Add logic to call bpf_setsockopt() and bpf_getsockopt() from setsockopt BPF
programs. An example use case is when the user sets the IPV6_TCLASS socket
option, we would also like to change the tcp-cc for that socket.
We don't have any use case for calling bpf_setsockopt() from supposedly read-
only sys_getsockopt(), so it is made available to BPF_CGROUP_SETSOCKOPT only
at this point.
Signed-off-by: Prankur Gupta <prankgup@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210817224221.3257826-2-prankgup@fb.com
Same as previous patch but for the keys. memdup_bpfptr is renamed
to kvmemdup_bpfptr (and converted to kvmalloc).
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818235216.1159202-2-sdf@google.com
Use kvmalloc/kvfree for temporary value when manipulating a map via
syscall. kmalloc might not be sufficient for percpu maps where the value
is big (and further multiplied by hundreds of CPUs).
Can be reproduced with netcnt test on qemu with "-smp 255".
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210818235216.1159202-1-sdf@google.com
The BPF interpreter as well as x86-64 BPF JIT were both in line by allowing
up to 33 tail calls (however odd that number may be!). Recently, this was
changed for the interpreter to reduce it down to 32 with the assumption that
this should have been the actual limit "which is in line with the behavior of
the x86 JITs" according to b61a28cf11 ("bpf: Fix off-by-one in tail call
count limiting").
Paul recently reported:
I'm a bit surprised by this because I had previously tested the tail call
limit of several JIT compilers and found it to be 33 (i.e., allowing chains
of up to 34 programs). I've just extended a test program I had to validate
this again on the x86-64 JIT, and found a limit of 33 tail calls again [1].
Also note we had previously changed the RISC-V and MIPS JITs to allow up to
33 tail calls [2, 3], for consistency with other JITs and with the interpreter.
We had decided to increase these two to 33 rather than decrease the other
JITs to 32 for backward compatibility, though that probably doesn't matter
much as I'd expect few people to actually use 33 tail calls.
[1] ae78874829
[2] 96bc4432f5 ("bpf, riscv: Limit to 33 tail calls")
[3] e49e6f6db0 ("bpf, mips: Limit to 33 tail calls")
Therefore, revert b61a28cf11 to re-align interpreter to limit a maximum of
33 tail calls. While it is unlikely to hit the limit for the vast majority,
programs in the wild could one way or another depend on this, so lets rather
be a bit more conservative, and lets align the small remainder of JITs to 33.
If needed in future, this limit could be slightly increased, but not decreased.
Fixes: b61a28cf11 ("bpf: Fix off-by-one in tail call count limiting")
Reported-by: Paul Chaignon <paul@cilium.io>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/CAO5pjwTWrC0_dzTbTHFPSqDwA56aVH+4KFGVqdq8=ASs0MqZGQ@mail.gmail.com
The variable allow is being initialized with a value that is never read, it
is being updated later on. The assignment is redundant and can be removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210817170842.495440-1-colin.king@canonical.com
Add ability for users to specify custom u64 value (bpf_cookie) when creating
BPF link for perf_event-backed BPF programs (kprobe/uprobe, perf_event,
tracepoints).
This is useful for cases when the same BPF program is used for attaching and
processing invocation of different tracepoints/kprobes/uprobes in a generic
fashion, but such that each invocation is distinguished from each other (e.g.,
BPF program can look up additional information associated with a specific
kernel function without having to rely on function IP lookups). This enables
new use cases to be implemented simply and efficiently that previously were
possible only through code generation (and thus multiple instances of almost
identical BPF program) or compilation at runtime (BCC-style) on target hosts
(even more expensive resource-wise). For uprobes it is not even possible in
some cases to know function IP before hand (e.g., when attaching to shared
library without PID filtering, in which case base load address is not known
for a library).
This is done by storing u64 bpf_cookie in struct bpf_prog_array_item,
corresponding to each attached and run BPF program. Given cgroup BPF programs
already use two 8-byte pointers for their needs and cgroup BPF programs don't
have (yet?) support for bpf_cookie, reuse that space through union of
cgroup_storage and new bpf_cookie field.
Make it available to kprobe/tracepoint BPF programs through bpf_trace_run_ctx.
This is set by BPF_PROG_RUN_ARRAY, used by kprobe/uprobe/tracepoint BPF
program execution code, which luckily is now also split from
BPF_PROG_RUN_ARRAY_CG. This run context will be utilized by a new BPF helper
giving access to this user-provided cookie value from inside a BPF program.
Generic perf_event BPF programs will access this value from perf_event itself
through passed in BPF program context.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-6-andrii@kernel.org
Introduce a new type of BPF link - BPF perf link. This brings perf_event-based
BPF program attachments (perf_event, tracepoints, kprobes, and uprobes) into
the common BPF link infrastructure, allowing to list all active perf_event
based attachments, auto-detaching BPF program from perf_event when link's FD
is closed, get generic BPF link fdinfo/get_info functionality.
BPF_LINK_CREATE command expects perf_event's FD as target_fd. No extra flags
are currently supported.
Force-detaching and atomic BPF program updates are not yet implemented, but
with perf_event-based BPF links we now have common framework for this without
the need to extend ioctl()-based perf_event interface.
One interesting consideration is a new value for bpf_attach_type, which
BPF_LINK_CREATE command expects. Generally, it's either 1-to-1 mapping from
bpf_attach_type to bpf_prog_type, or many-to-1 mapping from a subset of
bpf_attach_types to one bpf_prog_type (e.g., see BPF_PROG_TYPE_SK_SKB or
BPF_PROG_TYPE_CGROUP_SOCK). In this case, though, we have three different
program types (KPROBE, TRACEPOINT, PERF_EVENT) using the same perf_event-based
mechanism, so it's many bpf_prog_types to one bpf_attach_type. I chose to
define a single BPF_PERF_EVENT attach type for all of them and adjust
link_create()'s logic for checking correspondence between attach type and
program type.
The alternative would be to define three new attach types (e.g., BPF_KPROBE,
BPF_TRACEPOINT, and BPF_PERF_EVENT), but that seemed like unnecessary overkill
and BPF_KPROBE will cause naming conflicts with BPF_KPROBE() macro, defined by
libbpf. I chose to not do this to avoid unnecessary proliferation of
bpf_attach_type enum values and not have to deal with naming conflicts.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lore.kernel.org/bpf/20210815070609.987780-5-andrii@kernel.org
Similar to BPF_PROG_RUN, turn BPF_PROG_RUN_ARRAY macros into proper functions
with all the same readability and maintainability benefits. Making them into
functions required shuffling around bpf_set_run_ctx/bpf_reset_run_ctx
functions. Also, explicitly specifying the type of the BPF prog run callback
required adjusting __bpf_prog_run_save_cb() to accept const void *, casted
internally to const struct sk_buff.
Further, split out a cgroup-specific BPF_PROG_RUN_ARRAY_CG and
BPF_PROG_RUN_ARRAY_CG_FLAGS from the more generic BPF_PROG_RUN_ARRAY due to
the differences in bpf_run_ctx used for those two different use cases.
I think BPF_PROG_RUN_ARRAY_CG would benefit from further refactoring to accept
struct cgroup and enum bpf_attach_type instead of bpf_prog_array, fetching
cgrp->bpf.effective[type] and RCU-dereferencing it internally. But that
required including include/linux/cgroup-defs.h, which I wasn't sure is ok with
everyone.
The remaining generic BPF_PROG_RUN_ARRAY function will be extended to
pass-through user-provided context value in the next patch.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-3-andrii@kernel.org
Turn BPF_PROG_RUN into a proper always inlined function. No functional and
performance changes are intended, but it makes it much easier to understand
what's going on with how BPF programs are actually get executed. It's more
obvious what types and callbacks are expected. Also extra () around input
parameters can be dropped, as well as `__` variable prefixes intended to avoid
naming collisions, which makes the code simpler to read and write.
This refactoring also highlighted one extra issue. BPF_PROG_RUN is both
a macro and an enum value (BPF_PROG_RUN == BPF_PROG_TEST_RUN). Turning
BPF_PROG_RUN into a function causes naming conflict compilation error. So
rename BPF_PROG_RUN into lower-case bpf_prog_run(), similar to
bpf_prog_run_xdp(), bpf_prog_run_pin_on_cpu(), etc. All existing callers of
BPF_PROG_RUN, the macro, are switched to bpf_prog_run() explicitly.
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210815070609.987780-2-andrii@kernel.org
/proc/net/unix uses "%c" to print a single-byte character to escape '\0' in
the name of the abstract UNIX domain socket. The following selftest uses
it, so this patch adds support for "%c". Note that it does not support
wide character ("%lc" and "%llc") for simplicity.
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210814015718.42704-3-kuniyu@amazon.co.jp
This is similar to existing BPF_PROG_TYPE_CGROUP_SOCK
and BPF_PROG_TYPE_CGROUP_SOCK_ADDR.
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210813230530.333779-2-sdf@google.com
"access skb fields ok" verifier test fails on s390 with the "verifier
bug. zext_dst is set, but no reg is defined" message. The first insns
of the test prog are ...
0: 61 01 00 00 00 00 00 00 ldxw %r0,[%r1+0]
8: 35 00 00 01 00 00 00 00 jge %r0,0,1
10: 61 01 00 08 00 00 00 00 ldxw %r0,[%r1+8]
... and the 3rd one is dead (this does not look intentional to me, but
this is a separate topic).
sanitize_dead_code() converts dead insns into "ja -1", but keeps
zext_dst. When opt_subreg_zext_lo32_rnd_hi32() tries to parse such
an insn, it sees this discrepancy and bails. This problem can be seen
only with JITs whose bpf_jit_needs_zext() returns true.
Fix by clearning dead insns' zext_dst.
The commits that contributed to this problem are:
1. 5aa5bd14c5 ("bpf: add initial suite for selftests"), which
introduced the test with the dead code.
2. 5327ed3d44 ("bpf: verifier: mark verified-insn with
sub-register zext flag"), which introduced the zext_dst flag.
3. 83a2881903 ("bpf: Account for BPF_FETCH in
insn_has_def32()"), which introduced the sanity check.
4. 9183671af6 ("bpf: Fix leakage under speculation on
mispredicted branches"), which bisect points to.
It's best to fix this on stable branches that contain the second one,
since that's the point where the inconsistency was introduced.
Fixes: 5327ed3d44 ("bpf: verifier: mark verified-insn with sub-register zext flag")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210812151811.184086-2-iii@linux.ibm.com
Currently, if bpf_get_current_cgroup_id() or
bpf_get_current_ancestor_cgroup_id() helper is
called with sleepable programs e.g., sleepable
fentry/fmod_ret/fexit/lsm programs, a rcu warning
may appear. For example, if I added the following
hack to test_progs/test_lsm sleepable fentry program
test_sys_setdomainname:
--- a/tools/testing/selftests/bpf/progs/lsm.c
+++ b/tools/testing/selftests/bpf/progs/lsm.c
@@ -168,6 +168,10 @@ int BPF_PROG(test_sys_setdomainname, struct pt_regs *regs)
int buf = 0;
long ret;
+ __u64 cg_id = bpf_get_current_cgroup_id();
+ if (cg_id == 1000)
+ copy_test++;
+
ret = bpf_copy_from_user(&buf, sizeof(buf), ptr);
if (len == -2 && ret == 0 && buf == 1234)
copy_test++;
I will hit the following rcu warning:
include/linux/cgroup.h:481 suspicious rcu_dereference_check() usage!
other info that might help us debug this:
rcu_scheduler_active = 2, debug_locks = 1
1 lock held by test_progs/260:
#0: ffffffffa5173360 (rcu_read_lock_trace){....}-{0:0}, at: __bpf_prog_enter_sleepable+0x0/0xa0
stack backtrace:
CPU: 1 PID: 260 Comm: test_progs Tainted: G O 5.14.0-rc2+ #176
Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS rel-1.14.0-0-g155821a1990b-prebuilt.qemu.org 04/01/2014
Call Trace:
dump_stack_lvl+0x56/0x7b
bpf_get_current_cgroup_id+0x9c/0xb1
bpf_prog_a29888d1c6706e09_test_sys_setdomainname+0x3e/0x89c
bpf_trampoline_6442469132_0+0x2d/0x1000
__x64_sys_setdomainname+0x5/0x110
do_syscall_64+0x3a/0x80
entry_SYSCALL_64_after_hwframe+0x44/0xae
I can get similar warning using bpf_get_current_ancestor_cgroup_id() helper.
syzbot reported a similar issue in [1] for syscall program. Helper
bpf_get_current_cgroup_id() or bpf_get_current_ancestor_cgroup_id()
has the following callchain:
task_dfl_cgroup
task_css_set
task_css_set_check
and we have
#define task_css_set_check(task, __c) \
rcu_dereference_check((task)->cgroups, \
lockdep_is_held(&cgroup_mutex) || \
lockdep_is_held(&css_set_lock) || \
((task)->flags & PF_EXITING) || (__c))
Since cgroup_mutex/css_set_lock is not held and the task
is not existing and rcu read_lock is not held, a warning
will be issued. Note that bpf sleepable program is protected by
rcu_read_lock_trace().
The above sleepable bpf programs are already protected
by migrate_disable(). Adding rcu_read_lock() in these
two helpers will silence the above warning.
I marked the patch fixing 95b861a793
("bpf: Allow bpf_get_current_ancestor_cgroup_id for tracing")
which added bpf_get_current_ancestor_cgroup_id() to tracing programs
in 5.14. I think backporting 5.14 is probably good enough as sleepable
progrems are not widely used.
This patch should fix [1] as well since syscall program is a sleepable
program protected with migrate_disable().
[1] https://lore.kernel.org/bpf/0000000000006d5cab05c7d9bb87@google.com/
Fixes: 95b861a793 ("bpf: Allow bpf_get_current_ancestor_cgroup_id for tracing")
Reported-by: syzbot+7ee5c2c09c284495371f@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210810230537.2864668-1-yhs@fb.com
Fix kernel-doc warnings in kernel/bpf/core.c (found by scripts/kernel-doc
and W=1 builds). That is, correct a function name in a comment and add
return descriptions for 2 functions.
Fixes these kernel-doc warnings:
kernel/bpf/core.c:1372: warning: expecting prototype for __bpf_prog_run(). Prototype was for ___bpf_prog_run() instead
kernel/bpf/core.c:1372: warning: No description found for return value of '___bpf_prog_run'
kernel/bpf/core.c:1883: warning: No description found for return value of 'bpf_prog_select_runtime'
Signed-off-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210809215229.7556-1-rdunlap@infradead.org
Commit b910eaaaa4 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage()
helper") fixed a bug for bpf_get_local_storage() helper so different tasks
won't mess up with each other's percpu local storage.
The percpu data contains 8 slots so it can hold up to 8 contexts (same or
different tasks), for 8 different program runs, at the same time. This in
general is sufficient. But our internal testing showed the following warning
multiple times:
[...]
warning: WARNING: CPU: 13 PID: 41661 at include/linux/bpf-cgroup.h:193
__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
RIP: 0010:__cgroup_bpf_run_filter_sock_ops+0x13e/0x180
<IRQ>
tcp_call_bpf.constprop.99+0x93/0xc0
tcp_conn_request+0x41e/0xa50
? tcp_rcv_state_process+0x203/0xe00
tcp_rcv_state_process+0x203/0xe00
? sk_filter_trim_cap+0xbc/0x210
? tcp_v6_inbound_md5_hash.constprop.41+0x44/0x160
tcp_v6_do_rcv+0x181/0x3e0
tcp_v6_rcv+0xc65/0xcb0
ip6_protocol_deliver_rcu+0xbd/0x450
ip6_input_finish+0x11/0x20
ip6_input+0xb5/0xc0
ip6_sublist_rcv_finish+0x37/0x50
ip6_sublist_rcv+0x1dc/0x270
ipv6_list_rcv+0x113/0x140
__netif_receive_skb_list_core+0x1a0/0x210
netif_receive_skb_list_internal+0x186/0x2a0
gro_normal_list.part.170+0x19/0x40
napi_complete_done+0x65/0x150
mlx5e_napi_poll+0x1ae/0x680
__napi_poll+0x25/0x120
net_rx_action+0x11e/0x280
__do_softirq+0xbb/0x271
irq_exit_rcu+0x97/0xa0
common_interrupt+0x7f/0xa0
</IRQ>
asm_common_interrupt+0x1e/0x40
RIP: 0010:bpf_prog_1835a9241238291a_tw_egress+0x5/0xbac
? __cgroup_bpf_run_filter_skb+0x378/0x4e0
? do_softirq+0x34/0x70
? ip6_finish_output2+0x266/0x590
? ip6_finish_output+0x66/0xa0
? ip6_output+0x6c/0x130
? ip6_xmit+0x279/0x550
? ip6_dst_check+0x61/0xd0
[...]
Using drgn [0] to dump the percpu buffer contents showed that on this CPU
slot 0 is still available, but slots 1-7 are occupied and those tasks in
slots 1-7 mostly don't exist any more. So we might have issues in
bpf_cgroup_storage_unset().
Further debugging confirmed that there is a bug in bpf_cgroup_storage_unset().
Currently, it tries to unset "current" slot with searching from the start.
So the following sequence is possible:
1. A task is running and claims slot 0
2. Running BPF program is done, and it checked slot 0 has the "task"
and ready to reset it to NULL (not yet).
3. An interrupt happens, another BPF program runs and it claims slot 1
with the *same* task.
4. The unset() in interrupt context releases slot 0 since it matches "task".
5. Interrupt is done, the task in process context reset slot 0.
At the end, slot 1 is not reset and the same process can continue to occupy
slots 2-7 and finally, when the above step 1-5 is repeated again, step 3 BPF
program won't be able to claim an empty slot and a warning will be issued.
To fix the issue, for unset() function, we should traverse from the last slot
to the first. This way, the above issue can be avoided.
The same reverse traversal should also be done in bpf_get_local_storage() helper
itself. Otherwise, incorrect local storage may be returned to BPF program.
[0] https://github.com/osandov/drgn
Fixes: b910eaaaa4 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper")
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210810010413.1976277-1-yhs@fb.com
Rename LOCKDOWN_BPF_READ into LOCKDOWN_BPF_READ_KERNEL so we have naming
more consistent with a LOCKDOWN_BPF_WRITE_USER option that we are adding.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
In __htab_map_lookup_and_delete_batch(), hash buckets are iterated
over to count the number of elements in each bucket (bucket_size).
If bucket_size is large enough, the multiplication to calculate
kvmalloc() size could overflow, resulting in out-of-bounds write
as reported by KASAN:
[...]
[ 104.986052] BUG: KASAN: vmalloc-out-of-bounds in __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.986489] Write of size 4194224 at addr ffffc9010503be70 by task crash/112
[ 104.986889]
[ 104.987193] CPU: 0 PID: 112 Comm: crash Not tainted 5.14.0-rc4 #13
[ 104.987552] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1.1 04/01/2014
[ 104.988104] Call Trace:
[ 104.988410] dump_stack_lvl+0x34/0x44
[ 104.988706] print_address_description.constprop.0+0x21/0x140
[ 104.988991] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989327] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.989622] kasan_report.cold+0x7f/0x11b
[ 104.989881] ? __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990239] kasan_check_range+0x17c/0x1e0
[ 104.990467] memcpy+0x39/0x60
[ 104.990670] __htab_map_lookup_and_delete_batch+0x5ce/0xb60
[ 104.990982] ? __wake_up_common+0x4d/0x230
[ 104.991256] ? htab_of_map_free+0x130/0x130
[ 104.991541] bpf_map_do_batch+0x1fb/0x220
[...]
In hashtable, if the elements' keys have the same jhash() value, the
elements will be put into the same bucket. By putting a lot of elements
into a single bucket, the value of bucket_size can be increased to
trigger the integer overflow.
Triggering the overflow is possible for both callers with CAP_SYS_ADMIN
and callers without CAP_SYS_ADMIN.
It will be trivial for a caller with CAP_SYS_ADMIN to intentionally
reach this overflow by enabling BPF_F_ZERO_SEED. As this flag will set
the random seed passed to jhash() to 0, it will be easy for the caller
to prepare keys which will be hashed into the same value, and thus put
all the elements into the same bucket.
If the caller does not have CAP_SYS_ADMIN, BPF_F_ZERO_SEED cannot be
used. However, it will be still technically possible to trigger the
overflow, by guessing the random seed value passed to jhash() (32bit)
and repeating the attempt to trigger the overflow. In this case,
the probability to trigger the overflow will be low and will take
a very long time.
Fix the integer overflow by calling kvmalloc_array() instead of
kvmalloc() to allocate memory.
Fixes: 057996380a ("bpf: Add batch ops to all htab bpf map")
Signed-off-by: Tatsuhiko Yasumatsu <th.yasumatsu@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210806150419.109658-1-th.yasumatsu@gmail.com
Before, the interpreter allowed up to MAX_TAIL_CALL_CNT + 1 tail calls.
Now precisely MAX_TAIL_CALL_CNT is allowed, which is in line with the
behavior of the x86 JITs.
Signed-off-by: Johan Almbladh <johan.almbladh@anyfinetworks.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210728164741.350370-1-johan.almbladh@anyfinetworks.com
Andrii Nakryiko says:
====================
bpf-next 2021-07-30
We've added 64 non-merge commits during the last 15 day(s) which contain
a total of 83 files changed, 5027 insertions(+), 1808 deletions(-).
The main changes are:
1) BTF-guided binary data dumping libbpf API, from Alan.
2) Internal factoring out of libbpf CO-RE relocation logic, from Alexei.
3) Ambient BPF run context and cgroup storage cleanup, from Andrii.
4) Few small API additions for libbpf 1.0 effort, from Evgeniy and Hengqi.
5) bpf_program__attach_kprobe_opts() fixes in libbpf, from Jiri.
6) bpf_{get,set}sockopt() support in BPF iterators, from Martin.
7) BPF map pinning improvements in libbpf, from Martynas.
8) Improved module BTF support in libbpf and bpftool, from Quentin.
9) Bpftool cleanups and documentation improvements, from Quentin.
10) Libbpf improvements for supporting CO-RE on old kernels, from Shuyi.
11) Increased maximum cgroup storage size, from Stanislav.
12) Small fixes and improvements to BPF tests and samples, from various folks.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf-next: (64 commits)
tools: bpftool: Complete metrics list in "bpftool prog profile" doc
tools: bpftool: Document and add bash completion for -L, -B options
selftests/bpf: Update bpftool's consistency script for checking options
tools: bpftool: Update and synchronise option list in doc and help msg
tools: bpftool: Complete and synchronise attach or map types
selftests/bpf: Check consistency between bpftool source, doc, completion
tools: bpftool: Slightly ease bash completion updates
unix_bpf: Fix a potential deadlock in unix_dgram_bpf_recvmsg()
libbpf: Add btf__load_vmlinux_btf/btf__load_module_btf
tools: bpftool: Support dumping split BTF by id
libbpf: Add split BTF support for btf__load_from_kernel_by_id()
tools: Replace btf__get_from_id() with btf__load_from_kernel_by_id()
tools: Free BTF objects at various locations
libbpf: Rename btf__get_from_id() as btf__load_from_kernel_by_id()
libbpf: Rename btf__load() as btf__load_into_kernel()
libbpf: Return non-null error on failures in libbpf_find_prog_btf_id()
bpf: Emit better log message if bpf_iter ctx arg btf_id == 0
tools/resolve_btfids: Emit warnings and patch zero id for missing symbols
bpf: Increase supported cgroup storage value size
libbpf: Fix race when pinning maps in parallel
...
====================
Link: https://lore.kernel.org/r/20210730225606.1897330-1-andrii@kernel.org
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
To avoid kernel build failure due to some missing .BTF-ids referenced
functions/types, the patch ([1]) tries to fill btf_id 0 for
these types.
In bpf verifier, for percpu variable and helper returning btf_id cases,
verifier already emitted proper warning with something like
verbose(env, "Helper has invalid btf_id in R%d\n", regno);
verbose(env, "invalid return type %d of func %s#%d\n",
fn->ret_type, func_id_name(func_id), func_id);
But this is not the case for bpf_iter context arguments.
I hacked resolve_btfids to encode btf_id 0 for struct task_struct.
With `./test_progs -n 7/5`, I got,
0: (79) r2 = *(u64 *)(r1 +0)
func 'bpf_iter_task' arg0 has btf_id 29739 type STRUCT 'bpf_iter_meta'
; struct seq_file *seq = ctx->meta->seq;
1: (79) r6 = *(u64 *)(r2 +0)
; struct task_struct *task = ctx->task;
2: (79) r7 = *(u64 *)(r1 +8)
; if (task == (void *)0) {
3: (55) if r7 != 0x0 goto pc+11
...
; BPF_SEQ_PRINTF(seq, "%8d %8d\n", task->tgid, task->pid);
26: (61) r1 = *(u32 *)(r7 +1372)
Type '(anon)' is not a struct
Basically, verifier will return btf_id 0 for task_struct.
Later on, when the code tries to access task->tgid, the
verifier correctly complains the type is '(anon)' and it is
not a struct. Users still need to backtrace to find out
what is going on.
Let us catch the invalid btf_id 0 earlier
and provide better message indicating btf_id is wrong.
The new error message looks like below:
R1 type=ctx expected=fp
; struct seq_file *seq = ctx->meta->seq;
0: (79) r2 = *(u64 *)(r1 +0)
func 'bpf_iter_task' arg0 has btf_id 29739 type STRUCT 'bpf_iter_meta'
; struct seq_file *seq = ctx->meta->seq;
1: (79) r6 = *(u64 *)(r2 +0)
; struct task_struct *task = ctx->task;
2: (79) r7 = *(u64 *)(r1 +8)
invalid btf_id for context argument offset 8
invalid bpf_context access off=8 size=8
[1] https://lore.kernel.org/bpf/20210727132532.2473636-1-hengqi.chen@gmail.com/
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210728183025.1461750-1-yhs@fb.com
Spectre v4 gadgets make use of memory disambiguation, which is a set of
techniques that execute memory access instructions, that is, loads and
stores, out of program order; Intel's optimization manual, section 2.4.4.5:
A load instruction micro-op may depend on a preceding store. Many
microarchitectures block loads until all preceding store addresses are
known. The memory disambiguator predicts which loads will not depend on
any previous stores. When the disambiguator predicts that a load does
not have such a dependency, the load takes its data from the L1 data
cache. Eventually, the prediction is verified. If an actual conflict is
detected, the load and all succeeding instructions are re-executed.
af86ca4e30 ("bpf: Prevent memory disambiguation attack") tried to mitigate
this attack by sanitizing the memory locations through preemptive "fast"
(low latency) stores of zero prior to the actual "slow" (high latency) store
of a pointer value such that upon dependency misprediction the CPU then
speculatively executes the load of the pointer value and retrieves the zero
value instead of the attacker controlled scalar value previously stored at
that location, meaning, subsequent access in the speculative domain is then
redirected to the "zero page".
The sanitized preemptive store of zero prior to the actual "slow" store is
done through a simple ST instruction based on r10 (frame pointer) with
relative offset to the stack location that the verifier has been tracking
on the original used register for STX, which does not have to be r10. Thus,
there are no memory dependencies for this store, since it's only using r10
and immediate constant of zero; hence af86ca4e30 /assumed/ a low latency
operation.
However, a recent attack demonstrated that this mitigation is not sufficient
since the preemptive store of zero could also be turned into a "slow" store
and is thus bypassed as well:
[...]
// r2 = oob address (e.g. scalar)
// r7 = pointer to map value
31: (7b) *(u64 *)(r10 -16) = r2
// r9 will remain "fast" register, r10 will become "slow" register below
32: (bf) r9 = r10
// JIT maps BPF reg to x86 reg:
// r9 -> r15 (callee saved)
// r10 -> rbp
// train store forward prediction to break dependency link between both r9
// and r10 by evicting them from the predictor's LRU table.
33: (61) r0 = *(u32 *)(r7 +24576)
34: (63) *(u32 *)(r7 +29696) = r0
35: (61) r0 = *(u32 *)(r7 +24580)
36: (63) *(u32 *)(r7 +29700) = r0
37: (61) r0 = *(u32 *)(r7 +24584)
38: (63) *(u32 *)(r7 +29704) = r0
39: (61) r0 = *(u32 *)(r7 +24588)
40: (63) *(u32 *)(r7 +29708) = r0
[...]
543: (61) r0 = *(u32 *)(r7 +25596)
544: (63) *(u32 *)(r7 +30716) = r0
// prepare call to bpf_ringbuf_output() helper. the latter will cause rbp
// to spill to stack memory while r13/r14/r15 (all callee saved regs) remain
// in hardware registers. rbp becomes slow due to push/pop latency. below is
// disasm of bpf_ringbuf_output() helper for better visual context:
//
// ffffffff8117ee20: 41 54 push r12
// ffffffff8117ee22: 55 push rbp
// ffffffff8117ee23: 53 push rbx
// ffffffff8117ee24: 48 f7 c1 fc ff ff ff test rcx,0xfffffffffffffffc
// ffffffff8117ee2b: 0f 85 af 00 00 00 jne ffffffff8117eee0 <-- jump taken
// [...]
// ffffffff8117eee0: 49 c7 c4 ea ff ff ff mov r12,0xffffffffffffffea
// ffffffff8117eee7: 5b pop rbx
// ffffffff8117eee8: 5d pop rbp
// ffffffff8117eee9: 4c 89 e0 mov rax,r12
// ffffffff8117eeec: 41 5c pop r12
// ffffffff8117eeee: c3 ret
545: (18) r1 = map[id:4]
547: (bf) r2 = r7
548: (b7) r3 = 0
549: (b7) r4 = 4
550: (85) call bpf_ringbuf_output#194288
// instruction 551 inserted by verifier \
551: (7a) *(u64 *)(r10 -16) = 0 | /both/ are now slow stores here
// storing map value pointer r7 at fp-16 | since value of r10 is "slow".
552: (7b) *(u64 *)(r10 -16) = r7 /
// following "fast" read to the same memory location, but due to dependency
// misprediction it will speculatively execute before insn 551/552 completes.
553: (79) r2 = *(u64 *)(r9 -16)
// in speculative domain contains attacker controlled r2. in non-speculative
// domain this contains r7, and thus accesses r7 +0 below.
554: (71) r3 = *(u8 *)(r2 +0)
// leak r3
As can be seen, the current speculative store bypass mitigation which the
verifier inserts at line 551 is insufficient since /both/, the write of
the zero sanitation as well as the map value pointer are a high latency
instruction due to prior memory access via push/pop of r10 (rbp) in contrast
to the low latency read in line 553 as r9 (r15) which stays in hardware
registers. Thus, architecturally, fp-16 is r7, however, microarchitecturally,
fp-16 can still be r2.
Initial thoughts to address this issue was to track spilled pointer loads
from stack and enforce their load via LDX through r10 as well so that /both/
the preemptive store of zero /as well as/ the load use the /same/ register
such that a dependency is created between the store and load. However, this
option is not sufficient either since it can be bypassed as well under
speculation. An updated attack with pointer spill/fills now _all_ based on
r10 would look as follows:
[...]
// r2 = oob address (e.g. scalar)
// r7 = pointer to map value
[...]
// longer store forward prediction training sequence than before.
2062: (61) r0 = *(u32 *)(r7 +25588)
2063: (63) *(u32 *)(r7 +30708) = r0
2064: (61) r0 = *(u32 *)(r7 +25592)
2065: (63) *(u32 *)(r7 +30712) = r0
2066: (61) r0 = *(u32 *)(r7 +25596)
2067: (63) *(u32 *)(r7 +30716) = r0
// store the speculative load address (scalar) this time after the store
// forward prediction training.
2068: (7b) *(u64 *)(r10 -16) = r2
// preoccupy the CPU store port by running sequence of dummy stores.
2069: (63) *(u32 *)(r7 +29696) = r0
2070: (63) *(u32 *)(r7 +29700) = r0
2071: (63) *(u32 *)(r7 +29704) = r0
2072: (63) *(u32 *)(r7 +29708) = r0
2073: (63) *(u32 *)(r7 +29712) = r0
2074: (63) *(u32 *)(r7 +29716) = r0
2075: (63) *(u32 *)(r7 +29720) = r0
2076: (63) *(u32 *)(r7 +29724) = r0
2077: (63) *(u32 *)(r7 +29728) = r0
2078: (63) *(u32 *)(r7 +29732) = r0
2079: (63) *(u32 *)(r7 +29736) = r0
2080: (63) *(u32 *)(r7 +29740) = r0
2081: (63) *(u32 *)(r7 +29744) = r0
2082: (63) *(u32 *)(r7 +29748) = r0
2083: (63) *(u32 *)(r7 +29752) = r0
2084: (63) *(u32 *)(r7 +29756) = r0
2085: (63) *(u32 *)(r7 +29760) = r0
2086: (63) *(u32 *)(r7 +29764) = r0
2087: (63) *(u32 *)(r7 +29768) = r0
2088: (63) *(u32 *)(r7 +29772) = r0
2089: (63) *(u32 *)(r7 +29776) = r0
2090: (63) *(u32 *)(r7 +29780) = r0
2091: (63) *(u32 *)(r7 +29784) = r0
2092: (63) *(u32 *)(r7 +29788) = r0
2093: (63) *(u32 *)(r7 +29792) = r0
2094: (63) *(u32 *)(r7 +29796) = r0
2095: (63) *(u32 *)(r7 +29800) = r0
2096: (63) *(u32 *)(r7 +29804) = r0
2097: (63) *(u32 *)(r7 +29808) = r0
2098: (63) *(u32 *)(r7 +29812) = r0
// overwrite scalar with dummy pointer; same as before, also including the
// sanitation store with 0 from the current mitigation by the verifier.
2099: (7a) *(u64 *)(r10 -16) = 0 | /both/ are now slow stores here
2100: (7b) *(u64 *)(r10 -16) = r7 | since store unit is still busy.
// load from stack intended to bypass stores.
2101: (79) r2 = *(u64 *)(r10 -16)
2102: (71) r3 = *(u8 *)(r2 +0)
// leak r3
[...]
Looking at the CPU microarchitecture, the scheduler might issue loads (such
as seen in line 2101) before stores (line 2099,2100) because the load execution
units become available while the store execution unit is still busy with the
sequence of dummy stores (line 2069-2098). And so the load may use the prior
stored scalar from r2 at address r10 -16 for speculation. The updated attack
may work less reliable on CPU microarchitectures where loads and stores share
execution resources.
This concludes that the sanitizing with zero stores from af86ca4e30 ("bpf:
Prevent memory disambiguation attack") is insufficient. Moreover, the detection
of stack reuse from af86ca4e30 where previously data (STACK_MISC) has been
written to a given stack slot where a pointer value is now to be stored does
not have sufficient coverage as precondition for the mitigation either; for
several reasons outlined as follows:
1) Stack content from prior program runs could still be preserved and is
therefore not "random", best example is to split a speculative store
bypass attack between tail calls, program A would prepare and store the
oob address at a given stack slot and then tail call into program B which
does the "slow" store of a pointer to the stack with subsequent "fast"
read. From program B PoV such stack slot type is STACK_INVALID, and
therefore also must be subject to mitigation.
2) The STACK_SPILL must not be coupled to register_is_const(&stack->spilled_ptr)
condition, for example, the previous content of that memory location could
also be a pointer to map or map value. Without the fix, a speculative
store bypass is not mitigated in such precondition and can then lead to
a type confusion in the speculative domain leaking kernel memory near
these pointer types.
While brainstorming on various alternative mitigation possibilities, we also
stumbled upon a retrospective from Chrome developers [0]:
[...] For variant 4, we implemented a mitigation to zero the unused memory
of the heap prior to allocation, which cost about 1% when done concurrently
and 4% for scavenging. Variant 4 defeats everything we could think of. We
explored more mitigations for variant 4 but the threat proved to be more
pervasive and dangerous than we anticipated. For example, stack slots used
by the register allocator in the optimizing compiler could be subject to
type confusion, leading to pointer crafting. Mitigating type confusion for
stack slots alone would have required a complete redesign of the backend of
the optimizing compiler, perhaps man years of work, without a guarantee of
completeness. [...]
From BPF side, the problem space is reduced, however, options are rather
limited. One idea that has been explored was to xor-obfuscate pointer spills
to the BPF stack:
[...]
// preoccupy the CPU store port by running sequence of dummy stores.
[...]
2106: (63) *(u32 *)(r7 +29796) = r0
2107: (63) *(u32 *)(r7 +29800) = r0
2108: (63) *(u32 *)(r7 +29804) = r0
2109: (63) *(u32 *)(r7 +29808) = r0
2110: (63) *(u32 *)(r7 +29812) = r0
// overwrite scalar with dummy pointer; xored with random 'secret' value
// of 943576462 before store ...
2111: (b4) w11 = 943576462
2112: (af) r11 ^= r7
2113: (7b) *(u64 *)(r10 -16) = r11
2114: (79) r11 = *(u64 *)(r10 -16)
2115: (b4) w2 = 943576462
2116: (af) r2 ^= r11
// ... and restored with the same 'secret' value with the help of AX reg.
2117: (71) r3 = *(u8 *)(r2 +0)
[...]
While the above would not prevent speculation, it would make data leakage
infeasible by directing it to random locations. In order to be effective
and prevent type confusion under speculation, such random secret would have
to be regenerated for each store. The additional complexity involved for a
tracking mechanism that prevents jumps such that restoring spilled pointers
would not get corrupted is not worth the gain for unprivileged. Hence, the
fix in here eventually opted for emitting a non-public BPF_ST | BPF_NOSPEC
instruction which the x86 JIT translates into a lfence opcode. Inserting the
latter in between the store and load instruction is one of the mitigations
options [1]. The x86 instruction manual notes:
[...] An LFENCE that follows an instruction that stores to memory might
complete before the data being stored have become globally visible. [...]
The latter meaning that the preceding store instruction finished execution
and the store is at minimum guaranteed to be in the CPU's store queue, but
it's not guaranteed to be in that CPU's L1 cache at that point (globally
visible). The latter would only be guaranteed via sfence. So the load which
is guaranteed to execute after the lfence for that local CPU would have to
rely on store-to-load forwarding. [2], in section 2.3 on store buffers says:
[...] For every store operation that is added to the ROB, an entry is
allocated in the store buffer. This entry requires both the virtual and
physical address of the target. Only if there is no free entry in the store
buffer, the frontend stalls until there is an empty slot available in the
store buffer again. Otherwise, the CPU can immediately continue adding
subsequent instructions to the ROB and execute them out of order. On Intel
CPUs, the store buffer has up to 56 entries. [...]
One small upside on the fix is that it lifts constraints from af86ca4e30
where the sanitize_stack_off relative to r10 must be the same when coming
from different paths. The BPF_ST | BPF_NOSPEC gets emitted after a BPF_STX
or BPF_ST instruction. This happens either when we store a pointer or data
value to the BPF stack for the first time, or upon later pointer spills.
The former needs to be enforced since otherwise stale stack data could be
leaked under speculation as outlined earlier. For non-x86 JITs the BPF_ST |
BPF_NOSPEC mapping is currently optimized away, but others could emit a
speculation barrier as well if necessary. For real-world unprivileged
programs e.g. generated by LLVM, pointer spill/fill is only generated upon
register pressure and LLVM only tries to do that for pointers which are not
used often. The program main impact will be the initial BPF_ST | BPF_NOSPEC
sanitation for the STACK_INVALID case when the first write to a stack slot
occurs e.g. upon map lookup. In future we might refine ways to mitigate
the latter cost.
[0] https://arxiv.org/pdf/1902.05178.pdf
[1] https://msrc-blog.microsoft.com/2018/05/21/analysis-and-mitigation-of-speculative-store-bypass-cve-2018-3639/
[2] https://arxiv.org/pdf/1905.05725.pdf
Fixes: af86ca4e30 ("bpf: Prevent memory disambiguation attack")
Fixes: f7cf25b202 ("bpf: track spill/fill of constants")
Co-developed-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Benedict Schlueter <benedict.schlueter@rub.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
In case of JITs, each of the JIT backends compiles the BPF nospec instruction
/either/ to a machine instruction which emits a speculation barrier /or/ to
/no/ machine instruction in case the underlying architecture is not affected
by Speculative Store Bypass or has different mitigations in place already.
This covers both x86 and (implicitly) arm64: In case of x86, we use 'lfence'
instruction for mitigation. In case of arm64, we rely on the firmware mitigation
as controlled via the ssbd kernel parameter. Whenever the mitigation is enabled,
it works for all of the kernel code with no need to provide any additional
instructions here (hence only comment in arm64 JIT). Other archs can follow
as needed. The BPF nospec instruction is specifically targeting Spectre v4
since i) we don't use a serialization barrier for the Spectre v1 case, and
ii) mitigation instructions for v1 and v4 might be different on some archs.
The BPF nospec is required for a future commit, where the BPF verifier does
annotate intermediate BPF programs with speculation barriers.
Co-developed-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Benedict Schlueter <benedict.schlueter@rub.de>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Current max cgroup storage value size is 4k (PAGE_SIZE). The other local
storages accept up to 64k (BPF_LOCAL_STORAGE_MAX_VALUE_SIZE). Let's align
max cgroup value size with the other storages.
For percpu, the max is 32k (PCPU_MIN_UNIT_SIZE) because percpu
allocator is not happy about larger values.
netcnt test is extended to exercise those maximum values
(non-percpu max size is close to, but not real max).
v4:
* remove inner union (Andrii Nakryiko)
* keep net_cnt on the stack (Andrii Nakryiko)
v3:
* refine SIZEOF_BPF_LOCAL_STORAGE_ELEM comment (Yonghong Song)
* anonymous struct in percpu_net_cnt & net_cnt (Yonghong Song)
* reorder free (Yonghong Song)
v2:
* cap max_value_size instead of BUILD_BUG_ON (Martin KaFai Lau)
Signed-off-by: Stanislav Fomichev <sdf@google.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210727222335.4029096-1-sdf@google.com
This patch allows bpf tcp iter to call bpf_(get|set)sockopt.
To allow a specific bpf iter (tcp here) to call a set of helpers,
get_func_proto function pointer is added to bpf_iter_reg.
The bpf iter is a tracing prog which currently requires
CAP_PERFMON or CAP_SYS_ADMIN, so this patch does not
impose other capability checks for bpf_(get|set)sockopt.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210701200619.1036715-1-kafai@fb.com
The variable stype is being initialized with a value that is never
read, it is being updated later on. The assignment is redundant and
can be removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210721115630.109279-1-colin.king@canonical.com
b910eaaaa4 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage()
helper") fixed the problem with cgroup-local storage use in BPF by
pre-allocating per-CPU array of 8 cgroup storage pointers to accommodate
possible BPF program preemptions and nested executions.
While this seems to work good in practice, it introduces new and unnecessary
failure mode in which not all BPF programs might be executed if we fail to
find an unused slot for cgroup storage, however unlikely it is. It might also
not be so unlikely when/if we allow sleepable cgroup BPF programs in the
future.
Further, the way that cgroup storage is implemented as ambiently-available
property during entire BPF program execution is a convenient way to pass extra
information to BPF program and helpers without requiring user code to pass
around extra arguments explicitly. So it would be good to have a generic
solution that can allow implementing this without arbitrary restrictions.
Ideally, such solution would work for both preemptable and sleepable BPF
programs in exactly the same way.
This patch introduces such solution, bpf_run_ctx. It adds one pointer field
(bpf_ctx) to task_struct. This field is maintained by BPF_PROG_RUN family of
macros in such a way that it always stays valid throughout BPF program
execution. BPF program preemption is handled by remembering previous
current->bpf_ctx value locally while executing nested BPF program and
restoring old value after nested BPF program finishes. This is handled by two
helper functions, bpf_set_run_ctx() and bpf_reset_run_ctx(), which are
supposed to be used before and after BPF program runs, respectively.
Restoring old value of the pointer handles preemption, while bpf_run_ctx
pointer being a property of current task_struct naturally solves this problem
for sleepable BPF programs by "following" BPF program execution as it is
scheduled in and out of CPU. It would even allow CPU migration of BPF
programs, even though it's not currently allowed by BPF infra.
This patch cleans up cgroup local storage handling as a first application. The
design itself is generic, though, with bpf_run_ctx being an empty struct that
is supposed to be embedded into a specific struct for a given BPF program type
(bpf_cg_run_ctx in this case). Follow up patches are planned that will expand
this mechanism for other uses within tracing BPF programs.
To verify that this change doesn't revert the fix to the original cgroup
storage issue, I ran the same repro as in the original report ([0]) and didn't
get any problems. Replacing bpf_reset_run_ctx(old_run_ctx) with
bpf_reset_run_ctx(NULL) triggers the issue pretty quickly (so repro does work).
[0] https://lore.kernel.org/bpf/YEEvBUiJl2pJkxTd@krava/
Fixes: b910eaaaa4 ("bpf: Fix NULL pointer dereference in bpf_get_local_storage() helper")
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210712230615.3525979-1-andrii@kernel.org
In 7fedb63a83 ("bpf: Tighten speculative pointer arithmetic mask") we
narrowed the offset mask for unprivileged pointer arithmetic in order to
mitigate a corner case where in the speculative domain it is possible to
advance, for example, the map value pointer by up to value_size-1 out-of-
bounds in order to leak kernel memory via side-channel to user space.
The verifier's state pruning for scalars leaves one corner case open
where in the first verification path R_x holds an unknown scalar with an
aux->alu_limit of e.g. 7, and in a second verification path that same
register R_x, here denoted as R_x', holds an unknown scalar which has
tighter bounds and would thus satisfy range_within(R_x, R_x') as well as
tnum_in(R_x, R_x') for state pruning, yielding an aux->alu_limit of 3:
Given the second path fits the register constraints for pruning, the final
generated mask from aux->alu_limit will remain at 7. While technically
not wrong for the non-speculative domain, it would however be possible
to craft similar cases where the mask would be too wide as in 7fedb63a83.
One way to fix it is to detect the presence of unknown scalar map pointer
arithmetic and force a deeper search on unknown scalars to ensure that
we do not run into a masking mismatch.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Follow-up to fe9a5ca7e3 ("bpf: Do not mark insn as seen under speculative
path verification"). The sanitize_insn_aux_data() helper does not serve a
particular purpose in today's code. The original intention for the helper
was that if function-by-function verification fails, a given program would
be cleared from temporary insn_aux_data[], and then its verification would
be re-attempted in the context of the main program a second time.
However, a failure in do_check_subprogs() will skip do_check_main() and
propagate the error to the user instead, thus such situation can never occur.
Given its interaction is not compatible to the Spectre v1 mitigation (due to
comparing aux->seen with env->pass_cnt), just remove sanitize_insn_aux_data()
to avoid future bugs in this area.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-07-15
The following pull-request contains BPF updates for your *net-next* tree.
We've added 45 non-merge commits during the last 15 day(s) which contain
a total of 52 files changed, 3122 insertions(+), 384 deletions(-).
The main changes are:
1) Introduce bpf timers, from Alexei.
2) Add sockmap support for unix datagram socket, from Cong.
3) Fix potential memleak and UAF in the verifier, from He.
4) Add bpf_get_func_ip helper, from Jiri.
5) Improvements to generic XDP mode, from Kumar.
6) Support for passing xdp_md to XDP programs in bpf_prog_run, from Zvi.
===================
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently sock_map still has Kconfig dependency on CONFIG_INET,
but there is no actual functional dependency on it after we
introduce ->psock_update_sk_prot().
We have to extend it to CONFIG_NET now as we are going to
support AF_UNIX.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210704190252.11866-2-xiyou.wangcong@gmail.com
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_KPROBE programs,
so it's now possible to call bpf_get_func_ip from both kprobe and
kretprobe programs.
Taking the caller's address from 'struct kprobe::addr', which is
defined for both kprobe and kretprobe.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Masami Hiramatsu <mhiramat@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-5-jolsa@kernel.org
Adding bpf_get_func_ip helper for BPF_PROG_TYPE_TRACING programs,
specifically for all trampoline attach types.
The trampoline's caller IP address is stored in (ctx - 8) address.
so there's no reason to actually call the helper, but rather fixup
the call instruction and return [ctx - 8] value directly.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-4-jolsa@kernel.org
Enabling BPF_TRAMP_F_IP_ARG for trampolines that actually need it.
The BPF_TRAMP_F_IP_ARG adds extra 3 instructions to trampoline code
and is used only by programs with bpf_get_func_ip helper, which is
added in following patch and sets call_get_func_ip bit.
This patch ensures that BPF_TRAMP_F_IP_ARG flag is used only for
trampolines that have programs with call_get_func_ip set.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210714094400.396467-3-jolsa@kernel.org
Teach max stack depth checking algorithm about async callbacks
that don't increase bpf program stack size.
Also add sanity check that bpf_tail_call didn't sneak into async cb.
It's impossible, since PTR_TO_CTX is not available in async cb,
hence the program cannot contain bpf_tail_call(ctx,...);
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-10-alexei.starovoitov@gmail.com
bpf_for_each_map_elem() and bpf_timer_set_callback() helpers are relying on
PTR_TO_FUNC infra in the verifier to validate addresses to subprograms
and pass them into the helpers as function callbacks.
In case of bpf_for_each_map_elem() the callback is invoked synchronously
and the verifier treats it as a normal subprogram call by adding another
bpf_func_state and new frame in __check_func_call().
bpf_timer_set_callback() doesn't invoke the callback directly.
The subprogram will be called asynchronously from bpf_timer_cb().
Teach the verifier to validate such async callbacks as special kind
of jump by pushing verifier state into stack and let pop_stack() process it.
Special care needs to be taken during state pruning.
The call insn doing bpf_timer_set_callback has to be a prune_point.
Otherwise short timer callbacks might not have prune points in front of
bpf_timer_set_callback() which means is_state_visited() will be called
after this call insn is processed in __check_func_call(). Which means that
another async_cb state will be pushed to be walked later and the verifier
will eventually hit BPF_COMPLEXITY_LIMIT_JMP_SEQ limit.
Since push_async_cb() looks like another push_stack() branch the
infinite loop detection will trigger false positive. To recognize
this case mark such states as in_async_callback_fn.
To distinguish infinite loop in async callback vs the same callback called
with different arguments for different map and timer add async_entry_cnt
to bpf_func_state.
Enforce return zero from async callbacks.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-9-alexei.starovoitov@gmail.com
In the following bpf subprogram:
static int timer_cb(void *map, void *key, void *value)
{
bpf_timer_set_callback(.., timer_cb);
}
the 'timer_cb' is a pointer to a function.
ld_imm64 insn is used to carry this pointer.
bpf_pseudo_func() returns true for such ld_imm64 insn.
Unlike bpf_for_each_map_elem() the bpf_timer_set_callback() is asynchronous.
Relax control flow check to allow such "recursion" that is seen as an infinite
loop by check_cfg(). The distinction between bpf_for_each_map_elem() the
bpf_timer_set_callback() is done in the follow up patch.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-8-alexei.starovoitov@gmail.com
BTF is required for 'struct bpf_timer' to be recognized inside map value.
The bpf timers are supported inside inner maps.
Remember 'struct btf *' in inner_map_meta to make it available
to the verifier in the sequence:
struct bpf_map *inner_map = bpf_map_lookup_elem(&outer_map, ...);
if (inner_map)
timer = bpf_map_lookup_elem(&inner_map, ...);
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-7-alexei.starovoitov@gmail.com
bpf_timer_init() arguments are:
1. pointer to a timer (which is embedded in map element).
2. pointer to a map.
Make sure that pointer to a timer actually belongs to that map.
Use map_uid (which is unique id of inner map) to reject:
inner_map1 = bpf_map_lookup_elem(outer_map, key1)
inner_map2 = bpf_map_lookup_elem(outer_map, key2)
if (inner_map1 && inner_map2) {
timer = bpf_map_lookup_elem(inner_map1);
if (timer)
// mismatch would have been allowed
bpf_timer_init(timer, inner_map2);
}
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-6-alexei.starovoitov@gmail.com
Restrict bpf timers to array, hash (both preallocated and kmalloced), and
lru map types. The per-cpu maps with timers don't make sense, since 'struct
bpf_timer' is a part of map value. bpf timers in per-cpu maps would mean that
the number of timers depends on number of possible cpus and timers would not be
accessible from all cpus. lpm map support can be added in the future.
The timers in inner maps are supported.
The bpf_map_update/delete_elem() helpers and sys_bpf commands cancel and free
bpf_timer in a given map element.
Similar to 'struct bpf_spin_lock' BTF is required and it is used to validate
that map element indeed contains 'struct bpf_timer'.
Make check_and_init_map_value() init both bpf_spin_lock and bpf_timer when
map element data is reused in preallocated htab and lru maps.
Teach copy_map_value() to support both bpf_spin_lock and bpf_timer in a single
map element. There could be one of each, but not more than one. Due to 'one
bpf_timer in one element' restriction do not support timers in global data,
since global data is a map of single element, but from bpf program side it's
seen as many global variables and restriction of single global timer would be
odd. The sys_bpf map_freeze and sys_mmap syscalls are not allowed on maps with
timers, since user space could have corrupted mmap element and crashed the
kernel. The maps with timers cannot be readonly. Due to these restrictions
search for bpf_timer in datasec BTF in case it was placed in the global data to
report clear error.
The previous patch allowed 'struct bpf_timer' as a first field in a map
element only. Relax this restriction.
Refactor lru map to s/bpf_lru_push_free/htab_lru_push_free/ to cancel and free
the timer when lru map deletes an element as a part of it eviction algorithm.
Make sure that bpf program cannot access 'struct bpf_timer' via direct load/store.
The timer operation are done through helpers only.
This is similar to 'struct bpf_spin_lock'.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-5-alexei.starovoitov@gmail.com
Introduce 'struct bpf_timer { __u64 :64; __u64 :64; };' that can be embedded
in hash/array/lru maps as a regular field and helpers to operate on it:
// Initialize the timer.
// First 4 bits of 'flags' specify clockid.
// Only CLOCK_MONOTONIC, CLOCK_REALTIME, CLOCK_BOOTTIME are allowed.
long bpf_timer_init(struct bpf_timer *timer, struct bpf_map *map, int flags);
// Configure the timer to call 'callback_fn' static function.
long bpf_timer_set_callback(struct bpf_timer *timer, void *callback_fn);
// Arm the timer to expire 'nsec' nanoseconds from the current time.
long bpf_timer_start(struct bpf_timer *timer, u64 nsec, u64 flags);
// Cancel the timer and wait for callback_fn to finish if it was running.
long bpf_timer_cancel(struct bpf_timer *timer);
Here is how BPF program might look like:
struct map_elem {
int counter;
struct bpf_timer timer;
};
struct {
__uint(type, BPF_MAP_TYPE_HASH);
__uint(max_entries, 1000);
__type(key, int);
__type(value, struct map_elem);
} hmap SEC(".maps");
static int timer_cb(void *map, int *key, struct map_elem *val);
/* val points to particular map element that contains bpf_timer. */
SEC("fentry/bpf_fentry_test1")
int BPF_PROG(test1, int a)
{
struct map_elem *val;
int key = 0;
val = bpf_map_lookup_elem(&hmap, &key);
if (val) {
bpf_timer_init(&val->timer, &hmap, CLOCK_REALTIME);
bpf_timer_set_callback(&val->timer, timer_cb);
bpf_timer_start(&val->timer, 1000 /* call timer_cb2 in 1 usec */, 0);
}
}
This patch adds helper implementations that rely on hrtimers
to call bpf functions as timers expire.
The following patches add necessary safety checks.
Only programs with CAP_BPF are allowed to use bpf_timer.
The amount of timers used by the program is constrained by
the memcg recorded at map creation time.
The bpf_timer_init() helper needs explicit 'map' argument because inner maps
are dynamic and not known at load time. While the bpf_timer_set_callback() is
receiving hidden 'aux->prog' argument supplied by the verifier.
The prog pointer is needed to do refcnting of bpf program to make sure that
program doesn't get freed while the timer is armed. This approach relies on
"user refcnt" scheme used in prog_array that stores bpf programs for
bpf_tail_call. The bpf_timer_set_callback() will increment the prog refcnt which is
paired with bpf_timer_cancel() that will drop the prog refcnt. The
ops->map_release_uref is responsible for cancelling the timers and dropping
prog refcnt when user space reference to a map reaches zero.
This uref approach is done to make sure that Ctrl-C of user space process will
not leave timers running forever unless the user space explicitly pinned a map
that contained timers in bpffs.
bpf_timer_init() and bpf_timer_set_callback() will return -EPERM if map doesn't
have user references (is not held by open file descriptor from user space and
not pinned in bpffs).
The bpf_map_delete_elem() and bpf_map_update_elem() operations cancel
and free the timer if given map element had it allocated.
"bpftool map update" command can be used to cancel timers.
The 'struct bpf_timer' is explicitly __attribute__((aligned(8))) because
'__u64 :64' has 1 byte alignment of 8 byte padding.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-4-alexei.starovoitov@gmail.com
Move ____bpf_spin_lock/unlock into helpers to make it more clear
that quadruple underscore bpf_spin_lock/unlock are irqsave/restore variants.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-3-alexei.starovoitov@gmail.com
Currently bpf_prog_put() is called from the task context only.
With addition of bpf timers the timer related helpers will start calling
bpf_prog_put() from irq-saved region and in rare cases might drop
the refcnt to zero.
To address this case, first, convert bpf_prog_free_id() to be irq-save
(this is similar to bpf_map_free_id), and, second, defer non irq
appropriate calls into work queue.
For example:
bpf_audit_prog() is calling kmalloc and wake_up_interruptible,
bpf_prog_kallsyms_del_all()->bpf_ksym_del()->spin_unlock_bh().
They are not safe with irqs disabled.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210715005417.78572-2-alexei.starovoitov@gmail.com
In bpf_patch_insn_data(), we first use the bpf_patch_insn_single() to
insert new instructions, then use adjust_insn_aux_data() to adjust
insn_aux_data. If the old env->prog have no enough room for new inserted
instructions, we use bpf_prog_realloc to construct new_prog and free the
old env->prog.
There have two errors here. First, if adjust_insn_aux_data() return
ENOMEM, we should free the new_prog. Second, if adjust_insn_aux_data()
return ENOMEM, bpf_patch_insn_data() will return NULL, and env->prog has
been freed in bpf_prog_realloc, but we will use it in bpf_check().
So in this patch, we make the adjust_insn_aux_data() never fails. In
bpf_patch_insn_data(), we first pre-malloc memory for the new
insn_aux_data, then call bpf_patch_insn_single() to insert new
instructions, at last call adjust_insn_aux_data() to adjust
insn_aux_data.
Fixes: 8041902dae ("bpf: adjust insn_aux_data when patching insns")
Signed-off-by: He Fengqing <hefengqing@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210714101815.164322-1-hefengqing@huawei.com
During testing of f263a81451 ("bpf: Track subprog poke descriptors correctly
and fix use-after-free") under various failure conditions, for example, when
jit_subprogs() fails and tries to clean up the program to be run under the
interpreter, we ran into the following freeze:
[...]
#127/8 tailcall_bpf2bpf_3:FAIL
[...]
[ 92.041251] BUG: KASAN: slab-out-of-bounds in ___bpf_prog_run+0x1b9d/0x2e20
[ 92.042408] Read of size 8 at addr ffff88800da67f68 by task test_progs/682
[ 92.043707]
[ 92.044030] CPU: 1 PID: 682 Comm: test_progs Tainted: G O 5.13.0-53301-ge6c08cb33a30-dirty #87
[ 92.045542] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-1ubuntu1 04/01/2014
[ 92.046785] Call Trace:
[ 92.047171] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.047773] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.048389] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.049019] ? ktime_get+0x117/0x130
[...] // few hundred [similar] lines more
[ 92.659025] ? ktime_get+0x117/0x130
[ 92.659845] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.660738] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.661528] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.662378] ? print_usage_bug+0x50/0x50
[ 92.663221] ? print_usage_bug+0x50/0x50
[ 92.664077] ? bpf_ksym_find+0x9c/0xe0
[ 92.664887] ? ktime_get+0x117/0x130
[ 92.665624] ? kernel_text_address+0xf5/0x100
[ 92.666529] ? __kernel_text_address+0xe/0x30
[ 92.667725] ? unwind_get_return_address+0x2f/0x50
[ 92.668854] ? ___bpf_prog_run+0x15d4/0x2e20
[ 92.670185] ? ktime_get+0x117/0x130
[ 92.671130] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.672020] ? __bpf_prog_run_args32+0x8b/0xb0
[ 92.672860] ? __bpf_prog_run_args64+0xc0/0xc0
[ 92.675159] ? ktime_get+0x117/0x130
[ 92.677074] ? lock_is_held_type+0xd5/0x130
[ 92.678662] ? ___bpf_prog_run+0x15d4/0x2e20
[ 92.680046] ? ktime_get+0x117/0x130
[ 92.681285] ? __bpf_prog_run32+0x6b/0x90
[ 92.682601] ? __bpf_prog_run64+0x90/0x90
[ 92.683636] ? lock_downgrade+0x370/0x370
[ 92.684647] ? mark_held_locks+0x44/0x90
[ 92.685652] ? ktime_get+0x117/0x130
[ 92.686752] ? lockdep_hardirqs_on+0x79/0x100
[ 92.688004] ? ktime_get+0x117/0x130
[ 92.688573] ? __cant_migrate+0x2b/0x80
[ 92.689192] ? bpf_test_run+0x2f4/0x510
[ 92.689869] ? bpf_test_timer_continue+0x1c0/0x1c0
[ 92.690856] ? rcu_read_lock_bh_held+0x90/0x90
[ 92.691506] ? __kasan_slab_alloc+0x61/0x80
[ 92.692128] ? eth_type_trans+0x128/0x240
[ 92.692737] ? __build_skb+0x46/0x50
[ 92.693252] ? bpf_prog_test_run_skb+0x65e/0xc50
[ 92.693954] ? bpf_prog_test_run_raw_tp+0x2d0/0x2d0
[ 92.694639] ? __fget_light+0xa1/0x100
[ 92.695162] ? bpf_prog_inc+0x23/0x30
[ 92.695685] ? __sys_bpf+0xb40/0x2c80
[ 92.696324] ? bpf_link_get_from_fd+0x90/0x90
[ 92.697150] ? mark_held_locks+0x24/0x90
[ 92.698007] ? lockdep_hardirqs_on_prepare+0x124/0x220
[ 92.699045] ? finish_task_switch+0xe6/0x370
[ 92.700072] ? lockdep_hardirqs_on+0x79/0x100
[ 92.701233] ? finish_task_switch+0x11d/0x370
[ 92.702264] ? __switch_to+0x2c0/0x740
[ 92.703148] ? mark_held_locks+0x24/0x90
[ 92.704155] ? __x64_sys_bpf+0x45/0x50
[ 92.705146] ? do_syscall_64+0x35/0x80
[ 92.706953] ? entry_SYSCALL_64_after_hwframe+0x44/0xae
[...]
Turns out that the program rejection from e411901c0b ("bpf: allow for tailcalls
in BPF subprograms for x64 JIT") is buggy since env->prog->aux->tail_call_reachable
is never true. Commit ebf7d1f508 ("bpf, x64: rework pro/epilogue and tailcall
handling in JIT") added a tracker into check_max_stack_depth() which propagates
the tail_call_reachable condition throughout the subprograms. This info is then
assigned to the subprogram's func[i]->aux->tail_call_reachable. However, in the
case of the rejection check upon JIT failure, env->prog->aux->tail_call_reachable
is used. func[0]->aux->tail_call_reachable which represents the main program's
information did not propagate this to the outer env->prog->aux, though. Add this
propagation into check_max_stack_depth() where it needs to belong so that the
check can be done reliably.
Fixes: ebf7d1f508 ("bpf, x64: rework pro/epilogue and tailcall handling in JIT")
Fixes: e411901c0b ("bpf: allow for tailcalls in BPF subprograms for x64 JIT")
Co-developed-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Link: https://lore.kernel.org/bpf/618c34e3163ad1a36b1e82377576a6081e182f25.1626123173.git.daniel@iogearbox.net
Subprograms are calling map_poke_track(), but on program release there is no
hook to call map_poke_untrack(). However, on program release, the aux memory
(and poke descriptor table) is freed even though we still have a reference to
it in the element list of the map aux data. When we run map_poke_run(), we then
end up accessing free'd memory, triggering KASAN in prog_array_map_poke_run():
[...]
[ 402.824689] BUG: KASAN: use-after-free in prog_array_map_poke_run+0xc2/0x34e
[ 402.824698] Read of size 4 at addr ffff8881905a7940 by task hubble-fgs/4337
[ 402.824705] CPU: 1 PID: 4337 Comm: hubble-fgs Tainted: G I 5.12.0+ #399
[ 402.824715] Call Trace:
[ 402.824719] dump_stack+0x93/0xc2
[ 402.824727] print_address_description.constprop.0+0x1a/0x140
[ 402.824736] ? prog_array_map_poke_run+0xc2/0x34e
[ 402.824740] ? prog_array_map_poke_run+0xc2/0x34e
[ 402.824744] kasan_report.cold+0x7c/0xd8
[ 402.824752] ? prog_array_map_poke_run+0xc2/0x34e
[ 402.824757] prog_array_map_poke_run+0xc2/0x34e
[ 402.824765] bpf_fd_array_map_update_elem+0x124/0x1a0
[...]
The elements concerned are walked as follows:
for (i = 0; i < elem->aux->size_poke_tab; i++) {
poke = &elem->aux->poke_tab[i];
[...]
The access to size_poke_tab is a 4 byte read, verified by checking offsets
in the KASAN dump:
[ 402.825004] The buggy address belongs to the object at ffff8881905a7800
which belongs to the cache kmalloc-1k of size 1024
[ 402.825008] The buggy address is located 320 bytes inside of
1024-byte region [ffff8881905a7800, ffff8881905a7c00)
The pahole output of bpf_prog_aux:
struct bpf_prog_aux {
[...]
/* --- cacheline 5 boundary (320 bytes) --- */
u32 size_poke_tab; /* 320 4 */
[...]
In general, subprograms do not necessarily manage their own data structures.
For example, BTF func_info and linfo are just pointers to the main program
structure. This allows reference counting and cleanup to be done on the latter
which simplifies their management a bit. The aux->poke_tab struct, however,
did not follow this logic. The initial proposed fix for this use-after-free
bug further embedded poke data tracking into the subprogram with proper
reference counting. However, Daniel and Alexei questioned why we were treating
these objects special; I agree, its unnecessary. The fix here removes the per
subprogram poke table allocation and map tracking and instead simply points
the aux->poke_tab pointer at the main programs poke table. This way, map
tracking is simplified to the main program and we do not need to manage them
per subprogram.
This also means, bpf_prog_free_deferred(), which unwinds the program reference
counting and kfrees objects, needs to ensure that we don't try to double free
the poke_tab when free'ing the subprog structures. This is easily solved by
NULL'ing the poke_tab pointer. The second detail is to ensure that per
subprogram JIT logic only does fixups on poke_tab[] entries it owns. To do
this, we add a pointer in the poke structure to point at the subprogram value
so JITs can easily check while walking the poke_tab structure if the current
entry belongs to the current program. The aux pointer is stable and therefore
suitable for such comparison. On the jit_subprogs() error path, we omit
cleaning up the poke->aux field because these are only ever referenced from
the JIT side, but on error we will never make it to the JIT, so its fine to
leave them dangling. Removing these pointers would complicate the error path
for no reason. However, we do need to untrack all poke descriptors from the
main program as otherwise they could race with the freeing of JIT memory from
the subprograms. Lastly, a748c6975d ("bpf: propagate poke descriptors to
subprograms") had an off-by-one on the subprogram instruction index range
check as it was testing 'insn_idx >= subprog_start && insn_idx <= subprog_end'.
However, subprog_end is the next subprogram's start instruction.
Fixes: a748c6975d ("bpf: propagate poke descriptors to subprograms")
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210707223848.14580-2-john.fastabend@gmail.com
This lifts the restriction on running devmap BPF progs in generic
redirect mode. To match native XDP behavior, it is invoked right before
generic_xdp_tx is called, and only supports XDP_PASS/XDP_ABORTED/
XDP_DROP actions.
We also return 0 even if devmap program drops the packet, as
semantically redirect has already succeeded and the devmap prog is the
last point before TX of the packet to device where it can deliver a
verdict on the packet.
This also means it must take care of freeing the skb, as
xdp_do_generic_redirect callers only do that in case an error is
returned.
Since devmap entry prog is supported, remove the check in
generic_xdp_install entirely.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-5-memxor@gmail.com
This change implements CPUMAP redirect support for generic XDP programs.
The idea is to reuse the cpu map entry's queue that is used to push
native xdp frames for redirecting skb to a different CPU. This will
match native XDP behavior (in that RPS is invoked again for packet
reinjected into networking stack).
To be able to determine whether the incoming skb is from the driver or
cpumap, we reuse skb->redirected bit that skips generic XDP processing
when it is set. To always make use of this, CONFIG_NET_REDIRECT guard on
it has been lifted and it is always available.
>From the redirect side, we add the skb to ptr_ring with its lowest bit
set to 1. This should be safe as skb is not 1-byte aligned. This allows
kthread to discern between xdp_frames and sk_buff. On consumption of the
ptr_ring item, the lowest bit is unset.
In the end, the skb is simply added to the list that kthread is anyway
going to maintain for xdp_frames converted to skb, and then received
again by using netif_receive_skb_list.
Bulking optimization for generic cpumap is left as an exercise for a
future patch for now.
Since cpumap entry progs are now supported, also remove check in
generic_xdp_install for the cpumap.
Signed-off-by: Kumar Kartikeya Dwivedi <memxor@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210702111825.491065-4-memxor@gmail.com
There were a couple of READ_ONCE()-invocations left-over by the devmap
RCU conversion. Convert these to rcu_dereference_check() as well to avoid
complaints from sparse.
Fixes: 782347b6bc ("xdp: Add proper __rcu annotations to redirect map entries")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Paul E. McKenney <paulmck@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210629093907.573598-1-toke@redhat.com
Trivial conflict in net/netfilter/nf_tables_api.c.
Duplicate fix in tools/testing/selftests/net/devlink_port_split.py
- take the net-next version.
skmsg, and L4 bpf - keep the bpf code but remove the flags
and err params.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Daniel Borkmann says:
====================
pull-request: bpf-next 2021-06-28
The following pull-request contains BPF updates for your *net-next* tree.
We've added 37 non-merge commits during the last 12 day(s) which contain
a total of 56 files changed, 394 insertions(+), 380 deletions(-).
The main changes are:
1) XDP driver RCU cleanups, from Toke Høiland-Jørgensen and Paul E. McKenney.
2) Fix bpf_skb_change_proto() IPv4/v6 GSO handling, from Maciej Żenczykowski.
3) Fix false positive kmemleak report for BPF ringbuf alloc, from Rustam Kovhaev.
4) Fix x86 JIT's extable offset calculation for PROBE_LDX NULL, from Ravi Bangoria.
5) Enable libbpf fallback probing with tracing under RHEL7, from Jonathan Edwards.
6) Clean up x86 JIT to remove unused cnt tracking from EMIT macro, from Jiri Olsa.
7) Netlink cleanups for libbpf to please Coverity, from Kumar Kartikeya Dwivedi.
8) Allow to retrieve ancestor cgroup id in tracing programs, from Namhyung Kim.
9) Fix lirc BPF program query to use user-provided prog_cnt, from Sean Young.
10) Add initial libbpf doc including generated kdoc for its API, from Grant Seltzer.
11) Make xdp_rxq_info_unreg_mem_model() more robust, from Jakub Kicinski.
12) Fix up bpfilter startup log-level to info level, from Gary Lin.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
kmemleak scans struct page, but it does not scan the page content. If we
allocate some memory with kmalloc(), then allocate page with alloc_page(),
and if we put kmalloc pointer somewhere inside that page, kmemleak will
report kmalloc pointer as a false positive.
We can instruct kmemleak to scan the memory area by calling kmemleak_alloc()
and kmemleak_free(), but part of struct bpf_ringbuf is mmaped to user space,
and if struct bpf_ringbuf changes we would have to revisit and review size
argument in kmemleak_alloc(), because we do not want kmemleak to scan the
user space memory. Let's simplify things and use kmemleak_not_leak() here.
For posterity, also adding additional prior analysis from Andrii:
I think either kmemleak or syzbot are misreporting this. I've added a
bunch of printks around all allocations performed by BPF ringbuf. [...]
On repro side I get these two warnings:
[vmuser@archvm bpf]$ sudo ./repro
BUG: memory leak
unreferenced object 0xffff88810d538c00 (size 64):
comm "repro", pid 2140, jiffies 4294692933 (age 14.540s)
hex dump (first 32 bytes):
00 af 19 04 00 ea ff ff c0 ae 19 04 00 ea ff ff ................
80 ae 19 04 00 ea ff ff c0 29 2e 04 00 ea ff ff .........)......
backtrace:
[<0000000077bfbfbd>] __bpf_map_area_alloc+0x31/0xc0
[<00000000587fa522>] ringbuf_map_alloc.cold.4+0x48/0x218
[<0000000044d49e96>] __do_sys_bpf+0x359/0x1d90
[<00000000f601d565>] do_syscall_64+0x2d/0x40
[<0000000043d3112a>] entry_SYSCALL_64_after_hwframe+0x44/0xae
BUG: memory leak
unreferenced object 0xffff88810d538c80 (size 64):
comm "repro", pid 2143, jiffies 4294699025 (age 8.448s)
hex dump (first 32 bytes):
80 aa 19 04 00 ea ff ff 00 ab 19 04 00 ea ff ff ................
c0 ab 19 04 00 ea ff ff 80 44 28 04 00 ea ff ff .........D(.....
backtrace:
[<0000000077bfbfbd>] __bpf_map_area_alloc+0x31/0xc0
[<00000000587fa522>] ringbuf_map_alloc.cold.4+0x48/0x218
[<0000000044d49e96>] __do_sys_bpf+0x359/0x1d90
[<00000000f601d565>] do_syscall_64+0x2d/0x40
[<0000000043d3112a>] entry_SYSCALL_64_after_hwframe+0x44/0xae
Note that both reported leaks (ffff88810d538c80 and ffff88810d538c00)
correspond to pages array bpf_ringbuf is allocating and tracking properly
internally. Note also that syzbot repro doesn't close FD of created BPF
ringbufs, and even when ./repro itself exits with error, there are still
two forked processes hanging around in my system. So clearly ringbuf maps
are alive at that point. So reporting any memory leak looks weird at that
point, because that memory is being used by active referenced BPF ringbuf.
It's also a question why repro doesn't clean up its forks. But if I do a
`pkill repro`, I do see that all the allocated memory is /properly/ cleaned
up [and the] "leaks" are deallocated properly.
BTW, if I add close() right after bpf() syscall in syzbot repro, I see that
everything is immediately deallocated, like designed. And no memory leak
is reported. So I don't think the problem is anywhere in bpf_ringbuf code,
rather in the leak detection and/or repro itself.
Reported-by: syzbot+5d895828587f49e7fe9b@syzkaller.appspotmail.com
Signed-off-by: Rustam Kovhaev <rkovhaev@gmail.com>
[ Daniel: also included analysis from Andrii to the commit log ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: syzbot+5d895828587f49e7fe9b@syzkaller.appspotmail.com
Cc: Dmitry Vyukov <dvyukov@google.com>
Cc: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/CAEf4BzYk+dqs+jwu6VKXP-RttcTEGFe+ySTGWT9CRNkagDiJVA@mail.gmail.com
Link: https://lore.kernel.org/lkml/YNTAqiE7CWJhOK2M@nuc10
Link: https://lore.kernel.org/lkml/20210615101515.GC26027@arm.com
Link: https://syzkaller.appspot.com/bug?extid=5d895828587f49e7fe9b
Link: https://lore.kernel.org/bpf/20210626181156.1873604-1-rkovhaev@gmail.com
XDP_REDIRECT works by a three-step process: the bpf_redirect() and
bpf_redirect_map() helpers will lookup the target of the redirect and store
it (along with some other metadata) in a per-CPU struct bpf_redirect_info.
Next, when the program returns the XDP_REDIRECT return code, the driver
will call xdp_do_redirect() which will use the information thus stored to
actually enqueue the frame into a bulk queue structure (that differs
slightly by map type, but shares the same principle). Finally, before
exiting its NAPI poll loop, the driver will call xdp_do_flush(), which will
flush all the different bulk queues, thus completing the redirect.
Pointers to the map entries will be kept around for this whole sequence of
steps, protected by RCU. However, there is no top-level rcu_read_lock() in
the core code; instead drivers add their own rcu_read_lock() around the XDP
portions of the code, but somewhat inconsistently as Martin discovered[0].
However, things still work because everything happens inside a single NAPI
poll sequence, which means it's between a pair of calls to
local_bh_disable()/local_bh_enable(). So Paul suggested[1] that we could
document this intention by using rcu_dereference_check() with
rcu_read_lock_bh_held() as a second parameter, thus allowing sparse and
lockdep to verify that everything is done correctly.
This patch does just that: we add an __rcu annotation to the map entry
pointers and remove the various comments explaining the NAPI poll assurance
strewn through devmap.c in favour of a longer explanation in filter.c. The
goal is to have one coherent documentation of the entire flow, and rely on
the RCU annotations as a "standard" way of communicating the flow in the
map code (which can additionally be understood by sparse and lockdep).
The RCU annotation replacements result in a fairly straight-forward
replacement where READ_ONCE() becomes rcu_dereference_check(), WRITE_ONCE()
becomes rcu_assign_pointer() and xchg() and cmpxchg() gets wrapped in the
proper constructs to cast the pointer back and forth between __rcu and
__kernel address space (for the benefit of sparse). The one complication is
that xskmap has a few constructions where double-pointers are passed back
and forth; these simply all gain __rcu annotations, and only the final
reference/dereference to the inner-most pointer gets changed.
With this, everything can be run through sparse without eliciting
complaints, and lockdep can verify correctness even without the use of
rcu_read_lock() in the drivers. Subsequent patches will clean these up from
the drivers.
[0] https://lore.kernel.org/bpf/20210415173551.7ma4slcbqeyiba2r@kafai-mbp.dhcp.thefacebook.com/
[1] https://lore.kernel.org/bpf/20210419165837.GA975577@paulmck-ThinkPad-P17-Gen-1/
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210624160609.292325-6-toke@redhat.com
XDP programs are called from a NAPI poll context, which means the RCU
reference liveness is ensured by local_bh_disable(). Add
rcu_read_lock_bh_held() as a condition to the RCU checks for map lookups so
lockdep understands that the dereferences are safe from inside *either* an
rcu_read_lock() section *or* a local_bh_disable() section. While both
bh_disabled and rcu_read_lock() provide RCU protection, they are
semantically distinct, so we need both conditions to prevent lockdep
complaints.
This change is done in preparation for removing the redundant
rcu_read_lock()s from drivers.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210624160609.292325-5-toke@redhat.com
The sub-programs prog->aux->poke_tab[] is populated in jit_subprogs() and
then used when emitting 'BPF_JMP|BPF_TAIL_CALL' insn->code from the
individual JITs. The poke_tab[] to use is stored in the insn->imm by
the code adding it to that array slot. The JIT then uses imm to find the
right entry for an individual instruction. In the x86 bpf_jit_comp.c
this is done by calling emit_bpf_tail_call_direct with the poke_tab[]
of the imm value.
However, we observed the below null-ptr-deref when mixing tail call
programs with subprog programs. For this to happen we just need to
mix bpf-2-bpf calls and tailcalls with some extra calls or instructions
that would be patched later by one of the fixup routines. So whats
happening?
Before the fixup_call_args() -- where the jit op is done -- various
code patching is done by do_misc_fixups(). This may increase the
insn count, for example when we patch map_lookup_up using map_gen_lookup
hook. This does two things. First, it means the instruction index,
insn_idx field, of a tail call instruction will move by a 'delta'.
In verifier code,
struct bpf_jit_poke_descriptor desc = {
.reason = BPF_POKE_REASON_TAIL_CALL,
.tail_call.map = BPF_MAP_PTR(aux->map_ptr_state),
.tail_call.key = bpf_map_key_immediate(aux),
.insn_idx = i + delta,
};
Then subprog start values subprog_info[i].start will be updated
with the delta and any poke descriptor index will also be updated
with the delta in adjust_poke_desc(). If we look at the adjust
subprog starts though we see its only adjusted when the delta
occurs before the new instructions,
/* NOTE: fake 'exit' subprog should be updated as well. */
for (i = 0; i <= env->subprog_cnt; i++) {
if (env->subprog_info[i].start <= off)
continue;
Earlier subprograms are not changed because their start values
are not moved. But, adjust_poke_desc() does the offset + delta
indiscriminately. The result is poke descriptors are potentially
corrupted.
Then in jit_subprogs() we only populate the poke_tab[]
when the above insn_idx is less than the next subprogram start. From
above we corrupted our insn_idx so we might incorrectly assume a
poke descriptor is not used in a subprogram omitting it from the
subprogram. And finally when the jit runs it does the deref of poke_tab
when emitting the instruction and crashes with below. Because earlier
step omitted the poke descriptor.
The fix is straight forward with above context. Simply move same logic
from adjust_subprog_starts() into adjust_poke_descs() and only adjust
insn_idx when needed.
[ 82.396354] bpf_testmod: version magic '5.12.0-rc2alu+ SMP preempt mod_unload ' should be '5.12.0+ SMP preempt mod_unload '
[ 82.623001] loop10: detected capacity change from 0 to 8
[ 88.487424] ==================================================================
[ 88.487438] BUG: KASAN: null-ptr-deref in do_jit+0x184a/0x3290
[ 88.487455] Write of size 8 at addr 0000000000000008 by task test_progs/5295
[ 88.487471] CPU: 7 PID: 5295 Comm: test_progs Tainted: G I 5.12.0+ #386
[ 88.487483] Hardware name: Dell Inc. Precision 5820 Tower/002KVM, BIOS 1.9.2 01/24/2019
[ 88.487490] Call Trace:
[ 88.487498] dump_stack+0x93/0xc2
[ 88.487515] kasan_report.cold+0x5f/0xd8
[ 88.487530] ? do_jit+0x184a/0x3290
[ 88.487542] do_jit+0x184a/0x3290
...
[ 88.487709] bpf_int_jit_compile+0x248/0x810
...
[ 88.487765] bpf_check+0x3718/0x5140
...
[ 88.487920] bpf_prog_load+0xa22/0xf10
Fixes: a748c6975d ("bpf: propagate poke descriptors to subprograms")
Reported-by: Jussi Maki <joamaki@gmail.com>
Signed-off-by: John Fastabend <john.fastabend@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Reviewed-by: Daniel Borkmann <daniel@iogearbox.net>
In 32-bit architecture, the result of sizeof() is a 32-bit integer so
the expression becomes the multiplication between 2 32-bit integer which
can potentially leads to integer overflow. As a result,
bpf_map_area_alloc() allocates less memory than needed.
Fix this by casting 1 operand to u64.
Fixes: 0d2c4f9640 ("bpf: Eliminate rlimit-based memory accounting for sockmap and sockhash maps")
Fixes: 99c51064fb ("devmap: Use bpf_map_area_alloc() for allocating hash buckets")
Fixes: 546ac1ffb7 ("bpf: add devmap, a map for storing net device references")
Signed-off-by: Bui Quang Minh <minhquangbui99@gmail.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210613143440.71975-1-minhquangbui99@gmail.com
This reverts commit d37300ed18 ("bpf: program: Refuse non-O_RDWR flags
in BPF_OBJ_GET"). It breaks Android userspace which expects to be able to
fetch programs with just read permissions.
See: https://cs.android.com/android/platform/superproject/+/master:frameworks/libs/net/common/native/bpf_syscall_wrappers/include/BpfSyscallWrappers.h;drc=7005c764be23d31fa1d69e826b4a2f6689a8c81e;l=124
Side-note: another option to fix it would be to extend bpf_prog_new_fd()
and to pass in used file mode flags in the same way as we do for maps via
bpf_map_new_fd(). Meaning, they'd end up in anon_inode_getfd() and thus
would be retained for prog fd operations with bpf() syscall. Right now
these flags are not checked with progs since they are immutable for their
lifetime (as opposed to maps which can be updated from user space). In
future this could potentially change with new features, but at that point
it's still fine to do the bpf_prog_new_fd() extension when needed. For a
simple stable fix, a revert is less churn.
Fixes: d37300ed18 ("bpf: program: Refuse non-O_RDWR flags in BPF_OBJ_GET")
Signed-off-by: Maciej Żenczykowski <maze@google.com>
[ Daniel: added side-note to commit message ]
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Lorenz Bauer <lmb@cloudflare.com>
Acked-by: Greg Kroah-Hartman <gregkh@google.com>
Link: https://lore.kernel.org/bpf/20210618105526.265003-1-zenczykowski@gmail.com
Trivial conflicts in net/can/isotp.c and
tools/testing/selftests/net/mptcp/mptcp_connect.sh
scaled_ppm_to_ppb() was moved from drivers/ptp/ptp_clock.c
to include/linux/ptp_clock_kernel.h in -next so re-apply
the fix there.
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Daniel Borkmann says:
====================
pull-request: bpf-next 2021-06-17
The following pull-request contains BPF updates for your *net-next* tree.
We've added 50 non-merge commits during the last 25 day(s) which contain
a total of 148 files changed, 4779 insertions(+), 1248 deletions(-).
The main changes are:
1) BPF infrastructure to migrate TCP child sockets from a listener to another
in the same reuseport group/map, from Kuniyuki Iwashima.
2) Add a provably sound, faster and more precise algorithm for tnum_mul() as
noted in https://arxiv.org/abs/2105.05398, from Harishankar Vishwanathan.
3) Streamline error reporting changes in libbpf as planned out in the
'libbpf: the road to v1.0' effort, from Andrii Nakryiko.
4) Add broadcast support to xdp_redirect_map(), from Hangbin Liu.
5) Extends bpf_map_lookup_and_delete_elem() functionality to 4 more map
types, that is, {LRU_,PERCPU_,LRU_PERCPU_,}HASH, from Denis Salopek.
6) Support new LLVM relocations in libbpf to make them more linker friendly,
also add a doc to describe the BPF backend relocations, from Yonghong Song.
7) Silence long standing KUBSAN complaints on register-based shifts in
interpreter, from Daniel Borkmann and Eric Biggers.
8) Add dummy PT_REGS macros in libbpf to fail BPF program compilation when
target arch cannot be determined, from Lorenz Bauer.
9) Extend AF_XDP to support large umems with 1M+ pages, from Magnus Karlsson.
10) Fix two minor libbpf tc BPF API issues, from Kumar Kartikeya Dwivedi.
11) Move libbpf BPF_SEQ_PRINTF/BPF_SNPRINTF macros that can be used by BPF
programs to bpf_helpers.h header, from Florent Revest.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
syzbot reported a shift-out-of-bounds that KUBSAN observed in the
interpreter:
[...]
UBSAN: shift-out-of-bounds in kernel/bpf/core.c:1420:2
shift exponent 255 is too large for 64-bit type 'long long unsigned int'
CPU: 1 PID: 11097 Comm: syz-executor.4 Not tainted 5.12.0-rc2-syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
Call Trace:
__dump_stack lib/dump_stack.c:79 [inline]
dump_stack+0x141/0x1d7 lib/dump_stack.c:120
ubsan_epilogue+0xb/0x5a lib/ubsan.c:148
__ubsan_handle_shift_out_of_bounds.cold+0xb1/0x181 lib/ubsan.c:327
___bpf_prog_run.cold+0x19/0x56c kernel/bpf/core.c:1420
__bpf_prog_run32+0x8f/0xd0 kernel/bpf/core.c:1735
bpf_dispatcher_nop_func include/linux/bpf.h:644 [inline]
bpf_prog_run_pin_on_cpu include/linux/filter.h:624 [inline]
bpf_prog_run_clear_cb include/linux/filter.h:755 [inline]
run_filter+0x1a1/0x470 net/packet/af_packet.c:2031
packet_rcv+0x313/0x13e0 net/packet/af_packet.c:2104
dev_queue_xmit_nit+0x7c2/0xa90 net/core/dev.c:2387
xmit_one net/core/dev.c:3588 [inline]
dev_hard_start_xmit+0xad/0x920 net/core/dev.c:3609
__dev_queue_xmit+0x2121/0x2e00 net/core/dev.c:4182
__bpf_tx_skb net/core/filter.c:2116 [inline]
__bpf_redirect_no_mac net/core/filter.c:2141 [inline]
__bpf_redirect+0x548/0xc80 net/core/filter.c:2164
____bpf_clone_redirect net/core/filter.c:2448 [inline]
bpf_clone_redirect+0x2ae/0x420 net/core/filter.c:2420
___bpf_prog_run+0x34e1/0x77d0 kernel/bpf/core.c:1523
__bpf_prog_run512+0x99/0xe0 kernel/bpf/core.c:1737
bpf_dispatcher_nop_func include/linux/bpf.h:644 [inline]
bpf_test_run+0x3ed/0xc50 net/bpf/test_run.c:50
bpf_prog_test_run_skb+0xabc/0x1c50 net/bpf/test_run.c:582
bpf_prog_test_run kernel/bpf/syscall.c:3127 [inline]
__do_sys_bpf+0x1ea9/0x4f00 kernel/bpf/syscall.c:4406
do_syscall_64+0x2d/0x70 arch/x86/entry/common.c:46
entry_SYSCALL_64_after_hwframe+0x44/0xae
[...]
Generally speaking, KUBSAN reports from the kernel should be fixed.
However, in case of BPF, this particular report caused concerns since
the large shift is not wrong from BPF point of view, just undefined.
In the verifier, K-based shifts that are >= {64,32} (depending on the
bitwidth of the instruction) are already rejected. The register-based
cases were not given their content might not be known at verification
time. Ideas such as verifier instruction rewrite with an additional
AND instruction for the source register were brought up, but regularly
rejected due to the additional runtime overhead they incur.
As Edward Cree rightly put it:
Shifts by more than insn bitness are legal in the BPF ISA; they are
implementation-defined behaviour [of the underlying architecture],
rather than UB, and have been made legal for performance reasons.
Each of the JIT backends compiles the BPF shift operations to machine
instructions which produce implementation-defined results in such a
case; the resulting contents of the register may be arbitrary but
program behaviour as a whole remains defined.
Guard checks in the fast path (i.e. affecting JITted code) will thus
not be accepted.
The case of division by zero is not truly analogous here, as division
instructions on many of the JIT-targeted architectures will raise a
machine exception / fault on division by zero, whereas (to the best
of my knowledge) none will do so on an out-of-bounds shift.
Given the KUBSAN report only affects the BPF interpreter, but not JITs,
one solution is to add the ANDs with 63 or 31 into ___bpf_prog_run().
That would make the shifts defined, and thus shuts up KUBSAN, and the
compiler would optimize out the AND on any CPU that interprets the shift
amounts modulo the width anyway (e.g., confirmed from disassembly that
on x86-64 and arm64 the generated interpreter code is the same before
and after this fix).
The BPF interpreter is slow path, and most likely compiled out anyway
as distros select BPF_JIT_ALWAYS_ON to avoid speculative execution of
BPF instructions by the interpreter. Given the main argument was to
avoid sacrificing performance, the fact that the AND is optimized away
from compiler for mainstream archs helps as well as a solution moving
forward. Also add a comment on LSH/RSH/ARSH translation for JIT authors
to provide guidance when they see the ___bpf_prog_run() interpreter
code and use it as a model for a new JIT backend.
Reported-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com
Reported-by: Kurt Manucredo <fuzzybritches0@gmail.com>
Signed-off-by: Eric Biggers <ebiggers@kernel.org>
Co-developed-by: Eric Biggers <ebiggers@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Tested-by: syzbot+bed360704c521841c85d@syzkaller.appspotmail.com
Cc: Edward Cree <ecree.xilinx@gmail.com>
Link: https://lore.kernel.org/bpf/0000000000008f912605bd30d5d7@google.com
Link: https://lore.kernel.org/bpf/bac16d8d-c174-bdc4-91bd-bfa62b410190@gmail.com
This patch introduces a new bpf_attach_type for BPF_PROG_TYPE_SK_REUSEPORT
to check if the attached eBPF program is capable of migrating sockets. When
the eBPF program is attached, we run it for socket migration if the
expected_attach_type is BPF_SK_REUSEPORT_SELECT_OR_MIGRATE or
net.ipv4.tcp_migrate_req is enabled.
Currently, the expected_attach_type is not enforced for the
BPF_PROG_TYPE_SK_REUSEPORT type of program. Thus, this commit follows the
earlier idea in the commit aac3fc320d ("bpf: Post-hooks for sys_bind") to
fix up the zero expected_attach_type in bpf_prog_load_fixup_attach_type().
Moreover, this patch adds a new field (migrating_sk) to sk_reuseport_md to
select a new listener based on the child socket. migrating_sk varies
depending on if it is migrating a request in the accept queue or during
3WHS.
- accept_queue : sock (ESTABLISHED/SYN_RECV)
- 3WHS : request_sock (NEW_SYN_RECV)
In the eBPF program, we can select a new listener by
BPF_FUNC_sk_select_reuseport(). Also, we can cancel migration by returning
SK_DROP. This feature is useful when listeners have different settings at
the socket API level or when we want to free resources as soon as possible.
- SK_PASS with selected_sk, select it as a new listener
- SK_PASS with selected_sk NULL, fallbacks to the random selection
- SK_DROP, cancel the migration.
There is a noteworthy point. We select a listening socket in three places,
but we do not have struct skb at closing a listener or retransmitting a
SYN+ACK. On the other hand, some helper functions do not expect skb is NULL
(e.g. skb_header_pointer() in BPF_FUNC_skb_load_bytes(), skb_tail_pointer()
in BPF_FUNC_skb_load_bytes_relative()). So we allocate an empty skb
temporarily before running the eBPF program.
Suggested-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.co.jp>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/netdev/20201123003828.xjpjdtk4ygl6tg6h@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201203042402.6cskdlit5f3mw4ru@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/netdev/20201209030903.hhow5r53l6fmozjn@kafai-mbp.dhcp.thefacebook.com/
Link: https://lore.kernel.org/bpf/20210612123224.12525-10-kuniyu@amazon.co.jp
The verifier only enumerates valid control-flow paths and skips paths that
are unreachable in the non-speculative domain. And so it can miss issues
under speculative execution on mispredicted branches.
For example, a type confusion has been demonstrated with the following
crafted program:
// r0 = pointer to a map array entry
// r6 = pointer to readable stack slot
// r9 = scalar controlled by attacker
1: r0 = *(u64 *)(r0) // cache miss
2: if r0 != 0x0 goto line 4
3: r6 = r9
4: if r0 != 0x1 goto line 6
5: r9 = *(u8 *)(r6)
6: // leak r9
Since line 3 runs iff r0 == 0 and line 5 runs iff r0 == 1, the verifier
concludes that the pointer dereference on line 5 is safe. But: if the
attacker trains both the branches to fall-through, such that the following
is speculatively executed ...
r6 = r9
r9 = *(u8 *)(r6)
// leak r9
... then the program will dereference an attacker-controlled value and could
leak its content under speculative execution via side-channel. This requires
to mistrain the branch predictor, which can be rather tricky, because the
branches are mutually exclusive. However such training can be done at
congruent addresses in user space using different branches that are not
mutually exclusive. That is, by training branches in user space ...
A: if r0 != 0x0 goto line C
B: ...
C: if r0 != 0x0 goto line D
D: ...
... such that addresses A and C collide to the same CPU branch prediction
entries in the PHT (pattern history table) as those of the BPF program's
lines 2 and 4, respectively. A non-privileged attacker could simply brute
force such collisions in the PHT until observing the attack succeeding.
Alternative methods to mistrain the branch predictor are also possible that
avoid brute forcing the collisions in the PHT. A reliable attack has been
demonstrated, for example, using the following crafted program:
// r0 = pointer to a [control] map array entry
// r7 = *(u64 *)(r0 + 0), training/attack phase
// r8 = *(u64 *)(r0 + 8), oob address
// [...]
// r0 = pointer to a [data] map array entry
1: if r7 == 0x3 goto line 3
2: r8 = r0
// crafted sequence of conditional jumps to separate the conditional
// branch in line 193 from the current execution flow
3: if r0 != 0x0 goto line 5
4: if r0 == 0x0 goto exit
5: if r0 != 0x0 goto line 7
6: if r0 == 0x0 goto exit
[...]
187: if r0 != 0x0 goto line 189
188: if r0 == 0x0 goto exit
// load any slowly-loaded value (due to cache miss in phase 3) ...
189: r3 = *(u64 *)(r0 + 0x1200)
// ... and turn it into known zero for verifier, while preserving slowly-
// loaded dependency when executing:
190: r3 &= 1
191: r3 &= 2
// speculatively bypassed phase dependency
192: r7 += r3
193: if r7 == 0x3 goto exit
194: r4 = *(u8 *)(r8 + 0)
// leak r4
As can be seen, in training phase (phase != 0x3), the condition in line 1
turns into false and therefore r8 with the oob address is overridden with
the valid map value address, which in line 194 we can read out without
issues. However, in attack phase, line 2 is skipped, and due to the cache
miss in line 189 where the map value is (zeroed and later) added to the
phase register, the condition in line 193 takes the fall-through path due
to prior branch predictor training, where under speculation, it'll load the
byte at oob address r8 (unknown scalar type at that point) which could then
be leaked via side-channel.
One way to mitigate these is to 'branch off' an unreachable path, meaning,
the current verification path keeps following the is_branch_taken() path
and we push the other branch to the verification stack. Given this is
unreachable from the non-speculative domain, this branch's vstate is
explicitly marked as speculative. This is needed for two reasons: i) if
this path is solely seen from speculative execution, then we later on still
want the dead code elimination to kick in in order to sanitize these
instructions with jmp-1s, and ii) to ensure that paths walked in the
non-speculative domain are not pruned from earlier walks of paths walked in
the speculative domain. Additionally, for robustness, we mark the registers
which have been part of the conditional as unknown in the speculative path
given there should be no assumptions made on their content.
The fix in here mitigates type confusion attacks described earlier due to
i) all code paths in the BPF program being explored and ii) existing
verifier logic already ensuring that given memory access instruction
references one specific data structure.
An alternative to this fix that has also been looked at in this scope was to
mark aux->alu_state at the jump instruction with a BPF_JMP_TAKEN state as
well as direction encoding (always-goto, always-fallthrough, unknown), such
that mixing of different always-* directions themselves as well as mixing of
always-* with unknown directions would cause a program rejection by the
verifier, e.g. programs with constructs like 'if ([...]) { x = 0; } else
{ x = 1; }' with subsequent 'if (x == 1) { [...] }'. For unprivileged, this
would result in only single direction always-* taken paths, and unknown taken
paths being allowed, such that the former could be patched from a conditional
jump to an unconditional jump (ja). Compared to this approach here, it would
have two downsides: i) valid programs that otherwise are not performing any
pointer arithmetic, etc, would potentially be rejected/broken, and ii) we are
required to turn off path pruning for unprivileged, where both can be avoided
in this work through pushing the invalid branch to the verification stack.
The issue was originally discovered by Adam and Ofek, and later independently
discovered and reported as a result of Benedict and Piotr's research work.
Fixes: b2157399cc ("bpf: prevent out-of-bounds speculation")
Reported-by: Adam Morrison <mad@cs.tau.ac.il>
Reported-by: Ofek Kirzner <ofekkir@gmail.com>
Reported-by: Benedict Schlueter <benedict.schlueter@rub.de>
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
... in such circumstances, we do not want to mark the instruction as seen given
the goal is still to jmp-1 rewrite/sanitize dead code, if it is not reachable
from the non-speculative path verification. We do however want to verify it for
safety regardless.
With the patch as-is all the insns that have been marked as seen before the
patch will also be marked as seen after the patch (just with a potentially
different non-zero count). An upcoming patch will also verify paths that are
unreachable in the non-speculative domain, hence this extension is needed.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Instead of relying on current env->pass_cnt, use the seen count from the
old aux data in adjust_insn_aux_data(), and expand it to the new range of
patched instructions. This change is valid given we always expand 1:n
with n>=1, so what applies to the old/original instruction needs to apply
for the replacement as well.
Not relying on env->pass_cnt is a prerequisite for a later change where we
want to avoid marking an instruction seen when verified under speculative
execution path.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Reviewed-by: Benedict Schlueter <benedict.schlueter@rub.de>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Commit 59438b4647 ("security,lockdown,selinux: implement SELinux lockdown")
added an implementation of the locked_down LSM hook to SELinux, with the aim
to restrict which domains are allowed to perform operations that would breach
lockdown. This is indirectly also getting audit subsystem involved to report
events. The latter is problematic, as reported by Ondrej and Serhei, since it
can bring down the whole system via audit:
1) The audit events that are triggered due to calls to security_locked_down()
can OOM kill a machine, see below details [0].
2) It also seems to be causing a deadlock via avc_has_perm()/slow_avc_audit()
when trying to wake up kauditd, for example, when using trace_sched_switch()
tracepoint, see details in [1]. Triggering this was not via some hypothetical
corner case, but with existing tools like runqlat & runqslower from bcc, for
example, which make use of this tracepoint. Rough call sequence goes like:
rq_lock(rq) -> -------------------------+
trace_sched_switch() -> |
bpf_prog_xyz() -> +-> deadlock
selinux_lockdown() -> |
audit_log_end() -> |
wake_up_interruptible() -> |
try_to_wake_up() -> |
rq_lock(rq) --------------+
What's worse is that the intention of 59438b4647 to further restrict lockdown
settings for specific applications in respect to the global lockdown policy is
completely broken for BPF. The SELinux policy rule for the current lockdown check
looks something like this:
allow <who> <who> : lockdown { <reason> };
However, this doesn't match with the 'current' task where the security_locked_down()
is executed, example: httpd does a syscall. There is a tracing program attached
to the syscall which triggers a BPF program to run, which ends up doing a
bpf_probe_read_kernel{,_str}() helper call. The selinux_lockdown() hook does
the permission check against 'current', that is, httpd in this example. httpd
has literally zero relation to this tracing program, and it would be nonsensical
having to write an SELinux policy rule against httpd to let the tracing helper
pass. The policy in this case needs to be against the entity that is installing
the BPF program. For example, if bpftrace would generate a histogram of syscall
counts by user space application:
bpftrace -e 'tracepoint:raw_syscalls:sys_enter { @[comm] = count(); }'
bpftrace would then go and generate a BPF program from this internally. One way
of doing it [for the sake of the example] could be to call bpf_get_current_task()
helper and then access current->comm via one of bpf_probe_read_kernel{,_str}()
helpers. So the program itself has nothing to do with httpd or any other random
app doing a syscall here. The BPF program _explicitly initiated_ the lockdown
check. The allow/deny policy belongs in the context of bpftrace: meaning, you
want to grant bpftrace access to use these helpers, but other tracers on the
system like my_random_tracer _not_.
Therefore fix all three issues at the same time by taking a completely different
approach for the security_locked_down() hook, that is, move the check into the
program verification phase where we actually retrieve the BPF func proto. This
also reliably gets the task (current) that is trying to install the BPF tracing
program, e.g. bpftrace/bcc/perf/systemtap/etc, and it also fixes the OOM since
we're moving this out of the BPF helper's fast-path which can be called several
millions of times per second.
The check is then also in line with other security_locked_down() hooks in the
system where the enforcement is performed at open/load time, for example,
open_kcore() for /proc/kcore access or module_sig_check() for module signatures
just to pick few random ones. What's out of scope in the fix as well as in
other security_locked_down() hook locations /outside/ of BPF subsystem is that
if the lockdown policy changes on the fly there is no retrospective action.
This requires a different discussion, potentially complex infrastructure, and
it's also not clear whether this can be solved generically. Either way, it is
out of scope for a suitable stable fix which this one is targeting. Note that
the breakage is specifically on 59438b4647 where it started to rely on 'current'
as UAPI behavior, and _not_ earlier infrastructure such as 9d1f8be5cf ("bpf:
Restrict bpf when kernel lockdown is in confidentiality mode").
[0] https://bugzilla.redhat.com/show_bug.cgi?id=1955585, Jakub Hrozek says:
I starting seeing this with F-34. When I run a container that is traced with
BPF to record the syscalls it is doing, auditd is flooded with messages like:
type=AVC msg=audit(1619784520.593:282387): avc: denied { confidentiality }
for pid=476 comm="auditd" lockdown_reason="use of bpf to read kernel RAM"
scontext=system_u:system_r:auditd_t:s0 tcontext=system_u:system_r:auditd_t:s0
tclass=lockdown permissive=0
This seems to be leading to auditd running out of space in the backlog buffer
and eventually OOMs the machine.
[...]
auditd running at 99% CPU presumably processing all the messages, eventually I get:
Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded
Apr 30 12:20:42 fedora kernel: audit: backlog limit exceeded
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152579 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152626 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_backlog=2152694 > audit_backlog_limit=64
Apr 30 12:20:42 fedora kernel: audit: audit_lost=6878426 audit_rate_limit=0 audit_backlog_limit=64
Apr 30 12:20:45 fedora kernel: oci-seccomp-bpf invoked oom-killer: gfp_mask=0x100cca(GFP_HIGHUSER_MOVABLE), order=0, oom_score_adj=-1000
Apr 30 12:20:45 fedora kernel: CPU: 0 PID: 13284 Comm: oci-seccomp-bpf Not tainted 5.11.12-300.fc34.x86_64 #1
Apr 30 12:20:45 fedora kernel: Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.13.0-2.fc32 04/01/2014
[...]
[1] https://lore.kernel.org/linux-audit/CANYvDQN7H5tVp47fbYcRasv4XF07eUbsDwT_eDCHXJUj43J7jQ@mail.gmail.com/,
Serhei Makarov says:
Upstream kernel 5.11.0-rc7 and later was found to deadlock during a
bpf_probe_read_compat() call within a sched_switch tracepoint. The problem
is reproducible with the reg_alloc3 testcase from SystemTap's BPF backend
testsuite on x86_64 as well as the runqlat, runqslower tools from bcc on
ppc64le. Example stack trace:
[...]
[ 730.868702] stack backtrace:
[ 730.869590] CPU: 1 PID: 701 Comm: in:imjournal Not tainted, 5.12.0-0.rc2.20210309git144c79ef3353.166.fc35.x86_64 #1
[ 730.871605] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.13.0-2.fc32 04/01/2014
[ 730.873278] Call Trace:
[ 730.873770] dump_stack+0x7f/0xa1
[ 730.874433] check_noncircular+0xdf/0x100
[ 730.875232] __lock_acquire+0x1202/0x1e10
[ 730.876031] ? __lock_acquire+0xfc0/0x1e10
[ 730.876844] lock_acquire+0xc2/0x3a0
[ 730.877551] ? __wake_up_common_lock+0x52/0x90
[ 730.878434] ? lock_acquire+0xc2/0x3a0
[ 730.879186] ? lock_is_held_type+0xa7/0x120
[ 730.880044] ? skb_queue_tail+0x1b/0x50
[ 730.880800] _raw_spin_lock_irqsave+0x4d/0x90
[ 730.881656] ? __wake_up_common_lock+0x52/0x90
[ 730.882532] __wake_up_common_lock+0x52/0x90
[ 730.883375] audit_log_end+0x5b/0x100
[ 730.884104] slow_avc_audit+0x69/0x90
[ 730.884836] avc_has_perm+0x8b/0xb0
[ 730.885532] selinux_lockdown+0xa5/0xd0
[ 730.886297] security_locked_down+0x20/0x40
[ 730.887133] bpf_probe_read_compat+0x66/0xd0
[ 730.887983] bpf_prog_250599c5469ac7b5+0x10f/0x820
[ 730.888917] trace_call_bpf+0xe9/0x240
[ 730.889672] perf_trace_run_bpf_submit+0x4d/0xc0
[ 730.890579] perf_trace_sched_switch+0x142/0x180
[ 730.891485] ? __schedule+0x6d8/0xb20
[ 730.892209] __schedule+0x6d8/0xb20
[ 730.892899] schedule+0x5b/0xc0
[ 730.893522] exit_to_user_mode_prepare+0x11d/0x240
[ 730.894457] syscall_exit_to_user_mode+0x27/0x70
[ 730.895361] entry_SYSCALL_64_after_hwframe+0x44/0xae
[...]
Fixes: 59438b4647 ("security,lockdown,selinux: implement SELinux lockdown")
Reported-by: Ondrej Mosnacek <omosnace@redhat.com>
Reported-by: Jakub Hrozek <jhrozek@redhat.com>
Reported-by: Serhei Makarov <smakarov@redhat.com>
Reported-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Jiri Olsa <jolsa@redhat.com>
Cc: Paul Moore <paul@paul-moore.com>
Cc: James Morris <jamorris@linux.microsoft.com>
Cc: Jerome Marchand <jmarchan@redhat.com>
Cc: Frank Eigler <fche@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: https://lore.kernel.org/bpf/01135120-8bf7-df2e-cff0-1d73f1f841c3@iogearbox.net
This patch introduces a new algorithm for multiplication of tristate
numbers (tnums) that is provably sound. It is faster and more precise when
compared to the existing method.
Like the existing method, this new algorithm follows the long
multiplication algorithm. The idea is to generate partial products by
multiplying each bit in the multiplier (tnum a) with the multiplicand
(tnum b), and adding the partial products after appropriately bit-shifting
them. The new algorithm, however, uses just a single loop over the bits of
the multiplier (tnum a) and accumulates only the uncertain components of
the multiplicand (tnum b) into a mask-only tnum. The following paper
explains the algorithm in more detail: https://arxiv.org/abs/2105.05398.
A natural way to construct the tnum product is by performing a tnum
addition on all the partial products. This algorithm presents another
method of doing this: decompose each partial product into two tnums,
consisting of the values and the masks separately. The mask-sum is
accumulated within the loop in acc_m. The value-sum tnum is generated
using a.value * b.value. The tnum constructed by tnum addition of the
value-sum and the mask-sum contains all possible summations of concrete
values drawn from the partial product tnums pairwise. We prove this result
in the paper.
Our evaluations show that the new algorithm is overall more precise
(producing tnums with less uncertain components) than the existing method.
As an illustrative example, consider the input tnums A and B. The numbers
in the parenthesis correspond to (value;mask).
A = 000000x1 (1;2)
B = 0010011x (38;1)
A * B (existing) = xxxxxxxx (0;255)
A * B (new) = 0x1xxxxx (32;95)
Importantly, we present a proof of soundness of the new algorithm in the
aforementioned paper. Additionally, we show that this new algorithm is
empirically faster than the existing method.
Co-developed-by: Matan Shachnai <m.shachnai@rutgers.edu>
Co-developed-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Co-developed-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Matan Shachnai <m.shachnai@rutgers.edu>
Signed-off-by: Srinivas Narayana <srinivas.narayana@rutgers.edu>
Signed-off-by: Santosh Nagarakatte <santosh.nagarakatte@rutgers.edu>
Signed-off-by: Harishankar Vishwanathan <harishankar.vishwanathan@rutgers.edu>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://arxiv.org/abs/2105.05398
Link: https://lore.kernel.org/bpf/20210531020157.7386-1-harishankar.vishwanathan@rutgers.edu
As Colin pointed out, the first drops assignment after declaration will
be overwritten by the second drops assignment before using, which makes
it useless.
Since the drops variable will be used only once. Just remove it and
use "cnt - sent" in trace_xdp_devmap_xmit().
Fixes: cb261b594b ("bpf: Run devmap xdp_prog on flush instead of bulk enqueue")
Reported-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210528024356.24333-1-liuhangbin@gmail.com
These macros are convenient wrappers around the bpf_seq_printf and
bpf_snprintf helpers. They are currently provided by bpf_tracing.h which
targets low level tracing primitives. bpf_helpers.h is a better fit.
The __bpf_narg and __bpf_apply are needed in both files and provided
twice. __bpf_empty isn't used anywhere and is removed from bpf_tracing.h
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210526164643.2881368-1-revest@chromium.org
This patch adds two flags BPF_F_BROADCAST and BPF_F_EXCLUDE_INGRESS to
extend xdp_redirect_map for broadcast support.
With BPF_F_BROADCAST the packet will be broadcasted to all the interfaces
in the map. with BPF_F_EXCLUDE_INGRESS the ingress interface will be
excluded when do broadcasting.
When getting the devices in dev hash map via dev_map_hash_get_next_key(),
there is a possibility that we fall back to the first key when a device
was removed. This will duplicate packets on some interfaces. So just walk
the whole buckets to avoid this issue. For dev array map, we also walk the
whole map to find valid interfaces.
Function bpf_clear_redirect_map() was removed in
commit ee75aef23a ("bpf, xdp: Restructure redirect actions").
Add it back as we need to use ri->map again.
With test topology:
+-------------------+ +-------------------+
| Host A (i40e 10G) | ---------- | eno1(i40e 10G) |
+-------------------+ | |
| Host B |
+-------------------+ | |
| Host C (i40e 10G) | ---------- | eno2(i40e 10G) |
+-------------------+ | |
| +------+ |
| veth0 -- | Peer | |
| veth1 -- | | |
| veth2 -- | NS | |
| +------+ |
+-------------------+
On Host A:
# pktgen/pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -s 64
On Host B(Intel(R) Xeon(R) CPU E5-2690 v3 @ 2.60GHz, 128G Memory):
Use xdp_redirect_map and xdp_redirect_map_multi in samples/bpf for testing.
All the veth peers in the NS have a XDP_DROP program loaded. The
forward_map max_entries in xdp_redirect_map_multi is modify to 4.
Testing the performance impact on the regular xdp_redirect path with and
without patch (to check impact of additional check for broadcast mode):
5.12 rc4 | redirect_map i40e->i40e | 2.0M | 9.7M
5.12 rc4 | redirect_map i40e->veth | 1.7M | 11.8M
5.12 rc4 + patch | redirect_map i40e->i40e | 2.0M | 9.6M
5.12 rc4 + patch | redirect_map i40e->veth | 1.7M | 11.7M
Testing the performance when cloning packets with the redirect_map_multi
test, using a redirect map size of 4, filled with 1-3 devices:
5.12 rc4 + patch | redirect_map multi i40e->veth (x1) | 1.7M | 11.4M
5.12 rc4 + patch | redirect_map multi i40e->veth (x2) | 1.1M | 4.3M
5.12 rc4 + patch | redirect_map multi i40e->veth (x3) | 0.8M | 2.6M
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/20210519090747.1655268-3-liuhangbin@gmail.com
This changes the devmap XDP program support to run the program when the
bulk queue is flushed instead of before the frame is enqueued. This has
a couple of benefits:
- It "sorts" the packets by destination devmap entry, and then runs the
same BPF program on all the packets in sequence. This ensures that we
keep the XDP program and destination device properties hot in I-cache.
- It makes the multicast implementation simpler because it can just
enqueue packets using bq_enqueue() without having to deal with the
devmap program at all.
The drawback is that if the devmap program drops the packet, the enqueue
step is redundant. However, arguably this is mostly visible in a
micro-benchmark, and with more mixed traffic the I-cache benefit should
win out. The performance impact of just this patch is as follows:
Using 2 10Gb i40e NIC, redirecting one to another, or into a veth interface,
which do XDP_DROP on veth peer. With xdp_redirect_map in sample/bpf, send
pkts via pktgen cmd:
./pktgen_sample03_burst_single_flow.sh -i eno1 -d $dst_ip -m $dst_mac -t 10 -s 64
There are about +/- 0.1M deviation for native testing, the performance
improved for the base-case, but some drop back with xdp devmap prog attached.
Version | Test | Generic | Native | Native + 2nd xdp_prog
5.12 rc4 | xdp_redirect_map i40e->i40e | 1.9M | 9.6M | 8.4M
5.12 rc4 | xdp_redirect_map i40e->veth | 1.7M | 11.7M | 9.8M
5.12 rc4 + patch | xdp_redirect_map i40e->i40e | 1.9M | 9.8M | 8.0M
5.12 rc4 + patch | xdp_redirect_map i40e->veth | 1.7M | 12.0M | 9.4M
When bq_xmit_all() is called from bq_enqueue(), another packet will
always be enqueued immediately after, so clearing dev_rx, xdp_prog and
flush_node in bq_xmit_all() is redundant. Move the clear to __dev_flush(),
and only check them once in bq_enqueue() since they are all modified
together.
This change also has the side effect of extending the lifetime of the
RCU-protected xdp_prog that lives inside the devmap entries: Instead of
just living for the duration of the XDP program invocation, the
reference now lives all the way until the bq is flushed. This is safe
because the bq flush happens at the end of the NAPI poll loop, so
everything happens between a local_bh_disable()/local_bh_enable() pair.
However, this is by no means obvious from looking at the call sites; in
particular, some drivers have an additional rcu_read_lock() around only
the XDP program invocation, which only confuses matters further.
Cleaning this up will be done in a separate patch series.
Signed-off-by: Jesper Dangaard Brouer <brouer@redhat.com>
Signed-off-by: Hangbin Liu <liuhangbin@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210519090747.1655268-2-liuhangbin@gmail.com
In 801c6058d1 ("bpf: Fix leakage of uninitialized bpf stack under
speculation") we replaced masking logic with direct loads of immediates
if the register is a known constant. Given in this case we do not apply
any masking, there is also no reason for the operation to be truncated
under the speculative domain.
Therefore, there is also zero reason for the verifier to branch-off and
simulate this case, it only needs to do it for unknown but bounded scalars.
As a side-effect, this also enables few test cases that were previously
rejected due to simulation under zero truncation.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Masking direction as indicated via mask_to_left is considered to be
calculated once and then used to derive pointer limits. Thus, this
needs to be placed into bpf_sanitize_info instead so we can pass it
to sanitize_ptr_alu() call after the pointer move. Piotr noticed a
corner case where the off reg causes masking direction change which
then results in an incorrect final aux->alu_limit.
Fixes: 7fedb63a83 ("bpf: Tighten speculative pointer arithmetic mask")
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Add a container structure struct bpf_sanitize_info which holds
the current aux info, and update call-sites to sanitize_ptr_alu()
to pass it in. This is needed for passing in additional state
later on.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Similarly as 6bdacdb48e ("bpf: Fix BPF_JIT kconfig symbol dependency") we
need to detangle the hard BPF_LSM dependency on NET. This was previously
implicit by its dependency on BPF_JIT which itself was dependent on NET (but
without any actual/real hard dependency code-wise). Given the latter was
lifted, so should be the former as BPF_LSMs could well exist on net-less
systems. This therefore also fixes a randconfig build error recently reported
by Randy:
ld: kernel/bpf/bpf_lsm.o: in function `bpf_lsm_func_proto':
bpf_lsm.c:(.text+0x1a0): undefined reference to `bpf_sk_storage_get_proto'
ld: bpf_lsm.c:(.text+0x1b8): undefined reference to `bpf_sk_storage_delete_proto'
[...]
Fixes: b24abcff91 ("bpf, kconfig: Add consolidated menu entry for bpf with core options")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
Fix some spelling mistakes in comments:
aother ==> another
Netiher ==> Neither
desribe ==> describe
intializing ==> initializing
funciton ==> function
wont ==> won't and move the word 'the' at the end to the next line
accross ==> across
pathes ==> paths
triggerred ==> triggered
excute ==> execute
ether ==> either
conervative ==> conservative
convetion ==> convention
markes ==> marks
interpeter ==> interpreter
Signed-off-by: Zhen Lei <thunder.leizhen@huawei.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210525025659.8898-2-thunder.leizhen@huawei.com
Extend the existing bpf_map_lookup_and_delete_elem() functionality to
hashtab map types, in addition to stacks and queues.
Create a new hashtab bpf_map_ops function that does lookup and deletion
of the element under the same bucket lock and add the created map_ops to
bpf.h.
Signed-off-by: Denis Salopek <denis.salopek@sartura.hr>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/4d18480a3e990ffbf14751ddef0325eed3be2966.1620763117.git.denis.salopek@sartura.hr
Commit 4976b718c3 ("bpf: Introduce pseudo_btf_id") switched the
order of resolve_pseudo_ldimm(), in which some pseudo instructions
are rewritten. Thus those rewritten instructions cannot be passed
to driver via 'prepare' offload callback.
Reorder the 'prepare' offload callback to fix it.
Fixes: 4976b718c3 ("bpf: Introduce pseudo_btf_id")
Signed-off-by: Yinjun Zhang <yinjun.zhang@corigine.com>
Signed-off-by: Simon Horman <simon.horman@netronome.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210520085834.15023-1-simon.horman@netronome.com
The cppcheck static code analysis reported the following error:
if (WARN_ON_ONCE(nest_level > ARRAY_SIZE(bufs->tmp_bufs))) {
^
ARRAY_SIZE is a macro that expands to sizeofs, so bufs is not actually
dereferenced at runtime, and the code is actually safe. But to keep
things tidy, this patch removes the need for a call to ARRAY_SIZE by
extracting the size of the array into a macro. Cppcheck should no longer
be confused and the code ends up being a bit cleaner.
Fixes: e2d5b2bb76 ("bpf: Fix nested bpf_bprintf_prepare with more per-cpu buffers")
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20210517092830.1026418-2-revest@chromium.org
The per-cpu buffers contain bprintf data rather than printf arguments.
The macro name and comment were a bit confusing, this rewords them in a
clearer way.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <song@kernel.org>
Link: https://lore.kernel.org/bpf/20210517092830.1026418-1-revest@chromium.org
Randy reported a randconfig build error recently on i386:
ld: arch/x86/net/bpf_jit_comp32.o: in function `do_jit':
bpf_jit_comp32.c:(.text+0x28c9): undefined reference to `__bpf_call_base'
ld: arch/x86/net/bpf_jit_comp32.o: in function `bpf_int_jit_compile':
bpf_jit_comp32.c:(.text+0x3694): undefined reference to `bpf_jit_blind_constants'
ld: bpf_jit_comp32.c:(.text+0x3719): undefined reference to `bpf_jit_binary_free'
ld: bpf_jit_comp32.c:(.text+0x3745): undefined reference to `bpf_jit_binary_alloc'
ld: bpf_jit_comp32.c:(.text+0x37d3): undefined reference to `bpf_jit_prog_release_other'
[...]
The cause was that b24abcff91 ("bpf, kconfig: Add consolidated menu entry for
bpf with core options") moved BPF_JIT from net/Kconfig into kernel/bpf/Kconfig
and previously BPF_JIT was guarded by a 'if NET'. However, there is no actual
dependency on NET, it's just that menuconfig NET selects BPF. And the latter in
turn causes kernel/bpf/core.o to be built which contains above symbols. Randy's
randconfig didn't have NET set, and BPF wasn't either, but BPF_JIT otoh was.
Detangle this by making BPF_JIT depend on BPF instead. arm64 was the only arch
that pulled in its JIT in net/ via obj-$(CONFIG_NET), all others unconditionally
pull this dir in via obj-y. Do the same since CONFIG_NET guard there is really
useless as we compiled the JIT via obj-$(CONFIG_BPF_JIT) += bpf_jit_comp.o anyway.
Fixes: b24abcff91 ("bpf, kconfig: Add consolidated menu entry for bpf with core options")
Reported-by: Randy Dunlap <rdunlap@infradead.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Randy Dunlap <rdunlap@infradead.org>
Tested-by: Randy Dunlap <rdunlap@infradead.org>
The sparse tool complains as follows:
kernel/bpf/syscall.c:4567:29: warning:
symbol 'bpf_sys_bpf_proto' was not declared. Should it be static?
kernel/bpf/syscall.c:4592:29: warning:
symbol 'bpf_sys_close_proto' was not declared. Should it be static?
This symbol is not used outside of syscall.c, so marks it static.
Signed-off-by: Pu Lehui <pulehui@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210519064116.240536-1-pulehui@huawei.com
Add bpf_sys_close() helper to be used by the syscall/loader program to close
intermediate FDs and other cleanup.
Note this helper must never be allowed inside fdget/fdput bracketing.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-11-alexei.starovoitov@gmail.com
Add new helper:
long bpf_btf_find_by_name_kind(char *name, int name_sz, u32 kind, int flags)
Description
Find BTF type with given name and kind in vmlinux BTF or in module's BTFs.
Return
Returns btf_id and btf_obj_fd in lower and upper 32 bits.
It will be used by loader program to find btf_id to attach the program to
and to find btf_ids of ksyms.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-10-alexei.starovoitov@gmail.com
Typical program loading sequence involves creating bpf maps and applying
map FDs into bpf instructions in various places in the bpf program.
This job is done by libbpf that is using compiler generated ELF relocations
to patch certain instruction after maps are created and BTFs are loaded.
The goal of fd_idx is to allow bpf instructions to stay immutable
after compilation. At load time the libbpf would still create maps as usual,
but it wouldn't need to patch instructions. It would store map_fds into
__u32 fd_array[] and would pass that pointer to sys_bpf(BPF_PROG_LOAD).
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-9-alexei.starovoitov@gmail.com
Similar to prog_load make btf_load command to be availble to
bpf_prog_type_syscall program.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-7-alexei.starovoitov@gmail.com
With the help from bpfptr_t prepare relevant bpf syscall commands
to be used from kernel and user space.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-4-alexei.starovoitov@gmail.com
Add placeholders for bpf_sys_bpf() helper and new program type.
Make sure to check that expected_attach_type is zero for future extensibility.
Allow tracing helper functions to be used in this program type, since they will
only execute from user context via bpf_prog_test_run.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210514003623.28033-2-alexei.starovoitov@gmail.com
The bpf_seq_printf, bpf_trace_printk and bpf_snprintf helpers share one
per-cpu buffer that they use to store temporary data (arguments to
bprintf). They "get" that buffer with try_get_fmt_tmp_buf and "put" it
by the end of their scope with bpf_bprintf_cleanup.
If one of these helpers gets called within the scope of one of these
helpers, for example: a first bpf program gets called, uses
bpf_trace_printk which calls raw_spin_lock_irqsave which is traced by
another bpf program that calls bpf_snprintf, then the second "get"
fails. Essentially, these helpers are not re-entrant. They would return
-EBUSY and print a warning message once.
This patch triples the number of bprintf buffers to allow three levels
of nesting. This is very similar to what was done for tracepoints in
"9594dc3c7e7 bpf: fix nested bpf tracepoints with per-cpu data"
Fixes: d9c9e4db18 ("bpf: Factorize bpf_trace_printk and bpf_seq_printf")
Reported-by: syzbot+63122d0bc347f18c1884@syzkaller.appspotmail.com
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210511081054.2125874-1-revest@chromium.org
The recursion check in __bpf_prog_enter and __bpf_prog_exit
leaves some (not inlined) functions unprotected:
In __bpf_prog_enter:
- migrate_disable is called before prog->active is checked
In __bpf_prog_exit:
- migrate_enable,rcu_read_unlock_strict are called after
prog->active is decreased
When attaching trampoline to them we get panic like:
traps: PANIC: double fault, error_code: 0x0
double fault: 0000 [#1] SMP PTI
RIP: 0010:__bpf_prog_enter+0x4/0x50
...
Call Trace:
<IRQ>
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
__bpf_prog_enter+0x9/0x50
bpf_trampoline_6442466513_0+0x18/0x1000
migrate_disable+0x5/0x50
...
Fixing this by adding deny list of btf ids for tracing
programs and checking btf id during program verification.
Adding above functions to this list.
Suggested-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210429114712.43783-1-jolsa@kernel.org
Add a kconfig knob which allows for unprivileged bpf to be disabled by default.
If set, the knob sets /proc/sys/kernel/unprivileged_bpf_disabled to value of 2.
This still allows a transition of 2 -> {0,1} through an admin. Similarly,
this also still keeps 1 -> {1} behavior intact, so that once set to permanently
disabled, it cannot be undone aside from a reboot.
We've also added extra2 with max of 2 for the procfs handler, so that an admin
still has a chance to toggle between 0 <-> 2.
Either way, as an additional alternative, applications can make use of CAP_BPF
that we added a while ago.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/74ec548079189e4e4dffaeb42b8987bb3c852eee.1620765074.git.daniel@iogearbox.net
Right now, all core BPF related options are scattered in different Kconfig
locations mainly due to historic reasons. Moving forward, lets add a proper
subsystem entry under ...
General setup --->
BPF subsystem --->
... in order to have all knobs in a single location and thus ease BPF related
configuration. Networking related bits such as sockmap are out of scope for
the general setup and therefore better suited to remain in net/Kconfig.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/f23f58765a4d59244ebd8037da7b6a6b2fb58446.1620765074.git.daniel@iogearbox.net
Only the very first page of BPF ringbuf that contains consumer position
counter is supposed to be mapped as writeable by user-space. Producer
position is read-only and can be modified only by the kernel code. BPF ringbuf
data pages are read-only as well and are not meant to be modified by
user-code to maintain integrity of per-record headers.
This patch allows to map only consumer position page as writeable and
everything else is restricted to be read-only. remap_vmalloc_range()
internally adds VM_DONTEXPAND, so all the established memory mappings can't be
extended, which prevents any future violations through mremap()'ing.
Fixes: 457f44363a ("bpf: Implement BPF ring buffer and verifier support for it")
Reported-by: Ryota Shiga (Flatt Security)
Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
A BPF program might try to reserve a buffer larger than the ringbuf size.
If the consumer pointer is way ahead of the producer, that would be
successfully reserved, allowing the BPF program to read or write out of
the ringbuf allocated area.
Reported-by: Ryota Shiga (Flatt Security)
Fixes: 457f44363a ("bpf: Implement BPF ring buffer and verifier support for it")
Signed-off-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Fix a bug in the verifier's scalar32_min_max_*() functions which leads to
incorrect tracking of 32 bit bounds for the simulation of and/or/xor bitops.
When both the src & dst subreg is a known constant, then the assumption is
that scalar_min_max_*() will take care to update bounds correctly. However,
this is not the case, for example, consider a register R2 which has a tnum
of 0xffffffff00000000, meaning, lower 32 bits are known constant and in this
case of value 0x00000001. R2 is then and'ed with a register R3 which is a
64 bit known constant, here, 0x100000002.
What can be seen in line '10:' is that 32 bit bounds reach an invalid state
where {u,s}32_min_value > {u,s}32_max_value. The reason is scalar32_min_max_*()
delegates 32 bit bounds updates to scalar_min_max_*(), however, that really
only takes place when both the 64 bit src & dst register is a known constant.
Given scalar32_min_max_*() is intended to be designed as closely as possible
to scalar_min_max_*(), update the 32 bit bounds in this situation through
__mark_reg32_known() which will set all {u,s}32_{min,max}_value to the correct
constant, which is 0x00000000 after the fix (given 0x00000001 & 0x00000002 in
32 bit space). This is possible given var32_off already holds the final value
as dst_reg->var_off is updated before calling scalar32_min_max_*().
Before fix, invalid tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=1,s32_max_value=0,u32_min_value=1,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
After fix, correct tracking of R2:
[...]
9: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=-9223372036854775807 (0x8000000000000001),smax_value=9223372032559808513 (0x7fffffff00000001),umin_value=1,umax_value=0xffffffff00000001,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_min_value=1,u32_max_value=1) R3_w=inv4294967298 R10=fp0
9: (5f) r2 &= r3
10: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,smin_value=0,smax_value=4294967296 (0x100000000),umin_value=0,umax_value=0x100000000,var_off=(0x0; 0x100000000),s32_min_value=0,s32_max_value=0,u32_min_value=0,u32_max_value=0) R3_w=inv4294967298 R10=fp0
[...]
Fixes: 3f50f132d8 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Fixes: 2921c90d47 ("bpf: Fix a verifier failure with xor")
Reported-by: Manfred Paul (@_manfp)
Reported-by: Thadeu Lima de Souza Cascardo <cascardo@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
func_states_equal makes a very short lived allocation for idmap,
probably because it's too large to fit on the stack. However the
function is called quite often, leading to a lot of alloc / free
churn. Replace the temporary allocation with dedicated scratch
space in struct bpf_verifier_env.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Link: https://lore.kernel.org/bpf/20210429134656.122225-4-lmb@cloudflare.com
Resizing and copying stack and reference tracking state currently
does a lot of kfree / kmalloc when the size of the tracked set changes.
The logic in copy_*_state and realloc_*_state is also hard to follow.
Refactor this into two core functions. copy_array copies from a source
into a destination. It avoids reallocation by taking the allocated
size of the destination into account via ksize(). The function is
essentially krealloc_array, with the difference that the contents of
dst are not preserved. realloc_array changes the size of an array and
zeroes newly allocated items. Contrary to krealloc both functions don't
free the destination if the size is zero. Instead we rely on free_func_state
to clean up.
realloc_stack_state is renamed to grow_stack_state to better convey
that it never shrinks the stack state.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210429134656.122225-2-lmb@cloudflare.com
We can't currently allow to attach functions with variable arguments.
The problem is that we should save all the registers for arguments,
which is probably doable, but if caller uses more than 6 arguments,
we need stack data, which will be wrong, because of the extra stack
frame we do in bpf trampoline, so we could crash.
Also currently there's malformed trampoline code generated for such
functions at the moment as described in:
https://lore.kernel.org/bpf/20210429212834.82621-1-jolsa@kernel.org/
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210505132529.401047-1-jolsa@kernel.org
The current implemented mechanisms to mitigate data disclosure under
speculation mainly address stack and map value oob access from the
speculative domain. However, Piotr discovered that uninitialized BPF
stack is not protected yet, and thus old data from the kernel stack,
potentially including addresses of kernel structures, could still be
extracted from that 512 bytes large window. The BPF stack is special
compared to map values since it's not zero initialized for every
program invocation, whereas map values /are/ zero initialized upon
their initial allocation and thus cannot leak any prior data in either
domain. In the non-speculative domain, the verifier ensures that every
stack slot read must have a prior stack slot write by the BPF program
to avoid such data leaking issue.
However, this is not enough: for example, when the pointer arithmetic
operation moves the stack pointer from the last valid stack offset to
the first valid offset, the sanitation logic allows for any intermediate
offsets during speculative execution, which could then be used to
extract any restricted stack content via side-channel.
Given for unprivileged stack pointer arithmetic the use of unknown
but bounded scalars is generally forbidden, we can simply turn the
register-based arithmetic operation into an immediate-based arithmetic
operation without the need for masking. This also gives the benefit
of reducing the needed instructions for the operation. Given after
the work in 7fedb63a83 ("bpf: Tighten speculative pointer arithmetic
mask"), the aux->alu_limit already holds the final immediate value for
the offset register with the known scalar. Thus, a simple mov of the
immediate to AX register with using AX as the source for the original
instruction is sufficient and possible now in this case.
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
The negation logic for the case where the off_reg is sitting in the
dst register is not correct given then we cannot just invert the add
to a sub or vice versa. As a fix, perform the final bitwise and-op
unconditionally into AX from the off_reg, then move the pointer from
the src to dst and finally use AX as the source for the original
pointer arithmetic operation such that the inversion yields a correct
result. The single non-AX mov in between is possible given constant
blinding is retaining it as it's not an immediate based operation.
Fixes: 979d63d50c ("bpf: prevent out of bounds speculation on pointer arithmetic")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Tested-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: Piotr Krysiuk <piotras@gmail.com>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Core:
- bpf:
- allow bpf programs calling kernel functions (initially to
reuse TCP congestion control implementations)
- enable task local storage for tracing programs - remove the
need to store per-task state in hash maps, and allow tracing
programs access to task local storage previously added for
BPF_LSM
- add bpf_for_each_map_elem() helper, allowing programs to
walk all map elements in a more robust and easier to verify
fashion
- sockmap: support UDP and cross-protocol BPF_SK_SKB_VERDICT
redirection
- lpm: add support for batched ops in LPM trie
- add BTF_KIND_FLOAT support - mostly to allow use of BTF
on s390 which has floats in its headers files
- improve BPF syscall documentation and extend the use of kdoc
parsing scripts we already employ for bpf-helpers
- libbpf, bpftool: support static linking of BPF ELF files
- improve support for encapsulation of L2 packets
- xdp: restructure redirect actions to avoid a runtime lookup,
improving performance by 4-8% in microbenchmarks
- xsk: build skb by page (aka generic zerocopy xmit) - improve
performance of software AF_XDP path by 33% for devices
which don't need headers in the linear skb part (e.g. virtio)
- nexthop: resilient next-hop groups - improve path stability
on next-hops group changes (incl. offload for mlxsw)
- ipv6: segment routing: add support for IPv4 decapsulation
- icmp: add support for RFC 8335 extended PROBE messages
- inet: use bigger hash table for IP ID generation
- tcp: deal better with delayed TX completions - make sure we don't
give up on fast TCP retransmissions only because driver is
slow in reporting that it completed transmitting the original
- tcp: reorder tcp_congestion_ops for better cache locality
- mptcp:
- add sockopt support for common TCP options
- add support for common TCP msg flags
- include multiple address ids in RM_ADDR
- add reset option support for resetting one subflow
- udp: GRO L4 improvements - improve 'forward' / 'frag_list'
co-existence with UDP tunnel GRO, allowing the first to take
place correctly even for encapsulated UDP traffic
- micro-optimize dev_gro_receive() and flow dissection, avoid
retpoline overhead on VLAN and TEB GRO
- use less memory for sysctls, add a new sysctl type, to allow using
u8 instead of "int" and "long" and shrink networking sysctls
- veth: allow GRO without XDP - this allows aggregating UDP
packets before handing them off to routing, bridge, OvS, etc.
- allow specifing ifindex when device is moved to another namespace
- netfilter:
- nft_socket: add support for cgroupsv2
- nftables: add catch-all set element - special element used
to define a default action in case normal lookup missed
- use net_generic infra in many modules to avoid allocating
per-ns memory unnecessarily
- xps: improve the xps handling to avoid potential out-of-bound
accesses and use-after-free when XPS change race with other
re-configuration under traffic
- add a config knob to turn off per-cpu netdev refcnt to catch
underflows in testing
Device APIs:
- add WWAN subsystem to organize the WWAN interfaces better and
hopefully start driving towards more unified and vendor-
-independent APIs
- ethtool:
- add interface for reading IEEE MIB stats (incl. mlx5 and
bnxt support)
- allow network drivers to dump arbitrary SFP EEPROM data,
current offset+length API was a poor fit for modern SFP
which define EEPROM in terms of pages (incl. mlx5 support)
- act_police, flow_offload: add support for packet-per-second
policing (incl. offload for nfp)
- psample: add additional metadata attributes like transit delay
for packets sampled from switch HW (and corresponding egress
and policy-based sampling in the mlxsw driver)
- dsa: improve support for sandwiched LAGs with bridge and DSA
- netfilter:
- flowtable: use direct xmit in topologies with IP
forwarding, bridging, vlans etc.
- nftables: counter hardware offload support
- Bluetooth:
- improvements for firmware download w/ Intel devices
- add support for reading AOSP vendor capabilities
- add support for virtio transport driver
- mac80211:
- allow concurrent monitor iface and ethernet rx decap
- set priority and queue mapping for injected frames
- phy: add support for Clause-45 PHY Loopback
- pci/iov: add sysfs MSI-X vector assignment interface
to distribute MSI-X resources to VFs (incl. mlx5 support)
New hardware/drivers:
- dsa: mv88e6xxx: add support for Marvell mv88e6393x -
11-port Ethernet switch with 8x 1-Gigabit Ethernet
and 3x 10-Gigabit interfaces.
- dsa: support for legacy Broadcom tags used on BCM5325, BCM5365
and BCM63xx switches
- Microchip KSZ8863 and KSZ8873; 3x 10/100Mbps Ethernet switches
- ath11k: support for QCN9074 a 802.11ax device
- Bluetooth: Broadcom BCM4330 and BMC4334
- phy: Marvell 88X2222 transceiver support
- mdio: add BCM6368 MDIO mux bus controller
- r8152: support RTL8153 and RTL8156 (USB Ethernet) chips
- mana: driver for Microsoft Azure Network Adapter (MANA)
- Actions Semi Owl Ethernet MAC
- can: driver for ETAS ES58X CAN/USB interfaces
Pure driver changes:
- add XDP support to: enetc, igc, stmmac
- add AF_XDP support to: stmmac
- virtio:
- page_to_skb() use build_skb when there's sufficient tailroom
(21% improvement for 1000B UDP frames)
- support XDP even without dedicated Tx queues - share the Tx
queues with the stack when necessary
- mlx5:
- flow rules: add support for mirroring with conntrack,
matching on ICMP, GTP, flex filters and more
- support packet sampling with flow offloads
- persist uplink representor netdev across eswitch mode
changes
- allow coexistence of CQE compression and HW time-stamping
- add ethtool extended link error state reporting
- ice, iavf: support flow filters, UDP Segmentation Offload
- dpaa2-switch:
- move the driver out of staging
- add spanning tree (STP) support
- add rx copybreak support
- add tc flower hardware offload on ingress traffic
- ionic:
- implement Rx page reuse
- support HW PTP time-stamping
- octeon: support TC hardware offloads - flower matching on ingress
and egress ratelimitting.
- stmmac:
- add RX frame steering based on VLAN priority in tc flower
- support frame preemption (FPE)
- intel: add cross time-stamping freq difference adjustment
- ocelot:
- support forwarding of MRP frames in HW
- support multiple bridges
- support PTP Sync one-step timestamping
- dsa: mv88e6xxx, dpaa2-switch: offload bridge port flags like
learning, flooding etc.
- ipa: add IPA v4.5, v4.9 and v4.11 support (Qualcomm SDX55, SM8350,
SC7280 SoCs)
- mt7601u: enable TDLS support
- mt76:
- add support for 802.3 rx frames (mt7915/mt7615)
- mt7915 flash pre-calibration support
- mt7921/mt7663 runtime power management fixes
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
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Merge tag 'net-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next
Pull networking updates from Jakub Kicinski:
"Core:
- bpf:
- allow bpf programs calling kernel functions (initially to
reuse TCP congestion control implementations)
- enable task local storage for tracing programs - remove the
need to store per-task state in hash maps, and allow tracing
programs access to task local storage previously added for
BPF_LSM
- add bpf_for_each_map_elem() helper, allowing programs to walk
all map elements in a more robust and easier to verify fashion
- sockmap: support UDP and cross-protocol BPF_SK_SKB_VERDICT
redirection
- lpm: add support for batched ops in LPM trie
- add BTF_KIND_FLOAT support - mostly to allow use of BTF on
s390 which has floats in its headers files
- improve BPF syscall documentation and extend the use of kdoc
parsing scripts we already employ for bpf-helpers
- libbpf, bpftool: support static linking of BPF ELF files
- improve support for encapsulation of L2 packets
- xdp: restructure redirect actions to avoid a runtime lookup,
improving performance by 4-8% in microbenchmarks
- xsk: build skb by page (aka generic zerocopy xmit) - improve
performance of software AF_XDP path by 33% for devices which don't
need headers in the linear skb part (e.g. virtio)
- nexthop: resilient next-hop groups - improve path stability on
next-hops group changes (incl. offload for mlxsw)
- ipv6: segment routing: add support for IPv4 decapsulation
- icmp: add support for RFC 8335 extended PROBE messages
- inet: use bigger hash table for IP ID generation
- tcp: deal better with delayed TX completions - make sure we don't
give up on fast TCP retransmissions only because driver is slow in
reporting that it completed transmitting the original
- tcp: reorder tcp_congestion_ops for better cache locality
- mptcp:
- add sockopt support for common TCP options
- add support for common TCP msg flags
- include multiple address ids in RM_ADDR
- add reset option support for resetting one subflow
- udp: GRO L4 improvements - improve 'forward' / 'frag_list'
co-existence with UDP tunnel GRO, allowing the first to take place
correctly even for encapsulated UDP traffic
- micro-optimize dev_gro_receive() and flow dissection, avoid
retpoline overhead on VLAN and TEB GRO
- use less memory for sysctls, add a new sysctl type, to allow using
u8 instead of "int" and "long" and shrink networking sysctls
- veth: allow GRO without XDP - this allows aggregating UDP packets
before handing them off to routing, bridge, OvS, etc.
- allow specifing ifindex when device is moved to another namespace
- netfilter:
- nft_socket: add support for cgroupsv2
- nftables: add catch-all set element - special element used to
define a default action in case normal lookup missed
- use net_generic infra in many modules to avoid allocating
per-ns memory unnecessarily
- xps: improve the xps handling to avoid potential out-of-bound
accesses and use-after-free when XPS change race with other
re-configuration under traffic
- add a config knob to turn off per-cpu netdev refcnt to catch
underflows in testing
Device APIs:
- add WWAN subsystem to organize the WWAN interfaces better and
hopefully start driving towards more unified and vendor-
independent APIs
- ethtool:
- add interface for reading IEEE MIB stats (incl. mlx5 and bnxt
support)
- allow network drivers to dump arbitrary SFP EEPROM data,
current offset+length API was a poor fit for modern SFP which
define EEPROM in terms of pages (incl. mlx5 support)
- act_police, flow_offload: add support for packet-per-second
policing (incl. offload for nfp)
- psample: add additional metadata attributes like transit delay for
packets sampled from switch HW (and corresponding egress and
policy-based sampling in the mlxsw driver)
- dsa: improve support for sandwiched LAGs with bridge and DSA
- netfilter:
- flowtable: use direct xmit in topologies with IP forwarding,
bridging, vlans etc.
- nftables: counter hardware offload support
- Bluetooth:
- improvements for firmware download w/ Intel devices
- add support for reading AOSP vendor capabilities
- add support for virtio transport driver
- mac80211:
- allow concurrent monitor iface and ethernet rx decap
- set priority and queue mapping for injected frames
- phy: add support for Clause-45 PHY Loopback
- pci/iov: add sysfs MSI-X vector assignment interface to distribute
MSI-X resources to VFs (incl. mlx5 support)
New hardware/drivers:
- dsa: mv88e6xxx: add support for Marvell mv88e6393x - 11-port
Ethernet switch with 8x 1-Gigabit Ethernet and 3x 10-Gigabit
interfaces.
- dsa: support for legacy Broadcom tags used on BCM5325, BCM5365 and
BCM63xx switches
- Microchip KSZ8863 and KSZ8873; 3x 10/100Mbps Ethernet switches
- ath11k: support for QCN9074 a 802.11ax device
- Bluetooth: Broadcom BCM4330 and BMC4334
- phy: Marvell 88X2222 transceiver support
- mdio: add BCM6368 MDIO mux bus controller
- r8152: support RTL8153 and RTL8156 (USB Ethernet) chips
- mana: driver for Microsoft Azure Network Adapter (MANA)
- Actions Semi Owl Ethernet MAC
- can: driver for ETAS ES58X CAN/USB interfaces
Pure driver changes:
- add XDP support to: enetc, igc, stmmac
- add AF_XDP support to: stmmac
- virtio:
- page_to_skb() use build_skb when there's sufficient tailroom
(21% improvement for 1000B UDP frames)
- support XDP even without dedicated Tx queues - share the Tx
queues with the stack when necessary
- mlx5:
- flow rules: add support for mirroring with conntrack, matching
on ICMP, GTP, flex filters and more
- support packet sampling with flow offloads
- persist uplink representor netdev across eswitch mode changes
- allow coexistence of CQE compression and HW time-stamping
- add ethtool extended link error state reporting
- ice, iavf: support flow filters, UDP Segmentation Offload
- dpaa2-switch:
- move the driver out of staging
- add spanning tree (STP) support
- add rx copybreak support
- add tc flower hardware offload on ingress traffic
- ionic:
- implement Rx page reuse
- support HW PTP time-stamping
- octeon: support TC hardware offloads - flower matching on ingress
and egress ratelimitting.
- stmmac:
- add RX frame steering based on VLAN priority in tc flower
- support frame preemption (FPE)
- intel: add cross time-stamping freq difference adjustment
- ocelot:
- support forwarding of MRP frames in HW
- support multiple bridges
- support PTP Sync one-step timestamping
- dsa: mv88e6xxx, dpaa2-switch: offload bridge port flags like
learning, flooding etc.
- ipa: add IPA v4.5, v4.9 and v4.11 support (Qualcomm SDX55, SM8350,
SC7280 SoCs)
- mt7601u: enable TDLS support
- mt76:
- add support for 802.3 rx frames (mt7915/mt7615)
- mt7915 flash pre-calibration support
- mt7921/mt7663 runtime power management fixes"
* tag 'net-next-5.13' of git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net-next: (2451 commits)
net: selftest: fix build issue if INET is disabled
net: netrom: nr_in: Remove redundant assignment to ns
net: tun: Remove redundant assignment to ret
net: phy: marvell: add downshift support for M88E1240
net: dsa: ksz: Make reg_mib_cnt a u8 as it never exceeds 255
net/sched: act_ct: Remove redundant ct get and check
icmp: standardize naming of RFC 8335 PROBE constants
bpf, selftests: Update array map tests for per-cpu batched ops
bpf: Add batched ops support for percpu array
bpf: Implement formatted output helpers with bstr_printf
seq_file: Add a seq_bprintf function
sfc: adjust efx->xdp_tx_queue_count with the real number of initialized queues
net:nfc:digital: Fix a double free in digital_tg_recv_dep_req
net: fix a concurrency bug in l2tp_tunnel_register()
net/smc: Remove redundant assignment to rc
mpls: Remove redundant assignment to err
llc2: Remove redundant assignment to rc
net/tls: Remove redundant initialization of record
rds: Remove redundant assignment to nr_sig
dt-bindings: net: mdio-gpio: add compatible for microchip,mdio-smi0
...
Uses the already in-place infrastructure provided by the
'generic_map_*_batch' functions.
No tweak was needed as it transparently handles the percpu variant.
As arrays don't have delete operations, let it return a error to
user space (default behaviour).
Suggested-by: Jamal Hadi Salim <jhs@mojatatu.com>
Signed-off-by: Pedro Tammela <pctammela@mojatatu.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210424214510.806627-2-pctammela@mojatatu.com
BPF has three formatted output helpers: bpf_trace_printk, bpf_seq_printf
and bpf_snprintf. Their signatures specify that all arguments are
provided from the BPF world as u64s (in an array or as registers). All
of these helpers are currently implemented by calling functions such as
snprintf() whose signatures take a variable number of arguments, then
placed in a va_list by the compiler to call vsnprintf().
"d9c9e4db bpf: Factorize bpf_trace_printk and bpf_seq_printf" introduced
a bpf_printf_prepare function that fills an array of u64 sanitized
arguments with an array of "modifiers" which indicate what the "real"
size of each argument should be (given by the format specifier). The
BPF_CAST_FMT_ARG macro consumes these arrays and casts each argument to
its real size. However, the C promotion rules implicitely cast them all
back to u64s. Therefore, the arguments given to snprintf are u64s and
the va_list constructed by the compiler will use 64 bits for each
argument. On 64 bit machines, this happens to work well because 32 bit
arguments in va_lists need to occupy 64 bits anyway, but on 32 bit
architectures this breaks the layout of the va_list expected by the
called function and mangles values.
In "88a5c690b6 bpf: fix bpf_trace_printk on 32 bit archs", this problem
had been solved for bpf_trace_printk only with a "horrid workaround"
that emitted multiple calls to trace_printk where each call had
different argument types and generated different va_list layouts. One of
the call would be dynamically chosen at runtime. This was ok with the 3
arguments that bpf_trace_printk takes but bpf_seq_printf and
bpf_snprintf accept up to 12 arguments. Because this approach scales
code exponentially, it is not a viable option anymore.
Because the promotion rules are part of the language and because the
construction of a va_list is an arch-specific ABI, it's best to just
avoid variadic arguments and va_lists altogether. Thankfully the
kernel's snprintf() has an alternative in the form of bstr_printf() that
accepts arguments in a "binary buffer representation". These binary
buffers are currently created by vbin_printf and used in the tracing
subsystem to split the cost of printing into two parts: a fast one that
only dereferences and remembers values, and a slower one, called later,
that does the pretty-printing.
This patch refactors bpf_printf_prepare to construct binary buffers of
arguments consumable by bstr_printf() instead of arrays of arguments and
modifiers. This gets rid of BPF_CAST_FMT_ARG and greatly simplifies the
bpf_printf_prepare usage but there are a few gotchas that change how
bpf_printf_prepare needs to do things.
Currently, bpf_printf_prepare uses a per cpu temporary buffer as a
generic storage for strings and IP addresses. With this refactoring, the
temporary buffers now holds all the arguments in a structured binary
format.
To comply with the format expected by bstr_printf, certain format
specifiers also need to be pre-formatted: %pB and %pi6/%pi4/%pI4/%pI6.
Because vsnprintf subroutines for these specifiers are hard to expose,
we pre-format these arguments with calls to snprintf().
Reported-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210427174313.860948-3-revest@chromium.org
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Merge tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux
Pull selinux updates from Paul Moore:
- Add support for measuring the SELinux state and policy capabilities
using IMA.
- A handful of SELinux/NFS patches to compare the SELinux state of one
mount with a set of mount options. Olga goes into more detail in the
patch descriptions, but this is important as it allows more
flexibility when using NFS and SELinux context mounts.
- Properly differentiate between the subjective and objective LSM
credentials; including support for the SELinux and Smack. My clumsy
attempt at a proper fix for AppArmor didn't quite pass muster so John
is working on a proper AppArmor patch, in the meantime this set of
patches shouldn't change the behavior of AppArmor in any way. This
change explains the bulk of the diffstat beyond security/.
- Fix a problem where we were not properly terminating the permission
list for two SELinux object classes.
* tag 'selinux-pr-20210426' of git://git.kernel.org/pub/scm/linux/kernel/git/pcmoore/selinux:
selinux: add proper NULL termination to the secclass_map permissions
smack: differentiate between subjective and objective task credentials
selinux: clarify task subjective and objective credentials
lsm: separate security_task_getsecid() into subjective and objective variants
nfs: account for selinux security context when deciding to share superblock
nfs: remove unneeded null check in nfs_fill_super()
lsm,selinux: add new hook to compare new mount to an existing mount
selinux: fix misspellings using codespell tool
selinux: fix misspellings using codespell tool
selinux: measure state and policy capabilities
selinux: Allow context mounts for unpriviliged overlayfs
Rely on netif_receive_skb_list routine to send skbs converted from
xdp_frames in cpu_map_kthread_run in order to improve i-cache usage.
The proposed patch has been tested running xdp_redirect_cpu bpf sample
available in the kernel tree that is used to redirect UDP frames from
ixgbe driver to a cpumap entry and then to the networking stack. UDP
frames are generated using pktgen. Packets are discarded by the UDP
layer.
$ xdp_redirect_cpu --cpu <cpu> --progname xdp_cpu_map0 --dev <eth>
bpf-next: ~2.35Mpps
bpf-next + cpumap skb-list: ~2.72Mpps
Rename drops counter in kmem_alloc_drops since now it reports just
kmem_cache_alloc_bulk failures
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Link: https://lore.kernel.org/bpf/c729f83e5d7482d9329e0f165bdbe5adcefd1510.1619169700.git.lorenzo@kernel.org
Similarly as b02709587e ("bpf: Fix propagation of 32-bit signed bounds
from 64-bit bounds."), we also need to fix the propagation of 32 bit
unsigned bounds from 64 bit counterparts. That is, really only set the
u32_{min,max}_value when /both/ {umin,umax}_value safely fit in 32 bit
space. For example, the register with a umin_value == 1 does /not/ imply
that u32_min_value is also equal to 1, since umax_value could be much
larger than 32 bit subregister can hold, and thus u32_min_value is in
the interval [0,1] instead.
Before fix, invalid tracking result of R2_w=inv1:
[...]
5: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0) R10=fp0
5: (35) if r2 >= 0x1 goto pc+1
[...] // goto path
7: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umin_value=1) R10=fp0
7: (b6) if w2 <= 0x1 goto pc+1
[...] // goto path
9: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,smin_value=-9223372036854775807,smax_value=9223372032559808513,umin_value=1,umax_value=18446744069414584321,var_off=(0x1; 0xffffffff00000000),s32_min_value=1,s32_max_value=1,u32_max_value=1) R10=fp0
9: (bc) w2 = w2
10: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv1 R10=fp0
[...]
After fix, correct tracking result of R2_w=inv(id=0,umax_value=1,var_off=(0x0; 0x1)):
[...]
5: R0_w=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0) R10=fp0
5: (35) if r2 >= 0x1 goto pc+1
[...] // goto path
7: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,umin_value=1) R10=fp0
7: (b6) if w2 <= 0x1 goto pc+1
[...] // goto path
9: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2=inv(id=0,smax_value=9223372032559808513,umax_value=18446744069414584321,var_off=(0x0; 0xffffffff00000001),s32_min_value=0,s32_max_value=1,u32_max_value=1) R10=fp0
9: (bc) w2 = w2
10: R0=inv1337 R1=ctx(id=0,off=0,imm=0) R2_w=inv(id=0,umax_value=1,var_off=(0x0; 0x1)) R10=fp0
[...]
Thus, same issue as in b02709587e holds for unsigned subregister tracking.
Also, align __reg64_bound_u32() similarly to __reg64_bound_s32() as done in
b02709587e to make them uniform again.
Fixes: 3f50f132d8 ("bpf: Verifier, do explicit ALU32 bounds tracking")
Reported-by: Manfred Paul (@_manfp)
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Currently we don't allow re-attaching of trampolines. Once
it's detached, it can't be re-attach even when the program
is still loaded.
Adding the possibility to re-attach the loaded tracing and
lsm programs.
Fixing missing unlock with proper cleanup goto jump reported
by Julia.
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Julia Lawall <julia.lawall@lip6.fr>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210414195147.1624932-2-jolsa@kernel.org
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-04-23
The following pull-request contains BPF updates for your *net-next* tree.
We've added 69 non-merge commits during the last 22 day(s) which contain
a total of 69 files changed, 3141 insertions(+), 866 deletions(-).
The main changes are:
1) Add BPF static linker support for extern resolution of global, from Andrii.
2) Refine retval for bpf_get_task_stack helper, from Dave.
3) Add a bpf_snprintf helper, from Florent.
4) A bunch of miscellaneous improvements from many developers.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
reg->type is enforced by check_reg_type() and map should never be NULL
(it would already have been dereferenced anyway) so these checks are
unnecessary.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210422235543.4007694-3-revest@chromium.org
In check_bpf_snprintf_call(), a map_direct_value_addr() of the fmt map
should never fail because it has already been checked by
ARG_PTR_TO_CONST_STR. But if it ever fails, it's better to error out
with an explicit debug message rather than silently fail.
Reported-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210422235543.4007694-2-revest@chromium.org
Verifier can constrain the min/max bounds of bpf_get_task_stack's return
value more tightly than the default tnum_unknown. Like bpf_get_stack,
return value is num bytes written into a caller-supplied buf, or error,
so do_refine_retval_range will work.
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210416204704.2816874-2-davemarchevsky@fb.com
The implementation takes inspiration from the existing bpf_trace_printk
helper but there are a few differences:
To allow for a large number of format-specifiers, parameters are
provided in an array, like in bpf_seq_printf.
Because the output string takes two arguments and the array of
parameters also takes two arguments, the format string needs to fit in
one argument. Thankfully, ARG_PTR_TO_CONST_STR is guaranteed to point to
a zero-terminated read-only map so we don't need a format string length
arg.
Because the format-string is known at verification time, we also do
a first pass of format string validation in the verifier logic. This
makes debugging easier.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-4-revest@chromium.org
This type provides the guarantee that an argument is going to be a const
pointer to somewhere in a read-only map value. It also checks that this
pointer is followed by a zero character before the end of the map value.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-3-revest@chromium.org
Two helpers (trace_printk and seq_printf) have very similar
implementations of format string parsing and a third one is coming
(snprintf). To avoid code duplication and make the code easier to
maintain, this moves the operations associated with format string
parsing (validation and argument sanitization) into one generic
function.
The implementation of the two existing helpers already drifted quite a
bit so unifying them entailed a lot of changes:
- bpf_trace_printk always expected fmt[fmt_size] to be the terminating
NULL character, this is no longer true, the first 0 is terminating.
- bpf_trace_printk now supports %% (which produces the percentage char).
- bpf_trace_printk now skips width formating fields.
- bpf_trace_printk now supports the X modifier (capital hexadecimal).
- bpf_trace_printk now supports %pK, %px, %pB, %pi4, %pI4, %pi6 and %pI6
- argument casting on 32 bit has been simplified into one macro and
using an enum instead of obscure int increments.
- bpf_seq_printf now uses bpf_trace_copy_string instead of
strncpy_from_kernel_nofault and handles the %pks %pus specifiers.
- bpf_seq_printf now prints longs correctly on 32 bit architectures.
- both were changed to use a global per-cpu tmp buffer instead of one
stack buffer for trace_printk and 6 small buffers for seq_printf.
- to avoid per-cpu buffer usage conflict, these helpers disable
preemption while the per-cpu buffer is in use.
- both helpers now support the %ps and %pS specifiers to print symbols.
The implementation is also moved from bpf_trace.c to helpers.c because
the upcoming bpf_snprintf helper will be made available to all BPF
programs and will need it.
Signed-off-by: Florent Revest <revest@chromium.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210419155243.1632274-2-revest@chromium.org
drivers/net/ethernet/stmicro/stmmac/stmmac_main.c
- keep the ZC code, drop the code related to reinit
net/bridge/netfilter/ebtables.c
- fix build after move to net_generic
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This work tightens the offset mask we use for unprivileged pointer arithmetic
in order to mitigate a corner case reported by Piotr and Benedict where in
the speculative domain it is possible to advance, for example, the map value
pointer by up to value_size-1 out-of-bounds in order to leak kernel memory
via side-channel to user space.
Before this change, the computed ptr_limit for retrieve_ptr_limit() helper
represents largest valid distance when moving pointer to the right or left
which is then fed as aux->alu_limit to generate masking instructions against
the offset register. After the change, the derived aux->alu_limit represents
the largest potential value of the offset register which we mask against which
is just a narrower subset of the former limit.
For minimal complexity, we call sanitize_ptr_alu() from 2 observation points
in adjust_ptr_min_max_vals(), that is, before and after the simulated alu
operation. In the first step, we retieve the alu_state and alu_limit before
the operation as well as we branch-off a verifier path and push it to the
verification stack as we did before which checks the dst_reg under truncation,
in other words, when the speculative domain would attempt to move the pointer
out-of-bounds.
In the second step, we retrieve the new alu_limit and calculate the absolute
distance between both. Moreover, we commit the alu_state and final alu_limit
via update_alu_sanitation_state() to the env's instruction aux data, and bail
out from there if there is a mismatch due to coming from different verification
paths with different states.
Reported-by: Piotr Krysiuk <piotras@gmail.com>
Reported-by: Benedict Schlueter <benedict.schlueter@rub.de>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Tested-by: Benedict Schlueter <benedict.schlueter@rub.de>
Add a small sanitize_needed() helper function and move sanitize_val_alu()
out of the main opcode switch. In upcoming work, we'll move sanitize_ptr_alu()
as well out of its opcode switch so this helps to streamline both.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Move the bounds check in adjust_ptr_min_max_vals() into a small helper named
sanitize_check_bounds() in order to simplify the former a bit.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Consolidate all error handling and provide more user-friendly error messages
from sanitize_ptr_alu() and sanitize_val_alu().
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Small refactor with no semantic changes in order to consolidate the max
ptr_limit boundary check.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
The mixed signed bounds check really belongs into retrieve_ptr_limit()
instead of outside of it in adjust_ptr_min_max_vals(). The reason is
that this check is not tied to PTR_TO_MAP_VALUE only, but to all pointer
types that we handle in retrieve_ptr_limit() and given errors from the latter
propagate back to adjust_ptr_min_max_vals() and lead to rejection of the
program, it's a better place to reside to avoid anything slipping through
for future types. The reason why we must reject such off_reg is that we
otherwise would not be able to derive a mask, see details in 9d7eceede7
("bpf: restrict unknown scalars of mixed signed bounds for unprivileged").
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Small refactor to drag off_reg into sanitize_ptr_alu(), so we later on can
use off_reg for generalizing some of the checks for all pointer types.
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
We forbid adding unknown scalars with mixed signed bounds due to the
spectre v1 masking mitigation. Hence this also needs bypass_spec_v1
flag instead of allow_ptr_leaks.
Fixes: 2c78ee898d ("bpf: Implement CAP_BPF")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
There is currently no way to discover the target of a tracing program
attachment after the fact. Add this information to bpf_link_info and return
it when querying the bpf_link fd.
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210413091607.58945-1-toke@redhat.com
Conflicts:
MAINTAINERS
- keep Chandrasekar
drivers/net/ethernet/mellanox/mlx5/core/en_main.c
- simple fix + trust the code re-added to param.c in -next is fine
include/linux/bpf.h
- trivial
include/linux/ethtool.h
- trivial, fix kdoc while at it
include/linux/skmsg.h
- move to relevant place in tcp.c, comment re-wrapped
net/core/skmsg.c
- add the sk = sk // sk = NULL around calls
net/tipc/crypto.c
- trivial
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
bpf_preload_lock is already defined with DEFINE_MUTEX(). There is no
need to initialize it again. Remove the extraneous initialization.
Signed-off-by: Muhammad Usama Anjum <musamaanjum@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210405194904.GA148013@LEGION
'stack' parameter is not used in ___bpf_prog_run() after f696b8f471
("bpf: split bpf core interpreter"), the base address have been set to
FP reg. So consequently remove it.
Signed-off-by: He Fengqing <hefengqing@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210331075135.3850782-1-hefengqing@huawei.com
As for bpf_link, refuse creating a non-O_RDWR fd. Since program fds
currently don't allow modifications this is a precaution, not a
straight up bug fix.
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210326160501.46234-2-lmb@cloudflare.com
Invoking BPF_OBJ_GET on a pinned bpf_link checks the path access
permissions based on file_flags, but the returned fd ignores flags.
This means that any user can acquire a "read-write" fd for a pinned
link with mode 0664 by invoking BPF_OBJ_GET with BPF_F_RDONLY in
file_flags. The fd can be used to invoke BPF_LINK_DETACH, etc.
Fix this by refusing non-O_RDWR flags in BPF_OBJ_GET. This works
because OBJ_GET by default returns a read write mapping and libbpf
doesn't expose a way to override this behaviour for programs
and links.
Fixes: 70ed506c3b ("bpf: Introduce pinnable bpf_link abstraction")
Signed-off-by: Lorenz Bauer <lmb@cloudflare.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210326160501.46234-1-lmb@cloudflare.com
On x86 the struct pt_regs * grabbed by task_pt_regs() points to an
offset of task->stack. The pt_regs are later dereferenced in
__bpf_get_stack (e.g. by user_mode() check). This can cause a fault if
the task in question exits while bpf_get_task_stack is executing, as
warned by task_stack_page's comment:
* When accessing the stack of a non-current task that might exit, use
* try_get_task_stack() instead. task_stack_page will return a pointer
* that could get freed out from under you.
Taking the comment's advice and using try_get_task_stack() and
put_task_stack() to hold task->stack refcount, or bail early if it's
already 0. Incrementing stack_refcount will ensure the task's stack
sticks around while we're using its data.
I noticed this bug while testing a bpf task iter similar to
bpf_iter_task_stack in selftests, except mine grabbed user stack, and
getting intermittent crashes, which resulted in dumps like:
BUG: unable to handle page fault for address: 0000000000003fe0
\#PF: supervisor read access in kernel mode
\#PF: error_code(0x0000) - not-present page
RIP: 0010:__bpf_get_stack+0xd0/0x230
<snip...>
Call Trace:
bpf_prog_0a2be35c092cb190_get_task_stacks+0x5d/0x3ec
bpf_iter_run_prog+0x24/0x81
__task_seq_show+0x58/0x80
bpf_seq_read+0xf7/0x3d0
vfs_read+0x91/0x140
ksys_read+0x59/0xd0
do_syscall_64+0x48/0x120
entry_SYSCALL_64_after_hwframe+0x44/0xa9
Fixes: fa28dcb82a ("bpf: Introduce helper bpf_get_task_stack()")
Signed-off-by: Dave Marchevsky <davemarchevsky@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210401000747.3648767-1-davemarchevsky@fb.com
Reusing BPF_SK_SKB_STREAM_VERDICT is possible but its name is
confusing and more importantly we still want to distinguish them
from user-space. So we can just reuse the stream verdict code but
introduce a new type of eBPF program, skb_verdict. Users are not
allowed to attach stream_verdict and skb_verdict programs to the
same map.
Signed-off-by: Cong Wang <cong.wang@bytedance.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: John Fastabend <john.fastabend@gmail.com>
Link: https://lore.kernel.org/bpf/20210331023237.41094-10-xiyou.wangcong@gmail.com
The variable id is being assigned a value that is never read, the
assignment is redundant and can be removed.
Addresses-Coverity: ("Unused value")
Signed-off-by: Colin Ian King <colin.king@canonical.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210326194348.623782-1-colin.king@canonical.com
This patch adds support to BPF verifier to allow bpf program calling
kernel function directly.
The use case included in this set is to allow bpf-tcp-cc to directly
call some tcp-cc helper functions (e.g. "tcp_cong_avoid_ai()"). Those
functions have already been used by some kernel tcp-cc implementations.
This set will also allow the bpf-tcp-cc program to directly call the
kernel tcp-cc implementation, For example, a bpf_dctcp may only want to
implement its own dctcp_cwnd_event() and reuse other dctcp_*() directly
from the kernel tcp_dctcp.c instead of reimplementing (or
copy-and-pasting) them.
The tcp-cc kernel functions mentioned above will be white listed
for the struct_ops bpf-tcp-cc programs to use in a later patch.
The white listed functions are not bounded to a fixed ABI contract.
Those functions have already been used by the existing kernel tcp-cc.
If any of them has changed, both in-tree and out-of-tree kernel tcp-cc
implementations have to be changed. The same goes for the struct_ops
bpf-tcp-cc programs which have to be adjusted accordingly.
This patch is to make the required changes in the bpf verifier.
First change is in btf.c, it adds a case in "btf_check_func_arg_match()".
When the passed in "btf->kernel_btf == true", it means matching the
verifier regs' states with a kernel function. This will handle the
PTR_TO_BTF_ID reg. It also maps PTR_TO_SOCK_COMMON, PTR_TO_SOCKET,
and PTR_TO_TCP_SOCK to its kernel's btf_id.
In the later libbpf patch, the insn calling a kernel function will
look like:
insn->code == (BPF_JMP | BPF_CALL)
insn->src_reg == BPF_PSEUDO_KFUNC_CALL /* <- new in this patch */
insn->imm == func_btf_id /* btf_id of the running kernel */
[ For the future calling function-in-kernel-module support, an array
of module btf_fds can be passed at the load time and insn->off
can be used to index into this array. ]
At the early stage of verifier, the verifier will collect all kernel
function calls into "struct bpf_kfunc_desc". Those
descriptors are stored in "prog->aux->kfunc_tab" and will
be available to the JIT. Since this "add" operation is similar
to the current "add_subprog()" and looking for the same insn->code,
they are done together in the new "add_subprog_and_kfunc()".
In the "do_check()" stage, the new "check_kfunc_call()" is added
to verify the kernel function call instruction:
1. Ensure the kernel function can be used by a particular BPF_PROG_TYPE.
A new bpf_verifier_ops "check_kfunc_call" is added to do that.
The bpf-tcp-cc struct_ops program will implement this function in
a later patch.
2. Call "btf_check_kfunc_args_match()" to ensure the regs can be
used as the args of a kernel function.
3. Mark the regs' type, subreg_def, and zext_dst.
At the later do_misc_fixups() stage, the new fixup_kfunc_call()
will replace the insn->imm with the function address (relative
to __bpf_call_base). If needed, the jit can find the btf_func_model
by calling the new bpf_jit_find_kfunc_model(prog, insn).
With the imm set to the function address, "bpftool prog dump xlated"
will be able to display the kernel function calls the same way as
it displays other bpf helper calls.
gpl_compatible program is required to call kernel function.
This feature currently requires JIT.
The verifier selftests are adjusted because of the changes in
the verbose log in add_subprog_and_kfunc().
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015142.1544736-1-kafai@fb.com
This patch moved the subprog specific logic from
btf_check_func_arg_match() to the new btf_check_subprog_arg_match().
The core logic is left in btf_check_func_arg_match() which
will be reused later to check the kernel function call.
The "if (!btf_type_is_ptr(t))" is checked first to improve the
indentation which will be useful for a later patch.
Some of the "btf_kind_str[]" usages is replaced with the shortcut
"btf_type_str(t)".
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015136.1544504-1-kafai@fb.com
This patch simplifies the linfo freeing logic by combining
"bpf_prog_free_jited_linfo()" and "bpf_prog_free_unused_jited_linfo()"
into the new "bpf_prog_jit_attempt_done()".
It is a prep work for the kernel function call support. In a later
patch, freeing the kernel function call descriptors will also
be done in the "bpf_prog_jit_attempt_done()".
"bpf_prog_free_linfo()" is removed since it is only called by
"__bpf_prog_put_noref()". The kvfree() are directly called
instead.
It also takes this chance to s/kcalloc/kvcalloc/ for the jited_linfo
allocation.
Signed-off-by: Martin KaFai Lau <kafai@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210325015130.1544323-1-kafai@fb.com
Currently module can be unloaded even if there's a trampoline
register in it. It's easily reproduced by running in parallel:
# while :; do ./test_progs -t module_attach; done
# while :; do rmmod bpf_testmod; sleep 0.5; done
Taking the module reference in case the trampoline's ip is
within the module code. Releasing it when the trampoline's
ip is unregistered.
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210326105900.151466-1-jolsa@kernel.org
The name string for BPF_XOR is "xor", not "or". Fix it.
Fixes: 981f94c3e9 ("bpf: Add bitwise atomic instructions")
Signed-off-by: Xu Kuohai <xukuohai@huawei.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210325134141.8533-1-xukuohai@huawei.com
With the introduction of the struct_ops program type, it became possible to
implement kernel functionality in BPF, making it viable to use BPF in place
of a regular kernel module for these particular operations.
Thus far, the only user of this mechanism is for implementing TCP
congestion control algorithms. These are clearly marked as GPL-only when
implemented as modules (as seen by the use of EXPORT_SYMBOL_GPL for
tcp_register_congestion_control()), so it seems like an oversight that this
was not carried over to BPF implementations. Since this is the only user
of the struct_ops mechanism, just enforcing GPL-only for the struct_ops
program type seems like the simplest way to fix this.
Fixes: 0baf26b0fc ("bpf: tcp: Support tcp_congestion_ops in bpf")
Signed-off-by: Toke Høiland-Jørgensen <toke@redhat.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210326100314.121853-1-toke@redhat.com
Jiri Olsa reported a bug ([1]) in kernel where cgroup local
storage pointer may be NULL in bpf_get_local_storage() helper.
There are two issues uncovered by this bug:
(1). kprobe or tracepoint prog incorrectly sets cgroup local storage
before prog run,
(2). due to change from preempt_disable to migrate_disable,
preemption is possible and percpu storage might be overwritten
by other tasks.
This issue (1) is fixed in [2]. This patch tried to address issue (2).
The following shows how things can go wrong:
task 1: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 2: bpf_cgroup_storage_set() for percpu local storage
preemption happens
task 1: run bpf program
task 1 will effectively use the percpu local storage setting by task 2
which will be either NULL or incorrect ones.
Instead of just one common local storage per cpu, this patch fixed
the issue by permitting 8 local storages per cpu and each local
storage is identified by a task_struct pointer. This way, we
allow at most 8 nested preemption between bpf_cgroup_storage_set()
and bpf_cgroup_storage_unset(). The percpu local storage slot
is released (calling bpf_cgroup_storage_unset()) by the same task
after bpf program finished running.
bpf_test_run() is also fixed to use the new bpf_cgroup_storage_set()
interface.
The patch is tested on top of [2] with reproducer in [1].
Without this patch, kernel will emit error in 2-3 minutes.
With this patch, after one hour, still no error.
[1] https://lore.kernel.org/bpf/CAKH8qBuXCfUz=w8L+Fj74OaUpbosO29niYwTki7e3Ag044_aww@mail.gmail.com/T
[2] https://lore.kernel.org/bpf/20210309185028.3763817-1-yhs@fb.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Roman Gushchin <guro@fb.com>
Link: https://lore.kernel.org/bpf/20210323055146.3334476-1-yhs@fb.com
Remove PTR_TO_MAP_KEY for the time being from being sanitized on pointer ALU
through sanitize_ptr_alu() mainly for 3 reasons:
1) It's currently unused and not available from unprivileged. However that by
itself is not yet a strong reason to drop the code.
2) Commit 69c087ba62 ("bpf: Add bpf_for_each_map_elem() helper") implemented
the sanitation not fully correct in that unlike stack or map_value pointer
it doesn't probe whether the access to the map key /after/ the simulated ALU
operation is still in bounds. This means that the generated mask can truncate
the offset in the non-speculative domain whereas it should only truncate in
the speculative domain. The verifier should instead reject such program as
we do for other types.
3) Given the recent fixes from f232326f69 ("bpf: Prohibit alu ops for pointer
types not defining ptr_limit"), 10d2bb2e6b ("bpf: Fix off-by-one for area
size in creating mask to left"), b5871dca25 ("bpf: Simplify alu_limit masking
for pointer arithmetic") as well as 1b1597e64e ("bpf: Add sanity check for
upper ptr_limit") the code changed quite a bit and the merge in efd13b71a3
broke the PTR_TO_MAP_KEY case due to an incorrect merge conflict.
Remove the relevant pieces for the time being and we can rework the PTR_TO_MAP_KEY
case once everything settles.
Fixes: efd13b71a3 ("Merge git://git.kernel.org/pub/scm/linux/kernel/git/netdev/net")
Fixes: 69c087ba62 ("bpf: Add bpf_for_each_map_elem() helper")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-03-24
The following pull-request contains BPF updates for your *net-next* tree.
We've added 37 non-merge commits during the last 15 day(s) which contain
a total of 65 files changed, 3200 insertions(+), 738 deletions(-).
The main changes are:
1) Static linking of multiple BPF ELF files, from Andrii.
2) Move drop error path to devmap for XDP_REDIRECT, from Lorenzo.
3) Spelling fixes from various folks.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
gcc -Wextra wants type modifiers in the normal order:
kernel/bpf/bpf_lsm.c:70:1: error: 'static' is not at beginning of declaration [-Werror=old-style-declaration]
70 | const static struct bpf_func_proto bpf_bprm_opts_set_proto = {
| ^~~~~
kernel/bpf/bpf_lsm.c:91:1: error: 'static' is not at beginning of declaration [-Werror=old-style-declaration]
91 | const static struct bpf_func_proto bpf_ima_inode_hash_proto = {
| ^~~~~
Fixes: 3f6719c7b6 ("bpf: Add bpf_bprm_opts_set helper")
Fixes: 27672f0d28 ("bpf: Add a BPF helper for getting the IMA hash of an inode")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210322215201.1097281-1-arnd@kernel.org
Of the three LSMs that implement the security_task_getsecid() LSM
hook, all three LSMs provide the task's objective security
credentials. This turns out to be unfortunate as most of the hook's
callers seem to expect the task's subjective credentials, although
a small handful of callers do correctly expect the objective
credentials.
This patch is the first step towards fixing the problem: it splits
the existing security_task_getsecid() hook into two variants, one
for the subjective creds, one for the objective creds.
void security_task_getsecid_subj(struct task_struct *p,
u32 *secid);
void security_task_getsecid_obj(struct task_struct *p,
u32 *secid);
While this patch does fix all of the callers to use the correct
variant, in order to keep this patch focused on the callers and to
ease review, the LSMs continue to use the same implementation for
both hooks. The net effect is that this patch should not change
the behavior of the kernel in any way, it will be up to the latter
LSM specific patches in this series to change the hook
implementations and return the correct credentials.
Acked-by: Mimi Zohar <zohar@linux.ibm.com> (IMA)
Acked-by: Casey Schaufler <casey@schaufler-ca.com>
Reviewed-by: Richard Guy Briggs <rgb@redhat.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Two insn_buf[16] variables are declared in the function which acts on
function scope and block scope respectively. The statement in the inner
block is redundant, so remove it.
Signed-off-by: Jianlin Lv <Jianlin.Lv@arm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210318024851.49693-1-Jianlin.Lv@arm.com
We want to change the current ndo_xdp_xmit drop semantics because it will
allow us to implement better queue overflow handling. This is working
towards the larger goal of a XDP TX queue-hook. Move XDP_REDIRECT error
path handling from each XDP ethernet driver to devmap code. According to
the new APIs, the driver running the ndo_xdp_xmit pointer, will break tx
loop whenever the hw reports a tx error and it will just return to devmap
caller the number of successfully transmitted frames. It will be devmap
responsibility to free dropped frames.
Move each XDP ndo_xdp_xmit capable driver to the new APIs:
- veth
- virtio-net
- mvneta
- mvpp2
- socionext
- amazon ena
- bnxt
- freescale (dpaa2, dpaa)
- xen-frontend
- qede
- ice
- igb
- ixgbe
- i40e
- mlx5
- ti (cpsw, cpsw-new)
- tun
- sfc
Signed-off-by: Lorenzo Bianconi <lorenzo@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Ioana Ciornei <ioana.ciornei@nxp.com>
Reviewed-by: Ilias Apalodimas <ilias.apalodimas@linaro.org>
Reviewed-by: Camelia Groza <camelia.groza@nxp.com>
Acked-by: Edward Cree <ecree.xilinx@gmail.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Shay Agroskin <shayagr@amazon.com>
Link: https://lore.kernel.org/bpf/ed670de24f951cfd77590decf0229a0ad7fd12f6.1615201152.git.lorenzo@kernel.org
The fexit/fmod_ret programs can be attached to kernel functions that can sleep.
The synchronize_rcu_tasks() will not wait for such tasks to complete.
In such case the trampoline image will be freed and when the task
wakes up the return IP will point to freed memory causing the crash.
Solve this by adding percpu_ref_get/put for the duration of trampoline
and separate trampoline vs its image life times.
The "half page" optimization has to be removed, since
first_half->second_half->first_half transition cannot be guaranteed to
complete in deterministic time. Every trampoline update becomes a new image.
The image with fmod_ret or fexit progs will be freed via percpu_ref_kill and
call_rcu_tasks. Together they will wait for the original function and
trampoline asm to complete. The trampoline is patched from nop to jmp to skip
fexit progs. They are freed independently from the trampoline. The image with
fentry progs only will be freed via call_rcu_tasks_trace+call_rcu_tasks which
will wait for both sleepable and non-sleepable progs to complete.
Fixes: fec56f5890 ("bpf: Introduce BPF trampoline")
Reported-by: Andrii Nakryiko <andrii@kernel.org>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Paul E. McKenney <paulmck@kernel.org> # for RCU
Link: https://lore.kernel.org/bpf/20210316210007.38949-1-alexei.starovoitov@gmail.com
Given we know the max possible value of ptr_limit at the time of retrieving
the latter, add basic assertions, so that the verifier can bail out if
anything looks odd and reject the program. Nothing triggered this so far,
but it also does not hurt to have these.
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
Instead of having the mov32 with aux->alu_limit - 1 immediate, move this
operation to retrieve_ptr_limit() instead to simplify the logic and to
allow for subsequent sanity boundary checks inside retrieve_ptr_limit().
This avoids in future that at the time of the verifier masking rewrite
we'd run into an underflow which would not sign extend due to the nature
of mov32 instruction.
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
retrieve_ptr_limit() computes the ptr_limit for registers with stack and
map_value type. ptr_limit is the size of the memory area that is still
valid / in-bounds from the point of the current position and direction
of the operation (add / sub). This size will later be used for masking
the operation such that attempting out-of-bounds access in the speculative
domain is redirected to remain within the bounds of the current map value.
When masking to the right the size is correct, however, when masking to
the left, the size is off-by-one which would lead to an incorrect mask
and thus incorrect arithmetic operation in the non-speculative domain.
Piotr found that if the resulting alu_limit value is zero, then the
BPF_MOV32_IMM() from the fixup_bpf_calls() rewrite will end up loading
0xffffffff into AX instead of sign-extending to the full 64 bit range,
and as a result, this allows abuse for executing speculatively out-of-
bounds loads against 4GB window of address space and thus extracting the
contents of kernel memory via side-channel.
Fixes: 979d63d50c ("bpf: prevent out of bounds speculation on pointer arithmetic")
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
The purpose of this patch is to streamline error propagation and in particular
to propagate retrieve_ptr_limit() errors for pointer types that are not defining
a ptr_limit such that register-based alu ops against these types can be rejected.
The main rationale is that a gap has been identified by Piotr in the existing
protection against speculatively out-of-bounds loads, for example, in case of
ctx pointers, unprivileged programs can still perform pointer arithmetic. This
can be abused to execute speculatively out-of-bounds loads without restrictions
and thus extract contents of kernel memory.
Fix this by rejecting unprivileged programs that attempt any pointer arithmetic
on unprotected pointer types. The two affected ones are pointer to ctx as well
as pointer to map. Field access to a modified ctx' pointer is rejected at a
later point in time in the verifier, and 7c69673262 ("bpf: Permit map_ptr
arithmetic with opcode add and offset 0") only relevant for root-only use cases.
Risk of unprivileged program breakage is considered very low.
Fixes: 7c69673262 ("bpf: Permit map_ptr arithmetic with opcode add and offset 0")
Fixes: b2157399cc ("bpf: prevent out-of-bounds speculation")
Signed-off-by: Piotr Krysiuk <piotras@gmail.com>
Co-developed-by: Daniel Borkmann <daniel@iogearbox.net>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Alexei Starovoitov <ast@kernel.org>
The sparse tool complains as follows:
kernel/bpf/bpf_task_storage.c:23:1: warning:
symbol '__pcpu_scope_bpf_task_storage_busy' was not declared. Should it be static?
This symbol is not used outside of bpf_task_storage.c, so this
commit marks it static.
Fixes: bc235cdb42 ("bpf: Prevent deadlock from recursive bpf_task_storage_[get|delete]")
Reported-by: Hulk Robot <hulkci@huawei.com>
Signed-off-by: Wei Yongjun <weiyongjun1@huawei.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Song Liu <songliubraving@fb.com>
Link: https://lore.kernel.org/bpf/20210311131505.1901509-1-weiyongjun1@huawei.com
A typo is found out by codespell tool in 34th lines of hashtab.c:
$ codespell ./kernel/bpf/
./hashtab.c:34 : differrent ==> different
Fix a typo found by codespell.
Signed-off-by: Liu xuzhi <liu.xuzhi@zte.com.cn>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210311123103.323589-1-liu.xuzhi@zte.com.cn
Alexei Starovoitov says:
====================
pull-request: bpf-next 2021-03-09
The following pull-request contains BPF updates for your *net-next* tree.
We've added 90 non-merge commits during the last 17 day(s) which contain
a total of 114 files changed, 5158 insertions(+), 1288 deletions(-).
The main changes are:
1) Faster bpf_redirect_map(), from Björn.
2) skmsg cleanup, from Cong.
3) Support for floating point types in BTF, from Ilya.
4) Documentation for sys_bpf commands, from Joe.
5) Support for sk_lookup in bpf_prog_test_run, form Lorenz.
6) Enable task local storage for tracing programs, from Song.
7) bpf_for_each_map_elem() helper, from Yonghong.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
The XDP_REDIRECT implementations for maps and non-maps are fairly
similar, but obviously need to take different code paths depending on
if the target is using a map or not. Today, the redirect targets for
XDP either uses a map, or is based on ifindex.
Here, the map type and id are added to bpf_redirect_info, instead of
the actual map. Map type, map item/ifindex, and the map_id (if any) is
passed to xdp_do_redirect().
For ifindex-based redirect, used by the bpf_redirect() XDP BFP helper,
a special map type/id are used. Map type of UNSPEC together with map id
equal to INT_MAX has the special meaning of an ifindex based
redirect. Note that valid map ids are 1 inclusive, INT_MAX exclusive
([1,INT_MAX[).
In addition to making the code easier to follow, using explicit type
and id in bpf_redirect_info has a slight positive performance impact
by avoiding a pointer indirection for the map type lookup, and instead
use the cacheline for bpf_redirect_info.
Since the actual map is not passed via bpf_redirect_info anymore, the
map lookup is only done in the BPF helper. This means that the
bpf_clear_redirect_map() function can be removed. The actual map item
is RCU protected.
The bpf_redirect_info flags member is not used by XDP, and not
read/written any more. The map member is only written to when
required/used, and not unconditionally.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: Maciej Fijalkowski <maciej.fijalkowski@intel.com>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-3-bjorn.topel@gmail.com
Currently the bpf_redirect_map() implementation dispatches to the
correct map-lookup function via a switch-statement. To avoid the
dispatching, this change adds bpf_redirect_map() as a map
operation. Each map provides its bpf_redirect_map() version, and
correct function is automatically selected by the BPF verifier.
A nice side-effect of the code movement is that the map lookup
functions are now local to the map implementation files, which removes
one additional function call.
Signed-off-by: Björn Töpel <bjorn.topel@intel.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Jesper Dangaard Brouer <brouer@redhat.com>
Acked-by: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210308112907.559576-2-bjorn.topel@gmail.com
bpf_fd_inode_storage_lookup_elem() returned NULL when getting a bad FD,
which caused -ENOENT in bpf_map_copy_value. -EBADF error is better than
-ENOENT for a bad FD behaviour.
The patch was partially contributed by CyberArk Software, Inc.
Fixes: 8ea636848a ("bpf: Implement bpf_local_storage for inodes")
Signed-off-by: Tal Lossos <tallossos@gmail.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210307120948.61414-1-tallossos@gmail.com
The syzbot got FD of vmlinux BTF and passed it into map_create which caused
crash in btf_type_id_size() when it tried to access resolved_ids. The vmlinux
BTF doesn't have 'resolved_ids' and 'resolved_sizes' initialized to save
memory. To avoid such issues disallow using vmlinux BTF in prog_load and
map_create commands.
Fixes: 5329722057 ("bpf: Assign ID to vmlinux BTF and return extra info for BTF in GET_OBJ_INFO")
Reported-by: syzbot+8bab8ed346746e7540e8@syzkaller.appspotmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210307225248.79031-1-alexei.starovoitov@gmail.com
As pointed out by Ilya and explained in the new comment, there's a
discrepancy between x86 and BPF CMPXCHG semantics: BPF always loads
the value from memory into r0, while x86 only does so when r0 and the
value in memory are different. The same issue affects s390.
At first this might sound like pure semantics, but it makes a real
difference when the comparison is 32-bit, since the load will
zero-extend r0/rax.
The fix is to explicitly zero-extend rax after doing such a
CMPXCHG. Since this problem affects multiple archs, this is done in
the verifier by patching in a BPF_ZEXT_REG instruction after every
32-bit cmpxchg. Any archs that don't need such manual zero-extension
can do a look-ahead with insn_is_zext to skip the unnecessary mov.
Note this still goes on top of Ilya's patch:
https://lore.kernel.org/bpf/20210301154019.129110-1-iii@linux.ibm.com/T/#u
Differences v5->v6[1]:
- Moved is_cmpxchg_insn and ensured it can be safely re-used. Also renamed it
and removed 'inline' to match the style of the is_*_function helpers.
- Fixed up comments in verifier test (thanks for the careful review, Martin!)
Differences v4->v5[1]:
- Moved the logic entirely into opt_subreg_zext_lo32_rnd_hi32, thanks to Martin
for suggesting this.
Differences v3->v4[1]:
- Moved the optimization against pointless zext into the correct place:
opt_subreg_zext_lo32_rnd_hi32 is called _after_ fixup_bpf_calls.
Differences v2->v3[1]:
- Moved patching into fixup_bpf_calls (patch incoming to rename this function)
- Added extra commentary on bpf_jit_needs_zext
- Added check to avoid adding a pointless zext(r0) if there's already one there.
Difference v1->v2[1]: Now solved centrally in the verifier instead of
specifically for the x86 JIT. Thanks to Ilya and Daniel for the suggestions!
[1] v5: https://lore.kernel.org/bpf/CA+i-1C3ytZz6FjcPmUg5s4L51pMQDxWcZNvM86w4RHZ_o2khwg@mail.gmail.com/T/#t
v4: https://lore.kernel.org/bpf/CA+i-1C3ytZz6FjcPmUg5s4L51pMQDxWcZNvM86w4RHZ_o2khwg@mail.gmail.com/T/#t
v3: https://lore.kernel.org/bpf/08669818-c99d-0d30-e1db-53160c063611@iogearbox.net/T/#t
v2: https://lore.kernel.org/bpf/08669818-c99d-0d30-e1db-53160c063611@iogearbox.net/T/#t
v1: https://lore.kernel.org/bpf/d7ebaefb-bfd6-a441-3ff2-2fdfe699b1d2@iogearbox.net/T/#t
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Fixes: 5ffa25502b ("bpf: Add instructions for atomic_[cmp]xchg")
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Ilya Leoshkevich <iii@linux.ibm.com>
Tested-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
On the kernel side, introduce a new btf_kind_operations. It is
similar to that of BTF_KIND_INT, however, it does not need to
handle encodings and bit offsets. Do not implement printing, since
the kernel does not know how to format floating-point values.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210226202256.116518-7-iii@linux.ibm.com
insn_has_def32() returns false for 32-bit BPF_FETCH insns. This makes
adjust_insn_aux_data() incorrectly set zext_dst, as can be seen in [1].
This happens because insn_no_def() does not know about the BPF_FETCH
variants of BPF_STX.
Fix in two steps.
First, replace insn_no_def() with insn_def_regno(), which returns the
register an insn defines. Normally insn_no_def() calls are followed by
insn->dst_reg uses; replace those with the insn_def_regno() return
value.
Second, adjust the BPF_STX special case in is_reg64() to deal with
queries made from opt_subreg_zext_lo32_rnd_hi32(), where the state
information is no longer available. Add a comment, since the purpose
of this special case is not clear at first glance.
[1] https://lore.kernel.org/bpf/20210223150845.1857620-1-jackmanb@google.com/
Fixes: 5ffa25502b ("bpf: Add instructions for atomic_[cmp]xchg")
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Acked-by: Brendan Jackman <jackmanb@google.com>
Link: https://lore.kernel.org/bpf/20210301154019.129110-1-iii@linux.ibm.com
This patch added support for arraymap and percpu arraymap.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204928.3885192-1-yhs@fb.com
The bpf_for_each_map_elem() helper is introduced which
iterates all map elements with a callback function. The
helper signature looks like
long bpf_for_each_map_elem(map, callback_fn, callback_ctx, flags)
and for each map element, the callback_fn will be called. For example,
like hashmap, the callback signature may look like
long callback_fn(map, key, val, callback_ctx)
There are two known use cases for this. One is from upstream ([1]) where
a for_each_map_elem helper may help implement a timeout mechanism
in a more generic way. Another is from our internal discussion
for a firewall use case where a map contains all the rules. The packet
data can be compared to all these rules to decide allow or deny
the packet.
For array maps, users can already use a bounded loop to traverse
elements. Using this helper can avoid using bounded loop. For other
type of maps (e.g., hash maps) where bounded loop is hard or
impossible to use, this helper provides a convenient way to
operate on all elements.
For callback_fn, besides map and map element, a callback_ctx,
allocated on caller stack, is also passed to the callback
function. This callback_ctx argument can provide additional
input and allow to write to caller stack for output.
If the callback_fn returns 0, the helper will iterate through next
element if available. If the callback_fn returns 1, the helper
will stop iterating and returns to the bpf program. Other return
values are not used for now.
Currently, this helper is only available with jit. It is possible
to make it work with interpreter with so effort but I leave it
as the future work.
[1]: https://lore.kernel.org/bpf/20210122205415.113822-1-xiyou.wangcong@gmail.com/
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204925.3884923-1-yhs@fb.com
Currently, verifier function add_subprog() returns 0 for success
and negative value for failure. Change the return value
to be the subprog number for success. This functionality will be
used in the next patch to save a call to find_subprog().
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204924.3884848-1-yhs@fb.com
Later proposed bpf_for_each_map_elem() helper has callback
function as one of its arguments. This patch refactored
check_func_call() to permit callback function which sets
callee state. Different callback functions may have
different callee states.
There is no functionality change for this patch.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204923.3884627-1-yhs@fb.com
Factor out the function verbose_invalid_scalar() to verbose
print if a scalar is not in a tnum range. There is no
functionality change and the function will be used by
later patch which introduced bpf_for_each_map_elem().
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204922.3884375-1-yhs@fb.com
During verifier check_cfg(), all instructions are
visited to ensure verifier can handle program control flows.
This patch factored out function visit_func_call_insn()
so it can be reused in later patch to visit callback function
calls. There is no functionality change for this patch.
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210226204920.3884136-1-yhs@fb.com
Alexei Starovoitov says:
====================
pull-request: bpf 2021-02-26
1) Fix for bpf atomic insns with src_reg=r0, from Brendan.
2) Fix use after free due to bpf_prog_clone, from Cong.
3) Drop imprecise verifier log message, from Dmitrii.
4) Remove incorrect blank line in bpf helper description, from Hangbin.
* https://git.kernel.org/pub/scm/linux/kernel/git/bpf/bpf:
selftests/bpf: No need to drop the packet when there is no geneve opt
bpf: Remove blank line in bpf helper description comment
tools/resolve_btfids: Fix build error with older host toolchains
selftests/bpf: Fix a compiler warning in global func test
bpf: Drop imprecise log message
bpf: Clear percpu pointers in bpf_prog_clone_free()
bpf: Fix a warning message in mark_ptr_not_null_reg()
bpf, x86: Fix BPF_FETCH atomic and/or/xor with r0 as src
====================
Link: https://lore.kernel.org/r/20210226193737.57004-1-alexei.starovoitov@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
This function has become overloaded, it actually does lots of diverse
things in a single pass. Rename it to avoid confusion, and add some
concise commentary.
Signed-off-by: Brendan Jackman <jackmanb@google.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210217104509.2423183-1-jackmanb@google.com
Instead of using integer literal here and there use macro name for
better context.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225202629.585485-1-me@ubique.spb.ru
BPF helpers bpf_task_storage_[get|delete] could hold two locks:
bpf_local_storage_map_bucket->lock and bpf_local_storage->lock. Calling
these helpers from fentry/fexit programs on functions in bpf_*_storage.c
may cause deadlock on either locks.
Prevent such deadlock with a per cpu counter, bpf_task_storage_busy. We
need this counter to be global, because the two locks here belong to two
different objects: bpf_local_storage_map and bpf_local_storage. If we
pick one of them as the owner of the counter, it is still possible to
trigger deadlock on the other lock. For example, if bpf_local_storage_map
owns the counters, it cannot prevent deadlock on bpf_local_storage->lock
when two maps are used.
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225234319.336131-3-songliubraving@fb.com
To access per-task data, BPF programs usually creates a hash table with
pid as the key. This is not ideal because:
1. The user need to estimate the proper size of the hash table, which may
be inaccurate;
2. Big hash tables are slow;
3. To clean up the data properly during task terminations, the user need
to write extra logic.
Task local storage overcomes these issues and offers a better option for
these per-task data. Task local storage is only available to BPF_LSM. Now
enable it for tracing programs.
Unlike LSM programs, tracing programs can be called in IRQ contexts.
Helpers that access task local storage are updated to use
raw_spin_lock_irqsave() instead of raw_spin_lock_bh().
Tracing programs can attach to functions on the task free path, e.g.
exit_creds(). To avoid allocating task local storage after
bpf_task_storage_free(). bpf_task_storage_get() is updated to not allocate
new storage when the task is not refcounted (task->usage == 0).
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210225234319.336131-2-songliubraving@fb.com
Now it is possible for global function to have a pointer argument that
points to something different than struct. Drop the irrelevant log
message and keep the logic same.
Fixes: e5069b9c23 ("bpf: Support pointers in global func args")
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Martin KaFai Lau <kafai@fb.com>
Link: https://lore.kernel.org/bpf/20210223090416.333943-1-me@ubique.spb.ru
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Merge tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux
Pull idmapped mounts from Christian Brauner:
"This introduces idmapped mounts which has been in the making for some
time. Simply put, different mounts can expose the same file or
directory with different ownership. This initial implementation comes
with ports for fat, ext4 and with Christoph's port for xfs with more
filesystems being actively worked on by independent people and
maintainers.
Idmapping mounts handle a wide range of long standing use-cases. Here
are just a few:
- Idmapped mounts make it possible to easily share files between
multiple users or multiple machines especially in complex
scenarios. For example, idmapped mounts will be used in the
implementation of portable home directories in
systemd-homed.service(8) where they allow users to move their home
directory to an external storage device and use it on multiple
computers where they are assigned different uids and gids. This
effectively makes it possible to assign random uids and gids at
login time.
- It is possible to share files from the host with unprivileged
containers without having to change ownership permanently through
chown(2).
- It is possible to idmap a container's rootfs and without having to
mangle every file. For example, Chromebooks use it to share the
user's Download folder with their unprivileged containers in their
Linux subsystem.
- It is possible to share files between containers with
non-overlapping idmappings.
- Filesystem that lack a proper concept of ownership such as fat can
use idmapped mounts to implement discretionary access (DAC)
permission checking.
- They allow users to efficiently changing ownership on a per-mount
basis without having to (recursively) chown(2) all files. In
contrast to chown (2) changing ownership of large sets of files is
instantenous with idmapped mounts. This is especially useful when
ownership of a whole root filesystem of a virtual machine or
container is changed. With idmapped mounts a single syscall
mount_setattr syscall will be sufficient to change the ownership of
all files.
- Idmapped mounts always take the current ownership into account as
idmappings specify what a given uid or gid is supposed to be mapped
to. This contrasts with the chown(2) syscall which cannot by itself
take the current ownership of the files it changes into account. It
simply changes the ownership to the specified uid and gid. This is
especially problematic when recursively chown(2)ing a large set of
files which is commong with the aforementioned portable home
directory and container and vm scenario.
- Idmapped mounts allow to change ownership locally, restricting it
to specific mounts, and temporarily as the ownership changes only
apply as long as the mount exists.
Several userspace projects have either already put up patches and
pull-requests for this feature or will do so should you decide to pull
this:
- systemd: In a wide variety of scenarios but especially right away
in their implementation of portable home directories.
https://systemd.io/HOME_DIRECTORY/
- container runtimes: containerd, runC, LXD:To share data between
host and unprivileged containers, unprivileged and privileged
containers, etc. The pull request for idmapped mounts support in
containerd, the default Kubernetes runtime is already up for quite
a while now: https://github.com/containerd/containerd/pull/4734
- The virtio-fs developers and several users have expressed interest
in using this feature with virtual machines once virtio-fs is
ported.
- ChromeOS: Sharing host-directories with unprivileged containers.
I've tightly synced with all those projects and all of those listed
here have also expressed their need/desire for this feature on the
mailing list. For more info on how people use this there's a bunch of
talks about this too. Here's just two recent ones:
https://www.cncf.io/wp-content/uploads/2020/12/Rootless-Containers-in-Gitpod.pdfhttps://fosdem.org/2021/schedule/event/containers_idmap/
This comes with an extensive xfstests suite covering both ext4 and
xfs:
https://git.kernel.org/brauner/xfstests-dev/h/idmapped_mounts
It covers truncation, creation, opening, xattrs, vfscaps, setid
execution, setgid inheritance and more both with idmapped and
non-idmapped mounts. It already helped to discover an unrelated xfs
setgid inheritance bug which has since been fixed in mainline. It will
be sent for inclusion with the xfstests project should you decide to
merge this.
In order to support per-mount idmappings vfsmounts are marked with
user namespaces. The idmapping of the user namespace will be used to
map the ids of vfs objects when they are accessed through that mount.
By default all vfsmounts are marked with the initial user namespace.
The initial user namespace is used to indicate that a mount is not
idmapped. All operations behave as before and this is verified in the
testsuite.
Based on prior discussions we want to attach the whole user namespace
and not just a dedicated idmapping struct. This allows us to reuse all
the helpers that already exist for dealing with idmappings instead of
introducing a whole new range of helpers. In addition, if we decide in
the future that we are confident enough to enable unprivileged users
to setup idmapped mounts the permission checking can take into account
whether the caller is privileged in the user namespace the mount is
currently marked with.
The user namespace the mount will be marked with can be specified by
passing a file descriptor refering to the user namespace as an
argument to the new mount_setattr() syscall together with the new
MOUNT_ATTR_IDMAP flag. The system call follows the openat2() pattern
of extensibility.
The following conditions must be met in order to create an idmapped
mount:
- The caller must currently have the CAP_SYS_ADMIN capability in the
user namespace the underlying filesystem has been mounted in.
- The underlying filesystem must support idmapped mounts.
- The mount must not already be idmapped. This also implies that the
idmapping of a mount cannot be altered once it has been idmapped.
- The mount must be a detached/anonymous mount, i.e. it must have
been created by calling open_tree() with the OPEN_TREE_CLONE flag
and it must not already have been visible in the filesystem.
The last two points guarantee easier semantics for userspace and the
kernel and make the implementation significantly simpler.
By default vfsmounts are marked with the initial user namespace and no
behavioral or performance changes are observed.
The manpage with a detailed description can be found here:
1d7b902e28
In order to support idmapped mounts, filesystems need to be changed
and mark themselves with the FS_ALLOW_IDMAP flag in fs_flags. The
patches to convert individual filesystem are not very large or
complicated overall as can be seen from the included fat, ext4, and
xfs ports. Patches for other filesystems are actively worked on and
will be sent out separately. The xfstestsuite can be used to verify
that port has been done correctly.
The mount_setattr() syscall is motivated independent of the idmapped
mounts patches and it's been around since July 2019. One of the most
valuable features of the new mount api is the ability to perform
mounts based on file descriptors only.
Together with the lookup restrictions available in the openat2()
RESOLVE_* flag namespace which we added in v5.6 this is the first time
we are close to hardened and race-free (e.g. symlinks) mounting and
path resolution.
While userspace has started porting to the new mount api to mount
proper filesystems and create new bind-mounts it is currently not
possible to change mount options of an already existing bind mount in
the new mount api since the mount_setattr() syscall is missing.
With the addition of the mount_setattr() syscall we remove this last
restriction and userspace can now fully port to the new mount api,
covering every use-case the old mount api could. We also add the
crucial ability to recursively change mount options for a whole mount
tree, both removing and adding mount options at the same time. This
syscall has been requested multiple times by various people and
projects.
There is a simple tool available at
https://github.com/brauner/mount-idmapped
that allows to create idmapped mounts so people can play with this
patch series. I'll add support for the regular mount binary should you
decide to pull this in the following weeks:
Here's an example to a simple idmapped mount of another user's home
directory:
u1001@f2-vm:/$ sudo ./mount --idmap both:1000:1001:1 /home/ubuntu/ /mnt
u1001@f2-vm:/$ ls -al /home/ubuntu/
total 28
drwxr-xr-x 2 ubuntu ubuntu 4096 Oct 28 22:07 .
drwxr-xr-x 4 root root 4096 Oct 28 04:00 ..
-rw------- 1 ubuntu ubuntu 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 ubuntu ubuntu 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 ubuntu ubuntu 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 ubuntu ubuntu 807 Feb 25 2020 .profile
-rw-r--r-- 1 ubuntu ubuntu 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 ubuntu ubuntu 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ ls -al /mnt/
total 28
drwxr-xr-x 2 u1001 u1001 4096 Oct 28 22:07 .
drwxr-xr-x 29 root root 4096 Oct 28 22:01 ..
-rw------- 1 u1001 u1001 3154 Oct 28 22:12 .bash_history
-rw-r--r-- 1 u1001 u1001 220 Feb 25 2020 .bash_logout
-rw-r--r-- 1 u1001 u1001 3771 Feb 25 2020 .bashrc
-rw-r--r-- 1 u1001 u1001 807 Feb 25 2020 .profile
-rw-r--r-- 1 u1001 u1001 0 Oct 16 16:11 .sudo_as_admin_successful
-rw------- 1 u1001 u1001 1144 Oct 28 00:43 .viminfo
u1001@f2-vm:/$ touch /mnt/my-file
u1001@f2-vm:/$ setfacl -m u:1001:rwx /mnt/my-file
u1001@f2-vm:/$ sudo setcap -n 1001 cap_net_raw+ep /mnt/my-file
u1001@f2-vm:/$ ls -al /mnt/my-file
-rw-rwxr--+ 1 u1001 u1001 0 Oct 28 22:14 /mnt/my-file
u1001@f2-vm:/$ ls -al /home/ubuntu/my-file
-rw-rwxr--+ 1 ubuntu ubuntu 0 Oct 28 22:14 /home/ubuntu/my-file
u1001@f2-vm:/$ getfacl /mnt/my-file
getfacl: Removing leading '/' from absolute path names
# file: mnt/my-file
# owner: u1001
# group: u1001
user::rw-
user:u1001:rwx
group::rw-
mask::rwx
other::r--
u1001@f2-vm:/$ getfacl /home/ubuntu/my-file
getfacl: Removing leading '/' from absolute path names
# file: home/ubuntu/my-file
# owner: ubuntu
# group: ubuntu
user::rw-
user:ubuntu:rwx
group::rw-
mask::rwx
other::r--"
* tag 'idmapped-mounts-v5.12' of git://git.kernel.org/pub/scm/linux/kernel/git/brauner/linux: (41 commits)
xfs: remove the possibly unused mp variable in xfs_file_compat_ioctl
xfs: support idmapped mounts
ext4: support idmapped mounts
fat: handle idmapped mounts
tests: add mount_setattr() selftests
fs: introduce MOUNT_ATTR_IDMAP
fs: add mount_setattr()
fs: add attr_flags_to_mnt_flags helper
fs: split out functions to hold writers
namespace: only take read lock in do_reconfigure_mnt()
mount: make {lock,unlock}_mount_hash() static
namespace: take lock_mount_hash() directly when changing flags
nfs: do not export idmapped mounts
overlayfs: do not mount on top of idmapped mounts
ecryptfs: do not mount on top of idmapped mounts
ima: handle idmapped mounts
apparmor: handle idmapped mounts
fs: make helpers idmap mount aware
exec: handle idmapped mounts
would_dump: handle idmapped mounts
...
The WARN_ON() argument is a condition, not an error message. So this
code will print a stack trace but will not print the warning message.
Fix that and also change it to only WARN_ONCE().
Fixes: 4ddb74165a ("bpf: Extract nullable reg type conversion into a helper function")
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/YCzJlV3hnF%2Ft1Pk4@mwanda
Daniel Borkmann says:
====================
pull-request: bpf-next 2021-02-16
The following pull-request contains BPF updates for your *net-next* tree.
There's a small merge conflict between 7eeba1706e ("tcp: Add receive timestamp
support for receive zerocopy.") from net-next tree and 9cacf81f81 ("bpf: Remove
extra lock_sock for TCP_ZEROCOPY_RECEIVE") from bpf-next tree. Resolve as follows:
[...]
lock_sock(sk);
err = tcp_zerocopy_receive(sk, &zc, &tss);
err = BPF_CGROUP_RUN_PROG_GETSOCKOPT_KERN(sk, level, optname,
&zc, &len, err);
release_sock(sk);
[...]
We've added 116 non-merge commits during the last 27 day(s) which contain
a total of 156 files changed, 5662 insertions(+), 1489 deletions(-).
The main changes are:
1) Adds support of pointers to types with known size among global function
args to overcome the limit on max # of allowed args, from Dmitrii Banshchikov.
2) Add bpf_iter for task_vma which can be used to generate information similar
to /proc/pid/maps, from Song Liu.
3) Enable bpf_{g,s}etsockopt() from all sock_addr related program hooks. Allow
rewriting bind user ports from BPF side below the ip_unprivileged_port_start
range, both from Stanislav Fomichev.
4) Prevent recursion on fentry/fexit & sleepable programs and allow map-in-map
as well as per-cpu maps for the latter, from Alexei Starovoitov.
5) Add selftest script to run BPF CI locally. Also enable BPF ringbuffer
for sleepable programs, both from KP Singh.
6) Extend verifier to enable variable offset read/write access to the BPF
program stack, from Andrei Matei.
7) Improve tc & XDP MTU handling and add a new bpf_check_mtu() helper to
query device MTU from programs, from Jesper Dangaard Brouer.
8) Allow bpf_get_socket_cookie() helper also be called from [sleepable] BPF
tracing programs, from Florent Revest.
9) Extend x86 JIT to pad JMPs with NOPs for helping image to converge when
otherwise too many passes are required, from Gary Lin.
10) Verifier fixes on atomics with BPF_FETCH as well as function-by-function
verification both related to zero-extension handling, from Ilya Leoshkevich.
11) Better kernel build integration of resolve_btfids tool, from Jiri Olsa.
12) Batch of AF_XDP selftest cleanups and small performance improvement
for libbpf's xsk map redirect for newer kernels, from Björn Töpel.
13) Follow-up BPF doc and verifier improvements around atomics with
BPF_FETCH, from Brendan Jackman.
14) Permit zero-sized data sections e.g. if ELF .rodata section contains
read-only data from local variables, from Yonghong Song.
15) veth driver skb bulk-allocation for ndo_xdp_xmit, from Lorenzo Bianconi.
====================
Signed-off-by: David S. Miller <davem@davemloft.net>
test_global_func4 fails on s390 as reported by Yauheni in [1].
The immediate problem is that the zext code includes the instruction,
whose result needs to be zero-extended, into the zero-extension
patchlet, and if this instruction happens to be a branch, then its
delta is not adjusted. As a result, the verifier rejects the program
later.
However, according to [2], as far as the verifier's algorithm is
concerned and as specified by the insn_no_def() function, branching
insns do not define anything. This includes call insns, even though
one might argue that they define %r0.
This means that the real problem is that zero extension kicks in at
all. This happens because clear_caller_saved_regs() sets BPF_REG_0's
subreg_def after global function calls. This can be fixed in many
ways; this patch mimics what helper function call handling already
does.
[1] https://lore.kernel.org/bpf/20200903140542.156624-1-yauheni.kaliuta@redhat.com/
[2] https://lore.kernel.org/bpf/CAADnVQ+2RPKcftZw8d+B1UwB35cpBhpF5u3OocNh90D9pETPwg@mail.gmail.com/
Fixes: 51c39bb1d5 ("bpf: Introduce function-by-function verification")
Reported-by: Yauheni Kaliuta <yauheni.kaliuta@redhat.com>
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Link: https://lore.kernel.org/bpf/20210212040408.90109-1-iii@linux.ibm.com
Add an ability to pass a pointer to a type with known size in arguments
of a global function. Such pointers may be used to overcome the limit on
the maximum number of arguments, avoid expensive and tricky workarounds
and to have multiple output arguments.
A referenced type may contain pointers but indirect access through them
isn't supported.
The implementation consists of two parts. If a global function has an
argument that is a pointer to a type with known size then:
1) In btf_check_func_arg_match(): check that the corresponding
register points to NULL or to a valid memory region that is large enough
to contain the expected argument's type.
2) In btf_prepare_func_args(): set the corresponding register type to
PTR_TO_MEM_OR_NULL and its size to the size of the expected type.
Only global functions are supported because allowance of pointers for
static functions might break validation. Consider the following
scenario. A static function has a pointer argument. A caller passes
pointer to its stack memory. Because the callee can change referenced
memory verifier cannot longer assume any particular slot type of the
caller's stack memory hence the slot type is changed to SLOT_MISC. If
there is an operation that relies on slot type other than SLOT_MISC then
verifier won't be able to infer safety of the operation.
When verifier sees a static function that has a pointer argument
different from PTR_TO_CTX then it skips arguments check and continues
with "inline" validation with more information available. The operation
that relies on the particular slot type now succeeds.
Because global functions were not allowed to have pointer arguments
different from PTR_TO_CTX it's not possible to break existing and valid
code.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-4-me@ubique.spb.ru
Extract conversion from a register's nullable type to a type with a
value. The helper will be used in mark_ptr_not_null_reg().
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-3-me@ubique.spb.ru
Using "reg" for an array of bpf_reg_state and "reg[i + 1]" for an
individual bpf_reg_state is error-prone and verbose. Use "regs" for the
former and "reg" for the latter as other code nearby does.
Signed-off-by: Dmitrii Banshchikov <me@ubique.spb.ru>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210212205642.620788-2-me@ubique.spb.ru
Recently noticed that when mod32 with a known src reg of 0 is performed,
then the dst register is 32-bit truncated in verifier:
0: R1=ctx(id=0,off=0,imm=0) R10=fp0
0: (b7) r0 = 0
1: R0_w=inv0 R1=ctx(id=0,off=0,imm=0) R10=fp0
1: (b7) r1 = -1
2: R0_w=inv0 R1_w=inv-1 R10=fp0
2: (b4) w2 = -1
3: R0_w=inv0 R1_w=inv-1 R2_w=inv4294967295 R10=fp0
3: (9c) w1 %= w0
4: R0_w=inv0 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0
4: (b7) r0 = 1
5: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0
5: (1d) if r1 == r2 goto pc+1
R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0
6: R0_w=inv1 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0
6: (b7) r0 = 2
7: R0_w=inv2 R1_w=inv(id=0,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2_w=inv4294967295 R10=fp0
7: (95) exit
7: R0=inv1 R1=inv(id=0,umin_value=4294967295,umax_value=4294967295,var_off=(0x0; 0xffffffff)) R2=inv4294967295 R10=fp0
7: (95) exit
However, as a runtime result, we get 2 instead of 1, meaning the dst
register does not contain (u32)-1 in this case. The reason is fairly
straight forward given the 0 test leaves the dst register as-is:
# ./bpftool p d x i 23
0: (b7) r0 = 0
1: (b7) r1 = -1
2: (b4) w2 = -1
3: (16) if w0 == 0x0 goto pc+1
4: (9c) w1 %= w0
5: (b7) r0 = 1
6: (1d) if r1 == r2 goto pc+1
7: (b7) r0 = 2
8: (95) exit
This was originally not an issue given the dst register was marked as
completely unknown (aka 64 bit unknown). However, after 468f6eafa6
("bpf: fix 32-bit ALU op verification") the verifier casts the register
output to 32 bit, and hence it becomes 32 bit unknown. Note that for
the case where the src register is unknown, the dst register is marked
64 bit unknown. After the fix, the register is truncated by the runtime
and the test passes:
# ./bpftool p d x i 23
0: (b7) r0 = 0
1: (b7) r1 = -1
2: (b4) w2 = -1
3: (16) if w0 == 0x0 goto pc+2
4: (9c) w1 %= w0
5: (05) goto pc+1
6: (bc) w1 = w1
7: (b7) r0 = 1
8: (1d) if r1 == r2 goto pc+1
9: (b7) r0 = 2
10: (95) exit
Semantics also match with {R,W}x mod{64,32} 0 -> {R,W}x. Invalid div
has always been {R,W}x div{64,32} 0 -> 0. Rewrites are as follows:
mod32: mod64:
(16) if w0 == 0x0 goto pc+2 (15) if r0 == 0x0 goto pc+1
(9c) w1 %= w0 (9f) r1 %= r0
(05) goto pc+1
(bc) w1 = w1
Fixes: 468f6eafa6 ("bpf: fix 32-bit ALU op verification")
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Reviewed-by: John Fastabend <john.fastabend@gmail.com>
Acked-by: Alexei Starovoitov <ast@kernel.org>
The devmap bulk queue is allocated with GFP_ATOMIC and the allocation
may fail if there is no available space in existing percpu pool.
Since commit 75ccae62cb ("xdp: Move devmap bulk queue into struct net_device")
moved the bulk queue allocation to NETDEV_REGISTER callback, whose context
is allowed to sleep, use GFP_KERNEL instead of GFP_ATOMIC to let percpu
allocator extend the pool when needed and avoid possible failure of netdev
registration.
As the required alignment is natural, we can simply use alloc_percpu().
Fixes: 75ccae62cb ("xdp: Move devmap bulk queue into struct net_device")
Signed-off-by: Jun'ichi Nomura <junichi.nomura@nec.com>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Cc: Toke Høiland-Jørgensen <toke@redhat.com>
Link: https://lore.kernel.org/bpf/20210209082451.GA44021@jeru.linux.bs1.fc.nec.co.jp
Commit 15d83c4d7c ("bpf: Allow loading of a bpf_iter program")
cached btf_id in struct bpf_iter_target_info so later on
if it can be checked cheaply compared to checking registered names.
syzbot found a bug that uninitialized value may occur to
bpf_iter_target_info->btf_id. This is because we allocated
bpf_iter_target_info structure with kmalloc and never initialized
field btf_id afterwards. This uninitialized btf_id is typically
compared to a u32 bpf program func proto btf_id, and the chance
of being equal is extremely slim.
This patch fixed the issue by using kzalloc which will also
prevent future likely instances due to adding new fields.
Fixes: 15d83c4d7c ("bpf: Allow loading of a bpf_iter program")
Reported-by: syzbot+580f4f2a272e452d55cb@syzkaller.appspotmail.com
Signed-off-by: Yonghong Song <yhs@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210212005926.2875002-1-yhs@fb.com
Introduce task_vma bpf_iter to print memory information of a process. It
can be used to print customized information similar to /proc/<pid>/maps.
Current /proc/<pid>/maps and /proc/<pid>/smaps provide information of
vma's of a process. However, these information are not flexible enough to
cover all use cases. For example, if a vma cover mixed 2MB pages and 4kB
pages (x86_64), there is no easy way to tell which address ranges are
backed by 2MB pages. task_vma solves the problem by enabling the user to
generate customize information based on the vma (and vma->vm_mm,
vma->vm_file, etc.).
To access the vma safely in the BPF program, task_vma iterator holds
target mmap_lock while calling the BPF program. If the mmap_lock is
contended, task_vma unlocks mmap_lock between iterations to unblock the
writer(s). This lock contention avoidance mechanism is similar to the one
used in show_smaps_rollup().
Signed-off-by: Song Liu <songliubraving@fb.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Acked-by: Yonghong Song <yhs@fb.com>
Link: https://lore.kernel.org/bpf/20210212183107.50963-2-songliubraving@fb.com
All 32-bit variants of BPF_FETCH (add, and, or, xor, xchg, cmpxchg)
define a 32-bit subreg and thus have zext_dst set. Their encoding,
however, uses dst_reg field as a base register, which causes
opt_subreg_zext_lo32_rnd_hi32() to zero-extend said base register
instead of the one the insn really defines (r0 or src_reg).
Fix by properly choosing a register being defined, similar to how
check_atomic() already does that.
Signed-off-by: Ilya Leoshkevich <iii@linux.ibm.com>
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/bpf/20210210204502.83429-1-iii@linux.ibm.com
bpf_prog_realloc copies contents of struct bpf_prog.
The pointers have to be cleared before freeing old struct.
Reported-by: Ilya Leoshkevich <iii@linux.ibm.com>
Fixes: 700d4796ef ("bpf: Optimize program stats")
Fixes: ca06f55b90 ("bpf: Add per-program recursion prevention mechanism")
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Since sleepable programs are now executing under migrate_disable
the per-cpu maps are safe to use.
The map-in-map were ok to use in sleepable from the time sleepable
progs were introduced.
Note that non-preallocated maps are still not safe, since there is
no rcu_read_lock yet in sleepable programs and dynamically allocated
map elements are relying on rcu protection. The sleepable programs
have rcu_read_lock_trace instead. That limitation will be addresses
in the future.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Acked-by: KP Singh <kpsingh@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-9-alexei.starovoitov@gmail.com
Add per-program counter for number of times recursion prevention mechanism
was triggered and expose it via show_fdinfo and bpf_prog_info.
Teach bpftool to print it.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-7-alexei.starovoitov@gmail.com
Since both sleepable and non-sleepable programs execute under migrate_disable
add recursion prevention mechanism to both types of programs when they're
executed via bpf trampoline.
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
Signed-off-by: Daniel Borkmann <daniel@iogearbox.net>
Acked-by: Andrii Nakryiko <andrii@kernel.org>
Link: https://lore.kernel.org/bpf/20210210033634.62081-5-alexei.starovoitov@gmail.com
