The function mctp_unregister() reclaims the device's relevant resource
when a netcard detaches. However, a running routine may be unaware of
this and cause the use-after-free of the mdev->addrs object.
The race condition can be demonstrated below
cleanup thread another thread
|
unregister_netdev() | mctp_sendmsg()
... | ...
mctp_unregister() | rt = mctp_route_lookup()
... | mctl_local_output()
kfree(mdev->addrs) | ...
| saddr = rt->dev->addrs[0];
|
An attacker can adopt the (recent provided) mtcpserial driver with pty
to fake the device detaching and use the userfaultfd to increase the
race success chance (in mctp_sendmsg). The KASan report for such a POC
is shown below:
[ 86.051955] ==================================================================
[ 86.051955] BUG: KASAN: use-after-free in mctp_local_output+0x4e9/0xb7d
[ 86.051955] Read of size 1 at addr ffff888005f298c0 by task poc/295
[ 86.051955]
[ 86.051955] Call Trace:
[ 86.051955] <TASK>
[ 86.051955] dump_stack_lvl+0x33/0x42
[ 86.051955] print_report.cold.13+0xb2/0x6b3
[ 86.051955] ? preempt_schedule_irq+0x57/0x80
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] kasan_report+0xa5/0x120
[ 86.051955] ? mctp_local_output+0x4e9/0xb7d
[ 86.051955] mctp_local_output+0x4e9/0xb7d
[ 86.051955] ? mctp_dev_set_key+0x79/0x79
[ 86.051955] ? copyin+0x38/0x50
[ 86.051955] ? _copy_from_iter+0x1b6/0xf20
[ 86.051955] ? sysvec_apic_timer_interrupt+0x97/0xb0
[ 86.051955] ? asm_sysvec_apic_timer_interrupt+0x12/0x20
[ 86.051955] ? mctp_local_output+0x1/0xb7d
[ 86.051955] mctp_sendmsg+0x64d/0xdb0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] ? __fget_light+0x2fd/0x4f0
[ 86.051955] ? mctp_sk_close+0x20/0x20
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] ? __ia32_sys_getpeername+0xa0/0xa0
[ 86.051955] ? new_sync_write+0x335/0x550
[ 86.051955] ? alloc_file+0x22f/0x500
[ 86.051955] ? __ip_do_redirect+0x820/0x1820
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? vfs_write+0x44d/0x7b0
[ 86.051955] ? fput_many+0x15/0x120
[ 86.051955] ? ksys_write+0x155/0x1b0
[ 86.051955] ? __ia32_sys_read+0xa0/0xa0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] ? exit_to_user_mode_prepare+0x2f/0x120
[ 86.051955] ? syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955] RIP: 0033:0x7f82118a56b3
[ 86.051955] RSP: 002b:00007ffdb154b110 EFLAGS: 00000293 ORIG_RAX: 000000000000002c
[ 86.051955] RAX: ffffffffffffffda RBX: 0000000000000000 RCX: 00007f82118a56b3
[ 86.051955] RDX: 0000000000000010 RSI: 00007f8211cd4000 RDI: 0000000000000007
[ 86.051955] RBP: 00007ffdb154c1d0 R08: 00007ffdb154b164 R09: 000000000000000c
[ 86.051955] R10: 0000000000000000 R11: 0000000000000293 R12: 000055d779800db0
[ 86.051955] R13: 00007ffdb154c2b0 R14: 0000000000000000 R15: 0000000000000000
[ 86.051955] </TASK>
[ 86.051955]
[ 86.051955] Allocated by task 295:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] __kasan_kmalloc+0x84/0xa0
[ 86.051955] mctp_rtm_newaddr+0x242/0x610
[ 86.051955] rtnetlink_rcv_msg+0x2fd/0x8b0
[ 86.051955] netlink_rcv_skb+0x11c/0x340
[ 86.051955] netlink_unicast+0x439/0x630
[ 86.051955] netlink_sendmsg+0x752/0xc00
[ 86.051955] sock_sendmsg+0xdd/0x110
[ 86.051955] __sys_sendto+0x1cc/0x2a0
[ 86.051955] __x64_sys_sendto+0xd8/0x1b0
[ 86.051955] do_syscall_64+0x3a/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] Freed by task 301:
[ 86.051955] kasan_save_stack+0x1c/0x40
[ 86.051955] kasan_set_track+0x21/0x30
[ 86.051955] kasan_set_free_info+0x20/0x30
[ 86.051955] __kasan_slab_free+0x104/0x170
[ 86.051955] kfree+0x8c/0x290
[ 86.051955] mctp_dev_notify+0x161/0x2c0
[ 86.051955] raw_notifier_call_chain+0x8b/0xc0
[ 86.051955] unregister_netdevice_many+0x299/0x1180
[ 86.051955] unregister_netdevice_queue+0x210/0x2f0
[ 86.051955] unregister_netdev+0x13/0x20
[ 86.051955] mctp_serial_close+0x6d/0xa0
[ 86.051955] tty_ldisc_kill+0x31/0xa0
[ 86.051955] tty_ldisc_hangup+0x24f/0x560
[ 86.051955] __tty_hangup.part.28+0x2ce/0x6b0
[ 86.051955] tty_release+0x327/0xc70
[ 86.051955] __fput+0x1df/0x8b0
[ 86.051955] task_work_run+0xca/0x150
[ 86.051955] exit_to_user_mode_prepare+0x114/0x120
[ 86.051955] syscall_exit_to_user_mode+0x12/0x20
[ 86.051955] do_syscall_64+0x46/0x80
[ 86.051955] entry_SYSCALL_64_after_hwframe+0x44/0xae
[ 86.051955]
[ 86.051955] The buggy address belongs to the object at ffff888005f298c0
[ 86.051955] which belongs to the cache kmalloc-8 of size 8
[ 86.051955] The buggy address is located 0 bytes inside of
[ 86.051955] 8-byte region [ffff888005f298c0, ffff888005f298c8)
[ 86.051955]
[ 86.051955] The buggy address belongs to the physical page:
[ 86.051955] flags: 0x100000000000200(slab|node=0|zone=1)
[ 86.051955] raw: 0100000000000200 dead000000000100 dead000000000122 ffff888005c42280
[ 86.051955] raw: 0000000000000000 0000000080660066 00000001ffffffff 0000000000000000
[ 86.051955] page dumped because: kasan: bad access detected
[ 86.051955]
[ 86.051955] Memory state around the buggy address:
[ 86.051955] ffff888005f29780: 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00
[ 86.051955] ffff888005f29800: fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc
[ 86.051955] >ffff888005f29880: fc fc fc fb fc fc fc fc fa fc fc fc fc fa fc fc
[ 86.051955] ^
[ 86.051955] ffff888005f29900: fc fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc
[ 86.051955] ffff888005f29980: fc 00 fc fc fc fc 00 fc fc fc fc 00 fc fc fc fc
[ 86.051955] ==================================================================
To this end, just like the commit e04480920d ("Bluetooth: defer
cleanup of resources in hci_unregister_dev()") this patch defers the
destructive kfree(mdev->addrs) in mctp_unregister to the mctp_dev_put,
where the refcount of mdev is zero and the entire device is reclaimed.
This prevents the use-after-free because the sendmsg thread holds the
reference of mdev in the mctp_route object.
Fixes: 583be982d9 (mctp: Add device handling and netlink interface)
Signed-off-by: Lin Ma <linma@zju.edu.cn>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Link: https://lore.kernel.org/r/20220422114340.32346-1-linma@zju.edu.cn
Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Previously the skb was allocated with headroom MCTP_HEADER_MAXLEN,
but that isn't sufficient if we are using devs that are not MCTP
specific.
This also adds a check that the smctp_halen provided to sendmsg for
extended addressing is the correct size for the netdev.
Fixes: 833ef3b91d ("mctp: Populate socket implementation")
Reported-by: Matthew Rinaldi <mjrinal@g.clemson.edu>
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
dev_hard_header() returns the length of the header, so
we need to test for negative errors rather than non-zero.
Fixes: 889b7da23a ("mctp: Add initial routing framework")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Previously if an unregister notify handler ran twice (waiting for
netdev to be released) it would print a warning in mctp_unregister()
every subsequent time the unregister notify occured.
Instead we only need to worry about the case where a mctp_ptr is
set on an unknown device type.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
net/mctp/device.c:140:11: warning: Assigned value is garbage or undefined
[clang-analyzer-core.uninitialized.Assign]
mcb->idx = idx;
- Not a real problem due to how the callback runs, fix the warning.
net/mctp/route.c:458:4: warning: Value stored to 'msk' is never read
[clang-analyzer-deadcode.DeadStores]
msk = container_of(key->sk, struct mctp_sock, sk);
- 'msk' dead assignment can be removed here.
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
In the extended addressing local route output codepath
dev_get_by_index_rcu() doesn't take a dev_hold() so we shouldn't
dev_put().
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Previously there was a race that could allow the mctp_dev refcount
to hit zero:
rcu_read_lock();
mdev = __mctp_dev_get(dev);
// mctp_unregister() happens here, mdev->refs hits zero
mctp_dev_hold(dev);
rcu_read_unlock();
Now we make __mctp_dev_get() take the hold itself. It is safe to test
against the zero refcount because __mctp_dev_get() is called holding
rcu_read_lock and mctp_dev uses kfree_rcu().
Reported-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds some basic sanity checks for the source and dest
headers of packets on initial receive.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Currently, we have mctp_address_ok(), which checks if an EID is in the
"valid" range of 8-254 inclusive. However, 0 and 255 may also be valid
addresses, depending on context. 0 is the NULL EID, which may be set
when physical addressing is used. 255 is valid as a destination address
for broadcasts.
This change renames mctp_address_ok to mctp_address_unicast, and adds
similar helpers for broadcast and null EIDs, which will be used in an
upcoming commit.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Clang static analysis reports this problem
route.c:425:4: warning: Use of memory after it is freed
trace_mctp_key_acquire(key);
^~~~~~~~~~~~~~~~~~~~~~~~~~~
When mctp_key_add() fails, key is freed but then is later
used in trace_mctp_key_acquire(). Add an else statement
to use the key only when mctp_key_add() is successful.
Fixes: 4f9e1ba6de ("mctp: Add tracepoints for tag/key handling")
Signed-off-by: Tom Rix <trix@redhat.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds a couple of new ioctls for mctp sockets:
SIOCMCTPALLOCTAG and SIOCMCTPDROPTAG. These ioctls provide facilities
for explicit allocation / release of tags, overriding the automatic
allocate-on-send/release-on-reply and timeout behaviours. This allows
userspace more control over messages that may not fit a simple
request/response model.
In order to indicate a pre-allocated tag to the sendmsg() syscall, we
introduce a new flag to the struct sockaddr_mctp.smctp_tag value:
MCTP_TAG_PREALLOC.
Additional changes from Jeremy Kerr <jk@codeconstruct.com.au>.
Contains a fix that was:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, we require an exact match on an incoming packet's dest
address, and the key's local_addr field.
In a future change, we may want to set up a key before packets are
routed, meaning we have no local address to match on.
This change allows key lookups to match on local_addr = MCTP_ADDR_ANY.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, we have a couple of paths that check that an EID matches, or
the match value is MCTP_ADDR_ANY.
Rather than open coding this, add a little helper.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds a few more tests to check the key/tag lookups on route
input. We add a specific entry to the keys lists, route a packet with
specific header values, and check for key match/mismatch.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This is a definition for the tag-owner flag, which has TO as a standard
abbreviation. We'll want to add a helper for the actual tag value in a
future change.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add neighbour source flag in mctp_neigh_remove(...) to allow removal of
only static neighbours.
This should be a no-op change and might be useful later when mctp can
have MCTP_NEIGH_DISCOVER neighbours.
Signed-off-by: Gagan Kumar <gagan1kumar.cs@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
The 'if (dev)' statement already move into dev_{put , hold}, so remove
redundant if statements.
Signed-off-by: Xu Wang <vulab@iscas.ac.cn>
Signed-off-by: David S. Miller <davem@davemloft.net>
We need to test against the existing route type, not
the rtm_type in the netlink request.
Fixes: 83f0a0b728 ("mctp: Specify route types, require rtm_type in RTM_*ROUTE messages")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
In our test device, we're currently freeing skbs in the transmit path
with kfree(), rather than kfree_skb(). This change uses the correct
kfree_skb() instead.
Fixes: ded21b7229 ("mctp: Add test utils")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Dan Carpenter <dan.carpenter@oracle.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
In 99ce45d5e, we moved a route refcount decrement from
mctp_do_fragment_route into the caller. This invalidates the assumption
that the route test makes about refcount behaviour, so the route tests
fail.
This change fixes the test case to suit the new refcount behaviour.
Fixes: 99ce45d5e7 ("mctp: Implement extended addressing")
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
struct sockaddr_mctp_ext.__smctp_paddin0 has to be checked for being set
to zero, otherwise it cannot be utilised in the future.
Fixes: 99ce45d5e7 ("mctp: Implement extended addressing")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
In order to have the padding fields actually usable in the future,
there have to be checks that user space doesn't supply non-zero garbage
there. It is also worth setting these padding fields to zero, unless
it is known that they have been already zeroed.
Cc: stable@vger.kernel.org # v5.15
Fixes: 5a20dd46b8 ("mctp: Be explicit about struct sockaddr_mctp padding")
Signed-off-by: Eugene Syromiatnikov <esyr@redhat.com>
Acked-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Now that we have an extension for MCTP data in skbs, populate the flow
when a key has been created for the packet, and add a device driver
operation to inform of flow destruction.
Includes a fix for a warning with test builds:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds a new skb extension for MCTP, to represent a
request/response flow.
The intention is to use this in a later change to allow i2c controllers
to correctly configure a multiplexer over a flow.
Since we have a cleanup function in the core path (if an extension is
present), we'll need to make CONFIG_MCTP a bool, rather than a tristate.
Includes a fix for a build warning with clang:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
In a future change, we will want the key available for future use after
allocating a new tag. This change returns the key from
mctp_alloc_local_tag, rather than just key->tag.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change allows an extended address struct - struct sockaddr_mctp_ext
- to be passed to sendmsg/recvmsg. This allows userspace to specify
output ifindex and physical address information (for sendmsg) or receive
the input ifindex/physaddr for incoming messages (for recvmsg). This is
typically used by userspace for MCTP address discovery and assignment
operations.
The extended addressing facility is conditional on a new sockopt:
MCTP_OPT_ADDR_EXT; userspace must explicitly enable addressing before
the kernel will consume/populate the extended address data.
Includes a fix for an uninitialised var:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
mctp_key_alloc() returns a key already referenced.
The mctp_route_input() path receives a packet for a bind socket and
allocates a key. It passes the key to mctp_key_add() which takes a
refcount and adds the key to lists. mctp_route_input() should then
release its own refcount when setting the key pointer to NULL.
In the mctp_alloc_local_tag() path (for mctp_local_output()) we
similarly need to unref the key before returning (mctp_reserve_tag()
takes a refcount and adds the key to lists).
Fixes: 73c618456d ("mctp: locking, lifetime and validity changes for sk_keys")
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Reviewed-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add multi-packet route input tests, for message reassembly. These will
feed packets to be received by a bound socket, or dropped.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a few tests for single-packet route inputs, testing the
mctp_route_input function.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a few tests for the initial packet ingress through
mctp_pkttype_receive function; mainly packet header sanity checks. Full
input routing checks will be added as a separate change.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds the first kunit test for the mctp subsystem, and an
initial test for the fragmentation path.
We're adding tests under a new net/mctp/test/ directory.
Incorporates a fix for module configs:
Reported-by: kernel test robot <lkp@intel.com>
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This reverts commit 4f42ad2011, reversing
changes made to ea2dd331bf.
These chanfges break the build when mctp is modular.
Signed-off-by: David S. Miller <davem@davemloft.net>
Add multi-packet route input tests, for message reassembly. These will
feed packets to be received by a bound socket, or dropped.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a few tests for single-packet route inputs, testing the
mctp_route_input function.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Add a few tests for the initial packet ingress through
mctp_pkttype_receive function; mainly packet header sanity checks. Full
input routing checks will be added as a separate change.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
This change adds the first kunit test for the mctp subsystem, and an
initial test for the fragmentation path.
We're adding tests under a new net/mctp/test/ directory.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
A route's RTAX_MTU can be set in nested RTAX_METRICS
Signed-off-by: Matt Johnston <matt@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
In a future change, we'll want to provide a registration call for
mctp-specific devices. This requires us to have the networks established
before device driver inits, so run the core init as a subsys_initcall.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
The tag allocation, release and bind events are somewhat opaque outside
the kernel; this change adds a few tracepoints to assist in
instrumentation and debugging.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Currently, a MCTP (local-eid,remote-eid,tag) tuple is allocated to a
socket on send, and only expires when the socket is closed.
This change introduces a tag timeout, freeing the tuple after a fixed
expiry - currently six seconds. This is greater than (but close to) the
max response timeout in upper-layer bindings.
Signed-off-by: Jeremy Kerr <jk@codeconstruct.com.au>
Signed-off-by: David S. Miller <davem@davemloft.net>
Lin Ma