Recently to prevent issues with SECCOMP_RET_KILL and similar signals
being changed before they are delivered SA_IMMUTABLE was added.
Unfortunately this broke debuggers[1][2] which reasonably expect
to be able to trap synchronous SIGTRAP and SIGSEGV even when
the target process is not configured to handle those signals.
Add force_exit_sig and use it instead of force_fatal_sig where
historically the code has directly called do_exit. This has the
implementation benefits of going through the signal exit path
(including generating core dumps) without the danger of allowing
userspace to ignore or change these signals.
This avoids userspace regressions as older kernels exited with do_exit
which debuggers also can not intercept.
In the future is should be possible to improve the quality of
implementation of the kernel by changing some of these force_exit_sig
calls to force_fatal_sig. That can be done where it matters on
a case-by-case basis with careful analysis.
Reported-by: Kyle Huey <me@kylehuey.com>
Reported-by: kernel test robot <oliver.sang@intel.com>
[1] https://lkml.kernel.org/r/CAP045AoMY4xf8aC_4QU_-j7obuEPYgTcnQQP3Yxk=2X90jtpjw@mail.gmail.com
[2] https://lkml.kernel.org/r/20211117150258.GB5403@xsang-OptiPlex-9020
Fixes: 00b06da29c ("signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed")
Fixes: a3616a3c02 ("signal/m68k: Use force_sigsegv(SIGSEGV) in fpsp040_die")
Fixes: 83a1f27ad7 ("signal/powerpc: On swapcontext failure force SIGSEGV")
Fixes: 9bc508cf07 ("signal/s390: Use force_sigsegv in default_trap_handler")
Fixes: 086ec444f8 ("signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig")
Fixes: c317d306d5 ("signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails")
Fixes: 695dd0d634 ("signal/x86: In emulate_vsyscall force a signal instead of calling do_exit")
Fixes: 1fbd60df8a ("signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.")
Fixes: 941edc5bf1 ("exit/syscall_user_dispatch: Send ordinary signals on failure")
Link: https://lkml.kernel.org/r/871r3dqfv8.fsf_-_@email.froward.int.ebiederm.org
Reviewed-by: Kees Cook <keescook@chromium.org>
Tested-by: Kees Cook <keescook@chromium.org>
Tested-by: Kyle Huey <khuey@kylehuey.com>
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Pull exit cleanups from Eric Biederman:
"While looking at some issues related to the exit path in the kernel I
found several instances where the code is not using the existing
abstractions properly.
This set of changes introduces force_fatal_sig a way of sending a
signal and not allowing it to be caught, and corrects the misuse of
the existing abstractions that I found.
A lot of the misuse of the existing abstractions are silly things such
as doing something after calling a no return function, rolling BUG by
hand, doing more work than necessary to terminate a kernel thread, or
calling do_exit(SIGKILL) instead of calling force_sig(SIGKILL).
In the review a deficiency in force_fatal_sig and force_sig_seccomp
where ptrace or sigaction could prevent the delivery of the signal was
found. I have added a change that adds SA_IMMUTABLE to change that
makes it impossible to interrupt the delivery of those signals, and
allows backporting to fix force_sig_seccomp
And Arnd found an issue where a function passed to kthread_run had the
wrong prototype, and after my cleanup was failing to build."
* 'exit-cleanups-for-v5.16' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (23 commits)
soc: ti: fix wkup_m3_rproc_boot_thread return type
signal: Add SA_IMMUTABLE to ensure forced siganls do not get changed
signal: Replace force_sigsegv(SIGSEGV) with force_fatal_sig(SIGSEGV)
exit/r8188eu: Replace the macro thread_exit with a simple return 0
exit/rtl8712: Replace the macro thread_exit with a simple return 0
exit/rtl8723bs: Replace the macro thread_exit with a simple return 0
signal/x86: In emulate_vsyscall force a signal instead of calling do_exit
signal/sparc32: In setup_rt_frame and setup_fram use force_fatal_sig
signal/sparc32: Exit with a fatal signal when try_to_clear_window_buffer fails
exit/syscall_user_dispatch: Send ordinary signals on failure
signal: Implement force_fatal_sig
exit/kthread: Have kernel threads return instead of calling do_exit
signal/s390: Use force_sigsegv in default_trap_handler
signal/vm86_32: Properly send SIGSEGV when the vm86 state cannot be saved.
signal/vm86_32: Replace open coded BUG_ON with an actual BUG_ON
signal/sparc: In setup_tsb_params convert open coded BUG into BUG
signal/powerpc: On swapcontext failure force SIGSEGV
signal/sh: Use force_sig(SIGKILL) instead of do_group_exit(SIGKILL)
signal/mips: Update (_save|_restore)_fp_context to fail with -EFAULT
signal/sparc32: Remove unreachable do_exit in do_sparc_fault
...
Now that force_fatal_sig exists it is unnecessary and a bit confusing
to use force_sigsegv in cases where the simpler force_fatal_sig is
wanted. So change every instance we can to make the code clearer.
Acked-by: Geert Uytterhoeven <geert@linux-m68k.org>
Reviewed-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Link: https://lkml.kernel.org/r/877de7jrev.fsf@disp2133
Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
If the register state may be partial and corrupted instead of calling
do_exit, call force_sigsegv(SIGSEGV). Which properly kills the
process with SIGSEGV and does not let any more userspace code execute,
instead of just killing one thread of the process and potentially
confusing everything.
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Paul Mackerras <paulus@samba.org>
Cc: linuxppc-dev@lists.ozlabs.org
History-tree: git://git.kernel.org/pub/scm/linux/kernel/git/tglx/history.git
Fixes: 756f1ae8a44e ("PPC32: Rework signal code and add a swapcontext system call.")
Fixes: 04879b04bf50 ("[PATCH] ppc64: VMX (Altivec) support & signal32 rework, from Ben Herrenschmidt")
Link: https://lkml.kernel.org/r/20211020174406.17889-7-ebiederm@xmission.com
Signed-off-by: Eric W. Biederman <ebiederm@xmission.com>
Turn fault_in_pages_{readable,writeable} into versions that return the
number of bytes not faulted in, similar to copy_to_user, instead of
returning a non-zero value when any of the requested pages couldn't be
faulted in. This supports the existing users that require all pages to
be faulted in as well as new users that are happy if any pages can be
faulted in.
Rename the functions to fault_in_{readable,writeable} to make sure
this change doesn't silently break things.
Neither of these functions is entirely trivial and it doesn't seem
useful to inline them, so move them to mm/gup.c.
Signed-off-by: Andreas Gruenbacher <agruenba@redhat.com>
When an interrupt is taken, the SRR registers are set to return to where
it left off. Unless they are modified in the meantime, or the return
address or MSR are modified, there is no need to reload these registers
when returning from interrupt.
Introduce per-CPU flags that track the validity of SRR and HSRR
registers. These are cleared when returning from interrupt, when
using the registers for something else (e.g., OPAL calls), when
adjusting the return address or MSR of a context, and when context
switching (which changes the return address and MSR).
This improves the performance of interrupt returns.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Fold in fixup patch from Nick]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210617155116.2167984-5-npiggin@gmail.com
PPC_TRANSACTIONAL_MEM is only on book3s/64
SPE is only on booke
PPC_TRANSACTIONAL_MEM selects ALTIVEC and VSX
Therefore, within PPC_TRANSACTIONAL_MEM sections,
ALTIVEC and VSX are always defined while SPE never is.
Remove all SPE code and all #ifdef ALTIVEC and VSX in tm
functions.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a069a348ee3c2fe3123a5a93695c2b35dc42cb40.1623340691.git.christophe.leroy@csgroup.eu
- Enable KFENCE for 32-bit.
- Implement EBPF for 32-bit.
- Convert 32-bit to do interrupt entry/exit in C.
- Convert 64-bit BookE to do interrupt entry/exit in C.
- Changes to our signal handling code to use user_access_begin/end() more extensively.
- Add support for time namespaces (CONFIG_TIME_NS)
- A series of fixes that allow us to reenable STRICT_KERNEL_RWX.
- Other smaller features, fixes & cleanups.
Thanks to: Alexey Kardashevskiy, Andreas Schwab, Andrew Donnellan, Aneesh Kumar K.V,
Athira Rajeev, Bhaskar Chowdhury, Bixuan Cui, Cédric Le Goater, Chen Huang, Chris
Packham, Christophe Leroy, Christopher M. Riedl, Colin Ian King, Dan Carpenter, Daniel
Axtens, Daniel Henrique Barboza, David Gibson, Davidlohr Bueso, Denis Efremov,
dingsenjie, Dmitry Safonov, Dominic DeMarco, Fabiano Rosas, Ganesh Goudar, Geert
Uytterhoeven, Geetika Moolchandani, Greg Kurz, Guenter Roeck, Haren Myneni, He Ying,
Jiapeng Chong, Jordan Niethe, Laurent Dufour, Lee Jones, Leonardo Bras, Li Huafei,
Madhavan Srinivasan, Mahesh Salgaonkar, Masahiro Yamada, Nathan Chancellor, Nathan
Lynch, Nicholas Piggin, Oliver O'Halloran, Paul Menzel, Pu Lehui, Randy Dunlap, Ravi
Bangoria, Rosen Penev, Russell Currey, Santosh Sivaraj, Sebastian Andrzej Siewior,
Segher Boessenkool, Shivaprasad G Bhat, Srikar Dronamraju, Stephen Rothwell, Thadeu Lima
de Souza Cascardo, Thomas Gleixner, Tony Ambardar, Tyrel Datwyler, Vaibhav Jain,
Vincenzo Frascino, Xiongwei Song, Yang Li, Yu Kuai, Zhang Yunkai.
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Merge tag 'powerpc-5.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux
Pull powerpc updates from Michael Ellerman:
- Enable KFENCE for 32-bit.
- Implement EBPF for 32-bit.
- Convert 32-bit to do interrupt entry/exit in C.
- Convert 64-bit BookE to do interrupt entry/exit in C.
- Changes to our signal handling code to use user_access_begin/end()
more extensively.
- Add support for time namespaces (CONFIG_TIME_NS)
- A series of fixes that allow us to reenable STRICT_KERNEL_RWX.
- Other smaller features, fixes & cleanups.
Thanks to Alexey Kardashevskiy, Andreas Schwab, Andrew Donnellan, Aneesh
Kumar K.V, Athira Rajeev, Bhaskar Chowdhury, Bixuan Cui, Cédric Le
Goater, Chen Huang, Chris Packham, Christophe Leroy, Christopher M.
Riedl, Colin Ian King, Dan Carpenter, Daniel Axtens, Daniel Henrique
Barboza, David Gibson, Davidlohr Bueso, Denis Efremov, dingsenjie,
Dmitry Safonov, Dominic DeMarco, Fabiano Rosas, Ganesh Goudar, Geert
Uytterhoeven, Geetika Moolchandani, Greg Kurz, Guenter Roeck, Haren
Myneni, He Ying, Jiapeng Chong, Jordan Niethe, Laurent Dufour, Lee
Jones, Leonardo Bras, Li Huafei, Madhavan Srinivasan, Mahesh Salgaonkar,
Masahiro Yamada, Nathan Chancellor, Nathan Lynch, Nicholas Piggin,
Oliver O'Halloran, Paul Menzel, Pu Lehui, Randy Dunlap, Ravi Bangoria,
Rosen Penev, Russell Currey, Santosh Sivaraj, Sebastian Andrzej Siewior,
Segher Boessenkool, Shivaprasad G Bhat, Srikar Dronamraju, Stephen
Rothwell, Thadeu Lima de Souza Cascardo, Thomas Gleixner, Tony Ambardar,
Tyrel Datwyler, Vaibhav Jain, Vincenzo Frascino, Xiongwei Song, Yang Li,
Yu Kuai, and Zhang Yunkai.
* tag 'powerpc-5.13-1' of git://git.kernel.org/pub/scm/linux/kernel/git/powerpc/linux: (302 commits)
powerpc/signal32: Fix erroneous SIGSEGV on RT signal return
powerpc: Avoid clang uninitialized warning in __get_user_size_allowed
powerpc/papr_scm: Mark nvdimm as unarmed if needed during probe
powerpc/kvm: Fix build error when PPC_MEM_KEYS/PPC_PSERIES=n
powerpc/kasan: Fix shadow start address with modules
powerpc/kernel/iommu: Use largepool as a last resort when !largealloc
powerpc/kernel/iommu: Align size for IOMMU_PAGE_SIZE() to save TCEs
powerpc/44x: fix spelling mistake in Kconfig "varients" -> "variants"
powerpc/iommu: Annotate nested lock for lockdep
powerpc/iommu: Do not immediately panic when failed IOMMU table allocation
powerpc/iommu: Allocate it_map by vmalloc
selftests/powerpc: remove unneeded semicolon
powerpc/64s: remove unneeded semicolon
powerpc/eeh: remove unneeded semicolon
powerpc/selftests: Add selftest to test concurrent perf/ptrace events
powerpc/selftests/perf-hwbreak: Add testcases for 2nd DAWR
powerpc/selftests/perf-hwbreak: Coalesce event creation code
powerpc/selftests/ptrace-hwbreak: Add testcases for 2nd DAWR
powerpc/configs: Add IBMVNIC to some 64-bit configs
selftests/powerpc: Add uaccess flush test
...
Return of user_read_access_begin() is tested the wrong way,
leading to a SIGSEGV when the user address is valid and likely
an Oops when the user address is bad.
Fix the test.
Fixes: 887f3ceb51 ("powerpc/signal32: Convert do_setcontext[_tm]() to user access block")
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a29aadc54c93bcbf069a83615fa102ca0f59c3ae.1619185912.git.christophe.leroy@csgroup.eu
All subarchitectures always save all GPRs to pt_regs interrupt frames
now. Remove FULL_REGS and associated bits.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210316104206.407354-11-npiggin@gmail.com
Add missing fault exit label in unsafe_copy_from_user() in order to
avoid following build failure with CONFIG_SPE
CC arch/powerpc/kernel/signal_32.o
arch/powerpc/kernel/signal_32.c: In function 'restore_user_regs':
arch/powerpc/kernel/signal_32.c:565:36: error: macro "unsafe_copy_from_user" requires 4 arguments, but only 3 given
565 | ELF_NEVRREG * sizeof(u32));
| ^
In file included from ./include/linux/uaccess.h:11,
from ./include/linux/sched/task.h:11,
from ./include/linux/sched/signal.h:9,
from ./include/linux/rcuwait.h:6,
from ./include/linux/percpu-rwsem.h:7,
from ./include/linux/fs.h:33,
from ./include/linux/huge_mm.h:8,
from ./include/linux/mm.h:707,
from arch/powerpc/kernel/signal_32.c:17:
./arch/powerpc/include/asm/uaccess.h:428: note: macro "unsafe_copy_from_user" defined here
428 | #define unsafe_copy_from_user(d, s, l, e) \
|
arch/powerpc/kernel/signal_32.c:564:3: error: 'unsafe_copy_from_user' undeclared (first use in this function); did you mean 'raw_copy_from_user'?
564 | unsafe_copy_from_user(current->thread.evr, &sr->mc_vregs,
| ^~~~~~~~~~~~~~~~~~~~~
| raw_copy_from_user
arch/powerpc/kernel/signal_32.c:564:3: note: each undeclared identifier is reported only once for each function it appears in
make[3]: *** [arch/powerpc/kernel/signal_32.o] Error 1
Fixes: 627b72bee8 ("powerpc/signal32: Convert restore_[tm]_user_regs() to user access block")
Reported-by: kernel test robot <lkp@intel.com>
Reported-by: Guenter Roeck <linux@roeck-us.net>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/aad2cb1801a3cc99bc27081022925b9fc18a0dfb.1618159169.git.christophe.leroy@csgroup.eu
In preparation of using user_access_begin/end in restore_user_regs(),
move the access_ok() inside the function.
It makes no difference as the behaviour on a failed access_ok() is
the same as on failed restore_user_regs().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c106eb2f37c3040f1fd38b40e50c670feb7cb835.1616151715.git.christophe.leroy@csgroup.eu
In the same spirit as commit f1cf4f93de ("powerpc/signal32: Remove
ifdefery in middle of if/else")
MSR_TM_ACTIVE() is always defined and returns always 0 when
CONFIG_PPC_TRANSACTIONAL_MEM is not selected, so the awful
ifdefery in the middle of an if/else can be removed.
Make 'msr_hi' a 'long long' to avoid build failure on PPC32
due to the 32 bits left shift.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/a4b48b2f0be1ef13fc8e57452b7f8350da28d521.1616151715.git.christophe.leroy@csgroup.eu
Convention is to prefix functions with __unsafe_ instead of
suffixing it with _unsafe.
Rename save_user_regs_unsafe() and save_general_regs_unsafe()
accordingly, that is respectively __unsafe_save_general_regs() and
__unsafe_save_user_regs().
Suggested-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8cef43607e5b35a7fd0829dec812d88beb570df2.1616151715.git.christophe.leroy@csgroup.eu
PPC32 encounters a KUAP fault when trying to handle a signal with
VDSO unmapped.
Kernel attempted to read user page (7fc07ec0) - exploit attempt? (uid: 0)
BUG: Unable to handle kernel data access on read at 0x7fc07ec0
Faulting instruction address: 0xc00111d4
Oops: Kernel access of bad area, sig: 11 [#1]
BE PAGE_SIZE=16K PREEMPT CMPC885
CPU: 0 PID: 353 Comm: sigreturn_vdso Not tainted 5.12.0-rc4-s3k-dev-01553-gb30c310ea220 #4814
NIP: c00111d4 LR: c0005a28 CTR: 00000000
REGS: cadb3dd0 TRAP: 0300 Not tainted (5.12.0-rc4-s3k-dev-01553-gb30c310ea220)
MSR: 00009032 <EE,ME,IR,DR,RI> CR: 48000884 XER: 20000000
DAR: 7fc07ec0 DSISR: 88000000
GPR00: c0007788 cadb3e90 c28d4a40 7fc07ec0 7fc07ed0 000004e0 7fc07ce0 00000000
GPR08: 00000001 00000001 7fc07ec0 00000000 28000282 1001b828 100a0920 00000000
GPR16: 100cac0c 100b0000 105c43a4 105c5685 100d0000 100d0000 100d0000 100b2e9e
GPR24: ffffffff 105c43c8 00000000 7fc07ec8 cadb3f40 cadb3ec8 c28d4a40 00000000
NIP [c00111d4] flush_icache_range+0x90/0xb4
LR [c0005a28] handle_signal32+0x1bc/0x1c4
Call Trace:
[cadb3e90] [100d0000] 0x100d0000 (unreliable)
[cadb3ec0] [c0007788] do_notify_resume+0x260/0x314
[cadb3f20] [c000c764] syscall_exit_prepare+0x120/0x184
[cadb3f30] [c00100b4] ret_from_syscall+0xc/0x28
--- interrupt: c00 at 0xfe807f8
NIP: 0fe807f8 LR: 10001060 CTR: c0139378
REGS: cadb3f40 TRAP: 0c00 Not tainted (5.12.0-rc4-s3k-dev-01553-gb30c310ea220)
MSR: 0000d032 <EE,PR,ME,IR,DR,RI> CR: 28000482 XER: 20000000
GPR00: 00000025 7fc081c0 77bb1690 00000000 0000000a 28000482 00000001 0ff03a38
GPR08: 0000d032 00006de5 c28d4a40 00000009 88000482 1001b828 100a0920 00000000
GPR16: 100cac0c 100b0000 105c43a4 105c5685 100d0000 100d0000 100d0000 100b2e9e
GPR24: ffffffff 105c43c8 00000000 77ba7628 10002398 10010000 10002124 00024000
NIP [0fe807f8] 0xfe807f8
LR [10001060] 0x10001060
--- interrupt: c00
Instruction dump:
38630010 7c001fac 38630010 4200fff0 7c0004ac 4c00012c 4e800020 7c001fac
2c0a0000 38630010 4082ffcc 4bffffe4 <7c00186c> 2c070000 39430010 4082ff8c
---[ end trace 3973fb72b049cb06 ]---
This is because flush_icache_range() is called on user addresses.
The same problem was detected some time ago on PPC64. It was fixed by
enabling KUAP in commit 59bee45b97 ("powerpc/mm: Fix missing KUAP
disable in flush_coherent_icache()").
PPC32 doesn't use flush_coherent_icache() and fallbacks on
clean_dcache_range() and invalidate_icache_range().
We could fix it similarly by enabling user access in those functions,
but this is overkill for just flushing two instructions.
The two instructions are 8 bytes aligned, so a single dcbst/icbi is
enough to flush them. Do like __patch_instruction() and inline
a dcbst followed by an icbi just after the write of the instructions,
while user access is still allowed. The isync is not required because
rfi will be used to return to user.
icbi() is handled as a read so read-write user access is needed.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/bde9154e5351a5ac7bca3d59cdb5a5e8edacbb79.1617199569.git.christophe.leroy@csgroup.eu
Usually sigset_t is exactly 8B which is a "trivial" size and does not
warrant using __copy_from_user(). Use __get_user() directly in
anticipation of future work to remove the trivial size optimizations
from __copy_from_user().
The ppc32 implementation of get_sigset_t() previously called
copy_from_user() which, unlike __copy_from_user(), calls access_ok().
Replacing this w/ __get_user() (no access_ok()) is fine here since both
callsites in signal_32.c are preceded by an earlier access_ok().
Signed-off-by: Christopher M. Riedl <cmr@codefail.de>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20210227011259.11992-11-cmr@codefail.de
This mirrors the behavior in handle_rt_signal32, to obey kernel endianness
rather than assume a 32-bit process is big-endian. Without this change,
any 32-bit little-endian process will SIGILL immediately upon handling a
signal.
Signed-off-by: Joseph J Allen <eerykitty@gmail.com>
Signed-off-by: Will Springer <skirmisher@protonmail.com>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2058876.irdbgypaU6@sheen
This is copied from arm64.
Instead of using runtime generated signal trampoline offsets,
get offsets at buildtime.
If the said trampoline doesn't exist, build will fail. So no
need to check whether the trampoline exists or not in the VDSO.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f8bfd6812c3e3678b1cdb4d55a52f9eb022b40d3.1601197618.git.christophe.leroy@csgroup.eu
All other architectures but s390 use a void pointer named 'vdso'
to reference the VDSO mapping.
In a following patch, the VDSO data page will be put in front of
text, vdso_base will then not anymore point to VDSO text.
To avoid confusion between vdso_base and VDSO text, rename vdso_base
into vdso and make it a void __user *.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/8e6cefe474aa4ceba028abb729485cd46c140990.1601197618.git.christophe.leroy@csgroup.eu
Change those two functions to be used within a user access block.
For that, change save_general_regs() to and unsafe_save_general_regs(),
then replace all user accesses by unsafe_ versions.
This series leads to a reduction from 2.55s to 1.73s of
the system CPU time with the following microbench app
on an mpc832x with KUAP (approx 32%)
Without KUAP, the difference is in the noise.
void sigusr1(int sig) { }
int main(int argc, char **argv)
{
int i = 100000;
signal(SIGUSR1, sigusr1);
for (;i--;)
raise(SIGUSR1);
exit(0);
}
An additional 0.10s reduction is achieved by removing
CONFIG_PPC_FPU, as the mpc832x has no FPU.
A bit less spectacular on an 8xx as KUAP is less heavy, prior to
the series (with KUAP) it ran in 8.10 ms. Once applies the removal
of FPU regs handling, we get 7.05s. With the full series, we get 6.9s.
If artificially re-activating FPU regs handling with the full series,
we get 7.6s.
So for the 8xx, the removal of the FPU regs copy is what makes the
difference, but the rework of handle_signal also have a benefit.
Same as above, without KUAP the difference is in the noise.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Fixup typo in SPE handling]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/c7b37b385ccf9666066452e58f018a86573f83e8.1597770847.git.christophe.leroy@csgroup.eu
Reorder actions in save_user_regs() and save_tm_user_regs() to
regroup copies together in order to switch to user_access_begin()
logic in a later patch.
Move non-copy actions into new functions called
prepare_save_user_regs() and prepare_save_tm_user_regs().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/f6eac65781b4a57220477c8864bca2b57f29a5d5.1597770847.git.christophe.leroy@csgroup.eu
put_sigset_t() calls copy_to_user() for copying two words.
This is terribly inefficient for copying two words.
By switching to unsafe_put_user(), we end up with something as
simple as:
3cc: 81 3d 00 00 lwz r9,0(r29)
3d0: 91 26 00 b4 stw r9,180(r6)
3d4: 81 3d 00 04 lwz r9,4(r29)
3d8: 91 26 00 b8 stw r9,184(r6)
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/06def97e87ac1c4ae8e3197e0982e1fab7b3c8ae.1597770847.git.christophe.leroy@csgroup.eu
On the same way as handle_signal32(), replace all user
accesses with equivalent unsafe_ versions, and move the
trampoline code icache flush outside the user access block.
Functions that have no unsafe_ equivalent also remains outside
the access block.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/2974314226256f958e2984912b48883ef1754185.1597770847.git.christophe.leroy@csgroup.eu
Those two functions are similar and serving the same purpose.
To ease refactorisation, move them close to each other.
This is pure move, no code change, no cosmetic. Yes, checkpatch is
not happy, most will clear later.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/dbce67900bf566bcf40179467bf1eb500814c405.1597770847.git.christophe.leroy@csgroup.eu
If something is bad in the frame, there is no point in
knowing which part of the frame exactly is wrong as it
got allocated as a single block.
Always print the root address of the frame in case of
failed user access, just like handle_signal32().
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/691895bd31fee89a2d8370befd66ad4eff5b63f2.1597770847.git.christophe.leroy@csgroup.eu
Instead of calling get_tm_stackpointer() from the caller, call it
directly from get_sigframe(). This avoids a double call and
allows get_tm_stackpointer() to become static and be inlined
into get_sigframe() by GCC.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/abfdc105b8b28c4eb3ab9a26297d17f302b600ea.1597770847.git.christophe.leroy@csgroup.eu
There is no point in copying floating point regs when there
is no FPU and MATH_EMULATION is not selected.
Create a new CONFIG_PPC_FPU_REGS bool that is selected by
CONFIG_MATH_EMULATION and CONFIG_PPC_FPU, and use it to
opt out everything related to fp_state in thread_struct.
The asm const used only by fpu.S are opted out with CONFIG_PPC_FPU
as fpu.S build is conditionnal to CONFIG_PPC_FPU.
The following app spends approx 8.1 seconds system time on an 8xx
without the patch, and 7.0 seconds with the patch (13.5% reduction).
On an 832x, it spends approx 2.6 seconds system time without
the patch and 2.1 seconds with the patch (19% reduction).
void sigusr1(int sig) { }
int main(int argc, char **argv)
{
int i = 100000;
signal(SIGUSR1, sigusr1);
for (;i--;)
raise(SIGUSR1);
exit(0);
}
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/7569070083e6cd5b279bb5023da601aba3c06f3c.1597770847.git.christophe.leroy@csgroup.eu
save_general_regs() which does special handling when i == PT_SOFTE.
Rewrite it to minimise the specific part, especially the __put_user()
and associated error handling is the same so make it common.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
[mpe: Use a regular if rather than ternary operator]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/47a38df46cae5a5a88a558a64d71f75e9c4d9950.1594125164.git.christophe.leroy@csgroup.eu
Since commit ("1bd79336a426 powerpc: Fix various
syscall/signal/swapcontext bugs"), getting save_general_regs() called
without FULL_REGS() is very unlikely and generates a warning.
The 32-bit version of save_general_regs() doesn't take care of it
at all and copies all registers anyway since that commit.
Moreover, commit 965dd3ad30 ("powerpc/64/syscall: Remove
non-volatile GPR save optimisation") is another reason why it would
never happen.
So the same with 64-bit, don't worry about FULL_REGS() and copy
all registers all the time.
Signed-off-by: Christophe Leroy <christophe.leroy@csgroup.eu>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/173de3b659fa3a5f126a0eb170522cccd909950f.1594125164.git.christophe.leroy@csgroup.eu
Patch series "mm: consolidate definitions of page table accessors", v2.
The low level page table accessors (pXY_index(), pXY_offset()) are
duplicated across all architectures and sometimes more than once. For
instance, we have 31 definition of pgd_offset() for 25 supported
architectures.
Most of these definitions are actually identical and typically it boils
down to, e.g.
static inline unsigned long pmd_index(unsigned long address)
{
return (address >> PMD_SHIFT) & (PTRS_PER_PMD - 1);
}
static inline pmd_t *pmd_offset(pud_t *pud, unsigned long address)
{
return (pmd_t *)pud_page_vaddr(*pud) + pmd_index(address);
}
These definitions can be shared among 90% of the arches provided
XYZ_SHIFT, PTRS_PER_XYZ and xyz_page_vaddr() are defined.
For architectures that really need a custom version there is always
possibility to override the generic version with the usual ifdefs magic.
These patches introduce include/linux/pgtable.h that replaces
include/asm-generic/pgtable.h and add the definitions of the page table
accessors to the new header.
This patch (of 12):
The linux/mm.h header includes <asm/pgtable.h> to allow inlining of the
functions involving page table manipulations, e.g. pte_alloc() and
pmd_alloc(). So, there is no point to explicitly include <asm/pgtable.h>
in the files that include <linux/mm.h>.
The include statements in such cases are remove with a simple loop:
for f in $(git grep -l "include <linux/mm.h>") ; do
sed -i -e '/include <asm\/pgtable.h>/ d' $f
done
Signed-off-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Borislav Petkov <bp@alien8.de>
Cc: Brian Cain <bcain@codeaurora.org>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: "David S. Miller" <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Greentime Hu <green.hu@gmail.com>
Cc: Greg Ungerer <gerg@linux-m68k.org>
Cc: Guan Xuetao <gxt@pku.edu.cn>
Cc: Guo Ren <guoren@kernel.org>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Ingo Molnar <mingo@redhat.com>
Cc: Ley Foon Tan <ley.foon.tan@intel.com>
Cc: Mark Salter <msalter@redhat.com>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Max Filippov <jcmvbkbc@gmail.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Nick Hu <nickhu@andestech.com>
Cc: Paul Walmsley <paul.walmsley@sifive.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: Rich Felker <dalias@libc.org>
Cc: Russell King <linux@armlinux.org.uk>
Cc: Stafford Horne <shorne@gmail.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Vincent Chen <deanbo422@gmail.com>
Cc: Vineet Gupta <vgupta@synopsys.com>
Cc: Will Deacon <will@kernel.org>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20200514170327.31389-1-rppt@kernel.org
Link: http://lkml.kernel.org/r/20200514170327.31389-2-rppt@kernel.org
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
It's not very nice to zero trap for this, because then system calls no
longer have trap_is_syscall(regs) invariant, and we can't distinguish
between sc and scv system calls (in a later patch).
Take one last unused bit from the low bits of the pt_regs.trap word
for this instead. There is not a really good reason why it should be
in trap as opposed to another field, but trap has some concept of
flags and it exists. Ideally I think we would move trap to 2-byte
field and have 2 more bytes available independently.
Add a selftests case for this, which can be seen to fail if
trap_norestart() is changed to return false.
Signed-off-by: Nicholas Piggin <npiggin@gmail.com>
[mpe: Make them static inlines]
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200507121332.2233629-4-mpe@ellerman.id.au
After a treclaim, we expect to be in non-transactional state. If we
don't clear the current thread's MSR[TS] before we get preempted, then
tm_recheckpoint_new_task() will recheckpoint and we get rescheduled in
suspended transaction state.
When handling a signal caught in transactional state,
handle_rt_signal64() calls get_tm_stackpointer() that treclaims the
transaction using tm_reclaim_current() but without clearing the
thread's MSR[TS]. This can cause the TM Bad Thing exception below if
later we pagefault and get preempted trying to access the user's
sigframe, using __put_user(). Afterwards, when we are rescheduled back
into do_page_fault() (but now in suspended state since the thread's
MSR[TS] was not cleared), upon executing 'rfid' after completion of
the page fault handling, the exception is raised because a transition
from suspended to non-transactional state is invalid.
Unexpected TM Bad Thing exception at c00000000000de44 (msr 0x8000000302a03031) tm_scratch=800000010280b033
Oops: Unrecoverable exception, sig: 6 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
CPU: 25 PID: 15547 Comm: a.out Not tainted 5.4.0-rc2 #32
NIP: c00000000000de44 LR: c000000000034728 CTR: 0000000000000000
REGS: c00000003fe7bd70 TRAP: 0700 Not tainted (5.4.0-rc2)
MSR: 8000000302a03031 <SF,VEC,VSX,FP,ME,IR,DR,LE,TM[SE]> CR: 44000884 XER: 00000000
CFAR: c00000000000dda4 IRQMASK: 0
PACATMSCRATCH: 800000010280b033
GPR00: c000000000034728 c000000f65a17c80 c000000001662800 00007fffacf3fd78
GPR04: 0000000000001000 0000000000001000 0000000000000000 c000000f611f8af0
GPR08: 0000000000000000 0000000078006001 0000000000000000 000c000000000000
GPR12: c000000f611f84b0 c00000003ffcb200 0000000000000000 0000000000000000
GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR20: 0000000000000000 0000000000000000 0000000000000000 c000000f611f8140
GPR24: 0000000000000000 00007fffacf3fd68 c000000f65a17d90 c000000f611f7800
GPR28: c000000f65a17e90 c000000f65a17e90 c000000001685e18 00007fffacf3f000
NIP [c00000000000de44] fast_exception_return+0xf4/0x1b0
LR [c000000000034728] handle_rt_signal64+0x78/0xc50
Call Trace:
[c000000f65a17c80] [c000000000034710] handle_rt_signal64+0x60/0xc50 (unreliable)
[c000000f65a17d30] [c000000000023640] do_notify_resume+0x330/0x460
[c000000f65a17e20] [c00000000000dcc4] ret_from_except_lite+0x70/0x74
Instruction dump:
7c4ff120 e8410170 7c5a03a6 38400000 f8410060 e8010070 e8410080 e8610088
60000000 60000000 e8810090 e8210078 <4c000024> 48000000 e8610178 88ed0989
---[ end trace 93094aa44b442f87 ]---
The simplified sequence of events that triggers the above exception is:
... # userspace in NON-TRANSACTIONAL state
tbegin # userspace in TRANSACTIONAL state
signal delivery # kernelspace in SUSPENDED state
handle_rt_signal64()
get_tm_stackpointer()
treclaim # kernelspace in NON-TRANSACTIONAL state
__put_user()
page fault happens. We will never get back here because of the TM Bad Thing exception.
page fault handling kicks in and we voluntarily preempt ourselves
do_page_fault()
__schedule()
__switch_to(other_task)
our task is rescheduled and we recheckpoint because the thread's MSR[TS] was not cleared
__switch_to(our_task)
switch_to_tm()
tm_recheckpoint_new_task()
trechkpt # kernelspace in SUSPENDED state
The page fault handling resumes, but now we are in suspended transaction state
do_page_fault() completes
rfid <----- trying to get back where the page fault happened (we were non-transactional back then)
TM Bad Thing # illegal transition from suspended to non-transactional
This patch fixes that issue by clearing the current thread's MSR[TS]
just after treclaim in get_tm_stackpointer() so that we stay in
non-transactional state in case we are preempted. In order to make
treclaim and clearing the thread's MSR[TS] atomic from a preemption
perspective when CONFIG_PREEMPT is set, preempt_disable/enable() is
used. It's also necessary to save the previous value of the thread's
MSR before get_tm_stackpointer() is called so that it can be exposed
to the signal handler later in setup_tm_sigcontexts() to inform the
userspace MSR at the moment of the signal delivery.
Found with tm-signal-context-force-tm kernel selftest.
Fixes: 2b0a576d15 ("powerpc: Add new transactional memory state to the signal context")
Cc: stable@vger.kernel.org # v3.9
Signed-off-by: Gustavo Luiz Duarte <gustavold@linux.ibm.com>
Acked-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20200211033831.11165-1-gustavold@linux.ibm.com
On systems like P9 powernv where we have no TM (or P8 booted with
ppc_tm=off), userspace can construct a signal context which still has
the MSR TS bits set. The kernel tries to restore this context which
results in the following crash:
Unexpected TM Bad Thing exception at c0000000000022fc (msr 0x8000000102a03031) tm_scratch=800000020280f033
Oops: Unrecoverable exception, sig: 6 [#1]
LE PAGE_SIZE=64K MMU=Hash SMP NR_CPUS=2048 NUMA pSeries
Modules linked in:
CPU: 0 PID: 1636 Comm: sigfuz Not tainted 5.2.0-11043-g0a8ad0ffa4 #69
NIP: c0000000000022fc LR: 00007fffb2d67e48 CTR: 0000000000000000
REGS: c00000003fffbd70 TRAP: 0700 Not tainted (5.2.0-11045-g7142b497d8)
MSR: 8000000102a03031 <SF,VEC,VSX,FP,ME,IR,DR,LE,TM[E]> CR: 42004242 XER: 00000000
CFAR: c0000000000022e0 IRQMASK: 0
GPR00: 0000000000000072 00007fffb2b6e560 00007fffb2d87f00 0000000000000669
GPR04: 00007fffb2b6e728 0000000000000000 0000000000000000 00007fffb2b6f2a8
GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000
GPR12: 0000000000000000 00007fffb2b76900 0000000000000000 0000000000000000
GPR16: 00007fffb2370000 00007fffb2d84390 00007fffea3a15ac 000001000a250420
GPR20: 00007fffb2b6f260 0000000010001770 0000000000000000 0000000000000000
GPR24: 00007fffb2d843a0 00007fffea3a14a0 0000000000010000 0000000000800000
GPR28: 00007fffea3a14d8 00000000003d0f00 0000000000000000 00007fffb2b6e728
NIP [c0000000000022fc] rfi_flush_fallback+0x7c/0x80
LR [00007fffb2d67e48] 0x7fffb2d67e48
Call Trace:
Instruction dump:
e96a0220 e96a02a8 e96a0330 e96a03b8 394a0400 4200ffdc 7d2903a6 e92d0c00
e94d0c08 e96d0c10 e82d0c18 7db242a6 <4c000024> 7db243a6 7db142a6 f82d0c18
The problem is the signal code assumes TM is enabled when
CONFIG_PPC_TRANSACTIONAL_MEM is enabled. This may not be the case as
with P9 powernv or if `ppc_tm=off` is used on P8.
This means any local user can crash the system.
Fix the problem by returning a bad stack frame to the user if they try
to set the MSR TS bits with sigreturn() on systems where TM is not
supported.
Found with sigfuz kernel selftest on P9.
This fixes CVE-2019-13648.
Fixes: 2b0a576d15 ("powerpc: Add new transactional memory state to the signal context")
Cc: stable@vger.kernel.org # v3.9
Reported-by: Praveen Pandey <Praveen.Pandey@in.ibm.com>
Signed-off-by: Michael Neuling <mikey@neuling.org>
Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>
Link: https://lore.kernel.org/r/20190719050502.405-1-mikey@neuling.org
Pull force_sig() argument change from Eric Biederman:
"A source of error over the years has been that force_sig has taken a
task parameter when it is only safe to use force_sig with the current
task.
The force_sig function is built for delivering synchronous signals
such as SIGSEGV where the userspace application caused a synchronous
fault (such as a page fault) and the kernel responded with a signal.
Because the name force_sig does not make this clear, and because the
force_sig takes a task parameter the function force_sig has been
abused for sending other kinds of signals over the years. Slowly those
have been fixed when the oopses have been tracked down.
This set of changes fixes the remaining abusers of force_sig and
carefully rips out the task parameter from force_sig and friends
making this kind of error almost impossible in the future"
* 'siginfo-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace: (27 commits)
signal/x86: Move tsk inside of CONFIG_MEMORY_FAILURE in do_sigbus
signal: Remove the signal number and task parameters from force_sig_info
signal: Factor force_sig_info_to_task out of force_sig_info
signal: Generate the siginfo in force_sig
signal: Move the computation of force into send_signal and correct it.
signal: Properly set TRACE_SIGNAL_LOSE_INFO in __send_signal
signal: Remove the task parameter from force_sig_fault
signal: Use force_sig_fault_to_task for the two calls that don't deliver to current
signal: Explicitly call force_sig_fault on current
signal/unicore32: Remove tsk parameter from __do_user_fault
signal/arm: Remove tsk parameter from __do_user_fault
signal/arm: Remove tsk parameter from ptrace_break
signal/nds32: Remove tsk parameter from send_sigtrap
signal/riscv: Remove tsk parameter from do_trap
signal/sh: Remove tsk parameter from force_sig_info_fault
signal/um: Remove task parameter from send_sigtrap
signal/x86: Remove task parameter from send_sigtrap
signal: Remove task parameter from force_sig_mceerr
signal: Remove task parameter from force_sig
signal: Remove task parameter from force_sigsegv
...
Based on 1 normalized pattern(s):
this program is free software you can redistribute it and or modify
it under the terms of the gnu general public license as published by
the free software foundation either version 2 of the license or at
your option any later version
extracted by the scancode license scanner the SPDX license identifier
GPL-2.0-or-later
has been chosen to replace the boilerplate/reference in 3029 file(s).
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Reviewed-by: Allison Randal <allison@lohutok.net>
Cc: linux-spdx@vger.kernel.org
Link: https://lkml.kernel.org/r/20190527070032.746973796@linutronix.de
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
