linux-stable/arch/x86/entry
Eric W. Biederman fcb116bc43 signal: Replace force_fatal_sig with force_exit_sig when in doubt
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>
2021-11-19 09:15:58 -06:00
..
syscalls futex,x86: Wire up sys_futex_waitv() 2021-10-07 13:51:11 +02:00
vdso x86/build/vdso: fix missing FORCE for *.so build rule 2021-09-03 08:17:19 +09:00
vsyscall signal: Replace force_fatal_sig with force_exit_sig when in doubt 2021-11-19 09:15:58 -06:00
calling.h x86/entry: Split PUSH_AND_CLEAR_REGS into two submacros 2021-05-12 10:49:15 +02:00
common.c X86 entry code related updates: 2021-06-29 12:44:51 -07:00
entry_32.S - turn the stack canary into a normal __percpu variable on 32-bit which 2021-04-27 17:45:09 -07:00
entry_64.S X86 entry code related updates: 2021-06-29 12:44:51 -07:00
entry_64_compat.S x86/sev-es: Introduce ip_within_syscall_gap() helper 2021-03-08 14:22:17 +01:00
Makefile x86/syscalls: Don't adjust CFLAGS for syscall tables 2021-05-25 16:59:23 +02:00
syscall_32.c x86/syscalls: Stop filling syscall arrays with *_sys_ni_syscall 2021-05-20 15:03:59 +02:00
syscall_64.c x86/syscalls: Stop filling syscall arrays with *_sys_ni_syscall 2021-05-20 15:03:59 +02:00
syscall_x32.c x86/syscalls: Stop filling syscall arrays with *_sys_ni_syscall 2021-05-20 15:03:59 +02:00
thunk_32.S x86/entry: Remove unused THUNKs 2020-08-26 12:41:54 +02:00
thunk_64.S x86/entry: Remove put_ret_addr_in_rdi THUNK macro argument 2021-01-19 11:06:14 +01:00