From: ldv@altlinux.org (Dmitry V. Levin)
To: linux-arm-kernel@lists.infradead.org
Subject: ARM: Call syscall_trace_exit even when system call skipped
Date: Wed, 14 Mar 2018 02:58:50 +0300 [thread overview]
Message-ID: <20180313235850.GA18373@altlinux.org> (raw)
In-Reply-To: <20180203152112.2449-1-T.E.Baldwin99@members.leeds.ac.uk>
Hi Kees,
As you probably know, ptracing of processes affected by SECCOMP_RET_TRAP
is broken on ARM since your commit v3.7-rc1-11-gad75b51459ae.
Could you review the proposed fix, please?
P.S. There is a test for this kernel bug in strace test suite,
you might find it useful:
https://github.com/strace/strace/compare/ldv/SECCOMP_RET_TRAP
On Sat, Feb 03, 2018 at 03:21:12PM +0000, Timothy E Baldwin wrote:
> On at least x86 and ARM64, and as documented in the ptrace man page
> a skipped system call will still cause a syscall exit ptrace stop.
>
> Previous to this commit 32-bit ARM did not, resulting in strace
> being confused when seccomp skips system calls.
>
> This change also impacts programs that use ptrace to skip system calls.
>
> Fixes: ad75b51459ae ("ARM: 7579/1: arch/allow a scno of -1 to not cause a SIGILL")
> Signed-off-by: Timothy E Baldwin <T.E.Baldwin99@members.leeds.ac.uk>
> ---
> arch/arm/kernel/entry-common.S | 9 ++++-----
> 1 file changed, 4 insertions(+), 5 deletions(-)
>
> diff --git a/arch/arm/kernel/entry-common.S b/arch/arm/kernel/entry-common.S
> index 99c908226065..88a65157307d 100644
> --- a/arch/arm/kernel/entry-common.S
> +++ b/arch/arm/kernel/entry-common.S
> @@ -288,16 +288,15 @@ __sys_trace:
> cmp scno, #-1 @ skip the syscall?
> bne 2b
> add sp, sp, #S_OFF @ restore stack
> - b ret_slow_syscall
>
> -__sys_trace_return:
> - str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
> +__sys_trace_return_nosave:
> + enable_irq_notrace
> mov r0, sp
> bl syscall_trace_exit
> b ret_slow_syscall
>
> -__sys_trace_return_nosave:
> - enable_irq_notrace
> +__sys_trace_return:
> + str r0, [sp, #S_R0 + S_OFF]! @ save returned r0
> mov r0, sp
> bl syscall_trace_exit
> b ret_slow_syscall
--
ldv
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next prev parent reply other threads:[~2018-03-13 23:58 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-03 15:21 [PATCH] ARM: Call syscall_trace_exit even when system call skipped Timothy E Baldwin
2018-03-13 23:58 ` Dmitry V. Levin [this message]
2018-03-15 0:44 ` Kees Cook
2018-03-15 10:38 ` T.E.Baldwin99 at members.leeds.ac.uk
2018-03-15 20:14 ` Kees Cook
2018-09-29 23:03 ` Eugene Syromyatnikov
2018-10-08 7:11 ` Eugene Syromyatnikov
2018-10-08 9:58 ` Vladimir Murzin
2018-10-08 11:00 ` Eugene Syromyatnikov
2018-10-08 18:08 ` Kees Cook
2018-10-08 18:13 ` Russell King - ARM Linux
2018-10-08 18:33 ` Eugene Syromyatnikov
2018-10-08 18:26 ` Eugene Syromyatnikov
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