linux-arm-kernel.lists.infradead.org archive mirror
 help / color / mirror / Atom feed
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
-------------- next part --------------
A non-text attachment was scrubbed...
Name: signature.asc
Type: application/pgp-signature
Size: 801 bytes
Desc: not available
URL: <http://lists.infradead.org/pipermail/linux-arm-kernel/attachments/20180314/f540b10f/attachment.sig>

  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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to=20180313235850.GA18373@altlinux.org \
    --to=ldv@altlinux.org \
    --cc=linux-arm-kernel@lists.infradead.org \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).