From mboxrd@z Thu Jan  1 00:00:00 1970
From: Michael Schmitz <schmitzmic@gmail.com>
Subject: Re: Kernel stack read with PTRACE_EVENT_EXIT and io_uring threads
Date: Wed, 23 Jun 2021 17:26:22 +1200
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To: "Eric W. Biederman" <ebiederm@xmission.com>, Linus Torvalds <torvalds@linux-foundation.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>, linux-arch <linux-arch@vger.kernel.org>, Jens Axboe <axboe@kernel.dk>, Oleg Nesterov <oleg@redhat.com>, Linux Kernel Mailing List <linux-kernel@vger.kernel.org>, Richard Henderson <rth@twiddle.net>, Ivan Kokshaysky <ink@jurassic.park.msu.ru>, Matt Turner <mattst88@gmail.com>, alpha <linux-alpha@vger.kernel.org>, Geert Uytterhoeven <geert@linux-m68k.org>, linux-m68k <linux-m68k@lists.linux-m68k.org>, Arnd Bergmann <arnd@kernel.org>, Tejun Heo <tj@kernel.org>, Kees Cook <keescook@chromium.org>, Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>, John Paul Adrian Glaubitz <glaubitz@physik.fu-berlin.de>

Hi Eric,

Am 23.06.2021 um 09:48 schrieb Michael Schmitz:
>>
>> The challenging ones are /proc/pid/syscall and seccomp which want to see
>> all of the system call arguments.  I think every architecture always
>> saves the system call arguments unconditionally, so those cases are
>> probably not as interesting.  But they certain look like they could be
>> trouble.
>
> Seccomp hasn't yet been implemented on m68k, though I'm working on that
> with Adrian. The sole secure_computing() call will happen in
> syscall_trace_enter(), so all system call arguments have been saved on
> the stack.
>
> Haven't looked at /proc/pid/syscall yet ...

Not supported at present (no HAVE_ARCH_TRACEHOOK for m68k). And the 
syscall_get_arguments I wrote for seccomp support only copies the first 
five data registers, which are always saved.

Cheers,

	Michael