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Subject: Re: Kernel stack read with PTRACE_EVENT_EXIT and io_uring threads
To:     "Eric W. Biederman" <ebiederm@xmission.com>,
        Linus Torvalds <torvalds@linux-foundation.org>
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Cc:     Al Viro <viro@zeniv.linux.org.uk>,
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From:   Michael Schmitz <schmitzmic@gmail.com>
Message-ID: <55bdad37-187b-e1f5-a359-c5206b20ff4d@gmail.com>
Date:   Wed, 23 Jun 2021 17:26:22 +1200
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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