Re: Kernel stack read with PTRACE_EVENT_EXIT and io_uring threads

Eric W. Biederman
2021-06-23T14:37:04Z

Michael Schmitz <schmitzmic@gmail.com> writes:

> 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.

Yes. It is looking like I can fix everything generically except for
faking user space registers for io_uring threads.

Eric