Re: [PATCH v2] x86/ptrace: Stop setting TS_COMPAT in ptrace code

[Pedro Alves <palves@redhat.com>]

On 06/20/2016 08:37 PM, Andy Lutomirski wrote:
> On Mon, Jun 20, 2016 at 9:29 AM, Andy Lutomirski <luto@kernel.org> wrote:
>> Setting TS_COMPAT in ptrace is wrong: if we happen to do it during
>> syscall entry, then we'll confuse seccomp and audit.  (The former
>> isn't a security problem: seccomp is currently entirely insecure if a
>> malicious ptracer is attached.)  As a minimal fix, this patch adds a
>> new flag TS_I386_REGS_POKED that handles the ptrace special case.
>>
>> Cc: Pedro Alves <palves@redhat.com>
>> Cc: Oleg Nesterov <oleg@redhat.com>
>> Cc: Kees Cook <keescook@chromium.org>
>> Signed-off-by: Andy Lutomirski <luto@kernel.org>
> 
> In case you're interested, my draft followup (definitely not for x86/urgent) is:
> 
> https://git.kernel.org/cgit/linux/kernel/git/luto/linux.git/commit/?h=x86/vmap_stack&id=50d2f2a9fe1b
> 
> Pedro, this appears to pass ptrace-tests.  I need to try the 64-vs-32
> thing, but it's intended to fix it for real.

Awesome, thanks much for working on this!

Thanks,
Pedro Alves