linux-kernel - Re: [PATCH v2] x86/ptrace: Stop setting TS

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Message-ID: <da123119-4336-90fd-6cb0-6d3e72843d42@redhat.com>
Date:	Mon, 20 Jun 2016 23:21:42 +0100
From:	Pedro Alves <palves@...hat.com>
To:	Andy Lutomirski <luto@...capital.net>,
	Andy Lutomirski <luto@...nel.org>
Cc:	X86 ML <x86@...nel.org>,
	"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
	Kees Cook <keescook@...omium.org>,
	Borislav Petkov <bp@...en8.de>, Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH v2] x86/ptrace: Stop setting TS_COMPAT in ptrace code

On 06/20/2016 08:37 PM, Andy Lutomirski wrote:
> On Mon, Jun 20, 2016 at 9:29 AM, Andy Lutomirski <luto@...nel.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@...hat.com>
>> Cc: Oleg Nesterov <oleg@...hat.com>
>> Cc: Kees Cook <keescook@...omium.org>
>> Signed-off-by: Andy Lutomirski <luto@...nel.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