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

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <CALCETrU3B1fiEQTS8d=w+outfWu3aMjT67LGtStCxYZgvfXomg@mail.gmail.com>
Date:	Mon, 20 Jun 2016 12:37:44 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	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>,
	Pedro Alves <palves@...hat.com>
Subject: Re: [PATCH v2] x86/ptrace: Stop setting TS_COMPAT in ptrace code

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.  It may not work for in
really exotic cases like gdb under UML, but I don't know if we can fix
that even in principle.

Some day we should expose syscall arch directly via ptrace.

--Andy