linux-kernel - Re: [PATCH 3.5 2/2] seccomp: Future-proof against silly tracers

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]

Date:	Thu, 2 Aug 2012 09:54:43 -0700
From:	Andy Lutomirski <luto@...capital.net>
To:	Will Drewry <wad@...omium.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Kees Cook <keescook@...omium.org>
Subject: Re: [PATCH 3.5 2/2] seccomp: Future-proof against silly tracers

On Thu, Aug 2, 2012 at 7:32 AM, Will Drewry <wad@...omium.org> wrote:
> On Thu, Jul 26, 2012 at 10:41 AM, Andy Lutomirski <luto@...capital.net> wrote:
>> On Tue, Jul 17, 2012 at 4:19 PM, Andy Lutomirski <luto@...capital.net> wrote:
>>> Currently, if a tracer changes a syscall nr to __NR_future_enosys,
>>> behavior will differ between kernels that know about
>>> __NR_future_enosys (and return -ENOSYS) and older kernels (which
>>> return the value from pt_regs).  This is silly; we should just
>>> return -ENOSYS.
>>>
>>> This is unlikely to ever happen on x86 because the return value in
>>> pt_regs starts out as -ENOSYS, but a silly tracer can change that.
>>>
>>> Signed-off-by: Andy Lutomirski <luto@...capital.net>
>>> Cc: Will Drewry <wad@...omium.org>
>>> ---
>>>  arch/x86/include/asm/syscall.h |   11 +++++++++++
>>>  kernel/seccomp.c               |   15 +++++++++++++++
>>>  2 files changed, 26 insertions(+), 0 deletions(-)
>>
>> Will, can you pick this, or some version of it, up in your
>> seccomp-for-ARM tree or wherever your development is?
>
> I'm still not sure about this change though the end result is nice.
> Regardless, I'll explore it when I can -- my family has just increased
> in size, so I'm going to be a bit delayed!

I don't think there's any particular rush here.  It's a very minor ABI
change, but I had to write code to explicitly look for it to detect
any difference at all.

--Andy


>
> cheers!
> will



-- 
Andy Lutomirski
AMA Capital Management, LLC
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@...r.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/