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Date: Thu, 23 Feb 2012 01:08:12 +0100
Subject: Re: [PATCH v10 05/11] seccomp: add system call filtering using BPF
From: "Indan Zupancic" <indan@nul.nu>
To: "Andrew Lutomirski" <luto@mit.edu>
Cc: "Will Drewry" <wad@chromium.org>,
        "Ben Hutchings" <bhutchings@solarflare.com>,
        linux-kernel@vger.kernel.org, linux-arch@vger.kernel.org,
        linux-doc@vger.kernel.org, kernel-hardening@lists.openwall.com,
        netdev@vger.kernel.org, x86@kernel.org, arnd@arndb.de,
        davem@davemloft.net, hpa@zytor.com, mingo@redhat.com, oleg@redhat.com,
        peterz@infradead.org, rdunlap@xenotime.net, mcgrathr@chromium.org,
        tglx@linutronix.de, eparis@redhat.com, serge.hallyn@canonical.com,
        djm@mindrot.org, scarybeasts@gmail.com, pmoore@redhat.com,
        akpm@linux-foundation.org, corbet@lwn.net, eric.dumazet@gmail.com,
        markus@chromium.org, keescook@chromium.org
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On Thu, February 23, 2012 00:51, Andrew Lutomirski wrote:
> On Wed, Feb 22, 2012 at 3:46 PM, Indan Zupancic <indan@nul.nu> wrote:
>> On Wed, February 22, 2012 20:47, Will Drewry wrote:
>>> On Wed, Feb 22, 2012 at 8:23 AM, Ben Hutchings
>>>> I would have thought the way to make sure the architecture is always
>>>> checked is to pack it together with the syscall number.
>>
>> I missed that suggestion, putting the syscall number and arch in one
>> data field would indeed make it harder to not check the arch.
>
> Is there enough room?  On x86-64 at least, rax could conceivably be
> extended to 64 bits some day.  Bit 30 is already spoken for by x32.

No, there isn't.


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