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From: Andrew Lutomirski <luto@mit.edu>
Date: Wed, 22 Feb 2012 15:51:40 -0800
Message-ID: <CAObL_7H14aPuaMjSyoaxWxWzP_=9D1yDiO0EKk9LPi_8-GYeyw@mail.gmail.com>
Subject: Re: [PATCH v10 05/11] seccomp: add system call filtering using BPF
To: Indan Zupancic <indan@nul.nu>
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,
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        tglx@linutronix.de, eparis@redhat.com, serge.hallyn@canonical.com,
        djm@mindrot.org, scarybeasts@gmail.com, pmoore@redhat.com,
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        markus@chromium.org, keescook@chromium.org
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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.

--Andy
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