Re: [PATCH] x86-64, vsyscalls: Rename UNSAFE_VSYSCALLS to COMPAT_VSYSCALLS
From: Andrew Lutomirski
Date: Mon Jun 06 2011 - 08:34:19 EST
On Mon, Jun 6, 2011 at 8:19 AM, Ted Ts'o <tytso@xxxxxxx> wrote:
> On Mon, Jun 06, 2011 at 12:24:19PM +0200, Ingo Molnar wrote:
>> -What: CONFIG_UNSAFE_VSYSCALLS (x86_64)
>> +What: CONFIG_COMPAT_VSYSCALLS (x86_64)
>> When: When glibc 2.14 or newer is ubitquitous. Perhaps mid-2012.
>> -Why: Having user-executable code at a fixed address is a security problem.
>> - Turning off CONFIG_UNSAFE_VSYSCALLS mostly removes the risk but will
>> +Why: Having user-executable syscall invoking code at a fixed addresses makes
>> + it easier for attackers to exploit security holes.
>> + Turning off CONFIG_COMPAT_VSYSCALLS mostly removes the risk but will
>> make the time() function slower on glibc versions 2.13 and below.
>> Who: Andy Lutomirski <luto@xxxxxxx>
> I'd suggest 2013 or 2014, at least. People using Ubuntu LTS and RHEL
> 6 are stuck back at glibc 2.11, and many of those users do like being
> able to upgrade to newer kernels. And there are probably are a large
> number of static binaries around.
> Maybe in 2012 or so we change the to be 'no' (and I'd suggest adding a
> comment in the feature-removal-schedule.txt file that this will also
> break static binaries).
It doesn't actually break them; it just slows them down. But I'm very
particular about the date.
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