linux-kernel - Re: [PATCH] x86-64, vsyscalls: Rename UNSAFE_VSYSCALLS to COMPAT

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Date:	Mon, 6 Jun 2011 08:33:49 -0400
From:	Andrew Lutomirski <luto@....edu>
To:	"Ted Ts'o" <tytso@....edu>, Ingo Molnar <mingo@...e.hu>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	Andy Lutomirski <luto@....edu>, x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Jesper Juhl <jj@...osbits.net>,
	Borislav Petkov <bp@...en8.de>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Arjan van de Ven <arjan@...radead.org>,
	Jan Beulich <JBeulich@...ell.com>,
	richard -rw- weinberger <richard.weinberger@...il.com>,
	Mikael Pettersson <mikpe@...uu.se>,
	Andi Kleen <andi@...stfloor.org>,
	Brian Gerst <brgerst@...il.com>,
	Louis Rilling <Louis.Rilling@...labs.com>,
	Valdis.Kletnieks@...edu, pageexec@...email.hu
Subject: Re: [PATCH] x86-64, vsyscalls: Rename UNSAFE_VSYSCALLS to COMPAT_VSYSCALLS

On Mon, Jun 6, 2011 at 8:19 AM, Ted Ts'o <tytso@....edu> 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@....edu>
>
> 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.

--Andy
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