linux-kernel - Re: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE

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:	Tue, 31 May 2011 20:34:48 +0200
From:	Andi Kleen <andi@...stfloor.org>
To:	Andy Lutomirski <luto@....EDU>
Cc:	Ingo Molnar <mingo@...e.hu>, x86@...nel.org,
	Thomas Gleixner <tglx@...utronix.de>,
	linux-kernel@...r.kernel.org, Jesper Juhl <jj@...osbits.net>,
	Borislav Petkov <bp@...en8.de>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	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>
Subject: Re: [PATCH v4 10/10] x86-64: Add CONFIG_UNSAFE_VSYSCALLS to feature-removal-schedule

> +What:	CONFIG_UNSAFE_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
> +	make the time() function slower on glibc versions 2.13 and below.

I disagree with this description (and the whole idea really)

First it's time+gettimeofday+vgetcu, not just time.

A more accurate description is 

"will make all x86-64 Linux programs written to the original pre
vDSO syscall ABI significantly slower"

And the assumption that all world is using glibc is still as bad
as it was on the first po.st

And it's still a bad idea. Especially since there's a much better
alternative anyways for the "security problem" which has none of 
these drawbacks.

-Andi
--
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/