From: Ingo Molnar <mingo@elte.hu>
To: Andrew Lutomirski <luto@mit.edu>
Cc: x86@kernel.org, Thomas Gleixner <tglx@linutronix.de>,
linux-kernel@vger.kernel.org, Jesper Juhl <jj@chaosbits.net>,
Borislav Petkov <bp@alien8.de>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrew Morton <akpm@linux-foundation.org>,
Arjan van de Ven <arjan@infradead.org>,
Jan Beulich <JBeulich@novell.com>,
richard -rw- weinberger <richard.weinberger@gmail.com>,
Mikael Pettersson <mikpe@it.uu.se>
Subject: Re: [PATCH v2 08/10] x86-64: Emulate vsyscalls
Date: Mon, 30 May 2011 12:59:37 +0200 [thread overview]
Message-ID: <20110530105937.GB20133@elte.hu> (raw)
In-Reply-To: <BANLkTi=aX5un5ZPVD9u6NRJb-koFG7T=6w@mail.gmail.com>
* Andrew Lutomirski <luto@mit.edu> wrote:
> On Mon, May 30, 2011 at 3:46 AM, Ingo Molnar <mingo@elte.hu> wrote:
> >
> > * Andy Lutomirski <luto@MIT.EDU> wrote:
> >
> >> There's a fair amount of code in the vsyscall page, and who knows
> >> what will happen if an exploit jumps into the middle of it. Reduce
> >> the risk by replacing most of it with short magic incantations that
> >> are useless if entered in the middle. This change can be disabled
> >> by CONFIG_UNSAFE_VSYSCALLS (default y).
> >
> > btw., please flip the default or consider removing the option
> > altogether.
> >
> > We want to improve security and we want safe vsyscalls the default,
> > and it's no good if we make it too easy for users to keep the fire
> > door open all the time! :-)
>
> I'd advocate waiting until glibc 2.14 comes out with this change:
>
> http://sourceware.org/git/?p=glibc.git;a=commit;h=a8509ca540427502bd955f35296ff7b727c7a8a1
>
> I want to add a warning (ratelimited to an extremely low rate) in v3
> whenever any of the vsyscalls get used telling users that their legacy
> code is suffering a performance impact, but it seems like bad form to
> tell people to build glibc from git to avoid a regression.
But only statically built binaries would be impacted in practice,
right? The number of statically built binaries that heavily rely on
vsyscalls ought to be a very small set ...
Thanks,
Ingo
next prev parent reply other threads:[~2011-05-30 11:00 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-05-30 3:48 [PATCH v2 00/10] Remove syscall instructions at fixed addresses Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 01/10] x86-64: Fix alignment of jiffies variable Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 02/10] x86-64: Give vvars their own page Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 03/10] x86-64: Remove kernel.vsyscall64 sysctl Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 04/10] x86-64: Replace vsyscall gettimeofday fallback with int 0xcc Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 05/10] x86-64: Map the HPET NX Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 06/10] x86-64: Remove vsyscall number 3 (venosys) Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 07/10] x86-64: Fill unused parts of the vsyscall page with 0xcc Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 08/10] x86-64: Emulate vsyscalls Andy Lutomirski
2011-05-30 7:35 ` Borislav Petkov
2011-05-30 10:43 ` Andrew Lutomirski
2011-05-30 7:46 ` Ingo Molnar
2011-05-30 10:57 ` Andrew Lutomirski
2011-05-30 10:59 ` Ingo Molnar [this message]
2011-05-30 11:35 ` Andrew Lutomirski
2011-05-30 12:15 ` Ingo Molnar
2011-05-30 12:25 ` Andrew Lutomirski
2011-05-30 14:12 ` Ingo Molnar
2011-05-30 7:51 ` Jan Beulich
2011-05-30 8:07 ` Ingo Molnar
2011-05-31 2:29 ` Andrew Lutomirski
2011-05-30 3:48 ` [PATCH v2 09/10] x86-64: Randomize int 0xcc magic al values at boot Andy Lutomirski
2011-05-30 3:48 ` [PATCH v2 10/10] x86-64: Document some of entry_64.S Andy Lutomirski
2011-05-30 7:59 ` Borislav Petkov
2011-05-30 10:40 ` Andrew Lutomirski
2011-05-30 10:50 ` Ingo Molnar
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