Re: [Security] [PATCH] proc: avoid information leaks to non-privileged processes [LWN.net]

From:		Linus Torvalds <torvalds-AT-linux-foundation.org>
To:		"Eric W. Biederman" <ebiederm-AT-xmission.com>
Subject:		Re: [Security] [PATCH] proc: avoid information leaks to non-privileged processes
Date:		Mon, 4 May 2009 15:24:15 -0700 (PDT)
Message-ID:		<alpine.LFD.2.01.0905041514350.4983@localhost.localdomain>
Cc:		Arjan van de Ven <arjan-AT-infradead.org>, Jake Edge <jake-AT-lwn.net>, security-AT-kernel.org, Linux Kernel Mailing List <linux-kernel-AT-vger.kernel.org>, James Morris <jmorris-AT-namei.org>, linux-security-module-AT-vger.kernel.org, Eric Paris <eparis-AT-redhat.com>, Alan Cox <alan-AT-lxorguk.ukuu.org.uk>, Roland McGrath <roland-AT-redhat.com>, mingo-AT-redhat.com, Andrew Morton <akpm-AT-linux-foundation.org>, Greg KH <greg-AT-kroah.com>, Matt Mackall <mpm-AT-selenic.com>
Archive-link:		Article, Thread

On Mon, 4 May 2009, Eric W. Biederman wrote:

> Arjan van de Ven <arjan@infradead.org> writes:
> 
> > On Mon, 4 May 2009 12:00:12 -0700 (PDT)
> > Linus Torvalds <torvalds@linux-foundation.org> wrote:
> >
> >> 
> >> 
> >> On Mon, 4 May 2009, Jake Edge wrote:
> >> >
> >> > This is essentially v2 of "[PATCH] proc: avoid leaking eip, esp, or
> >> > wchan to non-privileged processes", adding some of Eric Biederman's
> >> > suggestions as well as the start_stack change (only give out that
> >> > address if the process is ptrace()-able).  This has been tested
> >> > with ps and top without any ill effects being seen.
> >> 
> >> Looks sane to me. Anybody objects?
> >> 
> >
> > Acked-by: Arjan van de Ven <arjan@linux.intel.com>
> 
> Looks sane here.
> 
> Acked-by: "Eric W. Biederman" <ebiederm@xmission.com>

Ok, applied.

Also, does anybody have any commentary or opinion on the patch by Matt 
Mackall to use stronger random numbers than "get_random_int()". I wonder 
what the performance impact of that is - "get_random_int()" is very cheap 
by design, and many users may consider calling "get_random_bytes()" to be 
overkill and a potential performance issue.

Quite frankly, the way "get_random_bytes()" works now (it does a _full_ 
sha thing every time), I think it's insane overkill. But I do have to 
admit that our current "get_random_int()" is insane _underkill_.

I'd like to improve the latter without going to quie the extreme that 
matt's patch did.

		Linus
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