linux-kernel - Re: [PATCH] restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace pid

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Date:	Sat, 5 Jan 2008 09:48:59 +0000
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, Matt Mackall <mpm@...enic.com>,
	Dave Hansen <haveblue@...ibm.com>
Subject: Re: [PATCH] restrict reading from /proc/<pid>/maps to those who share ->mm or can ptrace pid

On Sat, Jan 05, 2008 at 01:31:09AM -0800, Andrew Morton wrote:
> On Wed, 2 Jan 2008 14:09:57 +0000 Al Viro <viro@...IV.linux.org.uk> wrote:
> 
> > 	Contents of /proc/*/maps is sensitive and may become sensitive
> > after open() (e.g. if target originally shares our ->mm and later
> > does exec on suid-root binary).
> 
> um, which contents?

Information about the addresses where libraries, etc. got mapped, to
start with - if you have that randomized, you don't want it seen
by attacker who tries to escalate...
 
> > 	Check at read() (actually, ->start() of iterator) time that
> > mm_struct we'd grabbed and locked is
> > 	* still the ->mm of target
> > 	* equal to reader's ->mm or the target is ptracable by reader.
> > 
> 
> Specifically, do /proc/pid/smaps and the maps4 goodies in -mm need similar
> treatment?

They differ only in ->show(), so this patch takes care of them as well...
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