linux-kernel - Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map

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Message-ID: <20110831090612.GA3253@albatros>
Date:	Wed, 31 Aug 2011 13:06:12 +0400
From:	Vasiliy Kulikov <segoon@...nwall.com>
To:	Cyrill Gorcunov <gorcunov@...nvz.org>
Cc:	containers@...ts.osdl.org, linux-kernel@...r.kernel.org,
	linux-fsdevel@...r.kernel.org, Nathan Lynch <ntl@...ox.com>,
	Oren Laadan <orenl@...columbia.edu>,
	Daniel Lezcano <dlezcano@...ibm.com>,
	Glauber Costa <glommer@...allels.com>,
	James Bottomley <jbottomley@...allels.com>,
	Tejun Heo <tj@...nel.org>,
	"Kirill A. Shutemov" <kirill@...temov.name>,
	Alexey Dobriyan <adobriyan@...il.com>,
	Al Viro <viro@...IV.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Pavel Emelyanov <xemul@...allels.com>
Subject: Re: [patch 2/2] fs, proc: Introduce the /proc/<pid>/map_files/
 directory v6

Hi,

On Wed, Aug 31, 2011 at 11:58 +0400, Cyrill Gorcunov wrote:
> From: Pavel Emelyanov <xemul@...allels.com>
> 
> This one behaves similarly to the /proc/<pid>/fd/ one - it contains symlinks
> one for each mapping with file, the name of a symlink is "vma->vm_start-vma->vm_end",
> the target is the file. Opening a symlink results in a file that point exactly
> to the same inode as them vma's one.

I'm late noting it before the RFCv6 :)  Besides checking
ptrace_may_access() on ->lookup and ->readdir you also should define
->stat, otherwise you can bypass ptrace checks if there is a
corresponding dentry in the cache.  The same issue existed in fd* handlers:

http://www.openwall.com/lists/kernel-hardening/2011/08/29/1

Thanks,

-- 
Vasiliy Kulikov
http://www.openwall.com - bringing security into open computing environments
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