linux-kernel - Re: [AppArmor 01/41] Pass struct vfsmount to the inode

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Message-Id: <200705291907.29547.agruen@suse.de>
Date:	Tue, 29 May 2007 19:07:29 +0200
From:	Andreas Gruenbacher <agruen@...e.de>
To:	Tetsuo Handa <from-lsm@...ove.sakura.ne.jp>
Cc:	crispin@...ell.com, cliffe@...et.net.au, casey@...aufler-ca.com,
	mrmacman_g4@....com, linux-security-module@...r.kernel.org,
	linux-kernel@...r.kernel.org
Subject: Re: [AppArmor 01/41] Pass struct vfsmount to the inode_create LSMhook

On Tuesday 29 May 2007 12:46, Tetsuo Handa wrote:
> But, from the pathname-based access control's point of view,
> bind mount interferes severely with pathname-based access control
> because it is impossible to determine which pathname was requested.

Wrong. It is very well possible to determine the path of a particular dentry 
(+ vfsmount) with bind mounts.

> Although both pathnames point to the same object, TOMOYO focuses on the
> PROCEDURE FOR REACHING AN OBJECT and being able to know the procedure is
> very important.

This doesn't make sense, either. With the following sequence of syscalls of 
processes A and B (both of them in the namespace root),

	A:				B:
	mkdir("/tmp/a")
	chdir("/tmp/a")
					rename("/tmp/a", "/tmp/b")
	creat("f")

the path being checked for the creat call must be "/tmp/b/f", even though 
process A never explicitly used "b". If that's not what TOMOYO is doing, then 
that's badly broken.

Andreas
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