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Date: Mon, 16 Jan 2012 20:06:18 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Andy Lutomirski <luto@amacapital.net>
Cc: Casey Schaufler <casey@schaufler-ca.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
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Subject: Re: [PATCH 4/4] Allow unprivileged chroot when safe
Message-ID: <20120116200618.GN23916@ZenIV.linux.org.uk>
References: <cover.1326673414.git.luto@amacapital.net>
 <c4c1a0e710a50e48221aa28d2b60b486ab686369.1326673414.git.luto@amacapital.net>
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On Sun, Jan 15, 2012 at 04:37:21PM -0800, Andy Lutomirski wrote:

> +	is_chrooted = (fs->root.mnt->mnt_mountpoint !=
> +		       fs->root.mnt->mnt_parent->mnt_root ||
> +		       fs->root.dentry != fs->root.mnt->mnt_root);

Folks, is it _that_ hard to at least try to compile your patches?  Hint:
this one will *not*.  That sad detail aside, this test would have been
a pile of garbage even on the kernels that used to have mnt_mountpoint
in struct vfsmount.  What *are* you trying to test here?  The last part
at least does make some sense - it's "process root happens to be the
root of some vfsmount".  The first part, though, makes no sense whatsoever;
it's "... and that vfsmount is mounted on top of root of some other
vfsmount".

Grr...  NAKed, with extreme prejudice.