linux-kernel - Re: [kernel-hardening] [PATCH 1/2] fs: add link restrictions

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Message-ID: <CAGXu5j+8mY1Rr5Uw5BYAhwhKVV_CvT5yu8YDJ1RqOta2NbVfQQ@mail.gmail.com>
Date:	Mon, 6 Aug 2012 16:59:22 -0700
From:	Kees Cook <keescook@...omium.org>
To:	"Eric W. Biederman" <ebiederm@...ssion.com>
Cc:	James Morris <jmorris@...ei.org>,
	kernel-hardening@...ts.openwall.com,
	Al Viro <viro@...iv.linux.org.uk>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Eric Paris <eparis@...hat.com>,
	Matthew Wilcox <matthew@....cx>,
	Doug Ledford <dledford@...hat.com>,
	Joe Korty <joe.korty@...r.com>, Ingo Molnar <mingo@...e.hu>,
	David Howells <dhowells@...hat.com>,
	James Morris <james.l.morris@...cle.com>,
	linux-doc@...r.kernel.org, Dan Rosenberg <drosenberg@...curity.com>
Subject: Re: [kernel-hardening] [PATCH 1/2] fs: add link restrictions

[resend: MUA tricked me into sending HTML email...]

On Mon, Aug 6, 2012 at 4:55 PM, Eric W. Biederman <ebiederm@...ssion.com> wrote:
>
> Kees Cook <keescook@...omium.org> writes:
>
> > On Thu, Aug 2, 2012 at 9:26 PM, James Morris <jmorris@...ei.org> wrote:
> >> On Wed, 25 Jul 2012, Kees Cook wrote:
> >>
> >>> This adds symlink and hardlink restrictions to the Linux VFS.
> >>
> >> Is Al happy with this now?
> >
> > Looks like it; thanks for checking. It's in mainline now:
> >
> > http://git.kernel.org/?p=linux/kernel/git/torvalds/linux.git;a=commitdiff;h=800179c9b8a1e796e441674776d11cd4c05d61d7
>
> So there was one trivial little issue with your patch.  You were
> directly comparing kuids instead of using uid_eq.  This only practically
> matters when user namespaces are enabled which is currently impossible
> in 3.6-rc1 :(
>
> I have added the following fixup patch to my for-next branch of
> user-namespace.git
>
> From: "Eric W. Biederman" <ebiederm@...ssion.com>
> Date: Fri, 3 Aug 2012 09:38:08 -0700
> Subject: [PATCH] userns:  Fix link restrictions to use uid_eq
>
> Signed-off-by: "Eric W. Biederman" <ebiederm@...ssion.com>

Ah-ha! Thanks for fixing this.

Acked-by: Kees Cook <keescook@...omium.org>

-Kees

--
Kees Cook
Chrome OS Security
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