linux-kernel - Re: [PATCH 1/1] mm_for_maps: simplify, use ptrace_may

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Date:	Thu, 25 Jun 2009 00:21:57 +1000 (EST)
From:	James Morris <jmorris@...ei.org>
To:	"Serge E. Hallyn" <serue@...ibm.com>
cc:	Oleg Nesterov <oleg@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Christoph Hellwig <hch@...radead.org>,
	Ingo Molnar <mingo@...e.hu>,
	Chris Wright <chrisw@...s-sol.org>,
	Roland McGrath <roland@...hat.com>,
	linux-kernel@...r.kernel.org, Al Viro <viro@...IV.linux.org.uk>,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH 1/1] mm_for_maps: simplify, use ptrace_may_access()

On Tue, 23 Jun 2009, Serge E. Hallyn wrote:

> Quoting Oleg Nesterov (oleg@...hat.com):
> > It would be nice to kill __ptrace_may_access(). It requires task_lock(),
> > but this lock is only needed to read mm->flags in the middle.
> > 
> > Convert mm_for_maps() to use ptrace_may_access(), this also simplifies
> > the code a little bit.
> > 
> > Also, we do not need to take ->mmap_sem in advance. In fact I think
> > mm_for_maps() should not play with ->mmap_sem at all, the caller should
> > take this lock.
> 
> Yeah I think that makes sense.
> 
> > With or without this patch, without ->cred_guard_mutex held we can race
> > with exec() and get the new ->mm but check old creds.
> > 
> > Signed-off-by: Oleg Nesterov <oleg@...hat.com>
> 
> reasoning on the security check also makes sense.
> 
> Reviewed-by: Serge Hallyn <serue@...ibm.com>


Applied to
git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/security-testing-2.6#next


-- 
James Morris
<jmorris@...ei.org>
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