linux-kernel - Re: [PATCH] vfs: fix IMA lockdep circular locking dependency

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Message-ID: <CA+55aFxiCksfNdRrm+O-eJSY=qTUQEsZtFbi8wj2_kj1XeNHnQ@mail.gmail.com>
Date:	Wed, 30 May 2012 13:28:09 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Eric Paris <eparis@...isplace.org>,
	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Mimi Zohar <zohar@...ibm.com>,
	linux-security-module@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] vfs: fix IMA lockdep circular locking dependency

On Wed, May 30, 2012 at 1:24 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
> On Wed, May 30, 2012 at 03:42:47PM -0400, Eric Paris wrote:
>> security_file_mmap() would pretty much only be used in do_mmap_pgoff()
>> (or validate_mmap_request)
>
> Callers, actually - the whole point is to lift it out of under ->mmap_sem.
> The tricky part is reqprot vs. prot mess.

See how I solved reqprot vs prot in my suggested original patch. You
have it somewhere in your inbox, I know, because you called me out on
the fact that my original email forgot to attach it ;)

It actually cleaned things up, and made the calling conventions
simpler. Just always pass in "reqprot", and have the security layer do
the trivial "calculate final prot".

Anyway, my original patch worked, but it (incorrectly) optimized away
the call to the security layer if file was NULL. But that's just a
matter of removing that check.

                  Linus
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