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

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Date:	Tue, 15 May 2012 18:53:33 -0700
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	Mimi Zohar <zohar@...ux.vnet.ibm.com>,
	Eric Paris <eparis@...isplace.org>,
	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 Tue, May 15, 2012 at 5:45 PM, Linus Torvalds
<torvalds@...ux-foundation.org> wrote:
>
> Oops. Err.. I meant to do that. Right. To check that you're awake.
>
> Here.

Btw, a few notes:

 - this adds the new security_mmap_file() calls to the same places
that Mimi added the ima_file_mmap() call.

   HOWEVER. There are other callers that call do_mmap[_pgoff].
Notably, do_shmat(). IMA probably doesn't care, but other security
models might - even if the file in question there will be one just
allocated by the shm layer.

   So it does change semantics a bit, in that not only does the
->mmap_file() function no longer get called when 'file' is NULL, it
also doesn't get called with a couple of special files (the other one
I noticed was the i810 driver doing it's do_mmap() dance)

 - the fact that we don't call the security function for a NULL-file
mmap() is actually consistent with what do_brk() has always done (it
used to do "addr_only=1", now it obviously does just
security_mmap_addr() instead). So that part looks sane, and no
security model can possibly care.

 - I booted the patch. Not that I actually *tested* it any real way,
but at least it boots and doesn't seem to break anything obvious.

Hmm?

                  Linus
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