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

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Message-ID: <20120530213638.GZ11775@ZenIV.linux.org.uk>
Date:	Wed, 30 May 2012 22:36:38 +0100
From:	Al Viro <viro@...IV.linux.org.uk>
To:	Linus Torvalds <torvalds@...ux-foundation.org>
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 02:04:23PM -0700, Linus Torvalds wrote:
> Generating 'prot' from 'reqprot' really *should* be as simple as what
> I did in my patch. The fact that some places f*ck it up is their
> problem - see for example mprotect (I think) that didn't take
> MNT_NOEXEC into account.
> 
> Don't try to emulate those broken semantics. Just fix them.

Actually, it's better than I thought, but not as simple as you say.
I've misread what's going on in !file case; mea culpa, they are
actually acting the same way there.

The only difference is that for file-backed ones !MMU wants
VM_MAYEXEC in that file's bdi flags (BDI_CAP_EXEC_MAP).  And
that actually sounds reasonable in !MMU case.

Anyway, I've dumped the variant I've got into vfs.git@...urity_file_mmap;
it should be at commit f12a0fd062b1d259a0b6bc6442019e6d4c45e9f5.

Comments?
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