linux-kernel - Re: [PATCH 2/3] SELINUX: Make selinux cache VFS RCU walks safe

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Date:	Fri, 22 Apr 2011 08:16:19 -0700
From:	Andi Kleen <ak@...ux.intel.com>
To:	Eric Paris <eparis@...isplace.org>
Cc:	Andi Kleen <andi@...stfloor.org>, linux-fsdevel@...r.kernel.org,
	akpm@...ux-foundation.org, torvalds@...ux-foundation.org,
	linux-kernel@...r.kernel.org, npiggin@...nel.dk,
	shaohua.li@...el.com, sds@...ho.nsa.gov, jmorris@...ei.org,
	linux-security-module@...r.kernel.org
Subject: Re: [PATCH 2/3] SELINUX: Make selinux cache VFS RCU walks safe

On Thu, Apr 21, 2011 at 08:45:17PM -0400, Eric Paris wrote:
> I'll take a close look over the weekend, but I'm pretty sure this is
> even more strict than it needs to be.  I looked at this a while ago
> and the only RCU unsafe location I could find was in the generic LSM
> 'audit' code (nothing to do with the audit subsystem).  That code can
> do a d = d_find_alias(); dput(d).  I don't think I realized the dput()
> was not RCU safe at the time.  We use it to come up with a name of a
> dentry that might have caused the denial (although obviously not
> necessarily the right name)
> 
> I could just drop that piece of functionality (and rely on the audit
> subsystem for the info), but I think I'd rather do it your way.  I
> think I can push your flags a lot deeper than you have pushed them
> (and remove them in some places you have included them).  Let me look
> over the next day or two....

Sounds good. I would prefer to do that as a follow on patch to make
this patch not even more complicated. Is that ok for you?

Also the same approach could be applied to SMACK then I guess.

-Andi
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