linux-kernel - Re: [GIT] Security updates for 3.3: SELinux

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Date:	Tue, 17 Jan 2012 09:38:42 -0500
From:	Eric Paris <eparis@...hat.com>
To:	"J. R. Okajima" <hooanon05@...oo.co.jp>
Cc:	James Morris <jmorris@...ei.org>,
	Linus Torvalds <torvalds@...ux-foundation.org>,
	linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org, w41ter@...il.com
Subject: Re: [GIT] Security updates for 3.3: SELinux

On Tue, 2012-01-17 at 23:28 +0900, J. R. Okajima wrote:
> James Morris:
> > Eric Paris (12):
> 	:::
> >       capabitlies: ns_capable can use the cap helpers rather than lsm call
> 
> After this commit, I am afraid access(2) on NFS may not work correctly.
> The scenario based upon my guess.
> - access(2) overrides the credentials.
> - calls inode_permission() -- ... -- generic_permission() --
>   ns_capable().
> - while the old ns_capable() calls security_capable(current_cred()), the
>   new ns_capable() calls has_ns_capability(current) --
>   security_capable(__task_cred(t)).
> 
> current_cred() returns current->cred which is effective (overridden)
> credentials, but __task_cred(current) returns current->real_cred (the
> NFSD's credential). And the overridden credentials by access(2) lost.
> 
> Is my guess correct?

Linus please revert d2a7009f0bb03fa22ad08dd25472efa0568126b9

Your explanation seems plausible.  I will review the rest and make sure
a similar problem was not introduced elsewhere.

-Eric

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