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

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Date:	Tue, 17 Jan 2012 23:28:03 +0900
From:	"J. R. Okajima" <hooanon05@...oo.co.jp>
To:	James Morris <jmorris@...ei.org>
Cc:	Linus Torvalds <torvalds@...ux-foundation.org>,
	Eric Paris <eparis@...hat.com>, linux-kernel@...r.kernel.org,
	linux-security-module@...r.kernel.org
Subject: Re: [GIT] Security updates for 3.3: SELinux


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?


J. R. Okajima
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