linux-kernel - Re: [PATCH 1/1] file capabilities: remove cap_task

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Date:	Mon, 3 Mar 2008 09:50:15 -0300
From:	"Luiz Fernando N. Capitulino" <lcapitulino@...driva.com.br>
To:	serge@...lyn.com
Cc:	lkml <linux-kernel@...r.kernel.org>,
	linux-security-module@...r.kernel.org,
	Andrew Morgan <morgan@...nel.org>,
	Stephen Smalley <sds@...ch.ncsc.mil>,
	Mike Galbraith <efault@....de>, buraphalinuxserver@...il.com,
	elendil@...net.nl, stable@...nel.org
Subject: Re: [PATCH 1/1] file capabilities: remove cap_task_kill()

Em Fri, 29 Feb 2008 15:26:34 -0600
serge@...lyn.com escreveu:

| Quoting Luiz Fernando N. Capitulino (lcapitulino@...driva.com.br):
| > Em Thu, 28 Feb 2008 11:38:17 -0600
| > serge@...lyn.com escreveu:
| > 
| > | The original justification for cap_task_kill() was as follows:
| > | 
| > | 	check_kill_permission() does appropriate uid equivalence checks.
| > | 	However with file capabilities it becomes possible for an
| > | 	unprivileged user to execute a file with file capabilities
| > | 	resulting in a more privileged task with the same uid.
| > | 
| > | However now that cap_task_kill() always returns 0 (permission
| > | granted) when p->uid==current->uid, the whole hook is worthless,
| > | and only likely to create more subtle problems in the corner cases
| > | where it might still be called but return -EPERM.  Those cases
| > | are basically when uids are different but euid/suid is equivalent
| > | as per the check in check_kill_permission().
| > | 
| > | This patch removes cap_task_kill().
| > 
| >  2.6.24 seems to have the same bug, what about a rediff for it and
| > submit the patch to -stable team?
| 
| Luiz, could you confirm that the below works?

 Yes, it does.

 Thanks.

-- 
Luiz Fernando N. Capitulino
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