[CVE-2012-2123] lucid/natty fcaps: clear the same personality flags as suid when fcaps are used

[Steve Conklin]

This is a clean application of an upstream patch. The same fix has
already come from upstream stable for Oneiric and Precise.

-Steve

>From c825bb675aea46fe858b58d1d31dccc6bb7c03c1 Mon Sep 17 00:00:00 2001
From: Eric Paris <eparis at redhat.com>
Date: Tue, 17 Apr 2012 16:26:54 -0400
Subject: [PATCH] fcaps: clear the same personality flags as suid when fcaps
 are used

CVE-2012-2123

BugLink: http://bugs.launchpad.net/bugs/987571

If a process increases permissions using fcaps all of the dangerous
personality flags which are cleared for suid apps should also be cleared.
Thus programs given priviledge with fcaps will continue to have address
space
randomization enabled even if the parent tried to disable it to make it
easier to attack.

Signed-off-by: Eric Paris <eparis at redhat.com>
Reviewed-by: Serge Hallyn <serge.hallyn at canonical.com>
Signed-off-by: James Morris <james.l.morris at oracle.com>

(cherry picked from commit d52fc5dde1)
Signed-off-by: Steve Conklin <sconklin at canonical.com>
---
 security/commoncap.c |    5 +++++
 1 file changed, 5 insertions(+)

diff --git a/security/commoncap.c b/security/commoncap.c
index 50be79b..5d5f64b 100644
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -512,6 +512,11 @@ int cap_bprm_set_creds(struct linux_binprm *bprm)
 	}
 skip:

+	/* if we have fs caps, clear dangerous personality flags */
+	if (!cap_issubset(new->cap_permitted, old->cap_permitted))
+		bprm->per_clear |= PER_CLEAR_ON_SETID;
+
+
 	/* Don't let someone trace a set[ug]id/setpcap binary with the revised
 	 * credentials unless they have the appropriate permit
 	 */
-- 
1.7.9.5