fcaps: clear the same personality flags as suid when fcaps are used

Bugdb: 13966
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.
This fixes: CVE-2012-2123

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

diff --git a/security/commoncap.c b/security/commoncap.c
index a93b3b73307991c69738bc0dab712e56330ba932..387fb959e0e122354e85374bf20565589095c795 100644 (file)
--- a/security/commoncap.c
+++ b/security/commoncap.c
@@ -510,6 +510,11 @@ 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
         */