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

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 <[email protected]>
Reviewed-by: Serge Hallyn <[email protected]>
Signed-off-by: James Morris <[email protected]>

Author: eparis

security/commoncap.c

@@ -505,6 +505,11 @@ 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
 	 */