audit: anchor all pid references in the initial pid namespace

Store and log all PIDs with reference to the initial PID namespace and
use the access functions task_pid_nr() and task_tgid_nr() for task->pid
and task->tgid.

Cc: "Eric W. Biederman" <ebiederm@xmission.com>
(informed by ebiederman's c776b5d2)
Signed-off-by: Richard Guy Briggs <rgb@redhat.com>
diff --git a/security/lsm_audit.c b/security/lsm_audit.c
index 9a62045..69fdf3b 100644
--- a/security/lsm_audit.c
+++ b/security/lsm_audit.c
@@ -220,7 +220,7 @@
 	 */
 	BUILD_BUG_ON(sizeof(a->u) > sizeof(void *)*2);
 
-	audit_log_format(ab, " pid=%d comm=", tsk->pid);
+	audit_log_format(ab, " pid=%d comm=", task_pid_nr(tsk));
 	audit_log_untrustedstring(ab, tsk->comm);
 
 	switch (a->type) {
@@ -278,9 +278,12 @@
 	}
 	case LSM_AUDIT_DATA_TASK:
 		tsk = a->u.tsk;
-		if (tsk && tsk->pid) {
-			audit_log_format(ab, " pid=%d comm=", tsk->pid);
-			audit_log_untrustedstring(ab, tsk->comm);
+		if (tsk) {
+			pid_t pid = task_pid_nr(tsk);
+			if (pid) {
+				audit_log_format(ab, " pid=%d comm=", pid);
+				audit_log_untrustedstring(ab, tsk->comm);
+			}
 		}
 		break;
 	case LSM_AUDIT_DATA_NET: