[AUDIT] ratelimit printk messages audit

some printk messages from the audit system can become excessive. This
patch ratelimits those messages. It was found that messages, such as
the audit backlog lost printk message could flood the logs to the point
that a machine could take an nmi watchdog hit or otherwise become
unresponsive.

Signed-off-by: Eric Paris <[e-mail]>

kernel/audit.c

···
 	case AUDIT_FAIL_SILENT:
 		break;
 	case AUDIT_FAIL_PRINTK:
-		printk(KERN_ERR "audit: %s\n", message);
+		if (printk_ratelimit())
+			printk(KERN_ERR "audit: %s\n", message);
 		break;
 	case AUDIT_FAIL_PANIC:
 		panic("audit: %s\n", message);
···
 	}
 
 	if (print) {
-		printk(KERN_WARNING
-		       "audit: audit_lost=%d audit_rate_limit=%d audit_backlog_limit=%d\n",
-		       atomic_read(&audit_lost),
-		       audit_rate_limit,
-		       audit_backlog_limit);
+		if (printk_ratelimit())
+			printk(KERN_WARNING
+				"audit: audit_lost=%d audit_rate_limit=%d "
+				"audit_backlog_limit=%d\n",
+				atomic_read(&audit_lost),
+				audit_rate_limit,
+				audit_backlog_limit);
 		audit_panic(message);
 	}
 }
···
 					audit_pid = 0;
 				}
 			} else {
-				printk(KERN_NOTICE "%s\n", skb->data + NLMSG_SPACE(0));
+				if (printk_ratelimit())
+					printk(KERN_NOTICE "%s\n", skb->data +
+						NLMSG_SPACE(0));
+				else
+					audit_log_lost("printk limit exceeded\n");
 				kfree_skb(skb);
 			}
 		} else {
···
 			remove_wait_queue(&audit_backlog_wait, &wait);
 			continue;
 		}
-		if (audit_rate_check())
+		if (audit_rate_check() && printk_ratelimit())
 			printk(KERN_WARNING
 			       "audit: audit_backlog=%d > "
 			       "audit_backlog_limit=%d\n",
···
 			skb_queue_tail(&audit_skb_queue, ab->skb);
 			ab->skb = NULL;
 			wake_up_interruptible(&kauditd_wait);
-		} else {
+		} else if (printk_ratelimit()) {
 			struct nlmsghdr *nlh = nlmsg_hdr(ab->skb);
 			printk(KERN_NOTICE "type=%d %s\n", nlh->nlmsg_type, ab->skb->data + NLMSG_SPACE(0));
+		} else {
+			audit_log_lost("printk limit exceeded\n");
 		}
 	}
 	audit_buffer_free(ab);