audit: handle a clean auditd shutdown with grace

When auditd stops cleanly it sets 'auditd_pid' to 0 with an
AUDIT_SET message, in this case we should reset our backlog
queues via the auditd_reset() function.  This patch also adds
a 'auditd_pid' check to the top of kauditd_send_unicast_skb()
so we can fail quicker.

Signed-off-by: Paul Moore <paul@paul-moore.com>

1 files changed, 6 insertions, 0 deletions

diff --git a/kernel/audit.c b/kernel/audit.c
index 0572e5dcfda7..b447a6b1fdc8 100644
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -468,6 +468,10 @@ static int kauditd_send_unicast_skb(struct sk_buff *skb)
 {
         int rc;
 
+        /* if we know nothing is connected, don't even try the netlink call */
+        if (!audit_pid)
+                return -ECONNREFUSED;
+
         /* get an extra skb reference in case we fail to send */
         skb_get(skb);
         rc = netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
@@ -1009,6 +1013,8 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
                         audit_pid = new_pid;
                         audit_nlk_portid = NETLINK_CB(skb).portid;
                         audit_sock = skb->sk;
+                        if (!new_pid)
+                                auditd_reset();
                         wake_up_interruptible(&kauditd_wait);
                 }
                 if (s.mask & AUDIT_STATUS_RATE_LIMIT) {