audit: stop an old auditd being starved out by a new auditd

[cascardo/linux.git] / kernel / audit.c

diff --git a/kernel/audit.c b/kernel/audit.c
index d6dd95c..2fd63d6 100644 (file)
--- a/kernel/audit.c
+++ b/kernel/audit.c
@@ -809,6 +809,16 @@ static int audit_set_feature(struct sk_buff *skb)
        return 0;
 }
 
+static int audit_replace(pid_t pid)
+{
+       struct sk_buff *skb = audit_make_reply(0, 0, AUDIT_REPLACE, 0, 0,
+                                              &pid, sizeof(pid));
+
+       if (!skb)
+               return -ENOMEM;
+       return netlink_unicast(audit_sock, skb, audit_nlk_portid, 0);
+}
+
 static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
 {
        u32                     seq;
@@ -870,9 +880,13 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh)
                }
                if (s.mask & AUDIT_STATUS_PID) {
                        int new_pid = s.pid;
+                       pid_t requesting_pid = task_tgid_vnr(current);
 
-                       if ((!new_pid) && (task_tgid_vnr(current) != audit_pid))
+                       if ((!new_pid) && (requesting_pid != audit_pid))
                                return -EACCES;
+                       if (audit_pid && new_pid &&
+                           audit_replace(requesting_pid) != -ECONNREFUSED)
+                               return -EEXIST;
                        if (audit_enabled != AUDIT_OFF)
                                audit_log_config_change("audit_pid", new_pid, audit_pid, 1);
                        audit_pid = new_pid;