1 files changed, 44 insertions, 11 deletions

diff --git a/net/netlink/af_netlink.c b/net/netlink/af_netlink.c
index 5b33879c6422..b73d4e61c5ac 100644
--- a/net/netlink/af_netlink.c
+++ b/net/netlink/af_netlink.c
@@ -85,6 +85,7 @@ struct netlink_sock {
 
 #define NETLINK_KERNEL_SOCKET   0x1
 #define NETLINK_RECV_PKTINFO    0x2
+#define NETLINK_BROADCAST_SEND_ERROR    0x4
 
 static inline struct netlink_sock *nlk_sk(struct sock *sk)
 {
@@ -995,12 +996,15 @@ static inline int do_one_broadcast(struct sock *sk,
                 netlink_overrun(sk);
                 /* Clone failed. Notify ALL listeners. */
                 p->failure = 1;
+                if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
+                        p->delivery_failure = 1;
         } else if (sk_filter(sk, p->skb2)) {
                 kfree_skb(p->skb2);
                 p->skb2 = NULL;
         } else if ((val = netlink_broadcast_deliver(sk, p->skb2)) < 0) {
                 netlink_overrun(sk);
-                p->delivery_failure = 1;
+                if (nlk->flags & NETLINK_BROADCAST_SEND_ERROR)
+                        p->delivery_failure = 1;
         } else {
                 p->congested |= val;
                 p->delivered = 1;
@@ -1045,10 +1049,9 @@ int netlink_broadcast(struct sock *ssk, struct sk_buff *skb, u32 pid,
 
         netlink_unlock_table();
 
-        if (info.skb2)
-                kfree_skb(info.skb2);
+        kfree_skb(info.skb2);
 
-        if (info.delivery_failure || info.failure)
+        if (info.delivery_failure)
                 return -ENOBUFS;
 
         if (info.delivered) {
@@ -1088,6 +1091,13 @@ out:
         return 0;
 }
 
+/**
+ * netlink_set_err - report error to broadcast listeners
+ * @ssk: the kernel netlink socket, as returned by netlink_kernel_create()
+ * @pid: the PID of a process that we want to skip (if any)
+ * @groups: the broadcast group that will notice the error
+ * @code: error code, must be negative (as usual in kernelspace)
+ */
 void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
 {
         struct netlink_set_err_data info;
@@ -1097,7 +1107,8 @@ void netlink_set_err(struct sock *ssk, u32 pid, u32 group, int code)
         info.exclude_sk = ssk;
         info.pid = pid;
         info.group = group;
-        info.code = code;
+        /* sk->sk_err wants a positive error value */
+        info.code = -code;
 
         read_lock(&nl_table_lock);
 
@@ -1164,6 +1175,13 @@ static int netlink_setsockopt(struct socket *sock, int level, int optname,
                 err = 0;
                 break;
         }
+        case NETLINK_BROADCAST_ERROR:
+                if (val)
+                        nlk->flags |= NETLINK_BROADCAST_SEND_ERROR;
+                else
+                        nlk->flags &= ~NETLINK_BROADCAST_SEND_ERROR;
+                err = 0;
+                break;
         default:
                 err = -ENOPROTOOPT;
         }
@@ -1196,6 +1214,16 @@ static int netlink_getsockopt(struct socket *sock, int level, int optname,
                         return -EFAULT;
                 err = 0;
                 break;
+        case NETLINK_BROADCAST_ERROR:
+                if (len < sizeof(int))
+                        return -EINVAL;
+                len = sizeof(int);
+                val = nlk->flags & NETLINK_BROADCAST_SEND_ERROR ? 1 : 0;
+                if (put_user(len, optlen) ||
+                    put_user(val, optval))
+                        return -EFAULT;
+                err = 0;
+                break;
         default:
                 err = -ENOPROTOOPT;
         }
@@ -1522,8 +1550,7 @@ EXPORT_SYMBOL(netlink_set_nonroot);
 
 static void netlink_destroy_callback(struct netlink_callback *cb)
 {
-        if (cb->skb)
-                kfree_skb(cb->skb);
+        kfree_skb(cb->skb);
         kfree(cb);
 }
 
@@ -1740,12 +1767,18 @@ int nlmsg_notify(struct sock *sk, struct sk_buff *skb, u32 pid,
                         exclude_pid = pid;
                 }
 
-                /* errors reported via destination sk->sk_err */
-                nlmsg_multicast(sk, skb, exclude_pid, group, flags);
+                /* errors reported via destination sk->sk_err, but propagate
+                 * delivery errors if NETLINK_BROADCAST_ERROR flag is set */
+                err = nlmsg_multicast(sk, skb, exclude_pid, group, flags);
         }
 
-        if (report)
-                err = nlmsg_unicast(sk, skb, pid);
+        if (report) {
+                int err2;
+
+                err2 = nlmsg_unicast(sk, skb, pid);
+                if (!err || err == -ESRCH)
+                        err = err2;
+        }
 
         return err;
 }