[SCTP]: Fix the bind_addr info during migration.

During accept/migrate the code attempts to copy the addresses from
the parent endpoint to the new endpoint. However, if the parent
was bound to a wildcard address, then we end up pointlessly copying
all of the current addresses on the system.

Signed-off-by: Vlad Yasevich <[e-mail]>
Signed-off-by: David S. Miller <[e-mail]>

include/net/sctp/structs.h

···
 			const struct sctp_bind_addr *src,
 			sctp_scope_t scope, gfp_t gfp,
 			int flags);
+int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
+			const struct sctp_bind_addr *src,
+			gfp_t gfp);
 int sctp_add_bind_addr(struct sctp_bind_addr *, union sctp_addr *,
 		       __u8 use_as_src, gfp_t gfp);
 int sctp_del_bind_addr(struct sctp_bind_addr *, union sctp_addr *);

net/sctp/bind_addr.c

···
 	return error;
 }
 
+/* Exactly duplicate the address lists.  This is necessary when doing
+ * peer-offs and accepts.  We don't want to put all the current system
+ * addresses into the endpoint.  That's useless.  But we do want duplicat
+ * the list of bound addresses that the older endpoint used.
+ */
+int sctp_bind_addr_dup(struct sctp_bind_addr *dest,
+			const struct sctp_bind_addr *src,
+			gfp_t gfp)
+{
+	struct sctp_sockaddr_entry *addr;
+	struct list_head *pos;
+	int error = 0;
+
+	/* All addresses share the same port.  */
+	dest->port = src->port;
+
+	list_for_each(pos, &src->address_list) {
+		addr = list_entry(pos, struct sctp_sockaddr_entry, list);
+		error = sctp_add_bind_addr(dest, &addr->a, 1, gfp);
+		if (error < 0)
+			break;
+	}
+
+	return error;
+}
+
 /* Initialize the SCTP_bind_addr structure for either an endpoint or
  * an association.
  */

net/sctp/socket.c

···
 	struct sk_buff *skb, *tmp;
 	struct sctp_ulpevent *event;
 	struct sctp_bind_hashbucket *head;
-	int flags = 0;
 
 	/* Migrate socket buffer sizes and all the socket level options to the
 	 * new socket.
···
 	/* Copy the bind_addr list from the original endpoint to the new
 	 * endpoint so that we can handle restarts properly
 	 */
-	if (PF_INET6 == assoc->base.sk->sk_family)
-		flags = SCTP_ADDR6_ALLOWED;
-	if (assoc->peer.ipv4_address)
-		flags |= SCTP_ADDR4_PEERSUPP;
-	if (assoc->peer.ipv6_address)
-		flags |= SCTP_ADDR6_PEERSUPP;
-	sctp_bind_addr_copy(&newsp->ep->base.bind_addr,
-			     &oldsp->ep->base.bind_addr,
-			     SCTP_SCOPE_GLOBAL, GFP_KERNEL, flags);
+	sctp_bind_addr_dup(&newsp->ep->base.bind_addr,
+				&oldsp->ep->base.bind_addr, GFP_KERNEL);
 
 	/* Move any messages in the old socket's receive queue that are for the
 	 * peeled off association to the new socket's receive queue.