[SCTP]: Correctly set IP id for SCTP traffic

Make SCTP 1-1 style and peeled-off associations behave like TCP when
setting IP id. In both cases, we set the inet_sk(sk)->daddr and initialize
inet_sk(sk)->id to a random value.

Signed-off-by: Vlad Yasevich <vladislav.yasevich@hp.com>
Signed-off-by: Sridhar Samudrala <sri@us.ibm.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

net/sctp/protocol.c

@@ -591,7 +591,7 @@ static struct sock *sctp_v4_create_accept_sk(struct sock *sk,
 	newinet->dport = htons(asoc->peer.port);
 	newinet->daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
 	newinet->pmtudisc = inet->pmtudisc;
-      	newinet->id = 0;
+      	newinet->id = asoc->next_tsn ^ jiffies;
 
 	newinet->uc_ttl = -1;
 	newinet->mc_loop = 1;

net/sctp/socket.c

@@ -3372,6 +3372,7 @@ SCTP_STATIC int sctp_do_peeloff(struct sctp_association *asoc,
 {
 	struct sock *sk = asoc->base.sk;
 	struct socket *sock;
+	struct inet_sock *inetsk;
 	int err = 0;
 
 	/* An association cannot be branched off from an already peeled-off
@@ -3389,6 +3390,14 @@ SCTP_STATIC int sctp_do_peeloff(struct sctp_association *asoc,
 	 * asoc to the newsk.
 	 */
 	sctp_sock_migrate(sk, sock->sk, asoc, SCTP_SOCKET_UDP_HIGH_BANDWIDTH);
+
+	/* Make peeled-off sockets more like 1-1 accepted sockets.
+	 * Set the daddr and initialize id to something more random
+	 */
+	inetsk = inet_sk(sock->sk);
+	inetsk->daddr = asoc->peer.primary_addr.v4.sin_addr.s_addr;
+	inetsk->id = asoc->next_tsn ^ jiffies;
+
 	*sockp = sock;
 
 	return err;