sctp: Make the port hash table use struct net in it's key.

- Add struct net into the port hash table hash calculation
- Add struct net inot the struct sctp_bind_bucket so there
  is a memory of which network namespace a port is allocated in.
  No need for a ref count because sctp_bind_bucket only exists
  when there are sockets in the hash table and sockets can not
  change their network namspace, and sockets already ref count
  their network namespace.
- Add struct net into the key comparison when we are testing
  to see if we have found the port hash table entry we are
  looking for.

With these changes lookups in the port hash table becomes
safe to use in multiple network namespaces.

Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Vlad Yasevich <vyasevich@gmail.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

include/net/sctp/sctp.h

@@ -632,9 +632,9 @@ static inline int sctp_sanity_check(void)
 
 /* Warning: The following hash functions assume a power of two 'size'. */
 /* This is the hash function for the SCTP port hash table. */
-static inline int sctp_phashfn(__u16 lport)
+static inline int sctp_phashfn(struct net *net, __u16 lport)
 {
-	return lport & (sctp_port_hashsize - 1);
+	return (net_hash_mix(net) + lport) & (sctp_port_hashsize - 1);
 }
 
 /* This is the hash function for the endpoint hash table. */

include/net/sctp/structs.h

@@ -102,6 +102,7 @@ struct sctp_bind_bucket {
 	unsigned short	fastreuse;
 	struct hlist_node	node;
 	struct hlist_head	owner;
+	struct net	*net;
 };
 
 struct sctp_bind_hashbucket {

net/sctp/socket.c

@@ -5769,7 +5769,7 @@ static void sctp_unhash(struct sock *sk)
  * a fastreuse flag (FIXME: NPI ipg).
  */
 static struct sctp_bind_bucket *sctp_bucket_create(
-	struct sctp_bind_hashbucket *head, unsigned short snum);
+	struct sctp_bind_hashbucket *head, struct net *, unsigned short snum);
 
 static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 {
@@ -5799,11 +5799,12 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 				rover = low;
 			if (inet_is_reserved_local_port(rover))
 				continue;
-			index = sctp_phashfn(rover);
+			index = sctp_phashfn(sock_net(sk), rover);
 			head = &sctp_port_hashtable[index];
 			sctp_spin_lock(&head->lock);
 			sctp_for_each_hentry(pp, node, &head->chain)
-				if (pp->port == rover)
+				if ((pp->port == rover) &&
+				    net_eq(sock_net(sk), pp->net))
 					goto next;
 			break;
 		next:
@@ -5827,10 +5828,10 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
 		 * to the port number (snum) - we detect that with the
 		 * port iterator, pp being NULL.
 		 */
-		head = &sctp_port_hashtable[sctp_phashfn(snum)];
+		head = &sctp_port_hashtable[sctp_phashfn(sock_net(sk), snum)];
 		sctp_spin_lock(&head->lock);
 		sctp_for_each_hentry(pp, node, &head->chain) {
-			if (pp->port == snum)
+			if ((pp->port == snum) && net_eq(pp->net, sock_net(sk)))
 				goto pp_found;
 		}
 	}
@@ -5881,7 +5882,7 @@ pp_found:
 pp_not_found:
 	/* If there was a hash table miss, create a new port.  */
 	ret = 1;
-	if (!pp && !(pp = sctp_bucket_create(head, snum)))
+	if (!pp && !(pp = sctp_bucket_create(head, sock_net(sk), snum)))
 		goto fail_unlock;
 
 	/* In either case (hit or miss), make sure fastreuse is 1 only
@@ -6113,7 +6114,7 @@ unsigned int sctp_poll(struct file *file, struct socket *sock, poll_table *wait)
  ********************************************************************/
 
 static struct sctp_bind_bucket *sctp_bucket_create(
-	struct sctp_bind_hashbucket *head, unsigned short snum)
+	struct sctp_bind_hashbucket *head, struct net *net, unsigned short snum)
 {
 	struct sctp_bind_bucket *pp;
 
@@ -6123,6 +6124,7 @@ static struct sctp_bind_bucket *sctp_bucket_create(
 		pp->port = snum;
 		pp->fastreuse = 0;
 		INIT_HLIST_HEAD(&pp->owner);
+		pp->net = net;
 		hlist_add_head(&pp->node, &head->chain);
 	}
 	return pp;
@@ -6142,7 +6144,8 @@ static void sctp_bucket_destroy(struct sctp_bind_bucket *pp)
 static inline void __sctp_put_port(struct sock *sk)
 {
 	struct sctp_bind_hashbucket *head =
-		&sctp_port_hashtable[sctp_phashfn(inet_sk(sk)->inet_num)];
+		&sctp_port_hashtable[sctp_phashfn(sock_net(sk),
+						  inet_sk(sk)->inet_num)];
 	struct sctp_bind_bucket *pp;
 
 	sctp_spin_lock(&head->lock);
@@ -6809,7 +6812,8 @@ static void sctp_sock_migrate(struct sock *oldsk, struct sock *newsk,
 	newsp->hmac = NULL;
 
 	/* Hook this new socket in to the bind_hash list. */
-	head = &sctp_port_hashtable[sctp_phashfn(inet_sk(oldsk)->inet_num)];
+	head = &sctp_port_hashtable[sctp_phashfn(sock_net(oldsk),
+						 inet_sk(oldsk)->inet_num)];
 	sctp_local_bh_disable();
 	sctp_spin_lock(&head->lock);
 	pp = sctp_sk(oldsk)->bind_hash;