[SCTP]: port randomization

Add port randomization rather than a simple fixed rover
for use with SCTP.  This makes it act similar to TCP, UDP, DCCP
when allocating ports.

No longer need port_alloc_lock as well (suggestion by Brian Haley).

Signed-off-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

diff --git a/include/net/sctp/structs.h b/include/net/sctp/structs.h
index 448f713..ef892e0 100644 (file)
--- a/include/net/sctp/structs.h
+++ b/include/net/sctp/structs.h
@@ -197,8 +197,6 @@ extern struct sctp_globals {
 
        /* This is the sctp port control hash.  */
        int port_hashsize;
-       int port_rover;
-       spinlock_t port_alloc_lock;  /* Protects port_rover. */
        struct sctp_bind_hashbucket *port_hashtable;
 
        /* This is the global local address list.

diff --git a/net/sctp/protocol.c b/net/sctp/protocol.c
index 4e6b59e..81b26c5 100644 (file)
--- a/net/sctp/protocol.c
+++ b/net/sctp/protocol.c
@@ -1172,9 +1172,6 @@ SCTP_STATIC __init int sctp_init(void)
                sctp_port_hashtable[i].chain = NULL;
        }
 
-       spin_lock_init(&sctp_port_alloc_lock);
-       sctp_port_rover = sysctl_local_port_range[0] - 1;
-
        printk(KERN_INFO "SCTP: Hash tables configured "
                         "(established %d bind %d)\n",
                sctp_assoc_hashsize, sctp_port_hashsize);

diff --git a/net/sctp/socket.c b/net/sctp/socket.c
index f3e1a9c..7cd58ef 100644 (file)
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5314,22 +5314,13 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
        sctp_local_bh_disable();
 
        if (snum == 0) {
-               /* Search for an available port.
-                *
-                * 'sctp_port_rover' was the last port assigned, so
-                * we start to search from 'sctp_port_rover +
-                * 1'. What we do is first check if port 'rover' is
-                * already in the hash table; if not, we use that; if
-                * it is, we try next.
-                */
-               int low = sysctl_local_port_range[0];
-               int high = sysctl_local_port_range[1];
-               int remaining = (high - low) + 1;
-               int rover;
+               /* Search for an available port. */
+               unsigned int low = sysctl_local_port_range[0];
+               unsigned int high = sysctl_local_port_range[1];
+               unsigned int remaining = (high - low) + 1;
+               unsigned int rover = net_random() % remaining + low;
                int index;
 
-               sctp_spin_lock(&sctp_port_alloc_lock);
-               rover = sctp_port_rover;
                do {
                        rover++;
                        if ((rover < low) || (rover > high))
@@ -5344,8 +5335,6 @@ static long sctp_get_port_local(struct sock *sk, union sctp_addr *addr)
                next:
                        sctp_spin_unlock(&head->lock);
                } while (--remaining > 0);
-               sctp_port_rover = rover;
-               sctp_spin_unlock(&sctp_port_alloc_lock);
 
                /* Exhausted local port range during search? */
                ret = 1;