[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/net/sctp/socket.c b/net/sctp/socket.c
index f3e1a9c..7cd58ef 100644
--- a/net/sctp/socket.c
+++ b/net/sctp/socket.c
@@ -5314,22 +5314,13 @@
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 @@
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;