From 6df716340da3a6fdd33d73d7ed4c6f7590ca1c42 Mon Sep 17 00:00:00 2001 From: Stephen Hemminger Date: Thu, 3 Nov 2005 16:33:23 -0800 Subject: [TCP/DCCP]: Randomize port selection This patch randomizes the port selected on bind() for connections to help with possible security attacks. It should also be faster in most cases because there is no need for a global lock. Signed-off-by: Stephen Hemminger Signed-off-by: Arnaldo Carvalho de Melo --- net/ipv6/tcp_ipv6.c | 15 ++++----------- 1 file changed, 4 insertions(+), 11 deletions(-) (limited to 'net/ipv6/tcp_ipv6.c') diff --git a/net/ipv6/tcp_ipv6.c b/net/ipv6/tcp_ipv6.c index d693cb9..d746d3b 100644 --- a/net/ipv6/tcp_ipv6.c +++ b/net/ipv6/tcp_ipv6.c @@ -114,16 +114,9 @@ static int tcp_v6_get_port(struct sock *sk, unsigned short snum) int low = sysctl_local_port_range[0]; int high = sysctl_local_port_range[1]; int remaining = (high - low) + 1; - int rover; + int rover = net_random() % (high - low) + low; - spin_lock(&tcp_hashinfo.portalloc_lock); - if (tcp_hashinfo.port_rover < low) - rover = low; - else - rover = tcp_hashinfo.port_rover; - do { rover++; - if (rover > high) - rover = low; + do { head = &tcp_hashinfo.bhash[inet_bhashfn(rover, tcp_hashinfo.bhash_size)]; spin_lock(&head->lock); inet_bind_bucket_for_each(tb, node, &head->chain) @@ -132,9 +125,9 @@ static int tcp_v6_get_port(struct sock *sk, unsigned short snum) break; next: spin_unlock(&head->lock); + if (++rover > high) + rover = low; } while (--remaining > 0); - tcp_hashinfo.port_rover = rover; - spin_unlock(&tcp_hashinfo.portalloc_lock); /* Exhausted local port range during search? It is not * possible for us to be holding one of the bind hash -- cgit v1.1