5 files changed, 98 insertions, 19 deletions

diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index fbe7714..3cef128 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -33,6 +33,19 @@ EXPORT_SYMBOL(inet_csk_timer_bug_msg);
  * This array holds the first and last local port number.
  */
 int sysctl_local_port_range[2] = { 32768, 61000 };
+DEFINE_SEQLOCK(sysctl_port_range_lock);
+
+void inet_get_local_port_range(int *low, int *high)
+{
+	unsigned seq;
+	do {
+		seq = read_seqbegin(&sysctl_port_range_lock);
+
+		*low = sysctl_local_port_range[0];
+		*high = sysctl_local_port_range[1];
+	} while (read_seqretry(&sysctl_port_range_lock, seq));
+}
+EXPORT_SYMBOL(inet_get_local_port_range);
 
 int inet_csk_bind_conflict(const struct sock *sk,
 			   const struct inet_bind_bucket *tb)
@@ -77,10 +90,11 @@ int inet_csk_get_port(struct inet_hashinfo *hashinfo,
 
 	local_bh_disable();
 	if (!snum) {
-		int low = sysctl_local_port_range[0];
-		int high = sysctl_local_port_range[1];
-		int remaining = (high - low) + 1;
-		int rover = net_random() % (high - low) + low;
+		int remaining, rover, low, high;
+
+		inet_get_local_port_range(&low, &high);
+		remaining = high - low;
+		rover = net_random() % remaining + low;
 
 		do {
 			head = &hashinfo->bhash[inet_bhashfn(rover, hashinfo->bhash_size)];
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index fb66262..fac6398 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -279,19 +279,18 @@ int inet_hash_connect(struct inet_timewait_death_row *death_row,
 	int ret;
 
 	if (!snum) {
-		int low = sysctl_local_port_range[0];
-		int high = sysctl_local_port_range[1];
-		int range = high - low;
-		int i;
-		int port;
+		int i, remaining, low, high, port;
 		static u32 hint;
 		u32 offset = hint + inet_sk_port_offset(sk);
 		struct hlist_node *node;
 		struct inet_timewait_sock *tw = NULL;
 
+		inet_get_local_port_range(&low, &high);
+		remaining = high - low;
+
 		local_bh_disable();
-		for (i = 1; i <= range; i++) {
-			port = low + (i + offset) % range;
+		for (i = 1; i <= remaining; i++) {
+			port = low + (i + offset) % remaining;
 			head = &hinfo->bhash[inet_bhashfn(port, hinfo->bhash_size)];
 			spin_lock(&head->lock);
 
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index 53ef0f4..eb286ab 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -12,6 +12,7 @@
 #include <linux/sysctl.h>
 #include <linux/igmp.h>
 #include <linux/inetdevice.h>
+#include <linux/seqlock.h>
 #include <net/snmp.h>
 #include <net/icmp.h>
 #include <net/ip.h>
@@ -89,6 +90,74 @@ static int ipv4_sysctl_forward_strategy(ctl_table *table,
 	return 1;
 }
 
+extern seqlock_t sysctl_port_range_lock;
+extern int sysctl_local_port_range[2];
+
+/* Update system visible IP port range */
+static void set_local_port_range(int range[2])
+{
+	write_seqlock(&sysctl_port_range_lock);
+	sysctl_local_port_range[0] = range[0];
+	sysctl_local_port_range[1] = range[1];
+	write_sequnlock(&sysctl_port_range_lock);
+}
+
+/* Validate changes from /proc interface. */
+static int ipv4_local_port_range(ctl_table *table, int write, struct file *filp,
+				 void __user *buffer,
+				 size_t *lenp, loff_t *ppos)
+{
+	int ret;
+	int range[2] = { sysctl_local_port_range[0],
+			 sysctl_local_port_range[1] };
+	ctl_table tmp = {
+		.data = &range,
+		.maxlen = sizeof(range),
+		.mode = table->mode,
+		.extra1 = &ip_local_port_range_min,
+		.extra2 = &ip_local_port_range_max,
+	};
+
+	ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);
+
+	if (write && ret == 0) {
+		if (range[1] <= range[0])
+			ret = -EINVAL;
+		else
+			set_local_port_range(range);
+	}
+
+	return ret;
+}
+
+/* Validate changes from sysctl interface. */
+static int ipv4_sysctl_local_port_range(ctl_table *table, int __user *name,
+					 int nlen, void __user *oldval,
+					 size_t __user *oldlenp,
+					void __user *newval, size_t newlen)
+{
+	int ret;
+	int range[2] = { sysctl_local_port_range[0],
+			 sysctl_local_port_range[1] };
+	ctl_table tmp = {
+		.data = &range,
+		.maxlen = sizeof(range),
+		.mode = table->mode,
+		.extra1 = &ip_local_port_range_min,
+		.extra2 = &ip_local_port_range_max,
+	};
+
+	ret = sysctl_intvec(&tmp, name, nlen, oldval, oldlenp, newval, newlen);
+	if (ret == 0 && newval && newlen) {
+		if (range[1] <= range[0])
+			ret = -EINVAL;
+		else
+			set_local_port_range(range);
+	}
+	return ret;
+}
+
+
 static int proc_tcp_congestion_control(ctl_table *ctl, int write, struct file * filp,
 				       void __user *buffer, size_t *lenp, loff_t *ppos)
 {
@@ -427,10 +496,8 @@ ctl_table ipv4_table[] = {
 		.data		= &sysctl_local_port_range,
 		.maxlen		= sizeof(sysctl_local_port_range),
 		.mode		= 0644,
-		.proc_handler	= &proc_dointvec_minmax,
-		.strategy	= &sysctl_intvec,
-		.extra1		= ip_local_port_range_min,
-		.extra2		= ip_local_port_range_max
+		.proc_handler	= &ipv4_local_port_range,
+		.strategy	= &ipv4_sysctl_local_port_range,
 	},
 	{
 		.ctl_name	= NET_IPV4_ICMP_ECHO_IGNORE_ALL,
diff --git a/net/ipv4/tcp_ipv4.c b/net/ipv4/tcp_ipv4.c
index 8855e64..38cf73a 100644
--- a/net/ipv4/tcp_ipv4.c
+++ b/net/ipv4/tcp_ipv4.c
@@ -2470,6 +2470,5 @@ EXPORT_SYMBOL(tcp_v4_syn_recv_sock);
 EXPORT_SYMBOL(tcp_proc_register);
 EXPORT_SYMBOL(tcp_proc_unregister);
 #endif
-EXPORT_SYMBOL(sysctl_local_port_range);
 EXPORT_SYMBOL(sysctl_tcp_low_latency);
 
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index ef4d901..cb9fc58 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -147,11 +147,11 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 	write_lock_bh(&udp_hash_lock);
 
 	if (!snum) {
-		int i;
-		int low = sysctl_local_port_range[0];
-		int high = sysctl_local_port_range[1];
+		int i, low, high;
 		unsigned rover, best, best_size_so_far;
 
+		inet_get_local_port_range(&low, &high);
+
 		best_size_so_far = UINT_MAX;
 		best = rover = net_random() % (high - low) + low;