[INET]: Justification for local port range robustness.

  There is a justifying patch for Stephen's patches. Stephen's patches
disallows using a port range of one single port and brakes the meaning
of the 'remaining' variable, in some places it has different meaning.
My patch gives back the sense of 'remaining' variable. It should mean
how many ports are remaining and nothing else. Also my patch allows
using a single port.

  I sure we must be able to use mentioned port range, this does not
restricted by documentation and does not brake current behavior.

usefull links:
Patches posted by Stephen Hemminger
  http://marc.info/?l=linux-netdev&m=119206106218187&w=2
  http://marc.info/?l=linux-netdev&m=119206109918235&w=2

Andrew Morton's comment
  http://marc.info/?l=linux-kernel&m=119248225007737&w=2

1. Allows using a port range of one single port.
2. Gives back sense of 'remaining' variable.

Signed-off-by: Anton Arapov <aarapov@redhat.com>
Acked-by: Stephen Hemminger <shemminger@linux-foundation.org>
Signed-off-by: David S. Miller <davem@davemloft.net>

6 files changed, 11 insertions, 9 deletions

diff --git a/drivers/infiniband/core/cma.c b/drivers/infiniband/core/cma.c
index 93644f82592..d08fb30768b 100644
--- a/drivers/infiniband/core/cma.c
+++ b/drivers/infiniband/core/cma.c
@@ -2797,11 +2797,12 @@ static void cma_remove_one(struct ib_device *device)
 
 static int cma_init(void)
 {
-	int ret, low, high;
+	int ret, low, high, remaining;
 
 	get_random_bytes(&next_port, sizeof next_port);
 	inet_get_local_port_range(&low, &high);
-	next_port = ((unsigned int) next_port % (high - low)) + low;
+	remaining = (high - low) + 1;
+	next_port = ((unsigned int) next_port % remaining) + low;
 
 	cma_wq = create_singlethread_workqueue("rdma_cm");
 	if (!cma_wq)
diff --git a/net/ipv4/inet_connection_sock.c b/net/ipv4/inet_connection_sock.c
index 3cef12835c4..8fb6ca23700 100644
--- a/net/ipv4/inet_connection_sock.c
+++ b/net/ipv4/inet_connection_sock.c
@@ -93,7 +93,7 @@ int inet_csk_get_port(struct inet_hashinfo *hashinfo,
 		int remaining, rover, low, high;
 
 		inet_get_local_port_range(&low, &high);
-		remaining = high - low;
+		remaining = (high - low) + 1;
 		rover = net_random() % remaining + low;
 
 		do {
diff --git a/net/ipv4/inet_hashtables.c b/net/ipv4/inet_hashtables.c
index fac6398e436..16eecc7046a 100644
--- a/net/ipv4/inet_hashtables.c
+++ b/net/ipv4/inet_hashtables.c
@@ -286,7 +286,7 @@ int inet_hash_connect(struct inet_timewait_death_row *death_row,
 		struct inet_timewait_sock *tw = NULL;
 
 		inet_get_local_port_range(&low, &high);
-		remaining = high - low;
+		remaining = (high - low) + 1;
 
 		local_bh_disable();
 		for (i = 1; i <= remaining; i++) {
diff --git a/net/ipv4/sysctl_net_ipv4.c b/net/ipv4/sysctl_net_ipv4.c
index c78acc1a7f1..ffddd2b4535 100644
--- a/net/ipv4/sysctl_net_ipv4.c
+++ b/net/ipv4/sysctl_net_ipv4.c
@@ -122,7 +122,7 @@ static int ipv4_local_port_range(ctl_table *table, int write, struct file *filp,
 	ret = proc_dointvec_minmax(&tmp, write, filp, buffer, lenp, ppos);
 
 	if (write && ret == 0) {
-		if (range[1] <= range[0])
+		if (range[1] < range[0])
 			ret = -EINVAL;
 		else
 			set_local_port_range(range);
@@ -150,7 +150,7 @@ static int ipv4_sysctl_local_port_range(ctl_table *table, int __user *name,
 
 	ret = sysctl_intvec(&tmp, name, nlen, oldval, oldlenp, newval, newlen);
 	if (ret == 0 && newval && newlen) {
-		if (range[1] <= range[0])
+		if (range[1] < range[0])
 			ret = -EINVAL;
 		else
 			set_local_port_range(range);
diff --git a/net/ipv4/udp.c b/net/ipv4/udp.c
index cb9fc58efb2..35d2b0e9e10 100644
--- a/net/ipv4/udp.c
+++ b/net/ipv4/udp.c
@@ -147,13 +147,14 @@ int __udp_lib_get_port(struct sock *sk, unsigned short snum,
 	write_lock_bh(&udp_hash_lock);
 
 	if (!snum) {
-		int i, low, high;
+		int i, low, high, remaining;
 		unsigned rover, best, best_size_so_far;
 
 		inet_get_local_port_range(&low, &high);
+		remaining = (high - low) + 1;
 
 		best_size_so_far = UINT_MAX;
-		best = rover = net_random() % (high - low) + low;
+		best = rover = net_random() % remaining + low;
 
 		/* 1st pass: look for empty (or shortest) hash chain */
 		for (i = 0; i < UDP_HTABLE_SIZE; i++) {
diff --git a/net/ipv6/inet6_hashtables.c b/net/ipv6/inet6_hashtables.c
index 1c2c2765543..d6f1026f194 100644
--- a/net/ipv6/inet6_hashtables.c
+++ b/net/ipv6/inet6_hashtables.c
@@ -261,7 +261,7 @@ int inet6_hash_connect(struct inet_timewait_death_row *death_row,
 		struct inet_timewait_sock *tw = NULL;
 
 		inet_get_local_port_range(&low, &high);
-		remaining = high - low;
+		remaining = (high - low) + 1;
 
 		local_bh_disable();
 		for (i = 1; i <= remaining; i++) {