bridge: range check STP parameters

Apply restrictions on STP parameters based 802.1D 1998 standard.
   * Fixes missing locking in set path cost ioctl
   * Uses common code for both ioctl and sysfs

This is based on an earlier patch Sasikanth V but with overhaul.

Note:
1. It does NOT enforce the restriction on the relationship max_age and
   forward delay or hello time because in existing implementation these are
   set as independant operations.

2. If STP is disabled, there is no restriction on forward delay

3. No restriction on holding time because users use Linux code to act
   as hub or be sticky.

4. Although standard allow 0-255, Linux only allows 0-63 for port priority
   because more bits are reserved for port number.

Signed-off-by: Stephen Hemminger <shemminger@vyatta.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

1 files changed, 3 insertions, 36 deletions

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 5c1e5559ebb..68b893ea8c3 100644
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -43,9 +43,7 @@ static ssize_t store_bridge_parm(struct device *d,
 	if (endp == buf)
 		return -EINVAL;
 
-	spin_lock_bh(&br->lock);
 	err = (*set)(br, val);
-	spin_unlock_bh(&br->lock);
 	return err ? err : len;
 }
 
@@ -57,20 +55,11 @@ static ssize_t show_forward_delay(struct device *d,
 	return sprintf(buf, "%lu\n", jiffies_to_clock_t(br->forward_delay));
 }
 
-static int set_forward_delay(struct net_bridge *br, unsigned long val)
-{
-	unsigned long delay = clock_t_to_jiffies(val);
-	br->forward_delay = delay;
-	if (br_is_root_bridge(br))
-		br->bridge_forward_delay = delay;
-	return 0;
-}
-
 static ssize_t store_forward_delay(struct device *d,
 				   struct device_attribute *attr,
 				   const char *buf, size_t len)
 {
-	return store_bridge_parm(d, buf, len, set_forward_delay);
+	return store_bridge_parm(d, buf, len, br_set_forward_delay);
 }
 static DEVICE_ATTR(forward_delay, S_IRUGO | S_IWUSR,
 		   show_forward_delay, store_forward_delay);
@@ -82,24 +71,11 @@ static ssize_t show_hello_time(struct device *d, struct device_attribute *attr,
 		       jiffies_to_clock_t(to_bridge(d)->hello_time));
 }
 
-static int set_hello_time(struct net_bridge *br, unsigned long val)
-{
-	unsigned long t = clock_t_to_jiffies(val);
-
-	if (t < HZ)
-		return -EINVAL;
-
-	br->hello_time = t;
-	if (br_is_root_bridge(br))
-		br->bridge_hello_time = t;
-	return 0;
-}
-
 static ssize_t store_hello_time(struct device *d,
 				struct device_attribute *attr, const char *buf,
 				size_t len)
 {
-	return store_bridge_parm(d, buf, len, set_hello_time);
+	return store_bridge_parm(d, buf, len, br_set_hello_time);
 }
 static DEVICE_ATTR(hello_time, S_IRUGO | S_IWUSR, show_hello_time,
 		   store_hello_time);
@@ -111,19 +87,10 @@ static ssize_t show_max_age(struct device *d, struct device_attribute *attr,
 		       jiffies_to_clock_t(to_bridge(d)->max_age));
 }
 
-static int set_max_age(struct net_bridge *br, unsigned long val)
-{
-	unsigned long t = clock_t_to_jiffies(val);
-	br->max_age = t;
-	if (br_is_root_bridge(br))
-		br->bridge_max_age = t;
-	return 0;
-}
-
 static ssize_t store_max_age(struct device *d, struct device_attribute *attr,
 			     const char *buf, size_t len)
 {
-	return store_bridge_parm(d, buf, len, set_max_age);
+	return store_bridge_parm(d, buf, len, br_set_max_age);
 }
 static DEVICE_ATTR(max_age, S_IRUGO | S_IWUSR, show_max_age, store_max_age);