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, 8 insertions, 18 deletions

diff --git a/net/bridge/br_sysfs_if.c b/net/bridge/br_sysfs_if.c
index fd5799c..6229b62 100644
--- a/net/bridge/br_sysfs_if.c
+++ b/net/bridge/br_sysfs_if.c
@@ -23,7 +23,7 @@
 struct brport_attribute {
 	struct attribute	attr;
 	ssize_t (*show)(struct net_bridge_port *, char *);
-	ssize_t (*store)(struct net_bridge_port *, unsigned long);
+	int (*store)(struct net_bridge_port *, unsigned long);
 };
 
 #define BRPORT_ATTR(_name,_mode,_show,_store)		        \
@@ -38,27 +38,17 @@ static ssize_t show_path_cost(struct net_bridge_port *p, char *buf)
 {
 	return sprintf(buf, "%d\n", p->path_cost);
 }
-static ssize_t store_path_cost(struct net_bridge_port *p, unsigned long v)
-{
-	br_stp_set_path_cost(p, v);
-	return 0;
-}
+
 static BRPORT_ATTR(path_cost, S_IRUGO | S_IWUSR,
-		   show_path_cost, store_path_cost);
+		   show_path_cost, br_stp_set_path_cost);
 
 static ssize_t show_priority(struct net_bridge_port *p, char *buf)
 {
 	return sprintf(buf, "%d\n", p->priority);
 }
-static ssize_t store_priority(struct net_bridge_port *p, unsigned long v)
-{
-	if (v >= (1<<(16-BR_PORT_BITS)))
-		return -ERANGE;
-	br_stp_set_port_priority(p, v);
-	return 0;
-}
+
 static BRPORT_ATTR(priority, S_IRUGO | S_IWUSR,
-			 show_priority, store_priority);
+			 show_priority, br_stp_set_port_priority);
 
 static ssize_t show_designated_root(struct net_bridge_port *p, char *buf)
 {
@@ -136,7 +126,7 @@ static ssize_t show_hold_timer(struct net_bridge_port *p,
 }
 static BRPORT_ATTR(hold_timer, S_IRUGO, show_hold_timer, NULL);
 
-static ssize_t store_flush(struct net_bridge_port *p, unsigned long v)
+static int store_flush(struct net_bridge_port *p, unsigned long v)
 {
 	br_fdb_delete_by_port(p->br, p, 0); // Don't delete local entry
 	return 0;
@@ -148,7 +138,7 @@ static ssize_t show_hairpin_mode(struct net_bridge_port *p, char *buf)
 	int hairpin_mode = (p->flags & BR_HAIRPIN_MODE) ? 1 : 0;
 	return sprintf(buf, "%d\n", hairpin_mode);
 }
-static ssize_t store_hairpin_mode(struct net_bridge_port *p, unsigned long v)
+static int store_hairpin_mode(struct net_bridge_port *p, unsigned long v)
 {
 	if (v)
 		p->flags |= BR_HAIRPIN_MODE;
@@ -165,7 +155,7 @@ static ssize_t show_multicast_router(struct net_bridge_port *p, char *buf)
 	return sprintf(buf, "%d\n", p->multicast_router);
 }
 
-static ssize_t store_multicast_router(struct net_bridge_port *p,
+static int store_multicast_router(struct net_bridge_port *p,
 				      unsigned long v)
 {
 	return br_multicast_set_port_router(p, v);