[BRIDGE]: allow show/store of group multicast address

Bridge's communicate with each other using Spanning Tree Protocol
over a standard multicast address. There are times when testing or
layering bridges over existing topologies or tunnels, when it is
useful to use alternative multicast addresses for STP packets.

The 802.1d standard has some unused addresses, that can be used for this.
This patch is restrictive in that it only allows one of the possible
addresses in the standard.

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

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index dad4094897530c3ffb97d1ba998b9acfd7ac7891..a9feb201542569ede6591a50ff52b6670ed71173 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -19,7 +19,8 @@
 #include <linux/netfilter_bridge.h>
 #include "br_private.h"
 
-const unsigned char bridge_ula[6] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
+/* Bridge group multicast address 802.1d (pg 51). */
+const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
 
 static void br_pass_frame_up(struct net_bridge *br, struct sk_buff *skb)
 {
@@ -108,9 +109,9 @@ static int br_handle_local_finish(struct sk_buff *skb)
 /* Does address match the link local multicast address.
  * 01:80:c2:00:00:0X
  */
-static inline int is_link_local(const unsigned char *dest)
+static inline int is_link_local(const const unsigned char *dest)
 {
-       return memcmp(dest, bridge_ula, 5) == 0 && (dest[5] & 0xf0) == 0;
+       return memcmp(dest, br_group_address, 5) == 0 && (dest[5] & 0xf0) == 0;
 }
 
 /*

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 3bc9ad4834734bf9b4dedb5a370787899dc9d7b8..86ecea7ed372f2623e2a2fb732905fe3d9a0118f 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -109,6 +109,7 @@ struct net_bridge
        unsigned long                   bridge_hello_time;
        unsigned long                   bridge_forward_delay;
 
+       u8                              group_addr[ETH_ALEN];
        u16                             root_port;
        unsigned char                   stp_enabled;
        unsigned char                   topology_change;
@@ -122,7 +123,7 @@ struct net_bridge
 };
 
 extern struct notifier_block br_device_notifier;
-extern const unsigned char bridge_ula[6];
+extern const u8 br_group_address[ETH_ALEN];
 
 /* called under bridge lock */
 static inline int br_is_root_bridge(const struct net_bridge *br)

diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
index a99e90e20952e789e5355ffb06c50131c0e3e527..ed3a5441a47e471cfd2debcb6a3be68c7538738d 100644 (file)
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -47,7 +47,7 @@ static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int len
        skb->dev = dev;
        skb->protocol = htons(ETH_P_802_2);
        skb->mac.raw = skb_put(skb, size);
-       memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
+       memcpy(skb->mac.raw, p->br->group_addr, ETH_ALEN);
        memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
        skb->mac.raw[2*ETH_ALEN] = 0;
        skb->mac.raw[2*ETH_ALEN+1] = length;
@@ -171,7 +171,7 @@ int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
            || !(br->dev->flags & IFF_UP))
                goto out;
 
-       if (compare_ether_addr(dest, bridge_ula) != 0)
+       if (compare_ether_addr(dest, br->group_addr) != 0)
                goto out;
 
        buf = skb_pull(skb, 3);

diff --git a/net/bridge/br_sysfs_br.c b/net/bridge/br_sysfs_br.c
index 6f577f16c4c0b590a67d6a8be154ac7cfec77f3b..96bcb2ff59abce05cd3be39c9384898c3ba93161 100644 (file)
--- a/net/bridge/br_sysfs_br.c
+++ b/net/bridge/br_sysfs_br.c
@@ -242,6 +242,54 @@ static ssize_t show_gc_timer(struct class_device *cd, char *buf)
 }
 static CLASS_DEVICE_ATTR(gc_timer, S_IRUGO, show_gc_timer, NULL);
 
+static ssize_t show_group_addr(struct class_device *cd, char *buf)
+{
+       struct net_bridge *br = to_bridge(cd);
+       return sprintf(buf, "%x:%x:%x:%x:%x:%x\n",
+                      br->group_addr[0], br->group_addr[1],
+                      br->group_addr[2], br->group_addr[3],
+                      br->group_addr[4], br->group_addr[5]);
+}
+
+static ssize_t store_group_addr(struct class_device *cd, const char *buf,
+                                   size_t len)
+{
+       struct net_bridge *br = to_bridge(cd);
+       unsigned new_addr[6];
+       int i;
+
+       if (!capable(CAP_NET_ADMIN))
+               return -EPERM;
+
+       if (sscanf(buf, "%x:%x:%x:%x:%x:%x",
+                  &new_addr[0], &new_addr[1], &new_addr[2],
+                  &new_addr[3], &new_addr[4], &new_addr[5]) != 6)
+               return -EINVAL;
+
+       /* Must be 01:80:c2:00:00:0X */
+       for (i = 0; i < 5; i++)
+               if (new_addr[i] != br_group_address[i])
+                       return -EINVAL;
+
+       if (new_addr[5] & ~0xf)
+               return -EINVAL;
+
+       if (new_addr[5] == 1    /* 802.3x Pause address */
+           || new_addr[5] == 2 /* 802.3ad Slow protocols */
+           || new_addr[5] == 3) /* 802.1X PAE address */
+               return -EINVAL;
+
+       spin_lock_bh(&br->lock);
+       for (i = 0; i < 6; i++)
+               br->group_addr[i] = new_addr[i];
+       spin_unlock_bh(&br->lock);
+       return len;
+}
+
+static CLASS_DEVICE_ATTR(group_addr, S_IRUGO | S_IWUSR,
+                        show_group_addr, store_group_addr);
+
+
 static struct attribute *bridge_attrs[] = {
        &class_device_attr_forward_delay.attr,
        &class_device_attr_hello_time.attr,
@@ -259,6 +307,7 @@ static struct attribute *bridge_attrs[] = {
        &class_device_attr_tcn_timer.attr,
        &class_device_attr_topology_change_timer.attr,
        &class_device_attr_gc_timer.attr,
+       &class_device_attr_group_addr.attr,
        NULL
 };