[BRIDGE]: use llc for receiving STP packets

Use LLC for the receive path of Spanning Tree Protocol packets.
This allows link local multicast packets to be received by
other protocols (if they care), and uses the existing LLC
code to get STP packets back into bridge code.

The bridge multicast address is also checked, so bridges using
other link local multicast addresses are ignored. This allows
for use of different multicast addresses to define separate STP
domains.

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

diff --git a/net/bridge/Kconfig b/net/bridge/Kconfig
index db23d59746cf291c2480cf7a5507af3c381f0893..12265aff7099a60ca0f6020d7839ec49561f4d3e 100644 (file)
--- a/net/bridge/Kconfig
+++ b/net/bridge/Kconfig
@@ -4,6 +4,7 @@
 
 config BRIDGE
        tristate "802.1d Ethernet Bridging"
+       select LLC
        ---help---
          If you say Y here, then your Linux box will be able to act as an
          Ethernet bridge, which means that the different Ethernet segments it

diff --git a/net/bridge/br.c b/net/bridge/br.c
index 188cc1ac49eb76ab2c5c806cbb03a406a3c59bf7..22d806cf40caf86d694eb05f2794bc1454c5ee19 100644 (file)
--- a/net/bridge/br.c
+++ b/net/bridge/br.c
@@ -19,13 +19,23 @@
 #include <linux/netdevice.h>
 #include <linux/etherdevice.h>
 #include <linux/init.h>
+#include <linux/llc.h>
+#include <net/llc.h>
 
 #include "br_private.h"
 
 int (*br_should_route_hook) (struct sk_buff **pskb) = NULL;
 
+static struct llc_sap *br_stp_sap;
+
 static int __init br_init(void)
 {
+       br_stp_sap = llc_sap_open(LLC_SAP_BSPAN, br_stp_rcv);
+       if (!br_stp_sap) {
+               printk(KERN_ERR "bridge: can't register sap for STP\n");
+               return -EBUSY;
+       }
+
        br_fdb_init();
 
 #ifdef CONFIG_BRIDGE_NETFILTER
@@ -45,6 +55,8 @@ static int __init br_init(void)
 
 static void __exit br_deinit(void)
 {
+       llc_sap_close(br_stp_sap);
+
 #ifdef CONFIG_BRIDGE_NETFILTER
        br_netfilter_fini();
 #endif

diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c
index 6e223723cc8d66887a8f002c20bd68db2c7ad529..dad4094897530c3ffb97d1ba998b9acfd7ac7891 100644 (file)
--- a/net/bridge/br_input.c
+++ b/net/bridge/br_input.c
@@ -94,6 +94,25 @@ drop:
        goto out;
 }
 
+/* note: already called with rcu_read_lock (preempt_disabled) */
+static int br_handle_local_finish(struct sk_buff *skb)
+{
+       struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
+
+       if (p && p->state != BR_STATE_DISABLED)
+               br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
+
+       return 0;        /* process further */
+}
+
+/* Does address match the link local multicast address.
+ * 01:80:c2:00:00:0X
+ */
+static inline int is_link_local(const unsigned char *dest)
+{
+       return memcmp(dest, bridge_ula, 5) == 0 && (dest[5] & 0xf0) == 0;
+}
+
 /*
  * Called via br_handle_frame_hook.
  * Return 0 if *pskb should be processed furthur
@@ -111,15 +130,10 @@ int br_handle_frame(struct net_bridge_port *p, struct sk_buff **pskb)
        if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
                goto err;
 
-       if (p->br->stp_enabled &&
-           !memcmp(dest, bridge_ula, 5) &&
-           !(dest[5] & 0xF0)) {
-               if (!dest[5]) {
-                       NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 
-                               NULL, br_stp_handle_bpdu);
-                       return 1;
-               }
-               goto err;
+       if (unlikely(is_link_local(dest))) {
+               skb->pkt_type = PACKET_HOST;
+               return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
+                              NULL, br_handle_local_finish) != 0;
        }
 
        if (p->state == BR_STATE_FORWARDING || p->state == BR_STATE_LEARNING) {

diff --git a/net/bridge/br_private.h b/net/bridge/br_private.h
index 8f10e09f251bd9169dfc347413de37e83d28c16a..3bc9ad4834734bf9b4dedb5a370787899dc9d7b8 100644 (file)
--- a/net/bridge/br_private.h
+++ b/net/bridge/br_private.h
@@ -217,7 +217,8 @@ extern void br_stp_set_path_cost(struct net_bridge_port *p,
 extern ssize_t br_show_bridge_id(char *buf, const struct bridge_id *id);
 
 /* br_stp_bpdu.c */
-extern int br_stp_handle_bpdu(struct sk_buff *skb);
+extern int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
+                     struct packet_type *pt, struct net_device *orig_dev);
 
 /* br_stp_timer.c */
 extern void br_stp_timer_init(struct net_bridge *br);

diff --git a/net/bridge/br_stp_bpdu.c b/net/bridge/br_stp_bpdu.c
index c3da01cc6a6f6a3c493d70680fb30e648d6c1115..a99e90e20952e789e5355ffb06c50131c0e3e527 100644 (file)
--- a/net/bridge/br_stp_bpdu.c
+++ b/net/bridge/br_stp_bpdu.c
@@ -15,6 +15,9 @@
 
 #include <linux/kernel.h>
 #include <linux/netfilter_bridge.h>
+#include <linux/etherdevice.h>
+#include <linux/llc.h>
+#include <net/llc_pdu.h>
 
 #include "br_private.h"
 #include "br_private_stp.h"
@@ -130,42 +133,54 @@ void br_send_tcn_bpdu(struct net_bridge_port *p)
        br_send_bpdu(p, buf, 7);
 }
 
-static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
-
-/* NO locks, but rcu_read_lock (preempt_disabled)  */
-int br_stp_handle_bpdu(struct sk_buff *skb)
+/*
+ * Called from llc.
+ *
+ * NO locks, but rcu_read_lock (preempt_disabled)
+ */
+int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
+              struct packet_type *pt, struct net_device *orig_dev)
 {
-       struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
+       const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
+       const unsigned char *dest = eth_hdr(skb)->h_dest;
+       struct net_bridge_port *p = rcu_dereference(dev->br_port);
        struct net_bridge *br;
-       unsigned char *buf;
+       const unsigned char *buf;
 
        if (!p)
                goto err;
 
-       br = p->br;
-       spin_lock(&br->lock);
+       if (pdu->ssap != LLC_SAP_BSPAN
+           || pdu->dsap != LLC_SAP_BSPAN
+           || pdu->ctrl_1 != LLC_PDU_TYPE_U)
+               goto err;
 
-       if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
-               goto out;
+       if (!pskb_may_pull(skb, 4))
+               goto err;
+
+       /* compare of protocol id and version */
+       buf = skb->data;
+       if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
+               goto err;
 
-       /* insert into forwarding database after filtering to avoid spoofing */
-       br_fdb_update(br, p, eth_hdr(skb)->h_source);
+       br = p->br;
+       spin_lock(&br->lock);
 
-       if (!br->stp_enabled)
+       if (p->state == BR_STATE_DISABLED
+           || !br->stp_enabled
+           || !(br->dev->flags & IFF_UP))
                goto out;
 
-       /* need at least the 802 and STP headers */
-       if (!pskb_may_pull(skb, sizeof(header)+1) ||
-           memcmp(skb->data, header, sizeof(header)))
+       if (compare_ether_addr(dest, bridge_ula) != 0)
                goto out;
 
-       buf = skb_pull(skb, sizeof(header));
+       buf = skb_pull(skb, 3);
 
        if (buf[0] == BPDU_TYPE_CONFIG) {
                struct br_config_bpdu bpdu;
 
                if (!pskb_may_pull(skb, 32))
-                   goto out;
+                       goto out;
 
                buf = skb->data;
                bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;