[linux-block.git] / net / bridge / br_stp_bpdu.c

/*
 *	Spanning tree protocol; BPDU handling
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 *
 *	$Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
 *
 *	This program is free software; you can redistribute it and/or
 *	modify it under the terms of the GNU General Public License
 *	as published by the Free Software Foundation; either version
 *	2 of the License, or (at your option) any later version.
 */

#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>

#include "br_private.h"
#include "br_private_stp.h"

#define STP_HZ		256

static void br_send_bpdu(struct net_bridge_port *p, unsigned char *data, int length)
{
	struct net_device *dev;
	struct sk_buff *skb;
	int size;

	if (!p->br->stp_enabled)
		return;

	size = length + 2*ETH_ALEN + 2;
	if (size < 60)
		size = 60;

	dev = p->dev;

	if ((skb = dev_alloc_skb(size)) == NULL) {
		printk(KERN_INFO "br: memory squeeze!\n");
		return;
	}

	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+ETH_ALEN, dev->dev_addr, ETH_ALEN);
	skb->mac.raw[2*ETH_ALEN] = 0;
	skb->mac.raw[2*ETH_ALEN+1] = length;
	skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
	memcpy(skb->nh.raw, data, length);
	memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);

	NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
		dev_queue_xmit);
}

static inline void br_set_ticks(unsigned char *dest, int j)
{
	unsigned long ticks = (STP_HZ * j)/ HZ;

	*((__be16 *) dest) = htons(ticks);
}

static inline int br_get_ticks(const unsigned char *src)
{
	unsigned long ticks = ntohs(*(__be16 *)src);

	return (ticks * HZ + STP_HZ - 1) / STP_HZ;
}

/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
	unsigned char buf[38];

	buf[0] = 0x42;
	buf[1] = 0x42;
	buf[2] = 0x03;
	buf[3] = 0;
	buf[4] = 0;
	buf[5] = 0;
	buf[6] = BPDU_TYPE_CONFIG;
	buf[7] = (bpdu->topology_change ? 0x01 : 0) |
		(bpdu->topology_change_ack ? 0x80 : 0);
	buf[8] = bpdu->root.prio[0];
	buf[9] = bpdu->root.prio[1];
	buf[10] = bpdu->root.addr[0];
	buf[11] = bpdu->root.addr[1];
	buf[12] = bpdu->root.addr[2];
	buf[13] = bpdu->root.addr[3];
	buf[14] = bpdu->root.addr[4];
	buf[15] = bpdu->root.addr[5];
	buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
	buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
	buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
	buf[19] = bpdu->root_path_cost & 0xFF;
	buf[20] = bpdu->bridge_id.prio[0];
	buf[21] = bpdu->bridge_id.prio[1];
	buf[22] = bpdu->bridge_id.addr[0];
	buf[23] = bpdu->bridge_id.addr[1];
	buf[24] = bpdu->bridge_id.addr[2];
	buf[25] = bpdu->bridge_id.addr[3];
	buf[26] = bpdu->bridge_id.addr[4];
	buf[27] = bpdu->bridge_id.addr[5];
	buf[28] = (bpdu->port_id >> 8) & 0xFF;
	buf[29] = bpdu->port_id & 0xFF;

	br_set_ticks(buf+30, bpdu->message_age);
	br_set_ticks(buf+32, bpdu->max_age);
	br_set_ticks(buf+34, bpdu->hello_time);
	br_set_ticks(buf+36, bpdu->forward_delay);

	br_send_bpdu(p, buf, 38);
}

/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
	unsigned char buf[7];

	buf[0] = 0x42;
	buf[1] = 0x42;
	buf[2] = 0x03;
	buf[3] = 0;
	buf[4] = 0;
	buf[5] = 0;
	buf[6] = BPDU_TYPE_TCN;
	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)
{
	struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
	struct net_bridge *br;
	unsigned char *buf;

	if (!p)
		goto err;

	br = p->br;
	spin_lock(&br->lock);

	if (p->state == BR_STATE_DISABLED || !(br->dev->flags & IFF_UP))
		goto out;

	/* insert into forwarding database after filtering to avoid spoofing */
	br_fdb_update(br, p, eth_hdr(skb)->h_source);

	if (!br->stp_enabled)
		goto out;

	/* need at least the 802 and STP headers */
	if (!pskb_may_pull(skb, sizeof(header)+1) ||
	    memcmp(skb->data, header, sizeof(header)))
		goto out;

	buf = skb_pull(skb, sizeof(header));

	if (buf[0] == BPDU_TYPE_CONFIG) {
		struct br_config_bpdu bpdu;

		if (!pskb_may_pull(skb, 32))
		    goto out;

		buf = skb->data;
		bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
		bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;

		bpdu.root.prio[0] = buf[2];
		bpdu.root.prio[1] = buf[3];
		bpdu.root.addr[0] = buf[4];
		bpdu.root.addr[1] = buf[5];
		bpdu.root.addr[2] = buf[6];
		bpdu.root.addr[3] = buf[7];
		bpdu.root.addr[4] = buf[8];
		bpdu.root.addr[5] = buf[9];
		bpdu.root_path_cost =
			(buf[10] << 24) |
			(buf[11] << 16) |
			(buf[12] << 8) |
			buf[13];
		bpdu.bridge_id.prio[0] = buf[14];
		bpdu.bridge_id.prio[1] = buf[15];
		bpdu.bridge_id.addr[0] = buf[16];
		bpdu.bridge_id.addr[1] = buf[17];
		bpdu.bridge_id.addr[2] = buf[18];
		bpdu.bridge_id.addr[3] = buf[19];
		bpdu.bridge_id.addr[4] = buf[20];
		bpdu.bridge_id.addr[5] = buf[21];
		bpdu.port_id = (buf[22] << 8) | buf[23];

		bpdu.message_age = br_get_ticks(buf+24);
		bpdu.max_age = br_get_ticks(buf+26);
		bpdu.hello_time = br_get_ticks(buf+28);
		bpdu.forward_delay = br_get_ticks(buf+30);

		br_received_config_bpdu(p, &bpdu);
	}

	else if (buf[0] == BPDU_TYPE_TCN) {
		br_received_tcn_bpdu(p);
	}
 out:
	spin_unlock(&br->lock);
 err:
	kfree_skb(skb);
	return 0;
}
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Spanning tree protocol; BPDU handling
	3	* Linux ethernet bridge
	4	*
	5	* Authors:
	6	* Lennert Buytenhek <buytenh@gnu.org>
	7	*
	8	* $Id: br_stp_bpdu.c,v 1.3 2001/11/10 02:35:25 davem Exp $
	9	*
	10	* This program is free software; you can redistribute it and/or
	11	* modify it under the terms of the GNU General Public License
	12	* as published by the Free Software Foundation; either version
	13	* 2 of the License, or (at your option) any later version.
	14	*/
	15
	16	#include <linux/kernel.h>
	17	#include <linux/netfilter_bridge.h>
	18
	19	#include "br_private.h"
	20	#include "br_private_stp.h"
	21
18fdb2b2	22	#define STP_HZ 256
1da177e4 LT	23
	24	static void br_send_bpdu(struct net_bridge_port p, unsigned char data, int length)
	25	{
	26	struct net_device *dev;
	27	struct sk_buff *skb;
	28	int size;
	29
	30	if (!p->br->stp_enabled)
	31	return;
	32
	33	size = length + 2*ETH_ALEN + 2;
	34	if (size < 60)
	35	size = 60;
	36
	37	dev = p->dev;
	38
	39	if ((skb = dev_alloc_skb(size)) == NULL) {
	40	printk(KERN_INFO "br: memory squeeze!\n");
	41	return;
	42	}
	43
	44	skb->dev = dev;
	45	skb->protocol = htons(ETH_P_802_2);
	46	skb->mac.raw = skb_put(skb, size);
	47	memcpy(skb->mac.raw, bridge_ula, ETH_ALEN);
	48	memcpy(skb->mac.raw+ETH_ALEN, dev->dev_addr, ETH_ALEN);
	49	skb->mac.raw[2*ETH_ALEN] = 0;
	50	skb->mac.raw[2*ETH_ALEN+1] = length;
	51	skb->nh.raw = skb->mac.raw + 2*ETH_ALEN + 2;
	52	memcpy(skb->nh.raw, data, length);
	53	memset(skb->nh.raw + length, 0xa5, size - length - 2*ETH_ALEN - 2);
	54
	55	NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
	56	dev_queue_xmit);
	57	}
	58
18fdb2b2	59	static inline void br_set_ticks(unsigned char *dest, int j)
1da177e4	60	{
18fdb2b2	61	unsigned long ticks = (STP_HZ * j)/ HZ;
1da177e4	62
18fdb2b2	63	((__be16 ) dest) = htons(ticks);
1da177e4 LT	64	}
1da177e4 LT	65
18fdb2b2	66	static inline int br_get_ticks(const unsigned char *src)
1da177e4	67	{
18fdb2b2 SH	68	unsigned long ticks = ntohs((__be16 )src);
	69
	70	return (ticks * HZ + STP_HZ - 1) / STP_HZ;
1da177e4 LT	71	}
	72
	73	/* called under bridge lock */
	74	void br_send_config_bpdu(struct net_bridge_port p, struct br_config_bpdu bpdu)
	75	{
	76	unsigned char buf[38];
	77
	78	buf[0] = 0x42;
	79	buf[1] = 0x42;
	80	buf[2] = 0x03;
	81	buf[3] = 0;
	82	buf[4] = 0;
	83	buf[5] = 0;
	84	buf[6] = BPDU_TYPE_CONFIG;
	85	buf[7] = (bpdu->topology_change ? 0x01 : 0) \|
	86	(bpdu->topology_change_ack ? 0x80 : 0);
	87	buf[8] = bpdu->root.prio[0];
	88	buf[9] = bpdu->root.prio[1];
	89	buf[10] = bpdu->root.addr[0];
	90	buf[11] = bpdu->root.addr[1];
	91	buf[12] = bpdu->root.addr[2];
	92	buf[13] = bpdu->root.addr[3];
	93	buf[14] = bpdu->root.addr[4];
	94	buf[15] = bpdu->root.addr[5];
	95	buf[16] = (bpdu->root_path_cost >> 24) & 0xFF;
	96	buf[17] = (bpdu->root_path_cost >> 16) & 0xFF;
	97	buf[18] = (bpdu->root_path_cost >> 8) & 0xFF;
	98	buf[19] = bpdu->root_path_cost & 0xFF;
	99	buf[20] = bpdu->bridge_id.prio[0];
	100	buf[21] = bpdu->bridge_id.prio[1];
	101	buf[22] = bpdu->bridge_id.addr[0];
	102	buf[23] = bpdu->bridge_id.addr[1];
	103	buf[24] = bpdu->bridge_id.addr[2];
	104	buf[25] = bpdu->bridge_id.addr[3];
	105	buf[26] = bpdu->bridge_id.addr[4];
	106	buf[27] = bpdu->bridge_id.addr[5];
	107	buf[28] = (bpdu->port_id >> 8) & 0xFF;
	108	buf[29] = bpdu->port_id & 0xFF;
	109
	110	br_set_ticks(buf+30, bpdu->message_age);
	111	br_set_ticks(buf+32, bpdu->max_age);
	112	br_set_ticks(buf+34, bpdu->hello_time);
	113	br_set_ticks(buf+36, bpdu->forward_delay);
	114
	115	br_send_bpdu(p, buf, 38);
	116	}
	117
	118	/* called under bridge lock */
	119	void br_send_tcn_bpdu(struct net_bridge_port *p)
	120	{
	121	unsigned char buf[7];
	122
	123	buf[0] = 0x42;
	124	buf[1] = 0x42;
	125	buf[2] = 0x03;
	126	buf[3] = 0;
	127	buf[4] = 0;
	128	buf[5] = 0;
	129	buf[6] = BPDU_TYPE_TCN;
	130	br_send_bpdu(p, buf, 7);
	131	}
	132
	133	static const unsigned char header[6] = {0x42, 0x42, 0x03, 0x00, 0x00, 0x00};
	134
b3f1be4b	135	/* NO locks, but rcu_read_lock (preempt_disabled) */
1da177e4 LT	136	int br_stp_handle_bpdu(struct sk_buff *skb)
1da177e4 LT	137	{
b3f1be4b SH	138	struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
b3f1be4b SH	139	struct net_bridge *br;
1da177e4 LT	140	unsigned char *buf;
1da177e4 LT	141
b3f1be4b SH	142	if (!p)
	143	goto err;
	144
	145	br = p->br;
	146	spin_lock(&br->lock);
	147
	148	if (p->state == BR_STATE_DISABLED \|\| !(br->dev->flags & IFF_UP))
	149	goto out;
	150
85967bb4	151	/* insert into forwarding database after filtering to avoid spoofing */
b3f1be4b SH	152	br_fdb_update(br, p, eth_hdr(skb)->h_source);
	153
	154	if (!br->stp_enabled)
	155	goto out;
85967bb4	156
1da177e4 LT	157	/* need at least the 802 and STP headers */
	158	if (!pskb_may_pull(skb, sizeof(header)+1) \|\|
	159	memcmp(skb->data, header, sizeof(header)))
b3f1be4b	160	goto out;
1da177e4 LT	161
	162	buf = skb_pull(skb, sizeof(header));
	163
1da177e4 LT	164	if (buf[0] == BPDU_TYPE_CONFIG) {
	165	struct br_config_bpdu bpdu;
	166
	167	if (!pskb_may_pull(skb, 32))
	168	goto out;
	169
	170	buf = skb->data;
	171	bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
	172	bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
	173
	174	bpdu.root.prio[0] = buf[2];
	175	bpdu.root.prio[1] = buf[3];
	176	bpdu.root.addr[0] = buf[4];
	177	bpdu.root.addr[1] = buf[5];
	178	bpdu.root.addr[2] = buf[6];
	179	bpdu.root.addr[3] = buf[7];
	180	bpdu.root.addr[4] = buf[8];
	181	bpdu.root.addr[5] = buf[9];
	182	bpdu.root_path_cost =
	183	(buf[10] << 24) \|
	184	(buf[11] << 16) \|
	185	(buf[12] << 8) \|
	186	buf[13];
	187	bpdu.bridge_id.prio[0] = buf[14];
	188	bpdu.bridge_id.prio[1] = buf[15];
	189	bpdu.bridge_id.addr[0] = buf[16];
	190	bpdu.bridge_id.addr[1] = buf[17];
	191	bpdu.bridge_id.addr[2] = buf[18];
	192	bpdu.bridge_id.addr[3] = buf[19];
	193	bpdu.bridge_id.addr[4] = buf[20];
	194	bpdu.bridge_id.addr[5] = buf[21];
	195	bpdu.port_id = (buf[22] << 8) \| buf[23];
	196
	197	bpdu.message_age = br_get_ticks(buf+24);
	198	bpdu.max_age = br_get_ticks(buf+26);
	199	bpdu.hello_time = br_get_ticks(buf+28);
	200	bpdu.forward_delay = br_get_ticks(buf+30);
	201
	202	br_received_config_bpdu(p, &bpdu);
	203	}
	204
	205	else if (buf[0] == BPDU_TYPE_TCN) {
	206	br_received_tcn_bpdu(p);
	207	}
	208	out:
b3f1be4b	209	spin_unlock(&br->lock);
1da177e4 LT	210	err:
	211	kfree_skb(skb);
	212	return 0;
	213	}