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

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Spanning tree protocol; BPDU handling
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<[email protected]>
 */

#include <linux/kernel.h>
#include <linux/netfilter_bridge.h>
#include <linux/etherdevice.h>
#include <linux/llc.h>
#include <linux/slab.h>
#include <linux/pkt_sched.h>
#include <net/net_namespace.h>
#include <net/llc.h>
#include <net/llc_pdu.h>
#include <net/stp.h>
#include <asm/unaligned.h>

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

#define STP_HZ		256

#define LLC_RESERVE sizeof(struct llc_pdu_un)

static int br_send_bpdu_finish(struct net *net, struct sock *sk,
			       struct sk_buff *skb)
{
	return dev_queue_xmit(skb);
}

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

	skb = dev_alloc_skb(length+LLC_RESERVE);
	if (!skb)
		return;

	skb->dev = p->dev;
	skb->protocol = htons(ETH_P_802_2);
	skb->priority = TC_PRIO_CONTROL;

	skb_reserve(skb, LLC_RESERVE);
	__skb_put_data(skb, data, length);

	llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
			    LLC_SAP_BSPAN, LLC_PDU_CMD);
	llc_pdu_init_as_ui_cmd(skb);

	llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);

	skb_reset_mac_header(skb);

	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
		dev_net(p->dev), NULL, skb, NULL, skb->dev,
		br_send_bpdu_finish);
}

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

	put_unaligned_be16(ticks, dest);
}

static inline int br_get_ticks(const unsigned char *src)
{
	unsigned long ticks = get_unaligned_be16(src);

	return DIV_ROUND_UP(ticks * HZ, STP_HZ);
}

/* called under bridge lock */
void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
{
	unsigned char buf[35];

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

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

	br_set_ticks(buf+27, bpdu->message_age);
	br_set_ticks(buf+29, bpdu->max_age);
	br_set_ticks(buf+31, bpdu->hello_time);
	br_set_ticks(buf+33, bpdu->forward_delay);

	br_send_bpdu(p, buf, 35);

	p->stp_xstats.tx_bpdu++;
}

/* called under bridge lock */
void br_send_tcn_bpdu(struct net_bridge_port *p)
{
	unsigned char buf[4];

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

	buf[0] = 0;
	buf[1] = 0;
	buf[2] = 0;
	buf[3] = BPDU_TYPE_TCN;
	br_send_bpdu(p, buf, 4);

	p->stp_xstats.tx_tcn++;
}

/*
 * Called from llc.
 *
 * NO locks, but rcu_read_lock
 */
void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
		struct net_device *dev)
{
	struct net_bridge_port *p;
	struct net_bridge *br;
	const unsigned char *buf;

	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;

	p = br_port_get_check_rcu(dev);
	if (!p)
		goto err;

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

	if (br->stp_enabled != BR_KERNEL_STP)
		goto out;

	if (!(br->dev->flags & IFF_UP))
		goto out;

	if (p->state == BR_STATE_DISABLED)
		goto out;

	if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
		goto out;

	if (p->flags & BR_BPDU_GUARD) {
		br_notice(br, "BPDU received on blocked port %u(%s)\n",
			  (unsigned int) p->port_no, p->dev->name);
		br_stp_disable_port(p);
		goto out;
	}

	buf = skb_pull(skb, 3);

	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);

		if (bpdu.message_age > bpdu.max_age) {
			if (net_ratelimit())
				br_notice(p->br,
					  "port %u config from %pM"
					  " (message_age %ul > max_age %ul)\n",
					  p->port_no,
					  eth_hdr(skb)->h_source,
					  bpdu.message_age, bpdu.max_age);
			goto out;
		}

		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);
}
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
1da177e4 LT	2	/*
	3	* Spanning tree protocol; BPDU handling
	4	* Linux ethernet bridge
	5	*
	6	* Authors:
	7	* Lennert Buytenhek <[email protected]>
1da177e4 LT	8	*/
	9
	10	#include <linux/kernel.h>
	11	#include <linux/netfilter_bridge.h>
cf0f02d0 SH	12	#include <linux/etherdevice.h>
cf0f02d0 SH	13	#include <linux/llc.h>
5a0e3ad6	14	#include <linux/slab.h>
547b4e71	15	#include <linux/pkt_sched.h>
e730c155	16	#include <net/net_namespace.h>
12ac84c4	17	#include <net/llc.h>
cf0f02d0	18	#include <net/llc_pdu.h>
7c85fbf0	19	#include <net/stp.h>
4dc6d9cc	20	#include <asm/unaligned.h>
1da177e4 LT	21
	22	#include "br_private.h"
	23	#include "br_private_stp.h"
	24
18fdb2b2	25	#define STP_HZ 256
1da177e4	26
12ac84c4 SH	27	#define LLC_RESERVE sizeof(struct llc_pdu_un)
12ac84c4 SH	28
0c4b51f0 EB	29	static int br_send_bpdu_finish(struct net net, struct sock sk,
0c4b51f0 EB	30	struct sk_buff *skb)
1f19c578 EB	31	{
	32	return dev_queue_xmit(skb);
	33	}
	34
12ac84c4	35	static void br_send_bpdu(struct net_bridge_port *p,
9d6f229f	36	const unsigned char *data, int length)
1da177e4	37	{
1da177e4	38	struct sk_buff *skb;
1da177e4	39
12ac84c4 SH	40	skb = dev_alloc_skb(length+LLC_RESERVE);
12ac84c4 SH	41	if (!skb)
1da177e4	42	return;
1da177e4	43
12ac84c4	44	skb->dev = p->dev;
1da177e4	45	skb->protocol = htons(ETH_P_802_2);
547b4e71	46	skb->priority = TC_PRIO_CONTROL;
12ac84c4 SH	47
12ac84c4 SH	48	skb_reserve(skb, LLC_RESERVE);
de77b966	49	__skb_put_data(skb, data, length);
12ac84c4 SH	50
	51	llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
	52	LLC_SAP_BSPAN, LLC_PDU_CMD);
	53	llc_pdu_init_as_ui_cmd(skb);
	54
	55	llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
1da177e4	56
e6f26129 FW	57	skb_reset_mac_header(skb);
e6f26129 FW	58
29a26a56 EB	59	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
29a26a56 EB	60	dev_net(p->dev), NULL, skb, NULL, skb->dev,
1f19c578	61	br_send_bpdu_finish);
1da177e4 LT	62	}
1da177e4 LT	63
18fdb2b2	64	static inline void br_set_ticks(unsigned char *dest, int j)
1da177e4	65	{
18fdb2b2	66	unsigned long ticks = (STP_HZ * j)/ HZ;
1da177e4	67
d3e2ce3b	68	put_unaligned_be16(ticks, dest);
1da177e4 LT	69	}
1da177e4 LT	70
18fdb2b2	71	static inline int br_get_ticks(const unsigned char *src)
1da177e4	72	{
d3e2ce3b	73	unsigned long ticks = get_unaligned_be16(src);
18fdb2b2	74
172589cc	75	return DIV_ROUND_UP(ticks * HZ, STP_HZ);
1da177e4 LT	76	}
	77
	78	/* called under bridge lock */
	79	void br_send_config_bpdu(struct net_bridge_port p, struct br_config_bpdu bpdu)
	80	{
12ac84c4 SH	81	unsigned char buf[35];
12ac84c4 SH	82
9cde0708 SH	83	if (p->br->stp_enabled != BR_KERNEL_STP)
	84	return;
	85
12ac84c4 SH	86	buf[0] = 0;
	87	buf[1] = 0;
	88	buf[2] = 0;
	89	buf[3] = BPDU_TYPE_CONFIG;
	90	buf[4] = (bpdu->topology_change ? 0x01 : 0) \|
1da177e4	91	(bpdu->topology_change_ack ? 0x80 : 0);
12ac84c4 SH	92	buf[5] = bpdu->root.prio[0];
	93	buf[6] = bpdu->root.prio[1];
	94	buf[7] = bpdu->root.addr[0];
	95	buf[8] = bpdu->root.addr[1];
	96	buf[9] = bpdu->root.addr[2];
	97	buf[10] = bpdu->root.addr[3];
	98	buf[11] = bpdu->root.addr[4];
	99	buf[12] = bpdu->root.addr[5];
	100	buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
	101	buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
	102	buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
	103	buf[16] = bpdu->root_path_cost & 0xFF;
	104	buf[17] = bpdu->bridge_id.prio[0];
	105	buf[18] = bpdu->bridge_id.prio[1];
	106	buf[19] = bpdu->bridge_id.addr[0];
	107	buf[20] = bpdu->bridge_id.addr[1];
	108	buf[21] = bpdu->bridge_id.addr[2];
	109	buf[22] = bpdu->bridge_id.addr[3];
	110	buf[23] = bpdu->bridge_id.addr[4];
	111	buf[24] = bpdu->bridge_id.addr[5];
	112	buf[25] = (bpdu->port_id >> 8) & 0xFF;
	113	buf[26] = bpdu->port_id & 0xFF;
	114
	115	br_set_ticks(buf+27, bpdu->message_age);
	116	br_set_ticks(buf+29, bpdu->max_age);
	117	br_set_ticks(buf+31, bpdu->hello_time);
	118	br_set_ticks(buf+33, bpdu->forward_delay);
	119
	120	br_send_bpdu(p, buf, 35);
de179966 VD	121
de179966 VD	122	p->stp_xstats.tx_bpdu++;
1da177e4 LT	123	}
	124
	125	/* called under bridge lock */
	126	void br_send_tcn_bpdu(struct net_bridge_port *p)
	127	{
12ac84c4 SH	128	unsigned char buf[4];
12ac84c4 SH	129
9cde0708 SH	130	if (p->br->stp_enabled != BR_KERNEL_STP)
	131	return;
	132
12ac84c4 SH	133	buf[0] = 0;
	134	buf[1] = 0;
	135	buf[2] = 0;
	136	buf[3] = BPDU_TYPE_TCN;
485c2967	137	br_send_bpdu(p, buf, 4);
de179966 VD	138
de179966 VD	139	p->stp_xstats.tx_tcn++;
1da177e4 LT	140	}
1da177e4 LT	141
cf0f02d0 SH	142	/*
	143	* Called from llc.
	144	*
eeaf61d8	145	* NO locks, but rcu_read_lock
cf0f02d0	146	*/
7c85fbf0 PM	147	void br_stp_rcv(const struct stp_proto proto, struct sk_buff skb,
7c85fbf0 PM	148	struct net_device *dev)
1da177e4	149	{
f350a0a8	150	struct net_bridge_port *p;
b3f1be4b	151	struct net_bridge *br;
cf0f02d0	152	const unsigned char *buf;
1da177e4	153
cf0f02d0 SH	154	if (!pskb_may_pull(skb, 4))
	155	goto err;
	156
	157	/* compare of protocol id and version */
	158	buf = skb->data;
	159	if (buf[0] != 0 \|\| buf[1] != 0 \|\| buf[2] != 0)
	160	goto err;
b3f1be4b	161
859828c0	162	p = br_port_get_check_rcu(dev);
b5ed54e9	163	if (!p)
	164	goto err;
	165
cf0f02d0 SH	166	br = p->br;
cf0f02d0 SH	167	spin_lock(&br->lock);
b3f1be4b	168
9cde0708 SH	169	if (br->stp_enabled != BR_KERNEL_STP)
	170	goto out;
	171
	172	if (!(br->dev->flags & IFF_UP))
	173	goto out;
	174
	175	if (p->state == BR_STATE_DISABLED)
b3f1be4b	176	goto out;
85967bb4	177
2446a68a	178	if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
b3f1be4b	179	goto out;
1da177e4	180
a2e01a65	181	if (p->flags & BR_BPDU_GUARD) {
	182	br_notice(br, "BPDU received on blocked port %u(%s)\n",
	183	(unsigned int) p->port_no, p->dev->name);
	184	br_stp_disable_port(p);
	185	goto out;
	186	}
	187
cf0f02d0	188	buf = skb_pull(skb, 3);
1da177e4	189
1da177e4 LT	190	if (buf[0] == BPDU_TYPE_CONFIG) {
	191	struct br_config_bpdu bpdu;
	192
	193	if (!pskb_may_pull(skb, 32))
cf0f02d0	194	goto out;
1da177e4 LT	195
	196	buf = skb->data;
	197	bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
	198	bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
	199
	200	bpdu.root.prio[0] = buf[2];
	201	bpdu.root.prio[1] = buf[3];
	202	bpdu.root.addr[0] = buf[4];
	203	bpdu.root.addr[1] = buf[5];
	204	bpdu.root.addr[2] = buf[6];
	205	bpdu.root.addr[3] = buf[7];
	206	bpdu.root.addr[4] = buf[8];
	207	bpdu.root.addr[5] = buf[9];
	208	bpdu.root_path_cost =
	209	(buf[10] << 24) \|
	210	(buf[11] << 16) \|
	211	(buf[12] << 8) \|
	212	buf[13];
	213	bpdu.bridge_id.prio[0] = buf[14];
	214	bpdu.bridge_id.prio[1] = buf[15];
	215	bpdu.bridge_id.addr[0] = buf[16];
	216	bpdu.bridge_id.addr[1] = buf[17];
	217	bpdu.bridge_id.addr[2] = buf[18];
	218	bpdu.bridge_id.addr[3] = buf[19];
	219	bpdu.bridge_id.addr[4] = buf[20];
	220	bpdu.bridge_id.addr[5] = buf[21];
	221	bpdu.port_id = (buf[22] << 8) \| buf[23];
	222
	223	bpdu.message_age = br_get_ticks(buf+24);
	224	bpdu.max_age = br_get_ticks(buf+26);
	225	bpdu.hello_time = br_get_ticks(buf+28);
	226	bpdu.forward_delay = br_get_ticks(buf+30);
	227
0652cac2	228	if (bpdu.message_age > bpdu.max_age) {
	229	if (net_ratelimit())
	230	br_notice(p->br,
	231	"port %u config from %pM"
	232	" (message_age %ul > max_age %ul)\n",
	233	p->port_no,
	234	eth_hdr(skb)->h_source,
	235	bpdu.message_age, bpdu.max_age);
	236	goto out;
	237	}
	238
1da177e4	239	br_received_config_bpdu(p, &bpdu);
160d73b8	240	} else if (buf[0] == BPDU_TYPE_TCN) {
1da177e4 LT	241	br_received_tcn_bpdu(p);
	242	}
	243	out:
b3f1be4b	244	spin_unlock(&br->lock);
1da177e4 LT	245	err:
1da177e4 LT	246	kfree_skb(skb);
1da177e4	247	}