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/net/bridge/br_stp_bpdu.c

http://github.com/mirrors/linux
C | 247 lines | 186 code | 45 blank | 16 comment | 28 complexity | a86563c5e08139eb5fd9f32916ad20a2 MD5 | raw file
  1// SPDX-License-Identifier: GPL-2.0-or-later
  2/*
  3 *	Spanning tree protocol; BPDU handling
  4 *	Linux ethernet bridge
  5 *
  6 *	Authors:
  7 *	Lennert Buytenhek		<buytenh@gnu.org>
  8 */
  9
 10#include <linux/kernel.h>
 11#include <linux/netfilter_bridge.h>
 12#include <linux/etherdevice.h>
 13#include <linux/llc.h>
 14#include <linux/slab.h>
 15#include <linux/pkt_sched.h>
 16#include <net/net_namespace.h>
 17#include <net/llc.h>
 18#include <net/llc_pdu.h>
 19#include <net/stp.h>
 20#include <asm/unaligned.h>
 21
 22#include "br_private.h"
 23#include "br_private_stp.h"
 24
 25#define STP_HZ		256
 26
 27#define LLC_RESERVE sizeof(struct llc_pdu_un)
 28
 29static int br_send_bpdu_finish(struct net *net, struct sock *sk,
 30			       struct sk_buff *skb)
 31{
 32	return dev_queue_xmit(skb);
 33}
 34
 35static void br_send_bpdu(struct net_bridge_port *p,
 36			 const unsigned char *data, int length)
 37{
 38	struct sk_buff *skb;
 39
 40	skb = dev_alloc_skb(length+LLC_RESERVE);
 41	if (!skb)
 42		return;
 43
 44	skb->dev = p->dev;
 45	skb->protocol = htons(ETH_P_802_2);
 46	skb->priority = TC_PRIO_CONTROL;
 47
 48	skb_reserve(skb, LLC_RESERVE);
 49	__skb_put_data(skb, data, length);
 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);
 56
 57	skb_reset_mac_header(skb);
 58
 59	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
 60		dev_net(p->dev), NULL, skb, NULL, skb->dev,
 61		br_send_bpdu_finish);
 62}
 63
 64static inline void br_set_ticks(unsigned char *dest, int j)
 65{
 66	unsigned long ticks = (STP_HZ * j)/ HZ;
 67
 68	put_unaligned_be16(ticks, dest);
 69}
 70
 71static inline int br_get_ticks(const unsigned char *src)
 72{
 73	unsigned long ticks = get_unaligned_be16(src);
 74
 75	return DIV_ROUND_UP(ticks * HZ, STP_HZ);
 76}
 77
 78/* called under bridge lock */
 79void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
 80{
 81	unsigned char buf[35];
 82
 83	if (p->br->stp_enabled != BR_KERNEL_STP)
 84		return;
 85
 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) |
 91		(bpdu->topology_change_ack ? 0x80 : 0);
 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);
121
122	p->stp_xstats.tx_bpdu++;
123}
124
125/* called under bridge lock */
126void br_send_tcn_bpdu(struct net_bridge_port *p)
127{
128	unsigned char buf[4];
129
130	if (p->br->stp_enabled != BR_KERNEL_STP)
131		return;
132
133	buf[0] = 0;
134	buf[1] = 0;
135	buf[2] = 0;
136	buf[3] = BPDU_TYPE_TCN;
137	br_send_bpdu(p, buf, 4);
138
139	p->stp_xstats.tx_tcn++;
140}
141
142/*
143 * Called from llc.
144 *
145 * NO locks, but rcu_read_lock
146 */
147void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
148		struct net_device *dev)
149{
150	struct net_bridge_port *p;
151	struct net_bridge *br;
152	const unsigned char *buf;
153
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;
161
162	p = br_port_get_check_rcu(dev);
163	if (!p)
164		goto err;
165
166	br = p->br;
167	spin_lock(&br->lock);
168
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)
176		goto out;
177
178	if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
179		goto out;
180
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
188	buf = skb_pull(skb, 3);
189
190	if (buf[0] == BPDU_TYPE_CONFIG) {
191		struct br_config_bpdu bpdu;
192
193		if (!pskb_may_pull(skb, 32))
194			goto out;
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
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
239		br_received_config_bpdu(p, &bpdu);
240	} else if (buf[0] == BPDU_TYPE_TCN) {
241		br_received_tcn_bpdu(p);
242	}
243 out:
244	spin_unlock(&br->lock);
245 err:
246	kfree_skb(skb);
247}