br_stp_bpdu.c 5.6 KB

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  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. #include <linux/kernel.h>
  10. #include <linux/netfilter_bridge.h>
  11. #include <linux/etherdevice.h>
  12. #include <linux/llc.h>
  13. #include <linux/slab.h>
  14. #include <linux/pkt_sched.h>
  15. #include <net/net_namespace.h>
  16. #include <net/llc.h>
  17. #include <net/llc_pdu.h>
  18. #include <net/stp.h>
  19. #include <asm/unaligned.h>
  20. #include "br_private.h"
  21. #include "br_private_stp.h"
  22. #define STP_HZ 256
  23. #define LLC_RESERVE sizeof(struct llc_pdu_un)
  24. static int br_send_bpdu_finish(struct net *net, struct sock *sk,
  25. struct sk_buff *skb)
  26. {
  27. return dev_queue_xmit(skb);
  28. }
  29. static void br_send_bpdu(struct net_bridge_port *p,
  30. const unsigned char *data, int length)
  31. {
  32. struct sk_buff *skb;
  33. skb = dev_alloc_skb(length+LLC_RESERVE);
  34. if (!skb)
  35. return;
  36. skb->dev = p->dev;
  37. skb->protocol = htons(ETH_P_802_2);
  38. skb->priority = TC_PRIO_CONTROL;
  39. skb_reserve(skb, LLC_RESERVE);
  40. __skb_put_data(skb, data, length);
  41. llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
  42. LLC_SAP_BSPAN, LLC_PDU_CMD);
  43. llc_pdu_init_as_ui_cmd(skb);
  44. llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
  45. skb_reset_mac_header(skb);
  46. NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_OUT,
  47. dev_net(p->dev), NULL, skb, NULL, skb->dev,
  48. br_send_bpdu_finish);
  49. }
  50. static inline void br_set_ticks(unsigned char *dest, int j)
  51. {
  52. unsigned long ticks = (STP_HZ * j)/ HZ;
  53. put_unaligned_be16(ticks, dest);
  54. }
  55. static inline int br_get_ticks(const unsigned char *src)
  56. {
  57. unsigned long ticks = get_unaligned_be16(src);
  58. return DIV_ROUND_UP(ticks * HZ, STP_HZ);
  59. }
  60. /* called under bridge lock */
  61. void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
  62. {
  63. unsigned char buf[35];
  64. if (p->br->stp_enabled != BR_KERNEL_STP)
  65. return;
  66. buf[0] = 0;
  67. buf[1] = 0;
  68. buf[2] = 0;
  69. buf[3] = BPDU_TYPE_CONFIG;
  70. buf[4] = (bpdu->topology_change ? 0x01 : 0) |
  71. (bpdu->topology_change_ack ? 0x80 : 0);
  72. buf[5] = bpdu->root.prio[0];
  73. buf[6] = bpdu->root.prio[1];
  74. buf[7] = bpdu->root.addr[0];
  75. buf[8] = bpdu->root.addr[1];
  76. buf[9] = bpdu->root.addr[2];
  77. buf[10] = bpdu->root.addr[3];
  78. buf[11] = bpdu->root.addr[4];
  79. buf[12] = bpdu->root.addr[5];
  80. buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
  81. buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
  82. buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
  83. buf[16] = bpdu->root_path_cost & 0xFF;
  84. buf[17] = bpdu->bridge_id.prio[0];
  85. buf[18] = bpdu->bridge_id.prio[1];
  86. buf[19] = bpdu->bridge_id.addr[0];
  87. buf[20] = bpdu->bridge_id.addr[1];
  88. buf[21] = bpdu->bridge_id.addr[2];
  89. buf[22] = bpdu->bridge_id.addr[3];
  90. buf[23] = bpdu->bridge_id.addr[4];
  91. buf[24] = bpdu->bridge_id.addr[5];
  92. buf[25] = (bpdu->port_id >> 8) & 0xFF;
  93. buf[26] = bpdu->port_id & 0xFF;
  94. br_set_ticks(buf+27, bpdu->message_age);
  95. br_set_ticks(buf+29, bpdu->max_age);
  96. br_set_ticks(buf+31, bpdu->hello_time);
  97. br_set_ticks(buf+33, bpdu->forward_delay);
  98. br_send_bpdu(p, buf, 35);
  99. p->stp_xstats.tx_bpdu++;
  100. }
  101. /* called under bridge lock */
  102. void br_send_tcn_bpdu(struct net_bridge_port *p)
  103. {
  104. unsigned char buf[4];
  105. if (p->br->stp_enabled != BR_KERNEL_STP)
  106. return;
  107. buf[0] = 0;
  108. buf[1] = 0;
  109. buf[2] = 0;
  110. buf[3] = BPDU_TYPE_TCN;
  111. br_send_bpdu(p, buf, 4);
  112. p->stp_xstats.tx_tcn++;
  113. }
  114. /*
  115. * Called from llc.
  116. *
  117. * NO locks, but rcu_read_lock
  118. */
  119. void br_stp_rcv(const struct stp_proto *proto, struct sk_buff *skb,
  120. struct net_device *dev)
  121. {
  122. struct net_bridge_port *p;
  123. struct net_bridge *br;
  124. const unsigned char *buf;
  125. if (!pskb_may_pull(skb, 4))
  126. goto err;
  127. /* compare of protocol id and version */
  128. buf = skb->data;
  129. if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
  130. goto err;
  131. p = br_port_get_check_rcu(dev);
  132. if (!p)
  133. goto err;
  134. br = p->br;
  135. spin_lock(&br->lock);
  136. if (br->stp_enabled != BR_KERNEL_STP)
  137. goto out;
  138. if (!(br->dev->flags & IFF_UP))
  139. goto out;
  140. if (p->state == BR_STATE_DISABLED)
  141. goto out;
  142. if (!ether_addr_equal(eth_hdr(skb)->h_dest, br->group_addr))
  143. goto out;
  144. if (p->flags & BR_BPDU_GUARD) {
  145. br_notice(br, "BPDU received on blocked port %u(%s)\n",
  146. (unsigned int) p->port_no, p->dev->name);
  147. br_stp_disable_port(p);
  148. goto out;
  149. }
  150. buf = skb_pull(skb, 3);
  151. if (buf[0] == BPDU_TYPE_CONFIG) {
  152. struct br_config_bpdu bpdu;
  153. if (!pskb_may_pull(skb, 32))
  154. goto out;
  155. buf = skb->data;
  156. bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
  157. bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
  158. bpdu.root.prio[0] = buf[2];
  159. bpdu.root.prio[1] = buf[3];
  160. bpdu.root.addr[0] = buf[4];
  161. bpdu.root.addr[1] = buf[5];
  162. bpdu.root.addr[2] = buf[6];
  163. bpdu.root.addr[3] = buf[7];
  164. bpdu.root.addr[4] = buf[8];
  165. bpdu.root.addr[5] = buf[9];
  166. bpdu.root_path_cost =
  167. (buf[10] << 24) |
  168. (buf[11] << 16) |
  169. (buf[12] << 8) |
  170. buf[13];
  171. bpdu.bridge_id.prio[0] = buf[14];
  172. bpdu.bridge_id.prio[1] = buf[15];
  173. bpdu.bridge_id.addr[0] = buf[16];
  174. bpdu.bridge_id.addr[1] = buf[17];
  175. bpdu.bridge_id.addr[2] = buf[18];
  176. bpdu.bridge_id.addr[3] = buf[19];
  177. bpdu.bridge_id.addr[4] = buf[20];
  178. bpdu.bridge_id.addr[5] = buf[21];
  179. bpdu.port_id = (buf[22] << 8) | buf[23];
  180. bpdu.message_age = br_get_ticks(buf+24);
  181. bpdu.max_age = br_get_ticks(buf+26);
  182. bpdu.hello_time = br_get_ticks(buf+28);
  183. bpdu.forward_delay = br_get_ticks(buf+30);
  184. if (bpdu.message_age > bpdu.max_age) {
  185. if (net_ratelimit())
  186. br_notice(p->br,
  187. "port %u config from %pM"
  188. " (message_age %ul > max_age %ul)\n",
  189. p->port_no,
  190. eth_hdr(skb)->h_source,
  191. bpdu.message_age, bpdu.max_age);
  192. goto out;
  193. }
  194. br_received_config_bpdu(p, &bpdu);
  195. } else if (buf[0] == BPDU_TYPE_TCN) {
  196. br_received_tcn_bpdu(p);
  197. }
  198. out:
  199. spin_unlock(&br->lock);
  200. err:
  201. kfree_skb(skb);
  202. }