br_stp_bpdu.c 5.3 KB

123456789101112131415161718192021222324252627282930313233343536373839404142434445464748495051525354555657585960616263646566676869707172737475767778798081828384858687888990919293949596979899100101102103104105106107108109110111112113114115116117118119120121122123124125126127128129130131132133134135136137138139140141142143144145146147148149150151152153154155156157158159160161162163164165166167168169170171172173174175176177178179180181182183184185186187188189190191192193194195196197198199200201202203204205206207208209210211212213214215216217218219
  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 1.1.1.1 2007/06/12 07:27:14 eyryu 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. #include <linux/kernel.h>
  16. #include <linux/netfilter_bridge.h>
  17. #include <linux/etherdevice.h>
  18. #include <linux/llc.h>
  19. #include <net/llc.h>
  20. #include <net/llc_pdu.h>
  21. #include <asm/unaligned.h>
  22. #include "br_private.h"
  23. #include "br_private_stp.h"
  24. #define STP_HZ 256
  25. #define LLC_RESERVE sizeof(struct llc_pdu_un)
  26. static void br_send_bpdu(struct net_bridge_port *p,
  27. const unsigned char *data, int length)
  28. {
  29. struct sk_buff *skb;
  30. if (!p->br->stp_enabled)
  31. return;
  32. skb = dev_alloc_skb(length+LLC_RESERVE);
  33. if (!skb)
  34. return;
  35. skb->dev = p->dev;
  36. skb->protocol = htons(ETH_P_802_2);
  37. skb_reserve(skb, LLC_RESERVE);
  38. memcpy(__skb_put(skb, length), data, length);
  39. llc_pdu_header_init(skb, LLC_PDU_TYPE_U, LLC_SAP_BSPAN,
  40. LLC_SAP_BSPAN, LLC_PDU_CMD);
  41. llc_pdu_init_as_ui_cmd(skb);
  42. llc_mac_hdr_init(skb, p->dev->dev_addr, p->br->group_addr);
  43. NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
  44. dev_queue_xmit);
  45. }
  46. static inline void br_set_ticks(unsigned char *dest, int j)
  47. {
  48. unsigned long ticks = (STP_HZ * j)/ HZ;
  49. put_unaligned(htons(ticks), (__be16 *)dest);
  50. }
  51. static inline int br_get_ticks(const unsigned char *src)
  52. {
  53. unsigned long ticks = ntohs(get_unaligned((__be16 *)src));
  54. return (ticks * HZ + STP_HZ - 1) / STP_HZ;
  55. }
  56. /* called under bridge lock */
  57. void br_send_config_bpdu(struct net_bridge_port *p, struct br_config_bpdu *bpdu)
  58. {
  59. unsigned char buf[35];
  60. buf[0] = 0;
  61. buf[1] = 0;
  62. buf[2] = 0;
  63. buf[3] = BPDU_TYPE_CONFIG;
  64. buf[4] = (bpdu->topology_change ? 0x01 : 0) |
  65. (bpdu->topology_change_ack ? 0x80 : 0);
  66. buf[5] = bpdu->root.prio[0];
  67. buf[6] = bpdu->root.prio[1];
  68. buf[7] = bpdu->root.addr[0];
  69. buf[8] = bpdu->root.addr[1];
  70. buf[9] = bpdu->root.addr[2];
  71. buf[10] = bpdu->root.addr[3];
  72. buf[11] = bpdu->root.addr[4];
  73. buf[12] = bpdu->root.addr[5];
  74. buf[13] = (bpdu->root_path_cost >> 24) & 0xFF;
  75. buf[14] = (bpdu->root_path_cost >> 16) & 0xFF;
  76. buf[15] = (bpdu->root_path_cost >> 8) & 0xFF;
  77. buf[16] = bpdu->root_path_cost & 0xFF;
  78. buf[17] = bpdu->bridge_id.prio[0];
  79. buf[18] = bpdu->bridge_id.prio[1];
  80. buf[19] = bpdu->bridge_id.addr[0];
  81. buf[20] = bpdu->bridge_id.addr[1];
  82. buf[21] = bpdu->bridge_id.addr[2];
  83. buf[22] = bpdu->bridge_id.addr[3];
  84. buf[23] = bpdu->bridge_id.addr[4];
  85. buf[24] = bpdu->bridge_id.addr[5];
  86. buf[25] = (bpdu->port_id >> 8) & 0xFF;
  87. buf[26] = bpdu->port_id & 0xFF;
  88. br_set_ticks(buf+27, bpdu->message_age);
  89. br_set_ticks(buf+29, bpdu->max_age);
  90. br_set_ticks(buf+31, bpdu->hello_time);
  91. br_set_ticks(buf+33, bpdu->forward_delay);
  92. br_send_bpdu(p, buf, 35);
  93. }
  94. /* called under bridge lock */
  95. void br_send_tcn_bpdu(struct net_bridge_port *p)
  96. {
  97. unsigned char buf[4];
  98. buf[0] = 0;
  99. buf[1] = 0;
  100. buf[2] = 0;
  101. buf[3] = BPDU_TYPE_TCN;
  102. br_send_bpdu(p, buf, 4);
  103. }
  104. /*
  105. * Called from llc.
  106. *
  107. * NO locks, but rcu_read_lock (preempt_disabled)
  108. */
  109. int br_stp_rcv(struct sk_buff *skb, struct net_device *dev,
  110. struct packet_type *pt, struct net_device *orig_dev)
  111. {
  112. const struct llc_pdu_un *pdu = llc_pdu_un_hdr(skb);
  113. const unsigned char *dest = eth_hdr(skb)->h_dest;
  114. struct net_bridge_port *p = rcu_dereference(dev->br_port);
  115. struct net_bridge *br;
  116. const unsigned char *buf;
  117. if (!p)
  118. goto err;
  119. if (pdu->ssap != LLC_SAP_BSPAN
  120. || pdu->dsap != LLC_SAP_BSPAN
  121. || pdu->ctrl_1 != LLC_PDU_TYPE_U)
  122. goto err;
  123. if (!pskb_may_pull(skb, 4))
  124. goto err;
  125. /* compare of protocol id and version */
  126. buf = skb->data;
  127. if (buf[0] != 0 || buf[1] != 0 || buf[2] != 0)
  128. goto err;
  129. br = p->br;
  130. spin_lock(&br->lock);
  131. if (p->state == BR_STATE_DISABLED
  132. || !br->stp_enabled
  133. || !(br->dev->flags & IFF_UP))
  134. goto out;
  135. if (compare_ether_addr(dest, br->group_addr) != 0)
  136. goto out;
  137. buf = skb_pull(skb, 3);
  138. if (buf[0] == BPDU_TYPE_CONFIG) {
  139. struct br_config_bpdu bpdu;
  140. if (!pskb_may_pull(skb, 32))
  141. goto out;
  142. buf = skb->data;
  143. bpdu.topology_change = (buf[1] & 0x01) ? 1 : 0;
  144. bpdu.topology_change_ack = (buf[1] & 0x80) ? 1 : 0;
  145. bpdu.root.prio[0] = buf[2];
  146. bpdu.root.prio[1] = buf[3];
  147. bpdu.root.addr[0] = buf[4];
  148. bpdu.root.addr[1] = buf[5];
  149. bpdu.root.addr[2] = buf[6];
  150. bpdu.root.addr[3] = buf[7];
  151. bpdu.root.addr[4] = buf[8];
  152. bpdu.root.addr[5] = buf[9];
  153. bpdu.root_path_cost =
  154. (buf[10] << 24) |
  155. (buf[11] << 16) |
  156. (buf[12] << 8) |
  157. buf[13];
  158. bpdu.bridge_id.prio[0] = buf[14];
  159. bpdu.bridge_id.prio[1] = buf[15];
  160. bpdu.bridge_id.addr[0] = buf[16];
  161. bpdu.bridge_id.addr[1] = buf[17];
  162. bpdu.bridge_id.addr[2] = buf[18];
  163. bpdu.bridge_id.addr[3] = buf[19];
  164. bpdu.bridge_id.addr[4] = buf[20];
  165. bpdu.bridge_id.addr[5] = buf[21];
  166. bpdu.port_id = (buf[22] << 8) | buf[23];
  167. bpdu.message_age = br_get_ticks(buf+24);
  168. bpdu.max_age = br_get_ticks(buf+26);
  169. bpdu.hello_time = br_get_ticks(buf+28);
  170. bpdu.forward_delay = br_get_ticks(buf+30);
  171. br_received_config_bpdu(p, &bpdu);
  172. }
  173. else if (buf[0] == BPDU_TYPE_TCN) {
  174. br_received_tcn_bpdu(p);
  175. }
  176. out:
  177. spin_unlock(&br->lock);
  178. err:
  179. kfree_skb(skb);
  180. return 0;
  181. }