br_input.c 4.1 KB

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  1. /*
  2. * Handle incoming frames
  3. * Linux ethernet bridge
  4. *
  5. * Authors:
  6. * Lennert Buytenhek <buytenh@gnu.org>
  7. *
  8. * This program is free software; you can redistribute it and/or
  9. * modify it under the terms of the GNU General Public License
  10. * as published by the Free Software Foundation; either version
  11. * 2 of the License, or (at your option) any later version.
  12. */
  13. #include <linux/kernel.h>
  14. #include <linux/netdevice.h>
  15. #include <linux/etherdevice.h>
  16. #include <linux/netfilter_bridge.h>
  17. #include "br_private.h"
  18. /* Bridge group multicast address 802.1d (pg 51). */
  19. const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 };
  20. static int br_pass_frame_up(struct sk_buff *skb)
  21. {
  22. struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
  23. brdev->stats.rx_packets++;
  24. brdev->stats.rx_bytes += skb->len;
  25. indev = skb->dev;
  26. skb->dev = brdev;
  27. return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,
  28. netif_receive_skb);
  29. }
  30. /* note: already called with rcu_read_lock (preempt_disabled) */
  31. int br_handle_frame_finish(struct sk_buff *skb)
  32. {
  33. const unsigned char *dest = eth_hdr(skb)->h_dest;
  34. struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
  35. struct net_bridge *br;
  36. struct net_bridge_fdb_entry *dst;
  37. struct sk_buff *skb2;
  38. if (!p || p->state == BR_STATE_DISABLED)
  39. goto drop;
  40. /* insert into forwarding database after filtering to avoid spoofing */
  41. br = p->br;
  42. br_fdb_update(br, p, eth_hdr(skb)->h_source);
  43. if (p->state == BR_STATE_LEARNING)
  44. goto drop;
  45. BR_INPUT_SKB_CB(skb)->brdev = br->dev;
  46. /* The packet skb2 goes to the local host (NULL to skip). */
  47. skb2 = NULL;
  48. if (br->dev->flags & IFF_PROMISC)
  49. skb2 = skb;
  50. dst = NULL;
  51. if (is_multicast_ether_addr(dest)) {
  52. br->dev->stats.multicast++;
  53. skb2 = skb;
  54. } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {
  55. skb2 = skb;
  56. /* Do not forward the packet since it's local. */
  57. skb = NULL;
  58. }
  59. if (skb) {
  60. if (dst)
  61. br_forward(dst->dst, skb);
  62. else
  63. br_flood_forward(br, skb, skb2);
  64. }
  65. if (skb2)
  66. return br_pass_frame_up(skb2);
  67. out:
  68. return 0;
  69. drop:
  70. kfree_skb(skb);
  71. goto out;
  72. }
  73. /* note: already called with rcu_read_lock (preempt_disabled) */
  74. static int br_handle_local_finish(struct sk_buff *skb)
  75. {
  76. struct net_bridge_port *p = rcu_dereference(skb->dev->br_port);
  77. if (p)
  78. br_fdb_update(p->br, p, eth_hdr(skb)->h_source);
  79. return 0; /* process further */
  80. }
  81. /* Does address match the link local multicast address.
  82. * 01:80:c2:00:00:0X
  83. */
  84. static inline int is_link_local(const unsigned char *dest)
  85. {
  86. __be16 *a = (__be16 *)dest;
  87. static const __be16 *b = (const __be16 *)br_group_address;
  88. static const __be16 m = cpu_to_be16(0xfff0);
  89. return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0;
  90. }
  91. /*
  92. * Called via br_handle_frame_hook.
  93. * Return NULL if skb is handled
  94. * note: already called with rcu_read_lock (preempt_disabled)
  95. */
  96. struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb)
  97. {
  98. const unsigned char *dest = eth_hdr(skb)->h_dest;
  99. int (*rhook)(struct sk_buff *skb);
  100. if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
  101. goto drop;
  102. skb = skb_share_check(skb, GFP_ATOMIC);
  103. if (!skb)
  104. return NULL;
  105. if (unlikely(is_link_local(dest))) {
  106. /* Pause frames shouldn't be passed up by driver anyway */
  107. if (skb->protocol == htons(ETH_P_PAUSE))
  108. goto drop;
  109. /* If STP is turned off, then forward */
  110. if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0)
  111. goto forward;
  112. if (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,
  113. NULL, br_handle_local_finish))
  114. return NULL; /* frame consumed by filter */
  115. else
  116. return skb; /* continue processing */
  117. }
  118. forward:
  119. switch (p->state) {
  120. case BR_STATE_FORWARDING:
  121. rhook = rcu_dereference(br_should_route_hook);
  122. if (rhook != NULL) {
  123. if (rhook(skb))
  124. return skb;
  125. dest = eth_hdr(skb)->h_dest;
  126. }
  127. /* fall through */
  128. case BR_STATE_LEARNING:
  129. if (!compare_ether_addr(p->br->dev->dev_addr, dest))
  130. skb->pkt_type = PACKET_HOST;
  131. NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL,
  132. br_handle_frame_finish);
  133. break;
  134. default:
  135. drop:
  136. kfree_skb(skb);
  137. }
  138. return NULL;
  139. }