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 14 #include <linux/kernel.h> 15 #include <linux/netdevice.h> 16 #include <linux/etherdevice.h> 17 #include <linux/netfilter_bridge.h> 18 #include "br_private.h" 19 20 /* Bridge group multicast address 802.1d (pg 51). */ 21 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 22 23 static int br_pass_frame_up(struct sk_buff *skb) 24 { 25 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 26 27 brdev->stats.rx_packets++; 28 brdev->stats.rx_bytes += skb->len; 29 30 indev = skb->dev; 31 skb->dev = brdev; 32 33 return NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 34 netif_receive_skb); 35 } 36 37 /* note: already called with rcu_read_lock (preempt_disabled) */ 38 int br_handle_frame_finish(struct sk_buff *skb) 39 { 40 const unsigned char *dest = eth_hdr(skb)->h_dest; 41 struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); 42 struct net_bridge *br; 43 struct net_bridge_fdb_entry *dst; 44 struct net_bridge_mdb_entry *mdst; 45 struct sk_buff *skb2; 46 47 if (!p || p->state == BR_STATE_DISABLED) 48 goto drop; 49 50 /* insert into forwarding database after filtering to avoid spoofing */ 51 br = p->br; 52 br_fdb_update(br, p, eth_hdr(skb)->h_source); 53 54 if (is_multicast_ether_addr(dest) && 55 br_multicast_rcv(br, p, skb)) 56 goto drop; 57 58 if (p->state == BR_STATE_LEARNING) 59 goto drop; 60 61 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 62 63 /* The packet skb2 goes to the local host (NULL to skip). */ 64 skb2 = NULL; 65 66 if (br->dev->flags & IFF_PROMISC) 67 skb2 = skb; 68 69 dst = NULL; 70 71 if (is_multicast_ether_addr(dest)) { 72 mdst = br_mdb_get(br, skb); 73 if (mdst || BR_INPUT_SKB_CB(skb)->mrouters_only) { 74 if ((mdst && !hlist_unhashed(&mdst->mglist)) || 75 br_multicast_is_router(br)) 76 skb2 = skb; 77 br_multicast_forward(mdst, skb, skb2); 78 skb = NULL; 79 if (!skb2) 80 goto out; 81 } else 82 skb2 = skb; 83 84 br->dev->stats.multicast++; 85 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { 86 skb2 = skb; 87 /* Do not forward the packet since it's local. */ 88 skb = NULL; 89 } 90 91 if (skb) { 92 if (dst) 93 br_forward(dst->dst, skb); 94 else 95 br_flood_forward(br, skb, skb2); 96 } 97 98 if (skb2) 99 return br_pass_frame_up(skb2); 100 101 out: 102 return 0; 103 drop: 104 kfree_skb(skb); 105 goto out; 106 } 107 108 /* note: already called with rcu_read_lock (preempt_disabled) */ 109 static int br_handle_local_finish(struct sk_buff *skb) 110 { 111 struct net_bridge_port *p = rcu_dereference(skb->dev->br_port); 112 113 if (p) 114 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 115 return 0; /* process further */ 116 } 117 118 /* Does address match the link local multicast address. 119 * 01:80:c2:00:00:0X 120 */ 121 static inline int is_link_local(const unsigned char *dest) 122 { 123 __be16 *a = (__be16 *)dest; 124 static const __be16 *b = (const __be16 *)br_group_address; 125 static const __be16 m = cpu_to_be16(0xfff0); 126 127 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 128 } 129 130 /* 131 * Called via br_handle_frame_hook. 132 * Return NULL if skb is handled 133 * note: already called with rcu_read_lock (preempt_disabled) 134 */ 135 struct sk_buff *br_handle_frame(struct net_bridge_port *p, struct sk_buff *skb) 136 { 137 const unsigned char *dest = eth_hdr(skb)->h_dest; 138 int (*rhook)(struct sk_buff *skb); 139 140 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 141 goto drop; 142 143 skb = skb_share_check(skb, GFP_ATOMIC); 144 if (!skb) 145 return NULL; 146 147 if (unlikely(is_link_local(dest))) { 148 /* Pause frames shouldn't be passed up by driver anyway */ 149 if (skb->protocol == htons(ETH_P_PAUSE)) 150 goto drop; 151 152 /* If STP is turned off, then forward */ 153 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0) 154 goto forward; 155 156 if (NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 157 NULL, br_handle_local_finish)) 158 return NULL; /* frame consumed by filter */ 159 else 160 return skb; /* continue processing */ 161 } 162 163 forward: 164 switch (p->state) { 165 case BR_STATE_FORWARDING: 166 rhook = rcu_dereference(br_should_route_hook); 167 if (rhook != NULL) { 168 if (rhook(skb)) 169 return skb; 170 dest = eth_hdr(skb)->h_dest; 171 } 172 /* fall through */ 173 case BR_STATE_LEARNING: 174 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 175 skb->pkt_type = PACKET_HOST; 176 177 NF_HOOK(PF_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 178 br_handle_frame_finish); 179 break; 180 default: 181 drop: 182 kfree_skb(skb); 183 } 184 return NULL; 185 } 186