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/slab.h> 15 #include <linux/kernel.h> 16 #include <linux/netdevice.h> 17 #include <linux/etherdevice.h> 18 #include <linux/netfilter_bridge.h> 19 #include "br_private.h" 20 21 /* Bridge group multicast address 802.1d (pg 51). */ 22 const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 23 24 /* Hook for brouter */ 25 br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; 26 EXPORT_SYMBOL(br_should_route_hook); 27 28 static int br_pass_frame_up(struct sk_buff *skb) 29 { 30 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 31 struct net_bridge *br = netdev_priv(brdev); 32 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats); 33 34 u64_stats_update_begin(&brstats->syncp); 35 brstats->rx_packets++; 36 brstats->rx_bytes += skb->len; 37 u64_stats_update_end(&brstats->syncp); 38 39 indev = skb->dev; 40 skb->dev = brdev; 41 42 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 43 netif_receive_skb); 44 } 45 46 /* note: already called with rcu_read_lock */ 47 int br_handle_frame_finish(struct sk_buff *skb) 48 { 49 const unsigned char *dest = eth_hdr(skb)->h_dest; 50 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 51 struct net_bridge *br; 52 struct net_bridge_fdb_entry *dst; 53 struct net_bridge_mdb_entry *mdst; 54 struct sk_buff *skb2; 55 56 if (!p || p->state == BR_STATE_DISABLED) 57 goto drop; 58 59 /* insert into forwarding database after filtering to avoid spoofing */ 60 br = p->br; 61 br_fdb_update(br, p, eth_hdr(skb)->h_source); 62 63 if (is_multicast_ether_addr(dest) && 64 br_multicast_rcv(br, p, skb)) 65 goto drop; 66 67 if (p->state == BR_STATE_LEARNING) 68 goto drop; 69 70 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 71 72 /* The packet skb2 goes to the local host (NULL to skip). */ 73 skb2 = NULL; 74 75 if (br->dev->flags & IFF_PROMISC) 76 skb2 = skb; 77 78 dst = NULL; 79 80 if (is_multicast_ether_addr(dest)) { 81 mdst = br_mdb_get(br, skb); 82 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { 83 if ((mdst && mdst->mglist) || 84 br_multicast_is_router(br)) 85 skb2 = skb; 86 br_multicast_forward(mdst, skb, skb2); 87 skb = NULL; 88 if (!skb2) 89 goto out; 90 } else 91 skb2 = skb; 92 93 br->dev->stats.multicast++; 94 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { 95 skb2 = skb; 96 /* Do not forward the packet since it's local. */ 97 skb = NULL; 98 } 99 100 if (skb) { 101 if (dst) 102 br_forward(dst->dst, skb, skb2); 103 else 104 br_flood_forward(br, skb, skb2); 105 } 106 107 if (skb2) 108 return br_pass_frame_up(skb2); 109 110 out: 111 return 0; 112 drop: 113 kfree_skb(skb); 114 goto out; 115 } 116 117 /* note: already called with rcu_read_lock */ 118 static int br_handle_local_finish(struct sk_buff *skb) 119 { 120 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 121 122 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 123 return 0; /* process further */ 124 } 125 126 /* Does address match the link local multicast address. 127 * 01:80:c2:00:00:0X 128 */ 129 static inline int is_link_local(const unsigned char *dest) 130 { 131 __be16 *a = (__be16 *)dest; 132 static const __be16 *b = (const __be16 *)br_group_address; 133 static const __be16 m = cpu_to_be16(0xfff0); 134 135 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 136 } 137 138 /* 139 * Return NULL if skb is handled 140 * note: already called with rcu_read_lock 141 */ 142 rx_handler_result_t br_handle_frame(struct sk_buff **pskb) 143 { 144 struct net_bridge_port *p; 145 struct sk_buff *skb = *pskb; 146 const unsigned char *dest = eth_hdr(skb)->h_dest; 147 br_should_route_hook_t *rhook; 148 149 if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) 150 return RX_HANDLER_PASS; 151 152 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 153 goto drop; 154 155 skb = skb_share_check(skb, GFP_ATOMIC); 156 if (!skb) 157 return RX_HANDLER_CONSUMED; 158 159 p = br_port_get_rcu(skb->dev); 160 161 if (unlikely(is_link_local(dest))) { 162 /* Pause frames shouldn't be passed up by driver anyway */ 163 if (skb->protocol == htons(ETH_P_PAUSE)) 164 goto drop; 165 166 /* If STP is turned off, then forward */ 167 if (p->br->stp_enabled == BR_NO_STP) 168 goto forward; 169 170 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 171 NULL, br_handle_local_finish)) { 172 return RX_HANDLER_CONSUMED; /* consumed by filter */ 173 } else { 174 *pskb = skb; 175 return RX_HANDLER_PASS; /* continue processing */ 176 } 177 } 178 179 forward: 180 switch (p->state) { 181 case BR_STATE_FORWARDING: 182 rhook = rcu_dereference(br_should_route_hook); 183 if (rhook) { 184 if ((*rhook)(skb)) { 185 *pskb = skb; 186 return RX_HANDLER_PASS; 187 } 188 dest = eth_hdr(skb)->h_dest; 189 } 190 /* fall through */ 191 case BR_STATE_LEARNING: 192 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 193 skb->pkt_type = PACKET_HOST; 194 195 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 196 br_handle_frame_finish); 197 break; 198 default: 199 drop: 200 kfree_skb(skb); 201 } 202 return RX_HANDLER_CONSUMED; 203 } 204