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 static int br_pass_frame_up(struct sk_buff *skb) 25 { 26 struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; 27 struct net_bridge *br = netdev_priv(brdev); 28 struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats); 29 30 u64_stats_update_begin(&brstats->syncp); 31 brstats->rx_packets++; 32 brstats->rx_bytes += skb->len; 33 u64_stats_update_end(&brstats->syncp); 34 35 indev = skb->dev; 36 skb->dev = brdev; 37 38 return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, 39 netif_receive_skb); 40 } 41 42 /* note: already called with rcu_read_lock */ 43 int br_handle_frame_finish(struct sk_buff *skb) 44 { 45 const unsigned char *dest = eth_hdr(skb)->h_dest; 46 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 47 struct net_bridge *br; 48 struct net_bridge_fdb_entry *dst; 49 struct net_bridge_mdb_entry *mdst; 50 struct sk_buff *skb2; 51 52 if (!p || p->state == BR_STATE_DISABLED) 53 goto drop; 54 55 /* insert into forwarding database after filtering to avoid spoofing */ 56 br = p->br; 57 br_fdb_update(br, p, eth_hdr(skb)->h_source); 58 59 if (is_multicast_ether_addr(dest) && 60 br_multicast_rcv(br, p, skb)) 61 goto drop; 62 63 if (p->state == BR_STATE_LEARNING) 64 goto drop; 65 66 BR_INPUT_SKB_CB(skb)->brdev = br->dev; 67 68 /* The packet skb2 goes to the local host (NULL to skip). */ 69 skb2 = NULL; 70 71 if (br->dev->flags & IFF_PROMISC) 72 skb2 = skb; 73 74 dst = NULL; 75 76 if (is_multicast_ether_addr(dest)) { 77 mdst = br_mdb_get(br, skb); 78 if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { 79 if ((mdst && !hlist_unhashed(&mdst->mglist)) || 80 br_multicast_is_router(br)) 81 skb2 = skb; 82 br_multicast_forward(mdst, skb, skb2); 83 skb = NULL; 84 if (!skb2) 85 goto out; 86 } else 87 skb2 = skb; 88 89 br->dev->stats.multicast++; 90 } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { 91 skb2 = skb; 92 /* Do not forward the packet since it's local. */ 93 skb = NULL; 94 } 95 96 if (skb) { 97 if (dst) 98 br_forward(dst->dst, skb, skb2); 99 else 100 br_flood_forward(br, skb, skb2); 101 } 102 103 if (skb2) 104 return br_pass_frame_up(skb2); 105 106 out: 107 return 0; 108 drop: 109 kfree_skb(skb); 110 goto out; 111 } 112 113 /* note: already called with rcu_read_lock */ 114 static int br_handle_local_finish(struct sk_buff *skb) 115 { 116 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 117 118 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 119 return 0; /* process further */ 120 } 121 122 /* Does address match the link local multicast address. 123 * 01:80:c2:00:00:0X 124 */ 125 static inline int is_link_local(const unsigned char *dest) 126 { 127 __be16 *a = (__be16 *)dest; 128 static const __be16 *b = (const __be16 *)br_group_address; 129 static const __be16 m = cpu_to_be16(0xfff0); 130 131 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 132 } 133 134 /* 135 * Return NULL if skb is handled 136 * note: already called with rcu_read_lock 137 */ 138 struct sk_buff *br_handle_frame(struct sk_buff *skb) 139 { 140 struct net_bridge_port *p; 141 const unsigned char *dest = eth_hdr(skb)->h_dest; 142 int (*rhook)(struct sk_buff *skb); 143 144 if (skb->pkt_type == PACKET_LOOPBACK) 145 return skb; 146 147 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 148 goto drop; 149 150 skb = skb_share_check(skb, GFP_ATOMIC); 151 if (!skb) 152 return NULL; 153 154 p = br_port_get_rcu(skb->dev); 155 156 if (unlikely(is_link_local(dest))) { 157 /* Pause frames shouldn't be passed up by driver anyway */ 158 if (skb->protocol == htons(ETH_P_PAUSE)) 159 goto drop; 160 161 /* If STP is turned off, then forward */ 162 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0) 163 goto forward; 164 165 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 166 NULL, br_handle_local_finish)) 167 return NULL; /* frame consumed by filter */ 168 else 169 return skb; /* continue processing */ 170 } 171 172 forward: 173 switch (p->state) { 174 case BR_STATE_FORWARDING: 175 rhook = rcu_dereference(br_should_route_hook); 176 if (rhook != NULL) { 177 if (rhook(skb)) 178 return skb; 179 dest = eth_hdr(skb)->h_dest; 180 } 181 /* fall through */ 182 case BR_STATE_LEARNING: 183 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 184 skb->pkt_type = PACKET_HOST; 185 186 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 187 br_handle_frame_finish); 188 break; 189 default: 190 drop: 191 kfree_skb(skb); 192 } 193 return NULL; 194 } 195