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). */ 22const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; 23 24static 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 */ 43int 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#ifdef HNDCTF 58 br_fdb_update(br, p, eth_hdr(skb)->h_source, skb); 59#else 60 br_fdb_update(br, p, eth_hdr(skb)->h_source); 61#endif 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 110out: 111 return 0; 112drop: 113 kfree_skb(skb); 114 goto out; 115} 116 117/* note: already called with rcu_read_lock */ 118static int br_handle_local_finish(struct sk_buff *skb) 119{ 120 struct net_bridge_port *p = br_port_get_rcu(skb->dev); 121 122#ifdef HNDCTF 123 br_fdb_update(p->br, p, eth_hdr(skb)->h_source, skb); 124#else 125 br_fdb_update(p->br, p, eth_hdr(skb)->h_source); 126#endif 127 return 0; /* process further */ 128} 129 130/* Does address match the link local multicast address. 131 * 01:80:c2:00:00:0X 132 */ 133static inline int is_link_local(const unsigned char *dest) 134{ 135 __be16 *a = (__be16 *)dest; 136 static const __be16 *b = (const __be16 *)br_group_address; 137 static const __be16 m = cpu_to_be16(0xfff0); 138 139 return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; 140} 141 142/* 143 * Return NULL if skb is handled 144 * note: already called with rcu_read_lock 145 */ 146struct sk_buff *br_handle_frame(struct sk_buff *skb) 147{ 148 struct net_bridge_port *p; 149 const unsigned char *dest = eth_hdr(skb)->h_dest; 150 int (*rhook)(struct sk_buff *skb); 151 152 if (skb->pkt_type == PACKET_LOOPBACK) 153 return skb; 154 155 if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) 156 goto drop; 157 158 skb = skb_share_check(skb, GFP_ATOMIC); 159 if (!skb) 160 return NULL; 161 162 p = br_port_get_rcu(skb->dev); 163 164 if (unlikely(is_link_local(dest))) { 165 /* Pause frames shouldn't be passed up by driver anyway */ 166 if (skb->protocol == htons(ETH_P_PAUSE)) 167 goto drop; 168 169 /* If STP is turned off, then forward */ 170 if (p->br->stp_enabled == BR_NO_STP && dest[5] == 0) 171 goto forward; 172 173 if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, 174 NULL, br_handle_local_finish)) 175 return NULL; /* frame consumed by filter */ 176 else 177 return skb; /* continue processing */ 178 } 179 180forward: 181 switch (p->state) { 182 case BR_STATE_FORWARDING: 183 rhook = rcu_dereference(br_should_route_hook); 184 if (rhook != NULL) { 185 if (rhook(skb)) 186 return skb; 187 dest = eth_hdr(skb)->h_dest; 188 } 189 /* fall through */ 190 case BR_STATE_LEARNING: 191 if (!compare_ether_addr(p->br->dev->dev_addr, dest)) 192 skb->pkt_type = PACKET_HOST; 193 194 NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, 195 br_handle_frame_finish); 196 break; 197 default: 198drop: 199 kfree_skb(skb); 200 } 201 return NULL; 202} 203