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