diff options
Diffstat (limited to 'net/bridge/br_input.c')
| -rw-r--r-- | net/bridge/br_input.c | 230 |
1 files changed, 230 insertions, 0 deletions
diff --git a/net/bridge/br_input.c b/net/bridge/br_input.c new file mode 100644 index 00000000..5a31731b --- /dev/null +++ b/net/bridge/br_input.c @@ -0,0 +1,230 @@ +/* + * Handle incoming frames + * Linux ethernet bridge + * + * Authors: + * Lennert Buytenhek <buytenh@gnu.org> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ + +#include <linux/slab.h> +#include <linux/kernel.h> +#include <linux/netdevice.h> +#include <linux/etherdevice.h> +#include <linux/netfilter_bridge.h> +#include <linux/export.h> +#include "br_private.h" + +/* Bridge group multicast address 802.1d (pg 51). */ +const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; + +/* Hook for brouter */ +br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; +EXPORT_SYMBOL(br_should_route_hook); + +static int br_pass_frame_up(struct sk_buff *skb) +{ + struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev; + struct net_bridge *br = netdev_priv(brdev); + struct br_cpu_netstats *brstats = this_cpu_ptr(br->stats); + + u64_stats_update_begin(&brstats->syncp); + brstats->rx_packets++; + brstats->rx_bytes += skb->len; + u64_stats_update_end(&brstats->syncp); + + indev = skb->dev; + skb->dev = brdev; + + return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL, + netif_receive_skb); +} + +/* note: already called with rcu_read_lock */ +int br_handle_frame_finish(struct sk_buff *skb) +{ + const unsigned char *dest = eth_hdr(skb)->h_dest; + struct net_bridge_port *p = br_port_get_rcu(skb->dev); + struct net_bridge *br; + struct net_bridge_fdb_entry *dst; + struct net_bridge_mdb_entry *mdst; + struct sk_buff *skb2; + + if (!p || p->state == BR_STATE_DISABLED) + goto drop; + + /* insert into forwarding database after filtering to avoid spoofing */ + br = p->br; + br_fdb_update(br, p, eth_hdr(skb)->h_source); + + if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) && + br_multicast_rcv(br, p, skb)) + goto drop; + + if (p->state == BR_STATE_LEARNING) + goto drop; + + BR_INPUT_SKB_CB(skb)->brdev = br->dev; + + /* The packet skb2 goes to the local host (NULL to skip). */ + skb2 = NULL; + + if (br->dev->flags & IFF_PROMISC) + skb2 = skb; + + dst = NULL; + + if (is_broadcast_ether_addr(dest)) + skb2 = skb; + else if (is_multicast_ether_addr(dest)) { + mdst = br_mdb_get(br, skb); + if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) { + if ((mdst && mdst->mglist) || + br_multicast_is_router(br)) + skb2 = skb; + br_multicast_forward(mdst, skb, skb2); + skb = NULL; + if (!skb2) + goto out; + } else + skb2 = skb; + + br->dev->stats.multicast++; + } else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) { + skb2 = skb; + /* Do not forward the packet since it's local. */ + skb = NULL; + } + + if (skb) { + if (dst) { + dst->used = jiffies; + br_forward(dst->dst, skb, skb2); + } else + br_flood_forward(br, skb, skb2); + } + + if (skb2) + return br_pass_frame_up(skb2); + +out: + return 0; +drop: + kfree_skb(skb); + goto out; +} + +/* note: already called with rcu_read_lock */ +static int br_handle_local_finish(struct sk_buff *skb) +{ + struct net_bridge_port *p = br_port_get_rcu(skb->dev); + + br_fdb_update(p->br, p, eth_hdr(skb)->h_source); + return 0; /* process further */ +} + +/* Does address match the link local multicast address. + * 01:80:c2:00:00:0X + */ +static inline int is_link_local(const unsigned char *dest) +{ + __be16 *a = (__be16 *)dest; + static const __be16 *b = (const __be16 *)br_group_address; + static const __be16 m = cpu_to_be16(0xfff0); + + return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 0; +} + +/* + * Return NULL if skb is handled + * note: already called with rcu_read_lock + */ +rx_handler_result_t br_handle_frame(struct sk_buff **pskb) +{ + struct net_bridge_port *p; + struct sk_buff *skb = *pskb; + const unsigned char *dest = eth_hdr(skb)->h_dest; + br_should_route_hook_t *rhook; + + if (unlikely(skb->pkt_type == PACKET_LOOPBACK)) + return RX_HANDLER_PASS; + + if (!is_valid_ether_addr(eth_hdr(skb)->h_source)) + goto drop; + + skb = skb_share_check(skb, GFP_ATOMIC); + if (!skb) + return RX_HANDLER_CONSUMED; + + p = br_port_get_rcu(skb->dev); + + if (unlikely(is_link_local(dest))) { + /* + * See IEEE 802.1D Table 7-10 Reserved addresses + * + * Assignment Value + * Bridge Group Address 01-80-C2-00-00-00 + * (MAC Control) 802.3 01-80-C2-00-00-01 + * (Link Aggregation) 802.3 01-80-C2-00-00-02 + * 802.1X PAE address 01-80-C2-00-00-03 + * + * 802.1AB LLDP 01-80-C2-00-00-0E + * + * Others reserved for future standardization + */ + switch (dest[5]) { + case 0x00: /* Bridge Group Address */ + /* If STP is turned off, + then must forward to keep loop detection */ + if (p->br->stp_enabled == BR_NO_STP) + goto forward; + break; + + case 0x01: /* IEEE MAC (Pause) */ + goto drop; + + default: + /* Allow selective forwarding for most other protocols */ + if (p->br->group_fwd_mask & (1u << dest[5])) + goto forward; + } + + /* Deliver packet to local host only */ + if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev, + NULL, br_handle_local_finish)) { + return RX_HANDLER_CONSUMED; /* consumed by filter */ + } else { + *pskb = skb; + return RX_HANDLER_PASS; /* continue processing */ + } + } + +forward: + switch (p->state) { + case BR_STATE_FORWARDING: + rhook = rcu_dereference(br_should_route_hook); + if (rhook) { + if ((*rhook)(skb)) { + *pskb = skb; + return RX_HANDLER_PASS; + } + dest = eth_hdr(skb)->h_dest; + } + /* fall through */ + case BR_STATE_LEARNING: + if (!compare_ether_addr(p->br->dev->dev_addr, dest)) + skb->pkt_type = PACKET_HOST; + + NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, skb, skb->dev, NULL, + br_handle_frame_finish); + break; + default: +drop: + kfree_skb(skb); + } + return RX_HANDLER_CONSUMED; +} |