| /* |
| * 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/neighbour.h> |
| #include <net/arp.h> |
| #include <linux/export.h> |
| #include <linux/rculist.h> |
| #include "br_private.h" |
| #include "br_private_tunnel.h" |
| |
| /* Hook for brouter */ |
| br_should_route_hook_t __rcu *br_should_route_hook __read_mostly; |
| EXPORT_SYMBOL(br_should_route_hook); |
| |
| static int |
| br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| br_drop_fake_rtable(skb); |
| return netif_receive_skb(skb); |
| } |
| |
| 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 net_bridge_vlan_group *vg; |
| struct pcpu_sw_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); |
| |
| vg = br_vlan_group_rcu(br); |
| /* Bridge is just like any other port. Make sure the |
| * packet is allowed except in promisc modue when someone |
| * may be running packet capture. |
| */ |
| if (!(brdev->flags & IFF_PROMISC) && |
| !br_allowed_egress(vg, skb)) { |
| kfree_skb(skb); |
| return NET_RX_DROP; |
| } |
| |
| indev = skb->dev; |
| skb->dev = brdev; |
| skb = br_handle_vlan(br, NULL, vg, skb); |
| if (!skb) |
| return NET_RX_DROP; |
| /* update the multicast stats if the packet is IGMP/MLD */ |
| br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb), |
| BR_MCAST_DIR_TX); |
| |
| return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
| dev_net(indev), NULL, skb, indev, NULL, |
| br_netif_receive_skb); |
| } |
| |
| static void br_do_proxy_arp(struct sk_buff *skb, struct net_bridge *br, |
| u16 vid, struct net_bridge_port *p) |
| { |
| struct net_device *dev = br->dev; |
| struct neighbour *n; |
| struct arphdr *parp; |
| u8 *arpptr, *sha; |
| __be32 sip, tip; |
| |
| BR_INPUT_SKB_CB(skb)->proxyarp_replied = false; |
| |
| if ((dev->flags & IFF_NOARP) || |
| !pskb_may_pull(skb, arp_hdr_len(dev))) |
| return; |
| |
| parp = arp_hdr(skb); |
| |
| if (parp->ar_pro != htons(ETH_P_IP) || |
| parp->ar_op != htons(ARPOP_REQUEST) || |
| parp->ar_hln != dev->addr_len || |
| parp->ar_pln != 4) |
| return; |
| |
| arpptr = (u8 *)parp + sizeof(struct arphdr); |
| sha = arpptr; |
| arpptr += dev->addr_len; /* sha */ |
| memcpy(&sip, arpptr, sizeof(sip)); |
| arpptr += sizeof(sip); |
| arpptr += dev->addr_len; /* tha */ |
| memcpy(&tip, arpptr, sizeof(tip)); |
| |
| if (ipv4_is_loopback(tip) || |
| ipv4_is_multicast(tip)) |
| return; |
| |
| n = neigh_lookup(&arp_tbl, &tip, dev); |
| if (n) { |
| struct net_bridge_fdb_entry *f; |
| |
| if (!(n->nud_state & NUD_VALID)) { |
| neigh_release(n); |
| return; |
| } |
| |
| f = br_fdb_find_rcu(br, n->ha, vid); |
| if (f && ((p->flags & BR_PROXYARP) || |
| (f->dst && (f->dst->flags & BR_PROXYARP_WIFI)))) { |
| arp_send(ARPOP_REPLY, ETH_P_ARP, sip, skb->dev, tip, |
| sha, n->ha, sha); |
| BR_INPUT_SKB_CB(skb)->proxyarp_replied = true; |
| } |
| |
| neigh_release(n); |
| } |
| } |
| |
| /* note: already called with rcu_read_lock */ |
| int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| struct net_bridge_port *p = br_port_get_rcu(skb->dev); |
| enum br_pkt_type pkt_type = BR_PKT_UNICAST; |
| struct net_bridge_fdb_entry *dst = NULL; |
| struct net_bridge_mdb_entry *mdst; |
| bool local_rcv, mcast_hit = false; |
| const unsigned char *dest; |
| struct net_bridge *br; |
| u16 vid = 0; |
| |
| if (!p || p->state == BR_STATE_DISABLED) |
| goto drop; |
| |
| if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid)) |
| goto out; |
| |
| nbp_switchdev_frame_mark(p, skb); |
| |
| /* insert into forwarding database after filtering to avoid spoofing */ |
| br = p->br; |
| if (p->flags & BR_LEARNING) |
| br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, false); |
| |
| local_rcv = !!(br->dev->flags & IFF_PROMISC); |
| dest = eth_hdr(skb)->h_dest; |
| if (is_multicast_ether_addr(dest)) { |
| /* by definition the broadcast is also a multicast address */ |
| if (is_broadcast_ether_addr(dest)) { |
| pkt_type = BR_PKT_BROADCAST; |
| local_rcv = true; |
| } else { |
| pkt_type = BR_PKT_MULTICAST; |
| if (br_multicast_rcv(br, p, skb, vid)) |
| goto drop; |
| } |
| } |
| |
| if (p->state == BR_STATE_LEARNING) |
| goto drop; |
| |
| BR_INPUT_SKB_CB(skb)->brdev = br->dev; |
| |
| if (IS_ENABLED(CONFIG_INET) && skb->protocol == htons(ETH_P_ARP)) |
| br_do_proxy_arp(skb, br, vid, p); |
| |
| switch (pkt_type) { |
| case BR_PKT_MULTICAST: |
| mdst = br_mdb_get(br, skb, vid); |
| if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && |
| br_multicast_querier_exists(br, eth_hdr(skb))) { |
| if ((mdst && mdst->mglist) || |
| br_multicast_is_router(br)) { |
| local_rcv = true; |
| br->dev->stats.multicast++; |
| } |
| mcast_hit = true; |
| } else { |
| local_rcv = true; |
| br->dev->stats.multicast++; |
| } |
| break; |
| case BR_PKT_UNICAST: |
| dst = br_fdb_find_rcu(br, dest, vid); |
| default: |
| break; |
| } |
| |
| if (dst) { |
| unsigned long now = jiffies; |
| |
| if (dst->is_local) |
| return br_pass_frame_up(skb); |
| |
| if (now != dst->used) |
| dst->used = now; |
| br_forward(dst->dst, skb, local_rcv, false); |
| } else { |
| if (!mcast_hit) |
| br_flood(br, skb, pkt_type, local_rcv, false); |
| else |
| br_multicast_flood(mdst, skb, local_rcv, false); |
| } |
| |
| if (local_rcv) |
| return br_pass_frame_up(skb); |
| |
| out: |
| return 0; |
| drop: |
| kfree_skb(skb); |
| goto out; |
| } |
| EXPORT_SYMBOL_GPL(br_handle_frame_finish); |
| |
| static void __br_handle_local_finish(struct sk_buff *skb) |
| { |
| struct net_bridge_port *p = br_port_get_rcu(skb->dev); |
| u16 vid = 0; |
| |
| /* check if vlan is allowed, to avoid spoofing */ |
| if (p->flags & BR_LEARNING && br_should_learn(p, skb, &vid)) |
| br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, false); |
| } |
| |
| /* note: already called with rcu_read_lock */ |
| static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb) |
| { |
| __br_handle_local_finish(skb); |
| |
| /* return 1 to signal the okfn() was called so it's ok to use the skb */ |
| return 1; |
| } |
| |
| /* |
| * 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 (p->flags & BR_VLAN_TUNNEL) { |
| if (br_handle_ingress_vlan_tunnel(skb, p, |
| nbp_vlan_group_rcu(p))) |
| goto drop; |
| } |
| |
| if (unlikely(is_link_local_ether_addr(dest))) { |
| u16 fwd_mask = p->br->group_fwd_mask_required; |
| |
| /* |
| * 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 || |
| fwd_mask & (1u << dest[5])) |
| goto forward; |
| *pskb = skb; |
| __br_handle_local_finish(skb); |
| return RX_HANDLER_PASS; |
| |
| case 0x01: /* IEEE MAC (Pause) */ |
| goto drop; |
| |
| case 0x0E: /* 802.1AB LLDP */ |
| fwd_mask |= p->br->group_fwd_mask; |
| if (fwd_mask & (1u << dest[5])) |
| goto forward; |
| *pskb = skb; |
| __br_handle_local_finish(skb); |
| return RX_HANDLER_PASS; |
| |
| default: |
| /* Allow selective forwarding for most other protocols */ |
| fwd_mask |= p->br->group_fwd_mask; |
| if (fwd_mask & (1u << dest[5])) |
| goto forward; |
| } |
| |
| /* The else clause should be hit when nf_hook(): |
| * - returns < 0 (drop/error) |
| * - returns = 0 (stolen/nf_queue) |
| * Thus return 1 from the okfn() to signal the skb is ok to pass |
| */ |
| if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, |
| dev_net(skb->dev), NULL, skb, skb->dev, NULL, |
| br_handle_local_finish) == 1) { |
| return RX_HANDLER_PASS; |
| } else { |
| return RX_HANDLER_CONSUMED; |
| } |
| } |
| |
| 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 (ether_addr_equal(p->br->dev->dev_addr, dest)) |
| skb->pkt_type = PACKET_HOST; |
| |
| NF_HOOK(NFPROTO_BRIDGE, NF_BR_PRE_ROUTING, |
| dev_net(skb->dev), NULL, skb, skb->dev, NULL, |
| br_handle_frame_finish); |
| break; |
| default: |
| drop: |
| kfree_skb(skb); |
| } |
| return RX_HANDLER_CONSUMED; |
| } |