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- // SPDX-License-Identifier: GPL-2.0-or-later
- /*
- * Handle incoming frames
- * Linux ethernet bridge
- *
- * Authors:
- * Lennert Buytenhek <buytenh@gnu.org>
- */
- #include <linux/slab.h>
- #include <linux/kernel.h>
- #include <linux/netdevice.h>
- #include <linux/etherdevice.h>
- #include <linux/netfilter_bridge.h>
- #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
- #include <net/netfilter/nf_queue.h>
- #endif
- #include <linux/neighbour.h>
- #include <net/arp.h>
- #include <net/dsa.h>
- #include <linux/export.h>
- #include <linux/rculist.h>
- #include "br_private.h"
- #include "br_private_tunnel.h"
- 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);
- }
- /* 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;
- struct net_bridge *br;
- u16 vid = 0;
- u8 state;
- if (!p || p->state == BR_STATE_DISABLED)
- goto drop;
- state = p->state;
- if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
- &state))
- 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, 0);
- local_rcv = !!(br->dev->flags & IFF_PROMISC);
- if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
- /* by definition the broadcast is also a multicast address */
- if (is_broadcast_ether_addr(eth_hdr(skb)->h_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 (state == BR_STATE_LEARNING)
- goto drop;
- BR_INPUT_SKB_CB(skb)->brdev = br->dev;
- BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
- if (IS_ENABLED(CONFIG_INET) &&
- (skb->protocol == htons(ETH_P_ARP) ||
- skb->protocol == htons(ETH_P_RARP))) {
- br_do_proxy_suppress_arp(skb, br, vid, p);
- } else if (IS_ENABLED(CONFIG_IPV6) &&
- skb->protocol == htons(ETH_P_IPV6) &&
- br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
- pskb_may_pull(skb, sizeof(struct ipv6hdr) +
- sizeof(struct nd_msg)) &&
- ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
- struct nd_msg *msg, _msg;
- msg = br_is_nd_neigh_msg(skb, &_msg);
- if (msg)
- br_do_suppress_nd(skb, br, vid, p, msg);
- }
- 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->host_joined) ||
- 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, eth_hdr(skb)->h_dest, vid);
- default:
- break;
- }
- if (dst) {
- unsigned long now = jiffies;
- if (test_bit(BR_FDB_LOCAL, &dst->flags))
- 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) &&
- nbp_state_should_learn(p) &&
- !br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
- br_should_learn(p, skb, &vid))
- br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
- }
- /* 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;
- }
- static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
- {
- #ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
- struct nf_hook_entries *e = NULL;
- struct nf_hook_state state;
- unsigned int verdict, i;
- struct net *net;
- int ret;
- net = dev_net(skb->dev);
- #ifdef HAVE_JUMP_LABEL
- if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
- goto frame_finish;
- #endif
- e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
- if (!e)
- goto frame_finish;
- nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
- NFPROTO_BRIDGE, skb->dev, NULL, NULL,
- net, br_handle_frame_finish);
- for (i = 0; i < e->num_hook_entries; i++) {
- verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
- switch (verdict & NF_VERDICT_MASK) {
- case NF_ACCEPT:
- if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
- *pskb = skb;
- return RX_HANDLER_PASS;
- }
- break;
- case NF_DROP:
- kfree_skb(skb);
- return RX_HANDLER_CONSUMED;
- case NF_QUEUE:
- ret = nf_queue(skb, &state, i, verdict);
- if (ret == 1)
- continue;
- return RX_HANDLER_CONSUMED;
- default: /* STOLEN */
- return RX_HANDLER_CONSUMED;
- }
- }
- frame_finish:
- net = dev_net(skb->dev);
- br_handle_frame_finish(net, NULL, skb);
- #else
- br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
- #endif
- return RX_HANDLER_CONSUMED;
- }
- /*
- * Return NULL if skb is handled
- * note: already called with rcu_read_lock
- */
- static 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;
- 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;
- memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
- 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
- */
- fwd_mask |= p->group_fwd_mask;
- 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;
- }
- }
- if (unlikely(br_mrp_process(p, skb)))
- return RX_HANDLER_PASS;
- forward:
- switch (p->state) {
- case BR_STATE_FORWARDING:
- case BR_STATE_LEARNING:
- if (ether_addr_equal(p->br->dev->dev_addr, dest))
- skb->pkt_type = PACKET_HOST;
- return nf_hook_bridge_pre(skb, pskb);
- default:
- drop:
- kfree_skb(skb);
- }
- return RX_HANDLER_CONSUMED;
- }
- /* This function has no purpose other than to appease the br_port_get_rcu/rtnl
- * helpers which identify bridged ports according to the rx_handler installed
- * on them (so there _needs_ to be a bridge rx_handler even if we don't need it
- * to do anything useful). This bridge won't support traffic to/from the stack,
- * but only hardware bridging. So return RX_HANDLER_PASS so we don't steal
- * frames from the ETH_P_XDSA packet_type handler.
- */
- static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb)
- {
- return RX_HANDLER_PASS;
- }
- rx_handler_func_t *br_get_rx_handler(const struct net_device *dev)
- {
- if (netdev_uses_dsa(dev))
- return br_handle_frame_dummy;
- return br_handle_frame;
- }
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