359 lines
9.0 KiB
C
359 lines
9.0 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* Handle incoming frames
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* Linux ethernet bridge
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*
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* Authors:
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* Lennert Buytenhek <buytenh@gnu.org>
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*/
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#include <linux/slab.h>
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#include <linux/kernel.h>
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#include <linux/netdevice.h>
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#include <linux/etherdevice.h>
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#include <linux/netfilter_bridge.h>
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#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
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#include <net/netfilter/nf_queue.h>
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#endif
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#include <linux/neighbour.h>
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#include <net/arp.h>
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#include <linux/export.h>
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#include <linux/rculist.h>
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#include "br_private.h"
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#include "br_private_tunnel.h"
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static int
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br_netif_receive_skb(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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br_drop_fake_rtable(skb);
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return netif_receive_skb(skb);
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}
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static int br_pass_frame_up(struct sk_buff *skb)
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{
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struct net_device *indev, *brdev = BR_INPUT_SKB_CB(skb)->brdev;
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struct net_bridge *br = netdev_priv(brdev);
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struct net_bridge_vlan_group *vg;
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struct pcpu_sw_netstats *brstats = this_cpu_ptr(br->stats);
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u64_stats_update_begin(&brstats->syncp);
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brstats->rx_packets++;
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brstats->rx_bytes += skb->len;
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u64_stats_update_end(&brstats->syncp);
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vg = br_vlan_group_rcu(br);
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/* Bridge is just like any other port. Make sure the
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* packet is allowed except in promisc modue when someone
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* may be running packet capture.
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*/
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if (!(brdev->flags & IFF_PROMISC) &&
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!br_allowed_egress(vg, skb)) {
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kfree_skb(skb);
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return NET_RX_DROP;
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}
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indev = skb->dev;
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skb->dev = brdev;
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skb = br_handle_vlan(br, NULL, vg, skb);
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if (!skb)
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return NET_RX_DROP;
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/* update the multicast stats if the packet is IGMP/MLD */
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br_multicast_count(br, NULL, skb, br_multicast_igmp_type(skb),
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BR_MCAST_DIR_TX);
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return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
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dev_net(indev), NULL, skb, indev, NULL,
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br_netif_receive_skb);
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}
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/* note: already called with rcu_read_lock */
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int br_handle_frame_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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struct net_bridge_port *p = br_port_get_rcu(skb->dev);
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enum br_pkt_type pkt_type = BR_PKT_UNICAST;
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struct net_bridge_fdb_entry *dst = NULL;
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struct net_bridge_mdb_entry *mdst;
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bool local_rcv, mcast_hit = false;
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struct net_bridge *br;
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u16 vid = 0;
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u8 state;
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if (!p || p->state == BR_STATE_DISABLED)
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goto drop;
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state = p->state;
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if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
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&state))
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goto out;
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nbp_switchdev_frame_mark(p, skb);
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/* insert into forwarding database after filtering to avoid spoofing */
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br = p->br;
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if (p->flags & BR_LEARNING)
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br_fdb_update(br, p, eth_hdr(skb)->h_source, vid, 0);
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local_rcv = !!(br->dev->flags & IFF_PROMISC);
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if (is_multicast_ether_addr(eth_hdr(skb)->h_dest)) {
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/* by definition the broadcast is also a multicast address */
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if (is_broadcast_ether_addr(eth_hdr(skb)->h_dest)) {
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pkt_type = BR_PKT_BROADCAST;
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local_rcv = true;
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} else {
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pkt_type = BR_PKT_MULTICAST;
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if (br_multicast_rcv(br, p, skb, vid))
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goto drop;
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}
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}
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if (state == BR_STATE_LEARNING)
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goto drop;
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BR_INPUT_SKB_CB(skb)->brdev = br->dev;
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BR_INPUT_SKB_CB(skb)->src_port_isolated = !!(p->flags & BR_ISOLATED);
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if (IS_ENABLED(CONFIG_INET) &&
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(skb->protocol == htons(ETH_P_ARP) ||
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skb->protocol == htons(ETH_P_RARP))) {
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br_do_proxy_suppress_arp(skb, br, vid, p);
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} else if (IS_ENABLED(CONFIG_IPV6) &&
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skb->protocol == htons(ETH_P_IPV6) &&
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br_opt_get(br, BROPT_NEIGH_SUPPRESS_ENABLED) &&
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pskb_may_pull(skb, sizeof(struct ipv6hdr) +
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sizeof(struct nd_msg)) &&
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ipv6_hdr(skb)->nexthdr == IPPROTO_ICMPV6) {
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struct nd_msg *msg, _msg;
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msg = br_is_nd_neigh_msg(skb, &_msg);
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if (msg)
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br_do_suppress_nd(skb, br, vid, p, msg);
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}
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switch (pkt_type) {
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case BR_PKT_MULTICAST:
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mdst = br_mdb_get(br, skb, vid);
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if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
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br_multicast_querier_exists(br, eth_hdr(skb))) {
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if ((mdst && mdst->host_joined) ||
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br_multicast_is_router(br)) {
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local_rcv = true;
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br->dev->stats.multicast++;
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}
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mcast_hit = true;
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} else {
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local_rcv = true;
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br->dev->stats.multicast++;
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}
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break;
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case BR_PKT_UNICAST:
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dst = br_fdb_find_rcu(br, eth_hdr(skb)->h_dest, vid);
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default:
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break;
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}
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if (dst) {
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unsigned long now = jiffies;
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if (test_bit(BR_FDB_LOCAL, &dst->flags))
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return br_pass_frame_up(skb);
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if (now != dst->used)
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dst->used = now;
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br_forward(dst->dst, skb, local_rcv, false);
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} else {
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if (!mcast_hit)
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br_flood(br, skb, pkt_type, local_rcv, false);
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else
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br_multicast_flood(mdst, skb, local_rcv, false);
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}
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if (local_rcv)
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return br_pass_frame_up(skb);
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out:
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return 0;
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drop:
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kfree_skb(skb);
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goto out;
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}
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EXPORT_SYMBOL_GPL(br_handle_frame_finish);
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static void __br_handle_local_finish(struct sk_buff *skb)
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{
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struct net_bridge_port *p = br_port_get_rcu(skb->dev);
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u16 vid = 0;
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/* check if vlan is allowed, to avoid spoofing */
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if ((p->flags & BR_LEARNING) &&
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nbp_state_should_learn(p) &&
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!br_opt_get(p->br, BROPT_NO_LL_LEARN) &&
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br_should_learn(p, skb, &vid))
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br_fdb_update(p->br, p, eth_hdr(skb)->h_source, vid, 0);
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}
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/* note: already called with rcu_read_lock */
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static int br_handle_local_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
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{
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__br_handle_local_finish(skb);
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/* return 1 to signal the okfn() was called so it's ok to use the skb */
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return 1;
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}
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static int nf_hook_bridge_pre(struct sk_buff *skb, struct sk_buff **pskb)
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{
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#ifdef CONFIG_NETFILTER_FAMILY_BRIDGE
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struct nf_hook_entries *e = NULL;
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struct nf_hook_state state;
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unsigned int verdict, i;
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struct net *net;
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int ret;
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net = dev_net(skb->dev);
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#ifdef HAVE_JUMP_LABEL
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if (!static_key_false(&nf_hooks_needed[NFPROTO_BRIDGE][NF_BR_PRE_ROUTING]))
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goto frame_finish;
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#endif
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e = rcu_dereference(net->nf.hooks_bridge[NF_BR_PRE_ROUTING]);
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if (!e)
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goto frame_finish;
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nf_hook_state_init(&state, NF_BR_PRE_ROUTING,
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NFPROTO_BRIDGE, skb->dev, NULL, NULL,
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net, br_handle_frame_finish);
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for (i = 0; i < e->num_hook_entries; i++) {
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verdict = nf_hook_entry_hookfn(&e->hooks[i], skb, &state);
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switch (verdict & NF_VERDICT_MASK) {
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case NF_ACCEPT:
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if (BR_INPUT_SKB_CB(skb)->br_netfilter_broute) {
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*pskb = skb;
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return RX_HANDLER_PASS;
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}
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break;
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case NF_DROP:
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kfree_skb(skb);
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return RX_HANDLER_CONSUMED;
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case NF_QUEUE:
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ret = nf_queue(skb, &state, i, verdict);
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if (ret == 1)
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continue;
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return RX_HANDLER_CONSUMED;
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default: /* STOLEN */
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return RX_HANDLER_CONSUMED;
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}
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}
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frame_finish:
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net = dev_net(skb->dev);
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br_handle_frame_finish(net, NULL, skb);
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#else
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br_handle_frame_finish(dev_net(skb->dev), NULL, skb);
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#endif
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return RX_HANDLER_CONSUMED;
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}
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/*
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* Return NULL if skb is handled
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* note: already called with rcu_read_lock
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*/
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rx_handler_result_t br_handle_frame(struct sk_buff **pskb)
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{
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struct net_bridge_port *p;
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struct sk_buff *skb = *pskb;
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const unsigned char *dest = eth_hdr(skb)->h_dest;
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if (unlikely(skb->pkt_type == PACKET_LOOPBACK))
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return RX_HANDLER_PASS;
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if (!is_valid_ether_addr(eth_hdr(skb)->h_source))
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goto drop;
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skb = skb_share_check(skb, GFP_ATOMIC);
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if (!skb)
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return RX_HANDLER_CONSUMED;
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memset(skb->cb, 0, sizeof(struct br_input_skb_cb));
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p = br_port_get_rcu(skb->dev);
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if (p->flags & BR_VLAN_TUNNEL) {
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if (br_handle_ingress_vlan_tunnel(skb, p,
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nbp_vlan_group_rcu(p)))
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goto drop;
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}
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if (unlikely(is_link_local_ether_addr(dest))) {
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u16 fwd_mask = p->br->group_fwd_mask_required;
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/*
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* See IEEE 802.1D Table 7-10 Reserved addresses
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*
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* Assignment Value
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* Bridge Group Address 01-80-C2-00-00-00
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* (MAC Control) 802.3 01-80-C2-00-00-01
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* (Link Aggregation) 802.3 01-80-C2-00-00-02
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* 802.1X PAE address 01-80-C2-00-00-03
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*
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* 802.1AB LLDP 01-80-C2-00-00-0E
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*
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* Others reserved for future standardization
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*/
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fwd_mask |= p->group_fwd_mask;
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switch (dest[5]) {
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case 0x00: /* Bridge Group Address */
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/* If STP is turned off,
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then must forward to keep loop detection */
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if (p->br->stp_enabled == BR_NO_STP ||
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fwd_mask & (1u << dest[5]))
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goto forward;
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*pskb = skb;
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__br_handle_local_finish(skb);
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return RX_HANDLER_PASS;
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case 0x01: /* IEEE MAC (Pause) */
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goto drop;
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case 0x0E: /* 802.1AB LLDP */
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fwd_mask |= p->br->group_fwd_mask;
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if (fwd_mask & (1u << dest[5]))
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goto forward;
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*pskb = skb;
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__br_handle_local_finish(skb);
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return RX_HANDLER_PASS;
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default:
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/* Allow selective forwarding for most other protocols */
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fwd_mask |= p->br->group_fwd_mask;
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if (fwd_mask & (1u << dest[5]))
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goto forward;
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}
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/* The else clause should be hit when nf_hook():
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* - returns < 0 (drop/error)
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* - returns = 0 (stolen/nf_queue)
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* Thus return 1 from the okfn() to signal the skb is ok to pass
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*/
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if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN,
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dev_net(skb->dev), NULL, skb, skb->dev, NULL,
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br_handle_local_finish) == 1) {
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return RX_HANDLER_PASS;
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} else {
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return RX_HANDLER_CONSUMED;
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}
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}
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forward:
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switch (p->state) {
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case BR_STATE_FORWARDING:
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case BR_STATE_LEARNING:
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if (ether_addr_equal(p->br->dev->dev_addr, dest))
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skb->pkt_type = PACKET_HOST;
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return nf_hook_bridge_pre(skb, pskb);
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default:
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drop:
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kfree_skb(skb);
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}
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return RX_HANDLER_CONSUMED;
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}
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