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412 lines
11 KiB
412 lines
11 KiB
// 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 <[email protected]> |
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*/ |
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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 <net/dsa.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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dev_sw_netstats_rx_add(brdev, skb->len); |
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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 mode 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_mcast_port *pmctx; |
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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_mcast *brmctx; |
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struct net_bridge_vlan *vlan; |
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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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brmctx = &p->br->multicast_ctx; |
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pmctx = &p->multicast_ctx; |
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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, &vlan)) |
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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(&brmctx, &pmctx, vlan, 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(brmctx, skb, vid); |
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if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) && |
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br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) { |
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if ((mdst && mdst->host_joined) || |
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br_multicast_is_router(brmctx, skb)) { |
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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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break; |
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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, brmctx, 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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/* Return 0 if the frame was not processed otherwise 1 |
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* note: already called with rcu_read_lock |
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*/ |
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static int br_process_frame_type(struct net_bridge_port *p, |
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struct sk_buff *skb) |
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{ |
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struct br_frame_type *tmp; |
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hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list) |
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if (unlikely(tmp->type == skb->protocol)) |
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return tmp->frame_handler(p, skb); |
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return 0; |
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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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static 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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br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p)); |
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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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if (unlikely(br_process_frame_type(p, skb))) |
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return RX_HANDLER_PASS; |
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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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/* This function has no purpose other than to appease the br_port_get_rcu/rtnl |
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* helpers which identify bridged ports according to the rx_handler installed |
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* on them (so there _needs_ to be a bridge rx_handler even if we don't need it |
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* to do anything useful). This bridge won't support traffic to/from the stack, |
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* but only hardware bridging. So return RX_HANDLER_PASS so we don't steal |
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* frames from the ETH_P_XDSA packet_type handler. |
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*/ |
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static rx_handler_result_t br_handle_frame_dummy(struct sk_buff **pskb) |
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{ |
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return RX_HANDLER_PASS; |
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} |
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rx_handler_func_t *br_get_rx_handler(const struct net_device *dev) |
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{ |
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if (netdev_uses_dsa(dev)) |
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return br_handle_frame_dummy; |
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return br_handle_frame; |
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} |
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void br_add_frame(struct net_bridge *br, struct br_frame_type *ft) |
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{ |
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hlist_add_head_rcu(&ft->list, &br->frame_type_list); |
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} |
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void br_del_frame(struct net_bridge *br, struct br_frame_type *ft) |
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{ |
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struct br_frame_type *tmp; |
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hlist_for_each_entry(tmp, &br->frame_type_list, list) |
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if (ft == tmp) { |
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hlist_del_rcu(&ft->list); |
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return; |
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} |
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}
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