net/bridge/br_input.c - linux - Git at Google

 // 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;

 	dev_sw_netstats_rx_add(brdev, skb->len);

 	vg = br_vlan_group_rcu(br);
 	/* Bridge is just like any other port.  Make sure the
 	 * packet is allowed except in promisc mode 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_mcast_port *pmctx;
 	struct net_bridge_mdb_entry *mdst;
 	bool local_rcv, mcast_hit = false;
 	struct net_bridge_mcast *brmctx;
 	struct net_bridge_vlan *vlan;
 	struct net_bridge *br;
 	u16 vid = 0;
 	u8 state;

 	if (!p || p->state == BR_STATE_DISABLED)
 		goto drop;

 	brmctx = &p->br->multicast_ctx;
 	pmctx = &p->multicast_ctx;
 	state = p->state;
 	if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
 				&state, &vlan))
 		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(&brmctx, &pmctx, vlan, 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(brmctx, skb, vid);
 		if ((mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
 		    br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
 			if ((mdst && mdst->host_joined) ||
 			    br_multicast_is_router(brmctx, skb)) {
 				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);
 		break;
 	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, brmctx, 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 0 if the frame was not processed otherwise 1
  * note: already called with rcu_read_lock
  */
 static int br_process_frame_type(struct net_bridge_port *p,
 				 struct sk_buff *skb)
 {
 	struct br_frame_type *tmp;

 	hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
 		if (unlikely(tmp->type == skb->protocol))
 			return tmp->frame_handler(p, skb);

 	return 0;
 }

 /*
  * 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)
 		br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));

 	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_process_frame_type(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;
 }

 void br_add_frame(struct net_bridge *br, struct br_frame_type *ft)
 {
 	hlist_add_head_rcu(&ft->list, &br->frame_type_list);
 }

 void br_del_frame(struct net_bridge *br, struct br_frame_type *ft)
 {
 	struct br_frame_type *tmp;

 	hlist_for_each_entry(tmp, &br->frame_type_list, list)
 		if (ft == tmp) {
 			hlist_del_rcu(&ft->list);
 			return;
 		}
 }
	// 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;

	dev_sw_netstats_rx_add(brdev, skb->len);

	vg = br_vlan_group_rcu(br);
	/* Bridge is just like any other port. Make sure the
	* packet is allowed except in promisc mode 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_mcast_port *pmctx;
	struct net_bridge_mdb_entry *mdst;
	bool local_rcv, mcast_hit = false;
	struct net_bridge_mcast *brmctx;
	struct net_bridge_vlan *vlan;
	struct net_bridge *br;
	u16 vid = 0;
	u8 state;

	if (!p \|\| p->state == BR_STATE_DISABLED)
	goto drop;

	brmctx = &p->br->multicast_ctx;
	pmctx = &p->multicast_ctx;
	state = p->state;
	if (!br_allowed_ingress(p->br, nbp_vlan_group_rcu(p), skb, &vid,
	&state, &vlan))
	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(&brmctx, &pmctx, vlan, 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(brmctx, skb, vid);
	if ((mdst \|\| BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) &&
	br_multicast_querier_exists(brmctx, eth_hdr(skb), mdst)) {
	if ((mdst && mdst->host_joined) \|\|
	br_multicast_is_router(brmctx, skb)) {
	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);
	break;
	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, brmctx, 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 0 if the frame was not processed otherwise 1
	* note: already called with rcu_read_lock
	*/
	static int br_process_frame_type(struct net_bridge_port *p,
	struct sk_buff *skb)
	{
	struct br_frame_type *tmp;

	hlist_for_each_entry_rcu(tmp, &p->br->frame_type_list, list)
	if (unlikely(tmp->type == skb->protocol))
	return tmp->frame_handler(p, skb);

	return 0;
	}

	/*
	* 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)
	br_handle_ingress_vlan_tunnel(skb, p, nbp_vlan_group_rcu(p));

	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_process_frame_type(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;
	}

	void br_add_frame(struct net_bridge br, struct br_frame_type ft)
	{
	hlist_add_head_rcu(&ft->list, &br->frame_type_list);
	}

	void br_del_frame(struct net_bridge br, struct br_frame_type ft)
	{
	struct br_frame_type *tmp;

	hlist_for_each_entry(tmp, &br->frame_type_list, list)
	if (ft == tmp) {
	hlist_del_rcu(&ft->list);
	return;
	}
	}