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

 /*
  *	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)
 {
 	struct net_bridge_port *p = br_port_get_rcu(skb->dev);

 	__br_handle_local_finish(skb);

 	BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
 	br_pass_frame_up(skb);
 	return 0;
 }

 /*
  * 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;
 		}

 		/* Deliver packet to local host only */
 		NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
 			NULL, skb, skb->dev, NULL, br_handle_local_finish);
 		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;
 }
	/*
	* 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)
	{
	struct net_bridge_port *p = br_port_get_rcu(skb->dev);

	__br_handle_local_finish(skb);

	BR_INPUT_SKB_CB(skb)->brdev = p->br->dev;
	br_pass_frame_up(skb);
	return 0;
	}

	/*
	* 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;
	}

	/* Deliver packet to local host only */
	NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, dev_net(skb->dev),
	NULL, skb, skb->dev, NULL, br_handle_local_finish);
	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;
	}