/* *	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/export.h>#include "br_private.h" /* Bridge group multicast address 802.1d (pg 51). */const u8 br_group_address[ETH_ALEN] = { 0x01, 0x80, 0xc2, 0x00, 0x00, 0x00 }; /* Hook for brouter */br_should_route_hook_t __rcu *br_should_route_hook __read_mostly;EXPORT_SYMBOL(br_should_route_hook); 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 br_cpu_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); 	indev = skb->dev;	skb->dev = brdev; 	return NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, indev, NULL,		       netif_receive_skb);} /* note: already called with rcu_read_lock */int br_handle_frame_finish(struct sk_buff *skb){	const unsigned char *dest = eth_hdr(skb)->h_dest;	struct net_bridge_port *p = br_port_get_rcu(skb->dev);	struct net_bridge *br;	struct net_bridge_fdb_entry *dst;	struct net_bridge_mdb_entry *mdst;	struct sk_buff *skb2; 	if (!p || p->state == BR_STATE_DISABLED)		goto drop; 	/* insert into forwarding database after filtering to avoid spoofing */	br = p->br;	br_fdb_update(br, p, eth_hdr(skb)->h_source); 	if (!is_broadcast_ether_addr(dest) && is_multicast_ether_addr(dest) &&	    br_multicast_rcv(br, p, skb))		goto drop; 	if (p->state == BR_STATE_LEARNING)		goto drop; 	BR_INPUT_SKB_CB(skb)->brdev = br->dev; 	/* The packet skb2 goes to the local host (NULL to skip). */	skb2 = NULL; 	if (br->dev->flags & IFF_PROMISC)		skb2 = skb; 	dst = NULL; 	if (is_broadcast_ether_addr(dest))		skb2 = skb;	else if (is_multicast_ether_addr(dest)) {		mdst = br_mdb_get(br, skb);		if (mdst || BR_INPUT_SKB_CB_MROUTERS_ONLY(skb)) {			if ((mdst && mdst->mglist) ||			    br_multicast_is_router(br))				skb2 = skb;			br_multicast_forward(mdst, skb, skb2);			skb = NULL;			if (!skb2)				goto out;		} else			skb2 = skb; 		br->dev->stats.multicast++;	} else if ((dst = __br_fdb_get(br, dest)) && dst->is_local) {		skb2 = skb;		/* Do not forward the packet since it's local. */		skb = NULL;	} 	if (skb) {		if (dst) {			dst->used = jiffies;			br_forward(dst->dst, skb, skb2);		} else			br_flood_forward(br, skb, skb2);	} 	if (skb2)		return br_pass_frame_up(skb2); out:	return 0;drop:	kfree_skb(skb);	goto out;} /* note: already called with rcu_read_lock */static int br_handle_local_finish(struct sk_buff *skb){	struct net_bridge_port *p = br_port_get_rcu(skb->dev); 	br_fdb_update(p->br, p, eth_hdr(skb)->h_source);	return 0;	 /* process further */} /* Does address match the link local multicast address. * 01:80:c2:00:00:0X */static inline int is_link_local(const unsigned char *dest){	__be16 *a = (__be16 *)dest;	static const __be16 *b = (const __be16 *)br_group_address;	static const __be16 m = cpu_to_be16(0xfff0); 	return ((a[0] ^ b[0]) | (a[1] ^ b[1]) | ((a[2] ^ b[2]) & m)) == 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 (unlikely(is_link_local(dest))) {		/*		 * 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)				goto forward;			break; 		case 0x01:	/* IEEE MAC (Pause) */			goto drop; 		default:			/* Allow selective forwarding for most other protocols */			if (p->br->group_fwd_mask & (1u << dest[5]))				goto forward;		} 		/* Deliver packet to local host only */		if (NF_HOOK(NFPROTO_BRIDGE, NF_BR_LOCAL_IN, skb, skb->dev,			    NULL, br_handle_local_finish)) {			return RX_HANDLER_CONSUMED; /* consumed by filter */		} else {			*pskb = skb;			return RX_HANDLER_PASS;	/* continue processing */		}	} 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, skb, skb->dev, NULL,			br_handle_frame_finish);		break;	default:drop:		kfree_skb(skb);	}	return RX_HANDLER_CONSUMED;}