/net/bridge/br_forward.c

  1/*
  2 *	Forwarding decision
  3 *	Linux ethernet bridge
  4 *
  5 *	Authors:
  6 *	Lennert Buytenhek		<buytenh@gnu.org>
  7 *
  8 *	This program is free software; you can redistribute it and/or
  9 *	modify it under the terms of the GNU General Public License
 10 *	as published by the Free Software Foundation; either version
 11 *	2 of the License, or (at your option) any later version.
 12 */
 13
 14#include <linux/err.h>
 15#include <linux/slab.h>
 16#include <linux/kernel.h>
 17#include <linux/netdevice.h>
 18#include <linux/skbuff.h>
 19#include <linux/if_vlan.h>
 20#include <linux/netfilter_bridge.h>
 21#include "br_private.h"
 22
 23static int deliver_clone(const struct net_bridge_port *prev,
 24			 struct sk_buff *skb,
 25			 void (*__packet_hook)(const struct net_bridge_port *p,
 26					       struct sk_buff *skb));
 27
 28/* Don't forward packets to originating port or forwarding diasabled */
 29static inline int should_deliver(const struct net_bridge_port *p,
 30				 const struct sk_buff *skb)
 31{
 32	return (((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
 33		p->state == BR_STATE_FORWARDING);
 34}
 35
 36static inline unsigned packet_length(const struct sk_buff *skb)
 37{
 38	return skb->len - (skb->protocol == htons(ETH_P_8021Q) ? VLAN_HLEN : 0);
 39}
 40
 41int br_dev_queue_push_xmit(struct sk_buff *skb)
 42{
 43	/* drop mtu oversized packets except gso */
 44	if (packet_length(skb) > skb->dev->mtu && !skb_is_gso(skb))
 45		kfree_skb(skb);
 46	else {
 47		/* ip_refrag calls ip_fragment, doesn't copy the MAC header. */
 48		if (nf_bridge_maybe_copy_header(skb))
 49			kfree_skb(skb);
 50		else {
 51			skb_push(skb, ETH_HLEN);
 52
 53			dev_queue_xmit(skb);
 54		}
 55	}
 56
 57	return 0;
 58}
 59
 60int br_forward_finish(struct sk_buff *skb)
 61{
 62	return NF_HOOK(PF_BRIDGE, NF_BR_POST_ROUTING, skb, NULL, skb->dev,
 63		       br_dev_queue_push_xmit);
 64
 65}
 66
 67static void __br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 68{
 69	skb->dev = to->dev;
 70	NF_HOOK(PF_BRIDGE, NF_BR_LOCAL_OUT, skb, NULL, skb->dev,
 71			br_forward_finish);
 72}
 73
 74static void __br_forward(const struct net_bridge_port *to, struct sk_buff *skb)
 75{
 76	struct net_device *indev;
 77
 78	if (skb_warn_if_lro(skb)) {
 79		kfree_skb(skb);
 80		return;
 81	}
 82
 83	indev = skb->dev;
 84	skb->dev = to->dev;
 85	skb_forward_csum(skb);
 86
 87	NF_HOOK(PF_BRIDGE, NF_BR_FORWARD, skb, indev, skb->dev,
 88			br_forward_finish);
 89}
 90
 91/* called with rcu_read_lock */
 92void br_deliver(const struct net_bridge_port *to, struct sk_buff *skb)
 93{
 94	if (should_deliver(to, skb)) {
 95		__br_deliver(to, skb);
 96		return;
 97	}
 98
 99	kfree_skb(skb);
100}
101
102/* called with rcu_read_lock */
103void br_forward(const struct net_bridge_port *to, struct sk_buff *skb, struct sk_buff *skb0)
104{
105	if (should_deliver(to, skb)) {
106		if (skb0)
107			deliver_clone(to, skb, __br_forward);
108		else
109			__br_forward(to, skb);
110		return;
111	}
112
113	if (!skb0)
114		kfree_skb(skb);
115}
116
117static int deliver_clone(const struct net_bridge_port *prev,
118			 struct sk_buff *skb,
119			 void (*__packet_hook)(const struct net_bridge_port *p,
120					       struct sk_buff *skb))
121{
122	skb = skb_clone(skb, GFP_ATOMIC);
123	if (!skb) {
124		struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
125
126		dev->stats.tx_dropped++;
127		return -ENOMEM;
128	}
129
130	__packet_hook(prev, skb);
131	return 0;
132}
133
134static struct net_bridge_port *maybe_deliver(
135	struct net_bridge_port *prev, struct net_bridge_port *p,
136	struct sk_buff *skb,
137	void (*__packet_hook)(const struct net_bridge_port *p,
138			      struct sk_buff *skb))
139{
140	int err;
141
142	if (!should_deliver(p, skb))
143		return prev;
144
145	if (!prev)
146		goto out;
147
148	err = deliver_clone(prev, skb, __packet_hook);
149	if (err)
150		return ERR_PTR(err);
151
152out:
153	return p;
154}
155
156/* called under bridge lock */
157static void br_flood(struct net_bridge *br, struct sk_buff *skb,
158		     struct sk_buff *skb0,
159		     void (*__packet_hook)(const struct net_bridge_port *p,
160					   struct sk_buff *skb))
161{
162	struct net_bridge_port *p;
163	struct net_bridge_port *prev;
164
165	prev = NULL;
166
167	list_for_each_entry_rcu(p, &br->port_list, list) {
168		prev = maybe_deliver(prev, p, skb, __packet_hook);
169		if (IS_ERR(prev))
170			goto out;
171	}
172
173	if (!prev)
174		goto out;
175
176	if (skb0)
177		deliver_clone(prev, skb, __packet_hook);
178	else
179		__packet_hook(prev, skb);
180	return;
181
182out:
183	if (!skb0)
184		kfree_skb(skb);
185}
186
187
188/* called with rcu_read_lock */
189void br_flood_deliver(struct net_bridge *br, struct sk_buff *skb)
190{
191	br_flood(br, skb, NULL, __br_deliver);
192}
193
194/* called under bridge lock */
195void br_flood_forward(struct net_bridge *br, struct sk_buff *skb,
196		      struct sk_buff *skb2)
197{
198	br_flood(br, skb, skb2, __br_forward);
199}
200
201#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
202/* called with rcu_read_lock */
203static void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
204			       struct sk_buff *skb, struct sk_buff *skb0,
205			       void (*__packet_hook)(
206					const struct net_bridge_port *p,
207					struct sk_buff *skb))
208{
209	struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
210	struct net_bridge *br = netdev_priv(dev);
211	struct net_bridge_port *port;
212	struct net_bridge_port *lport, *rport;
213	struct net_bridge_port *prev;
214	struct net_bridge_port_group *p;
215	struct hlist_node *rp;
216
217	prev = NULL;
218
219	rp = br->router_list.first;
220	p = mdst ? mdst->ports : NULL;
221	while (p || rp) {
222		lport = p ? p->port : NULL;
223		rport = rp ? hlist_entry(rp, struct net_bridge_port, rlist) :
224			     NULL;
225
226		port = (unsigned long)lport > (unsigned long)rport ?
227		       lport : rport;
228
229		prev = maybe_deliver(prev, port, skb, __packet_hook);
230		if (IS_ERR(prev))
231			goto out;
232
233		if ((unsigned long)lport >= (unsigned long)port)
234			p = p->next;
235		if ((unsigned long)rport >= (unsigned long)port)
236			rp = rp->next;
237	}
238
239	if (!prev)
240		goto out;
241
242	if (skb0)
243		deliver_clone(prev, skb, __packet_hook);
244	else
245		__packet_hook(prev, skb);
246	return;
247
248out:
249	if (!skb0)
250		kfree_skb(skb);
251}
252
253/* called with rcu_read_lock */
254void br_multicast_deliver(struct net_bridge_mdb_entry *mdst,
255			  struct sk_buff *skb)
256{
257	br_multicast_flood(mdst, skb, NULL, __br_deliver);
258}
259
260/* called with rcu_read_lock */
261void br_multicast_forward(struct net_bridge_mdb_entry *mdst,
262			  struct sk_buff *skb, struct sk_buff *skb2)
263{
264	br_multicast_flood(mdst, skb, skb2, __br_forward);
265}
266#endif