br_fdb.c

Linux Kernel 2.6.9 for OMAP1710

/*
 *	Forwarding database
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<[e-mail]>
 *
 *	$Id: br_fdb.c,v 1.6 2002/01/17 00:57:07 davem Exp $
 *
 *	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/kernel.h>
#include <linux/init.h>
#include <linux/spinlock.h>
#include <linux/times.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <asm/atomic.h>
#include "br_private.h"

static kmem_cache_t *br_fdb_cache;
static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
		      const unsigned char *addr, int is_local);

void __init br_fdb_init(void)
{
	br_fdb_cache = kmem_cache_create("bridge_fdb_cache",
					 sizeof(struct net_bridge_fdb_entry),
					 0,
					 SLAB_HWCACHE_ALIGN, NULL, NULL);
}

void __exit br_fdb_fini(void)
{
	kmem_cache_destroy(br_fdb_cache);
}


/* if topology_changing then use forward_delay (default 15 sec)
 * otherwise keep longer (default 5 minutes)
 */
static __inline__ unsigned long hold_time(const struct net_bridge *br)
{
	return br->topology_change ? br->forward_delay : br->ageing_time;
}

static __inline__ int has_expired(const struct net_bridge *br,
				  const struct net_bridge_fdb_entry *fdb)
{
	return !fdb->is_static 
		&& time_before_eq(fdb->ageing_timer + hold_time(br), jiffies);
}

static __inline__ int br_mac_hash(const unsigned char *mac)
{
	unsigned long x;

	x = mac[0];
	x = (x << 2) ^ mac[1];
	x = (x << 2) ^ mac[2];
	x = (x << 2) ^ mac[3];
	x = (x << 2) ^ mac[4];
	x = (x << 2) ^ mac[5];

	x ^= x >> 8;

	return x & (BR_HASH_SIZE - 1);
}

static __inline__ void fdb_delete(struct net_bridge_fdb_entry *f)
{
	hlist_del_rcu(&f->hlist);
	if (!f->is_static)
		list_del(&f->u.age_list);

	br_fdb_put(f);
}

void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
{
	struct net_bridge *br = p->br;
	int i;
	
	spin_lock_bh(&br->hash_lock);

	/* Search all chains since old address/hash is unknown */
	for (i = 0; i < BR_HASH_SIZE; i++) {
		struct hlist_node *h;
		hlist_for_each(h, &br->hash[i]) {
			struct net_bridge_fdb_entry *f;

			f = hlist_entry(h, struct net_bridge_fdb_entry, hlist);
			if (f->dst == p && f->is_local) {
				/* maybe another port has same hw addr? */
				struct net_bridge_port *op;
				list_for_each_entry(op, &br->port_list, list) {
					if (op != p && 
					    !memcmp(op->dev->dev_addr,
						    f->addr.addr, ETH_ALEN)) {
						f->dst = op;
						goto insert;
					}
				}

				/* delete old one */
				fdb_delete(f);
				goto insert;
			}
		}
	}
 insert:
	/* insert new address,  may fail if invalid address or dup. */
	fdb_insert(br, p, newaddr, 1);


	spin_unlock_bh(&br->hash_lock);
}

void br_fdb_cleanup(unsigned long _data)
{
	struct net_bridge *br = (struct net_bridge *)_data;
	struct list_head *l, *n;
	unsigned long delay;

	spin_lock_bh(&br->hash_lock);
	delay = hold_time(br);

	list_for_each_safe(l, n, &br->age_list) {
		struct net_bridge_fdb_entry *f;
		unsigned long expires;

		f = list_entry(l, struct net_bridge_fdb_entry, u.age_list);
		expires = f->ageing_timer + delay;

		if (time_before_eq(expires, jiffies)) {
			WARN_ON(f->is_static);
			pr_debug("expire age %lu jiffies %lu\n",
				 f->ageing_timer, jiffies);
			fdb_delete(f);
		} else {
			mod_timer(&br->gc_timer, expires);
			break;
		}
	}
	spin_unlock_bh(&br->hash_lock);
}

void br_fdb_delete_by_port(struct net_bridge *br, struct net_bridge_port *p)
{
	int i;

	spin_lock_bh(&br->hash_lock);
	for (i = 0; i < BR_HASH_SIZE; i++) {
		struct hlist_node *h, *g;
		
		hlist_for_each_safe(h, g, &br->hash[i]) {
			struct net_bridge_fdb_entry *f
				= hlist_entry(h, struct net_bridge_fdb_entry, hlist);
			if (f->dst != p) 
				continue;

			/*
			 * if multiple ports all have the same device address
			 * then when one port is deleted, assign
			 * the local entry to other port
			 */
			if (f->is_local) {
				struct net_bridge_port *op;
				list_for_each_entry(op, &br->port_list, list) {
					if (op != p && 
					    !memcmp(op->dev->dev_addr,
						    f->addr.addr, ETH_ALEN)) {
						f->dst = op;
						goto skip_delete;
					}
				}
			}

			fdb_delete(f);
		skip_delete: ;
		}
	}
	spin_unlock_bh(&br->hash_lock);
}

/* No locking or refcounting, assumes caller has no preempt (rcu_read_lock) */
struct net_bridge_fdb_entry *__br_fdb_get(struct net_bridge *br,
					  const unsigned char *addr)
{
	struct hlist_node *h;
	struct net_bridge_fdb_entry *fdb;

	hlist_for_each_entry_rcu(fdb, h, &br->hash[br_mac_hash(addr)], hlist) {
		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
			if (unlikely(has_expired(br, fdb)))
				break;
			return fdb;
		}
	}

	return NULL;
}

/* Interface used by ATM hook that keeps a ref count */
struct net_bridge_fdb_entry *br_fdb_get(struct net_bridge *br, 
					unsigned char *addr)
{
	struct net_bridge_fdb_entry *fdb;

	rcu_read_lock();
	fdb = __br_fdb_get(br, addr);
	if (fdb) 
		atomic_inc(&fdb->use_count);
	rcu_read_unlock();
	return fdb;
}

static void fdb_rcu_free(struct rcu_head *head)
{
	struct net_bridge_fdb_entry *ent
		= container_of(head, struct net_bridge_fdb_entry, u.rcu);
	kmem_cache_free(br_fdb_cache, ent);
}

/* Set entry up for deletion with RCU  */
void br_fdb_put(struct net_bridge_fdb_entry *ent)
{
	if (atomic_dec_and_test(&ent->use_count))
		call_rcu(&ent->u.rcu, fdb_rcu_free);
}

/*
 * Fill buffer with forwarding table records in 
 * the API format.
 */
int br_fdb_fillbuf(struct net_bridge *br, void *buf,
		   unsigned long maxnum, unsigned long skip)
{
	struct __fdb_entry *fe = buf;
	int i, num = 0;
	struct hlist_node *h;
	struct net_bridge_fdb_entry *f;

	memset(buf, 0, maxnum*sizeof(struct __fdb_entry));

	rcu_read_lock();
	for (i = 0; i < BR_HASH_SIZE; i++) {
		hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
			if (num >= maxnum)
				goto out;

			if (has_expired(br, f)) 
				continue;

			if (skip) {
				--skip;
				continue;
			}

			/* convert from internal format to API */
			memcpy(fe->mac_addr, f->addr.addr, ETH_ALEN);
			fe->port_no = f->dst->port_no;
			fe->is_local = f->is_local;
			if (!f->is_static)
				fe->ageing_timer_value = jiffies_to_clock_t(jiffies - f->ageing_timer);
			++fe;
			++num;
		}
	}

 out:
	rcu_read_unlock();

	return num;
}

static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
		  const unsigned char *addr, int is_local)
{
	struct hlist_node *h;
	struct net_bridge_fdb_entry *fdb;
	int hash = br_mac_hash(addr);

	if (!is_valid_ether_addr(addr))
		return -EADDRNOTAVAIL;

	hlist_for_each_entry(fdb, h, &br->hash[hash], hlist) {
		if (!memcmp(fdb->addr.addr, addr, ETH_ALEN)) {
			/* attempt to update an entry for a local interface */
			if (fdb->is_local) {
				/* it is okay to have multiple ports with same 
				 * address, just don't allow to be spoofed.
				 */
				if (is_local) 
					return 0;

				if (net_ratelimit()) 
					printk(KERN_WARNING "%s: received packet with "
					       " own address as source address\n",
					       source->dev->name);
				return -EEXIST;
			}

			if (is_local) {
				printk(KERN_WARNING "%s adding interface with same address "
				       "as a received packet\n",
				       source->dev->name);
				goto update;
			}

			if (fdb->is_static)
				return 0;

			/* move to end of age list */
			list_del(&fdb->u.age_list);
			goto update;
		}
	}

	fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
	if (!fdb)
		return ENOMEM;

	memcpy(fdb->addr.addr, addr, ETH_ALEN);
	atomic_set(&fdb->use_count, 1);
	hlist_add_head_rcu(&fdb->hlist, &br->hash[hash]);

	if (!timer_pending(&br->gc_timer)) {
		br->gc_timer.expires = jiffies + hold_time(br);
		add_timer(&br->gc_timer);
	}

 update:
	fdb->dst = source;
	fdb->is_local = is_local;
	fdb->is_static = is_local;
	fdb->ageing_timer = jiffies;
	if (!is_local) 
		list_add_tail(&fdb->u.age_list, &br->age_list);

	return 0;
}

int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
		  const unsigned char *addr, int is_local)
{
	int ret;

	spin_lock_bh(&br->hash_lock);
	ret = fdb_insert(br, source, addr, is_local);
	spin_unlock_bh(&br->hash_lock);
	return ret;
}