path: root/net/bridge/br_fdb.c

/*
 *	Forwarding database
 *	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/kernel.h>
#include <linux/init.h>
#include <linux/rculist.h>
#include <linux/spinlock.h>
#include <linux/times.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/jhash.h>
#include <linux/random.h>
#include <linux/slab.h>
#include <linux/atomic.h>
#include <asm/unaligned.h>
#include <linux/if_vlan.h>
#include "br_private.h"

static struct kmem_cache *br_fdb_cache __read_mostly;
static struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
					     const unsigned char *addr,
					     __u16 vid);
static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
		      const unsigned char *addr, u16 vid);
static void fdb_notify(struct net_bridge *br,
		       const struct net_bridge_fdb_entry *, int);

static u32 fdb_salt __read_mostly;

int __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);
	if (!br_fdb_cache)
		return -ENOMEM;

	get_random_bytes(&fdb_salt, sizeof(fdb_salt));
	return 0;
}

void 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->updated + hold_time(br), jiffies);
}

static inline int br_mac_hash(const unsigned char *mac, __u16 vid)
{
	/* use 1 byte of OUI and 3 bytes of NIC */
	u32 key = get_unaligned((u32 *)(mac + 2));
	return jhash_2words(key, vid, fdb_salt) & (BR_HASH_SIZE - 1);
}

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

static void fdb_delete(struct net_bridge *br, struct net_bridge_fdb_entry *f)
{
	hlist_del_rcu(&f->hlist);
	fdb_notify(br, f, RTM_DELNEIGH);
	call_rcu(&f->rcu, fdb_rcu_free);
}

/* Delete a local entry if no other port had the same address. */
static void fdb_delete_local(struct net_bridge *br,
			     const struct net_bridge_port *p,
			     struct net_bridge_fdb_entry *f)
{
	const unsigned char *addr = f->addr.addr;
	u16 vid = f->vlan_id;
	struct net_bridge_port *op;

	/* Maybe another port has same hw addr? */
	list_for_each_entry(op, &br->port_list, list) {
		if (op != p && ether_addr_equal(op->dev->dev_addr, addr) &&
		    (!vid || nbp_vlan_find(op, vid))) {
			f->dst = op;
			f->added_by_user = 0;
			return;
		}
	}

	/* Maybe bridge device has same hw addr? */
	if (p && ether_addr_equal(br->dev->dev_addr, addr) &&
	    (!vid || br_vlan_find(br, vid))) {
		f->dst = NULL;
		f->added_by_user = 0;
		return;
	}

	fdb_delete(br, f);
}

void br_fdb_find_delete_local(struct net_bridge *br,
			      const struct net_bridge_port *p,
			      const unsigned char *addr, u16 vid)
{
	struct hlist_head *head = &br->hash[br_mac_hash(addr, vid)];
	struct net_bridge_fdb_entry *f;

	spin_lock_bh(&br->hash_lock);
	f = fdb_find(head, addr, vid);
	if (f && f->is_local && !f->added_by_user && f->dst == p)
		fdb_delete_local(br, p, f);
	spin_unlock_bh(&br->hash_lock);
}

void br_fdb_changeaddr(struct net_bridge_port *p, const unsigned char *newaddr)
{
	struct net_bridge *br = p->br;
	struct net_port_vlans *pv = nbp_get_vlan_info(p);
	bool no_vlan = !pv;
	int i;
	u16 vid;

	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