/*
* 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 <asm/atomic.h>
#include <asm/unaligned.h>
#include "br_private.h"
static struct kmem_cache *br_fdb_cache __read_mostly;
static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr);
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->ageing_timer + hold_time(br), jiffies);
}
static inline int br_mac_hash(const unsigned char *mac)
{
/* use 1 byte of OUI cnd 3 bytes of NIC */
u32 key = get_unaligned((u32 *)(mac + 2));
return jhash_1word(key, 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 inline void fdb_delete(struct net_bridge_fdb_entry *f)
{
hlist_del_rcu(&f->hlist);
call_rcu(&f->rcu, fdb_rcu_free);
}
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 &&
!compare_ether_addr(op->dev->dev_addr,
f->addr.addr)) {
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);
spin_unlock_bh(&br->hash_lock);
}
void br_fdb_cleanup(unsigned long _data)
{
struct net_bridge *br = (struct net_bridge *)_data;
unsigned long delay = hold_time(br);
unsigned long next_timer = jiffies + br->forward_delay;
int i;
spin_lock_bh(&br->hash_lock);
for (i = 0; i < BR_HASH_SIZE; i++) {
struct net_bridge_fdb_entry *f;
struct hlist_node *h, *n;
hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
unsigned long this_timer;
if (f->is_static)
continue;
this_timer = f->ageing_timer + delay;
if (time_before_eq(this_timer, jiffies))
fdb_delete(f);
else if (time_before(this_timer, next_timer))
next_timer = this_timer;
}
}
spin_unlock_bh(&br->hash_lock);
/* Add HZ/4 to ensure we round the jiffies upwards to be after the next
* timer, otherwise we might round down and will have no-op run. */
mod_timer(&br->gc_timer, round_jiffies(next_timer + HZ/4));
}
/* Completely flush all dynamic entries in forwarding database.*/
void br_fdb_flush(struct net_bridge *br)
{
int i;
spin_lock_bh(&br->hash_lock);
for (i = 0; i < BR_HASH_SIZE; i++) {
struct net_bridge_fdb_entry *f;
struct hlist_node *h, *n;
hlist_for_each_entry_safe(f, h, n, &br->hash[i], hlist) {
if (!f->is_static)
fdb_delete(f);
}
}
spin_unlock_bh(&br->hash_lock);
}
/* Flush all entries refering to a specific port.
* if do_all is set also flush static entries
*/
void br_fdb_delete_by_port(struct net_bridge *br,
const struct net_bridge_port *p,
int do_all)
{
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 (f->is_static && !do_all)
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 &&
!compare_ether_addr(op->dev->dev_addr,
f->addr.addr)) {
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 (!compare_ether_addr(fdb->addr.addr, addr)) {
if (unlikely(has_expired(br, fdb)))
break;
return fdb;
}
}
return NULL;
}
#if defined(CONFIG_ATM_LANE) || defined(CONFIG_ATM_LANE_MODULE)
/* Interface used by ATM LANE hook to test
* if an addr is on some other bridge port */
int br_fdb_test_addr(struct net_device *dev, unsigned char *addr)
{
struct net_bridge_fdb_entry *fdb;
int ret;
if (!dev->br_port)
return 0;
rcu_read_lock();
fdb = __br_fdb_get(dev->br_port->br, addr);
ret = fdb && fdb->dst->dev != dev &&
fdb->dst->state == BR_STATE_FORWARDING;
rcu_read_unlock();
return ret;
}
#endif /* CONFIG_ATM_LANE */
/*
* 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);
/* due to ABI compat need to split into hi/lo */
fe->port_no = f->dst->port_no;
fe->port_hi = f->dst->port_no >> 8;
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 inline struct net_bridge_fdb_entry *fdb_find(struct hlist_head *head,
const unsigned char *addr)
{
struct hlist_node *h;
struct net_bridge_fdb_entry *fdb;
hlist_for_each_entry_rcu(fdb, h, head, hlist) {
if (!compare_ether_addr(fdb->addr.addr, addr))
return fdb;
}
return NULL;
}
static struct net_bridge_fdb_entry *fdb_create(struct hlist_head *head,
struct net_bridge_port *source,
const unsigned char *addr,
int is_local)
{
struct net_bridge_fdb_entry *fdb;
fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
if (fdb) {
memcpy(fdb->addr.addr, addr, ETH_ALEN);
hlist_add_head_rcu(&fdb->hlist, head);
fdb->dst = source;
fdb->is_local = is_local;
fdb->is_static = is_local;
fdb->ageing_timer = jiffies;
}
return fdb;
}
static int fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr)
{
struct hlist_head *head = &br->hash[br_mac_hash(addr)];
struct net_bridge_fdb_entry *fdb;
if (!is_valid_ether_addr(addr))
return -EINVAL;
fdb = fdb_find(head, addr);
if (fdb) {
/* it is okay to have multiple ports with same
* address, just use the first one.
*/
if (fdb->is_local)
return 0;
printk(KERN_WARNING "%s adding interface with same address "
"as a received packet\n",
source->dev->name);
fdb_delete(fdb);
}
if (!fdb_create(head, source, addr, 1))
return -ENOMEM;
return 0;
}
int br_fdb_insert(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr)
{
int ret;
spin_lock_bh(&br->hash_lock);
ret = fdb_insert(br, source, addr);
spin_unlock_bh(&br->hash_lock);
return ret;
}
void br_fdb_update(struct net_bridge *br, struct net_bridge_port *source,
const unsigned char *addr)
{
struct hlist_head *head = &br->hash[br_mac_hash(addr)];
struct net_bridge_fdb_entry *fdb;
/* some users want to always flood. */
if (hold_time(br) == 0)
return;
/* ignore packets unless we are using this port */
if (!(source->state == BR_STATE_LEARNING ||
source->state == BR_STATE_FORWARDING))
return;
fdb = fdb_find(head, addr);
if (likely(fdb)) {
/* attempt to update an entry for a local interface */
if (unlikely(fdb->is_local)) {
if (net_ratelimit())
printk(KERN_WARNING "%s: received packet with "
"own address as source address\n",
source->dev->name);
} else {
/* fastpath: update of existing entry */
fdb->dst = source;
fdb->ageing_timer = jiffies;
}
} else {
spin_lock(&br->hash_lock);
if (!fdb_find(head, addr))
fdb_create(head, source, addr, 0);
/* else we lose race and someone else inserts
* it first, don't bother updating
*/
spin_unlock(&br->hash_lock);
}
}
