/* * 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 <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 inline void fdb_delete(struct net_bridge_fdb_entry *f) { hlist_del_rcu(&f->hlist); 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 && !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; } /* 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_not_zero(&fdb->use_count)) fdb = NULL; 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, 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->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); /* 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); atomic_set(&fdb->use_count, 1); 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); } }