path: root/net/bridge/br_fdb.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 *	Forwarding database
 *	Linux ethernet bridge
 *
 *	Authors:
 *	Lennert Buytenhek		<buytenh@gnu.org>
 */

#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 <net/switchdev.h>
#include <trace/events/bridge.h>
#include "br_private.h"

static const struct rhashtable_params br_fdb_rht_params = {
	.head_offset = offsetof(struct net_bridge_fdb_entry, rhnode),
	.key_offset = offsetof(struct net_bridge_fdb_entry, key),
	.key_len = sizeof(struct net_bridge_fdb_key),
	.automatic_shrinking = true,
};

static struct kmem_cache *br_fdb_cache __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;

	return 0;
}

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

int br_fdb_hash_init(struct net_bridge *br)
{
	return rhashtable_init(&br->fdb_hash_tbl, &br_fdb_rht_params);
}

void br_fdb_hash_fini(struct net_bridge *br)
{
	rhashtable_destroy(&br->fdb_hash_tbl);
}

/* 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 !test_bit(BR_FDB_STATIC, &fdb->flags) &&
	       !test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags) &&
	       time_before_eq(fdb->updated + hold_time(br), jiffies);
}

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 int fdb_to_nud(const struct net_bridge *br,
		      const struct net_bridge_fdb_entry *fdb)
{
	if (test_bit(BR_FDB_LOCAL, &fdb->flags))
		return NUD_PERMANENT;
	else if (test_bit(BR_FDB_STATIC, &fdb->flags))
		return NUD_NOARP;
	else if (has_expired(br, fdb))
		return NUD_STALE;
	else
		return NUD_REACHABLE;
}

static int fdb_fill_info(struct sk_buff *skb, const struct net_bridge *br,
			 const struct net_bridge_fdb_entry *fdb,
			 u32 portid, u32 seq, int type, unsigned int flags)
{
	const struct net_bridge_port *dst = READ_ONCE(fdb->dst);
	unsigned long now = jiffies;
	struct nda_cacheinfo ci;
	struct nlmsghdr *nlh;
	struct ndmsg *ndm;
	u32 ext_flags = 0;

	nlh = nlmsg_put(skb, portid, seq, type, sizeof(*ndm), flags);
	if (nlh == NULL)
		return -EMSGSIZE;

	ndm = nlmsg_data(nlh);
	ndm->ndm_family	 = AF_BRIDGE;
	ndm->ndm_pad1    = 0;
	ndm->ndm_pad2    = 0;
	ndm->ndm_flags	 = 0;
	ndm->ndm_type	 = 0;
	ndm->ndm_ifindex = dst ? dst->dev->ifindex : br->dev->ifindex;
	ndm->ndm_state   = fdb_to_nud(br, fdb);

	if (test_bit(BR_FDB_OFFLOADED, &fdb->flags))
		ndm->ndm_flags |= NTF_OFFLOADED;
	if (test_bit(BR_FDB_ADDED_BY_EXT_LEARN, &fdb->flags))
		ndm->ndm_flags |= NTF_EXT_LEARNED;
	if (test_bit(BR_FDB_STICKY, &fdb->flags))
		ndm->ndm_flags |= NTF_STICKY;
	if (test_bit(BR_FDB_LOCKED, &fdb->flags))
		ext_flags |= NTF_EXT_LOCKED;

	if (nla_put(skb, NDA_LLADDR, ETH_ALEN, &fdb->key.addr))
		goto nla_put_failure;
	if (nla_put_u32(skb, NDA_MASTER, br->dev->ifindex))
		goto nla_put_failure;
	if (nla_put_u32(skb, NDA_FLAGS_EXT, ext_flags))
		goto nla_put_failure;

	ci.ndm_used	 = jiffies_to_clock_t(now - fdb->used);
	ci.ndm_confirmed = 0;
	ci.ndm_updated	 = jiffies_to_clock_t(now - fdb->updated);
	ci.ndm_refcnt	 = 0;
	if (nla_put(skb, NDA_CACHEINFO, sizeof(ci), &ci))
		goto nla_put_failure;

	if (fdb->key.vlan_id && nla_put(skb, NDA_VLAN, sizeof(u16),
					&fdb->key.vlan_id))
		goto nla_put_failure;

	if (test_bit(BR_FDB_NOTIFY, &fdb->flags)) {
		struct nlattr *nest = nla_nest_start(skb, NDA_FDB_EXT_ATTRS);
		u8 notify_bits = FDB_NOTIFY_BIT;

		if (!nest)
			goto nla_put_failure;
		if (test_bit(BR_FDB_NOTIFY_INACTIVE, &fdb->flags))
			notify_bits |= FDB_NOTIFY_INACTIVE_BIT;

		if (nla_put_u8(skb, NFEA_ACTIVITY_NOTIFY, notify_bits)) {
			nla_nest_cancel(skb, nest);
			goto nla_put_failure;
		}

		nla_nest_end(skb, nest);
	}

	nlmsg_end(skb, nlh);
	return 0;

nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
}

static inline size_t fdb_nlmsg_size(void)
{
	return NLMSG_ALIGN(sizeof(struct ndmsg))
		+ nla_total_size(ETH_ALEN) /* NDA_LLADDR */
		+ nla_total_size(sizeof(u32)) /* NDA_MASTER */
		+ nla_total_size(sizeof(u32)) /* NDA_FLAGS_EXT */
		+ nla_total_size(sizeof(u16)) /* NDA_VLAN */
		+ nla_total_size(sizeof(struct nda_cacheinfo))
		+ nla_total_size(0) /* NDA_FDB_EXT_ATTRS */
		+ nla_total_size(sizeof(u8)); /* NFEA_ACTIVITY_NOTIFY */
}

static void fdb_notify(struct net_bridge *br,
		       const struct net_bridge_fdb_entry *fdb, int type,
		       bool swdev_notify)
{
	struct net *net = dev_net(br->dev);
	struct sk_buff *skb;
	int err = -ENOBUFS;

	if (swdev_notify)
		br_switchdev_fdb_notify(br, fdb, type);

	skb = nlmsg_new(fdb_nlmsg_size(), GFP_ATOMIC);
	if (skb == NULL)
		goto errout;

	err = fdb_fill_info(skb, br, fdb, 0, 0, type, 0);
	if (err < 0) {
		/* -EMSGSIZE implies BUG in fdb_nlmsg_size() */
		WARN_ON(err == -EMSGSIZE);
		kfree_skb(skb);
		goto errout;
	}
	rtnl_notify(skb, net, 0, RTNLGRP_NEIGH, NULL, GFP_ATOMIC);
	return;
errout:
	rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
}

static struct net_bridge_fdb_entry *fdb_find_rcu(struct rhashtable *tbl,
						 const unsigned char *addr,
						 __u16 vid)
{
	struct net_bridge_fdb_key key;

	WARN_ON_ONCE(!rcu_read_lock_held());

	key.vlan_id = vid;
	memcpy(key.addr.addr, addr, sizeof(key.addr.addr));

	return rhashtable_lookup(tbl, &key, br_fdb_rht_params);
}

/* requires bridge hash_lock */
static struct net_bridge_fdb_entry *br_fdb_find(struct net_bridge *br,
						const unsigned char *addr,
						__u16 vid)
{
	struct net_bridge_fdb_entry *fdb;

	lockdep_assert_held_once(&br->hash_lock);

	rcu_read_lock();
	fdb = fdb_find_rcu(&br->fdb_hash_tbl, addr, vid);
	rcu_read_unlock();

	return fdb;
}

struct net_device *br_fdb_find_port(const struct net_device *br_dev,
				    const unsigned char *addr,
				    __u16 vid)
{
	struct net_bridge_fdb_entry *f;
	struct net_device *dev = NULL;
	struct net_bridge *br;

	ASSERT_RTNL();

	if (!netif_is_bridge_master(br_dev))
		return NULL;

	br = netdev_priv(br_dev);
	rcu_read_lock();
	f = br_fdb_find_rcu(br, addr, vid);
	if (f && f->dst)
		dev = f->dst->dev;
	rcu_read_unlock();

	return dev;
}
EXPORT_SYMBOL_GPL(br_fdb_find_port);

struct net_bridge_fdb_entry *br_fdb_find_rcu(struct net_bridge *br,
					     const unsigned char *addr,
					     __u16 vid)
{
	return fdb_find_rcu(&br->fdb_hash_tbl, addr, vid);
}

/* When a static FDB entry is added, the mac address from the entry is
 * added to the bridge private HW address list and all required ports
 * are then updated with the new information.
 * Called under RTNL.
 */
static void fdb_add_hw_addr(struct net_bridge *br, const unsigned char *addr)
{
	int err;
	struct net_bridge_port *p;

	ASSERT_RTNL();

	list_for_each_entry(p, &br->port_list, list) {
		if (!br_promisc_port(p)) {
			err = dev_uc_add(p->dev, addr);
			if (err)
				goto undo;
		}
	}

	return;
undo:
	list_for_each_entry_continue_reverse(p, &br->port_list, list) {
		if (!br_promisc_port(p))
			dev_uc_del(p->dev, addr);
	}
}

/* When a static FDB entry is deleted, the HW address from that entry is
 * also removed from the bridge private HW address list and updates all
 * the ports with needed information.
 * Called under RTNL.
 */
static void fdb_del_hw_addr(struct net_bridge *br, const unsigned char *addr)
{
	struct net_bridge_port *p;

	ASSERT_RTNL();

	list_for