/*
 *      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 "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 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)
{
        /* 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 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);
}

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(br, 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_change_mac_address(struct net_bridge *br, const u8 *newaddr)
{
        struct net_bridge_fdb_entry *f;

        /* If old entry was unassociated with any port, then delete it. */
        f = __br_fdb_get(br, br->dev->dev_addr);
        if (f && f->is_local && !f->dst)
                fdb_delete(br, f);

        fdb_insert(br, NULL, newaddr);
}

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->ageing_time;
        int i;

        spin_lock(&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->updated + delay;
                        if (time_before_eq(this_timer, jiffies))
                                fdb_delete(br, f);
                        else if (time_before(this_timer, next_timer))
                                next_timer = this_timer;
                }
        }
        spin_unlock(&br->hash_lock);

        mod_timer(&br->gc_timer, round_jiffies_up(next_timer));
}

/* 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(br, f);
                }
        }
        spin_unlock_bh(&br->hash_lock);
}

/* Flush all entries referring 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(br, f);
                skip_delete: ;
                }
        }
        spin_unlock_bh(&br->hash_lock);
}

/* No locking or refcounting, assumes caller has 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 IS_ENABLED(CONFIG_ATM_LANE)
/* 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;
        struct net_bridge_port *port;
        int ret;

        rcu_read_lock();
        port = br_port_get_rcu(dev);
        if (!port)
                ret = 0;
        else {
                fdb = __br_fdb_get(port->br, addr);
                ret = fdb && fdb->dst && 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;

                        /* ignore pseudo entry for local MAC address */
                        if (!f->dst)
                                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->updated);
                        ++fe;
                        ++num;
                }
        }

 out:
        rcu_read_unlock();

        return num;
}

static 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(fdb, h, head, hlist) {
                if (!compare_ether_addr(fdb->addr.addr, addr))
                        return fdb;
        }
        return NULL;
}

static struct net_bridge_fdb_entry *fdb_find_rcu(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)
{
        struct net_bridge_fdb_entry *fdb;

        fdb = kmem_cache_alloc(br_fdb_cache, GFP_ATOMIC);
        if (fdb) {
                memcpy(fdb->addr.addr, addr, ETH_ALEN);
                fdb->dst = source;
                fdb->is_local = 0;
                fdb->is_static = 0;
                fdb->updated = fdb->used = jiffies;
                hlist_add_head_rcu(&fdb->hlist, head);
        }
        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;
                br_warn(br, "adding interface %s with same address "
                       "as a received packet\n",
                       source->dev->name);
                fdb_delete(br, fdb);
        }

        fdb = fdb_create(head, source, addr);
        if (!fdb)
                return -ENOMEM;

        fdb->is_local = fdb->is_static = 1;
        fdb_notify(br, fdb, RTM_NEWNEIGH);
        return 0;
}

/* Add entry for local address of interface */
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_rcu(head, addr);
        if (likely(fdb)) {
                /* attempt to update an entry for a local interface */
                if (unlikely(fdb->is_local)) {
                        if (net_ratelimit())
                                br_warn(br, "received packet on %s with "
                                        "own address as source address\n",
                                        source->dev->name);
                } else {
                        /* fastpath: update of existing entry */
                        fdb->dst = source;
                        fdb->updated = jiffies;
                }
        } else {
                spin_lock(&br->hash_lock);
                if (likely(!fdb_find(head, addr))) {
                        fdb = fdb_create(head, source, addr);
                        if (fdb)
                                fdb_notify(br, fdb, RTM_NEWNEIGH);
                }
                /* else  we lose race and someone else inserts
                 * it first, don't bother updating
                 */
                spin_unlock(&br->hash_lock);
        }
}

static int fdb_to_nud(const struct net_bridge_fdb_entry *fdb)
{
        if (fdb->is_local)
                return NUD_PERMANENT;
        else if (fdb->is_static)
                return NUD_NOARP;
        else if (has_expired(fdb->dst->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 pid, u32 seq, int type, unsigned int flags)
{
        unsigned long now = jiffies;
        struct nda_cacheinfo ci;
        struct nlmsghdr *nlh;
        struct ndmsg *ndm;

        nlh = nlmsg_put(skb, pid, 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 = fdb->dst ? fdb->dst->dev->ifindex : br->dev->ifindex;
        ndm->ndm_state   = fdb_to_nud(fdb);

        NLA_PUT(skb, NDA_LLADDR, ETH_ALEN, &fdb->addr);

        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;
        NLA_PUT(skb, NDA_CACHEINFO, sizeof(ci), &ci);

        return nlmsg_end(skb, nlh);

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(struct nda_cacheinfo));
}

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

        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:
        if (err < 0)
                rtnl_set_sk_err(net, RTNLGRP_NEIGH, err);
}

/* Dump information about entries, in response to GETNEIGH */
int br_fdb_dump(struct sk_buff *skb, struct netlink_callback *cb)
{
        struct net *net = sock_net(skb->sk);
        struct net_device *dev;
        int idx = 0;

        rcu_read_lock();
        for_each_netdev_rcu(net, dev) {
                struct net_bridge *br = netdev_priv(dev);
                int i;

                if (!(dev->priv_flags & IFF_EBRIDGE))
                        continue;

                for (i = 0; i < BR_HASH_SIZE; i++) {
                        struct hlist_node *h;
                        struct net_bridge_fdb_entry *f;

                        hlist_for_each_entry_rcu(f, h, &br->hash[i], hlist) {
                                if (idx < cb->args[0])
                                        goto skip;

                                if (fdb_fill_info(skb, br, f,
                                                  NETLINK_CB(cb->skb).pid,
                                                  cb->nlh->nlmsg_seq,
                                                  RTM_NEWNEIGH,
                                                  NLM_F_MULTI) < 0)
                                        break;
skip:
                                ++idx;
                        }
                }
        }
        rcu_read_unlock();

        cb->args[0] = idx;

        return skb->len;
}

/* Update (create or replace) forwarding database entry */
static int fdb_add_entry(struct net_bridge_port *source, const __u8 *addr,
                         __u16 state, __u16 flags)
{
        struct net_bridge *br = source->br;
        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
        struct net_bridge_fdb_entry *fdb;

        fdb = fdb_find(head, addr);
        if (fdb == NULL) {
                if (!(flags & NLM_F_CREATE))
                        return -ENOENT;

                fdb = fdb_create(head, source, addr);
                if (!fdb)
                        return -ENOMEM;
                fdb_notify(br, fdb, RTM_NEWNEIGH);
        } else {
                if (flags & NLM_F_EXCL)
                        return -EEXIST;
        }

        if (fdb_to_nud(fdb) != state) {
                if (state & NUD_PERMANENT)
                        fdb->is_local = fdb->is_static = 1;
                else if (state & NUD_NOARP) {
                        fdb->is_local = 0;
                        fdb->is_static = 1;
                } else
                        fdb->is_local = fdb->is_static = 0;

                fdb->updated = fdb->used = jiffies;
                fdb_notify(br, fdb, RTM_NEWNEIGH);
        }

        return 0;
}

/* Add new permanent fdb entry with RTM_NEWNEIGH */
int br_fdb_add(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct ndmsg *ndm;
        struct nlattr *tb[NDA_MAX+1];
        struct net_device *dev;
        struct net_bridge_port *p;
        const __u8 *addr;
        int err;

        ASSERT_RTNL();
        err = nlmsg_parse(nlh, sizeof(*ndm), tb, NDA_MAX, NULL);
        if (err < 0)
                return err;

        ndm = nlmsg_data(nlh);
        if (ndm->ndm_ifindex == 0) {
                pr_info("bridge: RTM_NEWNEIGH with invalid ifindex\n");
                return -EINVAL;
        }

        dev = __dev_get_by_index(net, ndm->ndm_ifindex);
        if (dev == NULL) {
                pr_info("bridge: RTM_NEWNEIGH with unknown ifindex\n");
                return -ENODEV;
        }

        if (!tb[NDA_LLADDR] || nla_len(tb[NDA_LLADDR]) != ETH_ALEN) {
                pr_info("bridge: RTM_NEWNEIGH with invalid address\n");
                return -EINVAL;
        }

        addr = nla_data(tb[NDA_LLADDR]);
        if (!is_valid_ether_addr(addr)) {
                pr_info("bridge: RTM_NEWNEIGH with invalid ether address\n");
                return -EINVAL;
        }

        if (!(ndm->ndm_state & (NUD_PERMANENT|NUD_NOARP|NUD_REACHABLE))) {
                pr_info("bridge: RTM_NEWNEIGH with invalid state %#x\n", ndm->ndm_state);
                return -EINVAL;
        }

        p = br_port_get_rtnl(dev);
        if (p == NULL) {
                pr_info("bridge: RTM_NEWNEIGH %s not a bridge port\n",
                        dev->name);
                return -EINVAL;
        }

        if (ndm->ndm_flags & NTF_USE) {
                rcu_read_lock();
                br_fdb_update(p->br, p, addr);
                rcu_read_unlock();
        } else {
                spin_lock_bh(&p->br->hash_lock);
                err = fdb_add_entry(p, addr, ndm->ndm_state, nlh->nlmsg_flags);
                spin_unlock_bh(&p->br->hash_lock);
        }

        return err;
}

static int fdb_delete_by_addr(struct net_bridge_port *p, const u8 *addr)
{
        struct net_bridge *br = p->br;
        struct hlist_head *head = &br->hash[br_mac_hash(addr)];
        struct net_bridge_fdb_entry *fdb;

        fdb = fdb_find(head, addr);
        if (!fdb)
                return -ENOENT;

        fdb_delete(p->br, fdb);
        return 0;
}

/* Remove neighbor entry with RTM_DELNEIGH */
int br_fdb_delete(struct sk_buff *skb, struct nlmsghdr *nlh, void *arg)
{
        struct net *net = sock_net(skb->sk);
        struct ndmsg *ndm;
        struct net_bridge_port *p;
        struct nlattr *llattr;
        const __u8 *addr;
        struct net_device *dev;
        int err;

        ASSERT_RTNL();
        if (nlmsg_len(nlh) < sizeof(*ndm))
                return -EINVAL;

        ndm = nlmsg_data(nlh);
        if (ndm->ndm_ifindex == 0) {
                pr_info("bridge: RTM_DELNEIGH with invalid ifindex\n");
                return -EINVAL;
        }

        dev = __dev_get_by_index(net, ndm->ndm_ifindex);
        if (dev == NULL) {
                pr_info("bridge: RTM_DELNEIGH with unknown ifindex\n");
                return -ENODEV;
        }

        llattr = nlmsg_find_attr(nlh, sizeof(*ndm), NDA_LLADDR);
        if (llattr == NULL || nla_len(llattr) != ETH_ALEN) {
                pr_info("bridge: RTM_DELNEIGH with invalid address\n");
                return -EINVAL;
        }

        addr = nla_data(llattr);

        p = br_port_get_rtnl(dev);
        if (p == NULL) {
                pr_info("bridge: RTM_DELNEIGH %s not a bridge port\n",
                        dev->name);
                return -EINVAL;
        }

        spin_lock_bh(&p->br->hash_lock);
        err = fdb_delete_by_addr(p, addr);
        spin_unlock_bh(&p->br->hash_lock);

        return err;
}