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

#include <linux/err.h>
#include <linux/slab.h>
#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/netpoll.h>
#include <linux/skbuff.h>
#include <linux/if_vlan.h>
#include <linux/netfilter_bridge.h>
#include "br_private.h"

/* Don't forward packets to originating port or forwarding disabled */
static inline int should_deliver(const struct net_bridge_port *p,
                                 const struct sk_buff *skb)
{
        struct net_bridge_vlan_group *vg;

        vg = nbp_vlan_group_rcu(p);
        return ((p->flags & BR_HAIRPIN_MODE) || skb->dev != p->dev) &&
                (br_mst_is_enabled(p) || p->state == BR_STATE_FORWARDING) &&
                br_allowed_egress(vg, skb) && nbp_switchdev_allowed_egress(p, skb) &&
                !br_skb_isolated(p, skb);
}

int br_dev_queue_push_xmit(struct net *net, struct sock *sk, struct sk_buff *skb)
{
        skb_push(skb, ETH_HLEN);
        if (!is_skb_forwardable(skb->dev, skb))
                goto drop;

        br_drop_fake_rtable(skb);

        if (skb->ip_summed == CHECKSUM_PARTIAL &&
            eth_type_vlan(skb->protocol)) {
                int depth;

                if (!vlan_get_protocol_and_depth(skb, skb->protocol, &depth))
                        goto drop;

                skb_set_network_header(skb, depth);
        }

        br_switchdev_frame_set_offload_fwd_mark(skb);

        dev_queue_xmit(skb);

        return 0;

drop:
        kfree_skb(skb);
        return 0;
}
EXPORT_SYMBOL_GPL(br_dev_queue_push_xmit);

int br_forward_finish(struct net *net, struct sock *sk, struct sk_buff *skb)
{
        skb_clear_tstamp(skb);
        return NF_HOOK(NFPROTO_BRIDGE, NF_BR_POST_ROUTING,
                       net, sk, skb, NULL, skb->dev,
                       br_dev_queue_push_xmit);

}
EXPORT_SYMBOL_GPL(br_forward_finish);

static void __br_forward(const struct net_bridge_port *to,
                         struct sk_buff *skb, bool local_orig)
{
        struct net_bridge_vlan_group *vg;
        struct net_device *indev;
        struct net *net;
        int br_hook;

        /* Mark the skb for forwarding offload early so that br_handle_vlan()
         * can know whether to pop the VLAN header on egress or keep it.
         */
        nbp_switchdev_frame_mark_tx_fwd_offload(to, skb);

        vg = nbp_vlan_group_rcu(to);
        skb = br_handle_vlan(to->br, to, vg, skb);
        if (!skb)
                return;

        indev = skb->dev;
        skb->dev = to->dev;
        if (!local_orig) {
                if (skb_warn_if_lro(skb)) {
                        kfree_skb(skb);
                        return;
                }
                br_hook = NF_BR_FORWARD;
                skb_forward_csum(skb);
                net = dev_net(indev);
        } else {
                if (unlikely(netpoll_tx_running(to->br->dev))) {
                        skb_push(skb, ETH_HLEN);
                        if (!is_skb_forwardable(skb->dev, skb))
                                kfree_skb(skb);
                        else
                                br_netpoll_send_skb(to, skb);
                        return;
                }
                br_hook = NF_BR_LOCAL_OUT;
                net = dev_net(skb->dev);
                indev = NULL;
        }

        NF_HOOK(NFPROTO_BRIDGE, br_hook,
                net, NULL, skb, indev, skb->dev,
                br_forward_finish);
}

static int deliver_clone(const struct net_bridge_port *prev,
                         struct sk_buff *skb, bool local_orig)
{
        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;

        skb = skb_clone(skb, GFP_ATOMIC);
        if (!skb) {
                DEV_STATS_INC(dev, tx_dropped);
                return -ENOMEM;
        }

        __br_forward(prev, skb, local_orig);
        return 0;
}

/**
 * br_forward - forward a packet to a specific port
 * @to: destination port
 * @skb: packet being forwarded
 * @local_rcv: packet will be received locally after forwarding
 * @local_orig: packet is locally originated
 *
 * Should be called with rcu_read_lock.
 */
void br_forward(const struct net_bridge_port *to,
                struct sk_buff *skb, bool local_rcv, bool local_orig)
{
        if (unlikely(!to))
                goto out;

        /* redirect to backup link if the destination port is down */
        if (rcu_access_pointer(to->backup_port) &&
            (!netif_carrier_ok(to->dev) || !netif_running(to->dev))) {
                struct net_bridge_port *backup_port;

                backup_port = rcu_dereference(to->backup_port);
                if (unlikely(!backup_port))
                        goto out;
                BR_INPUT_SKB_CB(skb)->backup_nhid = READ_ONCE(to->backup_nhid);
                to = backup_port;
        }

        if (should_deliver(to, skb)) {
                if (local_rcv)
                        deliver_clone(to, skb, local_orig);
                else
                        __br_forward(to, skb, local_orig);
                return;
        }

out:
        if (!local_rcv)
                kfree_skb(skb);
}
EXPORT_SYMBOL_GPL(br_forward);

static struct net_bridge_port *maybe_deliver(
        struct net_bridge_port *prev, struct net_bridge_port *p,
        struct sk_buff *skb, bool local_orig)
{
        u8 igmp_type = br_multicast_igmp_type(skb);
        int err;

        if (!should_deliver(p, skb))
                return prev;

        nbp_switchdev_frame_mark_tx_fwd_to_hwdom(p, skb);

        if (!prev)
                goto out;

        err = deliver_clone(prev, skb, local_orig);
        if (err)
                return ERR_PTR(err);
out:
        br_multicast_count(p->br, p, skb, igmp_type, BR_MCAST_DIR_TX);

        return p;
}

/* called under rcu_read_lock */
void br_flood(struct net_bridge *br, struct sk_buff *skb,
              enum br_pkt_type pkt_type, bool local_rcv, bool local_orig,
              u16 vid)
{
        enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
        struct net_bridge_port *prev = NULL;
        struct net_bridge_port *p;

        br_tc_skb_miss_set(skb, pkt_type != BR_PKT_BROADCAST);

        list_for_each_entry_rcu(p, &br->port_list, list) {
                /* Do not flood unicast traffic to ports that turn it off, nor
                 * other traffic if flood off, except for traffic we originate
                 */
                switch (pkt_type) {
                case BR_PKT_UNICAST:
                        if (!(p->flags & BR_FLOOD))
                                continue;
                        break;
                case BR_PKT_MULTICAST:
                        if (!(p->flags & BR_MCAST_FLOOD) && skb->dev != br->dev)
                                continue;
                        break;
                case BR_PKT_BROADCAST:
                        if (!(p->flags & BR_BCAST_FLOOD) && skb->dev != br->dev)
                                continue;
                        break;
                }

                /* Do not flood to ports that enable proxy ARP */
                if (p->flags & BR_PROXYARP)
                        continue;
                if (BR_INPUT_SKB_CB(skb)->proxyarp_replied &&
                    ((p->flags & BR_PROXYARP_WIFI) ||
                     br_is_neigh_suppress_enabled(p, vid)))
                        continue;

                prev = maybe_deliver(prev, p, skb, local_orig);
                if (IS_ERR(prev)) {
                        reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
                                 SKB_DROP_REASON_NOT_SPECIFIED;
                        goto out;
                }
        }

        if (!prev)
                goto out;

        if (local_rcv)
                deliver_clone(prev, skb, local_orig);
        else
                __br_forward(prev, skb, local_orig);
        return;

out:
        if (!local_rcv)
                kfree_skb_reason(skb, reason);
}

#ifdef CONFIG_BRIDGE_IGMP_SNOOPING
static void maybe_deliver_addr(struct net_bridge_port *p, struct sk_buff *skb,
                               const unsigned char *addr, bool local_orig)
{
        struct net_device *dev = BR_INPUT_SKB_CB(skb)->brdev;
        const unsigned char *src = eth_hdr(skb)->h_source;
        struct sk_buff *nskb;

        if (!should_deliver(p, skb))
                return;

        /* Even with hairpin, no soliloquies - prevent breaking IPv6 DAD */
        if (skb->dev == p->dev && ether_addr_equal(src, addr))
                return;

        __skb_push(skb, ETH_HLEN);
        nskb = pskb_copy(skb, GFP_ATOMIC);
        __skb_pull(skb, ETH_HLEN);
        if (!nskb) {
                DEV_STATS_INC(dev, tx_dropped);
                return;
        }

        skb = nskb;
        __skb_pull(skb, ETH_HLEN);
        if (!is_broadcast_ether_addr(addr))
                memcpy(eth_hdr(skb)->h_dest, addr, ETH_ALEN);

        __br_forward(p, skb, local_orig);
}

/* called with rcu_read_lock */
void br_multicast_flood(struct net_bridge_mdb_entry *mdst,
                        struct sk_buff *skb,
                        struct net_bridge_mcast *brmctx,
                        bool local_rcv, bool local_orig)
{
        enum skb_drop_reason reason = SKB_DROP_REASON_NO_TX_TARGET;
        struct net_bridge_port *prev = NULL;
        struct net_bridge_port_group *p;
        bool allow_mode_include = true;
        struct hlist_node *rp;

        rp = br_multicast_get_first_rport_node(brmctx, skb);

        if (mdst) {
                p = rcu_dereference(mdst->ports);
                if (br_multicast_should_handle_mode(brmctx, mdst->addr.proto) &&
                    br_multicast_is_star_g(&mdst->addr))
                        allow_mode_include = false;
        } else {
                p = NULL;
                br_tc_skb_miss_set(skb, true);
        }

        while (p || rp) {
                struct net_bridge_port *port, *lport, *rport;

                lport = p ? p->key.port : NULL;
                rport = br_multicast_rport_from_node_skb(rp, skb);

                if ((unsigned long)lport > (unsigned long)rport) {
                        port = lport;

                        if (port->flags & BR_MULTICAST_TO_UNICAST) {
                                maybe_deliver_addr(lport, skb, p->eth_addr,
                                                   local_orig);
                                goto delivered;
                        }
                        if ((!allow_mode_include &&
                             p->filter_mode == MCAST_INCLUDE) ||
                            (p->flags & MDB_PG_FLAGS_BLOCKED))
                                goto delivered;
                } else {
                        port = rport;
                }

                prev = maybe_deliver(prev, port, skb, local_orig);
                if (IS_ERR(prev)) {
                        reason = PTR_ERR(prev) == -ENOMEM ? SKB_DROP_REASON_NOMEM :
                                 SKB_DROP_REASON_NOT_SPECIFIED;
                        goto out;
                }
delivered:
                if ((unsigned long)lport >= (unsigned long)port)
                        p = rcu_dereference(p->next);
                if ((unsigned long)rport >= (unsigned long)port)
                        rp = rcu_dereference(hlist_next_rcu(rp));
        }

        if (!prev)
                goto out;

        if (local_rcv)
                deliver_clone(prev, skb, local_orig);
        else
                __br_forward(prev, skb, local_orig);
        return;

out:
        if (!local_rcv)
                kfree_skb_reason(skb, reason);
}
#endif