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

#include <linux/kernel.h>
#include <linux/netdevice.h>
#include <linux/etherdevice.h>
#include <linux/netpoll.h>
#include <linux/ethtool.h>
#include <linux/if_arp.h>
#include <linux/module.h>
#include <linux/init.h>
#include <linux/rtnetlink.h>
#include <linux/if_ether.h>
#include <linux/slab.h>
#include <net/dsa.h>
#include <net/sock.h>
#include <linux/if_vlan.h>
#include <net/switchdev.h>
#include <net/net_namespace.h>

#include "br_private.h"

/*
 * Determine initial path cost based on speed.
 * using recommendations from 802.1d standard
 *
 * Since driver might sleep need to not be holding any locks.
 */
static int port_cost(struct net_device *dev)
{
        struct ethtool_link_ksettings ecmd;

        if (!__ethtool_get_link_ksettings(dev, &ecmd)) {
                switch (ecmd.base.speed) {
                case SPEED_10000:
                        return 2;
                case SPEED_1000:
                        return 4;
                case SPEED_100:
                        return 19;
                case SPEED_10:
                        return 100;
                }
        }

        /* Old silly heuristics based on name */
        if (!strncmp(dev->name, "lec", 3))
                return 7;

        if (!strncmp(dev->name, "plip", 4))
                return 2500;

        return 100;     /* assume old 10Mbps */
}


/* Check for port carrier transitions. */
void br_port_carrier_check(struct net_bridge_port *p, bool *notified)
{
        struct net_device *dev = p->dev;
        struct net_bridge *br = p->br;

        if (!(p->flags & BR_ADMIN_COST) &&
            netif_running(dev) && netif_oper_up(dev))
                p->path_cost = port_cost(dev);

        *notified = false;
        if (!netif_running(br->dev))
                return;

        spin_lock_bh(&br->lock);
        if (netif_running(dev) && netif_oper_up(dev)) {
                if (p->state == BR_STATE_DISABLED) {
                        br_stp_enable_port(p);
                        *notified = true;
                }
        } else {
                if (p->state != BR_STATE_DISABLED) {
                        br_stp_disable_port(p);
                        *notified = true;
                }
        }
        spin_unlock_bh(&br->lock);
}

static void br_port_set_promisc(struct net_bridge_port *p)
{
        int err = 0;

        if (br_promisc_port(p))
                return;

        err = dev_set_promiscuity(p->dev, 1);
        if (err)
                return;

        br_fdb_unsync_static(p->br, p);
        p->flags |= BR_PROMISC;
}

static void br_port_clear_promisc(struct net_bridge_port *p)
{
        int err;

        /* Check if the port is already non-promisc or if it doesn't
         * support UNICAST filtering.  Without unicast filtering support
         * we'll end up re-enabling promisc mode anyway, so just check for
         * it here.
         */
        if (!br_promisc_port(p) || !(p->dev->priv_flags & IFF_UNICAST_FLT))
                return;

        /* Since we'll be clearing the promisc mode, program the port
         * first so that we don't have interruption in traffic.
         */
        err = br_fdb_sync_static(p->br, p);
        if (err)
                return;

        dev_set_promiscuity(p->dev, -1);
        p->flags &= ~BR_PROMISC;
}

/* When a port is added or removed or when certain port flags
 * change, this function is called to automatically manage
 * promiscuity setting of all the bridge ports.  We are always called
 * under RTNL so can skip using rcu primitives.
 */
void br_manage_promisc(struct net_bridge *br)
{
        struct net_bridge_port *p;
        bool set_all = false;

        /* If vlan filtering is disabled or bridge interface is placed
         * into promiscuous mode, place all ports in promiscuous mode.
         */
        if ((br->dev->flags & IFF_PROMISC) || !br_vlan_enabled(br->dev))
                set_all = true;

        list_for_each_entry(p, &br->port_list, list) {
                if (set_all) {
                        br_port_set_promisc(p);
                } else {
                        /* If the number of auto-ports is <= 1, then all other
                         * ports will have their output configuration
                         * statically specified through fdbs.  Since ingress
                         * on the auto-port becomes forwarding/egress to other
                         * ports and egress configuration is statically known,
                         * we can say that ingress configuration of the
                         * auto-port is also statically known.
                         * This lets us disable promiscuous mode and write
                         * this config to hw.
                         */
                        if (br->auto_cnt == 0 ||
                            (br->auto_cnt == 1 && br_auto_port(p)))
                                br_port_clear_promisc(p);
                        else
                                br_port_set_promisc(p);
                }
        }
}

int nbp_backup_change(struct net_bridge_port *p,
                      struct net_device *backup_dev)
{
        struct net_bridge_port *old_backup = rtnl_dereference(p->backup_port);
        struct net_bridge_port *backup_p = NULL;

        ASSERT_RTNL();

        if (backup_dev) {
                if (!netif_is_bridge_port(backup_dev))
                        return -ENOENT;

                backup_p = br_port_get_rtnl(backup_dev);
                if (backup_p->br != p->br)
                        return -EINVAL;
        }

        if (p == backup_p)
                return -EINVAL;

        if (old_backup == backup_p)
                return 0;

        /* if the backup link is already set, clear it */
        if (old_backup)
                old_backup->backup_redirected_cnt--;

        if (backup_p)
                backup_p->backup_redirected_cnt++;
        rcu_assign_pointer(p->backup_port, backup_p);

        return 0;
}

static void nbp_backup_clear(struct net_bridge_port *p)
{
        nbp_backup_change(p, NULL);
        if (p->backup_redirected_cnt) {
                struct net_bridge_port *cur_p;

                list_for_each_entry(cur_p, &p->br->port_list, list) {
                        struct net_bridge_port *backup_p;

                        backup_p = rtnl_dereference(cur_p->backup_port);
                        if (backup_p == p)
                                nbp_backup_change(cur_p, NULL);
                }
        }

        WARN_ON(rcu_access_pointer(p->backup_port) || p->backup_redirected_cnt);
}

static void nbp_update_port_count(struct net_bridge *br)
{
        struct net_bridge_port *p;
        u32 cnt = 0;

        list_for_each_entry(p, &br->port_list, list) {
                if (br_auto_port(p))
                        cnt++;
        }
        if (br->auto_cnt != cnt) {
                br->auto_cnt = cnt;
                br_manage_promisc(br);
        }
}

static void nbp_delete_promisc(struct net_bridge_port *p)
{
        /* If port is currently promiscuous, unset promiscuity.
         * Otherwise, it is a static port so remove all addresses
         * from it.
         */
        dev_set_allmulti(p->dev, -1);
        if (br_promisc_port(p))
                dev_set_promiscuity(p->dev, -1);
        else
                br_fdb_unsync_static(p->br, p);
}

static void release_nbp(struct kobject *kobj)
{
        struct net_bridge_port *p
                = container_of(kobj, struct net_bridge_port, kobj);
        kfree(p);
}

static void brport_get_ownership(struct kobject *kobj, kuid_t *uid, kgid_t *gid)
{
        struct net_bridge_port *p = kobj_to_brport(kobj);

        net_ns_get_ownership(dev_net(p->dev), uid, gid);
}

static struct kobj_type brport_ktype = {
#ifdef CONFIG_SYSFS
        .sysfs_ops = &brport_sysfs_ops,
#endif
        .release = release_nbp,
        .get_ownership = brport_get_ownership,
};

static void destroy_nbp(struct net_bridge_port *p)
{
        struct net_device *dev = p->dev;

        p->br = NULL;
        p->dev = NULL;
        dev_put(dev);

        kobject_put(&p->kobj);
}

static void destroy_nbp_rcu(struct rcu_head *head)
{
        struct net_bridge_port *p =
                        container_of(head, struct net_bridge_port, rcu);
        destroy_nbp(p);
}

static unsigned get_max_headroom(struct net_bridge *br)
{
        unsigned max_headroom = 0;
        struct net_bridge_port *p;

        list_for_each_entry(p, &br->port_list, list) {
                unsigned dev_headroom = netdev_get_fwd_headroom(p->dev);

                if (dev_headroom > max_headroom)
                        max_headroom = dev_headroom;
        }

        return max_headroom;
}

static void update_headroom(struct net_bridge *br, int new_hr)
{
        struct net_bridge_port *p;

        list_for_each_entry(p, &br->port_list, list)
                netdev_set_rx_headroom(p->dev, new_hr);

        br->dev->needed_headroom = new_hr;
}

/* Delete port(interface) from bridge is done in two steps.
 * via RCU. First step, marks device as down. That deletes
 * all the timers and stops new packets from flowing through.
 *
 * Final cleanup doesn't occur until after all CPU's finished
 * processing packets.
 *
 * Protected from multiple admin operations by RTNL mutex
 */
static void del_nbp(struct net_bridge_port *p)
{
        struct net_bridge *br = p->br;
        struct net_device *dev = p->dev;

        sysfs_remove_link(br->ifobj, p->dev->name);

        nbp_delete_promisc(p);

        spin_lock_bh(&br->lock);
        br_stp_disable_port(p);
        spin_unlock_bh(&br->lock);

        br_mrp_port_del(br, p);
        br_cfm_port_del(br, p);

        br_ifinfo_notify(RTM_DELLINK, NULL, p);

        list_del_rcu(&p->list);
        if (netdev_get_fwd_headroom(dev) == br->dev->needed_headroom)
                update_headroom(br, get_max_headroom(br));
        netdev_reset_rx_headroom(dev);

        nbp_vlan_flush(p);
        br_fdb_delete_by_port(br, p, 0, 1);
        switchdev_deferred_process();
        nbp_backup_clear(p);

        nbp_update_port_count(br);

        netdev_upper_dev_unlink(dev, br->dev);

        dev->priv_flags &= ~IFF_BRIDGE_PORT;

        netdev_rx_handler_unregister(dev);

        br_multicast_del_port(p);

        kobject_uevent(&p->kobj, KOBJ_REMOVE);
        kobject_del(&p->kobj);

        br_netpoll_disable(p);

        call_rcu(&p->rcu, destroy_nbp_rcu);
}

/* Delete bridge device */
void br_dev_delete(struct net_device *dev, struct list_head *head)
{
        struct net_bridge *br = netdev_priv(dev);
        struct net_bridge_port *p, *n;

        list_for_each_entry_safe(p, n, &br->port_list, list) {
                del_nbp(p);
        }

        br_recalculate_neigh_suppress_enabled(br);

        br_fdb_delete_by_port(br, NULL, 0, 1);

        cancel_delayed_work_sync(&br->gc_work);

        br_sysfs_delbr(br->dev);
        unregister_netdevice_queue(br->dev, head);
}

/* find an available port number */
static int find_portno(struct net_bridge *br)
{
        int index;
        struct net_bridge_port *p;
        unsigned long *inuse;

        inuse = bitmap_zalloc(BR_MAX_PORTS, GFP_KERNEL);
        if (!inuse)
                return -ENOMEM;

        set_bit(0, inuse);      /* zero is reserved */
        list_for_each_entry(p, &br->port_list, list) {
                set_bit(p->port_no, inuse);
        }
        index = find_first_zero_bit(inuse, BR_MAX_PORTS);
        bitmap_free(inuse);

        return (index >= BR_MAX_PORTS) ? -EXFULL : index;
}

/* called with RTNL but without bridge lock */
static struct net_bridge_port *new_nbp(struct net_bridge *br,
                                       struct net_device *dev)
{
        struct net_bridge_port *p;
        int index, err;

        index = find_portno(br);
        if (index < 0)
                return ERR_PTR(index);

        p = kzalloc(sizeof(*p), GFP_KERNEL);
        if (p == NULL)
                return ERR_PTR(-ENOMEM);

        p->br = br;
        dev_hold(dev);
        p->dev = dev;
        p->path_cost = port_cost(dev);
        p->priority = 0x8000 >> BR_PORT_BITS;
        p->port_no = index;
        p->flags = BR_LEARNING | BR_FLOOD | BR_MCAST_FLOOD | BR_BCAST_FLOOD;
        br_init_port(p);
        br_set_state(p, BR_STATE_DISABLED);
        br_stp_port_timer_init(p);
        err = br_multicast_add_port(p);
        if (err) {
                dev_put(dev);
                kfree(p);
                p = ERR_PTR(err);
        }

        return p;
}

int br_add_bridge(struct net *net, const char *name)
{
        struct net_device *dev;
        int res;

        dev = alloc_netdev(sizeof(struct net_bridge), name, NET_NAME_UNKNOWN,
                           br_dev_setup);

        if (!dev)
                return -ENOMEM;

        dev_net_set(dev, net);
        dev->rtnl_link_ops = &br_link_ops;

        res = register_netdevice(dev);
        if (res)
                free_netdev(dev);
        return res;
}

int br_del_bridge(struct net *net, const char *name)
{
        struct net_device *dev;
        int ret = 0;

        dev = __dev_get_by_name(net, name);
        if (dev == NULL)
                ret =  -ENXIO;  /* Could not find device */

        else if (!netif_is_bridge_master(dev)) {
                /* Attempt to delete non bridge device! */
                ret = -EPERM;
        }

        else if (dev->flags & IFF_UP) {
                /* Not shutdown yet. */
                ret = -EBUSY;
        }

        else
                br_dev_delete(dev, NULL);

        return ret;
}

/* MTU of the bridge pseudo-device: ETH_DATA_LEN or the minimum of the ports */
static int br_mtu_min(const struct net_bridge *br)
{
        const struct net_bridge_port *p;
        int ret_mtu = 0;

        list_for_each_entry(p, &br->port_list, list)
                if (!ret_mtu || ret_mtu > p->dev->mtu)
                        ret_mtu = p->dev->mtu;

        return ret_mtu ? ret_mtu : ETH_DATA_LEN;
}

void br_mtu_auto_adjust(struct net_bridge *br)
{
        ASSERT_RTNL();

        /* if the bridge MTU was manually configured don't mess with it */
        if (br_opt_get(br, BROPT_MTU_SET_BY_USER))
                return;

        /* change to the minimum MTU and clear the flag which was set by
         * the bridge ndo_change_mtu callback
         */
        dev_set_mtu(br->dev, br_mtu_min(br));
        br_opt_toggle(br, BROPT_MTU_SET_BY_USER, false);
}

static void br_set_gso_limits(struct net_bridge *br)
{
        unsigned int gso_max_size = GSO_MAX_SIZE;
        u16 gso_max_segs = GSO_MAX_SEGS;
        const struct net_bridge_port *p;

        list_for_each_entry(p, &br->port_list, list) {
                gso_max_size = min(gso_max_size, p->dev->gso_max_size);
                gso_max_segs = min(gso_max_segs, p->dev->gso_max_segs);
        }
        br->dev->gso_max_size = gso_max_size;
        br->dev->gso_max_segs = gso_max_segs;
}

/*
 * Recomputes features using slave's features
 */
netdev_features_t br_features_recompute(struct net_bridge *br,
        netdev_features_t features)
{
        struct net_bridge_port *p;
        netdev_features_t mask;

        if (list_empty(&br->port_list))
                return features;

        mask = features;
        features &= ~NETIF_F_ONE_FOR_ALL;

        list_for_each_entry(p, &br->port_list, list) {
                features = netdev_increment_features(features,
                                                     p->dev->features, mask);
        }
        features = netdev_add_tso_features(features, mask);

        return features;
}

/* called with RTNL */
int br_add_if(struct net_bridge *br, struct net_device *dev,
              struct netlink_ext_ack *extack)
{
        struct net_bridge_port *p;
        int err = 0;
        unsigned br_hr, dev_hr;
        bool changed_addr, fdb_synced = false;

        /* Don't allow bridging non-ethernet like devices. */
        if ((dev->flags & IFF_LOOPBACK) ||
            dev->type != ARPHRD_ETHER || dev->addr_len != ETH_ALEN ||
            !is_valid_ether_addr(dev->dev_addr))
                return -EINVAL;

        /* Also don't allow bridging of net devices that are DSA masters, since
         * the bridge layer rx_handler prevents the DSA fake ethertype handler
         * to be invoked, so we don't get the chance to strip off and parse the
         * DSA switch tag protocol header (the bridge layer just returns
         * RX_HANDLER_CONSUMED, stopping RX processing for these frames).
         * The only case where that would not be an issue is when bridging can
         * already be offloaded, such as when the DSA master is itself a DSA
         * or plain switchdev port, and is bridged only with other ports from
         * the same hardware device.
         */
        if (netdev_uses_dsa(dev)) {
                list_for_each_entry(p, &br->port_list, list) {
                        if (!netdev_port_same_parent_id(dev, p->dev)) {
                                NL_SET_ERR_MSG(extack,
                                               "Cannot do software bridging with a DSA master");
                                return -EINVAL;
                        }
                }
        }

        /* No bridging of bridges */
        if (dev->netdev_ops->ndo_start_xmit == br_dev_xmit) {
                NL_SET_ERR_MSG(extack,
                               "Can not enslave a bridge to a bridge");
                return -ELOOP;
        }

        /* Device has master upper dev */
        if (netdev_master_upper_dev_get(dev))
                return -EBUSY;

        /* No bridging devices that dislike that (e.g. wireless) */
        if (dev->priv_flags & IFF_DONT_BRIDGE) {
                NL_SET_ERR_MSG(extack,
                               "Device does not allow enslaving to a bridge");
                return -EOPNOTSUPP;
        }

        p = new_nbp(br, dev);
        if (IS_ERR(p))
                return PTR_ERR(p);

        call_netdevice_notifiers(NETDEV_JOIN, dev);

        err = dev_set_allmulti(dev, 1);
        if (err) {
                br_multicast_del_port(p);
                kfree(p);       /* kobject not yet init'd, manually free */
                goto err1;
        }

        err = kobject_init_and_add(&p->kobj, &brport_ktype, &(dev->dev.kobj),
                                   SYSFS_BRIDGE_PORT_ATTR);
        if (err)
                goto err2;

        err = br_sysfs_addif(p);
        if (err)
                goto err2;

        err = br_netpoll_enable(p);
        if (err)
                goto err3;

        err = netdev_rx_handler_register(dev, br_get_rx_handler(dev), p);
        if (err)
                goto err4;

        dev->priv_flags |= IFF_BRIDGE_PORT;

        err = netdev_master_upper_dev_link(dev, br->dev, NULL, NULL, extack);
        if (err)
                goto err5;

        dev_disable_lro(dev);

        list_add_rcu(&p->list, &br->port_list);

        nbp_update_port_count(br);
        if (!br_promisc_port(p) && (p->dev->priv_flags & IFF_UNICAST_FLT)) {
                /* When updating the port count we also update all ports'
                 * promiscuous mode.
                 * A port leaving promiscuous mode normally gets the bridge's
                 * fdb synced to the unicast filter (if supported), however,
                 * `br_port_clear_promisc` does not distinguish between
                 * non-promiscuous ports and *new* ports, so we need to
                 * sync explicitly here.
                 */
                fdb_synced = br_fdb_sync_static(br, p) == 0;
                if (!fdb_synced)
                        netdev_err(dev, "failed to sync bridge static fdb addresses to this port\n");
        }

        netdev_update_features(br->dev);

        br_hr = br->dev->needed_headroom;
        dev_hr = netdev_get_fwd_headroom(dev);
        if (br_hr < dev_hr)
                update_headroom(br, dev_hr);
        else
                netdev_set_rx_headroom(dev, br_hr);

        if (br_fdb_add_local(br, p, dev->dev_addr, 0))
                netdev_err(dev, "failed insert local address bridge forwarding table\n");

        if (br->dev->addr_assign_type != NET_ADDR_SET) {
                /* Ask for permission to use this MAC address now, even if we
                 * don't end up choosing it below.
                 */
                err = dev_pre_changeaddr_notify(br->dev, dev->dev_addr, extack);
                if (err)
                        goto err6;
        }

        err = nbp_vlan_init(p, extack);
        if (err) {
                netdev_err(dev, "failed to initialize vlan filtering on this port\n");
                goto err6;
        }

        spin_lock_bh(&br->lock);
        changed_addr = br_stp_recalculate_bridge_id(br);

        if (netif_running(dev) && netif_oper_up(dev) &&
            (br->dev->flags & IFF_UP))
                br_stp_enable_port(p);
        spin_unlock_bh(&br->lock);

        br_ifinfo_notify(RTM_NEWLINK, NULL, p);

        if (changed_addr)
                call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

        br_mtu_auto_adjust(br);
        br_set_gso_limits(br);

        kobject_uevent(&p->kobj, KOBJ_ADD);

        return 0;

err6:
        if (fdb_synced)
                br_fdb_unsync_static(br, p);
        list_del_rcu(&p->list);
        br_fdb_delete_by_port(br, p, 0, 1);
        nbp_update_port_count(br);
        netdev_upper_dev_unlink(dev, br->dev);
err5:
        dev->priv_flags &= ~IFF_BRIDGE_PORT;
        netdev_rx_handler_unregister(dev);
err4:
        br_netpoll_disable(p);
err3:
        sysfs_remove_link(br->ifobj, p->dev->name);
err2:
        br_multicast_del_port(p);
        kobject_put(&p->kobj);
        dev_set_allmulti(dev, -1);
err1:
        dev_put(dev);
        return err;
}

/* called with RTNL */
int br_del_if(struct net_bridge *br, struct net_device *dev)
{
        struct net_bridge_port *p;
        bool changed_addr;

        p = br_port_get_rtnl(dev);
        if (!p || p->br != br)
                return -EINVAL;

        /* Since more than one interface can be attached to a bridge,
         * there still maybe an alternate path for netconsole to use;
         * therefore there is no reason for a NETDEV_RELEASE event.
         */
        del_nbp(p);

        br_mtu_auto_adjust(br);
        br_set_gso_limits(br);

        spin_lock_bh(&br->lock);
        changed_addr = br_stp_recalculate_bridge_id(br);
        spin_unlock_bh(&br->lock);

        if (changed_addr)
                call_netdevice_notifiers(NETDEV_CHANGEADDR, br->dev);

        netdev_update_features(br->dev);

        return 0;
}

void br_port_flags_change(struct net_bridge_port *p, unsigned long mask)
{
        struct net_bridge *br = p->br;

        if (mask & BR_AUTO_MASK)
                nbp_update_port_count(br);

        if (mask & BR_NEIGH_SUPPRESS)
                br_recalculate_neigh_suppress_enabled(br);
}

bool br_port_flag_is_set(const struct net_device *dev, unsigned long flag)
{
        struct net_bridge_port *p;

        p = br_port_get_rtnl_rcu(dev);
        if (!p)
                return false;

        return p->flags & flag;
}
EXPORT_SYMBOL_GPL(br_port_flag_is_set);