// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * net/l3mdev/l3mdev.c - L3 master device implementation
 * Copyright (c) 2015 Cumulus Networks
 * Copyright (c) 2015 David Ahern <dsa@cumulusnetworks.com>
 */

#include <linux/netdevice.h>
#include <net/fib_rules.h>
#include <net/l3mdev.h>

static DEFINE_SPINLOCK(l3mdev_lock);

struct l3mdev_handler {
        lookup_by_table_id_t dev_lookup;
};

static struct l3mdev_handler l3mdev_handlers[L3MDEV_TYPE_MAX + 1];

static int l3mdev_check_type(enum l3mdev_type l3type)
{
        if (l3type <= L3MDEV_TYPE_UNSPEC || l3type > L3MDEV_TYPE_MAX)
                return -EINVAL;

        return 0;
}

int l3mdev_table_lookup_register(enum l3mdev_type l3type,
                                 lookup_by_table_id_t fn)
{
        struct l3mdev_handler *hdlr;
        int res;

        res = l3mdev_check_type(l3type);
        if (res)
                return res;

        hdlr = &l3mdev_handlers[l3type];

        spin_lock(&l3mdev_lock);

        if (hdlr->dev_lookup) {
                res = -EBUSY;
                goto unlock;
        }

        hdlr->dev_lookup = fn;
        res = 0;

unlock:
        spin_unlock(&l3mdev_lock);

        return res;
}
EXPORT_SYMBOL_GPL(l3mdev_table_lookup_register);

void l3mdev_table_lookup_unregister(enum l3mdev_type l3type,
                                    lookup_by_table_id_t fn)
{
        struct l3mdev_handler *hdlr;

        if (l3mdev_check_type(l3type))
                return;

        hdlr = &l3mdev_handlers[l3type];

        spin_lock(&l3mdev_lock);

        if (hdlr->dev_lookup == fn)
                hdlr->dev_lookup = NULL;

        spin_unlock(&l3mdev_lock);
}
EXPORT_SYMBOL_GPL(l3mdev_table_lookup_unregister);

int l3mdev_ifindex_lookup_by_table_id(enum l3mdev_type l3type,
                                      struct net *net, u32 table_id)
{
        lookup_by_table_id_t lookup;
        struct l3mdev_handler *hdlr;
        int ifindex = -EINVAL;
        int res;

        res = l3mdev_check_type(l3type);
        if (res)
                return res;

        hdlr = &l3mdev_handlers[l3type];

        spin_lock(&l3mdev_lock);

        lookup = hdlr->dev_lookup;
        if (!lookup)
                goto unlock;

        ifindex = lookup(net, table_id);

unlock:
        spin_unlock(&l3mdev_lock);

        return ifindex;
}
EXPORT_SYMBOL_GPL(l3mdev_ifindex_lookup_by_table_id);

/**
 *      l3mdev_master_ifindex_rcu - get index of L3 master device
 *      @dev: targeted interface
 */

int l3mdev_master_ifindex_rcu(const struct net_device *dev)
{
        int ifindex = 0;

        if (!dev)
                return 0;

        if (netif_is_l3_master(dev)) {
                ifindex = dev->ifindex;
        } else if (netif_is_l3_slave(dev)) {
                struct net_device *master;
                struct net_device *_dev = (struct net_device *)dev;

                /* netdev_master_upper_dev_get_rcu calls
                 * list_first_or_null_rcu to walk the upper dev list.
                 * list_first_or_null_rcu does not handle a const arg. We aren't
                 * making changes, just want the master device from that list so
                 * typecast to remove the const
                 */
                master = netdev_master_upper_dev_get_rcu(_dev);
                if (master)
                        ifindex = master->ifindex;
        }

        return ifindex;
}
EXPORT_SYMBOL_GPL(l3mdev_master_ifindex_rcu);

/**
 *      l3mdev_master_upper_ifindex_by_index_rcu - get index of upper l3 master
 *                                             device
 *      @net: network namespace for device index lookup
 *      @ifindex: targeted interface
 */
int l3mdev_master_upper_ifindex_by_index_rcu(struct net *net, int ifindex)
{
        struct net_device *dev;

        dev = dev_get_by_index_rcu(net, ifindex);
        while (dev && !netif_is_l3_master(dev))
                dev = netdev_master_upper_dev_get_rcu(dev);

        return dev ? dev->ifindex : 0;
}
EXPORT_SYMBOL_GPL(l3mdev_master_upper_ifindex_by_index_rcu);

/**
 *      l3mdev_fib_table_rcu - get FIB table id associated with an L3
 *                             master interface
 *      @dev: targeted interface
 */

u32 l3mdev_fib_table_rcu(const struct net_device *dev)
{
        u32 tb_id = 0;

        if (!dev)
                return 0;

        if (netif_is_l3_master(dev)) {
                if (dev->l3mdev_ops->l3mdev_fib_table)
                        tb_id = dev->l3mdev_ops->l3mdev_fib_table(dev);
        } else if (netif_is_l3_slave(dev)) {
                /* Users of netdev_master_upper_dev_get_rcu need non-const,
                 * but current inet_*type functions take a const
                 */
                struct net_device *_dev = (struct net_device *) dev;
                const struct net_device *master;

                master = netdev_master_upper_dev_get_rcu(_dev);
                if (master &&
                    master->l3mdev_ops->l3mdev_fib_table)
                        tb_id = master->l3mdev_ops->l3mdev_fib_table(master);
        }

        return tb_id;
}
EXPORT_SYMBOL_GPL(l3mdev_fib_table_rcu);

u32 l3mdev_fib_table_by_index(struct net *net, int ifindex)
{
        struct net_device *dev;
        u32 tb_id = 0;

        if (!ifindex)
                return 0;

        rcu_read_lock();

        dev = dev_get_by_index_rcu(net, ifindex);
        if (dev)
                tb_id = l3mdev_fib_table_rcu(dev);

        rcu_read_unlock();

        return tb_id;
}
EXPORT_SYMBOL_GPL(l3mdev_fib_table_by_index);

/**
 *      l3mdev_link_scope_lookup - IPv6 route lookup based on flow for link
 *                           local and multicast addresses
 *      @net: network namespace for device index lookup
 *      @fl6: IPv6 flow struct for lookup
 *      This function does not hold refcnt on the returned dst.
 *      Caller must hold rcu_read_lock().
 */

struct dst_entry *l3mdev_link_scope_lookup(struct net *net,
                                           struct flowi6 *fl6)
{
        struct dst_entry *dst = NULL;
        struct net_device *dev;

        WARN_ON_ONCE(!rcu_read_lock_held());
        if (fl6->flowi6_oif) {
                dev = dev_get_by_index_rcu(net, fl6->flowi6_oif);
                if (dev && netif_is_l3_slave(dev))
                        dev = netdev_master_upper_dev_get_rcu(dev);

                if (dev && netif_is_l3_master(dev) &&
                    dev->l3mdev_ops->l3mdev_link_scope_lookup)
                        dst = dev->l3mdev_ops->l3mdev_link_scope_lookup(dev, fl6);
        }

        return dst;
}
EXPORT_SYMBOL_GPL(l3mdev_link_scope_lookup);

/**
 *      l3mdev_fib_rule_match - Determine if flowi references an
 *                              L3 master device
 *      @net: network namespace for device index lookup
 *      @fl:  flow struct
 *      @arg: store the table the rule matched with here
 */

int l3mdev_fib_rule_match(struct net *net, struct flowi *fl,
                          struct fib_lookup_arg *arg)
{
        struct net_device *dev;
        int rc = 0;

        /* update flow ensures flowi_l3mdev is set when relevant */
        if (!fl->flowi_l3mdev)
                return 0;

        rcu_read_lock();

        dev = dev_get_by_index_rcu(net, fl->flowi_l3mdev);
        if (dev && netif_is_l3_master(dev) &&
            dev->l3mdev_ops->l3mdev_fib_table) {
                arg->table = dev->l3mdev_ops->l3mdev_fib_table(dev);
                rc = 1;
        }

        rcu_read_unlock();

        return rc;
}

void l3mdev_update_flow(struct net *net, struct flowi *fl)
{
        struct net_device *dev;

        rcu_read_lock();

        if (fl->flowi_oif) {
                dev = dev_get_by_index_rcu(net, fl->flowi_oif);
                if (dev) {
                        if (!fl->flowi_l3mdev) {
                                fl->flowi_l3mdev = l3mdev_master_ifindex_rcu(dev);
                                fl->flowi_flags |= FLOWI_FLAG_L3MDEV_OIF;
                        }

                        /* oif set to L3mdev directs lookup to its table;
                         * reset to avoid oif match in fib_lookup
                         */
                        if (netif_is_l3_master(dev))
                                fl->flowi_oif = 0;
                        goto out;
                }
        }

        if (fl->flowi_iif > LOOPBACK_IFINDEX && !fl->flowi_l3mdev) {
                dev = dev_get_by_index_rcu(net, fl->flowi_iif);
                if (dev)
                        fl->flowi_l3mdev = l3mdev_master_ifindex_rcu(dev);
        }

out:
        rcu_read_unlock();
}
EXPORT_SYMBOL_GPL(l3mdev_update_flow);