// 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);

			/* 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);