/*
   * INET		An implementation of the TCP/IP protocol suite for the LINUX
   *		operating system.  INET is implemented using the  BSD Socket
   *		interface as the means of communication with the user level.
   *
   *		IPv4 Forwarding Information Base: policy rules.
   *

   * Authors:	Alexey Kuznetsov, <kuznet@ms2.inr.ac.ru>

   *		Thomas Graf <tgraf@suug.ch>

   *
   *		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.
   *
   * Fixes:

   *		Rani Assaf	:	local_rule cannot be deleted

   *		Marc Boucher	:	routing by fwmark
   */

  #include <linux/types.h>
  #include <linux/kernel.h>

  #include <linux/netdevice.h>

  #include <linux/netlink.h>

  #include <linux/inetdevice.h>

  #include <linux/init.h>

  #include <linux/list.h>
  #include <linux/rcupdate.h>

  #include <linux/export.h>

  #include <net/ip.h>

  #include <net/route.h>
  #include <net/tcp.h>

  #include <net/ip_fib.h>

  #include <net/fib_rules.h>

  struct fib4_rule {

  	struct fib_rule		common;
  	u8			dst_len;
  	u8			src_len;
  	u8			tos;

  	__be32			src;
  	__be32			srcmask;
  	__be32			dst;
  	__be32			dstmask;

  #ifdef CONFIG_IP_ROUTE_CLASSID

  	u32			tclassid;

  #endif

  };

  static bool fib4_rule_matchall(const struct fib_rule *rule)
  {
  	struct fib4_rule *r = container_of(rule, struct fib4_rule, common);
  
  	if (r->dst_len || r->src_len || r->tos)
  		return false;
  	return fib_rule_matchall(rule);
  }
  
  bool fib4_rule_default(const struct fib_rule *rule)
  {
  	if (!fib4_rule_matchall(rule) || rule->action != FR_ACT_TO_TBL ||
  	    rule->l3mdev)
  		return false;
  	if (rule->table != RT_TABLE_LOCAL && rule->table != RT_TABLE_MAIN &&
  	    rule->table != RT_TABLE_DEFAULT)
  		return false;
  	return true;
  }
  EXPORT_SYMBOL_GPL(fib4_rule_default);

  int fib4_rules_dump(struct net *net, struct notifier_block *nb)
  {
  	return fib_rules_dump(net, nb, AF_INET);
  }
  
  unsigned int fib4_rules_seq_read(struct net *net)
  {
  	return fib_rules_seq_read(net, AF_INET);
  }

  int __fib_lookup(struct net *net, struct flowi4 *flp,
  		 struct fib_result *res, unsigned int flags)

  {
  	struct fib_lookup_arg arg = {
  		.result = res,

  		.flags = flags,

  	};
  	int err;

  	/* update flow if oif or iif point to device enslaved to l3mdev */
  	l3mdev_update_flow(net, flowi4_to_flowi(flp));

  	err = fib_rules_lookup(net->ipv4.rules_ops, flowi4_to_flowi(flp), 0, &arg);

  #ifdef CONFIG_IP_ROUTE_CLASSID
  	if (arg.rule)
  		res->tclassid = ((struct fib4_rule *)arg.rule)->tclassid;
  	else
  		res->tclassid = 0;
  #endif

  
  	if (err == -ESRCH)
  		err = -ENETUNREACH;

  	return err;
  }

  EXPORT_SYMBOL_GPL(__fib_lookup);

  static int fib4_rule_action(struct fib_rule *rule, struct flowi *flp,
  			    int flags, struct fib_lookup_arg *arg)

  {

  	int err = -EAGAIN;
  	struct fib_table *tbl;

  	u32 tb_id;

  
  	switch (rule->action) {
  	case FR_ACT_TO_TBL:
  		break;
  
  	case FR_ACT_UNREACHABLE:

  		return -ENETUNREACH;

  
  	case FR_ACT_PROHIBIT:

  		return -EACCES;

  
  	case FR_ACT_BLACKHOLE:
  	default:

  		return -EINVAL;

  	}

  	rcu_read_lock();

  	tb_id = fib_rule_get_table(rule, arg);
  	tbl = fib_get_table(rule->fr_net, tb_id);

  	if (tbl)
  		err = fib_table_lookup(tbl, &flp->u.ip4,
  				       (struct fib_result *)arg->result,
  				       arg->flags);

  	rcu_read_unlock();

  	return err;
  }

  static bool fib4_rule_suppress(struct fib_rule *rule, struct fib_lookup_arg *arg)
  {

  	struct fib_result *result = (struct fib_result *) arg->result;

  	struct net_device *dev = NULL;
  
  	if (result->fi)
  		dev = result->fi->fib_dev;

  	/* do not accept result if the route does
  	 * not meet the required prefix length
  	 */

  	if (result->prefixlen <= rule->suppress_prefixlen)

  		goto suppress_route;
  
  	/* do not accept result if the route uses a device
  	 * belonging to a forbidden interface group
  	 */
  	if (rule->suppress_ifgroup != -1 && dev && dev->group == rule->suppress_ifgroup)
  		goto suppress_route;

  	return false;

  
  suppress_route:
  	if (!(arg->flags & FIB_LOOKUP_NOREF))
  		fib_info_put(result->fi);
  	return true;

  }

  static int fib4_rule_match(struct fib_rule *rule, struct flowi *fl, int flags)
  {
  	struct fib4_rule *r = (struct fib4_rule *) rule;

  	struct flowi4 *fl4 = &fl->u.ip4;
  	__be32 daddr = fl4->daddr;
  	__be32 saddr = fl4->saddr;

  
  	if (((saddr ^ r->src) & r->srcmask) ||
  	    ((daddr ^ r->dst) & r->dstmask))
  		return 0;

  	if (r->tos && (r->tos != fl4->flowi4_tos))

  		return 0;

  	return 1;
  }

  static struct fib_table *fib_empty_table(struct net *net)

  {

  	u32 id;

  
  	for (id = 1; id <= RT_TABLE_MAX; id++)

  		if (!fib_get_table(net, id))

  			return fib_new_table(net, id);

  	return NULL;
  }

  static const struct nla_policy fib4_rule_policy[FRA_MAX+1] = {

  	FRA_GENERIC_POLICY,

  	[FRA_FLOW]	= { .type = NLA_U32 },
  };

  static int fib4_rule_configure(struct fib_rule *rule, struct sk_buff *skb,

  			       struct fib_rule_hdr *frh,

  			       struct nlattr **tb)

  {

  	struct net *net = sock_net(skb->sk);

  	int err = -EINVAL;
  	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

  	if (frh->tos & ~IPTOS_TOS_MASK)

  		goto errout;

  	/* split local/main if they are not already split */
  	err = fib_unmerge(net);
  	if (err)
  		goto errout;

  	if (rule->table == RT_TABLE_UNSPEC && !rule->l3mdev) {

  		if (rule->action == FR_ACT_TO_TBL) {
  			struct fib_table *table;

  			table = fib_empty_table(net);

  			if (!table) {

  				err = -ENOBUFS;
  				goto errout;
  			}

  			rule->table = table->tb_id;

  		}
  	}

  	if (frh->src_len)

  		rule4->src = nla_get_in_addr(tb[FRA_SRC]);

  	if (frh->dst_len)

  		rule4->dst = nla_get_in_addr(tb[FRA_DST]);

  #ifdef CONFIG_IP_ROUTE_CLASSID

  	if (tb[FRA_FLOW]) {

  		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);

  		if (rule4->tclassid)

  			net->ipv4.fib_num_tclassid_users++;

  	}

  #endif

  	rule4->src_len = frh->src_len;
  	rule4->srcmask = inet_make_mask(rule4->src_len);
  	rule4->dst_len = frh->dst_len;
  	rule4->dstmask = inet_make_mask(rule4->dst_len);
  	rule4->tos = frh->tos;

  	net->ipv4.fib_has_custom_rules = true;

  	err = 0;
  errout:
  	return err;

  }

  static int fib4_rule_delete(struct fib_rule *rule)

  {

  	struct net *net = rule->fr_net;

  	int err;

  	/* split local/main if they are not already split */
  	err = fib_unmerge(net);
  	if (err)
  		goto errout;
  
  #ifdef CONFIG_IP_ROUTE_CLASSID
  	if (((struct fib4_rule *)rule)->tclassid)

  		net->ipv4.fib_num_tclassid_users--;

  #endif

  	net->ipv4.fib_has_custom_rules = true;

  errout:
  	return err;

  }

  static int fib4_rule_compare(struct fib_rule *rule, struct fib_rule_hdr *frh,
  			     struct nlattr **tb)

  {

  	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

  	if (frh->src_len && (rule4->src_len != frh->src_len))
  		return 0;

  	if (frh->dst_len && (rule4->dst_len != frh->dst_len))
  		return 0;

  	if (frh->tos && (rule4->tos != frh->tos))
  		return 0;

  #ifdef CONFIG_IP_ROUTE_CLASSID

  	if (tb[FRA_FLOW] && (rule4->tclassid != nla_get_u32(tb[FRA_FLOW])))
  		return 0;
  #endif

  	if (frh->src_len && (rule4->src != nla_get_in_addr(tb[FRA_SRC])))

  		return 0;

  	if (frh->dst_len && (rule4->dst != nla_get_in_addr(tb[FRA_DST])))

  		return 0;

  	return 1;

  }

  static int fib4_rule_fill(struct fib_rule *rule, struct sk_buff *skb,

  			  struct fib_rule_hdr *frh)

  {
  	struct fib4_rule *rule4 = (struct fib4_rule *) rule;

  	frh->dst_len = rule4->dst_len;
  	frh->src_len = rule4->src_len;
  	frh->tos = rule4->tos;

  	if ((rule4->dst_len &&

  	     nla_put_in_addr(skb, FRA_DST, rule4->dst)) ||

  	    (rule4->src_len &&

  	     nla_put_in_addr(skb, FRA_SRC, rule4->src)))

  		goto nla_put_failure;

  #ifdef CONFIG_IP_ROUTE_CLASSID

  	if (rule4->tclassid &&
  	    nla_put_u32(skb, FRA_FLOW, rule4->tclassid))
  		goto nla_put_failure;

  #endif

  	return 0;

  nla_put_failure:
  	return -ENOBUFS;

  }

  static size_t fib4_rule_nlmsg_payload(struct fib_rule *rule)
  {
  	return nla_total_size(4) /* dst */
  	       + nla_total_size(4) /* src */
  	       + nla_total_size(4); /* flow */
  }

  static void fib4_rule_flush_cache(struct fib_rules_ops *ops)

  {

  	rt_cache_flush(ops->fro_net);

  }

  static const struct fib_rules_ops __net_initconst fib4_rules_ops_template = {

  	.family		= AF_INET,

  	.rule_size	= sizeof(struct fib4_rule),

  	.addr_size	= sizeof(u32),

  	.action		= fib4_rule_action,

  	.suppress	= fib4_rule_suppress,

  	.match		= fib4_rule_match,
  	.configure	= fib4_rule_configure,

  	.delete		= fib4_rule_delete,

  	.compare	= fib4_rule_compare,
  	.fill		= fib4_rule_fill,

  	.nlmsg_payload	= fib4_rule_nlmsg_payload,

  	.flush_cache	= fib4_rule_flush_cache,

  	.nlgroup	= RTNLGRP_IPV4_RULE,
  	.policy		= fib4_rule_policy,

  	.owner		= THIS_MODULE,
  };

  static int fib_default_rules_init(struct fib_rules_ops *ops)

  {

  	int err;

  	err = fib_default_rule_add(ops, 0, RT_TABLE_LOCAL, 0);

  	if (err < 0)
  		return err;

  	err = fib_default_rule_add(ops, 0x7FFE, RT_TABLE_MAIN, 0);

  	if (err < 0)
  		return err;

  	err = fib_default_rule_add(ops, 0x7FFF, RT_TABLE_DEFAULT, 0);

  	if (err < 0)
  		return err;
  	return 0;
  }

  int __net_init fib4_rules_init(struct net *net)

  {

  	int err;

  	struct fib_rules_ops *ops;

  	ops = fib_rules_register(&fib4_rules_ops_template, net);
  	if (IS_ERR(ops))
  		return PTR_ERR(ops);

  	err = fib_default_rules_init(ops);

  	if (err < 0)
  		goto fail;

  	net->ipv4.rules_ops = ops;

  	net->ipv4.fib_has_custom_rules = false;

  	return 0;
  
  fail:
  	/* also cleans all rules already added */

  	fib_rules_unregister(ops);

  	return err;

  }

  
  void __net_exit fib4_rules_exit(struct net *net)
  {

  	fib_rules_unregister(net->ipv4.rules_ops);

  }