net/core/fib_rules.c - kernel/msm-4.9 - Gitiles

 /*
  * net/core/fib_rules.c		Generic Routing Rules
  *
  *	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, version 2.
  *
  * Authors:	Thomas Graf <tgraf@suug.ch>
  */

 #include <linux/types.h>
 #include <linux/kernel.h>
 #include <linux/slab.h>
 #include <linux/list.h>
 #include <net/net_namespace.h>
 #include <net/sock.h>
 #include <net/fib_rules.h>

 int fib_default_rule_add(struct fib_rules_ops *ops,
 			 u32 pref, u32 table, u32 flags)
 {
 	struct fib_rule *r;

 	r = kzalloc(ops->rule_size, GFP_KERNEL);
 	if (r == NULL)
 		return -ENOMEM;

 	atomic_set(&r->refcnt, 1);
 	r->action = FR_ACT_TO_TBL;
 	r->pref = pref;
 	r->table = table;
 	r->flags = flags;
 	r->fr_net = hold_net(ops->fro_net);

 	/* The lock is not required here, the list in unreacheable
 	 * at the moment this function is called */
 	list_add_tail(&r->list, &ops->rules_list);
 	return 0;
 }
 EXPORT_SYMBOL(fib_default_rule_add);

 u32 fib_default_rule_pref(struct fib_rules_ops *ops)
 {
 	struct list_head *pos;
 	struct fib_rule *rule;

 	if (!list_empty(&ops->rules_list)) {
 		pos = ops->rules_list.next;
 		if (pos->next != &ops->rules_list) {
 			rule = list_entry(pos->next, struct fib_rule, list);
 			if (rule->pref)
 				return rule->pref - 1;
 		}
 	}

 	return 0;
 }
 EXPORT_SYMBOL(fib_default_rule_pref);

 static void notify_rule_change(int event, struct fib_rule *rule,
 			       struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 			       u32 pid);

 static struct fib_rules_ops *lookup_rules_ops(struct net *net, int family)
 {
 	struct fib_rules_ops *ops;

 	rcu_read_lock();
 	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
 		if (ops->family == family) {
 			if (!try_module_get(ops->owner))
 				ops = NULL;
 			rcu_read_unlock();
 			return ops;
 		}
 	}
 	rcu_read_unlock();

 	return NULL;
 }

 static void rules_ops_put(struct fib_rules_ops *ops)
 {
 	if (ops)
 		module_put(ops->owner);
 }

 static void flush_route_cache(struct fib_rules_ops *ops)
 {
 	if (ops->flush_cache)
 		ops->flush_cache(ops);
 }

 static int __fib_rules_register(struct fib_rules_ops *ops)
 {
 	int err = -EEXIST;
 	struct fib_rules_ops *o;
 	struct net *net;

 	net = ops->fro_net;

 	if (ops->rule_size < sizeof(struct fib_rule))
 		return -EINVAL;

 	if (ops->match == NULL || ops->configure == NULL ||
 	    ops->compare == NULL || ops->fill == NULL ||
 	    ops->action == NULL)
 		return -EINVAL;

 	spin_lock(&net->rules_mod_lock);
 	list_for_each_entry(o, &net->rules_ops, list)
 		if (ops->family == o->family)
 			goto errout;

 	hold_net(net);
 	list_add_tail_rcu(&ops->list, &net->rules_ops);
 	err = 0;
 errout:
 	spin_unlock(&net->rules_mod_lock);

 	return err;
 }

 struct fib_rules_ops *
 fib_rules_register(const struct fib_rules_ops *tmpl, struct net *net)
 {
 	struct fib_rules_ops *ops;
 	int err;

 	ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
 	if (ops == NULL)
 		return ERR_PTR(-ENOMEM);

 	INIT_LIST_HEAD(&ops->rules_list);
 	ops->fro_net = net;

 	err = __fib_rules_register(ops);
 	if (err) {
 		kfree(ops);
 		ops = ERR_PTR(err);
 	}

 	return ops;
 }
 EXPORT_SYMBOL_GPL(fib_rules_register);

 static void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
 {
 	struct fib_rule *rule, *tmp;

 	list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
 		list_del_rcu(&rule->list);
 		fib_rule_put(rule);
 	}
 }

 static void fib_rules_put_rcu(struct rcu_head *head)
 {
 	struct fib_rules_ops *ops = container_of(head, struct fib_rules_ops, rcu);
 	struct net *net = ops->fro_net;

 	release_net(net);
 	kfree(ops);
 }

 void fib_rules_unregister(struct fib_rules_ops *ops)
 {
 	struct net *net = ops->fro_net;

 	spin_lock(&net->rules_mod_lock);
 	list_del_rcu(&ops->list);
 	fib_rules_cleanup_ops(ops);
 	spin_unlock(&net->rules_mod_lock);

 	call_rcu(&ops->rcu, fib_rules_put_rcu);
 }
 EXPORT_SYMBOL_GPL(fib_rules_unregister);

 static int fib_rule_match(struct fib_rule *rule, struct fib_rules_ops *ops,
 			  struct flowi *fl, int flags)
 {
 	int ret = 0;

 	if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
 		goto out;

 	if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
 		goto out;

 	if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
 		goto out;

 	ret = ops->match(rule, fl, flags);
 out:
 	return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
 }

 int fib_rules_lookup(struct fib_rules_ops *ops, struct flowi *fl,
 		     int flags, struct fib_lookup_arg *arg)
 {
 	struct fib_rule *rule;
 	int err;

 	rcu_read_lock();

 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 jumped:
 		if (!fib_rule_match(rule, ops, fl, flags))
 			continue;

 		if (rule->action == FR_ACT_GOTO) {
 			struct fib_rule *target;

 			target = rcu_dereference(rule->ctarget);
 			if (target == NULL) {
 				continue;
 			} else {
 				rule = target;
 				goto jumped;
 			}
 		} else if (rule->action == FR_ACT_NOP)
 			continue;
 		else
 			err = ops->action(rule, fl, flags, arg);

 		if (err != -EAGAIN) {
 			if ((arg->flags & FIB_LOOKUP_NOREF) ||
 			    likely(atomic_inc_not_zero(&rule->refcnt))) {
 				arg->rule = rule;
 				goto out;
 			}
 			break;
 		}
 	}

 	err = -ESRCH;
 out:
 	rcu_read_unlock();

 	return err;
 }
 EXPORT_SYMBOL_GPL(fib_rules_lookup);

 static int validate_rulemsg(struct fib_rule_hdr *frh, struct nlattr **tb,
 			    struct fib_rules_ops *ops)
 {
 	int err = -EINVAL;

 	if (frh->src_len)
 		if (tb[FRA_SRC] == NULL ||
 		    frh->src_len > (ops->addr_size * 8) ||
 		    nla_len(tb[FRA_SRC]) != ops->addr_size)
 			goto errout;

 	if (frh->dst_len)
 		if (tb[FRA_DST] == NULL ||
 		    frh->dst_len > (ops->addr_size * 8) ||
 		    nla_len(tb[FRA_DST]) != ops->addr_size)
 			goto errout;

 	err = 0;
 errout:
 	return err;
 }

 static int fib_nl_newrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
 	struct net *net = sock_net(skb->sk);
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
 	struct fib_rules_ops *ops = NULL;
 	struct fib_rule *rule, *r, *last = NULL;
 	struct nlattr *tb[FRA_MAX+1];
 	int err = -EINVAL, unresolved = 0;

 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 		goto errout;

 	ops = lookup_rules_ops(net, frh->family);
 	if (ops == NULL) {
 		err = -EAFNOSUPPORT;
 		goto errout;
 	}

 	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 	if (err < 0)
 		goto errout;

 	err = validate_rulemsg(frh, tb, ops);
 	if (err < 0)
 		goto errout;

 	rule = kzalloc(ops->rule_size, GFP_KERNEL);
 	if (rule == NULL) {
 		err = -ENOMEM;
 		goto errout;
 	}
 	rule->fr_net = hold_net(net);

 	if (tb[FRA_PRIORITY])
 		rule->pref = nla_get_u32(tb[FRA_PRIORITY]);

 	if (tb[FRA_IIFNAME]) {
 		struct net_device *dev;

 		rule->iifindex = -1;
 		nla_strlcpy(rule->iifname, tb[FRA_IIFNAME], IFNAMSIZ);
 		dev = __dev_get_by_name(net, rule->iifname);
 		if (dev)
 			rule->iifindex = dev->ifindex;
 	}

 	if (tb[FRA_OIFNAME]) {
 		struct net_device *dev;

 		rule->oifindex = -1;
 		nla_strlcpy(rule->oifname, tb[FRA_OIFNAME], IFNAMSIZ);
 		dev = __dev_get_by_name(net, rule->oifname);
 		if (dev)
 			rule->oifindex = dev->ifindex;
 	}

 	if (tb[FRA_FWMARK]) {
 		rule->mark = nla_get_u32(tb[FRA_FWMARK]);
 		if (rule->mark)
 			/* compatibility: if the mark value is non-zero all bits
 			 * are compared unless a mask is explicitly specified.
 			 */
 			rule->mark_mask = 0xFFFFFFFF;
 	}

 	if (tb[FRA_FWMASK])
 		rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);

 	rule->action = frh->action;
 	rule->flags = frh->flags;
 	rule->table = frh_get_table(frh, tb);

 	if (!tb[FRA_PRIORITY] && ops->default_pref)
 		rule->pref = ops->default_pref(ops);

 	err = -EINVAL;
 	if (tb[FRA_GOTO]) {
 		if (rule->action != FR_ACT_GOTO)
 			goto errout_free;

 		rule->target = nla_get_u32(tb[FRA_GOTO]);
 		/* Backward jumps are prohibited to avoid endless loops */
 		if (rule->target <= rule->pref)
 			goto errout_free;

 		list_for_each_entry(r, &ops->rules_list, list) {
 			if (r->pref == rule->target) {
 				RCU_INIT_POINTER(rule->ctarget, r);
 				break;
 			}
 		}

 		if (rcu_dereference_protected(rule->ctarget, 1) == NULL)
 			unresolved = 1;
 	} else if (rule->action == FR_ACT_GOTO)
 		goto errout_free;

 	err = ops->configure(rule, skb, frh, tb);
 	if (err < 0)
 		goto errout_free;

 	list_for_each_entry(r, &ops->rules_list, list) {
 		if (r->pref > rule->pref)
 			break;
 		last = r;
 	}

 	fib_rule_get(rule);

 	if (last)
 		list_add_rcu(&rule->list, &last->list);
 	else
 		list_add_rcu(&rule->list, &ops->rules_list);

 	if (ops->unresolved_rules) {
 		/*
 		 * There are unresolved goto rules in the list, check if
 		 * any of them are pointing to this new rule.
 		 */
 		list_for_each_entry(r, &ops->rules_list, list) {
 			if (r->action == FR_ACT_GOTO &&
 			    r->target == rule->pref) {
 				BUG_ON(rtnl_dereference(r->ctarget) != NULL);
 				rcu_assign_pointer(r->ctarget, rule);
 				if (--ops->unresolved_rules == 0)
 					break;
 			}
 		}
 	}

 	if (rule->action == FR_ACT_GOTO)
 		ops->nr_goto_rules++;

 	if (unresolved)
 		ops->unresolved_rules++;

 	notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
 	flush_route_cache(ops);
 	rules_ops_put(ops);
 	return 0;

 errout_free:
 	release_net(rule->fr_net);
 	kfree(rule);
 errout:
 	rules_ops_put(ops);
 	return err;
 }

 static int fib_nl_delrule(struct sk_buff *skb, struct nlmsghdr* nlh, void *arg)
 {
 	struct net *net = sock_net(skb->sk);
 	struct fib_rule_hdr *frh = nlmsg_data(nlh);
 	struct fib_rules_ops *ops = NULL;
 	struct fib_rule *rule, *tmp;
 	struct nlattr *tb[FRA_MAX+1];
 	int err = -EINVAL;

 	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
 		goto errout;

 	ops = lookup_rules_ops(net, frh->family);
 	if (ops == NULL) {
 		err = -EAFNOSUPPORT;
 		goto errout;
 	}

 	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
 	if (err < 0)
 		goto errout;

 	err = validate_rulemsg(frh, tb, ops);
 	if (err < 0)
 		goto errout;

 	list_for_each_entry(rule, &ops->rules_list, list) {
 		if (frh->action && (frh->action != rule->action))
 			continue;

 		if (frh->table && (frh_get_table(frh, tb) != rule->table))
 			continue;

 		if (tb[FRA_PRIORITY] &&
 		    (rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
 			continue;

 		if (tb[FRA_IIFNAME] &&
 		    nla_strcmp(tb[FRA_IIFNAME], rule->iifname))
 			continue;

 		if (tb[FRA_OIFNAME] &&
 		    nla_strcmp(tb[FRA_OIFNAME], rule->oifname))
 			continue;

 		if (tb[FRA_FWMARK] &&
 		    (rule->mark != nla_get_u32(tb[FRA_FWMARK])))
 			continue;

 		if (tb[FRA_FWMASK] &&
 		    (rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
 			continue;

 		if (!ops->compare(rule, frh, tb))
 			continue;

 		if (rule->flags & FIB_RULE_PERMANENT) {
 			err = -EPERM;
 			goto errout;
 		}

 		list_del_rcu(&rule->list);

 		if (rule->action == FR_ACT_GOTO)
 			ops->nr_goto_rules--;

 		/*
 		 * Check if this rule is a target to any of them. If so,
 		 * disable them. As this operation is eventually very
 		 * expensive, it is only performed if goto rules have
 		 * actually been added.
 		 */
 		if (ops->nr_goto_rules > 0) {
 			list_for_each_entry(tmp, &ops->rules_list, list) {
 				if (rtnl_dereference(tmp->ctarget) == rule) {
 					rcu_assign_pointer(tmp->ctarget, NULL);
 					ops->unresolved_rules++;
 				}
 			}
 		}

 		notify_rule_change(RTM_DELRULE, rule, ops, nlh,
 				   NETLINK_CB(skb).pid);
 		fib_rule_put(rule);
 		flush_route_cache(ops);
 		rules_ops_put(ops);
 		return 0;
 	}

 	err = -ENOENT;
 errout:
 	rules_ops_put(ops);
 	return err;
 }

 static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
 					 struct fib_rule *rule)
 {
 	size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
 			 + nla_total_size(IFNAMSIZ) /* FRA_IIFNAME */
 			 + nla_total_size(IFNAMSIZ) /* FRA_OIFNAME */
 			 + nla_total_size(4) /* FRA_PRIORITY */
 			 + nla_total_size(4) /* FRA_TABLE */
 			 + nla_total_size(4) /* FRA_FWMARK */
 			 + nla_total_size(4); /* FRA_FWMASK */

 	if (ops->nlmsg_payload)
 		payload += ops->nlmsg_payload(rule);

 	return payload;
 }

 static int fib_nl_fill_rule(struct sk_buff *skb, struct fib_rule *rule,
 			    u32 pid, u32 seq, int type, int flags,
 			    struct fib_rules_ops *ops)
 {
 	struct nlmsghdr *nlh;
 	struct fib_rule_hdr *frh;

 	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
 	if (nlh == NULL)
 		return -EMSGSIZE;

 	frh = nlmsg_data(nlh);
 	frh->family = ops->family;
 	frh->table = rule->table;
 	NLA_PUT_U32(skb, FRA_TABLE, rule->table);
 	frh->res1 = 0;
 	frh->res2 = 0;
 	frh->action = rule->action;
 	frh->flags = rule->flags;

 	if (rule->action == FR_ACT_GOTO &&
 	    rcu_dereference_raw(rule->ctarget) == NULL)
 		frh->flags |= FIB_RULE_UNRESOLVED;

 	if (rule->iifname[0]) {
 		NLA_PUT_STRING(skb, FRA_IIFNAME, rule->iifname);

 		if (rule->iifindex == -1)
 			frh->flags |= FIB_RULE_IIF_DETACHED;
 	}

 	if (rule->oifname[0]) {
 		NLA_PUT_STRING(skb, FRA_OIFNAME, rule->oifname);

 		if (rule->oifindex == -1)
 			frh->flags |= FIB_RULE_OIF_DETACHED;
 	}

 	if (rule->pref)
 		NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);

 	if (rule->mark)
 		NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);

 	if (rule->mark_mask || rule->mark)
 		NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);

 	if (rule->target)
 		NLA_PUT_U32(skb, FRA_GOTO, rule->target);

 	if (ops->fill(rule, skb, frh) < 0)
 		goto nla_put_failure;

 	return nlmsg_end(skb, nlh);

 nla_put_failure:
 	nlmsg_cancel(skb, nlh);
 	return -EMSGSIZE;
 }

 static int dump_rules(struct sk_buff *skb, struct netlink_callback *cb,
 		      struct fib_rules_ops *ops)
 {
 	int idx = 0;
 	struct fib_rule *rule;

 	rcu_read_lock();
 	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
 		if (idx < cb->args[1])
 			goto skip;

 		if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
 				     cb->nlh->nlmsg_seq, RTM_NEWRULE,
 				     NLM_F_MULTI, ops) < 0)
 			break;
 skip:
 		idx++;
 	}
 	cb->args[1] = idx;
 	rules_ops_put(ops);

 	return skb->len;
 }

 static int fib_nl_dumprule(struct sk_buff *skb, struct netlink_callback *cb)
 {
 	struct net *net = sock_net(skb->sk);
 	struct fib_rules_ops *ops;
 	int idx = 0, family;

 	family = rtnl_msg_family(cb->nlh);
 	if (family != AF_UNSPEC) {
 		/* Protocol specific dump request */
 		ops = lookup_rules_ops(net, family);
 		if (ops == NULL)
 			return -EAFNOSUPPORT;

 		return dump_rules(skb, cb, ops);
 	}

 	rcu_read_lock();
 	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
 		if (idx < cb->args[0] || !try_module_get(ops->owner))
 			goto skip;

 		if (dump_rules(skb, cb, ops) < 0)
 			break;

 		cb->args[1] = 0;
 skip:
 		idx++;
 	}
 	rcu_read_unlock();
 	cb->args[0] = idx;

 	return skb->len;
 }

 static void notify_rule_change(int event, struct fib_rule *rule,
 			       struct fib_rules_ops *ops, struct nlmsghdr *nlh,
 			       u32 pid)
 {
 	struct net *net;
 	struct sk_buff *skb;
 	int err = -ENOBUFS;

 	net = ops->fro_net;
 	skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
 	if (skb == NULL)
 		goto errout;

 	err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
 	if (err < 0) {
 		/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
 		WARN_ON(err == -EMSGSIZE);
 		kfree_skb(skb);
 		goto errout;
 	}

 	rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
 	return;
 errout:
 	if (err < 0)
 		rtnl_set_sk_err(net, ops->nlgroup, err);
 }

 static void attach_rules(struct list_head *rules, struct net_device *dev)
 {
 	struct fib_rule *rule;

 	list_for_each_entry(rule, rules, list) {
 		if (rule->iifindex == -1 &&
 		    strcmp(dev->name, rule->iifname) == 0)
 			rule->iifindex = dev->ifindex;
 		if (rule->oifindex == -1 &&
 		    strcmp(dev->name, rule->oifname) == 0)
 			rule->oifindex = dev->ifindex;
 	}
 }

 static void detach_rules(struct list_head *rules, struct net_device *dev)
 {
 	struct fib_rule *rule;

 	list_for_each_entry(rule, rules, list) {
 		if (rule->iifindex == dev->ifindex)
 			rule->iifindex = -1;
 		if (rule->oifindex == dev->ifindex)
 			rule->oifindex = -1;
 	}
 }


 static int fib_rules_event(struct notifier_block *this, unsigned long event,
 			    void *ptr)
 {
 	struct net_device *dev = ptr;
 	struct net *net = dev_net(dev);
 	struct fib_rules_ops *ops;

 	ASSERT_RTNL();

 	switch (event) {
 	case NETDEV_REGISTER:
 		list_for_each_entry(ops, &net->rules_ops, list)
 			attach_rules(&ops->rules_list, dev);
 		break;

 	case NETDEV_UNREGISTER:
 		list_for_each_entry(ops, &net->rules_ops, list)
 			detach_rules(&ops->rules_list, dev);
 		break;
 	}

 	return NOTIFY_DONE;
 }

 static struct notifier_block fib_rules_notifier = {
 	.notifier_call = fib_rules_event,
 };

 static int __net_init fib_rules_net_init(struct net *net)
 {
 	INIT_LIST_HEAD(&net->rules_ops);
 	spin_lock_init(&net->rules_mod_lock);
 	return 0;
 }

 static struct pernet_operations fib_rules_net_ops = {
 	.init = fib_rules_net_init,
 };

 static int __init fib_rules_init(void)
 {
 	int err;
 	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
 	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
 	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);

 	err = register_pernet_subsys(&fib_rules_net_ops);
 	if (err < 0)
 		goto fail;

 	err = register_netdevice_notifier(&fib_rules_notifier);
 	if (err < 0)
 		goto fail_unregister;

 	return 0;

 fail_unregister:
 	unregister_pernet_subsys(&fib_rules_net_ops);
 fail:
 	rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
 	rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
 	rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
 	return err;
 }

 subsys_initcall(fib_rules_init);
	/*
	* net/core/fib_rules.c Generic Routing Rules
	*
	* 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, version 2.
	*
	* Authors: Thomas Graf <tgraf@suug.ch>
	*/

	#include <linux/types.h>
	#include <linux/kernel.h>
	#include <linux/slab.h>
	#include <linux/list.h>
	#include <net/net_namespace.h>
	#include <net/sock.h>
	#include <net/fib_rules.h>

	int fib_default_rule_add(struct fib_rules_ops *ops,
	u32 pref, u32 table, u32 flags)
	{
	struct fib_rule *r;

	r = kzalloc(ops->rule_size, GFP_KERNEL);
	if (r == NULL)
	return -ENOMEM;

	atomic_set(&r->refcnt, 1);
	r->action = FR_ACT_TO_TBL;
	r->pref = pref;
	r->table = table;
	r->flags = flags;
	r->fr_net = hold_net(ops->fro_net);

	/* The lock is not required here, the list in unreacheable
	* at the moment this function is called */
	list_add_tail(&r->list, &ops->rules_list);
	return 0;
	}
	EXPORT_SYMBOL(fib_default_rule_add);

	u32 fib_default_rule_pref(struct fib_rules_ops *ops)
	{
	struct list_head *pos;
	struct fib_rule *rule;

	if (!list_empty(&ops->rules_list)) {
	pos = ops->rules_list.next;
	if (pos->next != &ops->rules_list) {
	rule = list_entry(pos->next, struct fib_rule, list);
	if (rule->pref)
	return rule->pref - 1;
	}
	}

	return 0;
	}
	EXPORT_SYMBOL(fib_default_rule_pref);

	static void notify_rule_change(int event, struct fib_rule *rule,
	struct fib_rules_ops ops, struct nlmsghdr nlh,
	u32 pid);

	static struct fib_rules_ops lookup_rules_ops(struct net net, int family)
	{
	struct fib_rules_ops *ops;

	rcu_read_lock();
	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
	if (ops->family == family) {
	if (!try_module_get(ops->owner))
	ops = NULL;
	rcu_read_unlock();
	return ops;
	}
	}
	rcu_read_unlock();

	return NULL;
	}

	static void rules_ops_put(struct fib_rules_ops *ops)
	{
	if (ops)
	module_put(ops->owner);
	}

	static void flush_route_cache(struct fib_rules_ops *ops)
	{
	if (ops->flush_cache)
	ops->flush_cache(ops);
	}

	static int __fib_rules_register(struct fib_rules_ops *ops)
	{
	int err = -EEXIST;
	struct fib_rules_ops *o;
	struct net *net;

	net = ops->fro_net;

	if (ops->rule_size < sizeof(struct fib_rule))
	return -EINVAL;

	if (ops->match == NULL \|\| ops->configure == NULL \|\|
	ops->compare == NULL \|\| ops->fill == NULL \|\|
	ops->action == NULL)
	return -EINVAL;

	spin_lock(&net->rules_mod_lock);
	list_for_each_entry(o, &net->rules_ops, list)
	if (ops->family == o->family)
	goto errout;

	hold_net(net);
	list_add_tail_rcu(&ops->list, &net->rules_ops);
	err = 0;
	errout:
	spin_unlock(&net->rules_mod_lock);

	return err;
	}

	struct fib_rules_ops *
	fib_rules_register(const struct fib_rules_ops tmpl, struct net net)
	{
	struct fib_rules_ops *ops;
	int err;

	ops = kmemdup(tmpl, sizeof(*ops), GFP_KERNEL);
	if (ops == NULL)
	return ERR_PTR(-ENOMEM);

	INIT_LIST_HEAD(&ops->rules_list);
	ops->fro_net = net;

	err = __fib_rules_register(ops);
	if (err) {
	kfree(ops);
	ops = ERR_PTR(err);
	}

	return ops;
	}
	EXPORT_SYMBOL_GPL(fib_rules_register);

	static void fib_rules_cleanup_ops(struct fib_rules_ops *ops)
	{
	struct fib_rule rule, tmp;

	list_for_each_entry_safe(rule, tmp, &ops->rules_list, list) {
	list_del_rcu(&rule->list);
	fib_rule_put(rule);
	}
	}

	static void fib_rules_put_rcu(struct rcu_head *head)
	{
	struct fib_rules_ops *ops = container_of(head, struct fib_rules_ops, rcu);
	struct net *net = ops->fro_net;

	release_net(net);
	kfree(ops);
	}

	void fib_rules_unregister(struct fib_rules_ops *ops)
	{
	struct net *net = ops->fro_net;

	spin_lock(&net->rules_mod_lock);
	list_del_rcu(&ops->list);
	fib_rules_cleanup_ops(ops);
	spin_unlock(&net->rules_mod_lock);

	call_rcu(&ops->rcu, fib_rules_put_rcu);
	}
	EXPORT_SYMBOL_GPL(fib_rules_unregister);

	static int fib_rule_match(struct fib_rule rule, struct fib_rules_ops ops,
	struct flowi *fl, int flags)
	{
	int ret = 0;

	if (rule->iifindex && (rule->iifindex != fl->flowi_iif))
	goto out;

	if (rule->oifindex && (rule->oifindex != fl->flowi_oif))
	goto out;

	if ((rule->mark ^ fl->flowi_mark) & rule->mark_mask)
	goto out;

	ret = ops->match(rule, fl, flags);
	out:
	return (rule->flags & FIB_RULE_INVERT) ? !ret : ret;
	}

	int fib_rules_lookup(struct fib_rules_ops ops, struct flowi fl,
	int flags, struct fib_lookup_arg *arg)
	{
	struct fib_rule *rule;
	int err;

	rcu_read_lock();

	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
	jumped:
	if (!fib_rule_match(rule, ops, fl, flags))
	continue;

	if (rule->action == FR_ACT_GOTO) {
	struct fib_rule *target;

	target = rcu_dereference(rule->ctarget);
	if (target == NULL) {
	continue;
	} else {
	rule = target;
	goto jumped;
	}
	} else if (rule->action == FR_ACT_NOP)
	continue;
	else
	err = ops->action(rule, fl, flags, arg);

	if (err != -EAGAIN) {
	if ((arg->flags & FIB_LOOKUP_NOREF) \|\|
	likely(atomic_inc_not_zero(&rule->refcnt))) {
	arg->rule = rule;
	goto out;
	}
	break;
	}
	}

	err = -ESRCH;
	out:
	rcu_read_unlock();

	return err;
	}
	EXPORT_SYMBOL_GPL(fib_rules_lookup);

	static int validate_rulemsg(struct fib_rule_hdr frh, struct nlattr *tb,
	struct fib_rules_ops *ops)
	{
	int err = -EINVAL;

	if (frh->src_len)
	if (tb[FRA_SRC] == NULL \|\|
	frh->src_len > (ops->addr_size * 8) \|\|
	nla_len(tb[FRA_SRC]) != ops->addr_size)
	goto errout;

	if (frh->dst_len)
	if (tb[FRA_DST] == NULL \|\|
	frh->dst_len > (ops->addr_size * 8) \|\|
	nla_len(tb[FRA_DST]) != ops->addr_size)
	goto errout;

	err = 0;
	errout:
	return err;
	}

	static int fib_nl_newrule(struct sk_buff skb, struct nlmsghdr nlh, void *arg)
	{
	struct net *net = sock_net(skb->sk);
	struct fib_rule_hdr *frh = nlmsg_data(nlh);
	struct fib_rules_ops *ops = NULL;
	struct fib_rule rule, r, *last = NULL;
	struct nlattr *tb[FRA_MAX+1];
	int err = -EINVAL, unresolved = 0;

	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
	goto errout;

	ops = lookup_rules_ops(net, frh->family);
	if (ops == NULL) {
	err = -EAFNOSUPPORT;
	goto errout;
	}

	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
	if (err < 0)
	goto errout;

	err = validate_rulemsg(frh, tb, ops);
	if (err < 0)
	goto errout;

	rule = kzalloc(ops->rule_size, GFP_KERNEL);
	if (rule == NULL) {
	err = -ENOMEM;
	goto errout;
	}
	rule->fr_net = hold_net(net);

	if (tb[FRA_PRIORITY])
	rule->pref = nla_get_u32(tb[FRA_PRIORITY]);

	if (tb[FRA_IIFNAME]) {
	struct net_device *dev;

	rule->iifindex = -1;
	nla_strlcpy(rule->iifname, tb[FRA_IIFNAME], IFNAMSIZ);
	dev = __dev_get_by_name(net, rule->iifname);
	if (dev)
	rule->iifindex = dev->ifindex;
	}

	if (tb[FRA_OIFNAME]) {
	struct net_device *dev;

	rule->oifindex = -1;
	nla_strlcpy(rule->oifname, tb[FRA_OIFNAME], IFNAMSIZ);
	dev = __dev_get_by_name(net, rule->oifname);
	if (dev)
	rule->oifindex = dev->ifindex;
	}

	if (tb[FRA_FWMARK]) {
	rule->mark = nla_get_u32(tb[FRA_FWMARK]);
	if (rule->mark)
	/* compatibility: if the mark value is non-zero all bits
	* are compared unless a mask is explicitly specified.
	*/
	rule->mark_mask = 0xFFFFFFFF;
	}

	if (tb[FRA_FWMASK])
	rule->mark_mask = nla_get_u32(tb[FRA_FWMASK]);

	rule->action = frh->action;
	rule->flags = frh->flags;
	rule->table = frh_get_table(frh, tb);

	if (!tb[FRA_PRIORITY] && ops->default_pref)
	rule->pref = ops->default_pref(ops);

	err = -EINVAL;
	if (tb[FRA_GOTO]) {
	if (rule->action != FR_ACT_GOTO)
	goto errout_free;

	rule->target = nla_get_u32(tb[FRA_GOTO]);
	/* Backward jumps are prohibited to avoid endless loops */
	if (rule->target <= rule->pref)
	goto errout_free;

	list_for_each_entry(r, &ops->rules_list, list) {
	if (r->pref == rule->target) {
	RCU_INIT_POINTER(rule->ctarget, r);
	break;
	}
	}

	if (rcu_dereference_protected(rule->ctarget, 1) == NULL)
	unresolved = 1;
	} else if (rule->action == FR_ACT_GOTO)
	goto errout_free;

	err = ops->configure(rule, skb, frh, tb);
	if (err < 0)
	goto errout_free;

	list_for_each_entry(r, &ops->rules_list, list) {
	if (r->pref > rule->pref)
	break;
	last = r;
	}

	fib_rule_get(rule);

	if (last)
	list_add_rcu(&rule->list, &last->list);
	else
	list_add_rcu(&rule->list, &ops->rules_list);

	if (ops->unresolved_rules) {
	/*
	* There are unresolved goto rules in the list, check if
	* any of them are pointing to this new rule.
	*/
	list_for_each_entry(r, &ops->rules_list, list) {
	if (r->action == FR_ACT_GOTO &&
	r->target == rule->pref) {
	BUG_ON(rtnl_dereference(r->ctarget) != NULL);
	rcu_assign_pointer(r->ctarget, rule);
	if (--ops->unresolved_rules == 0)
	break;
	}
	}
	}

	if (rule->action == FR_ACT_GOTO)
	ops->nr_goto_rules++;

	if (unresolved)
	ops->unresolved_rules++;

	notify_rule_change(RTM_NEWRULE, rule, ops, nlh, NETLINK_CB(skb).pid);
	flush_route_cache(ops);
	rules_ops_put(ops);
	return 0;

	errout_free:
	release_net(rule->fr_net);
	kfree(rule);
	errout:
	rules_ops_put(ops);
	return err;
	}

	static int fib_nl_delrule(struct sk_buff skb, struct nlmsghdr nlh, void *arg)
	{
	struct net *net = sock_net(skb->sk);
	struct fib_rule_hdr *frh = nlmsg_data(nlh);
	struct fib_rules_ops *ops = NULL;
	struct fib_rule rule, tmp;
	struct nlattr *tb[FRA_MAX+1];
	int err = -EINVAL;

	if (nlh->nlmsg_len < nlmsg_msg_size(sizeof(*frh)))
	goto errout;

	ops = lookup_rules_ops(net, frh->family);
	if (ops == NULL) {
	err = -EAFNOSUPPORT;
	goto errout;
	}

	err = nlmsg_parse(nlh, sizeof(*frh), tb, FRA_MAX, ops->policy);
	if (err < 0)
	goto errout;

	err = validate_rulemsg(frh, tb, ops);
	if (err < 0)
	goto errout;

	list_for_each_entry(rule, &ops->rules_list, list) {
	if (frh->action && (frh->action != rule->action))
	continue;

	if (frh->table && (frh_get_table(frh, tb) != rule->table))
	continue;

	if (tb[FRA_PRIORITY] &&
	(rule->pref != nla_get_u32(tb[FRA_PRIORITY])))
	continue;

	if (tb[FRA_IIFNAME] &&
	nla_strcmp(tb[FRA_IIFNAME], rule->iifname))
	continue;

	if (tb[FRA_OIFNAME] &&
	nla_strcmp(tb[FRA_OIFNAME], rule->oifname))
	continue;

	if (tb[FRA_FWMARK] &&
	(rule->mark != nla_get_u32(tb[FRA_FWMARK])))
	continue;

	if (tb[FRA_FWMASK] &&
	(rule->mark_mask != nla_get_u32(tb[FRA_FWMASK])))
	continue;

	if (!ops->compare(rule, frh, tb))
	continue;

	if (rule->flags & FIB_RULE_PERMANENT) {
	err = -EPERM;
	goto errout;
	}

	list_del_rcu(&rule->list);

	if (rule->action == FR_ACT_GOTO)
	ops->nr_goto_rules--;

	/*
	* Check if this rule is a target to any of them. If so,
	* disable them. As this operation is eventually very
	* expensive, it is only performed if goto rules have
	* actually been added.
	*/
	if (ops->nr_goto_rules > 0) {
	list_for_each_entry(tmp, &ops->rules_list, list) {
	if (rtnl_dereference(tmp->ctarget) == rule) {
	rcu_assign_pointer(tmp->ctarget, NULL);
	ops->unresolved_rules++;
	}
	}
	}

	notify_rule_change(RTM_DELRULE, rule, ops, nlh,
	NETLINK_CB(skb).pid);
	fib_rule_put(rule);
	flush_route_cache(ops);
	rules_ops_put(ops);
	return 0;
	}

	err = -ENOENT;
	errout:
	rules_ops_put(ops);
	return err;
	}

	static inline size_t fib_rule_nlmsg_size(struct fib_rules_ops *ops,
	struct fib_rule *rule)
	{
	size_t payload = NLMSG_ALIGN(sizeof(struct fib_rule_hdr))
	+ nla_total_size(IFNAMSIZ) /* FRA_IIFNAME */
	+ nla_total_size(IFNAMSIZ) /* FRA_OIFNAME */
	+ nla_total_size(4) /* FRA_PRIORITY */
	+ nla_total_size(4) /* FRA_TABLE */
	+ nla_total_size(4) /* FRA_FWMARK */
	+ nla_total_size(4); /* FRA_FWMASK */

	if (ops->nlmsg_payload)
	payload += ops->nlmsg_payload(rule);

	return payload;
	}

	static int fib_nl_fill_rule(struct sk_buff skb, struct fib_rule rule,
	u32 pid, u32 seq, int type, int flags,
	struct fib_rules_ops *ops)
	{
	struct nlmsghdr *nlh;
	struct fib_rule_hdr *frh;

	nlh = nlmsg_put(skb, pid, seq, type, sizeof(*frh), flags);
	if (nlh == NULL)
	return -EMSGSIZE;

	frh = nlmsg_data(nlh);
	frh->family = ops->family;
	frh->table = rule->table;
	NLA_PUT_U32(skb, FRA_TABLE, rule->table);
	frh->res1 = 0;
	frh->res2 = 0;
	frh->action = rule->action;
	frh->flags = rule->flags;

	if (rule->action == FR_ACT_GOTO &&
	rcu_dereference_raw(rule->ctarget) == NULL)
	frh->flags \|= FIB_RULE_UNRESOLVED;

	if (rule->iifname[0]) {
	NLA_PUT_STRING(skb, FRA_IIFNAME, rule->iifname);

	if (rule->iifindex == -1)
	frh->flags \|= FIB_RULE_IIF_DETACHED;
	}

	if (rule->oifname[0]) {
	NLA_PUT_STRING(skb, FRA_OIFNAME, rule->oifname);

	if (rule->oifindex == -1)
	frh->flags \|= FIB_RULE_OIF_DETACHED;
	}

	if (rule->pref)
	NLA_PUT_U32(skb, FRA_PRIORITY, rule->pref);

	if (rule->mark)
	NLA_PUT_U32(skb, FRA_FWMARK, rule->mark);

	if (rule->mark_mask \|\| rule->mark)
	NLA_PUT_U32(skb, FRA_FWMASK, rule->mark_mask);

	if (rule->target)
	NLA_PUT_U32(skb, FRA_GOTO, rule->target);

	if (ops->fill(rule, skb, frh) < 0)
	goto nla_put_failure;

	return nlmsg_end(skb, nlh);

	nla_put_failure:
	nlmsg_cancel(skb, nlh);
	return -EMSGSIZE;
	}

	static int dump_rules(struct sk_buff skb, struct netlink_callback cb,
	struct fib_rules_ops *ops)
	{
	int idx = 0;
	struct fib_rule *rule;

	rcu_read_lock();
	list_for_each_entry_rcu(rule, &ops->rules_list, list) {
	if (idx < cb->args[1])
	goto skip;

	if (fib_nl_fill_rule(skb, rule, NETLINK_CB(cb->skb).pid,
	cb->nlh->nlmsg_seq, RTM_NEWRULE,
	NLM_F_MULTI, ops) < 0)
	break;
	skip:
	idx++;
	}
	cb->args[1] = idx;
	rules_ops_put(ops);

	return skb->len;
	}

	static int fib_nl_dumprule(struct sk_buff skb, struct netlink_callback cb)
	{
	struct net *net = sock_net(skb->sk);
	struct fib_rules_ops *ops;
	int idx = 0, family;

	family = rtnl_msg_family(cb->nlh);
	if (family != AF_UNSPEC) {
	/* Protocol specific dump request */
	ops = lookup_rules_ops(net, family);
	if (ops == NULL)
	return -EAFNOSUPPORT;

	return dump_rules(skb, cb, ops);
	}

	rcu_read_lock();
	list_for_each_entry_rcu(ops, &net->rules_ops, list) {
	if (idx < cb->args[0] \|\| !try_module_get(ops->owner))
	goto skip;

	if (dump_rules(skb, cb, ops) < 0)
	break;

	cb->args[1] = 0;
	skip:
	idx++;
	}
	rcu_read_unlock();
	cb->args[0] = idx;

	return skb->len;
	}

	static void notify_rule_change(int event, struct fib_rule *rule,
	struct fib_rules_ops ops, struct nlmsghdr nlh,
	u32 pid)
	{
	struct net *net;
	struct sk_buff *skb;
	int err = -ENOBUFS;

	net = ops->fro_net;
	skb = nlmsg_new(fib_rule_nlmsg_size(ops, rule), GFP_KERNEL);
	if (skb == NULL)
	goto errout;

	err = fib_nl_fill_rule(skb, rule, pid, nlh->nlmsg_seq, event, 0, ops);
	if (err < 0) {
	/* -EMSGSIZE implies BUG in fib_rule_nlmsg_size() */
	WARN_ON(err == -EMSGSIZE);
	kfree_skb(skb);
	goto errout;
	}

	rtnl_notify(skb, net, pid, ops->nlgroup, nlh, GFP_KERNEL);
	return;
	errout:
	if (err < 0)
	rtnl_set_sk_err(net, ops->nlgroup, err);
	}

	static void attach_rules(struct list_head rules, struct net_device dev)
	{
	struct fib_rule *rule;

	list_for_each_entry(rule, rules, list) {
	if (rule->iifindex == -1 &&
	strcmp(dev->name, rule->iifname) == 0)
	rule->iifindex = dev->ifindex;
	if (rule->oifindex == -1 &&
	strcmp(dev->name, rule->oifname) == 0)
	rule->oifindex = dev->ifindex;
	}
	}

	static void detach_rules(struct list_head rules, struct net_device dev)
	{
	struct fib_rule *rule;

	list_for_each_entry(rule, rules, list) {
	if (rule->iifindex == dev->ifindex)
	rule->iifindex = -1;
	if (rule->oifindex == dev->ifindex)
	rule->oifindex = -1;
	}
	}


	static int fib_rules_event(struct notifier_block *this, unsigned long event,
	void *ptr)
	{
	struct net_device *dev = ptr;
	struct net *net = dev_net(dev);
	struct fib_rules_ops *ops;

	ASSERT_RTNL();

	switch (event) {
	case NETDEV_REGISTER:
	list_for_each_entry(ops, &net->rules_ops, list)
	attach_rules(&ops->rules_list, dev);
	break;

	case NETDEV_UNREGISTER:
	list_for_each_entry(ops, &net->rules_ops, list)
	detach_rules(&ops->rules_list, dev);
	break;
	}

	return NOTIFY_DONE;
	}

	static struct notifier_block fib_rules_notifier = {
	.notifier_call = fib_rules_event,
	};

	static int __net_init fib_rules_net_init(struct net *net)
	{
	INIT_LIST_HEAD(&net->rules_ops);
	spin_lock_init(&net->rules_mod_lock);
	return 0;
	}

	static struct pernet_operations fib_rules_net_ops = {
	.init = fib_rules_net_init,
	};

	static int __init fib_rules_init(void)
	{
	int err;
	rtnl_register(PF_UNSPEC, RTM_NEWRULE, fib_nl_newrule, NULL);
	rtnl_register(PF_UNSPEC, RTM_DELRULE, fib_nl_delrule, NULL);
	rtnl_register(PF_UNSPEC, RTM_GETRULE, NULL, fib_nl_dumprule);

	err = register_pernet_subsys(&fib_rules_net_ops);
	if (err < 0)
	goto fail;

	err = register_netdevice_notifier(&fib_rules_notifier);
	if (err < 0)
	goto fail_unregister;

	return 0;

	fail_unregister:
	unregister_pernet_subsys(&fib_rules_net_ops);
	fail:
	rtnl_unregister(PF_UNSPEC, RTM_NEWRULE);
	rtnl_unregister(PF_UNSPEC, RTM_DELRULE);
	rtnl_unregister(PF_UNSPEC, RTM_GETRULE);
	return err;
	}

	subsys_initcall(fib_rules_init);