net/ipv4/fib_rules.c - maze/linux - Git at Google

 /*
  * 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
 };

 #ifdef CONFIG_IP_ROUTE_CLASSID
 u32 fib_rules_tclass(const struct fib_result *res)
 {
 	return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
 }
 #endif

 int fib_lookup(struct net *net, struct flowi4 *flp, struct fib_result *res)
 {
 	struct fib_lookup_arg arg = {
 		.result = res,
 		.flags = FIB_LOOKUP_NOREF,
 	};
 	int err;

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

 	return err;
 }

 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;

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

 	case FR_ACT_UNREACHABLE:
 		err = -ENETUNREACH;
 		goto errout;

 	case FR_ACT_PROHIBIT:
 		err = -EACCES;
 		goto errout;

 	case FR_ACT_BLACKHOLE:
 	default:
 		err = -EINVAL;
 		goto errout;
 	}

 	tbl = fib_get_table(rule->fr_net, rule->table);
 	if (!tbl)
 		goto errout;

 	err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
 	if (err > 0)
 		err = -EAGAIN;
 errout:
 	return err;
 }


 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) == NULL)
 			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;

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

 			table = fib_empty_table(net);
 			if (table == NULL) {
 				err = -ENOBUFS;
 				goto errout;
 			}

 			rule->table = table->tb_id;
 		}
 	}

 	if (frh->src_len)
 		rule4->src = nla_get_be32(tb[FRA_SRC]);

 	if (frh->dst_len)
 		rule4->dst = nla_get_be32(tb[FRA_DST]);

 #ifdef CONFIG_IP_ROUTE_CLASSID
 	if (tb[FRA_FLOW])
 		rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
 #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;

 	err = 0;
 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_be32(tb[FRA_SRC])))
 		return 0;

 	if (frh->dst_len && (rule4->dst != nla_get_be32(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_BE32(skb, FRA_DST, rule4->dst);

 	if (rule4->src_len)
 		NLA_PUT_BE32(skb, FRA_SRC, rule4->src);

 #ifdef CONFIG_IP_ROUTE_CLASSID
 	if (rule4->tclassid)
 		NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
 #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, -1);
 }

 static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
 	.family		= AF_INET,
 	.rule_size	= sizeof(struct fib4_rule),
 	.addr_size	= sizeof(u32),
 	.action		= fib4_rule_action,
 	.match		= fib4_rule_match,
 	.configure	= fib4_rule_configure,
 	.compare	= fib4_rule_compare,
 	.fill		= fib4_rule_fill,
 	.default_pref	= fib_default_rule_pref,
 	.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;
 	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);
 }
	/*
	* 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
	};

	#ifdef CONFIG_IP_ROUTE_CLASSID
	u32 fib_rules_tclass(const struct fib_result *res)
	{
	return res->r ? ((struct fib4_rule *) res->r)->tclassid : 0;
	}
	#endif

	int fib_lookup(struct net net, struct flowi4 flp, struct fib_result *res)
	{
	struct fib_lookup_arg arg = {
	.result = res,
	.flags = FIB_LOOKUP_NOREF,
	};
	int err;

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

	return err;
	}

	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;

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

	case FR_ACT_UNREACHABLE:
	err = -ENETUNREACH;
	goto errout;

	case FR_ACT_PROHIBIT:
	err = -EACCES;
	goto errout;

	case FR_ACT_BLACKHOLE:
	default:
	err = -EINVAL;
	goto errout;
	}

	tbl = fib_get_table(rule->fr_net, rule->table);
	if (!tbl)
	goto errout;

	err = fib_table_lookup(tbl, &flp->u.ip4, (struct fib_result *) arg->result, arg->flags);
	if (err > 0)
	err = -EAGAIN;
	errout:
	return err;
	}


	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) == NULL)
	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;

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

	table = fib_empty_table(net);
	if (table == NULL) {
	err = -ENOBUFS;
	goto errout;
	}

	rule->table = table->tb_id;
	}
	}

	if (frh->src_len)
	rule4->src = nla_get_be32(tb[FRA_SRC]);

	if (frh->dst_len)
	rule4->dst = nla_get_be32(tb[FRA_DST]);

	#ifdef CONFIG_IP_ROUTE_CLASSID
	if (tb[FRA_FLOW])
	rule4->tclassid = nla_get_u32(tb[FRA_FLOW]);
	#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;

	err = 0;
	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_be32(tb[FRA_SRC])))
	return 0;

	if (frh->dst_len && (rule4->dst != nla_get_be32(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_BE32(skb, FRA_DST, rule4->dst);

	if (rule4->src_len)
	NLA_PUT_BE32(skb, FRA_SRC, rule4->src);

	#ifdef CONFIG_IP_ROUTE_CLASSID
	if (rule4->tclassid)
	NLA_PUT_U32(skb, FRA_FLOW, rule4->tclassid);
	#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, -1);
	}

	static const struct fib_rules_ops __net_initdata fib4_rules_ops_template = {
	.family = AF_INET,
	.rule_size = sizeof(struct fib4_rule),
	.addr_size = sizeof(u32),
	.action = fib4_rule_action,
	.match = fib4_rule_match,
	.configure = fib4_rule_configure,
	.compare = fib4_rule_compare,
	.fill = fib4_rule_fill,
	.default_pref = fib_default_rule_pref,
	.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;
	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);
	}