[mirror_ubuntu-bionic-kernel.git] / net / ipv6 / netfilter / ip6t_rpfilter.c

/*
 * Copyright (c) 2011 Florian Westphal <fw@strlen.de>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/skbuff.h>
#include <linux/netdevice.h>
#include <linux/route.h>
#include <net/ip6_fib.h>
#include <net/ip6_route.h>

#include <linux/netfilter/xt_rpfilter.h>
#include <linux/netfilter/x_tables.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
MODULE_DESCRIPTION("Xtables: IPv6 reverse path filter match");

static bool rpfilter_addr_unicast(const struct in6_addr *addr)
{
	int addr_type = ipv6_addr_type(addr);
	return addr_type & IPV6_ADDR_UNICAST;
}

static bool rpfilter_lookup_reverse6(struct net *net, const struct sk_buff *skb,
				     const struct net_device *dev, u8 flags)
{
	struct rt6_info *rt;
	struct ipv6hdr *iph = ipv6_hdr(skb);
	bool ret = false;
	struct flowi6 fl6 = {
		.flowi6_iif = LOOPBACK_IFINDEX,
		.flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK,
		.flowi6_proto = iph->nexthdr,
		.daddr = iph->saddr,
	};
	int lookup_flags;

	if (rpfilter_addr_unicast(&iph->daddr)) {
		memcpy(&fl6.saddr, &iph->daddr, sizeof(struct in6_addr));
		lookup_flags = RT6_LOOKUP_F_HAS_SADDR;
	} else {
		lookup_flags = 0;
	}

	fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
	if ((flags & XT_RPFILTER_LOOSE) == 0)
		fl6.flowi6_oif = dev->ifindex;

	rt = (void *) ip6_route_lookup(net, &fl6, lookup_flags);
	if (rt->dst.error)
		goto out;

	if (rt->rt6i_flags & (RTF_REJECT|RTF_ANYCAST))
		goto out;

	if (rt->rt6i_flags & RTF_LOCAL) {
		ret = flags & XT_RPFILTER_ACCEPT_LOCAL;
		goto out;
	}

	if (rt->rt6i_idev->dev == dev || (flags & XT_RPFILTER_LOOSE))
		ret = true;
 out:
	ip6_rt_put(rt);
	return ret;
}

static bool
rpfilter_is_loopback(const struct sk_buff *skb, const struct net_device *in)
{
	return skb->pkt_type == PACKET_LOOPBACK || in->flags & IFF_LOOPBACK;
}

static bool rpfilter_mt(const struct sk_buff *skb, struct xt_action_param *par)
{
	const struct xt_rpfilter_info *info = par->matchinfo;
	int saddrtype;
	struct ipv6hdr *iph;
	bool invert = info->flags & XT_RPFILTER_INVERT;

	if (rpfilter_is_loopback(skb, xt_in(par)))
		return true ^ invert;

	iph = ipv6_hdr(skb);
	saddrtype = ipv6_addr_type(&iph->saddr);
	if (unlikely(saddrtype == IPV6_ADDR_ANY))
		return true ^ invert; /* not routable: forward path will drop it */

	return rpfilter_lookup_reverse6(xt_net(par), skb, xt_in(par),
					info->flags) ^ invert;
}

static int rpfilter_check(const struct xt_mtchk_param *par)
{
	const struct xt_rpfilter_info *info = par->matchinfo;
	unsigned int options = ~XT_RPFILTER_OPTION_MASK;

	if (info->flags & options) {
		pr_info("unknown options encountered");
		return -EINVAL;
	}

	if (strcmp(par->table, "mangle") != 0 &&
	    strcmp(par->table, "raw") != 0) {
		pr_info("match only valid in the \'raw\' "
			"or \'mangle\' tables, not \'%s\'.\n", par->table);
		return -EINVAL;
	}

	return 0;
}

static struct xt_match rpfilter_mt_reg __read_mostly = {
	.name		= "rpfilter",
	.family		= NFPROTO_IPV6,
	.checkentry	= rpfilter_check,
	.match		= rpfilter_mt,
	.matchsize	= sizeof(struct xt_rpfilter_info),
	.hooks		= (1 << NF_INET_PRE_ROUTING),
	.me		= THIS_MODULE
};

static int __init rpfilter_mt_init(void)
{
	return xt_register_match(&rpfilter_mt_reg);
}

static void __exit rpfilter_mt_exit(void)
{
	xt_unregister_match(&rpfilter_mt_reg);
}

module_init(rpfilter_mt_init);
module_exit(rpfilter_mt_exit);
Commit	Line	Data
e26f9a48 FW	1	/*
	2	* Copyright (c) 2011 Florian Westphal <fw@strlen.de>
	3	*
	4	* This program is free software; you can redistribute it and/or modify
	5	* it under the terms of the GNU General Public License version 2 as
	6	* published by the Free Software Foundation.
	7	*/
	8	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
	9	#include <linux/module.h>
	10	#include <linux/skbuff.h>
	11	#include <linux/netdevice.h>
	12	#include <linux/route.h>
	13	#include <net/ip6_fib.h>
	14	#include <net/ip6_route.h>
	15
	16	#include <linux/netfilter/xt_rpfilter.h>
	17	#include <linux/netfilter/x_tables.h>
	18
	19	MODULE_LICENSE("GPL");
	20	MODULE_AUTHOR("Florian Westphal <fw@strlen.de>");
	21	MODULE_DESCRIPTION("Xtables: IPv6 reverse path filter match");
	22
	23	static bool rpfilter_addr_unicast(const struct in6_addr *addr)
	24	{
	25	int addr_type = ipv6_addr_type(addr);
	26	return addr_type & IPV6_ADDR_UNICAST;
	27	}
	28
686c9b50	29	static bool rpfilter_lookup_reverse6(struct net net, const struct sk_buff skb,
e26f9a48 FW	30	const struct net_device *dev, u8 flags)
	31	{
	32	struct rt6_info *rt;
	33	struct ipv6hdr *iph = ipv6_hdr(skb);
	34	bool ret = false;
	35	struct flowi6 fl6 = {
e374c618	36	.flowi6_iif = LOOPBACK_IFINDEX,
e26f9a48 FW	37	.flowlabel = (* (__be32 *) iph) & IPV6_FLOWINFO_MASK,
	38	.flowi6_proto = iph->nexthdr,
	39	.daddr = iph->saddr,
	40	};
	41	int lookup_flags;
	42
	43	if (rpfilter_addr_unicast(&iph->daddr)) {
	44	memcpy(&fl6.saddr, &iph->daddr, sizeof(struct in6_addr));
	45	lookup_flags = RT6_LOOKUP_F_HAS_SADDR;
	46	} else {
	47	lookup_flags = 0;
	48	}
	49
	50	fl6.flowi6_mark = flags & XT_RPFILTER_VALID_MARK ? skb->mark : 0;
a858bb28 VB	51	if ((flags & XT_RPFILTER_LOOSE) == 0)
a858bb28 VB	52	fl6.flowi6_oif = dev->ifindex;
e26f9a48	53
686c9b50	54	rt = (void *) ip6_route_lookup(net, &fl6, lookup_flags);
e26f9a48 FW	55	if (rt->dst.error)
	56	goto out;
	57
	58	if (rt->rt6i_flags & (RTF_REJECT\|RTF_ANYCAST))
	59	goto out;
	60
	61	if (rt->rt6i_flags & RTF_LOCAL) {
	62	ret = flags & XT_RPFILTER_ACCEPT_LOCAL;
	63	goto out;
	64	}
	65
	66	if (rt->rt6i_idev->dev == dev \|\| (flags & XT_RPFILTER_LOOSE))
	67	ret = true;
	68	out:
94e187c0	69	ip6_rt_put(rt);
e26f9a48 FW	70	return ret;
	71	}
	72
6443ebc3 LZ	73	static bool
6443ebc3 LZ	74	rpfilter_is_loopback(const struct sk_buff skb, const struct net_device in)
f83a7ea2	75	{
6443ebc3	76	return skb->pkt_type == PACKET_LOOPBACK \|\| in->flags & IFF_LOOPBACK;
f83a7ea2 FW	77	}
f83a7ea2 FW	78
e26f9a48 FW	79	static bool rpfilter_mt(const struct sk_buff skb, struct xt_action_param par)
	80	{
	81	const struct xt_rpfilter_info *info = par->matchinfo;
	82	int saddrtype;
	83	struct ipv6hdr *iph;
	84	bool invert = info->flags & XT_RPFILTER_INVERT;
	85
6443ebc3	86	if (rpfilter_is_loopback(skb, xt_in(par)))
e26f9a48 FW	87	return true ^ invert;
	88
	89	iph = ipv6_hdr(skb);
	90	saddrtype = ipv6_addr_type(&iph->saddr);
	91	if (unlikely(saddrtype == IPV6_ADDR_ANY))
	92	return true ^ invert; /* not routable: forward path will drop it */
	93
613dbd95 PNA	94	return rpfilter_lookup_reverse6(xt_net(par), skb, xt_in(par),
613dbd95 PNA	95	info->flags) ^ invert;
e26f9a48 FW	96	}
	97
	98	static int rpfilter_check(const struct xt_mtchk_param *par)
	99	{
	100	const struct xt_rpfilter_info *info = par->matchinfo;
	101	unsigned int options = ~XT_RPFILTER_OPTION_MASK;
	102
	103	if (info->flags & options) {
	104	pr_info("unknown options encountered");
	105	return -EINVAL;
	106	}
	107
	108	if (strcmp(par->table, "mangle") != 0 &&
	109	strcmp(par->table, "raw") != 0) {
	110	pr_info("match only valid in the \'raw\' "
	111	"or \'mangle\' tables, not \'%s\'.\n", par->table);
	112	return -EINVAL;
	113	}
	114
	115	return 0;
	116	}
	117
	118	static struct xt_match rpfilter_mt_reg __read_mostly = {
	119	.name = "rpfilter",
	120	.family = NFPROTO_IPV6,
	121	.checkentry = rpfilter_check,
	122	.match = rpfilter_mt,
	123	.matchsize = sizeof(struct xt_rpfilter_info),
	124	.hooks = (1 << NF_INET_PRE_ROUTING),
	125	.me = THIS_MODULE
	126	};
	127
	128	static int __init rpfilter_mt_init(void)
	129	{
	130	return xt_register_match(&rpfilter_mt_reg);
	131	}
	132
	133	static void __exit rpfilter_mt_exit(void)
	134	{
	135	xt_unregister_match(&rpfilter_mt_reg);
	136	}
	137
	138	module_init(rpfilter_mt_init);
	139	module_exit(rpfilter_mt_exit);