[net-next-2.6.git] / net / ipv4 / netfilter.c

/* IPv4 specific functions of netfilter core */
#include <linux/kernel.h>
#include <linux/netfilter.h>
#include <linux/netfilter_ipv4.h>
#include <linux/ip.h>
#include <net/route.h>
#include <net/xfrm.h>
#include <net/ip.h>

/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
int ip_route_me_harder(struct sk_buff **pskb)
{
	struct iphdr *iph = (*pskb)->nh.iph;
	struct rtable *rt;
	struct flowi fl = {};
	struct dst_entry *odst;
	unsigned int hh_len;

	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
	 * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
	 */
	if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
		fl.nl_u.ip4_u.daddr = iph->daddr;
		fl.nl_u.ip4_u.saddr = iph->saddr;
		fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
		fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
#ifdef CONFIG_IP_ROUTE_FWMARK
		fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
#endif
		if (ip_route_output_key(&rt, &fl) != 0)
			return -1;

		/* Drop old route. */
		dst_release((*pskb)->dst);
		(*pskb)->dst = &rt->u.dst;
	} else {
		/* non-local src, find valid iif to satisfy
		 * rp-filter when calling ip_route_input. */
		fl.nl_u.ip4_u.daddr = iph->saddr;
		if (ip_route_output_key(&rt, &fl) != 0)
			return -1;

		odst = (*pskb)->dst;
		if (ip_route_input(*pskb, iph->daddr, iph->saddr,
				   RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
			dst_release(&rt->u.dst);
			return -1;
		}
		dst_release(&rt->u.dst);
		dst_release(odst);
	}
	
	if ((*pskb)->dst->error)
		return -1;

#ifdef CONFIG_XFRM
	if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) &&
	    xfrm_decode_session(*pskb, &fl, AF_INET) == 0)
		if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0))
			return -1;
#endif

	/* Change in oif may mean change in hh_len. */
	hh_len = (*pskb)->dst->dev->hard_header_len;
	if (skb_headroom(*pskb) < hh_len) {
		struct sk_buff *nskb;

		nskb = skb_realloc_headroom(*pskb, hh_len);
		if (!nskb) 
			return -1;
		if ((*pskb)->sk)
			skb_set_owner_w(nskb, (*pskb)->sk);
		kfree_skb(*pskb);
		*pskb = nskb;
	}

	return 0;
}
EXPORT_SYMBOL(ip_route_me_harder);

#ifdef CONFIG_XFRM
int ip_xfrm_me_harder(struct sk_buff **pskb)
{
	struct flowi fl;
	unsigned int hh_len;
	struct dst_entry *dst;

	if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
		return 0;
	if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
		return -1;

	dst = (*pskb)->dst;
	if (dst->xfrm)
		dst = ((struct xfrm_dst *)dst)->route;
	dst_hold(dst);

	if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
		return -1;

	dst_release((*pskb)->dst);
	(*pskb)->dst = dst;

	/* Change in oif may mean change in hh_len. */
	hh_len = (*pskb)->dst->dev->hard_header_len;
	if (skb_headroom(*pskb) < hh_len) {
		struct sk_buff *nskb;

		nskb = skb_realloc_headroom(*pskb, hh_len);
		if (!nskb)
			return -1;
		if ((*pskb)->sk)
			skb_set_owner_w(nskb, (*pskb)->sk);
		kfree_skb(*pskb);
		*pskb = nskb;
	}
	return 0;
}
EXPORT_SYMBOL(ip_xfrm_me_harder);
#endif

void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
EXPORT_SYMBOL(ip_nat_decode_session);

/*
 * Extra routing may needed on local out, as the QUEUE target never
 * returns control to the table.
 */

struct ip_rt_info {
	u_int32_t daddr;
	u_int32_t saddr;
	u_int8_t tos;
};

static void queue_save(const struct sk_buff *skb, struct nf_info *info)
{
	struct ip_rt_info *rt_info = nf_info_reroute(info);

	if (info->hook == NF_IP_LOCAL_OUT) {
		const struct iphdr *iph = skb->nh.iph;

		rt_info->tos = iph->tos;
		rt_info->daddr = iph->daddr;
		rt_info->saddr = iph->saddr;
	}
}

static int queue_reroute(struct sk_buff **pskb, const struct nf_info *info)
{
	const struct ip_rt_info *rt_info = nf_info_reroute(info);

	if (info->hook == NF_IP_LOCAL_OUT) {
		struct iphdr *iph = (*pskb)->nh.iph;

		if (!(iph->tos == rt_info->tos
		      && iph->daddr == rt_info->daddr
		      && iph->saddr == rt_info->saddr))
			return ip_route_me_harder(pskb);
	}
	return 0;
}

static struct nf_queue_rerouter ip_reroute = {
	.rer_size	= sizeof(struct ip_rt_info),
	.save		= queue_save,
	.reroute	= queue_reroute,
};

static int ipv4_netfilter_init(void)
{
	return nf_register_queue_rerouter(PF_INET, &ip_reroute);
}

static void ipv4_netfilter_fini(void)
{
	nf_unregister_queue_rerouter(PF_INET);
}

module_init(ipv4_netfilter_init);
module_exit(ipv4_netfilter_fini);
Commit	Line	Data
2cc7d573	1	/* IPv4 specific functions of netfilter core */
020b4c12 HW	2	#include <linux/kernel.h>
020b4c12 HW	3	#include <linux/netfilter.h>
2cc7d573	4	#include <linux/netfilter_ipv4.h>
3e3850e9	5	#include <linux/ip.h>
020b4c12	6	#include <net/route.h>
3e3850e9 PM	7	#include <net/xfrm.h>
3e3850e9 PM	8	#include <net/ip.h>
020b4c12 HW	9
	10	/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
	11	int ip_route_me_harder(struct sk_buff **pskb)
	12	{
	13	struct iphdr iph = (pskb)->nh.iph;
	14	struct rtable *rt;
	15	struct flowi fl = {};
	16	struct dst_entry *odst;
	17	unsigned int hh_len;
	18
	19	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
	20	* packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
	21	*/
	22	if (inet_addr_type(iph->saddr) == RTN_LOCAL) {
	23	fl.nl_u.ip4_u.daddr = iph->daddr;
	24	fl.nl_u.ip4_u.saddr = iph->saddr;
	25	fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
	26	fl.oif = (pskb)->sk ? (pskb)->sk->sk_bound_dev_if : 0;
	27	#ifdef CONFIG_IP_ROUTE_FWMARK
	28	fl.nl_u.ip4_u.fwmark = (*pskb)->nfmark;
	29	#endif
020b4c12 HW	30	if (ip_route_output_key(&rt, &fl) != 0)
	31	return -1;
	32
	33	/* Drop old route. */
	34	dst_release((*pskb)->dst);
	35	(*pskb)->dst = &rt->u.dst;
	36	} else {
	37	/* non-local src, find valid iif to satisfy
	38	* rp-filter when calling ip_route_input. */
	39	fl.nl_u.ip4_u.daddr = iph->saddr;
	40	if (ip_route_output_key(&rt, &fl) != 0)
	41	return -1;
	42
	43	odst = (*pskb)->dst;
	44	if (ip_route_input(*pskb, iph->daddr, iph->saddr,
	45	RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
	46	dst_release(&rt->u.dst);
	47	return -1;
	48	}
	49	dst_release(&rt->u.dst);
	50	dst_release(odst);
	51	}
	52
	53	if ((*pskb)->dst->error)
	54	return -1;
	55
3e3850e9 PM	56	#ifdef CONFIG_XFRM
	57	if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) &&
	58	xfrm_decode_session(*pskb, &fl, AF_INET) == 0)
	59	if (xfrm_lookup(&(pskb)->dst, &fl, (pskb)->sk, 0))
	60	return -1;
	61	#endif
	62
020b4c12 HW	63	/* Change in oif may mean change in hh_len. */
	64	hh_len = (*pskb)->dst->dev->hard_header_len;
	65	if (skb_headroom(*pskb) < hh_len) {
	66	struct sk_buff *nskb;
	67
	68	nskb = skb_realloc_headroom(*pskb, hh_len);
	69	if (!nskb)
	70	return -1;
	71	if ((*pskb)->sk)
	72	skb_set_owner_w(nskb, (*pskb)->sk);
	73	kfree_skb(*pskb);
	74	*pskb = nskb;
	75	}
	76
	77	return 0;
	78	}
	79	EXPORT_SYMBOL(ip_route_me_harder);
2cc7d573	80
ee68cea2 PM	81	#ifdef CONFIG_XFRM
	82	int ip_xfrm_me_harder(struct sk_buff **pskb)
	83	{
	84	struct flowi fl;
	85	unsigned int hh_len;
	86	struct dst_entry *dst;
	87
	88	if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
	89	return 0;
	90	if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
	91	return -1;
	92
	93	dst = (*pskb)->dst;
	94	if (dst->xfrm)
	95	dst = ((struct xfrm_dst *)dst)->route;
	96	dst_hold(dst);
	97
	98	if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
	99	return -1;
	100
	101	dst_release((*pskb)->dst);
	102	(*pskb)->dst = dst;
	103
	104	/* Change in oif may mean change in hh_len. */
	105	hh_len = (*pskb)->dst->dev->hard_header_len;
	106	if (skb_headroom(*pskb) < hh_len) {
	107	struct sk_buff *nskb;
	108
	109	nskb = skb_realloc_headroom(*pskb, hh_len);
	110	if (!nskb)
	111	return -1;
	112	if ((*pskb)->sk)
	113	skb_set_owner_w(nskb, (*pskb)->sk);
	114	kfree_skb(*pskb);
	115	*pskb = nskb;
	116	}
	117	return 0;
	118	}
	119	EXPORT_SYMBOL(ip_xfrm_me_harder);
	120	#endif
	121
eb9c7ebe PM	122	void (ip_nat_decode_session)(struct sk_buff , struct flowi *);
	123	EXPORT_SYMBOL(ip_nat_decode_session);
	124
2cc7d573 HW	125	/*
	126	* Extra routing may needed on local out, as the QUEUE target never
	127	* returns control to the table.
	128	*/
	129
	130	struct ip_rt_info {
	131	u_int32_t daddr;
	132	u_int32_t saddr;
	133	u_int8_t tos;
	134	};
	135
	136	static void queue_save(const struct sk_buff skb, struct nf_info info)
	137	{
	138	struct ip_rt_info *rt_info = nf_info_reroute(info);
	139
	140	if (info->hook == NF_IP_LOCAL_OUT) {
	141	const struct iphdr *iph = skb->nh.iph;
	142
	143	rt_info->tos = iph->tos;
	144	rt_info->daddr = iph->daddr;
	145	rt_info->saddr = iph->saddr;
	146	}
	147	}
	148
	149	static int queue_reroute(struct sk_buff *pskb, const struct nf_info info)
	150	{
	151	const struct ip_rt_info *rt_info = nf_info_reroute(info);
	152
	153	if (info->hook == NF_IP_LOCAL_OUT) {
	154	struct iphdr iph = (pskb)->nh.iph;
	155
	156	if (!(iph->tos == rt_info->tos
	157	&& iph->daddr == rt_info->daddr
	158	&& iph->saddr == rt_info->saddr))
	159	return ip_route_me_harder(pskb);
	160	}
	161	return 0;
	162	}
	163
	164	static struct nf_queue_rerouter ip_reroute = {
	165	.rer_size = sizeof(struct ip_rt_info),
	166	.save = queue_save,
	167	.reroute = queue_reroute,
	168	};
	169
65b4b4e8	170	static int ipv4_netfilter_init(void)
2cc7d573 HW	171	{
	172	return nf_register_queue_rerouter(PF_INET, &ip_reroute);
	173	}
	174
65b4b4e8	175	static void ipv4_netfilter_fini(void)
2cc7d573 HW	176	{
	177	nf_unregister_queue_rerouter(PF_INET);
	178	}
	179
65b4b4e8 AM	180	module_init(ipv4_netfilter_init);
65b4b4e8 AM	181	module_exit(ipv4_netfilter_fini);