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v3.15
  1/*
  2 * IPv4 specific functions of netfilter core
  3 *
  4 * Rusty Russell (C) 2000 -- This code is GPL.
  5 * Patrick McHardy (C) 2006-2012
  6 */
  7#include <linux/kernel.h>
  8#include <linux/netfilter.h>
  9#include <linux/netfilter_ipv4.h>
 10#include <linux/ip.h>
 11#include <linux/skbuff.h>
 12#include <linux/gfp.h>
 13#include <linux/export.h>
 14#include <net/route.h>
 15#include <net/xfrm.h>
 16#include <net/ip.h>
 17#include <net/netfilter/nf_queue.h>
 18
 19/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
 20int ip_route_me_harder(struct sk_buff *skb, unsigned int addr_type)
 21{
 22	struct net *net = dev_net(skb_dst(skb)->dev);
 23	const struct iphdr *iph = ip_hdr(skb);
 24	struct rtable *rt;
 25	struct flowi4 fl4 = {};
 26	__be32 saddr = iph->saddr;
 27	__u8 flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
 
 
 28	unsigned int hh_len;
 29
 30	if (addr_type == RTN_UNSPEC)
 31		addr_type = inet_addr_type(net, saddr);
 32	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
 33		flags |= FLOWI_FLAG_ANYSRC;
 34	else
 35		saddr = 0;
 36
 37	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
 38	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
 39	 */
 40	fl4.daddr = iph->daddr;
 41	fl4.saddr = saddr;
 42	fl4.flowi4_tos = RT_TOS(iph->tos);
 43	fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
 
 
 44	fl4.flowi4_mark = skb->mark;
 45	fl4.flowi4_flags = flags;
 46	rt = ip_route_output_key(net, &fl4);
 47	if (IS_ERR(rt))
 48		return PTR_ERR(rt);
 49
 50	/* Drop old route. */
 51	skb_dst_drop(skb);
 52	skb_dst_set(skb, &rt->dst);
 53
 54	if (skb_dst(skb)->error)
 55		return skb_dst(skb)->error;
 56
 57#ifdef CONFIG_XFRM
 58	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
 59	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
 60		struct dst_entry *dst = skb_dst(skb);
 61		skb_dst_set(skb, NULL);
 62		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
 63		if (IS_ERR(dst))
 64			return PTR_ERR(dst);
 65		skb_dst_set(skb, dst);
 66	}
 67#endif
 68
 69	/* Change in oif may mean change in hh_len. */
 70	hh_len = skb_dst(skb)->dev->hard_header_len;
 71	if (skb_headroom(skb) < hh_len &&
 72	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
 73				0, GFP_ATOMIC))
 74		return -ENOMEM;
 75
 76	return 0;
 77}
 78EXPORT_SYMBOL(ip_route_me_harder);
 79
 80/*
 81 * Extra routing may needed on local out, as the QUEUE target never
 82 * returns control to the table.
 83 */
 84
 85struct ip_rt_info {
 86	__be32 daddr;
 87	__be32 saddr;
 88	u_int8_t tos;
 89	u_int32_t mark;
 90};
 91
 92static void nf_ip_saveroute(const struct sk_buff *skb,
 93			    struct nf_queue_entry *entry)
 94{
 95	struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
 96
 97	if (entry->hook == NF_INET_LOCAL_OUT) {
 98		const struct iphdr *iph = ip_hdr(skb);
 99
100		rt_info->tos = iph->tos;
101		rt_info->daddr = iph->daddr;
102		rt_info->saddr = iph->saddr;
103		rt_info->mark = skb->mark;
104	}
105}
106
107static int nf_ip_reroute(struct sk_buff *skb,
108			 const struct nf_queue_entry *entry)
109{
110	const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
111
112	if (entry->hook == NF_INET_LOCAL_OUT) {
113		const struct iphdr *iph = ip_hdr(skb);
114
115		if (!(iph->tos == rt_info->tos &&
116		      skb->mark == rt_info->mark &&
117		      iph->daddr == rt_info->daddr &&
118		      iph->saddr == rt_info->saddr))
119			return ip_route_me_harder(skb, RTN_UNSPEC);
 
120	}
121	return 0;
122}
 
123
124__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
125			    unsigned int dataoff, u_int8_t protocol)
126{
127	const struct iphdr *iph = ip_hdr(skb);
128	__sum16 csum = 0;
129
130	switch (skb->ip_summed) {
131	case CHECKSUM_COMPLETE:
132		if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
133			break;
134		if ((protocol == 0 && !csum_fold(skb->csum)) ||
135		    !csum_tcpudp_magic(iph->saddr, iph->daddr,
136				       skb->len - dataoff, protocol,
137				       skb->csum)) {
138			skb->ip_summed = CHECKSUM_UNNECESSARY;
139			break;
140		}
141		/* fall through */
142	case CHECKSUM_NONE:
143		if (protocol == 0)
144			skb->csum = 0;
145		else
146			skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
147						       skb->len - dataoff,
148						       protocol, 0);
149		csum = __skb_checksum_complete(skb);
150	}
151	return csum;
152}
153EXPORT_SYMBOL(nf_ip_checksum);
154
155static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
156				      unsigned int dataoff, unsigned int len,
157				      u_int8_t protocol)
158{
159	const struct iphdr *iph = ip_hdr(skb);
160	__sum16 csum = 0;
161
162	switch (skb->ip_summed) {
163	case CHECKSUM_COMPLETE:
164		if (len == skb->len - dataoff)
165			return nf_ip_checksum(skb, hook, dataoff, protocol);
166		/* fall through */
167	case CHECKSUM_NONE:
168		skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
169					       skb->len - dataoff, 0);
170		skb->ip_summed = CHECKSUM_NONE;
171		return __skb_checksum_complete_head(skb, dataoff + len);
172	}
173	return csum;
174}
 
175
176static int nf_ip_route(struct net *net, struct dst_entry **dst,
177		       struct flowi *fl, bool strict __always_unused)
178{
179	struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
180	if (IS_ERR(rt))
181		return PTR_ERR(rt);
182	*dst = &rt->dst;
183	return 0;
184}
185
186static const struct nf_afinfo nf_ip_afinfo = {
187	.family			= AF_INET,
188	.checksum		= nf_ip_checksum,
189	.checksum_partial	= nf_ip_checksum_partial,
190	.route			= nf_ip_route,
191	.saveroute		= nf_ip_saveroute,
192	.reroute		= nf_ip_reroute,
193	.route_key_size		= sizeof(struct ip_rt_info),
194};
195
196static int __init ipv4_netfilter_init(void)
197{
198	return nf_register_afinfo(&nf_ip_afinfo);
199}
200
201static void __exit ipv4_netfilter_fini(void)
202{
203	nf_unregister_afinfo(&nf_ip_afinfo);
204}
205
206module_init(ipv4_netfilter_init);
207module_exit(ipv4_netfilter_fini);
v4.17
  1/*
  2 * IPv4 specific functions of netfilter core
  3 *
  4 * Rusty Russell (C) 2000 -- This code is GPL.
  5 * Patrick McHardy (C) 2006-2012
  6 */
  7#include <linux/kernel.h>
  8#include <linux/netfilter.h>
  9#include <linux/netfilter_ipv4.h>
 10#include <linux/ip.h>
 11#include <linux/skbuff.h>
 12#include <linux/gfp.h>
 13#include <linux/export.h>
 14#include <net/route.h>
 15#include <net/xfrm.h>
 16#include <net/ip.h>
 17#include <net/netfilter/nf_queue.h>
 18
 19/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
 20int ip_route_me_harder(struct net *net, struct sk_buff *skb, unsigned int addr_type)
 21{
 
 22	const struct iphdr *iph = ip_hdr(skb);
 23	struct rtable *rt;
 24	struct flowi4 fl4 = {};
 25	__be32 saddr = iph->saddr;
 26	const struct sock *sk = skb_to_full_sk(skb);
 27	__u8 flags = sk ? inet_sk_flowi_flags(sk) : 0;
 28	struct net_device *dev = skb_dst(skb)->dev;
 29	unsigned int hh_len;
 30
 31	if (addr_type == RTN_UNSPEC)
 32		addr_type = inet_addr_type_dev_table(net, dev, saddr);
 33	if (addr_type == RTN_LOCAL || addr_type == RTN_UNICAST)
 34		flags |= FLOWI_FLAG_ANYSRC;
 35	else
 36		saddr = 0;
 37
 38	/* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
 39	 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
 40	 */
 41	fl4.daddr = iph->daddr;
 42	fl4.saddr = saddr;
 43	fl4.flowi4_tos = RT_TOS(iph->tos);
 44	fl4.flowi4_oif = sk ? sk->sk_bound_dev_if : 0;
 45	if (!fl4.flowi4_oif)
 46		fl4.flowi4_oif = l3mdev_master_ifindex(dev);
 47	fl4.flowi4_mark = skb->mark;
 48	fl4.flowi4_flags = flags;
 49	rt = ip_route_output_key(net, &fl4);
 50	if (IS_ERR(rt))
 51		return PTR_ERR(rt);
 52
 53	/* Drop old route. */
 54	skb_dst_drop(skb);
 55	skb_dst_set(skb, &rt->dst);
 56
 57	if (skb_dst(skb)->error)
 58		return skb_dst(skb)->error;
 59
 60#ifdef CONFIG_XFRM
 61	if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
 62	    xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
 63		struct dst_entry *dst = skb_dst(skb);
 64		skb_dst_set(skb, NULL);
 65		dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), sk, 0);
 66		if (IS_ERR(dst))
 67			return PTR_ERR(dst);
 68		skb_dst_set(skb, dst);
 69	}
 70#endif
 71
 72	/* Change in oif may mean change in hh_len. */
 73	hh_len = skb_dst(skb)->dev->hard_header_len;
 74	if (skb_headroom(skb) < hh_len &&
 75	    pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
 76				0, GFP_ATOMIC))
 77		return -ENOMEM;
 78
 79	return 0;
 80}
 81EXPORT_SYMBOL(ip_route_me_harder);
 82
 83int nf_ip_reroute(struct sk_buff *skb, const struct nf_queue_entry *entry)
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 84{
 85	const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
 86
 87	if (entry->state.hook == NF_INET_LOCAL_OUT) {
 88		const struct iphdr *iph = ip_hdr(skb);
 89
 90		if (!(iph->tos == rt_info->tos &&
 91		      skb->mark == rt_info->mark &&
 92		      iph->daddr == rt_info->daddr &&
 93		      iph->saddr == rt_info->saddr))
 94			return ip_route_me_harder(entry->state.net, skb,
 95						  RTN_UNSPEC);
 96	}
 97	return 0;
 98}
 99EXPORT_SYMBOL_GPL(nf_ip_reroute);
100
101__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
102			    unsigned int dataoff, u_int8_t protocol)
103{
104	const struct iphdr *iph = ip_hdr(skb);
105	__sum16 csum = 0;
106
107	switch (skb->ip_summed) {
108	case CHECKSUM_COMPLETE:
109		if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
110			break;
111		if ((protocol == 0 && !csum_fold(skb->csum)) ||
112		    !csum_tcpudp_magic(iph->saddr, iph->daddr,
113				       skb->len - dataoff, protocol,
114				       skb->csum)) {
115			skb->ip_summed = CHECKSUM_UNNECESSARY;
116			break;
117		}
118		/* fall through */
119	case CHECKSUM_NONE:
120		if (protocol == 0)
121			skb->csum = 0;
122		else
123			skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
124						       skb->len - dataoff,
125						       protocol, 0);
126		csum = __skb_checksum_complete(skb);
127	}
128	return csum;
129}
130EXPORT_SYMBOL(nf_ip_checksum);
131
132__sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
133			       unsigned int dataoff, unsigned int len,
134			       u_int8_t protocol)
135{
136	const struct iphdr *iph = ip_hdr(skb);
137	__sum16 csum = 0;
138
139	switch (skb->ip_summed) {
140	case CHECKSUM_COMPLETE:
141		if (len == skb->len - dataoff)
142			return nf_ip_checksum(skb, hook, dataoff, protocol);
143		/* fall through */
144	case CHECKSUM_NONE:
145		skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
146					       skb->len - dataoff, 0);
147		skb->ip_summed = CHECKSUM_NONE;
148		return __skb_checksum_complete_head(skb, dataoff + len);
149	}
150	return csum;
151}
152EXPORT_SYMBOL_GPL(nf_ip_checksum_partial);
153
154int nf_ip_route(struct net *net, struct dst_entry **dst, struct flowi *fl,
155		bool strict __always_unused)
156{
157	struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
158	if (IS_ERR(rt))
159		return PTR_ERR(rt);
160	*dst = &rt->dst;
161	return 0;
162}
163EXPORT_SYMBOL_GPL(nf_ip_route);