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Harald Welte2cc7d572005-08-09 19:42:34 -07001/* IPv4 specific functions of netfilter core */
Harald Welte020b4c12005-08-09 19:39:00 -07002#include <linux/kernel.h>
3#include <linux/netfilter.h>
Harald Welte2cc7d572005-08-09 19:42:34 -07004#include <linux/netfilter_ipv4.h>
Patrick McHardy3e3850e2006-01-06 23:04:54 -08005#include <linux/ip.h>
Harald Welte020b4c12005-08-09 19:39:00 -07006#include <net/route.h>
Patrick McHardy3e3850e2006-01-06 23:04:54 -08007#include <net/xfrm.h>
8#include <net/ip.h>
Harald Welte020b4c12005-08-09 19:39:00 -07009
10/* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
Simon Hormanb4c4ed12006-10-02 16:11:13 -070011int ip_route_me_harder(struct sk_buff **pskb, unsigned addr_type)
Harald Welte020b4c12005-08-09 19:39:00 -070012{
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;
Patrick McHardyc68b8b62007-01-04 12:15:34 -080018 unsigned int type;
Harald Welte020b4c12005-08-09 19:39:00 -070019
Patrick McHardyc68b8b62007-01-04 12:15:34 -080020 type = inet_addr_type(iph->saddr);
Simon Hormanb4c4ed12006-10-02 16:11:13 -070021 if (addr_type == RTN_UNSPEC)
Patrick McHardyc68b8b62007-01-04 12:15:34 -080022 addr_type = type;
Simon Hormanb4c4ed12006-10-02 16:11:13 -070023
Harald Welte020b4c12005-08-09 19:39:00 -070024 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
25 * packets with foreign saddr to appear on the NF_IP_LOCAL_OUT hook.
26 */
Simon Hormanb4c4ed12006-10-02 16:11:13 -070027 if (addr_type == RTN_LOCAL) {
Harald Welte020b4c12005-08-09 19:39:00 -070028 fl.nl_u.ip4_u.daddr = iph->daddr;
Patrick McHardyc68b8b62007-01-04 12:15:34 -080029 if (type == RTN_LOCAL)
30 fl.nl_u.ip4_u.saddr = iph->saddr;
Harald Welte020b4c12005-08-09 19:39:00 -070031 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
32 fl.oif = (*pskb)->sk ? (*pskb)->sk->sk_bound_dev_if : 0;
Thomas Graf47dcf0c2006-11-09 15:20:38 -080033 fl.mark = (*pskb)->mark;
Harald Welte020b4c12005-08-09 19:39:00 -070034 if (ip_route_output_key(&rt, &fl) != 0)
35 return -1;
36
37 /* Drop old route. */
38 dst_release((*pskb)->dst);
39 (*pskb)->dst = &rt->u.dst;
40 } else {
41 /* non-local src, find valid iif to satisfy
42 * rp-filter when calling ip_route_input. */
43 fl.nl_u.ip4_u.daddr = iph->saddr;
44 if (ip_route_output_key(&rt, &fl) != 0)
45 return -1;
46
47 odst = (*pskb)->dst;
48 if (ip_route_input(*pskb, iph->daddr, iph->saddr,
49 RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
50 dst_release(&rt->u.dst);
51 return -1;
52 }
53 dst_release(&rt->u.dst);
54 dst_release(odst);
55 }
56
57 if ((*pskb)->dst->error)
58 return -1;
59
Patrick McHardy3e3850e2006-01-06 23:04:54 -080060#ifdef CONFIG_XFRM
61 if (!(IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED) &&
62 xfrm_decode_session(*pskb, &fl, AF_INET) == 0)
63 if (xfrm_lookup(&(*pskb)->dst, &fl, (*pskb)->sk, 0))
64 return -1;
65#endif
66
Harald Welte020b4c12005-08-09 19:39:00 -070067 /* Change in oif may mean change in hh_len. */
68 hh_len = (*pskb)->dst->dev->hard_header_len;
69 if (skb_headroom(*pskb) < hh_len) {
70 struct sk_buff *nskb;
71
72 nskb = skb_realloc_headroom(*pskb, hh_len);
73 if (!nskb)
74 return -1;
75 if ((*pskb)->sk)
76 skb_set_owner_w(nskb, (*pskb)->sk);
77 kfree_skb(*pskb);
78 *pskb = nskb;
79 }
80
81 return 0;
82}
83EXPORT_SYMBOL(ip_route_me_harder);
Harald Welte2cc7d572005-08-09 19:42:34 -070084
Patrick McHardyee68cea2006-02-15 01:34:23 -080085#ifdef CONFIG_XFRM
86int ip_xfrm_me_harder(struct sk_buff **pskb)
87{
88 struct flowi fl;
89 unsigned int hh_len;
90 struct dst_entry *dst;
91
92 if (IPCB(*pskb)->flags & IPSKB_XFRM_TRANSFORMED)
93 return 0;
94 if (xfrm_decode_session(*pskb, &fl, AF_INET) < 0)
95 return -1;
96
97 dst = (*pskb)->dst;
98 if (dst->xfrm)
99 dst = ((struct xfrm_dst *)dst)->route;
100 dst_hold(dst);
101
102 if (xfrm_lookup(&dst, &fl, (*pskb)->sk, 0) < 0)
103 return -1;
104
105 dst_release((*pskb)->dst);
106 (*pskb)->dst = dst;
107
108 /* Change in oif may mean change in hh_len. */
109 hh_len = (*pskb)->dst->dev->hard_header_len;
110 if (skb_headroom(*pskb) < hh_len) {
111 struct sk_buff *nskb;
112
113 nskb = skb_realloc_headroom(*pskb, hh_len);
114 if (!nskb)
115 return -1;
116 if ((*pskb)->sk)
117 skb_set_owner_w(nskb, (*pskb)->sk);
118 kfree_skb(*pskb);
119 *pskb = nskb;
120 }
121 return 0;
122}
123EXPORT_SYMBOL(ip_xfrm_me_harder);
124#endif
125
Patrick McHardyeb9c7eb2006-01-06 23:06:30 -0800126void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
127EXPORT_SYMBOL(ip_nat_decode_session);
128
Harald Welte2cc7d572005-08-09 19:42:34 -0700129/*
130 * Extra routing may needed on local out, as the QUEUE target never
131 * returns control to the table.
132 */
133
134struct ip_rt_info {
Al Viro59b8bfd2006-09-28 14:21:07 -0700135 __be32 daddr;
136 __be32 saddr;
Harald Welte2cc7d572005-08-09 19:42:34 -0700137 u_int8_t tos;
138};
139
Patrick McHardybce80322006-04-06 14:18:09 -0700140static void nf_ip_saveroute(const struct sk_buff *skb, struct nf_info *info)
Harald Welte2cc7d572005-08-09 19:42:34 -0700141{
142 struct ip_rt_info *rt_info = nf_info_reroute(info);
143
144 if (info->hook == NF_IP_LOCAL_OUT) {
145 const struct iphdr *iph = skb->nh.iph;
146
147 rt_info->tos = iph->tos;
148 rt_info->daddr = iph->daddr;
149 rt_info->saddr = iph->saddr;
150 }
151}
152
Patrick McHardybce80322006-04-06 14:18:09 -0700153static int nf_ip_reroute(struct sk_buff **pskb, const struct nf_info *info)
Harald Welte2cc7d572005-08-09 19:42:34 -0700154{
155 const struct ip_rt_info *rt_info = nf_info_reroute(info);
156
157 if (info->hook == NF_IP_LOCAL_OUT) {
158 struct iphdr *iph = (*pskb)->nh.iph;
159
160 if (!(iph->tos == rt_info->tos
161 && iph->daddr == rt_info->daddr
162 && iph->saddr == rt_info->saddr))
Simon Hormanb4c4ed12006-10-02 16:11:13 -0700163 return ip_route_me_harder(pskb, RTN_UNSPEC);
Harald Welte2cc7d572005-08-09 19:42:34 -0700164 }
165 return 0;
166}
167
Al Virob51655b2006-11-14 21:40:42 -0800168__sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
Patrick McHardy422c3462006-04-06 14:18:43 -0700169 unsigned int dataoff, u_int8_t protocol)
170{
171 struct iphdr *iph = skb->nh.iph;
Al Virob51655b2006-11-14 21:40:42 -0800172 __sum16 csum = 0;
Patrick McHardy422c3462006-04-06 14:18:43 -0700173
174 switch (skb->ip_summed) {
Patrick McHardy84fa7932006-08-29 16:44:56 -0700175 case CHECKSUM_COMPLETE:
Patrick McHardy422c3462006-04-06 14:18:43 -0700176 if (hook != NF_IP_PRE_ROUTING && hook != NF_IP_LOCAL_IN)
177 break;
Al Virod3bc23e2006-11-14 21:24:49 -0800178 if ((protocol == 0 && !csum_fold(skb->csum)) ||
Patrick McHardy422c3462006-04-06 14:18:43 -0700179 !csum_tcpudp_magic(iph->saddr, iph->daddr,
180 skb->len - dataoff, protocol,
181 skb->csum)) {
182 skb->ip_summed = CHECKSUM_UNNECESSARY;
183 break;
184 }
185 /* fall through */
186 case CHECKSUM_NONE:
187 if (protocol == 0)
188 skb->csum = 0;
189 else
190 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
191 skb->len - dataoff,
192 protocol, 0);
193 csum = __skb_checksum_complete(skb);
194 }
195 return csum;
196}
197
198EXPORT_SYMBOL(nf_ip_checksum);
199
Patrick McHardybce80322006-04-06 14:18:09 -0700200static struct nf_afinfo nf_ip_afinfo = {
201 .family = AF_INET,
Patrick McHardy422c3462006-04-06 14:18:43 -0700202 .checksum = nf_ip_checksum,
Patrick McHardybce80322006-04-06 14:18:09 -0700203 .saveroute = nf_ip_saveroute,
204 .reroute = nf_ip_reroute,
205 .route_key_size = sizeof(struct ip_rt_info),
Harald Welte2cc7d572005-08-09 19:42:34 -0700206};
207
Andrew Morton65b4b4e2006-03-28 16:37:06 -0800208static int ipv4_netfilter_init(void)
Harald Welte2cc7d572005-08-09 19:42:34 -0700209{
Patrick McHardybce80322006-04-06 14:18:09 -0700210 return nf_register_afinfo(&nf_ip_afinfo);
Harald Welte2cc7d572005-08-09 19:42:34 -0700211}
212
Andrew Morton65b4b4e2006-03-28 16:37:06 -0800213static void ipv4_netfilter_fini(void)
Harald Welte2cc7d572005-08-09 19:42:34 -0700214{
Patrick McHardybce80322006-04-06 14:18:09 -0700215 nf_unregister_afinfo(&nf_ip_afinfo);
Harald Welte2cc7d572005-08-09 19:42:34 -0700216}
217
Andrew Morton65b4b4e2006-03-28 16:37:06 -0800218module_init(ipv4_netfilter_init);
219module_exit(ipv4_netfilter_fini);