1 /* IPv4 specific functions of netfilter core */
2 #include <linux/kernel.h>
3 #include <linux/netfilter.h>
4 #include <linux/netfilter_ipv4.h>
6 #include <linux/skbuff.h>
10 #include <net/netfilter/nf_queue.h>
12 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
13 int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
15 const struct iphdr *iph = ip_hdr(skb);
18 struct dst_entry *odst;
22 type = inet_addr_type(&init_net, iph->saddr);
23 if (skb->sk && inet_sk(skb->sk)->transparent)
25 if (addr_type == RTN_UNSPEC)
28 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
29 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
31 if (addr_type == RTN_LOCAL) {
32 fl.nl_u.ip4_u.daddr = iph->daddr;
33 if (type == RTN_LOCAL)
34 fl.nl_u.ip4_u.saddr = iph->saddr;
35 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
36 fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
38 fl.flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
39 if (ip_route_output_key(&init_net, &rt, &fl) != 0)
43 dst_release(skb->dst);
44 skb->dst = &rt->u.dst;
46 /* non-local src, find valid iif to satisfy
47 * rp-filter when calling ip_route_input. */
48 fl.nl_u.ip4_u.daddr = iph->saddr;
49 if (ip_route_output_key(&init_net, &rt, &fl) != 0)
53 if (ip_route_input(skb, iph->daddr, iph->saddr,
54 RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
55 dst_release(&rt->u.dst);
58 dst_release(&rt->u.dst);
66 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
67 xfrm_decode_session(skb, &fl, AF_INET) == 0)
68 if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
72 /* Change in oif may mean change in hh_len. */
73 hh_len = skb->dst->dev->hard_header_len;
74 if (skb_headroom(skb) < hh_len &&
75 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
80 EXPORT_SYMBOL(ip_route_me_harder);
83 int ip_xfrm_me_harder(struct sk_buff *skb)
87 struct dst_entry *dst;
89 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
91 if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
96 dst = ((struct xfrm_dst *)dst)->route;
99 if (xfrm_lookup(&dst, &fl, skb->sk, 0) < 0)
102 dst_release(skb->dst);
105 /* Change in oif may mean change in hh_len. */
106 hh_len = skb->dst->dev->hard_header_len;
107 if (skb_headroom(skb) < hh_len &&
108 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
112 EXPORT_SYMBOL(ip_xfrm_me_harder);
115 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
116 EXPORT_SYMBOL(ip_nat_decode_session);
119 * Extra routing may needed on local out, as the QUEUE target never
120 * returns control to the table.
129 static void nf_ip_saveroute(const struct sk_buff *skb,
130 struct nf_queue_entry *entry)
132 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
134 if (entry->hook == NF_INET_LOCAL_OUT) {
135 const struct iphdr *iph = ip_hdr(skb);
137 rt_info->tos = iph->tos;
138 rt_info->daddr = iph->daddr;
139 rt_info->saddr = iph->saddr;
143 static int nf_ip_reroute(struct sk_buff *skb,
144 const struct nf_queue_entry *entry)
146 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
148 if (entry->hook == NF_INET_LOCAL_OUT) {
149 const struct iphdr *iph = ip_hdr(skb);
151 if (!(iph->tos == rt_info->tos
152 && iph->daddr == rt_info->daddr
153 && iph->saddr == rt_info->saddr))
154 return ip_route_me_harder(skb, RTN_UNSPEC);
159 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
160 unsigned int dataoff, u_int8_t protocol)
162 const struct iphdr *iph = ip_hdr(skb);
165 switch (skb->ip_summed) {
166 case CHECKSUM_COMPLETE:
167 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
169 if ((protocol == 0 && !csum_fold(skb->csum)) ||
170 !csum_tcpudp_magic(iph->saddr, iph->daddr,
171 skb->len - dataoff, protocol,
173 skb->ip_summed = CHECKSUM_UNNECESSARY;
181 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
184 csum = __skb_checksum_complete(skb);
188 EXPORT_SYMBOL(nf_ip_checksum);
190 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
191 unsigned int dataoff, unsigned int len,
194 const struct iphdr *iph = ip_hdr(skb);
197 switch (skb->ip_summed) {
198 case CHECKSUM_COMPLETE:
199 if (len == skb->len - dataoff)
200 return nf_ip_checksum(skb, hook, dataoff, protocol);
203 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
204 skb->len - dataoff, 0);
205 skb->ip_summed = CHECKSUM_NONE;
206 csum = __skb_checksum_complete_head(skb, dataoff + len);
208 skb->ip_summed = CHECKSUM_UNNECESSARY;
213 static int nf_ip_route(struct dst_entry **dst, struct flowi *fl)
215 return ip_route_output_key(&init_net, (struct rtable **)dst, fl);
218 static const struct nf_afinfo nf_ip_afinfo = {
220 .checksum = nf_ip_checksum,
221 .checksum_partial = nf_ip_checksum_partial,
222 .route = nf_ip_route,
223 .saveroute = nf_ip_saveroute,
224 .reroute = nf_ip_reroute,
225 .route_key_size = sizeof(struct ip_rt_info),
228 static int ipv4_netfilter_init(void)
230 return nf_register_afinfo(&nf_ip_afinfo);
233 static void ipv4_netfilter_fini(void)
235 nf_unregister_afinfo(&nf_ip_afinfo);
238 module_init(ipv4_netfilter_init);
239 module_exit(ipv4_netfilter_fini);
242 struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
243 { .procname = "net", .ctl_name = CTL_NET, },
244 { .procname = "ipv4", .ctl_name = NET_IPV4, },
245 { .procname = "netfilter", .ctl_name = NET_IPV4_NETFILTER, },
248 EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
249 #endif /* CONFIG_SYSCTL */