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>
11 #include <net/netfilter/nf_queue.h>
13 /* route_me_harder function, used by iptable_nat, iptable_mangle + ip_queue */
14 int ip_route_me_harder(struct sk_buff *skb, unsigned addr_type)
16 struct net *net = dev_net(skb_dst(skb)->dev);
17 const struct iphdr *iph = ip_hdr(skb);
20 unsigned long orefdst;
24 type = inet_addr_type(net, iph->saddr);
25 if (skb->sk && inet_sk(skb->sk)->transparent)
27 if (addr_type == RTN_UNSPEC)
30 /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
31 * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
33 if (addr_type == RTN_LOCAL) {
34 fl.nl_u.ip4_u.daddr = iph->daddr;
35 if (type == RTN_LOCAL)
36 fl.nl_u.ip4_u.saddr = iph->saddr;
37 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
38 fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
40 fl.flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
41 if (ip_route_output_key(net, &rt, &fl) != 0)
46 skb_dst_set(skb, &rt->u.dst);
48 /* non-local src, find valid iif to satisfy
49 * rp-filter when calling ip_route_input. */
50 fl.nl_u.ip4_u.daddr = iph->saddr;
51 if (ip_route_output_key(net, &rt, &fl) != 0)
54 orefdst = skb->_skb_refdst;
55 if (ip_route_input(skb, iph->daddr, iph->saddr,
56 RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
57 dst_release(&rt->u.dst);
60 dst_release(&rt->u.dst);
64 if (skb_dst(skb)->error)
68 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
69 xfrm_decode_session(skb, &fl, AF_INET) == 0) {
70 struct dst_entry *dst = skb_dst(skb);
71 skb_dst_set(skb, NULL);
72 if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
74 skb_dst_set(skb, dst);
78 /* Change in oif may mean change in hh_len. */
79 hh_len = skb_dst(skb)->dev->hard_header_len;
80 if (skb_headroom(skb) < hh_len &&
81 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
86 EXPORT_SYMBOL(ip_route_me_harder);
89 int ip_xfrm_me_harder(struct sk_buff *skb)
93 struct dst_entry *dst;
95 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
97 if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
102 dst = ((struct xfrm_dst *)dst)->route;
105 if (xfrm_lookup(dev_net(dst->dev), &dst, &fl, skb->sk, 0) < 0)
109 skb_dst_set(skb, dst);
111 /* Change in oif may mean change in hh_len. */
112 hh_len = skb_dst(skb)->dev->hard_header_len;
113 if (skb_headroom(skb) < hh_len &&
114 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
118 EXPORT_SYMBOL(ip_xfrm_me_harder);
121 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
122 EXPORT_SYMBOL(ip_nat_decode_session);
125 * Extra routing may needed on local out, as the QUEUE target never
126 * returns control to the table.
136 static void nf_ip_saveroute(const struct sk_buff *skb,
137 struct nf_queue_entry *entry)
139 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
141 if (entry->hook == NF_INET_LOCAL_OUT) {
142 const struct iphdr *iph = ip_hdr(skb);
144 rt_info->tos = iph->tos;
145 rt_info->daddr = iph->daddr;
146 rt_info->saddr = iph->saddr;
147 rt_info->mark = skb->mark;
151 static int nf_ip_reroute(struct sk_buff *skb,
152 const struct nf_queue_entry *entry)
154 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
156 if (entry->hook == NF_INET_LOCAL_OUT) {
157 const struct iphdr *iph = ip_hdr(skb);
159 if (!(iph->tos == rt_info->tos &&
160 skb->mark == rt_info->mark &&
161 iph->daddr == rt_info->daddr &&
162 iph->saddr == rt_info->saddr))
163 return ip_route_me_harder(skb, RTN_UNSPEC);
168 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
169 unsigned int dataoff, u_int8_t protocol)
171 const struct iphdr *iph = ip_hdr(skb);
174 switch (skb->ip_summed) {
175 case CHECKSUM_COMPLETE:
176 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
178 if ((protocol == 0 && !csum_fold(skb->csum)) ||
179 !csum_tcpudp_magic(iph->saddr, iph->daddr,
180 skb->len - dataoff, protocol,
182 skb->ip_summed = CHECKSUM_UNNECESSARY;
190 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
193 csum = __skb_checksum_complete(skb);
197 EXPORT_SYMBOL(nf_ip_checksum);
199 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
200 unsigned int dataoff, unsigned int len,
203 const struct iphdr *iph = ip_hdr(skb);
206 switch (skb->ip_summed) {
207 case CHECKSUM_COMPLETE:
208 if (len == skb->len - dataoff)
209 return nf_ip_checksum(skb, hook, dataoff, protocol);
212 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
213 skb->len - dataoff, 0);
214 skb->ip_summed = CHECKSUM_NONE;
215 csum = __skb_checksum_complete_head(skb, dataoff + len);
217 skb->ip_summed = CHECKSUM_UNNECESSARY;
222 static int nf_ip_route(struct dst_entry **dst, struct flowi *fl)
224 return ip_route_output_key(&init_net, (struct rtable **)dst, fl);
227 static const struct nf_afinfo nf_ip_afinfo = {
229 .checksum = nf_ip_checksum,
230 .checksum_partial = nf_ip_checksum_partial,
231 .route = nf_ip_route,
232 .saveroute = nf_ip_saveroute,
233 .reroute = nf_ip_reroute,
234 .route_key_size = sizeof(struct ip_rt_info),
237 static int ipv4_netfilter_init(void)
239 return nf_register_afinfo(&nf_ip_afinfo);
242 static void ipv4_netfilter_fini(void)
244 nf_unregister_afinfo(&nf_ip_afinfo);
247 module_init(ipv4_netfilter_init);
248 module_exit(ipv4_netfilter_fini);
251 struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
252 { .procname = "net", },
253 { .procname = "ipv4", },
254 { .procname = "netfilter", },
257 EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
258 #endif /* CONFIG_SYSCTL */