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.fl4_dst = iph->daddr;
35 if (type == RTN_LOCAL)
36 fl.fl4_src = iph->saddr;
37 fl.fl4_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->dst);
48 /* non-local src, find valid iif to satisfy
49 * rp-filter when calling ip_route_input. */
50 fl.fl4_dst = 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->dst.dev) != 0) {
57 dst_release(&rt->dst);
60 dst_release(&rt->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 dst = xfrm_lookup(net, dst, &fl, skb->sk, 0);
75 skb_dst_set(skb, dst);
79 /* Change in oif may mean change in hh_len. */
80 hh_len = skb_dst(skb)->dev->hard_header_len;
81 if (skb_headroom(skb) < hh_len &&
82 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
87 EXPORT_SYMBOL(ip_route_me_harder);
90 int ip_xfrm_me_harder(struct sk_buff *skb)
94 struct dst_entry *dst;
96 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
98 if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
103 dst = ((struct xfrm_dst *)dst)->route;
106 dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
111 skb_dst_set(skb, dst);
113 /* Change in oif may mean change in hh_len. */
114 hh_len = skb_dst(skb)->dev->hard_header_len;
115 if (skb_headroom(skb) < hh_len &&
116 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
120 EXPORT_SYMBOL(ip_xfrm_me_harder);
123 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
124 EXPORT_SYMBOL(ip_nat_decode_session);
127 * Extra routing may needed on local out, as the QUEUE target never
128 * returns control to the table.
138 static void nf_ip_saveroute(const struct sk_buff *skb,
139 struct nf_queue_entry *entry)
141 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
143 if (entry->hook == NF_INET_LOCAL_OUT) {
144 const struct iphdr *iph = ip_hdr(skb);
146 rt_info->tos = iph->tos;
147 rt_info->daddr = iph->daddr;
148 rt_info->saddr = iph->saddr;
149 rt_info->mark = skb->mark;
153 static int nf_ip_reroute(struct sk_buff *skb,
154 const struct nf_queue_entry *entry)
156 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
158 if (entry->hook == NF_INET_LOCAL_OUT) {
159 const struct iphdr *iph = ip_hdr(skb);
161 if (!(iph->tos == rt_info->tos &&
162 skb->mark == rt_info->mark &&
163 iph->daddr == rt_info->daddr &&
164 iph->saddr == rt_info->saddr))
165 return ip_route_me_harder(skb, RTN_UNSPEC);
170 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
171 unsigned int dataoff, u_int8_t protocol)
173 const struct iphdr *iph = ip_hdr(skb);
176 switch (skb->ip_summed) {
177 case CHECKSUM_COMPLETE:
178 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
180 if ((protocol == 0 && !csum_fold(skb->csum)) ||
181 !csum_tcpudp_magic(iph->saddr, iph->daddr,
182 skb->len - dataoff, protocol,
184 skb->ip_summed = CHECKSUM_UNNECESSARY;
192 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
195 csum = __skb_checksum_complete(skb);
199 EXPORT_SYMBOL(nf_ip_checksum);
201 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
202 unsigned int dataoff, unsigned int len,
205 const struct iphdr *iph = ip_hdr(skb);
208 switch (skb->ip_summed) {
209 case CHECKSUM_COMPLETE:
210 if (len == skb->len - dataoff)
211 return nf_ip_checksum(skb, hook, dataoff, protocol);
214 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
215 skb->len - dataoff, 0);
216 skb->ip_summed = CHECKSUM_NONE;
217 return __skb_checksum_complete_head(skb, dataoff + len);
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 */