kconfig/gconf: silent missing prototype warnings
[linux-2.6/linux-mips.git] / net / ipv4 / netfilter.c
blob4614babdc45fec0a2c5dbf553576267ba78d79b8
1 /* IPv4 specific functions of netfilter core */
2 #include <linux/kernel.h>
3 #include <linux/netfilter.h>
4 #include <linux/netfilter_ipv4.h>
5 #include <linux/ip.h>
6 #include <linux/skbuff.h>
7 #include <linux/gfp.h>
8 #include <net/route.h>
9 #include <net/xfrm.h>
10 #include <net/ip.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);
18 struct rtable *rt;
19 struct flowi4 fl4 = {};
20 unsigned long orefdst;
21 unsigned int hh_len;
22 unsigned int type;
24 type = inet_addr_type(net, iph->saddr);
25 if (skb->sk && inet_sk(skb->sk)->transparent)
26 type = RTN_LOCAL;
27 if (addr_type == RTN_UNSPEC)
28 addr_type = type;
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 fl4.daddr = iph->daddr;
35 if (type == RTN_LOCAL)
36 fl4.saddr = iph->saddr;
37 fl4.flowi4_tos = RT_TOS(iph->tos);
38 fl4.flowi4_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
39 fl4.flowi4_mark = skb->mark;
40 fl4.flowi4_flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
41 rt = ip_route_output_key(net, &fl4);
42 if (IS_ERR(rt))
43 return -1;
45 /* Drop old route. */
46 skb_dst_drop(skb);
47 skb_dst_set(skb, &rt->dst);
48 } else {
49 /* non-local src, find valid iif to satisfy
50 * rp-filter when calling ip_route_input. */
51 fl4.daddr = iph->saddr;
52 rt = ip_route_output_key(net, &fl4);
53 if (IS_ERR(rt))
54 return -1;
56 orefdst = skb->_skb_refdst;
57 if (ip_route_input(skb, iph->daddr, iph->saddr,
58 RT_TOS(iph->tos), rt->dst.dev) != 0) {
59 dst_release(&rt->dst);
60 return -1;
62 dst_release(&rt->dst);
63 refdst_drop(orefdst);
66 if (skb_dst(skb)->error)
67 return -1;
69 #ifdef CONFIG_XFRM
70 if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
71 xfrm_decode_session(skb, flowi4_to_flowi(&fl4), AF_INET) == 0) {
72 struct dst_entry *dst = skb_dst(skb);
73 skb_dst_set(skb, NULL);
74 dst = xfrm_lookup(net, dst, flowi4_to_flowi(&fl4), skb->sk, 0);
75 if (IS_ERR(dst))
76 return -1;
77 skb_dst_set(skb, dst);
79 #endif
81 /* Change in oif may mean change in hh_len. */
82 hh_len = skb_dst(skb)->dev->hard_header_len;
83 if (skb_headroom(skb) < hh_len &&
84 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
85 return -1;
87 return 0;
89 EXPORT_SYMBOL(ip_route_me_harder);
91 #ifdef CONFIG_XFRM
92 int ip_xfrm_me_harder(struct sk_buff *skb)
94 struct flowi fl;
95 unsigned int hh_len;
96 struct dst_entry *dst;
98 if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
99 return 0;
100 if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
101 return -1;
103 dst = skb_dst(skb);
104 if (dst->xfrm)
105 dst = ((struct xfrm_dst *)dst)->route;
106 dst_hold(dst);
108 dst = xfrm_lookup(dev_net(dst->dev), dst, &fl, skb->sk, 0);
109 if (IS_ERR(dst))
110 return -1;
112 skb_dst_drop(skb);
113 skb_dst_set(skb, dst);
115 /* Change in oif may mean change in hh_len. */
116 hh_len = skb_dst(skb)->dev->hard_header_len;
117 if (skb_headroom(skb) < hh_len &&
118 pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
119 return -1;
120 return 0;
122 EXPORT_SYMBOL(ip_xfrm_me_harder);
123 #endif
125 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
126 EXPORT_SYMBOL(ip_nat_decode_session);
129 * Extra routing may needed on local out, as the QUEUE target never
130 * returns control to the table.
133 struct ip_rt_info {
134 __be32 daddr;
135 __be32 saddr;
136 u_int8_t tos;
137 u_int32_t mark;
140 static void nf_ip_saveroute(const struct sk_buff *skb,
141 struct nf_queue_entry *entry)
143 struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
145 if (entry->hook == NF_INET_LOCAL_OUT) {
146 const struct iphdr *iph = ip_hdr(skb);
148 rt_info->tos = iph->tos;
149 rt_info->daddr = iph->daddr;
150 rt_info->saddr = iph->saddr;
151 rt_info->mark = skb->mark;
155 static int nf_ip_reroute(struct sk_buff *skb,
156 const struct nf_queue_entry *entry)
158 const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
160 if (entry->hook == NF_INET_LOCAL_OUT) {
161 const struct iphdr *iph = ip_hdr(skb);
163 if (!(iph->tos == rt_info->tos &&
164 skb->mark == rt_info->mark &&
165 iph->daddr == rt_info->daddr &&
166 iph->saddr == rt_info->saddr))
167 return ip_route_me_harder(skb, RTN_UNSPEC);
169 return 0;
172 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
173 unsigned int dataoff, u_int8_t protocol)
175 const struct iphdr *iph = ip_hdr(skb);
176 __sum16 csum = 0;
178 switch (skb->ip_summed) {
179 case CHECKSUM_COMPLETE:
180 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
181 break;
182 if ((protocol == 0 && !csum_fold(skb->csum)) ||
183 !csum_tcpudp_magic(iph->saddr, iph->daddr,
184 skb->len - dataoff, protocol,
185 skb->csum)) {
186 skb->ip_summed = CHECKSUM_UNNECESSARY;
187 break;
189 /* fall through */
190 case CHECKSUM_NONE:
191 if (protocol == 0)
192 skb->csum = 0;
193 else
194 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
195 skb->len - dataoff,
196 protocol, 0);
197 csum = __skb_checksum_complete(skb);
199 return csum;
201 EXPORT_SYMBOL(nf_ip_checksum);
203 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
204 unsigned int dataoff, unsigned int len,
205 u_int8_t protocol)
207 const struct iphdr *iph = ip_hdr(skb);
208 __sum16 csum = 0;
210 switch (skb->ip_summed) {
211 case CHECKSUM_COMPLETE:
212 if (len == skb->len - dataoff)
213 return nf_ip_checksum(skb, hook, dataoff, protocol);
214 /* fall through */
215 case CHECKSUM_NONE:
216 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
217 skb->len - dataoff, 0);
218 skb->ip_summed = CHECKSUM_NONE;
219 return __skb_checksum_complete_head(skb, dataoff + len);
221 return csum;
224 static int nf_ip_route(struct net *net, struct dst_entry **dst,
225 struct flowi *fl, bool strict __always_unused)
227 struct rtable *rt = ip_route_output_key(net, &fl->u.ip4);
228 if (IS_ERR(rt))
229 return PTR_ERR(rt);
230 *dst = &rt->dst;
231 return 0;
234 static const struct nf_afinfo nf_ip_afinfo = {
235 .family = AF_INET,
236 .checksum = nf_ip_checksum,
237 .checksum_partial = nf_ip_checksum_partial,
238 .route = nf_ip_route,
239 .saveroute = nf_ip_saveroute,
240 .reroute = nf_ip_reroute,
241 .route_key_size = sizeof(struct ip_rt_info),
244 static int ipv4_netfilter_init(void)
246 return nf_register_afinfo(&nf_ip_afinfo);
249 static void ipv4_netfilter_fini(void)
251 nf_unregister_afinfo(&nf_ip_afinfo);
254 module_init(ipv4_netfilter_init);
255 module_exit(ipv4_netfilter_fini);
257 #ifdef CONFIG_SYSCTL
258 struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
259 { .procname = "net", },
260 { .procname = "ipv4", },
261 { .procname = "netfilter", },
264 EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
265 #endif /* CONFIG_SYSCTL */