Merge branch 'master' of git://git.kernel.org/pub/scm/linux/kernel/git/kaber/nf-next-2.6
[linux-2.6.git] / net / ipv4 / netfilter.c
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 <net/route.h>
8 #include <net/xfrm.h>
9 #include <net/ip.h>
10 #include <net/netfilter/nf_queue.h>
11
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)
14 {
15         struct net *net = dev_net(skb->dst->dev);
16         const struct iphdr *iph = ip_hdr(skb);
17         struct rtable *rt;
18         struct flowi fl = {};
19         struct dst_entry *odst;
20         unsigned int hh_len;
21         unsigned int type;
22
23         type = inet_addr_type(net, iph->saddr);
24         if (skb->sk && inet_sk(skb->sk)->transparent)
25                 type = RTN_LOCAL;
26         if (addr_type == RTN_UNSPEC)
27                 addr_type = type;
28
29         /* some non-standard hacks like ipt_REJECT.c:send_reset() can cause
30          * packets with foreign saddr to appear on the NF_INET_LOCAL_OUT hook.
31          */
32         if (addr_type == RTN_LOCAL) {
33                 fl.nl_u.ip4_u.daddr = iph->daddr;
34                 if (type == RTN_LOCAL)
35                         fl.nl_u.ip4_u.saddr = iph->saddr;
36                 fl.nl_u.ip4_u.tos = RT_TOS(iph->tos);
37                 fl.oif = skb->sk ? skb->sk->sk_bound_dev_if : 0;
38                 fl.mark = skb->mark;
39                 fl.flags = skb->sk ? inet_sk_flowi_flags(skb->sk) : 0;
40                 if (ip_route_output_key(net, &rt, &fl) != 0)
41                         return -1;
42
43                 /* Drop old route. */
44                 dst_release(skb->dst);
45                 skb->dst = &rt->u.dst;
46         } else {
47                 /* non-local src, find valid iif to satisfy
48                  * rp-filter when calling ip_route_input. */
49                 fl.nl_u.ip4_u.daddr = iph->saddr;
50                 if (ip_route_output_key(net, &rt, &fl) != 0)
51                         return -1;
52
53                 odst = skb->dst;
54                 if (ip_route_input(skb, iph->daddr, iph->saddr,
55                                    RT_TOS(iph->tos), rt->u.dst.dev) != 0) {
56                         dst_release(&rt->u.dst);
57                         return -1;
58                 }
59                 dst_release(&rt->u.dst);
60                 dst_release(odst);
61         }
62
63         if (skb->dst->error)
64                 return -1;
65
66 #ifdef CONFIG_XFRM
67         if (!(IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED) &&
68             xfrm_decode_session(skb, &fl, AF_INET) == 0)
69                 if (xfrm_lookup(net, &skb->dst, &fl, skb->sk, 0))
70                         return -1;
71 #endif
72
73         /* Change in oif may mean change in hh_len. */
74         hh_len = skb->dst->dev->hard_header_len;
75         if (skb_headroom(skb) < hh_len &&
76             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
77                 return -1;
78
79         return 0;
80 }
81 EXPORT_SYMBOL(ip_route_me_harder);
82
83 #ifdef CONFIG_XFRM
84 int ip_xfrm_me_harder(struct sk_buff *skb)
85 {
86         struct flowi fl;
87         unsigned int hh_len;
88         struct dst_entry *dst;
89
90         if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
91                 return 0;
92         if (xfrm_decode_session(skb, &fl, AF_INET) < 0)
93                 return -1;
94
95         dst = skb->dst;
96         if (dst->xfrm)
97                 dst = ((struct xfrm_dst *)dst)->route;
98         dst_hold(dst);
99
100         if (xfrm_lookup(dev_net(dst->dev), &dst, &fl, skb->sk, 0) < 0)
101                 return -1;
102
103         dst_release(skb->dst);
104         skb->dst = dst;
105
106         /* Change in oif may mean change in hh_len. */
107         hh_len = skb->dst->dev->hard_header_len;
108         if (skb_headroom(skb) < hh_len &&
109             pskb_expand_head(skb, hh_len - skb_headroom(skb), 0, GFP_ATOMIC))
110                 return -1;
111         return 0;
112 }
113 EXPORT_SYMBOL(ip_xfrm_me_harder);
114 #endif
115
116 void (*ip_nat_decode_session)(struct sk_buff *, struct flowi *);
117 EXPORT_SYMBOL(ip_nat_decode_session);
118
119 /*
120  * Extra routing may needed on local out, as the QUEUE target never
121  * returns control to the table.
122  */
123
124 struct ip_rt_info {
125         __be32 daddr;
126         __be32 saddr;
127         u_int8_t tos;
128         u_int32_t mark;
129 };
130
131 static void nf_ip_saveroute(const struct sk_buff *skb,
132                             struct nf_queue_entry *entry)
133 {
134         struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
135
136         if (entry->hook == NF_INET_LOCAL_OUT) {
137                 const struct iphdr *iph = ip_hdr(skb);
138
139                 rt_info->tos = iph->tos;
140                 rt_info->daddr = iph->daddr;
141                 rt_info->saddr = iph->saddr;
142                 rt_info->mark = skb->mark;
143         }
144 }
145
146 static int nf_ip_reroute(struct sk_buff *skb,
147                          const struct nf_queue_entry *entry)
148 {
149         const struct ip_rt_info *rt_info = nf_queue_entry_reroute(entry);
150
151         if (entry->hook == NF_INET_LOCAL_OUT) {
152                 const struct iphdr *iph = ip_hdr(skb);
153
154                 if (!(iph->tos == rt_info->tos
155                       && skb->mark == rt_info->mark
156                       && iph->daddr == rt_info->daddr
157                       && iph->saddr == rt_info->saddr))
158                         return ip_route_me_harder(skb, RTN_UNSPEC);
159         }
160         return 0;
161 }
162
163 __sum16 nf_ip_checksum(struct sk_buff *skb, unsigned int hook,
164                             unsigned int dataoff, u_int8_t protocol)
165 {
166         const struct iphdr *iph = ip_hdr(skb);
167         __sum16 csum = 0;
168
169         switch (skb->ip_summed) {
170         case CHECKSUM_COMPLETE:
171                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
172                         break;
173                 if ((protocol == 0 && !csum_fold(skb->csum)) ||
174                     !csum_tcpudp_magic(iph->saddr, iph->daddr,
175                                        skb->len - dataoff, protocol,
176                                        skb->csum)) {
177                         skb->ip_summed = CHECKSUM_UNNECESSARY;
178                         break;
179                 }
180                 /* fall through */
181         case CHECKSUM_NONE:
182                 if (protocol == 0)
183                         skb->csum = 0;
184                 else
185                         skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr,
186                                                        skb->len - dataoff,
187                                                        protocol, 0);
188                 csum = __skb_checksum_complete(skb);
189         }
190         return csum;
191 }
192 EXPORT_SYMBOL(nf_ip_checksum);
193
194 static __sum16 nf_ip_checksum_partial(struct sk_buff *skb, unsigned int hook,
195                                       unsigned int dataoff, unsigned int len,
196                                       u_int8_t protocol)
197 {
198         const struct iphdr *iph = ip_hdr(skb);
199         __sum16 csum = 0;
200
201         switch (skb->ip_summed) {
202         case CHECKSUM_COMPLETE:
203                 if (len == skb->len - dataoff)
204                         return nf_ip_checksum(skb, hook, dataoff, protocol);
205                 /* fall through */
206         case CHECKSUM_NONE:
207                 skb->csum = csum_tcpudp_nofold(iph->saddr, iph->daddr, protocol,
208                                                skb->len - dataoff, 0);
209                 skb->ip_summed = CHECKSUM_NONE;
210                 csum = __skb_checksum_complete_head(skb, dataoff + len);
211                 if (!csum)
212                         skb->ip_summed = CHECKSUM_UNNECESSARY;
213         }
214         return csum;
215 }
216
217 static int nf_ip_route(struct dst_entry **dst, struct flowi *fl)
218 {
219         return ip_route_output_key(&init_net, (struct rtable **)dst, fl);
220 }
221
222 static const struct nf_afinfo nf_ip_afinfo = {
223         .family                 = AF_INET,
224         .checksum               = nf_ip_checksum,
225         .checksum_partial       = nf_ip_checksum_partial,
226         .route                  = nf_ip_route,
227         .saveroute              = nf_ip_saveroute,
228         .reroute                = nf_ip_reroute,
229         .route_key_size         = sizeof(struct ip_rt_info),
230 };
231
232 static int ipv4_netfilter_init(void)
233 {
234         return nf_register_afinfo(&nf_ip_afinfo);
235 }
236
237 static void ipv4_netfilter_fini(void)
238 {
239         nf_unregister_afinfo(&nf_ip_afinfo);
240 }
241
242 module_init(ipv4_netfilter_init);
243 module_exit(ipv4_netfilter_fini);
244
245 #ifdef CONFIG_SYSCTL
246 struct ctl_path nf_net_ipv4_netfilter_sysctl_path[] = {
247         { .procname = "net", .ctl_name = CTL_NET, },
248         { .procname = "ipv4", .ctl_name = NET_IPV4, },
249         { .procname = "netfilter", .ctl_name = NET_IPV4_NETFILTER, },
250         { }
251 };
252 EXPORT_SYMBOL_GPL(nf_net_ipv4_netfilter_sysctl_path);
253 #endif /* CONFIG_SYSCTL */