ipv4: fix redirect handling
[linux-2.6.git] / net / ipv6 / netfilter.c
1 #include <linux/kernel.h>
2 #include <linux/init.h>
3 #include <linux/ipv6.h>
4 #include <linux/netfilter.h>
5 #include <linux/netfilter_ipv6.h>
6 #include <net/dst.h>
7 #include <net/ipv6.h>
8 #include <net/ip6_route.h>
9 #include <net/xfrm.h>
10 #include <net/ip6_checksum.h>
11 #include <net/netfilter/nf_queue.h>
12
13 int ip6_route_me_harder(struct sk_buff *skb)
14 {
15         struct net *net = dev_net(skb_dst(skb)->dev);
16         const struct ipv6hdr *iph = ipv6_hdr(skb);
17         struct dst_entry *dst;
18         struct flowi6 fl6 = {
19                 .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
20                 .flowi6_mark = skb->mark,
21                 .daddr = iph->daddr,
22                 .saddr = iph->saddr,
23         };
24
25         dst = ip6_route_output(net, skb->sk, &fl6);
26         if (dst->error) {
27                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
28                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
29                 dst_release(dst);
30                 return -EINVAL;
31         }
32
33         /* Drop old route. */
34         skb_dst_drop(skb);
35
36         skb_dst_set(skb, dst);
37
38 #ifdef CONFIG_XFRM
39         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
40             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
41                 skb_dst_set(skb, NULL);
42                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0);
43                 if (IS_ERR(dst))
44                         return -1;
45                 skb_dst_set(skb, dst);
46         }
47 #endif
48
49         return 0;
50 }
51 EXPORT_SYMBOL(ip6_route_me_harder);
52
53 /*
54  * Extra routing may needed on local out, as the QUEUE target never
55  * returns control to the table.
56  */
57
58 struct ip6_rt_info {
59         struct in6_addr daddr;
60         struct in6_addr saddr;
61         u_int32_t mark;
62 };
63
64 static void nf_ip6_saveroute(const struct sk_buff *skb,
65                              struct nf_queue_entry *entry)
66 {
67         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
68
69         if (entry->hook == NF_INET_LOCAL_OUT) {
70                 const struct ipv6hdr *iph = ipv6_hdr(skb);
71
72                 rt_info->daddr = iph->daddr;
73                 rt_info->saddr = iph->saddr;
74                 rt_info->mark = skb->mark;
75         }
76 }
77
78 static int nf_ip6_reroute(struct sk_buff *skb,
79                           const struct nf_queue_entry *entry)
80 {
81         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
82
83         if (entry->hook == NF_INET_LOCAL_OUT) {
84                 const struct ipv6hdr *iph = ipv6_hdr(skb);
85                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
86                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
87                     skb->mark != rt_info->mark)
88                         return ip6_route_me_harder(skb);
89         }
90         return 0;
91 }
92
93 static int nf_ip6_route(struct net *net, struct dst_entry **dst,
94                         struct flowi *fl, bool strict)
95 {
96         static const struct ipv6_pinfo fake_pinfo;
97         static const struct inet_sock fake_sk = {
98                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
99                 .sk.sk_bound_dev_if = 1,
100                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
101         };
102         const void *sk = strict ? &fake_sk : NULL;
103
104         *dst = ip6_route_output(net, sk, &fl->u.ip6);
105         return (*dst)->error;
106 }
107
108 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
109                              unsigned int dataoff, u_int8_t protocol)
110 {
111         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
112         __sum16 csum = 0;
113
114         switch (skb->ip_summed) {
115         case CHECKSUM_COMPLETE:
116                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
117                         break;
118                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
119                                      skb->len - dataoff, protocol,
120                                      csum_sub(skb->csum,
121                                               skb_checksum(skb, 0,
122                                                            dataoff, 0)))) {
123                         skb->ip_summed = CHECKSUM_UNNECESSARY;
124                         break;
125                 }
126                 /* fall through */
127         case CHECKSUM_NONE:
128                 skb->csum = ~csum_unfold(
129                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
130                                              skb->len - dataoff,
131                                              protocol,
132                                              csum_sub(0,
133                                                       skb_checksum(skb, 0,
134                                                                    dataoff, 0))));
135                 csum = __skb_checksum_complete(skb);
136         }
137         return csum;
138 }
139 EXPORT_SYMBOL(nf_ip6_checksum);
140
141 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
142                                        unsigned int dataoff, unsigned int len,
143                                        u_int8_t protocol)
144 {
145         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
146         __wsum hsum;
147         __sum16 csum = 0;
148
149         switch (skb->ip_summed) {
150         case CHECKSUM_COMPLETE:
151                 if (len == skb->len - dataoff)
152                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
153                 /* fall through */
154         case CHECKSUM_NONE:
155                 hsum = skb_checksum(skb, 0, dataoff, 0);
156                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
157                                                          &ip6h->daddr,
158                                                          skb->len - dataoff,
159                                                          protocol,
160                                                          csum_sub(0, hsum)));
161                 skb->ip_summed = CHECKSUM_NONE;
162                 return __skb_checksum_complete_head(skb, dataoff + len);
163         }
164         return csum;
165 };
166
167 static const struct nf_afinfo nf_ip6_afinfo = {
168         .family                 = AF_INET6,
169         .checksum               = nf_ip6_checksum,
170         .checksum_partial       = nf_ip6_checksum_partial,
171         .route                  = nf_ip6_route,
172         .saveroute              = nf_ip6_saveroute,
173         .reroute                = nf_ip6_reroute,
174         .route_key_size         = sizeof(struct ip6_rt_info),
175 };
176
177 int __init ipv6_netfilter_init(void)
178 {
179         return nf_register_afinfo(&nf_ip6_afinfo);
180 }
181
182 /* This can be called from inet6_init() on errors, so it cannot
183  * be marked __exit. -DaveM
184  */
185 void ipv6_netfilter_fini(void)
186 {
187         nf_unregister_afinfo(&nf_ip6_afinfo);
188 }