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         struct ipv6hdr *iph = ipv6_hdr(skb);
  17         struct dst_entry *dst;
  18         struct flowi fl = {
  19                 .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  20                 .mark = skb->mark,
  21                 .nl_u =
  22                 { .ip6_u =
  23                   { .daddr = iph->daddr,
  24                     .saddr = iph->saddr, } },
  25         };
  26
  27         dst = ip6_route_output(net, skb->sk, &fl);
  28
  29 #ifdef CONFIG_XFRM
  30         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  31             xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
  32                 struct dst_entry *dst2 = skb_dst(skb);
  33
  34                 if (xfrm_lookup(net, &dst2, &fl, skb->sk, 0)) {
  35                         skb_dst_set(skb, NULL);
  36                         return -1;
  37                 }
  38                 skb_dst_set(skb, dst2);
  39         }
  40 #endif
  41
  42         if (dst->error) {
  43                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  44                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  45                 dst_release(dst);
  46                 return -EINVAL;
  47         }
  48
  49         /* Drop old route. */
  50         skb_dst_drop(skb);
  51
  52         skb_dst_set(skb, dst);
  53         return 0;
  54 }
  55 EXPORT_SYMBOL(ip6_route_me_harder);
  56
  57 /*
  58  * Extra routing may needed on local out, as the QUEUE target never
  59  * returns control to the table.
  60  */
  61
  62 struct ip6_rt_info {
  63         struct in6_addr daddr;
  64         struct in6_addr saddr;
  65         u_int32_t mark;
  66 };
  67
  68 static void nf_ip6_saveroute(const struct sk_buff *skb,
  69                              struct nf_queue_entry *entry)
  70 {
  71         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  72
  73         if (entry->hook == NF_INET_LOCAL_OUT) {
  74                 struct ipv6hdr *iph = ipv6_hdr(skb);
  75
  76                 rt_info->daddr = iph->daddr;
  77                 rt_info->saddr = iph->saddr;
  78                 rt_info->mark = skb->mark;
  79         }
  80 }
  81
  82 static int nf_ip6_reroute(struct sk_buff *skb,
  83                           const struct nf_queue_entry *entry)
  84 {
  85         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  86
  87         if (entry->hook == NF_INET_LOCAL_OUT) {
  88                 struct ipv6hdr *iph = ipv6_hdr(skb);
  89                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  90                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  91                     skb->mark != rt_info->mark)
  92                         return ip6_route_me_harder(skb);
  93         }
  94         return 0;
  95 }
  96
  97 static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
  98 {
  99         *dst = ip6_route_output(&init_net, NULL, fl);
 100         return (*dst)->error;
 101 }
 102
 103 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 104                              unsigned int dataoff, u_int8_t protocol)
 105 {
 106         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 107         __sum16 csum = 0;
 108
 109         switch (skb->ip_summed) {
 110         case CHECKSUM_COMPLETE:
 111                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 112                         break;
 113                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 114                                      skb->len - dataoff, protocol,
 115                                      csum_sub(skb->csum,
 116                                               skb_checksum(skb, 0,
 117                                                            dataoff, 0)))) {
 118                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 119                         break;
 120                 }
 121                 /* fall through */
 122         case CHECKSUM_NONE:
 123                 skb->csum = ~csum_unfold(
 124                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 125                                              skb->len - dataoff,
 126                                              protocol,
 127                                              csum_sub(0,
 128                                                       skb_checksum(skb, 0,
 129                                                                    dataoff, 0))));
 130                 csum = __skb_checksum_complete(skb);
 131         }
 132         return csum;
 133 }
 134 EXPORT_SYMBOL(nf_ip6_checksum);
 135
 136 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 137                                        unsigned int dataoff, unsigned int len,
 138                                        u_int8_t protocol)
 139 {
 140         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 141         __wsum hsum;
 142         __sum16 csum = 0;
 143
 144         switch (skb->ip_summed) {
 145         case CHECKSUM_COMPLETE:
 146                 if (len == skb->len - dataoff)
 147                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 148                 /* fall through */
 149         case CHECKSUM_NONE:
 150                 hsum = skb_checksum(skb, 0, dataoff, 0);
 151                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 152                                                          &ip6h->daddr,
 153                                                          skb->len - dataoff,
 154                                                          protocol,
 155                                                          csum_sub(0, hsum)));
 156                 skb->ip_summed = CHECKSUM_NONE;
 157                 csum = __skb_checksum_complete_head(skb, dataoff + len);
 158                 if (!csum)
 159                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 160         }
 161         return csum;
 162 };
 163
 164 static const struct nf_afinfo nf_ip6_afinfo = {
 165         .family                 = AF_INET6,
 166         .checksum               = nf_ip6_checksum,
 167         .checksum_partial       = nf_ip6_checksum_partial,
 168         .route                  = nf_ip6_route,
 169         .saveroute              = nf_ip6_saveroute,
 170         .reroute                = nf_ip6_reroute,
 171         .route_key_size         = sizeof(struct ip6_rt_info),
 172 };
 173
 174 int __init ipv6_netfilter_init(void)
 175 {
 176         return nf_register_afinfo(&nf_ip6_afinfo);
 177 }
 178
 179 /* This can be called from inet6_init() on errors, so it cannot
 180  * be marked __exit. -DaveM
 181  */
 182 void ipv6_netfilter_fini(void)
 183 {
 184         nf_unregister_afinfo(&nf_ip6_afinfo);
 185 }