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
  12 int ip6_route_me_harder(struct sk_buff *skb)
  13 {
  14         struct ipv6hdr *iph = skb->nh.ipv6h;
  15         struct dst_entry *dst;
  16         struct flowi fl = {
  17                 .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  18                 .nl_u =
  19                 { .ip6_u =
  20                   { .daddr = iph->daddr,
  21                     .saddr = iph->saddr, } },
  22         };
  23
  24         dst = ip6_route_output(skb->sk, &fl);
  25
  26 #ifdef CONFIG_XFRM
  27         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  28             xfrm_decode_session(skb, &fl, AF_INET6) == 0)
  29                 if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
  30                         return -1;
  31 #endif
  32
  33         if (dst->error) {
  34                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  35                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  36                 dst_release(dst);
  37                 return -EINVAL;
  38         }
  39
  40         /* Drop old route. */
  41         dst_release(skb->dst);
  42
  43         skb->dst = dst;
  44         return 0;
  45 }
  46 EXPORT_SYMBOL(ip6_route_me_harder);
  47
  48 /*
  49  * Extra routing may needed on local out, as the QUEUE target never
  50  * returns control to the table.
  51  */
  52
  53 struct ip6_rt_info {
  54         struct in6_addr daddr;
  55         struct in6_addr saddr;
  56 };
  57
  58 static void nf_ip6_saveroute(const struct sk_buff *skb, struct nf_info *info)
  59 {
  60         struct ip6_rt_info *rt_info = nf_info_reroute(info);
  61
  62         if (info->hook == NF_IP6_LOCAL_OUT) {
  63                 struct ipv6hdr *iph = skb->nh.ipv6h;
  64
  65                 rt_info->daddr = iph->daddr;
  66                 rt_info->saddr = iph->saddr;
  67         }
  68 }
  69
  70 static int nf_ip6_reroute(struct sk_buff **pskb, const struct nf_info *info)
  71 {
  72         struct ip6_rt_info *rt_info = nf_info_reroute(info);
  73
  74         if (info->hook == NF_IP6_LOCAL_OUT) {
  75                 struct ipv6hdr *iph = (*pskb)->nh.ipv6h;
  76                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  77                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr))
  78                         return ip6_route_me_harder(*pskb);
  79         }
  80         return 0;
  81 }
  82
  83 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  84                              unsigned int dataoff, u_int8_t protocol)
  85 {
  86         struct ipv6hdr *ip6h = skb->nh.ipv6h;
  87         __sum16 csum = 0;
  88
  89         switch (skb->ip_summed) {
  90         case CHECKSUM_COMPLETE:
  91                 if (hook != NF_IP6_PRE_ROUTING && hook != NF_IP6_LOCAL_IN)
  92                         break;
  93                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
  94                                      skb->len - dataoff, protocol,
  95                                      csum_sub(skb->csum,
  96                                               skb_checksum(skb, 0,
  97                                                            dataoff, 0)))) {
  98                         skb->ip_summed = CHECKSUM_UNNECESSARY;
  99                         break;
 100                 }
 101                 /* fall through */
 102         case CHECKSUM_NONE:
 103                 skb->csum = ~csum_unfold(
 104                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 105                                              skb->len - dataoff,
 106                                              protocol,
 107                                              csum_sub(0,
 108                                                       skb_checksum(skb, 0,
 109                                                                    dataoff, 0))));
 110                 csum = __skb_checksum_complete(skb);
 111         }
 112         return csum;
 113 }
 114
 115 EXPORT_SYMBOL(nf_ip6_checksum);
 116
 117 static struct nf_afinfo nf_ip6_afinfo = {
 118         .family         = AF_INET6,
 119         .checksum       = nf_ip6_checksum,
 120         .saveroute      = nf_ip6_saveroute,
 121         .reroute        = nf_ip6_reroute,
 122         .route_key_size = sizeof(struct ip6_rt_info),
 123 };
 124
 125 int __init ipv6_netfilter_init(void)
 126 {
 127         return nf_register_afinfo(&nf_ip6_afinfo);
 128 }
 129
 130 /* This can be called from inet6_init() on errors, so it cannot
 131  * be marked __exit. -DaveM
 132  */
 133 void ipv6_netfilter_fini(void)
 134 {
 135         nf_unregister_afinfo(&nf_ip6_afinfo);
 136 }