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 = ipv6_hdr(skb);
  15         struct dst_entry *dst;
  16         struct flowi fl = {
  17                 .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  18                 .mark = skb->mark,
  19                 .nl_u =
  20                 { .ip6_u =
  21                   { .daddr = iph->daddr,
  22                     .saddr = iph->saddr, } },
  23         };
  24
  25         dst = ip6_route_output(skb->sk, &fl);
  26
  27 #ifdef CONFIG_XFRM
  28         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  29             xfrm_decode_session(skb, &fl, AF_INET6) == 0)
  30                 if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
  31                         return -1;
  32 #endif
  33
  34         if (dst->error) {
  35                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  36                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  37                 dst_release(dst);
  38                 return -EINVAL;
  39         }
  40
  41         /* Drop old route. */
  42         dst_release(skb->dst);
  43
  44         skb->dst = dst;
  45         return 0;
  46 }
  47 EXPORT_SYMBOL(ip6_route_me_harder);
  48
  49 /*
  50  * Extra routing may needed on local out, as the QUEUE target never
  51  * returns control to the table.
  52  */
  53
  54 struct ip6_rt_info {
  55         struct in6_addr daddr;
  56         struct in6_addr saddr;
  57 };
  58
  59 static void nf_ip6_saveroute(const struct sk_buff *skb, struct nf_info *info)
  60 {
  61         struct ip6_rt_info *rt_info = nf_info_reroute(info);
  62
  63         if (info->hook == NF_IP6_LOCAL_OUT) {
  64                 struct ipv6hdr *iph = ipv6_hdr(skb);
  65
  66                 rt_info->daddr = iph->daddr;
  67                 rt_info->saddr = iph->saddr;
  68         }
  69 }
  70
  71 static int nf_ip6_reroute(struct sk_buff *skb, const struct nf_info *info)
  72 {
  73         struct ip6_rt_info *rt_info = nf_info_reroute(info);
  74
  75         if (info->hook == NF_IP6_LOCAL_OUT) {
  76                 struct ipv6hdr *iph = ipv6_hdr(skb);
  77                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  78                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr))
  79                         return ip6_route_me_harder(skb);
  80         }
  81         return 0;
  82 }
  83
  84 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  85                              unsigned int dataoff, u_int8_t protocol)
  86 {
  87         struct ipv6hdr *ip6h = ipv6_hdr(skb);
  88         __sum16 csum = 0;
  89
  90         switch (skb->ip_summed) {
  91         case CHECKSUM_COMPLETE:
  92                 if (hook != NF_IP6_PRE_ROUTING && hook != NF_IP6_LOCAL_IN)
  93                         break;
  94                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
  95                                      skb->len - dataoff, protocol,
  96                                      csum_sub(skb->csum,
  97                                               skb_checksum(skb, 0,
  98                                                            dataoff, 0)))) {
  99                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 100                         break;
 101                 }
 102                 /* fall through */
 103         case CHECKSUM_NONE:
 104                 skb->csum = ~csum_unfold(
 105                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 106                                              skb->len - dataoff,
 107                                              protocol,
 108                                              csum_sub(0,
 109                                                       skb_checksum(skb, 0,
 110                                                                    dataoff, 0))));
 111                 csum = __skb_checksum_complete(skb);
 112         }
 113         return csum;
 114 }
 115
 116 EXPORT_SYMBOL(nf_ip6_checksum);
 117
 118 static struct nf_afinfo nf_ip6_afinfo = {
 119         .family         = AF_INET6,
 120         .checksum       = nf_ip6_checksum,
 121         .saveroute      = nf_ip6_saveroute,
 122         .reroute        = nf_ip6_reroute,
 123         .route_key_size = sizeof(struct ip6_rt_info),
 124 };
 125
 126 int __init ipv6_netfilter_init(void)
 127 {
 128         return nf_register_afinfo(&nf_ip6_afinfo);
 129 }
 130
 131 /* This can be called from inet6_init() on errors, so it cannot
 132  * be marked __exit. -DaveM
 133  */
 134 void ipv6_netfilter_fini(void)
 135 {
 136         nf_unregister_afinfo(&nf_ip6_afinfo);
 137 }