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                 .fl6_dst = iph->daddr,
  22                 .fl6_src = iph->saddr,
  23         };
  24
  25         dst = ip6_route_output(net, skb->sk, &fl);
  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, &fl, AF_INET6) == 0) {
  41                 skb_dst_set(skb, NULL);
  42                 if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
  43                         return -1;
  44                 skb_dst_set(skb, dst);
  45         }
  46 #endif
  47
  48         return 0;
  49 }
  50 EXPORT_SYMBOL(ip6_route_me_harder);
  51
  52 /*
  53  * Extra routing may needed on local out, as the QUEUE target never
  54  * returns control to the table.
  55  */
  56
  57 struct ip6_rt_info {
  58         struct in6_addr daddr;
  59         struct in6_addr saddr;
  60         u_int32_t mark;
  61 };
  62
  63 static void nf_ip6_saveroute(const struct sk_buff *skb,
  64                              struct nf_queue_entry *entry)
  65 {
  66         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  67
  68         if (entry->hook == NF_INET_LOCAL_OUT) {
  69                 struct ipv6hdr *iph = ipv6_hdr(skb);
  70
  71                 rt_info->daddr = iph->daddr;
  72                 rt_info->saddr = iph->saddr;
  73                 rt_info->mark = skb->mark;
  74         }
  75 }
  76
  77 static int nf_ip6_reroute(struct sk_buff *skb,
  78                           const struct nf_queue_entry *entry)
  79 {
  80         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  81
  82         if (entry->hook == NF_INET_LOCAL_OUT) {
  83                 struct ipv6hdr *iph = ipv6_hdr(skb);
  84                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  85                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  86                     skb->mark != rt_info->mark)
  87                         return ip6_route_me_harder(skb);
  88         }
  89         return 0;
  90 }
  91
  92 static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
  93 {
  94         *dst = ip6_route_output(&init_net, NULL, fl);
  95         return (*dst)->error;
  96 }
  97
  98 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  99                              unsigned int dataoff, u_int8_t protocol)
 100 {
 101         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 102         __sum16 csum = 0;
 103
 104         switch (skb->ip_summed) {
 105         case CHECKSUM_COMPLETE:
 106                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 107                         break;
 108                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 109                                      skb->len - dataoff, protocol,
 110                                      csum_sub(skb->csum,
 111                                               skb_checksum(skb, 0,
 112                                                            dataoff, 0)))) {
 113                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 114                         break;
 115                 }
 116                 /* fall through */
 117         case CHECKSUM_NONE:
 118                 skb->csum = ~csum_unfold(
 119                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 120                                              skb->len - dataoff,
 121                                              protocol,
 122                                              csum_sub(0,
 123                                                       skb_checksum(skb, 0,
 124                                                                    dataoff, 0))));
 125                 csum = __skb_checksum_complete(skb);
 126         }
 127         return csum;
 128 }
 129 EXPORT_SYMBOL(nf_ip6_checksum);
 130
 131 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 132                                        unsigned int dataoff, unsigned int len,
 133                                        u_int8_t protocol)
 134 {
 135         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 136         __wsum hsum;
 137         __sum16 csum = 0;
 138
 139         switch (skb->ip_summed) {
 140         case CHECKSUM_COMPLETE:
 141                 if (len == skb->len - dataoff)
 142                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 143                 /* fall through */
 144         case CHECKSUM_NONE:
 145                 hsum = skb_checksum(skb, 0, dataoff, 0);
 146                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 147                                                          &ip6h->daddr,
 148                                                          skb->len - dataoff,
 149                                                          protocol,
 150                                                          csum_sub(0, hsum)));
 151                 skb->ip_summed = CHECKSUM_NONE;
 152                 return __skb_checksum_complete_head(skb, dataoff + len);
 153         }
 154         return csum;
 155 };
 156
 157 static const struct nf_afinfo nf_ip6_afinfo = {
 158         .family                 = AF_INET6,
 159         .checksum               = nf_ip6_checksum,
 160         .checksum_partial       = nf_ip6_checksum_partial,
 161         .route                  = nf_ip6_route,
 162         .saveroute              = nf_ip6_saveroute,
 163         .reroute                = nf_ip6_reroute,
 164         .route_key_size         = sizeof(struct ip6_rt_info),
 165 };
 166
 167 int __init ipv6_netfilter_init(void)
 168 {
 169         return nf_register_afinfo(&nf_ip6_afinfo);
 170 }
 171
 172 /* This can be called from inet6_init() on errors, so it cannot
 173  * be marked __exit. -DaveM
 174  */
 175 void ipv6_netfilter_fini(void)
 176 {
 177         nf_unregister_afinfo(&nf_ip6_afinfo);
 178 }