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 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                 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                 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 dst_entry **dst, struct flowi *fl)
  94 {
  95         *dst = ip6_route_output(&init_net, NULL, &fl->u.ip6);
  96         return (*dst)->error;
  97 }
  98
  99 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 100                              unsigned int dataoff, u_int8_t protocol)
 101 {
 102         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 103         __sum16 csum = 0;
 104
 105         switch (skb->ip_summed) {
 106         case CHECKSUM_COMPLETE:
 107                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 108                         break;
 109                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 110                                      skb->len - dataoff, protocol,
 111                                      csum_sub(skb->csum,
 112                                               skb_checksum(skb, 0,
 113                                                            dataoff, 0)))) {
 114                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 115                         break;
 116                 }
 117                 /* fall through */
 118         case CHECKSUM_NONE:
 119                 skb->csum = ~csum_unfold(
 120                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 121                                              skb->len - dataoff,
 122                                              protocol,
 123                                              csum_sub(0,
 124                                                       skb_checksum(skb, 0,
 125                                                                    dataoff, 0))));
 126                 csum = __skb_checksum_complete(skb);
 127         }
 128         return csum;
 129 }
 130 EXPORT_SYMBOL(nf_ip6_checksum);
 131
 132 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 133                                        unsigned int dataoff, unsigned int len,
 134                                        u_int8_t protocol)
 135 {
 136         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 137         __wsum hsum;
 138         __sum16 csum = 0;
 139
 140         switch (skb->ip_summed) {
 141         case CHECKSUM_COMPLETE:
 142                 if (len == skb->len - dataoff)
 143                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 144                 /* fall through */
 145         case CHECKSUM_NONE:
 146                 hsum = skb_checksum(skb, 0, dataoff, 0);
 147                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 148                                                          &ip6h->daddr,
 149                                                          skb->len - dataoff,
 150                                                          protocol,
 151                                                          csum_sub(0, hsum)));
 152                 skb->ip_summed = CHECKSUM_NONE;
 153                 return __skb_checksum_complete_head(skb, dataoff + len);
 154         }
 155         return csum;
 156 };
 157
 158 static const struct nf_afinfo nf_ip6_afinfo = {
 159         .family                 = AF_INET6,
 160         .checksum               = nf_ip6_checksum,
 161         .checksum_partial       = nf_ip6_checksum_partial,
 162         .route                  = nf_ip6_route,
 163         .saveroute              = nf_ip6_saveroute,
 164         .reroute                = nf_ip6_reroute,
 165         .route_key_size         = sizeof(struct ip6_rt_info),
 166 };
 167
 168 int __init ipv6_netfilter_init(void)
 169 {
 170         return nf_register_afinfo(&nf_ip6_afinfo);
 171 }
 172
 173 /* This can be called from inet6_init() on errors, so it cannot
 174  * be marked __exit. -DaveM
 175  */
 176 void ipv6_netfilter_fini(void)
 177 {
 178         nf_unregister_afinfo(&nf_ip6_afinfo);
 179 }