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         const 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                 const 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                 const 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 net *net, struct dst_entry **dst,
  94                         struct flowi *fl, bool strict)
  95 {
  96         static const struct ipv6_pinfo fake_pinfo;
  97         static const struct inet_sock fake_sk = {
  98                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
  99                 .sk.sk_bound_dev_if = 1,
 100                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 101         };
 102         const void *sk = strict ? &fake_sk : NULL;
 103         struct dst_entry *result;
 104         int err;
 105
 106         result = ip6_route_output(net, sk, &fl->u.ip6);
 107         err = result->error;
 108         if (err)
 109                 dst_release(result);
 110         else
 111                 *dst = result;
 112         return err;
 113 }
 114
 115 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 116                              unsigned int dataoff, u_int8_t protocol)
 117 {
 118         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 119         __sum16 csum = 0;
 120
 121         switch (skb->ip_summed) {
 122         case CHECKSUM_COMPLETE:
 123                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 124                         break;
 125                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 126                                      skb->len - dataoff, protocol,
 127                                      csum_sub(skb->csum,
 128                                               skb_checksum(skb, 0,
 129                                                            dataoff, 0)))) {
 130                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 131                         break;
 132                 }
 133                 /* fall through */
 134         case CHECKSUM_NONE:
 135                 skb->csum = ~csum_unfold(
 136                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 137                                              skb->len - dataoff,
 138                                              protocol,
 139                                              csum_sub(0,
 140                                                       skb_checksum(skb, 0,
 141                                                                    dataoff, 0))));
 142                 csum = __skb_checksum_complete(skb);
 143         }
 144         return csum;
 145 }
 146 EXPORT_SYMBOL(nf_ip6_checksum);
 147
 148 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 149                                        unsigned int dataoff, unsigned int len,
 150                                        u_int8_t protocol)
 151 {
 152         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 153         __wsum hsum;
 154         __sum16 csum = 0;
 155
 156         switch (skb->ip_summed) {
 157         case CHECKSUM_COMPLETE:
 158                 if (len == skb->len - dataoff)
 159                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 160                 /* fall through */
 161         case CHECKSUM_NONE:
 162                 hsum = skb_checksum(skb, 0, dataoff, 0);
 163                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 164                                                          &ip6h->daddr,
 165                                                          skb->len - dataoff,
 166                                                          protocol,
 167                                                          csum_sub(0, hsum)));
 168                 skb->ip_summed = CHECKSUM_NONE;
 169                 return __skb_checksum_complete_head(skb, dataoff + len);
 170         }
 171         return csum;
 172 };
 173
 174 static const struct nf_afinfo nf_ip6_afinfo = {
 175         .family                 = AF_INET6,
 176         .checksum               = nf_ip6_checksum,
 177         .checksum_partial       = nf_ip6_checksum_partial,
 178         .route                  = nf_ip6_route,
 179         .saveroute              = nf_ip6_saveroute,
 180         .reroute                = nf_ip6_reroute,
 181         .route_key_size         = sizeof(struct ip6_rt_info),
 182 };
 183
 184 int __init ipv6_netfilter_init(void)
 185 {
 186         return nf_register_afinfo(&nf_ip6_afinfo);
 187 }
 188
 189 /* This can be called from inet6_init() on errors, so it cannot
 190  * be marked __exit. -DaveM
 191  */
 192 void ipv6_netfilter_fini(void)
 193 {
 194         nf_unregister_afinfo(&nf_ip6_afinfo);
 195 }