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 <linux/export.h>
   7 #include <net/dst.h>
   8 #include <net/ipv6.h>
   9 #include <net/ip6_route.h>
  10 #include <net/xfrm.h>
  11 #include <net/ip6_checksum.h>
  12 #include <net/netfilter/nf_queue.h>
  13
  14 int ip6_route_me_harder(struct sk_buff *skb)
  15 {
  16         struct net *net = dev_net(skb_dst(skb)->dev);
  17         const struct ipv6hdr *iph = ipv6_hdr(skb);
  18         struct dst_entry *dst;
  19         struct flowi6 fl6 = {
  20                 .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  21                 .flowi6_mark = skb->mark,
  22                 .daddr = iph->daddr,
  23                 .saddr = iph->saddr,
  24         };
  25
  26         dst = ip6_route_output(net, skb->sk, &fl6);
  27         if (dst->error) {
  28                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  29                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  30                 dst_release(dst);
  31                 return -EINVAL;
  32         }
  33
  34         /* Drop old route. */
  35         skb_dst_drop(skb);
  36
  37         skb_dst_set(skb, dst);
  38
  39 #ifdef CONFIG_XFRM
  40         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  41             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  42                 skb_dst_set(skb, NULL);
  43                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0);
  44                 if (IS_ERR(dst))
  45                         return -1;
  46                 skb_dst_set(skb, dst);
  47         }
  48 #endif
  49
  50         return 0;
  51 }
  52 EXPORT_SYMBOL(ip6_route_me_harder);
  53
  54 /*
  55  * Extra routing may needed on local out, as the QUEUE target never
  56  * returns control to the table.
  57  */
  58
  59 struct ip6_rt_info {
  60         struct in6_addr daddr;
  61         struct in6_addr saddr;
  62         u_int32_t mark;
  63 };
  64
  65 static void nf_ip6_saveroute(const struct sk_buff *skb,
  66                              struct nf_queue_entry *entry)
  67 {
  68         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  69
  70         if (entry->hook == NF_INET_LOCAL_OUT) {
  71                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  72
  73                 rt_info->daddr = iph->daddr;
  74                 rt_info->saddr = iph->saddr;
  75                 rt_info->mark = skb->mark;
  76         }
  77 }
  78
  79 static int nf_ip6_reroute(struct sk_buff *skb,
  80                           const struct nf_queue_entry *entry)
  81 {
  82         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  83
  84         if (entry->hook == NF_INET_LOCAL_OUT) {
  85                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  86                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  87                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  88                     skb->mark != rt_info->mark)
  89                         return ip6_route_me_harder(skb);
  90         }
  91         return 0;
  92 }
  93
  94 static int nf_ip6_route(struct net *net, struct dst_entry **dst,
  95                         struct flowi *fl, bool strict)
  96 {
  97         static const struct ipv6_pinfo fake_pinfo;
  98         static const struct inet_sock fake_sk = {
  99                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
 100                 .sk.sk_bound_dev_if = 1,
 101                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 102         };
 103         const void *sk = strict ? &fake_sk : NULL;
 104         struct dst_entry *result;
 105         int err;
 106
 107         result = ip6_route_output(net, sk, &fl->u.ip6);
 108         err = result->error;
 109         if (err)
 110                 dst_release(result);
 111         else
 112                 *dst = result;
 113         return err;
 114 }
 115
 116 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 117                              unsigned int dataoff, u_int8_t protocol)
 118 {
 119         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 120         __sum16 csum = 0;
 121
 122         switch (skb->ip_summed) {
 123         case CHECKSUM_COMPLETE:
 124                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 125                         break;
 126                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 127                                      skb->len - dataoff, protocol,
 128                                      csum_sub(skb->csum,
 129                                               skb_checksum(skb, 0,
 130                                                            dataoff, 0)))) {
 131                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 132                         break;
 133                 }
 134                 /* fall through */
 135         case CHECKSUM_NONE:
 136                 skb->csum = ~csum_unfold(
 137                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 138                                              skb->len - dataoff,
 139                                              protocol,
 140                                              csum_sub(0,
 141                                                       skb_checksum(skb, 0,
 142                                                                    dataoff, 0))));
 143                 csum = __skb_checksum_complete(skb);
 144         }
 145         return csum;
 146 }
 147 EXPORT_SYMBOL(nf_ip6_checksum);
 148
 149 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 150                                        unsigned int dataoff, unsigned int len,
 151                                        u_int8_t protocol)
 152 {
 153         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 154         __wsum hsum;
 155         __sum16 csum = 0;
 156
 157         switch (skb->ip_summed) {
 158         case CHECKSUM_COMPLETE:
 159                 if (len == skb->len - dataoff)
 160                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 161                 /* fall through */
 162         case CHECKSUM_NONE:
 163                 hsum = skb_checksum(skb, 0, dataoff, 0);
 164                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 165                                                          &ip6h->daddr,
 166                                                          skb->len - dataoff,
 167                                                          protocol,
 168                                                          csum_sub(0, hsum)));
 169                 skb->ip_summed = CHECKSUM_NONE;
 170                 return __skb_checksum_complete_head(skb, dataoff + len);
 171         }
 172         return csum;
 173 };
 174
 175 static const struct nf_afinfo nf_ip6_afinfo = {
 176         .family                 = AF_INET6,
 177         .checksum               = nf_ip6_checksum,
 178         .checksum_partial       = nf_ip6_checksum_partial,
 179         .route                  = nf_ip6_route,
 180         .saveroute              = nf_ip6_saveroute,
 181         .reroute                = nf_ip6_reroute,
 182         .route_key_size         = sizeof(struct ip6_rt_info),
 183 };
 184
 185 int __init ipv6_netfilter_init(void)
 186 {
 187         return nf_register_afinfo(&nf_ip6_afinfo);
 188 }
 189
 190 /* This can be called from inet6_init() on errors, so it cannot
 191  * be marked __exit. -DaveM
 192  */
 193 void ipv6_netfilter_fini(void)
 194 {
 195         nf_unregister_afinfo(&nf_ip6_afinfo);
 196 }