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                 .nl_u =
  22                 { .ip6_u =
  23                   { .daddr = iph->daddr,
  24                     .saddr = iph->saddr, } },
  25         };
  26
  27         dst = ip6_route_output(net, skb->sk, &fl);
  28         if (dst->error) {
  29                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  30                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  31                 dst_release(dst);
  32                 return -EINVAL;
  33         }
  34
  35         /* Drop old route. */
  36         skb_dst_drop(skb);
  37
  38         skb_dst_set(skb, dst);
  39
  40 #ifdef CONFIG_XFRM
  41         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  42             xfrm_decode_session(skb, &fl, AF_INET6) == 0) {
  43                 skb_dst_set(skb, NULL);
  44                 if (xfrm_lookup(net, &dst, &fl, skb->sk, 0))
  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                 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                 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 dst_entry **dst, struct flowi *fl)
  95 {
  96         *dst = ip6_route_output(&init_net, NULL, fl);
  97         return (*dst)->error;
  98 }
  99
 100 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 101                              unsigned int dataoff, u_int8_t protocol)
 102 {
 103         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 104         __sum16 csum = 0;
 105
 106         switch (skb->ip_summed) {
 107         case CHECKSUM_COMPLETE:
 108                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 109                         break;
 110                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 111                                      skb->len - dataoff, protocol,
 112                                      csum_sub(skb->csum,
 113                                               skb_checksum(skb, 0,
 114                                                            dataoff, 0)))) {
 115                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 116                         break;
 117                 }
 118                 /* fall through */
 119         case CHECKSUM_NONE:
 120                 skb->csum = ~csum_unfold(
 121                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 122                                              skb->len - dataoff,
 123                                              protocol,
 124                                              csum_sub(0,
 125                                                       skb_checksum(skb, 0,
 126                                                                    dataoff, 0))));
 127                 csum = __skb_checksum_complete(skb);
 128         }
 129         return csum;
 130 }
 131 EXPORT_SYMBOL(nf_ip6_checksum);
 132
 133 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 134                                        unsigned int dataoff, unsigned int len,
 135                                        u_int8_t protocol)
 136 {
 137         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 138         __wsum hsum;
 139         __sum16 csum = 0;
 140
 141         switch (skb->ip_summed) {
 142         case CHECKSUM_COMPLETE:
 143                 if (len == skb->len - dataoff)
 144                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 145                 /* fall through */
 146         case CHECKSUM_NONE:
 147                 hsum = skb_checksum(skb, 0, dataoff, 0);
 148                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 149                                                          &ip6h->daddr,
 150                                                          skb->len - dataoff,
 151                                                          protocol,
 152                                                          csum_sub(0, hsum)));
 153                 skb->ip_summed = CHECKSUM_NONE;
 154                 return __skb_checksum_complete_head(skb, dataoff + len);
 155         }
 156         return csum;
 157 };
 158
 159 static const struct nf_afinfo nf_ip6_afinfo = {
 160         .family                 = AF_INET6,
 161         .checksum               = nf_ip6_checksum,
 162         .checksum_partial       = nf_ip6_checksum_partial,
 163         .route                  = nf_ip6_route,
 164         .saveroute              = nf_ip6_saveroute,
 165         .reroute                = nf_ip6_reroute,
 166         .route_key_size         = sizeof(struct ip6_rt_info),
 167 };
 168
 169 int __init ipv6_netfilter_init(void)
 170 {
 171         return nf_register_afinfo(&nf_ip6_afinfo);
 172 }
 173
 174 /* This can be called from inet6_init() on errors, so it cannot
 175  * be marked __exit. -DaveM
 176  */
 177 void ipv6_netfilter_fini(void)
 178 {
 179         nf_unregister_afinfo(&nf_ip6_afinfo);
 180 }