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->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
  29 #ifdef CONFIG_XFRM
  30         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  31             xfrm_decode_session(skb, &fl, AF_INET6) == 0)
  32                 if (xfrm_lookup(net, &skb->dst, &fl, skb->sk, 0))
  33                         return -1;
  34 #endif
  35
  36         if (dst->error) {
  37                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  38                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  39                 dst_release(dst);
  40                 return -EINVAL;
  41         }
  42
  43         /* Drop old route. */
  44         dst_release(skb->dst);
  45
  46         skb->dst = dst;
  47         return 0;
  48 }
  49 EXPORT_SYMBOL(ip6_route_me_harder);
  50
  51 /*
  52  * Extra routing may needed on local out, as the QUEUE target never
  53  * returns control to the table.
  54  */
  55
  56 struct ip6_rt_info {
  57         struct in6_addr daddr;
  58         struct in6_addr saddr;
  59         u_int32_t mark;
  60 };
  61
  62 static void nf_ip6_saveroute(const struct sk_buff *skb,
  63                              struct nf_queue_entry *entry)
  64 {
  65         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  66
  67         if (entry->hook == NF_INET_LOCAL_OUT) {
  68                 struct ipv6hdr *iph = ipv6_hdr(skb);
  69
  70                 rt_info->daddr = iph->daddr;
  71                 rt_info->saddr = iph->saddr;
  72                 rt_info->mark = skb->mark;
  73         }
  74 }
  75
  76 static int nf_ip6_reroute(struct sk_buff *skb,
  77                           const struct nf_queue_entry *entry)
  78 {
  79         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  80
  81         if (entry->hook == NF_INET_LOCAL_OUT) {
  82                 struct ipv6hdr *iph = ipv6_hdr(skb);
  83                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  84                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  85                     skb->mark != rt_info->mark)
  86                         return ip6_route_me_harder(skb);
  87         }
  88         return 0;
  89 }
  90
  91 static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
  92 {
  93         *dst = ip6_route_output(&init_net, NULL, fl);
  94         return (*dst)->error;
  95 }
  96
  97 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  98                              unsigned int dataoff, u_int8_t protocol)
  99 {
 100         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 101         __sum16 csum = 0;
 102
 103         switch (skb->ip_summed) {
 104         case CHECKSUM_COMPLETE:
 105                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 106                         break;
 107                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 108                                      skb->len - dataoff, protocol,
 109                                      csum_sub(skb->csum,
 110                                               skb_checksum(skb, 0,
 111                                                            dataoff, 0)))) {
 112                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 113                         break;
 114                 }
 115                 /* fall through */
 116         case CHECKSUM_NONE:
 117                 skb->csum = ~csum_unfold(
 118                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 119                                              skb->len - dataoff,
 120                                              protocol,
 121                                              csum_sub(0,
 122                                                       skb_checksum(skb, 0,
 123                                                                    dataoff, 0))));
 124                 csum = __skb_checksum_complete(skb);
 125         }
 126         return csum;
 127 }
 128 EXPORT_SYMBOL(nf_ip6_checksum);
 129
 130 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 131                                        unsigned int dataoff, unsigned int len,
 132                                        u_int8_t protocol)
 133 {
 134         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 135         __wsum hsum;
 136         __sum16 csum = 0;
 137
 138         switch (skb->ip_summed) {
 139         case CHECKSUM_COMPLETE:
 140                 if (len == skb->len - dataoff)
 141                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 142                 /* fall through */
 143         case CHECKSUM_NONE:
 144                 hsum = skb_checksum(skb, 0, dataoff, 0);
 145                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 146                                                          &ip6h->daddr,
 147                                                          skb->len - dataoff,
 148                                                          protocol,
 149                                                          csum_sub(0, hsum)));
 150                 skb->ip_summed = CHECKSUM_NONE;
 151                 csum = __skb_checksum_complete_head(skb, dataoff + len);
 152                 if (!csum)
 153                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 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 }