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(&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 };
  60
  61 static void nf_ip6_saveroute(const struct sk_buff *skb,
  62                              struct nf_queue_entry *entry)
  63 {
  64         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  65
  66         if (entry->hook == NF_INET_LOCAL_OUT) {
  67                 struct ipv6hdr *iph = ipv6_hdr(skb);
  68
  69                 rt_info->daddr = iph->daddr;
  70                 rt_info->saddr = iph->saddr;
  71         }
  72 }
  73
  74 static int nf_ip6_reroute(struct sk_buff *skb,
  75                           const struct nf_queue_entry *entry)
  76 {
  77         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  78
  79         if (entry->hook == NF_INET_LOCAL_OUT) {
  80                 struct ipv6hdr *iph = ipv6_hdr(skb);
  81                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  82                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr))
  83                         return ip6_route_me_harder(skb);
  84         }
  85         return 0;
  86 }
  87
  88 static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
  89 {
  90         *dst = ip6_route_output(&init_net, NULL, fl);
  91         return (*dst)->error;
  92 }
  93
  94 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  95                              unsigned int dataoff, u_int8_t protocol)
  96 {
  97         struct ipv6hdr *ip6h = ipv6_hdr(skb);
  98         __sum16 csum = 0;
  99
 100         switch (skb->ip_summed) {
 101         case CHECKSUM_COMPLETE:
 102                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 103                         break;
 104                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 105                                      skb->len - dataoff, protocol,
 106                                      csum_sub(skb->csum,
 107                                               skb_checksum(skb, 0,
 108                                                            dataoff, 0)))) {
 109                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 110                         break;
 111                 }
 112                 /* fall through */
 113         case CHECKSUM_NONE:
 114                 skb->csum = ~csum_unfold(
 115                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 116                                              skb->len - dataoff,
 117                                              protocol,
 118                                              csum_sub(0,
 119                                                       skb_checksum(skb, 0,
 120                                                                    dataoff, 0))));
 121                 csum = __skb_checksum_complete(skb);
 122         }
 123         return csum;
 124 }
 125 EXPORT_SYMBOL(nf_ip6_checksum);
 126
 127 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 128                                        unsigned int dataoff, unsigned int len,
 129                                        u_int8_t protocol)
 130 {
 131         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 132         __wsum hsum;
 133         __sum16 csum = 0;
 134
 135         switch (skb->ip_summed) {
 136         case CHECKSUM_COMPLETE:
 137                 if (len == skb->len - dataoff)
 138                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 139                 /* fall through */
 140         case CHECKSUM_NONE:
 141                 hsum = skb_checksum(skb, 0, dataoff, 0);
 142                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 143                                                          &ip6h->daddr,
 144                                                          skb->len - dataoff,
 145                                                          protocol,
 146                                                          csum_sub(0, hsum)));
 147                 skb->ip_summed = CHECKSUM_NONE;
 148                 csum = __skb_checksum_complete_head(skb, dataoff + len);
 149                 if (!csum)
 150                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 151         }
 152         return csum;
 153 };
 154
 155 static const struct nf_afinfo nf_ip6_afinfo = {
 156         .family                 = AF_INET6,
 157         .checksum               = nf_ip6_checksum,
 158         .checksum_partial       = nf_ip6_checksum_partial,
 159         .route                  = nf_ip6_route,
 160         .saveroute              = nf_ip6_saveroute,
 161         .reroute                = nf_ip6_reroute,
 162         .route_key_size         = sizeof(struct ip6_rt_info),
 163 };
 164
 165 int __init ipv6_netfilter_init(void)
 166 {
 167         return nf_register_afinfo(&nf_ip6_afinfo);
 168 }
 169
 170 /* This can be called from inet6_init() on errors, so it cannot
 171  * be marked __exit. -DaveM
 172  */
 173 void ipv6_netfilter_fini(void)
 174 {
 175         nf_unregister_afinfo(&nf_ip6_afinfo);
 176 }