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 ipv6hdr *iph = ipv6_hdr(skb);
  16         struct dst_entry *dst;
  17         struct flowi fl = {
  18                 .oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  19                 .mark = skb->mark,
  20                 .nl_u =
  21                 { .ip6_u =
  22                   { .daddr = iph->daddr,
  23                     .saddr = iph->saddr, } },
  24         };
  25
  26         dst = ip6_route_output(&init_net, skb->sk, &fl);
  27
  28 #ifdef CONFIG_XFRM
  29         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  30             xfrm_decode_session(skb, &fl, AF_INET6) == 0)
  31                 if (xfrm_lookup(&skb->dst, &fl, skb->sk, 0))
  32                         return -1;
  33 #endif
  34
  35         if (dst->error) {
  36                 IP6_INC_STATS(ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  37                 LIMIT_NETDEBUG(KERN_DEBUG "ip6_route_me_harder: No more route.\n");
  38                 dst_release(dst);
  39                 return -EINVAL;
  40         }
  41
  42         /* Drop old route. */
  43         dst_release(skb->dst);
  44
  45         skb->dst = dst;
  46         return 0;
  47 }
  48 EXPORT_SYMBOL(ip6_route_me_harder);
  49
  50 /*
  51  * Extra routing may needed on local out, as the QUEUE target never
  52  * returns control to the table.
  53  */
  54
  55 struct ip6_rt_info {
  56         struct in6_addr daddr;
  57         struct in6_addr saddr;
  58 };
  59
  60 static void nf_ip6_saveroute(const struct sk_buff *skb,
  61                              struct nf_queue_entry *entry)
  62 {
  63         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  64
  65         if (entry->hook == NF_INET_LOCAL_OUT) {
  66                 struct ipv6hdr *iph = ipv6_hdr(skb);
  67
  68                 rt_info->daddr = iph->daddr;
  69                 rt_info->saddr = iph->saddr;
  70         }
  71 }
  72
  73 static int nf_ip6_reroute(struct sk_buff *skb,
  74                           const struct nf_queue_entry *entry)
  75 {
  76         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  77
  78         if (entry->hook == NF_INET_LOCAL_OUT) {
  79                 struct ipv6hdr *iph = ipv6_hdr(skb);
  80                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  81                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr))
  82                         return ip6_route_me_harder(skb);
  83         }
  84         return 0;
  85 }
  86
  87 static int nf_ip6_route(struct dst_entry **dst, struct flowi *fl)
  88 {
  89         *dst = ip6_route_output(&init_net, NULL, fl);
  90         return (*dst)->error;
  91 }
  92
  93 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
  94                              unsigned int dataoff, u_int8_t protocol)
  95 {
  96         struct ipv6hdr *ip6h = ipv6_hdr(skb);
  97         __sum16 csum = 0;
  98
  99         switch (skb->ip_summed) {
 100         case CHECKSUM_COMPLETE:
 101                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 102                         break;
 103                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 104                                      skb->len - dataoff, protocol,
 105                                      csum_sub(skb->csum,
 106                                               skb_checksum(skb, 0,
 107                                                            dataoff, 0)))) {
 108                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 109                         break;
 110                 }
 111                 /* fall through */
 112         case CHECKSUM_NONE:
 113                 skb->csum = ~csum_unfold(
 114                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 115                                              skb->len - dataoff,
 116                                              protocol,
 117                                              csum_sub(0,
 118                                                       skb_checksum(skb, 0,
 119                                                                    dataoff, 0))));
 120                 csum = __skb_checksum_complete(skb);
 121         }
 122         return csum;
 123 }
 124 EXPORT_SYMBOL(nf_ip6_checksum);
 125
 126 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 127                                        unsigned int dataoff, unsigned int len,
 128                                        u_int8_t protocol)
 129 {
 130         struct ipv6hdr *ip6h = ipv6_hdr(skb);
 131         __wsum hsum;
 132         __sum16 csum = 0;
 133
 134         switch (skb->ip_summed) {
 135         case CHECKSUM_COMPLETE:
 136                 if (len == skb->len - dataoff)
 137                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 138                 /* fall through */
 139         case CHECKSUM_NONE:
 140                 hsum = skb_checksum(skb, 0, dataoff, 0);
 141                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 142                                                          &ip6h->daddr,
 143                                                          skb->len - dataoff,
 144                                                          protocol,
 145                                                          csum_sub(0, hsum)));
 146                 skb->ip_summed = CHECKSUM_NONE;
 147                 csum = __skb_checksum_complete_head(skb, dataoff + len);
 148                 if (!csum)
 149                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 150         }
 151         return csum;
 152 };
 153
 154 static const struct nf_afinfo nf_ip6_afinfo = {
 155         .family                 = AF_INET6,
 156         .checksum               = nf_ip6_checksum,
 157         .checksum_partial       = nf_ip6_checksum_partial,
 158         .route                  = nf_ip6_route,
 159         .saveroute              = nf_ip6_saveroute,
 160         .reroute                = nf_ip6_reroute,
 161         .route_key_size         = sizeof(struct ip6_rt_info),
 162 };
 163
 164 int __init ipv6_netfilter_init(void)
 165 {
 166         return nf_register_afinfo(&nf_ip6_afinfo);
 167 }
 168
 169 /* This can be called from inet6_init() on errors, so it cannot
 170  * be marked __exit. -DaveM
 171  */
 172 void ipv6_netfilter_fini(void)
 173 {
 174         nf_unregister_afinfo(&nf_ip6_afinfo);
 175 }