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         unsigned int hh_len;
  19         struct dst_entry *dst;
  20         struct flowi6 fl6 = {
  21                 .flowi6_oif = skb->sk ? skb->sk->sk_bound_dev_if : 0,
  22                 .flowi6_mark = skb->mark,
  23                 .daddr = iph->daddr,
  24                 .saddr = iph->saddr,
  25         };
  26
  27         dst = ip6_route_output(net, skb->sk, &fl6);
  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, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  43                 skb_dst_set(skb, NULL);
  44                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), skb->sk, 0);
  45                 if (IS_ERR(dst))
  46                         return -1;
  47                 skb_dst_set(skb, dst);
  48         }
  49 #endif
  50
  51         /* Change in oif may mean change in hh_len. */
  52         hh_len = skb_dst(skb)->dev->hard_header_len;
  53         if (skb_headroom(skb) < hh_len &&
  54             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  55                              0, GFP_ATOMIC))
  56                 return -1;
  57
  58         return 0;
  59 }
  60 EXPORT_SYMBOL(ip6_route_me_harder);
  61
  62 /*
  63  * Extra routing may needed on local out, as the QUEUE target never
  64  * returns control to the table.
  65  */
  66
  67 struct ip6_rt_info {
  68         struct in6_addr daddr;
  69         struct in6_addr saddr;
  70         u_int32_t mark;
  71 };
  72
  73 static void nf_ip6_saveroute(const struct sk_buff *skb,
  74                              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                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  80
  81                 rt_info->daddr = iph->daddr;
  82                 rt_info->saddr = iph->saddr;
  83                 rt_info->mark = skb->mark;
  84         }
  85 }
  86
  87 static int nf_ip6_reroute(struct sk_buff *skb,
  88                           const struct nf_queue_entry *entry)
  89 {
  90         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  91
  92         if (entry->hook == NF_INET_LOCAL_OUT) {
  93                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  94                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  95                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  96                     skb->mark != rt_info->mark)
  97                         return ip6_route_me_harder(skb);
  98         }
  99         return 0;
 100 }
 101
 102 static int nf_ip6_route(struct net *net, struct dst_entry **dst,
 103                         struct flowi *fl, bool strict)
 104 {
 105         static const struct ipv6_pinfo fake_pinfo;
 106         static const struct inet_sock fake_sk = {
 107                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
 108                 .sk.sk_bound_dev_if = 1,
 109                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
 110         };
 111         const void *sk = strict ? &fake_sk : NULL;
 112         struct dst_entry *result;
 113         int err;
 114
 115         result = ip6_route_output(net, sk, &fl->u.ip6);
 116         err = result->error;
 117         if (err)
 118                 dst_release(result);
 119         else
 120                 *dst = result;
 121         return err;
 122 }
 123
 124 __sum16 nf_ip6_checksum(struct sk_buff *skb, unsigned int hook,
 125                              unsigned int dataoff, u_int8_t protocol)
 126 {
 127         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 128         __sum16 csum = 0;
 129
 130         switch (skb->ip_summed) {
 131         case CHECKSUM_COMPLETE:
 132                 if (hook != NF_INET_PRE_ROUTING && hook != NF_INET_LOCAL_IN)
 133                         break;
 134                 if (!csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 135                                      skb->len - dataoff, protocol,
 136                                      csum_sub(skb->csum,
 137                                               skb_checksum(skb, 0,
 138                                                            dataoff, 0)))) {
 139                         skb->ip_summed = CHECKSUM_UNNECESSARY;
 140                         break;
 141                 }
 142                 /* fall through */
 143         case CHECKSUM_NONE:
 144                 skb->csum = ~csum_unfold(
 145                                 csum_ipv6_magic(&ip6h->saddr, &ip6h->daddr,
 146                                              skb->len - dataoff,
 147                                              protocol,
 148                                              csum_sub(0,
 149                                                       skb_checksum(skb, 0,
 150                                                                    dataoff, 0))));
 151                 csum = __skb_checksum_complete(skb);
 152         }
 153         return csum;
 154 }
 155 EXPORT_SYMBOL(nf_ip6_checksum);
 156
 157 static __sum16 nf_ip6_checksum_partial(struct sk_buff *skb, unsigned int hook,
 158                                        unsigned int dataoff, unsigned int len,
 159                                        u_int8_t protocol)
 160 {
 161         const struct ipv6hdr *ip6h = ipv6_hdr(skb);
 162         __wsum hsum;
 163         __sum16 csum = 0;
 164
 165         switch (skb->ip_summed) {
 166         case CHECKSUM_COMPLETE:
 167                 if (len == skb->len - dataoff)
 168                         return nf_ip6_checksum(skb, hook, dataoff, protocol);
 169                 /* fall through */
 170         case CHECKSUM_NONE:
 171                 hsum = skb_checksum(skb, 0, dataoff, 0);
 172                 skb->csum = ~csum_unfold(csum_ipv6_magic(&ip6h->saddr,
 173                                                          &ip6h->daddr,
 174                                                          skb->len - dataoff,
 175                                                          protocol,
 176                                                          csum_sub(0, hsum)));
 177                 skb->ip_summed = CHECKSUM_NONE;
 178                 return __skb_checksum_complete_head(skb, dataoff + len);
 179         }
 180         return csum;
 181 };
 182
 183 static const struct nf_afinfo nf_ip6_afinfo = {
 184         .family                 = AF_INET6,
 185         .checksum               = nf_ip6_checksum,
 186         .checksum_partial       = nf_ip6_checksum_partial,
 187         .route                  = nf_ip6_route,
 188         .saveroute              = nf_ip6_saveroute,
 189         .reroute                = nf_ip6_reroute,
 190         .route_key_size         = sizeof(struct ip6_rt_info),
 191 };
 192
 193 int __init ipv6_netfilter_init(void)
 194 {
 195         return nf_register_afinfo(&nf_ip6_afinfo);
 196 }
 197
 198 /* This can be called from inet6_init() on errors, so it cannot
 199  * be marked __exit. -DaveM
 200  */
 201 void ipv6_netfilter_fini(void)
 202 {
 203         nf_unregister_afinfo(&nf_ip6_afinfo);
 204 }