net/ipv6/netfilter.c

   1 /*
   2  * IPv6 specific functions of netfilter core
   3  *
   4  * Rusty Russell (C) 2000 -- This code is GPL.
   5  * Patrick McHardy (C) 2006-2012
   6  */
   7 #include <linux/kernel.h>
   8 #include <linux/init.h>
   9 #include <linux/ipv6.h>
  10 #include <linux/netfilter.h>
  11 #include <linux/netfilter_ipv6.h>
  12 #include <linux/export.h>
  13 #include <net/addrconf.h>
  14 #include <net/dst.h>
  15 #include <net/ipv6.h>
  16 #include <net/ip6_route.h>
  17 #include <net/xfrm.h>
  18 #include <net/netfilter/nf_queue.h>
  19
  20 int ip6_route_me_harder(struct net *net, struct sk_buff *skb)
  21 {
  22         const struct ipv6hdr *iph = ipv6_hdr(skb);
  23         struct sock *sk = sk_to_full_sk(skb->sk);
  24         unsigned int hh_len;
  25         struct dst_entry *dst;
  26         struct flowi6 fl6 = {
  27                 .flowi6_oif = sk ? sk->sk_bound_dev_if : 0,
  28                 .flowi6_mark = skb->mark,
  29                 .flowi6_uid = sock_net_uid(net, sk),
  30                 .daddr = iph->daddr,
  31                 .saddr = iph->saddr,
  32         };
  33         int err;
  34
  35         dst = ip6_route_output(net, sk, &fl6);
  36         err = dst->error;
  37         if (err) {
  38                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  39                 net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
  40                 dst_release(dst);
  41                 return err;
  42         }
  43
  44         /* Drop old route. */
  45         skb_dst_drop(skb);
  46
  47         skb_dst_set(skb, dst);
  48
  49 #ifdef CONFIG_XFRM
  50         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  51             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  52                 skb_dst_set(skb, NULL);
  53                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
  54                 if (IS_ERR(dst))
  55                         return PTR_ERR(dst);
  56                 skb_dst_set(skb, dst);
  57         }
  58 #endif
  59
  60         /* Change in oif may mean change in hh_len. */
  61         hh_len = skb_dst(skb)->dev->hard_header_len;
  62         if (skb_headroom(skb) < hh_len &&
  63             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  64                              0, GFP_ATOMIC))
  65                 return -ENOMEM;
  66
  67         return 0;
  68 }
  69 EXPORT_SYMBOL(ip6_route_me_harder);
  70
  71 static int nf_ip6_reroute(struct sk_buff *skb,
  72                           const struct nf_queue_entry *entry)
  73 {
  74         struct ip6_rt_info *rt_info = nf_queue_entry_reroute(entry);
  75
  76         if (entry->state.hook == NF_INET_LOCAL_OUT) {
  77                 const struct ipv6hdr *iph = ipv6_hdr(skb);
  78                 if (!ipv6_addr_equal(&iph->daddr, &rt_info->daddr) ||
  79                     !ipv6_addr_equal(&iph->saddr, &rt_info->saddr) ||
  80                     skb->mark != rt_info->mark)
  81                         return ip6_route_me_harder(entry->state.net, skb);
  82         }
  83         return 0;
  84 }
  85
  86 static int nf_ip6_route(struct net *net, struct dst_entry **dst,
  87                         struct flowi *fl, bool strict)
  88 {
  89         static const struct ipv6_pinfo fake_pinfo;
  90         static const struct inet_sock fake_sk = {
  91                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
  92                 .sk.sk_bound_dev_if = 1,
  93                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
  94         };
  95         const void *sk = strict ? &fake_sk : NULL;
  96         struct dst_entry *result;
  97         int err;
  98
  99         result = ip6_route_output(net, sk, &fl->u.ip6);
 100         err = result->error;
 101         if (err)
 102                 dst_release(result);
 103         else
 104                 *dst = result;
 105         return err;
 106 }
 107
 108 static const struct nf_ipv6_ops ipv6ops = {
 109         .chk_addr               = ipv6_chk_addr,
 110         .route_input            = ip6_route_input,
 111         .fragment               = ip6_fragment,
 112         .route                  = nf_ip6_route,
 113         .reroute                = nf_ip6_reroute,
 114 };
 115
 116 int __init ipv6_netfilter_init(void)
 117 {
 118         RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
 119         return 0;
 120 }
 121
 122 /* This can be called from inet6_init() on errors, so it cannot
 123  * be marked __exit. -DaveM
 124  */
 125 void ipv6_netfilter_fini(void)
 126 {
 127         RCU_INIT_POINTER(nf_ipv6_ops, NULL);
 128 }