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 sock *sk_partial, struct sk_buff *skb)
  21 {
  22         const struct ipv6hdr *iph = ipv6_hdr(skb);
  23         struct sock *sk = sk_to_full_sk(sk_partial);
  24         unsigned int hh_len;
  25         struct dst_entry *dst;
  26         int strict = (ipv6_addr_type(&iph->daddr) &
  27                       (IPV6_ADDR_MULTICAST | IPV6_ADDR_LINKLOCAL));
  28         struct flowi6 fl6 = {
  29                 .flowi6_oif = sk && sk->sk_bound_dev_if ? sk->sk_bound_dev_if :
  30                         strict ? skb_dst(skb)->dev->ifindex : 0,
  31                 .flowi6_mark = skb->mark,
  32                 .flowi6_uid = sock_net_uid(net, sk),
  33                 .daddr = iph->daddr,
  34                 .saddr = iph->saddr,
  35         };
  36         int err;
  37
  38         dst = ip6_route_output(net, sk, &fl6);
  39         err = dst->error;
  40         if (err) {
  41                 IP6_INC_STATS(net, ip6_dst_idev(dst), IPSTATS_MIB_OUTNOROUTES);
  42                 net_dbg_ratelimited("ip6_route_me_harder: No more route\n");
  43                 dst_release(dst);
  44                 return err;
  45         }
  46
  47         /* Drop old route. */
  48         skb_dst_drop(skb);
  49
  50         skb_dst_set(skb, dst);
  51
  52 #ifdef CONFIG_XFRM
  53         if (!(IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED) &&
  54             xfrm_decode_session(skb, flowi6_to_flowi(&fl6), AF_INET6) == 0) {
  55                 skb_dst_set(skb, NULL);
  56                 dst = xfrm_lookup(net, dst, flowi6_to_flowi(&fl6), sk, 0);
  57                 if (IS_ERR(dst))
  58                         return PTR_ERR(dst);
  59                 skb_dst_set(skb, dst);
  60         }
  61 #endif
  62
  63         /* Change in oif may mean change in hh_len. */
  64         hh_len = skb_dst(skb)->dev->hard_header_len;
  65         if (skb_headroom(skb) < hh_len &&
  66             pskb_expand_head(skb, HH_DATA_ALIGN(hh_len - skb_headroom(skb)),
  67                              0, GFP_ATOMIC))
  68                 return -ENOMEM;
  69
  70         return 0;
  71 }
  72 EXPORT_SYMBOL(ip6_route_me_harder);
  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->state.hook == NF_INET_LOCAL_OUT) {
  80                 const 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                     skb->mark != rt_info->mark)
  84                         return ip6_route_me_harder(entry->state.net, entry->state.sk, skb);
  85         }
  86         return 0;
  87 }
  88
  89 static int nf_ip6_route(struct net *net, struct dst_entry **dst,
  90                         struct flowi *fl, bool strict)
  91 {
  92         static const struct ipv6_pinfo fake_pinfo;
  93         static const struct inet_sock fake_sk = {
  94                 /* makes ip6_route_output set RT6_LOOKUP_F_IFACE: */
  95                 .sk.sk_bound_dev_if = 1,
  96                 .pinet6 = (struct ipv6_pinfo *) &fake_pinfo,
  97         };
  98         const void *sk = strict ? &fake_sk : NULL;
  99         struct dst_entry *result;
 100         int err;
 101
 102         result = ip6_route_output(net, sk, &fl->u.ip6);
 103         err = result->error;
 104         if (err)
 105                 dst_release(result);
 106         else
 107                 *dst = result;
 108         return err;
 109 }
 110
 111 static const struct nf_ipv6_ops ipv6ops = {
 112         .chk_addr               = ipv6_chk_addr,
 113         .route_input            = ip6_route_input,
 114         .fragment               = ip6_fragment,
 115         .route                  = nf_ip6_route,
 116         .reroute                = nf_ip6_reroute,
 117 };
 118
 119 int __init ipv6_netfilter_init(void)
 120 {
 121         RCU_INIT_POINTER(nf_ipv6_ops, &ipv6ops);
 122         return 0;
 123 }
 124
 125 /* This can be called from inet6_init() on errors, so it cannot
 126  * be marked __exit. -DaveM
 127  */
 128 void ipv6_netfilter_fini(void)
 129 {
 130         RCU_INIT_POINTER(nf_ipv6_ops, NULL);
 131 }