net/ipv6/netfilter/nf_nat_proto_icmpv6.c

   1 /*
   2  * Copyright (c) 2011 Patrick Mchardy <kaber@trash.net>
   3  *
   4  * This program is free software; you can redistribute it and/or modify
   5  * it under the terms of the GNU General Public License version 2 as
   6  * published by the Free Software Foundation.
   7  *
   8  * Based on Rusty Russell's IPv4 ICMP NAT code. Development of IPv6
   9  * NAT funded by Astaro.
  10  */
  11
  12 #include <linux/types.h>
  13 #include <linux/init.h>
  14 #include <linux/icmpv6.h>
  15
  16 #include <linux/netfilter.h>
  17 #include <net/netfilter/nf_nat.h>
  18 #include <net/netfilter/nf_nat_core.h>
  19 #include <net/netfilter/nf_nat_l3proto.h>
  20 #include <net/netfilter/nf_nat_l4proto.h>
  21
  22 static bool
  23 icmpv6_in_range(const struct nf_conntrack_tuple *tuple,
  24                 enum nf_nat_manip_type maniptype,
  25                 const union nf_conntrack_man_proto *min,
  26                 const union nf_conntrack_man_proto *max)
  27 {
  28         return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) &&
  29                ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id);
  30 }
  31
  32 static void
  33 icmpv6_unique_tuple(const struct nf_nat_l3proto *l3proto,
  34                     struct nf_conntrack_tuple *tuple,
  35                     const struct nf_nat_range *range,
  36                     enum nf_nat_manip_type maniptype,
  37                     const struct nf_conn *ct)
  38 {
  39         static u16 id;
  40         unsigned int range_size;
  41         unsigned int i;
  42
  43         range_size = ntohs(range->max_proto.icmp.id) -
  44                      ntohs(range->min_proto.icmp.id) + 1;
  45
  46         if (!(range->flags & NF_NAT_RANGE_PROTO_SPECIFIED))
  47                 range_size = 0xffff;
  48
  49         for (i = 0; ; ++id) {
  50                 tuple->src.u.icmp.id = htons(ntohs(range->min_proto.icmp.id) +
  51                                              (id % range_size));
  52                 if (++i == range_size || !nf_nat_used_tuple(tuple, ct))
  53                         return;
  54         }
  55 }
  56
  57 static bool
  58 icmpv6_manip_pkt(struct sk_buff *skb,
  59                  const struct nf_nat_l3proto *l3proto,
  60                  unsigned int iphdroff, unsigned int hdroff,
  61                  const struct nf_conntrack_tuple *tuple,
  62                  enum nf_nat_manip_type maniptype)
  63 {
  64         struct icmp6hdr *hdr;
  65
  66         if (!skb_make_writable(skb, hdroff + sizeof(*hdr)))
  67                 return false;
  68
  69         hdr = (struct icmp6hdr *)(skb->data + hdroff);
  70         l3proto->csum_update(skb, iphdroff, &hdr->icmp6_cksum,
  71                              tuple, maniptype);
  72         if (hdr->icmp6_type == ICMPV6_ECHO_REQUEST ||
  73             hdr->icmp6_type == ICMPV6_ECHO_REPLY) {
  74                 inet_proto_csum_replace2(&hdr->icmp6_cksum, skb,
  75                                          hdr->icmp6_identifier,
  76                                          tuple->src.u.icmp.id, false);
  77                 hdr->icmp6_identifier = tuple->src.u.icmp.id;
  78         }
  79         return true;
  80 }
  81
  82 const struct nf_nat_l4proto nf_nat_l4proto_icmpv6 = {
  83         .l4proto                = IPPROTO_ICMPV6,
  84         .manip_pkt              = icmpv6_manip_pkt,
  85         .in_range               = icmpv6_in_range,
  86         .unique_tuple           = icmpv6_unique_tuple,
  87 #if IS_ENABLED(CONFIG_NF_CT_NETLINK)
  88         .nlattr_to_range        = nf_nat_l4proto_nlattr_to_range,
  89 #endif
  90 };