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
icmpv6_in_range(const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype,const union nf_conntrack_man_proto * min,const union nf_conntrack_man_proto * max)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
icmpv6_unique_tuple(const struct nf_nat_l3proto * l3proto,struct nf_conntrack_tuple * tuple,const struct nf_nat_range * range,enum nf_nat_manip_type maniptype,const struct nf_conn * ct)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
icmpv6_manip_pkt(struct sk_buff * skb,const struct nf_nat_l3proto * l3proto,unsigned int iphdroff,unsigned int hdroff,const struct nf_conntrack_tuple * tuple,enum nf_nat_manip_type maniptype)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 };
91