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5b1158e9 JK |
1 | /* (C) 1999-2001 Paul `Rusty' Russell |
2 | * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.org> | |
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 | ||
9 | #include <linux/types.h> | |
10 | #include <linux/init.h> | |
11 | #include <linux/ip.h> | |
12 | #include <linux/icmp.h> | |
13 | ||
14 | #include <linux/netfilter.h> | |
15 | #include <net/netfilter/nf_nat.h> | |
16 | #include <net/netfilter/nf_nat_core.h> | |
17 | #include <net/netfilter/nf_nat_rule.h> | |
18 | #include <net/netfilter/nf_nat_protocol.h> | |
19 | ||
20 | static int | |
21 | icmp_in_range(const struct nf_conntrack_tuple *tuple, | |
22 | enum nf_nat_manip_type maniptype, | |
23 | const union nf_conntrack_man_proto *min, | |
24 | const union nf_conntrack_man_proto *max) | |
25 | { | |
26 | return ntohs(tuple->src.u.icmp.id) >= ntohs(min->icmp.id) && | |
27 | ntohs(tuple->src.u.icmp.id) <= ntohs(max->icmp.id); | |
28 | } | |
29 | ||
30 | static int | |
31 | icmp_unique_tuple(struct nf_conntrack_tuple *tuple, | |
32 | const struct nf_nat_range *range, | |
33 | enum nf_nat_manip_type maniptype, | |
34 | const struct nf_conn *ct) | |
35 | { | |
36 | static u_int16_t id; | |
37 | unsigned int range_size; | |
38 | unsigned int i; | |
39 | ||
40 | range_size = ntohs(range->max.icmp.id) - ntohs(range->min.icmp.id) + 1; | |
41 | /* If no range specified... */ | |
42 | if (!(range->flags & IP_NAT_RANGE_PROTO_SPECIFIED)) | |
43 | range_size = 0xFFFF; | |
44 | ||
45 | for (i = 0; i < range_size; i++, id++) { | |
46 | tuple->src.u.icmp.id = htons(ntohs(range->min.icmp.id) + | |
e905a9ed | 47 | (id % range_size)); |
5b1158e9 JK |
48 | if (!nf_nat_used_tuple(tuple, ct)) |
49 | return 1; | |
50 | } | |
51 | return 0; | |
52 | } | |
53 | ||
54 | static int | |
55 | icmp_manip_pkt(struct sk_buff **pskb, | |
56 | unsigned int iphdroff, | |
57 | const struct nf_conntrack_tuple *tuple, | |
58 | enum nf_nat_manip_type maniptype) | |
59 | { | |
60 | struct iphdr *iph = (struct iphdr *)((*pskb)->data + iphdroff); | |
61 | struct icmphdr *hdr; | |
62 | unsigned int hdroff = iphdroff + iph->ihl*4; | |
63 | ||
64 | if (!skb_make_writable(pskb, hdroff + sizeof(*hdr))) | |
65 | return 0; | |
66 | ||
67 | hdr = (struct icmphdr *)((*pskb)->data + hdroff); | |
68 | nf_proto_csum_replace2(&hdr->checksum, *pskb, | |
69 | hdr->un.echo.id, tuple->src.u.icmp.id, 0); | |
70 | hdr->un.echo.id = tuple->src.u.icmp.id; | |
71 | return 1; | |
72 | } | |
73 | ||
74 | struct nf_nat_protocol nf_nat_protocol_icmp = { | |
75 | .name = "ICMP", | |
76 | .protonum = IPPROTO_ICMP, | |
77 | .me = THIS_MODULE, | |
78 | .manip_pkt = icmp_manip_pkt, | |
79 | .in_range = icmp_in_range, | |
80 | .unique_tuple = icmp_unique_tuple, | |
81 | #if defined(CONFIG_IP_NF_CONNTRACK_NETLINK) || \ | |
82 | defined(CONFIG_IP_NF_CONNTRACK_NETLINK_MODULE) | |
83 | .range_to_nfattr = nf_nat_port_range_to_nfattr, | |
84 | .nfattr_to_range = nf_nat_port_nfattr_to_range, | |
85 | #endif | |
86 | }; |