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869f37d8 PM |
1 | /* IRC extension for TCP NAT alteration. |
2 | * | |
3 | * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> | |
4 | * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
5 | * based on a copy of RR's ip_nat_ftp.c | |
6 | * | |
7 | * This program is free software; you can redistribute it and/or | |
8 | * modify it under the terms of the GNU General Public License | |
9 | * as published by the Free Software Foundation; either version | |
10 | * 2 of the License, or (at your option) any later version. | |
11 | */ | |
12 | ||
13 | #include <linux/module.h> | |
14 | #include <linux/moduleparam.h> | |
15 | #include <linux/tcp.h> | |
16 | #include <linux/kernel.h> | |
17 | ||
18 | #include <net/netfilter/nf_nat.h> | |
19 | #include <net/netfilter/nf_nat_helper.h> | |
869f37d8 PM |
20 | #include <net/netfilter/nf_conntrack_helper.h> |
21 | #include <net/netfilter/nf_conntrack_expect.h> | |
22 | #include <linux/netfilter/nf_conntrack_irc.h> | |
23 | ||
869f37d8 PM |
24 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); |
25 | MODULE_DESCRIPTION("IRC (DCC) NAT helper"); | |
26 | MODULE_LICENSE("GPL"); | |
27 | MODULE_ALIAS("ip_nat_irc"); | |
28 | ||
3db05fea | 29 | static unsigned int help(struct sk_buff *skb, |
869f37d8 | 30 | enum ip_conntrack_info ctinfo, |
051966c0 | 31 | unsigned int protoff, |
869f37d8 PM |
32 | unsigned int matchoff, |
33 | unsigned int matchlen, | |
34 | struct nf_conntrack_expect *exp) | |
35 | { | |
36 | char buffer[sizeof("4294967296 65635")]; | |
2690d97a DB |
37 | struct nf_conn *ct = exp->master; |
38 | union nf_inet_addr newaddr; | |
869f37d8 PM |
39 | u_int16_t port; |
40 | unsigned int ret; | |
41 | ||
869f37d8 | 42 | /* Reply comes from server. */ |
2690d97a DB |
43 | newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3; |
44 | ||
869f37d8 PM |
45 | exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; |
46 | exp->dir = IP_CT_DIR_REPLY; | |
47 | exp->expectfn = nf_nat_follow_master; | |
48 | ||
49 | /* Try to get same port: if not, try to change it. */ | |
50 | for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { | |
5b92b61f PNA |
51 | int ret; |
52 | ||
869f37d8 | 53 | exp->tuple.dst.u.tcp.port = htons(port); |
5b92b61f PNA |
54 | ret = nf_ct_expect_related(exp); |
55 | if (ret == 0) | |
56 | break; | |
57 | else if (ret != -EBUSY) { | |
58 | port = 0; | |
869f37d8 | 59 | break; |
5b92b61f | 60 | } |
869f37d8 PM |
61 | } |
62 | ||
b20ab9cc | 63 | if (port == 0) { |
2690d97a | 64 | nf_ct_helper_log(skb, ct, "all ports in use"); |
869f37d8 | 65 | return NF_DROP; |
b20ab9cc | 66 | } |
869f37d8 | 67 | |
2690d97a DB |
68 | /* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27 |
69 | * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28 | |
70 | * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26 | |
71 | * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26 | |
72 | * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27 | |
73 | * | |
74 | * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits, | |
75 | * 255.255.255.255==4294967296, 10 digits) | |
76 | * P: bound port (min 1 d, max 5d (65635)) | |
77 | * F: filename (min 1 d ) | |
78 | * S: size (min 1 d ) | |
79 | * 0x01, \n: terminators | |
80 | */ | |
81 | /* AAA = "us", ie. where server normally talks to. */ | |
82 | snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port); | |
83 | pr_debug("nf_nat_irc: inserting '%s' == %pI4, port %u\n", | |
84 | buffer, &newaddr.ip, port); | |
85 | ||
86 | ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff, | |
87 | matchlen, buffer, strlen(buffer)); | |
b20ab9cc | 88 | if (ret != NF_ACCEPT) { |
2690d97a | 89 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
6823645d | 90 | nf_ct_unexpect_related(exp); |
b20ab9cc | 91 | } |
2690d97a | 92 | |
869f37d8 PM |
93 | return ret; |
94 | } | |
95 | ||
96 | static void __exit nf_nat_irc_fini(void) | |
97 | { | |
a9b3cd7f | 98 | RCU_INIT_POINTER(nf_nat_irc_hook, NULL); |
869f37d8 PM |
99 | synchronize_rcu(); |
100 | } | |
101 | ||
102 | static int __init nf_nat_irc_init(void) | |
103 | { | |
d1332e0a | 104 | BUG_ON(nf_nat_irc_hook != NULL); |
a9b3cd7f | 105 | RCU_INIT_POINTER(nf_nat_irc_hook, help); |
869f37d8 PM |
106 | return 0; |
107 | } | |
108 | ||
109 | /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */ | |
110 | static int warn_set(const char *val, struct kernel_param *kp) | |
111 | { | |
112 | printk(KERN_INFO KBUILD_MODNAME | |
113 | ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n"); | |
114 | return 0; | |
115 | } | |
116 | module_param_call(ports, warn_set, NULL, NULL, 0); | |
117 | ||
118 | module_init(nf_nat_irc_init); | |
119 | module_exit(nf_nat_irc_fini); |