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2874c5fd | 1 | // SPDX-License-Identifier: GPL-2.0-or-later |
869f37d8 PM |
2 | /* IRC extension for TCP NAT alteration. |
3 | * | |
4 | * (C) 2000-2001 by Harald Welte <laforge@gnumonks.org> | |
5 | * (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation | |
6 | * based on a copy of RR's ip_nat_ftp.c | |
869f37d8 PM |
7 | */ |
8 | ||
5191d70f AS |
9 | #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
10 | ||
869f37d8 PM |
11 | #include <linux/module.h> |
12 | #include <linux/moduleparam.h> | |
13 | #include <linux/tcp.h> | |
14 | #include <linux/kernel.h> | |
15 | ||
16 | #include <net/netfilter/nf_nat.h> | |
17 | #include <net/netfilter/nf_nat_helper.h> | |
869f37d8 PM |
18 | #include <net/netfilter/nf_conntrack_helper.h> |
19 | #include <net/netfilter/nf_conntrack_expect.h> | |
20 | #include <linux/netfilter/nf_conntrack_irc.h> | |
21 | ||
53b11308 FL |
22 | #define NAT_HELPER_NAME "irc" |
23 | ||
869f37d8 PM |
24 | MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>"); |
25 | MODULE_DESCRIPTION("IRC (DCC) NAT helper"); | |
26 | MODULE_LICENSE("GPL"); | |
53b11308 FL |
27 | MODULE_ALIAS_NF_NAT_HELPER(NAT_HELPER_NAME); |
28 | ||
29 | static struct nf_conntrack_nat_helper nat_helper_irc = | |
30 | NF_CT_NAT_HELPER_INIT(NAT_HELPER_NAME); | |
869f37d8 | 31 | |
3db05fea | 32 | static unsigned int help(struct sk_buff *skb, |
869f37d8 | 33 | enum ip_conntrack_info ctinfo, |
051966c0 | 34 | unsigned int protoff, |
869f37d8 PM |
35 | unsigned int matchoff, |
36 | unsigned int matchlen, | |
37 | struct nf_conntrack_expect *exp) | |
38 | { | |
39 | char buffer[sizeof("4294967296 65635")]; | |
2690d97a DB |
40 | struct nf_conn *ct = exp->master; |
41 | union nf_inet_addr newaddr; | |
869f37d8 | 42 | u_int16_t port; |
869f37d8 | 43 | |
869f37d8 | 44 | /* Reply comes from server. */ |
2690d97a DB |
45 | newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3; |
46 | ||
869f37d8 PM |
47 | exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; |
48 | exp->dir = IP_CT_DIR_REPLY; | |
49 | exp->expectfn = nf_nat_follow_master; | |
50 | ||
c92c2717 FW |
51 | port = nf_nat_exp_find_port(exp, |
52 | ntohs(exp->saved_proto.tcp.port)); | |
b20ab9cc | 53 | if (port == 0) { |
2690d97a | 54 | nf_ct_helper_log(skb, ct, "all ports in use"); |
869f37d8 | 55 | return NF_DROP; |
b20ab9cc | 56 | } |
869f37d8 | 57 | |
2690d97a DB |
58 | /* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27 |
59 | * strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28 | |
60 | * strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26 | |
61 | * strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26 | |
62 | * strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27 | |
63 | * | |
64 | * AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits, | |
65 | * 255.255.255.255==4294967296, 10 digits) | |
66 | * P: bound port (min 1 d, max 5d (65635)) | |
67 | * F: filename (min 1 d ) | |
68 | * S: size (min 1 d ) | |
69 | * 0x01, \n: terminators | |
70 | */ | |
71 | /* AAA = "us", ie. where server normally talks to. */ | |
72 | snprintf(buffer, sizeof(buffer), "%u %u", ntohl(newaddr.ip), port); | |
5191d70f | 73 | pr_debug("inserting '%s' == %pI4, port %u\n", |
2690d97a DB |
74 | buffer, &newaddr.ip, port); |
75 | ||
cba81cc4 GF |
76 | if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff, |
77 | matchlen, buffer, strlen(buffer))) { | |
2690d97a | 78 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
6823645d | 79 | nf_ct_unexpect_related(exp); |
cba81cc4 | 80 | return NF_DROP; |
b20ab9cc | 81 | } |
2690d97a | 82 | |
cba81cc4 | 83 | return NF_ACCEPT; |
869f37d8 PM |
84 | } |
85 | ||
86 | static void __exit nf_nat_irc_fini(void) | |
87 | { | |
53b11308 | 88 | nf_nat_helper_unregister(&nat_helper_irc); |
a9b3cd7f | 89 | RCU_INIT_POINTER(nf_nat_irc_hook, NULL); |
869f37d8 PM |
90 | synchronize_rcu(); |
91 | } | |
92 | ||
93 | static int __init nf_nat_irc_init(void) | |
94 | { | |
d1332e0a | 95 | BUG_ON(nf_nat_irc_hook != NULL); |
53b11308 | 96 | nf_nat_helper_register(&nat_helper_irc); |
a9b3cd7f | 97 | RCU_INIT_POINTER(nf_nat_irc_hook, help); |
869f37d8 PM |
98 | return 0; |
99 | } | |
100 | ||
101 | /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */ | |
e4dca7b7 | 102 | static int warn_set(const char *val, const struct kernel_param *kp) |
869f37d8 | 103 | { |
5191d70f | 104 | pr_info("kernel >= 2.6.10 only uses 'ports' for conntrack modules\n"); |
869f37d8 PM |
105 | return 0; |
106 | } | |
107 | module_param_call(ports, warn_set, NULL, NULL, 0); | |
108 | ||
109 | module_init(nf_nat_irc_init); | |
110 | module_exit(nf_nat_irc_fini); |