Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 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> |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 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 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 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 | |
Herbert Xu | 3db05fe | 2007-10-15 00:53:15 -0700 | [diff] [blame] | 29 | static unsigned int help(struct sk_buff *skb, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 30 | enum ip_conntrack_info ctinfo, |
Patrick McHardy | 051966c | 2012-08-26 19:14:04 +0200 | [diff] [blame] | 31 | unsigned int protoff, |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 32 | unsigned int matchoff, |
| 33 | unsigned int matchlen, |
| 34 | struct nf_conntrack_expect *exp) |
| 35 | { |
| 36 | char buffer[sizeof("4294967296 65635")]; |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 37 | struct nf_conn *ct = exp->master; |
| 38 | union nf_inet_addr newaddr; |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 39 | u_int16_t port; |
| 40 | unsigned int ret; |
| 41 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 42 | /* Reply comes from server. */ |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 43 | newaddr = ct->tuplehash[IP_CT_DIR_REPLY].tuple.dst.u3; |
| 44 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 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++) { |
Pablo Neira Ayuso | 5b92b61 | 2010-09-22 08:34:12 +0200 | [diff] [blame] | 51 | int ret; |
| 52 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 53 | exp->tuple.dst.u.tcp.port = htons(port); |
Pablo Neira Ayuso | 5b92b61 | 2010-09-22 08:34:12 +0200 | [diff] [blame] | 54 | ret = nf_ct_expect_related(exp); |
| 55 | if (ret == 0) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 56 | break; |
Pablo Neira Ayuso | 5b92b61 | 2010-09-22 08:34:12 +0200 | [diff] [blame] | 57 | else if (ret != -EBUSY) { |
| 58 | port = 0; |
| 59 | break; |
| 60 | } |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 61 | } |
| 62 | |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 63 | if (port == 0) { |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 64 | nf_ct_helper_log(skb, ct, "all ports in use"); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 65 | return NF_DROP; |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 66 | } |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 67 | |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 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)); |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 88 | if (ret != NF_ACCEPT) { |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 89 | nf_ct_helper_log(skb, ct, "cannot mangle packet"); |
Patrick McHardy | 6823645 | 2007-07-07 22:30:49 -0700 | [diff] [blame] | 90 | nf_ct_unexpect_related(exp); |
Pablo Neira Ayuso | b20ab9cc | 2013-02-10 18:56:56 +0100 | [diff] [blame] | 91 | } |
Daniel Borkmann | 2690d97 | 2013-12-31 16:28:39 +0100 | [diff] [blame] | 92 | |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 93 | return ret; |
| 94 | } |
| 95 | |
| 96 | static void __exit nf_nat_irc_fini(void) |
| 97 | { |
Stephen Hemminger | a9b3cd7 | 2011-08-01 16:19:00 +0000 | [diff] [blame] | 98 | RCU_INIT_POINTER(nf_nat_irc_hook, NULL); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 99 | synchronize_rcu(); |
| 100 | } |
| 101 | |
| 102 | static int __init nf_nat_irc_init(void) |
| 103 | { |
Patrick McHardy | d1332e0 | 2007-11-05 20:43:30 -0800 | [diff] [blame] | 104 | BUG_ON(nf_nat_irc_hook != NULL); |
Stephen Hemminger | a9b3cd7 | 2011-08-01 16:19:00 +0000 | [diff] [blame] | 105 | RCU_INIT_POINTER(nf_nat_irc_hook, help); |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 106 | return 0; |
| 107 | } |
| 108 | |
| 109 | /* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */ |
Kees Cook | 24da2c8 | 2017-10-17 19:04:42 -0700 | [diff] [blame] | 110 | static int warn_set(const char *val, const struct kernel_param *kp) |
Patrick McHardy | 869f37d | 2006-12-02 22:09:06 -0800 | [diff] [blame] | 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); |