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