diff options
Diffstat (limited to 'net/netfilter/nf_nat_irc.c')
| -rw-r--r-- | net/netfilter/nf_nat_irc.c | 110 |
1 files changed, 110 insertions, 0 deletions
diff --git a/net/netfilter/nf_nat_irc.c b/net/netfilter/nf_nat_irc.c new file mode 100644 index 000000000..19c4fcc60 --- /dev/null +++ b/net/netfilter/nf_nat_irc.c @@ -0,0 +1,110 @@ +// 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); |