337fbc4166
The NAT helpr hooks are protected by RCU, but all of the conntrack helpers test and use the global pointers instead of copying them first using rcu_dereference() Also replace synchronize_net() by synchronize_rcu() for clarity since sychronizing only with packet receive processing is insufficient to prevent races. Signed-off-by: Patrick McHardy <kaber@trash.net>
123 lines
3.7 KiB
C
123 lines
3.7 KiB
C
/* IRC extension for TCP NAT alteration.
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* (C) 2000-2001 by Harald Welte <laforge@gnumonks.org>
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* (C) 2004 Rusty Russell <rusty@rustcorp.com.au> IBM Corporation
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* based on a copy of RR's ip_nat_ftp.c
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*
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* ip_nat_irc.c,v 1.16 2001/12/06 07:42:10 laforge Exp
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*/
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#include <linux/module.h>
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#include <linux/netfilter_ipv4.h>
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#include <linux/ip.h>
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#include <linux/tcp.h>
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#include <linux/kernel.h>
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#include <net/tcp.h>
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#include <linux/netfilter_ipv4/ip_nat.h>
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#include <linux/netfilter_ipv4/ip_nat_helper.h>
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#include <linux/netfilter_ipv4/ip_nat_rule.h>
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#include <linux/netfilter_ipv4/ip_conntrack_irc.h>
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#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
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#include <linux/moduleparam.h>
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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MODULE_AUTHOR("Harald Welte <laforge@gnumonks.org>");
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MODULE_DESCRIPTION("IRC (DCC) NAT helper");
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MODULE_LICENSE("GPL");
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static unsigned int help(struct sk_buff **pskb,
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enum ip_conntrack_info ctinfo,
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unsigned int matchoff,
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unsigned int matchlen,
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struct ip_conntrack_expect *exp)
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{
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u_int16_t port;
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unsigned int ret;
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/* "4294967296 65635 " */
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char buffer[18];
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DEBUGP("IRC_NAT: info (seq %u + %u) in %u\n",
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expect->seq, exp_irc_info->len,
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ntohl(tcph->seq));
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/* Reply comes from server. */
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exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
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exp->dir = IP_CT_DIR_REPLY;
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/* When you see the packet, we need to NAT it the same as the
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* this one. */
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exp->expectfn = ip_nat_follow_master;
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/* Try to get same port: if not, try to change it. */
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for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
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exp->tuple.dst.u.tcp.port = htons(port);
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if (ip_conntrack_expect_related(exp) == 0)
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break;
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}
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if (port == 0)
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return NF_DROP;
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/* strlen("\1DCC CHAT chat AAAAAAAA P\1\n")=27
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* strlen("\1DCC SCHAT chat AAAAAAAA P\1\n")=28
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* strlen("\1DCC SEND F AAAAAAAA P S\1\n")=26
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* strlen("\1DCC MOVE F AAAAAAAA P S\1\n")=26
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* strlen("\1DCC TSEND F AAAAAAAA P S\1\n")=27
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* AAAAAAAAA: bound addr (1.0.0.0==16777216, min 8 digits,
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* 255.255.255.255==4294967296, 10 digits)
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* P: bound port (min 1 d, max 5d (65635))
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* F: filename (min 1 d )
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* S: size (min 1 d )
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* 0x01, \n: terminators
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*/
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/* AAA = "us", ie. where server normally talks to. */
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sprintf(buffer, "%u %u",
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ntohl(exp->master->tuplehash[IP_CT_DIR_REPLY].tuple.dst.ip),
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port);
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DEBUGP("ip_nat_irc: Inserting '%s' == %u.%u.%u.%u, port %u\n",
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buffer, NIPQUAD(exp->tuple.src.ip), port);
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ret = ip_nat_mangle_tcp_packet(pskb, exp->master, ctinfo,
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matchoff, matchlen, buffer,
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strlen(buffer));
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if (ret != NF_ACCEPT)
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ip_conntrack_unexpect_related(exp);
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return ret;
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}
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static void __exit ip_nat_irc_fini(void)
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{
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rcu_assign_pointer(ip_nat_irc_hook, NULL);
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synchronize_rcu();
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}
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static int __init ip_nat_irc_init(void)
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{
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BUG_ON(rcu_dereference(ip_nat_irc_hook));
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rcu_assign_pointer(ip_nat_irc_hook, help);
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return 0;
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}
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/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
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static int warn_set(const char *val, struct kernel_param *kp)
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{
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printk(KERN_INFO KBUILD_MODNAME
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": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
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return 0;
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}
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module_param_call(ports, warn_set, NULL, NULL, 0);
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module_init(ip_nat_irc_init);
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module_exit(ip_nat_irc_fini);
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