b20ab9cc63
Connection tracking helpers have to drop packets under exceptional situations. Currently, the user gets the following logging message in case that happens: nf_ct_%s: dropping packet ... However, depending on the helper, there are different reasons why a packet can be dropped. This patch modifies the existing code to provide more specific error message in the scope of each helper to help users to debug the reason why the packet has been dropped, ie: nf_ct_%s: dropping packet: reason ... Thanks to Joe Perches for many formatting suggestions. Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
98 lines
2.6 KiB
C
98 lines
2.6 KiB
C
/* IRC extension for TCP NAT alteration.
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*
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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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* 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/moduleparam.h>
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#include <linux/tcp.h>
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#include <linux/kernel.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_helper.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <linux/netfilter/nf_conntrack_irc.h>
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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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MODULE_ALIAS("ip_nat_irc");
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static unsigned int help(struct sk_buff *skb,
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enum ip_conntrack_info ctinfo,
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unsigned int protoff,
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unsigned int matchoff,
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unsigned int matchlen,
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struct nf_conntrack_expect *exp)
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{
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char buffer[sizeof("4294967296 65635")];
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u_int16_t port;
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unsigned int ret;
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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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exp->expectfn = nf_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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int ret;
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exp->tuple.dst.u.tcp.port = htons(port);
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ret = nf_ct_expect_related(exp);
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if (ret == 0)
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break;
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else if (ret != -EBUSY) {
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port = 0;
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break;
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}
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}
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if (port == 0) {
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nf_ct_helper_log(skb, exp->master, "all ports in use");
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return NF_DROP;
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}
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ret = nf_nat_mangle_tcp_packet(skb, exp->master, ctinfo,
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protoff, matchoff, matchlen, buffer,
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strlen(buffer));
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if (ret != NF_ACCEPT) {
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nf_ct_helper_log(skb, exp->master, "cannot mangle packet");
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nf_ct_unexpect_related(exp);
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}
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return ret;
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}
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static void __exit nf_nat_irc_fini(void)
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{
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RCU_INIT_POINTER(nf_nat_irc_hook, NULL);
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synchronize_rcu();
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}
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static int __init nf_nat_irc_init(void)
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{
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BUG_ON(nf_nat_irc_hook != NULL);
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RCU_INIT_POINTER(nf_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(nf_nat_irc_init);
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module_exit(nf_nat_irc_fini);
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