Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 1 | /* iptables module to match on related connections */ |
| 2 | /* |
| 3 | * (C) 2001 Martin Josefsson <gandalf@wlug.westbo.se> |
| 4 | * |
| 5 | * This program is free software; you can redistribute it and/or modify |
| 6 | * it under the terms of the GNU General Public License version 2 as |
| 7 | * published by the Free Software Foundation. |
| 8 | * |
| 9 | * 19 Mar 2002 Harald Welte <laforge@gnumonks.org>: |
| 10 | * - Port to newnat infrastructure |
| 11 | */ |
| 12 | |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/skbuff.h> |
| 15 | #include <linux/netfilter.h> |
| 16 | #include <linux/netfilter_ipv4/ip_conntrack.h> |
| 17 | #include <linux/netfilter_ipv4/ip_conntrack_core.h> |
| 18 | #include <linux/netfilter_ipv4/ip_conntrack_helper.h> |
| 19 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 20 | #include <linux/netfilter_ipv4/ipt_helper.h> |
| 21 | |
| 22 | MODULE_LICENSE("GPL"); |
| 23 | MODULE_AUTHOR("Martin Josefsson <gandalf@netfilter.org>"); |
| 24 | MODULE_DESCRIPTION("iptables helper match module"); |
| 25 | |
| 26 | #if 0 |
| 27 | #define DEBUGP printk |
| 28 | #else |
| 29 | #define DEBUGP(format, args...) |
| 30 | #endif |
| 31 | |
| 32 | static int |
| 33 | match(const struct sk_buff *skb, |
| 34 | const struct net_device *in, |
| 35 | const struct net_device *out, |
| 36 | const void *matchinfo, |
| 37 | int offset, |
| 38 | int *hotdrop) |
| 39 | { |
| 40 | const struct ipt_helper_info *info = matchinfo; |
| 41 | struct ip_conntrack *ct; |
| 42 | enum ip_conntrack_info ctinfo; |
| 43 | int ret = info->invert; |
| 44 | |
| 45 | ct = ip_conntrack_get((struct sk_buff *)skb, &ctinfo); |
| 46 | if (!ct) { |
| 47 | DEBUGP("ipt_helper: Eek! invalid conntrack?\n"); |
| 48 | return ret; |
| 49 | } |
| 50 | |
| 51 | if (!ct->master) { |
| 52 | DEBUGP("ipt_helper: conntrack %p has no master\n", ct); |
| 53 | return ret; |
| 54 | } |
| 55 | |
Patrick McHardy | e45b1be | 2005-06-21 14:01:30 -0700 | [diff] [blame^] | 56 | read_lock_bh(&ip_conntrack_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 57 | if (!ct->master->helper) { |
| 58 | DEBUGP("ipt_helper: master ct %p has no helper\n", |
| 59 | exp->expectant); |
| 60 | goto out_unlock; |
| 61 | } |
| 62 | |
| 63 | DEBUGP("master's name = %s , info->name = %s\n", |
| 64 | ct->master->helper->name, info->name); |
| 65 | |
| 66 | if (info->name[0] == '\0') |
| 67 | ret ^= 1; |
| 68 | else |
| 69 | ret ^= !strncmp(ct->master->helper->name, info->name, |
| 70 | strlen(ct->master->helper->name)); |
| 71 | out_unlock: |
Patrick McHardy | e45b1be | 2005-06-21 14:01:30 -0700 | [diff] [blame^] | 72 | read_unlock_bh(&ip_conntrack_lock); |
Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame] | 73 | return ret; |
| 74 | } |
| 75 | |
| 76 | static int check(const char *tablename, |
| 77 | const struct ipt_ip *ip, |
| 78 | void *matchinfo, |
| 79 | unsigned int matchsize, |
| 80 | unsigned int hook_mask) |
| 81 | { |
| 82 | struct ipt_helper_info *info = matchinfo; |
| 83 | |
| 84 | info->name[29] = '\0'; |
| 85 | |
| 86 | /* verify size */ |
| 87 | if (matchsize != IPT_ALIGN(sizeof(struct ipt_helper_info))) |
| 88 | return 0; |
| 89 | |
| 90 | return 1; |
| 91 | } |
| 92 | |
| 93 | static struct ipt_match helper_match = { |
| 94 | .name = "helper", |
| 95 | .match = &match, |
| 96 | .checkentry = &check, |
| 97 | .me = THIS_MODULE, |
| 98 | }; |
| 99 | |
| 100 | static int __init init(void) |
| 101 | { |
| 102 | need_ip_conntrack(); |
| 103 | return ipt_register_match(&helper_match); |
| 104 | } |
| 105 | |
| 106 | static void __exit fini(void) |
| 107 | { |
| 108 | ipt_unregister_match(&helper_match); |
| 109 | } |
| 110 | |
| 111 | module_init(init); |
| 112 | module_exit(fini); |
| 113 | |