projects / linux-2.6-block.git / blame
| Commit | Line | Data |
|---|---|---|
| 16958900 PM |
1 | /* Amanda extension for TCP NAT alteration. |
| 2 | * (C) 2002 by Brian J. Murrell <netfilter@interlinx.bc.ca> | |
| 3 | * based on a copy of HW's ip_nat_irc.c as well as other modules | |
| 4 | * | |
| 5 | * This program is free software; you can redistribute it and/or | |
| 6 | * modify it under the terms of the GNU General Public License | |
| 7 | * as published by the Free Software Foundation; either version | |
| 8 | * 2 of the License, or (at your option) any later version. | |
| 9 | */ | |
| 10 | ||
| 11 | #include <linux/kernel.h> | |
| 12 | #include <linux/module.h> | |
| 13 | #include <linux/skbuff.h> | |
| 14 | #include <linux/udp.h> | |
| 15 | ||
| 16 | #include <net/netfilter/nf_nat_helper.h> | |
| 17 | #include <net/netfilter/nf_nat_rule.h> | |
| 18 | #include <net/netfilter/nf_conntrack_helper.h> | |
| 19 | #include <net/netfilter/nf_conntrack_expect.h> | |
| 20 | #include <linux/netfilter/nf_conntrack_amanda.h> | |
| 21 | ||
| 22 | MODULE_AUTHOR("Brian J. Murrell <netfilter@interlinx.bc.ca>"); | |
| 23 | MODULE_DESCRIPTION("Amanda NAT helper"); | |
| 24 | MODULE_LICENSE("GPL"); | |
| 25 | MODULE_ALIAS("ip_nat_amanda"); | |
| 26 | ||
| 27 | static unsigned int help(struct sk_buff **pskb, | |
| 28 | enum ip_conntrack_info ctinfo, | |
| 29 | unsigned int matchoff, | |
| 30 | unsigned int matchlen, | |
| 31 | struct nf_conntrack_expect *exp) | |
| 32 | { | |
| 33 | char buffer[sizeof("65535")]; | |
| 34 | u_int16_t port; | |
| 35 | unsigned int ret; | |
| 36 | ||
| 37 | /* Connection comes from client. */ | |
| 38 | exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port; | |
| 39 | exp->dir = IP_CT_DIR_ORIGINAL; | |
| 40 | ||
| 41 | /* When you see the packet, we need to NAT it the same as the | |
| 42 | * this one (ie. same IP: it will be TCP and master is UDP). */ | |
| 43 | exp->expectfn = nf_nat_follow_master; | |
| 44 | ||
| 45 | /* Try to get same port: if not, try to change it. */ | |
| 46 | for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) { | |
| 47 | exp->tuple.dst.u.tcp.port = htons(port); | |
| 48 | if (nf_conntrack_expect_related(exp) == 0) | |
| 49 | break; | |
| 50 | } | |
| 51 | ||
| 52 | if (port == 0) | |
| 53 | return NF_DROP; | |
| 54 | ||
| 55 | sprintf(buffer, "%u", port); | |
| 56 | ret = nf_nat_mangle_udp_packet(pskb, exp->master, ctinfo, | |
| 57 | matchoff, matchlen, | |
| 58 | buffer, strlen(buffer)); | |
| 59 | if (ret != NF_ACCEPT) | |
| 60 | nf_conntrack_unexpect_related(exp); | |
| 61 | return ret; | |
| 62 | } | |
| 63 | ||
| 64 | static void __exit nf_nat_amanda_fini(void) | |
| 65 | { | |
| 66 | rcu_assign_pointer(nf_nat_amanda_hook, NULL); | |
| 67 | synchronize_rcu(); | |
| 68 | } | |
| 69 | ||
| 70 | static int __init nf_nat_amanda_init(void) | |
| 71 | { | |
| 72 | BUG_ON(rcu_dereference(nf_nat_amanda_hook)); | |
| 73 | rcu_assign_pointer(nf_nat_amanda_hook, help); | |
| 74 | return 0; | |
| 75 | } | |
| 76 | ||
| 77 | module_init(nf_nat_amanda_init); | |
| 78 | module_exit(nf_nat_amanda_fini); |