KOVACS Krisztian | e843927 | 2008-10-08 11:35:12 +0200 | [diff] [blame] | 1 | /* |
| 2 | * Transparent proxy support for Linux/iptables |
| 3 | * |
| 4 | * Copyright (c) 2006-2007 BalaBit IT Ltd. |
| 5 | * Author: Balazs Scheidler, Krisztian Kovacs |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | * |
| 11 | */ |
| 12 | |
| 13 | #include <linux/module.h> |
| 14 | #include <linux/skbuff.h> |
| 15 | #include <linux/ip.h> |
| 16 | #include <net/checksum.h> |
| 17 | #include <net/udp.h> |
| 18 | #include <net/inet_sock.h> |
| 19 | |
| 20 | #include <linux/netfilter/x_tables.h> |
| 21 | #include <linux/netfilter_ipv4/ip_tables.h> |
| 22 | #include <linux/netfilter/xt_TPROXY.h> |
| 23 | |
| 24 | #include <net/netfilter/ipv4/nf_defrag_ipv4.h> |
| 25 | #include <net/netfilter/nf_tproxy_core.h> |
| 26 | |
| 27 | static unsigned int |
| 28 | tproxy_tg(struct sk_buff *skb, |
| 29 | const struct net_device *in, |
| 30 | const struct net_device *out, |
| 31 | unsigned int hooknum, |
| 32 | const struct xt_target *target, |
| 33 | const void *targinfo) |
| 34 | { |
| 35 | const struct iphdr *iph = ip_hdr(skb); |
| 36 | const struct xt_tproxy_target_info *tgi = targinfo; |
| 37 | struct udphdr _hdr, *hp; |
| 38 | struct sock *sk; |
| 39 | |
| 40 | hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); |
| 41 | if (hp == NULL) |
| 42 | return NF_DROP; |
| 43 | |
| 44 | sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, |
| 45 | iph->saddr, tgi->laddr ? tgi->laddr : iph->daddr, |
| 46 | hp->source, tgi->lport ? tgi->lport : hp->dest, |
| 47 | in, true); |
| 48 | |
| 49 | /* NOTE: assign_sock consumes our sk reference */ |
| 50 | if (sk && nf_tproxy_assign_sock(skb, sk)) { |
| 51 | /* This should be in a separate target, but we don't do multiple |
| 52 | targets on the same rule yet */ |
| 53 | skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; |
| 54 | |
| 55 | pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n", |
| 56 | iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), |
| 57 | ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); |
| 58 | return NF_ACCEPT; |
| 59 | } |
| 60 | |
| 61 | pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n", |
| 62 | iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), |
| 63 | ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); |
| 64 | return NF_DROP; |
| 65 | } |
| 66 | |
| 67 | static bool |
| 68 | tproxy_tg_check(const char *tablename, |
| 69 | const void *entry, |
| 70 | const struct xt_target *target, |
| 71 | void *targetinfo, |
| 72 | unsigned int hook_mask) |
| 73 | { |
| 74 | const struct ipt_ip *i = entry; |
| 75 | |
| 76 | if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) |
| 77 | && !(i->invflags & IPT_INV_PROTO)) |
| 78 | return true; |
| 79 | |
| 80 | pr_info("xt_TPROXY: Can be used only in combination with " |
| 81 | "either -p tcp or -p udp\n"); |
| 82 | return false; |
| 83 | } |
| 84 | |
| 85 | static struct xt_target tproxy_tg_reg __read_mostly = { |
| 86 | .name = "TPROXY", |
| 87 | .family = AF_INET, |
| 88 | .table = "mangle", |
| 89 | .target = tproxy_tg, |
| 90 | .targetsize = sizeof(struct xt_tproxy_target_info), |
| 91 | .checkentry = tproxy_tg_check, |
| 92 | .hooks = 1 << NF_INET_PRE_ROUTING, |
| 93 | .me = THIS_MODULE, |
| 94 | }; |
| 95 | |
| 96 | static int __init tproxy_tg_init(void) |
| 97 | { |
| 98 | nf_defrag_ipv4_enable(); |
| 99 | return xt_register_target(&tproxy_tg_reg); |
| 100 | } |
| 101 | |
| 102 | static void __exit tproxy_tg_exit(void) |
| 103 | { |
| 104 | xt_unregister_target(&tproxy_tg_reg); |
| 105 | } |
| 106 | |
| 107 | module_init(tproxy_tg_init); |
| 108 | module_exit(tproxy_tg_exit); |
| 109 | MODULE_LICENSE("GPL"); |
| 110 | MODULE_AUTHOR("Krisztian Kovacs"); |
| 111 | MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); |
| 112 | MODULE_ALIAS("ipt_TPROXY"); |