| /* |
| * Transparent proxy support for Linux/iptables |
| * |
| * Copyright (c) 2006-2007 BalaBit IT Ltd. |
| * Author: Balazs Scheidler, Krisztian Kovacs |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/ip.h> |
| #include <net/checksum.h> |
| #include <net/udp.h> |
| #include <net/inet_sock.h> |
| |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <linux/netfilter/xt_TPROXY.h> |
| |
| #include <net/netfilter/ipv4/nf_defrag_ipv4.h> |
| #include <net/netfilter/nf_tproxy_core.h> |
| |
| static unsigned int |
| tproxy_tg(struct sk_buff *skb, const struct xt_target_param *par) |
| { |
| const struct iphdr *iph = ip_hdr(skb); |
| const struct xt_tproxy_target_info *tgi = par->targinfo; |
| struct udphdr _hdr, *hp; |
| struct sock *sk; |
| |
| hp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_hdr), &_hdr); |
| if (hp == NULL) |
| return NF_DROP; |
| |
| sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), iph->protocol, |
| iph->saddr, tgi->laddr ? tgi->laddr : iph->daddr, |
| hp->source, tgi->lport ? tgi->lport : hp->dest, |
| par->in, true); |
| |
| /* NOTE: assign_sock consumes our sk reference */ |
| if (sk && nf_tproxy_assign_sock(skb, sk)) { |
| /* This should be in a separate target, but we don't do multiple |
| targets on the same rule yet */ |
| skb->mark = (skb->mark & ~tgi->mark_mask) ^ tgi->mark_value; |
| |
| pr_debug("redirecting: proto %u %08x:%u -> %08x:%u, mark: %x\n", |
| iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), |
| ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); |
| return NF_ACCEPT; |
| } |
| |
| pr_debug("no socket, dropping: proto %u %08x:%u -> %08x:%u, mark: %x\n", |
| iph->protocol, ntohl(iph->daddr), ntohs(hp->dest), |
| ntohl(tgi->laddr), ntohs(tgi->lport), skb->mark); |
| return NF_DROP; |
| } |
| |
| static bool tproxy_tg_check(const struct xt_tgchk_param *par) |
| { |
| const struct ipt_ip *i = par->entryinfo; |
| |
| if ((i->proto == IPPROTO_TCP || i->proto == IPPROTO_UDP) |
| && !(i->invflags & IPT_INV_PROTO)) |
| return true; |
| |
| pr_info("Can be used only in combination with " |
| "either -p tcp or -p udp\n"); |
| return false; |
| } |
| |
| static struct xt_target tproxy_tg_reg __read_mostly = { |
| .name = "TPROXY", |
| .family = AF_INET, |
| .table = "mangle", |
| .target = tproxy_tg, |
| .targetsize = sizeof(struct xt_tproxy_target_info), |
| .checkentry = tproxy_tg_check, |
| .hooks = 1 << NF_INET_PRE_ROUTING, |
| .me = THIS_MODULE, |
| }; |
| |
| static int __init tproxy_tg_init(void) |
| { |
| nf_defrag_ipv4_enable(); |
| return xt_register_target(&tproxy_tg_reg); |
| } |
| |
| static void __exit tproxy_tg_exit(void) |
| { |
| xt_unregister_target(&tproxy_tg_reg); |
| } |
| |
| module_init(tproxy_tg_init); |
| module_exit(tproxy_tg_exit); |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Krisztian Kovacs"); |
| MODULE_DESCRIPTION("Netfilter transparent proxy (TPROXY) target module."); |
| MODULE_ALIAS("ipt_TPROXY"); |