text: /*
   * ip_vs_nfct.c:	Netfilter connection tracking support for IPVS
   *
   * Portions Copyright (C) 2001-2002
   * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland.
   *
   * Portions Copyright (C) 2003-2010
   * Julian Anastasov
   *
   *
   * This code is free software; you can redistribute it and/or modify
   * it under the terms of the GNU General Public License as published by
   * the Free Software Foundation; either version 2 of the License, or
   * (at your option) any later version.
   *
   * This program is distributed in the hope that it will be useful,
   * but WITHOUT ANY WARRANTY; without even the implied warranty of
   * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   * GNU General Public License for more details.
   *
   * You should have received a copy of the GNU General Public License
   * along with this program; if not, see <http://www.gnu.org/licenses/>.
   *
   *
   * Authors:
   * Ben North <ben@redfrontdoor.org>
   * Julian Anastasov <ja@ssi.bg>		Reorganize and sync with latest kernels
   * Hannes Eder <heder@google.com>	Extend NFCT support for FTP, ipvs match
   *
   *
   * Current status:
   *
   * - provide conntrack confirmation for new and related connections, by
   * this way we can see their proper conntrack state in all hooks
   * - support for all forwarding methods, not only NAT
   * - FTP support (NAT), ability to support other NAT apps with expectations
   * - to correctly create expectations for related NAT connections the proper
   * NF conntrack support must be already installed, eg. ip_vs_ftp requires
   * nf_conntrack_ftp ... iptables_nat for the same ports (but no iptables
   * NAT rules are needed)
   * - alter reply for NAT when forwarding packet in original direction:
   * conntrack from client in NEW or RELATED (Passive FTP DATA) state or
   * when RELATED conntrack is created from real server (Active FTP DATA)
   * - if iptables_nat is not loaded the Passive FTP will not work (the
   * PASV response can not be NAT-ed) but Active FTP should work
   *
   */
  
  #define KMSG_COMPONENT "IPVS"
  #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
  
  #include <linux/module.h>
  #include <linux/types.h>
  #include <linux/kernel.h>
  #include <linux/errno.h>
  #include <linux/compiler.h>
  #include <linux/vmalloc.h>
  #include <linux/skbuff.h>
  #include <net/ip.h>
  #include <linux/netfilter.h>
  #include <linux/netfilter_ipv4.h>
  #include <net/ip_vs.h>
  #include <net/netfilter/nf_conntrack_core.h>
  #include <net/netfilter/nf_conntrack_expect.h>
  #include <net/netfilter/nf_conntrack_seqadj.h>
  #include <net/netfilter/nf_conntrack_helper.h>
  #include <net/netfilter/nf_conntrack_zones.h>
  
  
  #define FMT_TUPLE	"%pI4:%u->%pI4:%u/%u"
  #define ARG_TUPLE(T)	&(T)->src.u3.ip, ntohs((T)->src.u.all), \
  			&(T)->dst.u3.ip, ntohs((T)->dst.u.all), \
  			(T)->dst.protonum
  
  #define FMT_CONN	"%pI4:%u->%pI4:%u->%pI4:%u/%u:%u"
  #define ARG_CONN(C)	&((C)->caddr.ip), ntohs((C)->cport), \
  			&((C)->vaddr.ip), ntohs((C)->vport), \
  			&((C)->daddr.ip), ntohs((C)->dport), \
  			(C)->protocol, (C)->state
  
  void
  ip_vs_update_conntrack(struct sk_buff *skb, struct ip_vs_conn *cp, int outin)
  {
  	enum ip_conntrack_info ctinfo;
  	struct nf_conn *ct = nf_ct_get(skb, &ctinfo);
  	struct nf_conntrack_tuple new_tuple;
  
  	if (ct == NULL || nf_ct_is_confirmed(ct) || nf_ct_is_untracked(ct) ||
  	    nf_ct_is_dying(ct))
  		return;
  
  	/* Never alter conntrack for non-NAT conns */
  	if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
  		return;
  
  	/* Alter reply only in original direction */
  	if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL)
  		return;
  
  	/* Applications may adjust TCP seqs */
  	if (cp->app && nf_ct_protonum(ct) == IPPROTO_TCP &&
  	    !nfct_seqadj(ct) && !nfct_seqadj_ext_add(ct))
  		return;
  
  	/*
  	 * The connection is not yet in the hashtable, so we update it.
  	 * CIP->VIP will remain the same, so leave the tuple in
  	 * IP_CT_DIR_ORIGINAL untouched.  When the reply comes back from the
  	 * real-server we will see RIP->DIP.
  	 */
  	new_tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  	/*
  	 * This will also take care of UDP and other protocols.
  	 */
  	if (outin) {
  		new_tuple.src.u3 = cp->daddr;
  		if (new_tuple.dst.protonum != IPPROTO_ICMP &&
  		    new_tuple.dst.protonum != IPPROTO_ICMPV6)
  			new_tuple.src.u.tcp.port = cp->dport;
  	} else {
  		new_tuple.dst.u3 = cp->vaddr;
  		if (new_tuple.dst.protonum != IPPROTO_ICMP &&
  		    new_tuple.dst.protonum != IPPROTO_ICMPV6)
  			new_tuple.dst.u.tcp.port = cp->vport;
  	}
  	IP_VS_DBG(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
  		  "ctinfo=%d, old reply=" FMT_TUPLE
  		  ", new reply=" FMT_TUPLE ", cp=" FMT_CONN "\n",
  		  __func__, ct, ct->status, ctinfo,
  		  ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple),
  		  ARG_TUPLE(&new_tuple), ARG_CONN(cp));
  	nf_conntrack_alter_reply(ct, &new_tuple);
  }
  
  int ip_vs_confirm_conntrack(struct sk_buff *skb)
  {
  	return nf_conntrack_confirm(skb);
  }
  
  /*
   * Called from init_conntrack() as expectfn handler.
   */
  static void ip_vs_nfct_expect_callback(struct nf_conn *ct,
  	struct nf_conntrack_expect *exp)
  {
  	struct nf_conntrack_tuple *orig, new_reply;
  	struct ip_vs_conn *cp;
  	struct ip_vs_conn_param p;
  	struct net *net = nf_ct_net(ct);
  
  	if (exp->tuple.src.l3num != PF_INET)
  		return;
  
  	/*
  	 * We assume that no NF locks are held before this callback.
  	 * ip_vs_conn_out_get and ip_vs_conn_in_get should match their
  	 * expectations even if they use wildcard values, now we provide the
  	 * actual values from the newly created original conntrack direction.
  	 * The conntrack is confirmed when packet reaches IPVS hooks.
  	 */
  
  	/* RS->CLIENT */
  	orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
  	ip_vs_conn_fill_param(net, exp->tuple.src.l3num, orig->dst.protonum,
  			      &orig->src.u3, orig->src.u.tcp.port,
  			      &orig->dst.u3, orig->dst.u.tcp.port, &p);
  	cp = ip_vs_conn_out_get(&p);
  	if (cp) {
  		/* Change reply CLIENT->RS to CLIENT->VS */
  		new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  		IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
  			  FMT_TUPLE ", found inout cp=" FMT_CONN "\n",
  			  __func__, ct, ct->status,
  			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
  			  ARG_CONN(cp));
  		new_reply.dst.u3 = cp->vaddr;
  		new_reply.dst.u.tcp.port = cp->vport;
  		IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE
  			  ", inout cp=" FMT_CONN "\n",
  			  __func__, ct,
  			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
  			  ARG_CONN(cp));
  		goto alter;
  	}
  
  	/* CLIENT->VS */
  	cp = ip_vs_conn_in_get(&p);
  	if (cp) {
  		/* Change reply VS->CLIENT to RS->CLIENT */
  		new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
  		IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", "
  			  FMT_TUPLE ", found outin cp=" FMT_CONN "\n",
  			  __func__, ct, ct->status,
  			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
  			  ARG_CONN(cp));
  		new_reply.src.u3 = cp->daddr;
  		new_reply.src.u.tcp.port = cp->dport;
  		IP_VS_DBG(7, "%s: ct=%p, new tuples=" FMT_TUPLE ", "
  			  FMT_TUPLE ", outin cp=" FMT_CONN "\n",
  			  __func__, ct,
  			  ARG_TUPLE(orig), ARG_TUPLE(&new_reply),
  			  ARG_CONN(cp));
  		goto alter;
  	}
  
  	IP_VS_DBG(7, "%s: ct=%p, status=0x%lX, tuple=" FMT_TUPLE
  		  " - unknown expect\n",
  		  __func__, ct, ct->status, ARG_TUPLE(orig));
  	return;
  
  alter:
  	/* Never alter conntrack for non-NAT conns */
  	if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ)
  		nf_conntrack_alter_reply(ct, &new_reply);
  	ip_vs_conn_put(cp);
  	return;
  }
  
  /*
   * Create NF conntrack expectation with wildcard (optional) source port.
   * Then the default callback function will alter the reply and will confirm
   * the conntrack entry when the first packet comes.
   * Use port 0 to expect connection from any port.
   */
  void ip_vs_nfct_expect_related(struct sk_buff *skb, struct nf_conn *ct,
  			       struct ip_vs_conn *cp, u_int8_t proto,
  			       const __be16 port, int from_rs)
  {
  	struct nf_conntrack_expect *exp;
  
  	if (ct == NULL || nf_ct_is_untracked(ct))
  		return;
  
  	exp = nf_ct_expect_alloc(ct);
  	if (!exp)
  		return;
  
  	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
  			from_rs ? &cp->daddr : &cp->caddr,
  			from_rs ? &cp->caddr : &cp->vaddr,
  			proto, port ? &port : NULL,
  			from_rs ? &cp->cport : &cp->vport);
  
  	exp->expectfn = ip_vs_nfct_expect_callback;
  
  	IP_VS_DBG(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
  		__func__, ct, ARG_TUPLE(&exp->tuple));
  	nf_ct_expect_related(exp);
  	nf_ct_expect_put(exp);
  }
  EXPORT_SYMBOL(ip_vs_nfct_expect_related);
  
  /*
   * Our connection was terminated, try to drop the conntrack immediately
   */
  void ip_vs_conn_drop_conntrack(struct ip_vs_conn *cp)
  {
  	struct nf_conntrack_tuple_hash *h;
  	struct nf_conn *ct;
  	struct nf_conntrack_tuple tuple;
  
  	if (!cp->cport)
  		return;
  
  	tuple = (struct nf_conntrack_tuple) {
  		.dst = { .protonum = cp->protocol, .dir = IP_CT_DIR_ORIGINAL } };
  	tuple.src.u3 = cp->caddr;
  	tuple.src.u.all = cp->cport;
  	tuple.src.l3num = cp->af;
  	tuple.dst.u3 = cp->vaddr;
  	tuple.dst.u.all = cp->vport;
  
  	IP_VS_DBG(7, "%s: dropping conntrack with tuple=" FMT_TUPLE
  		" for conn " FMT_CONN "\n",
  		__func__, ARG_TUPLE(&tuple), ARG_CONN(cp));
  
  	h = nf_conntrack_find_get(ip_vs_conn_net(cp), NF_CT_DEFAULT_ZONE,
  				  &tuple);
  	if (h) {
  		ct = nf_ct_tuplehash_to_ctrack(h);
  		/* Show what happens instead of calling nf_ct_kill() */
  		if (del_timer(&ct->timeout)) {
  			IP_VS_DBG(7, "%s: ct=%p, deleted conntrack timer for tuple="
  				FMT_TUPLE "\n",
  				__func__, ct, ARG_TUPLE(&tuple));
  			if (ct->timeout.function)
  				ct->timeout.function(ct->timeout.data);
  		} else {
  			IP_VS_DBG(7, "%s: ct=%p, no conntrack timer for tuple="
  				FMT_TUPLE "\n",
  				__func__, ct, ARG_TUPLE(&tuple));
  		}
  		nf_ct_put(ct);
  	} else {
  		IP_VS_DBG(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
  			__func__, ARG_TUPLE(&tuple));
  	}
  }
  
  