// SPDX-License-Identifier: GPL-2.0-or-later
/*
* 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
*
* Authors:
* Ben North <[email protected]>
* Julian Anastasov <[email protected]> Reorganize and sync with latest kernels
* Hannes Eder <[email protected]> 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 "%s:%u->%s:%u/%u"
#define ARG_TUPLE(T) IP_VS_DBG_ADDR((T)->src.l3num, &(T)->src.u3), \
ntohs((T)->src.u.all), \
IP_VS_DBG_ADDR((T)->src.l3num, &(T)->dst.u3), \
ntohs((T)->dst.u.all), \
(T)->dst.protonum
#define FMT_CONN "%s:%u->%s:%u->%s:%u/%u:%u"
#define ARG_CONN(C) IP_VS_DBG_ADDR((C)->af, &((C)->caddr)), \
ntohs((C)->cport), \
IP_VS_DBG_ADDR((C)->af, &((C)->vaddr)), \
ntohs((C)->vport), \
IP_VS_DBG_ADDR((C)->daf, &((C)->daddr)), \
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_dying(ct))
return;
/* Never alter conntrack for non-NAT conns */
if (IP_VS_FWD_METHOD(cp) != IP_VS_CONN_F_MASQ)
return;
/* Never alter conntrack for OPS conns (no reply is expected) */
if (cp->flags & IP_VS_CONN_F_ONE_PACKET)
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_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
"ctinfo=%d, old reply=" FMT_TUPLE "\n",
__func__, ct, ct->status, ctinfo,
ARG_TUPLE(&ct->tuplehash[IP_CT_DIR_REPLY].tuple));
IP_VS_DBG_BUF(7, "%s: Updating conntrack ct=%p, status=0x%lX, "
"ctinfo=%d, new reply=" FMT_TUPLE "\n",
__func__, ct, ct->status, ctinfo,
ARG_TUPLE(&new_tuple));
nf_conntrack_alter_reply(ct, &new_tuple);
IP_VS_DBG_BUF(7, "%s: Updated conntrack ct=%p for cp=" FMT_CONN "\n",
__func__, ct, ARG_CONN(cp));
}
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);
/*
* 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_ipvs(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 */
IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found inout cp="
FMT_CONN "\n",
__func__, ct, ct->status, ARG_CONN(cp));
new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
IP_VS_DBG_BUF(7, "%s: ct=%p before alter: reply tuple="
FMT_TUPLE "\n",
__func__, ct, ARG_TUPLE(&new_reply));
new_reply.dst.u3 = cp->vaddr;
new_reply.dst.u.tcp.port = cp->vport;
goto alter;
}
/* CLIENT->VS */
cp = ip_vs_conn_in_get(&p);
if (cp) {
/* Change reply VS->CLIENT to RS->CLIENT */
IP_VS_DBG_BUF(7, "%s: for ct=%p, status=0x%lX found outin cp="
FMT_CONN "\n",
__func__, ct, ct->status, ARG_CONN(cp));
new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple;
IP_VS_DBG_BUF(7, "%s: ct=%p before alter: reply tuple="
FMT_TUPLE "\n",
__func__, ct, ARG_TUPLE(&new_reply));
new_reply.src.u3 = cp->daddr;
new_reply.src.u.tcp.port = cp->dport;
goto alter;
}
IP_VS_DBG_BUF(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)
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_BUF(7, "%s: ct=%p, expect tuple=" FMT_TUPLE "\n",
__func__, ct, ARG_TUPLE(&exp->tuple));
nf_ct_expect_related(exp, 0);
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_BUF(7, "%s: dropping conntrack for conn " FMT_CONN "\n",
__func__, ARG_CONN(cp));
h = nf_conntrack_find_get(cp->ipvs->net, &nf_ct_zone_dflt, &tuple);
if (h) {
ct = nf_ct_tuplehash_to_ctrack(h);
if (nf_ct_kill(ct)) {
IP_VS_DBG_BUF(7, "%s: ct=%p deleted for tuple="
FMT_TUPLE "\n",
__func__, ct, ARG_TUPLE(&tuple));
} else {
IP_VS_DBG_BUF(7, "%s: ct=%p, no conntrack for tuple="
FMT_TUPLE "\n",
__func__, ct, ARG_TUPLE(&tuple));
}
nf_ct_put(ct);
} else {
IP_VS_DBG_BUF(7, "%s: no conntrack for tuple=" FMT_TUPLE "\n",
__func__, ARG_TUPLE(&tuple));
}
}
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