2 * ip_vs_ftp.c: IPVS ftp application module
4 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
9 * This program is free software; you can redistribute it and/or
10 * modify it under the terms of the GNU General Public License
11 * as published by the Free Software Foundation; either version
12 * 2 of the License, or (at your option) any later version.
14 * Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference
15 * is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp.
17 * IP_MASQ_FTP ftp masquerading module
19 * Version: @(#)ip_masq_ftp.c 0.04 02/05/96
21 * Author: Wouter Gadeyne
25 #define KMSG_COMPONENT "IPVS"
26 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
28 #include <linux/module.h>
29 #include <linux/moduleparam.h>
30 #include <linux/kernel.h>
31 #include <linux/skbuff.h>
34 #include <linux/netfilter.h>
35 #include <net/netfilter/nf_conntrack.h>
36 #include <net/netfilter/nf_conntrack_expect.h>
37 #include <net/netfilter/nf_nat.h>
38 #include <net/netfilter/nf_nat_helper.h>
39 #include <linux/gfp.h>
40 #include <net/protocol.h>
42 #include <asm/unaligned.h>
44 #include <net/ip_vs.h>
47 #define SERVER_STRING "227 "
48 #define CLIENT_STRING "PORT"
52 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
53 * First port is set to the default port.
55 static unsigned int ports_count
= 1;
56 static unsigned short ports
[IP_VS_APP_MAX_PORTS
] = {21, 0};
57 module_param_array(ports
, ushort
, &ports_count
, 0444);
58 MODULE_PARM_DESC(ports
, "Ports to monitor for FTP control commands");
62 static int ip_vs_ftp_pasv
;
66 ip_vs_ftp_init_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
68 /* We use connection tracking for the command connection */
69 cp
->flags
|= IP_VS_CONN_F_NFCT
;
75 ip_vs_ftp_done_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
82 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
83 * with the "pattern", ignoring before "skip" and terminated with
84 * the "term" character.
85 * <addr,port> is in network order.
87 static int ip_vs_ftp_get_addrport(char *data
, char *data_limit
,
88 const char *pattern
, size_t plen
,
90 __be32
*addr
, __be16
*port
,
91 char **start
, char **end
)
97 if (data_limit
- data
< plen
) {
98 /* check if there is partial match */
99 if (strnicmp(data
, pattern
, data_limit
- data
) == 0)
105 if (strnicmp(data
, pattern
, plen
) != 0) {
118 } else if (*s
!= skip
) {
124 for (data
= s
; ; data
++) {
125 if (data
== data_limit
)
132 memset(p
, 0, sizeof(p
));
133 for (data
= s
; ; data
++) {
137 if (c
>= '0' && c
<= '9') {
138 p
[i
] = p
[i
]*10 + c
- '0';
139 } else if (c
== ',' && i
< 5) {
142 /* unexpected character */
151 *addr
= get_unaligned((__be32
*) p
);
152 *port
= get_unaligned((__be16
*) (p
+ 4));
157 * Look at outgoing ftp packets to catch the response to a PASV command
158 * from the server (inside-to-outside).
159 * When we see one, we build a connection entry with the client address,
160 * client port 0 (unknown at the moment), the server address and the
161 * server port. Mark the current connection entry as a control channel
162 * of the new entry. All this work is just to make the data connection
163 * can be scheduled to the right server later.
165 * The outgoing packet should be something like
166 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
167 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
169 static int ip_vs_ftp_out(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
170 struct sk_buff
*skb
, int *diff
)
174 char *data
, *data_limit
;
176 union nf_inet_addr from
;
178 struct ip_vs_conn
*n_cp
;
179 char buf
[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
180 unsigned int buf_len
;
182 enum ip_conntrack_info ctinfo
;
186 #ifdef CONFIG_IP_VS_IPV6
187 /* This application helper doesn't work with IPv6 yet,
188 * so turn this into a no-op for IPv6 packets
190 if (cp
->af
== AF_INET6
)
196 /* Only useful for established sessions */
197 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
200 /* Linear packets are much easier to deal with. */
201 if (!skb_make_writable(skb
, skb
->len
))
204 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
206 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
207 data
= (char *)th
+ (th
->doff
<< 2);
208 data_limit
= skb_tail_pointer(skb
);
210 if (ip_vs_ftp_get_addrport(data
, data_limit
,
212 sizeof(SERVER_STRING
)-1,
218 IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
219 &from
.ip
, ntohs(port
), &cp
->caddr
.ip
, 0);
222 * Now update or create an connection entry for it
225 struct ip_vs_conn_param p
;
226 ip_vs_conn_fill_param(ip_vs_conn_net(cp
), AF_INET
,
227 iph
->protocol
, &from
, port
,
229 n_cp
= ip_vs_conn_out_get(&p
);
232 struct ip_vs_conn_param p
;
233 ip_vs_conn_fill_param(ip_vs_conn_net(cp
),
234 AF_INET
, IPPROTO_TCP
, &cp
->caddr
,
235 0, &cp
->vaddr
, port
, &p
);
236 n_cp
= ip_vs_conn_new(&p
, &from
, port
,
237 IP_VS_CONN_F_NO_CPORT
|
239 cp
->dest
, skb
->mark
);
243 /* add its controller */
244 ip_vs_control_add(n_cp
, cp
);
248 * Replace the old passive address with the new one
250 from
.ip
= n_cp
->vaddr
.ip
;
252 snprintf(buf
, sizeof(buf
), "%u,%u,%u,%u,%u,%u",
253 ((unsigned char *)&from
.ip
)[0],
254 ((unsigned char *)&from
.ip
)[1],
255 ((unsigned char *)&from
.ip
)[2],
256 ((unsigned char *)&from
.ip
)[3],
260 buf_len
= strlen(buf
);
262 ct
= nf_ct_get(skb
, &ctinfo
);
263 if (ct
&& !nf_ct_is_untracked(ct
) && nfct_nat(ct
)) {
264 /* If mangling fails this function will return 0
265 * which will cause the packet to be dropped.
266 * Mangling can only fail under memory pressure,
267 * hopefully it will succeed on the retransmitted
270 ret
= nf_nat_mangle_tcp_packet(skb
, ct
, ctinfo
,
272 start
-data
, end
-start
,
275 ip_vs_nfct_expect_related(skb
, ct
, n_cp
,
277 if (skb
->ip_summed
== CHECKSUM_COMPLETE
)
278 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
279 /* csum is updated */
285 * Not setting 'diff' is intentional, otherwise the sequence
286 * would be adjusted twice.
291 ip_vs_tcp_conn_listen(net
, n_cp
);
292 ip_vs_conn_put(n_cp
);
300 * Look at incoming ftp packets to catch the PASV/PORT command
301 * (outside-to-inside).
303 * The incoming packet having the PORT command should be something like
304 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
305 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
306 * In this case, we create a connection entry using the client address and
307 * port, so that the active ftp data connection from the server can reach
310 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
311 struct sk_buff
*skb
, int *diff
)
315 char *data
, *data_start
, *data_limit
;
317 union nf_inet_addr to
;
319 struct ip_vs_conn
*n_cp
;
322 #ifdef CONFIG_IP_VS_IPV6
323 /* This application helper doesn't work with IPv6 yet,
324 * so turn this into a no-op for IPv6 packets
326 if (cp
->af
== AF_INET6
)
330 /* no diff required for incoming packets */
333 /* Only useful for established sessions */
334 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
337 /* Linear packets are much easier to deal with. */
338 if (!skb_make_writable(skb
, skb
->len
))
342 * Detecting whether it is passive
345 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
347 /* Since there may be OPTIONS in the TCP packet and the HLEN is
348 the length of the header in 32-bit multiples, it is accurate
349 to calculate data address by th+HLEN*4 */
350 data
= data_start
= (char *)th
+ (th
->doff
<< 2);
351 data_limit
= skb_tail_pointer(skb
);
353 while (data
<= data_limit
- 6) {
354 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
355 /* Passive mode on */
356 IP_VS_DBG(7, "got PASV at %td of %td\n",
358 data_limit
- data_start
);
359 cp
->app_data
= &ip_vs_ftp_pasv
;
366 * To support virtual FTP server, the scenerio is as follows:
367 * FTP client ----> Load Balancer ----> FTP server
368 * First detect the port number in the application data,
369 * then create a new connection entry for the coming data
372 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
373 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
374 ' ', '\r', &to
.ip
, &port
,
378 IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to
.ip
, ntohs(port
));
380 /* Passive mode off */
384 * Now update or create a connection entry for it
386 IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
387 ip_vs_proto_name(iph
->protocol
),
388 &to
.ip
, ntohs(port
), &cp
->vaddr
.ip
, 0);
391 struct ip_vs_conn_param p
;
392 ip_vs_conn_fill_param(ip_vs_conn_net(cp
), AF_INET
,
393 iph
->protocol
, &to
, port
, &cp
->vaddr
,
394 htons(ntohs(cp
->vport
)-1), &p
);
395 n_cp
= ip_vs_conn_in_get(&p
);
397 n_cp
= ip_vs_conn_new(&p
, &cp
->daddr
,
398 htons(ntohs(cp
->dport
)-1),
399 IP_VS_CONN_F_NFCT
, cp
->dest
,
404 /* add its controller */
405 ip_vs_control_add(n_cp
, cp
);
410 * Move tunnel to listen state
413 ip_vs_tcp_conn_listen(net
, n_cp
);
414 ip_vs_conn_put(n_cp
);
420 static struct ip_vs_app ip_vs_ftp
= {
422 .type
= IP_VS_APP_TYPE_FTP
,
423 .protocol
= IPPROTO_TCP
,
424 .module
= THIS_MODULE
,
425 .incs_list
= LIST_HEAD_INIT(ip_vs_ftp
.incs_list
),
426 .init_conn
= ip_vs_ftp_init_conn
,
427 .done_conn
= ip_vs_ftp_done_conn
,
430 .pkt_out
= ip_vs_ftp_out
,
431 .pkt_in
= ip_vs_ftp_in
,
435 * per netns ip_vs_ftp initialization
437 static int __net_init
__ip_vs_ftp_init(struct net
*net
)
440 struct ip_vs_app
*app
;
441 struct netns_ipvs
*ipvs
= net_ipvs(net
);
446 app
= register_ip_vs_app(net
, &ip_vs_ftp
);
450 for (i
= 0; i
< ports_count
; i
++) {
453 ret
= register_ip_vs_app_inc(net
, app
, app
->protocol
, ports
[i
]);
456 pr_info("%s: loaded support on port[%d] = %d\n",
457 app
->name
, i
, ports
[i
]);
462 unregister_ip_vs_app(net
, &ip_vs_ftp
);
468 static void __ip_vs_ftp_exit(struct net
*net
)
470 unregister_ip_vs_app(net
, &ip_vs_ftp
);
473 static struct pernet_operations ip_vs_ftp_ops
= {
474 .init
= __ip_vs_ftp_init
,
475 .exit
= __ip_vs_ftp_exit
,
478 static int __init
ip_vs_ftp_init(void)
482 rv
= register_pernet_subsys(&ip_vs_ftp_ops
);
483 /* rcu_barrier() is called by netns on error */
490 static void __exit
ip_vs_ftp_exit(void)
492 unregister_pernet_subsys(&ip_vs_ftp_ops
);
493 /* rcu_barrier() is called by netns */
497 module_init(ip_vs_ftp_init
);
498 module_exit(ip_vs_ftp_exit
);
499 MODULE_LICENSE("GPL");