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 <linux/gfp.h>
36 #include <net/protocol.h>
38 #include <asm/unaligned.h>
40 #include <net/ip_vs.h>
43 #define SERVER_STRING "227 Entering Passive Mode ("
44 #define CLIENT_STRING "PORT "
48 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
49 * First port is set to the default port.
51 static unsigned short ports
[IP_VS_APP_MAX_PORTS
] = {21, 0};
52 module_param_array(ports
, ushort
, NULL
, 0);
53 MODULE_PARM_DESC(ports
, "Ports to monitor for FTP control commands");
57 static int ip_vs_ftp_pasv
;
61 ip_vs_ftp_init_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
68 ip_vs_ftp_done_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
75 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
76 * with the "pattern" and terminated with the "term" character.
77 * <addr,port> is in network order.
79 static int ip_vs_ftp_get_addrport(char *data
, char *data_limit
,
80 const char *pattern
, size_t plen
, char term
,
81 __be32
*addr
, __be16
*port
,
82 char **start
, char **end
)
87 if (data_limit
- data
< plen
) {
88 /* check if there is partial match */
89 if (strnicmp(data
, pattern
, data_limit
- data
) == 0)
95 if (strnicmp(data
, pattern
, plen
) != 0) {
100 for (data
= *start
; *data
!= term
; data
++) {
101 if (data
== data_limit
)
106 memset(p
, 0, sizeof(p
));
107 for (data
= *start
; data
!= *end
; data
++) {
108 if (*data
>= '0' && *data
<= '9') {
109 p
[i
] = p
[i
]*10 + *data
- '0';
110 } else if (*data
== ',' && i
< 5) {
113 /* unexpected character */
121 *addr
= get_unaligned((__be32
*)p
);
122 *port
= get_unaligned((__be16
*)(p
+ 4));
128 * Look at outgoing ftp packets to catch the response to a PASV command
129 * from the server (inside-to-outside).
130 * When we see one, we build a connection entry with the client address,
131 * client port 0 (unknown at the moment), the server address and the
132 * server port. Mark the current connection entry as a control channel
133 * of the new entry. All this work is just to make the data connection
134 * can be scheduled to the right server later.
136 * The outgoing packet should be something like
137 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
138 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
140 static int ip_vs_ftp_out(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
141 struct sk_buff
*skb
, int *diff
)
145 char *data
, *data_limit
;
147 union nf_inet_addr from
;
149 struct ip_vs_conn
*n_cp
;
150 char buf
[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
154 #ifdef CONFIG_IP_VS_IPV6
155 /* This application helper doesn't work with IPv6 yet,
156 * so turn this into a no-op for IPv6 packets
158 if (cp
->af
== AF_INET6
)
164 /* Only useful for established sessions */
165 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
168 /* Linear packets are much easier to deal with. */
169 if (!skb_make_writable(skb
, skb
->len
))
172 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
174 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
175 data
= (char *)th
+ (th
->doff
<< 2);
176 data_limit
= skb_tail_pointer(skb
);
178 if (ip_vs_ftp_get_addrport(data
, data_limit
,
180 sizeof(SERVER_STRING
)-1, ')',
185 IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
186 &from
.ip
, ntohs(port
), &cp
->caddr
.ip
, 0);
189 * Now update or create an connection entry for it
191 n_cp
= ip_vs_conn_out_get(AF_INET
, iph
->protocol
, &from
, port
,
194 n_cp
= ip_vs_conn_new(AF_INET
, IPPROTO_TCP
,
198 IP_VS_CONN_F_NO_CPORT
,
203 /* add its controller */
204 ip_vs_control_add(n_cp
, cp
);
208 * Replace the old passive address with the new one
210 from
.ip
= n_cp
->vaddr
.ip
;
212 snprintf(buf
, sizeof(buf
), "%u,%u,%u,%u,%u,%u",
213 ((unsigned char *)&from
.ip
)[0],
214 ((unsigned char *)&from
.ip
)[1],
215 ((unsigned char *)&from
.ip
)[2],
216 ((unsigned char *)&from
.ip
)[3],
220 buf_len
= strlen(buf
);
223 * Calculate required delta-offset to keep TCP happy
225 *diff
= buf_len
- (end
-start
);
228 /* simply replace it with new passive address */
229 memcpy(start
, buf
, buf_len
);
232 ret
= !ip_vs_skb_replace(skb
, GFP_ATOMIC
, start
,
233 end
-start
, buf
, buf_len
);
237 ip_vs_tcp_conn_listen(n_cp
);
238 ip_vs_conn_put(n_cp
);
246 * Look at incoming ftp packets to catch the PASV/PORT command
247 * (outside-to-inside).
249 * The incoming packet having the PORT command should be something like
250 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
251 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
252 * In this case, we create a connection entry using the client address and
253 * port, so that the active ftp data connection from the server can reach
256 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
257 struct sk_buff
*skb
, int *diff
)
261 char *data
, *data_start
, *data_limit
;
263 union nf_inet_addr to
;
265 struct ip_vs_conn
*n_cp
;
267 #ifdef CONFIG_IP_VS_IPV6
268 /* This application helper doesn't work with IPv6 yet,
269 * so turn this into a no-op for IPv6 packets
271 if (cp
->af
== AF_INET6
)
275 /* no diff required for incoming packets */
278 /* Only useful for established sessions */
279 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
282 /* Linear packets are much easier to deal with. */
283 if (!skb_make_writable(skb
, skb
->len
))
287 * Detecting whether it is passive
290 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
292 /* Since there may be OPTIONS in the TCP packet and the HLEN is
293 the length of the header in 32-bit multiples, it is accurate
294 to calculate data address by th+HLEN*4 */
295 data
= data_start
= (char *)th
+ (th
->doff
<< 2);
296 data_limit
= skb_tail_pointer(skb
);
298 while (data
<= data_limit
- 6) {
299 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
300 /* Passive mode on */
301 IP_VS_DBG(7, "got PASV at %td of %td\n",
303 data_limit
- data_start
);
304 cp
->app_data
= &ip_vs_ftp_pasv
;
311 * To support virtual FTP server, the scenerio is as follows:
312 * FTP client ----> Load Balancer ----> FTP server
313 * First detect the port number in the application data,
314 * then create a new connection entry for the coming data
317 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
318 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
323 IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to
.ip
, ntohs(port
));
325 /* Passive mode off */
329 * Now update or create a connection entry for it
331 IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
332 ip_vs_proto_name(iph
->protocol
),
333 &to
.ip
, ntohs(port
), &cp
->vaddr
.ip
, 0);
335 n_cp
= ip_vs_conn_in_get(AF_INET
, iph
->protocol
,
337 &cp
->vaddr
, htons(ntohs(cp
->vport
)-1));
339 n_cp
= ip_vs_conn_new(AF_INET
, IPPROTO_TCP
,
341 &cp
->vaddr
, htons(ntohs(cp
->vport
)-1),
342 &cp
->daddr
, htons(ntohs(cp
->dport
)-1),
348 /* add its controller */
349 ip_vs_control_add(n_cp
, cp
);
353 * Move tunnel to listen state
355 ip_vs_tcp_conn_listen(n_cp
);
356 ip_vs_conn_put(n_cp
);
362 static struct ip_vs_app ip_vs_ftp
= {
364 .type
= IP_VS_APP_TYPE_FTP
,
365 .protocol
= IPPROTO_TCP
,
366 .module
= THIS_MODULE
,
367 .incs_list
= LIST_HEAD_INIT(ip_vs_ftp
.incs_list
),
368 .init_conn
= ip_vs_ftp_init_conn
,
369 .done_conn
= ip_vs_ftp_done_conn
,
372 .pkt_out
= ip_vs_ftp_out
,
373 .pkt_in
= ip_vs_ftp_in
,
378 * ip_vs_ftp initialization
380 static int __init
ip_vs_ftp_init(void)
383 struct ip_vs_app
*app
= &ip_vs_ftp
;
385 ret
= register_ip_vs_app(app
);
389 for (i
=0; i
<IP_VS_APP_MAX_PORTS
; i
++) {
392 ret
= register_ip_vs_app_inc(app
, app
->protocol
, ports
[i
]);
395 pr_info("%s: loaded support on port[%d] = %d\n",
396 app
->name
, i
, ports
[i
]);
400 unregister_ip_vs_app(app
);
409 static void __exit
ip_vs_ftp_exit(void)
411 unregister_ip_vs_app(&ip_vs_ftp
);
415 module_init(ip_vs_ftp_init
);
416 module_exit(ip_vs_ftp_exit
);
417 MODULE_LICENSE("GPL");