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 #include <linux/module.h>
26 #include <linux/moduleparam.h>
27 #include <linux/kernel.h>
28 #include <linux/skbuff.h>
31 #include <linux/netfilter.h>
32 #include <net/protocol.h>
34 #include <asm/unaligned.h>
36 #include <net/ip_vs.h>
39 #define SERVER_STRING "227 Entering Passive Mode ("
40 #define CLIENT_STRING "PORT "
44 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
45 * First port is set to the default port.
47 static unsigned short ports
[IP_VS_APP_MAX_PORTS
] = {21, 0};
48 module_param_array(ports
, ushort
, NULL
, 0);
49 MODULE_PARM_DESC(ports
, "Ports to monitor for FTP control commands");
53 static int ip_vs_ftp_pasv
;
57 ip_vs_ftp_init_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
64 ip_vs_ftp_done_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
71 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
72 * with the "pattern" and terminated with the "term" character.
73 * <addr,port> is in network order.
75 static int ip_vs_ftp_get_addrport(char *data
, char *data_limit
,
76 const char *pattern
, size_t plen
, char term
,
77 __be32
*addr
, __be16
*port
,
78 char **start
, char **end
)
83 if (data_limit
- data
< plen
) {
84 /* check if there is partial match */
85 if (strnicmp(data
, pattern
, data_limit
- data
) == 0)
91 if (strnicmp(data
, pattern
, plen
) != 0) {
96 for (data
= *start
; *data
!= term
; data
++) {
97 if (data
== data_limit
)
102 memset(p
, 0, sizeof(p
));
103 for (data
= *start
; data
!= *end
; data
++) {
104 if (*data
>= '0' && *data
<= '9') {
105 p
[i
] = p
[i
]*10 + *data
- '0';
106 } else if (*data
== ',' && i
< 5) {
109 /* unexpected character */
117 *addr
= get_unaligned((__be32
*)p
);
118 *port
= get_unaligned((__be16
*)(p
+ 4));
124 * Look at outgoing ftp packets to catch the response to a PASV command
125 * from the server (inside-to-outside).
126 * When we see one, we build a connection entry with the client address,
127 * client port 0 (unknown at the moment), the server address and the
128 * server port. Mark the current connection entry as a control channel
129 * of the new entry. All this work is just to make the data connection
130 * can be scheduled to the right server later.
132 * The outgoing packet should be something like
133 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
134 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
136 static int ip_vs_ftp_out(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
137 struct sk_buff
*skb
, int *diff
)
141 char *data
, *data_limit
;
145 struct ip_vs_conn
*n_cp
;
146 char buf
[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
152 /* Only useful for established sessions */
153 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
156 /* Linear packets are much easier to deal with. */
157 if (!skb_make_writable(skb
, skb
->len
))
160 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
162 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
163 data
= (char *)th
+ (th
->doff
<< 2);
164 data_limit
= skb_tail_pointer(skb
);
166 if (ip_vs_ftp_get_addrport(data
, data_limit
,
168 sizeof(SERVER_STRING
)-1, ')',
173 IP_VS_DBG(7, "PASV response (%u.%u.%u.%u:%d) -> "
174 "%u.%u.%u.%u:%d detected\n",
175 NIPQUAD(from
), ntohs(port
), NIPQUAD(cp
->caddr
), 0);
178 * Now update or create an connection entry for it
180 n_cp
= ip_vs_conn_out_get(iph
->protocol
, from
, port
,
183 n_cp
= ip_vs_conn_new(IPPROTO_TCP
,
187 IP_VS_CONN_F_NO_CPORT
,
192 /* add its controller */
193 ip_vs_control_add(n_cp
, cp
);
197 * Replace the old passive address with the new one
201 sprintf(buf
,"%d,%d,%d,%d,%d,%d", NIPQUAD(from
),
202 (ntohs(port
)>>8)&255, ntohs(port
)&255);
203 buf_len
= strlen(buf
);
206 * Calculate required delta-offset to keep TCP happy
208 *diff
= buf_len
- (end
-start
);
211 /* simply replace it with new passive address */
212 memcpy(start
, buf
, buf_len
);
215 ret
= !ip_vs_skb_replace(skb
, GFP_ATOMIC
, start
,
216 end
-start
, buf
, buf_len
);
220 ip_vs_tcp_conn_listen(n_cp
);
221 ip_vs_conn_put(n_cp
);
229 * Look at incoming ftp packets to catch the PASV/PORT command
230 * (outside-to-inside).
232 * The incoming packet having the PORT command should be something like
233 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
234 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
235 * In this case, we create a connection entry using the client address and
236 * port, so that the active ftp data connection from the server can reach
239 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
240 struct sk_buff
*skb
, int *diff
)
244 char *data
, *data_start
, *data_limit
;
248 struct ip_vs_conn
*n_cp
;
250 /* no diff required for incoming packets */
253 /* Only useful for established sessions */
254 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
257 /* Linear packets are much easier to deal with. */
258 if (!skb_make_writable(skb
, skb
->len
))
262 * Detecting whether it is passive
265 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
267 /* Since there may be OPTIONS in the TCP packet and the HLEN is
268 the length of the header in 32-bit multiples, it is accurate
269 to calculate data address by th+HLEN*4 */
270 data
= data_start
= (char *)th
+ (th
->doff
<< 2);
271 data_limit
= skb_tail_pointer(skb
);
273 while (data
<= data_limit
- 6) {
274 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
275 /* Passive mode on */
276 IP_VS_DBG(7, "got PASV at %td of %td\n",
278 data_limit
- data_start
);
279 cp
->app_data
= &ip_vs_ftp_pasv
;
286 * To support virtual FTP server, the scenerio is as follows:
287 * FTP client ----> Load Balancer ----> FTP server
288 * First detect the port number in the application data,
289 * then create a new connection entry for the coming data
292 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
293 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
298 IP_VS_DBG(7, "PORT %u.%u.%u.%u:%d detected\n",
299 NIPQUAD(to
), ntohs(port
));
301 /* Passive mode off */
305 * Now update or create a connection entry for it
307 IP_VS_DBG(7, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
308 ip_vs_proto_name(iph
->protocol
),
309 NIPQUAD(to
), ntohs(port
), NIPQUAD(cp
->vaddr
), 0);
311 n_cp
= ip_vs_conn_in_get(iph
->protocol
,
313 cp
->vaddr
, htons(ntohs(cp
->vport
)-1));
315 n_cp
= ip_vs_conn_new(IPPROTO_TCP
,
317 cp
->vaddr
, htons(ntohs(cp
->vport
)-1),
318 cp
->daddr
, htons(ntohs(cp
->dport
)-1),
324 /* add its controller */
325 ip_vs_control_add(n_cp
, cp
);
329 * Move tunnel to listen state
331 ip_vs_tcp_conn_listen(n_cp
);
332 ip_vs_conn_put(n_cp
);
338 static struct ip_vs_app ip_vs_ftp
= {
340 .type
= IP_VS_APP_TYPE_FTP
,
341 .protocol
= IPPROTO_TCP
,
342 .module
= THIS_MODULE
,
343 .incs_list
= LIST_HEAD_INIT(ip_vs_ftp
.incs_list
),
344 .init_conn
= ip_vs_ftp_init_conn
,
345 .done_conn
= ip_vs_ftp_done_conn
,
348 .pkt_out
= ip_vs_ftp_out
,
349 .pkt_in
= ip_vs_ftp_in
,
354 * ip_vs_ftp initialization
356 static int __init
ip_vs_ftp_init(void)
359 struct ip_vs_app
*app
= &ip_vs_ftp
;
361 ret
= register_ip_vs_app(app
);
365 for (i
=0; i
<IP_VS_APP_MAX_PORTS
; i
++) {
368 ret
= register_ip_vs_app_inc(app
, app
->protocol
, ports
[i
]);
371 IP_VS_INFO("%s: loaded support on port[%d] = %d\n",
372 app
->name
, i
, ports
[i
]);
376 unregister_ip_vs_app(app
);
385 static void __exit
ip_vs_ftp_exit(void)
387 unregister_ip_vs_app(&ip_vs_ftp
);
391 module_init(ip_vs_ftp_init
);
392 module_exit(ip_vs_ftp_exit
);
393 MODULE_LICENSE("GPL");
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