2 * ip_vs_ftp.c: IPVS ftp application module
4 * Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
11 * This program is free software; you can redistribute it and/or
12 * modify it under the terms of the GNU General Public License
13 * as published by the Free Software Foundation; either version
14 * 2 of the License, or (at your option) any later version.
16 * Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference
17 * is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp.
19 * IP_MASQ_FTP ftp masquerading module
21 * Version: @(#)ip_masq_ftp.c 0.04 02/05/96
23 * Author: Wouter Gadeyne
27 #include <linux/module.h>
28 #include <linux/moduleparam.h>
29 #include <linux/kernel.h>
30 #include <linux/skbuff.h>
33 #include <net/protocol.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 int ports[IP_VS_APP_MAX_PORTS] = {21, 0};
48 module_param_array(ports, int, NULL, 0);
49 MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands");
54 #ifdef CONFIG_IP_VS_DEBUG
56 module_param(debug, int, 0);
61 static int ip_vs_ftp_pasv;
65 ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
72 ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
79 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
80 * with the "pattern" and terminated with the "term" character.
81 * <addr,port> is in network order.
83 static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
84 const char *pattern, size_t plen, char term,
85 __u32 *addr, __u16 *port,
86 char **start, char **end)
91 if (data_limit - data < plen) {
92 /* check if there is partial match */
93 if (strnicmp(data, pattern, data_limit - data) == 0)
99 if (strnicmp(data, pattern, plen) != 0) {
102 *start = data + plen;
104 for (data = *start; *data != term; data++) {
105 if (data == data_limit)
110 memset(p, 0, sizeof(p));
111 for (data = *start; data != *end; data++) {
112 if (*data >= '0' && *data <= '9') {
113 p[i] = p[i]*10 + *data - '0';
114 } else if (*data == ',' && i < 5) {
117 /* unexpected character */
125 *addr = (p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0];
126 *port = (p[5]<<8) | p[4];
132 * Look at outgoing ftp packets to catch the response to a PASV command
133 * from the server (inside-to-outside).
134 * When we see one, we build a connection entry with the client address,
135 * client port 0 (unknown at the moment), the server address and the
136 * server port. Mark the current connection entry as a control channel
137 * of the new entry. All this work is just to make the data connection
138 * can be scheduled to the right server later.
140 * The outgoing packet should be something like
141 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
142 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
144 static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
145 struct sk_buff **pskb, int *diff)
149 char *data, *data_limit;
153 struct ip_vs_conn *n_cp;
154 char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
160 /* Only useful for established sessions */
161 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
164 /* Linear packets are much easier to deal with. */
165 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
168 if (cp->app_data == &ip_vs_ftp_pasv) {
169 iph = (*pskb)->nh.iph;
170 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
171 data = (char *)th + (th->doff << 2);
172 data_limit = (*pskb)->tail;
174 if (ip_vs_ftp_get_addrport(data, data_limit,
176 sizeof(SERVER_STRING)-1, ')',
181 IP_VS_DBG(1-debug, "PASV response (%u.%u.%u.%u:%d) -> "
182 "%u.%u.%u.%u:%d detected\n",
183 NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0);
186 * Now update or create an connection entry for it
188 n_cp = ip_vs_conn_out_get(iph->protocol, from, port,
191 n_cp = ip_vs_conn_new(IPPROTO_TCP,
195 IP_VS_CONN_F_NO_CPORT,
200 /* add its controller */
201 ip_vs_control_add(n_cp, cp);
205 * Replace the old passive address with the new one
209 sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from),
210 port&255, (port>>8)&255);
211 buf_len = strlen(buf);
214 * Calculate required delta-offset to keep TCP happy
216 *diff = buf_len - (end-start);
219 /* simply replace it with new passive address */
220 memcpy(start, buf, buf_len);
223 ret = !ip_vs_skb_replace(*pskb, GFP_ATOMIC, start,
224 end-start, buf, buf_len);
228 ip_vs_tcp_conn_listen(n_cp);
229 ip_vs_conn_put(n_cp);
237 * Look at incoming ftp packets to catch the PASV/PORT command
238 * (outside-to-inside).
240 * The incoming packet having the PORT command should be something like
241 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
242 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
243 * In this case, we create a connection entry using the client address and
244 * port, so that the active ftp data connection from the server can reach
247 static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
248 struct sk_buff **pskb, int *diff)
252 char *data, *data_start, *data_limit;
256 struct ip_vs_conn *n_cp;
258 /* no diff required for incoming packets */
261 /* Only useful for established sessions */
262 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
265 /* Linear packets are much easier to deal with. */
266 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
270 * Detecting whether it is passive
272 iph = (*pskb)->nh.iph;
273 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
275 /* Since there may be OPTIONS in the TCP packet and the HLEN is
276 the length of the header in 32-bit multiples, it is accurate
277 to calculate data address by th+HLEN*4 */
278 data = data_start = (char *)th + (th->doff << 2);
279 data_limit = (*pskb)->tail;
281 while (data <= data_limit - 6) {
282 if (strnicmp(data, "PASV\r\n", 6) == 0) {
283 /* Passive mode on */
284 IP_VS_DBG(1-debug, "got PASV at %zd of %zd\n",
286 data_limit - data_start);
287 cp->app_data = &ip_vs_ftp_pasv;
294 * To support virtual FTP server, the scenerio is as follows:
295 * FTP client ----> Load Balancer ----> FTP server
296 * First detect the port number in the application data,
297 * then create a new connection entry for the coming data
300 if (ip_vs_ftp_get_addrport(data_start, data_limit,
301 CLIENT_STRING, sizeof(CLIENT_STRING)-1,
306 IP_VS_DBG(1-debug, "PORT %u.%u.%u.%u:%d detected\n",
307 NIPQUAD(to), ntohs(port));
309 /* Passive mode off */
313 * Now update or create a connection entry for it
315 IP_VS_DBG(1-debug, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
316 ip_vs_proto_name(iph->protocol),
317 NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0);
319 n_cp = ip_vs_conn_in_get(iph->protocol,
321 cp->vaddr, htons(ntohs(cp->vport)-1));
323 n_cp = ip_vs_conn_new(IPPROTO_TCP,
325 cp->vaddr, htons(ntohs(cp->vport)-1),
326 cp->daddr, htons(ntohs(cp->dport)-1),
332 /* add its controller */
333 ip_vs_control_add(n_cp, cp);
337 * Move tunnel to listen state
339 ip_vs_tcp_conn_listen(n_cp);
340 ip_vs_conn_put(n_cp);
346 static struct ip_vs_app ip_vs_ftp = {
348 .type = IP_VS_APP_TYPE_FTP,
349 .protocol = IPPROTO_TCP,
350 .module = THIS_MODULE,
351 .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
352 .init_conn = ip_vs_ftp_init_conn,
353 .done_conn = ip_vs_ftp_done_conn,
356 .pkt_out = ip_vs_ftp_out,
357 .pkt_in = ip_vs_ftp_in,
362 * ip_vs_ftp initialization
364 static int __init ip_vs_ftp_init(void)
367 struct ip_vs_app *app = &ip_vs_ftp;
369 ret = register_ip_vs_app(app);
373 for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
376 if (ports[i] < 0 || ports[i] > 0xffff) {
377 IP_VS_WARNING("ip_vs_ftp: Ignoring invalid "
378 "configuration port[%d] = %d\n",
382 ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
385 IP_VS_DBG(1-debug, "%s: loaded support on port[%d] = %d\n",
386 app->name, i, ports[i]);
390 unregister_ip_vs_app(app);
399 static void __exit ip_vs_ftp_exit(void)
401 unregister_ip_vs_app(&ip_vs_ftp);
405 module_init(ip_vs_ftp_init);
406 module_exit(ip_vs_ftp_exit);
407 MODULE_LICENSE("GPL");