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Linus Torvalds1da177e2005-04-16 15:20:36 -07001/*
2 * ip_vs_ftp.c: IPVS ftp application module
3 *
4 * Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $
5 *
6 * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
7 *
8 * Changes:
9 *
10 *
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.
15 *
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.
18 *
19 * IP_MASQ_FTP ftp masquerading module
20 *
21 * Version: @(#)ip_masq_ftp.c 0.04 02/05/96
22 *
23 * Author: Wouter Gadeyne
24 *
25 */
26
27#include <linux/module.h>
28#include <linux/moduleparam.h>
29#include <linux/kernel.h>
30#include <linux/skbuff.h>
31#include <linux/in.h>
32#include <linux/ip.h>
33#include <net/protocol.h>
34#include <net/tcp.h>
Al Viro96d2ca42006-09-28 14:31:49 -070035#include <asm/unaligned.h>
Linus Torvalds1da177e2005-04-16 15:20:36 -070036
37#include <net/ip_vs.h>
38
39
40#define SERVER_STRING "227 Entering Passive Mode ("
41#define CLIENT_STRING "PORT "
42
43
44/*
45 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
46 * First port is set to the default port.
47 */
Simon Horman28b06c32006-09-27 22:53:24 -070048static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0};
49module_param_array(ports, ushort, NULL, 0);
Simon Horman70e76b72006-09-13 19:57:54 -070050MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands");
Linus Torvalds1da177e2005-04-16 15:20:36 -070051
Linus Torvalds1da177e2005-04-16 15:20:36 -070052
53/* Dummy variable */
54static int ip_vs_ftp_pasv;
55
56
57static int
58ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
59{
60 return 0;
61}
62
63
64static int
65ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
66{
67 return 0;
68}
69
70
71/*
72 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
73 * with the "pattern" and terminated with the "term" character.
74 * <addr,port> is in network order.
75 */
76static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
77 const char *pattern, size_t plen, char term,
Al Viro014d7302006-09-28 14:29:52 -070078 __be32 *addr, __be16 *port,
Linus Torvalds1da177e2005-04-16 15:20:36 -070079 char **start, char **end)
80{
81 unsigned char p[6];
82 int i = 0;
83
84 if (data_limit - data < plen) {
85 /* check if there is partial match */
86 if (strnicmp(data, pattern, data_limit - data) == 0)
87 return -1;
88 else
89 return 0;
90 }
91
92 if (strnicmp(data, pattern, plen) != 0) {
93 return 0;
94 }
95 *start = data + plen;
96
97 for (data = *start; *data != term; data++) {
98 if (data == data_limit)
99 return -1;
100 }
101 *end = data;
102
103 memset(p, 0, sizeof(p));
104 for (data = *start; data != *end; data++) {
105 if (*data >= '0' && *data <= '9') {
106 p[i] = p[i]*10 + *data - '0';
107 } else if (*data == ',' && i < 5) {
108 i++;
109 } else {
110 /* unexpected character */
111 return -1;
112 }
113 }
114
115 if (i != 5)
116 return -1;
117
Al Viro96d2ca42006-09-28 14:31:49 -0700118 *addr = get_unaligned((__be32 *)p);
119 *port = get_unaligned((__be16 *)(p + 4));
Linus Torvalds1da177e2005-04-16 15:20:36 -0700120 return 1;
121}
122
123
124/*
125 * Look at outgoing ftp packets to catch the response to a PASV command
126 * from the server (inside-to-outside).
127 * When we see one, we build a connection entry with the client address,
128 * client port 0 (unknown at the moment), the server address and the
129 * server port. Mark the current connection entry as a control channel
130 * of the new entry. All this work is just to make the data connection
131 * can be scheduled to the right server later.
132 *
133 * The outgoing packet should be something like
134 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
135 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
136 */
137static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
138 struct sk_buff **pskb, int *diff)
139{
140 struct iphdr *iph;
141 struct tcphdr *th;
142 char *data, *data_limit;
143 char *start, *end;
Al Viro014d7302006-09-28 14:29:52 -0700144 __be32 from;
145 __be16 port;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700146 struct ip_vs_conn *n_cp;
147 char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
148 unsigned buf_len;
149 int ret;
150
151 *diff = 0;
152
153 /* Only useful for established sessions */
154 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
155 return 1;
156
157 /* Linear packets are much easier to deal with. */
158 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
159 return 0;
160
161 if (cp->app_data == &ip_vs_ftp_pasv) {
162 iph = (*pskb)->nh.iph;
163 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
164 data = (char *)th + (th->doff << 2);
165 data_limit = (*pskb)->tail;
166
167 if (ip_vs_ftp_get_addrport(data, data_limit,
168 SERVER_STRING,
169 sizeof(SERVER_STRING)-1, ')',
170 &from, &port,
171 &start, &end) != 1)
172 return 1;
173
Simon Hormanb5522162006-09-13 19:59:23 -0700174 IP_VS_DBG(7, "PASV response (%u.%u.%u.%u:%d) -> "
Linus Torvalds1da177e2005-04-16 15:20:36 -0700175 "%u.%u.%u.%u:%d detected\n",
176 NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0);
177
178 /*
179 * Now update or create an connection entry for it
180 */
181 n_cp = ip_vs_conn_out_get(iph->protocol, from, port,
182 cp->caddr, 0);
183 if (!n_cp) {
184 n_cp = ip_vs_conn_new(IPPROTO_TCP,
185 cp->caddr, 0,
186 cp->vaddr, port,
187 from, port,
188 IP_VS_CONN_F_NO_CPORT,
189 cp->dest);
190 if (!n_cp)
191 return 0;
192
193 /* add its controller */
194 ip_vs_control_add(n_cp, cp);
195 }
196
197 /*
198 * Replace the old passive address with the new one
199 */
200 from = n_cp->vaddr;
201 port = n_cp->vport;
202 sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from),
Al Viro014d7302006-09-28 14:29:52 -0700203 ntohs(port)&255, (ntohs(port)>>8)&255);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700204 buf_len = strlen(buf);
205
206 /*
207 * Calculate required delta-offset to keep TCP happy
208 */
209 *diff = buf_len - (end-start);
210
211 if (*diff == 0) {
212 /* simply replace it with new passive address */
213 memcpy(start, buf, buf_len);
214 ret = 1;
215 } else {
216 ret = !ip_vs_skb_replace(*pskb, GFP_ATOMIC, start,
217 end-start, buf, buf_len);
218 }
219
220 cp->app_data = NULL;
221 ip_vs_tcp_conn_listen(n_cp);
222 ip_vs_conn_put(n_cp);
223 return ret;
224 }
225 return 1;
226}
227
228
229/*
230 * Look at incoming ftp packets to catch the PASV/PORT command
231 * (outside-to-inside).
232 *
233 * The incoming packet having the PORT command should be something like
234 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
235 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
236 * In this case, we create a connection entry using the client address and
237 * port, so that the active ftp data connection from the server can reach
238 * the client.
239 */
240static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
241 struct sk_buff **pskb, int *diff)
242{
243 struct iphdr *iph;
244 struct tcphdr *th;
245 char *data, *data_start, *data_limit;
246 char *start, *end;
Al Viro014d7302006-09-28 14:29:52 -0700247 __be32 to;
248 __be16 port;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700249 struct ip_vs_conn *n_cp;
250
251 /* no diff required for incoming packets */
252 *diff = 0;
253
254 /* Only useful for established sessions */
255 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
256 return 1;
257
258 /* Linear packets are much easier to deal with. */
259 if (!ip_vs_make_skb_writable(pskb, (*pskb)->len))
260 return 0;
261
262 /*
263 * Detecting whether it is passive
264 */
265 iph = (*pskb)->nh.iph;
266 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
267
268 /* Since there may be OPTIONS in the TCP packet and the HLEN is
269 the length of the header in 32-bit multiples, it is accurate
270 to calculate data address by th+HLEN*4 */
271 data = data_start = (char *)th + (th->doff << 2);
272 data_limit = (*pskb)->tail;
273
274 while (data <= data_limit - 6) {
275 if (strnicmp(data, "PASV\r\n", 6) == 0) {
276 /* Passive mode on */
Al Viro5e7ddac2006-10-10 22:49:07 +0100277 IP_VS_DBG(7, "got PASV at %td of %td\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700278 data - data_start,
279 data_limit - data_start);
280 cp->app_data = &ip_vs_ftp_pasv;
281 return 1;
282 }
283 data++;
284 }
285
286 /*
287 * To support virtual FTP server, the scenerio is as follows:
288 * FTP client ----> Load Balancer ----> FTP server
289 * First detect the port number in the application data,
290 * then create a new connection entry for the coming data
291 * connection.
292 */
293 if (ip_vs_ftp_get_addrport(data_start, data_limit,
294 CLIENT_STRING, sizeof(CLIENT_STRING)-1,
295 '\r', &to, &port,
296 &start, &end) != 1)
297 return 1;
298
Simon Hormanb5522162006-09-13 19:59:23 -0700299 IP_VS_DBG(7, "PORT %u.%u.%u.%u:%d detected\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700300 NIPQUAD(to), ntohs(port));
301
302 /* Passive mode off */
303 cp->app_data = NULL;
304
305 /*
306 * Now update or create a connection entry for it
307 */
Simon Hormanb5522162006-09-13 19:59:23 -0700308 IP_VS_DBG(7, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
Linus Torvalds1da177e2005-04-16 15:20:36 -0700309 ip_vs_proto_name(iph->protocol),
310 NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0);
311
312 n_cp = ip_vs_conn_in_get(iph->protocol,
313 to, port,
314 cp->vaddr, htons(ntohs(cp->vport)-1));
315 if (!n_cp) {
316 n_cp = ip_vs_conn_new(IPPROTO_TCP,
317 to, port,
318 cp->vaddr, htons(ntohs(cp->vport)-1),
319 cp->daddr, htons(ntohs(cp->dport)-1),
320 0,
321 cp->dest);
322 if (!n_cp)
323 return 0;
324
325 /* add its controller */
326 ip_vs_control_add(n_cp, cp);
327 }
328
329 /*
330 * Move tunnel to listen state
331 */
332 ip_vs_tcp_conn_listen(n_cp);
333 ip_vs_conn_put(n_cp);
334
335 return 1;
336}
337
338
339static struct ip_vs_app ip_vs_ftp = {
340 .name = "ftp",
341 .type = IP_VS_APP_TYPE_FTP,
342 .protocol = IPPROTO_TCP,
343 .module = THIS_MODULE,
344 .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
345 .init_conn = ip_vs_ftp_init_conn,
346 .done_conn = ip_vs_ftp_done_conn,
347 .bind_conn = NULL,
348 .unbind_conn = NULL,
349 .pkt_out = ip_vs_ftp_out,
350 .pkt_in = ip_vs_ftp_in,
351};
352
353
354/*
355 * ip_vs_ftp initialization
356 */
357static int __init ip_vs_ftp_init(void)
358{
359 int i, ret;
360 struct ip_vs_app *app = &ip_vs_ftp;
361
362 ret = register_ip_vs_app(app);
363 if (ret)
364 return ret;
365
366 for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
367 if (!ports[i])
368 continue;
Linus Torvalds1da177e2005-04-16 15:20:36 -0700369 ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
370 if (ret)
371 break;
Simon Hormanb5522162006-09-13 19:59:23 -0700372 IP_VS_INFO("%s: loaded support on port[%d] = %d\n",
373 app->name, i, ports[i]);
Linus Torvalds1da177e2005-04-16 15:20:36 -0700374 }
375
376 if (ret)
377 unregister_ip_vs_app(app);
378
379 return ret;
380}
381
382
383/*
384 * ip_vs_ftp finish.
385 */
386static void __exit ip_vs_ftp_exit(void)
387{
388 unregister_ip_vs_app(&ip_vs_ftp);
389}
390
391
392module_init(ip_vs_ftp_init);
393module_exit(ip_vs_ftp_exit);
394MODULE_LICENSE("GPL");