Commit | Line | Data |
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1da177e4 LT |
1 | /* |
2 | * ip_vs_ftp.c: IPVS ftp application module | |
3 | * | |
1da177e4 LT |
4 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
5 | * | |
6 | * Changes: | |
7 | * | |
8 | * | |
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. | |
13 | * | |
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. | |
16 | * | |
17 | * IP_MASQ_FTP ftp masquerading module | |
18 | * | |
19 | * Version: @(#)ip_masq_ftp.c 0.04 02/05/96 | |
20 | * | |
21 | * Author: Wouter Gadeyne | |
22 | * | |
23 | */ | |
24 | ||
9aada7ac HE |
25 | #define KMSG_COMPONENT "IPVS" |
26 | #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt | |
27 | ||
1da177e4 LT |
28 | #include <linux/module.h> |
29 | #include <linux/moduleparam.h> | |
30 | #include <linux/kernel.h> | |
31 | #include <linux/skbuff.h> | |
32 | #include <linux/in.h> | |
33 | #include <linux/ip.h> | |
af1e1cf0 | 34 | #include <linux/netfilter.h> |
7f1c4075 HE |
35 | #include <net/netfilter/nf_conntrack.h> |
36 | #include <net/netfilter/nf_conntrack_expect.h> | |
7bcbf81a | 37 | #include <net/netfilter/nf_nat.h> |
7f1c4075 | 38 | #include <net/netfilter/nf_nat_helper.h> |
5a0e3ad6 | 39 | #include <linux/gfp.h> |
1da177e4 LT |
40 | #include <net/protocol.h> |
41 | #include <net/tcp.h> | |
96d2ca4e | 42 | #include <asm/unaligned.h> |
1da177e4 LT |
43 | |
44 | #include <net/ip_vs.h> | |
45 | ||
46 | ||
47 | #define SERVER_STRING "227 Entering Passive Mode (" | |
48 | #define CLIENT_STRING "PORT " | |
49 | ||
50 | ||
51 | /* | |
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. | |
54 | */ | |
28b06c38 SH |
55 | static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0}; |
56 | module_param_array(ports, ushort, NULL, 0); | |
70e76b76 | 57 | MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands"); |
1da177e4 | 58 | |
1da177e4 LT |
59 | |
60 | /* Dummy variable */ | |
61 | static int ip_vs_ftp_pasv; | |
62 | ||
63 | ||
64 | static int | |
65 | ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) | |
66 | { | |
f4bc17cd JA |
67 | /* We use connection tracking for the command connection */ |
68 | cp->flags |= IP_VS_CONN_F_NFCT; | |
1da177e4 LT |
69 | return 0; |
70 | } | |
71 | ||
72 | ||
73 | static int | |
74 | ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) | |
75 | { | |
76 | return 0; | |
77 | } | |
78 | ||
79 | ||
80 | /* | |
81 | * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started | |
82 | * with the "pattern" and terminated with the "term" character. | |
83 | * <addr,port> is in network order. | |
84 | */ | |
85 | static int ip_vs_ftp_get_addrport(char *data, char *data_limit, | |
86 | const char *pattern, size_t plen, char term, | |
014d730d | 87 | __be32 *addr, __be16 *port, |
1da177e4 LT |
88 | char **start, char **end) |
89 | { | |
90 | unsigned char p[6]; | |
91 | int i = 0; | |
92 | ||
93 | if (data_limit - data < plen) { | |
94 | /* check if there is partial match */ | |
95 | if (strnicmp(data, pattern, data_limit - data) == 0) | |
96 | return -1; | |
97 | else | |
98 | return 0; | |
99 | } | |
100 | ||
101 | if (strnicmp(data, pattern, plen) != 0) { | |
102 | return 0; | |
103 | } | |
104 | *start = data + plen; | |
105 | ||
106 | for (data = *start; *data != term; data++) { | |
107 | if (data == data_limit) | |
108 | return -1; | |
109 | } | |
110 | *end = data; | |
111 | ||
112 | memset(p, 0, sizeof(p)); | |
113 | for (data = *start; data != *end; data++) { | |
114 | if (*data >= '0' && *data <= '9') { | |
115 | p[i] = p[i]*10 + *data - '0'; | |
116 | } else if (*data == ',' && i < 5) { | |
117 | i++; | |
118 | } else { | |
119 | /* unexpected character */ | |
120 | return -1; | |
121 | } | |
122 | } | |
123 | ||
124 | if (i != 5) | |
125 | return -1; | |
126 | ||
96d2ca4e AV |
127 | *addr = get_unaligned((__be32 *)p); |
128 | *port = get_unaligned((__be16 *)(p + 4)); | |
1da177e4 LT |
129 | return 1; |
130 | } | |
131 | ||
1da177e4 LT |
132 | /* |
133 | * Look at outgoing ftp packets to catch the response to a PASV command | |
134 | * from the server (inside-to-outside). | |
135 | * When we see one, we build a connection entry with the client address, | |
136 | * client port 0 (unknown at the moment), the server address and the | |
137 | * server port. Mark the current connection entry as a control channel | |
138 | * of the new entry. All this work is just to make the data connection | |
139 | * can be scheduled to the right server later. | |
140 | * | |
141 | * The outgoing packet should be something like | |
142 | * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)". | |
143 | * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number. | |
144 | */ | |
145 | static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp, | |
3db05fea | 146 | struct sk_buff *skb, int *diff) |
1da177e4 LT |
147 | { |
148 | struct iphdr *iph; | |
149 | struct tcphdr *th; | |
150 | char *data, *data_limit; | |
151 | char *start, *end; | |
28364a59 | 152 | union nf_inet_addr from; |
014d730d | 153 | __be16 port; |
1da177e4 LT |
154 | struct ip_vs_conn *n_cp; |
155 | char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */ | |
156 | unsigned buf_len; | |
7f1c4075 HE |
157 | int ret = 0; |
158 | enum ip_conntrack_info ctinfo; | |
159 | struct nf_conn *ct; | |
4a85b96c | 160 | struct net *net; |
1da177e4 | 161 | |
a0eb662f JV |
162 | #ifdef CONFIG_IP_VS_IPV6 |
163 | /* This application helper doesn't work with IPv6 yet, | |
164 | * so turn this into a no-op for IPv6 packets | |
165 | */ | |
166 | if (cp->af == AF_INET6) | |
167 | return 1; | |
168 | #endif | |
169 | ||
1da177e4 LT |
170 | *diff = 0; |
171 | ||
172 | /* Only useful for established sessions */ | |
173 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) | |
174 | return 1; | |
175 | ||
176 | /* Linear packets are much easier to deal with. */ | |
3db05fea | 177 | if (!skb_make_writable(skb, skb->len)) |
1da177e4 LT |
178 | return 0; |
179 | ||
180 | if (cp->app_data == &ip_vs_ftp_pasv) { | |
3db05fea | 181 | iph = ip_hdr(skb); |
1da177e4 LT |
182 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
183 | data = (char *)th + (th->doff << 2); | |
3db05fea | 184 | data_limit = skb_tail_pointer(skb); |
1da177e4 LT |
185 | |
186 | if (ip_vs_ftp_get_addrport(data, data_limit, | |
187 | SERVER_STRING, | |
188 | sizeof(SERVER_STRING)-1, ')', | |
28364a59 | 189 | &from.ip, &port, |
1da177e4 LT |
190 | &start, &end) != 1) |
191 | return 1; | |
192 | ||
14d5e834 HH |
193 | IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n", |
194 | &from.ip, ntohs(port), &cp->caddr.ip, 0); | |
1da177e4 LT |
195 | |
196 | /* | |
197 | * Now update or create an connection entry for it | |
198 | */ | |
f11017ec SH |
199 | { |
200 | struct ip_vs_conn_param p; | |
6e67e586 HS |
201 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), AF_INET, |
202 | iph->protocol, &from, port, | |
203 | &cp->caddr, 0, &p); | |
f11017ec SH |
204 | n_cp = ip_vs_conn_out_get(&p); |
205 | } | |
1da177e4 | 206 | if (!n_cp) { |
f11017ec | 207 | struct ip_vs_conn_param p; |
6e67e586 HS |
208 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), |
209 | AF_INET, IPPROTO_TCP, &cp->caddr, | |
f11017ec SH |
210 | 0, &cp->vaddr, port, &p); |
211 | n_cp = ip_vs_conn_new(&p, &from, port, | |
f4bc17cd JA |
212 | IP_VS_CONN_F_NO_CPORT | |
213 | IP_VS_CONN_F_NFCT, | |
0e051e68 | 214 | cp->dest, skb->mark); |
1da177e4 LT |
215 | if (!n_cp) |
216 | return 0; | |
217 | ||
218 | /* add its controller */ | |
219 | ip_vs_control_add(n_cp, cp); | |
220 | } | |
221 | ||
222 | /* | |
223 | * Replace the old passive address with the new one | |
224 | */ | |
28364a59 | 225 | from.ip = n_cp->vaddr.ip; |
1da177e4 | 226 | port = n_cp->vport; |
1da05f50 JP |
227 | snprintf(buf, sizeof(buf), "%u,%u,%u,%u,%u,%u", |
228 | ((unsigned char *)&from.ip)[0], | |
229 | ((unsigned char *)&from.ip)[1], | |
230 | ((unsigned char *)&from.ip)[2], | |
231 | ((unsigned char *)&from.ip)[3], | |
232 | ntohs(port) >> 8, | |
233 | ntohs(port) & 0xFF); | |
234 | ||
1da177e4 LT |
235 | buf_len = strlen(buf); |
236 | ||
7f1c4075 | 237 | ct = nf_ct_get(skb, &ctinfo); |
7bcbf81a | 238 | if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) { |
7f1c4075 HE |
239 | /* If mangling fails this function will return 0 |
240 | * which will cause the packet to be dropped. | |
241 | * Mangling can only fail under memory pressure, | |
242 | * hopefully it will succeed on the retransmitted | |
243 | * packet. | |
244 | */ | |
245 | ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo, | |
246 | start-data, end-start, | |
247 | buf, buf_len); | |
8b27b10f | 248 | if (ret) { |
f4bc17cd JA |
249 | ip_vs_nfct_expect_related(skb, ct, n_cp, |
250 | IPPROTO_TCP, 0, 0); | |
8b27b10f JA |
251 | if (skb->ip_summed == CHECKSUM_COMPLETE) |
252 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
253 | /* csum is updated */ | |
254 | ret = 1; | |
255 | } | |
7f1c4075 HE |
256 | } |
257 | ||
1da177e4 | 258 | /* |
7f1c4075 HE |
259 | * Not setting 'diff' is intentional, otherwise the sequence |
260 | * would be adjusted twice. | |
1da177e4 | 261 | */ |
1da177e4 | 262 | |
4a85b96c | 263 | net = skb_net(skb); |
1da177e4 | 264 | cp->app_data = NULL; |
4a85b96c | 265 | ip_vs_tcp_conn_listen(net, n_cp); |
1da177e4 LT |
266 | ip_vs_conn_put(n_cp); |
267 | return ret; | |
268 | } | |
269 | return 1; | |
270 | } | |
271 | ||
272 | ||
273 | /* | |
274 | * Look at incoming ftp packets to catch the PASV/PORT command | |
275 | * (outside-to-inside). | |
276 | * | |
277 | * The incoming packet having the PORT command should be something like | |
278 | * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n". | |
279 | * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number. | |
280 | * In this case, we create a connection entry using the client address and | |
281 | * port, so that the active ftp data connection from the server can reach | |
282 | * the client. | |
283 | */ | |
284 | static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp, | |
3db05fea | 285 | struct sk_buff *skb, int *diff) |
1da177e4 LT |
286 | { |
287 | struct iphdr *iph; | |
288 | struct tcphdr *th; | |
289 | char *data, *data_start, *data_limit; | |
290 | char *start, *end; | |
28364a59 | 291 | union nf_inet_addr to; |
014d730d | 292 | __be16 port; |
1da177e4 | 293 | struct ip_vs_conn *n_cp; |
4a85b96c | 294 | struct net *net; |
1da177e4 | 295 | |
a0eb662f JV |
296 | #ifdef CONFIG_IP_VS_IPV6 |
297 | /* This application helper doesn't work with IPv6 yet, | |
298 | * so turn this into a no-op for IPv6 packets | |
299 | */ | |
300 | if (cp->af == AF_INET6) | |
301 | return 1; | |
302 | #endif | |
303 | ||
1da177e4 LT |
304 | /* no diff required for incoming packets */ |
305 | *diff = 0; | |
306 | ||
307 | /* Only useful for established sessions */ | |
308 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) | |
309 | return 1; | |
310 | ||
311 | /* Linear packets are much easier to deal with. */ | |
3db05fea | 312 | if (!skb_make_writable(skb, skb->len)) |
1da177e4 LT |
313 | return 0; |
314 | ||
315 | /* | |
316 | * Detecting whether it is passive | |
317 | */ | |
3db05fea | 318 | iph = ip_hdr(skb); |
1da177e4 LT |
319 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
320 | ||
321 | /* Since there may be OPTIONS in the TCP packet and the HLEN is | |
322 | the length of the header in 32-bit multiples, it is accurate | |
323 | to calculate data address by th+HLEN*4 */ | |
324 | data = data_start = (char *)th + (th->doff << 2); | |
3db05fea | 325 | data_limit = skb_tail_pointer(skb); |
1da177e4 LT |
326 | |
327 | while (data <= data_limit - 6) { | |
328 | if (strnicmp(data, "PASV\r\n", 6) == 0) { | |
329 | /* Passive mode on */ | |
5e7ddac7 | 330 | IP_VS_DBG(7, "got PASV at %td of %td\n", |
1da177e4 LT |
331 | data - data_start, |
332 | data_limit - data_start); | |
333 | cp->app_data = &ip_vs_ftp_pasv; | |
334 | return 1; | |
335 | } | |
336 | data++; | |
337 | } | |
338 | ||
339 | /* | |
340 | * To support virtual FTP server, the scenerio is as follows: | |
341 | * FTP client ----> Load Balancer ----> FTP server | |
342 | * First detect the port number in the application data, | |
343 | * then create a new connection entry for the coming data | |
344 | * connection. | |
345 | */ | |
346 | if (ip_vs_ftp_get_addrport(data_start, data_limit, | |
347 | CLIENT_STRING, sizeof(CLIENT_STRING)-1, | |
28364a59 | 348 | '\r', &to.ip, &port, |
1da177e4 LT |
349 | &start, &end) != 1) |
350 | return 1; | |
351 | ||
14d5e834 | 352 | IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to.ip, ntohs(port)); |
1da177e4 LT |
353 | |
354 | /* Passive mode off */ | |
355 | cp->app_data = NULL; | |
356 | ||
357 | /* | |
358 | * Now update or create a connection entry for it | |
359 | */ | |
14d5e834 | 360 | IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n", |
1da177e4 | 361 | ip_vs_proto_name(iph->protocol), |
14d5e834 | 362 | &to.ip, ntohs(port), &cp->vaddr.ip, 0); |
1da177e4 | 363 | |
f11017ec SH |
364 | { |
365 | struct ip_vs_conn_param p; | |
6e67e586 HS |
366 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), AF_INET, |
367 | iph->protocol, &to, port, &cp->vaddr, | |
368 | htons(ntohs(cp->vport)-1), &p); | |
f11017ec SH |
369 | n_cp = ip_vs_conn_in_get(&p); |
370 | if (!n_cp) { | |
371 | n_cp = ip_vs_conn_new(&p, &cp->daddr, | |
372 | htons(ntohs(cp->dport)-1), | |
0e051e68 HS |
373 | IP_VS_CONN_F_NFCT, cp->dest, |
374 | skb->mark); | |
f11017ec SH |
375 | if (!n_cp) |
376 | return 0; | |
1da177e4 | 377 | |
f11017ec SH |
378 | /* add its controller */ |
379 | ip_vs_control_add(n_cp, cp); | |
380 | } | |
1da177e4 LT |
381 | } |
382 | ||
383 | /* | |
384 | * Move tunnel to listen state | |
385 | */ | |
4a85b96c HS |
386 | net = skb_net(skb); |
387 | ip_vs_tcp_conn_listen(net, n_cp); | |
1da177e4 LT |
388 | ip_vs_conn_put(n_cp); |
389 | ||
390 | return 1; | |
391 | } | |
392 | ||
393 | ||
394 | static struct ip_vs_app ip_vs_ftp = { | |
395 | .name = "ftp", | |
396 | .type = IP_VS_APP_TYPE_FTP, | |
397 | .protocol = IPPROTO_TCP, | |
398 | .module = THIS_MODULE, | |
399 | .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list), | |
400 | .init_conn = ip_vs_ftp_init_conn, | |
401 | .done_conn = ip_vs_ftp_done_conn, | |
402 | .bind_conn = NULL, | |
403 | .unbind_conn = NULL, | |
404 | .pkt_out = ip_vs_ftp_out, | |
405 | .pkt_in = ip_vs_ftp_in, | |
406 | }; | |
407 | ||
1da177e4 | 408 | /* |
61b1ab45 | 409 | * per netns ip_vs_ftp initialization |
1da177e4 | 410 | */ |
61b1ab45 | 411 | static int __net_init __ip_vs_ftp_init(struct net *net) |
1da177e4 LT |
412 | { |
413 | int i, ret; | |
c74c0bfe HS |
414 | struct ip_vs_app *app; |
415 | struct netns_ipvs *ipvs = net_ipvs(net); | |
416 | ||
417 | app = kmemdup(&ip_vs_ftp, sizeof(struct ip_vs_app), GFP_KERNEL); | |
418 | if (!app) | |
419 | return -ENOMEM; | |
420 | INIT_LIST_HEAD(&app->a_list); | |
421 | INIT_LIST_HEAD(&app->incs_list); | |
422 | ipvs->ftp_app = app; | |
1da177e4 | 423 | |
ab8a5e84 | 424 | ret = register_ip_vs_app(net, app); |
1da177e4 | 425 | if (ret) |
c74c0bfe | 426 | goto err_exit; |
1da177e4 LT |
427 | |
428 | for (i=0; i<IP_VS_APP_MAX_PORTS; i++) { | |
429 | if (!ports[i]) | |
430 | continue; | |
ab8a5e84 | 431 | ret = register_ip_vs_app_inc(net, app, app->protocol, ports[i]); |
1da177e4 | 432 | if (ret) |
c74c0bfe | 433 | goto err_unreg; |
1e3e238e HE |
434 | pr_info("%s: loaded support on port[%d] = %d\n", |
435 | app->name, i, ports[i]); | |
1da177e4 | 436 | } |
c74c0bfe | 437 | return 0; |
1da177e4 | 438 | |
c74c0bfe HS |
439 | err_unreg: |
440 | unregister_ip_vs_app(net, app); | |
441 | err_exit: | |
442 | kfree(ipvs->ftp_app); | |
1da177e4 LT |
443 | return ret; |
444 | } | |
61b1ab45 HS |
445 | /* |
446 | * netns exit | |
447 | */ | |
448 | static void __ip_vs_ftp_exit(struct net *net) | |
449 | { | |
c74c0bfe | 450 | struct netns_ipvs *ipvs = net_ipvs(net); |
61b1ab45 | 451 | |
c74c0bfe HS |
452 | unregister_ip_vs_app(net, ipvs->ftp_app); |
453 | kfree(ipvs->ftp_app); | |
61b1ab45 HS |
454 | } |
455 | ||
456 | static struct pernet_operations ip_vs_ftp_ops = { | |
457 | .init = __ip_vs_ftp_init, | |
458 | .exit = __ip_vs_ftp_exit, | |
459 | }; | |
1da177e4 | 460 | |
61b1ab45 HS |
461 | int __init ip_vs_ftp_init(void) |
462 | { | |
463 | int rv; | |
464 | ||
465 | rv = register_pernet_subsys(&ip_vs_ftp_ops); | |
466 | return rv; | |
467 | } | |
1da177e4 LT |
468 | |
469 | /* | |
470 | * ip_vs_ftp finish. | |
471 | */ | |
472 | static void __exit ip_vs_ftp_exit(void) | |
473 | { | |
61b1ab45 | 474 | unregister_pernet_subsys(&ip_vs_ftp_ops); |
1da177e4 LT |
475 | } |
476 | ||
477 | ||
478 | module_init(ip_vs_ftp_init); | |
479 | module_exit(ip_vs_ftp_exit); | |
480 | MODULE_LICENSE("GPL"); |