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 | ||
c3aa1bd3 JA |
47 | #define SERVER_STRING "227 " |
48 | #define CLIENT_STRING "PORT" | |
1da177e4 LT |
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 | */ | |
52669dfa | 55 | static unsigned int ports_count = 1; |
28b06c38 | 56 | static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0}; |
52669dfa | 57 | module_param_array(ports, ushort, &ports_count, 0444); |
70e76b76 | 58 | MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands"); |
1da177e4 | 59 | |
1da177e4 LT |
60 | |
61 | /* Dummy variable */ | |
62 | static int ip_vs_ftp_pasv; | |
63 | ||
64 | ||
65 | static int | |
66 | ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) | |
67 | { | |
f4bc17cd JA |
68 | /* We use connection tracking for the command connection */ |
69 | cp->flags |= IP_VS_CONN_F_NFCT; | |
1da177e4 LT |
70 | return 0; |
71 | } | |
72 | ||
73 | ||
74 | static int | |
75 | ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) | |
76 | { | |
77 | return 0; | |
78 | } | |
79 | ||
80 | ||
81 | /* | |
82 | * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started | |
c3aa1bd3 JA |
83 | * with the "pattern", ignoring before "skip" and terminated with |
84 | * the "term" character. | |
1da177e4 LT |
85 | * <addr,port> is in network order. |
86 | */ | |
87 | static int ip_vs_ftp_get_addrport(char *data, char *data_limit, | |
c3aa1bd3 JA |
88 | const char *pattern, size_t plen, |
89 | char skip, char term, | |
014d730d | 90 | __be32 *addr, __be16 *port, |
1da177e4 LT |
91 | char **start, char **end) |
92 | { | |
c3aa1bd3 | 93 | char *s, c; |
1da177e4 LT |
94 | unsigned char p[6]; |
95 | int i = 0; | |
96 | ||
97 | if (data_limit - data < plen) { | |
98 | /* check if there is partial match */ | |
99 | if (strnicmp(data, pattern, data_limit - data) == 0) | |
100 | return -1; | |
101 | else | |
102 | return 0; | |
103 | } | |
104 | ||
105 | if (strnicmp(data, pattern, plen) != 0) { | |
106 | return 0; | |
107 | } | |
c3aa1bd3 JA |
108 | s = data + plen; |
109 | if (skip) { | |
110 | int found = 0; | |
111 | ||
112 | for (;; s++) { | |
113 | if (s == data_limit) | |
114 | return -1; | |
115 | if (!found) { | |
116 | if (*s == skip) | |
117 | found = 1; | |
118 | } else if (*s != skip) { | |
119 | break; | |
120 | } | |
121 | } | |
122 | } | |
1da177e4 | 123 | |
c3aa1bd3 | 124 | for (data = s; ; data++) { |
1da177e4 LT |
125 | if (data == data_limit) |
126 | return -1; | |
c3aa1bd3 JA |
127 | if (*data == term) |
128 | break; | |
1da177e4 LT |
129 | } |
130 | *end = data; | |
131 | ||
132 | memset(p, 0, sizeof(p)); | |
c3aa1bd3 JA |
133 | for (data = s; ; data++) { |
134 | c = *data; | |
135 | if (c == term) | |
136 | break; | |
137 | if (c >= '0' && c <= '9') { | |
138 | p[i] = p[i]*10 + c - '0'; | |
139 | } else if (c == ',' && i < 5) { | |
1da177e4 LT |
140 | i++; |
141 | } else { | |
142 | /* unexpected character */ | |
143 | return -1; | |
144 | } | |
145 | } | |
146 | ||
147 | if (i != 5) | |
148 | return -1; | |
149 | ||
c3aa1bd3 JA |
150 | *start = s; |
151 | *addr = get_unaligned((__be32 *) p); | |
152 | *port = get_unaligned((__be16 *) (p + 4)); | |
1da177e4 LT |
153 | return 1; |
154 | } | |
155 | ||
1da177e4 LT |
156 | /* |
157 | * Look at outgoing ftp packets to catch the response to a PASV command | |
158 | * from the server (inside-to-outside). | |
159 | * When we see one, we build a connection entry with the client address, | |
160 | * client port 0 (unknown at the moment), the server address and the | |
161 | * server port. Mark the current connection entry as a control channel | |
162 | * of the new entry. All this work is just to make the data connection | |
163 | * can be scheduled to the right server later. | |
164 | * | |
165 | * The outgoing packet should be something like | |
166 | * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)". | |
167 | * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number. | |
168 | */ | |
169 | static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp, | |
3db05fea | 170 | struct sk_buff *skb, int *diff) |
1da177e4 LT |
171 | { |
172 | struct iphdr *iph; | |
173 | struct tcphdr *th; | |
174 | char *data, *data_limit; | |
175 | char *start, *end; | |
28364a59 | 176 | union nf_inet_addr from; |
014d730d | 177 | __be16 port; |
1da177e4 LT |
178 | struct ip_vs_conn *n_cp; |
179 | char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */ | |
95c96174 | 180 | unsigned int buf_len; |
7f1c4075 HE |
181 | int ret = 0; |
182 | enum ip_conntrack_info ctinfo; | |
183 | struct nf_conn *ct; | |
4a85b96c | 184 | struct net *net; |
1da177e4 | 185 | |
a0eb662f JV |
186 | #ifdef CONFIG_IP_VS_IPV6 |
187 | /* This application helper doesn't work with IPv6 yet, | |
188 | * so turn this into a no-op for IPv6 packets | |
189 | */ | |
190 | if (cp->af == AF_INET6) | |
191 | return 1; | |
192 | #endif | |
193 | ||
1da177e4 LT |
194 | *diff = 0; |
195 | ||
196 | /* Only useful for established sessions */ | |
197 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) | |
198 | return 1; | |
199 | ||
200 | /* Linear packets are much easier to deal with. */ | |
3db05fea | 201 | if (!skb_make_writable(skb, skb->len)) |
1da177e4 LT |
202 | return 0; |
203 | ||
204 | if (cp->app_data == &ip_vs_ftp_pasv) { | |
3db05fea | 205 | iph = ip_hdr(skb); |
1da177e4 LT |
206 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
207 | data = (char *)th + (th->doff << 2); | |
3db05fea | 208 | data_limit = skb_tail_pointer(skb); |
1da177e4 LT |
209 | |
210 | if (ip_vs_ftp_get_addrport(data, data_limit, | |
211 | SERVER_STRING, | |
c3aa1bd3 JA |
212 | sizeof(SERVER_STRING)-1, |
213 | '(', ')', | |
28364a59 | 214 | &from.ip, &port, |
1da177e4 LT |
215 | &start, &end) != 1) |
216 | return 1; | |
217 | ||
14d5e834 HH |
218 | IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n", |
219 | &from.ip, ntohs(port), &cp->caddr.ip, 0); | |
1da177e4 LT |
220 | |
221 | /* | |
222 | * Now update or create an connection entry for it | |
223 | */ | |
f11017ec SH |
224 | { |
225 | struct ip_vs_conn_param p; | |
6e67e586 HS |
226 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), AF_INET, |
227 | iph->protocol, &from, port, | |
228 | &cp->caddr, 0, &p); | |
f11017ec SH |
229 | n_cp = ip_vs_conn_out_get(&p); |
230 | } | |
1da177e4 | 231 | if (!n_cp) { |
f11017ec | 232 | struct ip_vs_conn_param p; |
6e67e586 HS |
233 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), |
234 | AF_INET, IPPROTO_TCP, &cp->caddr, | |
f11017ec SH |
235 | 0, &cp->vaddr, port, &p); |
236 | n_cp = ip_vs_conn_new(&p, &from, port, | |
f4bc17cd JA |
237 | IP_VS_CONN_F_NO_CPORT | |
238 | IP_VS_CONN_F_NFCT, | |
0e051e68 | 239 | cp->dest, skb->mark); |
1da177e4 LT |
240 | if (!n_cp) |
241 | return 0; | |
242 | ||
243 | /* add its controller */ | |
244 | ip_vs_control_add(n_cp, cp); | |
245 | } | |
246 | ||
247 | /* | |
248 | * Replace the old passive address with the new one | |
249 | */ | |
28364a59 | 250 | from.ip = n_cp->vaddr.ip; |
1da177e4 | 251 | port = n_cp->vport; |
1da05f50 JP |
252 | snprintf(buf, sizeof(buf), "%u,%u,%u,%u,%u,%u", |
253 | ((unsigned char *)&from.ip)[0], | |
254 | ((unsigned char *)&from.ip)[1], | |
255 | ((unsigned char *)&from.ip)[2], | |
256 | ((unsigned char *)&from.ip)[3], | |
257 | ntohs(port) >> 8, | |
258 | ntohs(port) & 0xFF); | |
259 | ||
1da177e4 LT |
260 | buf_len = strlen(buf); |
261 | ||
7f1c4075 | 262 | ct = nf_ct_get(skb, &ctinfo); |
7bcbf81a | 263 | if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) { |
7f1c4075 HE |
264 | /* If mangling fails this function will return 0 |
265 | * which will cause the packet to be dropped. | |
266 | * Mangling can only fail under memory pressure, | |
267 | * hopefully it will succeed on the retransmitted | |
268 | * packet. | |
269 | */ | |
270 | ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo, | |
271 | start-data, end-start, | |
272 | buf, buf_len); | |
8b27b10f | 273 | if (ret) { |
f4bc17cd JA |
274 | ip_vs_nfct_expect_related(skb, ct, n_cp, |
275 | IPPROTO_TCP, 0, 0); | |
8b27b10f JA |
276 | if (skb->ip_summed == CHECKSUM_COMPLETE) |
277 | skb->ip_summed = CHECKSUM_UNNECESSARY; | |
278 | /* csum is updated */ | |
279 | ret = 1; | |
280 | } | |
7f1c4075 HE |
281 | } |
282 | ||
1da177e4 | 283 | /* |
7f1c4075 HE |
284 | * Not setting 'diff' is intentional, otherwise the sequence |
285 | * would be adjusted twice. | |
1da177e4 | 286 | */ |
1da177e4 | 287 | |
4a85b96c | 288 | net = skb_net(skb); |
1da177e4 | 289 | cp->app_data = NULL; |
4a85b96c | 290 | ip_vs_tcp_conn_listen(net, n_cp); |
1da177e4 LT |
291 | ip_vs_conn_put(n_cp); |
292 | return ret; | |
293 | } | |
294 | return 1; | |
295 | } | |
296 | ||
297 | ||
298 | /* | |
299 | * Look at incoming ftp packets to catch the PASV/PORT command | |
300 | * (outside-to-inside). | |
301 | * | |
302 | * The incoming packet having the PORT command should be something like | |
303 | * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n". | |
304 | * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number. | |
305 | * In this case, we create a connection entry using the client address and | |
306 | * port, so that the active ftp data connection from the server can reach | |
307 | * the client. | |
308 | */ | |
309 | static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp, | |
3db05fea | 310 | struct sk_buff *skb, int *diff) |
1da177e4 LT |
311 | { |
312 | struct iphdr *iph; | |
313 | struct tcphdr *th; | |
314 | char *data, *data_start, *data_limit; | |
315 | char *start, *end; | |
28364a59 | 316 | union nf_inet_addr to; |
014d730d | 317 | __be16 port; |
1da177e4 | 318 | struct ip_vs_conn *n_cp; |
4a85b96c | 319 | struct net *net; |
1da177e4 | 320 | |
a0eb662f JV |
321 | #ifdef CONFIG_IP_VS_IPV6 |
322 | /* This application helper doesn't work with IPv6 yet, | |
323 | * so turn this into a no-op for IPv6 packets | |
324 | */ | |
325 | if (cp->af == AF_INET6) | |
326 | return 1; | |
327 | #endif | |
328 | ||
1da177e4 LT |
329 | /* no diff required for incoming packets */ |
330 | *diff = 0; | |
331 | ||
332 | /* Only useful for established sessions */ | |
333 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) | |
334 | return 1; | |
335 | ||
336 | /* Linear packets are much easier to deal with. */ | |
3db05fea | 337 | if (!skb_make_writable(skb, skb->len)) |
1da177e4 LT |
338 | return 0; |
339 | ||
340 | /* | |
341 | * Detecting whether it is passive | |
342 | */ | |
3db05fea | 343 | iph = ip_hdr(skb); |
1da177e4 LT |
344 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
345 | ||
346 | /* Since there may be OPTIONS in the TCP packet and the HLEN is | |
347 | the length of the header in 32-bit multiples, it is accurate | |
348 | to calculate data address by th+HLEN*4 */ | |
349 | data = data_start = (char *)th + (th->doff << 2); | |
3db05fea | 350 | data_limit = skb_tail_pointer(skb); |
1da177e4 LT |
351 | |
352 | while (data <= data_limit - 6) { | |
353 | if (strnicmp(data, "PASV\r\n", 6) == 0) { | |
354 | /* Passive mode on */ | |
5e7ddac7 | 355 | IP_VS_DBG(7, "got PASV at %td of %td\n", |
1da177e4 LT |
356 | data - data_start, |
357 | data_limit - data_start); | |
358 | cp->app_data = &ip_vs_ftp_pasv; | |
359 | return 1; | |
360 | } | |
361 | data++; | |
362 | } | |
363 | ||
364 | /* | |
365 | * To support virtual FTP server, the scenerio is as follows: | |
366 | * FTP client ----> Load Balancer ----> FTP server | |
367 | * First detect the port number in the application data, | |
368 | * then create a new connection entry for the coming data | |
369 | * connection. | |
370 | */ | |
371 | if (ip_vs_ftp_get_addrport(data_start, data_limit, | |
372 | CLIENT_STRING, sizeof(CLIENT_STRING)-1, | |
c3aa1bd3 | 373 | ' ', '\r', &to.ip, &port, |
1da177e4 LT |
374 | &start, &end) != 1) |
375 | return 1; | |
376 | ||
14d5e834 | 377 | IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to.ip, ntohs(port)); |
1da177e4 LT |
378 | |
379 | /* Passive mode off */ | |
380 | cp->app_data = NULL; | |
381 | ||
382 | /* | |
383 | * Now update or create a connection entry for it | |
384 | */ | |
14d5e834 | 385 | IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n", |
1da177e4 | 386 | ip_vs_proto_name(iph->protocol), |
14d5e834 | 387 | &to.ip, ntohs(port), &cp->vaddr.ip, 0); |
1da177e4 | 388 | |
f11017ec SH |
389 | { |
390 | struct ip_vs_conn_param p; | |
6e67e586 HS |
391 | ip_vs_conn_fill_param(ip_vs_conn_net(cp), AF_INET, |
392 | iph->protocol, &to, port, &cp->vaddr, | |
393 | htons(ntohs(cp->vport)-1), &p); | |
f11017ec SH |
394 | n_cp = ip_vs_conn_in_get(&p); |
395 | if (!n_cp) { | |
396 | n_cp = ip_vs_conn_new(&p, &cp->daddr, | |
397 | htons(ntohs(cp->dport)-1), | |
0e051e68 HS |
398 | IP_VS_CONN_F_NFCT, cp->dest, |
399 | skb->mark); | |
f11017ec SH |
400 | if (!n_cp) |
401 | return 0; | |
1da177e4 | 402 | |
f11017ec SH |
403 | /* add its controller */ |
404 | ip_vs_control_add(n_cp, cp); | |
405 | } | |
1da177e4 LT |
406 | } |
407 | ||
408 | /* | |
409 | * Move tunnel to listen state | |
410 | */ | |
4a85b96c HS |
411 | net = skb_net(skb); |
412 | ip_vs_tcp_conn_listen(net, n_cp); | |
1da177e4 LT |
413 | ip_vs_conn_put(n_cp); |
414 | ||
415 | return 1; | |
416 | } | |
417 | ||
418 | ||
419 | static struct ip_vs_app ip_vs_ftp = { | |
420 | .name = "ftp", | |
421 | .type = IP_VS_APP_TYPE_FTP, | |
422 | .protocol = IPPROTO_TCP, | |
423 | .module = THIS_MODULE, | |
424 | .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list), | |
425 | .init_conn = ip_vs_ftp_init_conn, | |
426 | .done_conn = ip_vs_ftp_done_conn, | |
427 | .bind_conn = NULL, | |
428 | .unbind_conn = NULL, | |
429 | .pkt_out = ip_vs_ftp_out, | |
430 | .pkt_in = ip_vs_ftp_in, | |
431 | }; | |
432 | ||
1da177e4 | 433 | /* |
61b1ab45 | 434 | * per netns ip_vs_ftp initialization |
1da177e4 | 435 | */ |
61b1ab45 | 436 | static int __net_init __ip_vs_ftp_init(struct net *net) |
1da177e4 LT |
437 | { |
438 | int i, ret; | |
c74c0bfe HS |
439 | struct ip_vs_app *app; |
440 | struct netns_ipvs *ipvs = net_ipvs(net); | |
441 | ||
442 | app = kmemdup(&ip_vs_ftp, sizeof(struct ip_vs_app), GFP_KERNEL); | |
443 | if (!app) | |
444 | return -ENOMEM; | |
445 | INIT_LIST_HEAD(&app->a_list); | |
446 | INIT_LIST_HEAD(&app->incs_list); | |
447 | ipvs->ftp_app = app; | |
1da177e4 | 448 | |
ab8a5e84 | 449 | ret = register_ip_vs_app(net, app); |
1da177e4 | 450 | if (ret) |
c74c0bfe | 451 | goto err_exit; |
1da177e4 | 452 | |
52669dfa | 453 | for (i = 0; i < ports_count; i++) { |
1da177e4 LT |
454 | if (!ports[i]) |
455 | continue; | |
ab8a5e84 | 456 | ret = register_ip_vs_app_inc(net, app, app->protocol, ports[i]); |
1da177e4 | 457 | if (ret) |
c74c0bfe | 458 | goto err_unreg; |
1e3e238e HE |
459 | pr_info("%s: loaded support on port[%d] = %d\n", |
460 | app->name, i, ports[i]); | |
1da177e4 | 461 | } |
c74c0bfe | 462 | return 0; |
1da177e4 | 463 | |
c74c0bfe HS |
464 | err_unreg: |
465 | unregister_ip_vs_app(net, app); | |
466 | err_exit: | |
467 | kfree(ipvs->ftp_app); | |
1da177e4 LT |
468 | return ret; |
469 | } | |
61b1ab45 HS |
470 | /* |
471 | * netns exit | |
472 | */ | |
473 | static void __ip_vs_ftp_exit(struct net *net) | |
474 | { | |
c74c0bfe | 475 | struct netns_ipvs *ipvs = net_ipvs(net); |
61b1ab45 | 476 | |
c74c0bfe HS |
477 | unregister_ip_vs_app(net, ipvs->ftp_app); |
478 | kfree(ipvs->ftp_app); | |
61b1ab45 HS |
479 | } |
480 | ||
481 | static struct pernet_operations ip_vs_ftp_ops = { | |
482 | .init = __ip_vs_ftp_init, | |
483 | .exit = __ip_vs_ftp_exit, | |
484 | }; | |
1da177e4 | 485 | |
61b1ab45 HS |
486 | int __init ip_vs_ftp_init(void) |
487 | { | |
488 | int rv; | |
489 | ||
490 | rv = register_pernet_subsys(&ip_vs_ftp_ops); | |
491 | return rv; | |
492 | } | |
1da177e4 LT |
493 | |
494 | /* | |
495 | * ip_vs_ftp finish. | |
496 | */ | |
497 | static void __exit ip_vs_ftp_exit(void) | |
498 | { | |
61b1ab45 | 499 | unregister_pernet_subsys(&ip_vs_ftp_ops); |
1da177e4 LT |
500 | } |
501 | ||
502 | ||
503 | module_init(ip_vs_ftp_init); | |
504 | module_exit(ip_vs_ftp_exit); | |
505 | MODULE_LICENSE("GPL"); |