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 #define KMSG_COMPONENT "IPVS"
26 #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
28 #include <linux/module.h>
29 #include <linux/moduleparam.h>
30 #include <linux/kernel.h>
31 #include <linux/skbuff.h>
34 #include <linux/netfilter.h>
35 #include <linux/gfp.h>
36 #include <net/protocol.h>
38 #include <asm/unaligned.h>
40 #include <net/ip_vs.h>
43 #define SERVER_STRING "227 Entering Passive Mode ("
44 #define CLIENT_STRING "PORT "
48 * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
49 * First port is set to the default port.
51 static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0};
52 module_param_array(ports, ushort, NULL, 0);
53 MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands");
57 static int ip_vs_ftp_pasv;
61 ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
68 ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
75 * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
76 * with the "pattern" and terminated with the "term" character.
77 * <addr,port> is in network order.
79 static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
80 const char *pattern, size_t plen, char term,
81 __be32 *addr, __be16 *port,
82 char **start, char **end)
87 if (data_limit - data < plen) {
88 /* check if there is partial match */
89 if (strnicmp(data, pattern, data_limit - data) == 0)
95 if (strnicmp(data, pattern, plen) != 0) {
100 for (data = *start; *data != term; data++) {
101 if (data == data_limit)
106 memset(p, 0, sizeof(p));
107 for (data = *start; data != *end; data++) {
108 if (*data >= '0' && *data <= '9') {
109 p[i] = p[i]*10 + *data - '0';
110 } else if (*data == ',' && i < 5) {
113 /* unexpected character */
121 *addr = get_unaligned((__be32 *)p);
122 *port = get_unaligned((__be16 *)(p + 4));
128 * Look at outgoing ftp packets to catch the response to a PASV command
129 * from the server (inside-to-outside).
130 * When we see one, we build a connection entry with the client address,
131 * client port 0 (unknown at the moment), the server address and the
132 * server port. Mark the current connection entry as a control channel
133 * of the new entry. All this work is just to make the data connection
134 * can be scheduled to the right server later.
136 * The outgoing packet should be something like
137 * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
138 * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
140 static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
141 struct sk_buff *skb, int *diff)
145 char *data, *data_limit;
147 union nf_inet_addr from;
149 struct ip_vs_conn *n_cp;
150 char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
154 #ifdef CONFIG_IP_VS_IPV6
155 /* This application helper doesn't work with IPv6 yet,
156 * so turn this into a no-op for IPv6 packets
158 if (cp->af == AF_INET6)
164 /* Only useful for established sessions */
165 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
168 /* Linear packets are much easier to deal with. */
169 if (!skb_make_writable(skb, skb->len))
172 if (cp->app_data == &ip_vs_ftp_pasv) {
174 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
175 data = (char *)th + (th->doff << 2);
176 data_limit = skb_tail_pointer(skb);
178 if (ip_vs_ftp_get_addrport(data, data_limit,
180 sizeof(SERVER_STRING)-1, ')',
185 IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
186 &from.ip, ntohs(port), &cp->caddr.ip, 0);
189 * Now update or create an connection entry for it
191 n_cp = ip_vs_conn_out_get(AF_INET, iph->protocol, &from, port,
194 n_cp = ip_vs_conn_new(AF_INET, IPPROTO_TCP,
198 IP_VS_CONN_F_NO_CPORT,
203 /* add its controller */
204 ip_vs_control_add(n_cp, cp);
208 * Replace the old passive address with the new one
210 from.ip = n_cp->vaddr.ip;
212 sprintf(buf, "%u,%u,%u,%u,%u,%u", NIPQUAD(from.ip),
213 (ntohs(port)>>8)&255, ntohs(port)&255);
214 buf_len = strlen(buf);
217 * Calculate required delta-offset to keep TCP happy
219 *diff = buf_len - (end-start);
222 /* simply replace it with new passive address */
223 memcpy(start, buf, buf_len);
226 ret = !ip_vs_skb_replace(skb, GFP_ATOMIC, start,
227 end-start, buf, buf_len);
231 ip_vs_tcp_conn_listen(n_cp);
232 ip_vs_conn_put(n_cp);
240 * Look at incoming ftp packets to catch the PASV/PORT command
241 * (outside-to-inside).
243 * The incoming packet having the PORT command should be something like
244 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
245 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
246 * In this case, we create a connection entry using the client address and
247 * port, so that the active ftp data connection from the server can reach
250 static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
251 struct sk_buff *skb, int *diff)
255 char *data, *data_start, *data_limit;
257 union nf_inet_addr to;
259 struct ip_vs_conn *n_cp;
261 #ifdef CONFIG_IP_VS_IPV6
262 /* This application helper doesn't work with IPv6 yet,
263 * so turn this into a no-op for IPv6 packets
265 if (cp->af == AF_INET6)
269 /* no diff required for incoming packets */
272 /* Only useful for established sessions */
273 if (cp->state != IP_VS_TCP_S_ESTABLISHED)
276 /* Linear packets are much easier to deal with. */
277 if (!skb_make_writable(skb, skb->len))
281 * Detecting whether it is passive
284 th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
286 /* Since there may be OPTIONS in the TCP packet and the HLEN is
287 the length of the header in 32-bit multiples, it is accurate
288 to calculate data address by th+HLEN*4 */
289 data = data_start = (char *)th + (th->doff << 2);
290 data_limit = skb_tail_pointer(skb);
292 while (data <= data_limit - 6) {
293 if (strnicmp(data, "PASV\r\n", 6) == 0) {
294 /* Passive mode on */
295 IP_VS_DBG(7, "got PASV at %td of %td\n",
297 data_limit - data_start);
298 cp->app_data = &ip_vs_ftp_pasv;
305 * To support virtual FTP server, the scenerio is as follows:
306 * FTP client ----> Load Balancer ----> FTP server
307 * First detect the port number in the application data,
308 * then create a new connection entry for the coming data
311 if (ip_vs_ftp_get_addrport(data_start, data_limit,
312 CLIENT_STRING, sizeof(CLIENT_STRING)-1,
317 IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to.ip, ntohs(port));
319 /* Passive mode off */
323 * Now update or create a connection entry for it
325 IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
326 ip_vs_proto_name(iph->protocol),
327 &to.ip, ntohs(port), &cp->vaddr.ip, 0);
329 n_cp = ip_vs_conn_in_get(AF_INET, iph->protocol,
331 &cp->vaddr, htons(ntohs(cp->vport)-1));
333 n_cp = ip_vs_conn_new(AF_INET, IPPROTO_TCP,
335 &cp->vaddr, htons(ntohs(cp->vport)-1),
336 &cp->daddr, htons(ntohs(cp->dport)-1),
342 /* add its controller */
343 ip_vs_control_add(n_cp, cp);
347 * Move tunnel to listen state
349 ip_vs_tcp_conn_listen(n_cp);
350 ip_vs_conn_put(n_cp);
356 static struct ip_vs_app ip_vs_ftp = {
358 .type = IP_VS_APP_TYPE_FTP,
359 .protocol = IPPROTO_TCP,
360 .module = THIS_MODULE,
361 .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
362 .init_conn = ip_vs_ftp_init_conn,
363 .done_conn = ip_vs_ftp_done_conn,
366 .pkt_out = ip_vs_ftp_out,
367 .pkt_in = ip_vs_ftp_in,
372 * ip_vs_ftp initialization
374 static int __init ip_vs_ftp_init(void)
377 struct ip_vs_app *app = &ip_vs_ftp;
379 ret = register_ip_vs_app(app);
383 for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
386 ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
389 pr_info("%s: loaded support on port[%d] = %d\n",
390 app->name, i, ports[i]);
394 unregister_ip_vs_app(app);
403 static void __exit ip_vs_ftp_exit(void)
405 unregister_ip_vs_app(&ip_vs_ftp);
409 module_init(ip_vs_ftp_init);
410 module_exit(ip_vs_ftp_exit);
411 MODULE_LICENSE("GPL");