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 <net/netfilter/nf_conntrack.h>
36 #include <net/netfilter/nf_conntrack_expect.h>
37 #include <net/netfilter/nf_nat.h>
38 #include <net/netfilter/nf_nat_helper.h>
39 #include <linux/gfp.h>
40 #include <net/protocol.h>
42 #include <asm/unaligned.h>
44 #include <net/ip_vs.h>
47 #define SERVER_STRING "227 Entering Passive Mode ("
48 #define CLIENT_STRING "PORT "
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.
55 static unsigned short ports
[IP_VS_APP_MAX_PORTS
] = {21, 0};
56 module_param_array(ports
, ushort
, NULL
, 0);
57 MODULE_PARM_DESC(ports
, "Ports to monitor for FTP control commands");
61 static int ip_vs_ftp_pasv
;
65 ip_vs_ftp_init_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
67 /* We use connection tracking for the command connection */
68 cp
->flags
|= IP_VS_CONN_F_NFCT
;
74 ip_vs_ftp_done_conn(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
)
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.
85 static int ip_vs_ftp_get_addrport(char *data
, char *data_limit
,
86 const char *pattern
, size_t plen
, char term
,
87 __be32
*addr
, __be16
*port
,
88 char **start
, char **end
)
93 if (data_limit
- data
< plen
) {
94 /* check if there is partial match */
95 if (strnicmp(data
, pattern
, data_limit
- data
) == 0)
101 if (strnicmp(data
, pattern
, plen
) != 0) {
104 *start
= data
+ plen
;
106 for (data
= *start
; *data
!= term
; data
++) {
107 if (data
== data_limit
)
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) {
119 /* unexpected character */
127 *addr
= get_unaligned((__be32
*)p
);
128 *port
= get_unaligned((__be16
*)(p
+ 4));
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.
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.
145 static int ip_vs_ftp_out(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
146 struct sk_buff
*skb
, int *diff
)
150 char *data
, *data_limit
;
152 union nf_inet_addr from
;
154 struct ip_vs_conn
*n_cp
;
155 char buf
[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
158 enum ip_conntrack_info ctinfo
;
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
166 if (cp
->af
== AF_INET6
)
172 /* Only useful for established sessions */
173 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
176 /* Linear packets are much easier to deal with. */
177 if (!skb_make_writable(skb
, skb
->len
))
180 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
182 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
183 data
= (char *)th
+ (th
->doff
<< 2);
184 data_limit
= skb_tail_pointer(skb
);
186 if (ip_vs_ftp_get_addrport(data
, data_limit
,
188 sizeof(SERVER_STRING
)-1, ')',
193 IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
194 &from
.ip
, ntohs(port
), &cp
->caddr
.ip
, 0);
197 * Now update or create an connection entry for it
200 struct ip_vs_conn_param p
;
201 ip_vs_conn_fill_param(ip_vs_conn_net(cp
), AF_INET
,
202 iph
->protocol
, &from
, port
,
204 n_cp
= ip_vs_conn_out_get(&p
);
207 struct ip_vs_conn_param p
;
208 ip_vs_conn_fill_param(ip_vs_conn_net(cp
),
209 AF_INET
, IPPROTO_TCP
, &cp
->caddr
,
210 0, &cp
->vaddr
, port
, &p
);
211 n_cp
= ip_vs_conn_new(&p
, &from
, port
,
212 IP_VS_CONN_F_NO_CPORT
|
214 cp
->dest
, skb
->mark
);
218 /* add its controller */
219 ip_vs_control_add(n_cp
, cp
);
223 * Replace the old passive address with the new one
225 from
.ip
= n_cp
->vaddr
.ip
;
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],
235 buf_len
= strlen(buf
);
237 ct
= nf_ct_get(skb
, &ctinfo
);
238 if (ct
&& !nf_ct_is_untracked(ct
) && nfct_nat(ct
)) {
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
245 ret
= nf_nat_mangle_tcp_packet(skb
, ct
, ctinfo
,
246 start
-data
, end
-start
,
249 ip_vs_nfct_expect_related(skb
, ct
, n_cp
,
251 if (skb
->ip_summed
== CHECKSUM_COMPLETE
)
252 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
253 /* csum is updated */
259 * Not setting 'diff' is intentional, otherwise the sequence
260 * would be adjusted twice.
265 ip_vs_tcp_conn_listen(net
, n_cp
);
266 ip_vs_conn_put(n_cp
);
274 * Look at incoming ftp packets to catch the PASV/PORT command
275 * (outside-to-inside).
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
284 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
285 struct sk_buff
*skb
, int *diff
)
289 char *data
, *data_start
, *data_limit
;
291 union nf_inet_addr to
;
293 struct ip_vs_conn
*n_cp
;
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
300 if (cp
->af
== AF_INET6
)
304 /* no diff required for incoming packets */
307 /* Only useful for established sessions */
308 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
311 /* Linear packets are much easier to deal with. */
312 if (!skb_make_writable(skb
, skb
->len
))
316 * Detecting whether it is passive
319 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
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);
325 data_limit
= skb_tail_pointer(skb
);
327 while (data
<= data_limit
- 6) {
328 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
329 /* Passive mode on */
330 IP_VS_DBG(7, "got PASV at %td of %td\n",
332 data_limit
- data_start
);
333 cp
->app_data
= &ip_vs_ftp_pasv
;
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
346 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
347 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
352 IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to
.ip
, ntohs(port
));
354 /* Passive mode off */
358 * Now update or create a connection entry for it
360 IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
361 ip_vs_proto_name(iph
->protocol
),
362 &to
.ip
, ntohs(port
), &cp
->vaddr
.ip
, 0);
365 struct ip_vs_conn_param p
;
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
);
369 n_cp
= ip_vs_conn_in_get(&p
);
371 n_cp
= ip_vs_conn_new(&p
, &cp
->daddr
,
372 htons(ntohs(cp
->dport
)-1),
373 IP_VS_CONN_F_NFCT
, cp
->dest
,
378 /* add its controller */
379 ip_vs_control_add(n_cp
, cp
);
384 * Move tunnel to listen state
387 ip_vs_tcp_conn_listen(net
, n_cp
);
388 ip_vs_conn_put(n_cp
);
394 static struct ip_vs_app ip_vs_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
,
404 .pkt_out
= ip_vs_ftp_out
,
405 .pkt_in
= ip_vs_ftp_in
,
409 * per netns ip_vs_ftp initialization
411 static int __net_init
__ip_vs_ftp_init(struct net
*net
)
414 struct ip_vs_app
*app
= &ip_vs_ftp
;
416 ret
= register_ip_vs_app(net
, app
);
420 for (i
=0; i
<IP_VS_APP_MAX_PORTS
; i
++) {
423 ret
= register_ip_vs_app_inc(net
, app
, app
->protocol
, ports
[i
]);
426 pr_info("%s: loaded support on port[%d] = %d\n",
427 app
->name
, i
, ports
[i
]);
431 unregister_ip_vs_app(net
, app
);
438 static void __ip_vs_ftp_exit(struct net
*net
)
440 struct ip_vs_app
*app
= &ip_vs_ftp
;
442 unregister_ip_vs_app(net
, app
);
445 static struct pernet_operations ip_vs_ftp_ops
= {
446 .init
= __ip_vs_ftp_init
,
447 .exit
= __ip_vs_ftp_exit
,
450 int __init
ip_vs_ftp_init(void)
454 rv
= register_pernet_subsys(&ip_vs_ftp_ops
);
461 static void __exit
ip_vs_ftp_exit(void)
463 unregister_pernet_subsys(&ip_vs_ftp_ops
);
467 module_init(ip_vs_ftp_init
);
468 module_exit(ip_vs_ftp_exit
);
469 MODULE_LICENSE("GPL");