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
;
161 #ifdef CONFIG_IP_VS_IPV6
162 /* This application helper doesn't work with IPv6 yet,
163 * so turn this into a no-op for IPv6 packets
165 if (cp
->af
== AF_INET6
)
171 /* Only useful for established sessions */
172 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
175 /* Linear packets are much easier to deal with. */
176 if (!skb_make_writable(skb
, skb
->len
))
179 if (cp
->app_data
== &ip_vs_ftp_pasv
) {
181 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
182 data
= (char *)th
+ (th
->doff
<< 2);
183 data_limit
= skb_tail_pointer(skb
);
185 if (ip_vs_ftp_get_addrport(data
, data_limit
,
187 sizeof(SERVER_STRING
)-1, ')',
192 IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
193 &from
.ip
, ntohs(port
), &cp
->caddr
.ip
, 0);
196 * Now update or create an connection entry for it
199 struct ip_vs_conn_param p
;
200 ip_vs_conn_fill_param(AF_INET
, iph
->protocol
,
201 &from
, port
, &cp
->caddr
, 0, &p
);
202 n_cp
= ip_vs_conn_out_get(&p
);
205 struct ip_vs_conn_param p
;
206 ip_vs_conn_fill_param(AF_INET
, IPPROTO_TCP
, &cp
->caddr
,
207 0, &cp
->vaddr
, port
, &p
);
208 n_cp
= ip_vs_conn_new(&p
, &from
, port
,
209 IP_VS_CONN_F_NO_CPORT
|
215 /* add its controller */
216 ip_vs_control_add(n_cp
, cp
);
220 * Replace the old passive address with the new one
222 from
.ip
= n_cp
->vaddr
.ip
;
224 snprintf(buf
, sizeof(buf
), "%u,%u,%u,%u,%u,%u",
225 ((unsigned char *)&from
.ip
)[0],
226 ((unsigned char *)&from
.ip
)[1],
227 ((unsigned char *)&from
.ip
)[2],
228 ((unsigned char *)&from
.ip
)[3],
232 buf_len
= strlen(buf
);
234 ct
= nf_ct_get(skb
, &ctinfo
);
235 if (ct
&& !nf_ct_is_untracked(ct
) && nfct_nat(ct
)) {
236 /* If mangling fails this function will return 0
237 * which will cause the packet to be dropped.
238 * Mangling can only fail under memory pressure,
239 * hopefully it will succeed on the retransmitted
242 ret
= nf_nat_mangle_tcp_packet(skb
, ct
, ctinfo
,
243 start
-data
, end
-start
,
246 ip_vs_nfct_expect_related(skb
, ct
, n_cp
,
248 if (skb
->ip_summed
== CHECKSUM_COMPLETE
)
249 skb
->ip_summed
= CHECKSUM_UNNECESSARY
;
250 /* csum is updated */
256 * Not setting 'diff' is intentional, otherwise the sequence
257 * would be adjusted twice.
261 ip_vs_tcp_conn_listen(n_cp
);
262 ip_vs_conn_put(n_cp
);
270 * Look at incoming ftp packets to catch the PASV/PORT command
271 * (outside-to-inside).
273 * The incoming packet having the PORT command should be something like
274 * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
275 * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
276 * In this case, we create a connection entry using the client address and
277 * port, so that the active ftp data connection from the server can reach
280 static int ip_vs_ftp_in(struct ip_vs_app
*app
, struct ip_vs_conn
*cp
,
281 struct sk_buff
*skb
, int *diff
)
285 char *data
, *data_start
, *data_limit
;
287 union nf_inet_addr to
;
289 struct ip_vs_conn
*n_cp
;
291 #ifdef CONFIG_IP_VS_IPV6
292 /* This application helper doesn't work with IPv6 yet,
293 * so turn this into a no-op for IPv6 packets
295 if (cp
->af
== AF_INET6
)
299 /* no diff required for incoming packets */
302 /* Only useful for established sessions */
303 if (cp
->state
!= IP_VS_TCP_S_ESTABLISHED
)
306 /* Linear packets are much easier to deal with. */
307 if (!skb_make_writable(skb
, skb
->len
))
311 * Detecting whether it is passive
314 th
= (struct tcphdr
*)&(((char *)iph
)[iph
->ihl
*4]);
316 /* Since there may be OPTIONS in the TCP packet and the HLEN is
317 the length of the header in 32-bit multiples, it is accurate
318 to calculate data address by th+HLEN*4 */
319 data
= data_start
= (char *)th
+ (th
->doff
<< 2);
320 data_limit
= skb_tail_pointer(skb
);
322 while (data
<= data_limit
- 6) {
323 if (strnicmp(data
, "PASV\r\n", 6) == 0) {
324 /* Passive mode on */
325 IP_VS_DBG(7, "got PASV at %td of %td\n",
327 data_limit
- data_start
);
328 cp
->app_data
= &ip_vs_ftp_pasv
;
335 * To support virtual FTP server, the scenerio is as follows:
336 * FTP client ----> Load Balancer ----> FTP server
337 * First detect the port number in the application data,
338 * then create a new connection entry for the coming data
341 if (ip_vs_ftp_get_addrport(data_start
, data_limit
,
342 CLIENT_STRING
, sizeof(CLIENT_STRING
)-1,
347 IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to
.ip
, ntohs(port
));
349 /* Passive mode off */
353 * Now update or create a connection entry for it
355 IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
356 ip_vs_proto_name(iph
->protocol
),
357 &to
.ip
, ntohs(port
), &cp
->vaddr
.ip
, 0);
360 struct ip_vs_conn_param p
;
361 ip_vs_conn_fill_param(AF_INET
, iph
->protocol
, &to
, port
,
362 &cp
->vaddr
, htons(ntohs(cp
->vport
)-1),
364 n_cp
= ip_vs_conn_in_get(&p
);
366 n_cp
= ip_vs_conn_new(&p
, &cp
->daddr
,
367 htons(ntohs(cp
->dport
)-1),
368 IP_VS_CONN_F_NFCT
, cp
->dest
);
372 /* add its controller */
373 ip_vs_control_add(n_cp
, cp
);
378 * Move tunnel to listen state
380 ip_vs_tcp_conn_listen(n_cp
);
381 ip_vs_conn_put(n_cp
);
387 static struct ip_vs_app ip_vs_ftp
= {
389 .type
= IP_VS_APP_TYPE_FTP
,
390 .protocol
= IPPROTO_TCP
,
391 .module
= THIS_MODULE
,
392 .incs_list
= LIST_HEAD_INIT(ip_vs_ftp
.incs_list
),
393 .init_conn
= ip_vs_ftp_init_conn
,
394 .done_conn
= ip_vs_ftp_done_conn
,
397 .pkt_out
= ip_vs_ftp_out
,
398 .pkt_in
= ip_vs_ftp_in
,
403 * ip_vs_ftp initialization
405 static int __init
ip_vs_ftp_init(void)
408 struct ip_vs_app
*app
= &ip_vs_ftp
;
410 ret
= register_ip_vs_app(app
);
414 for (i
=0; i
<IP_VS_APP_MAX_PORTS
; i
++) {
417 ret
= register_ip_vs_app_inc(app
, app
->protocol
, ports
[i
]);
420 pr_info("%s: loaded support on port[%d] = %d\n",
421 app
->name
, i
, ports
[i
]);
425 unregister_ip_vs_app(app
);
434 static void __exit
ip_vs_ftp_exit(void)
436 unregister_ip_vs_app(&ip_vs_ftp
);
440 module_init(ip_vs_ftp_init
);
441 module_exit(ip_vs_ftp_exit
);
442 MODULE_LICENSE("GPL");