Linus Torvalds | 1da177e | 2005-04-16 15:20:36 -0700 | [diff] [blame^] | 1 | /* |
| 2 | * ip_vs_ftp.c: IPVS ftp application module |
| 3 | * |
| 4 | * Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $ |
| 5 | * |
| 6 | * Authors: Wensong Zhang <wensong@linuxvirtualserver.org> |
| 7 | * |
| 8 | * Changes: |
| 9 | * |
| 10 | * |
| 11 | * This program is free software; you can redistribute it and/or |
| 12 | * modify it under the terms of the GNU General Public License |
| 13 | * as published by the Free Software Foundation; either version |
| 14 | * 2 of the License, or (at your option) any later version. |
| 15 | * |
| 16 | * Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference |
| 17 | * is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp. |
| 18 | * |
| 19 | * IP_MASQ_FTP ftp masquerading module |
| 20 | * |
| 21 | * Version: @(#)ip_masq_ftp.c 0.04 02/05/96 |
| 22 | * |
| 23 | * Author: Wouter Gadeyne |
| 24 | * |
| 25 | */ |
| 26 | |
| 27 | #include <linux/module.h> |
| 28 | #include <linux/moduleparam.h> |
| 29 | #include <linux/kernel.h> |
| 30 | #include <linux/skbuff.h> |
| 31 | #include <linux/in.h> |
| 32 | #include <linux/ip.h> |
| 33 | #include <net/protocol.h> |
| 34 | #include <net/tcp.h> |
| 35 | |
| 36 | #include <net/ip_vs.h> |
| 37 | |
| 38 | |
| 39 | #define SERVER_STRING "227 Entering Passive Mode (" |
| 40 | #define CLIENT_STRING "PORT " |
| 41 | |
| 42 | |
| 43 | /* |
| 44 | * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper |
| 45 | * First port is set to the default port. |
| 46 | */ |
| 47 | static int ports[IP_VS_APP_MAX_PORTS] = {21, 0}; |
| 48 | module_param_array(ports, int, NULL, 0); |
| 49 | |
| 50 | /* |
| 51 | * Debug level |
| 52 | */ |
| 53 | #ifdef CONFIG_IP_VS_DEBUG |
| 54 | static int debug=0; |
| 55 | module_param(debug, int, 0); |
| 56 | #endif |
| 57 | |
| 58 | |
| 59 | /* Dummy variable */ |
| 60 | static int ip_vs_ftp_pasv; |
| 61 | |
| 62 | |
| 63 | static int |
| 64 | ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) |
| 65 | { |
| 66 | return 0; |
| 67 | } |
| 68 | |
| 69 | |
| 70 | static int |
| 71 | ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp) |
| 72 | { |
| 73 | return 0; |
| 74 | } |
| 75 | |
| 76 | |
| 77 | /* |
| 78 | * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started |
| 79 | * with the "pattern" and terminated with the "term" character. |
| 80 | * <addr,port> is in network order. |
| 81 | */ |
| 82 | static int ip_vs_ftp_get_addrport(char *data, char *data_limit, |
| 83 | const char *pattern, size_t plen, char term, |
| 84 | __u32 *addr, __u16 *port, |
| 85 | char **start, char **end) |
| 86 | { |
| 87 | unsigned char p[6]; |
| 88 | int i = 0; |
| 89 | |
| 90 | if (data_limit - data < plen) { |
| 91 | /* check if there is partial match */ |
| 92 | if (strnicmp(data, pattern, data_limit - data) == 0) |
| 93 | return -1; |
| 94 | else |
| 95 | return 0; |
| 96 | } |
| 97 | |
| 98 | if (strnicmp(data, pattern, plen) != 0) { |
| 99 | return 0; |
| 100 | } |
| 101 | *start = data + plen; |
| 102 | |
| 103 | for (data = *start; *data != term; data++) { |
| 104 | if (data == data_limit) |
| 105 | return -1; |
| 106 | } |
| 107 | *end = data; |
| 108 | |
| 109 | memset(p, 0, sizeof(p)); |
| 110 | for (data = *start; data != *end; data++) { |
| 111 | if (*data >= '0' && *data <= '9') { |
| 112 | p[i] = p[i]*10 + *data - '0'; |
| 113 | } else if (*data == ',' && i < 5) { |
| 114 | i++; |
| 115 | } else { |
| 116 | /* unexpected character */ |
| 117 | return -1; |
| 118 | } |
| 119 | } |
| 120 | |
| 121 | if (i != 5) |
| 122 | return -1; |
| 123 | |
| 124 | *addr = (p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0]; |
| 125 | *port = (p[5]<<8) | p[4]; |
| 126 | return 1; |
| 127 | } |
| 128 | |
| 129 | |
| 130 | /* |
| 131 | * Look at outgoing ftp packets to catch the response to a PASV command |
| 132 | * from the server (inside-to-outside). |
| 133 | * When we see one, we build a connection entry with the client address, |
| 134 | * client port 0 (unknown at the moment), the server address and the |
| 135 | * server port. Mark the current connection entry as a control channel |
| 136 | * of the new entry. All this work is just to make the data connection |
| 137 | * can be scheduled to the right server later. |
| 138 | * |
| 139 | * The outgoing packet should be something like |
| 140 | * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)". |
| 141 | * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number. |
| 142 | */ |
| 143 | static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp, |
| 144 | struct sk_buff **pskb, int *diff) |
| 145 | { |
| 146 | struct iphdr *iph; |
| 147 | struct tcphdr *th; |
| 148 | char *data, *data_limit; |
| 149 | char *start, *end; |
| 150 | __u32 from; |
| 151 | __u16 port; |
| 152 | struct ip_vs_conn *n_cp; |
| 153 | char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */ |
| 154 | unsigned buf_len; |
| 155 | int ret; |
| 156 | |
| 157 | *diff = 0; |
| 158 | |
| 159 | /* Only useful for established sessions */ |
| 160 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) |
| 161 | return 1; |
| 162 | |
| 163 | /* Linear packets are much easier to deal with. */ |
| 164 | if (!ip_vs_make_skb_writable(pskb, (*pskb)->len)) |
| 165 | return 0; |
| 166 | |
| 167 | if (cp->app_data == &ip_vs_ftp_pasv) { |
| 168 | iph = (*pskb)->nh.iph; |
| 169 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
| 170 | data = (char *)th + (th->doff << 2); |
| 171 | data_limit = (*pskb)->tail; |
| 172 | |
| 173 | if (ip_vs_ftp_get_addrport(data, data_limit, |
| 174 | SERVER_STRING, |
| 175 | sizeof(SERVER_STRING)-1, ')', |
| 176 | &from, &port, |
| 177 | &start, &end) != 1) |
| 178 | return 1; |
| 179 | |
| 180 | IP_VS_DBG(1-debug, "PASV response (%u.%u.%u.%u:%d) -> " |
| 181 | "%u.%u.%u.%u:%d detected\n", |
| 182 | NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0); |
| 183 | |
| 184 | /* |
| 185 | * Now update or create an connection entry for it |
| 186 | */ |
| 187 | n_cp = ip_vs_conn_out_get(iph->protocol, from, port, |
| 188 | cp->caddr, 0); |
| 189 | if (!n_cp) { |
| 190 | n_cp = ip_vs_conn_new(IPPROTO_TCP, |
| 191 | cp->caddr, 0, |
| 192 | cp->vaddr, port, |
| 193 | from, port, |
| 194 | IP_VS_CONN_F_NO_CPORT, |
| 195 | cp->dest); |
| 196 | if (!n_cp) |
| 197 | return 0; |
| 198 | |
| 199 | /* add its controller */ |
| 200 | ip_vs_control_add(n_cp, cp); |
| 201 | } |
| 202 | |
| 203 | /* |
| 204 | * Replace the old passive address with the new one |
| 205 | */ |
| 206 | from = n_cp->vaddr; |
| 207 | port = n_cp->vport; |
| 208 | sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from), |
| 209 | port&255, (port>>8)&255); |
| 210 | buf_len = strlen(buf); |
| 211 | |
| 212 | /* |
| 213 | * Calculate required delta-offset to keep TCP happy |
| 214 | */ |
| 215 | *diff = buf_len - (end-start); |
| 216 | |
| 217 | if (*diff == 0) { |
| 218 | /* simply replace it with new passive address */ |
| 219 | memcpy(start, buf, buf_len); |
| 220 | ret = 1; |
| 221 | } else { |
| 222 | ret = !ip_vs_skb_replace(*pskb, GFP_ATOMIC, start, |
| 223 | end-start, buf, buf_len); |
| 224 | } |
| 225 | |
| 226 | cp->app_data = NULL; |
| 227 | ip_vs_tcp_conn_listen(n_cp); |
| 228 | ip_vs_conn_put(n_cp); |
| 229 | return ret; |
| 230 | } |
| 231 | return 1; |
| 232 | } |
| 233 | |
| 234 | |
| 235 | /* |
| 236 | * Look at incoming ftp packets to catch the PASV/PORT command |
| 237 | * (outside-to-inside). |
| 238 | * |
| 239 | * The incoming packet having the PORT command should be something like |
| 240 | * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n". |
| 241 | * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number. |
| 242 | * In this case, we create a connection entry using the client address and |
| 243 | * port, so that the active ftp data connection from the server can reach |
| 244 | * the client. |
| 245 | */ |
| 246 | static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp, |
| 247 | struct sk_buff **pskb, int *diff) |
| 248 | { |
| 249 | struct iphdr *iph; |
| 250 | struct tcphdr *th; |
| 251 | char *data, *data_start, *data_limit; |
| 252 | char *start, *end; |
| 253 | __u32 to; |
| 254 | __u16 port; |
| 255 | struct ip_vs_conn *n_cp; |
| 256 | |
| 257 | /* no diff required for incoming packets */ |
| 258 | *diff = 0; |
| 259 | |
| 260 | /* Only useful for established sessions */ |
| 261 | if (cp->state != IP_VS_TCP_S_ESTABLISHED) |
| 262 | return 1; |
| 263 | |
| 264 | /* Linear packets are much easier to deal with. */ |
| 265 | if (!ip_vs_make_skb_writable(pskb, (*pskb)->len)) |
| 266 | return 0; |
| 267 | |
| 268 | /* |
| 269 | * Detecting whether it is passive |
| 270 | */ |
| 271 | iph = (*pskb)->nh.iph; |
| 272 | th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
| 273 | |
| 274 | /* Since there may be OPTIONS in the TCP packet and the HLEN is |
| 275 | the length of the header in 32-bit multiples, it is accurate |
| 276 | to calculate data address by th+HLEN*4 */ |
| 277 | data = data_start = (char *)th + (th->doff << 2); |
| 278 | data_limit = (*pskb)->tail; |
| 279 | |
| 280 | while (data <= data_limit - 6) { |
| 281 | if (strnicmp(data, "PASV\r\n", 6) == 0) { |
| 282 | /* Passive mode on */ |
| 283 | IP_VS_DBG(1-debug, "got PASV at %zd of %zd\n", |
| 284 | data - data_start, |
| 285 | data_limit - data_start); |
| 286 | cp->app_data = &ip_vs_ftp_pasv; |
| 287 | return 1; |
| 288 | } |
| 289 | data++; |
| 290 | } |
| 291 | |
| 292 | /* |
| 293 | * To support virtual FTP server, the scenerio is as follows: |
| 294 | * FTP client ----> Load Balancer ----> FTP server |
| 295 | * First detect the port number in the application data, |
| 296 | * then create a new connection entry for the coming data |
| 297 | * connection. |
| 298 | */ |
| 299 | if (ip_vs_ftp_get_addrport(data_start, data_limit, |
| 300 | CLIENT_STRING, sizeof(CLIENT_STRING)-1, |
| 301 | '\r', &to, &port, |
| 302 | &start, &end) != 1) |
| 303 | return 1; |
| 304 | |
| 305 | IP_VS_DBG(1-debug, "PORT %u.%u.%u.%u:%d detected\n", |
| 306 | NIPQUAD(to), ntohs(port)); |
| 307 | |
| 308 | /* Passive mode off */ |
| 309 | cp->app_data = NULL; |
| 310 | |
| 311 | /* |
| 312 | * Now update or create a connection entry for it |
| 313 | */ |
| 314 | IP_VS_DBG(1-debug, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n", |
| 315 | ip_vs_proto_name(iph->protocol), |
| 316 | NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0); |
| 317 | |
| 318 | n_cp = ip_vs_conn_in_get(iph->protocol, |
| 319 | to, port, |
| 320 | cp->vaddr, htons(ntohs(cp->vport)-1)); |
| 321 | if (!n_cp) { |
| 322 | n_cp = ip_vs_conn_new(IPPROTO_TCP, |
| 323 | to, port, |
| 324 | cp->vaddr, htons(ntohs(cp->vport)-1), |
| 325 | cp->daddr, htons(ntohs(cp->dport)-1), |
| 326 | 0, |
| 327 | cp->dest); |
| 328 | if (!n_cp) |
| 329 | return 0; |
| 330 | |
| 331 | /* add its controller */ |
| 332 | ip_vs_control_add(n_cp, cp); |
| 333 | } |
| 334 | |
| 335 | /* |
| 336 | * Move tunnel to listen state |
| 337 | */ |
| 338 | ip_vs_tcp_conn_listen(n_cp); |
| 339 | ip_vs_conn_put(n_cp); |
| 340 | |
| 341 | return 1; |
| 342 | } |
| 343 | |
| 344 | |
| 345 | static struct ip_vs_app ip_vs_ftp = { |
| 346 | .name = "ftp", |
| 347 | .type = IP_VS_APP_TYPE_FTP, |
| 348 | .protocol = IPPROTO_TCP, |
| 349 | .module = THIS_MODULE, |
| 350 | .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list), |
| 351 | .init_conn = ip_vs_ftp_init_conn, |
| 352 | .done_conn = ip_vs_ftp_done_conn, |
| 353 | .bind_conn = NULL, |
| 354 | .unbind_conn = NULL, |
| 355 | .pkt_out = ip_vs_ftp_out, |
| 356 | .pkt_in = ip_vs_ftp_in, |
| 357 | }; |
| 358 | |
| 359 | |
| 360 | /* |
| 361 | * ip_vs_ftp initialization |
| 362 | */ |
| 363 | static int __init ip_vs_ftp_init(void) |
| 364 | { |
| 365 | int i, ret; |
| 366 | struct ip_vs_app *app = &ip_vs_ftp; |
| 367 | |
| 368 | ret = register_ip_vs_app(app); |
| 369 | if (ret) |
| 370 | return ret; |
| 371 | |
| 372 | for (i=0; i<IP_VS_APP_MAX_PORTS; i++) { |
| 373 | if (!ports[i]) |
| 374 | continue; |
| 375 | ret = register_ip_vs_app_inc(app, app->protocol, ports[i]); |
| 376 | if (ret) |
| 377 | break; |
| 378 | IP_VS_DBG(1-debug, "%s: loaded support on port[%d] = %d\n", |
| 379 | app->name, i, ports[i]); |
| 380 | } |
| 381 | |
| 382 | if (ret) |
| 383 | unregister_ip_vs_app(app); |
| 384 | |
| 385 | return ret; |
| 386 | } |
| 387 | |
| 388 | |
| 389 | /* |
| 390 | * ip_vs_ftp finish. |
| 391 | */ |
| 392 | static void __exit ip_vs_ftp_exit(void) |
| 393 | { |
| 394 | unregister_ip_vs_app(&ip_vs_ftp); |
| 395 | } |
| 396 | |
| 397 | |
| 398 | module_init(ip_vs_ftp_init); |
| 399 | module_exit(ip_vs_ftp_exit); |
| 400 | MODULE_LICENSE("GPL"); |