Yasuyuki Kozakai | 9fb9cbb | 2005-11-09 16:38:16 -0800 | [diff] [blame] | 1 | /* FTP extension for connection tracking. */ |
| 2 | |
| 3 | /* (C) 1999-2001 Paul `Rusty' Russell |
| 4 | * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org> |
| 5 | * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org> |
| 6 | * |
| 7 | * This program is free software; you can redistribute it and/or modify |
| 8 | * it under the terms of the GNU General Public License version 2 as |
| 9 | * published by the Free Software Foundation. |
| 10 | * |
| 11 | * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp> |
| 12 | * - enable working with Layer 3 protocol independent connection tracking. |
| 13 | * - track EPRT and EPSV commands with IPv6 address. |
| 14 | * |
| 15 | * Derived from net/ipv4/netfilter/ip_conntrack_ftp.c |
| 16 | */ |
| 17 | |
| 18 | #include <linux/config.h> |
| 19 | #include <linux/module.h> |
| 20 | #include <linux/moduleparam.h> |
| 21 | #include <linux/netfilter.h> |
| 22 | #include <linux/ip.h> |
| 23 | #include <linux/ipv6.h> |
| 24 | #include <linux/ctype.h> |
| 25 | #include <net/checksum.h> |
| 26 | #include <net/tcp.h> |
| 27 | |
| 28 | #include <net/netfilter/nf_conntrack.h> |
| 29 | #include <net/netfilter/nf_conntrack_helper.h> |
| 30 | #include <linux/netfilter/nf_conntrack_ftp.h> |
| 31 | |
| 32 | MODULE_LICENSE("GPL"); |
| 33 | MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>"); |
| 34 | MODULE_DESCRIPTION("ftp connection tracking helper"); |
| 35 | |
| 36 | /* This is slow, but it's simple. --RR */ |
| 37 | static char *ftp_buffer; |
| 38 | |
| 39 | static DEFINE_SPINLOCK(nf_ftp_lock); |
| 40 | |
| 41 | #define MAX_PORTS 8 |
| 42 | static u_int16_t ports[MAX_PORTS]; |
| 43 | static unsigned int ports_c; |
| 44 | module_param_array(ports, ushort, &ports_c, 0400); |
| 45 | |
| 46 | static int loose; |
Patrick McHardy | e7be699 | 2006-01-05 12:19:46 -0800 | [diff] [blame] | 47 | module_param(loose, bool, 0600); |
Yasuyuki Kozakai | 9fb9cbb | 2005-11-09 16:38:16 -0800 | [diff] [blame] | 48 | |
| 49 | unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb, |
| 50 | enum ip_conntrack_info ctinfo, |
| 51 | enum ip_ct_ftp_type type, |
| 52 | unsigned int matchoff, |
| 53 | unsigned int matchlen, |
| 54 | struct nf_conntrack_expect *exp, |
| 55 | u32 *seq); |
| 56 | EXPORT_SYMBOL_GPL(nf_nat_ftp_hook); |
| 57 | |
| 58 | #if 0 |
| 59 | #define DEBUGP printk |
| 60 | #else |
| 61 | #define DEBUGP(format, args...) |
| 62 | #endif |
| 63 | |
| 64 | static int try_rfc959(const char *, size_t, struct nf_conntrack_man *, char); |
| 65 | static int try_eprt(const char *, size_t, struct nf_conntrack_man *, char); |
| 66 | static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *, |
| 67 | char); |
| 68 | |
| 69 | static struct ftp_search { |
| 70 | enum ip_conntrack_dir dir; |
| 71 | const char *pattern; |
| 72 | size_t plen; |
| 73 | char skip; |
| 74 | char term; |
| 75 | enum ip_ct_ftp_type ftptype; |
| 76 | int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char); |
| 77 | } search[] = { |
| 78 | { |
| 79 | IP_CT_DIR_ORIGINAL, |
| 80 | "PORT", sizeof("PORT") - 1, ' ', '\r', |
| 81 | IP_CT_FTP_PORT, |
| 82 | try_rfc959, |
| 83 | }, |
| 84 | { |
| 85 | IP_CT_DIR_REPLY, |
| 86 | "227 ", sizeof("227 ") - 1, '(', ')', |
| 87 | IP_CT_FTP_PASV, |
| 88 | try_rfc959, |
| 89 | }, |
| 90 | { |
| 91 | IP_CT_DIR_ORIGINAL, |
| 92 | "EPRT", sizeof("EPRT") - 1, ' ', '\r', |
| 93 | IP_CT_FTP_EPRT, |
| 94 | try_eprt, |
| 95 | }, |
| 96 | { |
| 97 | IP_CT_DIR_REPLY, |
| 98 | "229 ", sizeof("229 ") - 1, '(', ')', |
| 99 | IP_CT_FTP_EPSV, |
| 100 | try_epsv_response, |
| 101 | }, |
| 102 | }; |
| 103 | |
| 104 | /* This code is based on inet_pton() in glibc-2.2.4 */ |
| 105 | static int |
| 106 | get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term) |
| 107 | { |
| 108 | static const char xdigits[] = "0123456789abcdef"; |
| 109 | u_int8_t tmp[16], *tp, *endp, *colonp; |
| 110 | int ch, saw_xdigit; |
| 111 | u_int32_t val; |
| 112 | size_t clen = 0; |
| 113 | |
| 114 | tp = memset(tmp, '\0', sizeof(tmp)); |
| 115 | endp = tp + sizeof(tmp); |
| 116 | colonp = NULL; |
| 117 | |
| 118 | /* Leading :: requires some special handling. */ |
| 119 | if (*src == ':'){ |
| 120 | if (*++src != ':') { |
| 121 | DEBUGP("invalid \":\" at the head of addr\n"); |
| 122 | return 0; |
| 123 | } |
| 124 | clen++; |
| 125 | } |
| 126 | |
| 127 | saw_xdigit = 0; |
| 128 | val = 0; |
| 129 | while ((clen < dlen) && (*src != term)) { |
| 130 | const char *pch; |
| 131 | |
| 132 | ch = tolower(*src++); |
| 133 | clen++; |
| 134 | |
| 135 | pch = strchr(xdigits, ch); |
| 136 | if (pch != NULL) { |
| 137 | val <<= 4; |
| 138 | val |= (pch - xdigits); |
| 139 | if (val > 0xffff) |
| 140 | return 0; |
| 141 | |
| 142 | saw_xdigit = 1; |
| 143 | continue; |
| 144 | } |
| 145 | if (ch != ':') { |
| 146 | DEBUGP("get_ipv6_addr: invalid char. \'%c\'\n", ch); |
| 147 | return 0; |
| 148 | } |
| 149 | |
| 150 | if (!saw_xdigit) { |
| 151 | if (colonp) { |
| 152 | DEBUGP("invalid location of \"::\".\n"); |
| 153 | return 0; |
| 154 | } |
| 155 | colonp = tp; |
| 156 | continue; |
| 157 | } else if (*src == term) { |
| 158 | DEBUGP("trancated IPv6 addr\n"); |
| 159 | return 0; |
| 160 | } |
| 161 | |
| 162 | if (tp + 2 > endp) |
| 163 | return 0; |
| 164 | *tp++ = (u_int8_t) (val >> 8) & 0xff; |
| 165 | *tp++ = (u_int8_t) val & 0xff; |
| 166 | |
| 167 | saw_xdigit = 0; |
| 168 | val = 0; |
| 169 | continue; |
| 170 | } |
| 171 | if (saw_xdigit) { |
| 172 | if (tp + 2 > endp) |
| 173 | return 0; |
| 174 | *tp++ = (u_int8_t) (val >> 8) & 0xff; |
| 175 | *tp++ = (u_int8_t) val & 0xff; |
| 176 | } |
| 177 | if (colonp != NULL) { |
| 178 | /* |
| 179 | * Since some memmove()'s erroneously fail to handle |
| 180 | * overlapping regions, we'll do the shift by hand. |
| 181 | */ |
| 182 | const int n = tp - colonp; |
| 183 | int i; |
| 184 | |
| 185 | if (tp == endp) |
| 186 | return 0; |
| 187 | |
| 188 | for (i = 1; i <= n; i++) { |
| 189 | endp[- i] = colonp[n - i]; |
| 190 | colonp[n - i] = 0; |
| 191 | } |
| 192 | tp = endp; |
| 193 | } |
| 194 | if (tp != endp || (*src != term)) |
| 195 | return 0; |
| 196 | |
| 197 | memcpy(dst->s6_addr, tmp, sizeof(dst->s6_addr)); |
| 198 | return clen; |
| 199 | } |
| 200 | |
| 201 | static int try_number(const char *data, size_t dlen, u_int32_t array[], |
| 202 | int array_size, char sep, char term) |
| 203 | { |
| 204 | u_int32_t i, len; |
| 205 | |
| 206 | memset(array, 0, sizeof(array[0])*array_size); |
| 207 | |
| 208 | /* Keep data pointing at next char. */ |
| 209 | for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) { |
| 210 | if (*data >= '0' && *data <= '9') { |
| 211 | array[i] = array[i]*10 + *data - '0'; |
| 212 | } |
| 213 | else if (*data == sep) |
| 214 | i++; |
| 215 | else { |
| 216 | /* Unexpected character; true if it's the |
| 217 | terminator and we're finished. */ |
| 218 | if (*data == term && i == array_size - 1) |
| 219 | return len; |
| 220 | |
| 221 | DEBUGP("Char %u (got %u nums) `%u' unexpected\n", |
| 222 | len, i, *data); |
| 223 | return 0; |
| 224 | } |
| 225 | } |
| 226 | DEBUGP("Failed to fill %u numbers separated by %c\n", array_size, sep); |
| 227 | |
| 228 | return 0; |
| 229 | } |
| 230 | |
| 231 | /* Returns 0, or length of numbers: 192,168,1,1,5,6 */ |
| 232 | static int try_rfc959(const char *data, size_t dlen, |
| 233 | struct nf_conntrack_man *cmd, char term) |
| 234 | { |
| 235 | int length; |
| 236 | u_int32_t array[6]; |
| 237 | |
| 238 | length = try_number(data, dlen, array, 6, ',', term); |
| 239 | if (length == 0) |
| 240 | return 0; |
| 241 | |
| 242 | cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) | |
| 243 | (array[2] << 8) | array[3]); |
| 244 | cmd->u.tcp.port = htons((array[4] << 8) | array[5]); |
| 245 | return length; |
| 246 | } |
| 247 | |
| 248 | /* Grab port: number up to delimiter */ |
| 249 | static int get_port(const char *data, int start, size_t dlen, char delim, |
| 250 | u_int16_t *port) |
| 251 | { |
| 252 | u_int16_t tmp_port = 0; |
| 253 | int i; |
| 254 | |
| 255 | for (i = start; i < dlen; i++) { |
| 256 | /* Finished? */ |
| 257 | if (data[i] == delim) { |
| 258 | if (tmp_port == 0) |
| 259 | break; |
| 260 | *port = htons(tmp_port); |
| 261 | DEBUGP("get_port: return %d\n", tmp_port); |
| 262 | return i + 1; |
| 263 | } |
| 264 | else if (data[i] >= '0' && data[i] <= '9') |
| 265 | tmp_port = tmp_port*10 + data[i] - '0'; |
| 266 | else { /* Some other crap */ |
| 267 | DEBUGP("get_port: invalid char.\n"); |
| 268 | break; |
| 269 | } |
| 270 | } |
| 271 | return 0; |
| 272 | } |
| 273 | |
| 274 | /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */ |
| 275 | static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd, |
| 276 | char term) |
| 277 | { |
| 278 | char delim; |
| 279 | int length; |
| 280 | |
| 281 | /* First character is delimiter, then "1" for IPv4 or "2" for IPv6, |
| 282 | then delimiter again. */ |
| 283 | if (dlen <= 3) { |
| 284 | DEBUGP("EPRT: too short\n"); |
| 285 | return 0; |
| 286 | } |
| 287 | delim = data[0]; |
| 288 | if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) { |
| 289 | DEBUGP("try_eprt: invalid delimitter.\n"); |
| 290 | return 0; |
| 291 | } |
| 292 | |
| 293 | if ((cmd->l3num == PF_INET && data[1] != '1') || |
| 294 | (cmd->l3num == PF_INET6 && data[1] != '2')) { |
| 295 | DEBUGP("EPRT: invalid protocol number.\n"); |
| 296 | return 0; |
| 297 | } |
| 298 | |
| 299 | DEBUGP("EPRT: Got %c%c%c\n", delim, data[1], delim); |
| 300 | |
| 301 | if (data[1] == '1') { |
| 302 | u_int32_t array[4]; |
| 303 | |
| 304 | /* Now we have IP address. */ |
| 305 | length = try_number(data + 3, dlen - 3, array, 4, '.', delim); |
| 306 | if (length != 0) |
| 307 | cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16) |
| 308 | | (array[2] << 8) | array[3]); |
| 309 | } else { |
| 310 | /* Now we have IPv6 address. */ |
| 311 | length = get_ipv6_addr(data + 3, dlen - 3, |
| 312 | (struct in6_addr *)cmd->u3.ip6, delim); |
| 313 | } |
| 314 | |
| 315 | if (length == 0) |
| 316 | return 0; |
| 317 | DEBUGP("EPRT: Got IP address!\n"); |
| 318 | /* Start offset includes initial "|1|", and trailing delimiter */ |
| 319 | return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port); |
| 320 | } |
| 321 | |
| 322 | /* Returns 0, or length of numbers: |||6446| */ |
| 323 | static int try_epsv_response(const char *data, size_t dlen, |
| 324 | struct nf_conntrack_man *cmd, char term) |
| 325 | { |
| 326 | char delim; |
| 327 | |
| 328 | /* Three delimiters. */ |
| 329 | if (dlen <= 3) return 0; |
| 330 | delim = data[0]; |
| 331 | if (isdigit(delim) || delim < 33 || delim > 126 |
| 332 | || data[1] != delim || data[2] != delim) |
| 333 | return 0; |
| 334 | |
| 335 | return get_port(data, 3, dlen, delim, &cmd->u.tcp.port); |
| 336 | } |
| 337 | |
| 338 | /* Return 1 for match, 0 for accept, -1 for partial. */ |
| 339 | static int find_pattern(const char *data, size_t dlen, |
| 340 | const char *pattern, size_t plen, |
| 341 | char skip, char term, |
| 342 | unsigned int *numoff, |
| 343 | unsigned int *numlen, |
| 344 | struct nf_conntrack_man *cmd, |
| 345 | int (*getnum)(const char *, size_t, |
| 346 | struct nf_conntrack_man *, char)) |
| 347 | { |
| 348 | size_t i; |
| 349 | |
| 350 | DEBUGP("find_pattern `%s': dlen = %u\n", pattern, dlen); |
| 351 | if (dlen == 0) |
| 352 | return 0; |
| 353 | |
| 354 | if (dlen <= plen) { |
| 355 | /* Short packet: try for partial? */ |
| 356 | if (strnicmp(data, pattern, dlen) == 0) |
| 357 | return -1; |
| 358 | else return 0; |
| 359 | } |
| 360 | |
| 361 | if (strnicmp(data, pattern, plen) != 0) { |
| 362 | #if 0 |
| 363 | size_t i; |
| 364 | |
| 365 | DEBUGP("ftp: string mismatch\n"); |
| 366 | for (i = 0; i < plen; i++) { |
| 367 | DEBUGP("ftp:char %u `%c'(%u) vs `%c'(%u)\n", |
| 368 | i, data[i], data[i], |
| 369 | pattern[i], pattern[i]); |
| 370 | } |
| 371 | #endif |
| 372 | return 0; |
| 373 | } |
| 374 | |
| 375 | DEBUGP("Pattern matches!\n"); |
| 376 | /* Now we've found the constant string, try to skip |
| 377 | to the 'skip' character */ |
| 378 | for (i = plen; data[i] != skip; i++) |
| 379 | if (i == dlen - 1) return -1; |
| 380 | |
| 381 | /* Skip over the last character */ |
| 382 | i++; |
| 383 | |
| 384 | DEBUGP("Skipped up to `%c'!\n", skip); |
| 385 | |
| 386 | *numoff = i; |
| 387 | *numlen = getnum(data + i, dlen - i, cmd, term); |
| 388 | if (!*numlen) |
| 389 | return -1; |
| 390 | |
| 391 | DEBUGP("Match succeeded!\n"); |
| 392 | return 1; |
| 393 | } |
| 394 | |
| 395 | /* Look up to see if we're just after a \n. */ |
| 396 | static int find_nl_seq(u32 seq, const struct ip_ct_ftp_master *info, int dir) |
| 397 | { |
| 398 | unsigned int i; |
| 399 | |
| 400 | for (i = 0; i < info->seq_aft_nl_num[dir]; i++) |
| 401 | if (info->seq_aft_nl[dir][i] == seq) |
| 402 | return 1; |
| 403 | return 0; |
| 404 | } |
| 405 | |
| 406 | /* We don't update if it's older than what we have. */ |
| 407 | static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir, |
| 408 | struct sk_buff *skb) |
| 409 | { |
| 410 | unsigned int i, oldest = NUM_SEQ_TO_REMEMBER; |
| 411 | |
| 412 | /* Look for oldest: if we find exact match, we're done. */ |
| 413 | for (i = 0; i < info->seq_aft_nl_num[dir]; i++) { |
| 414 | if (info->seq_aft_nl[dir][i] == nl_seq) |
| 415 | return; |
| 416 | |
| 417 | if (oldest == info->seq_aft_nl_num[dir] |
| 418 | || before(info->seq_aft_nl[dir][i], oldest)) |
| 419 | oldest = i; |
| 420 | } |
| 421 | |
| 422 | if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) { |
| 423 | info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq; |
| 424 | nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb); |
| 425 | } else if (oldest != NUM_SEQ_TO_REMEMBER) { |
| 426 | info->seq_aft_nl[dir][oldest] = nl_seq; |
| 427 | nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb); |
| 428 | } |
| 429 | } |
| 430 | |
| 431 | static int help(struct sk_buff **pskb, |
| 432 | unsigned int protoff, |
| 433 | struct nf_conn *ct, |
| 434 | enum ip_conntrack_info ctinfo) |
| 435 | { |
| 436 | unsigned int dataoff, datalen; |
| 437 | struct tcphdr _tcph, *th; |
| 438 | char *fb_ptr; |
| 439 | int ret; |
| 440 | u32 seq; |
| 441 | int dir = CTINFO2DIR(ctinfo); |
| 442 | unsigned int matchlen, matchoff; |
| 443 | struct ip_ct_ftp_master *ct_ftp_info = &ct->help->ct_ftp_info; |
| 444 | struct nf_conntrack_expect *exp; |
| 445 | struct nf_conntrack_man cmd = {}; |
| 446 | |
| 447 | unsigned int i; |
| 448 | int found = 0, ends_in_nl; |
| 449 | |
| 450 | /* Until there's been traffic both ways, don't look in packets. */ |
| 451 | if (ctinfo != IP_CT_ESTABLISHED |
| 452 | && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) { |
| 453 | DEBUGP("ftp: Conntrackinfo = %u\n", ctinfo); |
| 454 | return NF_ACCEPT; |
| 455 | } |
| 456 | |
| 457 | th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph); |
| 458 | if (th == NULL) |
| 459 | return NF_ACCEPT; |
| 460 | |
| 461 | dataoff = protoff + th->doff * 4; |
| 462 | /* No data? */ |
| 463 | if (dataoff >= (*pskb)->len) { |
| 464 | DEBUGP("ftp: dataoff(%u) >= skblen(%u)\n", dataoff, |
| 465 | (*pskb)->len); |
| 466 | return NF_ACCEPT; |
| 467 | } |
| 468 | datalen = (*pskb)->len - dataoff; |
| 469 | |
| 470 | spin_lock_bh(&nf_ftp_lock); |
| 471 | fb_ptr = skb_header_pointer(*pskb, dataoff, datalen, ftp_buffer); |
| 472 | BUG_ON(fb_ptr == NULL); |
| 473 | |
| 474 | ends_in_nl = (fb_ptr[datalen - 1] == '\n'); |
| 475 | seq = ntohl(th->seq) + datalen; |
| 476 | |
| 477 | /* Look up to see if we're just after a \n. */ |
| 478 | if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) { |
| 479 | /* Now if this ends in \n, update ftp info. */ |
| 480 | DEBUGP("nf_conntrack_ftp_help: wrong seq pos %s(%u) or %s(%u)\n", |
| 481 | ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)", |
| 482 | ct_ftp_info->seq_aft_nl[dir][0], |
| 483 | ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)", |
| 484 | ct_ftp_info->seq_aft_nl[dir][1]); |
| 485 | ret = NF_ACCEPT; |
| 486 | goto out_update_nl; |
| 487 | } |
| 488 | |
| 489 | /* Initialize IP/IPv6 addr to expected address (it's not mentioned |
| 490 | in EPSV responses) */ |
| 491 | cmd.l3num = ct->tuplehash[dir].tuple.src.l3num; |
| 492 | memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all, |
| 493 | sizeof(cmd.u3.all)); |
| 494 | |
| 495 | for (i = 0; i < ARRAY_SIZE(search); i++) { |
| 496 | if (search[i].dir != dir) continue; |
| 497 | |
| 498 | found = find_pattern(fb_ptr, datalen, |
| 499 | search[i].pattern, |
| 500 | search[i].plen, |
| 501 | search[i].skip, |
| 502 | search[i].term, |
| 503 | &matchoff, &matchlen, |
| 504 | &cmd, |
| 505 | search[i].getnum); |
| 506 | if (found) break; |
| 507 | } |
| 508 | if (found == -1) { |
| 509 | /* We don't usually drop packets. After all, this is |
| 510 | connection tracking, not packet filtering. |
| 511 | However, it is necessary for accurate tracking in |
| 512 | this case. */ |
| 513 | if (net_ratelimit()) |
| 514 | printk("conntrack_ftp: partial %s %u+%u\n", |
| 515 | search[i].pattern, |
| 516 | ntohl(th->seq), datalen); |
| 517 | ret = NF_DROP; |
| 518 | goto out; |
| 519 | } else if (found == 0) { /* No match */ |
| 520 | ret = NF_ACCEPT; |
| 521 | goto out_update_nl; |
| 522 | } |
| 523 | |
| 524 | DEBUGP("conntrack_ftp: match `%.*s' (%u bytes at %u)\n", |
| 525 | (int)matchlen, fb_ptr + matchoff, |
| 526 | matchlen, ntohl(th->seq) + matchoff); |
| 527 | |
| 528 | exp = nf_conntrack_expect_alloc(ct); |
| 529 | if (exp == NULL) { |
| 530 | ret = NF_DROP; |
| 531 | goto out; |
| 532 | } |
| 533 | |
| 534 | /* We refer to the reverse direction ("!dir") tuples here, |
| 535 | * because we're expecting something in the other direction. |
| 536 | * Doesn't matter unless NAT is happening. */ |
| 537 | exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3; |
| 538 | |
| 539 | /* Update the ftp info */ |
| 540 | if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) && |
| 541 | memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all, |
| 542 | sizeof(cmd.u3.all))) { |
| 543 | /* Enrico Scholz's passive FTP to partially RNAT'd ftp |
| 544 | server: it really wants us to connect to a |
| 545 | different IP address. Simply don't record it for |
| 546 | NAT. */ |
| 547 | if (cmd.l3num == PF_INET) { |
| 548 | DEBUGP("conntrack_ftp: NOT RECORDING: %u,%u,%u,%u != %u.%u.%u.%u\n", |
| 549 | NIPQUAD(cmd.u3.ip), |
| 550 | NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip)); |
| 551 | } else { |
| 552 | DEBUGP("conntrack_ftp: NOT RECORDING: %x:%x:%x:%x:%x:%x:%x:%x != %x:%x:%x:%x:%x:%x:%x:%x\n", |
| 553 | NIP6(*((struct in6_addr *)cmd.u3.ip6)), |
| 554 | NIP6(*((struct in6_addr *)ct->tuplehash[dir] |
| 555 | .tuple.src.u3.ip6))); |
| 556 | } |
| 557 | |
| 558 | /* Thanks to Cristiano Lincoln Mattos |
| 559 | <lincoln@cesar.org.br> for reporting this potential |
| 560 | problem (DMZ machines opening holes to internal |
| 561 | networks, or the packet filter itself). */ |
| 562 | if (!loose) { |
| 563 | ret = NF_ACCEPT; |
| 564 | goto out_put_expect; |
| 565 | } |
| 566 | memcpy(&exp->tuple.dst.u3, &cmd.u3.all, |
| 567 | sizeof(exp->tuple.dst.u3)); |
| 568 | } |
| 569 | |
| 570 | exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3; |
| 571 | exp->tuple.src.l3num = cmd.l3num; |
| 572 | exp->tuple.src.u.tcp.port = 0; |
| 573 | exp->tuple.dst.u.tcp.port = cmd.u.tcp.port; |
| 574 | exp->tuple.dst.protonum = IPPROTO_TCP; |
| 575 | |
| 576 | exp->mask = (struct nf_conntrack_tuple) |
| 577 | { .src = { .l3num = 0xFFFF, |
| 578 | .u = { .tcp = { 0 }}, |
| 579 | }, |
| 580 | .dst = { .protonum = 0xFF, |
| 581 | .u = { .tcp = { 0xFFFF }}, |
| 582 | }, |
| 583 | }; |
| 584 | if (cmd.l3num == PF_INET) { |
| 585 | exp->mask.src.u3.ip = 0xFFFFFFFF; |
| 586 | exp->mask.dst.u3.ip = 0xFFFFFFFF; |
| 587 | } else { |
| 588 | memset(exp->mask.src.u3.ip6, 0xFF, |
| 589 | sizeof(exp->mask.src.u3.ip6)); |
| 590 | memset(exp->mask.dst.u3.ip6, 0xFF, |
| 591 | sizeof(exp->mask.src.u3.ip6)); |
| 592 | } |
| 593 | |
| 594 | exp->expectfn = NULL; |
| 595 | exp->flags = 0; |
| 596 | |
| 597 | /* Now, NAT might want to mangle the packet, and register the |
| 598 | * (possibly changed) expectation itself. */ |
| 599 | if (nf_nat_ftp_hook) |
| 600 | ret = nf_nat_ftp_hook(pskb, ctinfo, search[i].ftptype, |
| 601 | matchoff, matchlen, exp, &seq); |
| 602 | else { |
| 603 | /* Can't expect this? Best to drop packet now. */ |
| 604 | if (nf_conntrack_expect_related(exp) != 0) |
| 605 | ret = NF_DROP; |
| 606 | else |
| 607 | ret = NF_ACCEPT; |
| 608 | } |
| 609 | |
| 610 | out_put_expect: |
| 611 | nf_conntrack_expect_put(exp); |
| 612 | |
| 613 | out_update_nl: |
| 614 | /* Now if this ends in \n, update ftp info. Seq may have been |
| 615 | * adjusted by NAT code. */ |
| 616 | if (ends_in_nl) |
| 617 | update_nl_seq(seq, ct_ftp_info, dir, *pskb); |
| 618 | out: |
| 619 | spin_unlock_bh(&nf_ftp_lock); |
| 620 | return ret; |
| 621 | } |
| 622 | |
| 623 | static struct nf_conntrack_helper ftp[MAX_PORTS][2]; |
| 624 | static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")]; |
| 625 | |
| 626 | /* don't make this __exit, since it's called from __init ! */ |
| 627 | static void fini(void) |
| 628 | { |
| 629 | int i, j; |
| 630 | for (i = 0; i < ports_c; i++) { |
| 631 | for (j = 0; j < 2; j++) { |
| 632 | if (ftp[i][j].me == NULL) |
| 633 | continue; |
| 634 | |
| 635 | DEBUGP("nf_ct_ftp: unregistering helper for pf: %d " |
| 636 | "port: %d\n", |
| 637 | ftp[i][j].tuple.src.l3num, ports[i]); |
| 638 | nf_conntrack_helper_unregister(&ftp[i][j]); |
| 639 | } |
| 640 | } |
| 641 | |
| 642 | kfree(ftp_buffer); |
| 643 | } |
| 644 | |
| 645 | static int __init init(void) |
| 646 | { |
| 647 | int i, j = -1, ret = 0; |
| 648 | char *tmpname; |
| 649 | |
| 650 | ftp_buffer = kmalloc(65536, GFP_KERNEL); |
| 651 | if (!ftp_buffer) |
| 652 | return -ENOMEM; |
| 653 | |
| 654 | if (ports_c == 0) |
| 655 | ports[ports_c++] = FTP_PORT; |
| 656 | |
| 657 | /* FIXME should be configurable whether IPv4 and IPv6 FTP connections |
| 658 | are tracked or not - YK */ |
| 659 | for (i = 0; i < ports_c; i++) { |
| 660 | memset(&ftp[i], 0, sizeof(struct nf_conntrack_helper)); |
| 661 | |
| 662 | ftp[i][0].tuple.src.l3num = PF_INET; |
| 663 | ftp[i][1].tuple.src.l3num = PF_INET6; |
| 664 | for (j = 0; j < 2; j++) { |
| 665 | ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]); |
| 666 | ftp[i][j].tuple.dst.protonum = IPPROTO_TCP; |
| 667 | ftp[i][j].mask.src.u.tcp.port = 0xFFFF; |
| 668 | ftp[i][j].mask.dst.protonum = 0xFF; |
| 669 | ftp[i][j].max_expected = 1; |
| 670 | ftp[i][j].timeout = 5 * 60; /* 5 Minutes */ |
| 671 | ftp[i][j].me = THIS_MODULE; |
| 672 | ftp[i][j].help = help; |
| 673 | tmpname = &ftp_names[i][j][0]; |
| 674 | if (ports[i] == FTP_PORT) |
| 675 | sprintf(tmpname, "ftp"); |
| 676 | else |
| 677 | sprintf(tmpname, "ftp-%d", ports[i]); |
| 678 | ftp[i][j].name = tmpname; |
| 679 | |
| 680 | DEBUGP("nf_ct_ftp: registering helper for pf: %d " |
| 681 | "port: %d\n", |
| 682 | ftp[i][j].tuple.src.l3num, ports[i]); |
| 683 | ret = nf_conntrack_helper_register(&ftp[i][j]); |
| 684 | if (ret) { |
| 685 | printk("nf_ct_ftp: failed to register helper " |
| 686 | " for pf: %d port: %d\n", |
| 687 | ftp[i][j].tuple.src.l3num, ports[i]); |
| 688 | fini(); |
| 689 | return ret; |
| 690 | } |
| 691 | } |
| 692 | } |
| 693 | |
| 694 | return 0; |
| 695 | } |
| 696 | |
| 697 | module_init(init); |
| 698 | module_exit(fini); |