net/netfilter/nf_conntrack_ftp.c

   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  * (C) 2006-2012 Patrick McHardy <kaber@trash.net>
   7  *
   8  * This program is free software; you can redistribute it and/or modify
   9  * it under the terms of the GNU General Public License version 2 as
  10  * published by the Free Software Foundation.
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/moduleparam.h>
  15 #include <linux/netfilter.h>
  16 #include <linux/ip.h>
  17 #include <linux/slab.h>
  18 #include <linux/ipv6.h>
  19 #include <linux/ctype.h>
  20 #include <linux/inet.h>
  21 #include <net/checksum.h>
  22 #include <net/tcp.h>
  23
  24 #include <net/netfilter/nf_conntrack.h>
  25 #include <net/netfilter/nf_conntrack_expect.h>
  26 #include <net/netfilter/nf_conntrack_ecache.h>
  27 #include <net/netfilter/nf_conntrack_helper.h>
  28 #include <linux/netfilter/nf_conntrack_ftp.h>
  29
  30 MODULE_LICENSE("GPL");
  31 MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
  32 MODULE_DESCRIPTION("ftp connection tracking helper");
  33 MODULE_ALIAS("ip_conntrack_ftp");
  34 MODULE_ALIAS_NFCT_HELPER("ftp");
  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 bool loose;
  47 module_param(loose, bool, 0600);
  48
  49 unsigned int (*nf_nat_ftp_hook)(struct sk_buff *skb,
  50                                 enum ip_conntrack_info ctinfo,
  51                                 enum nf_ct_ftp_type type,
  52                                 unsigned int protoff,
  53                                 unsigned int matchoff,
  54                                 unsigned int matchlen,
  55                                 struct nf_conntrack_expect *exp);
  56 EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
  57
  58 static int try_rfc959(const char *, size_t, struct nf_conntrack_man *,
  59                       char, unsigned int *);
  60 static int try_rfc1123(const char *, size_t, struct nf_conntrack_man *,
  61                        char, unsigned int *);
  62 static int try_eprt(const char *, size_t, struct nf_conntrack_man *,
  63                     char, unsigned int *);
  64 static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
  65                              char, unsigned int *);
  66
  67 static struct ftp_search {
  68         const char *pattern;
  69         size_t plen;
  70         char skip;
  71         char term;
  72         enum nf_ct_ftp_type ftptype;
  73         int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char, unsigned int *);
  74 } search[IP_CT_DIR_MAX][2] = {
  75         [IP_CT_DIR_ORIGINAL] = {
  76                 {
  77                         .pattern        = "PORT",
  78                         .plen           = sizeof("PORT") - 1,
  79                         .skip           = ' ',
  80                         .term           = '\r',
  81                         .ftptype        = NF_CT_FTP_PORT,
  82                         .getnum         = try_rfc959,
  83                 },
  84                 {
  85                         .pattern        = "EPRT",
  86                         .plen           = sizeof("EPRT") - 1,
  87                         .skip           = ' ',
  88                         .term           = '\r',
  89                         .ftptype        = NF_CT_FTP_EPRT,
  90                         .getnum         = try_eprt,
  91                 },
  92         },
  93         [IP_CT_DIR_REPLY] = {
  94                 {
  95                         .pattern        = "227 ",
  96                         .plen           = sizeof("227 ") - 1,
  97                         .ftptype        = NF_CT_FTP_PASV,
  98                         .getnum         = try_rfc1123,
  99                 },
 100                 {
 101                         .pattern        = "229 ",
 102                         .plen           = sizeof("229 ") - 1,
 103                         .skip           = '(',
 104                         .term           = ')',
 105                         .ftptype        = NF_CT_FTP_EPSV,
 106                         .getnum         = try_epsv_response,
 107                 },
 108         },
 109 };
 110
 111 static int
 112 get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
 113 {
 114         const char *end;
 115         int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
 116         if (ret > 0)
 117                 return (int)(end - src);
 118         return 0;
 119 }
 120
 121 static int try_number(const char *data, size_t dlen, u_int32_t array[],
 122                       int array_size, char sep, char term)
 123 {
 124         u_int32_t i, len;
 125
 126         memset(array, 0, sizeof(array[0])*array_size);
 127
 128         /* Keep data pointing at next char. */
 129         for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
 130                 if (*data >= '0' && *data <= '9') {
 131                         array[i] = array[i]*10 + *data - '0';
 132                 }
 133                 else if (*data == sep)
 134                         i++;
 135                 else {
 136                         /* Unexpected character; true if it's the
 137                            terminator (or we don't care about one)
 138                            and we're finished. */
 139                         if ((*data == term || !term) && i == array_size - 1)
 140                                 return len;
 141
 142                         pr_debug("Char %u (got %u nums) `%u' unexpected\n",
 143                                  len, i, *data);
 144                         return 0;
 145                 }
 146         }
 147         pr_debug("Failed to fill %u numbers separated by %c\n",
 148                  array_size, sep);
 149         return 0;
 150 }
 151
 152 /* Returns 0, or length of numbers: 192,168,1,1,5,6 */
 153 static int try_rfc959(const char *data, size_t dlen,
 154                       struct nf_conntrack_man *cmd, char term,
 155                       unsigned int *offset)
 156 {
 157         int length;
 158         u_int32_t array[6];
 159
 160         length = try_number(data, dlen, array, 6, ',', term);
 161         if (length == 0)
 162                 return 0;
 163
 164         cmd->u3.ip =  htonl((array[0] << 24) | (array[1] << 16) |
 165                                     (array[2] << 8) | array[3]);
 166         cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
 167         return length;
 168 }
 169
 170 /*
 171  * From RFC 1123:
 172  * The format of the 227 reply to a PASV command is not
 173  * well standardized.  In particular, an FTP client cannot
 174  * assume that the parentheses shown on page 40 of RFC-959
 175  * will be present (and in fact, Figure 3 on page 43 omits
 176  * them).  Therefore, a User-FTP program that interprets
 177  * the PASV reply must scan the reply for the first digit
 178  * of the host and port numbers.
 179  */
 180 static int try_rfc1123(const char *data, size_t dlen,
 181                        struct nf_conntrack_man *cmd, char term,
 182                        unsigned int *offset)
 183 {
 184         int i;
 185         for (i = 0; i < dlen; i++)
 186                 if (isdigit(data[i]))
 187                         break;
 188
 189         if (i == dlen)
 190                 return 0;
 191
 192         *offset += i;
 193
 194         return try_rfc959(data + i, dlen - i, cmd, 0, offset);
 195 }
 196
 197 /* Grab port: number up to delimiter */
 198 static int get_port(const char *data, int start, size_t dlen, char delim,
 199                     __be16 *port)
 200 {
 201         u_int16_t tmp_port = 0;
 202         int i;
 203
 204         for (i = start; i < dlen; i++) {
 205                 /* Finished? */
 206                 if (data[i] == delim) {
 207                         if (tmp_port == 0)
 208                                 break;
 209                         *port = htons(tmp_port);
 210                         pr_debug("get_port: return %d\n", tmp_port);
 211                         return i + 1;
 212                 }
 213                 else if (data[i] >= '0' && data[i] <= '9')
 214                         tmp_port = tmp_port*10 + data[i] - '0';
 215                 else { /* Some other crap */
 216                         pr_debug("get_port: invalid char.\n");
 217                         break;
 218                 }
 219         }
 220         return 0;
 221 }
 222
 223 /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
 224 static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
 225                     char term, unsigned int *offset)
 226 {
 227         char delim;
 228         int length;
 229
 230         /* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
 231            then delimiter again. */
 232         if (dlen <= 3) {
 233                 pr_debug("EPRT: too short\n");
 234                 return 0;
 235         }
 236         delim = data[0];
 237         if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
 238                 pr_debug("try_eprt: invalid delimitter.\n");
 239                 return 0;
 240         }
 241
 242         if ((cmd->l3num == PF_INET && data[1] != '1') ||
 243             (cmd->l3num == PF_INET6 && data[1] != '2')) {
 244                 pr_debug("EPRT: invalid protocol number.\n");
 245                 return 0;
 246         }
 247
 248         pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim);
 249
 250         if (data[1] == '1') {
 251                 u_int32_t array[4];
 252
 253                 /* Now we have IP address. */
 254                 length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
 255                 if (length != 0)
 256                         cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
 257                                            | (array[2] << 8) | array[3]);
 258         } else {
 259                 /* Now we have IPv6 address. */
 260                 length = get_ipv6_addr(data + 3, dlen - 3,
 261                                        (struct in6_addr *)cmd->u3.ip6, delim);
 262         }
 263
 264         if (length == 0)
 265                 return 0;
 266         pr_debug("EPRT: Got IP address!\n");
 267         /* Start offset includes initial "|1|", and trailing delimiter */
 268         return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
 269 }
 270
 271 /* Returns 0, or length of numbers: |||6446| */
 272 static int try_epsv_response(const char *data, size_t dlen,
 273                              struct nf_conntrack_man *cmd, char term,
 274                              unsigned int *offset)
 275 {
 276         char delim;
 277
 278         /* Three delimiters. */
 279         if (dlen <= 3) return 0;
 280         delim = data[0];
 281         if (isdigit(delim) || delim < 33 || delim > 126 ||
 282             data[1] != delim || data[2] != delim)
 283                 return 0;
 284
 285         return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
 286 }
 287
 288 /* Return 1 for match, 0 for accept, -1 for partial. */
 289 static int find_pattern(const char *data, size_t dlen,
 290                         const char *pattern, size_t plen,
 291                         char skip, char term,
 292                         unsigned int *numoff,
 293                         unsigned int *numlen,
 294                         struct nf_conntrack_man *cmd,
 295                         int (*getnum)(const char *, size_t,
 296                                       struct nf_conntrack_man *, char,
 297                                       unsigned int *))
 298 {
 299         size_t i = plen;
 300
 301         pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen);
 302         if (dlen == 0)
 303                 return 0;
 304
 305         if (dlen <= plen) {
 306                 /* Short packet: try for partial? */
 307                 if (strnicmp(data, pattern, dlen) == 0)
 308                         return -1;
 309                 else return 0;
 310         }
 311
 312         if (strnicmp(data, pattern, plen) != 0) {
 313 #if 0
 314                 size_t i;
 315
 316                 pr_debug("ftp: string mismatch\n");
 317                 for (i = 0; i < plen; i++) {
 318                         pr_debug("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
 319                                  i, data[i], data[i],
 320                                  pattern[i], pattern[i]);
 321                 }
 322 #endif
 323                 return 0;
 324         }
 325
 326         pr_debug("Pattern matches!\n");
 327         /* Now we've found the constant string, try to skip
 328            to the 'skip' character */
 329         if (skip) {
 330                 for (i = plen; data[i] != skip; i++)
 331                         if (i == dlen - 1) return -1;
 332
 333                 /* Skip over the last character */
 334                 i++;
 335         }
 336
 337         pr_debug("Skipped up to `%c'!\n", skip);
 338
 339         *numoff = i;
 340         *numlen = getnum(data + i, dlen - i, cmd, term, numoff);
 341         if (!*numlen)
 342                 return -1;
 343
 344         pr_debug("Match succeeded!\n");
 345         return 1;
 346 }
 347
 348 /* Look up to see if we're just after a \n. */
 349 static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
 350 {
 351         unsigned int i;
 352
 353         for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
 354                 if (info->seq_aft_nl[dir][i] == seq)
 355                         return 1;
 356         return 0;
 357 }
 358
 359 /* We don't update if it's older than what we have. */
 360 static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
 361                           struct nf_ct_ftp_master *info, int dir,
 362                           struct sk_buff *skb)
 363 {
 364         unsigned int i, oldest;
 365
 366         /* Look for oldest: if we find exact match, we're done. */
 367         for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
 368                 if (info->seq_aft_nl[dir][i] == nl_seq)
 369                         return;
 370         }
 371
 372         if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
 373                 info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
 374         } else {
 375                 if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
 376                         oldest = 0;
 377                 else
 378                         oldest = 1;
 379
 380                 if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
 381                         info->seq_aft_nl[dir][oldest] = nl_seq;
 382         }
 383 }
 384
 385 static int help(struct sk_buff *skb,
 386                 unsigned int protoff,
 387                 struct nf_conn *ct,
 388                 enum ip_conntrack_info ctinfo)
 389 {
 390         unsigned int dataoff, datalen;
 391         const struct tcphdr *th;
 392         struct tcphdr _tcph;
 393         const char *fb_ptr;
 394         int ret;
 395         u32 seq;
 396         int dir = CTINFO2DIR(ctinfo);
 397         unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff);
 398         struct nf_ct_ftp_master *ct_ftp_info = nfct_help_data(ct);
 399         struct nf_conntrack_expect *exp;
 400         union nf_inet_addr *daddr;
 401         struct nf_conntrack_man cmd = {};
 402         unsigned int i;
 403         int found = 0, ends_in_nl;
 404         typeof(nf_nat_ftp_hook) nf_nat_ftp;
 405
 406         /* Until there's been traffic both ways, don't look in packets. */
 407         if (ctinfo != IP_CT_ESTABLISHED &&
 408             ctinfo != IP_CT_ESTABLISHED_REPLY) {
 409                 pr_debug("ftp: Conntrackinfo = %u\n", ctinfo);
 410                 return NF_ACCEPT;
 411         }
 412
 413         th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
 414         if (th == NULL)
 415                 return NF_ACCEPT;
 416
 417         dataoff = protoff + th->doff * 4;
 418         /* No data? */
 419         if (dataoff >= skb->len) {
 420                 pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
 421                          skb->len);
 422                 return NF_ACCEPT;
 423         }
 424         datalen = skb->len - dataoff;
 425
 426         spin_lock_bh(&nf_ftp_lock);
 427         fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer);
 428         BUG_ON(fb_ptr == NULL);
 429
 430         ends_in_nl = (fb_ptr[datalen - 1] == '\n');
 431         seq = ntohl(th->seq) + datalen;
 432
 433         /* Look up to see if we're just after a \n. */
 434         if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
 435                 /* We're picking up this, clear flags and let it continue */
 436                 if (unlikely(ct_ftp_info->flags[dir] & NF_CT_FTP_SEQ_PICKUP)) {
 437                         ct_ftp_info->flags[dir] ^= NF_CT_FTP_SEQ_PICKUP;
 438                         goto skip_nl_seq;
 439                 }
 440
 441                 /* Now if this ends in \n, update ftp info. */
 442                 pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
 443                          ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
 444                          ct_ftp_info->seq_aft_nl[dir][0],
 445                          ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
 446                          ct_ftp_info->seq_aft_nl[dir][1]);
 447                 ret = NF_ACCEPT;
 448                 goto out_update_nl;
 449         }
 450
 451 skip_nl_seq:
 452         /* Initialize IP/IPv6 addr to expected address (it's not mentioned
 453            in EPSV responses) */
 454         cmd.l3num = nf_ct_l3num(ct);
 455         memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 456                sizeof(cmd.u3.all));
 457
 458         for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
 459                 found = find_pattern(fb_ptr, datalen,
 460                                      search[dir][i].pattern,
 461                                      search[dir][i].plen,
 462                                      search[dir][i].skip,
 463                                      search[dir][i].term,
 464                                      &matchoff, &matchlen,
 465                                      &cmd,
 466                                      search[dir][i].getnum);
 467                 if (found) break;
 468         }
 469         if (found == -1) {
 470                 /* We don't usually drop packets.  After all, this is
 471                    connection tracking, not packet filtering.
 472                    However, it is necessary for accurate tracking in
 473                    this case. */
 474                 nf_ct_helper_log(skb, ct, "partial matching of `%s'",
 475                                  search[dir][i].pattern);
 476                 ret = NF_DROP;
 477                 goto out;
 478         } else if (found == 0) { /* No match */
 479                 ret = NF_ACCEPT;
 480                 goto out_update_nl;
 481         }
 482
 483         pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
 484                  matchlen, fb_ptr + matchoff,
 485                  matchlen, ntohl(th->seq) + matchoff);
 486
 487         exp = nf_ct_expect_alloc(ct);
 488         if (exp == NULL) {
 489                 nf_ct_helper_log(skb, ct, "cannot alloc expectation");
 490                 ret = NF_DROP;
 491                 goto out;
 492         }
 493
 494         /* We refer to the reverse direction ("!dir") tuples here,
 495          * because we're expecting something in the other direction.
 496          * Doesn't matter unless NAT is happening.  */
 497         daddr = &ct->tuplehash[!dir].tuple.dst.u3;
 498
 499         /* Update the ftp info */
 500         if ((cmd.l3num == nf_ct_l3num(ct)) &&
 501             memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 502                      sizeof(cmd.u3.all))) {
 503                 /* Enrico Scholz's passive FTP to partially RNAT'd ftp
 504                    server: it really wants us to connect to a
 505                    different IP address.  Simply don't record it for
 506                    NAT. */
 507                 if (cmd.l3num == PF_INET) {
 508                         pr_debug("conntrack_ftp: NOT RECORDING: %pI4 != %pI4\n",
 509                                  &cmd.u3.ip,
 510                                  &ct->tuplehash[dir].tuple.src.u3.ip);
 511                 } else {
 512                         pr_debug("conntrack_ftp: NOT RECORDING: %pI6 != %pI6\n",
 513                                  cmd.u3.ip6,
 514                                  ct->tuplehash[dir].tuple.src.u3.ip6);
 515                 }
 516
 517                 /* Thanks to Cristiano Lincoln Mattos
 518                    <lincoln@cesar.org.br> for reporting this potential
 519                    problem (DMZ machines opening holes to internal
 520                    networks, or the packet filter itself). */
 521                 if (!loose) {
 522                         ret = NF_ACCEPT;
 523                         goto out_put_expect;
 524                 }
 525                 daddr = &cmd.u3;
 526         }
 527
 528         nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num,
 529                           &ct->tuplehash[!dir].tuple.src.u3, daddr,
 530                           IPPROTO_TCP, NULL, &cmd.u.tcp.port);
 531
 532         /* Now, NAT might want to mangle the packet, and register the
 533          * (possibly changed) expectation itself. */
 534         nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
 535         if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
 536                 ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype,
 537                                  protoff, matchoff, matchlen, exp);
 538         else {
 539                 /* Can't expect this?  Best to drop packet now. */
 540                 if (nf_ct_expect_related(exp) != 0) {
 541                         nf_ct_helper_log(skb, ct, "cannot add expectation");
 542                         ret = NF_DROP;
 543                 } else
 544                         ret = NF_ACCEPT;
 545         }
 546
 547 out_put_expect:
 548         nf_ct_expect_put(exp);
 549
 550 out_update_nl:
 551         /* Now if this ends in \n, update ftp info.  Seq may have been
 552          * adjusted by NAT code. */
 553         if (ends_in_nl)
 554                 update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
 555  out:
 556         spin_unlock_bh(&nf_ftp_lock);
 557         return ret;
 558 }
 559
 560 static int nf_ct_ftp_from_nlattr(struct nlattr *attr, struct nf_conn *ct)
 561 {
 562         struct nf_ct_ftp_master *ftp = nfct_help_data(ct);
 563
 564         /* This conntrack has been injected from user-space, always pick up
 565          * sequence tracking. Otherwise, the first FTP command after the
 566          * failover breaks.
 567          */
 568         ftp->flags[IP_CT_DIR_ORIGINAL] |= NF_CT_FTP_SEQ_PICKUP;
 569         ftp->flags[IP_CT_DIR_REPLY] |= NF_CT_FTP_SEQ_PICKUP;
 570         return 0;
 571 }
 572
 573 static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
 574
 575 static const struct nf_conntrack_expect_policy ftp_exp_policy = {
 576         .max_expected   = 1,
 577         .timeout        = 5 * 60,
 578 };
 579
 580 /* don't make this __exit, since it's called from __init ! */
 581 static void nf_conntrack_ftp_fini(void)
 582 {
 583         int i, j;
 584         for (i = 0; i < ports_c; i++) {
 585                 for (j = 0; j < 2; j++) {
 586                         if (ftp[i][j].me == NULL)
 587                                 continue;
 588
 589                         pr_debug("nf_ct_ftp: unregistering helper for pf: %d "
 590                                  "port: %d\n",
 591                                  ftp[i][j].tuple.src.l3num, ports[i]);
 592                         nf_conntrack_helper_unregister(&ftp[i][j]);
 593                 }
 594         }
 595
 596         kfree(ftp_buffer);
 597 }
 598
 599 static int __init nf_conntrack_ftp_init(void)
 600 {
 601         int i, j = -1, ret = 0;
 602
 603         ftp_buffer = kmalloc(65536, GFP_KERNEL);
 604         if (!ftp_buffer)
 605                 return -ENOMEM;
 606
 607         if (ports_c == 0)
 608                 ports[ports_c++] = FTP_PORT;
 609
 610         /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
 611                  are tracked or not - YK */
 612         for (i = 0; i < ports_c; i++) {
 613                 ftp[i][0].tuple.src.l3num = PF_INET;
 614                 ftp[i][1].tuple.src.l3num = PF_INET6;
 615                 for (j = 0; j < 2; j++) {
 616                         ftp[i][j].data_len = sizeof(struct nf_ct_ftp_master);
 617                         ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
 618                         ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
 619                         ftp[i][j].expect_policy = &ftp_exp_policy;
 620                         ftp[i][j].me = THIS_MODULE;
 621                         ftp[i][j].help = help;
 622                         ftp[i][j].from_nlattr = nf_ct_ftp_from_nlattr;
 623                         if (ports[i] == FTP_PORT)
 624                                 sprintf(ftp[i][j].name, "ftp");
 625                         else
 626                                 sprintf(ftp[i][j].name, "ftp-%d", ports[i]);
 627
 628                         pr_debug("nf_ct_ftp: registering helper for pf: %d "
 629                                  "port: %d\n",
 630                                  ftp[i][j].tuple.src.l3num, ports[i]);
 631                         ret = nf_conntrack_helper_register(&ftp[i][j]);
 632                         if (ret) {
 633                                 printk(KERN_ERR "nf_ct_ftp: failed to register"
 634                                        " helper for pf: %d port: %d\n",
 635                                         ftp[i][j].tuple.src.l3num, ports[i]);
 636                                 nf_conntrack_ftp_fini();
 637                                 return ret;
 638                         }
 639                 }
 640         }
 641
 642         return 0;
 643 }
 644
 645 module_init(nf_conntrack_ftp_init);
 646 module_exit(nf_conntrack_ftp_fini);