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