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  *
   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/module.h>
  19 #include <linux/moduleparam.h>
  20 #include <linux/netfilter.h>
  21 #include <linux/ip.h>
  22 #include <linux/ipv6.h>
  23 #include <linux/ctype.h>
  24 #include <linux/inet.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;
  47 module_param(loose, bool, 0600);
  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         const char *pattern;
  71         size_t plen;
  72         char skip;
  73         char term;
  74         enum ip_ct_ftp_type ftptype;
  75         int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char);
  76 } search[IP_CT_DIR_MAX][2] = {
  77         [IP_CT_DIR_ORIGINAL] = {
  78                 {
  79                         .pattern        = "PORT",
  80                         .plen           = sizeof("PORT") - 1,
  81                         .skip           = ' ',
  82                         .term           = '\r',
  83                         .ftptype        = IP_CT_FTP_PORT,
  84                         .getnum         = try_rfc959,
  85                 },
  86                 {
  87                         .pattern        = "EPRT",
  88                         .plen           = sizeof("EPRT") - 1,
  89                         .skip           = ' ',
  90                         .term           = '\r',
  91                         .ftptype        = IP_CT_FTP_EPRT,
  92                         .getnum         = try_eprt,
  93                 },
  94         },
  95         [IP_CT_DIR_REPLY] = {
  96                 {
  97                         .pattern        = "227 ",
  98                         .plen           = sizeof("227 ") - 1,
  99                         .skip           = '(',
 100                         .term           = ')',
 101                         .ftptype        = IP_CT_FTP_PASV,
 102                         .getnum         = try_rfc959,
 103                 },
 104                 {
 105                         .pattern        = "229 ",
 106                         .plen           = sizeof("229 ") - 1,
 107                         .skip           = '(',
 108                         .term           = ')',
 109                         .ftptype        = IP_CT_FTP_EPSV,
 110                         .getnum         = try_epsv_response,
 111                 },
 112         },
 113 };
 114
 115 static int
 116 get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
 117 {
 118         const char *end;
 119         int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
 120         if (ret > 0)
 121                 return (int)(end - src);
 122         return 0;
 123 }
 124
 125 static int try_number(const char *data, size_t dlen, u_int32_t array[],
 126                       int array_size, char sep, char term)
 127 {
 128         u_int32_t i, len;
 129
 130         memset(array, 0, sizeof(array[0])*array_size);
 131
 132         /* Keep data pointing at next char. */
 133         for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
 134                 if (*data >= '0' && *data <= '9') {
 135                         array[i] = array[i]*10 + *data - '0';
 136                 }
 137                 else if (*data == sep)
 138                         i++;
 139                 else {
 140                         /* Unexpected character; true if it's the
 141                            terminator and we're finished. */
 142                         if (*data == term && i == array_size - 1)
 143                                 return len;
 144
 145                         DEBUGP("Char %u (got %u nums) `%u' unexpected\n",
 146                                len, i, *data);
 147                         return 0;
 148                 }
 149         }
 150         DEBUGP("Failed to fill %u numbers separated by %c\n", array_size, sep);
 151
 152         return 0;
 153 }
 154
 155 /* Returns 0, or length of numbers: 192,168,1,1,5,6 */
 156 static int try_rfc959(const char *data, size_t dlen,
 157                       struct nf_conntrack_man *cmd, char term)
 158 {
 159         int length;
 160         u_int32_t array[6];
 161
 162         length = try_number(data, dlen, array, 6, ',', term);
 163         if (length == 0)
 164                 return 0;
 165
 166         cmd->u3.ip =  htonl((array[0] << 24) | (array[1] << 16) |
 167                                     (array[2] << 8) | array[3]);
 168         cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
 169         return length;
 170 }
 171
 172 /* Grab port: number up to delimiter */
 173 static int get_port(const char *data, int start, size_t dlen, char delim,
 174                     u_int16_t *port)
 175 {
 176         u_int16_t tmp_port = 0;
 177         int i;
 178
 179         for (i = start; i < dlen; i++) {
 180                 /* Finished? */
 181                 if (data[i] == delim) {
 182                         if (tmp_port == 0)
 183                                 break;
 184                         *port = htons(tmp_port);
 185                         DEBUGP("get_port: return %d\n", tmp_port);
 186                         return i + 1;
 187                 }
 188                 else if (data[i] >= '0' && data[i] <= '9')
 189                         tmp_port = tmp_port*10 + data[i] - '0';
 190                 else { /* Some other crap */
 191                         DEBUGP("get_port: invalid char.\n");
 192                         break;
 193                 }
 194         }
 195         return 0;
 196 }
 197
 198 /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
 199 static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
 200                     char term)
 201 {
 202         char delim;
 203         int length;
 204
 205         /* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
 206            then delimiter again. */
 207         if (dlen <= 3) {
 208                 DEBUGP("EPRT: too short\n");
 209                 return 0;
 210         }
 211         delim = data[0];
 212         if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
 213                 DEBUGP("try_eprt: invalid delimitter.\n");
 214                 return 0;
 215         }
 216
 217         if ((cmd->l3num == PF_INET && data[1] != '1') ||
 218             (cmd->l3num == PF_INET6 && data[1] != '2')) {
 219                 DEBUGP("EPRT: invalid protocol number.\n");
 220                 return 0;
 221         }
 222
 223         DEBUGP("EPRT: Got %c%c%c\n", delim, data[1], delim);
 224
 225         if (data[1] == '1') {
 226                 u_int32_t array[4];
 227
 228                 /* Now we have IP address. */
 229                 length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
 230                 if (length != 0)
 231                         cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
 232                                            | (array[2] << 8) | array[3]);
 233         } else {
 234                 /* Now we have IPv6 address. */
 235                 length = get_ipv6_addr(data + 3, dlen - 3,
 236                                        (struct in6_addr *)cmd->u3.ip6, delim);
 237         }
 238
 239         if (length == 0)
 240                 return 0;
 241         DEBUGP("EPRT: Got IP address!\n");
 242         /* Start offset includes initial "|1|", and trailing delimiter */
 243         return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
 244 }
 245
 246 /* Returns 0, or length of numbers: |||6446| */
 247 static int try_epsv_response(const char *data, size_t dlen,
 248                              struct nf_conntrack_man *cmd, char term)
 249 {
 250         char delim;
 251
 252         /* Three delimiters. */
 253         if (dlen <= 3) return 0;
 254         delim = data[0];
 255         if (isdigit(delim) || delim < 33 || delim > 126
 256             || data[1] != delim || data[2] != delim)
 257                 return 0;
 258
 259         return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
 260 }
 261
 262 /* Return 1 for match, 0 for accept, -1 for partial. */
 263 static int find_pattern(const char *data, size_t dlen,
 264                         const char *pattern, size_t plen,
 265                         char skip, char term,
 266                         unsigned int *numoff,
 267                         unsigned int *numlen,
 268                         struct nf_conntrack_man *cmd,
 269                         int (*getnum)(const char *, size_t,
 270                                       struct nf_conntrack_man *, char))
 271 {
 272         size_t i;
 273
 274         DEBUGP("find_pattern `%s': dlen = %u\n", pattern, dlen);
 275         if (dlen == 0)
 276                 return 0;
 277
 278         if (dlen <= plen) {
 279                 /* Short packet: try for partial? */
 280                 if (strnicmp(data, pattern, dlen) == 0)
 281                         return -1;
 282                 else return 0;
 283         }
 284
 285         if (strnicmp(data, pattern, plen) != 0) {
 286 #if 0
 287                 size_t i;
 288
 289                 DEBUGP("ftp: string mismatch\n");
 290                 for (i = 0; i < plen; i++) {
 291                         DEBUGP("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
 292                                 i, data[i], data[i],
 293                                 pattern[i], pattern[i]);
 294                 }
 295 #endif
 296                 return 0;
 297         }
 298
 299         DEBUGP("Pattern matches!\n");
 300         /* Now we've found the constant string, try to skip
 301            to the 'skip' character */
 302         for (i = plen; data[i] != skip; i++)
 303                 if (i == dlen - 1) return -1;
 304
 305         /* Skip over the last character */
 306         i++;
 307
 308         DEBUGP("Skipped up to `%c'!\n", skip);
 309
 310         *numoff = i;
 311         *numlen = getnum(data + i, dlen - i, cmd, term);
 312         if (!*numlen)
 313                 return -1;
 314
 315         DEBUGP("Match succeeded!\n");
 316         return 1;
 317 }
 318
 319 /* Look up to see if we're just after a \n. */
 320 static int find_nl_seq(u32 seq, const struct ip_ct_ftp_master *info, int dir)
 321 {
 322         unsigned int i;
 323
 324         for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
 325                 if (info->seq_aft_nl[dir][i] == seq)
 326                         return 1;
 327         return 0;
 328 }
 329
 330 /* We don't update if it's older than what we have. */
 331 static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir,
 332                           struct sk_buff *skb)
 333 {
 334         unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
 335
 336         /* Look for oldest: if we find exact match, we're done. */
 337         for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
 338                 if (info->seq_aft_nl[dir][i] == nl_seq)
 339                         return;
 340
 341                 if (oldest == info->seq_aft_nl_num[dir]
 342                     || before(info->seq_aft_nl[dir][i], oldest))
 343                         oldest = i;
 344         }
 345
 346         if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
 347                 info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
 348                 nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
 349         } else if (oldest != NUM_SEQ_TO_REMEMBER) {
 350                 info->seq_aft_nl[dir][oldest] = nl_seq;
 351                 nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
 352         }
 353 }
 354
 355 static int help(struct sk_buff **pskb,
 356                 unsigned int protoff,
 357                 struct nf_conn *ct,
 358                 enum ip_conntrack_info ctinfo)
 359 {
 360         unsigned int dataoff, datalen;
 361         struct tcphdr _tcph, *th;
 362         char *fb_ptr;
 363         int ret;
 364         u32 seq;
 365         int dir = CTINFO2DIR(ctinfo);
 366         unsigned int matchlen, matchoff;
 367         struct ip_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
 368         struct nf_conntrack_expect *exp;
 369         struct nf_conntrack_man cmd = {};
 370
 371         unsigned int i;
 372         int found = 0, ends_in_nl;
 373
 374         /* Until there's been traffic both ways, don't look in packets. */
 375         if (ctinfo != IP_CT_ESTABLISHED
 376             && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
 377                 DEBUGP("ftp: Conntrackinfo = %u\n", ctinfo);
 378                 return NF_ACCEPT;
 379         }
 380
 381         th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
 382         if (th == NULL)
 383                 return NF_ACCEPT;
 384
 385         dataoff = protoff + th->doff * 4;
 386         /* No data? */
 387         if (dataoff >= (*pskb)->len) {
 388                 DEBUGP("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
 389                         (*pskb)->len);
 390                 return NF_ACCEPT;
 391         }
 392         datalen = (*pskb)->len - dataoff;
 393
 394         spin_lock_bh(&nf_ftp_lock);
 395         fb_ptr = skb_header_pointer(*pskb, dataoff, datalen, ftp_buffer);
 396         BUG_ON(fb_ptr == NULL);
 397
 398         ends_in_nl = (fb_ptr[datalen - 1] == '\n');
 399         seq = ntohl(th->seq) + datalen;
 400
 401         /* Look up to see if we're just after a \n. */
 402         if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
 403                 /* Now if this ends in \n, update ftp info. */
 404                 DEBUGP("nf_conntrack_ftp_help: wrong seq pos %s(%u) or %s(%u)\n",
 405                        ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
 406                        ct_ftp_info->seq_aft_nl[dir][0],
 407                        ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
 408                        ct_ftp_info->seq_aft_nl[dir][1]);
 409                 ret = NF_ACCEPT;
 410                 goto out_update_nl;
 411         }
 412
 413         /* Initialize IP/IPv6 addr to expected address (it's not mentioned
 414            in EPSV responses) */
 415         cmd.l3num = ct->tuplehash[dir].tuple.src.l3num;
 416         memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 417                sizeof(cmd.u3.all));
 418
 419         for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
 420                 found = find_pattern(fb_ptr, datalen,
 421                                      search[dir][i].pattern,
 422                                      search[dir][i].plen,
 423                                      search[dir][i].skip,
 424                                      search[dir][i].term,
 425                                      &matchoff, &matchlen,
 426                                      &cmd,
 427                                      search[dir][i].getnum);
 428                 if (found) break;
 429         }
 430         if (found == -1) {
 431                 /* We don't usually drop packets.  After all, this is
 432                    connection tracking, not packet filtering.
 433                    However, it is necessary for accurate tracking in
 434                    this case. */
 435                 if (net_ratelimit())
 436                         printk("conntrack_ftp: partial %s %u+%u\n",
 437                                search[dir][i].pattern,
 438                                ntohl(th->seq), datalen);
 439                 ret = NF_DROP;
 440                 goto out;
 441         } else if (found == 0) { /* No match */
 442                 ret = NF_ACCEPT;
 443                 goto out_update_nl;
 444         }
 445
 446         DEBUGP("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
 447                (int)matchlen, fb_ptr + matchoff,
 448                matchlen, ntohl(th->seq) + matchoff);
 449
 450         exp = nf_conntrack_expect_alloc(ct);
 451         if (exp == NULL) {
 452                 ret = NF_DROP;
 453                 goto out;
 454         }
 455
 456         /* We refer to the reverse direction ("!dir") tuples here,
 457          * because we're expecting something in the other direction.
 458          * Doesn't matter unless NAT is happening.  */
 459         exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3;
 460
 461         /* Update the ftp info */
 462         if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) &&
 463             memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 464                      sizeof(cmd.u3.all))) {
 465                 /* Enrico Scholz's passive FTP to partially RNAT'd ftp
 466                    server: it really wants us to connect to a
 467                    different IP address.  Simply don't record it for
 468                    NAT. */
 469                 if (cmd.l3num == PF_INET) {
 470                         DEBUGP("conntrack_ftp: NOT RECORDING: " NIPQUAD_FMT " != " NIPQUAD_FMT "\n",
 471                                NIPQUAD(cmd.u3.ip),
 472                                NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip));
 473                 } else {
 474                         DEBUGP("conntrack_ftp: NOT RECORDING: " NIP6_FMT " != " NIP6_FMT "\n",
 475                                NIP6(*((struct in6_addr *)cmd.u3.ip6)),
 476                                NIP6(*((struct in6_addr *)ct->tuplehash[dir]
 477                                                         .tuple.src.u3.ip6)));
 478                 }
 479
 480                 /* Thanks to Cristiano Lincoln Mattos
 481                    <lincoln@cesar.org.br> for reporting this potential
 482                    problem (DMZ machines opening holes to internal
 483                    networks, or the packet filter itself). */
 484                 if (!loose) {
 485                         ret = NF_ACCEPT;
 486                         goto out_put_expect;
 487                 }
 488                 memcpy(&exp->tuple.dst.u3, &cmd.u3.all,
 489                        sizeof(exp->tuple.dst.u3));
 490         }
 491
 492         exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3;
 493         exp->tuple.src.l3num = cmd.l3num;
 494         exp->tuple.src.u.tcp.port = 0;
 495         exp->tuple.dst.u.tcp.port = cmd.u.tcp.port;
 496         exp->tuple.dst.protonum = IPPROTO_TCP;
 497
 498         exp->mask = (struct nf_conntrack_tuple)
 499                     { .src = { .l3num = 0xFFFF,
 500                                .u = { .tcp = { 0 }},
 501                              },
 502                       .dst = { .protonum = 0xFF,
 503                                .u = { .tcp = { 0xFFFF }},
 504                              },
 505                     };
 506         if (cmd.l3num == PF_INET) {
 507                 exp->mask.src.u3.ip = 0xFFFFFFFF;
 508                 exp->mask.dst.u3.ip = 0xFFFFFFFF;
 509         } else {
 510                 memset(exp->mask.src.u3.ip6, 0xFF,
 511                        sizeof(exp->mask.src.u3.ip6));
 512                 memset(exp->mask.dst.u3.ip6, 0xFF,
 513                        sizeof(exp->mask.src.u3.ip6));
 514         }
 515
 516         exp->expectfn = NULL;
 517         exp->flags = 0;
 518
 519         /* Now, NAT might want to mangle the packet, and register the
 520          * (possibly changed) expectation itself. */
 521         if (nf_nat_ftp_hook)
 522                 ret = nf_nat_ftp_hook(pskb, ctinfo, search[dir][i].ftptype,
 523                                       matchoff, matchlen, exp, &seq);
 524         else {
 525                 /* Can't expect this?  Best to drop packet now. */
 526                 if (nf_conntrack_expect_related(exp) != 0)
 527                         ret = NF_DROP;
 528                 else
 529                         ret = NF_ACCEPT;
 530         }
 531
 532 out_put_expect:
 533         nf_conntrack_expect_put(exp);
 534
 535 out_update_nl:
 536         /* Now if this ends in \n, update ftp info.  Seq may have been
 537          * adjusted by NAT code. */
 538         if (ends_in_nl)
 539                 update_nl_seq(seq, ct_ftp_info, dir, *pskb);
 540  out:
 541         spin_unlock_bh(&nf_ftp_lock);
 542         return ret;
 543 }
 544
 545 static struct nf_conntrack_helper ftp[MAX_PORTS][2];
 546 static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")];
 547
 548 /* don't make this __exit, since it's called from __init ! */
 549 static void nf_conntrack_ftp_fini(void)
 550 {
 551         int i, j;
 552         for (i = 0; i < ports_c; i++) {
 553                 for (j = 0; j < 2; j++) {
 554                         if (ftp[i][j].me == NULL)
 555                                 continue;
 556
 557                         DEBUGP("nf_ct_ftp: unregistering helper for pf: %d "
 558                                "port: %d\n",
 559                                 ftp[i][j].tuple.src.l3num, ports[i]);
 560                         nf_conntrack_helper_unregister(&ftp[i][j]);
 561                 }
 562         }
 563
 564         kfree(ftp_buffer);
 565 }
 566
 567 static int __init nf_conntrack_ftp_init(void)
 568 {
 569         int i, j = -1, ret = 0;
 570         char *tmpname;
 571
 572         ftp_buffer = kmalloc(65536, GFP_KERNEL);
 573         if (!ftp_buffer)
 574                 return -ENOMEM;
 575
 576         if (ports_c == 0)
 577                 ports[ports_c++] = FTP_PORT;
 578
 579         /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
 580                  are tracked or not - YK */
 581         for (i = 0; i < ports_c; i++) {
 582                 ftp[i][0].tuple.src.l3num = PF_INET;
 583                 ftp[i][1].tuple.src.l3num = PF_INET6;
 584                 for (j = 0; j < 2; j++) {
 585                         ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
 586                         ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
 587                         ftp[i][j].mask.src.u.tcp.port = 0xFFFF;
 588                         ftp[i][j].mask.dst.protonum = 0xFF;
 589                         ftp[i][j].max_expected = 1;
 590                         ftp[i][j].timeout = 5 * 60;     /* 5 Minutes */
 591                         ftp[i][j].me = THIS_MODULE;
 592                         ftp[i][j].help = help;
 593                         tmpname = &ftp_names[i][j][0];
 594                         if (ports[i] == FTP_PORT)
 595                                 sprintf(tmpname, "ftp");
 596                         else
 597                                 sprintf(tmpname, "ftp-%d", ports[i]);
 598                         ftp[i][j].name = tmpname;
 599
 600                         DEBUGP("nf_ct_ftp: registering helper for pf: %d "
 601                                "port: %d\n",
 602                                 ftp[i][j].tuple.src.l3num, ports[i]);
 603                         ret = nf_conntrack_helper_register(&ftp[i][j]);
 604                         if (ret) {
 605                                 printk("nf_ct_ftp: failed to register helper "
 606                                        " for pf: %d port: %d\n",
 607                                         ftp[i][j].tuple.src.l3num, ports[i]);
 608                                 nf_conntrack_ftp_fini();
 609                                 return ret;
 610                         }
 611                 }
 612         }
 613
 614         return 0;
 615 }
 616
 617 module_init(nf_conntrack_ftp_init);
 618 module_exit(nf_conntrack_ftp_fini);