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/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;
  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 /* This code is based on inet_pton() in glibc-2.2.4 */
 116 static int
 117 get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
 118 {
 119         static const char xdigits[] = "0123456789abcdef";
 120         u_int8_t tmp[16], *tp, *endp, *colonp;
 121         int ch, saw_xdigit;
 122         u_int32_t val;
 123         size_t clen = 0;
 124
 125         tp = memset(tmp, '\0', sizeof(tmp));
 126         endp = tp + sizeof(tmp);
 127         colonp = NULL;
 128
 129         /* Leading :: requires some special handling. */
 130         if (*src == ':'){
 131                 if (*++src != ':') {
 132                         DEBUGP("invalid \":\" at the head of addr\n");
 133                         return 0;
 134                 }
 135                 clen++;
 136         }
 137
 138         saw_xdigit = 0;
 139         val = 0;
 140         while ((clen < dlen) && (*src != term)) {
 141                 const char *pch;
 142
 143                 ch = tolower(*src++);
 144                 clen++;
 145
 146                 pch = strchr(xdigits, ch);
 147                 if (pch != NULL) {
 148                         val <<= 4;
 149                         val |= (pch - xdigits);
 150                         if (val > 0xffff)
 151                                 return 0;
 152
 153                         saw_xdigit = 1;
 154                         continue;
 155                 }
 156                 if (ch != ':') {
 157                         DEBUGP("get_ipv6_addr: invalid char. \'%c\'\n", ch);
 158                         return 0;
 159                 }
 160
 161                 if (!saw_xdigit) {
 162                         if (colonp) {
 163                                 DEBUGP("invalid location of \"::\".\n");
 164                                 return 0;
 165                         }
 166                         colonp = tp;
 167                         continue;
 168                 } else if (*src == term) {
 169                         DEBUGP("trancated IPv6 addr\n");
 170                         return 0;
 171                 }
 172
 173                 if (tp + 2 > endp)
 174                         return 0;
 175                 *tp++ = (u_int8_t) (val >> 8) & 0xff;
 176                 *tp++ = (u_int8_t) val & 0xff;
 177
 178                 saw_xdigit = 0;
 179                 val = 0;
 180                 continue;
 181         }
 182         if (saw_xdigit) {
 183                 if (tp + 2 > endp)
 184                         return 0;
 185                 *tp++ = (u_int8_t) (val >> 8) & 0xff;
 186                 *tp++ = (u_int8_t) val & 0xff;
 187         }
 188         if (colonp != NULL) {
 189                 /*
 190                  * Since some memmove()'s erroneously fail to handle
 191                  * overlapping regions, we'll do the shift by hand.
 192                  */
 193                 const int n = tp - colonp;
 194                 int i;
 195
 196                 if (tp == endp)
 197                         return 0;
 198
 199                 for (i = 1; i <= n; i++) {
 200                         endp[- i] = colonp[n - i];
 201                         colonp[n - i] = 0;
 202                 }
 203                 tp = endp;
 204         }
 205         if (tp != endp || (*src != term))
 206                 return 0;
 207
 208         memcpy(dst->s6_addr, tmp, sizeof(dst->s6_addr));
 209         return clen;
 210 }
 211
 212 static int try_number(const char *data, size_t dlen, u_int32_t array[],
 213                       int array_size, char sep, char term)
 214 {
 215         u_int32_t i, len;
 216
 217         memset(array, 0, sizeof(array[0])*array_size);
 218
 219         /* Keep data pointing at next char. */
 220         for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
 221                 if (*data >= '0' && *data <= '9') {
 222                         array[i] = array[i]*10 + *data - '0';
 223                 }
 224                 else if (*data == sep)
 225                         i++;
 226                 else {
 227                         /* Unexpected character; true if it's the
 228                            terminator and we're finished. */
 229                         if (*data == term && i == array_size - 1)
 230                                 return len;
 231
 232                         DEBUGP("Char %u (got %u nums) `%u' unexpected\n",
 233                                len, i, *data);
 234                         return 0;
 235                 }
 236         }
 237         DEBUGP("Failed to fill %u numbers separated by %c\n", array_size, sep);
 238
 239         return 0;
 240 }
 241
 242 /* Returns 0, or length of numbers: 192,168,1,1,5,6 */
 243 static int try_rfc959(const char *data, size_t dlen,
 244                       struct nf_conntrack_man *cmd, char term)
 245 {
 246         int length;
 247         u_int32_t array[6];
 248
 249         length = try_number(data, dlen, array, 6, ',', term);
 250         if (length == 0)
 251                 return 0;
 252
 253         cmd->u3.ip =  htonl((array[0] << 24) | (array[1] << 16) |
 254                                     (array[2] << 8) | array[3]);
 255         cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
 256         return length;
 257 }
 258
 259 /* Grab port: number up to delimiter */
 260 static int get_port(const char *data, int start, size_t dlen, char delim,
 261                     u_int16_t *port)
 262 {
 263         u_int16_t tmp_port = 0;
 264         int i;
 265
 266         for (i = start; i < dlen; i++) {
 267                 /* Finished? */
 268                 if (data[i] == delim) {
 269                         if (tmp_port == 0)
 270                                 break;
 271                         *port = htons(tmp_port);
 272                         DEBUGP("get_port: return %d\n", tmp_port);
 273                         return i + 1;
 274                 }
 275                 else if (data[i] >= '0' && data[i] <= '9')
 276                         tmp_port = tmp_port*10 + data[i] - '0';
 277                 else { /* Some other crap */
 278                         DEBUGP("get_port: invalid char.\n");
 279                         break;
 280                 }
 281         }
 282         return 0;
 283 }
 284
 285 /* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
 286 static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
 287                     char term)
 288 {
 289         char delim;
 290         int length;
 291
 292         /* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
 293            then delimiter again. */
 294         if (dlen <= 3) {
 295                 DEBUGP("EPRT: too short\n");
 296                 return 0;
 297         }
 298         delim = data[0];
 299         if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
 300                 DEBUGP("try_eprt: invalid delimitter.\n");
 301                 return 0;
 302         }
 303
 304         if ((cmd->l3num == PF_INET && data[1] != '1') ||
 305             (cmd->l3num == PF_INET6 && data[1] != '2')) {
 306                 DEBUGP("EPRT: invalid protocol number.\n");
 307                 return 0;
 308         }
 309
 310         DEBUGP("EPRT: Got %c%c%c\n", delim, data[1], delim);
 311
 312         if (data[1] == '1') {
 313                 u_int32_t array[4];
 314
 315                 /* Now we have IP address. */
 316                 length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
 317                 if (length != 0)
 318                         cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
 319                                            | (array[2] << 8) | array[3]);
 320         } else {
 321                 /* Now we have IPv6 address. */
 322                 length = get_ipv6_addr(data + 3, dlen - 3,
 323                                        (struct in6_addr *)cmd->u3.ip6, delim);
 324         }
 325
 326         if (length == 0)
 327                 return 0;
 328         DEBUGP("EPRT: Got IP address!\n");
 329         /* Start offset includes initial "|1|", and trailing delimiter */
 330         return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
 331 }
 332
 333 /* Returns 0, or length of numbers: |||6446| */
 334 static int try_epsv_response(const char *data, size_t dlen,
 335                              struct nf_conntrack_man *cmd, char term)
 336 {
 337         char delim;
 338
 339         /* Three delimiters. */
 340         if (dlen <= 3) return 0;
 341         delim = data[0];
 342         if (isdigit(delim) || delim < 33 || delim > 126
 343             || data[1] != delim || data[2] != delim)
 344                 return 0;
 345
 346         return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
 347 }
 348
 349 /* Return 1 for match, 0 for accept, -1 for partial. */
 350 static int find_pattern(const char *data, size_t dlen,
 351                         const char *pattern, size_t plen,
 352                         char skip, char term,
 353                         unsigned int *numoff,
 354                         unsigned int *numlen,
 355                         struct nf_conntrack_man *cmd,
 356                         int (*getnum)(const char *, size_t,
 357                                       struct nf_conntrack_man *, char))
 358 {
 359         size_t i;
 360
 361         DEBUGP("find_pattern `%s': dlen = %u\n", pattern, dlen);
 362         if (dlen == 0)
 363                 return 0;
 364
 365         if (dlen <= plen) {
 366                 /* Short packet: try for partial? */
 367                 if (strnicmp(data, pattern, dlen) == 0)
 368                         return -1;
 369                 else return 0;
 370         }
 371
 372         if (strnicmp(data, pattern, plen) != 0) {
 373 #if 0
 374                 size_t i;
 375
 376                 DEBUGP("ftp: string mismatch\n");
 377                 for (i = 0; i < plen; i++) {
 378                         DEBUGP("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
 379                                 i, data[i], data[i],
 380                                 pattern[i], pattern[i]);
 381                 }
 382 #endif
 383                 return 0;
 384         }
 385
 386         DEBUGP("Pattern matches!\n");
 387         /* Now we've found the constant string, try to skip
 388            to the 'skip' character */
 389         for (i = plen; data[i] != skip; i++)
 390                 if (i == dlen - 1) return -1;
 391
 392         /* Skip over the last character */
 393         i++;
 394
 395         DEBUGP("Skipped up to `%c'!\n", skip);
 396
 397         *numoff = i;
 398         *numlen = getnum(data + i, dlen - i, cmd, term);
 399         if (!*numlen)
 400                 return -1;
 401
 402         DEBUGP("Match succeeded!\n");
 403         return 1;
 404 }
 405
 406 /* Look up to see if we're just after a \n. */
 407 static int find_nl_seq(u32 seq, const struct ip_ct_ftp_master *info, int dir)
 408 {
 409         unsigned int i;
 410
 411         for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
 412                 if (info->seq_aft_nl[dir][i] == seq)
 413                         return 1;
 414         return 0;
 415 }
 416
 417 /* We don't update if it's older than what we have. */
 418 static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir,
 419                           struct sk_buff *skb)
 420 {
 421         unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
 422
 423         /* Look for oldest: if we find exact match, we're done. */
 424         for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
 425                 if (info->seq_aft_nl[dir][i] == nl_seq)
 426                         return;
 427
 428                 if (oldest == info->seq_aft_nl_num[dir]
 429                     || before(info->seq_aft_nl[dir][i], oldest))
 430                         oldest = i;
 431         }
 432
 433         if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
 434                 info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
 435                 nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
 436         } else if (oldest != NUM_SEQ_TO_REMEMBER) {
 437                 info->seq_aft_nl[dir][oldest] = nl_seq;
 438                 nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
 439         }
 440 }
 441
 442 static int help(struct sk_buff **pskb,
 443                 unsigned int protoff,
 444                 struct nf_conn *ct,
 445                 enum ip_conntrack_info ctinfo)
 446 {
 447         unsigned int dataoff, datalen;
 448         struct tcphdr _tcph, *th;
 449         char *fb_ptr;
 450         int ret;
 451         u32 seq;
 452         int dir = CTINFO2DIR(ctinfo);
 453         unsigned int matchlen, matchoff;
 454         struct ip_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
 455         struct nf_conntrack_expect *exp;
 456         struct nf_conntrack_man cmd = {};
 457
 458         unsigned int i;
 459         int found = 0, ends_in_nl;
 460
 461         /* Until there's been traffic both ways, don't look in packets. */
 462         if (ctinfo != IP_CT_ESTABLISHED
 463             && ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
 464                 DEBUGP("ftp: Conntrackinfo = %u\n", ctinfo);
 465                 return NF_ACCEPT;
 466         }
 467
 468         th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
 469         if (th == NULL)
 470                 return NF_ACCEPT;
 471
 472         dataoff = protoff + th->doff * 4;
 473         /* No data? */
 474         if (dataoff >= (*pskb)->len) {
 475                 DEBUGP("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
 476                         (*pskb)->len);
 477                 return NF_ACCEPT;
 478         }
 479         datalen = (*pskb)->len - dataoff;
 480
 481         spin_lock_bh(&nf_ftp_lock);
 482         fb_ptr = skb_header_pointer(*pskb, dataoff, datalen, ftp_buffer);
 483         BUG_ON(fb_ptr == NULL);
 484
 485         ends_in_nl = (fb_ptr[datalen - 1] == '\n');
 486         seq = ntohl(th->seq) + datalen;
 487
 488         /* Look up to see if we're just after a \n. */
 489         if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
 490                 /* Now if this ends in \n, update ftp info. */
 491                 DEBUGP("nf_conntrack_ftp_help: wrong seq pos %s(%u) or %s(%u)\n",
 492                        ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
 493                        ct_ftp_info->seq_aft_nl[dir][0],
 494                        ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
 495                        ct_ftp_info->seq_aft_nl[dir][1]);
 496                 ret = NF_ACCEPT;
 497                 goto out_update_nl;
 498         }
 499
 500         /* Initialize IP/IPv6 addr to expected address (it's not mentioned
 501            in EPSV responses) */
 502         cmd.l3num = ct->tuplehash[dir].tuple.src.l3num;
 503         memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 504                sizeof(cmd.u3.all));
 505
 506         for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
 507                 found = find_pattern(fb_ptr, datalen,
 508                                      search[dir][i].pattern,
 509                                      search[dir][i].plen,
 510                                      search[dir][i].skip,
 511                                      search[dir][i].term,
 512                                      &matchoff, &matchlen,
 513                                      &cmd,
 514                                      search[dir][i].getnum);
 515                 if (found) break;
 516         }
 517         if (found == -1) {
 518                 /* We don't usually drop packets.  After all, this is
 519                    connection tracking, not packet filtering.
 520                    However, it is necessary for accurate tracking in
 521                    this case. */
 522                 if (net_ratelimit())
 523                         printk("conntrack_ftp: partial %s %u+%u\n",
 524                                search[dir][i].pattern,
 525                                ntohl(th->seq), datalen);
 526                 ret = NF_DROP;
 527                 goto out;
 528         } else if (found == 0) { /* No match */
 529                 ret = NF_ACCEPT;
 530                 goto out_update_nl;
 531         }
 532
 533         DEBUGP("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
 534                (int)matchlen, fb_ptr + matchoff,
 535                matchlen, ntohl(th->seq) + matchoff);
 536
 537         exp = nf_conntrack_expect_alloc(ct);
 538         if (exp == NULL) {
 539                 ret = NF_DROP;
 540                 goto out;
 541         }
 542
 543         /* We refer to the reverse direction ("!dir") tuples here,
 544          * because we're expecting something in the other direction.
 545          * Doesn't matter unless NAT is happening.  */
 546         exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3;
 547
 548         /* Update the ftp info */
 549         if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) &&
 550             memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
 551                      sizeof(cmd.u3.all))) {
 552                 /* Enrico Scholz's passive FTP to partially RNAT'd ftp
 553                    server: it really wants us to connect to a
 554                    different IP address.  Simply don't record it for
 555                    NAT. */
 556                 if (cmd.l3num == PF_INET) {
 557                         DEBUGP("conntrack_ftp: NOT RECORDING: " NIPQUAD_FMT " != " NIPQUAD_FMT "\n",
 558                                NIPQUAD(cmd.u3.ip),
 559                                NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip));
 560                 } else {
 561                         DEBUGP("conntrack_ftp: NOT RECORDING: " NIP6_FMT " != " NIP6_FMT "\n",
 562                                NIP6(*((struct in6_addr *)cmd.u3.ip6)),
 563                                NIP6(*((struct in6_addr *)ct->tuplehash[dir]
 564                                                         .tuple.src.u3.ip6)));
 565                 }
 566
 567                 /* Thanks to Cristiano Lincoln Mattos
 568                    <lincoln@cesar.org.br> for reporting this potential
 569                    problem (DMZ machines opening holes to internal
 570                    networks, or the packet filter itself). */
 571                 if (!loose) {
 572                         ret = NF_ACCEPT;
 573                         goto out_put_expect;
 574                 }
 575                 memcpy(&exp->tuple.dst.u3, &cmd.u3.all,
 576                        sizeof(exp->tuple.dst.u3));
 577         }
 578
 579         exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3;
 580         exp->tuple.src.l3num = cmd.l3num;
 581         exp->tuple.src.u.tcp.port = 0;
 582         exp->tuple.dst.u.tcp.port = cmd.u.tcp.port;
 583         exp->tuple.dst.protonum = IPPROTO_TCP;
 584
 585         exp->mask = (struct nf_conntrack_tuple)
 586                     { .src = { .l3num = 0xFFFF,
 587                                .u = { .tcp = { 0 }},
 588                              },
 589                       .dst = { .protonum = 0xFF,
 590                                .u = { .tcp = { 0xFFFF }},
 591                              },
 592                     };
 593         if (cmd.l3num == PF_INET) {
 594                 exp->mask.src.u3.ip = 0xFFFFFFFF;
 595                 exp->mask.dst.u3.ip = 0xFFFFFFFF;
 596         } else {
 597                 memset(exp->mask.src.u3.ip6, 0xFF,
 598                        sizeof(exp->mask.src.u3.ip6));
 599                 memset(exp->mask.dst.u3.ip6, 0xFF,
 600                        sizeof(exp->mask.src.u3.ip6));
 601         }
 602
 603         exp->expectfn = NULL;
 604         exp->flags = 0;
 605
 606         /* Now, NAT might want to mangle the packet, and register the
 607          * (possibly changed) expectation itself. */
 608         if (nf_nat_ftp_hook)
 609                 ret = nf_nat_ftp_hook(pskb, ctinfo, search[dir][i].ftptype,
 610                                       matchoff, matchlen, exp, &seq);
 611         else {
 612                 /* Can't expect this?  Best to drop packet now. */
 613                 if (nf_conntrack_expect_related(exp) != 0)
 614                         ret = NF_DROP;
 615                 else
 616                         ret = NF_ACCEPT;
 617         }
 618
 619 out_put_expect:
 620         nf_conntrack_expect_put(exp);
 621
 622 out_update_nl:
 623         /* Now if this ends in \n, update ftp info.  Seq may have been
 624          * adjusted by NAT code. */
 625         if (ends_in_nl)
 626                 update_nl_seq(seq, ct_ftp_info, dir, *pskb);
 627  out:
 628         spin_unlock_bh(&nf_ftp_lock);
 629         return ret;
 630 }
 631
 632 static struct nf_conntrack_helper ftp[MAX_PORTS][2];
 633 static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")];
 634
 635 /* don't make this __exit, since it's called from __init ! */
 636 static void nf_conntrack_ftp_fini(void)
 637 {
 638         int i, j;
 639         for (i = 0; i < ports_c; i++) {
 640                 for (j = 0; j < 2; j++) {
 641                         if (ftp[i][j].me == NULL)
 642                                 continue;
 643
 644                         DEBUGP("nf_ct_ftp: unregistering helper for pf: %d "
 645                                "port: %d\n",
 646                                 ftp[i][j].tuple.src.l3num, ports[i]);
 647                         nf_conntrack_helper_unregister(&ftp[i][j]);
 648                 }
 649         }
 650
 651         kfree(ftp_buffer);
 652 }
 653
 654 static int __init nf_conntrack_ftp_init(void)
 655 {
 656         int i, j = -1, ret = 0;
 657         char *tmpname;
 658
 659         ftp_buffer = kmalloc(65536, GFP_KERNEL);
 660         if (!ftp_buffer)
 661                 return -ENOMEM;
 662
 663         if (ports_c == 0)
 664                 ports[ports_c++] = FTP_PORT;
 665
 666         /* FIXME should be configurable whether IPv4 and IPv6 FTP connections
 667                  are tracked or not - YK */
 668         for (i = 0; i < ports_c; i++) {
 669                 ftp[i][0].tuple.src.l3num = PF_INET;
 670                 ftp[i][1].tuple.src.l3num = PF_INET6;
 671                 for (j = 0; j < 2; j++) {
 672                         ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
 673                         ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
 674                         ftp[i][j].mask.src.u.tcp.port = 0xFFFF;
 675                         ftp[i][j].mask.dst.protonum = 0xFF;
 676                         ftp[i][j].max_expected = 1;
 677                         ftp[i][j].timeout = 5 * 60;     /* 5 Minutes */
 678                         ftp[i][j].me = THIS_MODULE;
 679                         ftp[i][j].help = help;
 680                         tmpname = &ftp_names[i][j][0];
 681                         if (ports[i] == FTP_PORT)
 682                                 sprintf(tmpname, "ftp");
 683                         else
 684                                 sprintf(tmpname, "ftp-%d", ports[i]);
 685                         ftp[i][j].name = tmpname;
 686
 687                         DEBUGP("nf_ct_ftp: registering helper for pf: %d "
 688                                "port: %d\n",
 689                                 ftp[i][j].tuple.src.l3num, ports[i]);
 690                         ret = nf_conntrack_helper_register(&ftp[i][j]);
 691                         if (ret) {
 692                                 printk("nf_ct_ftp: failed to register helper "
 693                                        " for pf: %d port: %d\n",
 694                                         ftp[i][j].tuple.src.l3num, ports[i]);
 695                                 nf_conntrack_ftp_fini();
 696                                 return ret;
 697                         }
 698                 }
 699         }
 700
 701         return 0;
 702 }
 703
 704 module_init(nf_conntrack_ftp_init);
 705 module_exit(nf_conntrack_ftp_fini);