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Linux/net/netfilter/nf_conntrack_ftp.c

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  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 >= '' && *data <= '9') {
131                         array[i] = array[i]*10 + *data - '';
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] >= '' && data[i] <= '9')
214                         tmp_port = tmp_port*10 + data[i] - '';
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 (strncasecmp(data, pattern, dlen) == 0)
308                         return -1;
309                 else return 0;
310         }
311 
312         if (strncasecmp(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);
647 

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