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1 /*
2  *  net/dccp/options.c
3  *
4  *  An implementation of the DCCP protocol
5  *  Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
6  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
7  *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
8  *
9  *      This program is free software; you can redistribute it and/or
10  *      modify it under the terms of the GNU General Public License
11  *      as published by the Free Software Foundation; either version
12  *      2 of the License, or (at your option) any later version.
13  */
14 #include <linux/dccp.h>
15 #include <linux/module.h>
16 #include <linux/types.h>
17 #include <asm/unaligned.h>
18 #include <linux/kernel.h>
19 #include <linux/skbuff.h>
20
21 #include "ackvec.h"
22 #include "ccid.h"
23 #include "dccp.h"
24 #include "feat.h"
25
26 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
27 {
28         u64 value = 0;
29
30         if (len >= DCCP_OPTVAL_MAXLEN)
31                 value += ((u64)*bf++) << 40;
32         if (len > 4)
33                 value += ((u64)*bf++) << 32;
34         if (len > 3)
35                 value += ((u64)*bf++) << 24;
36         if (len > 2)
37                 value += ((u64)*bf++) << 16;
38         if (len > 1)
39                 value += ((u64)*bf++) << 8;
40         if (len > 0)
41                 value += *bf;
42
43         return value;
44 }
45
46 /**
47  * dccp_parse_options  -  Parse DCCP options present in @skb
48  * @sk: client|server|listening dccp socket (when @dreq != NULL)
49  * @dreq: request socket to use during connection setup, or NULL
50  */
51 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
52                        struct sk_buff *skb)
53 {
54         struct dccp_sock *dp = dccp_sk(sk);
55         const struct dccp_hdr *dh = dccp_hdr(skb);
56         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
57         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
58         unsigned char *opt_ptr = options;
59         const unsigned char *opt_end = (unsigned char *)dh +
60                                         (dh->dccph_doff * 4);
61         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
62         unsigned char opt, len;
63         unsigned char *uninitialized_var(value);
64         u32 elapsed_time;
65         __be32 opt_val;
66         int rc;
67         int mandatory = 0;
68
69         memset(opt_recv, 0, sizeof(*opt_recv));
70
71         opt = len = 0;
72         while (opt_ptr != opt_end) {
73                 opt   = *opt_ptr++;
74                 len   = 0;
75                 value = NULL;
76
77                 /* Check if this isn't a single byte option */
78                 if (opt > DCCPO_MAX_RESERVED) {
79                         if (opt_ptr == opt_end)
80                                 goto out_nonsensical_length;
81
82                         len = *opt_ptr++;
83                         if (len < 2)
84                                 goto out_nonsensical_length;
85                         /*
86                          * Remove the type and len fields, leaving
87                          * just the value size
88                          */
89                         len     -= 2;
90                         value   = opt_ptr;
91                         opt_ptr += len;
92
93                         if (opt_ptr > opt_end)
94                                 goto out_nonsensical_length;
95                 }
96
97                 /*
98                  * CCID-specific options are ignored during connection setup, as
99                  * negotiation may still be in progress (see RFC 4340, 10.3).
100                  * The same applies to Ack Vectors, as these depend on the CCID.
101                  */
102                 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
103                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
104                         goto ignore_option;
105
106                 switch (opt) {
107                 case DCCPO_PADDING:
108                         break;
109                 case DCCPO_MANDATORY:
110                         if (mandatory)
111                                 goto out_invalid_option;
112                         if (pkt_type != DCCP_PKT_DATA)
113                                 mandatory = 1;
114                         break;
115                 case DCCPO_NDP_COUNT:
116                         if (len > 6)
117                                 goto out_invalid_option;
118
119                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
120                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
121                                       (unsigned long long)opt_recv->dccpor_ndp);
122                         break;
123                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
124                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
125                                 break;
126                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
127                                                     *value, value + 1, len - 1);
128                         if (rc)
129                                 goto out_featneg_failed;
130                         break;
131                 case DCCPO_ACK_VECTOR_0:
132                 case DCCPO_ACK_VECTOR_1:
133                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
134                                 break;
135                         dccp_pr_debug("%s Ack Vector (len=%u)\n", dccp_role(sk),
136                                       len);
137                         break;
138                 case DCCPO_TIMESTAMP:
139                         if (len != 4)
140                                 goto out_invalid_option;
141                         /*
142                          * RFC 4340 13.1: "The precise time corresponding to
143                          * Timestamp Value zero is not specified". We use
144                          * zero to indicate absence of a meaningful timestamp.
145                          */
146                         opt_val = get_unaligned((__be32 *)value);
147                         if (unlikely(opt_val == 0)) {
148                                 DCCP_WARN("Timestamp with zero value\n");
149                                 break;
150                         }
151
152                         if (dreq != NULL) {
153                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
154                                 dreq->dreq_timestamp_time = dccp_timestamp();
155                         } else {
156                                 opt_recv->dccpor_timestamp =
157                                         dp->dccps_timestamp_echo = ntohl(opt_val);
158                                 dp->dccps_timestamp_time = dccp_timestamp();
159                         }
160                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
161                                       dccp_role(sk), ntohl(opt_val),
162                                       (unsigned long long)
163                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
164                         /* schedule an Ack in case this sender is quiescent */
165                         inet_csk_schedule_ack(sk);
166                         break;
167                 case DCCPO_TIMESTAMP_ECHO:
168                         if (len != 4 && len != 6 && len != 8)
169                                 goto out_invalid_option;
170
171                         opt_val = get_unaligned((__be32 *)value);
172                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
173
174                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
175                                       "ackno=%llu", dccp_role(sk),
176                                       opt_recv->dccpor_timestamp_echo,
177                                       len + 2,
178                                       (unsigned long long)
179                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
180
181                         value += 4;
182
183                         if (len == 4) {         /* no elapsed time included */
184                                 dccp_pr_debug_cat("\n");
185                                 break;
186                         }
187
188                         if (len == 6) {         /* 2-byte elapsed time */
189                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
190                                 elapsed_time = ntohs(opt_val2);
191                         } else {                /* 4-byte elapsed time */
192                                 opt_val = get_unaligned((__be32 *)value);
193                                 elapsed_time = ntohl(opt_val);
194                         }
195
196                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
197
198                         /* Give precedence to the biggest ELAPSED_TIME */
199                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
200                                 opt_recv->dccpor_elapsed_time = elapsed_time;
201                         break;
202                 case DCCPO_ELAPSED_TIME:
203                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
204                                 break;
205
206                         if (len == 2) {
207                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
208                                 elapsed_time = ntohs(opt_val2);
209                         } else if (len == 4) {
210                                 opt_val = get_unaligned((__be32 *)value);
211                                 elapsed_time = ntohl(opt_val);
212                         } else {
213                                 goto out_invalid_option;
214                         }
215
216                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
217                                 opt_recv->dccpor_elapsed_time = elapsed_time;
218
219                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
220                                       dccp_role(sk), elapsed_time);
221                         break;
222                 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
223                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
224                                                      pkt_type, opt, value, len))
225                                 goto out_invalid_option;
226                         break;
227                 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
228                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
229                                                      pkt_type, opt, value, len))
230                                 goto out_invalid_option;
231                         break;
232                 default:
233                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
234                                   "implemented, ignoring", sk, opt, len);
235                         break;
236                 }
237 ignore_option:
238                 if (opt != DCCPO_MANDATORY)
239                         mandatory = 0;
240         }
241
242         /* mandatory was the last byte in option list -> reset connection */
243         if (mandatory)
244                 goto out_invalid_option;
245
246 out_nonsensical_length:
247         /* RFC 4340, 5.8: ignore option and all remaining option space */
248         return 0;
249
250 out_invalid_option:
251         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
252         rc = DCCP_RESET_CODE_OPTION_ERROR;
253 out_featneg_failed:
254         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
255         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
256         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
257         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
258         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
259         return -1;
260 }
261
262 EXPORT_SYMBOL_GPL(dccp_parse_options);
263
264 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
265 {
266         if (len >= DCCP_OPTVAL_MAXLEN)
267                 *to++ = (value & 0xFF0000000000ull) >> 40;
268         if (len > 4)
269                 *to++ = (value & 0xFF00000000ull) >> 32;
270         if (len > 3)
271                 *to++ = (value & 0xFF000000) >> 24;
272         if (len > 2)
273                 *to++ = (value & 0xFF0000) >> 16;
274         if (len > 1)
275                 *to++ = (value & 0xFF00) >> 8;
276         if (len > 0)
277                 *to++ = (value & 0xFF);
278 }
279
280 static inline u8 dccp_ndp_len(const u64 ndp)
281 {
282         if (likely(ndp <= 0xFF))
283                 return 1;
284         return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
285 }
286
287 int dccp_insert_option(struct sk_buff *skb, const unsigned char option,
288                        const void *value, const unsigned char len)
289 {
290         unsigned char *to;
291
292         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
293                 return -1;
294
295         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
296
297         to    = skb_push(skb, len + 2);
298         *to++ = option;
299         *to++ = len + 2;
300
301         memcpy(to, value, len);
302         return 0;
303 }
304
305 EXPORT_SYMBOL_GPL(dccp_insert_option);
306
307 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
308 {
309         struct dccp_sock *dp = dccp_sk(sk);
310         u64 ndp = dp->dccps_ndp_count;
311
312         if (dccp_non_data_packet(skb))
313                 ++dp->dccps_ndp_count;
314         else
315                 dp->dccps_ndp_count = 0;
316
317         if (ndp > 0) {
318                 unsigned char *ptr;
319                 const int ndp_len = dccp_ndp_len(ndp);
320                 const int len = ndp_len + 2;
321
322                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
323                         return -1;
324
325                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
326
327                 ptr = skb_push(skb, len);
328                 *ptr++ = DCCPO_NDP_COUNT;
329                 *ptr++ = len;
330                 dccp_encode_value_var(ndp, ptr, ndp_len);
331         }
332
333         return 0;
334 }
335
336 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
337 {
338         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
339 }
340
341 /* FIXME: This function is currently not used anywhere */
342 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
343 {
344         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
345         const int len = 2 + elapsed_time_len;
346         unsigned char *to;
347
348         if (elapsed_time_len == 0)
349                 return 0;
350
351         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
352                 return -1;
353
354         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
355
356         to    = skb_push(skb, len);
357         *to++ = DCCPO_ELAPSED_TIME;
358         *to++ = len;
359
360         if (elapsed_time_len == 2) {
361                 const __be16 var16 = htons((u16)elapsed_time);
362                 memcpy(to, &var16, 2);
363         } else {
364                 const __be32 var32 = htonl(elapsed_time);
365                 memcpy(to, &var32, 4);
366         }
367
368         return 0;
369 }
370
371 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
372
373 static int dccp_insert_option_timestamp(struct sk_buff *skb)
374 {
375         __be32 now = htonl(dccp_timestamp());
376         /* yes this will overflow but that is the point as we want a
377          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
378
379         return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
380 }
381
382 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
383                                              struct dccp_request_sock *dreq,
384                                              struct sk_buff *skb)
385 {
386         __be32 tstamp_echo;
387         unsigned char *to;
388         u32 elapsed_time, elapsed_time_len, len;
389
390         if (dreq != NULL) {
391                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
392                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
393                 dreq->dreq_timestamp_echo = 0;
394         } else {
395                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
396                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
397                 dp->dccps_timestamp_echo = 0;
398         }
399
400         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
401         len = 6 + elapsed_time_len;
402
403         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
404                 return -1;
405
406         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
407
408         to    = skb_push(skb, len);
409         *to++ = DCCPO_TIMESTAMP_ECHO;
410         *to++ = len;
411
412         memcpy(to, &tstamp_echo, 4);
413         to += 4;
414
415         if (elapsed_time_len == 2) {
416                 const __be16 var16 = htons((u16)elapsed_time);
417                 memcpy(to, &var16, 2);
418         } else if (elapsed_time_len == 4) {
419                 const __be32 var32 = htonl(elapsed_time);
420                 memcpy(to, &var32, 4);
421         }
422
423         return 0;
424 }
425
426 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
427 {
428         struct dccp_sock *dp = dccp_sk(sk);
429         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
430         const u16 buflen = dccp_ackvec_buflen(av);
431         /* Figure out how many options do we need to represent the ackvec */
432         const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
433         u16 len = buflen + 2 * nr_opts;
434         u8 i, nonce = 0;
435         const unsigned char *tail, *from;
436         unsigned char *to;
437
438         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
439                 return -1;
440
441         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
442
443         to   = skb_push(skb, len);
444         len  = buflen;
445         from = av->av_buf + av->av_buf_head;
446         tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
447
448         for (i = 0; i < nr_opts; ++i) {
449                 int copylen = len;
450
451                 if (len > DCCP_SINGLE_OPT_MAXLEN)
452                         copylen = DCCP_SINGLE_OPT_MAXLEN;
453
454                 /*
455                  * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
456                  * its type; ack_nonce is the sum of all individual buf_nonce's.
457                  */
458                 nonce ^= av->av_buf_nonce[i];
459
460                 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
461                 *to++ = copylen + 2;
462
463                 /* Check if buf_head wraps */
464                 if (from + copylen > tail) {
465                         const u16 tailsize = tail - from;
466
467                         memcpy(to, from, tailsize);
468                         to      += tailsize;
469                         len     -= tailsize;
470                         copylen -= tailsize;
471                         from    = av->av_buf;
472                 }
473
474                 memcpy(to, from, copylen);
475                 from += copylen;
476                 to   += copylen;
477                 len  -= copylen;
478         }
479         /*
480          * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
481          */
482         if (dccp_ackvec_update_records(av, DCCP_SKB_CB(skb)->dccpd_seq, nonce))
483                 return -ENOBUFS;
484         return 0;
485 }
486
487 /**
488  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
489  * Note that since we are using skb_push, this function needs to be called
490  * _after_ inserting the option it is supposed to influence (stack order).
491  */
492 int dccp_insert_option_mandatory(struct sk_buff *skb)
493 {
494         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
495                 return -1;
496
497         DCCP_SKB_CB(skb)->dccpd_opt_len++;
498         *skb_push(skb, 1) = DCCPO_MANDATORY;
499         return 0;
500 }
501
502 /**
503  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
504  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
505  * @feat: one out of %dccp_feature_numbers
506  * @val: NN value or SP array (preferred element first) to copy
507  * @len: true length of @val in bytes (excluding first element repetition)
508  * @repeat_first: whether to copy the first element of @val twice
509  * The last argument is used to construct Confirm options, where the preferred
510  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
511  * lists are kept such that the preferred entry is always first, so we only need
512  * to copy twice, and avoid the overhead of cloning into a bigger array.
513  */
514 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
515                        u8 *val, u8 len, bool repeat_first)
516 {
517         u8 tot_len, *to;
518
519         /* take the `Feature' field and possible repetition into account */
520         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
521                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
522                 return -1;
523         }
524
525         if (unlikely(val == NULL || len == 0))
526                 len = repeat_first = 0;
527         tot_len = 3 + repeat_first + len;
528
529         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
530                 DCCP_WARN("packet too small for feature %d option!\n", feat);
531                 return -1;
532         }
533         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
534
535         to    = skb_push(skb, tot_len);
536         *to++ = type;
537         *to++ = tot_len;
538         *to++ = feat;
539
540         if (repeat_first)
541                 *to++ = *val;
542         if (len)
543                 memcpy(to, val, len);
544         return 0;
545 }
546
547 /* The length of all options needs to be a multiple of 4 (5.8) */
548 static void dccp_insert_option_padding(struct sk_buff *skb)
549 {
550         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
551
552         if (padding != 0) {
553                 padding = 4 - padding;
554                 memset(skb_push(skb, padding), 0, padding);
555                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
556         }
557 }
558
559 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
560 {
561         struct dccp_sock *dp = dccp_sk(sk);
562
563         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
564
565         if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
566                 return -1;
567
568         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
569
570                 /* Feature Negotiation */
571                 if (dccp_feat_insert_opts(dp, NULL, skb))
572                         return -1;
573
574                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
575                         /*
576                          * Obtain RTT sample from Request/Response exchange.
577                          * This is currently used for TFRC initialisation.
578                          */
579                         if (dccp_insert_option_timestamp(skb))
580                                 return -1;
581
582                 } else if (dccp_ackvec_pending(sk) &&
583                            dccp_insert_option_ackvec(sk, skb)) {
584                                 return -1;
585                 }
586         }
587
588         if (dp->dccps_hc_rx_insert_options) {
589                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
590                         return -1;
591                 dp->dccps_hc_rx_insert_options = 0;
592         }
593
594         if (dp->dccps_timestamp_echo != 0 &&
595             dccp_insert_option_timestamp_echo(dp, NULL, skb))
596                 return -1;
597
598         dccp_insert_option_padding(skb);
599         return 0;
600 }
601
602 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
603 {
604         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
605
606         if (dccp_feat_insert_opts(NULL, dreq, skb))
607                 return -1;
608
609         /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
610         if (dccp_insert_option_timestamp(skb))
611                 return -1;
612
613         if (dreq->dreq_timestamp_echo != 0 &&
614             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
615                 return -1;
616
617         dccp_insert_option_padding(skb);
618         return 0;
619 }