dccp/tcp: Fixup bhash2 bucket when connect() fails.
[platform/kernel/linux-starfive.git] / net / dccp / options.c
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /*
3  *  net/dccp/options.c
4  *
5  *  An implementation of the DCCP protocol
6  *  Copyright (c) 2005 Aristeu Sergio Rozanski Filho <aris@cathedrallabs.org>
7  *  Copyright (c) 2005 Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
8  *  Copyright (c) 2005 Ian McDonald <ian.mcdonald@jandi.co.nz>
9  */
10 #include <linux/dccp.h>
11 #include <linux/module.h>
12 #include <linux/types.h>
13 #include <asm/unaligned.h>
14 #include <linux/kernel.h>
15 #include <linux/skbuff.h>
16
17 #include "ackvec.h"
18 #include "ccid.h"
19 #include "dccp.h"
20 #include "feat.h"
21
22 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
23 {
24         u64 value = 0;
25
26         if (len >= DCCP_OPTVAL_MAXLEN)
27                 value += ((u64)*bf++) << 40;
28         if (len > 4)
29                 value += ((u64)*bf++) << 32;
30         if (len > 3)
31                 value += ((u64)*bf++) << 24;
32         if (len > 2)
33                 value += ((u64)*bf++) << 16;
34         if (len > 1)
35                 value += ((u64)*bf++) << 8;
36         if (len > 0)
37                 value += *bf;
38
39         return value;
40 }
41
42 /**
43  * dccp_parse_options  -  Parse DCCP options present in @skb
44  * @sk: client|server|listening dccp socket (when @dreq != NULL)
45  * @dreq: request socket to use during connection setup, or NULL
46  * @skb: frame to parse
47  */
48 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
49                        struct sk_buff *skb)
50 {
51         struct dccp_sock *dp = dccp_sk(sk);
52         const struct dccp_hdr *dh = dccp_hdr(skb);
53         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
54         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
55         unsigned char *opt_ptr = options;
56         const unsigned char *opt_end = (unsigned char *)dh +
57                                         (dh->dccph_doff * 4);
58         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
59         unsigned char opt, len;
60         unsigned char *value;
61         u32 elapsed_time;
62         __be32 opt_val;
63         int rc;
64         int mandatory = 0;
65
66         memset(opt_recv, 0, sizeof(*opt_recv));
67
68         opt = len = 0;
69         while (opt_ptr != opt_end) {
70                 opt   = *opt_ptr++;
71                 len   = 0;
72                 value = NULL;
73
74                 /* Check if this isn't a single byte option */
75                 if (opt > DCCPO_MAX_RESERVED) {
76                         if (opt_ptr == opt_end)
77                                 goto out_nonsensical_length;
78
79                         len = *opt_ptr++;
80                         if (len < 2)
81                                 goto out_nonsensical_length;
82                         /*
83                          * Remove the type and len fields, leaving
84                          * just the value size
85                          */
86                         len     -= 2;
87                         value   = opt_ptr;
88                         opt_ptr += len;
89
90                         if (opt_ptr > opt_end)
91                                 goto out_nonsensical_length;
92                 }
93
94                 /*
95                  * CCID-specific options are ignored during connection setup, as
96                  * negotiation may still be in progress (see RFC 4340, 10.3).
97                  * The same applies to Ack Vectors, as these depend on the CCID.
98                  */
99                 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
100                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
101                         goto ignore_option;
102
103                 switch (opt) {
104                 case DCCPO_PADDING:
105                         break;
106                 case DCCPO_MANDATORY:
107                         if (mandatory)
108                                 goto out_invalid_option;
109                         if (pkt_type != DCCP_PKT_DATA)
110                                 mandatory = 1;
111                         break;
112                 case DCCPO_NDP_COUNT:
113                         if (len > 6)
114                                 goto out_invalid_option;
115
116                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
117                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
118                                       (unsigned long long)opt_recv->dccpor_ndp);
119                         break;
120                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
121                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
122                                 break;
123                         if (len == 0)
124                                 goto out_invalid_option;
125                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
126                                                     *value, value + 1, len - 1);
127                         if (rc)
128                                 goto out_featneg_failed;
129                         break;
130                 case DCCPO_TIMESTAMP:
131                         if (len != 4)
132                                 goto out_invalid_option;
133                         /*
134                          * RFC 4340 13.1: "The precise time corresponding to
135                          * Timestamp Value zero is not specified". We use
136                          * zero to indicate absence of a meaningful timestamp.
137                          */
138                         opt_val = get_unaligned((__be32 *)value);
139                         if (unlikely(opt_val == 0)) {
140                                 DCCP_WARN("Timestamp with zero value\n");
141                                 break;
142                         }
143
144                         if (dreq != NULL) {
145                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
146                                 dreq->dreq_timestamp_time = dccp_timestamp();
147                         } else {
148                                 opt_recv->dccpor_timestamp =
149                                         dp->dccps_timestamp_echo = ntohl(opt_val);
150                                 dp->dccps_timestamp_time = dccp_timestamp();
151                         }
152                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
153                                       dccp_role(sk), ntohl(opt_val),
154                                       (unsigned long long)
155                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
156                         /* schedule an Ack in case this sender is quiescent */
157                         inet_csk_schedule_ack(sk);
158                         break;
159                 case DCCPO_TIMESTAMP_ECHO:
160                         if (len != 4 && len != 6 && len != 8)
161                                 goto out_invalid_option;
162
163                         opt_val = get_unaligned((__be32 *)value);
164                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
165
166                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
167                                       "ackno=%llu", dccp_role(sk),
168                                       opt_recv->dccpor_timestamp_echo,
169                                       len + 2,
170                                       (unsigned long long)
171                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
172
173                         value += 4;
174
175                         if (len == 4) {         /* no elapsed time included */
176                                 dccp_pr_debug_cat("\n");
177                                 break;
178                         }
179
180                         if (len == 6) {         /* 2-byte elapsed time */
181                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
182                                 elapsed_time = ntohs(opt_val2);
183                         } else {                /* 4-byte elapsed time */
184                                 opt_val = get_unaligned((__be32 *)value);
185                                 elapsed_time = ntohl(opt_val);
186                         }
187
188                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
189
190                         /* Give precedence to the biggest ELAPSED_TIME */
191                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
192                                 opt_recv->dccpor_elapsed_time = elapsed_time;
193                         break;
194                 case DCCPO_ELAPSED_TIME:
195                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
196                                 break;
197
198                         if (len == 2) {
199                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
200                                 elapsed_time = ntohs(opt_val2);
201                         } else if (len == 4) {
202                                 opt_val = get_unaligned((__be32 *)value);
203                                 elapsed_time = ntohl(opt_val);
204                         } else {
205                                 goto out_invalid_option;
206                         }
207
208                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
209                                 opt_recv->dccpor_elapsed_time = elapsed_time;
210
211                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
212                                       dccp_role(sk), elapsed_time);
213                         break;
214                 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC:
215                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
216                                                      pkt_type, opt, value, len))
217                                 goto out_invalid_option;
218                         break;
219                 case DCCPO_ACK_VECTOR_0:
220                 case DCCPO_ACK_VECTOR_1:
221                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
222                                 break;
223                         /*
224                          * Ack vectors are processed by the TX CCID if it is
225                          * interested. The RX CCID need not parse Ack Vectors,
226                          * since it is only interested in clearing old state.
227                          */
228                         fallthrough;
229                 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC:
230                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
231                                                      pkt_type, opt, value, len))
232                                 goto out_invalid_option;
233                         break;
234                 default:
235                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
236                                   "implemented, ignoring", sk, opt, len);
237                         break;
238                 }
239 ignore_option:
240                 if (opt != DCCPO_MANDATORY)
241                         mandatory = 0;
242         }
243
244         /* mandatory was the last byte in option list -> reset connection */
245         if (mandatory)
246                 goto out_invalid_option;
247
248 out_nonsensical_length:
249         /* RFC 4340, 5.8: ignore option and all remaining option space */
250         return 0;
251
252 out_invalid_option:
253         DCCP_INC_STATS(DCCP_MIB_INVALIDOPT);
254         rc = DCCP_RESET_CODE_OPTION_ERROR;
255 out_featneg_failed:
256         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
257         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
258         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
259         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
260         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
261         return -1;
262 }
263
264 EXPORT_SYMBOL_GPL(dccp_parse_options);
265
266 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
267 {
268         if (len >= DCCP_OPTVAL_MAXLEN)
269                 *to++ = (value & 0xFF0000000000ull) >> 40;
270         if (len > 4)
271                 *to++ = (value & 0xFF00000000ull) >> 32;
272         if (len > 3)
273                 *to++ = (value & 0xFF000000) >> 24;
274         if (len > 2)
275                 *to++ = (value & 0xFF0000) >> 16;
276         if (len > 1)
277                 *to++ = (value & 0xFF00) >> 8;
278         if (len > 0)
279                 *to++ = (value & 0xFF);
280 }
281
282 static inline u8 dccp_ndp_len(const u64 ndp)
283 {
284         if (likely(ndp <= 0xFF))
285                 return 1;
286         return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
287 }
288
289 int dccp_insert_option(struct sk_buff *skb, const unsigned char option,
290                        const void *value, const unsigned char len)
291 {
292         unsigned char *to;
293
294         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
295                 return -1;
296
297         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
298
299         to    = skb_push(skb, len + 2);
300         *to++ = option;
301         *to++ = len + 2;
302
303         memcpy(to, value, len);
304         return 0;
305 }
306
307 EXPORT_SYMBOL_GPL(dccp_insert_option);
308
309 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
310 {
311         struct dccp_sock *dp = dccp_sk(sk);
312         u64 ndp = dp->dccps_ndp_count;
313
314         if (dccp_non_data_packet(skb))
315                 ++dp->dccps_ndp_count;
316         else
317                 dp->dccps_ndp_count = 0;
318
319         if (ndp > 0) {
320                 unsigned char *ptr;
321                 const int ndp_len = dccp_ndp_len(ndp);
322                 const int len = ndp_len + 2;
323
324                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
325                         return -1;
326
327                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
328
329                 ptr = skb_push(skb, len);
330                 *ptr++ = DCCPO_NDP_COUNT;
331                 *ptr++ = len;
332                 dccp_encode_value_var(ndp, ptr, ndp_len);
333         }
334
335         return 0;
336 }
337
338 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
339 {
340         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
341 }
342
343 static int dccp_insert_option_timestamp(struct sk_buff *skb)
344 {
345         __be32 now = htonl(dccp_timestamp());
346         /* yes this will overflow but that is the point as we want a
347          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
348
349         return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
350 }
351
352 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
353                                              struct dccp_request_sock *dreq,
354                                              struct sk_buff *skb)
355 {
356         __be32 tstamp_echo;
357         unsigned char *to;
358         u32 elapsed_time, elapsed_time_len, len;
359
360         if (dreq != NULL) {
361                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
362                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
363                 dreq->dreq_timestamp_echo = 0;
364         } else {
365                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
366                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
367                 dp->dccps_timestamp_echo = 0;
368         }
369
370         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
371         len = 6 + elapsed_time_len;
372
373         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
374                 return -1;
375
376         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
377
378         to    = skb_push(skb, len);
379         *to++ = DCCPO_TIMESTAMP_ECHO;
380         *to++ = len;
381
382         memcpy(to, &tstamp_echo, 4);
383         to += 4;
384
385         if (elapsed_time_len == 2) {
386                 const __be16 var16 = htons((u16)elapsed_time);
387                 memcpy(to, &var16, 2);
388         } else if (elapsed_time_len == 4) {
389                 const __be32 var32 = htonl(elapsed_time);
390                 memcpy(to, &var32, 4);
391         }
392
393         return 0;
394 }
395
396 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb)
397 {
398         struct dccp_sock *dp = dccp_sk(sk);
399         struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec;
400         struct dccp_skb_cb *dcb = DCCP_SKB_CB(skb);
401         const u16 buflen = dccp_ackvec_buflen(av);
402         /* Figure out how many options do we need to represent the ackvec */
403         const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN);
404         u16 len = buflen + 2 * nr_opts;
405         u8 i, nonce = 0;
406         const unsigned char *tail, *from;
407         unsigned char *to;
408
409         if (dcb->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) {
410                 DCCP_WARN("Lacking space for %u bytes on %s packet\n", len,
411                           dccp_packet_name(dcb->dccpd_type));
412                 return -1;
413         }
414         /*
415          * Since Ack Vectors are variable-length, we can not always predict
416          * their size. To catch exception cases where the space is running out
417          * on the skb, a separate Sync is scheduled to carry the Ack Vector.
418          */
419         if (len > DCCPAV_MIN_OPTLEN &&
420             len + dcb->dccpd_opt_len + skb->len > dp->dccps_mss_cache) {
421                 DCCP_WARN("No space left for Ack Vector (%u) on skb (%u+%u), "
422                           "MPS=%u ==> reduce payload size?\n", len, skb->len,
423                           dcb->dccpd_opt_len, dp->dccps_mss_cache);
424                 dp->dccps_sync_scheduled = 1;
425                 return 0;
426         }
427         dcb->dccpd_opt_len += len;
428
429         to   = skb_push(skb, len);
430         len  = buflen;
431         from = av->av_buf + av->av_buf_head;
432         tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN;
433
434         for (i = 0; i < nr_opts; ++i) {
435                 int copylen = len;
436
437                 if (len > DCCP_SINGLE_OPT_MAXLEN)
438                         copylen = DCCP_SINGLE_OPT_MAXLEN;
439
440                 /*
441                  * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via
442                  * its type; ack_nonce is the sum of all individual buf_nonce's.
443                  */
444                 nonce ^= av->av_buf_nonce[i];
445
446                 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i];
447                 *to++ = copylen + 2;
448
449                 /* Check if buf_head wraps */
450                 if (from + copylen > tail) {
451                         const u16 tailsize = tail - from;
452
453                         memcpy(to, from, tailsize);
454                         to      += tailsize;
455                         len     -= tailsize;
456                         copylen -= tailsize;
457                         from    = av->av_buf;
458                 }
459
460                 memcpy(to, from, copylen);
461                 from += copylen;
462                 to   += copylen;
463                 len  -= copylen;
464         }
465         /*
466          * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340.
467          */
468         if (dccp_ackvec_update_records(av, dcb->dccpd_seq, nonce))
469                 return -ENOBUFS;
470         return 0;
471 }
472
473 /**
474  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
475  * @skb: frame into which to insert option
476  *
477  * Note that since we are using skb_push, this function needs to be called
478  * _after_ inserting the option it is supposed to influence (stack order).
479  */
480 int dccp_insert_option_mandatory(struct sk_buff *skb)
481 {
482         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
483                 return -1;
484
485         DCCP_SKB_CB(skb)->dccpd_opt_len++;
486         *(u8 *)skb_push(skb, 1) = DCCPO_MANDATORY;
487         return 0;
488 }
489
490 /**
491  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
492  * @skb: frame to insert feature negotiation option into
493  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
494  * @feat: one out of %dccp_feature_numbers
495  * @val: NN value or SP array (preferred element first) to copy
496  * @len: true length of @val in bytes (excluding first element repetition)
497  * @repeat_first: whether to copy the first element of @val twice
498  *
499  * The last argument is used to construct Confirm options, where the preferred
500  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
501  * lists are kept such that the preferred entry is always first, so we only need
502  * to copy twice, and avoid the overhead of cloning into a bigger array.
503  */
504 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
505                        u8 *val, u8 len, bool repeat_first)
506 {
507         u8 tot_len, *to;
508
509         /* take the `Feature' field and possible repetition into account */
510         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
511                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
512                 return -1;
513         }
514
515         if (unlikely(val == NULL || len == 0))
516                 len = repeat_first = false;
517         tot_len = 3 + repeat_first + len;
518
519         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
520                 DCCP_WARN("packet too small for feature %d option!\n", feat);
521                 return -1;
522         }
523         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
524
525         to    = skb_push(skb, tot_len);
526         *to++ = type;
527         *to++ = tot_len;
528         *to++ = feat;
529
530         if (repeat_first)
531                 *to++ = *val;
532         if (len)
533                 memcpy(to, val, len);
534         return 0;
535 }
536
537 /* The length of all options needs to be a multiple of 4 (5.8) */
538 static void dccp_insert_option_padding(struct sk_buff *skb)
539 {
540         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
541
542         if (padding != 0) {
543                 padding = 4 - padding;
544                 memset(skb_push(skb, padding), 0, padding);
545                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
546         }
547 }
548
549 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
550 {
551         struct dccp_sock *dp = dccp_sk(sk);
552
553         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
554
555         if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
556                 return -1;
557
558         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
559
560                 /* Feature Negotiation */
561                 if (dccp_feat_insert_opts(dp, NULL, skb))
562                         return -1;
563
564                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
565                         /*
566                          * Obtain RTT sample from Request/Response exchange.
567                          * This is currently used for TFRC initialisation.
568                          */
569                         if (dccp_insert_option_timestamp(skb))
570                                 return -1;
571
572                 } else if (dccp_ackvec_pending(sk) &&
573                            dccp_insert_option_ackvec(sk, skb)) {
574                                 return -1;
575                 }
576         }
577
578         if (dp->dccps_hc_rx_insert_options) {
579                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
580                         return -1;
581                 dp->dccps_hc_rx_insert_options = 0;
582         }
583
584         if (dp->dccps_timestamp_echo != 0 &&
585             dccp_insert_option_timestamp_echo(dp, NULL, skb))
586                 return -1;
587
588         dccp_insert_option_padding(skb);
589         return 0;
590 }
591
592 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
593 {
594         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
595
596         if (dccp_feat_insert_opts(NULL, dreq, skb))
597                 return -1;
598
599         /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
600         if (dccp_insert_option_timestamp(skb))
601                 return -1;
602
603         if (dreq->dreq_timestamp_echo != 0 &&
604             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
605                 return -1;
606
607         dccp_insert_option_padding(skb);
608         return 0;
609 }