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dccp: Header option insertion routine for feature-negotiation
[firewire-audio.git] / net / dccp / options.c
blobbfa1cb8f3ef1d689649c5ef2fef71edb1963b550
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 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
27 int sysctl_dccp_feat_rx_ccid = DCCPF_INITIAL_CCID;
28 int sysctl_dccp_feat_tx_ccid = DCCPF_INITIAL_CCID;
29 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
30 int sysctl_dccp_feat_send_ndp_count = DCCPF_INITIAL_SEND_NDP_COUNT;
31
32 u64 dccp_decode_value_var(const u8 *bf, const u8 len)
33 {
34 u64 value = 0;
35
36 if (len >= DCCP_OPTVAL_MAXLEN)
37 value += ((u64)*bf++) << 40;
38 if (len > 4)
39 value += ((u64)*bf++) << 32;
40 if (len > 3)
41 value += ((u64)*bf++) << 24;
42 if (len > 2)
43 value += ((u64)*bf++) << 16;
44 if (len > 1)
45 value += ((u64)*bf++) << 8;
46 if (len > 0)
47 value += *bf;
48
49 return value;
50 }
51
52 /**
53 * dccp_parse_options - Parse DCCP options present in @skb
54 * @sk: client|server|listening dccp socket (when @dreq != NULL)
55 * @dreq: request socket to use during connection setup, or NULL
56 */
57 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
58 struct sk_buff *skb)
59 {
60 struct dccp_sock *dp = dccp_sk(sk);
61 const struct dccp_hdr *dh = dccp_hdr(skb);
62 const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
63 u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
64 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
65 unsigned char *opt_ptr = options;
66 const unsigned char *opt_end = (unsigned char *)dh +
67 (dh->dccph_doff * 4);
68 struct dccp_options_received *opt_recv = &dp->dccps_options_received;
69 unsigned char opt, len;
70 unsigned char *value;
71 u32 elapsed_time;
72 __be32 opt_val;
73 int rc;
74 int mandatory = 0;
75
76 memset(opt_recv, 0, sizeof(*opt_recv));
77
78 opt = len = 0;
79 while (opt_ptr != opt_end) {
80 opt = *opt_ptr++;
81 len = 0;
82 value = NULL;
83
84 /* Check if this isn't a single byte option */
85 if (opt > DCCPO_MAX_RESERVED) {
86 if (opt_ptr == opt_end)
87 goto out_nonsensical_length;
88
89 len = *opt_ptr++;
90 if (len < 2)
91 goto out_nonsensical_length;
92 /*
93 * Remove the type and len fields, leaving
94 * just the value size
95 */
96 len -= 2;
97 value = opt_ptr;
98 opt_ptr += len;
99
100 if (opt_ptr > opt_end)
101 goto out_nonsensical_length;
102 }
103
104 /*
105 * CCID-Specific Options (from RFC 4340, sec. 10.3):
106 *
107 * Option numbers 128 through 191 are for options sent from the
108 * HC-Sender to the HC-Receiver; option numbers 192 through 255
109 * are for options sent from the HC-Receiver to the HC-Sender.
110 *
111 * CCID-specific options are ignored during connection setup, as
112 * negotiation may still be in progress (see RFC 4340, 10.3).
113 * The same applies to Ack Vectors, as these depend on the CCID.
114 *
115 */
116 if (dreq != NULL && (opt >= 128 ||
117 opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
118 goto ignore_option;
119
120 switch (opt) {
121 case DCCPO_PADDING:
122 break;
123 case DCCPO_MANDATORY:
124 if (mandatory)
125 goto out_invalid_option;
126 if (pkt_type != DCCP_PKT_DATA)
127 mandatory = 1;
128 break;
129 case DCCPO_NDP_COUNT:
130 if (len > 6)
131 goto out_invalid_option;
132
133 opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
134 dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
135 (unsigned long long)opt_recv->dccpor_ndp);
136 break;
137 case DCCPO_CHANGE_L:
138 /* fall through */
139 case DCCPO_CHANGE_R:
140 if (pkt_type == DCCP_PKT_DATA)
141 break;
142 if (len < 2)
143 goto out_invalid_option;
144 rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
145 len - 1);
146 /*
147 * When there is a change error, change_recv is
148 * responsible for dealing with it. i.e. reply with an
149 * empty confirm.
150 * If the change was mandatory, then we need to die.
151 */
152 if (rc && mandatory)
153 goto out_invalid_option;
154 break;
155 case DCCPO_CONFIRM_L:
156 /* fall through */
157 case DCCPO_CONFIRM_R:
158 if (pkt_type == DCCP_PKT_DATA)
159 break;
160 if (len < 2) /* FIXME this disallows empty confirm */
161 goto out_invalid_option;
162 if (dccp_feat_confirm_recv(sk, opt, *value,
163 value + 1, len - 1))
164 goto out_invalid_option;
165 break;
166 case DCCPO_ACK_VECTOR_0:
167 case DCCPO_ACK_VECTOR_1:
168 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
169 break;
170
171 if (dccp_msk(sk)->dccpms_send_ack_vector &&
172 dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
173 goto out_invalid_option;
174 break;
175 case DCCPO_TIMESTAMP:
176 if (len != 4)
177 goto out_invalid_option;
178 /*
179 * RFC 4340 13.1: "The precise time corresponding to
180 * Timestamp Value zero is not specified". We use
181 * zero to indicate absence of a meaningful timestamp.
182 */
183 opt_val = get_unaligned((__be32 *)value);
184 if (unlikely(opt_val == 0)) {
185 DCCP_WARN("Timestamp with zero value\n");
186 break;
187 }
188
189 if (dreq != NULL) {
190 dreq->dreq_timestamp_echo = ntohl(opt_val);
191 dreq->dreq_timestamp_time = dccp_timestamp();
192 } else {
193 opt_recv->dccpor_timestamp =
194 dp->dccps_timestamp_echo = ntohl(opt_val);
195 dp->dccps_timestamp_time = dccp_timestamp();
196 }
197 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
198 dccp_role(sk), ntohl(opt_val),
199 (unsigned long long)
200 DCCP_SKB_CB(skb)->dccpd_ack_seq);
201 break;
202 case DCCPO_TIMESTAMP_ECHO:
203 if (len != 4 && len != 6 && len != 8)
204 goto out_invalid_option;
205
206 opt_val = get_unaligned((__be32 *)value);
207 opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
208
209 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
210 "ackno=%llu", dccp_role(sk),
211 opt_recv->dccpor_timestamp_echo,
212 len + 2,
213 (unsigned long long)
214 DCCP_SKB_CB(skb)->dccpd_ack_seq);
215
216 value += 4;
217
218 if (len == 4) { /* no elapsed time included */
219 dccp_pr_debug_cat("\n");
220 break;
221 }
222
223 if (len == 6) { /* 2-byte elapsed time */
224 __be16 opt_val2 = get_unaligned((__be16 *)value);
225 elapsed_time = ntohs(opt_val2);
226 } else { /* 4-byte elapsed time */
227 opt_val = get_unaligned((__be32 *)value);
228 elapsed_time = ntohl(opt_val);
229 }
230
231 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
232
233 /* Give precedence to the biggest ELAPSED_TIME */
234 if (elapsed_time > opt_recv->dccpor_elapsed_time)
235 opt_recv->dccpor_elapsed_time = elapsed_time;
236 break;
237 case DCCPO_ELAPSED_TIME:
238 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */
239 break;
240
241 if (len == 2) {
242 __be16 opt_val2 = get_unaligned((__be16 *)value);
243 elapsed_time = ntohs(opt_val2);
244 } else if (len == 4) {
245 opt_val = get_unaligned((__be32 *)value);
246 elapsed_time = ntohl(opt_val);
247 } else {
248 goto out_invalid_option;
249 }
250
251 if (elapsed_time > opt_recv->dccpor_elapsed_time)
252 opt_recv->dccpor_elapsed_time = elapsed_time;
253
254 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
255 dccp_role(sk), elapsed_time);
256 break;
257 case 128 ... 191: {
258 const u16 idx = value - options;
259
260 if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
261 opt, len, idx,
262 value) != 0)
263 goto out_invalid_option;
264 }
265 break;
266 case 192 ... 255: {
267 const u16 idx = value - options;
268
269 if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
270 opt, len, idx,
271 value) != 0)
272 goto out_invalid_option;
273 }
274 break;
275 default:
276 DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
277 "implemented, ignoring", sk, opt, len);
278 break;
279 }
280 ignore_option:
281 if (opt != DCCPO_MANDATORY)
282 mandatory = 0;
283 }
284
285 /* mandatory was the last byte in option list -> reset connection */
286 if (mandatory)
287 goto out_invalid_option;
288
289 out_nonsensical_length:
290 /* RFC 4340, 5.8: ignore option and all remaining option space */
291 return 0;
292
293 out_invalid_option:
294 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
295 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
296 DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
297 DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
298 DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
299 DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
300 return -1;
301 }
302
303 EXPORT_SYMBOL_GPL(dccp_parse_options);
304
305 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
306 {
307 if (len >= DCCP_OPTVAL_MAXLEN)
308 *to++ = (value & 0xFF0000000000ull) >> 40;
309 if (len > 4)
310 *to++ = (value & 0xFF00000000ull) >> 32;
311 if (len > 3)
312 *to++ = (value & 0xFF000000) >> 24;
313 if (len > 2)
314 *to++ = (value & 0xFF0000) >> 16;
315 if (len > 1)
316 *to++ = (value & 0xFF00) >> 8;
317 if (len > 0)
318 *to++ = (value & 0xFF);
319 }
320
321 static inline u8 dccp_ndp_len(const u64 ndp)
322 {
323 if (likely(ndp <= 0xFF))
324 return 1;
325 return likely(ndp <= USHORT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
326 }
327
328 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
329 const unsigned char option,
330 const void *value, const unsigned char len)
331 {
332 unsigned char *to;
333
334 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
335 return -1;
336
337 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
338
339 to = skb_push(skb, len + 2);
340 *to++ = option;
341 *to++ = len + 2;
342
343 memcpy(to, value, len);
344 return 0;
345 }
346
347 EXPORT_SYMBOL_GPL(dccp_insert_option);
348
349 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
350 {
351 struct dccp_sock *dp = dccp_sk(sk);
352 u64 ndp = dp->dccps_ndp_count;
353
354 if (dccp_non_data_packet(skb))
355 ++dp->dccps_ndp_count;
356 else
357 dp->dccps_ndp_count = 0;
358
359 if (ndp > 0) {
360 unsigned char *ptr;
361 const int ndp_len = dccp_ndp_len(ndp);
362 const int len = ndp_len + 2;
363
364 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
365 return -1;
366
367 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
368
369 ptr = skb_push(skb, len);
370 *ptr++ = DCCPO_NDP_COUNT;
371 *ptr++ = len;
372 dccp_encode_value_var(ndp, ptr, ndp_len);
373 }
374
375 return 0;
376 }
377
378 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
379 {
380 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
381 }
382
383 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
384 u32 elapsed_time)
385 {
386 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
387 const int len = 2 + elapsed_time_len;
388 unsigned char *to;
389
390 if (elapsed_time_len == 0)
391 return 0;
392
393 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
394 return -1;
395
396 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
397
398 to = skb_push(skb, len);
399 *to++ = DCCPO_ELAPSED_TIME;
400 *to++ = len;
401
402 if (elapsed_time_len == 2) {
403 const __be16 var16 = htons((u16)elapsed_time);
404 memcpy(to, &var16, 2);
405 } else {
406 const __be32 var32 = htonl(elapsed_time);
407 memcpy(to, &var32, 4);
408 }
409
410 return 0;
411 }
412
413 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
414
415 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
416 {
417 __be32 now = htonl(dccp_timestamp());
418 /* yes this will overflow but that is the point as we want a
419 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
420
421 return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
422 }
423
424 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
425
426 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
427 struct dccp_request_sock *dreq,
428 struct sk_buff *skb)
429 {
430 __be32 tstamp_echo;
431 unsigned char *to;
432 u32 elapsed_time, elapsed_time_len, len;
433
434 if (dreq != NULL) {
435 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
436 tstamp_echo = htonl(dreq->dreq_timestamp_echo);
437 dreq->dreq_timestamp_echo = 0;
438 } else {
439 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
440 tstamp_echo = htonl(dp->dccps_timestamp_echo);
441 dp->dccps_timestamp_echo = 0;
442 }
443
444 elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
445 len = 6 + elapsed_time_len;
446
447 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
448 return -1;
449
450 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
451
452 to = skb_push(skb, len);
453 *to++ = DCCPO_TIMESTAMP_ECHO;
454 *to++ = len;
455
456 memcpy(to, &tstamp_echo, 4);
457 to += 4;
458
459 if (elapsed_time_len == 2) {
460 const __be16 var16 = htons((u16)elapsed_time);
461 memcpy(to, &var16, 2);
462 } else if (elapsed_time_len == 4) {
463 const __be32 var32 = htonl(elapsed_time);
464 memcpy(to, &var32, 4);
465 }
466
467 return 0;
468 }
469
470 /**
471 * dccp_insert_option_mandatory - Mandatory option (5.8.2)
472 * Note that since we are using skb_push, this function needs to be called
473 * _after_ inserting the option it is supposed to influence (stack order).
474 */
475 int dccp_insert_option_mandatory(struct sk_buff *skb)
476 {
477 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
478 return -1;
479
480 DCCP_SKB_CB(skb)->dccpd_opt_len++;
481 *skb_push(skb, 1) = DCCPO_MANDATORY;
482 return 0;
483 }
484
485 /**
486 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
487 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
488 * @feat: one out of %dccp_feature_numbers
489 * @val: NN value or SP array (preferred element first) to copy
490 * @len: true length of @val in bytes (excluding first element repetition)
491 * @repeat_first: whether to copy the first element of @val twice
492 * The last argument is used to construct Confirm options, where the preferred
493 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
494 * lists are kept such that the preferred entry is always first, so we only need
495 * to copy twice, and avoid the overhead of cloning into a bigger array.
496 */
497 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
498 u8 *val, u8 len, bool repeat_first)
499 {
500 u8 tot_len, *to;
501
502 /* take the `Feature' field and possible repetition into account */
503 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
504 DCCP_WARN("length %u for feature %u too large\n", len, feat);
505 return -1;
506 }
507
508 if (unlikely(val == NULL || len == 0))
509 len = repeat_first = 0;
510 tot_len = 3 + repeat_first + len;
511
512 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
513 DCCP_WARN("packet too small for feature %d option!\n", feat);
514 return -1;
515 }
516 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
517
518 to = skb_push(skb, tot_len);
519 *to++ = type;
520 *to++ = tot_len;
521 *to++ = feat;
522
523 if (repeat_first)
524 *to++ = *val;
525 if (len)
526 memcpy(to, val, len);
527
528 dccp_pr_debug("%s(%s (%d), ...), length %d\n",
529 dccp_feat_typename(type),
530 dccp_feat_name(feat), feat, len);
531 return 0;
532 }
533
534 /* The length of all options needs to be a multiple of 4 (5.8) */
535 static void dccp_insert_option_padding(struct sk_buff *skb)
536 {
537 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
538
539 if (padding != 0) {
540 padding = 4 - padding;
541 memset(skb_push(skb, padding), 0, padding);
542 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
543 }
544 }
545
546 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
547 {
548 struct dccp_sock *dp = dccp_sk(sk);
549 struct dccp_minisock *dmsk = dccp_msk(sk);
550
551 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
552
553 if (dmsk->dccpms_send_ndp_count &&
554 dccp_insert_option_ndp(sk, skb))
555 return -1;
556
557 if (!dccp_packet_without_ack(skb)) {
558 if (dmsk->dccpms_send_ack_vector &&
559 dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
560 dccp_insert_option_ackvec(sk, skb))
561 return -1;
562 }
563
564 if (dp->dccps_hc_rx_insert_options) {
565 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
566 return -1;
567 dp->dccps_hc_rx_insert_options = 0;
568 }
569
570 /*
571 * Obtain RTT sample from Request/Response exchange.
572 * This is currently used in CCID 3 initialisation.
573 */
574 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
575 dccp_insert_option_timestamp(sk, skb))
576 return -1;
577
578 if (dp->dccps_timestamp_echo != 0 &&
579 dccp_insert_option_timestamp_echo(dp, NULL, skb))
580 return -1;
581
582 dccp_insert_option_padding(skb);
583 return 0;
584 }
585
586 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
587 {
588 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
589
590 if (dreq->dreq_timestamp_echo != 0 &&
591 dccp_insert_option_timestamp_echo(NULL, dreq, skb))
592 return -1;
593
594 dccp_insert_option_padding(skb);
595 return 0;
596 }
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