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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 u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
58 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
59 unsigned char *opt_ptr = options;
60 const unsigned char *opt_end = (unsigned char *)dh +
61 (dh->dccph_doff * 4);
62 struct dccp_options_received *opt_recv = &dp->dccps_options_received;
63 unsigned char opt, len;
64 unsigned char *uninitialized_var(value);
65 u32 elapsed_time;
66 __be32 opt_val;
67 int rc;
68 int mandatory = 0;
69
70 memset(opt_recv, 0, sizeof(*opt_recv));
71
72 opt = len = 0;
73 while (opt_ptr != opt_end) {
74 opt = *opt_ptr++;
75 len = 0;
76 value = NULL;
77
78 /* Check if this isn't a single byte option */
79 if (opt > DCCPO_MAX_RESERVED) {
80 if (opt_ptr == opt_end)
81 goto out_nonsensical_length;
82
83 len = *opt_ptr++;
84 if (len < 2)
85 goto out_nonsensical_length;
86 /*
87 * Remove the type and len fields, leaving
88 * just the value size
89 */
90 len -= 2;
91 value = opt_ptr;
92 opt_ptr += len;
93
94 if (opt_ptr > opt_end)
95 goto out_nonsensical_length;
96 }
97
98 /*
99 * CCID-specific options are ignored during connection setup, as
100 * negotiation may still be in progress (see RFC 4340, 10.3).
101 * The same applies to Ack Vectors, as these depend on the CCID.
102 */
103 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC ||
104 opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
105 goto ignore_option;
106
107 switch (opt) {
108 case DCCPO_PADDING:
109 break;
110 case DCCPO_MANDATORY:
111 if (mandatory)
112 goto out_invalid_option;
113 if (pkt_type != DCCP_PKT_DATA)
114 mandatory = 1;
115 break;
116 case DCCPO_NDP_COUNT:
117 if (len > 6)
118 goto out_invalid_option;
119
120 opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
121 dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
122 (unsigned long long)opt_recv->dccpor_ndp);
123 break;
124 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
125 if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */
126 break;
127 rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
128 *value, value + 1, len - 1);
129 if (rc)
130 goto out_featneg_failed;
131 break;
132 case DCCPO_ACK_VECTOR_0:
133 case DCCPO_ACK_VECTOR_1:
134 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */
135 break;
136 if (dp->dccps_hc_rx_ackvec != NULL &&
137 dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
138 goto out_invalid_option;
139 break;
140 case DCCPO_TIMESTAMP:
141 if (len != 4)
142 goto out_invalid_option;
143 /*
144 * RFC 4340 13.1: "The precise time corresponding to
145 * Timestamp Value zero is not specified". We use
146 * zero to indicate absence of a meaningful timestamp.
147 */
148 opt_val = get_unaligned((__be32 *)value);
149 if (unlikely(opt_val == 0)) {
150 DCCP_WARN("Timestamp with zero value\n");
151 break;
152 }
153
154 if (dreq != NULL) {
155 dreq->dreq_timestamp_echo = ntohl(opt_val);
156 dreq->dreq_timestamp_time = dccp_timestamp();
157 } else {
158 opt_recv->dccpor_timestamp =
159 dp->dccps_timestamp_echo = ntohl(opt_val);
160 dp->dccps_timestamp_time = dccp_timestamp();
161 }
162 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
163 dccp_role(sk), ntohl(opt_val),
164 (unsigned long long)
165 DCCP_SKB_CB(skb)->dccpd_ack_seq);
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 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time)
342 {
343 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
344 const int len = 2 + elapsed_time_len;
345 unsigned char *to;
346
347 if (elapsed_time_len == 0)
348 return 0;
349
350 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
351 return -1;
352
353 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
354
355 to = skb_push(skb, len);
356 *to++ = DCCPO_ELAPSED_TIME;
357 *to++ = len;
358
359 if (elapsed_time_len == 2) {
360 const __be16 var16 = htons((u16)elapsed_time);
361 memcpy(to, &var16, 2);
362 } else {
363 const __be32 var32 = htonl(elapsed_time);
364 memcpy(to, &var32, 4);
365 }
366
367 return 0;
368 }
369
370 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
371
372 int dccp_insert_option_timestamp(struct sk_buff *skb)
373 {
374 __be32 now = htonl(dccp_timestamp());
375 /* yes this will overflow but that is the point as we want a
376 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
377
378 return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now));
379 }
380
381 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
382
383 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
384 struct dccp_request_sock *dreq,
385 struct sk_buff *skb)
386 {
387 __be32 tstamp_echo;
388 unsigned char *to;
389 u32 elapsed_time, elapsed_time_len, len;
390
391 if (dreq != NULL) {
392 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
393 tstamp_echo = htonl(dreq->dreq_timestamp_echo);
394 dreq->dreq_timestamp_echo = 0;
395 } else {
396 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
397 tstamp_echo = htonl(dp->dccps_timestamp_echo);
398 dp->dccps_timestamp_echo = 0;
399 }
400
401 elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
402 len = 6 + elapsed_time_len;
403
404 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
405 return -1;
406
407 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
408
409 to = skb_push(skb, len);
410 *to++ = DCCPO_TIMESTAMP_ECHO;
411 *to++ = len;
412
413 memcpy(to, &tstamp_echo, 4);
414 to += 4;
415
416 if (elapsed_time_len == 2) {
417 const __be16 var16 = htons((u16)elapsed_time);
418 memcpy(to, &var16, 2);
419 } else if (elapsed_time_len == 4) {
420 const __be32 var32 = htonl(elapsed_time);
421 memcpy(to, &var32, 4);
422 }
423
424 return 0;
425 }
426
427 /**
428 * dccp_insert_option_mandatory - Mandatory option (5.8.2)
429 * Note that since we are using skb_push, this function needs to be called
430 * _after_ inserting the option it is supposed to influence (stack order).
431 */
432 int dccp_insert_option_mandatory(struct sk_buff *skb)
433 {
434 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
435 return -1;
436
437 DCCP_SKB_CB(skb)->dccpd_opt_len++;
438 *skb_push(skb, 1) = DCCPO_MANDATORY;
439 return 0;
440 }
441
442 /**
443 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb
444 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
445 * @feat: one out of %dccp_feature_numbers
446 * @val: NN value or SP array (preferred element first) to copy
447 * @len: true length of @val in bytes (excluding first element repetition)
448 * @repeat_first: whether to copy the first element of @val twice
449 * The last argument is used to construct Confirm options, where the preferred
450 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
451 * lists are kept such that the preferred entry is always first, so we only need
452 * to copy twice, and avoid the overhead of cloning into a bigger array.
453 */
454 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
455 u8 *val, u8 len, bool repeat_first)
456 {
457 u8 tot_len, *to;
458
459 /* take the `Feature' field and possible repetition into account */
460 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
461 DCCP_WARN("length %u for feature %u too large\n", len, feat);
462 return -1;
463 }
464
465 if (unlikely(val == NULL || len == 0))
466 len = repeat_first = 0;
467 tot_len = 3 + repeat_first + len;
468
469 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
470 DCCP_WARN("packet too small for feature %d option!\n", feat);
471 return -1;
472 }
473 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
474
475 to = skb_push(skb, tot_len);
476 *to++ = type;
477 *to++ = tot_len;
478 *to++ = feat;
479
480 if (repeat_first)
481 *to++ = *val;
482 if (len)
483 memcpy(to, val, len);
484 return 0;
485 }
486
487 /* The length of all options needs to be a multiple of 4 (5.8) */
488 static void dccp_insert_option_padding(struct sk_buff *skb)
489 {
490 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
491
492 if (padding != 0) {
493 padding = 4 - padding;
494 memset(skb_push(skb, padding), 0, padding);
495 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
496 }
497 }
498
499 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
500 {
501 struct dccp_sock *dp = dccp_sk(sk);
502
503 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
504
505 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
506 return -1;
507
508 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
509
510 /* Feature Negotiation */
511 if (dccp_feat_insert_opts(dp, NULL, skb))
512 return -1;
513
514 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
515 /*
516 * Obtain RTT sample from Request/Response exchange.
517 * This is currently used for TFRC initialisation.
518 */
519 if (dccp_insert_option_timestamp(skb))
520 return -1;
521
522 } else if (dp->dccps_hc_rx_ackvec != NULL &&
523 dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
524 dccp_insert_option_ackvec(sk, skb)) {
525 return -1;
526 }
527 }
528
529 if (dp->dccps_hc_rx_insert_options) {
530 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
531 return -1;
532 dp->dccps_hc_rx_insert_options = 0;
533 }
534
535 if (dp->dccps_timestamp_echo != 0 &&
536 dccp_insert_option_timestamp_echo(dp, NULL, skb))
537 return -1;
538
539 dccp_insert_option_padding(skb);
540 return 0;
541 }
542
543 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
544 {
545 DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
546
547 if (dccp_feat_insert_opts(NULL, dreq, skb))
548 return -1;
549
550 /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */
551 if (dccp_insert_option_timestamp(skb))
552 return -1;
553
554 if (dreq->dreq_timestamp_echo != 0 &&
555 dccp_insert_option_timestamp_echo(NULL, dreq, skb))
556 return -1;
557
558 dccp_insert_option_padding(skb);
559 return 0;
560 }
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