xref: /openbmc/linux/net/dccp/options.c (revision 22246614)
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_ack_ratio	      = DCCPF_INITIAL_ACK_RATIO;
30 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
31 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
32 
33 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
34 {
35 	u32 value = 0;
36 
37 	if (len > 3)
38 		value += *bf++ << 24;
39 	if (len > 2)
40 		value += *bf++ << 16;
41 	if (len > 1)
42 		value += *bf++ << 8;
43 	if (len > 0)
44 		value += *bf;
45 
46 	return value;
47 }
48 
49 /**
50  * dccp_parse_options  -  Parse DCCP options present in @skb
51  * @sk: client|server|listening dccp socket (when @dreq != NULL)
52  * @dreq: request socket to use during connection setup, or NULL
53  */
54 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
55 		       struct sk_buff *skb)
56 {
57 	struct dccp_sock *dp = dccp_sk(sk);
58 	const struct dccp_hdr *dh = dccp_hdr(skb);
59 	const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
60 	u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
61 	unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
62 	unsigned char *opt_ptr = options;
63 	const unsigned char *opt_end = (unsigned char *)dh +
64 					(dh->dccph_doff * 4);
65 	struct dccp_options_received *opt_recv = &dp->dccps_options_received;
66 	unsigned char opt, len;
67 	unsigned char *value;
68 	u32 elapsed_time;
69 	__be32 opt_val;
70 	int rc;
71 	int mandatory = 0;
72 
73 	memset(opt_recv, 0, sizeof(*opt_recv));
74 
75 	opt = len = 0;
76 	while (opt_ptr != opt_end) {
77 		opt   = *opt_ptr++;
78 		len   = 0;
79 		value = NULL;
80 
81 		/* Check if this isn't a single byte option */
82 		if (opt > DCCPO_MAX_RESERVED) {
83 			if (opt_ptr == opt_end)
84 				goto out_invalid_option;
85 
86 			len = *opt_ptr++;
87 			if (len < 3)
88 				goto out_invalid_option;
89 			/*
90 			 * Remove the type and len fields, leaving
91 			 * just the value size
92 			 */
93 			len	-= 2;
94 			value	= opt_ptr;
95 			opt_ptr += len;
96 
97 			if (opt_ptr > opt_end)
98 				goto out_invalid_option;
99 		}
100 
101 		/*
102 		 * CCID-Specific Options (from RFC 4340, sec. 10.3):
103 		 *
104 		 * Option numbers 128 through 191 are for options sent from the
105 		 * HC-Sender to the HC-Receiver; option numbers 192 through 255
106 		 * are for options sent from the HC-Receiver to	the HC-Sender.
107 		 *
108 		 * CCID-specific options are ignored during connection setup, as
109 		 * negotiation may still be in progress (see RFC 4340, 10.3).
110 		 *
111 		 */
112 		if (dreq != NULL && opt >= 128)
113 			goto ignore_option;
114 
115 		switch (opt) {
116 		case DCCPO_PADDING:
117 			break;
118 		case DCCPO_MANDATORY:
119 			if (mandatory)
120 				goto out_invalid_option;
121 			if (pkt_type != DCCP_PKT_DATA)
122 				mandatory = 1;
123 			break;
124 		case DCCPO_NDP_COUNT:
125 			if (len > 3)
126 				goto out_invalid_option;
127 
128 			opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
129 			dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
130 				      opt_recv->dccpor_ndp);
131 			break;
132 		case DCCPO_CHANGE_L:
133 			/* fall through */
134 		case DCCPO_CHANGE_R:
135 			if (pkt_type == DCCP_PKT_DATA)
136 				break;
137 			if (len < 2)
138 				goto out_invalid_option;
139 			rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
140 						   len - 1);
141 			/*
142 			 * When there is a change error, change_recv is
143 			 * responsible for dealing with it.  i.e. reply with an
144 			 * empty confirm.
145 			 * If the change was mandatory, then we need to die.
146 			 */
147 			if (rc && mandatory)
148 				goto out_invalid_option;
149 			break;
150 		case DCCPO_CONFIRM_L:
151 			/* fall through */
152 		case DCCPO_CONFIRM_R:
153 			if (pkt_type == DCCP_PKT_DATA)
154 				break;
155 			if (len < 2)	/* FIXME this disallows empty confirm */
156 				goto out_invalid_option;
157 			if (dccp_feat_confirm_recv(sk, opt, *value,
158 						   value + 1, len - 1))
159 				goto out_invalid_option;
160 			break;
161 		case DCCPO_ACK_VECTOR_0:
162 		case DCCPO_ACK_VECTOR_1:
163 			if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
164 				break;
165 
166 			if (dccp_msk(sk)->dccpms_send_ack_vector &&
167 			    dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
168 				goto out_invalid_option;
169 			break;
170 		case DCCPO_TIMESTAMP:
171 			if (len != 4)
172 				goto out_invalid_option;
173 			/*
174 			 * RFC 4340 13.1: "The precise time corresponding to
175 			 * Timestamp Value zero is not specified". We use
176 			 * zero to indicate absence of a meaningful timestamp.
177 			 */
178 			opt_val = get_unaligned((__be32 *)value);
179 			if (unlikely(opt_val == 0)) {
180 				DCCP_WARN("Timestamp with zero value\n");
181 				break;
182 			}
183 
184 			if (dreq != NULL) {
185 				dreq->dreq_timestamp_echo = ntohl(opt_val);
186 				dreq->dreq_timestamp_time = dccp_timestamp();
187 			} else {
188 				opt_recv->dccpor_timestamp =
189 					dp->dccps_timestamp_echo = ntohl(opt_val);
190 				dp->dccps_timestamp_time = dccp_timestamp();
191 			}
192 			dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
193 				      dccp_role(sk), ntohl(opt_val),
194 				      (unsigned long long)
195 				      DCCP_SKB_CB(skb)->dccpd_ack_seq);
196 			break;
197 		case DCCPO_TIMESTAMP_ECHO:
198 			if (len != 4 && len != 6 && len != 8)
199 				goto out_invalid_option;
200 
201 			opt_val = get_unaligned((__be32 *)value);
202 			opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
203 
204 			dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
205 				      "ackno=%llu", dccp_role(sk),
206 				      opt_recv->dccpor_timestamp_echo,
207 				      len + 2,
208 				      (unsigned long long)
209 				      DCCP_SKB_CB(skb)->dccpd_ack_seq);
210 
211 			value += 4;
212 
213 			if (len == 4) {		/* no elapsed time included */
214 				dccp_pr_debug_cat("\n");
215 				break;
216 			}
217 
218 			if (len == 6) {		/* 2-byte elapsed time */
219 				__be16 opt_val2 = get_unaligned((__be16 *)value);
220 				elapsed_time = ntohs(opt_val2);
221 			} else {		/* 4-byte elapsed time */
222 				opt_val = get_unaligned((__be32 *)value);
223 				elapsed_time = ntohl(opt_val);
224 			}
225 
226 			dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
227 
228 			/* Give precedence to the biggest ELAPSED_TIME */
229 			if (elapsed_time > opt_recv->dccpor_elapsed_time)
230 				opt_recv->dccpor_elapsed_time = elapsed_time;
231 			break;
232 		case DCCPO_ELAPSED_TIME:
233 			if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
234 				break;
235 
236 			if (len == 2) {
237 				__be16 opt_val2 = get_unaligned((__be16 *)value);
238 				elapsed_time = ntohs(opt_val2);
239 			} else if (len == 4) {
240 				opt_val = get_unaligned((__be32 *)value);
241 				elapsed_time = ntohl(opt_val);
242 			} else {
243 				goto out_invalid_option;
244 			}
245 
246 			if (elapsed_time > opt_recv->dccpor_elapsed_time)
247 				opt_recv->dccpor_elapsed_time = elapsed_time;
248 
249 			dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
250 				      dccp_role(sk), elapsed_time);
251 			break;
252 		case 128 ... 191: {
253 			const u16 idx = value - options;
254 
255 			if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
256 						     opt, len, idx,
257 						     value) != 0)
258 				goto out_invalid_option;
259 		}
260 			break;
261 		case 192 ... 255: {
262 			const u16 idx = value - options;
263 
264 			if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
265 						     opt, len, idx,
266 						     value) != 0)
267 				goto out_invalid_option;
268 		}
269 			break;
270 		default:
271 			DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
272 				  "implemented, ignoring", sk, opt, len);
273 			break;
274 		}
275 ignore_option:
276 		if (opt != DCCPO_MANDATORY)
277 			mandatory = 0;
278 	}
279 
280 	/* mandatory was the last byte in option list -> reset connection */
281 	if (mandatory)
282 		goto out_invalid_option;
283 
284 	return 0;
285 
286 out_invalid_option:
287 	DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
288 	DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
289 	DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
290 	return -1;
291 }
292 
293 EXPORT_SYMBOL_GPL(dccp_parse_options);
294 
295 static void dccp_encode_value_var(const u32 value, unsigned char *to,
296 				  const unsigned int len)
297 {
298 	if (len > 3)
299 		*to++ = (value & 0xFF000000) >> 24;
300 	if (len > 2)
301 		*to++ = (value & 0xFF0000) >> 16;
302 	if (len > 1)
303 		*to++ = (value & 0xFF00) >> 8;
304 	if (len > 0)
305 		*to++ = (value & 0xFF);
306 }
307 
308 static inline int dccp_ndp_len(const int ndp)
309 {
310 	return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
311 }
312 
313 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
314 			const unsigned char option,
315 			const void *value, const unsigned char len)
316 {
317 	unsigned char *to;
318 
319 	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
320 		return -1;
321 
322 	DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
323 
324 	to    = skb_push(skb, len + 2);
325 	*to++ = option;
326 	*to++ = len + 2;
327 
328 	memcpy(to, value, len);
329 	return 0;
330 }
331 
332 EXPORT_SYMBOL_GPL(dccp_insert_option);
333 
334 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
335 {
336 	struct dccp_sock *dp = dccp_sk(sk);
337 	int ndp = dp->dccps_ndp_count;
338 
339 	if (dccp_non_data_packet(skb))
340 		++dp->dccps_ndp_count;
341 	else
342 		dp->dccps_ndp_count = 0;
343 
344 	if (ndp > 0) {
345 		unsigned char *ptr;
346 		const int ndp_len = dccp_ndp_len(ndp);
347 		const int len = ndp_len + 2;
348 
349 		if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
350 			return -1;
351 
352 		DCCP_SKB_CB(skb)->dccpd_opt_len += len;
353 
354 		ptr = skb_push(skb, len);
355 		*ptr++ = DCCPO_NDP_COUNT;
356 		*ptr++ = len;
357 		dccp_encode_value_var(ndp, ptr, ndp_len);
358 	}
359 
360 	return 0;
361 }
362 
363 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
364 {
365 	return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
366 }
367 
368 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
369 				    u32 elapsed_time)
370 {
371 	const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
372 	const int len = 2 + elapsed_time_len;
373 	unsigned char *to;
374 
375 	if (elapsed_time_len == 0)
376 		return 0;
377 
378 	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
379 		return -1;
380 
381 	DCCP_SKB_CB(skb)->dccpd_opt_len += len;
382 
383 	to    = skb_push(skb, len);
384 	*to++ = DCCPO_ELAPSED_TIME;
385 	*to++ = len;
386 
387 	if (elapsed_time_len == 2) {
388 		const __be16 var16 = htons((u16)elapsed_time);
389 		memcpy(to, &var16, 2);
390 	} else {
391 		const __be32 var32 = htonl(elapsed_time);
392 		memcpy(to, &var32, 4);
393 	}
394 
395 	return 0;
396 }
397 
398 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
399 
400 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
401 {
402 	__be32 now = htonl(dccp_timestamp());
403 	/* yes this will overflow but that is the point as we want a
404 	 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
405 
406 	return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
407 }
408 
409 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
410 
411 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
412 					     struct dccp_request_sock *dreq,
413 					     struct sk_buff *skb)
414 {
415 	__be32 tstamp_echo;
416 	unsigned char *to;
417 	u32 elapsed_time, elapsed_time_len, len;
418 
419 	if (dreq != NULL) {
420 		elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
421 		tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
422 		dreq->dreq_timestamp_echo = 0;
423 	} else {
424 		elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
425 		tstamp_echo  = htonl(dp->dccps_timestamp_echo);
426 		dp->dccps_timestamp_echo = 0;
427 	}
428 
429 	elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
430 	len = 6 + elapsed_time_len;
431 
432 	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
433 		return -1;
434 
435 	DCCP_SKB_CB(skb)->dccpd_opt_len += len;
436 
437 	to    = skb_push(skb, len);
438 	*to++ = DCCPO_TIMESTAMP_ECHO;
439 	*to++ = len;
440 
441 	memcpy(to, &tstamp_echo, 4);
442 	to += 4;
443 
444 	if (elapsed_time_len == 2) {
445 		const __be16 var16 = htons((u16)elapsed_time);
446 		memcpy(to, &var16, 2);
447 	} else if (elapsed_time_len == 4) {
448 		const __be32 var32 = htonl(elapsed_time);
449 		memcpy(to, &var32, 4);
450 	}
451 
452 	return 0;
453 }
454 
455 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
456 				u8 *val, u8 len)
457 {
458 	u8 *to;
459 
460 	if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
461 		DCCP_WARN("packet too small for feature %d option!\n", feat);
462 		return -1;
463 	}
464 
465 	DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
466 
467 	to    = skb_push(skb, len + 3);
468 	*to++ = type;
469 	*to++ = len + 3;
470 	*to++ = feat;
471 
472 	if (len)
473 		memcpy(to, val, len);
474 
475 	dccp_pr_debug("%s(%s (%d), ...), length %d\n",
476 		      dccp_feat_typename(type),
477 		      dccp_feat_name(feat), feat, len);
478 	return 0;
479 }
480 
481 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
482 {
483 	struct dccp_sock *dp = dccp_sk(sk);
484 	struct dccp_minisock *dmsk = dccp_msk(sk);
485 	struct dccp_opt_pend *opt, *next;
486 	int change = 0;
487 
488 	/* confirm any options [NN opts] */
489 	list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
490 		dccp_insert_feat_opt(skb, opt->dccpop_type,
491 				     opt->dccpop_feat, opt->dccpop_val,
492 				     opt->dccpop_len);
493 		/* fear empty confirms */
494 		if (opt->dccpop_val)
495 			kfree(opt->dccpop_val);
496 		kfree(opt);
497 	}
498 	INIT_LIST_HEAD(&dmsk->dccpms_conf);
499 
500 	/* see which features we need to send */
501 	list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
502 		/* see if we need to send any confirm */
503 		if (opt->dccpop_sc) {
504 			dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
505 					     opt->dccpop_feat,
506 					     opt->dccpop_sc->dccpoc_val,
507 					     opt->dccpop_sc->dccpoc_len);
508 
509 			BUG_ON(!opt->dccpop_sc->dccpoc_val);
510 			kfree(opt->dccpop_sc->dccpoc_val);
511 			kfree(opt->dccpop_sc);
512 			opt->dccpop_sc = NULL;
513 		}
514 
515 		/* any option not confirmed, re-send it */
516 		if (!opt->dccpop_conf) {
517 			dccp_insert_feat_opt(skb, opt->dccpop_type,
518 					     opt->dccpop_feat, opt->dccpop_val,
519 					     opt->dccpop_len);
520 			change++;
521 		}
522 	}
523 
524 	/* Retransmit timer.
525 	 * If this is the master listening sock, we don't set a timer on it.  It
526 	 * should be fine because if the dude doesn't receive our RESPONSE
527 	 * [which will contain the CHANGE] he will send another REQUEST which
528 	 * will "retrnasmit" the change.
529 	 */
530 	if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
531 		dccp_pr_debug("reset feat negotiation timer %p\n", sk);
532 
533 		/* XXX don't reset the timer on re-transmissions.  I.e. reset it
534 		 * only when sending new stuff i guess.  Currently the timer
535 		 * never backs off because on re-transmission it just resets it!
536 		 */
537 		inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
538 					  inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
539 	}
540 
541 	return 0;
542 }
543 
544 /* The length of all options needs to be a multiple of 4 (5.8) */
545 static void dccp_insert_option_padding(struct sk_buff *skb)
546 {
547 	int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
548 
549 	if (padding != 0) {
550 		padding = 4 - padding;
551 		memset(skb_push(skb, padding), 0, padding);
552 		DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
553 	}
554 }
555 
556 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
557 {
558 	struct dccp_sock *dp = dccp_sk(sk);
559 	struct dccp_minisock *dmsk = dccp_msk(sk);
560 
561 	DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
562 
563 	if (dmsk->dccpms_send_ndp_count &&
564 	    dccp_insert_option_ndp(sk, skb))
565 		return -1;
566 
567 	if (!dccp_packet_without_ack(skb)) {
568 		if (dmsk->dccpms_send_ack_vector &&
569 		    dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
570 		    dccp_insert_option_ackvec(sk, skb))
571 			return -1;
572 	}
573 
574 	if (dp->dccps_hc_rx_insert_options) {
575 		if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
576 			return -1;
577 		dp->dccps_hc_rx_insert_options = 0;
578 	}
579 
580 	/* Feature negotiation */
581 	/* Data packets can't do feat negotiation */
582 	if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
583 	    DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
584 	    dccp_insert_options_feat(sk, skb))
585 		return -1;
586 
587 	/*
588 	 * Obtain RTT sample from Request/Response exchange.
589 	 * This is currently used in CCID 3 initialisation.
590 	 */
591 	if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
592 	    dccp_insert_option_timestamp(sk, skb))
593 		return -1;
594 
595 	if (dp->dccps_timestamp_echo != 0 &&
596 	    dccp_insert_option_timestamp_echo(dp, NULL, skb))
597 		return -1;
598 
599 	dccp_insert_option_padding(skb);
600 	return 0;
601 }
602 
603 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
604 {
605 	DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
606 
607 	if (dreq->dreq_timestamp_echo != 0 &&
608 	    dccp_insert_option_timestamp_echo(NULL, dreq, skb))
609 		return -1;
610 
611 	dccp_insert_option_padding(skb);
612 	return 0;
613 }
614