dccp: Initialisation and type-checking of feature sysctls
[linux-2.6.git] / net / dccp / options.c
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 *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 (from RFC 4340, sec. 10.3):
100                  *
101                  * Option numbers 128 through 191 are for options sent from the
102                  * HC-Sender to the HC-Receiver; option numbers 192 through 255
103                  * are for options sent from the HC-Receiver to the HC-Sender.
104                  *
105                  * CCID-specific options are ignored during connection setup, as
106                  * negotiation may still be in progress (see RFC 4340, 10.3).
107                  * The same applies to Ack Vectors, as these depend on the CCID.
108                  *
109                  */
110                 if (dreq != NULL && (opt >= 128 ||
111                     opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1))
112                         goto ignore_option;
113
114                 switch (opt) {
115                 case DCCPO_PADDING:
116                         break;
117                 case DCCPO_MANDATORY:
118                         if (mandatory)
119                                 goto out_invalid_option;
120                         if (pkt_type != DCCP_PKT_DATA)
121                                 mandatory = 1;
122                         break;
123                 case DCCPO_NDP_COUNT:
124                         if (len > 6)
125                                 goto out_invalid_option;
126
127                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
128                         dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk),
129                                       (unsigned long long)opt_recv->dccpor_ndp);
130                         break;
131                 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R:
132                         if (pkt_type == DCCP_PKT_DATA)      /* RFC 4340, 6 */
133                                 break;
134                         rc = dccp_feat_parse_options(sk, dreq, mandatory, opt,
135                                                     *value, value + 1, len - 1);
136                         if (rc)
137                                 goto out_featneg_failed;
138                         break;
139                 case DCCPO_ACK_VECTOR_0:
140                 case DCCPO_ACK_VECTOR_1:
141                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
142                                 break;
143                         if (dp->dccps_hc_rx_ackvec != NULL &&
144                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
145                                 goto out_invalid_option;
146                         break;
147                 case DCCPO_TIMESTAMP:
148                         if (len != 4)
149                                 goto out_invalid_option;
150                         /*
151                          * RFC 4340 13.1: "The precise time corresponding to
152                          * Timestamp Value zero is not specified". We use
153                          * zero to indicate absence of a meaningful timestamp.
154                          */
155                         opt_val = get_unaligned((__be32 *)value);
156                         if (unlikely(opt_val == 0)) {
157                                 DCCP_WARN("Timestamp with zero value\n");
158                                 break;
159                         }
160
161                         if (dreq != NULL) {
162                                 dreq->dreq_timestamp_echo = ntohl(opt_val);
163                                 dreq->dreq_timestamp_time = dccp_timestamp();
164                         } else {
165                                 opt_recv->dccpor_timestamp =
166                                         dp->dccps_timestamp_echo = ntohl(opt_val);
167                                 dp->dccps_timestamp_time = dccp_timestamp();
168                         }
169                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
170                                       dccp_role(sk), ntohl(opt_val),
171                                       (unsigned long long)
172                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
173                         break;
174                 case DCCPO_TIMESTAMP_ECHO:
175                         if (len != 4 && len != 6 && len != 8)
176                                 goto out_invalid_option;
177
178                         opt_val = get_unaligned((__be32 *)value);
179                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
180
181                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
182                                       "ackno=%llu", dccp_role(sk),
183                                       opt_recv->dccpor_timestamp_echo,
184                                       len + 2,
185                                       (unsigned long long)
186                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
187
188                         value += 4;
189
190                         if (len == 4) {         /* no elapsed time included */
191                                 dccp_pr_debug_cat("\n");
192                                 break;
193                         }
194
195                         if (len == 6) {         /* 2-byte elapsed time */
196                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
197                                 elapsed_time = ntohs(opt_val2);
198                         } else {                /* 4-byte elapsed time */
199                                 opt_val = get_unaligned((__be32 *)value);
200                                 elapsed_time = ntohl(opt_val);
201                         }
202
203                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
204
205                         /* Give precedence to the biggest ELAPSED_TIME */
206                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
207                                 opt_recv->dccpor_elapsed_time = elapsed_time;
208                         break;
209                 case DCCPO_ELAPSED_TIME:
210                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
211                                 break;
212
213                         if (len == 2) {
214                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
215                                 elapsed_time = ntohs(opt_val2);
216                         } else if (len == 4) {
217                                 opt_val = get_unaligned((__be32 *)value);
218                                 elapsed_time = ntohl(opt_val);
219                         } else {
220                                 goto out_invalid_option;
221                         }
222
223                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
224                                 opt_recv->dccpor_elapsed_time = elapsed_time;
225
226                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
227                                       dccp_role(sk), elapsed_time);
228                         break;
229                 case 128 ... 191: {
230                         const u16 idx = value - options;
231
232                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
233                                                      opt, len, idx,
234                                                      value) != 0)
235                                 goto out_invalid_option;
236                 }
237                         break;
238                 case 192 ... 255: {
239                         const u16 idx = value - options;
240
241                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
242                                                      opt, len, idx,
243                                                      value) != 0)
244                                 goto out_invalid_option;
245                 }
246                         break;
247                 default:
248                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
249                                   "implemented, ignoring", sk, opt, len);
250                         break;
251                 }
252 ignore_option:
253                 if (opt != DCCPO_MANDATORY)
254                         mandatory = 0;
255         }
256
257         /* mandatory was the last byte in option list -> reset connection */
258         if (mandatory)
259                 goto out_invalid_option;
260
261 out_nonsensical_length:
262         /* RFC 4340, 5.8: ignore option and all remaining option space */
263         return 0;
264
265 out_invalid_option:
266         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
267         rc = DCCP_RESET_CODE_OPTION_ERROR;
268 out_featneg_failed:
269         DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc);
270         DCCP_SKB_CB(skb)->dccpd_reset_code = rc;
271         DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt;
272         DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0;
273         DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0;
274         return -1;
275 }
276
277 EXPORT_SYMBOL_GPL(dccp_parse_options);
278
279 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len)
280 {
281         if (len >= DCCP_OPTVAL_MAXLEN)
282                 *to++ = (value & 0xFF0000000000ull) >> 40;
283         if (len > 4)
284                 *to++ = (value & 0xFF00000000ull) >> 32;
285         if (len > 3)
286                 *to++ = (value & 0xFF000000) >> 24;
287         if (len > 2)
288                 *to++ = (value & 0xFF0000) >> 16;
289         if (len > 1)
290                 *to++ = (value & 0xFF00) >> 8;
291         if (len > 0)
292                 *to++ = (value & 0xFF);
293 }
294
295 static inline u8 dccp_ndp_len(const u64 ndp)
296 {
297         if (likely(ndp <= 0xFF))
298                 return 1;
299         return likely(ndp <= USHORT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6);
300 }
301
302 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
303                         const unsigned char option,
304                         const void *value, const unsigned char len)
305 {
306         unsigned char *to;
307
308         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
309                 return -1;
310
311         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
312
313         to    = skb_push(skb, len + 2);
314         *to++ = option;
315         *to++ = len + 2;
316
317         memcpy(to, value, len);
318         return 0;
319 }
320
321 EXPORT_SYMBOL_GPL(dccp_insert_option);
322
323 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
324 {
325         struct dccp_sock *dp = dccp_sk(sk);
326         u64 ndp = dp->dccps_ndp_count;
327
328         if (dccp_non_data_packet(skb))
329                 ++dp->dccps_ndp_count;
330         else
331                 dp->dccps_ndp_count = 0;
332
333         if (ndp > 0) {
334                 unsigned char *ptr;
335                 const int ndp_len = dccp_ndp_len(ndp);
336                 const int len = ndp_len + 2;
337
338                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
339                         return -1;
340
341                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
342
343                 ptr = skb_push(skb, len);
344                 *ptr++ = DCCPO_NDP_COUNT;
345                 *ptr++ = len;
346                 dccp_encode_value_var(ndp, ptr, ndp_len);
347         }
348
349         return 0;
350 }
351
352 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
353 {
354         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
355 }
356
357 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
358                                     u32 elapsed_time)
359 {
360         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
361         const int len = 2 + elapsed_time_len;
362         unsigned char *to;
363
364         if (elapsed_time_len == 0)
365                 return 0;
366
367         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
368                 return -1;
369
370         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
371
372         to    = skb_push(skb, len);
373         *to++ = DCCPO_ELAPSED_TIME;
374         *to++ = len;
375
376         if (elapsed_time_len == 2) {
377                 const __be16 var16 = htons((u16)elapsed_time);
378                 memcpy(to, &var16, 2);
379         } else {
380                 const __be32 var32 = htonl(elapsed_time);
381                 memcpy(to, &var32, 4);
382         }
383
384         return 0;
385 }
386
387 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
388
389 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
390 {
391         __be32 now = htonl(dccp_timestamp());
392         /* yes this will overflow but that is the point as we want a
393          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
394
395         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
396 }
397
398 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
399
400 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp,
401                                              struct dccp_request_sock *dreq,
402                                              struct sk_buff *skb)
403 {
404         __be32 tstamp_echo;
405         unsigned char *to;
406         u32 elapsed_time, elapsed_time_len, len;
407
408         if (dreq != NULL) {
409                 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time;
410                 tstamp_echo  = htonl(dreq->dreq_timestamp_echo);
411                 dreq->dreq_timestamp_echo = 0;
412         } else {
413                 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time;
414                 tstamp_echo  = htonl(dp->dccps_timestamp_echo);
415                 dp->dccps_timestamp_echo = 0;
416         }
417
418         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
419         len = 6 + elapsed_time_len;
420
421         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
422                 return -1;
423
424         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
425
426         to    = skb_push(skb, len);
427         *to++ = DCCPO_TIMESTAMP_ECHO;
428         *to++ = len;
429
430         memcpy(to, &tstamp_echo, 4);
431         to += 4;
432
433         if (elapsed_time_len == 2) {
434                 const __be16 var16 = htons((u16)elapsed_time);
435                 memcpy(to, &var16, 2);
436         } else if (elapsed_time_len == 4) {
437                 const __be32 var32 = htonl(elapsed_time);
438                 memcpy(to, &var32, 4);
439         }
440
441         return 0;
442 }
443
444 /**
445  * dccp_insert_option_mandatory  -  Mandatory option (5.8.2)
446  * Note that since we are using skb_push, this function needs to be called
447  * _after_ inserting the option it is supposed to influence (stack order).
448  */
449 int dccp_insert_option_mandatory(struct sk_buff *skb)
450 {
451         if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN)
452                 return -1;
453
454         DCCP_SKB_CB(skb)->dccpd_opt_len++;
455         *skb_push(skb, 1) = DCCPO_MANDATORY;
456         return 0;
457 }
458
459 /**
460  * dccp_insert_fn_opt  -  Insert single Feature-Negotiation option into @skb
461  * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R
462  * @feat: one out of %dccp_feature_numbers
463  * @val: NN value or SP array (preferred element first) to copy
464  * @len: true length of @val in bytes (excluding first element repetition)
465  * @repeat_first: whether to copy the first element of @val twice
466  * The last argument is used to construct Confirm options, where the preferred
467  * value and the preference list appear separately (RFC 4340, 6.3.1). Preference
468  * lists are kept such that the preferred entry is always first, so we only need
469  * to copy twice, and avoid the overhead of cloning into a bigger array.
470  */
471 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat,
472                        u8 *val, u8 len, bool repeat_first)
473 {
474         u8 tot_len, *to;
475
476         /* take the `Feature' field and possible repetition into account */
477         if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) {
478                 DCCP_WARN("length %u for feature %u too large\n", len, feat);
479                 return -1;
480         }
481
482         if (unlikely(val == NULL || len == 0))
483                 len = repeat_first = 0;
484         tot_len = 3 + repeat_first + len;
485
486         if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) {
487                 DCCP_WARN("packet too small for feature %d option!\n", feat);
488                 return -1;
489         }
490         DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len;
491
492         to    = skb_push(skb, tot_len);
493         *to++ = type;
494         *to++ = tot_len;
495         *to++ = feat;
496
497         if (repeat_first)
498                 *to++ = *val;
499         if (len)
500                 memcpy(to, val, len);
501
502         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
503                       dccp_feat_typename(type),
504                       dccp_feat_name(feat), feat, len);
505         return 0;
506 }
507
508 /* The length of all options needs to be a multiple of 4 (5.8) */
509 static void dccp_insert_option_padding(struct sk_buff *skb)
510 {
511         int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
512
513         if (padding != 0) {
514                 padding = 4 - padding;
515                 memset(skb_push(skb, padding), 0, padding);
516                 DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
517         }
518 }
519
520 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
521 {
522         struct dccp_sock *dp = dccp_sk(sk);
523
524         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
525
526         if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb))
527                 return -1;
528
529         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) {
530
531                 /* Feature Negotiation */
532                 if (dccp_feat_insert_opts(dp, NULL, skb))
533                         return -1;
534
535                 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) {
536                         /*
537                          * Obtain RTT sample from Request/Response exchange.
538                          * This is currently used in CCID 3 initialisation.
539                          */
540                         if (dccp_insert_option_timestamp(sk, skb))
541                                 return -1;
542
543                 } else if (dp->dccps_hc_rx_ackvec != NULL &&
544                            dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
545                            dccp_insert_option_ackvec(sk, skb)) {
546                                 return -1;
547                 }
548         }
549
550         if (dp->dccps_hc_rx_insert_options) {
551                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
552                         return -1;
553                 dp->dccps_hc_rx_insert_options = 0;
554         }
555
556         if (dp->dccps_timestamp_echo != 0 &&
557             dccp_insert_option_timestamp_echo(dp, NULL, skb))
558                 return -1;
559
560         dccp_insert_option_padding(skb);
561         return 0;
562 }
563
564 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb)
565 {
566         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
567
568         if (dccp_feat_insert_opts(NULL, dreq, skb))
569                 return -1;
570
571         if (dreq->dreq_timestamp_echo != 0 &&
572             dccp_insert_option_timestamp_echo(NULL, dreq, skb))
573                 return -1;
574
575         dccp_insert_option_padding(skb);
576         return 0;
577 }