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