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