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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 <linux/kernel.h>
  18 #include <linux/skbuff.h>
  19
  20 #include "ackvec.h"
  21 #include "ccid.h"
  22 #include "dccp.h"
  23 #include "feat.h"
  24
  25 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
  26 int sysctl_dccp_feat_rx_ccid          = DCCPF_INITIAL_CCID;
  27 int sysctl_dccp_feat_tx_ccid          = DCCPF_INITIAL_CCID;
  28 int sysctl_dccp_feat_ack_ratio        = DCCPF_INITIAL_ACK_RATIO;
  29 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  30 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  31
  32 void dccp_minisock_init(struct dccp_minisock *dmsk)
  33 {
  34         dmsk->dccpms_sequence_window = sysctl_dccp_feat_sequence_window;
  35         dmsk->dccpms_rx_ccid         = sysctl_dccp_feat_rx_ccid;
  36         dmsk->dccpms_tx_ccid         = sysctl_dccp_feat_tx_ccid;
  37         dmsk->dccpms_ack_ratio       = sysctl_dccp_feat_ack_ratio;
  38         dmsk->dccpms_send_ack_vector = sysctl_dccp_feat_send_ack_vector;
  39         dmsk->dccpms_send_ndp_count  = sysctl_dccp_feat_send_ndp_count;
  40 }
  41
  42 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  43 {
  44         u32 value = 0;
  45
  46         if (len > 3)
  47                 value += *bf++ << 24;
  48         if (len > 2)
  49                 value += *bf++ << 16;
  50         if (len > 1)
  51                 value += *bf++ << 8;
  52         if (len > 0)
  53                 value += *bf;
  54
  55         return value;
  56 }
  57
  58 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
  59 {
  60         struct dccp_sock *dp = dccp_sk(sk);
  61         const struct dccp_hdr *dh = dccp_hdr(skb);
  62         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  63         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
  64         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  65         unsigned char *opt_ptr = options;
  66         const unsigned char *opt_end = (unsigned char *)dh +
  67                                         (dh->dccph_doff * 4);
  68         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  69         unsigned char opt, len;
  70         unsigned char *value;
  71         u32 elapsed_time;
  72         int rc;
  73         int mandatory = 0;
  74
  75         memset(opt_recv, 0, sizeof(*opt_recv));
  76
  77         opt = len = 0;
  78         while (opt_ptr != opt_end) {
  79                 opt   = *opt_ptr++;
  80                 len   = 0;
  81                 value = NULL;
  82
  83                 /* Check if this isn't a single byte option */
  84                 if (opt > DCCPO_MAX_RESERVED) {
  85                         if (opt_ptr == opt_end)
  86                                 goto out_invalid_option;
  87
  88                         len = *opt_ptr++;
  89                         if (len < 3)
  90                                 goto out_invalid_option;
  91                         /*
  92                          * Remove the type and len fields, leaving
  93                          * just the value size
  94                          */
  95                         len     -= 2;
  96                         value   = opt_ptr;
  97                         opt_ptr += len;
  98
  99                         if (opt_ptr > opt_end)
 100                                 goto out_invalid_option;
 101                 }
 102
 103                 switch (opt) {
 104                 case DCCPO_PADDING:
 105                         break;
 106                 case DCCPO_MANDATORY:
 107                         if (mandatory)
 108                                 goto out_invalid_option;
 109                         if (pkt_type != DCCP_PKT_DATA)
 110                                 mandatory = 1;
 111                         break;
 112                 case DCCPO_NDP_COUNT:
 113                         if (len > 3)
 114                                 goto out_invalid_option;
 115
 116                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 117                         dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
 118                                       opt_recv->dccpor_ndp);
 119                         break;
 120                 case DCCPO_CHANGE_L:
 121                         /* fall through */
 122                 case DCCPO_CHANGE_R:
 123                         if (len < 2)
 124                                 goto out_invalid_option;
 125                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 126                                                    len - 1);
 127                         /*
 128                          * When there is a change error, change_recv is
 129                          * responsible for dealing with it.  i.e. reply with an
 130                          * empty confirm.
 131                          * If the change was mandatory, then we need to die.
 132                          */
 133                         if (rc && mandatory)
 134                                 goto out_invalid_option;
 135                         break;
 136                 case DCCPO_CONFIRM_L:
 137                         /* fall through */
 138                 case DCCPO_CONFIRM_R:
 139                         if (len < 2)
 140                                 goto out_invalid_option;
 141                         if (dccp_feat_confirm_recv(sk, opt, *value,
 142                                                    value + 1, len - 1))
 143                                 goto out_invalid_option;
 144                         break;
 145                 case DCCPO_ACK_VECTOR_0:
 146                 case DCCPO_ACK_VECTOR_1:
 147                         if (pkt_type == DCCP_PKT_DATA)
 148                                 break;
 149
 150                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 151                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 152                                 goto out_invalid_option;
 153                         break;
 154                 case DCCPO_TIMESTAMP:
 155                         if (len != 4)
 156                                 goto out_invalid_option;
 157
 158                         opt_recv->dccpor_timestamp = ntohl(*(__be32 *)value);
 159
 160                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 161                         dccp_timestamp(sk, &dp->dccps_timestamp_time);
 162
 163                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 164                                       dccp_role(sk), opt_recv->dccpor_timestamp,
 165                                       (unsigned long long)
 166                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 167                         break;
 168                 case DCCPO_TIMESTAMP_ECHO:
 169                         if (len != 4 && len != 6 && len != 8)
 170                                 goto out_invalid_option;
 171
 172                         opt_recv->dccpor_timestamp_echo = ntohl(*(__be32 *)value);
 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
 182                         if (len == 4) {
 183                                 dccp_pr_debug_cat("\n");
 184                                 break;
 185                         }
 186
 187                         if (len == 6)
 188                                 elapsed_time = ntohs(*(__be16 *)(value + 4));
 189                         else
 190                                 elapsed_time = ntohl(*(__be32 *)(value + 4));
 191
 192                         dccp_pr_debug_cat(", ELAPSED_TIME=%d\n", elapsed_time);
 193
 194                         /* Give precedence to the biggest ELAPSED_TIME */
 195                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 196                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 197                         break;
 198                 case DCCPO_ELAPSED_TIME:
 199                         if (len != 2 && len != 4)
 200                                 goto out_invalid_option;
 201
 202                         if (pkt_type == DCCP_PKT_DATA)
 203                                 continue;
 204
 205                         if (len == 2)
 206                                 elapsed_time = ntohs(*(__be16 *)value);
 207                         else
 208                                 elapsed_time = ntohl(*(__be32 *)value);
 209
 210                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 211                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 212
 213                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 214                                       dccp_role(sk), elapsed_time);
 215                         break;
 216                         /*
 217                          * From RFC 4340, sec. 10.3:
 218                          *
 219                          *      Option numbers 128 through 191 are for
 220                          *      options sent from the HC-Sender to the
 221                          *      HC-Receiver; option numbers 192 through 255
 222                          *      are for options sent from the HC-Receiver to
 223                          *      the HC-Sender.
 224                          */
 225                 case 128 ... 191: {
 226                         const u16 idx = value - options;
 227
 228                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 229                                                      opt, len, idx,
 230                                                      value) != 0)
 231                                 goto out_invalid_option;
 232                 }
 233                         break;
 234                 case 192 ... 255: {
 235                         const u16 idx = value - options;
 236
 237                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 238                                                      opt, len, idx,
 239                                                      value) != 0)
 240                                 goto out_invalid_option;
 241                 }
 242                         break;
 243                 default:
 244                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 245                                   "implemented, ignoring", sk, opt, len);
 246                         break;
 247                 }
 248
 249                 if (opt != DCCPO_MANDATORY)
 250                         mandatory = 0;
 251         }
 252
 253         /* mandatory was the last byte in option list -> reset connection */
 254         if (mandatory)
 255                 goto out_invalid_option;
 256
 257         return 0;
 258
 259 out_invalid_option:
 260         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 261         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 262         DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
 263         return -1;
 264 }
 265
 266 EXPORT_SYMBOL_GPL(dccp_parse_options);
 267
 268 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 269                                   const unsigned int len)
 270 {
 271         if (len > 3)
 272                 *to++ = (value & 0xFF000000) >> 24;
 273         if (len > 2)
 274                 *to++ = (value & 0xFF0000) >> 16;
 275         if (len > 1)
 276                 *to++ = (value & 0xFF00) >> 8;
 277         if (len > 0)
 278                 *to++ = (value & 0xFF);
 279 }
 280
 281 static inline int dccp_ndp_len(const int ndp)
 282 {
 283         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 284 }
 285
 286 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 287                         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         int 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 sock *sk, struct sk_buff *skb,
 342                                     u32 elapsed_time)
 343 {
 344         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 345         const int len = 2 + elapsed_time_len;
 346         unsigned char *to;
 347
 348         if (elapsed_time_len == 0)
 349                 return 0;
 350
 351         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 352                 return -1;
 353
 354         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 355
 356         to    = skb_push(skb, len);
 357         *to++ = DCCPO_ELAPSED_TIME;
 358         *to++ = len;
 359
 360         if (elapsed_time_len == 2) {
 361                 const __be16 var16 = htons((u16)elapsed_time);
 362                 memcpy(to, &var16, 2);
 363         } else {
 364                 const __be32 var32 = htonl(elapsed_time);
 365                 memcpy(to, &var32, 4);
 366         }
 367
 368         return 0;
 369 }
 370
 371 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 372
 373 void dccp_timestamp(const struct sock *sk, struct timeval *tv)
 374 {
 375         const struct dccp_sock *dp = dccp_sk(sk);
 376
 377         do_gettimeofday(tv);
 378         tv->tv_sec  -= dp->dccps_epoch.tv_sec;
 379         tv->tv_usec -= dp->dccps_epoch.tv_usec;
 380
 381         while (tv->tv_usec < 0) {
 382                 tv->tv_sec--;
 383                 tv->tv_usec += USEC_PER_SEC;
 384         }
 385 }
 386
 387 EXPORT_SYMBOL_GPL(dccp_timestamp);
 388
 389 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 390 {
 391         struct timeval tv;
 392         __be32 now;
 393
 394         dccp_timestamp(sk, &tv);
 395         now = htonl(timeval_usecs(&tv) / 10);
 396         /* yes this will overflow but that is the point as we want a
 397          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 398
 399         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 400 }
 401
 402 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 403
 404 static int dccp_insert_option_timestamp_echo(struct sock *sk,
 405                                              struct sk_buff *skb)
 406 {
 407         struct dccp_sock *dp = dccp_sk(sk);
 408         struct timeval now;
 409         __be32 tstamp_echo;
 410         u32 elapsed_time;
 411         int len, elapsed_time_len;
 412         unsigned char *to;
 413
 414         dccp_timestamp(sk, &now);
 415         elapsed_time = timeval_delta(&now, &dp->dccps_timestamp_time) / 10;
 416         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 417         len = 6 + elapsed_time_len;
 418
 419         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 420                 return -1;
 421
 422         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 423
 424         to    = skb_push(skb, len);
 425         *to++ = DCCPO_TIMESTAMP_ECHO;
 426         *to++ = len;
 427
 428         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 429         memcpy(to, &tstamp_echo, 4);
 430         to += 4;
 431
 432         if (elapsed_time_len == 2) {
 433                 const __be16 var16 = htons((u16)elapsed_time);
 434                 memcpy(to, &var16, 2);
 435         } else if (elapsed_time_len == 4) {
 436                 const __be32 var32 = htonl(elapsed_time);
 437                 memcpy(to, &var32, 4);
 438         }
 439
 440         dp->dccps_timestamp_echo = 0;
 441         dp->dccps_timestamp_time.tv_sec = 0;
 442         dp->dccps_timestamp_time.tv_usec = 0;
 443         return 0;
 444 }
 445
 446 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 447                                 u8 *val, u8 len)
 448 {
 449         u8 *to;
 450
 451         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 452                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 453                 return -1;
 454         }
 455
 456         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 457
 458         to    = skb_push(skb, len + 3);
 459         *to++ = type;
 460         *to++ = len + 3;
 461         *to++ = feat;
 462
 463         if (len)
 464                 memcpy(to, val, len);
 465
 466         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 467                       dccp_feat_typename(type),
 468                       dccp_feat_name(feat), feat, len);
 469         return 0;
 470 }
 471
 472 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 473 {
 474         struct dccp_sock *dp = dccp_sk(sk);
 475         struct dccp_minisock *dmsk = dccp_msk(sk);
 476         struct dccp_opt_pend *opt, *next;
 477         int change = 0;
 478
 479         /* confirm any options [NN opts] */
 480         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 481                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 482                                      opt->dccpop_feat, opt->dccpop_val,
 483                                      opt->dccpop_len);
 484                 /* fear empty confirms */
 485                 if (opt->dccpop_val)
 486                         kfree(opt->dccpop_val);
 487                 kfree(opt);
 488         }
 489         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 490
 491         /* see which features we need to send */
 492         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 493                 /* see if we need to send any confirm */
 494                 if (opt->dccpop_sc) {
 495                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 496                                              opt->dccpop_feat,
 497                                              opt->dccpop_sc->dccpoc_val,
 498                                              opt->dccpop_sc->dccpoc_len);
 499
 500                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 501                         kfree(opt->dccpop_sc->dccpoc_val);
 502                         kfree(opt->dccpop_sc);
 503                         opt->dccpop_sc = NULL;
 504                 }
 505
 506                 /* any option not confirmed, re-send it */
 507                 if (!opt->dccpop_conf) {
 508                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 509                                              opt->dccpop_feat, opt->dccpop_val,
 510                                              opt->dccpop_len);
 511                         change++;
 512                 }
 513         }
 514
 515         /* Retransmit timer.
 516          * If this is the master listening sock, we don't set a timer on it.  It
 517          * should be fine because if the dude doesn't receive our RESPONSE
 518          * [which will contain the CHANGE] he will send another REQUEST which
 519          * will "retrnasmit" the change.
 520          */
 521         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 522                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 523
 524                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 525                  * only when sending new stuff i guess.  Currently the timer
 526                  * never backs off because on re-transmission it just resets it!
 527                  */
 528                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 529                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 530         }
 531
 532         return 0;
 533 }
 534
 535 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 536 {
 537         struct dccp_sock *dp = dccp_sk(sk);
 538         struct dccp_minisock *dmsk = dccp_msk(sk);
 539
 540         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 541
 542         if (dmsk->dccpms_send_ndp_count &&
 543             dccp_insert_option_ndp(sk, skb))
 544                 return -1;
 545
 546         if (!dccp_packet_without_ack(skb)) {
 547                 if (dmsk->dccpms_send_ack_vector &&
 548                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 549                     dccp_insert_option_ackvec(sk, skb))
 550                         return -1;
 551
 552                 if (dp->dccps_timestamp_echo != 0 &&
 553                     dccp_insert_option_timestamp_echo(sk, skb))
 554                         return -1;
 555         }
 556
 557         if (dp->dccps_hc_rx_insert_options) {
 558                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 559                         return -1;
 560                 dp->dccps_hc_rx_insert_options = 0;
 561         }
 562
 563         /* Feature negotiation */
 564         /* Data packets can't do feat negotiation */
 565         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 566             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 567             dccp_insert_options_feat(sk, skb))
 568                 return -1;
 569
 570         /*
 571          * Obtain RTT sample from Request/Response exchange.
 572          * This is currently used in CCID 3 initialisation.
 573          */
 574         if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
 575             dccp_insert_option_timestamp(sk, skb))
 576                 return -1;
 577
 578         /* XXX: insert other options when appropriate */
 579
 580         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 581                 /* The length of all options has to be a multiple of 4 */
 582                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 583
 584                 if (padding != 0) {
 585                         padding = 4 - padding;
 586                         memset(skb_push(skb, padding), 0, padding);
 587                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 588                 }
 589         }
 590
 591         return 0;
 592 }