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