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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 dccp_feat_default_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
  26 int dccp_feat_default_rx_ccid         = DCCPF_INITIAL_CCID;
  27 int dccp_feat_default_tx_ccid         = DCCPF_INITIAL_CCID;
  28 int dccp_feat_default_ack_ratio       = DCCPF_INITIAL_ACK_RATIO;
  29 int dccp_feat_default_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  30 int dccp_feat_default_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  31
  32 EXPORT_SYMBOL_GPL(dccp_feat_default_sequence_window);
  33
  34 void dccp_minisock_init(struct dccp_minisock *dmsk)
  35 {
  36         dmsk->dccpms_sequence_window = dccp_feat_default_sequence_window;
  37         dmsk->dccpms_rx_ccid         = dccp_feat_default_rx_ccid;
  38         dmsk->dccpms_tx_ccid         = dccp_feat_default_tx_ccid;
  39         dmsk->dccpms_ack_ratio       = dccp_feat_default_ack_ratio;
  40         dmsk->dccpms_send_ack_vector = dccp_feat_default_send_ack_vector;
  41         dmsk->dccpms_send_ndp_count  = dccp_feat_default_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 #ifdef CONFIG_IP_DCCP_DEBUG
  64         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
  65                                         "CLIENT rx opt: " : "server rx opt: ";
  66 #endif
  67         const struct dccp_hdr *dh = dccp_hdr(skb);
  68         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  69         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  70         unsigned char *opt_ptr = options;
  71         const unsigned char *opt_end = (unsigned char *)dh +
  72                                         (dh->dccph_doff * 4);
  73         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  74         unsigned char opt, len;
  75         unsigned char *value;
  76         u32 elapsed_time;
  77         int rc;
  78         int mandatory = 0;
  79
  80         memset(opt_recv, 0, sizeof(*opt_recv));
  81
  82         opt = len = 0;
  83         while (opt_ptr != opt_end) {
  84                 opt   = *opt_ptr++;
  85                 len   = 0;
  86                 value = NULL;
  87
  88                 /* Check if this isn't a single byte option */
  89                 if (opt > DCCPO_MAX_RESERVED) {
  90                         if (opt_ptr == opt_end)
  91                                 goto out_invalid_option;
  92
  93                         len = *opt_ptr++;
  94                         if (len < 3)
  95                                 goto out_invalid_option;
  96                         /*
  97                          * Remove the type and len fields, leaving
  98                          * just the value size
  99                          */
 100                         len     -= 2;
 101                         value   = opt_ptr;
 102                         opt_ptr += len;
 103
 104                         if (opt_ptr > opt_end)
 105                                 goto out_invalid_option;
 106                 }
 107
 108                 switch (opt) {
 109                 case DCCPO_PADDING:
 110                         break;
 111                 case DCCPO_MANDATORY:
 112                         if (mandatory)
 113                                 goto out_invalid_option;
 114                         if (pkt_type != DCCP_PKT_DATA)
 115                                 mandatory = 1;
 116                         break;
 117                 case DCCPO_NDP_COUNT:
 118                         if (len > 3)
 119                                 goto out_invalid_option;
 120
 121                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 122                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
 123                                       opt_recv->dccpor_ndp);
 124                         break;
 125                 case DCCPO_CHANGE_L:
 126                         /* fall through */
 127                 case DCCPO_CHANGE_R:
 128                         if (len < 2)
 129                                 goto out_invalid_option;
 130                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 131                                                    len - 1);
 132                         /*
 133                          * When there is a change error, change_recv is
 134                          * responsible for dealing with it.  i.e. reply with an
 135                          * empty confirm.
 136                          * If the change was mandatory, then we need to die.
 137                          */
 138                         if (rc && mandatory)
 139                                 goto out_invalid_option;
 140                         break;
 141                 case DCCPO_CONFIRM_L:
 142                         /* fall through */
 143                 case DCCPO_CONFIRM_R:
 144                         if (len < 2)
 145                                 goto out_invalid_option;
 146                         if (dccp_feat_confirm_recv(sk, opt, *value,
 147                                                    value + 1, len - 1))
 148                                 goto out_invalid_option;
 149                         break;
 150                 case DCCPO_ACK_VECTOR_0:
 151                 case DCCPO_ACK_VECTOR_1:
 152                         if (pkt_type == DCCP_PKT_DATA)
 153                                 break;
 154
 155                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 156                             dccp_ackvec_parse(sk, skb, opt, value, len))
 157                                 goto out_invalid_option;
 158                         break;
 159                 case DCCPO_TIMESTAMP:
 160                         if (len != 4)
 161                                 goto out_invalid_option;
 162
 163                         opt_recv->dccpor_timestamp = ntohl(*(__be32 *)value);
 164
 165                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 166                         dccp_timestamp(sk, &dp->dccps_timestamp_time);
 167
 168                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
 169                                       debug_prefix, opt_recv->dccpor_timestamp,
 170                                       (unsigned long long)
 171                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 172                         break;
 173                 case DCCPO_TIMESTAMP_ECHO:
 174                         if (len != 4 && len != 6 && len != 8)
 175                                 goto out_invalid_option;
 176
 177                         opt_recv->dccpor_timestamp_echo = ntohl(*(__be32 *)value);
 178
 179                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, ",
 180                                       debug_prefix,
 181                                       opt_recv->dccpor_timestamp_echo,
 182                                       len + 2,
 183                                       (unsigned long long)
 184                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 185
 186
 187                         if (len == 4)
 188                                 break;
 189
 190                         if (len == 6)
 191                                 elapsed_time = ntohs(*(__be16 *)(value + 4));
 192                         else
 193                                 elapsed_time = ntohl(*(__be32 *)(value + 4));
 194
 195                         /* Give precedence to the biggest ELAPSED_TIME */
 196                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 197                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 198                         break;
 199                 case DCCPO_ELAPSED_TIME:
 200                         if (len != 2 && len != 4)
 201                                 goto out_invalid_option;
 202
 203                         if (pkt_type == DCCP_PKT_DATA)
 204                                 continue;
 205
 206                         if (len == 2)
 207                                 elapsed_time = ntohs(*(__be16 *)value);
 208                         else
 209                                 elapsed_time = ntohl(*(__be32 *)value);
 210
 211                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 212                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 213
 214                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
 215                                       elapsed_time);
 216                         break;
 217                         /*
 218                          * From draft-ietf-dccp-spec-11.txt:
 219                          *
 220                          *      Option numbers 128 through 191 are for
 221                          *      options sent from the HC-Sender to the
 222                          *      HC-Receiver; option numbers 192 through 255
 223                          *      are for options sent from the HC-Receiver to
 224                          *      the HC-Sender.
 225                          */
 226                 case 128 ... 191: {
 227                         const u16 idx = value - options;
 228
 229                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 230                                                      opt, len, idx,
 231                                                      value) != 0)
 232                                 goto out_invalid_option;
 233                 }
 234                         break;
 235                 case 192 ... 255: {
 236                         const u16 idx = value - options;
 237
 238                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 239                                                      opt, len, idx,
 240                                                      value) != 0)
 241                                 goto out_invalid_option;
 242                 }
 243                         break;
 244                 default:
 245                         pr_info("DCCP(%p): option %d(len=%d) not "
 246                                 "implemented, ignoring\n",
 247                                 sk, opt, len);
 248                         break;
 249                 }
 250
 251                 if (opt != DCCPO_MANDATORY)
 252                         mandatory = 0;
 253         }
 254
 255         /* mandatory was the last byte in option list -> reset connection */
 256         if (mandatory)
 257                 goto out_invalid_option;
 258
 259         return 0;
 260
 261 out_invalid_option:
 262         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 263         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 264         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
 265         return -1;
 266 }
 267
 268 EXPORT_SYMBOL_GPL(dccp_parse_options);
 269
 270 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 271                                   const unsigned int len)
 272 {
 273         if (len > 3)
 274                 *to++ = (value & 0xFF000000) >> 24;
 275         if (len > 2)
 276                 *to++ = (value & 0xFF0000) >> 16;
 277         if (len > 1)
 278                 *to++ = (value & 0xFF00) >> 8;
 279         if (len > 0)
 280                 *to++ = (value & 0xFF);
 281 }
 282
 283 static inline int dccp_ndp_len(const int ndp)
 284 {
 285         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 286 }
 287
 288 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 289                         const unsigned char option,
 290                         const void *value, const unsigned char len)
 291 {
 292         unsigned char *to;
 293
 294         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 295                 return -1;
 296
 297         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 298
 299         to    = skb_push(skb, len + 2);
 300         *to++ = option;
 301         *to++ = len + 2;
 302
 303         memcpy(to, value, len);
 304         return 0;
 305 }
 306
 307 EXPORT_SYMBOL_GPL(dccp_insert_option);
 308
 309 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 310 {
 311         struct dccp_sock *dp = dccp_sk(sk);
 312         int ndp = dp->dccps_ndp_count;
 313
 314         if (dccp_non_data_packet(skb))
 315                 ++dp->dccps_ndp_count;
 316         else
 317                 dp->dccps_ndp_count = 0;
 318
 319         if (ndp > 0) {
 320                 unsigned char *ptr;
 321                 const int ndp_len = dccp_ndp_len(ndp);
 322                 const int len = ndp_len + 2;
 323
 324                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 325                         return -1;
 326
 327                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 328
 329                 ptr = skb_push(skb, len);
 330                 *ptr++ = DCCPO_NDP_COUNT;
 331                 *ptr++ = len;
 332                 dccp_encode_value_var(ndp, ptr, ndp_len);
 333         }
 334
 335         return 0;
 336 }
 337
 338 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 339 {
 340         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 341 }
 342
 343 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
 344                                     u32 elapsed_time)
 345 {
 346         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 347         const int len = 2 + elapsed_time_len;
 348         unsigned char *to;
 349
 350         if (elapsed_time_len == 0)
 351                 return 0;
 352
 353         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 354                 return -1;
 355
 356         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 357
 358         to    = skb_push(skb, len);
 359         *to++ = DCCPO_ELAPSED_TIME;
 360         *to++ = len;
 361
 362         if (elapsed_time_len == 2) {
 363                 const __be16 var16 = htons((u16)elapsed_time);
 364                 memcpy(to, &var16, 2);
 365         } else {
 366                 const __be32 var32 = htonl(elapsed_time);
 367                 memcpy(to, &var32, 4);
 368         }
 369
 370         return 0;
 371 }
 372
 373 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 374
 375 void dccp_timestamp(const struct sock *sk, struct timeval *tv)
 376 {
 377         const struct dccp_sock *dp = dccp_sk(sk);
 378
 379         do_gettimeofday(tv);
 380         tv->tv_sec  -= dp->dccps_epoch.tv_sec;
 381         tv->tv_usec -= dp->dccps_epoch.tv_usec;
 382
 383         while (tv->tv_usec < 0) {
 384                 tv->tv_sec--;
 385                 tv->tv_usec += USEC_PER_SEC;
 386         }
 387 }
 388
 389 EXPORT_SYMBOL_GPL(dccp_timestamp);
 390
 391 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 392 {
 393         struct timeval tv;
 394         __be32 now;
 395
 396         dccp_timestamp(sk, &tv);
 397         now = htonl(timeval_usecs(&tv) / 10);
 398         /* yes this will overflow but that is the point as we want a
 399          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 400
 401         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 402 }
 403
 404 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 405
 406 static int dccp_insert_option_timestamp_echo(struct sock *sk,
 407                                              struct sk_buff *skb)
 408 {
 409         struct dccp_sock *dp = dccp_sk(sk);
 410         struct timeval now;
 411         __be32 tstamp_echo;
 412         u32 elapsed_time;
 413         int len, elapsed_time_len;
 414         unsigned char *to;
 415
 416         dccp_timestamp(sk, &now);
 417         elapsed_time = timeval_delta(&now, &dp->dccps_timestamp_time) / 10;
 418         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 419         len = 6 + elapsed_time_len;
 420
 421         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 422                 return -1;
 423
 424         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 425
 426         to    = skb_push(skb, len);
 427         *to++ = DCCPO_TIMESTAMP_ECHO;
 428         *to++ = len;
 429
 430         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 431         memcpy(to, &tstamp_echo, 4);
 432         to += 4;
 433
 434         if (elapsed_time_len == 2) {
 435                 const __be16 var16 = htons((u16)elapsed_time);
 436                 memcpy(to, &var16, 2);
 437         } else if (elapsed_time_len == 4) {
 438                 const __be32 var32 = htonl(elapsed_time);
 439                 memcpy(to, &var32, 4);
 440         }
 441
 442         dp->dccps_timestamp_echo = 0;
 443         dp->dccps_timestamp_time.tv_sec = 0;
 444         dp->dccps_timestamp_time.tv_usec = 0;
 445         return 0;
 446 }
 447
 448 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 449                                 u8 *val, u8 len)
 450 {
 451         u8 *to;
 452
 453         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 454                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small"
 455                                " to insert feature %d option!\n", feat);
 456                 return -1;
 457         }
 458
 459         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 460
 461         to    = skb_push(skb, len + 3);
 462         *to++ = type;
 463         *to++ = len + 3;
 464         *to++ = feat;
 465
 466         if (len)
 467                 memcpy(to, val, len);
 468         dccp_pr_debug("option %d feat %d len %d\n", type, feat, len);
 469
 470         return 0;
 471 }
 472
 473 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 474 {
 475         struct dccp_sock *dp = dccp_sk(sk);
 476         struct dccp_minisock *dmsk = dccp_msk(sk);
 477         struct dccp_opt_pend *opt, *next;
 478         int change = 0;
 479
 480         /* confirm any options [NN opts] */
 481         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 482                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 483                                      opt->dccpop_feat, opt->dccpop_val,
 484                                      opt->dccpop_len);
 485                 /* fear empty confirms */
 486                 if (opt->dccpop_val)
 487                         kfree(opt->dccpop_val);
 488                 kfree(opt);
 489         }
 490         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 491
 492         /* see which features we need to send */
 493         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 494                 /* see if we need to send any confirm */
 495                 if (opt->dccpop_sc) {
 496                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 497                                              opt->dccpop_feat,
 498                                              opt->dccpop_sc->dccpoc_val,
 499                                              opt->dccpop_sc->dccpoc_len);
 500
 501                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 502                         kfree(opt->dccpop_sc->dccpoc_val);
 503                         kfree(opt->dccpop_sc);
 504                         opt->dccpop_sc = NULL;
 505                 }
 506
 507                 /* any option not confirmed, re-send it */
 508                 if (!opt->dccpop_conf) {
 509                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 510                                              opt->dccpop_feat, opt->dccpop_val,
 511                                              opt->dccpop_len);
 512                         change++;
 513                 }
 514         }
 515
 516         /* Retransmit timer.
 517          * If this is the master listening sock, we don't set a timer on it.  It
 518          * should be fine because if the dude doesn't receive our RESPONSE
 519          * [which will contain the CHANGE] he will send another REQUEST which
 520          * will "retrnasmit" the change.
 521          */
 522         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 523                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 524
 525                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 526                  * only when sending new stuff i guess.  Currently the timer
 527                  * never backs off because on re-transmission it just resets it!
 528                  */
 529                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 530                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 531         }
 532
 533         return 0;
 534 }
 535
 536 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 537 {
 538         struct dccp_sock *dp = dccp_sk(sk);
 539         struct dccp_minisock *dmsk = dccp_msk(sk);
 540
 541         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 542
 543         if (dmsk->dccpms_send_ndp_count &&
 544             dccp_insert_option_ndp(sk, skb))
 545                 return -1;
 546
 547         if (!dccp_packet_without_ack(skb)) {
 548                 if (dmsk->dccpms_send_ack_vector &&
 549                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 550                     dccp_insert_option_ackvec(sk, skb))
 551                         return -1;
 552
 553                 if (dp->dccps_timestamp_echo != 0 &&
 554                     dccp_insert_option_timestamp_echo(sk, skb))
 555                         return -1;
 556         }
 557
 558         if (dp->dccps_hc_rx_insert_options) {
 559                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 560                         return -1;
 561                 dp->dccps_hc_rx_insert_options = 0;
 562         }
 563         if (dp->dccps_hc_tx_insert_options) {
 564                 if (ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb))
 565                         return -1;
 566                 dp->dccps_hc_tx_insert_options = 0;
 567         }
 568
 569         /* Feature negotiation */
 570         /* Data packets can't do feat negotiation */
 571         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 572             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 573             dccp_insert_options_feat(sk, skb))
 574                 return -1;
 575
 576         /* XXX: insert other options when appropriate */
 577
 578         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 579                 /* The length of all options has to be a multiple of 4 */
 580                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 581
 582                 if (padding != 0) {
 583                         padding = 4 - padding;
 584                         memset(skb_push(skb, padding), 0, padding);
 585                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 586                 }
 587         }
 588
 589         return 0;
 590 }