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