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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 <asm/unaligned.h>
  18 #include <linux/kernel.h>
  19 #include <linux/skbuff.h>
  20
  21 #include "ackvec.h"
  22 #include "ccid.h"
  23 #include "dccp.h"
  24 #include "feat.h"
  25
  26 int sysctl_dccp_feat_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
  27 int sysctl_dccp_feat_rx_ccid          = DCCPF_INITIAL_CCID;
  28 int sysctl_dccp_feat_tx_ccid          = DCCPF_INITIAL_CCID;
  29 int sysctl_dccp_feat_ack_ratio        = DCCPF_INITIAL_ACK_RATIO;
  30 int sysctl_dccp_feat_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  31 int sysctl_dccp_feat_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  32
  33 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  34 {
  35         u32 value = 0;
  36
  37         if (len > 3)
  38                 value += *bf++ << 24;
  39         if (len > 2)
  40                 value += *bf++ << 16;
  41         if (len > 1)
  42                 value += *bf++ << 8;
  43         if (len > 0)
  44                 value += *bf;
  45
  46         return value;
  47 }
  48
  49 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
  50 {
  51         struct dccp_sock *dp = dccp_sk(sk);
  52         const struct dccp_hdr *dh = dccp_hdr(skb);
  53         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  54         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
  55         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  56         unsigned char *opt_ptr = options;
  57         const unsigned char *opt_end = (unsigned char *)dh +
  58                                         (dh->dccph_doff * 4);
  59         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  60         unsigned char opt, len;
  61         unsigned char *value;
  62         u32 elapsed_time;
  63         __be32 opt_val;
  64         int rc;
  65         int mandatory = 0;
  66
  67         memset(opt_recv, 0, sizeof(*opt_recv));
  68
  69         opt = len = 0;
  70         while (opt_ptr != opt_end) {
  71                 opt   = *opt_ptr++;
  72                 len   = 0;
  73                 value = NULL;
  74
  75                 /* Check if this isn't a single byte option */
  76                 if (opt > DCCPO_MAX_RESERVED) {
  77                         if (opt_ptr == opt_end)
  78                                 goto out_invalid_option;
  79
  80                         len = *opt_ptr++;
  81                         if (len < 3)
  82                                 goto out_invalid_option;
  83                         /*
  84                          * Remove the type and len fields, leaving
  85                          * just the value size
  86                          */
  87                         len     -= 2;
  88                         value   = opt_ptr;
  89                         opt_ptr += len;
  90
  91                         if (opt_ptr > opt_end)
  92                                 goto out_invalid_option;
  93                 }
  94
  95                 switch (opt) {
  96                 case DCCPO_PADDING:
  97                         break;
  98                 case DCCPO_MANDATORY:
  99                         if (mandatory)
 100                                 goto out_invalid_option;
 101                         if (pkt_type != DCCP_PKT_DATA)
 102                                 mandatory = 1;
 103                         break;
 104                 case DCCPO_NDP_COUNT:
 105                         if (len > 3)
 106                                 goto out_invalid_option;
 107
 108                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 109                         dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
 110                                       opt_recv->dccpor_ndp);
 111                         break;
 112                 case DCCPO_CHANGE_L:
 113                         /* fall through */
 114                 case DCCPO_CHANGE_R:
 115                         if (len < 2)
 116                                 goto out_invalid_option;
 117                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 118                                                    len - 1);
 119                         /*
 120                          * When there is a change error, change_recv is
 121                          * responsible for dealing with it.  i.e. reply with an
 122                          * empty confirm.
 123                          * If the change was mandatory, then we need to die.
 124                          */
 125                         if (rc && mandatory)
 126                                 goto out_invalid_option;
 127                         break;
 128                 case DCCPO_CONFIRM_L:
 129                         /* fall through */
 130                 case DCCPO_CONFIRM_R:
 131                         if (len < 2)
 132                                 goto out_invalid_option;
 133                         if (dccp_feat_confirm_recv(sk, opt, *value,
 134                                                    value + 1, len - 1))
 135                                 goto out_invalid_option;
 136                         break;
 137                 case DCCPO_ACK_VECTOR_0:
 138                 case DCCPO_ACK_VECTOR_1:
 139                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 140                                 break;
 141
 142                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 143                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 144                                 goto out_invalid_option;
 145                         break;
 146                 case DCCPO_TIMESTAMP:
 147                         if (len != 4)
 148                                 goto out_invalid_option;
 149
 150                         opt_val = get_unaligned((__be32 *)value);
 151                         opt_recv->dccpor_timestamp = ntohl(opt_val);
 152
 153                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 154                         dp->dccps_timestamp_time = ktime_get_real();
 155
 156                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 157                                       dccp_role(sk), opt_recv->dccpor_timestamp,
 158                                       (unsigned long long)
 159                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 160                         break;
 161                 case DCCPO_TIMESTAMP_ECHO:
 162                         if (len != 4 && len != 6 && len != 8)
 163                                 goto out_invalid_option;
 164
 165                         opt_val = get_unaligned((__be32 *)value);
 166                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 167
 168                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 169                                       "ackno=%llu", dccp_role(sk),
 170                                       opt_recv->dccpor_timestamp_echo,
 171                                       len + 2,
 172                                       (unsigned long long)
 173                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 174
 175                         value += 4;
 176
 177                         if (len == 4) {         /* no elapsed time included */
 178                                 dccp_pr_debug_cat("\n");
 179                                 break;
 180                         }
 181
 182                         if (len == 6) {         /* 2-byte elapsed time */
 183                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 184                                 elapsed_time = ntohs(opt_val2);
 185                         } else {                /* 4-byte elapsed time */
 186                                 opt_val = get_unaligned((__be32 *)value);
 187                                 elapsed_time = ntohl(opt_val);
 188                         }
 189
 190                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 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 (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 198                                 break;
 199
 200                         if (len == 2) {
 201                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 202                                 elapsed_time = ntohs(opt_val2);
 203                         } else if (len == 4) {
 204                                 opt_val = get_unaligned((__be32 *)value);
 205                                 elapsed_time = ntohl(opt_val);
 206                         } else {
 207                                 goto out_invalid_option;
 208                         }
 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 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 374 {
 375         __be32 now = htonl(dccp_timestamp());
 376         /* yes this will overflow but that is the point as we want a
 377          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 378
 379         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 380 }
 381
 382 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 383
 384 static int dccp_insert_option_timestamp_echo(struct sock *sk,
 385                                              struct sk_buff *skb)
 386 {
 387         struct dccp_sock *dp = dccp_sk(sk);
 388         __be32 tstamp_echo;
 389         int len, elapsed_time_len;
 390         unsigned char *to;
 391         const suseconds_t delta = ktime_us_delta(ktime_get_real(),
 392                                                  dp->dccps_timestamp_time);
 393         u32 elapsed_time = delta / 10;
 394         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 395         len = 6 + elapsed_time_len;
 396
 397         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 398                 return -1;
 399
 400         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 401
 402         to    = skb_push(skb, len);
 403         *to++ = DCCPO_TIMESTAMP_ECHO;
 404         *to++ = len;
 405
 406         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 407         memcpy(to, &tstamp_echo, 4);
 408         to += 4;
 409
 410         if (elapsed_time_len == 2) {
 411                 const __be16 var16 = htons((u16)elapsed_time);
 412                 memcpy(to, &var16, 2);
 413         } else if (elapsed_time_len == 4) {
 414                 const __be32 var32 = htonl(elapsed_time);
 415                 memcpy(to, &var32, 4);
 416         }
 417
 418         dp->dccps_timestamp_echo = 0;
 419         dp->dccps_timestamp_time = ktime_set(0, 0);
 420         return 0;
 421 }
 422
 423 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 424                                 u8 *val, u8 len)
 425 {
 426         u8 *to;
 427
 428         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 429                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 430                 return -1;
 431         }
 432
 433         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 434
 435         to    = skb_push(skb, len + 3);
 436         *to++ = type;
 437         *to++ = len + 3;
 438         *to++ = feat;
 439
 440         if (len)
 441                 memcpy(to, val, len);
 442
 443         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 444                       dccp_feat_typename(type),
 445                       dccp_feat_name(feat), feat, len);
 446         return 0;
 447 }
 448
 449 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 450 {
 451         struct dccp_sock *dp = dccp_sk(sk);
 452         struct dccp_minisock *dmsk = dccp_msk(sk);
 453         struct dccp_opt_pend *opt, *next;
 454         int change = 0;
 455
 456         /* confirm any options [NN opts] */
 457         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 458                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 459                                      opt->dccpop_feat, opt->dccpop_val,
 460                                      opt->dccpop_len);
 461                 /* fear empty confirms */
 462                 if (opt->dccpop_val)
 463                         kfree(opt->dccpop_val);
 464                 kfree(opt);
 465         }
 466         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 467
 468         /* see which features we need to send */
 469         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 470                 /* see if we need to send any confirm */
 471                 if (opt->dccpop_sc) {
 472                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 473                                              opt->dccpop_feat,
 474                                              opt->dccpop_sc->dccpoc_val,
 475                                              opt->dccpop_sc->dccpoc_len);
 476
 477                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 478                         kfree(opt->dccpop_sc->dccpoc_val);
 479                         kfree(opt->dccpop_sc);
 480                         opt->dccpop_sc = NULL;
 481                 }
 482
 483                 /* any option not confirmed, re-send it */
 484                 if (!opt->dccpop_conf) {
 485                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 486                                              opt->dccpop_feat, opt->dccpop_val,
 487                                              opt->dccpop_len);
 488                         change++;
 489                 }
 490         }
 491
 492         /* Retransmit timer.
 493          * If this is the master listening sock, we don't set a timer on it.  It
 494          * should be fine because if the dude doesn't receive our RESPONSE
 495          * [which will contain the CHANGE] he will send another REQUEST which
 496          * will "retrnasmit" the change.
 497          */
 498         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 499                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 500
 501                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 502                  * only when sending new stuff i guess.  Currently the timer
 503                  * never backs off because on re-transmission it just resets it!
 504                  */
 505                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 506                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 507         }
 508
 509         return 0;
 510 }
 511
 512 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 513 {
 514         struct dccp_sock *dp = dccp_sk(sk);
 515         struct dccp_minisock *dmsk = dccp_msk(sk);
 516
 517         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 518
 519         if (dmsk->dccpms_send_ndp_count &&
 520             dccp_insert_option_ndp(sk, skb))
 521                 return -1;
 522
 523         if (!dccp_packet_without_ack(skb)) {
 524                 if (dmsk->dccpms_send_ack_vector &&
 525                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 526                     dccp_insert_option_ackvec(sk, skb))
 527                         return -1;
 528
 529                 if (dp->dccps_timestamp_echo != 0 &&
 530                     dccp_insert_option_timestamp_echo(sk, skb))
 531                         return -1;
 532         }
 533
 534         if (dp->dccps_hc_rx_insert_options) {
 535                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 536                         return -1;
 537                 dp->dccps_hc_rx_insert_options = 0;
 538         }
 539
 540         /* Feature negotiation */
 541         /* Data packets can't do feat negotiation */
 542         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 543             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 544             dccp_insert_options_feat(sk, skb))
 545                 return -1;
 546
 547         /*
 548          * Obtain RTT sample from Request/Response exchange.
 549          * This is currently used in CCID 3 initialisation.
 550          */
 551         if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
 552             dccp_insert_option_timestamp(sk, skb))
 553                 return -1;
 554
 555         /* XXX: insert other options when appropriate */
 556
 557         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 558                 /* The length of all options has to be a multiple of 4 */
 559                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 560
 561                 if (padding != 0) {
 562                         padding = 4 - padding;
 563                         memset(skb_push(skb, padding), 0, padding);
 564                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 565                 }
 566         }
 567
 568         return 0;
 569 }