net/dccp/options.c

   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 /**
  50  * dccp_parse_options  -  Parse DCCP options present in @skb
  51  * @sk: client|server|listening dccp socket (when @dreq != NULL)
  52  * @dreq: request socket to use during connection setup, or NULL
  53  */
  54 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
  55                        struct sk_buff *skb)
  56 {
  57         struct dccp_sock *dp = dccp_sk(sk);
  58         const struct dccp_hdr *dh = dccp_hdr(skb);
  59         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  60         u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq;
  61         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  62         unsigned char *opt_ptr = options;
  63         const unsigned char *opt_end = (unsigned char *)dh +
  64                                         (dh->dccph_doff * 4);
  65         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  66         unsigned char opt, len;
  67         unsigned char *value;
  68         u32 elapsed_time;
  69         __be32 opt_val;
  70         int rc;
  71         int mandatory = 0;
  72
  73         memset(opt_recv, 0, sizeof(*opt_recv));
  74
  75         opt = len = 0;
  76         while (opt_ptr != opt_end) {
  77                 opt   = *opt_ptr++;
  78                 len   = 0;
  79                 value = NULL;
  80
  81                 /* Check if this isn't a single byte option */
  82                 if (opt > DCCPO_MAX_RESERVED) {
  83                         if (opt_ptr == opt_end)
  84                                 goto out_invalid_option;
  85
  86                         len = *opt_ptr++;
  87                         if (len < 3)
  88                                 goto out_invalid_option;
  89                         /*
  90                          * Remove the type and len fields, leaving
  91                          * just the value size
  92                          */
  93                         len     -= 2;
  94                         value   = opt_ptr;
  95                         opt_ptr += len;
  96
  97                         if (opt_ptr > opt_end)
  98                                 goto out_invalid_option;
  99                 }
 100
 101                 /*
 102                  * CCID-Specific Options (from RFC 4340, sec. 10.3):
 103                  *
 104                  * Option numbers 128 through 191 are for options sent from the
 105                  * HC-Sender to the HC-Receiver; option numbers 192 through 255
 106                  * are for options sent from the HC-Receiver to the HC-Sender.
 107                  *
 108                  * CCID-specific options are ignored during connection setup, as
 109                  * negotiation may still be in progress (see RFC 4340, 10.3).
 110                  *
 111                  */
 112                 if (dreq != NULL && opt >= 128)
 113                         goto ignore_option;
 114
 115                 switch (opt) {
 116                 case DCCPO_PADDING:
 117                         break;
 118                 case DCCPO_MANDATORY:
 119                         if (mandatory)
 120                                 goto out_invalid_option;
 121                         if (pkt_type != DCCP_PKT_DATA)
 122                                 mandatory = 1;
 123                         break;
 124                 case DCCPO_NDP_COUNT:
 125                         if (len > 3)
 126                                 goto out_invalid_option;
 127
 128                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 129                         dccp_pr_debug("%s rx opt: NDP count=%d\n", dccp_role(sk),
 130                                       opt_recv->dccpor_ndp);
 131                         break;
 132                 case DCCPO_CHANGE_L:
 133                         /* fall through */
 134                 case DCCPO_CHANGE_R:
 135                         if (len < 2)
 136                                 goto out_invalid_option;
 137                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 138                                                    len - 1);
 139                         /*
 140                          * When there is a change error, change_recv is
 141                          * responsible for dealing with it.  i.e. reply with an
 142                          * empty confirm.
 143                          * If the change was mandatory, then we need to die.
 144                          */
 145                         if (rc && mandatory)
 146                                 goto out_invalid_option;
 147                         break;
 148                 case DCCPO_CONFIRM_L:
 149                         /* fall through */
 150                 case DCCPO_CONFIRM_R:
 151                         if (len < 2)
 152                                 goto out_invalid_option;
 153                         if (dccp_feat_confirm_recv(sk, opt, *value,
 154                                                    value + 1, len - 1))
 155                                 goto out_invalid_option;
 156                         break;
 157                 case DCCPO_ACK_VECTOR_0:
 158                 case DCCPO_ACK_VECTOR_1:
 159                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 11.4 */
 160                                 break;
 161
 162                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 163                             dccp_ackvec_parse(sk, skb, &ackno, opt, value, len))
 164                                 goto out_invalid_option;
 165                         break;
 166                 case DCCPO_TIMESTAMP:
 167                         if (len != 4)
 168                                 goto out_invalid_option;
 169
 170                         opt_val = get_unaligned((__be32 *)value);
 171                         opt_recv->dccpor_timestamp = ntohl(opt_val);
 172
 173                         /* FIXME: if dreq != NULL, don't store this on listening socket */
 174                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 175                         dp->dccps_timestamp_time = ktime_get_real();
 176
 177                         dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n",
 178                                       dccp_role(sk), opt_recv->dccpor_timestamp,
 179                                       (unsigned long long)
 180                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 181                         break;
 182                 case DCCPO_TIMESTAMP_ECHO:
 183                         if (len != 4 && len != 6 && len != 8)
 184                                 goto out_invalid_option;
 185
 186                         opt_val = get_unaligned((__be32 *)value);
 187                         opt_recv->dccpor_timestamp_echo = ntohl(opt_val);
 188
 189                         dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, "
 190                                       "ackno=%llu", dccp_role(sk),
 191                                       opt_recv->dccpor_timestamp_echo,
 192                                       len + 2,
 193                                       (unsigned long long)
 194                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 195
 196                         value += 4;
 197
 198                         if (len == 4) {         /* no elapsed time included */
 199                                 dccp_pr_debug_cat("\n");
 200                                 break;
 201                         }
 202
 203                         if (len == 6) {         /* 2-byte elapsed time */
 204                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 205                                 elapsed_time = ntohs(opt_val2);
 206                         } else {                /* 4-byte elapsed time */
 207                                 opt_val = get_unaligned((__be32 *)value);
 208                                 elapsed_time = ntohl(opt_val);
 209                         }
 210
 211                         dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time);
 212
 213                         /* Give precedence to the biggest ELAPSED_TIME */
 214                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 215                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 216                         break;
 217                 case DCCPO_ELAPSED_TIME:
 218                         if (dccp_packet_without_ack(skb))   /* RFC 4340, 13.2 */
 219                                 break;
 220
 221                         if (len == 2) {
 222                                 __be16 opt_val2 = get_unaligned((__be16 *)value);
 223                                 elapsed_time = ntohs(opt_val2);
 224                         } else if (len == 4) {
 225                                 opt_val = get_unaligned((__be32 *)value);
 226                                 elapsed_time = ntohl(opt_val);
 227                         } else {
 228                                 goto out_invalid_option;
 229                         }
 230
 231                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 232                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 233
 234                         dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n",
 235                                       dccp_role(sk), elapsed_time);
 236                         break;
 237                 case 128 ... 191: {
 238                         const u16 idx = value - options;
 239
 240                         if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk,
 241                                                      opt, len, idx,
 242                                                      value) != 0)
 243                                 goto out_invalid_option;
 244                 }
 245                         break;
 246                 case 192 ... 255: {
 247                         const u16 idx = value - options;
 248
 249                         if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk,
 250                                                      opt, len, idx,
 251                                                      value) != 0)
 252                                 goto out_invalid_option;
 253                 }
 254                         break;
 255                 default:
 256                         DCCP_CRIT("DCCP(%p): option %d(len=%d) not "
 257                                   "implemented, ignoring", sk, opt, len);
 258                         break;
 259                 }
 260 ignore_option:
 261                 if (opt != DCCPO_MANDATORY)
 262                         mandatory = 0;
 263         }
 264
 265         /* mandatory was the last byte in option list -> reset connection */
 266         if (mandatory)
 267                 goto out_invalid_option;
 268
 269         return 0;
 270
 271 out_invalid_option:
 272         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 273         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 274         DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len);
 275         return -1;
 276 }
 277
 278 EXPORT_SYMBOL_GPL(dccp_parse_options);
 279
 280 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 281                                   const unsigned int len)
 282 {
 283         if (len > 3)
 284                 *to++ = (value & 0xFF000000) >> 24;
 285         if (len > 2)
 286                 *to++ = (value & 0xFF0000) >> 16;
 287         if (len > 1)
 288                 *to++ = (value & 0xFF00) >> 8;
 289         if (len > 0)
 290                 *to++ = (value & 0xFF);
 291 }
 292
 293 static inline int dccp_ndp_len(const int ndp)
 294 {
 295         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 296 }
 297
 298 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 299                         const unsigned char option,
 300                         const void *value, const unsigned char len)
 301 {
 302         unsigned char *to;
 303
 304         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 305                 return -1;
 306
 307         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 308
 309         to    = skb_push(skb, len + 2);
 310         *to++ = option;
 311         *to++ = len + 2;
 312
 313         memcpy(to, value, len);
 314         return 0;
 315 }
 316
 317 EXPORT_SYMBOL_GPL(dccp_insert_option);
 318
 319 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 320 {
 321         struct dccp_sock *dp = dccp_sk(sk);
 322         int ndp = dp->dccps_ndp_count;
 323
 324         if (dccp_non_data_packet(skb))
 325                 ++dp->dccps_ndp_count;
 326         else
 327                 dp->dccps_ndp_count = 0;
 328
 329         if (ndp > 0) {
 330                 unsigned char *ptr;
 331                 const int ndp_len = dccp_ndp_len(ndp);
 332                 const int len = ndp_len + 2;
 333
 334                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 335                         return -1;
 336
 337                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 338
 339                 ptr = skb_push(skb, len);
 340                 *ptr++ = DCCPO_NDP_COUNT;
 341                 *ptr++ = len;
 342                 dccp_encode_value_var(ndp, ptr, ndp_len);
 343         }
 344
 345         return 0;
 346 }
 347
 348 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 349 {
 350         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 351 }
 352
 353 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
 354                                     u32 elapsed_time)
 355 {
 356         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 357         const int len = 2 + elapsed_time_len;
 358         unsigned char *to;
 359
 360         if (elapsed_time_len == 0)
 361                 return 0;
 362
 363         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 364                 return -1;
 365
 366         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 367
 368         to    = skb_push(skb, len);
 369         *to++ = DCCPO_ELAPSED_TIME;
 370         *to++ = len;
 371
 372         if (elapsed_time_len == 2) {
 373                 const __be16 var16 = htons((u16)elapsed_time);
 374                 memcpy(to, &var16, 2);
 375         } else {
 376                 const __be32 var32 = htonl(elapsed_time);
 377                 memcpy(to, &var32, 4);
 378         }
 379
 380         return 0;
 381 }
 382
 383 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 384
 385 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 386 {
 387         __be32 now = htonl(dccp_timestamp());
 388         /* yes this will overflow but that is the point as we want a
 389          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 390
 391         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 392 }
 393
 394 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 395
 396 static int dccp_insert_option_timestamp_echo(struct sock *sk,
 397                                              struct sk_buff *skb)
 398 {
 399         struct dccp_sock *dp = dccp_sk(sk);
 400         __be32 tstamp_echo;
 401         int len, elapsed_time_len;
 402         unsigned char *to;
 403         const suseconds_t delta = ktime_us_delta(ktime_get_real(),
 404                                                  dp->dccps_timestamp_time);
 405         u32 elapsed_time = delta / 10;
 406         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 407         len = 6 + elapsed_time_len;
 408
 409         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 410                 return -1;
 411
 412         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 413
 414         to    = skb_push(skb, len);
 415         *to++ = DCCPO_TIMESTAMP_ECHO;
 416         *to++ = len;
 417
 418         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 419         memcpy(to, &tstamp_echo, 4);
 420         to += 4;
 421
 422         if (elapsed_time_len == 2) {
 423                 const __be16 var16 = htons((u16)elapsed_time);
 424                 memcpy(to, &var16, 2);
 425         } else if (elapsed_time_len == 4) {
 426                 const __be32 var32 = htonl(elapsed_time);
 427                 memcpy(to, &var32, 4);
 428         }
 429
 430         dp->dccps_timestamp_echo = 0;
 431         dp->dccps_timestamp_time = ktime_set(0, 0);
 432         return 0;
 433 }
 434
 435 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 436                                 u8 *val, u8 len)
 437 {
 438         u8 *to;
 439
 440         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 441                 DCCP_WARN("packet too small for feature %d option!\n", feat);
 442                 return -1;
 443         }
 444
 445         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 446
 447         to    = skb_push(skb, len + 3);
 448         *to++ = type;
 449         *to++ = len + 3;
 450         *to++ = feat;
 451
 452         if (len)
 453                 memcpy(to, val, len);
 454
 455         dccp_pr_debug("%s(%s (%d), ...), length %d\n",
 456                       dccp_feat_typename(type),
 457                       dccp_feat_name(feat), feat, len);
 458         return 0;
 459 }
 460
 461 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 462 {
 463         struct dccp_sock *dp = dccp_sk(sk);
 464         struct dccp_minisock *dmsk = dccp_msk(sk);
 465         struct dccp_opt_pend *opt, *next;
 466         int change = 0;
 467
 468         /* confirm any options [NN opts] */
 469         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 470                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 471                                      opt->dccpop_feat, opt->dccpop_val,
 472                                      opt->dccpop_len);
 473                 /* fear empty confirms */
 474                 if (opt->dccpop_val)
 475                         kfree(opt->dccpop_val);
 476                 kfree(opt);
 477         }
 478         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 479
 480         /* see which features we need to send */
 481         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 482                 /* see if we need to send any confirm */
 483                 if (opt->dccpop_sc) {
 484                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 485                                              opt->dccpop_feat,
 486                                              opt->dccpop_sc->dccpoc_val,
 487                                              opt->dccpop_sc->dccpoc_len);
 488
 489                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 490                         kfree(opt->dccpop_sc->dccpoc_val);
 491                         kfree(opt->dccpop_sc);
 492                         opt->dccpop_sc = NULL;
 493                 }
 494
 495                 /* any option not confirmed, re-send it */
 496                 if (!opt->dccpop_conf) {
 497                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 498                                              opt->dccpop_feat, opt->dccpop_val,
 499                                              opt->dccpop_len);
 500                         change++;
 501                 }
 502         }
 503
 504         /* Retransmit timer.
 505          * If this is the master listening sock, we don't set a timer on it.  It
 506          * should be fine because if the dude doesn't receive our RESPONSE
 507          * [which will contain the CHANGE] he will send another REQUEST which
 508          * will "retrnasmit" the change.
 509          */
 510         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 511                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 512
 513                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 514                  * only when sending new stuff i guess.  Currently the timer
 515                  * never backs off because on re-transmission it just resets it!
 516                  */
 517                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 518                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 519         }
 520
 521         return 0;
 522 }
 523
 524 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 525 {
 526         struct dccp_sock *dp = dccp_sk(sk);
 527         struct dccp_minisock *dmsk = dccp_msk(sk);
 528
 529         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 530
 531         if (dmsk->dccpms_send_ndp_count &&
 532             dccp_insert_option_ndp(sk, skb))
 533                 return -1;
 534
 535         if (!dccp_packet_without_ack(skb)) {
 536                 if (dmsk->dccpms_send_ack_vector &&
 537                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 538                     dccp_insert_option_ackvec(sk, skb))
 539                         return -1;
 540
 541                 if (dp->dccps_timestamp_echo != 0 &&
 542                     dccp_insert_option_timestamp_echo(sk, skb))
 543                         return -1;
 544         }
 545
 546         if (dp->dccps_hc_rx_insert_options) {
 547                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 548                         return -1;
 549                 dp->dccps_hc_rx_insert_options = 0;
 550         }
 551
 552         /* Feature negotiation */
 553         /* Data packets can't do feat negotiation */
 554         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 555             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 556             dccp_insert_options_feat(sk, skb))
 557                 return -1;
 558
 559         /*
 560          * Obtain RTT sample from Request/Response exchange.
 561          * This is currently used in CCID 3 initialisation.
 562          */
 563         if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST &&
 564             dccp_insert_option_timestamp(sk, skb))
 565                 return -1;
 566
 567         /* XXX: insert other options when appropriate */
 568
 569         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 570                 /* The length of all options has to be a multiple of 4 */
 571                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 572
 573                 if (padding != 0) {
 574                         padding = 4 - padding;
 575                         memset(skb_push(skb, padding), 0, padding);
 576                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 577                 }
 578         }
 579
 580         return 0;
 581 }