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 <iam4@cs.waikato.ac.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/config.h>
  15 #include <linux/dccp.h>
  16 #include <linux/module.h>
  17 #include <linux/types.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 dccp_feat_default_sequence_window = DCCPF_INITIAL_SEQUENCE_WINDOW;
  27 int dccp_feat_default_rx_ccid         = DCCPF_INITIAL_CCID;
  28 int dccp_feat_default_tx_ccid         = DCCPF_INITIAL_CCID;
  29 int dccp_feat_default_ack_ratio       = DCCPF_INITIAL_ACK_RATIO;
  30 int dccp_feat_default_send_ack_vector = DCCPF_INITIAL_SEND_ACK_VECTOR;
  31 int dccp_feat_default_send_ndp_count  = DCCPF_INITIAL_SEND_NDP_COUNT;
  32
  33 void dccp_minisock_init(struct dccp_minisock *dmsk)
  34 {
  35         dmsk->dccpms_sequence_window = dccp_feat_default_sequence_window;
  36         dmsk->dccpms_rx_ccid         = dccp_feat_default_rx_ccid;
  37         dmsk->dccpms_tx_ccid         = dccp_feat_default_tx_ccid;
  38         dmsk->dccpms_ack_ratio       = dccp_feat_default_ack_ratio;
  39         dmsk->dccpms_send_ack_vector = dccp_feat_default_send_ack_vector;
  40         dmsk->dccpms_send_ndp_count  = dccp_feat_default_send_ndp_count;
  41 }
  42
  43 static u32 dccp_decode_value_var(const unsigned char *bf, const u8 len)
  44 {
  45         u32 value = 0;
  46
  47         if (len > 3)
  48                 value += *bf++ << 24;
  49         if (len > 2)
  50                 value += *bf++ << 16;
  51         if (len > 1)
  52                 value += *bf++ << 8;
  53         if (len > 0)
  54                 value += *bf;
  55
  56         return value;
  57 }
  58
  59 int dccp_parse_options(struct sock *sk, struct sk_buff *skb)
  60 {
  61         struct dccp_sock *dp = dccp_sk(sk);
  62 #ifdef CONFIG_IP_DCCP_DEBUG
  63         const char *debug_prefix = dp->dccps_role == DCCP_ROLE_CLIENT ?
  64                                         "CLIENT rx opt: " : "server rx opt: ";
  65 #endif
  66         const struct dccp_hdr *dh = dccp_hdr(skb);
  67         const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type;
  68         unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb);
  69         unsigned char *opt_ptr = options;
  70         const unsigned char *opt_end = (unsigned char *)dh +
  71                                         (dh->dccph_doff * 4);
  72         struct dccp_options_received *opt_recv = &dp->dccps_options_received;
  73         unsigned char opt, len;
  74         unsigned char *value;
  75         u32 elapsed_time;
  76         int rc;
  77         int mandatory = 0;
  78
  79         memset(opt_recv, 0, sizeof(*opt_recv));
  80
  81         opt = len = 0;
  82         while (opt_ptr != opt_end) {
  83                 opt   = *opt_ptr++;
  84                 len   = 0;
  85                 value = NULL;
  86
  87                 /* Check if this isn't a single byte option */
  88                 if (opt > DCCPO_MAX_RESERVED) {
  89                         if (opt_ptr == opt_end)
  90                                 goto out_invalid_option;
  91
  92                         len = *opt_ptr++;
  93                         if (len < 3)
  94                                 goto out_invalid_option;
  95                         /*
  96                          * Remove the type and len fields, leaving
  97                          * just the value size
  98                          */
  99                         len     -= 2;
 100                         value   = opt_ptr;
 101                         opt_ptr += len;
 102
 103                         if (opt_ptr > opt_end)
 104                                 goto out_invalid_option;
 105                 }
 106
 107                 switch (opt) {
 108                 case DCCPO_PADDING:
 109                         break;
 110                 case DCCPO_MANDATORY:
 111                         if (mandatory)
 112                                 goto out_invalid_option;
 113                         if (pkt_type != DCCP_PKT_DATA)
 114                                 mandatory = 1;
 115                         break;
 116                 case DCCPO_NDP_COUNT:
 117                         if (len > 3)
 118                                 goto out_invalid_option;
 119
 120                         opt_recv->dccpor_ndp = dccp_decode_value_var(value, len);
 121                         dccp_pr_debug("%sNDP count=%d\n", debug_prefix,
 122                                       opt_recv->dccpor_ndp);
 123                         break;
 124                 case DCCPO_CHANGE_L:
 125                         /* fall through */
 126                 case DCCPO_CHANGE_R:
 127                         if (len < 2)
 128                                 goto out_invalid_option;
 129                         rc = dccp_feat_change_recv(sk, opt, *value, value + 1,
 130                                                    len - 1);
 131                         /*
 132                          * When there is a change error, change_recv is
 133                          * responsible for dealing with it.  i.e. reply with an
 134                          * empty confirm.
 135                          * If the change was mandatory, then we need to die.
 136                          */
 137                         if (rc && mandatory)
 138                                 goto out_invalid_option;
 139                         break;
 140                 case DCCPO_CONFIRM_L:
 141                         /* fall through */
 142                 case DCCPO_CONFIRM_R:
 143                         if (len < 2)
 144                                 goto out_invalid_option;
 145                         if (dccp_feat_confirm_recv(sk, opt, *value,
 146                                                    value + 1, len - 1))
 147                                 goto out_invalid_option;
 148                         break;
 149                 case DCCPO_ACK_VECTOR_0:
 150                 case DCCPO_ACK_VECTOR_1:
 151                         if (pkt_type == DCCP_PKT_DATA)
 152                                 break;
 153
 154                         if (dccp_msk(sk)->dccpms_send_ack_vector &&
 155                             dccp_ackvec_parse(sk, skb, opt, value, len))
 156                                 goto out_invalid_option;
 157                         break;
 158                 case DCCPO_TIMESTAMP:
 159                         if (len != 4)
 160                                 goto out_invalid_option;
 161
 162                         opt_recv->dccpor_timestamp = ntohl(*(__be32 *)value);
 163
 164                         dp->dccps_timestamp_echo = opt_recv->dccpor_timestamp;
 165                         dccp_timestamp(sk, &dp->dccps_timestamp_time);
 166
 167                         dccp_pr_debug("%sTIMESTAMP=%u, ackno=%llu\n",
 168                                       debug_prefix, opt_recv->dccpor_timestamp,
 169                                       (unsigned long long)
 170                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 171                         break;
 172                 case DCCPO_TIMESTAMP_ECHO:
 173                         if (len != 4 && len != 6 && len != 8)
 174                                 goto out_invalid_option;
 175
 176                         opt_recv->dccpor_timestamp_echo = ntohl(*(__be32 *)value);
 177
 178                         dccp_pr_debug("%sTIMESTAMP_ECHO=%u, len=%d, ackno=%llu, ",
 179                                       debug_prefix,
 180                                       opt_recv->dccpor_timestamp_echo,
 181                                       len + 2,
 182                                       (unsigned long long)
 183                                       DCCP_SKB_CB(skb)->dccpd_ack_seq);
 184
 185
 186                         if (len == 4)
 187                                 break;
 188
 189                         if (len == 6)
 190                                 elapsed_time = ntohs(*(__be16 *)(value + 4));
 191                         else
 192                                 elapsed_time = ntohl(*(__be32 *)(value + 4));
 193
 194                         /* Give precedence to the biggest ELAPSED_TIME */
 195                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 196                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 197                         break;
 198                 case DCCPO_ELAPSED_TIME:
 199                         if (len != 2 && len != 4)
 200                                 goto out_invalid_option;
 201
 202                         if (pkt_type == DCCP_PKT_DATA)
 203                                 continue;
 204
 205                         if (len == 2)
 206                                 elapsed_time = ntohs(*(__be16 *)value);
 207                         else
 208                                 elapsed_time = ntohl(*(__be32 *)value);
 209
 210                         if (elapsed_time > opt_recv->dccpor_elapsed_time)
 211                                 opt_recv->dccpor_elapsed_time = elapsed_time;
 212
 213                         dccp_pr_debug("%sELAPSED_TIME=%d\n", debug_prefix,
 214                                       elapsed_time);
 215                         break;
 216                         /*
 217                          * From draft-ietf-dccp-spec-11.txt:
 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                         pr_info("DCCP(%p): option %d(len=%d) not "
 245                                 "implemented, ignoring\n",
 246                                 sk, opt, len);
 247                         break;
 248                 }
 249
 250                 if (opt != DCCPO_MANDATORY)
 251                         mandatory = 0;
 252         }
 253
 254         /* mandatory was the last byte in option list -> reset connection */
 255         if (mandatory)
 256                 goto out_invalid_option;
 257
 258         return 0;
 259
 260 out_invalid_option:
 261         DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT);
 262         DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR;
 263         pr_info("DCCP(%p): invalid option %d, len=%d\n", sk, opt, len);
 264         return -1;
 265 }
 266
 267 EXPORT_SYMBOL_GPL(dccp_parse_options);
 268
 269 static void dccp_encode_value_var(const u32 value, unsigned char *to,
 270                                   const unsigned int len)
 271 {
 272         if (len > 3)
 273                 *to++ = (value & 0xFF000000) >> 24;
 274         if (len > 2)
 275                 *to++ = (value & 0xFF0000) >> 16;
 276         if (len > 1)
 277                 *to++ = (value & 0xFF00) >> 8;
 278         if (len > 0)
 279                 *to++ = (value & 0xFF);
 280 }
 281
 282 static inline int dccp_ndp_len(const int ndp)
 283 {
 284         return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3;
 285 }
 286
 287 int dccp_insert_option(struct sock *sk, struct sk_buff *skb,
 288                         const unsigned char option,
 289                         const void *value, const unsigned char len)
 290 {
 291         unsigned char *to;
 292
 293         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN)
 294                 return -1;
 295
 296         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2;
 297
 298         to    = skb_push(skb, len + 2);
 299         *to++ = option;
 300         *to++ = len + 2;
 301
 302         memcpy(to, value, len);
 303         return 0;
 304 }
 305
 306 EXPORT_SYMBOL_GPL(dccp_insert_option);
 307
 308 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb)
 309 {
 310         struct dccp_sock *dp = dccp_sk(sk);
 311         int ndp = dp->dccps_ndp_count;
 312
 313         if (dccp_non_data_packet(skb))
 314                 ++dp->dccps_ndp_count;
 315         else
 316                 dp->dccps_ndp_count = 0;
 317
 318         if (ndp > 0) {
 319                 unsigned char *ptr;
 320                 const int ndp_len = dccp_ndp_len(ndp);
 321                 const int len = ndp_len + 2;
 322
 323                 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 324                         return -1;
 325
 326                 DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 327
 328                 ptr = skb_push(skb, len);
 329                 *ptr++ = DCCPO_NDP_COUNT;
 330                 *ptr++ = len;
 331                 dccp_encode_value_var(ndp, ptr, ndp_len);
 332         }
 333
 334         return 0;
 335 }
 336
 337 static inline int dccp_elapsed_time_len(const u32 elapsed_time)
 338 {
 339         return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4;
 340 }
 341
 342 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb,
 343                                     u32 elapsed_time)
 344 {
 345         const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 346         const int len = 2 + elapsed_time_len;
 347         unsigned char *to;
 348
 349         if (elapsed_time_len == 0)
 350                 return 0;
 351
 352         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 353                 return -1;
 354
 355         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 356
 357         to    = skb_push(skb, len);
 358         *to++ = DCCPO_ELAPSED_TIME;
 359         *to++ = len;
 360
 361         if (elapsed_time_len == 2) {
 362                 const __be16 var16 = htons((u16)elapsed_time);
 363                 memcpy(to, &var16, 2);
 364         } else {
 365                 const __be32 var32 = htonl(elapsed_time);
 366                 memcpy(to, &var32, 4);
 367         }
 368
 369         return 0;
 370 }
 371
 372 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time);
 373
 374 void dccp_timestamp(const struct sock *sk, struct timeval *tv)
 375 {
 376         const struct dccp_sock *dp = dccp_sk(sk);
 377
 378         do_gettimeofday(tv);
 379         tv->tv_sec  -= dp->dccps_epoch.tv_sec;
 380         tv->tv_usec -= dp->dccps_epoch.tv_usec;
 381
 382         while (tv->tv_usec < 0) {
 383                 tv->tv_sec--;
 384                 tv->tv_usec += USEC_PER_SEC;
 385         }
 386 }
 387
 388 EXPORT_SYMBOL_GPL(dccp_timestamp);
 389
 390 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb)
 391 {
 392         struct timeval tv;
 393         __be32 now;
 394
 395         dccp_timestamp(sk, &tv);
 396         now = htonl(timeval_usecs(&tv) / 10);
 397         /* yes this will overflow but that is the point as we want a
 398          * 10 usec 32 bit timer which mean it wraps every 11.9 hours */
 399
 400         return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now));
 401 }
 402
 403 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp);
 404
 405 static int dccp_insert_option_timestamp_echo(struct sock *sk,
 406                                              struct sk_buff *skb)
 407 {
 408         struct dccp_sock *dp = dccp_sk(sk);
 409         struct timeval now;
 410         __be32 tstamp_echo;
 411         u32 elapsed_time;
 412         int len, elapsed_time_len;
 413         unsigned char *to;
 414
 415         dccp_timestamp(sk, &now);
 416         elapsed_time = timeval_delta(&now, &dp->dccps_timestamp_time) / 10;
 417         elapsed_time_len = dccp_elapsed_time_len(elapsed_time);
 418         len = 6 + elapsed_time_len;
 419
 420         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN)
 421                 return -1;
 422
 423         DCCP_SKB_CB(skb)->dccpd_opt_len += len;
 424
 425         to    = skb_push(skb, len);
 426         *to++ = DCCPO_TIMESTAMP_ECHO;
 427         *to++ = len;
 428
 429         tstamp_echo = htonl(dp->dccps_timestamp_echo);
 430         memcpy(to, &tstamp_echo, 4);
 431         to += 4;
 432
 433         if (elapsed_time_len == 2) {
 434                 const __be16 var16 = htons((u16)elapsed_time);
 435                 memcpy(to, &var16, 2);
 436         } else if (elapsed_time_len == 4) {
 437                 const __be32 var32 = htonl(elapsed_time);
 438                 memcpy(to, &var32, 4);
 439         }
 440
 441         dp->dccps_timestamp_echo = 0;
 442         dp->dccps_timestamp_time.tv_sec = 0;
 443         dp->dccps_timestamp_time.tv_usec = 0;
 444         return 0;
 445 }
 446
 447 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat,
 448                                 u8 *val, u8 len)
 449 {
 450         u8 *to;
 451
 452         if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) {
 453                 LIMIT_NETDEBUG(KERN_INFO "DCCP: packet too small"
 454                                " to insert feature %d option!\n", feat);
 455                 return -1;
 456         }
 457
 458         DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3;
 459
 460         to    = skb_push(skb, len + 3);
 461         *to++ = type;
 462         *to++ = len + 3;
 463         *to++ = feat;
 464
 465         if (len)
 466                 memcpy(to, val, len);
 467         dccp_pr_debug("option %d feat %d len %d\n", type, feat, len);
 468
 469         return 0;
 470 }
 471
 472 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb)
 473 {
 474         struct dccp_sock *dp = dccp_sk(sk);
 475         struct dccp_minisock *dmsk = dccp_msk(sk);
 476         struct dccp_opt_pend *opt, *next;
 477         int change = 0;
 478
 479         /* confirm any options [NN opts] */
 480         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
 481                 dccp_insert_feat_opt(skb, opt->dccpop_type,
 482                                      opt->dccpop_feat, opt->dccpop_val,
 483                                      opt->dccpop_len);
 484                 /* fear empty confirms */
 485                 if (opt->dccpop_val)
 486                         kfree(opt->dccpop_val);
 487                 kfree(opt);
 488         }
 489         INIT_LIST_HEAD(&dmsk->dccpms_conf);
 490
 491         /* see which features we need to send */
 492         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 493                 /* see if we need to send any confirm */
 494                 if (opt->dccpop_sc) {
 495                         dccp_insert_feat_opt(skb, opt->dccpop_type + 1,
 496                                              opt->dccpop_feat,
 497                                              opt->dccpop_sc->dccpoc_val,
 498                                              opt->dccpop_sc->dccpoc_len);
 499
 500                         BUG_ON(!opt->dccpop_sc->dccpoc_val);
 501                         kfree(opt->dccpop_sc->dccpoc_val);
 502                         kfree(opt->dccpop_sc);
 503                         opt->dccpop_sc = NULL;
 504                 }
 505
 506                 /* any option not confirmed, re-send it */
 507                 if (!opt->dccpop_conf) {
 508                         dccp_insert_feat_opt(skb, opt->dccpop_type,
 509                                              opt->dccpop_feat, opt->dccpop_val,
 510                                              opt->dccpop_len);
 511                         change++;
 512                 }
 513         }
 514
 515         /* Retransmit timer.
 516          * If this is the master listening sock, we don't set a timer on it.  It
 517          * should be fine because if the dude doesn't receive our RESPONSE
 518          * [which will contain the CHANGE] he will send another REQUEST which
 519          * will "retrnasmit" the change.
 520          */
 521         if (change && dp->dccps_role != DCCP_ROLE_LISTEN) {
 522                 dccp_pr_debug("reset feat negotiation timer %p\n", sk);
 523
 524                 /* XXX don't reset the timer on re-transmissions.  I.e. reset it
 525                  * only when sending new stuff i guess.  Currently the timer
 526                  * never backs off because on re-transmission it just resets it!
 527                  */
 528                 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS,
 529                                           inet_csk(sk)->icsk_rto, DCCP_RTO_MAX);
 530         }
 531
 532         return 0;
 533 }
 534
 535 int dccp_insert_options(struct sock *sk, struct sk_buff *skb)
 536 {
 537         struct dccp_sock *dp = dccp_sk(sk);
 538         struct dccp_minisock *dmsk = dccp_msk(sk);
 539
 540         DCCP_SKB_CB(skb)->dccpd_opt_len = 0;
 541
 542         if (dmsk->dccpms_send_ndp_count &&
 543             dccp_insert_option_ndp(sk, skb))
 544                 return -1;
 545
 546         if (!dccp_packet_without_ack(skb)) {
 547                 if (dmsk->dccpms_send_ack_vector &&
 548                     dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) &&
 549                     dccp_insert_option_ackvec(sk, skb))
 550                         return -1;
 551
 552                 if (dp->dccps_timestamp_echo != 0 &&
 553                     dccp_insert_option_timestamp_echo(sk, skb))
 554                         return -1;
 555         }
 556
 557         if (dp->dccps_hc_rx_insert_options) {
 558                 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb))
 559                         return -1;
 560                 dp->dccps_hc_rx_insert_options = 0;
 561         }
 562         if (dp->dccps_hc_tx_insert_options) {
 563                 if (ccid_hc_tx_insert_options(dp->dccps_hc_tx_ccid, sk, skb))
 564                         return -1;
 565                 dp->dccps_hc_tx_insert_options = 0;
 566         }
 567
 568         /* Feature negotiation */
 569         /* Data packets can't do feat negotiation */
 570         if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA &&
 571             DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK &&
 572             dccp_insert_options_feat(sk, skb))
 573                 return -1;
 574
 575         /* XXX: insert other options when appropriate */
 576
 577         if (DCCP_SKB_CB(skb)->dccpd_opt_len != 0) {
 578                 /* The length of all options has to be a multiple of 4 */
 579                 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4;
 580
 581                 if (padding != 0) {
 582                         padding = 4 - padding;
 583                         memset(skb_push(skb, padding), 0, padding);
 584                         DCCP_SKB_CB(skb)->dccpd_opt_len += padding;
 585                 }
 586         }
 587
 588         return 0;
 589 }