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 u64 dccp_decode_value_var(const u8 *bf, const u8 len) 27 { 28 u64 value = 0; 29 30 if (len >= DCCP_OPTVAL_MAXLEN) 31 value += ((u64)*bf++) << 40; 32 if (len > 4) 33 value += ((u64)*bf++) << 32; 34 if (len > 3) 35 value += ((u64)*bf++) << 24; 36 if (len > 2) 37 value += ((u64)*bf++) << 16; 38 if (len > 1) 39 value += ((u64)*bf++) << 8; 40 if (len > 0) 41 value += *bf; 42 43 return value; 44 } 45 46 /** 47 * dccp_parse_options - Parse DCCP options present in @skb 48 * @sk: client|server|listening dccp socket (when @dreq != NULL) 49 * @dreq: request socket to use during connection setup, or NULL 50 */ 51 int dccp_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 52 struct sk_buff *skb) 53 { 54 struct dccp_sock *dp = dccp_sk(sk); 55 const struct dccp_hdr *dh = dccp_hdr(skb); 56 const u8 pkt_type = DCCP_SKB_CB(skb)->dccpd_type; 57 u64 ackno = DCCP_SKB_CB(skb)->dccpd_ack_seq; 58 unsigned char *options = (unsigned char *)dh + dccp_hdr_len(skb); 59 unsigned char *opt_ptr = options; 60 const unsigned char *opt_end = (unsigned char *)dh + 61 (dh->dccph_doff * 4); 62 struct dccp_options_received *opt_recv = &dp->dccps_options_received; 63 unsigned char opt, len; 64 unsigned char *uninitialized_var(value); 65 u32 elapsed_time; 66 __be32 opt_val; 67 int rc; 68 int mandatory = 0; 69 70 memset(opt_recv, 0, sizeof(*opt_recv)); 71 72 opt = len = 0; 73 while (opt_ptr != opt_end) { 74 opt = *opt_ptr++; 75 len = 0; 76 value = NULL; 77 78 /* Check if this isn't a single byte option */ 79 if (opt > DCCPO_MAX_RESERVED) { 80 if (opt_ptr == opt_end) 81 goto out_nonsensical_length; 82 83 len = *opt_ptr++; 84 if (len < 2) 85 goto out_nonsensical_length; 86 /* 87 * Remove the type and len fields, leaving 88 * just the value size 89 */ 90 len -= 2; 91 value = opt_ptr; 92 opt_ptr += len; 93 94 if (opt_ptr > opt_end) 95 goto out_nonsensical_length; 96 } 97 98 /* 99 * CCID-specific options are ignored during connection setup, as 100 * negotiation may still be in progress (see RFC 4340, 10.3). 101 * The same applies to Ack Vectors, as these depend on the CCID. 102 */ 103 if (dreq != NULL && (opt >= DCCPO_MIN_RX_CCID_SPECIFIC || 104 opt == DCCPO_ACK_VECTOR_0 || opt == DCCPO_ACK_VECTOR_1)) 105 goto ignore_option; 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 > 6) 118 goto out_invalid_option; 119 120 opt_recv->dccpor_ndp = dccp_decode_value_var(value, len); 121 dccp_pr_debug("%s opt: NDP count=%llu\n", dccp_role(sk), 122 (unsigned long long)opt_recv->dccpor_ndp); 123 break; 124 case DCCPO_CHANGE_L ... DCCPO_CONFIRM_R: 125 if (pkt_type == DCCP_PKT_DATA) /* RFC 4340, 6 */ 126 break; 127 rc = dccp_feat_parse_options(sk, dreq, mandatory, opt, 128 *value, value + 1, len - 1); 129 if (rc) 130 goto out_featneg_failed; 131 break; 132 case DCCPO_ACK_VECTOR_0: 133 case DCCPO_ACK_VECTOR_1: 134 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */ 135 break; 136 if (dp->dccps_hc_rx_ackvec != NULL && 137 dccp_ackvec_parse(sk, skb, &ackno, opt, value, len)) 138 goto out_invalid_option; 139 break; 140 case DCCPO_TIMESTAMP: 141 if (len != 4) 142 goto out_invalid_option; 143 /* 144 * RFC 4340 13.1: "The precise time corresponding to 145 * Timestamp Value zero is not specified". We use 146 * zero to indicate absence of a meaningful timestamp. 147 */ 148 opt_val = get_unaligned((__be32 *)value); 149 if (unlikely(opt_val == 0)) { 150 DCCP_WARN("Timestamp with zero value\n"); 151 break; 152 } 153 154 if (dreq != NULL) { 155 dreq->dreq_timestamp_echo = ntohl(opt_val); 156 dreq->dreq_timestamp_time = dccp_timestamp(); 157 } else { 158 opt_recv->dccpor_timestamp = 159 dp->dccps_timestamp_echo = ntohl(opt_val); 160 dp->dccps_timestamp_time = dccp_timestamp(); 161 } 162 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n", 163 dccp_role(sk), ntohl(opt_val), 164 (unsigned long long) 165 DCCP_SKB_CB(skb)->dccpd_ack_seq); 166 /* schedule an Ack in case this sender is quiescent */ 167 inet_csk_schedule_ack(sk); 168 break; 169 case DCCPO_TIMESTAMP_ECHO: 170 if (len != 4 && len != 6 && len != 8) 171 goto out_invalid_option; 172 173 opt_val = get_unaligned((__be32 *)value); 174 opt_recv->dccpor_timestamp_echo = ntohl(opt_val); 175 176 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, " 177 "ackno=%llu", dccp_role(sk), 178 opt_recv->dccpor_timestamp_echo, 179 len + 2, 180 (unsigned long long) 181 DCCP_SKB_CB(skb)->dccpd_ack_seq); 182 183 value += 4; 184 185 if (len == 4) { /* no elapsed time included */ 186 dccp_pr_debug_cat("\n"); 187 break; 188 } 189 190 if (len == 6) { /* 2-byte elapsed time */ 191 __be16 opt_val2 = get_unaligned((__be16 *)value); 192 elapsed_time = ntohs(opt_val2); 193 } else { /* 4-byte elapsed time */ 194 opt_val = get_unaligned((__be32 *)value); 195 elapsed_time = ntohl(opt_val); 196 } 197 198 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time); 199 200 /* Give precedence to the biggest ELAPSED_TIME */ 201 if (elapsed_time > opt_recv->dccpor_elapsed_time) 202 opt_recv->dccpor_elapsed_time = elapsed_time; 203 break; 204 case DCCPO_ELAPSED_TIME: 205 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */ 206 break; 207 208 if (len == 2) { 209 __be16 opt_val2 = get_unaligned((__be16 *)value); 210 elapsed_time = ntohs(opt_val2); 211 } else if (len == 4) { 212 opt_val = get_unaligned((__be32 *)value); 213 elapsed_time = ntohl(opt_val); 214 } else { 215 goto out_invalid_option; 216 } 217 218 if (elapsed_time > opt_recv->dccpor_elapsed_time) 219 opt_recv->dccpor_elapsed_time = elapsed_time; 220 221 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n", 222 dccp_role(sk), elapsed_time); 223 break; 224 case DCCPO_MIN_RX_CCID_SPECIFIC ... DCCPO_MAX_RX_CCID_SPECIFIC: 225 if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk, 226 pkt_type, opt, value, len)) 227 goto out_invalid_option; 228 break; 229 case DCCPO_MIN_TX_CCID_SPECIFIC ... DCCPO_MAX_TX_CCID_SPECIFIC: 230 if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk, 231 pkt_type, opt, value, len)) 232 goto out_invalid_option; 233 break; 234 default: 235 DCCP_CRIT("DCCP(%p): option %d(len=%d) not " 236 "implemented, ignoring", sk, opt, len); 237 break; 238 } 239 ignore_option: 240 if (opt != DCCPO_MANDATORY) 241 mandatory = 0; 242 } 243 244 /* mandatory was the last byte in option list -> reset connection */ 245 if (mandatory) 246 goto out_invalid_option; 247 248 out_nonsensical_length: 249 /* RFC 4340, 5.8: ignore option and all remaining option space */ 250 return 0; 251 252 out_invalid_option: 253 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT); 254 rc = DCCP_RESET_CODE_OPTION_ERROR; 255 out_featneg_failed: 256 DCCP_WARN("DCCP(%p): Option %d (len=%d) error=%u\n", sk, opt, len, rc); 257 DCCP_SKB_CB(skb)->dccpd_reset_code = rc; 258 DCCP_SKB_CB(skb)->dccpd_reset_data[0] = opt; 259 DCCP_SKB_CB(skb)->dccpd_reset_data[1] = len > 0 ? value[0] : 0; 260 DCCP_SKB_CB(skb)->dccpd_reset_data[2] = len > 1 ? value[1] : 0; 261 return -1; 262 } 263 264 EXPORT_SYMBOL_GPL(dccp_parse_options); 265 266 void dccp_encode_value_var(const u64 value, u8 *to, const u8 len) 267 { 268 if (len >= DCCP_OPTVAL_MAXLEN) 269 *to++ = (value & 0xFF0000000000ull) >> 40; 270 if (len > 4) 271 *to++ = (value & 0xFF00000000ull) >> 32; 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 u8 dccp_ndp_len(const u64 ndp) 283 { 284 if (likely(ndp <= 0xFF)) 285 return 1; 286 return likely(ndp <= USHRT_MAX) ? 2 : (ndp <= UINT_MAX ? 4 : 6); 287 } 288 289 int dccp_insert_option(struct sk_buff *skb, const unsigned char option, 290 const void *value, const unsigned char len) 291 { 292 unsigned char *to; 293 294 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) 295 return -1; 296 297 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2; 298 299 to = skb_push(skb, len + 2); 300 *to++ = option; 301 *to++ = len + 2; 302 303 memcpy(to, value, len); 304 return 0; 305 } 306 307 EXPORT_SYMBOL_GPL(dccp_insert_option); 308 309 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb) 310 { 311 struct dccp_sock *dp = dccp_sk(sk); 312 u64 ndp = dp->dccps_ndp_count; 313 314 if (dccp_non_data_packet(skb)) 315 ++dp->dccps_ndp_count; 316 else 317 dp->dccps_ndp_count = 0; 318 319 if (ndp > 0) { 320 unsigned char *ptr; 321 const int ndp_len = dccp_ndp_len(ndp); 322 const int len = ndp_len + 2; 323 324 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 325 return -1; 326 327 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 328 329 ptr = skb_push(skb, len); 330 *ptr++ = DCCPO_NDP_COUNT; 331 *ptr++ = len; 332 dccp_encode_value_var(ndp, ptr, ndp_len); 333 } 334 335 return 0; 336 } 337 338 static inline int dccp_elapsed_time_len(const u32 elapsed_time) 339 { 340 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4; 341 } 342 343 /* FIXME: This function is currently not used anywhere */ 344 int dccp_insert_option_elapsed_time(struct sk_buff *skb, u32 elapsed_time) 345 { 346 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time); 347 const int len = 2 + elapsed_time_len; 348 unsigned char *to; 349 350 if (elapsed_time_len == 0) 351 return 0; 352 353 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 354 return -1; 355 356 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 357 358 to = skb_push(skb, len); 359 *to++ = DCCPO_ELAPSED_TIME; 360 *to++ = len; 361 362 if (elapsed_time_len == 2) { 363 const __be16 var16 = htons((u16)elapsed_time); 364 memcpy(to, &var16, 2); 365 } else { 366 const __be32 var32 = htonl(elapsed_time); 367 memcpy(to, &var32, 4); 368 } 369 370 return 0; 371 } 372 373 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time); 374 375 static int dccp_insert_option_timestamp(struct sk_buff *skb) 376 { 377 __be32 now = htonl(dccp_timestamp()); 378 /* yes this will overflow but that is the point as we want a 379 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */ 380 381 return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now)); 382 } 383 384 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp, 385 struct dccp_request_sock *dreq, 386 struct sk_buff *skb) 387 { 388 __be32 tstamp_echo; 389 unsigned char *to; 390 u32 elapsed_time, elapsed_time_len, len; 391 392 if (dreq != NULL) { 393 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time; 394 tstamp_echo = htonl(dreq->dreq_timestamp_echo); 395 dreq->dreq_timestamp_echo = 0; 396 } else { 397 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time; 398 tstamp_echo = htonl(dp->dccps_timestamp_echo); 399 dp->dccps_timestamp_echo = 0; 400 } 401 402 elapsed_time_len = dccp_elapsed_time_len(elapsed_time); 403 len = 6 + elapsed_time_len; 404 405 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 406 return -1; 407 408 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 409 410 to = skb_push(skb, len); 411 *to++ = DCCPO_TIMESTAMP_ECHO; 412 *to++ = len; 413 414 memcpy(to, &tstamp_echo, 4); 415 to += 4; 416 417 if (elapsed_time_len == 2) { 418 const __be16 var16 = htons((u16)elapsed_time); 419 memcpy(to, &var16, 2); 420 } else if (elapsed_time_len == 4) { 421 const __be32 var32 = htonl(elapsed_time); 422 memcpy(to, &var32, 4); 423 } 424 425 return 0; 426 } 427 428 static int dccp_insert_option_ackvec(struct sock *sk, struct sk_buff *skb) 429 { 430 struct dccp_sock *dp = dccp_sk(sk); 431 struct dccp_ackvec *av = dp->dccps_hc_rx_ackvec; 432 const u16 buflen = dccp_ackvec_buflen(av); 433 /* Figure out how many options do we need to represent the ackvec */ 434 const u8 nr_opts = DIV_ROUND_UP(buflen, DCCP_SINGLE_OPT_MAXLEN); 435 u16 len = buflen + 2 * nr_opts; 436 u8 i, nonce = 0; 437 const unsigned char *tail, *from; 438 unsigned char *to; 439 440 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 441 return -1; 442 443 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 444 445 to = skb_push(skb, len); 446 len = buflen; 447 from = av->av_buf + av->av_buf_head; 448 tail = av->av_buf + DCCPAV_MAX_ACKVEC_LEN; 449 450 for (i = 0; i < nr_opts; ++i) { 451 int copylen = len; 452 453 if (len > DCCP_SINGLE_OPT_MAXLEN) 454 copylen = DCCP_SINGLE_OPT_MAXLEN; 455 456 /* 457 * RFC 4340, 12.2: Encode the Nonce Echo for this Ack Vector via 458 * its type; ack_nonce is the sum of all individual buf_nonce's. 459 */ 460 nonce ^= av->av_buf_nonce[i]; 461 462 *to++ = DCCPO_ACK_VECTOR_0 + av->av_buf_nonce[i]; 463 *to++ = copylen + 2; 464 465 /* Check if buf_head wraps */ 466 if (from + copylen > tail) { 467 const u16 tailsize = tail - from; 468 469 memcpy(to, from, tailsize); 470 to += tailsize; 471 len -= tailsize; 472 copylen -= tailsize; 473 from = av->av_buf; 474 } 475 476 memcpy(to, from, copylen); 477 from += copylen; 478 to += copylen; 479 len -= copylen; 480 } 481 /* 482 * Each sent Ack Vector is recorded in the list, as per A.2 of RFC 4340. 483 */ 484 if (dccp_ackvec_update_records(av, DCCP_SKB_CB(skb)->dccpd_seq, nonce)) 485 return -ENOBUFS; 486 return 0; 487 } 488 489 /** 490 * dccp_insert_option_mandatory - Mandatory option (5.8.2) 491 * Note that since we are using skb_push, this function needs to be called 492 * _after_ inserting the option it is supposed to influence (stack order). 493 */ 494 int dccp_insert_option_mandatory(struct sk_buff *skb) 495 { 496 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN) 497 return -1; 498 499 DCCP_SKB_CB(skb)->dccpd_opt_len++; 500 *skb_push(skb, 1) = DCCPO_MANDATORY; 501 return 0; 502 } 503 504 /** 505 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb 506 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R 507 * @feat: one out of %dccp_feature_numbers 508 * @val: NN value or SP array (preferred element first) to copy 509 * @len: true length of @val in bytes (excluding first element repetition) 510 * @repeat_first: whether to copy the first element of @val twice 511 * The last argument is used to construct Confirm options, where the preferred 512 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference 513 * lists are kept such that the preferred entry is always first, so we only need 514 * to copy twice, and avoid the overhead of cloning into a bigger array. 515 */ 516 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat, 517 u8 *val, u8 len, bool repeat_first) 518 { 519 u8 tot_len, *to; 520 521 /* take the `Feature' field and possible repetition into account */ 522 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) { 523 DCCP_WARN("length %u for feature %u too large\n", len, feat); 524 return -1; 525 } 526 527 if (unlikely(val == NULL || len == 0)) 528 len = repeat_first = 0; 529 tot_len = 3 + repeat_first + len; 530 531 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) { 532 DCCP_WARN("packet too small for feature %d option!\n", feat); 533 return -1; 534 } 535 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len; 536 537 to = skb_push(skb, tot_len); 538 *to++ = type; 539 *to++ = tot_len; 540 *to++ = feat; 541 542 if (repeat_first) 543 *to++ = *val; 544 if (len) 545 memcpy(to, val, len); 546 return 0; 547 } 548 549 /* The length of all options needs to be a multiple of 4 (5.8) */ 550 static void dccp_insert_option_padding(struct sk_buff *skb) 551 { 552 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4; 553 554 if (padding != 0) { 555 padding = 4 - padding; 556 memset(skb_push(skb, padding), 0, padding); 557 DCCP_SKB_CB(skb)->dccpd_opt_len += padding; 558 } 559 } 560 561 int dccp_insert_options(struct sock *sk, struct sk_buff *skb) 562 { 563 struct dccp_sock *dp = dccp_sk(sk); 564 565 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 566 567 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb)) 568 return -1; 569 570 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) { 571 572 /* Feature Negotiation */ 573 if (dccp_feat_insert_opts(dp, NULL, skb)) 574 return -1; 575 576 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) { 577 /* 578 * Obtain RTT sample from Request/Response exchange. 579 * This is currently used for TFRC initialisation. 580 */ 581 if (dccp_insert_option_timestamp(skb)) 582 return -1; 583 584 } else if (dccp_ackvec_pending(sk) && 585 dccp_insert_option_ackvec(sk, skb)) { 586 return -1; 587 } 588 } 589 590 if (dp->dccps_hc_rx_insert_options) { 591 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb)) 592 return -1; 593 dp->dccps_hc_rx_insert_options = 0; 594 } 595 596 if (dp->dccps_timestamp_echo != 0 && 597 dccp_insert_option_timestamp_echo(dp, NULL, skb)) 598 return -1; 599 600 dccp_insert_option_padding(skb); 601 return 0; 602 } 603 604 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb) 605 { 606 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 607 608 if (dccp_feat_insert_opts(NULL, dreq, skb)) 609 return -1; 610 611 /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */ 612 if (dccp_insert_option_timestamp(skb)) 613 return -1; 614 615 if (dreq->dreq_timestamp_echo != 0 && 616 dccp_insert_option_timestamp_echo(NULL, dreq, skb)) 617 return -1; 618 619 dccp_insert_option_padding(skb); 620 return 0; 621 } 622