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 int dccp_insert_option_elapsed_time(struct sk_buff *skb, 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 static int dccp_insert_option_timestamp(struct sk_buff *skb) 375 { 376 __be32 now = htonl(dccp_timestamp()); 377 /* yes this will overflow but that is the point as we want a 378 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */ 379 380 return dccp_insert_option(skb, DCCPO_TIMESTAMP, &now, sizeof(now)); 381 } 382 383 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp, 384 struct dccp_request_sock *dreq, 385 struct sk_buff *skb) 386 { 387 __be32 tstamp_echo; 388 unsigned char *to; 389 u32 elapsed_time, elapsed_time_len, len; 390 391 if (dreq != NULL) { 392 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time; 393 tstamp_echo = htonl(dreq->dreq_timestamp_echo); 394 dreq->dreq_timestamp_echo = 0; 395 } else { 396 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time; 397 tstamp_echo = htonl(dp->dccps_timestamp_echo); 398 dp->dccps_timestamp_echo = 0; 399 } 400 401 elapsed_time_len = dccp_elapsed_time_len(elapsed_time); 402 len = 6 + elapsed_time_len; 403 404 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 405 return -1; 406 407 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 408 409 to = skb_push(skb, len); 410 *to++ = DCCPO_TIMESTAMP_ECHO; 411 *to++ = len; 412 413 memcpy(to, &tstamp_echo, 4); 414 to += 4; 415 416 if (elapsed_time_len == 2) { 417 const __be16 var16 = htons((u16)elapsed_time); 418 memcpy(to, &var16, 2); 419 } else if (elapsed_time_len == 4) { 420 const __be32 var32 = htonl(elapsed_time); 421 memcpy(to, &var32, 4); 422 } 423 424 return 0; 425 } 426 427 /** 428 * dccp_insert_option_mandatory - Mandatory option (5.8.2) 429 * Note that since we are using skb_push, this function needs to be called 430 * _after_ inserting the option it is supposed to influence (stack order). 431 */ 432 int dccp_insert_option_mandatory(struct sk_buff *skb) 433 { 434 if (DCCP_SKB_CB(skb)->dccpd_opt_len >= DCCP_MAX_OPT_LEN) 435 return -1; 436 437 DCCP_SKB_CB(skb)->dccpd_opt_len++; 438 *skb_push(skb, 1) = DCCPO_MANDATORY; 439 return 0; 440 } 441 442 /** 443 * dccp_insert_fn_opt - Insert single Feature-Negotiation option into @skb 444 * @type: %DCCPO_CHANGE_L, %DCCPO_CHANGE_R, %DCCPO_CONFIRM_L, %DCCPO_CONFIRM_R 445 * @feat: one out of %dccp_feature_numbers 446 * @val: NN value or SP array (preferred element first) to copy 447 * @len: true length of @val in bytes (excluding first element repetition) 448 * @repeat_first: whether to copy the first element of @val twice 449 * The last argument is used to construct Confirm options, where the preferred 450 * value and the preference list appear separately (RFC 4340, 6.3.1). Preference 451 * lists are kept such that the preferred entry is always first, so we only need 452 * to copy twice, and avoid the overhead of cloning into a bigger array. 453 */ 454 int dccp_insert_fn_opt(struct sk_buff *skb, u8 type, u8 feat, 455 u8 *val, u8 len, bool repeat_first) 456 { 457 u8 tot_len, *to; 458 459 /* take the `Feature' field and possible repetition into account */ 460 if (len > (DCCP_SINGLE_OPT_MAXLEN - 2)) { 461 DCCP_WARN("length %u for feature %u too large\n", len, feat); 462 return -1; 463 } 464 465 if (unlikely(val == NULL || len == 0)) 466 len = repeat_first = 0; 467 tot_len = 3 + repeat_first + len; 468 469 if (DCCP_SKB_CB(skb)->dccpd_opt_len + tot_len > DCCP_MAX_OPT_LEN) { 470 DCCP_WARN("packet too small for feature %d option!\n", feat); 471 return -1; 472 } 473 DCCP_SKB_CB(skb)->dccpd_opt_len += tot_len; 474 475 to = skb_push(skb, tot_len); 476 *to++ = type; 477 *to++ = tot_len; 478 *to++ = feat; 479 480 if (repeat_first) 481 *to++ = *val; 482 if (len) 483 memcpy(to, val, len); 484 return 0; 485 } 486 487 /* The length of all options needs to be a multiple of 4 (5.8) */ 488 static void dccp_insert_option_padding(struct sk_buff *skb) 489 { 490 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4; 491 492 if (padding != 0) { 493 padding = 4 - padding; 494 memset(skb_push(skb, padding), 0, padding); 495 DCCP_SKB_CB(skb)->dccpd_opt_len += padding; 496 } 497 } 498 499 int dccp_insert_options(struct sock *sk, struct sk_buff *skb) 500 { 501 struct dccp_sock *dp = dccp_sk(sk); 502 503 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 504 505 if (dp->dccps_send_ndp_count && dccp_insert_option_ndp(sk, skb)) 506 return -1; 507 508 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA) { 509 510 /* Feature Negotiation */ 511 if (dccp_feat_insert_opts(dp, NULL, skb)) 512 return -1; 513 514 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST) { 515 /* 516 * Obtain RTT sample from Request/Response exchange. 517 * This is currently used for TFRC initialisation. 518 */ 519 if (dccp_insert_option_timestamp(skb)) 520 return -1; 521 522 } else if (dp->dccps_hc_rx_ackvec != NULL && 523 dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) && 524 dccp_insert_option_ackvec(sk, skb)) { 525 return -1; 526 } 527 } 528 529 if (dp->dccps_hc_rx_insert_options) { 530 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb)) 531 return -1; 532 dp->dccps_hc_rx_insert_options = 0; 533 } 534 535 if (dp->dccps_timestamp_echo != 0 && 536 dccp_insert_option_timestamp_echo(dp, NULL, skb)) 537 return -1; 538 539 dccp_insert_option_padding(skb); 540 return 0; 541 } 542 543 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb) 544 { 545 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 546 547 if (dccp_feat_insert_opts(NULL, dreq, skb)) 548 return -1; 549 550 /* Obtain RTT sample from Response/Ack exchange (used by TFRC). */ 551 if (dccp_insert_option_timestamp(skb)) 552 return -1; 553 554 if (dreq->dreq_timestamp_echo != 0 && 555 dccp_insert_option_timestamp_echo(NULL, dreq, skb)) 556 return -1; 557 558 dccp_insert_option_padding(skb); 559 return 0; 560 } 561