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 (pkt_type == DCCP_PKT_DATA) 136 break; 137 if (len < 2) 138 goto out_invalid_option; 139 rc = dccp_feat_change_recv(sk, opt, *value, value + 1, 140 len - 1); 141 /* 142 * When there is a change error, change_recv is 143 * responsible for dealing with it. i.e. reply with an 144 * empty confirm. 145 * If the change was mandatory, then we need to die. 146 */ 147 if (rc && mandatory) 148 goto out_invalid_option; 149 break; 150 case DCCPO_CONFIRM_L: 151 /* fall through */ 152 case DCCPO_CONFIRM_R: 153 if (pkt_type == DCCP_PKT_DATA) 154 break; 155 if (len < 2) /* FIXME this disallows empty confirm */ 156 goto out_invalid_option; 157 if (dccp_feat_confirm_recv(sk, opt, *value, 158 value + 1, len - 1)) 159 goto out_invalid_option; 160 break; 161 case DCCPO_ACK_VECTOR_0: 162 case DCCPO_ACK_VECTOR_1: 163 if (dccp_packet_without_ack(skb)) /* RFC 4340, 11.4 */ 164 break; 165 166 if (dccp_msk(sk)->dccpms_send_ack_vector && 167 dccp_ackvec_parse(sk, skb, &ackno, opt, value, len)) 168 goto out_invalid_option; 169 break; 170 case DCCPO_TIMESTAMP: 171 if (len != 4) 172 goto out_invalid_option; 173 /* 174 * RFC 4340 13.1: "The precise time corresponding to 175 * Timestamp Value zero is not specified". We use 176 * zero to indicate absence of a meaningful timestamp. 177 */ 178 opt_val = get_unaligned((__be32 *)value); 179 if (unlikely(opt_val == 0)) { 180 DCCP_WARN("Timestamp with zero value\n"); 181 break; 182 } 183 184 if (dreq != NULL) { 185 dreq->dreq_timestamp_echo = ntohl(opt_val); 186 dreq->dreq_timestamp_time = dccp_timestamp(); 187 } else { 188 opt_recv->dccpor_timestamp = 189 dp->dccps_timestamp_echo = ntohl(opt_val); 190 dp->dccps_timestamp_time = dccp_timestamp(); 191 } 192 dccp_pr_debug("%s rx opt: TIMESTAMP=%u, ackno=%llu\n", 193 dccp_role(sk), ntohl(opt_val), 194 (unsigned long long) 195 DCCP_SKB_CB(skb)->dccpd_ack_seq); 196 break; 197 case DCCPO_TIMESTAMP_ECHO: 198 if (len != 4 && len != 6 && len != 8) 199 goto out_invalid_option; 200 201 opt_val = get_unaligned((__be32 *)value); 202 opt_recv->dccpor_timestamp_echo = ntohl(opt_val); 203 204 dccp_pr_debug("%s rx opt: TIMESTAMP_ECHO=%u, len=%d, " 205 "ackno=%llu", dccp_role(sk), 206 opt_recv->dccpor_timestamp_echo, 207 len + 2, 208 (unsigned long long) 209 DCCP_SKB_CB(skb)->dccpd_ack_seq); 210 211 value += 4; 212 213 if (len == 4) { /* no elapsed time included */ 214 dccp_pr_debug_cat("\n"); 215 break; 216 } 217 218 if (len == 6) { /* 2-byte elapsed time */ 219 __be16 opt_val2 = get_unaligned((__be16 *)value); 220 elapsed_time = ntohs(opt_val2); 221 } else { /* 4-byte elapsed time */ 222 opt_val = get_unaligned((__be32 *)value); 223 elapsed_time = ntohl(opt_val); 224 } 225 226 dccp_pr_debug_cat(", ELAPSED_TIME=%u\n", elapsed_time); 227 228 /* Give precedence to the biggest ELAPSED_TIME */ 229 if (elapsed_time > opt_recv->dccpor_elapsed_time) 230 opt_recv->dccpor_elapsed_time = elapsed_time; 231 break; 232 case DCCPO_ELAPSED_TIME: 233 if (dccp_packet_without_ack(skb)) /* RFC 4340, 13.2 */ 234 break; 235 236 if (len == 2) { 237 __be16 opt_val2 = get_unaligned((__be16 *)value); 238 elapsed_time = ntohs(opt_val2); 239 } else if (len == 4) { 240 opt_val = get_unaligned((__be32 *)value); 241 elapsed_time = ntohl(opt_val); 242 } else { 243 goto out_invalid_option; 244 } 245 246 if (elapsed_time > opt_recv->dccpor_elapsed_time) 247 opt_recv->dccpor_elapsed_time = elapsed_time; 248 249 dccp_pr_debug("%s rx opt: ELAPSED_TIME=%d\n", 250 dccp_role(sk), elapsed_time); 251 break; 252 case 128 ... 191: { 253 const u16 idx = value - options; 254 255 if (ccid_hc_rx_parse_options(dp->dccps_hc_rx_ccid, sk, 256 opt, len, idx, 257 value) != 0) 258 goto out_invalid_option; 259 } 260 break; 261 case 192 ... 255: { 262 const u16 idx = value - options; 263 264 if (ccid_hc_tx_parse_options(dp->dccps_hc_tx_ccid, sk, 265 opt, len, idx, 266 value) != 0) 267 goto out_invalid_option; 268 } 269 break; 270 default: 271 DCCP_CRIT("DCCP(%p): option %d(len=%d) not " 272 "implemented, ignoring", sk, opt, len); 273 break; 274 } 275 ignore_option: 276 if (opt != DCCPO_MANDATORY) 277 mandatory = 0; 278 } 279 280 /* mandatory was the last byte in option list -> reset connection */ 281 if (mandatory) 282 goto out_invalid_option; 283 284 return 0; 285 286 out_invalid_option: 287 DCCP_INC_STATS_BH(DCCP_MIB_INVALIDOPT); 288 DCCP_SKB_CB(skb)->dccpd_reset_code = DCCP_RESET_CODE_OPTION_ERROR; 289 DCCP_WARN("DCCP(%p): invalid option %d, len=%d", sk, opt, len); 290 return -1; 291 } 292 293 EXPORT_SYMBOL_GPL(dccp_parse_options); 294 295 static void dccp_encode_value_var(const u32 value, unsigned char *to, 296 const unsigned int len) 297 { 298 if (len > 3) 299 *to++ = (value & 0xFF000000) >> 24; 300 if (len > 2) 301 *to++ = (value & 0xFF0000) >> 16; 302 if (len > 1) 303 *to++ = (value & 0xFF00) >> 8; 304 if (len > 0) 305 *to++ = (value & 0xFF); 306 } 307 308 static inline int dccp_ndp_len(const int ndp) 309 { 310 return likely(ndp <= 0xFF) ? 1 : ndp <= 0xFFFF ? 2 : 3; 311 } 312 313 int dccp_insert_option(struct sock *sk, struct sk_buff *skb, 314 const unsigned char option, 315 const void *value, const unsigned char len) 316 { 317 unsigned char *to; 318 319 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 2 > DCCP_MAX_OPT_LEN) 320 return -1; 321 322 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 2; 323 324 to = skb_push(skb, len + 2); 325 *to++ = option; 326 *to++ = len + 2; 327 328 memcpy(to, value, len); 329 return 0; 330 } 331 332 EXPORT_SYMBOL_GPL(dccp_insert_option); 333 334 static int dccp_insert_option_ndp(struct sock *sk, struct sk_buff *skb) 335 { 336 struct dccp_sock *dp = dccp_sk(sk); 337 int ndp = dp->dccps_ndp_count; 338 339 if (dccp_non_data_packet(skb)) 340 ++dp->dccps_ndp_count; 341 else 342 dp->dccps_ndp_count = 0; 343 344 if (ndp > 0) { 345 unsigned char *ptr; 346 const int ndp_len = dccp_ndp_len(ndp); 347 const int len = ndp_len + 2; 348 349 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 350 return -1; 351 352 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 353 354 ptr = skb_push(skb, len); 355 *ptr++ = DCCPO_NDP_COUNT; 356 *ptr++ = len; 357 dccp_encode_value_var(ndp, ptr, ndp_len); 358 } 359 360 return 0; 361 } 362 363 static inline int dccp_elapsed_time_len(const u32 elapsed_time) 364 { 365 return elapsed_time == 0 ? 0 : elapsed_time <= 0xFFFF ? 2 : 4; 366 } 367 368 int dccp_insert_option_elapsed_time(struct sock *sk, struct sk_buff *skb, 369 u32 elapsed_time) 370 { 371 const int elapsed_time_len = dccp_elapsed_time_len(elapsed_time); 372 const int len = 2 + elapsed_time_len; 373 unsigned char *to; 374 375 if (elapsed_time_len == 0) 376 return 0; 377 378 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 379 return -1; 380 381 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 382 383 to = skb_push(skb, len); 384 *to++ = DCCPO_ELAPSED_TIME; 385 *to++ = len; 386 387 if (elapsed_time_len == 2) { 388 const __be16 var16 = htons((u16)elapsed_time); 389 memcpy(to, &var16, 2); 390 } else { 391 const __be32 var32 = htonl(elapsed_time); 392 memcpy(to, &var32, 4); 393 } 394 395 return 0; 396 } 397 398 EXPORT_SYMBOL_GPL(dccp_insert_option_elapsed_time); 399 400 int dccp_insert_option_timestamp(struct sock *sk, struct sk_buff *skb) 401 { 402 __be32 now = htonl(dccp_timestamp()); 403 /* yes this will overflow but that is the point as we want a 404 * 10 usec 32 bit timer which mean it wraps every 11.9 hours */ 405 406 return dccp_insert_option(sk, skb, DCCPO_TIMESTAMP, &now, sizeof(now)); 407 } 408 409 EXPORT_SYMBOL_GPL(dccp_insert_option_timestamp); 410 411 static int dccp_insert_option_timestamp_echo(struct dccp_sock *dp, 412 struct dccp_request_sock *dreq, 413 struct sk_buff *skb) 414 { 415 __be32 tstamp_echo; 416 unsigned char *to; 417 u32 elapsed_time, elapsed_time_len, len; 418 419 if (dreq != NULL) { 420 elapsed_time = dccp_timestamp() - dreq->dreq_timestamp_time; 421 tstamp_echo = htonl(dreq->dreq_timestamp_echo); 422 dreq->dreq_timestamp_echo = 0; 423 } else { 424 elapsed_time = dccp_timestamp() - dp->dccps_timestamp_time; 425 tstamp_echo = htonl(dp->dccps_timestamp_echo); 426 dp->dccps_timestamp_echo = 0; 427 } 428 429 elapsed_time_len = dccp_elapsed_time_len(elapsed_time); 430 len = 6 + elapsed_time_len; 431 432 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len > DCCP_MAX_OPT_LEN) 433 return -1; 434 435 DCCP_SKB_CB(skb)->dccpd_opt_len += len; 436 437 to = skb_push(skb, len); 438 *to++ = DCCPO_TIMESTAMP_ECHO; 439 *to++ = len; 440 441 memcpy(to, &tstamp_echo, 4); 442 to += 4; 443 444 if (elapsed_time_len == 2) { 445 const __be16 var16 = htons((u16)elapsed_time); 446 memcpy(to, &var16, 2); 447 } else if (elapsed_time_len == 4) { 448 const __be32 var32 = htonl(elapsed_time); 449 memcpy(to, &var32, 4); 450 } 451 452 return 0; 453 } 454 455 static int dccp_insert_feat_opt(struct sk_buff *skb, u8 type, u8 feat, 456 u8 *val, u8 len) 457 { 458 u8 *to; 459 460 if (DCCP_SKB_CB(skb)->dccpd_opt_len + len + 3 > DCCP_MAX_OPT_LEN) { 461 DCCP_WARN("packet too small for feature %d option!\n", feat); 462 return -1; 463 } 464 465 DCCP_SKB_CB(skb)->dccpd_opt_len += len + 3; 466 467 to = skb_push(skb, len + 3); 468 *to++ = type; 469 *to++ = len + 3; 470 *to++ = feat; 471 472 if (len) 473 memcpy(to, val, len); 474 475 dccp_pr_debug("%s(%s (%d), ...), length %d\n", 476 dccp_feat_typename(type), 477 dccp_feat_name(feat), feat, len); 478 return 0; 479 } 480 481 static int dccp_insert_options_feat(struct sock *sk, struct sk_buff *skb) 482 { 483 struct dccp_sock *dp = dccp_sk(sk); 484 struct dccp_minisock *dmsk = dccp_msk(sk); 485 struct dccp_opt_pend *opt, *next; 486 int change = 0; 487 488 /* confirm any options [NN opts] */ 489 list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) { 490 dccp_insert_feat_opt(skb, opt->dccpop_type, 491 opt->dccpop_feat, opt->dccpop_val, 492 opt->dccpop_len); 493 /* fear empty confirms */ 494 if (opt->dccpop_val) 495 kfree(opt->dccpop_val); 496 kfree(opt); 497 } 498 INIT_LIST_HEAD(&dmsk->dccpms_conf); 499 500 /* see which features we need to send */ 501 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) { 502 /* see if we need to send any confirm */ 503 if (opt->dccpop_sc) { 504 dccp_insert_feat_opt(skb, opt->dccpop_type + 1, 505 opt->dccpop_feat, 506 opt->dccpop_sc->dccpoc_val, 507 opt->dccpop_sc->dccpoc_len); 508 509 BUG_ON(!opt->dccpop_sc->dccpoc_val); 510 kfree(opt->dccpop_sc->dccpoc_val); 511 kfree(opt->dccpop_sc); 512 opt->dccpop_sc = NULL; 513 } 514 515 /* any option not confirmed, re-send it */ 516 if (!opt->dccpop_conf) { 517 dccp_insert_feat_opt(skb, opt->dccpop_type, 518 opt->dccpop_feat, opt->dccpop_val, 519 opt->dccpop_len); 520 change++; 521 } 522 } 523 524 /* Retransmit timer. 525 * If this is the master listening sock, we don't set a timer on it. It 526 * should be fine because if the dude doesn't receive our RESPONSE 527 * [which will contain the CHANGE] he will send another REQUEST which 528 * will "retrnasmit" the change. 529 */ 530 if (change && dp->dccps_role != DCCP_ROLE_LISTEN) { 531 dccp_pr_debug("reset feat negotiation timer %p\n", sk); 532 533 /* XXX don't reset the timer on re-transmissions. I.e. reset it 534 * only when sending new stuff i guess. Currently the timer 535 * never backs off because on re-transmission it just resets it! 536 */ 537 inet_csk_reset_xmit_timer(sk, ICSK_TIME_RETRANS, 538 inet_csk(sk)->icsk_rto, DCCP_RTO_MAX); 539 } 540 541 return 0; 542 } 543 544 /* The length of all options needs to be a multiple of 4 (5.8) */ 545 static void dccp_insert_option_padding(struct sk_buff *skb) 546 { 547 int padding = DCCP_SKB_CB(skb)->dccpd_opt_len % 4; 548 549 if (padding != 0) { 550 padding = 4 - padding; 551 memset(skb_push(skb, padding), 0, padding); 552 DCCP_SKB_CB(skb)->dccpd_opt_len += padding; 553 } 554 } 555 556 int dccp_insert_options(struct sock *sk, struct sk_buff *skb) 557 { 558 struct dccp_sock *dp = dccp_sk(sk); 559 struct dccp_minisock *dmsk = dccp_msk(sk); 560 561 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 562 563 if (dmsk->dccpms_send_ndp_count && 564 dccp_insert_option_ndp(sk, skb)) 565 return -1; 566 567 if (!dccp_packet_without_ack(skb)) { 568 if (dmsk->dccpms_send_ack_vector && 569 dccp_ackvec_pending(dp->dccps_hc_rx_ackvec) && 570 dccp_insert_option_ackvec(sk, skb)) 571 return -1; 572 } 573 574 if (dp->dccps_hc_rx_insert_options) { 575 if (ccid_hc_rx_insert_options(dp->dccps_hc_rx_ccid, sk, skb)) 576 return -1; 577 dp->dccps_hc_rx_insert_options = 0; 578 } 579 580 /* Feature negotiation */ 581 /* Data packets can't do feat negotiation */ 582 if (DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATA && 583 DCCP_SKB_CB(skb)->dccpd_type != DCCP_PKT_DATAACK && 584 dccp_insert_options_feat(sk, skb)) 585 return -1; 586 587 /* 588 * Obtain RTT sample from Request/Response exchange. 589 * This is currently used in CCID 3 initialisation. 590 */ 591 if (DCCP_SKB_CB(skb)->dccpd_type == DCCP_PKT_REQUEST && 592 dccp_insert_option_timestamp(sk, skb)) 593 return -1; 594 595 if (dp->dccps_timestamp_echo != 0 && 596 dccp_insert_option_timestamp_echo(dp, NULL, skb)) 597 return -1; 598 599 dccp_insert_option_padding(skb); 600 return 0; 601 } 602 603 int dccp_insert_options_rsk(struct dccp_request_sock *dreq, struct sk_buff *skb) 604 { 605 DCCP_SKB_CB(skb)->dccpd_opt_len = 0; 606 607 if (dreq->dreq_timestamp_echo != 0 && 608 dccp_insert_option_timestamp_echo(NULL, dreq, skb)) 609 return -1; 610 611 dccp_insert_option_padding(skb); 612 return 0; 613 } 614