1/* 2 * net/dccp/feat.c 3 * 4 * Feature negotiation for the DCCP protocol (RFC 4340, section 6) 5 * 6 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk> 7 * Rewrote from scratch, some bits from earlier code by 8 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> 9 * 10 * 11 * ASSUMPTIONS 12 * ----------- 13 * o Feature negotiation is coordinated with connection setup (as in TCP), wild 14 * changes of parameters of an established connection are not supported. 15 * o Changing non-negotiable (NN) values is supported in state OPEN/PARTOPEN. 16 * o All currently known SP features have 1-byte quantities. If in the future 17 * extensions of RFCs 4340..42 define features with item lengths larger than 18 * one byte, a feature-specific extension of the code will be required. 19 * 20 * This program is free software; you can redistribute it and/or 21 * modify it under the terms of the GNU General Public License 22 * as published by the Free Software Foundation; either version 23 * 2 of the License, or (at your option) any later version. 24 */ 25#include <linux/module.h> 26#include <linux/slab.h> 27#include "ccid.h" 28#include "feat.h" 29 30/* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */ 31unsigned long sysctl_dccp_sequence_window __read_mostly = 100; 32int sysctl_dccp_rx_ccid __read_mostly = 2, 33 sysctl_dccp_tx_ccid __read_mostly = 2; 34 35/* 36 * Feature activation handlers. 37 * 38 * These all use an u64 argument, to provide enough room for NN/SP features. At 39 * this stage the negotiated values have been checked to be within their range. 40 */ 41static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx) 42{ 43 struct dccp_sock *dp = dccp_sk(sk); 44 struct ccid *new_ccid = ccid_new(ccid, sk, rx); 45 46 if (new_ccid == NULL) 47 return -ENOMEM; 48 49 if (rx) { 50 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 51 dp->dccps_hc_rx_ccid = new_ccid; 52 } else { 53 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 54 dp->dccps_hc_tx_ccid = new_ccid; 55 } 56 return 0; 57} 58 59static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx) 60{ 61 struct dccp_sock *dp = dccp_sk(sk); 62 63 if (rx) { 64 dp->dccps_r_seq_win = seq_win; 65 /* propagate changes to update SWL/SWH */ 66 dccp_update_gsr(sk, dp->dccps_gsr); 67 } else { 68 dp->dccps_l_seq_win = seq_win; 69 /* propagate changes to update AWL */ 70 dccp_update_gss(sk, dp->dccps_gss); 71 } 72 return 0; 73} 74 75static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx) 76{ 77 if (rx) 78 dccp_sk(sk)->dccps_r_ack_ratio = ratio; 79 else 80 dccp_sk(sk)->dccps_l_ack_ratio = ratio; 81 return 0; 82} 83 84static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx) 85{ 86 struct dccp_sock *dp = dccp_sk(sk); 87 88 if (rx) { 89 if (enable && dp->dccps_hc_rx_ackvec == NULL) { 90 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any()); 91 if (dp->dccps_hc_rx_ackvec == NULL) 92 return -ENOMEM; 93 } else if (!enable) { 94 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 95 dp->dccps_hc_rx_ackvec = NULL; 96 } 97 } 98 return 0; 99} 100 101static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx) 102{ 103 if (!rx) 104 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0); 105 return 0; 106} 107 108/* 109 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that 110 * `rx' holds when the sending peer informs about his partial coverage via a 111 * ChangeR() option. In the other case, we are the sender and the receiver 112 * announces its coverage via ChangeL() options. The policy here is to honour 113 * such communication by enabling the corresponding partial coverage - but only 114 * if it has not been set manually before; the warning here means that all 115 * packets will be dropped. 116 */ 117static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx) 118{ 119 struct dccp_sock *dp = dccp_sk(sk); 120 121 if (rx) 122 dp->dccps_pcrlen = cscov; 123 else { 124 if (dp->dccps_pcslen == 0) 125 dp->dccps_pcslen = cscov; 126 else if (cscov > dp->dccps_pcslen) 127 DCCP_WARN("CsCov %u too small, peer requires >= %u\n", 128 dp->dccps_pcslen, (u8)cscov); 129 } 130 return 0; 131} 132 133static const struct { 134 u8 feat_num; /* DCCPF_xxx */ 135 enum dccp_feat_type rxtx; /* RX or TX */ 136 enum dccp_feat_type reconciliation; /* SP or NN */ 137 u8 default_value; /* as in 6.4 */ 138 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx); 139/* 140 * Lookup table for location and type of features (from RFC 4340/4342) 141 * +--------------------------+----+-----+----+----+---------+-----------+ 142 * | Feature | Location | Reconc. | Initial | Section | 143 * | | RX | TX | SP | NN | Value | Reference | 144 * +--------------------------+----+-----+----+----+---------+-----------+ 145 * | DCCPF_CCID | | X | X | | 2 | 10 | 146 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 | 147 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 | 148 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 | 149 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 | 150 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 | 151 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 | 152 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 | 153 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 | 154 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 | 155 * +--------------------------+----+-----+----+----+---------+-----------+ 156 */ 157} dccp_feat_table[] = { 158 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid }, 159 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL }, 160 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win }, 161 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL }, 162 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio}, 163 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec }, 164 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp }, 165 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov}, 166 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL }, 167 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL }, 168}; 169#define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table) 170 171/** 172 * dccp_feat_index - Hash function to map feature number into array position 173 * Returns consecutive array index or -1 if the feature is not understood. 174 */ 175static int dccp_feat_index(u8 feat_num) 176{ 177 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */ 178 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM) 179 return feat_num - 1; 180 181 /* 182 * Other features: add cases for new feature types here after adding 183 * them to the above table. 184 */ 185 switch (feat_num) { 186 case DCCPF_SEND_LEV_RATE: 187 return DCCP_FEAT_SUPPORTED_MAX - 1; 188 } 189 return -1; 190} 191 192static u8 dccp_feat_type(u8 feat_num) 193{ 194 int idx = dccp_feat_index(feat_num); 195 196 if (idx < 0) 197 return FEAT_UNKNOWN; 198 return dccp_feat_table[idx].reconciliation; 199} 200 201static int dccp_feat_default_value(u8 feat_num) 202{ 203 int idx = dccp_feat_index(feat_num); 204 /* 205 * There are no default values for unknown features, so encountering a 206 * negative index here indicates a serious problem somewhere else. 207 */ 208 DCCP_BUG_ON(idx < 0); 209 210 return idx < 0 ? 0 : dccp_feat_table[idx].default_value; 211} 212 213/* 214 * Debugging and verbose-printing section 215 */ 216static const char *dccp_feat_fname(const u8 feat) 217{ 218 static const char *const feature_names[] = { 219 [DCCPF_RESERVED] = "Reserved", 220 [DCCPF_CCID] = "CCID", 221 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos", 222 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window", 223 [DCCPF_ECN_INCAPABLE] = "ECN Incapable", 224 [DCCPF_ACK_RATIO] = "Ack Ratio", 225 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector", 226 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count", 227 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage", 228 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum", 229 }; 230 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC) 231 return feature_names[DCCPF_RESERVED]; 232 233 if (feat == DCCPF_SEND_LEV_RATE) 234 return "Send Loss Event Rate"; 235 if (feat >= DCCPF_MIN_CCID_SPECIFIC) 236 return "CCID-specific"; 237 238 return feature_names[feat]; 239} 240 241static const char *const dccp_feat_sname[] = { 242 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE", 243}; 244 245#ifdef CONFIG_IP_DCCP_DEBUG 246static const char *dccp_feat_oname(const u8 opt) 247{ 248 switch (opt) { 249 case DCCPO_CHANGE_L: return "Change_L"; 250 case DCCPO_CONFIRM_L: return "Confirm_L"; 251 case DCCPO_CHANGE_R: return "Change_R"; 252 case DCCPO_CONFIRM_R: return "Confirm_R"; 253 } 254 return NULL; 255} 256 257static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val) 258{ 259 u8 i, type = dccp_feat_type(feat_num); 260 261 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL)) 262 dccp_pr_debug_cat("(NULL)"); 263 else if (type == FEAT_SP) 264 for (i = 0; i < val->sp.len; i++) 265 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]); 266 else if (type == FEAT_NN) 267 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn); 268 else 269 dccp_pr_debug_cat("unknown type %u", type); 270} 271 272static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len) 273{ 274 u8 type = dccp_feat_type(feat_num); 275 dccp_feat_val fval = { .sp.vec = list, .sp.len = len }; 276 277 if (type == FEAT_NN) 278 fval.nn = dccp_decode_value_var(list, len); 279 dccp_feat_printval(feat_num, &fval); 280} 281 282static void dccp_feat_print_entry(struct dccp_feat_entry const *entry) 283{ 284 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote", 285 dccp_feat_fname(entry->feat_num)); 286 dccp_feat_printval(entry->feat_num, &entry->val); 287 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state], 288 entry->needs_confirm ? "(Confirm pending)" : ""); 289} 290 291#define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \ 292 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\ 293 dccp_feat_printvals(feat, val, len); \ 294 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0) 295 296#define dccp_feat_print_fnlist(fn_list) { \ 297 const struct dccp_feat_entry *___entry; \ 298 \ 299 dccp_pr_debug("List Dump:\n"); \ 300 list_for_each_entry(___entry, fn_list, node) \ 301 dccp_feat_print_entry(___entry); \ 302} 303#else /* ! CONFIG_IP_DCCP_DEBUG */ 304#define dccp_feat_print_opt(opt, feat, val, len, mandatory) 305#define dccp_feat_print_fnlist(fn_list) 306#endif 307 308static int __dccp_feat_activate(struct sock *sk, const int idx, 309 const bool is_local, dccp_feat_val const *fval) 310{ 311 bool rx; 312 u64 val; 313 314 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX) 315 return -1; 316 if (dccp_feat_table[idx].activation_hdlr == NULL) 317 return 0; 318 319 if (fval == NULL) { 320 val = dccp_feat_table[idx].default_value; 321 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) { 322 if (fval->sp.vec == NULL) { 323 /* 324 * This can happen when an empty Confirm is sent 325 * for an SP (i.e. known) feature. In this case 326 * we would be using the default anyway. 327 */ 328 DCCP_CRIT("Feature #%d undefined: using default", idx); 329 val = dccp_feat_table[idx].default_value; 330 } else { 331 val = fval->sp.vec[0]; 332 } 333 } else { 334 val = fval->nn; 335 } 336 337 /* Location is RX if this is a local-RX or remote-TX feature */ 338 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX)); 339 340 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX", 341 dccp_feat_fname(dccp_feat_table[idx].feat_num), 342 fval ? "" : "default ", (unsigned long long)val); 343 344 return dccp_feat_table[idx].activation_hdlr(sk, val, rx); 345} 346 347/** 348 * dccp_feat_activate - Activate feature value on socket 349 * @sk: fully connected DCCP socket (after handshake is complete) 350 * @feat_num: feature to activate, one of %dccp_feature_numbers 351 * @local: whether local (1) or remote (0) @feat_num is meant 352 * @fval: the value (SP or NN) to activate, or NULL to use the default value 353 * 354 * For general use this function is preferable over __dccp_feat_activate(). 355 */ 356static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local, 357 dccp_feat_val const *fval) 358{ 359 return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval); 360} 361 362/* Test for "Req'd" feature (RFC 4340, 6.4) */ 363static inline int dccp_feat_must_be_understood(u8 feat_num) 364{ 365 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS || 366 feat_num == DCCPF_SEQUENCE_WINDOW; 367} 368 369/* copy constructor, fval must not already contain allocated memory */ 370static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len) 371{ 372 fval->sp.len = len; 373 if (fval->sp.len > 0) { 374 fval->sp.vec = kmemdup(val, len, gfp_any()); 375 if (fval->sp.vec == NULL) { 376 fval->sp.len = 0; 377 return -ENOBUFS; 378 } 379 } 380 return 0; 381} 382 383static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val) 384{ 385 if (unlikely(val == NULL)) 386 return; 387 if (dccp_feat_type(feat_num) == FEAT_SP) 388 kfree(val->sp.vec); 389 memset(val, 0, sizeof(*val)); 390} 391 392static struct dccp_feat_entry * 393 dccp_feat_clone_entry(struct dccp_feat_entry const *original) 394{ 395 struct dccp_feat_entry *new; 396 u8 type = dccp_feat_type(original->feat_num); 397 398 if (type == FEAT_UNKNOWN) 399 return NULL; 400 401 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any()); 402 if (new == NULL) 403 return NULL; 404 405 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val, 406 original->val.sp.vec, 407 original->val.sp.len)) { 408 kfree(new); 409 return NULL; 410 } 411 return new; 412} 413 414static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry) 415{ 416 if (entry != NULL) { 417 dccp_feat_val_destructor(entry->feat_num, &entry->val); 418 kfree(entry); 419 } 420} 421 422/* 423 * List management functions 424 * 425 * Feature negotiation lists rely on and maintain the following invariants: 426 * - each feat_num in the list is known, i.e. we know its type and default value 427 * - each feat_num/is_local combination is unique (old entries are overwritten) 428 * - SP values are always freshly allocated 429 * - list is sorted in increasing order of feature number (faster lookup) 430 */ 431static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list, 432 u8 feat_num, bool is_local) 433{ 434 struct dccp_feat_entry *entry; 435 436 list_for_each_entry(entry, fn_list, node) { 437 if (entry->feat_num == feat_num && entry->is_local == is_local) 438 return entry; 439 else if (entry->feat_num > feat_num) 440 break; 441 } 442 return NULL; 443} 444 445/** 446 * dccp_feat_entry_new - Central list update routine (called by all others) 447 * @head: list to add to 448 * @feat: feature number 449 * @local: whether the local (1) or remote feature with number @feat is meant 450 * 451 * This is the only constructor and serves to ensure the above invariants. 452 */ 453static struct dccp_feat_entry * 454 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local) 455{ 456 struct dccp_feat_entry *entry; 457 458 list_for_each_entry(entry, head, node) 459 if (entry->feat_num == feat && entry->is_local == local) { 460 dccp_feat_val_destructor(entry->feat_num, &entry->val); 461 return entry; 462 } else if (entry->feat_num > feat) { 463 head = &entry->node; 464 break; 465 } 466 467 entry = kmalloc(sizeof(*entry), gfp_any()); 468 if (entry != NULL) { 469 entry->feat_num = feat; 470 entry->is_local = local; 471 list_add_tail(&entry->node, head); 472 } 473 return entry; 474} 475 476/** 477 * dccp_feat_push_change - Add/overwrite a Change option in the list 478 * @fn_list: feature-negotiation list to update 479 * @feat: one of %dccp_feature_numbers 480 * @local: whether local (1) or remote (0) @feat_num is meant 481 * @needs_mandatory: whether to use Mandatory feature negotiation options 482 * @fval: pointer to NN/SP value to be inserted (will be copied) 483 */ 484static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local, 485 u8 mandatory, dccp_feat_val *fval) 486{ 487 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 488 489 if (new == NULL) 490 return -ENOMEM; 491 492 new->feat_num = feat; 493 new->is_local = local; 494 new->state = FEAT_INITIALISING; 495 new->needs_confirm = false; 496 new->empty_confirm = false; 497 new->val = *fval; 498 new->needs_mandatory = mandatory; 499 500 return 0; 501} 502 503/** 504 * dccp_feat_push_confirm - Add a Confirm entry to the FN list 505 * @fn_list: feature-negotiation list to add to 506 * @feat: one of %dccp_feature_numbers 507 * @local: whether local (1) or remote (0) @feat_num is being confirmed 508 * @fval: pointer to NN/SP value to be inserted or NULL 509 * 510 * Returns 0 on success, a Reset code for further processing otherwise. 511 */ 512static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local, 513 dccp_feat_val *fval) 514{ 515 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 516 517 if (new == NULL) 518 return DCCP_RESET_CODE_TOO_BUSY; 519 520 new->feat_num = feat; 521 new->is_local = local; 522 new->state = FEAT_STABLE; /* transition in 6.6.2 */ 523 new->needs_confirm = true; 524 new->empty_confirm = (fval == NULL); 525 new->val.nn = 0; /* zeroes the whole structure */ 526 if (!new->empty_confirm) 527 new->val = *fval; 528 new->needs_mandatory = false; 529 530 return 0; 531} 532 533static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local) 534{ 535 return dccp_feat_push_confirm(fn_list, feat, local, NULL); 536} 537 538static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry) 539{ 540 list_del(&entry->node); 541 dccp_feat_entry_destructor(entry); 542} 543 544void dccp_feat_list_purge(struct list_head *fn_list) 545{ 546 struct dccp_feat_entry *entry, *next; 547 548 list_for_each_entry_safe(entry, next, fn_list, node) 549 dccp_feat_entry_destructor(entry); 550 INIT_LIST_HEAD(fn_list); 551} 552EXPORT_SYMBOL_GPL(dccp_feat_list_purge); 553 554/* generate @to as full clone of @from - @to must not contain any nodes */ 555int dccp_feat_clone_list(struct list_head const *from, struct list_head *to) 556{ 557 struct dccp_feat_entry *entry, *new; 558 559 INIT_LIST_HEAD(to); 560 list_for_each_entry(entry, from, node) { 561 new = dccp_feat_clone_entry(entry); 562 if (new == NULL) 563 goto cloning_failed; 564 list_add_tail(&new->node, to); 565 } 566 return 0; 567 568cloning_failed: 569 dccp_feat_list_purge(to); 570 return -ENOMEM; 571} 572 573/** 574 * dccp_feat_valid_nn_length - Enforce length constraints on NN options 575 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only, 576 * incoming options are accepted as long as their values are valid. 577 */ 578static u8 dccp_feat_valid_nn_length(u8 feat_num) 579{ 580 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */ 581 return 2; 582 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */ 583 return 6; 584 return 0; 585} 586 587static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val) 588{ 589 switch (feat_num) { 590 case DCCPF_ACK_RATIO: 591 return val <= DCCPF_ACK_RATIO_MAX; 592 case DCCPF_SEQUENCE_WINDOW: 593 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX; 594 } 595 return 0; /* feature unknown - so we can't tell */ 596} 597 598/* check that SP values are within the ranges defined in RFC 4340 */ 599static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val) 600{ 601 switch (feat_num) { 602 case DCCPF_CCID: 603 return val == DCCPC_CCID2 || val == DCCPC_CCID3; 604 /* Type-check Boolean feature values: */ 605 case DCCPF_SHORT_SEQNOS: 606 case DCCPF_ECN_INCAPABLE: 607 case DCCPF_SEND_ACK_VECTOR: 608 case DCCPF_SEND_NDP_COUNT: 609 case DCCPF_DATA_CHECKSUM: 610 case DCCPF_SEND_LEV_RATE: 611 return val < 2; 612 case DCCPF_MIN_CSUM_COVER: 613 return val < 16; 614 } 615 return 0; /* feature unknown */ 616} 617 618static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len) 619{ 620 if (sp_list == NULL || sp_len < 1) 621 return 0; 622 while (sp_len--) 623 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++)) 624 return 0; 625 return 1; 626} 627 628/** 629 * dccp_feat_insert_opts - Generate FN options from current list state 630 * @skb: next sk_buff to be sent to the peer 631 * @dp: for client during handshake and general negotiation 632 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND) 633 */ 634int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq, 635 struct sk_buff *skb) 636{ 637 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 638 struct dccp_feat_entry *pos, *next; 639 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN]; 640 bool rpt; 641 642 /* put entries into @skb in the order they appear in the list */ 643 list_for_each_entry_safe_reverse(pos, next, fn, node) { 644 opt = dccp_feat_genopt(pos); 645 type = dccp_feat_type(pos->feat_num); 646 rpt = false; 647 648 if (pos->empty_confirm) { 649 len = 0; 650 ptr = NULL; 651 } else { 652 if (type == FEAT_SP) { 653 len = pos->val.sp.len; 654 ptr = pos->val.sp.vec; 655 rpt = pos->needs_confirm; 656 } else if (type == FEAT_NN) { 657 len = dccp_feat_valid_nn_length(pos->feat_num); 658 ptr = nn_in_nbo; 659 dccp_encode_value_var(pos->val.nn, ptr, len); 660 } else { 661 DCCP_BUG("unknown feature %u", pos->feat_num); 662 return -1; 663 } 664 } 665 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0); 666 667 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt)) 668 return -1; 669 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb)) 670 return -1; 671 672 if (skb->sk->sk_state == DCCP_OPEN && 673 (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) { 674 /* 675 * Confirms don't get retransmitted (6.6.3) once the 676 * connection is in state OPEN 677 */ 678 dccp_feat_list_pop(pos); 679 } else { 680 /* 681 * Enter CHANGING after transmitting the Change 682 * option (6.6.2). 683 */ 684 if (pos->state == FEAT_INITIALISING) 685 pos->state = FEAT_CHANGING; 686 } 687 } 688 return 0; 689} 690 691/** 692 * __feat_register_nn - Register new NN value on socket 693 * @fn: feature-negotiation list to register with 694 * @feat: an NN feature from %dccp_feature_numbers 695 * @mandatory: use Mandatory option if 1 696 * @nn_val: value to register (restricted to 4 bytes) 697 * 698 * Note that NN features are local by definition (RFC 4340, 6.3.2). 699 */ 700static int __feat_register_nn(struct list_head *fn, u8 feat, 701 u8 mandatory, u64 nn_val) 702{ 703 dccp_feat_val fval = { .nn = nn_val }; 704 705 if (dccp_feat_type(feat) != FEAT_NN || 706 !dccp_feat_is_valid_nn_val(feat, nn_val)) 707 return -EINVAL; 708 709 /* Don't bother with default values, they will be activated anyway. */ 710 if (nn_val - (u64)dccp_feat_default_value(feat) == 0) 711 return 0; 712 713 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval); 714} 715 716/** 717 * __feat_register_sp - Register new SP value/list on socket 718 * @fn: feature-negotiation list to register with 719 * @feat: an SP feature from %dccp_feature_numbers 720 * @is_local: whether the local (1) or the remote (0) @feat is meant 721 * @mandatory: use Mandatory option if 1 722 * @sp_val: SP value followed by optional preference list 723 * @sp_len: length of @sp_val in bytes 724 */ 725static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local, 726 u8 mandatory, u8 const *sp_val, u8 sp_len) 727{ 728 dccp_feat_val fval; 729 730 if (dccp_feat_type(feat) != FEAT_SP || 731 !dccp_feat_sp_list_ok(feat, sp_val, sp_len)) 732 return -EINVAL; 733 734 /* Avoid negotiating alien CCIDs by only advertising supported ones */ 735 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len)) 736 return -EOPNOTSUPP; 737 738 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len)) 739 return -ENOMEM; 740 741 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval); 742} 743 744/** 745 * dccp_feat_register_sp - Register requests to change SP feature values 746 * @sk: client or listening socket 747 * @feat: one of %dccp_feature_numbers 748 * @is_local: whether the local (1) or remote (0) @feat is meant 749 * @list: array of preferred values, in descending order of preference 750 * @len: length of @list in bytes 751 */ 752int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, 753 u8 const *list, u8 len) 754{ /* any changes must be registered before establishing the connection */ 755 if (sk->sk_state != DCCP_CLOSED) 756 return -EISCONN; 757 if (dccp_feat_type(feat) != FEAT_SP) 758 return -EINVAL; 759 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local, 760 0, list, len); 761} 762 763/** 764 * dccp_feat_nn_get - Query current/pending value of NN feature 765 * @sk: DCCP socket of an established connection 766 * @feat: NN feature number from %dccp_feature_numbers 767 * 768 * For a known NN feature, returns value currently being negotiated, or 769 * current (confirmed) value if no negotiation is going on. 770 */ 771u64 dccp_feat_nn_get(struct sock *sk, u8 feat) 772{ 773 if (dccp_feat_type(feat) == FEAT_NN) { 774 struct dccp_sock *dp = dccp_sk(sk); 775 struct dccp_feat_entry *entry; 776 777 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1); 778 if (entry != NULL) 779 return entry->val.nn; 780 781 switch (feat) { 782 case DCCPF_ACK_RATIO: 783 return dp->dccps_l_ack_ratio; 784 case DCCPF_SEQUENCE_WINDOW: 785 return dp->dccps_l_seq_win; 786 } 787 } 788 DCCP_BUG("attempt to look up unsupported feature %u", feat); 789 return 0; 790} 791EXPORT_SYMBOL_GPL(dccp_feat_nn_get); 792 793/** 794 * dccp_feat_signal_nn_change - Update NN values for an established connection 795 * @sk: DCCP socket of an established connection 796 * @feat: NN feature number from %dccp_feature_numbers 797 * @nn_val: the new value to use 798 * 799 * This function is used to communicate NN updates out-of-band. 800 */ 801int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val) 802{ 803 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 804 dccp_feat_val fval = { .nn = nn_val }; 805 struct dccp_feat_entry *entry; 806 807 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN) 808 return 0; 809 810 if (dccp_feat_type(feat) != FEAT_NN || 811 !dccp_feat_is_valid_nn_val(feat, nn_val)) 812 return -EINVAL; 813 814 if (nn_val == dccp_feat_nn_get(sk, feat)) 815 return 0; /* already set or negotiation under way */ 816 817 entry = dccp_feat_list_lookup(fn, feat, 1); 818 if (entry != NULL) { 819 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n", 820 (unsigned long long)entry->val.nn, 821 (unsigned long long)nn_val); 822 dccp_feat_list_pop(entry); 823 } 824 825 inet_csk_schedule_ack(sk); 826 return dccp_feat_push_change(fn, feat, 1, 0, &fval); 827} 828EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change); 829 830/* 831 * Tracking features whose value depend on the choice of CCID 832 * 833 * This is designed with an extension in mind so that a list walk could be done 834 * before activating any features. However, the existing framework was found to 835 * work satisfactorily up until now, the automatic verification is left open. 836 * When adding new CCIDs, add a corresponding dependency table here. 837 */ 838static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local) 839{ 840 static const struct ccid_dependency ccid2_dependencies[2][2] = { 841 /* 842 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX 843 * feature and Send Ack Vector is an RX feature, `is_local' 844 * needs to be reversed. 845 */ 846 { /* Dependencies of the receiver-side (remote) CCID2 */ 847 { 848 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 849 .is_local = true, 850 .is_mandatory = true, 851 .val = 1 852 }, 853 { 0, 0, 0, 0 } 854 }, 855 { /* Dependencies of the sender-side (local) CCID2 */ 856 { 857 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 858 .is_local = false, 859 .is_mandatory = true, 860 .val = 1 861 }, 862 { 0, 0, 0, 0 } 863 } 864 }; 865 static const struct ccid_dependency ccid3_dependencies[2][5] = { 866 { /* 867 * Dependencies of the receiver-side CCID3 868 */ 869 { /* locally disable Ack Vectors */ 870 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 871 .is_local = true, 872 .is_mandatory = false, 873 .val = 0 874 }, 875 { /* see below why Send Loss Event Rate is on */ 876 .dependent_feat = DCCPF_SEND_LEV_RATE, 877 .is_local = true, 878 .is_mandatory = true, 879 .val = 1 880 }, 881 { /* NDP Count is needed as per RFC 4342, 6.1.1 */ 882 .dependent_feat = DCCPF_SEND_NDP_COUNT, 883 .is_local = false, 884 .is_mandatory = true, 885 .val = 1 886 }, 887 { 0, 0, 0, 0 }, 888 }, 889 { /* 890 * CCID3 at the TX side: we request that the HC-receiver 891 * will not send Ack Vectors (they will be ignored, so 892 * Mandatory is not set); we enable Send Loss Event Rate 893 * (Mandatory since the implementation does not support 894 * the Loss Intervals option of RFC 4342, 8.6). 895 * The last two options are for peer's information only. 896 */ 897 { 898 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 899 .is_local = false, 900 .is_mandatory = false, 901 .val = 0 902 }, 903 { 904 .dependent_feat = DCCPF_SEND_LEV_RATE, 905 .is_local = false, 906 .is_mandatory = true, 907 .val = 1 908 }, 909 { /* this CCID does not support Ack Ratio */ 910 .dependent_feat = DCCPF_ACK_RATIO, 911 .is_local = true, 912 .is_mandatory = false, 913 .val = 0 914 }, 915 { /* tell receiver we are sending NDP counts */ 916 .dependent_feat = DCCPF_SEND_NDP_COUNT, 917 .is_local = true, 918 .is_mandatory = false, 919 .val = 1 920 }, 921 { 0, 0, 0, 0 } 922 } 923 }; 924 switch (ccid) { 925 case DCCPC_CCID2: 926 return ccid2_dependencies[is_local]; 927 case DCCPC_CCID3: 928 return ccid3_dependencies[is_local]; 929 default: 930 return NULL; 931 } 932} 933 934/** 935 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID 936 * @fn: feature-negotiation list to update 937 * @id: CCID number to track 938 * @is_local: whether TX CCID (1) or RX CCID (0) is meant 939 * 940 * This function needs to be called after registering all other features. 941 */ 942static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local) 943{ 944 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local); 945 int i, rc = (table == NULL); 946 947 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++) 948 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP) 949 rc = __feat_register_sp(fn, table[i].dependent_feat, 950 table[i].is_local, 951 table[i].is_mandatory, 952 &table[i].val, 1); 953 else 954 rc = __feat_register_nn(fn, table[i].dependent_feat, 955 table[i].is_mandatory, 956 table[i].val); 957 return rc; 958} 959 960/** 961 * dccp_feat_finalise_settings - Finalise settings before starting negotiation 962 * @dp: client or listening socket (settings will be inherited) 963 * 964 * This is called after all registrations (socket initialisation, sysctls, and 965 * sockopt calls), and before sending the first packet containing Change options 966 * (ie. client-Request or server-Response), to ensure internal consistency. 967 */ 968int dccp_feat_finalise_settings(struct dccp_sock *dp) 969{ 970 struct list_head *fn = &dp->dccps_featneg; 971 struct dccp_feat_entry *entry; 972 int i = 2, ccids[2] = { -1, -1 }; 973 974 /* 975 * Propagating CCIDs: 976 * 1) not useful to propagate CCID settings if this host advertises more 977 * than one CCID: the choice of CCID may still change - if this is 978 * the client, or if this is the server and the client sends 979 * singleton CCID values. 980 * 2) since is that propagate_ccid changes the list, we defer changing 981 * the sorted list until after the traversal. 982 */ 983 list_for_each_entry(entry, fn, node) 984 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1) 985 ccids[entry->is_local] = entry->val.sp.vec[0]; 986 while (i--) 987 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i)) 988 return -1; 989 dccp_feat_print_fnlist(fn); 990 return 0; 991} 992 993/** 994 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features 995 * It is the server which resolves the dependencies once the CCID has been 996 * fully negotiated. If no CCID has been negotiated, it uses the default CCID. 997 */ 998int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq) 999{ 1000 struct list_head *fn = &dreq->dreq_featneg; 1001 struct dccp_feat_entry *entry; 1002 u8 is_local, ccid; 1003 1004 for (is_local = 0; is_local <= 1; is_local++) { 1005 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local); 1006 1007 if (entry != NULL && !entry->empty_confirm) 1008 ccid = entry->val.sp.vec[0]; 1009 else 1010 ccid = dccp_feat_default_value(DCCPF_CCID); 1011 1012 if (dccp_feat_propagate_ccid(fn, ccid, is_local)) 1013 return -1; 1014 } 1015 return 0; 1016} 1017 1018/* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */ 1019static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen) 1020{ 1021 u8 c, s; 1022 1023 for (s = 0; s < slen; s++) 1024 for (c = 0; c < clen; c++) 1025 if (servlist[s] == clilist[c]) 1026 return servlist[s]; 1027 return -1; 1028} 1029 1030/** 1031 * dccp_feat_prefer - Move preferred entry to the start of array 1032 * Reorder the @array_len elements in @array so that @preferred_value comes 1033 * first. Returns >0 to indicate that @preferred_value does occur in @array. 1034 */ 1035static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len) 1036{ 1037 u8 i, does_occur = 0; 1038 1039 if (array != NULL) { 1040 for (i = 0; i < array_len; i++) 1041 if (array[i] == preferred_value) { 1042 array[i] = array[0]; 1043 does_occur++; 1044 } 1045 if (does_occur) 1046 array[0] = preferred_value; 1047 } 1048 return does_occur; 1049} 1050 1051/** 1052 * dccp_feat_reconcile - Reconcile SP preference lists 1053 * @fval: SP list to reconcile into 1054 * @arr: received SP preference list 1055 * @len: length of @arr in bytes 1056 * @is_server: whether this side is the server (and @fv is the server's list) 1057 * @reorder: whether to reorder the list in @fv after reconciling with @arr 1058 * When successful, > 0 is returned and the reconciled list is in @fval. 1059 * A value of 0 means that negotiation failed (no shared entry). 1060 */ 1061static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len, 1062 bool is_server, bool reorder) 1063{ 1064 int rc; 1065 1066 if (!fv->sp.vec || !arr) { 1067 DCCP_CRIT("NULL feature value or array"); 1068 return 0; 1069 } 1070 1071 if (is_server) 1072 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len); 1073 else 1074 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len); 1075 1076 if (!reorder) 1077 return rc; 1078 if (rc < 0) 1079 return 0; 1080 1081 /* 1082 * Reorder list: used for activating features and in dccp_insert_fn_opt. 1083 */ 1084 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len); 1085} 1086 1087/** 1088 * dccp_feat_change_recv - Process incoming ChangeL/R options 1089 * @fn: feature-negotiation list to update 1090 * @is_mandatory: whether the Change was preceded by a Mandatory option 1091 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R 1092 * @feat: one of %dccp_feature_numbers 1093 * @val: NN value or SP value/preference list 1094 * @len: length of @val in bytes 1095 * @server: whether this node is the server (1) or the client (0) 1096 */ 1097static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1098 u8 feat, u8 *val, u8 len, const bool server) 1099{ 1100 u8 defval, type = dccp_feat_type(feat); 1101 const bool local = (opt == DCCPO_CHANGE_R); 1102 struct dccp_feat_entry *entry; 1103 dccp_feat_val fval; 1104 1105 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */ 1106 goto unknown_feature_or_value; 1107 1108 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1109 1110 /* 1111 * Negotiation of NN features: Change R is invalid, so there is no 1112 * simultaneous negotiation; hence we do not look up in the list. 1113 */ 1114 if (type == FEAT_NN) { 1115 if (local || len > sizeof(fval.nn)) 1116 goto unknown_feature_or_value; 1117 1118 /* 6.3.2: "The feature remote MUST accept any valid value..." */ 1119 fval.nn = dccp_decode_value_var(val, len); 1120 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1121 goto unknown_feature_or_value; 1122 1123 return dccp_feat_push_confirm(fn, feat, local, &fval); 1124 } 1125 1126 /* 1127 * Unidirectional/simultaneous negotiation of SP features (6.3.1) 1128 */ 1129 entry = dccp_feat_list_lookup(fn, feat, local); 1130 if (entry == NULL) { 1131 /* 1132 * No particular preferences have been registered. We deal with 1133 * this situation by assuming that all valid values are equally 1134 * acceptable, and apply the following checks: 1135 * - if the peer's list is a singleton, we accept a valid value; 1136 * - if we are the server, we first try to see if the peer (the 1137 * client) advertises the default value. If yes, we use it, 1138 * otherwise we accept the preferred value; 1139 * - else if we are the client, we use the first list element. 1140 */ 1141 if (dccp_feat_clone_sp_val(&fval, val, 1)) 1142 return DCCP_RESET_CODE_TOO_BUSY; 1143 1144 if (len > 1 && server) { 1145 defval = dccp_feat_default_value(feat); 1146 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1) 1147 fval.sp.vec[0] = defval; 1148 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) { 1149 kfree(fval.sp.vec); 1150 goto unknown_feature_or_value; 1151 } 1152 1153 /* Treat unsupported CCIDs like invalid values */ 1154 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) { 1155 kfree(fval.sp.vec); 1156 goto not_valid_or_not_known; 1157 } 1158 1159 return dccp_feat_push_confirm(fn, feat, local, &fval); 1160 1161 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */ 1162 return 0; 1163 } 1164 1165 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) { 1166 entry->empty_confirm = false; 1167 } else if (is_mandatory) { 1168 return DCCP_RESET_CODE_MANDATORY_ERROR; 1169 } else if (entry->state == FEAT_INITIALISING) { 1170 /* 1171 * Failed simultaneous negotiation (server only): try to `save' 1172 * the connection by checking whether entry contains the default 1173 * value for @feat. If yes, send an empty Confirm to signal that 1174 * the received Change was not understood - which implies using 1175 * the default value. 1176 * If this also fails, we use Reset as the last resort. 1177 */ 1178 WARN_ON(!server); 1179 defval = dccp_feat_default_value(feat); 1180 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true)) 1181 return DCCP_RESET_CODE_OPTION_ERROR; 1182 entry->empty_confirm = true; 1183 } 1184 entry->needs_confirm = true; 1185 entry->needs_mandatory = false; 1186 entry->state = FEAT_STABLE; 1187 return 0; 1188 1189unknown_feature_or_value: 1190 if (!is_mandatory) 1191 return dccp_push_empty_confirm(fn, feat, local); 1192 1193not_valid_or_not_known: 1194 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1195 : DCCP_RESET_CODE_OPTION_ERROR; 1196} 1197 1198/** 1199 * dccp_feat_confirm_recv - Process received Confirm options 1200 * @fn: feature-negotiation list to update 1201 * @is_mandatory: whether @opt was preceded by a Mandatory option 1202 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R 1203 * @feat: one of %dccp_feature_numbers 1204 * @val: NN value or SP value/preference list 1205 * @len: length of @val in bytes 1206 * @server: whether this node is server (1) or client (0) 1207 */ 1208static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1209 u8 feat, u8 *val, u8 len, const bool server) 1210{ 1211 u8 *plist, plen, type = dccp_feat_type(feat); 1212 const bool local = (opt == DCCPO_CONFIRM_R); 1213 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local); 1214 1215 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1216 1217 if (entry == NULL) { /* nothing queued: ignore or handle error */ 1218 if (is_mandatory && type == FEAT_UNKNOWN) 1219 return DCCP_RESET_CODE_MANDATORY_ERROR; 1220 1221 if (!local && type == FEAT_NN) /* 6.3.2 */ 1222 goto confirmation_failed; 1223 return 0; 1224 } 1225 1226 if (entry->state != FEAT_CHANGING) /* 6.6.2 */ 1227 return 0; 1228 1229 if (len == 0) { 1230 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */ 1231 goto confirmation_failed; 1232 /* 1233 * Empty Confirm during connection setup: this means reverting 1234 * to the `old' value, which in this case is the default. Since 1235 * we handle default values automatically when no other values 1236 * have been set, we revert to the old value by removing this 1237 * entry from the list. 1238 */ 1239 dccp_feat_list_pop(entry); 1240 return 0; 1241 } 1242 1243 if (type == FEAT_NN) { 1244 if (len > sizeof(entry->val.nn)) 1245 goto confirmation_failed; 1246 1247 if (entry->val.nn == dccp_decode_value_var(val, len)) 1248 goto confirmation_succeeded; 1249 1250 DCCP_WARN("Bogus Confirm for non-existing value\n"); 1251 goto confirmation_failed; 1252 } 1253 1254 /* 1255 * Parsing SP Confirms: the first element of @val is the preferred 1256 * SP value which the peer confirms, the remainder depends on @len. 1257 * Note that only the confirmed value need to be a valid SP value. 1258 */ 1259 if (!dccp_feat_is_valid_sp_val(feat, *val)) 1260 goto confirmation_failed; 1261 1262 if (len == 1) { /* peer didn't supply a preference list */ 1263 plist = val; 1264 plen = len; 1265 } else { /* preferred value + preference list */ 1266 plist = val + 1; 1267 plen = len - 1; 1268 } 1269 1270 /* Check whether the peer got the reconciliation right (6.6.8) */ 1271 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) { 1272 DCCP_WARN("Confirm selected the wrong value %u\n", *val); 1273 return DCCP_RESET_CODE_OPTION_ERROR; 1274 } 1275 entry->val.sp.vec[0] = *val; 1276 1277confirmation_succeeded: 1278 entry->state = FEAT_STABLE; 1279 return 0; 1280 1281confirmation_failed: 1282 DCCP_WARN("Confirmation failed\n"); 1283 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1284 : DCCP_RESET_CODE_OPTION_ERROR; 1285} 1286 1287/** 1288 * dccp_feat_handle_nn_established - Fast-path reception of NN options 1289 * @sk: socket of an established DCCP connection 1290 * @mandatory: whether @opt was preceded by a Mandatory option 1291 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only) 1292 * @feat: NN number, one of %dccp_feature_numbers 1293 * @val: NN value 1294 * @len: length of @val in bytes 1295 * 1296 * This function combines the functionality of change_recv/confirm_recv, with 1297 * the following differences (reset codes are the same): 1298 * - cleanup after receiving the Confirm; 1299 * - values are directly activated after successful parsing; 1300 * - deliberately restricted to NN features. 1301 * The restriction to NN features is essential since SP features can have non- 1302 * predictable outcomes (depending on the remote configuration), and are inter- 1303 * dependent (CCIDs for instance cause further dependencies). 1304 */ 1305static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt, 1306 u8 feat, u8 *val, u8 len) 1307{ 1308 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1309 const bool local = (opt == DCCPO_CONFIRM_R); 1310 struct dccp_feat_entry *entry; 1311 u8 type = dccp_feat_type(feat); 1312 dccp_feat_val fval; 1313 1314 dccp_feat_print_opt(opt, feat, val, len, mandatory); 1315 1316 /* Ignore non-mandatory unknown and non-NN features */ 1317 if (type == FEAT_UNKNOWN) { 1318 if (local && !mandatory) 1319 return 0; 1320 goto fast_path_unknown; 1321 } else if (type != FEAT_NN) { 1322 return 0; 1323 } 1324 1325 /* 1326 * We don't accept empty Confirms, since in fast-path feature 1327 * negotiation the values are enabled immediately after sending 1328 * the Change option. 1329 * Empty Changes on the other hand are invalid (RFC 4340, 6.1). 1330 */ 1331 if (len == 0 || len > sizeof(fval.nn)) 1332 goto fast_path_unknown; 1333 1334 if (opt == DCCPO_CHANGE_L) { 1335 fval.nn = dccp_decode_value_var(val, len); 1336 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1337 goto fast_path_unknown; 1338 1339 if (dccp_feat_push_confirm(fn, feat, local, &fval) || 1340 dccp_feat_activate(sk, feat, local, &fval)) 1341 return DCCP_RESET_CODE_TOO_BUSY; 1342 1343 /* set the `Ack Pending' flag to piggyback a Confirm */ 1344 inet_csk_schedule_ack(sk); 1345 1346 } else if (opt == DCCPO_CONFIRM_R) { 1347 entry = dccp_feat_list_lookup(fn, feat, local); 1348 if (entry == NULL || entry->state != FEAT_CHANGING) 1349 return 0; 1350 1351 fval.nn = dccp_decode_value_var(val, len); 1352 /* 1353 * Just ignore a value that doesn't match our current value. 1354 * If the option changes twice within two RTTs, then at least 1355 * one CONFIRM will be received for the old value after a 1356 * new CHANGE was sent. 1357 */ 1358 if (fval.nn != entry->val.nn) 1359 return 0; 1360 1361 /* Only activate after receiving the Confirm option (6.6.1). */ 1362 dccp_feat_activate(sk, feat, local, &fval); 1363 1364 /* It has been confirmed - so remove the entry */ 1365 dccp_feat_list_pop(entry); 1366 1367 } else { 1368 DCCP_WARN("Received illegal option %u\n", opt); 1369 goto fast_path_failed; 1370 } 1371 return 0; 1372 1373fast_path_unknown: 1374 if (!mandatory) 1375 return dccp_push_empty_confirm(fn, feat, local); 1376 1377fast_path_failed: 1378 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1379 : DCCP_RESET_CODE_OPTION_ERROR; 1380} 1381 1382/** 1383 * dccp_feat_parse_options - Process Feature-Negotiation Options 1384 * @sk: for general use and used by the client during connection setup 1385 * @dreq: used by the server during connection setup 1386 * @mandatory: whether @opt was preceded by a Mandatory option 1387 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R 1388 * @feat: one of %dccp_feature_numbers 1389 * @val: value contents of @opt 1390 * @len: length of @val in bytes 1391 * 1392 * Returns 0 on success, a Reset code for ending the connection otherwise. 1393 */ 1394int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 1395 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len) 1396{ 1397 struct dccp_sock *dp = dccp_sk(sk); 1398 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 1399 bool server = false; 1400 1401 switch (sk->sk_state) { 1402 /* 1403 * Negotiation during connection setup 1404 */ 1405 case DCCP_LISTEN: 1406 server = true; /* fall through */ 1407 case DCCP_REQUESTING: 1408 switch (opt) { 1409 case DCCPO_CHANGE_L: 1410 case DCCPO_CHANGE_R: 1411 return dccp_feat_change_recv(fn, mandatory, opt, feat, 1412 val, len, server); 1413 case DCCPO_CONFIRM_R: 1414 case DCCPO_CONFIRM_L: 1415 return dccp_feat_confirm_recv(fn, mandatory, opt, feat, 1416 val, len, server); 1417 } 1418 break; 1419 /* 1420 * Support for exchanging NN options on an established connection. 1421 */ 1422 case DCCP_OPEN: 1423 case DCCP_PARTOPEN: 1424 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat, 1425 val, len); 1426 } 1427 return 0; /* ignore FN options in all other states */ 1428} 1429 1430/** 1431 * dccp_feat_init - Seed feature negotiation with host-specific defaults 1432 * This initialises global defaults, depending on the value of the sysctls. 1433 * These can later be overridden by registering changes via setsockopt calls. 1434 * The last link in the chain is finalise_settings, to make sure that between 1435 * here and the start of actual feature negotiation no inconsistencies enter. 1436 * 1437 * All features not appearing below use either defaults or are otherwise 1438 * later adjusted through dccp_feat_finalise_settings(). 1439 */ 1440int dccp_feat_init(struct sock *sk) 1441{ 1442 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1443 u8 on = 1, off = 0; 1444 int rc; 1445 struct { 1446 u8 *val; 1447 u8 len; 1448 } tx, rx; 1449 1450 /* Non-negotiable (NN) features */ 1451 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, 1452 sysctl_dccp_sequence_window); 1453 if (rc) 1454 return rc; 1455 1456 /* Server-priority (SP) features */ 1457 1458 /* Advertise that short seqnos are not supported (7.6.1) */ 1459 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); 1460 if (rc) 1461 return rc; 1462 1463 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ 1464 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); 1465 if (rc) 1466 return rc; 1467 1468 /* 1469 * We advertise the available list of CCIDs and reorder according to 1470 * preferences, to avoid failure resulting from negotiating different 1471 * singleton values (which always leads to failure). 1472 * These settings can still (later) be overridden via sockopts. 1473 */ 1474 if (ccid_get_builtin_ccids(&tx.val, &tx.len) || 1475 ccid_get_builtin_ccids(&rx.val, &rx.len)) 1476 return -ENOBUFS; 1477 1478 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) || 1479 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len)) 1480 goto free_ccid_lists; 1481 1482 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); 1483 if (rc) 1484 goto free_ccid_lists; 1485 1486 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); 1487 1488free_ccid_lists: 1489 kfree(tx.val); 1490 kfree(rx.val); 1491 return rc; 1492} 1493 1494int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) 1495{ 1496 struct dccp_sock *dp = dccp_sk(sk); 1497 struct dccp_feat_entry *cur, *next; 1498 int idx; 1499 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = { 1500 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL } 1501 }; 1502 1503 list_for_each_entry(cur, fn_list, node) { 1504 /* 1505 * An empty Confirm means that either an unknown feature type 1506 * or an invalid value was present. In the first case there is 1507 * nothing to activate, in the other the default value is used. 1508 */ 1509 if (cur->empty_confirm) 1510 continue; 1511 1512 idx = dccp_feat_index(cur->feat_num); 1513 if (idx < 0) { 1514 DCCP_BUG("Unknown feature %u", cur->feat_num); 1515 goto activation_failed; 1516 } 1517 if (cur->state != FEAT_STABLE) { 1518 DCCP_CRIT("Negotiation of %s %s failed in state %s", 1519 cur->is_local ? "local" : "remote", 1520 dccp_feat_fname(cur->feat_num), 1521 dccp_feat_sname[cur->state]); 1522 goto activation_failed; 1523 } 1524 fvals[idx][cur->is_local] = &cur->val; 1525 } 1526 1527 /* 1528 * Activate in decreasing order of index, so that the CCIDs are always 1529 * activated as the last feature. This avoids the case where a CCID 1530 * relies on the initialisation of one or more features that it depends 1531 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features). 1532 */ 1533 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;) 1534 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) || 1535 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) { 1536 DCCP_CRIT("Could not activate %d", idx); 1537 goto activation_failed; 1538 } 1539 1540 /* Clean up Change options which have been confirmed already */ 1541 list_for_each_entry_safe(cur, next, fn_list, node) 1542 if (!cur->needs_confirm) 1543 dccp_feat_list_pop(cur); 1544 1545 dccp_pr_debug("Activation OK\n"); 1546 return 0; 1547 1548activation_failed: 1549 /* 1550 * We clean up everything that may have been allocated, since 1551 * it is difficult to track at which stage negotiation failed. 1552 * This is ok, since all allocation functions below are robust 1553 * against NULL arguments. 1554 */ 1555 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 1556 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 1557 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; 1558 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 1559 dp->dccps_hc_rx_ackvec = NULL; 1560 return -1; 1561} 1562