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 */ 31 unsigned long sysctl_dccp_sequence_window __read_mostly = 100; 32 int 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 */ 41 static 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 59 static 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 75 static 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 84 static 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 } 100 101 static 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 */ 117 static 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 } 132 133 static 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 */ 175 static 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 } 191 192 static 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 } 200 201 static 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 */ 216 static 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 } 240 241 static const char *const dccp_feat_sname[] = { 242 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE", 243 }; 244 245 #ifdef CONFIG_IP_DCCP_DEBUG 246 static 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 } 256 257 static 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 } 271 272 static 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 } 281 282 static 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 307 308 static 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 */ 356 static 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) */ 363 static 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 */ 370 static 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 } 382 383 static 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 } 391 392 static 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 } 413 414 static 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 */ 431 static 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 */ 453 static 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 * @mandatory: whether to use Mandatory feature negotiation options 482 * @fval: pointer to NN/SP value to be inserted (will be copied) 483 */ 484 static 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 */ 512 static 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 } 532 533 static 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 } 537 538 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry) 539 { 540 list_del(&entry->node); 541 dccp_feat_entry_destructor(entry); 542 } 543 544 void 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 } 552 EXPORT_SYMBOL_GPL(dccp_feat_list_purge); 553 554 /* generate @to as full clone of @from - @to must not contain any nodes */ 555 int 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; 567 568 cloning_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 */ 578 static 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 } 586 587 static 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 */ 599 static 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 } 617 618 static 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 */ 634 int 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 */ 700 static 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 */ 725 static 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 if (dccp_feat_push_change(fn, feat, is_local, mandatory, &fval)) { 742 kfree(fval.sp.vec); 743 return -ENOMEM; 744 } 745 746 return 0; 747 } 748 749 /** 750 * dccp_feat_register_sp - Register requests to change SP feature values 751 * @sk: client or listening socket 752 * @feat: one of %dccp_feature_numbers 753 * @is_local: whether the local (1) or remote (0) @feat is meant 754 * @list: array of preferred values, in descending order of preference 755 * @len: length of @list in bytes 756 */ 757 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, 758 u8 const *list, u8 len) 759 { /* any changes must be registered before establishing the connection */ 760 if (sk->sk_state != DCCP_CLOSED) 761 return -EISCONN; 762 if (dccp_feat_type(feat) != FEAT_SP) 763 return -EINVAL; 764 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local, 765 0, list, len); 766 } 767 768 /** 769 * dccp_feat_nn_get - Query current/pending value of NN feature 770 * @sk: DCCP socket of an established connection 771 * @feat: NN feature number from %dccp_feature_numbers 772 * 773 * For a known NN feature, returns value currently being negotiated, or 774 * current (confirmed) value if no negotiation is going on. 775 */ 776 u64 dccp_feat_nn_get(struct sock *sk, u8 feat) 777 { 778 if (dccp_feat_type(feat) == FEAT_NN) { 779 struct dccp_sock *dp = dccp_sk(sk); 780 struct dccp_feat_entry *entry; 781 782 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1); 783 if (entry != NULL) 784 return entry->val.nn; 785 786 switch (feat) { 787 case DCCPF_ACK_RATIO: 788 return dp->dccps_l_ack_ratio; 789 case DCCPF_SEQUENCE_WINDOW: 790 return dp->dccps_l_seq_win; 791 } 792 } 793 DCCP_BUG("attempt to look up unsupported feature %u", feat); 794 return 0; 795 } 796 EXPORT_SYMBOL_GPL(dccp_feat_nn_get); 797 798 /** 799 * dccp_feat_signal_nn_change - Update NN values for an established connection 800 * @sk: DCCP socket of an established connection 801 * @feat: NN feature number from %dccp_feature_numbers 802 * @nn_val: the new value to use 803 * 804 * This function is used to communicate NN updates out-of-band. 805 */ 806 int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val) 807 { 808 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 809 dccp_feat_val fval = { .nn = nn_val }; 810 struct dccp_feat_entry *entry; 811 812 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN) 813 return 0; 814 815 if (dccp_feat_type(feat) != FEAT_NN || 816 !dccp_feat_is_valid_nn_val(feat, nn_val)) 817 return -EINVAL; 818 819 if (nn_val == dccp_feat_nn_get(sk, feat)) 820 return 0; /* already set or negotiation under way */ 821 822 entry = dccp_feat_list_lookup(fn, feat, 1); 823 if (entry != NULL) { 824 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n", 825 (unsigned long long)entry->val.nn, 826 (unsigned long long)nn_val); 827 dccp_feat_list_pop(entry); 828 } 829 830 inet_csk_schedule_ack(sk); 831 return dccp_feat_push_change(fn, feat, 1, 0, &fval); 832 } 833 EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change); 834 835 /* 836 * Tracking features whose value depend on the choice of CCID 837 * 838 * This is designed with an extension in mind so that a list walk could be done 839 * before activating any features. However, the existing framework was found to 840 * work satisfactorily up until now, the automatic verification is left open. 841 * When adding new CCIDs, add a corresponding dependency table here. 842 */ 843 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local) 844 { 845 static const struct ccid_dependency ccid2_dependencies[2][2] = { 846 /* 847 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX 848 * feature and Send Ack Vector is an RX feature, `is_local' 849 * needs to be reversed. 850 */ 851 { /* Dependencies of the receiver-side (remote) CCID2 */ 852 { 853 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 854 .is_local = true, 855 .is_mandatory = true, 856 .val = 1 857 }, 858 { 0, 0, 0, 0 } 859 }, 860 { /* Dependencies of the sender-side (local) CCID2 */ 861 { 862 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 863 .is_local = false, 864 .is_mandatory = true, 865 .val = 1 866 }, 867 { 0, 0, 0, 0 } 868 } 869 }; 870 static const struct ccid_dependency ccid3_dependencies[2][5] = { 871 { /* 872 * Dependencies of the receiver-side CCID3 873 */ 874 { /* locally disable Ack Vectors */ 875 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 876 .is_local = true, 877 .is_mandatory = false, 878 .val = 0 879 }, 880 { /* see below why Send Loss Event Rate is on */ 881 .dependent_feat = DCCPF_SEND_LEV_RATE, 882 .is_local = true, 883 .is_mandatory = true, 884 .val = 1 885 }, 886 { /* NDP Count is needed as per RFC 4342, 6.1.1 */ 887 .dependent_feat = DCCPF_SEND_NDP_COUNT, 888 .is_local = false, 889 .is_mandatory = true, 890 .val = 1 891 }, 892 { 0, 0, 0, 0 }, 893 }, 894 { /* 895 * CCID3 at the TX side: we request that the HC-receiver 896 * will not send Ack Vectors (they will be ignored, so 897 * Mandatory is not set); we enable Send Loss Event Rate 898 * (Mandatory since the implementation does not support 899 * the Loss Intervals option of RFC 4342, 8.6). 900 * The last two options are for peer's information only. 901 */ 902 { 903 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 904 .is_local = false, 905 .is_mandatory = false, 906 .val = 0 907 }, 908 { 909 .dependent_feat = DCCPF_SEND_LEV_RATE, 910 .is_local = false, 911 .is_mandatory = true, 912 .val = 1 913 }, 914 { /* this CCID does not support Ack Ratio */ 915 .dependent_feat = DCCPF_ACK_RATIO, 916 .is_local = true, 917 .is_mandatory = false, 918 .val = 0 919 }, 920 { /* tell receiver we are sending NDP counts */ 921 .dependent_feat = DCCPF_SEND_NDP_COUNT, 922 .is_local = true, 923 .is_mandatory = false, 924 .val = 1 925 }, 926 { 0, 0, 0, 0 } 927 } 928 }; 929 switch (ccid) { 930 case DCCPC_CCID2: 931 return ccid2_dependencies[is_local]; 932 case DCCPC_CCID3: 933 return ccid3_dependencies[is_local]; 934 default: 935 return NULL; 936 } 937 } 938 939 /** 940 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID 941 * @fn: feature-negotiation list to update 942 * @id: CCID number to track 943 * @is_local: whether TX CCID (1) or RX CCID (0) is meant 944 * 945 * This function needs to be called after registering all other features. 946 */ 947 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local) 948 { 949 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local); 950 int i, rc = (table == NULL); 951 952 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++) 953 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP) 954 rc = __feat_register_sp(fn, table[i].dependent_feat, 955 table[i].is_local, 956 table[i].is_mandatory, 957 &table[i].val, 1); 958 else 959 rc = __feat_register_nn(fn, table[i].dependent_feat, 960 table[i].is_mandatory, 961 table[i].val); 962 return rc; 963 } 964 965 /** 966 * dccp_feat_finalise_settings - Finalise settings before starting negotiation 967 * @dp: client or listening socket (settings will be inherited) 968 * 969 * This is called after all registrations (socket initialisation, sysctls, and 970 * sockopt calls), and before sending the first packet containing Change options 971 * (ie. client-Request or server-Response), to ensure internal consistency. 972 */ 973 int dccp_feat_finalise_settings(struct dccp_sock *dp) 974 { 975 struct list_head *fn = &dp->dccps_featneg; 976 struct dccp_feat_entry *entry; 977 int i = 2, ccids[2] = { -1, -1 }; 978 979 /* 980 * Propagating CCIDs: 981 * 1) not useful to propagate CCID settings if this host advertises more 982 * than one CCID: the choice of CCID may still change - if this is 983 * the client, or if this is the server and the client sends 984 * singleton CCID values. 985 * 2) since is that propagate_ccid changes the list, we defer changing 986 * the sorted list until after the traversal. 987 */ 988 list_for_each_entry(entry, fn, node) 989 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1) 990 ccids[entry->is_local] = entry->val.sp.vec[0]; 991 while (i--) 992 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i)) 993 return -1; 994 dccp_feat_print_fnlist(fn); 995 return 0; 996 } 997 998 /** 999 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features 1000 * It is the server which resolves the dependencies once the CCID has been 1001 * fully negotiated. If no CCID has been negotiated, it uses the default CCID. 1002 */ 1003 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq) 1004 { 1005 struct list_head *fn = &dreq->dreq_featneg; 1006 struct dccp_feat_entry *entry; 1007 u8 is_local, ccid; 1008 1009 for (is_local = 0; is_local <= 1; is_local++) { 1010 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local); 1011 1012 if (entry != NULL && !entry->empty_confirm) 1013 ccid = entry->val.sp.vec[0]; 1014 else 1015 ccid = dccp_feat_default_value(DCCPF_CCID); 1016 1017 if (dccp_feat_propagate_ccid(fn, ccid, is_local)) 1018 return -1; 1019 } 1020 return 0; 1021 } 1022 1023 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */ 1024 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen) 1025 { 1026 u8 c, s; 1027 1028 for (s = 0; s < slen; s++) 1029 for (c = 0; c < clen; c++) 1030 if (servlist[s] == clilist[c]) 1031 return servlist[s]; 1032 return -1; 1033 } 1034 1035 /** 1036 * dccp_feat_prefer - Move preferred entry to the start of array 1037 * Reorder the @array_len elements in @array so that @preferred_value comes 1038 * first. Returns >0 to indicate that @preferred_value does occur in @array. 1039 */ 1040 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len) 1041 { 1042 u8 i, does_occur = 0; 1043 1044 if (array != NULL) { 1045 for (i = 0; i < array_len; i++) 1046 if (array[i] == preferred_value) { 1047 array[i] = array[0]; 1048 does_occur++; 1049 } 1050 if (does_occur) 1051 array[0] = preferred_value; 1052 } 1053 return does_occur; 1054 } 1055 1056 /** 1057 * dccp_feat_reconcile - Reconcile SP preference lists 1058 * @fv: SP list to reconcile into 1059 * @arr: received SP preference list 1060 * @len: length of @arr in bytes 1061 * @is_server: whether this side is the server (and @fv is the server's list) 1062 * @reorder: whether to reorder the list in @fv after reconciling with @arr 1063 * When successful, > 0 is returned and the reconciled list is in @fval. 1064 * A value of 0 means that negotiation failed (no shared entry). 1065 */ 1066 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len, 1067 bool is_server, bool reorder) 1068 { 1069 int rc; 1070 1071 if (!fv->sp.vec || !arr) { 1072 DCCP_CRIT("NULL feature value or array"); 1073 return 0; 1074 } 1075 1076 if (is_server) 1077 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len); 1078 else 1079 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len); 1080 1081 if (!reorder) 1082 return rc; 1083 if (rc < 0) 1084 return 0; 1085 1086 /* 1087 * Reorder list: used for activating features and in dccp_insert_fn_opt. 1088 */ 1089 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len); 1090 } 1091 1092 /** 1093 * dccp_feat_change_recv - Process incoming ChangeL/R options 1094 * @fn: feature-negotiation list to update 1095 * @is_mandatory: whether the Change was preceded by a Mandatory option 1096 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R 1097 * @feat: one of %dccp_feature_numbers 1098 * @val: NN value or SP value/preference list 1099 * @len: length of @val in bytes 1100 * @server: whether this node is the server (1) or the client (0) 1101 */ 1102 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1103 u8 feat, u8 *val, u8 len, const bool server) 1104 { 1105 u8 defval, type = dccp_feat_type(feat); 1106 const bool local = (opt == DCCPO_CHANGE_R); 1107 struct dccp_feat_entry *entry; 1108 dccp_feat_val fval; 1109 1110 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */ 1111 goto unknown_feature_or_value; 1112 1113 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1114 1115 /* 1116 * Negotiation of NN features: Change R is invalid, so there is no 1117 * simultaneous negotiation; hence we do not look up in the list. 1118 */ 1119 if (type == FEAT_NN) { 1120 if (local || len > sizeof(fval.nn)) 1121 goto unknown_feature_or_value; 1122 1123 /* 6.3.2: "The feature remote MUST accept any valid value..." */ 1124 fval.nn = dccp_decode_value_var(val, len); 1125 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1126 goto unknown_feature_or_value; 1127 1128 return dccp_feat_push_confirm(fn, feat, local, &fval); 1129 } 1130 1131 /* 1132 * Unidirectional/simultaneous negotiation of SP features (6.3.1) 1133 */ 1134 entry = dccp_feat_list_lookup(fn, feat, local); 1135 if (entry == NULL) { 1136 /* 1137 * No particular preferences have been registered. We deal with 1138 * this situation by assuming that all valid values are equally 1139 * acceptable, and apply the following checks: 1140 * - if the peer's list is a singleton, we accept a valid value; 1141 * - if we are the server, we first try to see if the peer (the 1142 * client) advertises the default value. If yes, we use it, 1143 * otherwise we accept the preferred value; 1144 * - else if we are the client, we use the first list element. 1145 */ 1146 if (dccp_feat_clone_sp_val(&fval, val, 1)) 1147 return DCCP_RESET_CODE_TOO_BUSY; 1148 1149 if (len > 1 && server) { 1150 defval = dccp_feat_default_value(feat); 1151 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1) 1152 fval.sp.vec[0] = defval; 1153 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) { 1154 kfree(fval.sp.vec); 1155 goto unknown_feature_or_value; 1156 } 1157 1158 /* Treat unsupported CCIDs like invalid values */ 1159 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) { 1160 kfree(fval.sp.vec); 1161 goto not_valid_or_not_known; 1162 } 1163 1164 return dccp_feat_push_confirm(fn, feat, local, &fval); 1165 1166 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */ 1167 return 0; 1168 } 1169 1170 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) { 1171 entry->empty_confirm = false; 1172 } else if (is_mandatory) { 1173 return DCCP_RESET_CODE_MANDATORY_ERROR; 1174 } else if (entry->state == FEAT_INITIALISING) { 1175 /* 1176 * Failed simultaneous negotiation (server only): try to `save' 1177 * the connection by checking whether entry contains the default 1178 * value for @feat. If yes, send an empty Confirm to signal that 1179 * the received Change was not understood - which implies using 1180 * the default value. 1181 * If this also fails, we use Reset as the last resort. 1182 */ 1183 WARN_ON(!server); 1184 defval = dccp_feat_default_value(feat); 1185 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true)) 1186 return DCCP_RESET_CODE_OPTION_ERROR; 1187 entry->empty_confirm = true; 1188 } 1189 entry->needs_confirm = true; 1190 entry->needs_mandatory = false; 1191 entry->state = FEAT_STABLE; 1192 return 0; 1193 1194 unknown_feature_or_value: 1195 if (!is_mandatory) 1196 return dccp_push_empty_confirm(fn, feat, local); 1197 1198 not_valid_or_not_known: 1199 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1200 : DCCP_RESET_CODE_OPTION_ERROR; 1201 } 1202 1203 /** 1204 * dccp_feat_confirm_recv - Process received Confirm options 1205 * @fn: feature-negotiation list to update 1206 * @is_mandatory: whether @opt was preceded by a Mandatory option 1207 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R 1208 * @feat: one of %dccp_feature_numbers 1209 * @val: NN value or SP value/preference list 1210 * @len: length of @val in bytes 1211 * @server: whether this node is server (1) or client (0) 1212 */ 1213 static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1214 u8 feat, u8 *val, u8 len, const bool server) 1215 { 1216 u8 *plist, plen, type = dccp_feat_type(feat); 1217 const bool local = (opt == DCCPO_CONFIRM_R); 1218 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local); 1219 1220 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1221 1222 if (entry == NULL) { /* nothing queued: ignore or handle error */ 1223 if (is_mandatory && type == FEAT_UNKNOWN) 1224 return DCCP_RESET_CODE_MANDATORY_ERROR; 1225 1226 if (!local && type == FEAT_NN) /* 6.3.2 */ 1227 goto confirmation_failed; 1228 return 0; 1229 } 1230 1231 if (entry->state != FEAT_CHANGING) /* 6.6.2 */ 1232 return 0; 1233 1234 if (len == 0) { 1235 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */ 1236 goto confirmation_failed; 1237 /* 1238 * Empty Confirm during connection setup: this means reverting 1239 * to the `old' value, which in this case is the default. Since 1240 * we handle default values automatically when no other values 1241 * have been set, we revert to the old value by removing this 1242 * entry from the list. 1243 */ 1244 dccp_feat_list_pop(entry); 1245 return 0; 1246 } 1247 1248 if (type == FEAT_NN) { 1249 if (len > sizeof(entry->val.nn)) 1250 goto confirmation_failed; 1251 1252 if (entry->val.nn == dccp_decode_value_var(val, len)) 1253 goto confirmation_succeeded; 1254 1255 DCCP_WARN("Bogus Confirm for non-existing value\n"); 1256 goto confirmation_failed; 1257 } 1258 1259 /* 1260 * Parsing SP Confirms: the first element of @val is the preferred 1261 * SP value which the peer confirms, the remainder depends on @len. 1262 * Note that only the confirmed value need to be a valid SP value. 1263 */ 1264 if (!dccp_feat_is_valid_sp_val(feat, *val)) 1265 goto confirmation_failed; 1266 1267 if (len == 1) { /* peer didn't supply a preference list */ 1268 plist = val; 1269 plen = len; 1270 } else { /* preferred value + preference list */ 1271 plist = val + 1; 1272 plen = len - 1; 1273 } 1274 1275 /* Check whether the peer got the reconciliation right (6.6.8) */ 1276 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) { 1277 DCCP_WARN("Confirm selected the wrong value %u\n", *val); 1278 return DCCP_RESET_CODE_OPTION_ERROR; 1279 } 1280 entry->val.sp.vec[0] = *val; 1281 1282 confirmation_succeeded: 1283 entry->state = FEAT_STABLE; 1284 return 0; 1285 1286 confirmation_failed: 1287 DCCP_WARN("Confirmation failed\n"); 1288 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1289 : DCCP_RESET_CODE_OPTION_ERROR; 1290 } 1291 1292 /** 1293 * dccp_feat_handle_nn_established - Fast-path reception of NN options 1294 * @sk: socket of an established DCCP connection 1295 * @mandatory: whether @opt was preceded by a Mandatory option 1296 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only) 1297 * @feat: NN number, one of %dccp_feature_numbers 1298 * @val: NN value 1299 * @len: length of @val in bytes 1300 * 1301 * This function combines the functionality of change_recv/confirm_recv, with 1302 * the following differences (reset codes are the same): 1303 * - cleanup after receiving the Confirm; 1304 * - values are directly activated after successful parsing; 1305 * - deliberately restricted to NN features. 1306 * The restriction to NN features is essential since SP features can have non- 1307 * predictable outcomes (depending on the remote configuration), and are inter- 1308 * dependent (CCIDs for instance cause further dependencies). 1309 */ 1310 static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt, 1311 u8 feat, u8 *val, u8 len) 1312 { 1313 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1314 const bool local = (opt == DCCPO_CONFIRM_R); 1315 struct dccp_feat_entry *entry; 1316 u8 type = dccp_feat_type(feat); 1317 dccp_feat_val fval; 1318 1319 dccp_feat_print_opt(opt, feat, val, len, mandatory); 1320 1321 /* Ignore non-mandatory unknown and non-NN features */ 1322 if (type == FEAT_UNKNOWN) { 1323 if (local && !mandatory) 1324 return 0; 1325 goto fast_path_unknown; 1326 } else if (type != FEAT_NN) { 1327 return 0; 1328 } 1329 1330 /* 1331 * We don't accept empty Confirms, since in fast-path feature 1332 * negotiation the values are enabled immediately after sending 1333 * the Change option. 1334 * Empty Changes on the other hand are invalid (RFC 4340, 6.1). 1335 */ 1336 if (len == 0 || len > sizeof(fval.nn)) 1337 goto fast_path_unknown; 1338 1339 if (opt == DCCPO_CHANGE_L) { 1340 fval.nn = dccp_decode_value_var(val, len); 1341 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1342 goto fast_path_unknown; 1343 1344 if (dccp_feat_push_confirm(fn, feat, local, &fval) || 1345 dccp_feat_activate(sk, feat, local, &fval)) 1346 return DCCP_RESET_CODE_TOO_BUSY; 1347 1348 /* set the `Ack Pending' flag to piggyback a Confirm */ 1349 inet_csk_schedule_ack(sk); 1350 1351 } else if (opt == DCCPO_CONFIRM_R) { 1352 entry = dccp_feat_list_lookup(fn, feat, local); 1353 if (entry == NULL || entry->state != FEAT_CHANGING) 1354 return 0; 1355 1356 fval.nn = dccp_decode_value_var(val, len); 1357 /* 1358 * Just ignore a value that doesn't match our current value. 1359 * If the option changes twice within two RTTs, then at least 1360 * one CONFIRM will be received for the old value after a 1361 * new CHANGE was sent. 1362 */ 1363 if (fval.nn != entry->val.nn) 1364 return 0; 1365 1366 /* Only activate after receiving the Confirm option (6.6.1). */ 1367 dccp_feat_activate(sk, feat, local, &fval); 1368 1369 /* It has been confirmed - so remove the entry */ 1370 dccp_feat_list_pop(entry); 1371 1372 } else { 1373 DCCP_WARN("Received illegal option %u\n", opt); 1374 goto fast_path_failed; 1375 } 1376 return 0; 1377 1378 fast_path_unknown: 1379 if (!mandatory) 1380 return dccp_push_empty_confirm(fn, feat, local); 1381 1382 fast_path_failed: 1383 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1384 : DCCP_RESET_CODE_OPTION_ERROR; 1385 } 1386 1387 /** 1388 * dccp_feat_parse_options - Process Feature-Negotiation Options 1389 * @sk: for general use and used by the client during connection setup 1390 * @dreq: used by the server during connection setup 1391 * @mandatory: whether @opt was preceded by a Mandatory option 1392 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R 1393 * @feat: one of %dccp_feature_numbers 1394 * @val: value contents of @opt 1395 * @len: length of @val in bytes 1396 * 1397 * Returns 0 on success, a Reset code for ending the connection otherwise. 1398 */ 1399 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 1400 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len) 1401 { 1402 struct dccp_sock *dp = dccp_sk(sk); 1403 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 1404 bool server = false; 1405 1406 switch (sk->sk_state) { 1407 /* 1408 * Negotiation during connection setup 1409 */ 1410 case DCCP_LISTEN: 1411 server = true; /* fall through */ 1412 case DCCP_REQUESTING: 1413 switch (opt) { 1414 case DCCPO_CHANGE_L: 1415 case DCCPO_CHANGE_R: 1416 return dccp_feat_change_recv(fn, mandatory, opt, feat, 1417 val, len, server); 1418 case DCCPO_CONFIRM_R: 1419 case DCCPO_CONFIRM_L: 1420 return dccp_feat_confirm_recv(fn, mandatory, opt, feat, 1421 val, len, server); 1422 } 1423 break; 1424 /* 1425 * Support for exchanging NN options on an established connection. 1426 */ 1427 case DCCP_OPEN: 1428 case DCCP_PARTOPEN: 1429 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat, 1430 val, len); 1431 } 1432 return 0; /* ignore FN options in all other states */ 1433 } 1434 1435 /** 1436 * dccp_feat_init - Seed feature negotiation with host-specific defaults 1437 * This initialises global defaults, depending on the value of the sysctls. 1438 * These can later be overridden by registering changes via setsockopt calls. 1439 * The last link in the chain is finalise_settings, to make sure that between 1440 * here and the start of actual feature negotiation no inconsistencies enter. 1441 * 1442 * All features not appearing below use either defaults or are otherwise 1443 * later adjusted through dccp_feat_finalise_settings(). 1444 */ 1445 int dccp_feat_init(struct sock *sk) 1446 { 1447 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1448 u8 on = 1, off = 0; 1449 int rc; 1450 struct { 1451 u8 *val; 1452 u8 len; 1453 } tx, rx; 1454 1455 /* Non-negotiable (NN) features */ 1456 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, 1457 sysctl_dccp_sequence_window); 1458 if (rc) 1459 return rc; 1460 1461 /* Server-priority (SP) features */ 1462 1463 /* Advertise that short seqnos are not supported (7.6.1) */ 1464 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); 1465 if (rc) 1466 return rc; 1467 1468 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ 1469 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); 1470 if (rc) 1471 return rc; 1472 1473 /* 1474 * We advertise the available list of CCIDs and reorder according to 1475 * preferences, to avoid failure resulting from negotiating different 1476 * singleton values (which always leads to failure). 1477 * These settings can still (later) be overridden via sockopts. 1478 */ 1479 if (ccid_get_builtin_ccids(&tx.val, &tx.len)) 1480 return -ENOBUFS; 1481 if (ccid_get_builtin_ccids(&rx.val, &rx.len)) { 1482 kfree(tx.val); 1483 return -ENOBUFS; 1484 } 1485 1486 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) || 1487 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len)) 1488 goto free_ccid_lists; 1489 1490 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); 1491 if (rc) 1492 goto free_ccid_lists; 1493 1494 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); 1495 1496 free_ccid_lists: 1497 kfree(tx.val); 1498 kfree(rx.val); 1499 return rc; 1500 } 1501 1502 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) 1503 { 1504 struct dccp_sock *dp = dccp_sk(sk); 1505 struct dccp_feat_entry *cur, *next; 1506 int idx; 1507 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = { 1508 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL } 1509 }; 1510 1511 list_for_each_entry(cur, fn_list, node) { 1512 /* 1513 * An empty Confirm means that either an unknown feature type 1514 * or an invalid value was present. In the first case there is 1515 * nothing to activate, in the other the default value is used. 1516 */ 1517 if (cur->empty_confirm) 1518 continue; 1519 1520 idx = dccp_feat_index(cur->feat_num); 1521 if (idx < 0) { 1522 DCCP_BUG("Unknown feature %u", cur->feat_num); 1523 goto activation_failed; 1524 } 1525 if (cur->state != FEAT_STABLE) { 1526 DCCP_CRIT("Negotiation of %s %s failed in state %s", 1527 cur->is_local ? "local" : "remote", 1528 dccp_feat_fname(cur->feat_num), 1529 dccp_feat_sname[cur->state]); 1530 goto activation_failed; 1531 } 1532 fvals[idx][cur->is_local] = &cur->val; 1533 } 1534 1535 /* 1536 * Activate in decreasing order of index, so that the CCIDs are always 1537 * activated as the last feature. This avoids the case where a CCID 1538 * relies on the initialisation of one or more features that it depends 1539 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features). 1540 */ 1541 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;) 1542 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) || 1543 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) { 1544 DCCP_CRIT("Could not activate %d", idx); 1545 goto activation_failed; 1546 } 1547 1548 /* Clean up Change options which have been confirmed already */ 1549 list_for_each_entry_safe(cur, next, fn_list, node) 1550 if (!cur->needs_confirm) 1551 dccp_feat_list_pop(cur); 1552 1553 dccp_pr_debug("Activation OK\n"); 1554 return 0; 1555 1556 activation_failed: 1557 /* 1558 * We clean up everything that may have been allocated, since 1559 * it is difficult to track at which stage negotiation failed. 1560 * This is ok, since all allocation functions below are robust 1561 * against NULL arguments. 1562 */ 1563 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 1564 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 1565 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; 1566 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 1567 dp->dccps_hc_rx_ackvec = NULL; 1568 return -1; 1569 } 1570