1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* 3 * net/dccp/feat.c 4 * 5 * Feature negotiation for the DCCP protocol (RFC 4340, section 6) 6 * 7 * Copyright (c) 2008 Gerrit Renker <gerrit@erg.abdn.ac.uk> 8 * Rewrote from scratch, some bits from earlier code by 9 * Copyright (c) 2005 Andrea Bittau <a.bittau@cs.ucl.ac.uk> 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 #include <linux/module.h> 21 #include <linux/slab.h> 22 #include "ccid.h" 23 #include "feat.h" 24 25 /* feature-specific sysctls - initialised to the defaults from RFC 4340, 6.4 */ 26 unsigned long sysctl_dccp_sequence_window __read_mostly = 100; 27 int sysctl_dccp_rx_ccid __read_mostly = 2, 28 sysctl_dccp_tx_ccid __read_mostly = 2; 29 30 /* 31 * Feature activation handlers. 32 * 33 * These all use an u64 argument, to provide enough room for NN/SP features. At 34 * this stage the negotiated values have been checked to be within their range. 35 */ 36 static int dccp_hdlr_ccid(struct sock *sk, u64 ccid, bool rx) 37 { 38 struct dccp_sock *dp = dccp_sk(sk); 39 struct ccid *new_ccid = ccid_new(ccid, sk, rx); 40 41 if (new_ccid == NULL) 42 return -ENOMEM; 43 44 if (rx) { 45 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 46 dp->dccps_hc_rx_ccid = new_ccid; 47 } else { 48 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 49 dp->dccps_hc_tx_ccid = new_ccid; 50 } 51 return 0; 52 } 53 54 static int dccp_hdlr_seq_win(struct sock *sk, u64 seq_win, bool rx) 55 { 56 struct dccp_sock *dp = dccp_sk(sk); 57 58 if (rx) { 59 dp->dccps_r_seq_win = seq_win; 60 /* propagate changes to update SWL/SWH */ 61 dccp_update_gsr(sk, dp->dccps_gsr); 62 } else { 63 dp->dccps_l_seq_win = seq_win; 64 /* propagate changes to update AWL */ 65 dccp_update_gss(sk, dp->dccps_gss); 66 } 67 return 0; 68 } 69 70 static int dccp_hdlr_ack_ratio(struct sock *sk, u64 ratio, bool rx) 71 { 72 if (rx) 73 dccp_sk(sk)->dccps_r_ack_ratio = ratio; 74 else 75 dccp_sk(sk)->dccps_l_ack_ratio = ratio; 76 return 0; 77 } 78 79 static int dccp_hdlr_ackvec(struct sock *sk, u64 enable, bool rx) 80 { 81 struct dccp_sock *dp = dccp_sk(sk); 82 83 if (rx) { 84 if (enable && dp->dccps_hc_rx_ackvec == NULL) { 85 dp->dccps_hc_rx_ackvec = dccp_ackvec_alloc(gfp_any()); 86 if (dp->dccps_hc_rx_ackvec == NULL) 87 return -ENOMEM; 88 } else if (!enable) { 89 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 90 dp->dccps_hc_rx_ackvec = NULL; 91 } 92 } 93 return 0; 94 } 95 96 static int dccp_hdlr_ndp(struct sock *sk, u64 enable, bool rx) 97 { 98 if (!rx) 99 dccp_sk(sk)->dccps_send_ndp_count = (enable > 0); 100 return 0; 101 } 102 103 /* 104 * Minimum Checksum Coverage is located at the RX side (9.2.1). This means that 105 * `rx' holds when the sending peer informs about his partial coverage via a 106 * ChangeR() option. In the other case, we are the sender and the receiver 107 * announces its coverage via ChangeL() options. The policy here is to honour 108 * such communication by enabling the corresponding partial coverage - but only 109 * if it has not been set manually before; the warning here means that all 110 * packets will be dropped. 111 */ 112 static int dccp_hdlr_min_cscov(struct sock *sk, u64 cscov, bool rx) 113 { 114 struct dccp_sock *dp = dccp_sk(sk); 115 116 if (rx) 117 dp->dccps_pcrlen = cscov; 118 else { 119 if (dp->dccps_pcslen == 0) 120 dp->dccps_pcslen = cscov; 121 else if (cscov > dp->dccps_pcslen) 122 DCCP_WARN("CsCov %u too small, peer requires >= %u\n", 123 dp->dccps_pcslen, (u8)cscov); 124 } 125 return 0; 126 } 127 128 static const struct { 129 u8 feat_num; /* DCCPF_xxx */ 130 enum dccp_feat_type rxtx; /* RX or TX */ 131 enum dccp_feat_type reconciliation; /* SP or NN */ 132 u8 default_value; /* as in 6.4 */ 133 int (*activation_hdlr)(struct sock *sk, u64 val, bool rx); 134 /* 135 * Lookup table for location and type of features (from RFC 4340/4342) 136 * +--------------------------+----+-----+----+----+---------+-----------+ 137 * | Feature | Location | Reconc. | Initial | Section | 138 * | | RX | TX | SP | NN | Value | Reference | 139 * +--------------------------+----+-----+----+----+---------+-----------+ 140 * | DCCPF_CCID | | X | X | | 2 | 10 | 141 * | DCCPF_SHORT_SEQNOS | | X | X | | 0 | 7.6.1 | 142 * | DCCPF_SEQUENCE_WINDOW | | X | | X | 100 | 7.5.2 | 143 * | DCCPF_ECN_INCAPABLE | X | | X | | 0 | 12.1 | 144 * | DCCPF_ACK_RATIO | | X | | X | 2 | 11.3 | 145 * | DCCPF_SEND_ACK_VECTOR | X | | X | | 0 | 11.5 | 146 * | DCCPF_SEND_NDP_COUNT | | X | X | | 0 | 7.7.2 | 147 * | DCCPF_MIN_CSUM_COVER | X | | X | | 0 | 9.2.1 | 148 * | DCCPF_DATA_CHECKSUM | X | | X | | 0 | 9.3.1 | 149 * | DCCPF_SEND_LEV_RATE | X | | X | | 0 | 4342/8.4 | 150 * +--------------------------+----+-----+----+----+---------+-----------+ 151 */ 152 } dccp_feat_table[] = { 153 { DCCPF_CCID, FEAT_AT_TX, FEAT_SP, 2, dccp_hdlr_ccid }, 154 { DCCPF_SHORT_SEQNOS, FEAT_AT_TX, FEAT_SP, 0, NULL }, 155 { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100, dccp_hdlr_seq_win }, 156 { DCCPF_ECN_INCAPABLE, FEAT_AT_RX, FEAT_SP, 0, NULL }, 157 { DCCPF_ACK_RATIO, FEAT_AT_TX, FEAT_NN, 2, dccp_hdlr_ack_ratio}, 158 { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_ackvec }, 159 { DCCPF_SEND_NDP_COUNT, FEAT_AT_TX, FEAT_SP, 0, dccp_hdlr_ndp }, 160 { DCCPF_MIN_CSUM_COVER, FEAT_AT_RX, FEAT_SP, 0, dccp_hdlr_min_cscov}, 161 { DCCPF_DATA_CHECKSUM, FEAT_AT_RX, FEAT_SP, 0, NULL }, 162 { DCCPF_SEND_LEV_RATE, FEAT_AT_RX, FEAT_SP, 0, NULL }, 163 }; 164 #define DCCP_FEAT_SUPPORTED_MAX ARRAY_SIZE(dccp_feat_table) 165 166 /** 167 * dccp_feat_index - Hash function to map feature number into array position 168 * @feat_num: feature to hash, one of %dccp_feature_numbers 169 * 170 * Returns consecutive array index or -1 if the feature is not understood. 171 */ 172 static int dccp_feat_index(u8 feat_num) 173 { 174 /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */ 175 if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM) 176 return feat_num - 1; 177 178 /* 179 * Other features: add cases for new feature types here after adding 180 * them to the above table. 181 */ 182 switch (feat_num) { 183 case DCCPF_SEND_LEV_RATE: 184 return DCCP_FEAT_SUPPORTED_MAX - 1; 185 } 186 return -1; 187 } 188 189 static u8 dccp_feat_type(u8 feat_num) 190 { 191 int idx = dccp_feat_index(feat_num); 192 193 if (idx < 0) 194 return FEAT_UNKNOWN; 195 return dccp_feat_table[idx].reconciliation; 196 } 197 198 static int dccp_feat_default_value(u8 feat_num) 199 { 200 int idx = dccp_feat_index(feat_num); 201 /* 202 * There are no default values for unknown features, so encountering a 203 * negative index here indicates a serious problem somewhere else. 204 */ 205 DCCP_BUG_ON(idx < 0); 206 207 return idx < 0 ? 0 : dccp_feat_table[idx].default_value; 208 } 209 210 /* 211 * Debugging and verbose-printing section 212 */ 213 static const char *dccp_feat_fname(const u8 feat) 214 { 215 static const char *const feature_names[] = { 216 [DCCPF_RESERVED] = "Reserved", 217 [DCCPF_CCID] = "CCID", 218 [DCCPF_SHORT_SEQNOS] = "Allow Short Seqnos", 219 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window", 220 [DCCPF_ECN_INCAPABLE] = "ECN Incapable", 221 [DCCPF_ACK_RATIO] = "Ack Ratio", 222 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector", 223 [DCCPF_SEND_NDP_COUNT] = "Send NDP Count", 224 [DCCPF_MIN_CSUM_COVER] = "Min. Csum Coverage", 225 [DCCPF_DATA_CHECKSUM] = "Send Data Checksum", 226 }; 227 if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC) 228 return feature_names[DCCPF_RESERVED]; 229 230 if (feat == DCCPF_SEND_LEV_RATE) 231 return "Send Loss Event Rate"; 232 if (feat >= DCCPF_MIN_CCID_SPECIFIC) 233 return "CCID-specific"; 234 235 return feature_names[feat]; 236 } 237 238 static const char *const dccp_feat_sname[] = { 239 "DEFAULT", "INITIALISING", "CHANGING", "UNSTABLE", "STABLE", 240 }; 241 242 #ifdef CONFIG_IP_DCCP_DEBUG 243 static const char *dccp_feat_oname(const u8 opt) 244 { 245 switch (opt) { 246 case DCCPO_CHANGE_L: return "Change_L"; 247 case DCCPO_CONFIRM_L: return "Confirm_L"; 248 case DCCPO_CHANGE_R: return "Change_R"; 249 case DCCPO_CONFIRM_R: return "Confirm_R"; 250 } 251 return NULL; 252 } 253 254 static void dccp_feat_printval(u8 feat_num, dccp_feat_val const *val) 255 { 256 u8 i, type = dccp_feat_type(feat_num); 257 258 if (val == NULL || (type == FEAT_SP && val->sp.vec == NULL)) 259 dccp_pr_debug_cat("(NULL)"); 260 else if (type == FEAT_SP) 261 for (i = 0; i < val->sp.len; i++) 262 dccp_pr_debug_cat("%s%u", i ? " " : "", val->sp.vec[i]); 263 else if (type == FEAT_NN) 264 dccp_pr_debug_cat("%llu", (unsigned long long)val->nn); 265 else 266 dccp_pr_debug_cat("unknown type %u", type); 267 } 268 269 static void dccp_feat_printvals(u8 feat_num, u8 *list, u8 len) 270 { 271 u8 type = dccp_feat_type(feat_num); 272 dccp_feat_val fval = { .sp.vec = list, .sp.len = len }; 273 274 if (type == FEAT_NN) 275 fval.nn = dccp_decode_value_var(list, len); 276 dccp_feat_printval(feat_num, &fval); 277 } 278 279 static void dccp_feat_print_entry(struct dccp_feat_entry const *entry) 280 { 281 dccp_debug(" * %s %s = ", entry->is_local ? "local" : "remote", 282 dccp_feat_fname(entry->feat_num)); 283 dccp_feat_printval(entry->feat_num, &entry->val); 284 dccp_pr_debug_cat(", state=%s %s\n", dccp_feat_sname[entry->state], 285 entry->needs_confirm ? "(Confirm pending)" : ""); 286 } 287 288 #define dccp_feat_print_opt(opt, feat, val, len, mandatory) do { \ 289 dccp_pr_debug("%s(%s, ", dccp_feat_oname(opt), dccp_feat_fname(feat));\ 290 dccp_feat_printvals(feat, val, len); \ 291 dccp_pr_debug_cat(") %s\n", mandatory ? "!" : ""); } while (0) 292 293 #define dccp_feat_print_fnlist(fn_list) { \ 294 const struct dccp_feat_entry *___entry; \ 295 \ 296 dccp_pr_debug("List Dump:\n"); \ 297 list_for_each_entry(___entry, fn_list, node) \ 298 dccp_feat_print_entry(___entry); \ 299 } 300 #else /* ! CONFIG_IP_DCCP_DEBUG */ 301 #define dccp_feat_print_opt(opt, feat, val, len, mandatory) 302 #define dccp_feat_print_fnlist(fn_list) 303 #endif 304 305 static int __dccp_feat_activate(struct sock *sk, const int idx, 306 const bool is_local, dccp_feat_val const *fval) 307 { 308 bool rx; 309 u64 val; 310 311 if (idx < 0 || idx >= DCCP_FEAT_SUPPORTED_MAX) 312 return -1; 313 if (dccp_feat_table[idx].activation_hdlr == NULL) 314 return 0; 315 316 if (fval == NULL) { 317 val = dccp_feat_table[idx].default_value; 318 } else if (dccp_feat_table[idx].reconciliation == FEAT_SP) { 319 if (fval->sp.vec == NULL) { 320 /* 321 * This can happen when an empty Confirm is sent 322 * for an SP (i.e. known) feature. In this case 323 * we would be using the default anyway. 324 */ 325 DCCP_CRIT("Feature #%d undefined: using default", idx); 326 val = dccp_feat_table[idx].default_value; 327 } else { 328 val = fval->sp.vec[0]; 329 } 330 } else { 331 val = fval->nn; 332 } 333 334 /* Location is RX if this is a local-RX or remote-TX feature */ 335 rx = (is_local == (dccp_feat_table[idx].rxtx == FEAT_AT_RX)); 336 337 dccp_debug(" -> activating %s %s, %sval=%llu\n", rx ? "RX" : "TX", 338 dccp_feat_fname(dccp_feat_table[idx].feat_num), 339 fval ? "" : "default ", (unsigned long long)val); 340 341 return dccp_feat_table[idx].activation_hdlr(sk, val, rx); 342 } 343 344 /** 345 * dccp_feat_activate - Activate feature value on socket 346 * @sk: fully connected DCCP socket (after handshake is complete) 347 * @feat_num: feature to activate, one of %dccp_feature_numbers 348 * @local: whether local (1) or remote (0) @feat_num is meant 349 * @fval: the value (SP or NN) to activate, or NULL to use the default value 350 * 351 * For general use this function is preferable over __dccp_feat_activate(). 352 */ 353 static int dccp_feat_activate(struct sock *sk, u8 feat_num, bool local, 354 dccp_feat_val const *fval) 355 { 356 return __dccp_feat_activate(sk, dccp_feat_index(feat_num), local, fval); 357 } 358 359 /* Test for "Req'd" feature (RFC 4340, 6.4) */ 360 static inline int dccp_feat_must_be_understood(u8 feat_num) 361 { 362 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS || 363 feat_num == DCCPF_SEQUENCE_WINDOW; 364 } 365 366 /* copy constructor, fval must not already contain allocated memory */ 367 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len) 368 { 369 fval->sp.len = len; 370 if (fval->sp.len > 0) { 371 fval->sp.vec = kmemdup(val, len, gfp_any()); 372 if (fval->sp.vec == NULL) { 373 fval->sp.len = 0; 374 return -ENOBUFS; 375 } 376 } 377 return 0; 378 } 379 380 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val) 381 { 382 if (unlikely(val == NULL)) 383 return; 384 if (dccp_feat_type(feat_num) == FEAT_SP) 385 kfree(val->sp.vec); 386 memset(val, 0, sizeof(*val)); 387 } 388 389 static struct dccp_feat_entry * 390 dccp_feat_clone_entry(struct dccp_feat_entry const *original) 391 { 392 struct dccp_feat_entry *new; 393 u8 type = dccp_feat_type(original->feat_num); 394 395 if (type == FEAT_UNKNOWN) 396 return NULL; 397 398 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any()); 399 if (new == NULL) 400 return NULL; 401 402 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val, 403 original->val.sp.vec, 404 original->val.sp.len)) { 405 kfree(new); 406 return NULL; 407 } 408 return new; 409 } 410 411 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry) 412 { 413 if (entry != NULL) { 414 dccp_feat_val_destructor(entry->feat_num, &entry->val); 415 kfree(entry); 416 } 417 } 418 419 /* 420 * List management functions 421 * 422 * Feature negotiation lists rely on and maintain the following invariants: 423 * - each feat_num in the list is known, i.e. we know its type and default value 424 * - each feat_num/is_local combination is unique (old entries are overwritten) 425 * - SP values are always freshly allocated 426 * - list is sorted in increasing order of feature number (faster lookup) 427 */ 428 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list, 429 u8 feat_num, bool is_local) 430 { 431 struct dccp_feat_entry *entry; 432 433 list_for_each_entry(entry, fn_list, node) { 434 if (entry->feat_num == feat_num && entry->is_local == is_local) 435 return entry; 436 else if (entry->feat_num > feat_num) 437 break; 438 } 439 return NULL; 440 } 441 442 /** 443 * dccp_feat_entry_new - Central list update routine (called by all others) 444 * @head: list to add to 445 * @feat: feature number 446 * @local: whether the local (1) or remote feature with number @feat is meant 447 * 448 * This is the only constructor and serves to ensure the above invariants. 449 */ 450 static struct dccp_feat_entry * 451 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local) 452 { 453 struct dccp_feat_entry *entry; 454 455 list_for_each_entry(entry, head, node) 456 if (entry->feat_num == feat && entry->is_local == local) { 457 dccp_feat_val_destructor(entry->feat_num, &entry->val); 458 return entry; 459 } else if (entry->feat_num > feat) { 460 head = &entry->node; 461 break; 462 } 463 464 entry = kmalloc(sizeof(*entry), gfp_any()); 465 if (entry != NULL) { 466 entry->feat_num = feat; 467 entry->is_local = local; 468 list_add_tail(&entry->node, head); 469 } 470 return entry; 471 } 472 473 /** 474 * dccp_feat_push_change - Add/overwrite a Change option in the list 475 * @fn_list: feature-negotiation list to update 476 * @feat: one of %dccp_feature_numbers 477 * @local: whether local (1) or remote (0) @feat_num is meant 478 * @mandatory: whether to use Mandatory feature negotiation options 479 * @fval: pointer to NN/SP value to be inserted (will be copied) 480 */ 481 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local, 482 u8 mandatory, dccp_feat_val *fval) 483 { 484 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 485 486 if (new == NULL) 487 return -ENOMEM; 488 489 new->feat_num = feat; 490 new->is_local = local; 491 new->state = FEAT_INITIALISING; 492 new->needs_confirm = false; 493 new->empty_confirm = false; 494 new->val = *fval; 495 new->needs_mandatory = mandatory; 496 497 return 0; 498 } 499 500 /** 501 * dccp_feat_push_confirm - Add a Confirm entry to the FN list 502 * @fn_list: feature-negotiation list to add to 503 * @feat: one of %dccp_feature_numbers 504 * @local: whether local (1) or remote (0) @feat_num is being confirmed 505 * @fval: pointer to NN/SP value to be inserted or NULL 506 * 507 * Returns 0 on success, a Reset code for further processing otherwise. 508 */ 509 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local, 510 dccp_feat_val *fval) 511 { 512 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 513 514 if (new == NULL) 515 return DCCP_RESET_CODE_TOO_BUSY; 516 517 new->feat_num = feat; 518 new->is_local = local; 519 new->state = FEAT_STABLE; /* transition in 6.6.2 */ 520 new->needs_confirm = true; 521 new->empty_confirm = (fval == NULL); 522 new->val.nn = 0; /* zeroes the whole structure */ 523 if (!new->empty_confirm) 524 new->val = *fval; 525 new->needs_mandatory = false; 526 527 return 0; 528 } 529 530 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local) 531 { 532 return dccp_feat_push_confirm(fn_list, feat, local, NULL); 533 } 534 535 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry) 536 { 537 list_del(&entry->node); 538 dccp_feat_entry_destructor(entry); 539 } 540 541 void dccp_feat_list_purge(struct list_head *fn_list) 542 { 543 struct dccp_feat_entry *entry, *next; 544 545 list_for_each_entry_safe(entry, next, fn_list, node) 546 dccp_feat_entry_destructor(entry); 547 INIT_LIST_HEAD(fn_list); 548 } 549 EXPORT_SYMBOL_GPL(dccp_feat_list_purge); 550 551 /* generate @to as full clone of @from - @to must not contain any nodes */ 552 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to) 553 { 554 struct dccp_feat_entry *entry, *new; 555 556 INIT_LIST_HEAD(to); 557 list_for_each_entry(entry, from, node) { 558 new = dccp_feat_clone_entry(entry); 559 if (new == NULL) 560 goto cloning_failed; 561 list_add_tail(&new->node, to); 562 } 563 return 0; 564 565 cloning_failed: 566 dccp_feat_list_purge(to); 567 return -ENOMEM; 568 } 569 570 /** 571 * dccp_feat_valid_nn_length - Enforce length constraints on NN options 572 * @feat_num: feature to return length of, one of %dccp_feature_numbers 573 * 574 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only, 575 * incoming options are accepted as long as their values are valid. 576 */ 577 static u8 dccp_feat_valid_nn_length(u8 feat_num) 578 { 579 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */ 580 return 2; 581 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */ 582 return 6; 583 return 0; 584 } 585 586 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val) 587 { 588 switch (feat_num) { 589 case DCCPF_ACK_RATIO: 590 return val <= DCCPF_ACK_RATIO_MAX; 591 case DCCPF_SEQUENCE_WINDOW: 592 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX; 593 } 594 return 0; /* feature unknown - so we can't tell */ 595 } 596 597 /* check that SP values are within the ranges defined in RFC 4340 */ 598 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val) 599 { 600 switch (feat_num) { 601 case DCCPF_CCID: 602 return val == DCCPC_CCID2 || val == DCCPC_CCID3; 603 /* Type-check Boolean feature values: */ 604 case DCCPF_SHORT_SEQNOS: 605 case DCCPF_ECN_INCAPABLE: 606 case DCCPF_SEND_ACK_VECTOR: 607 case DCCPF_SEND_NDP_COUNT: 608 case DCCPF_DATA_CHECKSUM: 609 case DCCPF_SEND_LEV_RATE: 610 return val < 2; 611 case DCCPF_MIN_CSUM_COVER: 612 return val < 16; 613 } 614 return 0; /* feature unknown */ 615 } 616 617 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len) 618 { 619 if (sp_list == NULL || sp_len < 1) 620 return 0; 621 while (sp_len--) 622 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++)) 623 return 0; 624 return 1; 625 } 626 627 /** 628 * dccp_feat_insert_opts - Generate FN options from current list state 629 * @skb: next sk_buff to be sent to the peer 630 * @dp: for client during handshake and general negotiation 631 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND) 632 */ 633 int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq, 634 struct sk_buff *skb) 635 { 636 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 637 struct dccp_feat_entry *pos, *next; 638 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN]; 639 bool rpt; 640 641 /* put entries into @skb in the order they appear in the list */ 642 list_for_each_entry_safe_reverse(pos, next, fn, node) { 643 opt = dccp_feat_genopt(pos); 644 type = dccp_feat_type(pos->feat_num); 645 rpt = false; 646 647 if (pos->empty_confirm) { 648 len = 0; 649 ptr = NULL; 650 } else { 651 if (type == FEAT_SP) { 652 len = pos->val.sp.len; 653 ptr = pos->val.sp.vec; 654 rpt = pos->needs_confirm; 655 } else if (type == FEAT_NN) { 656 len = dccp_feat_valid_nn_length(pos->feat_num); 657 ptr = nn_in_nbo; 658 dccp_encode_value_var(pos->val.nn, ptr, len); 659 } else { 660 DCCP_BUG("unknown feature %u", pos->feat_num); 661 return -1; 662 } 663 } 664 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0); 665 666 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt)) 667 return -1; 668 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb)) 669 return -1; 670 671 if (skb->sk->sk_state == DCCP_OPEN && 672 (opt == DCCPO_CONFIRM_R || opt == DCCPO_CONFIRM_L)) { 673 /* 674 * Confirms don't get retransmitted (6.6.3) once the 675 * connection is in state OPEN 676 */ 677 dccp_feat_list_pop(pos); 678 } else { 679 /* 680 * Enter CHANGING after transmitting the Change 681 * option (6.6.2). 682 */ 683 if (pos->state == FEAT_INITIALISING) 684 pos->state = FEAT_CHANGING; 685 } 686 } 687 return 0; 688 } 689 690 /** 691 * __feat_register_nn - Register new NN value on socket 692 * @fn: feature-negotiation list to register with 693 * @feat: an NN feature from %dccp_feature_numbers 694 * @mandatory: use Mandatory option if 1 695 * @nn_val: value to register (restricted to 4 bytes) 696 * 697 * Note that NN features are local by definition (RFC 4340, 6.3.2). 698 */ 699 static int __feat_register_nn(struct list_head *fn, u8 feat, 700 u8 mandatory, u64 nn_val) 701 { 702 dccp_feat_val fval = { .nn = nn_val }; 703 704 if (dccp_feat_type(feat) != FEAT_NN || 705 !dccp_feat_is_valid_nn_val(feat, nn_val)) 706 return -EINVAL; 707 708 /* Don't bother with default values, they will be activated anyway. */ 709 if (nn_val - (u64)dccp_feat_default_value(feat) == 0) 710 return 0; 711 712 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval); 713 } 714 715 /** 716 * __feat_register_sp - Register new SP value/list on socket 717 * @fn: feature-negotiation list to register with 718 * @feat: an SP feature from %dccp_feature_numbers 719 * @is_local: whether the local (1) or the remote (0) @feat is meant 720 * @mandatory: use Mandatory option if 1 721 * @sp_val: SP value followed by optional preference list 722 * @sp_len: length of @sp_val in bytes 723 */ 724 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local, 725 u8 mandatory, u8 const *sp_val, u8 sp_len) 726 { 727 dccp_feat_val fval; 728 729 if (dccp_feat_type(feat) != FEAT_SP || 730 !dccp_feat_sp_list_ok(feat, sp_val, sp_len)) 731 return -EINVAL; 732 733 /* Avoid negotiating alien CCIDs by only advertising supported ones */ 734 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len)) 735 return -EOPNOTSUPP; 736 737 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len)) 738 return -ENOMEM; 739 740 if (dccp_feat_push_change(fn, feat, is_local, mandatory, &fval)) { 741 kfree(fval.sp.vec); 742 return -ENOMEM; 743 } 744 745 return 0; 746 } 747 748 /** 749 * dccp_feat_register_sp - Register requests to change SP feature values 750 * @sk: client or listening socket 751 * @feat: one of %dccp_feature_numbers 752 * @is_local: whether the local (1) or remote (0) @feat is meant 753 * @list: array of preferred values, in descending order of preference 754 * @len: length of @list in bytes 755 */ 756 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, 757 u8 const *list, u8 len) 758 { /* any changes must be registered before establishing the connection */ 759 if (sk->sk_state != DCCP_CLOSED) 760 return -EISCONN; 761 if (dccp_feat_type(feat) != FEAT_SP) 762 return -EINVAL; 763 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local, 764 0, list, len); 765 } 766 767 /** 768 * dccp_feat_nn_get - Query current/pending value of NN feature 769 * @sk: DCCP socket of an established connection 770 * @feat: NN feature number from %dccp_feature_numbers 771 * 772 * For a known NN feature, returns value currently being negotiated, or 773 * current (confirmed) value if no negotiation is going on. 774 */ 775 u64 dccp_feat_nn_get(struct sock *sk, u8 feat) 776 { 777 if (dccp_feat_type(feat) == FEAT_NN) { 778 struct dccp_sock *dp = dccp_sk(sk); 779 struct dccp_feat_entry *entry; 780 781 entry = dccp_feat_list_lookup(&dp->dccps_featneg, feat, 1); 782 if (entry != NULL) 783 return entry->val.nn; 784 785 switch (feat) { 786 case DCCPF_ACK_RATIO: 787 return dp->dccps_l_ack_ratio; 788 case DCCPF_SEQUENCE_WINDOW: 789 return dp->dccps_l_seq_win; 790 } 791 } 792 DCCP_BUG("attempt to look up unsupported feature %u", feat); 793 return 0; 794 } 795 EXPORT_SYMBOL_GPL(dccp_feat_nn_get); 796 797 /** 798 * dccp_feat_signal_nn_change - Update NN values for an established connection 799 * @sk: DCCP socket of an established connection 800 * @feat: NN feature number from %dccp_feature_numbers 801 * @nn_val: the new value to use 802 * 803 * This function is used to communicate NN updates out-of-band. 804 */ 805 int dccp_feat_signal_nn_change(struct sock *sk, u8 feat, u64 nn_val) 806 { 807 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 808 dccp_feat_val fval = { .nn = nn_val }; 809 struct dccp_feat_entry *entry; 810 811 if (sk->sk_state != DCCP_OPEN && sk->sk_state != DCCP_PARTOPEN) 812 return 0; 813 814 if (dccp_feat_type(feat) != FEAT_NN || 815 !dccp_feat_is_valid_nn_val(feat, nn_val)) 816 return -EINVAL; 817 818 if (nn_val == dccp_feat_nn_get(sk, feat)) 819 return 0; /* already set or negotiation under way */ 820 821 entry = dccp_feat_list_lookup(fn, feat, 1); 822 if (entry != NULL) { 823 dccp_pr_debug("Clobbering existing NN entry %llu -> %llu\n", 824 (unsigned long long)entry->val.nn, 825 (unsigned long long)nn_val); 826 dccp_feat_list_pop(entry); 827 } 828 829 inet_csk_schedule_ack(sk); 830 return dccp_feat_push_change(fn, feat, 1, 0, &fval); 831 } 832 EXPORT_SYMBOL_GPL(dccp_feat_signal_nn_change); 833 834 /* 835 * Tracking features whose value depend on the choice of CCID 836 * 837 * This is designed with an extension in mind so that a list walk could be done 838 * before activating any features. However, the existing framework was found to 839 * work satisfactorily up until now, the automatic verification is left open. 840 * When adding new CCIDs, add a corresponding dependency table here. 841 */ 842 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local) 843 { 844 static const struct ccid_dependency ccid2_dependencies[2][2] = { 845 /* 846 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX 847 * feature and Send Ack Vector is an RX feature, `is_local' 848 * needs to be reversed. 849 */ 850 { /* Dependencies of the receiver-side (remote) CCID2 */ 851 { 852 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 853 .is_local = true, 854 .is_mandatory = true, 855 .val = 1 856 }, 857 { 0, 0, 0, 0 } 858 }, 859 { /* Dependencies of the sender-side (local) CCID2 */ 860 { 861 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 862 .is_local = false, 863 .is_mandatory = true, 864 .val = 1 865 }, 866 { 0, 0, 0, 0 } 867 } 868 }; 869 static const struct ccid_dependency ccid3_dependencies[2][5] = { 870 { /* 871 * Dependencies of the receiver-side CCID3 872 */ 873 { /* locally disable Ack Vectors */ 874 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 875 .is_local = true, 876 .is_mandatory = false, 877 .val = 0 878 }, 879 { /* see below why Send Loss Event Rate is on */ 880 .dependent_feat = DCCPF_SEND_LEV_RATE, 881 .is_local = true, 882 .is_mandatory = true, 883 .val = 1 884 }, 885 { /* NDP Count is needed as per RFC 4342, 6.1.1 */ 886 .dependent_feat = DCCPF_SEND_NDP_COUNT, 887 .is_local = false, 888 .is_mandatory = true, 889 .val = 1 890 }, 891 { 0, 0, 0, 0 }, 892 }, 893 { /* 894 * CCID3 at the TX side: we request that the HC-receiver 895 * will not send Ack Vectors (they will be ignored, so 896 * Mandatory is not set); we enable Send Loss Event Rate 897 * (Mandatory since the implementation does not support 898 * the Loss Intervals option of RFC 4342, 8.6). 899 * The last two options are for peer's information only. 900 */ 901 { 902 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 903 .is_local = false, 904 .is_mandatory = false, 905 .val = 0 906 }, 907 { 908 .dependent_feat = DCCPF_SEND_LEV_RATE, 909 .is_local = false, 910 .is_mandatory = true, 911 .val = 1 912 }, 913 { /* this CCID does not support Ack Ratio */ 914 .dependent_feat = DCCPF_ACK_RATIO, 915 .is_local = true, 916 .is_mandatory = false, 917 .val = 0 918 }, 919 { /* tell receiver we are sending NDP counts */ 920 .dependent_feat = DCCPF_SEND_NDP_COUNT, 921 .is_local = true, 922 .is_mandatory = false, 923 .val = 1 924 }, 925 { 0, 0, 0, 0 } 926 } 927 }; 928 switch (ccid) { 929 case DCCPC_CCID2: 930 return ccid2_dependencies[is_local]; 931 case DCCPC_CCID3: 932 return ccid3_dependencies[is_local]; 933 default: 934 return NULL; 935 } 936 } 937 938 /** 939 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID 940 * @fn: feature-negotiation list to update 941 * @id: CCID number to track 942 * @is_local: whether TX CCID (1) or RX CCID (0) is meant 943 * 944 * This function needs to be called after registering all other features. 945 */ 946 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local) 947 { 948 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local); 949 int i, rc = (table == NULL); 950 951 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++) 952 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP) 953 rc = __feat_register_sp(fn, table[i].dependent_feat, 954 table[i].is_local, 955 table[i].is_mandatory, 956 &table[i].val, 1); 957 else 958 rc = __feat_register_nn(fn, table[i].dependent_feat, 959 table[i].is_mandatory, 960 table[i].val); 961 return rc; 962 } 963 964 /** 965 * dccp_feat_finalise_settings - Finalise settings before starting negotiation 966 * @dp: client or listening socket (settings will be inherited) 967 * 968 * This is called after all registrations (socket initialisation, sysctls, and 969 * sockopt calls), and before sending the first packet containing Change options 970 * (ie. client-Request or server-Response), to ensure internal consistency. 971 */ 972 int dccp_feat_finalise_settings(struct dccp_sock *dp) 973 { 974 struct list_head *fn = &dp->dccps_featneg; 975 struct dccp_feat_entry *entry; 976 int i = 2, ccids[2] = { -1, -1 }; 977 978 /* 979 * Propagating CCIDs: 980 * 1) not useful to propagate CCID settings if this host advertises more 981 * than one CCID: the choice of CCID may still change - if this is 982 * the client, or if this is the server and the client sends 983 * singleton CCID values. 984 * 2) since is that propagate_ccid changes the list, we defer changing 985 * the sorted list until after the traversal. 986 */ 987 list_for_each_entry(entry, fn, node) 988 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1) 989 ccids[entry->is_local] = entry->val.sp.vec[0]; 990 while (i--) 991 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i)) 992 return -1; 993 dccp_feat_print_fnlist(fn); 994 return 0; 995 } 996 997 /** 998 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features 999 * @dreq: server socket to resolve 1000 * 1001 * It is the server which resolves the dependencies once the CCID has been 1002 * fully negotiated. If no CCID has been negotiated, it uses the default CCID. 1003 */ 1004 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq) 1005 { 1006 struct list_head *fn = &dreq->dreq_featneg; 1007 struct dccp_feat_entry *entry; 1008 u8 is_local, ccid; 1009 1010 for (is_local = 0; is_local <= 1; is_local++) { 1011 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local); 1012 1013 if (entry != NULL && !entry->empty_confirm) 1014 ccid = entry->val.sp.vec[0]; 1015 else 1016 ccid = dccp_feat_default_value(DCCPF_CCID); 1017 1018 if (dccp_feat_propagate_ccid(fn, ccid, is_local)) 1019 return -1; 1020 } 1021 return 0; 1022 } 1023 1024 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */ 1025 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen) 1026 { 1027 u8 c, s; 1028 1029 for (s = 0; s < slen; s++) 1030 for (c = 0; c < clen; c++) 1031 if (servlist[s] == clilist[c]) 1032 return servlist[s]; 1033 return -1; 1034 } 1035 1036 /** 1037 * dccp_feat_prefer - Move preferred entry to the start of array 1038 * @preferred_value: entry to move to start of array 1039 * @array: array of preferred entries 1040 * @array_len: size of the array 1041 * 1042 * Reorder the @array_len elements in @array so that @preferred_value comes 1043 * first. Returns >0 to indicate that @preferred_value does occur in @array. 1044 */ 1045 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len) 1046 { 1047 u8 i, does_occur = 0; 1048 1049 if (array != NULL) { 1050 for (i = 0; i < array_len; i++) 1051 if (array[i] == preferred_value) { 1052 array[i] = array[0]; 1053 does_occur++; 1054 } 1055 if (does_occur) 1056 array[0] = preferred_value; 1057 } 1058 return does_occur; 1059 } 1060 1061 /** 1062 * dccp_feat_reconcile - Reconcile SP preference lists 1063 * @fv: SP list to reconcile into 1064 * @arr: received SP preference list 1065 * @len: length of @arr in bytes 1066 * @is_server: whether this side is the server (and @fv is the server's list) 1067 * @reorder: whether to reorder the list in @fv after reconciling with @arr 1068 * When successful, > 0 is returned and the reconciled list is in @fval. 1069 * A value of 0 means that negotiation failed (no shared entry). 1070 */ 1071 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len, 1072 bool is_server, bool reorder) 1073 { 1074 int rc; 1075 1076 if (!fv->sp.vec || !arr) { 1077 DCCP_CRIT("NULL feature value or array"); 1078 return 0; 1079 } 1080 1081 if (is_server) 1082 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len); 1083 else 1084 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len); 1085 1086 if (!reorder) 1087 return rc; 1088 if (rc < 0) 1089 return 0; 1090 1091 /* 1092 * Reorder list: used for activating features and in dccp_insert_fn_opt. 1093 */ 1094 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len); 1095 } 1096 1097 /** 1098 * dccp_feat_change_recv - Process incoming ChangeL/R options 1099 * @fn: feature-negotiation list to update 1100 * @is_mandatory: whether the Change was preceded by a Mandatory option 1101 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R 1102 * @feat: one of %dccp_feature_numbers 1103 * @val: NN value or SP value/preference list 1104 * @len: length of @val in bytes 1105 * @server: whether this node is the server (1) or the client (0) 1106 */ 1107 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1108 u8 feat, u8 *val, u8 len, const bool server) 1109 { 1110 u8 defval, type = dccp_feat_type(feat); 1111 const bool local = (opt == DCCPO_CHANGE_R); 1112 struct dccp_feat_entry *entry; 1113 dccp_feat_val fval; 1114 1115 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */ 1116 goto unknown_feature_or_value; 1117 1118 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1119 1120 /* 1121 * Negotiation of NN features: Change R is invalid, so there is no 1122 * simultaneous negotiation; hence we do not look up in the list. 1123 */ 1124 if (type == FEAT_NN) { 1125 if (local || len > sizeof(fval.nn)) 1126 goto unknown_feature_or_value; 1127 1128 /* 6.3.2: "The feature remote MUST accept any valid value..." */ 1129 fval.nn = dccp_decode_value_var(val, len); 1130 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1131 goto unknown_feature_or_value; 1132 1133 return dccp_feat_push_confirm(fn, feat, local, &fval); 1134 } 1135 1136 /* 1137 * Unidirectional/simultaneous negotiation of SP features (6.3.1) 1138 */ 1139 entry = dccp_feat_list_lookup(fn, feat, local); 1140 if (entry == NULL) { 1141 /* 1142 * No particular preferences have been registered. We deal with 1143 * this situation by assuming that all valid values are equally 1144 * acceptable, and apply the following checks: 1145 * - if the peer's list is a singleton, we accept a valid value; 1146 * - if we are the server, we first try to see if the peer (the 1147 * client) advertises the default value. If yes, we use it, 1148 * otherwise we accept the preferred value; 1149 * - else if we are the client, we use the first list element. 1150 */ 1151 if (dccp_feat_clone_sp_val(&fval, val, 1)) 1152 return DCCP_RESET_CODE_TOO_BUSY; 1153 1154 if (len > 1 && server) { 1155 defval = dccp_feat_default_value(feat); 1156 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1) 1157 fval.sp.vec[0] = defval; 1158 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) { 1159 kfree(fval.sp.vec); 1160 goto unknown_feature_or_value; 1161 } 1162 1163 /* Treat unsupported CCIDs like invalid values */ 1164 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) { 1165 kfree(fval.sp.vec); 1166 goto not_valid_or_not_known; 1167 } 1168 1169 return dccp_feat_push_confirm(fn, feat, local, &fval); 1170 1171 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */ 1172 return 0; 1173 } 1174 1175 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) { 1176 entry->empty_confirm = false; 1177 } else if (is_mandatory) { 1178 return DCCP_RESET_CODE_MANDATORY_ERROR; 1179 } else if (entry->state == FEAT_INITIALISING) { 1180 /* 1181 * Failed simultaneous negotiation (server only): try to `save' 1182 * the connection by checking whether entry contains the default 1183 * value for @feat. If yes, send an empty Confirm to signal that 1184 * the received Change was not understood - which implies using 1185 * the default value. 1186 * If this also fails, we use Reset as the last resort. 1187 */ 1188 WARN_ON(!server); 1189 defval = dccp_feat_default_value(feat); 1190 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true)) 1191 return DCCP_RESET_CODE_OPTION_ERROR; 1192 entry->empty_confirm = true; 1193 } 1194 entry->needs_confirm = true; 1195 entry->needs_mandatory = false; 1196 entry->state = FEAT_STABLE; 1197 return 0; 1198 1199 unknown_feature_or_value: 1200 if (!is_mandatory) 1201 return dccp_push_empty_confirm(fn, feat, local); 1202 1203 not_valid_or_not_known: 1204 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1205 : DCCP_RESET_CODE_OPTION_ERROR; 1206 } 1207 1208 /** 1209 * dccp_feat_confirm_recv - Process received Confirm options 1210 * @fn: feature-negotiation list to update 1211 * @is_mandatory: whether @opt was preceded by a Mandatory option 1212 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R 1213 * @feat: one of %dccp_feature_numbers 1214 * @val: NN value or SP value/preference list 1215 * @len: length of @val in bytes 1216 * @server: whether this node is server (1) or client (0) 1217 */ 1218 static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1219 u8 feat, u8 *val, u8 len, const bool server) 1220 { 1221 u8 *plist, plen, type = dccp_feat_type(feat); 1222 const bool local = (opt == DCCPO_CONFIRM_R); 1223 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local); 1224 1225 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1226 1227 if (entry == NULL) { /* nothing queued: ignore or handle error */ 1228 if (is_mandatory && type == FEAT_UNKNOWN) 1229 return DCCP_RESET_CODE_MANDATORY_ERROR; 1230 1231 if (!local && type == FEAT_NN) /* 6.3.2 */ 1232 goto confirmation_failed; 1233 return 0; 1234 } 1235 1236 if (entry->state != FEAT_CHANGING) /* 6.6.2 */ 1237 return 0; 1238 1239 if (len == 0) { 1240 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */ 1241 goto confirmation_failed; 1242 /* 1243 * Empty Confirm during connection setup: this means reverting 1244 * to the `old' value, which in this case is the default. Since 1245 * we handle default values automatically when no other values 1246 * have been set, we revert to the old value by removing this 1247 * entry from the list. 1248 */ 1249 dccp_feat_list_pop(entry); 1250 return 0; 1251 } 1252 1253 if (type == FEAT_NN) { 1254 if (len > sizeof(entry->val.nn)) 1255 goto confirmation_failed; 1256 1257 if (entry->val.nn == dccp_decode_value_var(val, len)) 1258 goto confirmation_succeeded; 1259 1260 DCCP_WARN("Bogus Confirm for non-existing value\n"); 1261 goto confirmation_failed; 1262 } 1263 1264 /* 1265 * Parsing SP Confirms: the first element of @val is the preferred 1266 * SP value which the peer confirms, the remainder depends on @len. 1267 * Note that only the confirmed value need to be a valid SP value. 1268 */ 1269 if (!dccp_feat_is_valid_sp_val(feat, *val)) 1270 goto confirmation_failed; 1271 1272 if (len == 1) { /* peer didn't supply a preference list */ 1273 plist = val; 1274 plen = len; 1275 } else { /* preferred value + preference list */ 1276 plist = val + 1; 1277 plen = len - 1; 1278 } 1279 1280 /* Check whether the peer got the reconciliation right (6.6.8) */ 1281 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) { 1282 DCCP_WARN("Confirm selected the wrong value %u\n", *val); 1283 return DCCP_RESET_CODE_OPTION_ERROR; 1284 } 1285 entry->val.sp.vec[0] = *val; 1286 1287 confirmation_succeeded: 1288 entry->state = FEAT_STABLE; 1289 return 0; 1290 1291 confirmation_failed: 1292 DCCP_WARN("Confirmation failed\n"); 1293 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1294 : DCCP_RESET_CODE_OPTION_ERROR; 1295 } 1296 1297 /** 1298 * dccp_feat_handle_nn_established - Fast-path reception of NN options 1299 * @sk: socket of an established DCCP connection 1300 * @mandatory: whether @opt was preceded by a Mandatory option 1301 * @opt: %DCCPO_CHANGE_L | %DCCPO_CONFIRM_R (NN only) 1302 * @feat: NN number, one of %dccp_feature_numbers 1303 * @val: NN value 1304 * @len: length of @val in bytes 1305 * 1306 * This function combines the functionality of change_recv/confirm_recv, with 1307 * the following differences (reset codes are the same): 1308 * - cleanup after receiving the Confirm; 1309 * - values are directly activated after successful parsing; 1310 * - deliberately restricted to NN features. 1311 * The restriction to NN features is essential since SP features can have non- 1312 * predictable outcomes (depending on the remote configuration), and are inter- 1313 * dependent (CCIDs for instance cause further dependencies). 1314 */ 1315 static u8 dccp_feat_handle_nn_established(struct sock *sk, u8 mandatory, u8 opt, 1316 u8 feat, u8 *val, u8 len) 1317 { 1318 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1319 const bool local = (opt == DCCPO_CONFIRM_R); 1320 struct dccp_feat_entry *entry; 1321 u8 type = dccp_feat_type(feat); 1322 dccp_feat_val fval; 1323 1324 dccp_feat_print_opt(opt, feat, val, len, mandatory); 1325 1326 /* Ignore non-mandatory unknown and non-NN features */ 1327 if (type == FEAT_UNKNOWN) { 1328 if (local && !mandatory) 1329 return 0; 1330 goto fast_path_unknown; 1331 } else if (type != FEAT_NN) { 1332 return 0; 1333 } 1334 1335 /* 1336 * We don't accept empty Confirms, since in fast-path feature 1337 * negotiation the values are enabled immediately after sending 1338 * the Change option. 1339 * Empty Changes on the other hand are invalid (RFC 4340, 6.1). 1340 */ 1341 if (len == 0 || len > sizeof(fval.nn)) 1342 goto fast_path_unknown; 1343 1344 if (opt == DCCPO_CHANGE_L) { 1345 fval.nn = dccp_decode_value_var(val, len); 1346 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1347 goto fast_path_unknown; 1348 1349 if (dccp_feat_push_confirm(fn, feat, local, &fval) || 1350 dccp_feat_activate(sk, feat, local, &fval)) 1351 return DCCP_RESET_CODE_TOO_BUSY; 1352 1353 /* set the `Ack Pending' flag to piggyback a Confirm */ 1354 inet_csk_schedule_ack(sk); 1355 1356 } else if (opt == DCCPO_CONFIRM_R) { 1357 entry = dccp_feat_list_lookup(fn, feat, local); 1358 if (entry == NULL || entry->state != FEAT_CHANGING) 1359 return 0; 1360 1361 fval.nn = dccp_decode_value_var(val, len); 1362 /* 1363 * Just ignore a value that doesn't match our current value. 1364 * If the option changes twice within two RTTs, then at least 1365 * one CONFIRM will be received for the old value after a 1366 * new CHANGE was sent. 1367 */ 1368 if (fval.nn != entry->val.nn) 1369 return 0; 1370 1371 /* Only activate after receiving the Confirm option (6.6.1). */ 1372 dccp_feat_activate(sk, feat, local, &fval); 1373 1374 /* It has been confirmed - so remove the entry */ 1375 dccp_feat_list_pop(entry); 1376 1377 } else { 1378 DCCP_WARN("Received illegal option %u\n", opt); 1379 goto fast_path_failed; 1380 } 1381 return 0; 1382 1383 fast_path_unknown: 1384 if (!mandatory) 1385 return dccp_push_empty_confirm(fn, feat, local); 1386 1387 fast_path_failed: 1388 return mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1389 : DCCP_RESET_CODE_OPTION_ERROR; 1390 } 1391 1392 /** 1393 * dccp_feat_parse_options - Process Feature-Negotiation Options 1394 * @sk: for general use and used by the client during connection setup 1395 * @dreq: used by the server during connection setup 1396 * @mandatory: whether @opt was preceded by a Mandatory option 1397 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R 1398 * @feat: one of %dccp_feature_numbers 1399 * @val: value contents of @opt 1400 * @len: length of @val in bytes 1401 * 1402 * Returns 0 on success, a Reset code for ending the connection otherwise. 1403 */ 1404 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 1405 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len) 1406 { 1407 struct dccp_sock *dp = dccp_sk(sk); 1408 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 1409 bool server = false; 1410 1411 switch (sk->sk_state) { 1412 /* 1413 * Negotiation during connection setup 1414 */ 1415 case DCCP_LISTEN: 1416 server = true; 1417 fallthrough; 1418 case DCCP_REQUESTING: 1419 switch (opt) { 1420 case DCCPO_CHANGE_L: 1421 case DCCPO_CHANGE_R: 1422 return dccp_feat_change_recv(fn, mandatory, opt, feat, 1423 val, len, server); 1424 case DCCPO_CONFIRM_R: 1425 case DCCPO_CONFIRM_L: 1426 return dccp_feat_confirm_recv(fn, mandatory, opt, feat, 1427 val, len, server); 1428 } 1429 break; 1430 /* 1431 * Support for exchanging NN options on an established connection. 1432 */ 1433 case DCCP_OPEN: 1434 case DCCP_PARTOPEN: 1435 return dccp_feat_handle_nn_established(sk, mandatory, opt, feat, 1436 val, len); 1437 } 1438 return 0; /* ignore FN options in all other states */ 1439 } 1440 1441 /** 1442 * dccp_feat_init - Seed feature negotiation with host-specific defaults 1443 * @sk: Socket to initialize. 1444 * 1445 * This initialises global defaults, depending on the value of the sysctls. 1446 * These can later be overridden by registering changes via setsockopt calls. 1447 * The last link in the chain is finalise_settings, to make sure that between 1448 * here and the start of actual feature negotiation no inconsistencies enter. 1449 * 1450 * All features not appearing below use either defaults or are otherwise 1451 * later adjusted through dccp_feat_finalise_settings(). 1452 */ 1453 int dccp_feat_init(struct sock *sk) 1454 { 1455 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1456 u8 on = 1, off = 0; 1457 int rc; 1458 struct { 1459 u8 *val; 1460 u8 len; 1461 } tx, rx; 1462 1463 /* Non-negotiable (NN) features */ 1464 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, 1465 sysctl_dccp_sequence_window); 1466 if (rc) 1467 return rc; 1468 1469 /* Server-priority (SP) features */ 1470 1471 /* Advertise that short seqnos are not supported (7.6.1) */ 1472 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); 1473 if (rc) 1474 return rc; 1475 1476 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ 1477 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); 1478 if (rc) 1479 return rc; 1480 1481 /* 1482 * We advertise the available list of CCIDs and reorder according to 1483 * preferences, to avoid failure resulting from negotiating different 1484 * singleton values (which always leads to failure). 1485 * These settings can still (later) be overridden via sockopts. 1486 */ 1487 if (ccid_get_builtin_ccids(&tx.val, &tx.len)) 1488 return -ENOBUFS; 1489 if (ccid_get_builtin_ccids(&rx.val, &rx.len)) { 1490 kfree(tx.val); 1491 return -ENOBUFS; 1492 } 1493 1494 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) || 1495 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len)) 1496 goto free_ccid_lists; 1497 1498 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); 1499 if (rc) 1500 goto free_ccid_lists; 1501 1502 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); 1503 1504 free_ccid_lists: 1505 kfree(tx.val); 1506 kfree(rx.val); 1507 return rc; 1508 } 1509 1510 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) 1511 { 1512 struct dccp_sock *dp = dccp_sk(sk); 1513 struct dccp_feat_entry *cur, *next; 1514 int idx; 1515 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = { 1516 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL } 1517 }; 1518 1519 list_for_each_entry(cur, fn_list, node) { 1520 /* 1521 * An empty Confirm means that either an unknown feature type 1522 * or an invalid value was present. In the first case there is 1523 * nothing to activate, in the other the default value is used. 1524 */ 1525 if (cur->empty_confirm) 1526 continue; 1527 1528 idx = dccp_feat_index(cur->feat_num); 1529 if (idx < 0) { 1530 DCCP_BUG("Unknown feature %u", cur->feat_num); 1531 goto activation_failed; 1532 } 1533 if (cur->state != FEAT_STABLE) { 1534 DCCP_CRIT("Negotiation of %s %s failed in state %s", 1535 cur->is_local ? "local" : "remote", 1536 dccp_feat_fname(cur->feat_num), 1537 dccp_feat_sname[cur->state]); 1538 goto activation_failed; 1539 } 1540 fvals[idx][cur->is_local] = &cur->val; 1541 } 1542 1543 /* 1544 * Activate in decreasing order of index, so that the CCIDs are always 1545 * activated as the last feature. This avoids the case where a CCID 1546 * relies on the initialisation of one or more features that it depends 1547 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features). 1548 */ 1549 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;) 1550 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) || 1551 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) { 1552 DCCP_CRIT("Could not activate %d", idx); 1553 goto activation_failed; 1554 } 1555 1556 /* Clean up Change options which have been confirmed already */ 1557 list_for_each_entry_safe(cur, next, fn_list, node) 1558 if (!cur->needs_confirm) 1559 dccp_feat_list_pop(cur); 1560 1561 dccp_pr_debug("Activation OK\n"); 1562 return 0; 1563 1564 activation_failed: 1565 /* 1566 * We clean up everything that may have been allocated, since 1567 * it is difficult to track at which stage negotiation failed. 1568 * This is ok, since all allocation functions below are robust 1569 * against NULL arguments. 1570 */ 1571 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 1572 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 1573 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; 1574 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 1575 dp->dccps_hc_rx_ackvec = NULL; 1576 return -1; 1577 } 1578