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