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