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 *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 *dccp_feat_sname[] = { "DEFAULT", "INITIALISING", "CHANGING", 240 "UNSTABLE", "STABLE" }; 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 /* Test for "Req'd" feature (RFC 4340, 6.4) */ 345 static inline int dccp_feat_must_be_understood(u8 feat_num) 346 { 347 return feat_num == DCCPF_CCID || feat_num == DCCPF_SHORT_SEQNOS || 348 feat_num == DCCPF_SEQUENCE_WINDOW; 349 } 350 351 /* copy constructor, fval must not already contain allocated memory */ 352 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len) 353 { 354 fval->sp.len = len; 355 if (fval->sp.len > 0) { 356 fval->sp.vec = kmemdup(val, len, gfp_any()); 357 if (fval->sp.vec == NULL) { 358 fval->sp.len = 0; 359 return -ENOBUFS; 360 } 361 } 362 return 0; 363 } 364 365 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val) 366 { 367 if (unlikely(val == NULL)) 368 return; 369 if (dccp_feat_type(feat_num) == FEAT_SP) 370 kfree(val->sp.vec); 371 memset(val, 0, sizeof(*val)); 372 } 373 374 static struct dccp_feat_entry * 375 dccp_feat_clone_entry(struct dccp_feat_entry const *original) 376 { 377 struct dccp_feat_entry *new; 378 u8 type = dccp_feat_type(original->feat_num); 379 380 if (type == FEAT_UNKNOWN) 381 return NULL; 382 383 new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any()); 384 if (new == NULL) 385 return NULL; 386 387 if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val, 388 original->val.sp.vec, 389 original->val.sp.len)) { 390 kfree(new); 391 return NULL; 392 } 393 return new; 394 } 395 396 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry) 397 { 398 if (entry != NULL) { 399 dccp_feat_val_destructor(entry->feat_num, &entry->val); 400 kfree(entry); 401 } 402 } 403 404 /* 405 * List management functions 406 * 407 * Feature negotiation lists rely on and maintain the following invariants: 408 * - each feat_num in the list is known, i.e. we know its type and default value 409 * - each feat_num/is_local combination is unique (old entries are overwritten) 410 * - SP values are always freshly allocated 411 * - list is sorted in increasing order of feature number (faster lookup) 412 */ 413 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list, 414 u8 feat_num, bool is_local) 415 { 416 struct dccp_feat_entry *entry; 417 418 list_for_each_entry(entry, fn_list, node) { 419 if (entry->feat_num == feat_num && entry->is_local == is_local) 420 return entry; 421 else if (entry->feat_num > feat_num) 422 break; 423 } 424 return NULL; 425 } 426 427 /** 428 * dccp_feat_entry_new - Central list update routine (called by all others) 429 * @head: list to add to 430 * @feat: feature number 431 * @local: whether the local (1) or remote feature with number @feat is meant 432 * This is the only constructor and serves to ensure the above invariants. 433 */ 434 static struct dccp_feat_entry * 435 dccp_feat_entry_new(struct list_head *head, u8 feat, bool local) 436 { 437 struct dccp_feat_entry *entry; 438 439 list_for_each_entry(entry, head, node) 440 if (entry->feat_num == feat && entry->is_local == local) { 441 dccp_feat_val_destructor(entry->feat_num, &entry->val); 442 return entry; 443 } else if (entry->feat_num > feat) { 444 head = &entry->node; 445 break; 446 } 447 448 entry = kmalloc(sizeof(*entry), gfp_any()); 449 if (entry != NULL) { 450 entry->feat_num = feat; 451 entry->is_local = local; 452 list_add_tail(&entry->node, head); 453 } 454 return entry; 455 } 456 457 /** 458 * dccp_feat_push_change - Add/overwrite a Change option in the list 459 * @fn_list: feature-negotiation list to update 460 * @feat: one of %dccp_feature_numbers 461 * @local: whether local (1) or remote (0) @feat_num is meant 462 * @needs_mandatory: whether to use Mandatory feature negotiation options 463 * @fval: pointer to NN/SP value to be inserted (will be copied) 464 */ 465 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local, 466 u8 mandatory, dccp_feat_val *fval) 467 { 468 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 469 470 if (new == NULL) 471 return -ENOMEM; 472 473 new->feat_num = feat; 474 new->is_local = local; 475 new->state = FEAT_INITIALISING; 476 new->needs_confirm = 0; 477 new->empty_confirm = 0; 478 new->val = *fval; 479 new->needs_mandatory = mandatory; 480 481 return 0; 482 } 483 484 /** 485 * dccp_feat_push_confirm - Add a Confirm entry to the FN list 486 * @fn_list: feature-negotiation list to add to 487 * @feat: one of %dccp_feature_numbers 488 * @local: whether local (1) or remote (0) @feat_num is being confirmed 489 * @fval: pointer to NN/SP value to be inserted or NULL 490 * Returns 0 on success, a Reset code for further processing otherwise. 491 */ 492 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local, 493 dccp_feat_val *fval) 494 { 495 struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local); 496 497 if (new == NULL) 498 return DCCP_RESET_CODE_TOO_BUSY; 499 500 new->feat_num = feat; 501 new->is_local = local; 502 new->state = FEAT_STABLE; /* transition in 6.6.2 */ 503 new->needs_confirm = 1; 504 new->empty_confirm = (fval == NULL); 505 new->val.nn = 0; /* zeroes the whole structure */ 506 if (!new->empty_confirm) 507 new->val = *fval; 508 new->needs_mandatory = 0; 509 510 return 0; 511 } 512 513 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local) 514 { 515 return dccp_feat_push_confirm(fn_list, feat, local, NULL); 516 } 517 518 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry) 519 { 520 list_del(&entry->node); 521 dccp_feat_entry_destructor(entry); 522 } 523 524 void dccp_feat_list_purge(struct list_head *fn_list) 525 { 526 struct dccp_feat_entry *entry, *next; 527 528 list_for_each_entry_safe(entry, next, fn_list, node) 529 dccp_feat_entry_destructor(entry); 530 INIT_LIST_HEAD(fn_list); 531 } 532 EXPORT_SYMBOL_GPL(dccp_feat_list_purge); 533 534 /* generate @to as full clone of @from - @to must not contain any nodes */ 535 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to) 536 { 537 struct dccp_feat_entry *entry, *new; 538 539 INIT_LIST_HEAD(to); 540 list_for_each_entry(entry, from, node) { 541 new = dccp_feat_clone_entry(entry); 542 if (new == NULL) 543 goto cloning_failed; 544 list_add_tail(&new->node, to); 545 } 546 return 0; 547 548 cloning_failed: 549 dccp_feat_list_purge(to); 550 return -ENOMEM; 551 } 552 553 /** 554 * dccp_feat_valid_nn_length - Enforce length constraints on NN options 555 * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only, 556 * incoming options are accepted as long as their values are valid. 557 */ 558 static u8 dccp_feat_valid_nn_length(u8 feat_num) 559 { 560 if (feat_num == DCCPF_ACK_RATIO) /* RFC 4340, 11.3 and 6.6.8 */ 561 return 2; 562 if (feat_num == DCCPF_SEQUENCE_WINDOW) /* RFC 4340, 7.5.2 and 6.5 */ 563 return 6; 564 return 0; 565 } 566 567 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val) 568 { 569 switch (feat_num) { 570 case DCCPF_ACK_RATIO: 571 return val <= DCCPF_ACK_RATIO_MAX; 572 case DCCPF_SEQUENCE_WINDOW: 573 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX; 574 } 575 return 0; /* feature unknown - so we can't tell */ 576 } 577 578 /* check that SP values are within the ranges defined in RFC 4340 */ 579 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val) 580 { 581 switch (feat_num) { 582 case DCCPF_CCID: 583 return val == DCCPC_CCID2 || val == DCCPC_CCID3; 584 /* Type-check Boolean feature values: */ 585 case DCCPF_SHORT_SEQNOS: 586 case DCCPF_ECN_INCAPABLE: 587 case DCCPF_SEND_ACK_VECTOR: 588 case DCCPF_SEND_NDP_COUNT: 589 case DCCPF_DATA_CHECKSUM: 590 case DCCPF_SEND_LEV_RATE: 591 return val < 2; 592 case DCCPF_MIN_CSUM_COVER: 593 return val < 16; 594 } 595 return 0; /* feature unknown */ 596 } 597 598 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len) 599 { 600 if (sp_list == NULL || sp_len < 1) 601 return 0; 602 while (sp_len--) 603 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++)) 604 return 0; 605 return 1; 606 } 607 608 /** 609 * dccp_feat_insert_opts - Generate FN options from current list state 610 * @skb: next sk_buff to be sent to the peer 611 * @dp: for client during handshake and general negotiation 612 * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND) 613 */ 614 int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq, 615 struct sk_buff *skb) 616 { 617 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 618 struct dccp_feat_entry *pos, *next; 619 u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN]; 620 bool rpt; 621 622 /* put entries into @skb in the order they appear in the list */ 623 list_for_each_entry_safe_reverse(pos, next, fn, node) { 624 opt = dccp_feat_genopt(pos); 625 type = dccp_feat_type(pos->feat_num); 626 rpt = false; 627 628 if (pos->empty_confirm) { 629 len = 0; 630 ptr = NULL; 631 } else { 632 if (type == FEAT_SP) { 633 len = pos->val.sp.len; 634 ptr = pos->val.sp.vec; 635 rpt = pos->needs_confirm; 636 } else if (type == FEAT_NN) { 637 len = dccp_feat_valid_nn_length(pos->feat_num); 638 ptr = nn_in_nbo; 639 dccp_encode_value_var(pos->val.nn, ptr, len); 640 } else { 641 DCCP_BUG("unknown feature %u", pos->feat_num); 642 return -1; 643 } 644 } 645 dccp_feat_print_opt(opt, pos->feat_num, ptr, len, 0); 646 647 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt)) 648 return -1; 649 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb)) 650 return -1; 651 /* 652 * Enter CHANGING after transmitting the Change option (6.6.2). 653 */ 654 if (pos->state == FEAT_INITIALISING) 655 pos->state = FEAT_CHANGING; 656 } 657 return 0; 658 } 659 660 /** 661 * __feat_register_nn - Register new NN value on socket 662 * @fn: feature-negotiation list to register with 663 * @feat: an NN feature from %dccp_feature_numbers 664 * @mandatory: use Mandatory option if 1 665 * @nn_val: value to register (restricted to 4 bytes) 666 * Note that NN features are local by definition (RFC 4340, 6.3.2). 667 */ 668 static int __feat_register_nn(struct list_head *fn, u8 feat, 669 u8 mandatory, u64 nn_val) 670 { 671 dccp_feat_val fval = { .nn = nn_val }; 672 673 if (dccp_feat_type(feat) != FEAT_NN || 674 !dccp_feat_is_valid_nn_val(feat, nn_val)) 675 return -EINVAL; 676 677 /* Don't bother with default values, they will be activated anyway. */ 678 if (nn_val - (u64)dccp_feat_default_value(feat) == 0) 679 return 0; 680 681 return dccp_feat_push_change(fn, feat, 1, mandatory, &fval); 682 } 683 684 /** 685 * __feat_register_sp - Register new SP value/list on socket 686 * @fn: feature-negotiation list to register with 687 * @feat: an SP feature from %dccp_feature_numbers 688 * @is_local: whether the local (1) or the remote (0) @feat is meant 689 * @mandatory: use Mandatory option if 1 690 * @sp_val: SP value followed by optional preference list 691 * @sp_len: length of @sp_val in bytes 692 */ 693 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local, 694 u8 mandatory, u8 const *sp_val, u8 sp_len) 695 { 696 dccp_feat_val fval; 697 698 if (dccp_feat_type(feat) != FEAT_SP || 699 !dccp_feat_sp_list_ok(feat, sp_val, sp_len)) 700 return -EINVAL; 701 702 /* Avoid negotiating alien CCIDs by only advertising supported ones */ 703 if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len)) 704 return -EOPNOTSUPP; 705 706 if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len)) 707 return -ENOMEM; 708 709 return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval); 710 } 711 712 /** 713 * dccp_feat_register_sp - Register requests to change SP feature values 714 * @sk: client or listening socket 715 * @feat: one of %dccp_feature_numbers 716 * @is_local: whether the local (1) or remote (0) @feat is meant 717 * @list: array of preferred values, in descending order of preference 718 * @len: length of @list in bytes 719 */ 720 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local, 721 u8 const *list, u8 len) 722 { /* any changes must be registered before establishing the connection */ 723 if (sk->sk_state != DCCP_CLOSED) 724 return -EISCONN; 725 if (dccp_feat_type(feat) != FEAT_SP) 726 return -EINVAL; 727 return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local, 728 0, list, len); 729 } 730 731 /* Analogous to dccp_feat_register_sp(), but for non-negotiable values */ 732 int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val) 733 { 734 /* any changes must be registered before establishing the connection */ 735 if (sk->sk_state != DCCP_CLOSED) 736 return -EISCONN; 737 if (dccp_feat_type(feat) != FEAT_NN) 738 return -EINVAL; 739 return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val); 740 } 741 742 /* 743 * Tracking features whose value depend on the choice of CCID 744 * 745 * This is designed with an extension in mind so that a list walk could be done 746 * before activating any features. However, the existing framework was found to 747 * work satisfactorily up until now, the automatic verification is left open. 748 * When adding new CCIDs, add a corresponding dependency table here. 749 */ 750 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local) 751 { 752 static const struct ccid_dependency ccid2_dependencies[2][2] = { 753 /* 754 * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX 755 * feature and Send Ack Vector is an RX feature, `is_local' 756 * needs to be reversed. 757 */ 758 { /* Dependencies of the receiver-side (remote) CCID2 */ 759 { 760 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 761 .is_local = true, 762 .is_mandatory = true, 763 .val = 1 764 }, 765 { 0, 0, 0, 0 } 766 }, 767 { /* Dependencies of the sender-side (local) CCID2 */ 768 { 769 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 770 .is_local = false, 771 .is_mandatory = true, 772 .val = 1 773 }, 774 { 0, 0, 0, 0 } 775 } 776 }; 777 static const struct ccid_dependency ccid3_dependencies[2][5] = { 778 { /* 779 * Dependencies of the receiver-side CCID3 780 */ 781 { /* locally disable Ack Vectors */ 782 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 783 .is_local = true, 784 .is_mandatory = false, 785 .val = 0 786 }, 787 { /* see below why Send Loss Event Rate is on */ 788 .dependent_feat = DCCPF_SEND_LEV_RATE, 789 .is_local = true, 790 .is_mandatory = true, 791 .val = 1 792 }, 793 { /* NDP Count is needed as per RFC 4342, 6.1.1 */ 794 .dependent_feat = DCCPF_SEND_NDP_COUNT, 795 .is_local = false, 796 .is_mandatory = true, 797 .val = 1 798 }, 799 { 0, 0, 0, 0 }, 800 }, 801 { /* 802 * CCID3 at the TX side: we request that the HC-receiver 803 * will not send Ack Vectors (they will be ignored, so 804 * Mandatory is not set); we enable Send Loss Event Rate 805 * (Mandatory since the implementation does not support 806 * the Loss Intervals option of RFC 4342, 8.6). 807 * The last two options are for peer's information only. 808 */ 809 { 810 .dependent_feat = DCCPF_SEND_ACK_VECTOR, 811 .is_local = false, 812 .is_mandatory = false, 813 .val = 0 814 }, 815 { 816 .dependent_feat = DCCPF_SEND_LEV_RATE, 817 .is_local = false, 818 .is_mandatory = true, 819 .val = 1 820 }, 821 { /* this CCID does not support Ack Ratio */ 822 .dependent_feat = DCCPF_ACK_RATIO, 823 .is_local = true, 824 .is_mandatory = false, 825 .val = 0 826 }, 827 { /* tell receiver we are sending NDP counts */ 828 .dependent_feat = DCCPF_SEND_NDP_COUNT, 829 .is_local = true, 830 .is_mandatory = false, 831 .val = 1 832 }, 833 { 0, 0, 0, 0 } 834 } 835 }; 836 switch (ccid) { 837 case DCCPC_CCID2: 838 return ccid2_dependencies[is_local]; 839 case DCCPC_CCID3: 840 return ccid3_dependencies[is_local]; 841 default: 842 return NULL; 843 } 844 } 845 846 /** 847 * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID 848 * @fn: feature-negotiation list to update 849 * @id: CCID number to track 850 * @is_local: whether TX CCID (1) or RX CCID (0) is meant 851 * This function needs to be called after registering all other features. 852 */ 853 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local) 854 { 855 const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local); 856 int i, rc = (table == NULL); 857 858 for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++) 859 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP) 860 rc = __feat_register_sp(fn, table[i].dependent_feat, 861 table[i].is_local, 862 table[i].is_mandatory, 863 &table[i].val, 1); 864 else 865 rc = __feat_register_nn(fn, table[i].dependent_feat, 866 table[i].is_mandatory, 867 table[i].val); 868 return rc; 869 } 870 871 /** 872 * dccp_feat_finalise_settings - Finalise settings before starting negotiation 873 * @dp: client or listening socket (settings will be inherited) 874 * This is called after all registrations (socket initialisation, sysctls, and 875 * sockopt calls), and before sending the first packet containing Change options 876 * (ie. client-Request or server-Response), to ensure internal consistency. 877 */ 878 int dccp_feat_finalise_settings(struct dccp_sock *dp) 879 { 880 struct list_head *fn = &dp->dccps_featneg; 881 struct dccp_feat_entry *entry; 882 int i = 2, ccids[2] = { -1, -1 }; 883 884 /* 885 * Propagating CCIDs: 886 * 1) not useful to propagate CCID settings if this host advertises more 887 * than one CCID: the choice of CCID may still change - if this is 888 * the client, or if this is the server and the client sends 889 * singleton CCID values. 890 * 2) since is that propagate_ccid changes the list, we defer changing 891 * the sorted list until after the traversal. 892 */ 893 list_for_each_entry(entry, fn, node) 894 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1) 895 ccids[entry->is_local] = entry->val.sp.vec[0]; 896 while (i--) 897 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i)) 898 return -1; 899 dccp_feat_print_fnlist(fn); 900 return 0; 901 } 902 903 /** 904 * dccp_feat_server_ccid_dependencies - Resolve CCID-dependent features 905 * It is the server which resolves the dependencies once the CCID has been 906 * fully negotiated. If no CCID has been negotiated, it uses the default CCID. 907 */ 908 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq) 909 { 910 struct list_head *fn = &dreq->dreq_featneg; 911 struct dccp_feat_entry *entry; 912 u8 is_local, ccid; 913 914 for (is_local = 0; is_local <= 1; is_local++) { 915 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local); 916 917 if (entry != NULL && !entry->empty_confirm) 918 ccid = entry->val.sp.vec[0]; 919 else 920 ccid = dccp_feat_default_value(DCCPF_CCID); 921 922 if (dccp_feat_propagate_ccid(fn, ccid, is_local)) 923 return -1; 924 } 925 return 0; 926 } 927 928 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */ 929 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen) 930 { 931 u8 c, s; 932 933 for (s = 0; s < slen; s++) 934 for (c = 0; c < clen; c++) 935 if (servlist[s] == clilist[c]) 936 return servlist[s]; 937 return -1; 938 } 939 940 /** 941 * dccp_feat_prefer - Move preferred entry to the start of array 942 * Reorder the @array_len elements in @array so that @preferred_value comes 943 * first. Returns >0 to indicate that @preferred_value does occur in @array. 944 */ 945 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len) 946 { 947 u8 i, does_occur = 0; 948 949 if (array != NULL) { 950 for (i = 0; i < array_len; i++) 951 if (array[i] == preferred_value) { 952 array[i] = array[0]; 953 does_occur++; 954 } 955 if (does_occur) 956 array[0] = preferred_value; 957 } 958 return does_occur; 959 } 960 961 /** 962 * dccp_feat_reconcile - Reconcile SP preference lists 963 * @fval: SP list to reconcile into 964 * @arr: received SP preference list 965 * @len: length of @arr in bytes 966 * @is_server: whether this side is the server (and @fv is the server's list) 967 * @reorder: whether to reorder the list in @fv after reconciling with @arr 968 * When successful, > 0 is returned and the reconciled list is in @fval. 969 * A value of 0 means that negotiation failed (no shared entry). 970 */ 971 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len, 972 bool is_server, bool reorder) 973 { 974 int rc; 975 976 if (!fv->sp.vec || !arr) { 977 DCCP_CRIT("NULL feature value or array"); 978 return 0; 979 } 980 981 if (is_server) 982 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len); 983 else 984 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len); 985 986 if (!reorder) 987 return rc; 988 if (rc < 0) 989 return 0; 990 991 /* 992 * Reorder list: used for activating features and in dccp_insert_fn_opt. 993 */ 994 return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len); 995 } 996 997 /** 998 * dccp_feat_change_recv - Process incoming ChangeL/R options 999 * @fn: feature-negotiation list to update 1000 * @is_mandatory: whether the Change was preceded by a Mandatory option 1001 * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R 1002 * @feat: one of %dccp_feature_numbers 1003 * @val: NN value or SP value/preference list 1004 * @len: length of @val in bytes 1005 * @server: whether this node is the server (1) or the client (0) 1006 */ 1007 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1008 u8 feat, u8 *val, u8 len, const bool server) 1009 { 1010 u8 defval, type = dccp_feat_type(feat); 1011 const bool local = (opt == DCCPO_CHANGE_R); 1012 struct dccp_feat_entry *entry; 1013 dccp_feat_val fval; 1014 1015 if (len == 0 || type == FEAT_UNKNOWN) /* 6.1 and 6.6.8 */ 1016 goto unknown_feature_or_value; 1017 1018 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1019 1020 /* 1021 * Negotiation of NN features: Change R is invalid, so there is no 1022 * simultaneous negotiation; hence we do not look up in the list. 1023 */ 1024 if (type == FEAT_NN) { 1025 if (local || len > sizeof(fval.nn)) 1026 goto unknown_feature_or_value; 1027 1028 /* 6.3.2: "The feature remote MUST accept any valid value..." */ 1029 fval.nn = dccp_decode_value_var(val, len); 1030 if (!dccp_feat_is_valid_nn_val(feat, fval.nn)) 1031 goto unknown_feature_or_value; 1032 1033 return dccp_feat_push_confirm(fn, feat, local, &fval); 1034 } 1035 1036 /* 1037 * Unidirectional/simultaneous negotiation of SP features (6.3.1) 1038 */ 1039 entry = dccp_feat_list_lookup(fn, feat, local); 1040 if (entry == NULL) { 1041 /* 1042 * No particular preferences have been registered. We deal with 1043 * this situation by assuming that all valid values are equally 1044 * acceptable, and apply the following checks: 1045 * - if the peer's list is a singleton, we accept a valid value; 1046 * - if we are the server, we first try to see if the peer (the 1047 * client) advertises the default value. If yes, we use it, 1048 * otherwise we accept the preferred value; 1049 * - else if we are the client, we use the first list element. 1050 */ 1051 if (dccp_feat_clone_sp_val(&fval, val, 1)) 1052 return DCCP_RESET_CODE_TOO_BUSY; 1053 1054 if (len > 1 && server) { 1055 defval = dccp_feat_default_value(feat); 1056 if (dccp_feat_preflist_match(&defval, 1, val, len) > -1) 1057 fval.sp.vec[0] = defval; 1058 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) { 1059 kfree(fval.sp.vec); 1060 goto unknown_feature_or_value; 1061 } 1062 1063 /* Treat unsupported CCIDs like invalid values */ 1064 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) { 1065 kfree(fval.sp.vec); 1066 goto not_valid_or_not_known; 1067 } 1068 1069 return dccp_feat_push_confirm(fn, feat, local, &fval); 1070 1071 } else if (entry->state == FEAT_UNSTABLE) { /* 6.6.2 */ 1072 return 0; 1073 } 1074 1075 if (dccp_feat_reconcile(&entry->val, val, len, server, true)) { 1076 entry->empty_confirm = 0; 1077 } else if (is_mandatory) { 1078 return DCCP_RESET_CODE_MANDATORY_ERROR; 1079 } else if (entry->state == FEAT_INITIALISING) { 1080 /* 1081 * Failed simultaneous negotiation (server only): try to `save' 1082 * the connection by checking whether entry contains the default 1083 * value for @feat. If yes, send an empty Confirm to signal that 1084 * the received Change was not understood - which implies using 1085 * the default value. 1086 * If this also fails, we use Reset as the last resort. 1087 */ 1088 WARN_ON(!server); 1089 defval = dccp_feat_default_value(feat); 1090 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true)) 1091 return DCCP_RESET_CODE_OPTION_ERROR; 1092 entry->empty_confirm = 1; 1093 } 1094 entry->needs_confirm = 1; 1095 entry->needs_mandatory = 0; 1096 entry->state = FEAT_STABLE; 1097 return 0; 1098 1099 unknown_feature_or_value: 1100 if (!is_mandatory) 1101 return dccp_push_empty_confirm(fn, feat, local); 1102 1103 not_valid_or_not_known: 1104 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1105 : DCCP_RESET_CODE_OPTION_ERROR; 1106 } 1107 1108 /** 1109 * dccp_feat_confirm_recv - Process received Confirm options 1110 * @fn: feature-negotiation list to update 1111 * @is_mandatory: whether @opt was preceded by a Mandatory option 1112 * @opt: %DCCPO_CONFIRM_L or %DCCPO_CONFIRM_R 1113 * @feat: one of %dccp_feature_numbers 1114 * @val: NN value or SP value/preference list 1115 * @len: length of @val in bytes 1116 * @server: whether this node is server (1) or client (0) 1117 */ 1118 static u8 dccp_feat_confirm_recv(struct list_head *fn, u8 is_mandatory, u8 opt, 1119 u8 feat, u8 *val, u8 len, const bool server) 1120 { 1121 u8 *plist, plen, type = dccp_feat_type(feat); 1122 const bool local = (opt == DCCPO_CONFIRM_R); 1123 struct dccp_feat_entry *entry = dccp_feat_list_lookup(fn, feat, local); 1124 1125 dccp_feat_print_opt(opt, feat, val, len, is_mandatory); 1126 1127 if (entry == NULL) { /* nothing queued: ignore or handle error */ 1128 if (is_mandatory && type == FEAT_UNKNOWN) 1129 return DCCP_RESET_CODE_MANDATORY_ERROR; 1130 1131 if (!local && type == FEAT_NN) /* 6.3.2 */ 1132 goto confirmation_failed; 1133 return 0; 1134 } 1135 1136 if (entry->state != FEAT_CHANGING) /* 6.6.2 */ 1137 return 0; 1138 1139 if (len == 0) { 1140 if (dccp_feat_must_be_understood(feat)) /* 6.6.7 */ 1141 goto confirmation_failed; 1142 /* 1143 * Empty Confirm during connection setup: this means reverting 1144 * to the `old' value, which in this case is the default. Since 1145 * we handle default values automatically when no other values 1146 * have been set, we revert to the old value by removing this 1147 * entry from the list. 1148 */ 1149 dccp_feat_list_pop(entry); 1150 return 0; 1151 } 1152 1153 if (type == FEAT_NN) { 1154 if (len > sizeof(entry->val.nn)) 1155 goto confirmation_failed; 1156 1157 if (entry->val.nn == dccp_decode_value_var(val, len)) 1158 goto confirmation_succeeded; 1159 1160 DCCP_WARN("Bogus Confirm for non-existing value\n"); 1161 goto confirmation_failed; 1162 } 1163 1164 /* 1165 * Parsing SP Confirms: the first element of @val is the preferred 1166 * SP value which the peer confirms, the remainder depends on @len. 1167 * Note that only the confirmed value need to be a valid SP value. 1168 */ 1169 if (!dccp_feat_is_valid_sp_val(feat, *val)) 1170 goto confirmation_failed; 1171 1172 if (len == 1) { /* peer didn't supply a preference list */ 1173 plist = val; 1174 plen = len; 1175 } else { /* preferred value + preference list */ 1176 plist = val + 1; 1177 plen = len - 1; 1178 } 1179 1180 /* Check whether the peer got the reconciliation right (6.6.8) */ 1181 if (dccp_feat_reconcile(&entry->val, plist, plen, server, 0) != *val) { 1182 DCCP_WARN("Confirm selected the wrong value %u\n", *val); 1183 return DCCP_RESET_CODE_OPTION_ERROR; 1184 } 1185 entry->val.sp.vec[0] = *val; 1186 1187 confirmation_succeeded: 1188 entry->state = FEAT_STABLE; 1189 return 0; 1190 1191 confirmation_failed: 1192 DCCP_WARN("Confirmation failed\n"); 1193 return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR 1194 : DCCP_RESET_CODE_OPTION_ERROR; 1195 } 1196 1197 /** 1198 * dccp_feat_parse_options - Process Feature-Negotiation Options 1199 * @sk: for general use and used by the client during connection setup 1200 * @dreq: used by the server during connection setup 1201 * @mandatory: whether @opt was preceded by a Mandatory option 1202 * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R 1203 * @feat: one of %dccp_feature_numbers 1204 * @val: value contents of @opt 1205 * @len: length of @val in bytes 1206 * Returns 0 on success, a Reset code for ending the connection otherwise. 1207 */ 1208 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq, 1209 u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len) 1210 { 1211 struct dccp_sock *dp = dccp_sk(sk); 1212 struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg; 1213 bool server = false; 1214 1215 switch (sk->sk_state) { 1216 /* 1217 * Negotiation during connection setup 1218 */ 1219 case DCCP_LISTEN: 1220 server = true; /* fall through */ 1221 case DCCP_REQUESTING: 1222 switch (opt) { 1223 case DCCPO_CHANGE_L: 1224 case DCCPO_CHANGE_R: 1225 return dccp_feat_change_recv(fn, mandatory, opt, feat, 1226 val, len, server); 1227 case DCCPO_CONFIRM_R: 1228 case DCCPO_CONFIRM_L: 1229 return dccp_feat_confirm_recv(fn, mandatory, opt, feat, 1230 val, len, server); 1231 } 1232 } 1233 return 0; /* ignore FN options in all other states */ 1234 } 1235 1236 /** 1237 * dccp_feat_init - Seed feature negotiation with host-specific defaults 1238 * This initialises global defaults, depending on the value of the sysctls. 1239 * These can later be overridden by registering changes via setsockopt calls. 1240 * The last link in the chain is finalise_settings, to make sure that between 1241 * here and the start of actual feature negotiation no inconsistencies enter. 1242 * 1243 * All features not appearing below use either defaults or are otherwise 1244 * later adjusted through dccp_feat_finalise_settings(). 1245 */ 1246 int dccp_feat_init(struct sock *sk) 1247 { 1248 struct list_head *fn = &dccp_sk(sk)->dccps_featneg; 1249 u8 on = 1, off = 0; 1250 int rc; 1251 struct { 1252 u8 *val; 1253 u8 len; 1254 } tx, rx; 1255 1256 /* Non-negotiable (NN) features */ 1257 rc = __feat_register_nn(fn, DCCPF_SEQUENCE_WINDOW, 0, 1258 sysctl_dccp_sequence_window); 1259 if (rc) 1260 return rc; 1261 1262 /* Server-priority (SP) features */ 1263 1264 /* Advertise that short seqnos are not supported (7.6.1) */ 1265 rc = __feat_register_sp(fn, DCCPF_SHORT_SEQNOS, true, true, &off, 1); 1266 if (rc) 1267 return rc; 1268 1269 /* RFC 4340 12.1: "If a DCCP is not ECN capable, ..." */ 1270 rc = __feat_register_sp(fn, DCCPF_ECN_INCAPABLE, true, true, &on, 1); 1271 if (rc) 1272 return rc; 1273 1274 /* 1275 * We advertise the available list of CCIDs and reorder according to 1276 * preferences, to avoid failure resulting from negotiating different 1277 * singleton values (which always leads to failure). 1278 * These settings can still (later) be overridden via sockopts. 1279 */ 1280 if (ccid_get_builtin_ccids(&tx.val, &tx.len) || 1281 ccid_get_builtin_ccids(&rx.val, &rx.len)) 1282 return -ENOBUFS; 1283 1284 if (!dccp_feat_prefer(sysctl_dccp_tx_ccid, tx.val, tx.len) || 1285 !dccp_feat_prefer(sysctl_dccp_rx_ccid, rx.val, rx.len)) 1286 goto free_ccid_lists; 1287 1288 rc = __feat_register_sp(fn, DCCPF_CCID, true, false, tx.val, tx.len); 1289 if (rc) 1290 goto free_ccid_lists; 1291 1292 rc = __feat_register_sp(fn, DCCPF_CCID, false, false, rx.val, rx.len); 1293 1294 free_ccid_lists: 1295 kfree(tx.val); 1296 kfree(rx.val); 1297 return rc; 1298 } 1299 1300 int dccp_feat_activate_values(struct sock *sk, struct list_head *fn_list) 1301 { 1302 struct dccp_sock *dp = dccp_sk(sk); 1303 struct dccp_feat_entry *cur, *next; 1304 int idx; 1305 dccp_feat_val *fvals[DCCP_FEAT_SUPPORTED_MAX][2] = { 1306 [0 ... DCCP_FEAT_SUPPORTED_MAX-1] = { NULL, NULL } 1307 }; 1308 1309 list_for_each_entry(cur, fn_list, node) { 1310 /* 1311 * An empty Confirm means that either an unknown feature type 1312 * or an invalid value was present. In the first case there is 1313 * nothing to activate, in the other the default value is used. 1314 */ 1315 if (cur->empty_confirm) 1316 continue; 1317 1318 idx = dccp_feat_index(cur->feat_num); 1319 if (idx < 0) { 1320 DCCP_BUG("Unknown feature %u", cur->feat_num); 1321 goto activation_failed; 1322 } 1323 if (cur->state != FEAT_STABLE) { 1324 DCCP_CRIT("Negotiation of %s %s failed in state %s", 1325 cur->is_local ? "local" : "remote", 1326 dccp_feat_fname(cur->feat_num), 1327 dccp_feat_sname[cur->state]); 1328 goto activation_failed; 1329 } 1330 fvals[idx][cur->is_local] = &cur->val; 1331 } 1332 1333 /* 1334 * Activate in decreasing order of index, so that the CCIDs are always 1335 * activated as the last feature. This avoids the case where a CCID 1336 * relies on the initialisation of one or more features that it depends 1337 * on (e.g. Send NDP Count, Send Ack Vector, and Ack Ratio features). 1338 */ 1339 for (idx = DCCP_FEAT_SUPPORTED_MAX; --idx >= 0;) 1340 if (__dccp_feat_activate(sk, idx, 0, fvals[idx][0]) || 1341 __dccp_feat_activate(sk, idx, 1, fvals[idx][1])) { 1342 DCCP_CRIT("Could not activate %d", idx); 1343 goto activation_failed; 1344 } 1345 1346 /* Clean up Change options which have been confirmed already */ 1347 list_for_each_entry_safe(cur, next, fn_list, node) 1348 if (!cur->needs_confirm) 1349 dccp_feat_list_pop(cur); 1350 1351 dccp_pr_debug("Activation OK\n"); 1352 return 0; 1353 1354 activation_failed: 1355 /* 1356 * We clean up everything that may have been allocated, since 1357 * it is difficult to track at which stage negotiation failed. 1358 * This is ok, since all allocation functions below are robust 1359 * against NULL arguments. 1360 */ 1361 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk); 1362 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk); 1363 dp->dccps_hc_rx_ccid = dp->dccps_hc_tx_ccid = NULL; 1364 dccp_ackvec_free(dp->dccps_hc_rx_ackvec); 1365 dp->dccps_hc_rx_ackvec = NULL; 1366 return -1; 1367 } 1368