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   1 /*
   2  *  net/dccp/feat.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
   6  *
   7  *  ASSUMPTIONS
   8  *  -----------
   9  *  o Feature negotiation is coordinated with connection setup (as in TCP), wild
  10  *    changes of parameters of an established connection are not supported.
  11  *  o All currently known SP features have 1-byte quantities. If in the future
  12  *    extensions of RFCs 4340..42 define features with item lengths larger than
  13  *    one byte, a feature-specific extension of the code will be required.
  14  *
  15  *  This program is free software; you can redistribute it and/or
  16  *  modify it under the terms of the GNU General Public License
  17  *  as published by the Free Software Foundation; either version
  18  *  2 of the License, or (at your option) any later version.
  19  */
  20
  21 #include <linux/module.h>
  22
  23 #include "ccid.h"
  24 #include "feat.h"
  25
  26 #define DCCP_FEAT_SP_NOAGREE (-123)
  27
  28 static const struct {
  29         u8                      feat_num;               /* DCCPF_xxx */
  30         enum dccp_feat_type     rxtx;                   /* RX or TX  */
  31         enum dccp_feat_type     reconciliation;         /* SP or NN  */
  32         u8                      default_value;          /* as in 6.4 */
  33 /*
  34  *    Lookup table for location and type of features (from RFC 4340/4342)
  35  *  +--------------------------+----+-----+----+----+---------+-----------+
  36  *  | Feature                  | Location | Reconc. | Initial |  Section  |
  37  *  |                          | RX | TX  | SP | NN |  Value  | Reference |
  38  *  +--------------------------+----+-----+----+----+---------+-----------+
  39  *  | DCCPF_CCID               |    |  X  | X  |    |   2     | 10        |
  40  *  | DCCPF_SHORT_SEQNOS       |    |  X  | X  |    |   0     |  7.6.1    |
  41  *  | DCCPF_SEQUENCE_WINDOW    |    |  X  |    | X  | 100     |  7.5.2    |
  42  *  | DCCPF_ECN_INCAPABLE      | X  |     | X  |    |   0     | 12.1      |
  43  *  | DCCPF_ACK_RATIO          |    |  X  |    | X  |   2     | 11.3      |
  44  *  | DCCPF_SEND_ACK_VECTOR    | X  |     | X  |    |   0     | 11.5      |
  45  *  | DCCPF_SEND_NDP_COUNT     |    |  X  | X  |    |   0     |  7.7.2    |
  46  *  | DCCPF_MIN_CSUM_COVER     | X  |     | X  |    |   0     |  9.2.1    |
  47  *  | DCCPF_DATA_CHECKSUM      | X  |     | X  |    |   0     |  9.3.1    |
  48  *  | DCCPF_SEND_LEV_RATE      | X  |     | X  |    |   0     | 4342/8.4  |
  49  *  +--------------------------+----+-----+----+----+---------+-----------+
  50  */
  51 } dccp_feat_table[] = {
  52         { DCCPF_CCID,            FEAT_AT_TX, FEAT_SP, 2 },
  53         { DCCPF_SHORT_SEQNOS,    FEAT_AT_TX, FEAT_SP, 0 },
  54         { DCCPF_SEQUENCE_WINDOW, FEAT_AT_TX, FEAT_NN, 100 },
  55         { DCCPF_ECN_INCAPABLE,   FEAT_AT_RX, FEAT_SP, 0 },
  56         { DCCPF_ACK_RATIO,       FEAT_AT_TX, FEAT_NN, 2 },
  57         { DCCPF_SEND_ACK_VECTOR, FEAT_AT_RX, FEAT_SP, 0 },
  58         { DCCPF_SEND_NDP_COUNT,  FEAT_AT_TX, FEAT_SP, 0 },
  59         { DCCPF_MIN_CSUM_COVER,  FEAT_AT_RX, FEAT_SP, 0 },
  60         { DCCPF_DATA_CHECKSUM,   FEAT_AT_RX, FEAT_SP, 0 },
  61         { DCCPF_SEND_LEV_RATE,   FEAT_AT_RX, FEAT_SP, 0 },
  62 };
  63 #define DCCP_FEAT_SUPPORTED_MAX         ARRAY_SIZE(dccp_feat_table)
  64
  65 /**
  66  * dccp_feat_index  -  Hash function to map feature number into array position
  67  * Returns consecutive array index or -1 if the feature is not understood.
  68  */
  69 static int dccp_feat_index(u8 feat_num)
  70 {
  71         /* The first 9 entries are occupied by the types from RFC 4340, 6.4 */
  72         if (feat_num > DCCPF_RESERVED && feat_num <= DCCPF_DATA_CHECKSUM)
  73                 return feat_num - 1;
  74
  75         /*
  76          * Other features: add cases for new feature types here after adding
  77          * them to the above table.
  78          */
  79         switch (feat_num) {
  80         case DCCPF_SEND_LEV_RATE:
  81                         return DCCP_FEAT_SUPPORTED_MAX - 1;
  82         }
  83         return -1;
  84 }
  85
  86 static u8 dccp_feat_type(u8 feat_num)
  87 {
  88         int idx = dccp_feat_index(feat_num);
  89
  90         if (idx < 0)
  91                 return FEAT_UNKNOWN;
  92         return dccp_feat_table[idx].reconciliation;
  93 }
  94
  95 static int dccp_feat_default_value(u8 feat_num)
  96 {
  97         int idx = dccp_feat_index(feat_num);
  98
  99         return idx < 0 ? : dccp_feat_table[idx].default_value;
 100 }
 101
 102 /* copy constructor, fval must not already contain allocated memory */
 103 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
 104 {
 105         fval->sp.len = len;
 106         if (fval->sp.len > 0) {
 107                 fval->sp.vec = kmemdup(val, len, gfp_any());
 108                 if (fval->sp.vec == NULL) {
 109                         fval->sp.len = 0;
 110                         return -ENOBUFS;
 111                 }
 112         }
 113         return 0;
 114 }
 115
 116 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
 117 {
 118         if (unlikely(val == NULL))
 119                 return;
 120         if (dccp_feat_type(feat_num) == FEAT_SP)
 121                 kfree(val->sp.vec);
 122         memset(val, 0, sizeof(*val));
 123 }
 124
 125 static struct dccp_feat_entry *
 126               dccp_feat_clone_entry(struct dccp_feat_entry const *original)
 127 {
 128         struct dccp_feat_entry *new;
 129         u8 type = dccp_feat_type(original->feat_num);
 130
 131         if (type == FEAT_UNKNOWN)
 132                 return NULL;
 133
 134         new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
 135         if (new == NULL)
 136                 return NULL;
 137
 138         if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
 139                                                       original->val.sp.vec,
 140                                                       original->val.sp.len)) {
 141                 kfree(new);
 142                 return NULL;
 143         }
 144         return new;
 145 }
 146
 147 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
 148 {
 149         if (entry != NULL) {
 150                 dccp_feat_val_destructor(entry->feat_num, &entry->val);
 151                 kfree(entry);
 152         }
 153 }
 154
 155 /*
 156  * List management functions
 157  *
 158  * Feature negotiation lists rely on and maintain the following invariants:
 159  * - each feat_num in the list is known, i.e. we know its type and default value
 160  * - each feat_num/is_local combination is unique (old entries are overwritten)
 161  * - SP values are always freshly allocated
 162  * - list is sorted in increasing order of feature number (faster lookup)
 163  */
 164 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
 165                                                      u8 feat_num, bool is_local)
 166 {
 167         struct dccp_feat_entry *entry;
 168
 169         list_for_each_entry(entry, fn_list, node)
 170                 if (entry->feat_num == feat_num && entry->is_local == is_local)
 171                         return entry;
 172                 else if (entry->feat_num > feat_num)
 173                         break;
 174         return NULL;
 175 }
 176
 177 /**
 178  * dccp_feat_entry_new  -  Central list update routine (called by all others)
 179  * @head:  list to add to
 180  * @feat:  feature number
 181  * @local: whether the local (1) or remote feature with number @feat is meant
 182  * This is the only constructor and serves to ensure the above invariants.
 183  */
 184 static struct dccp_feat_entry *
 185               dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
 186 {
 187         struct dccp_feat_entry *entry;
 188
 189         list_for_each_entry(entry, head, node)
 190                 if (entry->feat_num == feat && entry->is_local == local) {
 191                         dccp_feat_val_destructor(entry->feat_num, &entry->val);
 192                         return entry;
 193                 } else if (entry->feat_num > feat) {
 194                         head = &entry->node;
 195                         break;
 196                 }
 197
 198         entry = kmalloc(sizeof(*entry), gfp_any());
 199         if (entry != NULL) {
 200                 entry->feat_num = feat;
 201                 entry->is_local = local;
 202                 list_add_tail(&entry->node, head);
 203         }
 204         return entry;
 205 }
 206
 207 /**
 208  * dccp_feat_push_change  -  Add/overwrite a Change option in the list
 209  * @fn_list: feature-negotiation list to update
 210  * @feat: one of %dccp_feature_numbers
 211  * @local: whether local (1) or remote (0) @feat_num is meant
 212  * @needs_mandatory: whether to use Mandatory feature negotiation options
 213  * @fval: pointer to NN/SP value to be inserted (will be copied)
 214  */
 215 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
 216                                  u8 mandatory, dccp_feat_val *fval)
 217 {
 218         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 219
 220         if (new == NULL)
 221                 return -ENOMEM;
 222
 223         new->feat_num        = feat;
 224         new->is_local        = local;
 225         new->state           = FEAT_INITIALISING;
 226         new->needs_confirm   = 0;
 227         new->empty_confirm   = 0;
 228         new->val             = *fval;
 229         new->needs_mandatory = mandatory;
 230
 231         return 0;
 232 }
 233
 234 /**
 235  * dccp_feat_push_confirm  -  Add a Confirm entry to the FN list
 236  * @fn_list: feature-negotiation list to add to
 237  * @feat: one of %dccp_feature_numbers
 238  * @local: whether local (1) or remote (0) @feat_num is being confirmed
 239  * @fval: pointer to NN/SP value to be inserted or NULL
 240  * Returns 0 on success, a Reset code for further processing otherwise.
 241  */
 242 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
 243                                   dccp_feat_val *fval)
 244 {
 245         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 246
 247         if (new == NULL)
 248                 return DCCP_RESET_CODE_TOO_BUSY;
 249
 250         new->feat_num        = feat;
 251         new->is_local        = local;
 252         new->state           = FEAT_STABLE;     /* transition in 6.6.2 */
 253         new->needs_confirm   = 1;
 254         new->empty_confirm   = (fval == NULL);
 255         new->val.nn          = 0;               /* zeroes the whole structure */
 256         if (!new->empty_confirm)
 257                 new->val     = *fval;
 258         new->needs_mandatory = 0;
 259
 260         return 0;
 261 }
 262
 263 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
 264 {
 265         return dccp_feat_push_confirm(fn_list, feat, local, NULL);
 266 }
 267
 268 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
 269 {
 270         list_del(&entry->node);
 271         dccp_feat_entry_destructor(entry);
 272 }
 273
 274 void dccp_feat_list_purge(struct list_head *fn_list)
 275 {
 276         struct dccp_feat_entry *entry, *next;
 277
 278         list_for_each_entry_safe(entry, next, fn_list, node)
 279                 dccp_feat_entry_destructor(entry);
 280         INIT_LIST_HEAD(fn_list);
 281 }
 282 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
 283
 284 /* generate @to as full clone of @from - @to must not contain any nodes */
 285 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
 286 {
 287         struct dccp_feat_entry *entry, *new;
 288
 289         INIT_LIST_HEAD(to);
 290         list_for_each_entry(entry, from, node) {
 291                 new = dccp_feat_clone_entry(entry);
 292                 if (new == NULL)
 293                         goto cloning_failed;
 294                 list_add_tail(&new->node, to);
 295         }
 296         return 0;
 297
 298 cloning_failed:
 299         dccp_feat_list_purge(to);
 300         return -ENOMEM;
 301 }
 302
 303 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
 304 {
 305         switch (feat_num) {
 306         case DCCPF_ACK_RATIO:
 307                 return val <= DCCPF_ACK_RATIO_MAX;
 308         case DCCPF_SEQUENCE_WINDOW:
 309                 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
 310         }
 311         return 0;       /* feature unknown - so we can't tell */
 312 }
 313
 314 /* check that SP values are within the ranges defined in RFC 4340 */
 315 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
 316 {
 317         switch (feat_num) {
 318         case DCCPF_CCID:
 319                 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
 320         /* Type-check Boolean feature values: */
 321         case DCCPF_SHORT_SEQNOS:
 322         case DCCPF_ECN_INCAPABLE:
 323         case DCCPF_SEND_ACK_VECTOR:
 324         case DCCPF_SEND_NDP_COUNT:
 325         case DCCPF_DATA_CHECKSUM:
 326         case DCCPF_SEND_LEV_RATE:
 327                 return val < 2;
 328         case DCCPF_MIN_CSUM_COVER:
 329                 return val < 16;
 330         }
 331         return 0;                       /* feature unknown */
 332 }
 333
 334 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
 335 {
 336         if (sp_list == NULL || sp_len < 1)
 337                 return 0;
 338         while (sp_len--)
 339                 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
 340                         return 0;
 341         return 1;
 342 }
 343
 344 /**
 345  * __feat_register_nn  -  Register new NN value on socket
 346  * @fn: feature-negotiation list to register with
 347  * @feat: an NN feature from %dccp_feature_numbers
 348  * @mandatory: use Mandatory option if 1
 349  * @nn_val: value to register (restricted to 4 bytes)
 350  * Note that NN features are local by definition (RFC 4340, 6.3.2).
 351  */
 352 static int __feat_register_nn(struct list_head *fn, u8 feat,
 353                               u8 mandatory, u64 nn_val)
 354 {
 355         dccp_feat_val fval = { .nn = nn_val };
 356
 357         if (dccp_feat_type(feat) != FEAT_NN ||
 358             !dccp_feat_is_valid_nn_val(feat, nn_val))
 359                 return -EINVAL;
 360
 361         /* Don't bother with default values, they will be activated anyway. */
 362         if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
 363                 return 0;
 364
 365         return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
 366 }
 367
 368 /**
 369  * __feat_register_sp  -  Register new SP value/list on socket
 370  * @fn: feature-negotiation list to register with
 371  * @feat: an SP feature from %dccp_feature_numbers
 372  * @is_local: whether the local (1) or the remote (0) @feat is meant
 373  * @mandatory: use Mandatory option if 1
 374  * @sp_val: SP value followed by optional preference list
 375  * @sp_len: length of @sp_val in bytes
 376  */
 377 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
 378                               u8 mandatory, u8 const *sp_val, u8 sp_len)
 379 {
 380         dccp_feat_val fval;
 381
 382         if (dccp_feat_type(feat) != FEAT_SP ||
 383             !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
 384                 return -EINVAL;
 385
 386         /* Avoid negotiating alien CCIDs by only advertising supported ones */
 387         if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
 388                 return -EOPNOTSUPP;
 389
 390         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
 391                 return -ENOMEM;
 392
 393         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
 394 }
 395
 396 int dccp_feat_change(struct dccp_minisock *dmsk, u8 type, u8 feature,
 397                      u8 *val, u8 len, gfp_t gfp)
 398 {
 399         struct dccp_opt_pend *opt;
 400
 401         dccp_feat_debug(type, feature, *val);
 402
 403         if (len > 3) {
 404                 DCCP_WARN("invalid length %d\n", len);
 405                 return -EINVAL;
 406         }
 407         /* XXX add further sanity checks */
 408
 409         /* check if that feature is already being negotiated */
 410         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 411                 /* ok we found a negotiation for this option already */
 412                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
 413                         dccp_pr_debug("Replacing old\n");
 414                         /* replace */
 415                         BUG_ON(opt->dccpop_val == NULL);
 416                         kfree(opt->dccpop_val);
 417                         opt->dccpop_val  = val;
 418                         opt->dccpop_len  = len;
 419                         opt->dccpop_conf = 0;
 420                         return 0;
 421                 }
 422         }
 423
 424         /* negotiation for a new feature */
 425         opt = kmalloc(sizeof(*opt), gfp);
 426         if (opt == NULL)
 427                 return -ENOMEM;
 428
 429         opt->dccpop_type = type;
 430         opt->dccpop_feat = feature;
 431         opt->dccpop_len  = len;
 432         opt->dccpop_val  = val;
 433         opt->dccpop_conf = 0;
 434         opt->dccpop_sc   = NULL;
 435
 436         BUG_ON(opt->dccpop_val == NULL);
 437
 438         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_pending);
 439         return 0;
 440 }
 441
 442 EXPORT_SYMBOL_GPL(dccp_feat_change);
 443
 444 /*
 445  *      Tracking features whose value depend on the choice of CCID
 446  *
 447  * This is designed with an extension in mind so that a list walk could be done
 448  * before activating any features. However, the existing framework was found to
 449  * work satisfactorily up until now, the automatic verification is left open.
 450  * When adding new CCIDs, add a corresponding dependency table here.
 451  */
 452 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
 453 {
 454         static const struct ccid_dependency ccid2_dependencies[2][2] = {
 455                 /*
 456                  * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
 457                  * feature and Send Ack Vector is an RX feature, `is_local'
 458                  * needs to be reversed.
 459                  */
 460                 {       /* Dependencies of the receiver-side (remote) CCID2 */
 461                         {
 462                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 463                                 .is_local       = true,
 464                                 .is_mandatory   = true,
 465                                 .val            = 1
 466                         },
 467                         { 0, 0, 0, 0 }
 468                 },
 469                 {       /* Dependencies of the sender-side (local) CCID2 */
 470                         {
 471                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 472                                 .is_local       = false,
 473                                 .is_mandatory   = true,
 474                                 .val            = 1
 475                         },
 476                         { 0, 0, 0, 0 }
 477                 }
 478         };
 479         static const struct ccid_dependency ccid3_dependencies[2][5] = {
 480                 {       /*
 481                          * Dependencies of the receiver-side CCID3
 482                          */
 483                         {       /* locally disable Ack Vectors */
 484                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 485                                 .is_local       = true,
 486                                 .is_mandatory   = false,
 487                                 .val            = 0
 488                         },
 489                         {       /* see below why Send Loss Event Rate is on */
 490                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 491                                 .is_local       = true,
 492                                 .is_mandatory   = true,
 493                                 .val            = 1
 494                         },
 495                         {       /* NDP Count is needed as per RFC 4342, 6.1.1 */
 496                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 497                                 .is_local       = false,
 498                                 .is_mandatory   = true,
 499                                 .val            = 1
 500                         },
 501                         { 0, 0, 0, 0 },
 502                 },
 503                 {       /*
 504                          * CCID3 at the TX side: we request that the HC-receiver
 505                          * will not send Ack Vectors (they will be ignored, so
 506                          * Mandatory is not set); we enable Send Loss Event Rate
 507                          * (Mandatory since the implementation does not support
 508                          * the Loss Intervals option of RFC 4342, 8.6).
 509                          * The last two options are for peer's information only.
 510                         */
 511                         {
 512                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 513                                 .is_local       = false,
 514                                 .is_mandatory   = false,
 515                                 .val            = 0
 516                         },
 517                         {
 518                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 519                                 .is_local       = false,
 520                                 .is_mandatory   = true,
 521                                 .val            = 1
 522                         },
 523                         {       /* this CCID does not support Ack Ratio */
 524                                 .dependent_feat = DCCPF_ACK_RATIO,
 525                                 .is_local       = true,
 526                                 .is_mandatory   = false,
 527                                 .val            = 0
 528                         },
 529                         {       /* tell receiver we are sending NDP counts */
 530                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 531                                 .is_local       = true,
 532                                 .is_mandatory   = false,
 533                                 .val            = 1
 534                         },
 535                         { 0, 0, 0, 0 }
 536                 }
 537         };
 538         switch (ccid) {
 539         case DCCPC_CCID2:
 540                 return ccid2_dependencies[is_local];
 541         case DCCPC_CCID3:
 542                 return ccid3_dependencies[is_local];
 543         default:
 544                 return NULL;
 545         }
 546 }
 547
 548 /**
 549  * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
 550  * @fn: feature-negotiation list to update
 551  * @id: CCID number to track
 552  * @is_local: whether TX CCID (1) or RX CCID (0) is meant
 553  * This function needs to be called after registering all other features.
 554  */
 555 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
 556 {
 557         const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
 558         int i, rc = (table == NULL);
 559
 560         for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
 561                 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
 562                         rc = __feat_register_sp(fn, table[i].dependent_feat,
 563                                                     table[i].is_local,
 564                                                     table[i].is_mandatory,
 565                                                     &table[i].val, 1);
 566                 else
 567                         rc = __feat_register_nn(fn, table[i].dependent_feat,
 568                                                     table[i].is_mandatory,
 569                                                     table[i].val);
 570         return rc;
 571 }
 572
 573 /**
 574  * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
 575  * @dp: client or listening socket (settings will be inherited)
 576  * This is called after all registrations (socket initialisation, sysctls, and
 577  * sockopt calls), and before sending the first packet containing Change options
 578  * (ie. client-Request or server-Response), to ensure internal consistency.
 579  */
 580 int dccp_feat_finalise_settings(struct dccp_sock *dp)
 581 {
 582         struct list_head *fn = &dp->dccps_featneg;
 583         struct dccp_feat_entry *entry;
 584         int i = 2, ccids[2] = { -1, -1 };
 585
 586         /*
 587          * Propagating CCIDs:
 588          * 1) not useful to propagate CCID settings if this host advertises more
 589          *    than one CCID: the choice of CCID  may still change - if this is
 590          *    the client, or if this is the server and the client sends
 591          *    singleton CCID values.
 592          * 2) since is that propagate_ccid changes the list, we defer changing
 593          *    the sorted list until after the traversal.
 594          */
 595         list_for_each_entry(entry, fn, node)
 596                 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
 597                         ccids[entry->is_local] = entry->val.sp.vec[0];
 598         while (i--)
 599                 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
 600                         return -1;
 601         return 0;
 602 }
 603
 604 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 605 {
 606         struct dccp_sock *dp = dccp_sk(sk);
 607         struct dccp_minisock *dmsk = dccp_msk(sk);
 608         /* figure out if we are changing our CCID or the peer's */
 609         const int rx = type == DCCPO_CHANGE_R;
 610         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 611         struct ccid *new_ccid;
 612
 613         /* Check if nothing is being changed. */
 614         if (ccid_nr == new_ccid_nr)
 615                 return 0;
 616
 617         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 618         if (new_ccid == NULL)
 619                 return -ENOMEM;
 620
 621         if (rx) {
 622                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 623                 dp->dccps_hc_rx_ccid = new_ccid;
 624                 dmsk->dccpms_rx_ccid = new_ccid_nr;
 625         } else {
 626                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 627                 dp->dccps_hc_tx_ccid = new_ccid;
 628                 dmsk->dccpms_tx_ccid = new_ccid_nr;
 629         }
 630
 631         return 0;
 632 }
 633
 634 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 635 {
 636         dccp_feat_debug(type, feat, val);
 637
 638         switch (feat) {
 639         case DCCPF_CCID:
 640                 return dccp_feat_update_ccid(sk, type, val);
 641         default:
 642                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 643                               dccp_feat_typename(type), feat);
 644                 break;
 645         }
 646         return 0;
 647 }
 648
 649 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 650                                u8 *rpref, u8 rlen)
 651 {
 652         struct dccp_sock *dp = dccp_sk(sk);
 653         u8 *spref, slen, *res = NULL;
 654         int i, j, rc, agree = 1;
 655
 656         BUG_ON(rpref == NULL);
 657
 658         /* check if we are the black sheep */
 659         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 660                 spref = rpref;
 661                 slen  = rlen;
 662                 rpref = opt->dccpop_val;
 663                 rlen  = opt->dccpop_len;
 664         } else {
 665                 spref = opt->dccpop_val;
 666                 slen  = opt->dccpop_len;
 667         }
 668         /*
 669          * Now we have server preference list in spref and client preference in
 670          * rpref
 671          */
 672         BUG_ON(spref == NULL);
 673         BUG_ON(rpref == NULL);
 674
 675         /* FIXME sanity check vals */
 676
 677         /* Are values in any order?  XXX Lame "algorithm" here */
 678         for (i = 0; i < slen; i++) {
 679                 for (j = 0; j < rlen; j++) {
 680                         if (spref[i] == rpref[j]) {
 681                                 res = &spref[i];
 682                                 break;
 683                         }
 684                 }
 685                 if (res)
 686                         break;
 687         }
 688
 689         /* we didn't agree on anything */
 690         if (res == NULL) {
 691                 /* confirm previous value */
 692                 switch (opt->dccpop_feat) {
 693                 case DCCPF_CCID:
 694                         /* XXX did i get this right? =P */
 695                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 696                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 697                         else
 698                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 699                         break;
 700
 701                 default:
 702                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 703                         /* XXX implement res */
 704                         return -EFAULT;
 705                 }
 706
 707                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 708                 agree = 0; /* this is used for mandatory options... */
 709         }
 710
 711         /* need to put result and our preference list */
 712         rlen = 1 + opt->dccpop_len;
 713         rpref = kmalloc(rlen, GFP_ATOMIC);
 714         if (rpref == NULL)
 715                 return -ENOMEM;
 716
 717         *rpref = *res;
 718         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 719
 720         /* put it in the "confirm queue" */
 721         if (opt->dccpop_sc == NULL) {
 722                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 723                 if (opt->dccpop_sc == NULL) {
 724                         kfree(rpref);
 725                         return -ENOMEM;
 726                 }
 727         } else {
 728                 /* recycle the confirm slot */
 729                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 730                 kfree(opt->dccpop_sc->dccpoc_val);
 731                 dccp_pr_debug("recycling confirm slot\n");
 732         }
 733         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 734
 735         opt->dccpop_sc->dccpoc_val = rpref;
 736         opt->dccpop_sc->dccpoc_len = rlen;
 737
 738         /* update the option on our side [we are about to send the confirm] */
 739         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 740         if (rc) {
 741                 kfree(opt->dccpop_sc->dccpoc_val);
 742                 kfree(opt->dccpop_sc);
 743                 opt->dccpop_sc = NULL;
 744                 return rc;
 745         }
 746
 747         dccp_pr_debug("Will confirm %d\n", *rpref);
 748
 749         /* say we want to change to X but we just got a confirm X, suppress our
 750          * change
 751          */
 752         if (!opt->dccpop_conf) {
 753                 if (*opt->dccpop_val == *res)
 754                         opt->dccpop_conf = 1;
 755                 dccp_pr_debug("won't ask for change of same feature\n");
 756         }
 757
 758         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 759 }
 760
 761 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 762 {
 763         struct dccp_minisock *dmsk = dccp_msk(sk);
 764         struct dccp_opt_pend *opt;
 765         int rc = 1;
 766         u8 t;
 767
 768         /*
 769          * We received a CHANGE.  We gotta match it against our own preference
 770          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 771          * to compare our CHANGE_L list.
 772          */
 773         if (type == DCCPO_CHANGE_L)
 774                 t = DCCPO_CHANGE_R;
 775         else
 776                 t = DCCPO_CHANGE_L;
 777
 778         /* find our preference list for this feature */
 779         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 780                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 781                         continue;
 782
 783                 /* find the winner from the two preference lists */
 784                 rc = dccp_feat_reconcile(sk, opt, val, len);
 785                 break;
 786         }
 787
 788         /* We didn't deal with the change.  This can happen if we have no
 789          * preference list for the feature.  In fact, it just shouldn't
 790          * happen---if we understand a feature, we should have a preference list
 791          * with at least the default value.
 792          */
 793         BUG_ON(rc == 1);
 794
 795         return rc;
 796 }
 797
 798 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 799 {
 800         struct dccp_opt_pend *opt;
 801         struct dccp_minisock *dmsk = dccp_msk(sk);
 802         u8 *copy;
 803         int rc;
 804
 805         /* NN features must be Change L (sec. 6.3.2) */
 806         if (type != DCCPO_CHANGE_L) {
 807                 dccp_pr_debug("received %s for NN feature %d\n",
 808                                 dccp_feat_typename(type), feature);
 809                 return -EFAULT;
 810         }
 811
 812         /* XXX sanity check opt val */
 813
 814         /* copy option so we can confirm it */
 815         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 816         if (opt == NULL)
 817                 return -ENOMEM;
 818
 819         copy = kmemdup(val, len, GFP_ATOMIC);
 820         if (copy == NULL) {
 821                 kfree(opt);
 822                 return -ENOMEM;
 823         }
 824
 825         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 826         opt->dccpop_feat = feature;
 827         opt->dccpop_val  = copy;
 828         opt->dccpop_len  = len;
 829
 830         /* change feature */
 831         rc = dccp_feat_update(sk, type, feature, *val);
 832         if (rc) {
 833                 kfree(opt->dccpop_val);
 834                 kfree(opt);
 835                 return rc;
 836         }
 837
 838         dccp_feat_debug(type, feature, *copy);
 839
 840         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 841
 842         return 0;
 843 }
 844
 845 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 846                                     u8 type, u8 feature)
 847 {
 848         /* XXX check if other confirms for that are queued and recycle slot */
 849         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 850
 851         if (opt == NULL) {
 852                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 853                  * after all =P
 854                  */
 855                 return;
 856         }
 857
 858         switch (type) {
 859         case DCCPO_CHANGE_L:
 860                 opt->dccpop_type = DCCPO_CONFIRM_R;
 861                 break;
 862         case DCCPO_CHANGE_R:
 863                 opt->dccpop_type = DCCPO_CONFIRM_L;
 864                 break;
 865         default:
 866                 DCCP_WARN("invalid type %d\n", type);
 867                 kfree(opt);
 868                 return;
 869         }
 870         opt->dccpop_feat = feature;
 871         opt->dccpop_val  = NULL;
 872         opt->dccpop_len  = 0;
 873
 874         /* change feature */
 875         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 876
 877         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 878 }
 879
 880 static void dccp_feat_flush_confirm(struct sock *sk)
 881 {
 882         struct dccp_minisock *dmsk = dccp_msk(sk);
 883         /* Check if there is anything to confirm in the first place */
 884         int yes = !list_empty(&dmsk->dccpms_conf);
 885
 886         if (!yes) {
 887                 struct dccp_opt_pend *opt;
 888
 889                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 890                         if (opt->dccpop_conf) {
 891                                 yes = 1;
 892                                 break;
 893                         }
 894                 }
 895         }
 896
 897         if (!yes)
 898                 return;
 899
 900         /* OK there is something to confirm... */
 901         /* XXX check if packet is in flight?  Send delayed ack?? */
 902         if (sk->sk_state == DCCP_OPEN)
 903                 dccp_send_ack(sk);
 904 }
 905
 906 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 907 {
 908         int rc;
 909
 910         /* Ignore Change requests other than during connection setup */
 911         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 912                 return 0;
 913         dccp_feat_debug(type, feature, *val);
 914
 915         /* figure out if it's SP or NN feature */
 916         switch (feature) {
 917         /* deal with SP features */
 918         case DCCPF_CCID:
 919                 rc = dccp_feat_sp(sk, type, feature, val, len);
 920                 break;
 921
 922         /* deal with NN features */
 923         case DCCPF_ACK_RATIO:
 924                 rc = dccp_feat_nn(sk, type, feature, val, len);
 925                 break;
 926
 927         /* XXX implement other features */
 928         default:
 929                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 930                               dccp_feat_typename(type), feature);
 931                 rc = -EFAULT;
 932                 break;
 933         }
 934
 935         /* check if there were problems changing features */
 936         if (rc) {
 937                 /* If we don't agree on SP, we sent a confirm for old value.
 938                  * However we propagate rc to caller in case option was
 939                  * mandatory
 940                  */
 941                 if (rc != DCCP_FEAT_SP_NOAGREE)
 942                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 943         }
 944
 945         /* generate the confirm [if required] */
 946         dccp_feat_flush_confirm(sk);
 947
 948         return rc;
 949 }
 950
 951 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 952
 953 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 954                            u8 *val, u8 len)
 955 {
 956         u8 t;
 957         struct dccp_opt_pend *opt;
 958         struct dccp_minisock *dmsk = dccp_msk(sk);
 959         int found = 0;
 960         int all_confirmed = 1;
 961
 962         /* Ignore Confirm options other than during connection setup */
 963         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 964                 return 0;
 965         dccp_feat_debug(type, feature, *val);
 966
 967         /* locate our change request */
 968         switch (type) {
 969         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 970         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 971         default:              DCCP_WARN("invalid type %d\n", type);
 972                               return 1;
 973
 974         }
 975         /* XXX sanity check feature value */
 976
 977         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 978                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 979                     opt->dccpop_feat == feature) {
 980                         found = 1;
 981                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 982
 983                         /* XXX do sanity check */
 984
 985                         opt->dccpop_conf = 1;
 986
 987                         /* We got a confirmation---change the option */
 988                         dccp_feat_update(sk, opt->dccpop_type,
 989                                          opt->dccpop_feat, *val);
 990
 991                         /* XXX check the return value of dccp_feat_update */
 992                         break;
 993                 }
 994
 995                 if (!opt->dccpop_conf)
 996                         all_confirmed = 0;
 997         }
 998
 999         if (!found)
1000                 dccp_pr_debug("%s(%d, ...) never requested\n",
1001                               dccp_feat_typename(type), feature);
1002         return 0;
1003 }
1004
1005 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
1006
1007 void dccp_feat_clean(struct dccp_minisock *dmsk)
1008 {
1009         struct dccp_opt_pend *opt, *next;
1010
1011         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
1012                                  dccpop_node) {
1013                 BUG_ON(opt->dccpop_val == NULL);
1014                 kfree(opt->dccpop_val);
1015
1016                 if (opt->dccpop_sc != NULL) {
1017                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
1018                         kfree(opt->dccpop_sc->dccpoc_val);
1019                         kfree(opt->dccpop_sc);
1020                 }
1021
1022                 kfree(opt);
1023         }
1024         INIT_LIST_HEAD(&dmsk->dccpms_pending);
1025
1026         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
1027                 BUG_ON(opt == NULL);
1028                 if (opt->dccpop_val != NULL)
1029                         kfree(opt->dccpop_val);
1030                 kfree(opt);
1031         }
1032         INIT_LIST_HEAD(&dmsk->dccpms_conf);
1033 }
1034
1035 EXPORT_SYMBOL_GPL(dccp_feat_clean);
1036
1037 /* this is to be called only when a listening sock creates its child.  It is
1038  * assumed by the function---the confirm is not duplicated, but rather it is
1039  * "passed on".
1040  */
1041 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
1042 {
1043         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
1044         struct dccp_minisock *newdmsk = dccp_msk(newsk);
1045         struct dccp_opt_pend *opt;
1046         int rc = 0;
1047
1048         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
1049         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
1050
1051         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
1052                 struct dccp_opt_pend *newopt;
1053                 /* copy the value of the option */
1054                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
1055
1056                 if (val == NULL)
1057                         goto out_clean;
1058
1059                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
1060                 if (newopt == NULL) {
1061                         kfree(val);
1062                         goto out_clean;
1063                 }
1064
1065                 /* insert the option */
1066                 newopt->dccpop_val = val;
1067                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
1068
1069                 /* XXX what happens with backlogs and multiple connections at
1070                  * once...
1071                  */
1072                 /* the master socket no longer needs to worry about confirms */
1073                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
1074
1075                 /* reset state for a new socket */
1076                 opt->dccpop_conf = 0;
1077         }
1078
1079         /* XXX not doing anything about the conf queue */
1080
1081 out:
1082         return rc;
1083
1084 out_clean:
1085         dccp_feat_clean(newdmsk);
1086         rc = -ENOMEM;
1087         goto out;
1088 }
1089
1090 EXPORT_SYMBOL_GPL(dccp_feat_clone);
1091
1092 int dccp_feat_init(struct sock *sk)
1093 {
1094         struct dccp_sock *dp = dccp_sk(sk);
1095         struct dccp_minisock *dmsk = dccp_msk(sk);
1096         int rc;
1097
1098         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
1099         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
1100
1101         /* CCID L */
1102         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
1103                                 &dmsk->dccpms_tx_ccid, 1);
1104         if (rc)
1105                 goto out;
1106
1107         /* CCID R */
1108         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
1109                                 &dmsk->dccpms_rx_ccid, 1);
1110         if (rc)
1111                 goto out;
1112
1113         /* Ack ratio */
1114         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1115                                 dmsk->dccpms_ack_ratio);
1116 out:
1117         return rc;
1118 }
1119
1120 EXPORT_SYMBOL_GPL(dccp_feat_init);
1121
1122 #ifdef CONFIG_IP_DCCP_DEBUG
1123 const char *dccp_feat_typename(const u8 type)
1124 {
1125         switch(type) {
1126         case DCCPO_CHANGE_L:  return("ChangeL");
1127         case DCCPO_CONFIRM_L: return("ConfirmL");
1128         case DCCPO_CHANGE_R:  return("ChangeR");
1129         case DCCPO_CONFIRM_R: return("ConfirmR");
1130         /* the following case must not appear in feature negotation  */
1131         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
1132         }
1133         return NULL;
1134 }
1135
1136 EXPORT_SYMBOL_GPL(dccp_feat_typename);
1137
1138 const char *dccp_feat_name(const u8 feat)
1139 {
1140         static const char *feature_names[] = {
1141                 [DCCPF_RESERVED]        = "Reserved",
1142                 [DCCPF_CCID]            = "CCID",
1143                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
1144                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1145                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
1146                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
1147                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1148                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
1149                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
1150                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
1151         };
1152         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1153                 return feature_names[DCCPF_RESERVED];
1154
1155         if (feat ==  DCCPF_SEND_LEV_RATE)
1156                 return "Send Loss Event Rate";
1157         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1158                 return "CCID-specific";
1159
1160         return feature_names[feat];
1161 }
1162
1163 EXPORT_SYMBOL_GPL(dccp_feat_name);
1164 #endif /* CONFIG_IP_DCCP_DEBUG */