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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 /**
 397  * dccp_feat_register_sp  -  Register requests to change SP feature values
 398  * @sk: client or listening socket
 399  * @feat: one of %dccp_feature_numbers
 400  * @is_local: whether the local (1) or remote (0) @feat is meant
 401  * @list: array of preferred values, in descending order of preference
 402  * @len: length of @list in bytes
 403  */
 404 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
 405                           u8 const *list, u8 len)
 406 {        /* any changes must be registered before establishing the connection */
 407         if (sk->sk_state != DCCP_CLOSED)
 408                 return -EISCONN;
 409         if (dccp_feat_type(feat) != FEAT_SP)
 410                 return -EINVAL;
 411         return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
 412                                   0, list, len);
 413 }
 414
 415 /* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
 416 int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
 417 {
 418         /* any changes must be registered before establishing the connection */
 419         if (sk->sk_state != DCCP_CLOSED)
 420                 return -EISCONN;
 421         if (dccp_feat_type(feat) != FEAT_NN)
 422                 return -EINVAL;
 423         return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
 424 }
 425
 426 /*
 427  *      Tracking features whose value depend on the choice of CCID
 428  *
 429  * This is designed with an extension in mind so that a list walk could be done
 430  * before activating any features. However, the existing framework was found to
 431  * work satisfactorily up until now, the automatic verification is left open.
 432  * When adding new CCIDs, add a corresponding dependency table here.
 433  */
 434 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
 435 {
 436         static const struct ccid_dependency ccid2_dependencies[2][2] = {
 437                 /*
 438                  * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
 439                  * feature and Send Ack Vector is an RX feature, `is_local'
 440                  * needs to be reversed.
 441                  */
 442                 {       /* Dependencies of the receiver-side (remote) CCID2 */
 443                         {
 444                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 445                                 .is_local       = true,
 446                                 .is_mandatory   = true,
 447                                 .val            = 1
 448                         },
 449                         { 0, 0, 0, 0 }
 450                 },
 451                 {       /* Dependencies of the sender-side (local) CCID2 */
 452                         {
 453                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 454                                 .is_local       = false,
 455                                 .is_mandatory   = true,
 456                                 .val            = 1
 457                         },
 458                         { 0, 0, 0, 0 }
 459                 }
 460         };
 461         static const struct ccid_dependency ccid3_dependencies[2][5] = {
 462                 {       /*
 463                          * Dependencies of the receiver-side CCID3
 464                          */
 465                         {       /* locally disable Ack Vectors */
 466                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 467                                 .is_local       = true,
 468                                 .is_mandatory   = false,
 469                                 .val            = 0
 470                         },
 471                         {       /* see below why Send Loss Event Rate is on */
 472                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 473                                 .is_local       = true,
 474                                 .is_mandatory   = true,
 475                                 .val            = 1
 476                         },
 477                         {       /* NDP Count is needed as per RFC 4342, 6.1.1 */
 478                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 479                                 .is_local       = false,
 480                                 .is_mandatory   = true,
 481                                 .val            = 1
 482                         },
 483                         { 0, 0, 0, 0 },
 484                 },
 485                 {       /*
 486                          * CCID3 at the TX side: we request that the HC-receiver
 487                          * will not send Ack Vectors (they will be ignored, so
 488                          * Mandatory is not set); we enable Send Loss Event Rate
 489                          * (Mandatory since the implementation does not support
 490                          * the Loss Intervals option of RFC 4342, 8.6).
 491                          * The last two options are for peer's information only.
 492                         */
 493                         {
 494                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 495                                 .is_local       = false,
 496                                 .is_mandatory   = false,
 497                                 .val            = 0
 498                         },
 499                         {
 500                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 501                                 .is_local       = false,
 502                                 .is_mandatory   = true,
 503                                 .val            = 1
 504                         },
 505                         {       /* this CCID does not support Ack Ratio */
 506                                 .dependent_feat = DCCPF_ACK_RATIO,
 507                                 .is_local       = true,
 508                                 .is_mandatory   = false,
 509                                 .val            = 0
 510                         },
 511                         {       /* tell receiver we are sending NDP counts */
 512                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 513                                 .is_local       = true,
 514                                 .is_mandatory   = false,
 515                                 .val            = 1
 516                         },
 517                         { 0, 0, 0, 0 }
 518                 }
 519         };
 520         switch (ccid) {
 521         case DCCPC_CCID2:
 522                 return ccid2_dependencies[is_local];
 523         case DCCPC_CCID3:
 524                 return ccid3_dependencies[is_local];
 525         default:
 526                 return NULL;
 527         }
 528 }
 529
 530 /**
 531  * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
 532  * @fn: feature-negotiation list to update
 533  * @id: CCID number to track
 534  * @is_local: whether TX CCID (1) or RX CCID (0) is meant
 535  * This function needs to be called after registering all other features.
 536  */
 537 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
 538 {
 539         const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
 540         int i, rc = (table == NULL);
 541
 542         for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
 543                 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
 544                         rc = __feat_register_sp(fn, table[i].dependent_feat,
 545                                                     table[i].is_local,
 546                                                     table[i].is_mandatory,
 547                                                     &table[i].val, 1);
 548                 else
 549                         rc = __feat_register_nn(fn, table[i].dependent_feat,
 550                                                     table[i].is_mandatory,
 551                                                     table[i].val);
 552         return rc;
 553 }
 554
 555 /**
 556  * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
 557  * @dp: client or listening socket (settings will be inherited)
 558  * This is called after all registrations (socket initialisation, sysctls, and
 559  * sockopt calls), and before sending the first packet containing Change options
 560  * (ie. client-Request or server-Response), to ensure internal consistency.
 561  */
 562 int dccp_feat_finalise_settings(struct dccp_sock *dp)
 563 {
 564         struct list_head *fn = &dp->dccps_featneg;
 565         struct dccp_feat_entry *entry;
 566         int i = 2, ccids[2] = { -1, -1 };
 567
 568         /*
 569          * Propagating CCIDs:
 570          * 1) not useful to propagate CCID settings if this host advertises more
 571          *    than one CCID: the choice of CCID  may still change - if this is
 572          *    the client, or if this is the server and the client sends
 573          *    singleton CCID values.
 574          * 2) since is that propagate_ccid changes the list, we defer changing
 575          *    the sorted list until after the traversal.
 576          */
 577         list_for_each_entry(entry, fn, node)
 578                 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
 579                         ccids[entry->is_local] = entry->val.sp.vec[0];
 580         while (i--)
 581                 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
 582                         return -1;
 583         return 0;
 584 }
 585
 586 /**
 587  * dccp_feat_server_ccid_dependencies  -  Resolve CCID-dependent features
 588  * It is the server which resolves the dependencies once the CCID has been
 589  * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
 590  */
 591 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
 592 {
 593         struct list_head *fn = &dreq->dreq_featneg;
 594         struct dccp_feat_entry *entry;
 595         u8 is_local, ccid;
 596
 597         for (is_local = 0; is_local <= 1; is_local++) {
 598                 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
 599
 600                 if (entry != NULL && !entry->empty_confirm)
 601                         ccid = entry->val.sp.vec[0];
 602                 else
 603                         ccid = dccp_feat_default_value(DCCPF_CCID);
 604
 605                 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
 606                         return -1;
 607         }
 608         return 0;
 609 }
 610
 611 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 612 {
 613         struct dccp_sock *dp = dccp_sk(sk);
 614         struct dccp_minisock *dmsk = dccp_msk(sk);
 615         /* figure out if we are changing our CCID or the peer's */
 616         const int rx = type == DCCPO_CHANGE_R;
 617         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 618         struct ccid *new_ccid;
 619
 620         /* Check if nothing is being changed. */
 621         if (ccid_nr == new_ccid_nr)
 622                 return 0;
 623
 624         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 625         if (new_ccid == NULL)
 626                 return -ENOMEM;
 627
 628         if (rx) {
 629                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 630                 dp->dccps_hc_rx_ccid = new_ccid;
 631                 dmsk->dccpms_rx_ccid = new_ccid_nr;
 632         } else {
 633                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 634                 dp->dccps_hc_tx_ccid = new_ccid;
 635                 dmsk->dccpms_tx_ccid = new_ccid_nr;
 636         }
 637
 638         return 0;
 639 }
 640
 641 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 642 {
 643         dccp_feat_debug(type, feat, val);
 644
 645         switch (feat) {
 646         case DCCPF_CCID:
 647                 return dccp_feat_update_ccid(sk, type, val);
 648         default:
 649                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 650                               dccp_feat_typename(type), feat);
 651                 break;
 652         }
 653         return 0;
 654 }
 655
 656 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 657                                u8 *rpref, u8 rlen)
 658 {
 659         struct dccp_sock *dp = dccp_sk(sk);
 660         u8 *spref, slen, *res = NULL;
 661         int i, j, rc, agree = 1;
 662
 663         BUG_ON(rpref == NULL);
 664
 665         /* check if we are the black sheep */
 666         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 667                 spref = rpref;
 668                 slen  = rlen;
 669                 rpref = opt->dccpop_val;
 670                 rlen  = opt->dccpop_len;
 671         } else {
 672                 spref = opt->dccpop_val;
 673                 slen  = opt->dccpop_len;
 674         }
 675         /*
 676          * Now we have server preference list in spref and client preference in
 677          * rpref
 678          */
 679         BUG_ON(spref == NULL);
 680         BUG_ON(rpref == NULL);
 681
 682         /* FIXME sanity check vals */
 683
 684         /* Are values in any order?  XXX Lame "algorithm" here */
 685         for (i = 0; i < slen; i++) {
 686                 for (j = 0; j < rlen; j++) {
 687                         if (spref[i] == rpref[j]) {
 688                                 res = &spref[i];
 689                                 break;
 690                         }
 691                 }
 692                 if (res)
 693                         break;
 694         }
 695
 696         /* we didn't agree on anything */
 697         if (res == NULL) {
 698                 /* confirm previous value */
 699                 switch (opt->dccpop_feat) {
 700                 case DCCPF_CCID:
 701                         /* XXX did i get this right? =P */
 702                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 703                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 704                         else
 705                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 706                         break;
 707
 708                 default:
 709                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 710                         /* XXX implement res */
 711                         return -EFAULT;
 712                 }
 713
 714                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 715                 agree = 0; /* this is used for mandatory options... */
 716         }
 717
 718         /* need to put result and our preference list */
 719         rlen = 1 + opt->dccpop_len;
 720         rpref = kmalloc(rlen, GFP_ATOMIC);
 721         if (rpref == NULL)
 722                 return -ENOMEM;
 723
 724         *rpref = *res;
 725         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 726
 727         /* put it in the "confirm queue" */
 728         if (opt->dccpop_sc == NULL) {
 729                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 730                 if (opt->dccpop_sc == NULL) {
 731                         kfree(rpref);
 732                         return -ENOMEM;
 733                 }
 734         } else {
 735                 /* recycle the confirm slot */
 736                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 737                 kfree(opt->dccpop_sc->dccpoc_val);
 738                 dccp_pr_debug("recycling confirm slot\n");
 739         }
 740         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 741
 742         opt->dccpop_sc->dccpoc_val = rpref;
 743         opt->dccpop_sc->dccpoc_len = rlen;
 744
 745         /* update the option on our side [we are about to send the confirm] */
 746         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 747         if (rc) {
 748                 kfree(opt->dccpop_sc->dccpoc_val);
 749                 kfree(opt->dccpop_sc);
 750                 opt->dccpop_sc = NULL;
 751                 return rc;
 752         }
 753
 754         dccp_pr_debug("Will confirm %d\n", *rpref);
 755
 756         /* say we want to change to X but we just got a confirm X, suppress our
 757          * change
 758          */
 759         if (!opt->dccpop_conf) {
 760                 if (*opt->dccpop_val == *res)
 761                         opt->dccpop_conf = 1;
 762                 dccp_pr_debug("won't ask for change of same feature\n");
 763         }
 764
 765         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 766 }
 767
 768 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 769 {
 770         struct dccp_minisock *dmsk = dccp_msk(sk);
 771         struct dccp_opt_pend *opt;
 772         int rc = 1;
 773         u8 t;
 774
 775         /*
 776          * We received a CHANGE.  We gotta match it against our own preference
 777          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 778          * to compare our CHANGE_L list.
 779          */
 780         if (type == DCCPO_CHANGE_L)
 781                 t = DCCPO_CHANGE_R;
 782         else
 783                 t = DCCPO_CHANGE_L;
 784
 785         /* find our preference list for this feature */
 786         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 787                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 788                         continue;
 789
 790                 /* find the winner from the two preference lists */
 791                 rc = dccp_feat_reconcile(sk, opt, val, len);
 792                 break;
 793         }
 794
 795         /* We didn't deal with the change.  This can happen if we have no
 796          * preference list for the feature.  In fact, it just shouldn't
 797          * happen---if we understand a feature, we should have a preference list
 798          * with at least the default value.
 799          */
 800         BUG_ON(rc == 1);
 801
 802         return rc;
 803 }
 804
 805 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 806 {
 807         struct dccp_opt_pend *opt;
 808         struct dccp_minisock *dmsk = dccp_msk(sk);
 809         u8 *copy;
 810         int rc;
 811
 812         /* NN features must be Change L (sec. 6.3.2) */
 813         if (type != DCCPO_CHANGE_L) {
 814                 dccp_pr_debug("received %s for NN feature %d\n",
 815                                 dccp_feat_typename(type), feature);
 816                 return -EFAULT;
 817         }
 818
 819         /* XXX sanity check opt val */
 820
 821         /* copy option so we can confirm it */
 822         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 823         if (opt == NULL)
 824                 return -ENOMEM;
 825
 826         copy = kmemdup(val, len, GFP_ATOMIC);
 827         if (copy == NULL) {
 828                 kfree(opt);
 829                 return -ENOMEM;
 830         }
 831
 832         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 833         opt->dccpop_feat = feature;
 834         opt->dccpop_val  = copy;
 835         opt->dccpop_len  = len;
 836
 837         /* change feature */
 838         rc = dccp_feat_update(sk, type, feature, *val);
 839         if (rc) {
 840                 kfree(opt->dccpop_val);
 841                 kfree(opt);
 842                 return rc;
 843         }
 844
 845         dccp_feat_debug(type, feature, *copy);
 846
 847         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 848
 849         return 0;
 850 }
 851
 852 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 853                                     u8 type, u8 feature)
 854 {
 855         /* XXX check if other confirms for that are queued and recycle slot */
 856         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 857
 858         if (opt == NULL) {
 859                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 860                  * after all =P
 861                  */
 862                 return;
 863         }
 864
 865         switch (type) {
 866         case DCCPO_CHANGE_L:
 867                 opt->dccpop_type = DCCPO_CONFIRM_R;
 868                 break;
 869         case DCCPO_CHANGE_R:
 870                 opt->dccpop_type = DCCPO_CONFIRM_L;
 871                 break;
 872         default:
 873                 DCCP_WARN("invalid type %d\n", type);
 874                 kfree(opt);
 875                 return;
 876         }
 877         opt->dccpop_feat = feature;
 878         opt->dccpop_val  = NULL;
 879         opt->dccpop_len  = 0;
 880
 881         /* change feature */
 882         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
 883
 884         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 885 }
 886
 887 static void dccp_feat_flush_confirm(struct sock *sk)
 888 {
 889         struct dccp_minisock *dmsk = dccp_msk(sk);
 890         /* Check if there is anything to confirm in the first place */
 891         int yes = !list_empty(&dmsk->dccpms_conf);
 892
 893         if (!yes) {
 894                 struct dccp_opt_pend *opt;
 895
 896                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 897                         if (opt->dccpop_conf) {
 898                                 yes = 1;
 899                                 break;
 900                         }
 901                 }
 902         }
 903
 904         if (!yes)
 905                 return;
 906
 907         /* OK there is something to confirm... */
 908         /* XXX check if packet is in flight?  Send delayed ack?? */
 909         if (sk->sk_state == DCCP_OPEN)
 910                 dccp_send_ack(sk);
 911 }
 912
 913 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 914 {
 915         int rc;
 916
 917         /* Ignore Change requests other than during connection setup */
 918         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 919                 return 0;
 920         dccp_feat_debug(type, feature, *val);
 921
 922         /* figure out if it's SP or NN feature */
 923         switch (feature) {
 924         /* deal with SP features */
 925         case DCCPF_CCID:
 926                 rc = dccp_feat_sp(sk, type, feature, val, len);
 927                 break;
 928
 929         /* deal with NN features */
 930         case DCCPF_ACK_RATIO:
 931                 rc = dccp_feat_nn(sk, type, feature, val, len);
 932                 break;
 933
 934         /* XXX implement other features */
 935         default:
 936                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
 937                               dccp_feat_typename(type), feature);
 938                 rc = -EFAULT;
 939                 break;
 940         }
 941
 942         /* check if there were problems changing features */
 943         if (rc) {
 944                 /* If we don't agree on SP, we sent a confirm for old value.
 945                  * However we propagate rc to caller in case option was
 946                  * mandatory
 947                  */
 948                 if (rc != DCCP_FEAT_SP_NOAGREE)
 949                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
 950         }
 951
 952         /* generate the confirm [if required] */
 953         dccp_feat_flush_confirm(sk);
 954
 955         return rc;
 956 }
 957
 958 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 959
 960 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 961                            u8 *val, u8 len)
 962 {
 963         u8 t;
 964         struct dccp_opt_pend *opt;
 965         struct dccp_minisock *dmsk = dccp_msk(sk);
 966         int found = 0;
 967         int all_confirmed = 1;
 968
 969         /* Ignore Confirm options other than during connection setup */
 970         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
 971                 return 0;
 972         dccp_feat_debug(type, feature, *val);
 973
 974         /* locate our change request */
 975         switch (type) {
 976         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
 977         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
 978         default:              DCCP_WARN("invalid type %d\n", type);
 979                               return 1;
 980
 981         }
 982         /* XXX sanity check feature value */
 983
 984         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 985                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 986                     opt->dccpop_feat == feature) {
 987                         found = 1;
 988                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
 989
 990                         /* XXX do sanity check */
 991
 992                         opt->dccpop_conf = 1;
 993
 994                         /* We got a confirmation---change the option */
 995                         dccp_feat_update(sk, opt->dccpop_type,
 996                                          opt->dccpop_feat, *val);
 997
 998                         /* XXX check the return value of dccp_feat_update */
 999                         break;
1000                 }
1001
1002                 if (!opt->dccpop_conf)
1003                         all_confirmed = 0;
1004         }
1005
1006         if (!found)
1007                 dccp_pr_debug("%s(%d, ...) never requested\n",
1008                               dccp_feat_typename(type), feature);
1009         return 0;
1010 }
1011
1012 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
1013
1014 void dccp_feat_clean(struct dccp_minisock *dmsk)
1015 {
1016         struct dccp_opt_pend *opt, *next;
1017
1018         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
1019                                  dccpop_node) {
1020                 BUG_ON(opt->dccpop_val == NULL);
1021                 kfree(opt->dccpop_val);
1022
1023                 if (opt->dccpop_sc != NULL) {
1024                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
1025                         kfree(opt->dccpop_sc->dccpoc_val);
1026                         kfree(opt->dccpop_sc);
1027                 }
1028
1029                 kfree(opt);
1030         }
1031         INIT_LIST_HEAD(&dmsk->dccpms_pending);
1032
1033         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
1034                 BUG_ON(opt == NULL);
1035                 if (opt->dccpop_val != NULL)
1036                         kfree(opt->dccpop_val);
1037                 kfree(opt);
1038         }
1039         INIT_LIST_HEAD(&dmsk->dccpms_conf);
1040 }
1041
1042 EXPORT_SYMBOL_GPL(dccp_feat_clean);
1043
1044 /* this is to be called only when a listening sock creates its child.  It is
1045  * assumed by the function---the confirm is not duplicated, but rather it is
1046  * "passed on".
1047  */
1048 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
1049 {
1050         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
1051         struct dccp_minisock *newdmsk = dccp_msk(newsk);
1052         struct dccp_opt_pend *opt;
1053         int rc = 0;
1054
1055         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
1056         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
1057
1058         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
1059                 struct dccp_opt_pend *newopt;
1060                 /* copy the value of the option */
1061                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
1062
1063                 if (val == NULL)
1064                         goto out_clean;
1065
1066                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
1067                 if (newopt == NULL) {
1068                         kfree(val);
1069                         goto out_clean;
1070                 }
1071
1072                 /* insert the option */
1073                 newopt->dccpop_val = val;
1074                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
1075
1076                 /* XXX what happens with backlogs and multiple connections at
1077                  * once...
1078                  */
1079                 /* the master socket no longer needs to worry about confirms */
1080                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
1081
1082                 /* reset state for a new socket */
1083                 opt->dccpop_conf = 0;
1084         }
1085
1086         /* XXX not doing anything about the conf queue */
1087
1088 out:
1089         return rc;
1090
1091 out_clean:
1092         dccp_feat_clean(newdmsk);
1093         rc = -ENOMEM;
1094         goto out;
1095 }
1096
1097 EXPORT_SYMBOL_GPL(dccp_feat_clone);
1098
1099 int dccp_feat_init(struct sock *sk)
1100 {
1101         struct dccp_sock *dp = dccp_sk(sk);
1102         struct dccp_minisock *dmsk = dccp_msk(sk);
1103         int rc;
1104
1105         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
1106         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
1107
1108         /* CCID L */
1109         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
1110                                 &dmsk->dccpms_tx_ccid, 1);
1111         if (rc)
1112                 goto out;
1113
1114         /* CCID R */
1115         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
1116                                 &dmsk->dccpms_rx_ccid, 1);
1117         if (rc)
1118                 goto out;
1119
1120         /* Ack ratio */
1121         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1122                                 dp->dccps_l_ack_ratio);
1123 out:
1124         return rc;
1125 }
1126
1127 EXPORT_SYMBOL_GPL(dccp_feat_init);
1128
1129 #ifdef CONFIG_IP_DCCP_DEBUG
1130 const char *dccp_feat_typename(const u8 type)
1131 {
1132         switch(type) {
1133         case DCCPO_CHANGE_L:  return("ChangeL");
1134         case DCCPO_CONFIRM_L: return("ConfirmL");
1135         case DCCPO_CHANGE_R:  return("ChangeR");
1136         case DCCPO_CONFIRM_R: return("ConfirmR");
1137         /* the following case must not appear in feature negotation  */
1138         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
1139         }
1140         return NULL;
1141 }
1142
1143 EXPORT_SYMBOL_GPL(dccp_feat_typename);
1144
1145 const char *dccp_feat_name(const u8 feat)
1146 {
1147         static const char *feature_names[] = {
1148                 [DCCPF_RESERVED]        = "Reserved",
1149                 [DCCPF_CCID]            = "CCID",
1150                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
1151                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1152                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
1153                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
1154                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1155                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
1156                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
1157                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
1158         };
1159         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1160                 return feature_names[DCCPF_RESERVED];
1161
1162         if (feat ==  DCCPF_SEND_LEV_RATE)
1163                 return "Send Loss Event Rate";
1164         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1165                 return "CCID-specific";
1166
1167         return feature_names[feat];
1168 }
1169
1170 EXPORT_SYMBOL_GPL(dccp_feat_name);
1171 #endif /* CONFIG_IP_DCCP_DEBUG */