net/dccp/feat.c

   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          * There are no default values for unknown features, so encountering a
 100          * negative index here indicates a serious problem somewhere else.
 101          */
 102         DCCP_BUG_ON(idx < 0);
 103
 104         return idx < 0 ? 0 : dccp_feat_table[idx].default_value;
 105 }
 106
 107 /* copy constructor, fval must not already contain allocated memory */
 108 static int dccp_feat_clone_sp_val(dccp_feat_val *fval, u8 const *val, u8 len)
 109 {
 110         fval->sp.len = len;
 111         if (fval->sp.len > 0) {
 112                 fval->sp.vec = kmemdup(val, len, gfp_any());
 113                 if (fval->sp.vec == NULL) {
 114                         fval->sp.len = 0;
 115                         return -ENOBUFS;
 116                 }
 117         }
 118         return 0;
 119 }
 120
 121 static void dccp_feat_val_destructor(u8 feat_num, dccp_feat_val *val)
 122 {
 123         if (unlikely(val == NULL))
 124                 return;
 125         if (dccp_feat_type(feat_num) == FEAT_SP)
 126                 kfree(val->sp.vec);
 127         memset(val, 0, sizeof(*val));
 128 }
 129
 130 static struct dccp_feat_entry *
 131               dccp_feat_clone_entry(struct dccp_feat_entry const *original)
 132 {
 133         struct dccp_feat_entry *new;
 134         u8 type = dccp_feat_type(original->feat_num);
 135
 136         if (type == FEAT_UNKNOWN)
 137                 return NULL;
 138
 139         new = kmemdup(original, sizeof(struct dccp_feat_entry), gfp_any());
 140         if (new == NULL)
 141                 return NULL;
 142
 143         if (type == FEAT_SP && dccp_feat_clone_sp_val(&new->val,
 144                                                       original->val.sp.vec,
 145                                                       original->val.sp.len)) {
 146                 kfree(new);
 147                 return NULL;
 148         }
 149         return new;
 150 }
 151
 152 static void dccp_feat_entry_destructor(struct dccp_feat_entry *entry)
 153 {
 154         if (entry != NULL) {
 155                 dccp_feat_val_destructor(entry->feat_num, &entry->val);
 156                 kfree(entry);
 157         }
 158 }
 159
 160 /*
 161  * List management functions
 162  *
 163  * Feature negotiation lists rely on and maintain the following invariants:
 164  * - each feat_num in the list is known, i.e. we know its type and default value
 165  * - each feat_num/is_local combination is unique (old entries are overwritten)
 166  * - SP values are always freshly allocated
 167  * - list is sorted in increasing order of feature number (faster lookup)
 168  */
 169 static struct dccp_feat_entry *dccp_feat_list_lookup(struct list_head *fn_list,
 170                                                      u8 feat_num, bool is_local)
 171 {
 172         struct dccp_feat_entry *entry;
 173
 174         list_for_each_entry(entry, fn_list, node) {
 175                 if (entry->feat_num == feat_num && entry->is_local == is_local)
 176                         return entry;
 177                 else if (entry->feat_num > feat_num)
 178                         break;
 179         }
 180         return NULL;
 181 }
 182
 183 /**
 184  * dccp_feat_entry_new  -  Central list update routine (called by all others)
 185  * @head:  list to add to
 186  * @feat:  feature number
 187  * @local: whether the local (1) or remote feature with number @feat is meant
 188  * This is the only constructor and serves to ensure the above invariants.
 189  */
 190 static struct dccp_feat_entry *
 191               dccp_feat_entry_new(struct list_head *head, u8 feat, bool local)
 192 {
 193         struct dccp_feat_entry *entry;
 194
 195         list_for_each_entry(entry, head, node)
 196                 if (entry->feat_num == feat && entry->is_local == local) {
 197                         dccp_feat_val_destructor(entry->feat_num, &entry->val);
 198                         return entry;
 199                 } else if (entry->feat_num > feat) {
 200                         head = &entry->node;
 201                         break;
 202                 }
 203
 204         entry = kmalloc(sizeof(*entry), gfp_any());
 205         if (entry != NULL) {
 206                 entry->feat_num = feat;
 207                 entry->is_local = local;
 208                 list_add_tail(&entry->node, head);
 209         }
 210         return entry;
 211 }
 212
 213 /**
 214  * dccp_feat_push_change  -  Add/overwrite a Change option in the list
 215  * @fn_list: feature-negotiation list to update
 216  * @feat: one of %dccp_feature_numbers
 217  * @local: whether local (1) or remote (0) @feat_num is meant
 218  * @needs_mandatory: whether to use Mandatory feature negotiation options
 219  * @fval: pointer to NN/SP value to be inserted (will be copied)
 220  */
 221 static int dccp_feat_push_change(struct list_head *fn_list, u8 feat, u8 local,
 222                                  u8 mandatory, dccp_feat_val *fval)
 223 {
 224         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 225
 226         if (new == NULL)
 227                 return -ENOMEM;
 228
 229         new->feat_num        = feat;
 230         new->is_local        = local;
 231         new->state           = FEAT_INITIALISING;
 232         new->needs_confirm   = 0;
 233         new->empty_confirm   = 0;
 234         new->val             = *fval;
 235         new->needs_mandatory = mandatory;
 236
 237         return 0;
 238 }
 239
 240 /**
 241  * dccp_feat_push_confirm  -  Add a Confirm entry to the FN list
 242  * @fn_list: feature-negotiation list to add to
 243  * @feat: one of %dccp_feature_numbers
 244  * @local: whether local (1) or remote (0) @feat_num is being confirmed
 245  * @fval: pointer to NN/SP value to be inserted or NULL
 246  * Returns 0 on success, a Reset code for further processing otherwise.
 247  */
 248 static int dccp_feat_push_confirm(struct list_head *fn_list, u8 feat, u8 local,
 249                                   dccp_feat_val *fval)
 250 {
 251         struct dccp_feat_entry *new = dccp_feat_entry_new(fn_list, feat, local);
 252
 253         if (new == NULL)
 254                 return DCCP_RESET_CODE_TOO_BUSY;
 255
 256         new->feat_num        = feat;
 257         new->is_local        = local;
 258         new->state           = FEAT_STABLE;     /* transition in 6.6.2 */
 259         new->needs_confirm   = 1;
 260         new->empty_confirm   = (fval == NULL);
 261         new->val.nn          = 0;               /* zeroes the whole structure */
 262         if (!new->empty_confirm)
 263                 new->val     = *fval;
 264         new->needs_mandatory = 0;
 265
 266         return 0;
 267 }
 268
 269 static int dccp_push_empty_confirm(struct list_head *fn_list, u8 feat, u8 local)
 270 {
 271         return dccp_feat_push_confirm(fn_list, feat, local, NULL);
 272 }
 273
 274 static inline void dccp_feat_list_pop(struct dccp_feat_entry *entry)
 275 {
 276         list_del(&entry->node);
 277         dccp_feat_entry_destructor(entry);
 278 }
 279
 280 void dccp_feat_list_purge(struct list_head *fn_list)
 281 {
 282         struct dccp_feat_entry *entry, *next;
 283
 284         list_for_each_entry_safe(entry, next, fn_list, node)
 285                 dccp_feat_entry_destructor(entry);
 286         INIT_LIST_HEAD(fn_list);
 287 }
 288 EXPORT_SYMBOL_GPL(dccp_feat_list_purge);
 289
 290 /* generate @to as full clone of @from - @to must not contain any nodes */
 291 int dccp_feat_clone_list(struct list_head const *from, struct list_head *to)
 292 {
 293         struct dccp_feat_entry *entry, *new;
 294
 295         INIT_LIST_HEAD(to);
 296         list_for_each_entry(entry, from, node) {
 297                 new = dccp_feat_clone_entry(entry);
 298                 if (new == NULL)
 299                         goto cloning_failed;
 300                 list_add_tail(&new->node, to);
 301         }
 302         return 0;
 303
 304 cloning_failed:
 305         dccp_feat_list_purge(to);
 306         return -ENOMEM;
 307 }
 308
 309 /**
 310  * dccp_feat_valid_nn_length  -  Enforce length constraints on NN options
 311  * Length is between 0 and %DCCP_OPTVAL_MAXLEN. Used for outgoing packets only,
 312  * incoming options are accepted as long as their values are valid.
 313  */
 314 static u8 dccp_feat_valid_nn_length(u8 feat_num)
 315 {
 316         if (feat_num == DCCPF_ACK_RATIO)        /* RFC 4340, 11.3 and 6.6.8 */
 317                 return 2;
 318         if (feat_num == DCCPF_SEQUENCE_WINDOW)  /* RFC 4340, 7.5.2 and 6.5  */
 319                 return 6;
 320         return 0;
 321 }
 322
 323 static u8 dccp_feat_is_valid_nn_val(u8 feat_num, u64 val)
 324 {
 325         switch (feat_num) {
 326         case DCCPF_ACK_RATIO:
 327                 return val <= DCCPF_ACK_RATIO_MAX;
 328         case DCCPF_SEQUENCE_WINDOW:
 329                 return val >= DCCPF_SEQ_WMIN && val <= DCCPF_SEQ_WMAX;
 330         }
 331         return 0;       /* feature unknown - so we can't tell */
 332 }
 333
 334 /* check that SP values are within the ranges defined in RFC 4340 */
 335 static u8 dccp_feat_is_valid_sp_val(u8 feat_num, u8 val)
 336 {
 337         switch (feat_num) {
 338         case DCCPF_CCID:
 339                 return val == DCCPC_CCID2 || val == DCCPC_CCID3;
 340         /* Type-check Boolean feature values: */
 341         case DCCPF_SHORT_SEQNOS:
 342         case DCCPF_ECN_INCAPABLE:
 343         case DCCPF_SEND_ACK_VECTOR:
 344         case DCCPF_SEND_NDP_COUNT:
 345         case DCCPF_DATA_CHECKSUM:
 346         case DCCPF_SEND_LEV_RATE:
 347                 return val < 2;
 348         case DCCPF_MIN_CSUM_COVER:
 349                 return val < 16;
 350         }
 351         return 0;                       /* feature unknown */
 352 }
 353
 354 static u8 dccp_feat_sp_list_ok(u8 feat_num, u8 const *sp_list, u8 sp_len)
 355 {
 356         if (sp_list == NULL || sp_len < 1)
 357                 return 0;
 358         while (sp_len--)
 359                 if (!dccp_feat_is_valid_sp_val(feat_num, *sp_list++))
 360                         return 0;
 361         return 1;
 362 }
 363
 364 /**
 365  * dccp_feat_insert_opts  -  Generate FN options from current list state
 366  * @skb: next sk_buff to be sent to the peer
 367  * @dp: for client during handshake and general negotiation
 368  * @dreq: used by the server only (all Changes/Confirms in LISTEN/RESPOND)
 369  */
 370 int dccp_feat_insert_opts(struct dccp_sock *dp, struct dccp_request_sock *dreq,
 371                           struct sk_buff *skb)
 372 {
 373         struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
 374         struct dccp_feat_entry *pos, *next;
 375         u8 opt, type, len, *ptr, nn_in_nbo[DCCP_OPTVAL_MAXLEN];
 376         bool rpt;
 377
 378         /* put entries into @skb in the order they appear in the list */
 379         list_for_each_entry_safe_reverse(pos, next, fn, node) {
 380                 opt  = dccp_feat_genopt(pos);
 381                 type = dccp_feat_type(pos->feat_num);
 382                 rpt  = false;
 383
 384                 if (pos->empty_confirm) {
 385                         len = 0;
 386                         ptr = NULL;
 387                 } else {
 388                         if (type == FEAT_SP) {
 389                                 len = pos->val.sp.len;
 390                                 ptr = pos->val.sp.vec;
 391                                 rpt = pos->needs_confirm;
 392                         } else if (type == FEAT_NN) {
 393                                 len = dccp_feat_valid_nn_length(pos->feat_num);
 394                                 ptr = nn_in_nbo;
 395                                 dccp_encode_value_var(pos->val.nn, ptr, len);
 396                         } else {
 397                                 DCCP_BUG("unknown feature %u", pos->feat_num);
 398                                 return -1;
 399                         }
 400                 }
 401
 402                 if (dccp_insert_fn_opt(skb, opt, pos->feat_num, ptr, len, rpt))
 403                         return -1;
 404                 if (pos->needs_mandatory && dccp_insert_option_mandatory(skb))
 405                         return -1;
 406                 /*
 407                  * Enter CHANGING after transmitting the Change option (6.6.2).
 408                  */
 409                 if (pos->state == FEAT_INITIALISING)
 410                         pos->state = FEAT_CHANGING;
 411         }
 412         return 0;
 413 }
 414
 415 /**
 416  * __feat_register_nn  -  Register new NN value on socket
 417  * @fn: feature-negotiation list to register with
 418  * @feat: an NN feature from %dccp_feature_numbers
 419  * @mandatory: use Mandatory option if 1
 420  * @nn_val: value to register (restricted to 4 bytes)
 421  * Note that NN features are local by definition (RFC 4340, 6.3.2).
 422  */
 423 static int __feat_register_nn(struct list_head *fn, u8 feat,
 424                               u8 mandatory, u64 nn_val)
 425 {
 426         dccp_feat_val fval = { .nn = nn_val };
 427
 428         if (dccp_feat_type(feat) != FEAT_NN ||
 429             !dccp_feat_is_valid_nn_val(feat, nn_val))
 430                 return -EINVAL;
 431
 432         /* Don't bother with default values, they will be activated anyway. */
 433         if (nn_val - (u64)dccp_feat_default_value(feat) == 0)
 434                 return 0;
 435
 436         return dccp_feat_push_change(fn, feat, 1, mandatory, &fval);
 437 }
 438
 439 /**
 440  * __feat_register_sp  -  Register new SP value/list on socket
 441  * @fn: feature-negotiation list to register with
 442  * @feat: an SP feature from %dccp_feature_numbers
 443  * @is_local: whether the local (1) or the remote (0) @feat is meant
 444  * @mandatory: use Mandatory option if 1
 445  * @sp_val: SP value followed by optional preference list
 446  * @sp_len: length of @sp_val in bytes
 447  */
 448 static int __feat_register_sp(struct list_head *fn, u8 feat, u8 is_local,
 449                               u8 mandatory, u8 const *sp_val, u8 sp_len)
 450 {
 451         dccp_feat_val fval;
 452
 453         if (dccp_feat_type(feat) != FEAT_SP ||
 454             !dccp_feat_sp_list_ok(feat, sp_val, sp_len))
 455                 return -EINVAL;
 456
 457         /* Avoid negotiating alien CCIDs by only advertising supported ones */
 458         if (feat == DCCPF_CCID && !ccid_support_check(sp_val, sp_len))
 459                 return -EOPNOTSUPP;
 460
 461         if (dccp_feat_clone_sp_val(&fval, sp_val, sp_len))
 462                 return -ENOMEM;
 463
 464         return dccp_feat_push_change(fn, feat, is_local, mandatory, &fval);
 465 }
 466
 467 /**
 468  * dccp_feat_register_sp  -  Register requests to change SP feature values
 469  * @sk: client or listening socket
 470  * @feat: one of %dccp_feature_numbers
 471  * @is_local: whether the local (1) or remote (0) @feat is meant
 472  * @list: array of preferred values, in descending order of preference
 473  * @len: length of @list in bytes
 474  */
 475 int dccp_feat_register_sp(struct sock *sk, u8 feat, u8 is_local,
 476                           u8 const *list, u8 len)
 477 {        /* any changes must be registered before establishing the connection */
 478         if (sk->sk_state != DCCP_CLOSED)
 479                 return -EISCONN;
 480         if (dccp_feat_type(feat) != FEAT_SP)
 481                 return -EINVAL;
 482         return __feat_register_sp(&dccp_sk(sk)->dccps_featneg, feat, is_local,
 483                                   0, list, len);
 484 }
 485
 486 /* Analogous to dccp_feat_register_sp(), but for non-negotiable values */
 487 int dccp_feat_register_nn(struct sock *sk, u8 feat, u64 val)
 488 {
 489         /* any changes must be registered before establishing the connection */
 490         if (sk->sk_state != DCCP_CLOSED)
 491                 return -EISCONN;
 492         if (dccp_feat_type(feat) != FEAT_NN)
 493                 return -EINVAL;
 494         return __feat_register_nn(&dccp_sk(sk)->dccps_featneg, feat, 0, val);
 495 }
 496
 497 /*
 498  *      Tracking features whose value depend on the choice of CCID
 499  *
 500  * This is designed with an extension in mind so that a list walk could be done
 501  * before activating any features. However, the existing framework was found to
 502  * work satisfactorily up until now, the automatic verification is left open.
 503  * When adding new CCIDs, add a corresponding dependency table here.
 504  */
 505 static const struct ccid_dependency *dccp_feat_ccid_deps(u8 ccid, bool is_local)
 506 {
 507         static const struct ccid_dependency ccid2_dependencies[2][2] = {
 508                 /*
 509                  * CCID2 mandates Ack Vectors (RFC 4341, 4.): as CCID is a TX
 510                  * feature and Send Ack Vector is an RX feature, `is_local'
 511                  * needs to be reversed.
 512                  */
 513                 {       /* Dependencies of the receiver-side (remote) CCID2 */
 514                         {
 515                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 516                                 .is_local       = true,
 517                                 .is_mandatory   = true,
 518                                 .val            = 1
 519                         },
 520                         { 0, 0, 0, 0 }
 521                 },
 522                 {       /* Dependencies of the sender-side (local) CCID2 */
 523                         {
 524                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 525                                 .is_local       = false,
 526                                 .is_mandatory   = true,
 527                                 .val            = 1
 528                         },
 529                         { 0, 0, 0, 0 }
 530                 }
 531         };
 532         static const struct ccid_dependency ccid3_dependencies[2][5] = {
 533                 {       /*
 534                          * Dependencies of the receiver-side CCID3
 535                          */
 536                         {       /* locally disable Ack Vectors */
 537                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 538                                 .is_local       = true,
 539                                 .is_mandatory   = false,
 540                                 .val            = 0
 541                         },
 542                         {       /* see below why Send Loss Event Rate is on */
 543                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 544                                 .is_local       = true,
 545                                 .is_mandatory   = true,
 546                                 .val            = 1
 547                         },
 548                         {       /* NDP Count is needed as per RFC 4342, 6.1.1 */
 549                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 550                                 .is_local       = false,
 551                                 .is_mandatory   = true,
 552                                 .val            = 1
 553                         },
 554                         { 0, 0, 0, 0 },
 555                 },
 556                 {       /*
 557                          * CCID3 at the TX side: we request that the HC-receiver
 558                          * will not send Ack Vectors (they will be ignored, so
 559                          * Mandatory is not set); we enable Send Loss Event Rate
 560                          * (Mandatory since the implementation does not support
 561                          * the Loss Intervals option of RFC 4342, 8.6).
 562                          * The last two options are for peer's information only.
 563                         */
 564                         {
 565                                 .dependent_feat = DCCPF_SEND_ACK_VECTOR,
 566                                 .is_local       = false,
 567                                 .is_mandatory   = false,
 568                                 .val            = 0
 569                         },
 570                         {
 571                                 .dependent_feat = DCCPF_SEND_LEV_RATE,
 572                                 .is_local       = false,
 573                                 .is_mandatory   = true,
 574                                 .val            = 1
 575                         },
 576                         {       /* this CCID does not support Ack Ratio */
 577                                 .dependent_feat = DCCPF_ACK_RATIO,
 578                                 .is_local       = true,
 579                                 .is_mandatory   = false,
 580                                 .val            = 0
 581                         },
 582                         {       /* tell receiver we are sending NDP counts */
 583                                 .dependent_feat = DCCPF_SEND_NDP_COUNT,
 584                                 .is_local       = true,
 585                                 .is_mandatory   = false,
 586                                 .val            = 1
 587                         },
 588                         { 0, 0, 0, 0 }
 589                 }
 590         };
 591         switch (ccid) {
 592         case DCCPC_CCID2:
 593                 return ccid2_dependencies[is_local];
 594         case DCCPC_CCID3:
 595                 return ccid3_dependencies[is_local];
 596         default:
 597                 return NULL;
 598         }
 599 }
 600
 601 /**
 602  * dccp_feat_propagate_ccid - Resolve dependencies of features on choice of CCID
 603  * @fn: feature-negotiation list to update
 604  * @id: CCID number to track
 605  * @is_local: whether TX CCID (1) or RX CCID (0) is meant
 606  * This function needs to be called after registering all other features.
 607  */
 608 static int dccp_feat_propagate_ccid(struct list_head *fn, u8 id, bool is_local)
 609 {
 610         const struct ccid_dependency *table = dccp_feat_ccid_deps(id, is_local);
 611         int i, rc = (table == NULL);
 612
 613         for (i = 0; rc == 0 && table[i].dependent_feat != DCCPF_RESERVED; i++)
 614                 if (dccp_feat_type(table[i].dependent_feat) == FEAT_SP)
 615                         rc = __feat_register_sp(fn, table[i].dependent_feat,
 616                                                     table[i].is_local,
 617                                                     table[i].is_mandatory,
 618                                                     &table[i].val, 1);
 619                 else
 620                         rc = __feat_register_nn(fn, table[i].dependent_feat,
 621                                                     table[i].is_mandatory,
 622                                                     table[i].val);
 623         return rc;
 624 }
 625
 626 /**
 627  * dccp_feat_finalise_settings  -  Finalise settings before starting negotiation
 628  * @dp: client or listening socket (settings will be inherited)
 629  * This is called after all registrations (socket initialisation, sysctls, and
 630  * sockopt calls), and before sending the first packet containing Change options
 631  * (ie. client-Request or server-Response), to ensure internal consistency.
 632  */
 633 int dccp_feat_finalise_settings(struct dccp_sock *dp)
 634 {
 635         struct list_head *fn = &dp->dccps_featneg;
 636         struct dccp_feat_entry *entry;
 637         int i = 2, ccids[2] = { -1, -1 };
 638
 639         /*
 640          * Propagating CCIDs:
 641          * 1) not useful to propagate CCID settings if this host advertises more
 642          *    than one CCID: the choice of CCID  may still change - if this is
 643          *    the client, or if this is the server and the client sends
 644          *    singleton CCID values.
 645          * 2) since is that propagate_ccid changes the list, we defer changing
 646          *    the sorted list until after the traversal.
 647          */
 648         list_for_each_entry(entry, fn, node)
 649                 if (entry->feat_num == DCCPF_CCID && entry->val.sp.len == 1)
 650                         ccids[entry->is_local] = entry->val.sp.vec[0];
 651         while (i--)
 652                 if (ccids[i] > 0 && dccp_feat_propagate_ccid(fn, ccids[i], i))
 653                         return -1;
 654         return 0;
 655 }
 656
 657 /**
 658  * dccp_feat_server_ccid_dependencies  -  Resolve CCID-dependent features
 659  * It is the server which resolves the dependencies once the CCID has been
 660  * fully negotiated. If no CCID has been negotiated, it uses the default CCID.
 661  */
 662 int dccp_feat_server_ccid_dependencies(struct dccp_request_sock *dreq)
 663 {
 664         struct list_head *fn = &dreq->dreq_featneg;
 665         struct dccp_feat_entry *entry;
 666         u8 is_local, ccid;
 667
 668         for (is_local = 0; is_local <= 1; is_local++) {
 669                 entry = dccp_feat_list_lookup(fn, DCCPF_CCID, is_local);
 670
 671                 if (entry != NULL && !entry->empty_confirm)
 672                         ccid = entry->val.sp.vec[0];
 673                 else
 674                         ccid = dccp_feat_default_value(DCCPF_CCID);
 675
 676                 if (dccp_feat_propagate_ccid(fn, ccid, is_local))
 677                         return -1;
 678         }
 679         return 0;
 680 }
 681
 682 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
 683 {
 684         struct dccp_sock *dp = dccp_sk(sk);
 685         struct dccp_minisock *dmsk = dccp_msk(sk);
 686         /* figure out if we are changing our CCID or the peer's */
 687         const int rx = type == DCCPO_CHANGE_R;
 688         const u8 ccid_nr = rx ? dmsk->dccpms_rx_ccid : dmsk->dccpms_tx_ccid;
 689         struct ccid *new_ccid;
 690
 691         /* Check if nothing is being changed. */
 692         if (ccid_nr == new_ccid_nr)
 693                 return 0;
 694
 695         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
 696         if (new_ccid == NULL)
 697                 return -ENOMEM;
 698
 699         if (rx) {
 700                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
 701                 dp->dccps_hc_rx_ccid = new_ccid;
 702                 dmsk->dccpms_rx_ccid = new_ccid_nr;
 703         } else {
 704                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
 705                 dp->dccps_hc_tx_ccid = new_ccid;
 706                 dmsk->dccpms_tx_ccid = new_ccid_nr;
 707         }
 708
 709         return 0;
 710 }
 711
 712 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 713 {
 714         dccp_feat_debug(type, feat, val);
 715
 716         switch (feat) {
 717         case DCCPF_CCID:
 718                 return dccp_feat_update_ccid(sk, type, val);
 719         default:
 720                 dccp_pr_debug("UNIMPLEMENTED: %s(%d, ...)\n",
 721                               dccp_feat_typename(type), feat);
 722                 break;
 723         }
 724         return 0;
 725 }
 726
 727 /* Select the first entry in @servlist that also occurs in @clilist (6.3.1) */
 728 static int dccp_feat_preflist_match(u8 *servlist, u8 slen, u8 *clilist, u8 clen)
 729 {
 730         u8 c, s;
 731
 732         for (s = 0; s < slen; s++)
 733                 for (c = 0; c < clen; c++)
 734                         if (servlist[s] == clilist[c])
 735                                 return servlist[s];
 736         return -1;
 737 }
 738
 739 /**
 740  * dccp_feat_prefer  -  Move preferred entry to the start of array
 741  * Reorder the @array_len elements in @array so that @preferred_value comes
 742  * first. Returns >0 to indicate that @preferred_value does occur in @array.
 743  */
 744 static u8 dccp_feat_prefer(u8 preferred_value, u8 *array, u8 array_len)
 745 {
 746         u8 i, does_occur = 0;
 747
 748         if (array != NULL) {
 749                 for (i = 0; i < array_len; i++)
 750                         if (array[i] == preferred_value) {
 751                                 array[i] = array[0];
 752                                 does_occur++;
 753                         }
 754                 if (does_occur)
 755                         array[0] = preferred_value;
 756         }
 757         return does_occur;
 758 }
 759
 760 /**
 761  * dccp_feat_reconcile  -  Reconcile SP preference lists
 762  *  @fval: SP list to reconcile into
 763  *  @arr: received SP preference list
 764  *  @len: length of @arr in bytes
 765  *  @is_server: whether this side is the server (and @fv is the server's list)
 766  *  @reorder: whether to reorder the list in @fv after reconciling with @arr
 767  * When successful, > 0 is returned and the reconciled list is in @fval.
 768  * A value of 0 means that negotiation failed (no shared entry).
 769  */
 770 static int dccp_feat_reconcile(dccp_feat_val *fv, u8 *arr, u8 len,
 771                                bool is_server, bool reorder)
 772 {
 773         int rc;
 774
 775         if (!fv->sp.vec || !arr) {
 776                 DCCP_CRIT("NULL feature value or array");
 777                 return 0;
 778         }
 779
 780         if (is_server)
 781                 rc = dccp_feat_preflist_match(fv->sp.vec, fv->sp.len, arr, len);
 782         else
 783                 rc = dccp_feat_preflist_match(arr, len, fv->sp.vec, fv->sp.len);
 784
 785         if (!reorder)
 786                 return rc;
 787         if (rc < 0)
 788                 return 0;
 789
 790         /*
 791          * Reorder list: used for activating features and in dccp_insert_fn_opt.
 792          */
 793         return dccp_feat_prefer(rc, fv->sp.vec, fv->sp.len);
 794 }
 795
 796 #ifdef __this_is_the_old_framework_and_will_be_removed_later_in_a_subsequent_patch
 797 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 798                                u8 *rpref, u8 rlen)
 799 {
 800         struct dccp_sock *dp = dccp_sk(sk);
 801         u8 *spref, slen, *res = NULL;
 802         int i, j, rc, agree = 1;
 803
 804         BUG_ON(rpref == NULL);
 805
 806         /* check if we are the black sheep */
 807         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 808                 spref = rpref;
 809                 slen  = rlen;
 810                 rpref = opt->dccpop_val;
 811                 rlen  = opt->dccpop_len;
 812         } else {
 813                 spref = opt->dccpop_val;
 814                 slen  = opt->dccpop_len;
 815         }
 816         /*
 817          * Now we have server preference list in spref and client preference in
 818          * rpref
 819          */
 820         BUG_ON(spref == NULL);
 821         BUG_ON(rpref == NULL);
 822
 823         /* FIXME sanity check vals */
 824
 825         /* Are values in any order?  XXX Lame "algorithm" here */
 826         for (i = 0; i < slen; i++) {
 827                 for (j = 0; j < rlen; j++) {
 828                         if (spref[i] == rpref[j]) {
 829                                 res = &spref[i];
 830                                 break;
 831                         }
 832                 }
 833                 if (res)
 834                         break;
 835         }
 836
 837         /* we didn't agree on anything */
 838         if (res == NULL) {
 839                 /* confirm previous value */
 840                 switch (opt->dccpop_feat) {
 841                 case DCCPF_CCID:
 842                         /* XXX did i get this right? =P */
 843                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 844                                 res = &dccp_msk(sk)->dccpms_tx_ccid;
 845                         else
 846                                 res = &dccp_msk(sk)->dccpms_rx_ccid;
 847                         break;
 848
 849                 default:
 850                         DCCP_BUG("Fell through, feat=%d", opt->dccpop_feat);
 851                         /* XXX implement res */
 852                         return -EFAULT;
 853                 }
 854
 855                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 856                 agree = 0; /* this is used for mandatory options... */
 857         }
 858
 859         /* need to put result and our preference list */
 860         rlen = 1 + opt->dccpop_len;
 861         rpref = kmalloc(rlen, GFP_ATOMIC);
 862         if (rpref == NULL)
 863                 return -ENOMEM;
 864
 865         *rpref = *res;
 866         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 867
 868         /* put it in the "confirm queue" */
 869         if (opt->dccpop_sc == NULL) {
 870                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 871                 if (opt->dccpop_sc == NULL) {
 872                         kfree(rpref);
 873                         return -ENOMEM;
 874                 }
 875         } else {
 876                 /* recycle the confirm slot */
 877                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 878                 kfree(opt->dccpop_sc->dccpoc_val);
 879                 dccp_pr_debug("recycling confirm slot\n");
 880         }
 881         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 882
 883         opt->dccpop_sc->dccpoc_val = rpref;
 884         opt->dccpop_sc->dccpoc_len = rlen;
 885
 886         /* update the option on our side [we are about to send the confirm] */
 887         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 888         if (rc) {
 889                 kfree(opt->dccpop_sc->dccpoc_val);
 890                 kfree(opt->dccpop_sc);
 891                 opt->dccpop_sc = NULL;
 892                 return rc;
 893         }
 894
 895         dccp_pr_debug("Will confirm %d\n", *rpref);
 896
 897         /* say we want to change to X but we just got a confirm X, suppress our
 898          * change
 899          */
 900         if (!opt->dccpop_conf) {
 901                 if (*opt->dccpop_val == *res)
 902                         opt->dccpop_conf = 1;
 903                 dccp_pr_debug("won't ask for change of same feature\n");
 904         }
 905
 906         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 907 }
 908
 909 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 910 {
 911         struct dccp_minisock *dmsk = dccp_msk(sk);
 912         struct dccp_opt_pend *opt;
 913         int rc = 1;
 914         u8 t;
 915
 916         /*
 917          * We received a CHANGE.  We gotta match it against our own preference
 918          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 919          * to compare our CHANGE_L list.
 920          */
 921         if (type == DCCPO_CHANGE_L)
 922                 t = DCCPO_CHANGE_R;
 923         else
 924                 t = DCCPO_CHANGE_L;
 925
 926         /* find our preference list for this feature */
 927         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
 928                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 929                         continue;
 930
 931                 /* find the winner from the two preference lists */
 932                 rc = dccp_feat_reconcile(sk, opt, val, len);
 933                 break;
 934         }
 935
 936         /* We didn't deal with the change.  This can happen if we have no
 937          * preference list for the feature.  In fact, it just shouldn't
 938          * happen---if we understand a feature, we should have a preference list
 939          * with at least the default value.
 940          */
 941         BUG_ON(rc == 1);
 942
 943         return rc;
 944 }
 945
 946 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 947 {
 948         struct dccp_opt_pend *opt;
 949         struct dccp_minisock *dmsk = dccp_msk(sk);
 950         u8 *copy;
 951         int rc;
 952
 953         /* NN features must be Change L (sec. 6.3.2) */
 954         if (type != DCCPO_CHANGE_L) {
 955                 dccp_pr_debug("received %s for NN feature %d\n",
 956                                 dccp_feat_typename(type), feature);
 957                 return -EFAULT;
 958         }
 959
 960         /* XXX sanity check opt val */
 961
 962         /* copy option so we can confirm it */
 963         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 964         if (opt == NULL)
 965                 return -ENOMEM;
 966
 967         copy = kmemdup(val, len, GFP_ATOMIC);
 968         if (copy == NULL) {
 969                 kfree(opt);
 970                 return -ENOMEM;
 971         }
 972
 973         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 974         opt->dccpop_feat = feature;
 975         opt->dccpop_val  = copy;
 976         opt->dccpop_len  = len;
 977
 978         /* change feature */
 979         rc = dccp_feat_update(sk, type, feature, *val);
 980         if (rc) {
 981                 kfree(opt->dccpop_val);
 982                 kfree(opt);
 983                 return rc;
 984         }
 985
 986         dccp_feat_debug(type, feature, *copy);
 987
 988         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
 989
 990         return 0;
 991 }
 992
 993 static void dccp_feat_empty_confirm(struct dccp_minisock *dmsk,
 994                                     u8 type, u8 feature)
 995 {
 996         /* XXX check if other confirms for that are queued and recycle slot */
 997         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 998
 999         if (opt == NULL) {
1000                 /* XXX what do we do?  Ignoring should be fine.  It's a change
1001                  * after all =P
1002                  */
1003                 return;
1004         }
1005
1006         switch (type) {
1007         case DCCPO_CHANGE_L:
1008                 opt->dccpop_type = DCCPO_CONFIRM_R;
1009                 break;
1010         case DCCPO_CHANGE_R:
1011                 opt->dccpop_type = DCCPO_CONFIRM_L;
1012                 break;
1013         default:
1014                 DCCP_WARN("invalid type %d\n", type);
1015                 kfree(opt);
1016                 return;
1017         }
1018         opt->dccpop_feat = feature;
1019         opt->dccpop_val  = NULL;
1020         opt->dccpop_len  = 0;
1021
1022         /* change feature */
1023         dccp_pr_debug("Empty %s(%d)\n", dccp_feat_typename(type), feature);
1024
1025         list_add_tail(&opt->dccpop_node, &dmsk->dccpms_conf);
1026 }
1027
1028 static void dccp_feat_flush_confirm(struct sock *sk)
1029 {
1030         struct dccp_minisock *dmsk = dccp_msk(sk);
1031         /* Check if there is anything to confirm in the first place */
1032         int yes = !list_empty(&dmsk->dccpms_conf);
1033
1034         if (!yes) {
1035                 struct dccp_opt_pend *opt;
1036
1037                 list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
1038                         if (opt->dccpop_conf) {
1039                                 yes = 1;
1040                                 break;
1041                         }
1042                 }
1043         }
1044
1045         if (!yes)
1046                 return;
1047
1048         /* OK there is something to confirm... */
1049         /* XXX check if packet is in flight?  Send delayed ack?? */
1050         if (sk->sk_state == DCCP_OPEN)
1051                 dccp_send_ack(sk);
1052 }
1053
1054 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
1055 {
1056         int rc;
1057
1058         /* Ignore Change requests other than during connection setup */
1059         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
1060                 return 0;
1061         dccp_feat_debug(type, feature, *val);
1062
1063         /* figure out if it's SP or NN feature */
1064         switch (feature) {
1065         /* deal with SP features */
1066         case DCCPF_CCID:
1067                 /* XXX Obsoleted by next patch
1068                 rc = dccp_feat_sp(sk, type, feature, val, len); */
1069                 break;
1070
1071         /* deal with NN features */
1072         case DCCPF_ACK_RATIO:
1073                 /* XXX Obsoleted by next patch
1074                 rc = dccp_feat_nn(sk, type, feature, val, len); */
1075                 break;
1076
1077         /* XXX implement other features */
1078         default:
1079                 dccp_pr_debug("UNIMPLEMENTED: not handling %s(%d, ...)\n",
1080                               dccp_feat_typename(type), feature);
1081                 rc = -EFAULT;
1082                 break;
1083         }
1084
1085         /* check if there were problems changing features */
1086         if (rc) {
1087                 /* If we don't agree on SP, we sent a confirm for old value.
1088                  * However we propagate rc to caller in case option was
1089                  * mandatory
1090                  */
1091                 if (rc != DCCP_FEAT_SP_NOAGREE)
1092                         dccp_feat_empty_confirm(dccp_msk(sk), type, feature);
1093         }
1094
1095         /* generate the confirm [if required] */
1096         dccp_feat_flush_confirm(sk);
1097
1098         return rc;
1099 }
1100
1101 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
1102 #endif  /* (later) */
1103
1104 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
1105                            u8 *val, u8 len)
1106 {
1107         u8 t;
1108         struct dccp_opt_pend *opt;
1109         struct dccp_minisock *dmsk = dccp_msk(sk);
1110         int found = 0;
1111         int all_confirmed = 1;
1112
1113         /* Ignore Confirm options other than during connection setup */
1114         if (sk->sk_state != DCCP_LISTEN && sk->sk_state != DCCP_REQUESTING)
1115                 return 0;
1116         dccp_feat_debug(type, feature, *val);
1117
1118         /* locate our change request */
1119         switch (type) {
1120         case DCCPO_CONFIRM_L: t = DCCPO_CHANGE_R; break;
1121         case DCCPO_CONFIRM_R: t = DCCPO_CHANGE_L; break;
1122         default:              DCCP_WARN("invalid type %d\n", type);
1123                               return 1;
1124
1125         }
1126         /* XXX sanity check feature value */
1127
1128         list_for_each_entry(opt, &dmsk->dccpms_pending, dccpop_node) {
1129                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
1130                     opt->dccpop_feat == feature) {
1131                         found = 1;
1132                         dccp_pr_debug("feature %d found\n", opt->dccpop_feat);
1133
1134                         /* XXX do sanity check */
1135
1136                         opt->dccpop_conf = 1;
1137
1138                         /* We got a confirmation---change the option */
1139                         dccp_feat_update(sk, opt->dccpop_type,
1140                                          opt->dccpop_feat, *val);
1141
1142                         /* XXX check the return value of dccp_feat_update */
1143                         break;
1144                 }
1145
1146                 if (!opt->dccpop_conf)
1147                         all_confirmed = 0;
1148         }
1149
1150         if (!found)
1151                 dccp_pr_debug("%s(%d, ...) never requested\n",
1152                               dccp_feat_typename(type), feature);
1153         return 0;
1154 }
1155
1156 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
1157
1158 void dccp_feat_clean(struct dccp_minisock *dmsk)
1159 {
1160         struct dccp_opt_pend *opt, *next;
1161
1162         list_for_each_entry_safe(opt, next, &dmsk->dccpms_pending,
1163                                  dccpop_node) {
1164                 BUG_ON(opt->dccpop_val == NULL);
1165                 kfree(opt->dccpop_val);
1166
1167                 if (opt->dccpop_sc != NULL) {
1168                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
1169                         kfree(opt->dccpop_sc->dccpoc_val);
1170                         kfree(opt->dccpop_sc);
1171                 }
1172
1173                 kfree(opt);
1174         }
1175         INIT_LIST_HEAD(&dmsk->dccpms_pending);
1176
1177         list_for_each_entry_safe(opt, next, &dmsk->dccpms_conf, dccpop_node) {
1178                 BUG_ON(opt == NULL);
1179                 if (opt->dccpop_val != NULL)
1180                         kfree(opt->dccpop_val);
1181                 kfree(opt);
1182         }
1183         INIT_LIST_HEAD(&dmsk->dccpms_conf);
1184 }
1185
1186 EXPORT_SYMBOL_GPL(dccp_feat_clean);
1187
1188 /* this is to be called only when a listening sock creates its child.  It is
1189  * assumed by the function---the confirm is not duplicated, but rather it is
1190  * "passed on".
1191  */
1192 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
1193 {
1194         struct dccp_minisock *olddmsk = dccp_msk(oldsk);
1195         struct dccp_minisock *newdmsk = dccp_msk(newsk);
1196         struct dccp_opt_pend *opt;
1197         int rc = 0;
1198
1199         INIT_LIST_HEAD(&newdmsk->dccpms_pending);
1200         INIT_LIST_HEAD(&newdmsk->dccpms_conf);
1201
1202         list_for_each_entry(opt, &olddmsk->dccpms_pending, dccpop_node) {
1203                 struct dccp_opt_pend *newopt;
1204                 /* copy the value of the option */
1205                 u8 *val = kmemdup(opt->dccpop_val, opt->dccpop_len, GFP_ATOMIC);
1206
1207                 if (val == NULL)
1208                         goto out_clean;
1209
1210                 newopt = kmemdup(opt, sizeof(*newopt), GFP_ATOMIC);
1211                 if (newopt == NULL) {
1212                         kfree(val);
1213                         goto out_clean;
1214                 }
1215
1216                 /* insert the option */
1217                 newopt->dccpop_val = val;
1218                 list_add_tail(&newopt->dccpop_node, &newdmsk->dccpms_pending);
1219
1220                 /* XXX what happens with backlogs and multiple connections at
1221                  * once...
1222                  */
1223                 /* the master socket no longer needs to worry about confirms */
1224                 opt->dccpop_sc = NULL; /* it's not a memleak---new socket has it */
1225
1226                 /* reset state for a new socket */
1227                 opt->dccpop_conf = 0;
1228         }
1229
1230         /* XXX not doing anything about the conf queue */
1231
1232 out:
1233         return rc;
1234
1235 out_clean:
1236         dccp_feat_clean(newdmsk);
1237         rc = -ENOMEM;
1238         goto out;
1239 }
1240
1241 EXPORT_SYMBOL_GPL(dccp_feat_clone);
1242
1243 /**
1244  * dccp_feat_change_recv  -  Process incoming ChangeL/R options
1245  * @fn: feature-negotiation list to update
1246  * @is_mandatory: whether the Change was preceded by a Mandatory option
1247  * @opt: %DCCPO_CHANGE_L or %DCCPO_CHANGE_R
1248  * @feat: one of %dccp_feature_numbers
1249  * @val: NN value or SP value/preference list
1250  * @len: length of @val in bytes
1251  * @server: whether this node is the server (1) or the client (0)
1252  */
1253 static u8 dccp_feat_change_recv(struct list_head *fn, u8 is_mandatory, u8 opt,
1254                                 u8 feat, u8 *val, u8 len, const bool server)
1255 {
1256         u8 defval, type = dccp_feat_type(feat);
1257         const bool local = (opt == DCCPO_CHANGE_R);
1258         struct dccp_feat_entry *entry;
1259         dccp_feat_val fval;
1260
1261         if (len == 0 || type == FEAT_UNKNOWN)           /* 6.1 and 6.6.8 */
1262                 goto unknown_feature_or_value;
1263
1264         /*
1265          *      Negotiation of NN features: Change R is invalid, so there is no
1266          *      simultaneous negotiation; hence we do not look up in the list.
1267          */
1268         if (type == FEAT_NN) {
1269                 if (local || len > sizeof(fval.nn))
1270                         goto unknown_feature_or_value;
1271
1272                 /* 6.3.2: "The feature remote MUST accept any valid value..." */
1273                 fval.nn = dccp_decode_value_var(val, len);
1274                 if (!dccp_feat_is_valid_nn_val(feat, fval.nn))
1275                         goto unknown_feature_or_value;
1276
1277                 return dccp_feat_push_confirm(fn, feat, local, &fval);
1278         }
1279
1280         /*
1281          *      Unidirectional/simultaneous negotiation of SP features (6.3.1)
1282          */
1283         entry = dccp_feat_list_lookup(fn, feat, local);
1284         if (entry == NULL) {
1285                 /*
1286                  * No particular preferences have been registered. We deal with
1287                  * this situation by assuming that all valid values are equally
1288                  * acceptable, and apply the following checks:
1289                  * - if the peer's list is a singleton, we accept a valid value;
1290                  * - if we are the server, we first try to see if the peer (the
1291                  *   client) advertises the default value. If yes, we use it,
1292                  *   otherwise we accept the preferred value;
1293                  * - else if we are the client, we use the first list element.
1294                  */
1295                 if (dccp_feat_clone_sp_val(&fval, val, 1))
1296                         return DCCP_RESET_CODE_TOO_BUSY;
1297
1298                 if (len > 1 && server) {
1299                         defval = dccp_feat_default_value(feat);
1300                         if (dccp_feat_preflist_match(&defval, 1, val, len) > -1)
1301                                 fval.sp.vec[0] = defval;
1302                 } else if (!dccp_feat_is_valid_sp_val(feat, fval.sp.vec[0])) {
1303                         kfree(fval.sp.vec);
1304                         goto unknown_feature_or_value;
1305                 }
1306
1307                 /* Treat unsupported CCIDs like invalid values */
1308                 if (feat == DCCPF_CCID && !ccid_support_check(fval.sp.vec, 1)) {
1309                         kfree(fval.sp.vec);
1310                         goto not_valid_or_not_known;
1311                 }
1312
1313                 return dccp_feat_push_confirm(fn, feat, local, &fval);
1314
1315         } else if (entry->state == FEAT_UNSTABLE) {     /* 6.6.2 */
1316                 return 0;
1317         }
1318
1319         if (dccp_feat_reconcile(&entry->val, val, len, server, true)) {
1320                 entry->empty_confirm = 0;
1321         } else if (is_mandatory) {
1322                 return DCCP_RESET_CODE_MANDATORY_ERROR;
1323         } else if (entry->state == FEAT_INITIALISING) {
1324                 /*
1325                  * Failed simultaneous negotiation (server only): try to `save'
1326                  * the connection by checking whether entry contains the default
1327                  * value for @feat. If yes, send an empty Confirm to signal that
1328                  * the received Change was not understood - which implies using
1329                  * the default value.
1330                  * If this also fails, we use Reset as the last resort.
1331                  */
1332                 WARN_ON(!server);
1333                 defval = dccp_feat_default_value(feat);
1334                 if (!dccp_feat_reconcile(&entry->val, &defval, 1, server, true))
1335                         return DCCP_RESET_CODE_OPTION_ERROR;
1336                 entry->empty_confirm = 1;
1337         }
1338         entry->needs_confirm   = 1;
1339         entry->needs_mandatory = 0;
1340         entry->state           = FEAT_STABLE;
1341         return 0;
1342
1343 unknown_feature_or_value:
1344         if (!is_mandatory)
1345                 return dccp_push_empty_confirm(fn, feat, local);
1346
1347 not_valid_or_not_known:
1348         return is_mandatory ? DCCP_RESET_CODE_MANDATORY_ERROR
1349                             : DCCP_RESET_CODE_OPTION_ERROR;
1350 }
1351
1352 /**
1353  * dccp_feat_parse_options  -  Process Feature-Negotiation Options
1354  * @sk: for general use and used by the client during connection setup
1355  * @dreq: used by the server during connection setup
1356  * @mandatory: whether @opt was preceded by a Mandatory option
1357  * @opt: %DCCPO_CHANGE_L | %DCCPO_CHANGE_R | %DCCPO_CONFIRM_L | %DCCPO_CONFIRM_R
1358  * @feat: one of %dccp_feature_numbers
1359  * @val: value contents of @opt
1360  * @len: length of @val in bytes
1361  * Returns 0 on success, a Reset code for ending the connection otherwise.
1362  */
1363 int dccp_feat_parse_options(struct sock *sk, struct dccp_request_sock *dreq,
1364                             u8 mandatory, u8 opt, u8 feat, u8 *val, u8 len)
1365 {
1366         struct dccp_sock *dp = dccp_sk(sk);
1367         struct list_head *fn = dreq ? &dreq->dreq_featneg : &dp->dccps_featneg;
1368         bool server = false;
1369
1370         switch (sk->sk_state) {
1371         /*
1372          *      Negotiation during connection setup
1373          */
1374         case DCCP_LISTEN:
1375                 server = true;                  /* fall through */
1376         case DCCP_REQUESTING:
1377                 switch (opt) {
1378                 case DCCPO_CHANGE_L:
1379                 case DCCPO_CHANGE_R:
1380                         return dccp_feat_change_recv(fn, mandatory, opt, feat,
1381                                                      val, len, server);
1382                 }
1383         }
1384         return 0;       /* ignore FN options in all other states */
1385 }
1386
1387 int dccp_feat_init(struct sock *sk)
1388 {
1389         struct dccp_sock *dp = dccp_sk(sk);
1390         struct dccp_minisock *dmsk = dccp_msk(sk);
1391         int rc;
1392
1393         INIT_LIST_HEAD(&dmsk->dccpms_pending);  /* XXX no longer used */
1394         INIT_LIST_HEAD(&dmsk->dccpms_conf);     /* XXX no longer used */
1395
1396         /* CCID L */
1397         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 1, 0,
1398                                 &dmsk->dccpms_tx_ccid, 1);
1399         if (rc)
1400                 goto out;
1401
1402         /* CCID R */
1403         rc = __feat_register_sp(&dp->dccps_featneg, DCCPF_CCID, 0, 0,
1404                                 &dmsk->dccpms_rx_ccid, 1);
1405         if (rc)
1406                 goto out;
1407
1408         /* Ack ratio */
1409         rc = __feat_register_nn(&dp->dccps_featneg, DCCPF_ACK_RATIO, 0,
1410                                 dp->dccps_l_ack_ratio);
1411 out:
1412         return rc;
1413 }
1414
1415 EXPORT_SYMBOL_GPL(dccp_feat_init);
1416
1417 #ifdef CONFIG_IP_DCCP_DEBUG
1418 const char *dccp_feat_typename(const u8 type)
1419 {
1420         switch(type) {
1421         case DCCPO_CHANGE_L:  return("ChangeL");
1422         case DCCPO_CONFIRM_L: return("ConfirmL");
1423         case DCCPO_CHANGE_R:  return("ChangeR");
1424         case DCCPO_CONFIRM_R: return("ConfirmR");
1425         /* the following case must not appear in feature negotation  */
1426         default:              dccp_pr_debug("unknown type %d [BUG!]\n", type);
1427         }
1428         return NULL;
1429 }
1430
1431 EXPORT_SYMBOL_GPL(dccp_feat_typename);
1432
1433 const char *dccp_feat_name(const u8 feat)
1434 {
1435         static const char *feature_names[] = {
1436                 [DCCPF_RESERVED]        = "Reserved",
1437                 [DCCPF_CCID]            = "CCID",
1438                 [DCCPF_SHORT_SEQNOS]    = "Allow Short Seqnos",
1439                 [DCCPF_SEQUENCE_WINDOW] = "Sequence Window",
1440                 [DCCPF_ECN_INCAPABLE]   = "ECN Incapable",
1441                 [DCCPF_ACK_RATIO]       = "Ack Ratio",
1442                 [DCCPF_SEND_ACK_VECTOR] = "Send ACK Vector",
1443                 [DCCPF_SEND_NDP_COUNT]  = "Send NDP Count",
1444                 [DCCPF_MIN_CSUM_COVER]  = "Min. Csum Coverage",
1445                 [DCCPF_DATA_CHECKSUM]   = "Send Data Checksum",
1446         };
1447         if (feat > DCCPF_DATA_CHECKSUM && feat < DCCPF_MIN_CCID_SPECIFIC)
1448                 return feature_names[DCCPF_RESERVED];
1449
1450         if (feat ==  DCCPF_SEND_LEV_RATE)
1451                 return "Send Loss Event Rate";
1452         if (feat >= DCCPF_MIN_CCID_SPECIFIC)
1453                 return "CCID-specific";
1454
1455         return feature_names[feat];
1456 }
1457
1458 EXPORT_SYMBOL_GPL(dccp_feat_name);
1459 #endif /* CONFIG_IP_DCCP_DEBUG */