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