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   1 /*
   2  *  net/dccp/feat.c
   3  *
   4  *  An implementation of the DCCP protocol
   5  *  Andrea Bittau <a.bittau@cs.ucl.ac.uk>
   6  *
   7  *      This program is free software; you can redistribute it and/or
   8  *      modify it under the terms of the GNU General Public License
   9  *      as published by the Free Software Foundation; either version
  10  *      2 of the License, or (at your option) any later version.
  11  */
  12
  13 #include <linux/config.h>
  14 #include <linux/module.h>
  15
  16 #include "dccp.h"
  17 #include "ccid.h"
  18 #include "feat.h"
  19
  20 #define DCCP_FEAT_SP_NOAGREE (-123)
  21
  22 int dccp_feat_change(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len,
  23                      gfp_t gfp)
  24 {
  25         struct dccp_sock *dp = dccp_sk(sk);
  26         struct dccp_opt_pend *opt;
  27
  28         dccp_pr_debug("feat change type=%d feat=%d\n", type, feature);
  29
  30         /* XXX sanity check feat change request */
  31
  32         /* check if that feature is already being negotiated */
  33         list_for_each_entry(opt, &dp->dccps_options.dccpo_pending,
  34                             dccpop_node) {
  35                 /* ok we found a negotiation for this option already */
  36                 if (opt->dccpop_feat == feature && opt->dccpop_type == type) {
  37                         dccp_pr_debug("Replacing old\n");
  38                         /* replace */
  39                         BUG_ON(opt->dccpop_val == NULL);
  40                         kfree(opt->dccpop_val);
  41                         opt->dccpop_val  = val;
  42                         opt->dccpop_len  = len;
  43                         opt->dccpop_conf = 0;
  44                         return 0;
  45                 }
  46         }
  47
  48         /* negotiation for a new feature */
  49         opt = kmalloc(sizeof(*opt), gfp);
  50         if (opt == NULL)
  51                 return -ENOMEM;
  52
  53         opt->dccpop_type = type;
  54         opt->dccpop_feat = feature;
  55         opt->dccpop_len  = len;
  56         opt->dccpop_val  = val;
  57         opt->dccpop_conf = 0;
  58         opt->dccpop_sc   = NULL;
  59
  60         BUG_ON(opt->dccpop_val == NULL);
  61
  62         list_add_tail(&opt->dccpop_node, &dp->dccps_options.dccpo_pending);
  63         return 0;
  64 }
  65
  66 EXPORT_SYMBOL_GPL(dccp_feat_change);
  67
  68 static int dccp_feat_update_ccid(struct sock *sk, u8 type, u8 new_ccid_nr)
  69 {
  70         struct dccp_sock *dp = dccp_sk(sk);
  71         /* figure out if we are changing our CCID or the peer's */
  72         const int rx = type == DCCPO_CHANGE_R;
  73         const u8 ccid_nr = rx ? dp->dccps_options.dccpo_rx_ccid :
  74                                 dp->dccps_options.dccpo_tx_ccid;
  75         struct ccid *new_ccid;
  76
  77         /* Check if nothing is being changed. */
  78         if (ccid_nr == new_ccid_nr)
  79                 return 0;
  80
  81         new_ccid = ccid_new(new_ccid_nr, sk, rx, GFP_ATOMIC);
  82         if (new_ccid == NULL)
  83                 return -ENOMEM;
  84
  85         if (rx) {
  86                 ccid_hc_rx_delete(dp->dccps_hc_rx_ccid, sk);
  87                 dp->dccps_hc_rx_ccid = new_ccid;
  88                 dp->dccps_options.dccpo_rx_ccid = new_ccid_nr;
  89         } else {
  90                 ccid_hc_tx_delete(dp->dccps_hc_tx_ccid, sk);
  91                 dp->dccps_hc_tx_ccid = new_ccid;
  92                 dp->dccps_options.dccpo_tx_ccid = new_ccid_nr;
  93         }
  94
  95         return 0;
  96 }
  97
  98 /* XXX taking only u8 vals */
  99 static int dccp_feat_update(struct sock *sk, u8 type, u8 feat, u8 val)
 100 {
 101         dccp_pr_debug("changing [%d] feat %d to %d\n", type, feat, val);
 102
 103         switch (feat) {
 104         case DCCPF_CCID:
 105                 return dccp_feat_update_ccid(sk, type, val);
 106         default:
 107                 dccp_pr_debug("IMPLEMENT changing [%d] feat %d to %d\n",
 108                               type, feat, val);
 109                 break;
 110         }
 111         return 0;
 112 }
 113
 114 static int dccp_feat_reconcile(struct sock *sk, struct dccp_opt_pend *opt,
 115                                u8 *rpref, u8 rlen)
 116 {
 117         struct dccp_sock *dp = dccp_sk(sk);
 118         u8 *spref, slen, *res = NULL;
 119         int i, j, rc, agree = 1;
 120
 121         BUG_ON(rpref == NULL);
 122
 123         /* check if we are the black sheep */
 124         if (dp->dccps_role == DCCP_ROLE_CLIENT) {
 125                 spref = rpref;
 126                 slen  = rlen;
 127                 rpref = opt->dccpop_val;
 128                 rlen  = opt->dccpop_len;
 129         } else {
 130                 spref = opt->dccpop_val;
 131                 slen  = opt->dccpop_len;
 132         }
 133         /*
 134          * Now we have server preference list in spref and client preference in
 135          * rpref
 136          */
 137         BUG_ON(spref == NULL);
 138         BUG_ON(rpref == NULL);
 139
 140         /* FIXME sanity check vals */
 141
 142         /* Are values in any order?  XXX Lame "algorithm" here */
 143         /* XXX assume values are 1 byte */
 144         for (i = 0; i < slen; i++) {
 145                 for (j = 0; j < rlen; j++) {
 146                         if (spref[i] == rpref[j]) {
 147                                 res = &spref[i];
 148                                 break;
 149                         }
 150                 }
 151                 if (res)
 152                         break;
 153         }
 154
 155         /* we didn't agree on anything */
 156         if (res == NULL) {
 157                 /* confirm previous value */
 158                 switch (opt->dccpop_feat) {
 159                 case DCCPF_CCID:
 160                         /* XXX did i get this right? =P */
 161                         if (opt->dccpop_type == DCCPO_CHANGE_L)
 162                                 res = &dp->dccps_options.dccpo_tx_ccid;
 163                         else
 164                                 res = &dp->dccps_options.dccpo_rx_ccid;
 165                         break;
 166
 167                 default:
 168                         WARN_ON(1); /* XXX implement res */
 169                         return -EFAULT;
 170                 }
 171
 172                 dccp_pr_debug("Don't agree... reconfirming %d\n", *res);
 173                 agree = 0; /* this is used for mandatory options... */
 174         }
 175
 176         /* need to put result and our preference list */
 177         /* XXX assume 1 byte vals */
 178         rlen = 1 + opt->dccpop_len;
 179         rpref = kmalloc(rlen, GFP_ATOMIC);
 180         if (rpref == NULL)
 181                 return -ENOMEM;
 182
 183         *rpref = *res;
 184         memcpy(&rpref[1], opt->dccpop_val, opt->dccpop_len);
 185
 186         /* put it in the "confirm queue" */
 187         if (opt->dccpop_sc == NULL) {
 188                 opt->dccpop_sc = kmalloc(sizeof(*opt->dccpop_sc), GFP_ATOMIC);
 189                 if (opt->dccpop_sc == NULL) {
 190                         kfree(rpref);
 191                         return -ENOMEM;
 192                 }
 193         } else {
 194                 /* recycle the confirm slot */
 195                 BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 196                 kfree(opt->dccpop_sc->dccpoc_val);
 197                 dccp_pr_debug("recycling confirm slot\n");
 198         }
 199         memset(opt->dccpop_sc, 0, sizeof(*opt->dccpop_sc));
 200
 201         opt->dccpop_sc->dccpoc_val = rpref;
 202         opt->dccpop_sc->dccpoc_len = rlen;
 203
 204         /* update the option on our side [we are about to send the confirm] */
 205         rc = dccp_feat_update(sk, opt->dccpop_type, opt->dccpop_feat, *res);
 206         if (rc) {
 207                 kfree(opt->dccpop_sc->dccpoc_val);
 208                 kfree(opt->dccpop_sc);
 209                 opt->dccpop_sc = 0;
 210                 return rc;
 211         }
 212
 213         dccp_pr_debug("Will confirm %d\n", *rpref);
 214
 215         /* say we want to change to X but we just got a confirm X, suppress our
 216          * change
 217          */
 218         if (!opt->dccpop_conf) {
 219                 if (*opt->dccpop_val == *res)
 220                         opt->dccpop_conf = 1;
 221                 dccp_pr_debug("won't ask for change of same feature\n");
 222         }
 223
 224         return agree ? 0 : DCCP_FEAT_SP_NOAGREE; /* used for mandatory opts */
 225 }
 226
 227 static int dccp_feat_sp(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 228 {
 229         struct dccp_sock *dp = dccp_sk(sk);
 230         struct dccp_opt_pend *opt;
 231         int rc = 1;
 232         u8 t;
 233
 234         /*
 235          * We received a CHANGE.  We gotta match it against our own preference
 236          * list.  If we got a CHANGE_R it means it's a change for us, so we need
 237          * to compare our CHANGE_L list.
 238          */
 239         if (type == DCCPO_CHANGE_L)
 240                 t = DCCPO_CHANGE_R;
 241         else
 242                 t = DCCPO_CHANGE_L;
 243
 244         /* find our preference list for this feature */
 245         list_for_each_entry(opt, &dp->dccps_options.dccpo_pending,
 246                             dccpop_node) {
 247                 if (opt->dccpop_type != t || opt->dccpop_feat != feature)
 248                         continue;
 249
 250                 /* find the winner from the two preference lists */
 251                 rc = dccp_feat_reconcile(sk, opt, val, len);
 252                 break;
 253         }
 254
 255         /* We didn't deal with the change.  This can happen if we have no
 256          * preference list for the feature.  In fact, it just shouldn't
 257          * happen---if we understand a feature, we should have a preference list
 258          * with at least the default value.
 259          */
 260         BUG_ON(rc == 1);
 261
 262         return rc;
 263 }
 264
 265 static int dccp_feat_nn(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 266 {
 267         struct dccp_opt_pend *opt;
 268         struct dccp_sock *dp = dccp_sk(sk);
 269         u8 *copy;
 270         int rc;
 271
 272         /* NN features must be change L */
 273         if (type == DCCPO_CHANGE_R) {
 274                 dccp_pr_debug("received CHANGE_R %d for NN feat %d\n",
 275                               type, feature);
 276                 return -EFAULT;
 277         }
 278
 279         /* XXX sanity check opt val */
 280
 281         /* copy option so we can confirm it */
 282         opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 283         if (opt == NULL)
 284                 return -ENOMEM;
 285
 286         copy = kmalloc(len, GFP_ATOMIC);
 287         if (copy == NULL) {
 288                 kfree(opt);
 289                 return -ENOMEM;
 290         }
 291         memcpy(copy, val, len);
 292
 293         opt->dccpop_type = DCCPO_CONFIRM_R; /* NN can only confirm R */
 294         opt->dccpop_feat = feature;
 295         opt->dccpop_val  = copy;
 296         opt->dccpop_len  = len;
 297
 298         /* change feature */
 299         rc = dccp_feat_update(sk, type, feature, *val);
 300         if (rc) {
 301                 kfree(opt->dccpop_val);
 302                 kfree(opt);
 303                 return rc;
 304         }
 305
 306         dccp_pr_debug("Confirming NN feature %d (val=%d)\n", feature, *copy);
 307         list_add_tail(&opt->dccpop_node, &dp->dccps_options.dccpo_conf);
 308
 309         return 0;
 310 }
 311
 312 static void dccp_feat_empty_confirm(struct sock *sk, u8 type, u8 feature)
 313 {
 314         struct dccp_sock *dp = dccp_sk(sk);
 315         /* XXX check if other confirms for that are queued and recycle slot */
 316         struct dccp_opt_pend *opt = kzalloc(sizeof(*opt), GFP_ATOMIC);
 317
 318         if (opt == NULL) {
 319                 /* XXX what do we do?  Ignoring should be fine.  It's a change
 320                  * after all =P
 321                  */
 322                 return;
 323         }
 324
 325         opt->dccpop_type = type == DCCPO_CHANGE_L ? DCCPO_CONFIRM_R :
 326                                                     DCCPO_CONFIRM_L;
 327         opt->dccpop_feat = feature;
 328         opt->dccpop_val  = 0;
 329         opt->dccpop_len  = 0;
 330
 331         /* change feature */
 332         dccp_pr_debug("Empty confirm feature %d type %d\n", feature, type);
 333         list_add_tail(&opt->dccpop_node, &dp->dccps_options.dccpo_conf);
 334 }
 335
 336 static void dccp_feat_flush_confirm(struct sock *sk)
 337 {
 338         struct dccp_sock *dp = dccp_sk(sk);
 339         /* Check if there is anything to confirm in the first place */
 340         int yes = !list_empty(&dp->dccps_options.dccpo_conf);
 341
 342         if (!yes) {
 343                 struct dccp_opt_pend *opt;
 344
 345                 list_for_each_entry(opt, &dp->dccps_options.dccpo_pending,
 346                                     dccpop_node) {
 347                         if (opt->dccpop_conf) {
 348                                 yes = 1;
 349                                 break;
 350                         }
 351                 }
 352         }
 353
 354         if (!yes)
 355                 return;
 356
 357         /* OK there is something to confirm... */
 358         /* XXX check if packet is in flight?  Send delayed ack?? */
 359         if (sk->sk_state == DCCP_OPEN)
 360                 dccp_send_ack(sk);
 361 }
 362
 363 int dccp_feat_change_recv(struct sock *sk, u8 type, u8 feature, u8 *val, u8 len)
 364 {
 365         int rc;
 366
 367         dccp_pr_debug("got feat change type=%d feat=%d\n", type, feature);
 368
 369         /* figure out if it's SP or NN feature */
 370         switch (feature) {
 371         /* deal with SP features */
 372         case DCCPF_CCID:
 373                 rc = dccp_feat_sp(sk, type, feature, val, len);
 374                 break;
 375
 376         /* deal with NN features */
 377         case DCCPF_ACK_RATIO:
 378                 rc = dccp_feat_nn(sk, type, feature, val, len);
 379                 break;
 380
 381         /* XXX implement other features */
 382         default:
 383                 rc = -EFAULT;
 384                 break;
 385         }
 386
 387         /* check if there were problems changing features */
 388         if (rc) {
 389                 /* If we don't agree on SP, we sent a confirm for old value.
 390                  * However we propagate rc to caller in case option was
 391                  * mandatory
 392                  */
 393                 if (rc != DCCP_FEAT_SP_NOAGREE)
 394                         dccp_feat_empty_confirm(sk, type, feature);
 395         }
 396
 397         /* generate the confirm [if required] */
 398         dccp_feat_flush_confirm(sk);
 399
 400         return rc;
 401 }
 402
 403 EXPORT_SYMBOL_GPL(dccp_feat_change_recv);
 404
 405 int dccp_feat_confirm_recv(struct sock *sk, u8 type, u8 feature,
 406                            u8 *val, u8 len)
 407 {
 408         u8 t;
 409         struct dccp_opt_pend *opt;
 410         struct dccp_sock *dp = dccp_sk(sk);
 411         int rc = 1;
 412         int all_confirmed = 1;
 413
 414         dccp_pr_debug("got feat confirm type=%d feat=%d\n", type, feature);
 415
 416         /* XXX sanity check type & feat */
 417
 418         /* locate our change request */
 419         t = type == DCCPO_CONFIRM_L ? DCCPO_CHANGE_R : DCCPO_CHANGE_L;
 420
 421         list_for_each_entry(opt, &dp->dccps_options.dccpo_pending,
 422                             dccpop_node) {
 423                 if (!opt->dccpop_conf && opt->dccpop_type == t &&
 424                     opt->dccpop_feat == feature) {
 425                         /* we found it */
 426                         /* XXX do sanity check */
 427
 428                         opt->dccpop_conf = 1;
 429
 430                         /* We got a confirmation---change the option */
 431                         dccp_feat_update(sk, opt->dccpop_type,
 432                                          opt->dccpop_feat, *val);
 433
 434                         dccp_pr_debug("feat %d type %d confirmed %d\n",
 435                                       feature, type, *val);
 436                         rc = 0;
 437                         break;
 438                 }
 439
 440                 if (!opt->dccpop_conf)
 441                         all_confirmed = 0;
 442         }
 443
 444         /* fix re-transmit timer */
 445         /* XXX gotta make sure that no option negotiation occurs during
 446          * connection shutdown.  Consider that the CLOSEREQ is sent and timer is
 447          * on.  if all options are confirmed it might kill timer which should
 448          * remain alive until close is received.
 449          */
 450         if (all_confirmed) {
 451                 dccp_pr_debug("clear feat negotiation timer %p\n", sk);
 452                 inet_csk_clear_xmit_timer(sk, ICSK_TIME_RETRANS);
 453         }
 454
 455         if (rc)
 456                 dccp_pr_debug("feat %d type %d never requested\n",
 457                               feature, type);
 458         return 0;
 459 }
 460
 461 EXPORT_SYMBOL_GPL(dccp_feat_confirm_recv);
 462
 463 void dccp_feat_clean(struct sock *sk)
 464 {
 465         struct dccp_sock *dp = dccp_sk(sk);
 466         struct dccp_opt_pend *opt, *next;
 467
 468         list_for_each_entry_safe(opt, next, &dp->dccps_options.dccpo_pending,
 469                                  dccpop_node) {
 470                 BUG_ON(opt->dccpop_val == NULL);
 471                 kfree(opt->dccpop_val);
 472
 473                 if (opt->dccpop_sc != NULL) {
 474                         BUG_ON(opt->dccpop_sc->dccpoc_val == NULL);
 475                         kfree(opt->dccpop_sc->dccpoc_val);
 476                         kfree(opt->dccpop_sc);
 477                 }
 478
 479                 kfree(opt);
 480         }
 481         INIT_LIST_HEAD(&dp->dccps_options.dccpo_pending);
 482
 483         list_for_each_entry_safe(opt, next, &dp->dccps_options.dccpo_conf,
 484                                  dccpop_node) {
 485                 BUG_ON(opt == NULL);
 486                 if (opt->dccpop_val != NULL)
 487                         kfree(opt->dccpop_val);
 488                 kfree(opt);
 489         }
 490         INIT_LIST_HEAD(&dp->dccps_options.dccpo_conf);
 491 }
 492
 493 EXPORT_SYMBOL_GPL(dccp_feat_clean);
 494
 495 /* this is to be called only when a listening sock creates its child.  It is
 496  * assumed by the function---the confirm is not duplicated, but rather it is
 497  * "passed on".
 498  */
 499 int dccp_feat_clone(struct sock *oldsk, struct sock *newsk)
 500 {
 501         struct dccp_sock *olddp = dccp_sk(oldsk);
 502         struct dccp_sock *newdp = dccp_sk(newsk);
 503         struct dccp_opt_pend *opt;
 504         int rc = 0;
 505
 506         INIT_LIST_HEAD(&newdp->dccps_options.dccpo_pending);
 507         INIT_LIST_HEAD(&newdp->dccps_options.dccpo_conf);
 508
 509         list_for_each_entry(opt, &olddp->dccps_options.dccpo_pending,
 510                             dccpop_node) {
 511                 struct dccp_opt_pend *newopt;
 512                 /* copy the value of the option */
 513                 u8 *val = kmalloc(opt->dccpop_len, GFP_ATOMIC);
 514
 515                 if (val == NULL)
 516                         goto out_clean;
 517                 memcpy(val, opt->dccpop_val, opt->dccpop_len);
 518
 519                 newopt = kmalloc(sizeof(*newopt), GFP_ATOMIC);
 520                 if (newopt == NULL) {
 521                         kfree(val);
 522                         goto out_clean;
 523                 }
 524
 525                 /* insert the option */
 526                 memcpy(newopt, opt, sizeof(*newopt));
 527                 newopt->dccpop_val = val;
 528                 list_add_tail(&newopt->dccpop_node,
 529                               &newdp->dccps_options.dccpo_pending);
 530
 531                 /* XXX what happens with backlogs and multiple connections at
 532                  * once...
 533                  */
 534                 /* the master socket no longer needs to worry about confirms */
 535                 opt->dccpop_sc = 0; /* it's not a memleak---new socket has it */
 536
 537                 /* reset state for a new socket */
 538                 opt->dccpop_conf = 0;
 539         }
 540
 541         /* XXX not doing anything about the conf queue */
 542
 543 out:
 544         return rc;
 545
 546 out_clean:
 547         dccp_feat_clean(newsk);
 548         rc = -ENOMEM;
 549         goto out;
 550 }
 551
 552 EXPORT_SYMBOL_GPL(dccp_feat_clone);
 553
 554 static int __dccp_feat_init(struct sock *sk, u8 type, u8 feat, u8 *val, u8 len)
 555 {
 556         int rc = -ENOMEM;
 557         u8 *copy = kmalloc(len, GFP_KERNEL);
 558
 559         if (copy != NULL) {
 560                 memcpy(copy, val, len);
 561                 rc = dccp_feat_change(sk, type, feat, copy, len, GFP_KERNEL);
 562                 if (rc)
 563                         kfree(copy);
 564         }
 565         return rc;
 566 }
 567
 568 int dccp_feat_init(struct sock *sk)
 569 {
 570         struct dccp_sock *dp = dccp_sk(sk);
 571         int rc;
 572
 573         INIT_LIST_HEAD(&dp->dccps_options.dccpo_pending);
 574         INIT_LIST_HEAD(&dp->dccps_options.dccpo_conf);
 575
 576         /* CCID L */
 577         rc = __dccp_feat_init(sk, DCCPO_CHANGE_L, DCCPF_CCID,
 578                               &dp->dccps_options.dccpo_tx_ccid, 1);
 579         if (rc)
 580                 goto out;
 581
 582         /* CCID R */
 583         rc = __dccp_feat_init(sk, DCCPO_CHANGE_R, DCCPF_CCID,
 584                               &dp->dccps_options.dccpo_rx_ccid, 1);
 585         if (rc)
 586                 goto out;
 587
 588         /* Ack ratio */
 589         rc = __dccp_feat_init(sk, DCCPO_CHANGE_L, DCCPF_ACK_RATIO,
 590                               &dp->dccps_options.dccpo_ack_ratio, 1);
 591 out:
 592         return rc;
 593 }
 594
 595 EXPORT_SYMBOL_GPL(dccp_feat_init);