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