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