security/keys/process_keys.c

   1 /* Management of a process's keyrings
   2  *
   3  * Copyright (C) 2004-2005, 2008 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/keyctl.h>
  16 #include <linux/fs.h>
  17 #include <linux/err.h>
  18 #include <linux/mutex.h>
  19 #include <linux/security.h>
  20 #include <linux/user_namespace.h>
  21 #include <asm/uaccess.h>
  22 #include "internal.h"
  23
  24 /* session keyring create vs join semaphore */
  25 static DEFINE_MUTEX(key_session_mutex);
  26
  27 /* user keyring creation semaphore */
  28 static DEFINE_MUTEX(key_user_keyring_mutex);
  29
  30 /* the root user's tracking struct */
  31 struct key_user root_key_user = {
  32         .usage          = ATOMIC_INIT(3),
  33         .cons_lock      = __MUTEX_INITIALIZER(root_key_user.cons_lock),
  34         .lock           = __SPIN_LOCK_UNLOCKED(root_key_user.lock),
  35         .nkeys          = ATOMIC_INIT(2),
  36         .nikeys         = ATOMIC_INIT(2),
  37         .uid            = 0,
  38         .user_ns        = &init_user_ns,
  39 };
  40
  41 /*****************************************************************************/
  42 /*
  43  * install user and user session keyrings for a particular UID
  44  */
  45 int install_user_keyrings(void)
  46 {
  47         struct user_struct *user;
  48         const struct cred *cred;
  49         struct key *uid_keyring, *session_keyring;
  50         char buf[20];
  51         int ret;
  52
  53         cred = current_cred();
  54         user = cred->user;
  55
  56         kenter("%p{%u}", user, user->uid);
  57
  58         if (user->uid_keyring) {
  59                 kleave(" = 0 [exist]");
  60                 return 0;
  61         }
  62
  63         mutex_lock(&key_user_keyring_mutex);
  64         ret = 0;
  65
  66         if (!user->uid_keyring) {
  67                 /* get the UID-specific keyring
  68                  * - there may be one in existence already as it may have been
  69                  *   pinned by a session, but the user_struct pointing to it
  70                  *   may have been destroyed by setuid */
  71                 sprintf(buf, "_uid.%u", user->uid);
  72
  73                 uid_keyring = find_keyring_by_name(buf, true);
  74                 if (IS_ERR(uid_keyring)) {
  75                         uid_keyring = keyring_alloc(buf, user->uid, (gid_t) -1,
  76                                                     cred, KEY_ALLOC_IN_QUOTA,
  77                                                     NULL);
  78                         if (IS_ERR(uid_keyring)) {
  79                                 ret = PTR_ERR(uid_keyring);
  80                                 goto error;
  81                         }
  82                 }
  83
  84                 /* get a default session keyring (which might also exist
  85                  * already) */
  86                 sprintf(buf, "_uid_ses.%u", user->uid);
  87
  88                 session_keyring = find_keyring_by_name(buf, true);
  89                 if (IS_ERR(session_keyring)) {
  90                         session_keyring =
  91                                 keyring_alloc(buf, user->uid, (gid_t) -1,
  92                                               cred, KEY_ALLOC_IN_QUOTA, NULL);
  93                         if (IS_ERR(session_keyring)) {
  94                                 ret = PTR_ERR(session_keyring);
  95                                 goto error_release;
  96                         }
  97
  98                         /* we install a link from the user session keyring to
  99                          * the user keyring */
 100                         ret = key_link(session_keyring, uid_keyring);
 101                         if (ret < 0)
 102                                 goto error_release_both;
 103                 }
 104
 105                 /* install the keyrings */
 106                 user->uid_keyring = uid_keyring;
 107                 user->session_keyring = session_keyring;
 108         }
 109
 110         mutex_unlock(&key_user_keyring_mutex);
 111         kleave(" = 0");
 112         return 0;
 113
 114 error_release_both:
 115         key_put(session_keyring);
 116 error_release:
 117         key_put(uid_keyring);
 118 error:
 119         mutex_unlock(&key_user_keyring_mutex);
 120         kleave(" = %d", ret);
 121         return ret;
 122 }
 123
 124 /*
 125  * install a fresh thread keyring directly to new credentials
 126  */
 127 int install_thread_keyring_to_cred(struct cred *new)
 128 {
 129         struct key *keyring;
 130
 131         keyring = keyring_alloc("_tid", new->uid, new->gid, new,
 132                                 KEY_ALLOC_QUOTA_OVERRUN, NULL);
 133         if (IS_ERR(keyring))
 134                 return PTR_ERR(keyring);
 135
 136         new->thread_keyring = keyring;
 137         return 0;
 138 }
 139
 140 /*
 141  * install a fresh thread keyring, discarding the old one
 142  */
 143 static int install_thread_keyring(void)
 144 {
 145         struct cred *new;
 146         int ret;
 147
 148         new = prepare_creds();
 149         if (!new)
 150                 return -ENOMEM;
 151
 152         BUG_ON(new->thread_keyring);
 153
 154         ret = install_thread_keyring_to_cred(new);
 155         if (ret < 0) {
 156                 abort_creds(new);
 157                 return ret;
 158         }
 159
 160         return commit_creds(new);
 161 }
 162
 163 /*
 164  * install a process keyring directly to a credentials struct
 165  * - returns -EEXIST if there was already a process keyring, 0 if one installed,
 166  *   and other -ve on any other error
 167  */
 168 int install_process_keyring_to_cred(struct cred *new)
 169 {
 170         struct key *keyring;
 171         int ret;
 172
 173         if (new->tgcred->process_keyring)
 174                 return -EEXIST;
 175
 176         keyring = keyring_alloc("_pid", new->uid, new->gid,
 177                                 new, KEY_ALLOC_QUOTA_OVERRUN, NULL);
 178         if (IS_ERR(keyring))
 179                 return PTR_ERR(keyring);
 180
 181         spin_lock_irq(&new->tgcred->lock);
 182         if (!new->tgcred->process_keyring) {
 183                 new->tgcred->process_keyring = keyring;
 184                 keyring = NULL;
 185                 ret = 0;
 186         } else {
 187                 ret = -EEXIST;
 188         }
 189         spin_unlock_irq(&new->tgcred->lock);
 190         key_put(keyring);
 191         return ret;
 192 }
 193
 194 /*
 195  * make sure a process keyring is installed
 196  * - we
 197  */
 198 static int install_process_keyring(void)
 199 {
 200         struct cred *new;
 201         int ret;
 202
 203         new = prepare_creds();
 204         if (!new)
 205                 return -ENOMEM;
 206
 207         ret = install_process_keyring_to_cred(new);
 208         if (ret < 0) {
 209                 abort_creds(new);
 210                 return ret != -EEXIST ?: 0;
 211         }
 212
 213         return commit_creds(new);
 214 }
 215
 216 /*
 217  * install a session keyring directly to a credentials struct
 218  */
 219 int install_session_keyring_to_cred(struct cred *cred, struct key *keyring)
 220 {
 221         unsigned long flags;
 222         struct key *old;
 223
 224         might_sleep();
 225
 226         /* create an empty session keyring */
 227         if (!keyring) {
 228                 flags = KEY_ALLOC_QUOTA_OVERRUN;
 229                 if (cred->tgcred->session_keyring)
 230                         flags = KEY_ALLOC_IN_QUOTA;
 231
 232                 keyring = keyring_alloc("_ses", cred->uid, cred->gid,
 233                                         cred, flags, NULL);
 234                 if (IS_ERR(keyring))
 235                         return PTR_ERR(keyring);
 236         } else {
 237                 atomic_inc(&keyring->usage);
 238         }
 239
 240         /* install the keyring */
 241         spin_lock_irq(&cred->tgcred->lock);
 242         old = cred->tgcred->session_keyring;
 243         rcu_assign_pointer(cred->tgcred->session_keyring, keyring);
 244         spin_unlock_irq(&cred->tgcred->lock);
 245
 246         /* we're using RCU on the pointer, but there's no point synchronising
 247          * on it if it didn't previously point to anything */
 248         if (old) {
 249                 synchronize_rcu();
 250                 key_put(old);
 251         }
 252
 253         return 0;
 254 }
 255
 256 /*
 257  * install a session keyring, discarding the old one
 258  * - if a keyring is not supplied, an empty one is invented
 259  */
 260 static int install_session_keyring(struct key *keyring)
 261 {
 262         struct cred *new;
 263         int ret;
 264
 265         new = prepare_creds();
 266         if (!new)
 267                 return -ENOMEM;
 268
 269         ret = install_session_keyring_to_cred(new, NULL);
 270         if (ret < 0) {
 271                 abort_creds(new);
 272                 return ret;
 273         }
 274
 275         return commit_creds(new);
 276 }
 277
 278 /*****************************************************************************/
 279 /*
 280  * the filesystem user ID changed
 281  */
 282 void key_fsuid_changed(struct task_struct *tsk)
 283 {
 284         /* update the ownership of the thread keyring */
 285         BUG_ON(!tsk->cred);
 286         if (tsk->cred->thread_keyring) {
 287                 down_write(&tsk->cred->thread_keyring->sem);
 288                 tsk->cred->thread_keyring->uid = tsk->cred->fsuid;
 289                 up_write(&tsk->cred->thread_keyring->sem);
 290         }
 291
 292 } /* end key_fsuid_changed() */
 293
 294 /*****************************************************************************/
 295 /*
 296  * the filesystem group ID changed
 297  */
 298 void key_fsgid_changed(struct task_struct *tsk)
 299 {
 300         /* update the ownership of the thread keyring */
 301         BUG_ON(!tsk->cred);
 302         if (tsk->cred->thread_keyring) {
 303                 down_write(&tsk->cred->thread_keyring->sem);
 304                 tsk->cred->thread_keyring->gid = tsk->cred->fsgid;
 305                 up_write(&tsk->cred->thread_keyring->sem);
 306         }
 307
 308 } /* end key_fsgid_changed() */
 309
 310 /*****************************************************************************/
 311 /*
 312  * search the process keyrings for the first matching key
 313  * - we use the supplied match function to see if the description (or other
 314  *   feature of interest) matches
 315  * - we return -EAGAIN if we didn't find any matching key
 316  * - we return -ENOKEY if we found only negative matching keys
 317  */
 318 key_ref_t search_process_keyrings(struct key_type *type,
 319                                   const void *description,
 320                                   key_match_func_t match,
 321                                   const struct cred *cred)
 322 {
 323         struct request_key_auth *rka;
 324         key_ref_t key_ref, ret, err;
 325
 326         might_sleep();
 327
 328         /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were
 329          * searchable, but we failed to find a key or we found a negative key;
 330          * otherwise we want to return a sample error (probably -EACCES) if
 331          * none of the keyrings were searchable
 332          *
 333          * in terms of priority: success > -ENOKEY > -EAGAIN > other error
 334          */
 335         key_ref = NULL;
 336         ret = NULL;
 337         err = ERR_PTR(-EAGAIN);
 338
 339         /* search the thread keyring first */
 340         if (cred->thread_keyring) {
 341                 key_ref = keyring_search_aux(
 342                         make_key_ref(cred->thread_keyring, 1),
 343                         cred, type, description, match);
 344                 if (!IS_ERR(key_ref))
 345                         goto found;
 346
 347                 switch (PTR_ERR(key_ref)) {
 348                 case -EAGAIN: /* no key */
 349                         if (ret)
 350                                 break;
 351                 case -ENOKEY: /* negative key */
 352                         ret = key_ref;
 353                         break;
 354                 default:
 355                         err = key_ref;
 356                         break;
 357                 }
 358         }
 359
 360         /* search the process keyring second */
 361         if (cred->tgcred->process_keyring) {
 362                 key_ref = keyring_search_aux(
 363                         make_key_ref(cred->tgcred->process_keyring, 1),
 364                         cred, type, description, match);
 365                 if (!IS_ERR(key_ref))
 366                         goto found;
 367
 368                 switch (PTR_ERR(key_ref)) {
 369                 case -EAGAIN: /* no key */
 370                         if (ret)
 371                                 break;
 372                 case -ENOKEY: /* negative key */
 373                         ret = key_ref;
 374                         break;
 375                 default:
 376                         err = key_ref;
 377                         break;
 378                 }
 379         }
 380
 381         /* search the session keyring */
 382         if (cred->tgcred->session_keyring) {
 383                 rcu_read_lock();
 384                 key_ref = keyring_search_aux(
 385                         make_key_ref(rcu_dereference(
 386                                              cred->tgcred->session_keyring),
 387                                      1),
 388                         cred, type, description, match);
 389                 rcu_read_unlock();
 390
 391                 if (!IS_ERR(key_ref))
 392                         goto found;
 393
 394                 switch (PTR_ERR(key_ref)) {
 395                 case -EAGAIN: /* no key */
 396                         if (ret)
 397                                 break;
 398                 case -ENOKEY: /* negative key */
 399                         ret = key_ref;
 400                         break;
 401                 default:
 402                         err = key_ref;
 403                         break;
 404                 }
 405         }
 406         /* or search the user-session keyring */
 407         else if (cred->user->session_keyring) {
 408                 key_ref = keyring_search_aux(
 409                         make_key_ref(cred->user->session_keyring, 1),
 410                         cred, type, description, match);
 411                 if (!IS_ERR(key_ref))
 412                         goto found;
 413
 414                 switch (PTR_ERR(key_ref)) {
 415                 case -EAGAIN: /* no key */
 416                         if (ret)
 417                                 break;
 418                 case -ENOKEY: /* negative key */
 419                         ret = key_ref;
 420                         break;
 421                 default:
 422                         err = key_ref;
 423                         break;
 424                 }
 425         }
 426
 427         /* if this process has an instantiation authorisation key, then we also
 428          * search the keyrings of the process mentioned there
 429          * - we don't permit access to request_key auth keys via this method
 430          */
 431         if (cred->request_key_auth &&
 432             cred == current_cred() &&
 433             type != &key_type_request_key_auth
 434             ) {
 435                 /* defend against the auth key being revoked */
 436                 down_read(&cred->request_key_auth->sem);
 437
 438                 if (key_validate(cred->request_key_auth) == 0) {
 439                         rka = cred->request_key_auth->payload.data;
 440
 441                         key_ref = search_process_keyrings(type, description,
 442                                                           match, rka->cred);
 443
 444                         up_read(&cred->request_key_auth->sem);
 445
 446                         if (!IS_ERR(key_ref))
 447                                 goto found;
 448
 449                         switch (PTR_ERR(key_ref)) {
 450                         case -EAGAIN: /* no key */
 451                                 if (ret)
 452                                         break;
 453                         case -ENOKEY: /* negative key */
 454                                 ret = key_ref;
 455                                 break;
 456                         default:
 457                                 err = key_ref;
 458                                 break;
 459                         }
 460                 } else {
 461                         up_read(&cred->request_key_auth->sem);
 462                 }
 463         }
 464
 465         /* no key - decide on the error we're going to go for */
 466         key_ref = ret ? ret : err;
 467
 468 found:
 469         return key_ref;
 470
 471 } /* end search_process_keyrings() */
 472
 473 /*****************************************************************************/
 474 /*
 475  * see if the key we're looking at is the target key
 476  */
 477 static int lookup_user_key_possessed(const struct key *key, const void *target)
 478 {
 479         return key == target;
 480
 481 } /* end lookup_user_key_possessed() */
 482
 483 /*****************************************************************************/
 484 /*
 485  * lookup a key given a key ID from userspace with a given permissions mask
 486  * - don't create special keyrings unless so requested
 487  * - partially constructed keys aren't found unless requested
 488  */
 489 key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags,
 490                           key_perm_t perm)
 491 {
 492         struct request_key_auth *rka;
 493         const struct cred *cred;
 494         struct key *key;
 495         key_ref_t key_ref, skey_ref;
 496         int ret;
 497
 498 try_again:
 499         cred = get_current_cred();
 500         key_ref = ERR_PTR(-ENOKEY);
 501
 502         switch (id) {
 503         case KEY_SPEC_THREAD_KEYRING:
 504                 if (!cred->thread_keyring) {
 505                         if (!(lflags & KEY_LOOKUP_CREATE))
 506                                 goto error;
 507
 508                         ret = install_thread_keyring();
 509                         if (ret < 0) {
 510                                 key_ref = ERR_PTR(ret);
 511                                 goto error;
 512                         }
 513                         goto reget_creds;
 514                 }
 515
 516                 key = cred->thread_keyring;
 517                 atomic_inc(&key->usage);
 518                 key_ref = make_key_ref(key, 1);
 519                 break;
 520
 521         case KEY_SPEC_PROCESS_KEYRING:
 522                 if (!cred->tgcred->process_keyring) {
 523                         if (!(lflags & KEY_LOOKUP_CREATE))
 524                                 goto error;
 525
 526                         ret = install_process_keyring();
 527                         if (ret < 0) {
 528                                 key_ref = ERR_PTR(ret);
 529                                 goto error;
 530                         }
 531                         goto reget_creds;
 532                 }
 533
 534                 key = cred->tgcred->process_keyring;
 535                 atomic_inc(&key->usage);
 536                 key_ref = make_key_ref(key, 1);
 537                 break;
 538
 539         case KEY_SPEC_SESSION_KEYRING:
 540                 if (!cred->tgcred->session_keyring) {
 541                         /* always install a session keyring upon access if one
 542                          * doesn't exist yet */
 543                         ret = install_user_keyrings();
 544                         if (ret < 0)
 545                                 goto error;
 546                         ret = install_session_keyring(
 547                                 cred->user->session_keyring);
 548
 549                         if (ret < 0)
 550                                 goto error;
 551                         goto reget_creds;
 552                 }
 553
 554                 rcu_read_lock();
 555                 key = rcu_dereference(cred->tgcred->session_keyring);
 556                 atomic_inc(&key->usage);
 557                 rcu_read_unlock();
 558                 key_ref = make_key_ref(key, 1);
 559                 break;
 560
 561         case KEY_SPEC_USER_KEYRING:
 562                 if (!cred->user->uid_keyring) {
 563                         ret = install_user_keyrings();
 564                         if (ret < 0)
 565                                 goto error;
 566                 }
 567
 568                 key = cred->user->uid_keyring;
 569                 atomic_inc(&key->usage);
 570                 key_ref = make_key_ref(key, 1);
 571                 break;
 572
 573         case KEY_SPEC_USER_SESSION_KEYRING:
 574                 if (!cred->user->session_keyring) {
 575                         ret = install_user_keyrings();
 576                         if (ret < 0)
 577                                 goto error;
 578                 }
 579
 580                 key = cred->user->session_keyring;
 581                 atomic_inc(&key->usage);
 582                 key_ref = make_key_ref(key, 1);
 583                 break;
 584
 585         case KEY_SPEC_GROUP_KEYRING:
 586                 /* group keyrings are not yet supported */
 587                 key_ref = ERR_PTR(-EINVAL);
 588                 goto error;
 589
 590         case KEY_SPEC_REQKEY_AUTH_KEY:
 591                 key = cred->request_key_auth;
 592                 if (!key)
 593                         goto error;
 594
 595                 atomic_inc(&key->usage);
 596                 key_ref = make_key_ref(key, 1);
 597                 break;
 598
 599         case KEY_SPEC_REQUESTOR_KEYRING:
 600                 if (!cred->request_key_auth)
 601                         goto error;
 602
 603                 down_read(&cred->request_key_auth->sem);
 604                 if (cred->request_key_auth->flags & KEY_FLAG_REVOKED) {
 605                         key_ref = ERR_PTR(-EKEYREVOKED);
 606                         key = NULL;
 607                 } else {
 608                         rka = cred->request_key_auth->payload.data;
 609                         key = rka->dest_keyring;
 610                         atomic_inc(&key->usage);
 611                 }
 612                 up_read(&cred->request_key_auth->sem);
 613                 if (!key)
 614                         goto error;
 615                 key_ref = make_key_ref(key, 1);
 616                 break;
 617
 618         default:
 619                 key_ref = ERR_PTR(-EINVAL);
 620                 if (id < 1)
 621                         goto error;
 622
 623                 key = key_lookup(id);
 624                 if (IS_ERR(key)) {
 625                         key_ref = ERR_CAST(key);
 626                         goto error;
 627                 }
 628
 629                 key_ref = make_key_ref(key, 0);
 630
 631                 /* check to see if we possess the key */
 632                 skey_ref = search_process_keyrings(key->type, key,
 633                                                    lookup_user_key_possessed,
 634                                                    cred);
 635
 636                 if (!IS_ERR(skey_ref)) {
 637                         key_put(key);
 638                         key_ref = skey_ref;
 639                 }
 640
 641                 break;
 642         }
 643
 644         /* unlink does not use the nominated key in any way, so can skip all
 645          * the permission checks as it is only concerned with the keyring */
 646         if (lflags & KEY_LOOKUP_FOR_UNLINK) {
 647                 ret = 0;
 648                 goto error;
 649         }
 650
 651         if (!(lflags & KEY_LOOKUP_PARTIAL)) {
 652                 ret = wait_for_key_construction(key, true);
 653                 switch (ret) {
 654                 case -ERESTARTSYS:
 655                         goto invalid_key;
 656                 default:
 657                         if (perm)
 658                                 goto invalid_key;
 659                 case 0:
 660                         break;
 661                 }
 662         } else if (perm) {
 663                 ret = key_validate(key);
 664                 if (ret < 0)
 665                         goto invalid_key;
 666         }
 667
 668         ret = -EIO;
 669         if (!(lflags & KEY_LOOKUP_PARTIAL) &&
 670             !test_bit(KEY_FLAG_INSTANTIATED, &key->flags))
 671                 goto invalid_key;
 672
 673         /* check the permissions */
 674         ret = key_task_permission(key_ref, cred, perm);
 675         if (ret < 0)
 676                 goto invalid_key;
 677
 678 error:
 679         put_cred(cred);
 680         return key_ref;
 681
 682 invalid_key:
 683         key_ref_put(key_ref);
 684         key_ref = ERR_PTR(ret);
 685         goto error;
 686
 687         /* if we attempted to install a keyring, then it may have caused new
 688          * creds to be installed */
 689 reget_creds:
 690         put_cred(cred);
 691         goto try_again;
 692
 693 } /* end lookup_user_key() */
 694
 695 /*****************************************************************************/
 696 /*
 697  * join the named keyring as the session keyring if possible, or attempt to
 698  * create a new one of that name if not
 699  * - if the name is NULL, an empty anonymous keyring is installed instead
 700  * - named session keyring joining is done with a semaphore held
 701  */
 702 long join_session_keyring(const char *name)
 703 {
 704         const struct cred *old;
 705         struct cred *new;
 706         struct key *keyring;
 707         long ret, serial;
 708
 709         /* only permit this if there's a single thread in the thread group -
 710          * this avoids us having to adjust the creds on all threads and risking
 711          * ENOMEM */
 712         if (!current_is_single_threaded())
 713                 return -EMLINK;
 714
 715         new = prepare_creds();
 716         if (!new)
 717                 return -ENOMEM;
 718         old = current_cred();
 719
 720         /* if no name is provided, install an anonymous keyring */
 721         if (!name) {
 722                 ret = install_session_keyring_to_cred(new, NULL);
 723                 if (ret < 0)
 724                         goto error;
 725
 726                 serial = new->tgcred->session_keyring->serial;
 727                 ret = commit_creds(new);
 728                 if (ret == 0)
 729                         ret = serial;
 730                 goto okay;
 731         }
 732
 733         /* allow the user to join or create a named keyring */
 734         mutex_lock(&key_session_mutex);
 735
 736         /* look for an existing keyring of this name */
 737         keyring = find_keyring_by_name(name, false);
 738         if (PTR_ERR(keyring) == -ENOKEY) {
 739                 /* not found - try and create a new one */
 740                 keyring = keyring_alloc(name, old->uid, old->gid, old,
 741                                         KEY_ALLOC_IN_QUOTA, NULL);
 742                 if (IS_ERR(keyring)) {
 743                         ret = PTR_ERR(keyring);
 744                         goto error2;
 745                 }
 746         } else if (IS_ERR(keyring)) {
 747                 ret = PTR_ERR(keyring);
 748                 goto error2;
 749         }
 750
 751         /* we've got a keyring - now to install it */
 752         ret = install_session_keyring_to_cred(new, keyring);
 753         if (ret < 0)
 754                 goto error2;
 755
 756         commit_creds(new);
 757         mutex_unlock(&key_session_mutex);
 758
 759         ret = keyring->serial;
 760         key_put(keyring);
 761 okay:
 762         return ret;
 763
 764 error2:
 765         mutex_unlock(&key_session_mutex);
 766 error:
 767         abort_creds(new);
 768         return ret;
 769 }
 770
 771 /*
 772  * Replace a process's session keyring when that process resumes userspace on
 773  * behalf of one of its children
 774  */
 775 void key_replace_session_keyring(void)
 776 {
 777         const struct cred *old;
 778         struct cred *new;
 779
 780         if (!current->replacement_session_keyring)
 781                 return;
 782
 783         write_lock_irq(&tasklist_lock);
 784         new = current->replacement_session_keyring;
 785         current->replacement_session_keyring = NULL;
 786         write_unlock_irq(&tasklist_lock);
 787
 788         if (!new)
 789                 return;
 790
 791         old = current_cred();
 792         new->  uid      = old->  uid;
 793         new-> euid      = old-> euid;
 794         new-> suid      = old-> suid;
 795         new->fsuid      = old->fsuid;
 796         new->  gid      = old->  gid;
 797         new-> egid      = old-> egid;
 798         new-> sgid      = old-> sgid;
 799         new->fsgid      = old->fsgid;
 800         new->user       = get_uid(old->user);
 801         new->group_info = get_group_info(old->group_info);
 802
 803         new->securebits = old->securebits;
 804         new->cap_inheritable    = old->cap_inheritable;
 805         new->cap_permitted      = old->cap_permitted;
 806         new->cap_effective      = old->cap_effective;
 807         new->cap_bset           = old->cap_bset;
 808
 809         new->jit_keyring        = old->jit_keyring;
 810         new->thread_keyring     = key_get(old->thread_keyring);
 811         new->tgcred->tgid       = old->tgcred->tgid;
 812         new->tgcred->process_keyring = key_get(old->tgcred->process_keyring);
 813
 814         security_transfer_creds(new, old);
 815
 816         commit_creds(new);
 817 }