root/security/keys/request_key.c

DEFINITIONS

1. check_cached_key
2. cache_requested_key
3. complete_request_key
4. umh_keys_init
5. umh_keys_cleanup
6. call_usermodehelper_keys
7. call_sbin_request_key
8. construct_key
9. construct_get_dest_keyring
10. construct_alloc_key
11. construct_key_and_link
12. request_key_and_link
13. wait_for_key_construction
14. request_key_tag
15. request_key_with_auxdata
16. request_key_rcu

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* Request a key from userspace
   3  *
   4  * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells (dhowells@redhat.com)
   6  *
   7  * See Documentation/security/keys/request-key.rst
   8  */
   9 
  10 #include <linux/export.h>
  11 #include <linux/sched.h>
  12 #include <linux/kmod.h>
  13 #include <linux/err.h>
  14 #include <linux/keyctl.h>
  15 #include <linux/slab.h>
  16 #include <net/net_namespace.h>
  17 #include "internal.h"
  18 #include <keys/request_key_auth-type.h>
  19 
  20 #define key_negative_timeout    60      /* default timeout on a negative key's existence */
  21 
  22 static struct key *check_cached_key(struct keyring_search_context *ctx)
  23 {
  24 #ifdef CONFIG_KEYS_REQUEST_CACHE
  25         struct key *key = current->cached_requested_key;
  26 
  27         if (key &&
  28             ctx->match_data.cmp(key, &ctx->match_data) &&
  29             !(key->flags & ((1 << KEY_FLAG_INVALIDATED) |
  30                             (1 << KEY_FLAG_REVOKED))))
  31                 return key_get(key);
  32 #endif
  33         return NULL;
  34 }
  35 
  36 static void cache_requested_key(struct key *key)
  37 {
  38 #ifdef CONFIG_KEYS_REQUEST_CACHE
  39         struct task_struct *t = current;
  40 
  41         key_put(t->cached_requested_key);
  42         t->cached_requested_key = key_get(key);
  43         set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
  44 #endif
  45 }
  46 
  47 /**
  48  * complete_request_key - Complete the construction of a key.
  49  * @authkey: The authorisation key.
  50  * @error: The success or failute of the construction.
  51  *
  52  * Complete the attempt to construct a key.  The key will be negated
  53  * if an error is indicated.  The authorisation key will be revoked
  54  * unconditionally.
  55  */
  56 void complete_request_key(struct key *authkey, int error)
  57 {
  58         struct request_key_auth *rka = get_request_key_auth(authkey);
  59         struct key *key = rka->target_key;
  60 
  61         kenter("%d{%d},%d", authkey->serial, key->serial, error);
  62 
  63         if (error < 0)
  64                 key_negate_and_link(key, key_negative_timeout, NULL, authkey);
  65         else
  66                 key_revoke(authkey);
  67 }
  68 EXPORT_SYMBOL(complete_request_key);
  69 
  70 /*
  71  * Initialise a usermode helper that is going to have a specific session
  72  * keyring.
  73  *
  74  * This is called in context of freshly forked kthread before kernel_execve(),
  75  * so we can simply install the desired session_keyring at this point.
  76  */
  77 static int umh_keys_init(struct subprocess_info *info, struct cred *cred)
  78 {
  79         struct key *keyring = info->data;
  80 
  81         return install_session_keyring_to_cred(cred, keyring);
  82 }
  83 
  84 /*
  85  * Clean up a usermode helper with session keyring.
  86  */
  87 static void umh_keys_cleanup(struct subprocess_info *info)
  88 {
  89         struct key *keyring = info->data;
  90         key_put(keyring);
  91 }
  92 
  93 /*
  94  * Call a usermode helper with a specific session keyring.
  95  */
  96 static int call_usermodehelper_keys(const char *path, char **argv, char **envp,
  97                                         struct key *session_keyring, int wait)
  98 {
  99         struct subprocess_info *info;
 100 
 101         info = call_usermodehelper_setup(path, argv, envp, GFP_KERNEL,
 102                                           umh_keys_init, umh_keys_cleanup,
 103                                           session_keyring);
 104         if (!info)
 105                 return -ENOMEM;
 106 
 107         key_get(session_keyring);
 108         return call_usermodehelper_exec(info, wait);
 109 }
 110 
 111 /*
 112  * Request userspace finish the construction of a key
 113  * - execute "/sbin/request-key <op> <key> <uid> <gid> <keyring> <keyring> <keyring>"
 114  */
 115 static int call_sbin_request_key(struct key *authkey, void *aux)
 116 {
 117         static char const request_key[] = "/sbin/request-key";
 118         struct request_key_auth *rka = get_request_key_auth(authkey);
 119         const struct cred *cred = current_cred();
 120         key_serial_t prkey, sskey;
 121         struct key *key = rka->target_key, *keyring, *session, *user_session;
 122         char *argv[9], *envp[3], uid_str[12], gid_str[12];
 123         char key_str[12], keyring_str[3][12];
 124         char desc[20];
 125         int ret, i;
 126 
 127         kenter("{%d},{%d},%s", key->serial, authkey->serial, rka->op);
 128 
 129         ret = look_up_user_keyrings(NULL, &user_session);
 130         if (ret < 0)
 131                 goto error_us;
 132 
 133         /* allocate a new session keyring */
 134         sprintf(desc, "_req.%u", key->serial);
 135 
 136         cred = get_current_cred();
 137         keyring = keyring_alloc(desc, cred->fsuid, cred->fsgid, cred,
 138                                 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ,
 139                                 KEY_ALLOC_QUOTA_OVERRUN, NULL, NULL);
 140         put_cred(cred);
 141         if (IS_ERR(keyring)) {
 142                 ret = PTR_ERR(keyring);
 143                 goto error_alloc;
 144         }
 145 
 146         /* attach the auth key to the session keyring */
 147         ret = key_link(keyring, authkey);
 148         if (ret < 0)
 149                 goto error_link;
 150 
 151         /* record the UID and GID */
 152         sprintf(uid_str, "%d", from_kuid(&init_user_ns, cred->fsuid));
 153         sprintf(gid_str, "%d", from_kgid(&init_user_ns, cred->fsgid));
 154 
 155         /* we say which key is under construction */
 156         sprintf(key_str, "%d", key->serial);
 157 
 158         /* we specify the process's default keyrings */
 159         sprintf(keyring_str[0], "%d",
 160                 cred->thread_keyring ? cred->thread_keyring->serial : 0);
 161 
 162         prkey = 0;
 163         if (cred->process_keyring)
 164                 prkey = cred->process_keyring->serial;
 165         sprintf(keyring_str[1], "%d", prkey);
 166 
 167         session = cred->session_keyring;
 168         if (!session)
 169                 session = user_session;
 170         sskey = session->serial;
 171 
 172         sprintf(keyring_str[2], "%d", sskey);
 173 
 174         /* set up a minimal environment */
 175         i = 0;
 176         envp[i++] = "HOME=/";
 177         envp[i++] = "PATH=/sbin:/bin:/usr/sbin:/usr/bin";
 178         envp[i] = NULL;
 179 
 180         /* set up the argument list */
 181         i = 0;
 182         argv[i++] = (char *)request_key;
 183         argv[i++] = (char *)rka->op;
 184         argv[i++] = key_str;
 185         argv[i++] = uid_str;
 186         argv[i++] = gid_str;
 187         argv[i++] = keyring_str[0];
 188         argv[i++] = keyring_str[1];
 189         argv[i++] = keyring_str[2];
 190         argv[i] = NULL;
 191 
 192         /* do it */
 193         ret = call_usermodehelper_keys(request_key, argv, envp, keyring,
 194                                        UMH_WAIT_PROC);
 195         kdebug("usermode -> 0x%x", ret);
 196         if (ret >= 0) {
 197                 /* ret is the exit/wait code */
 198                 if (test_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags) ||
 199                     key_validate(key) < 0)
 200                         ret = -ENOKEY;
 201                 else
 202                         /* ignore any errors from userspace if the key was
 203                          * instantiated */
 204                         ret = 0;
 205         }
 206 
 207 error_link:
 208         key_put(keyring);
 209 
 210 error_alloc:
 211         key_put(user_session);
 212 error_us:
 213         complete_request_key(authkey, ret);
 214         kleave(" = %d", ret);
 215         return ret;
 216 }
 217 
 218 /*
 219  * Call out to userspace for key construction.
 220  *
 221  * Program failure is ignored in favour of key status.
 222  */
 223 static int construct_key(struct key *key, const void *callout_info,
 224                          size_t callout_len, void *aux,
 225                          struct key *dest_keyring)
 226 {
 227         request_key_actor_t actor;
 228         struct key *authkey;
 229         int ret;
 230 
 231         kenter("%d,%p,%zu,%p", key->serial, callout_info, callout_len, aux);
 232 
 233         /* allocate an authorisation key */
 234         authkey = request_key_auth_new(key, "create", callout_info, callout_len,
 235                                        dest_keyring);
 236         if (IS_ERR(authkey))
 237                 return PTR_ERR(authkey);
 238 
 239         /* Make the call */
 240         actor = call_sbin_request_key;
 241         if (key->type->request_key)
 242                 actor = key->type->request_key;
 243 
 244         ret = actor(authkey, aux);
 245 
 246         /* check that the actor called complete_request_key() prior to
 247          * returning an error */
 248         WARN_ON(ret < 0 &&
 249                 !test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
 250 
 251         key_put(authkey);
 252         kleave(" = %d", ret);
 253         return ret;
 254 }
 255 
 256 /*
 257  * Get the appropriate destination keyring for the request.
 258  *
 259  * The keyring selected is returned with an extra reference upon it which the
 260  * caller must release.
 261  */
 262 static int construct_get_dest_keyring(struct key **_dest_keyring)
 263 {
 264         struct request_key_auth *rka;
 265         const struct cred *cred = current_cred();
 266         struct key *dest_keyring = *_dest_keyring, *authkey;
 267         int ret;
 268 
 269         kenter("%p", dest_keyring);
 270 
 271         /* find the appropriate keyring */
 272         if (dest_keyring) {
 273                 /* the caller supplied one */
 274                 key_get(dest_keyring);
 275         } else {
 276                 bool do_perm_check = true;
 277 
 278                 /* use a default keyring; falling through the cases until we
 279                  * find one that we actually have */
 280                 switch (cred->jit_keyring) {
 281                 case KEY_REQKEY_DEFL_DEFAULT:
 282                 case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
 283                         if (cred->request_key_auth) {
 284                                 authkey = cred->request_key_auth;
 285                                 down_read(&authkey->sem);
 286                                 rka = get_request_key_auth(authkey);
 287                                 if (!test_bit(KEY_FLAG_REVOKED,
 288                                               &authkey->flags))
 289                                         dest_keyring =
 290                                                 key_get(rka->dest_keyring);
 291                                 up_read(&authkey->sem);
 292                                 if (dest_keyring) {
 293                                         do_perm_check = false;
 294                                         break;
 295                                 }
 296                         }
 297 
 298                         /* fall through */
 299                 case KEY_REQKEY_DEFL_THREAD_KEYRING:
 300                         dest_keyring = key_get(cred->thread_keyring);
 301                         if (dest_keyring)
 302                                 break;
 303 
 304                         /* fall through */
 305                 case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 306                         dest_keyring = key_get(cred->process_keyring);
 307                         if (dest_keyring)
 308                                 break;
 309 
 310                         /* fall through */
 311                 case KEY_REQKEY_DEFL_SESSION_KEYRING:
 312                         dest_keyring = key_get(cred->session_keyring);
 313 
 314                         if (dest_keyring)
 315                                 break;
 316 
 317                         /* fall through */
 318                 case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 319                         ret = look_up_user_keyrings(NULL, &dest_keyring);
 320                         if (ret < 0)
 321                                 return ret;
 322                         break;
 323 
 324                 case KEY_REQKEY_DEFL_USER_KEYRING:
 325                         ret = look_up_user_keyrings(&dest_keyring, NULL);
 326                         if (ret < 0)
 327                                 return ret;
 328                         break;
 329 
 330                 case KEY_REQKEY_DEFL_GROUP_KEYRING:
 331                 default:
 332                         BUG();
 333                 }
 334 
 335                 /*
 336                  * Require Write permission on the keyring.  This is essential
 337                  * because the default keyring may be the session keyring, and
 338                  * joining a keyring only requires Search permission.
 339                  *
 340                  * However, this check is skipped for the "requestor keyring" so
 341                  * that /sbin/request-key can itself use request_key() to add
 342                  * keys to the original requestor's destination keyring.
 343                  */
 344                 if (dest_keyring && do_perm_check) {
 345                         ret = key_permission(make_key_ref(dest_keyring, 1),
 346                                              KEY_NEED_WRITE);
 347                         if (ret) {
 348                                 key_put(dest_keyring);
 349                                 return ret;
 350                         }
 351                 }
 352         }
 353 
 354         *_dest_keyring = dest_keyring;
 355         kleave(" [dk %d]", key_serial(dest_keyring));
 356         return 0;
 357 }
 358 
 359 /*
 360  * Allocate a new key in under-construction state and attempt to link it in to
 361  * the requested keyring.
 362  *
 363  * May return a key that's already under construction instead if there was a
 364  * race between two thread calling request_key().
 365  */
 366 static int construct_alloc_key(struct keyring_search_context *ctx,
 367                                struct key *dest_keyring,
 368                                unsigned long flags,
 369                                struct key_user *user,
 370                                struct key **_key)
 371 {
 372         struct assoc_array_edit *edit = NULL;
 373         struct key *key;
 374         key_perm_t perm;
 375         key_ref_t key_ref;
 376         int ret;
 377 
 378         kenter("%s,%s,,,",
 379                ctx->index_key.type->name, ctx->index_key.description);
 380 
 381         *_key = NULL;
 382         mutex_lock(&user->cons_lock);
 383 
 384         perm = KEY_POS_VIEW | KEY_POS_SEARCH | KEY_POS_LINK | KEY_POS_SETATTR;
 385         perm |= KEY_USR_VIEW;
 386         if (ctx->index_key.type->read)
 387                 perm |= KEY_POS_READ;
 388         if (ctx->index_key.type == &key_type_keyring ||
 389             ctx->index_key.type->update)
 390                 perm |= KEY_POS_WRITE;
 391 
 392         key = key_alloc(ctx->index_key.type, ctx->index_key.description,
 393                         ctx->cred->fsuid, ctx->cred->fsgid, ctx->cred,
 394                         perm, flags, NULL);
 395         if (IS_ERR(key))
 396                 goto alloc_failed;
 397 
 398         set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
 399 
 400         if (dest_keyring) {
 401                 ret = __key_link_lock(dest_keyring, &ctx->index_key);
 402                 if (ret < 0)
 403                         goto link_lock_failed;
 404                 ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
 405                 if (ret < 0)
 406                         goto link_prealloc_failed;
 407         }
 408 
 409         /* attach the key to the destination keyring under lock, but we do need
 410          * to do another check just in case someone beat us to it whilst we
 411          * waited for locks */
 412         mutex_lock(&key_construction_mutex);
 413 
 414         rcu_read_lock();
 415         key_ref = search_process_keyrings_rcu(ctx);
 416         rcu_read_unlock();
 417         if (!IS_ERR(key_ref))
 418                 goto key_already_present;
 419 
 420         if (dest_keyring)
 421                 __key_link(key, &edit);
 422 
 423         mutex_unlock(&key_construction_mutex);
 424         if (dest_keyring)
 425                 __key_link_end(dest_keyring, &ctx->index_key, edit);
 426         mutex_unlock(&user->cons_lock);
 427         *_key = key;
 428         kleave(" = 0 [%d]", key_serial(key));
 429         return 0;
 430 
 431         /* the key is now present - we tell the caller that we found it by
 432          * returning -EINPROGRESS  */
 433 key_already_present:
 434         key_put(key);
 435         mutex_unlock(&key_construction_mutex);
 436         key = key_ref_to_ptr(key_ref);
 437         if (dest_keyring) {
 438                 ret = __key_link_check_live_key(dest_keyring, key);
 439                 if (ret == 0)
 440                         __key_link(key, &edit);
 441                 __key_link_end(dest_keyring, &ctx->index_key, edit);
 442                 if (ret < 0)
 443                         goto link_check_failed;
 444         }
 445         mutex_unlock(&user->cons_lock);
 446         *_key = key;
 447         kleave(" = -EINPROGRESS [%d]", key_serial(key));
 448         return -EINPROGRESS;
 449 
 450 link_check_failed:
 451         mutex_unlock(&user->cons_lock);
 452         key_put(key);
 453         kleave(" = %d [linkcheck]", ret);
 454         return ret;
 455 
 456 link_prealloc_failed:
 457         __key_link_end(dest_keyring, &ctx->index_key, edit);
 458 link_lock_failed:
 459         mutex_unlock(&user->cons_lock);
 460         key_put(key);
 461         kleave(" = %d [prelink]", ret);
 462         return ret;
 463 
 464 alloc_failed:
 465         mutex_unlock(&user->cons_lock);
 466         kleave(" = %ld", PTR_ERR(key));
 467         return PTR_ERR(key);
 468 }
 469 
 470 /*
 471  * Commence key construction.
 472  */
 473 static struct key *construct_key_and_link(struct keyring_search_context *ctx,
 474                                           const char *callout_info,
 475                                           size_t callout_len,
 476                                           void *aux,
 477                                           struct key *dest_keyring,
 478                                           unsigned long flags)
 479 {
 480         struct key_user *user;
 481         struct key *key;
 482         int ret;
 483 
 484         kenter("");
 485 
 486         if (ctx->index_key.type == &key_type_keyring)
 487                 return ERR_PTR(-EPERM);
 488 
 489         ret = construct_get_dest_keyring(&dest_keyring);
 490         if (ret)
 491                 goto error;
 492 
 493         user = key_user_lookup(current_fsuid());
 494         if (!user) {
 495                 ret = -ENOMEM;
 496                 goto error_put_dest_keyring;
 497         }
 498 
 499         ret = construct_alloc_key(ctx, dest_keyring, flags, user, &key);
 500         key_user_put(user);
 501 
 502         if (ret == 0) {
 503                 ret = construct_key(key, callout_info, callout_len, aux,
 504                                     dest_keyring);
 505                 if (ret < 0) {
 506                         kdebug("cons failed");
 507                         goto construction_failed;
 508                 }
 509         } else if (ret == -EINPROGRESS) {
 510                 ret = 0;
 511         } else {
 512                 goto error_put_dest_keyring;
 513         }
 514 
 515         key_put(dest_keyring);
 516         kleave(" = key %d", key_serial(key));
 517         return key;
 518 
 519 construction_failed:
 520         key_negate_and_link(key, key_negative_timeout, NULL, NULL);
 521         key_put(key);
 522 error_put_dest_keyring:
 523         key_put(dest_keyring);
 524 error:
 525         kleave(" = %d", ret);
 526         return ERR_PTR(ret);
 527 }
 528 
 529 /**
 530  * request_key_and_link - Request a key and cache it in a keyring.
 531  * @type: The type of key we want.
 532  * @description: The searchable description of the key.
 533  * @domain_tag: The domain in which the key operates.
 534  * @callout_info: The data to pass to the instantiation upcall (or NULL).
 535  * @callout_len: The length of callout_info.
 536  * @aux: Auxiliary data for the upcall.
 537  * @dest_keyring: Where to cache the key.
 538  * @flags: Flags to key_alloc().
 539  *
 540  * A key matching the specified criteria (type, description, domain_tag) is
 541  * searched for in the process's keyrings and returned with its usage count
 542  * incremented if found.  Otherwise, if callout_info is not NULL, a key will be
 543  * allocated and some service (probably in userspace) will be asked to
 544  * instantiate it.
 545  *
 546  * If successfully found or created, the key will be linked to the destination
 547  * keyring if one is provided.
 548  *
 549  * Returns a pointer to the key if successful; -EACCES, -ENOKEY, -EKEYREVOKED
 550  * or -EKEYEXPIRED if an inaccessible, negative, revoked or expired key was
 551  * found; -ENOKEY if no key was found and no @callout_info was given; -EDQUOT
 552  * if insufficient key quota was available to create a new key; or -ENOMEM if
 553  * insufficient memory was available.
 554  *
 555  * If the returned key was created, then it may still be under construction,
 556  * and wait_for_key_construction() should be used to wait for that to complete.
 557  */
 558 struct key *request_key_and_link(struct key_type *type,
 559                                  const char *description,
 560                                  struct key_tag *domain_tag,
 561                                  const void *callout_info,
 562                                  size_t callout_len,
 563                                  void *aux,
 564                                  struct key *dest_keyring,
 565                                  unsigned long flags)
 566 {
 567         struct keyring_search_context ctx = {
 568                 .index_key.type         = type,
 569                 .index_key.domain_tag   = domain_tag,
 570                 .index_key.description  = description,
 571                 .index_key.desc_len     = strlen(description),
 572                 .cred                   = current_cred(),
 573                 .match_data.cmp         = key_default_cmp,
 574                 .match_data.raw_data    = description,
 575                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
 576                 .flags                  = (KEYRING_SEARCH_DO_STATE_CHECK |
 577                                            KEYRING_SEARCH_SKIP_EXPIRED |
 578                                            KEYRING_SEARCH_RECURSE),
 579         };
 580         struct key *key;
 581         key_ref_t key_ref;
 582         int ret;
 583 
 584         kenter("%s,%s,%p,%zu,%p,%p,%lx",
 585                ctx.index_key.type->name, ctx.index_key.description,
 586                callout_info, callout_len, aux, dest_keyring, flags);
 587 
 588         if (type->match_preparse) {
 589                 ret = type->match_preparse(&ctx.match_data);
 590                 if (ret < 0) {
 591                         key = ERR_PTR(ret);
 592                         goto error;
 593                 }
 594         }
 595 
 596         key = check_cached_key(&ctx);
 597         if (key)
 598                 goto error_free;
 599 
 600         /* search all the process keyrings for a key */
 601         rcu_read_lock();
 602         key_ref = search_process_keyrings_rcu(&ctx);
 603         rcu_read_unlock();
 604 
 605         if (!IS_ERR(key_ref)) {
 606                 if (dest_keyring) {
 607                         ret = key_task_permission(key_ref, current_cred(),
 608                                                   KEY_NEED_LINK);
 609                         if (ret < 0) {
 610                                 key_ref_put(key_ref);
 611                                 key = ERR_PTR(ret);
 612                                 goto error_free;
 613                         }
 614                 }
 615 
 616                 key = key_ref_to_ptr(key_ref);
 617                 if (dest_keyring) {
 618                         ret = key_link(dest_keyring, key);
 619                         if (ret < 0) {
 620                                 key_put(key);
 621                                 key = ERR_PTR(ret);
 622                                 goto error_free;
 623                         }
 624                 }
 625 
 626                 /* Only cache the key on immediate success */
 627                 cache_requested_key(key);
 628         } else if (PTR_ERR(key_ref) != -EAGAIN) {
 629                 key = ERR_CAST(key_ref);
 630         } else  {
 631                 /* the search failed, but the keyrings were searchable, so we
 632                  * should consult userspace if we can */
 633                 key = ERR_PTR(-ENOKEY);
 634                 if (!callout_info)
 635                         goto error_free;
 636 
 637                 key = construct_key_and_link(&ctx, callout_info, callout_len,
 638                                              aux, dest_keyring, flags);
 639         }
 640 
 641 error_free:
 642         if (type->match_free)
 643                 type->match_free(&ctx.match_data);
 644 error:
 645         kleave(" = %p", key);
 646         return key;
 647 }
 648 
 649 /**
 650  * wait_for_key_construction - Wait for construction of a key to complete
 651  * @key: The key being waited for.
 652  * @intr: Whether to wait interruptibly.
 653  *
 654  * Wait for a key to finish being constructed.
 655  *
 656  * Returns 0 if successful; -ERESTARTSYS if the wait was interrupted; -ENOKEY
 657  * if the key was negated; or -EKEYREVOKED or -EKEYEXPIRED if the key was
 658  * revoked or expired.
 659  */
 660 int wait_for_key_construction(struct key *key, bool intr)
 661 {
 662         int ret;
 663 
 664         ret = wait_on_bit(&key->flags, KEY_FLAG_USER_CONSTRUCT,
 665                           intr ? TASK_INTERRUPTIBLE : TASK_UNINTERRUPTIBLE);
 666         if (ret)
 667                 return -ERESTARTSYS;
 668         ret = key_read_state(key);
 669         if (ret < 0)
 670                 return ret;
 671         return key_validate(key);
 672 }
 673 EXPORT_SYMBOL(wait_for_key_construction);
 674 
 675 /**
 676  * request_key_tag - Request a key and wait for construction
 677  * @type: Type of key.
 678  * @description: The searchable description of the key.
 679  * @domain_tag: The domain in which the key operates.
 680  * @callout_info: The data to pass to the instantiation upcall (or NULL).
 681  *
 682  * As for request_key_and_link() except that it does not add the returned key
 683  * to a keyring if found, new keys are always allocated in the user's quota,
 684  * the callout_info must be a NUL-terminated string and no auxiliary data can
 685  * be passed.
 686  *
 687  * Furthermore, it then works as wait_for_key_construction() to wait for the
 688  * completion of keys undergoing construction with a non-interruptible wait.
 689  */
 690 struct key *request_key_tag(struct key_type *type,
 691                             const char *description,
 692                             struct key_tag *domain_tag,
 693                             const char *callout_info)
 694 {
 695         struct key *key;
 696         size_t callout_len = 0;
 697         int ret;
 698 
 699         if (callout_info)
 700                 callout_len = strlen(callout_info);
 701         key = request_key_and_link(type, description, domain_tag,
 702                                    callout_info, callout_len,
 703                                    NULL, NULL, KEY_ALLOC_IN_QUOTA);
 704         if (!IS_ERR(key)) {
 705                 ret = wait_for_key_construction(key, false);
 706                 if (ret < 0) {
 707                         key_put(key);
 708                         return ERR_PTR(ret);
 709                 }
 710         }
 711         return key;
 712 }
 713 EXPORT_SYMBOL(request_key_tag);
 714 
 715 /**
 716  * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
 717  * @type: The type of key we want.
 718  * @description: The searchable description of the key.
 719  * @domain_tag: The domain in which the key operates.
 720  * @callout_info: The data to pass to the instantiation upcall (or NULL).
 721  * @callout_len: The length of callout_info.
 722  * @aux: Auxiliary data for the upcall.
 723  *
 724  * As for request_key_and_link() except that it does not add the returned key
 725  * to a keyring if found and new keys are always allocated in the user's quota.
 726  *
 727  * Furthermore, it then works as wait_for_key_construction() to wait for the
 728  * completion of keys undergoing construction with a non-interruptible wait.
 729  */
 730 struct key *request_key_with_auxdata(struct key_type *type,
 731                                      const char *description,
 732                                      struct key_tag *domain_tag,
 733                                      const void *callout_info,
 734                                      size_t callout_len,
 735                                      void *aux)
 736 {
 737         struct key *key;
 738         int ret;
 739 
 740         key = request_key_and_link(type, description, domain_tag,
 741                                    callout_info, callout_len,
 742                                    aux, NULL, KEY_ALLOC_IN_QUOTA);
 743         if (!IS_ERR(key)) {
 744                 ret = wait_for_key_construction(key, false);
 745                 if (ret < 0) {
 746                         key_put(key);
 747                         return ERR_PTR(ret);
 748                 }
 749         }
 750         return key;
 751 }
 752 EXPORT_SYMBOL(request_key_with_auxdata);
 753 
 754 /**
 755  * request_key_rcu - Request key from RCU-read-locked context
 756  * @type: The type of key we want.
 757  * @description: The name of the key we want.
 758  * @domain_tag: The domain in which the key operates.
 759  *
 760  * Request a key from a context that we may not sleep in (such as RCU-mode
 761  * pathwalk).  Keys under construction are ignored.
 762  *
 763  * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
 764  * a key or some other error if the key found was unsuitable or inaccessible.
 765  */
 766 struct key *request_key_rcu(struct key_type *type,
 767                             const char *description,
 768                             struct key_tag *domain_tag)
 769 {
 770         struct keyring_search_context ctx = {
 771                 .index_key.type         = type,
 772                 .index_key.domain_tag   = domain_tag,
 773                 .index_key.description  = description,
 774                 .index_key.desc_len     = strlen(description),
 775                 .cred                   = current_cred(),
 776                 .match_data.cmp         = key_default_cmp,
 777                 .match_data.raw_data    = description,
 778                 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT,
 779                 .flags                  = (KEYRING_SEARCH_DO_STATE_CHECK |
 780                                            KEYRING_SEARCH_SKIP_EXPIRED),
 781         };
 782         struct key *key;
 783         key_ref_t key_ref;
 784 
 785         kenter("%s,%s", type->name, description);
 786 
 787         key = check_cached_key(&ctx);
 788         if (key)
 789                 return key;
 790 
 791         /* search all the process keyrings for a key */
 792         key_ref = search_process_keyrings_rcu(&ctx);
 793         if (IS_ERR(key_ref)) {
 794                 key = ERR_CAST(key_ref);
 795                 if (PTR_ERR(key_ref) == -EAGAIN)
 796                         key = ERR_PTR(-ENOKEY);
 797         } else {
 798                 key = key_ref_to_ptr(key_ref);
 799                 cache_requested_key(key);
 800         }
 801 
 802         kleave(" = %p", key);
 803         return key;
 804 }
 805 EXPORT_SYMBOL(request_key_rcu);