1 /* Manage 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/init.h> 13 #include <linux/sched.h> 14 #include <linux/sched/user.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 <linux/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 = REFCOUNT_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 = GLOBAL_ROOT_UID, 38 }; 39 40 /* 41 * Install the user and user session keyrings for the current process's UID. 42 */ 43 int install_user_keyrings(void) 44 { 45 struct user_struct *user; 46 const struct cred *cred; 47 struct key *uid_keyring, *session_keyring; 48 key_perm_t user_keyring_perm; 49 char buf[20]; 50 int ret; 51 uid_t uid; 52 53 user_keyring_perm = (KEY_POS_ALL & ~KEY_POS_SETATTR) | KEY_USR_ALL; 54 cred = current_cred(); 55 user = cred->user; 56 uid = from_kuid(cred->user_ns, user->uid); 57 58 kenter("%p{%u}", user, uid); 59 60 if (user->uid_keyring && user->session_keyring) { 61 kleave(" = 0 [exist]"); 62 return 0; 63 } 64 65 mutex_lock(&key_user_keyring_mutex); 66 ret = 0; 67 68 if (!user->uid_keyring) { 69 /* get the UID-specific keyring 70 * - there may be one in existence already as it may have been 71 * pinned by a session, but the user_struct pointing to it 72 * may have been destroyed by setuid */ 73 sprintf(buf, "_uid.%u", uid); 74 75 uid_keyring = find_keyring_by_name(buf, true); 76 if (IS_ERR(uid_keyring)) { 77 uid_keyring = keyring_alloc(buf, user->uid, INVALID_GID, 78 cred, user_keyring_perm, 79 KEY_ALLOC_UID_KEYRING | 80 KEY_ALLOC_IN_QUOTA, 81 NULL, NULL); 82 if (IS_ERR(uid_keyring)) { 83 ret = PTR_ERR(uid_keyring); 84 goto error; 85 } 86 } 87 88 /* get a default session keyring (which might also exist 89 * already) */ 90 sprintf(buf, "_uid_ses.%u", uid); 91 92 session_keyring = find_keyring_by_name(buf, true); 93 if (IS_ERR(session_keyring)) { 94 session_keyring = 95 keyring_alloc(buf, user->uid, INVALID_GID, 96 cred, user_keyring_perm, 97 KEY_ALLOC_UID_KEYRING | 98 KEY_ALLOC_IN_QUOTA, 99 NULL, NULL); 100 if (IS_ERR(session_keyring)) { 101 ret = PTR_ERR(session_keyring); 102 goto error_release; 103 } 104 105 /* we install a link from the user session keyring to 106 * the user keyring */ 107 ret = key_link(session_keyring, uid_keyring); 108 if (ret < 0) 109 goto error_release_both; 110 } 111 112 /* install the keyrings */ 113 user->uid_keyring = uid_keyring; 114 user->session_keyring = session_keyring; 115 } 116 117 mutex_unlock(&key_user_keyring_mutex); 118 kleave(" = 0"); 119 return 0; 120 121 error_release_both: 122 key_put(session_keyring); 123 error_release: 124 key_put(uid_keyring); 125 error: 126 mutex_unlock(&key_user_keyring_mutex); 127 kleave(" = %d", ret); 128 return ret; 129 } 130 131 /* 132 * Install a thread keyring to the given credentials struct if it didn't have 133 * one already. This is allowed to overrun the quota. 134 * 135 * Return: 0 if a thread keyring is now present; -errno on failure. 136 */ 137 int install_thread_keyring_to_cred(struct cred *new) 138 { 139 struct key *keyring; 140 141 if (new->thread_keyring) 142 return 0; 143 144 keyring = keyring_alloc("_tid", new->uid, new->gid, new, 145 KEY_POS_ALL | KEY_USR_VIEW, 146 KEY_ALLOC_QUOTA_OVERRUN, 147 NULL, NULL); 148 if (IS_ERR(keyring)) 149 return PTR_ERR(keyring); 150 151 new->thread_keyring = keyring; 152 return 0; 153 } 154 155 /* 156 * Install a thread keyring to the current task if it didn't have one already. 157 * 158 * Return: 0 if a thread keyring is now present; -errno on failure. 159 */ 160 static int install_thread_keyring(void) 161 { 162 struct cred *new; 163 int ret; 164 165 new = prepare_creds(); 166 if (!new) 167 return -ENOMEM; 168 169 ret = install_thread_keyring_to_cred(new); 170 if (ret < 0) { 171 abort_creds(new); 172 return ret; 173 } 174 175 return commit_creds(new); 176 } 177 178 /* 179 * Install a process keyring to the given credentials struct if it didn't have 180 * one already. This is allowed to overrun the quota. 181 * 182 * Return: 0 if a process keyring is now present; -errno on failure. 183 */ 184 int install_process_keyring_to_cred(struct cred *new) 185 { 186 struct key *keyring; 187 188 if (new->process_keyring) 189 return 0; 190 191 keyring = keyring_alloc("_pid", new->uid, new->gid, new, 192 KEY_POS_ALL | KEY_USR_VIEW, 193 KEY_ALLOC_QUOTA_OVERRUN, 194 NULL, NULL); 195 if (IS_ERR(keyring)) 196 return PTR_ERR(keyring); 197 198 new->process_keyring = keyring; 199 return 0; 200 } 201 202 /* 203 * Install a process keyring to the current task if it didn't have one already. 204 * 205 * Return: 0 if a process keyring is now present; -errno on failure. 206 */ 207 static int install_process_keyring(void) 208 { 209 struct cred *new; 210 int ret; 211 212 new = prepare_creds(); 213 if (!new) 214 return -ENOMEM; 215 216 ret = install_process_keyring_to_cred(new); 217 if (ret < 0) { 218 abort_creds(new); 219 return ret; 220 } 221 222 return commit_creds(new); 223 } 224 225 /* 226 * Install the given keyring as the session keyring of the given credentials 227 * struct, replacing the existing one if any. If the given keyring is NULL, 228 * then install a new anonymous session keyring. 229 * 230 * Return: 0 on success; -errno on failure. 231 */ 232 int install_session_keyring_to_cred(struct cred *cred, struct key *keyring) 233 { 234 unsigned long flags; 235 struct key *old; 236 237 might_sleep(); 238 239 /* create an empty session keyring */ 240 if (!keyring) { 241 flags = KEY_ALLOC_QUOTA_OVERRUN; 242 if (cred->session_keyring) 243 flags = KEY_ALLOC_IN_QUOTA; 244 245 keyring = keyring_alloc("_ses", cred->uid, cred->gid, cred, 246 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ, 247 flags, NULL, NULL); 248 if (IS_ERR(keyring)) 249 return PTR_ERR(keyring); 250 } else { 251 __key_get(keyring); 252 } 253 254 /* install the keyring */ 255 old = cred->session_keyring; 256 rcu_assign_pointer(cred->session_keyring, keyring); 257 258 if (old) 259 key_put(old); 260 261 return 0; 262 } 263 264 /* 265 * Install the given keyring as the session keyring of the current task, 266 * replacing the existing one if any. If the given keyring is NULL, then 267 * install a new anonymous session keyring. 268 * 269 * Return: 0 on success; -errno on failure. 270 */ 271 static int install_session_keyring(struct key *keyring) 272 { 273 struct cred *new; 274 int ret; 275 276 new = prepare_creds(); 277 if (!new) 278 return -ENOMEM; 279 280 ret = install_session_keyring_to_cred(new, keyring); 281 if (ret < 0) { 282 abort_creds(new); 283 return ret; 284 } 285 286 return commit_creds(new); 287 } 288 289 /* 290 * Handle the fsuid changing. 291 */ 292 void key_fsuid_changed(struct task_struct *tsk) 293 { 294 /* update the ownership of the thread keyring */ 295 BUG_ON(!tsk->cred); 296 if (tsk->cred->thread_keyring) { 297 down_write(&tsk->cred->thread_keyring->sem); 298 tsk->cred->thread_keyring->uid = tsk->cred->fsuid; 299 up_write(&tsk->cred->thread_keyring->sem); 300 } 301 } 302 303 /* 304 * Handle the fsgid changing. 305 */ 306 void key_fsgid_changed(struct task_struct *tsk) 307 { 308 /* update the ownership of the thread keyring */ 309 BUG_ON(!tsk->cred); 310 if (tsk->cred->thread_keyring) { 311 down_write(&tsk->cred->thread_keyring->sem); 312 tsk->cred->thread_keyring->gid = tsk->cred->fsgid; 313 up_write(&tsk->cred->thread_keyring->sem); 314 } 315 } 316 317 /* 318 * Search the process keyrings attached to the supplied cred for the first 319 * matching key. 320 * 321 * The search criteria are the type and the match function. The description is 322 * given to the match function as a parameter, but doesn't otherwise influence 323 * the search. Typically the match function will compare the description 324 * parameter to the key's description. 325 * 326 * This can only search keyrings that grant Search permission to the supplied 327 * credentials. Keyrings linked to searched keyrings will also be searched if 328 * they grant Search permission too. Keys can only be found if they grant 329 * Search permission to the credentials. 330 * 331 * Returns a pointer to the key with the key usage count incremented if 332 * successful, -EAGAIN if we didn't find any matching key or -ENOKEY if we only 333 * matched negative keys. 334 * 335 * In the case of a successful return, the possession attribute is set on the 336 * returned key reference. 337 */ 338 key_ref_t search_my_process_keyrings(struct keyring_search_context *ctx) 339 { 340 key_ref_t key_ref, ret, err; 341 342 /* we want to return -EAGAIN or -ENOKEY if any of the keyrings were 343 * searchable, but we failed to find a key or we found a negative key; 344 * otherwise we want to return a sample error (probably -EACCES) if 345 * none of the keyrings were searchable 346 * 347 * in terms of priority: success > -ENOKEY > -EAGAIN > other error 348 */ 349 key_ref = NULL; 350 ret = NULL; 351 err = ERR_PTR(-EAGAIN); 352 353 /* search the thread keyring first */ 354 if (ctx->cred->thread_keyring) { 355 key_ref = keyring_search_aux( 356 make_key_ref(ctx->cred->thread_keyring, 1), ctx); 357 if (!IS_ERR(key_ref)) 358 goto found; 359 360 switch (PTR_ERR(key_ref)) { 361 case -EAGAIN: /* no key */ 362 case -ENOKEY: /* negative key */ 363 ret = key_ref; 364 break; 365 default: 366 err = key_ref; 367 break; 368 } 369 } 370 371 /* search the process keyring second */ 372 if (ctx->cred->process_keyring) { 373 key_ref = keyring_search_aux( 374 make_key_ref(ctx->cred->process_keyring, 1), ctx); 375 if (!IS_ERR(key_ref)) 376 goto found; 377 378 switch (PTR_ERR(key_ref)) { 379 case -EAGAIN: /* no key */ 380 if (ret) 381 break; 382 /* fall through */ 383 case -ENOKEY: /* negative key */ 384 ret = key_ref; 385 break; 386 default: 387 err = key_ref; 388 break; 389 } 390 } 391 392 /* search the session keyring */ 393 if (ctx->cred->session_keyring) { 394 rcu_read_lock(); 395 key_ref = keyring_search_aux( 396 make_key_ref(rcu_dereference(ctx->cred->session_keyring), 1), 397 ctx); 398 rcu_read_unlock(); 399 400 if (!IS_ERR(key_ref)) 401 goto found; 402 403 switch (PTR_ERR(key_ref)) { 404 case -EAGAIN: /* no key */ 405 if (ret) 406 break; 407 /* fall through */ 408 case -ENOKEY: /* negative key */ 409 ret = key_ref; 410 break; 411 default: 412 err = key_ref; 413 break; 414 } 415 } 416 /* or search the user-session keyring */ 417 else if (ctx->cred->user->session_keyring) { 418 key_ref = keyring_search_aux( 419 make_key_ref(ctx->cred->user->session_keyring, 1), 420 ctx); 421 if (!IS_ERR(key_ref)) 422 goto found; 423 424 switch (PTR_ERR(key_ref)) { 425 case -EAGAIN: /* no key */ 426 if (ret) 427 break; 428 /* fall through */ 429 case -ENOKEY: /* negative key */ 430 ret = key_ref; 431 break; 432 default: 433 err = key_ref; 434 break; 435 } 436 } 437 438 /* no key - decide on the error we're going to go for */ 439 key_ref = ret ? ret : err; 440 441 found: 442 return key_ref; 443 } 444 445 /* 446 * Search the process keyrings attached to the supplied cred for the first 447 * matching key in the manner of search_my_process_keyrings(), but also search 448 * the keys attached to the assumed authorisation key using its credentials if 449 * one is available. 450 * 451 * Return same as search_my_process_keyrings(). 452 */ 453 key_ref_t search_process_keyrings(struct keyring_search_context *ctx) 454 { 455 struct request_key_auth *rka; 456 key_ref_t key_ref, ret = ERR_PTR(-EACCES), err; 457 458 might_sleep(); 459 460 key_ref = search_my_process_keyrings(ctx); 461 if (!IS_ERR(key_ref)) 462 goto found; 463 err = key_ref; 464 465 /* if this process has an instantiation authorisation key, then we also 466 * search the keyrings of the process mentioned there 467 * - we don't permit access to request_key auth keys via this method 468 */ 469 if (ctx->cred->request_key_auth && 470 ctx->cred == current_cred() && 471 ctx->index_key.type != &key_type_request_key_auth 472 ) { 473 const struct cred *cred = ctx->cred; 474 475 /* defend against the auth key being revoked */ 476 down_read(&cred->request_key_auth->sem); 477 478 if (key_validate(ctx->cred->request_key_auth) == 0) { 479 rka = ctx->cred->request_key_auth->payload.data[0]; 480 481 ctx->cred = rka->cred; 482 key_ref = search_process_keyrings(ctx); 483 ctx->cred = cred; 484 485 up_read(&cred->request_key_auth->sem); 486 487 if (!IS_ERR(key_ref)) 488 goto found; 489 490 ret = key_ref; 491 } else { 492 up_read(&cred->request_key_auth->sem); 493 } 494 } 495 496 /* no key - decide on the error we're going to go for */ 497 if (err == ERR_PTR(-ENOKEY) || ret == ERR_PTR(-ENOKEY)) 498 key_ref = ERR_PTR(-ENOKEY); 499 else if (err == ERR_PTR(-EACCES)) 500 key_ref = ret; 501 else 502 key_ref = err; 503 504 found: 505 return key_ref; 506 } 507 508 /* 509 * See if the key we're looking at is the target key. 510 */ 511 bool lookup_user_key_possessed(const struct key *key, 512 const struct key_match_data *match_data) 513 { 514 return key == match_data->raw_data; 515 } 516 517 /* 518 * Look up a key ID given us by userspace with a given permissions mask to get 519 * the key it refers to. 520 * 521 * Flags can be passed to request that special keyrings be created if referred 522 * to directly, to permit partially constructed keys to be found and to skip 523 * validity and permission checks on the found key. 524 * 525 * Returns a pointer to the key with an incremented usage count if successful; 526 * -EINVAL if the key ID is invalid; -ENOKEY if the key ID does not correspond 527 * to a key or the best found key was a negative key; -EKEYREVOKED or 528 * -EKEYEXPIRED if the best found key was revoked or expired; -EACCES if the 529 * found key doesn't grant the requested permit or the LSM denied access to it; 530 * or -ENOMEM if a special keyring couldn't be created. 531 * 532 * In the case of a successful return, the possession attribute is set on the 533 * returned key reference. 534 */ 535 key_ref_t lookup_user_key(key_serial_t id, unsigned long lflags, 536 key_perm_t perm) 537 { 538 struct keyring_search_context ctx = { 539 .match_data.cmp = lookup_user_key_possessed, 540 .match_data.lookup_type = KEYRING_SEARCH_LOOKUP_DIRECT, 541 .flags = KEYRING_SEARCH_NO_STATE_CHECK, 542 }; 543 struct request_key_auth *rka; 544 struct key *key; 545 key_ref_t key_ref, skey_ref; 546 int ret; 547 548 try_again: 549 ctx.cred = get_current_cred(); 550 key_ref = ERR_PTR(-ENOKEY); 551 552 switch (id) { 553 case KEY_SPEC_THREAD_KEYRING: 554 if (!ctx.cred->thread_keyring) { 555 if (!(lflags & KEY_LOOKUP_CREATE)) 556 goto error; 557 558 ret = install_thread_keyring(); 559 if (ret < 0) { 560 key_ref = ERR_PTR(ret); 561 goto error; 562 } 563 goto reget_creds; 564 } 565 566 key = ctx.cred->thread_keyring; 567 __key_get(key); 568 key_ref = make_key_ref(key, 1); 569 break; 570 571 case KEY_SPEC_PROCESS_KEYRING: 572 if (!ctx.cred->process_keyring) { 573 if (!(lflags & KEY_LOOKUP_CREATE)) 574 goto error; 575 576 ret = install_process_keyring(); 577 if (ret < 0) { 578 key_ref = ERR_PTR(ret); 579 goto error; 580 } 581 goto reget_creds; 582 } 583 584 key = ctx.cred->process_keyring; 585 __key_get(key); 586 key_ref = make_key_ref(key, 1); 587 break; 588 589 case KEY_SPEC_SESSION_KEYRING: 590 if (!ctx.cred->session_keyring) { 591 /* always install a session keyring upon access if one 592 * doesn't exist yet */ 593 ret = install_user_keyrings(); 594 if (ret < 0) 595 goto error; 596 if (lflags & KEY_LOOKUP_CREATE) 597 ret = join_session_keyring(NULL); 598 else 599 ret = install_session_keyring( 600 ctx.cred->user->session_keyring); 601 602 if (ret < 0) 603 goto error; 604 goto reget_creds; 605 } else if (ctx.cred->session_keyring == 606 ctx.cred->user->session_keyring && 607 lflags & KEY_LOOKUP_CREATE) { 608 ret = join_session_keyring(NULL); 609 if (ret < 0) 610 goto error; 611 goto reget_creds; 612 } 613 614 rcu_read_lock(); 615 key = rcu_dereference(ctx.cred->session_keyring); 616 __key_get(key); 617 rcu_read_unlock(); 618 key_ref = make_key_ref(key, 1); 619 break; 620 621 case KEY_SPEC_USER_KEYRING: 622 if (!ctx.cred->user->uid_keyring) { 623 ret = install_user_keyrings(); 624 if (ret < 0) 625 goto error; 626 } 627 628 key = ctx.cred->user->uid_keyring; 629 __key_get(key); 630 key_ref = make_key_ref(key, 1); 631 break; 632 633 case KEY_SPEC_USER_SESSION_KEYRING: 634 if (!ctx.cred->user->session_keyring) { 635 ret = install_user_keyrings(); 636 if (ret < 0) 637 goto error; 638 } 639 640 key = ctx.cred->user->session_keyring; 641 __key_get(key); 642 key_ref = make_key_ref(key, 1); 643 break; 644 645 case KEY_SPEC_GROUP_KEYRING: 646 /* group keyrings are not yet supported */ 647 key_ref = ERR_PTR(-EINVAL); 648 goto error; 649 650 case KEY_SPEC_REQKEY_AUTH_KEY: 651 key = ctx.cred->request_key_auth; 652 if (!key) 653 goto error; 654 655 __key_get(key); 656 key_ref = make_key_ref(key, 1); 657 break; 658 659 case KEY_SPEC_REQUESTOR_KEYRING: 660 if (!ctx.cred->request_key_auth) 661 goto error; 662 663 down_read(&ctx.cred->request_key_auth->sem); 664 if (test_bit(KEY_FLAG_REVOKED, 665 &ctx.cred->request_key_auth->flags)) { 666 key_ref = ERR_PTR(-EKEYREVOKED); 667 key = NULL; 668 } else { 669 rka = ctx.cred->request_key_auth->payload.data[0]; 670 key = rka->dest_keyring; 671 __key_get(key); 672 } 673 up_read(&ctx.cred->request_key_auth->sem); 674 if (!key) 675 goto error; 676 key_ref = make_key_ref(key, 1); 677 break; 678 679 default: 680 key_ref = ERR_PTR(-EINVAL); 681 if (id < 1) 682 goto error; 683 684 key = key_lookup(id); 685 if (IS_ERR(key)) { 686 key_ref = ERR_CAST(key); 687 goto error; 688 } 689 690 key_ref = make_key_ref(key, 0); 691 692 /* check to see if we possess the key */ 693 ctx.index_key.type = key->type; 694 ctx.index_key.description = key->description; 695 ctx.index_key.desc_len = strlen(key->description); 696 ctx.match_data.raw_data = key; 697 kdebug("check possessed"); 698 skey_ref = search_process_keyrings(&ctx); 699 kdebug("possessed=%p", skey_ref); 700 701 if (!IS_ERR(skey_ref)) { 702 key_put(key); 703 key_ref = skey_ref; 704 } 705 706 break; 707 } 708 709 /* unlink does not use the nominated key in any way, so can skip all 710 * the permission checks as it is only concerned with the keyring */ 711 if (lflags & KEY_LOOKUP_FOR_UNLINK) { 712 ret = 0; 713 goto error; 714 } 715 716 if (!(lflags & KEY_LOOKUP_PARTIAL)) { 717 ret = wait_for_key_construction(key, true); 718 switch (ret) { 719 case -ERESTARTSYS: 720 goto invalid_key; 721 default: 722 if (perm) 723 goto invalid_key; 724 case 0: 725 break; 726 } 727 } else if (perm) { 728 ret = key_validate(key); 729 if (ret < 0) 730 goto invalid_key; 731 } 732 733 ret = -EIO; 734 if (!(lflags & KEY_LOOKUP_PARTIAL) && 735 key_read_state(key) == KEY_IS_UNINSTANTIATED) 736 goto invalid_key; 737 738 /* check the permissions */ 739 ret = key_task_permission(key_ref, ctx.cred, perm); 740 if (ret < 0) 741 goto invalid_key; 742 743 key->last_used_at = ktime_get_real_seconds(); 744 745 error: 746 put_cred(ctx.cred); 747 return key_ref; 748 749 invalid_key: 750 key_ref_put(key_ref); 751 key_ref = ERR_PTR(ret); 752 goto error; 753 754 /* if we attempted to install a keyring, then it may have caused new 755 * creds to be installed */ 756 reget_creds: 757 put_cred(ctx.cred); 758 goto try_again; 759 } 760 EXPORT_SYMBOL(lookup_user_key); 761 762 /* 763 * Join the named keyring as the session keyring if possible else attempt to 764 * create a new one of that name and join that. 765 * 766 * If the name is NULL, an empty anonymous keyring will be installed as the 767 * session keyring. 768 * 769 * Named session keyrings are joined with a semaphore held to prevent the 770 * keyrings from going away whilst the attempt is made to going them and also 771 * to prevent a race in creating compatible session keyrings. 772 */ 773 long join_session_keyring(const char *name) 774 { 775 const struct cred *old; 776 struct cred *new; 777 struct key *keyring; 778 long ret, serial; 779 780 new = prepare_creds(); 781 if (!new) 782 return -ENOMEM; 783 old = current_cred(); 784 785 /* if no name is provided, install an anonymous keyring */ 786 if (!name) { 787 ret = install_session_keyring_to_cred(new, NULL); 788 if (ret < 0) 789 goto error; 790 791 serial = new->session_keyring->serial; 792 ret = commit_creds(new); 793 if (ret == 0) 794 ret = serial; 795 goto okay; 796 } 797 798 /* allow the user to join or create a named keyring */ 799 mutex_lock(&key_session_mutex); 800 801 /* look for an existing keyring of this name */ 802 keyring = find_keyring_by_name(name, false); 803 if (PTR_ERR(keyring) == -ENOKEY) { 804 /* not found - try and create a new one */ 805 keyring = keyring_alloc( 806 name, old->uid, old->gid, old, 807 KEY_POS_ALL | KEY_USR_VIEW | KEY_USR_READ | KEY_USR_LINK, 808 KEY_ALLOC_IN_QUOTA, NULL, NULL); 809 if (IS_ERR(keyring)) { 810 ret = PTR_ERR(keyring); 811 goto error2; 812 } 813 } else if (IS_ERR(keyring)) { 814 ret = PTR_ERR(keyring); 815 goto error2; 816 } else if (keyring == new->session_keyring) { 817 ret = 0; 818 goto error3; 819 } 820 821 /* we've got a keyring - now to install it */ 822 ret = install_session_keyring_to_cred(new, keyring); 823 if (ret < 0) 824 goto error3; 825 826 commit_creds(new); 827 mutex_unlock(&key_session_mutex); 828 829 ret = keyring->serial; 830 key_put(keyring); 831 okay: 832 return ret; 833 834 error3: 835 key_put(keyring); 836 error2: 837 mutex_unlock(&key_session_mutex); 838 error: 839 abort_creds(new); 840 return ret; 841 } 842 843 /* 844 * Replace a process's session keyring on behalf of one of its children when 845 * the target process is about to resume userspace execution. 846 */ 847 void key_change_session_keyring(struct callback_head *twork) 848 { 849 const struct cred *old = current_cred(); 850 struct cred *new = container_of(twork, struct cred, rcu); 851 852 if (unlikely(current->flags & PF_EXITING)) { 853 put_cred(new); 854 return; 855 } 856 857 new-> uid = old-> uid; 858 new-> euid = old-> euid; 859 new-> suid = old-> suid; 860 new->fsuid = old->fsuid; 861 new-> gid = old-> gid; 862 new-> egid = old-> egid; 863 new-> sgid = old-> sgid; 864 new->fsgid = old->fsgid; 865 new->user = get_uid(old->user); 866 new->user_ns = get_user_ns(old->user_ns); 867 new->group_info = get_group_info(old->group_info); 868 869 new->securebits = old->securebits; 870 new->cap_inheritable = old->cap_inheritable; 871 new->cap_permitted = old->cap_permitted; 872 new->cap_effective = old->cap_effective; 873 new->cap_ambient = old->cap_ambient; 874 new->cap_bset = old->cap_bset; 875 876 new->jit_keyring = old->jit_keyring; 877 new->thread_keyring = key_get(old->thread_keyring); 878 new->process_keyring = key_get(old->process_keyring); 879 880 security_transfer_creds(new, old); 881 882 commit_creds(new); 883 } 884 885 /* 886 * Make sure that root's user and user-session keyrings exist. 887 */ 888 static int __init init_root_keyring(void) 889 { 890 return install_user_keyrings(); 891 } 892 893 late_initcall(init_root_keyring); 894