security/keys/keyctl.c

   1 /* Userspace key control operations
   2  *
   3  * Copyright (C) 2004-5 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/slab.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/key.h>
  18 #include <linux/keyctl.h>
  19 #include <linux/fs.h>
  20 #include <linux/capability.h>
  21 #include <linux/string.h>
  22 #include <linux/err.h>
  23 #include <linux/vmalloc.h>
  24 #include <linux/security.h>
  25 #include <asm/uaccess.h>
  26 #include "internal.h"
  27
  28 static int key_get_type_from_user(char *type,
  29                                   const char __user *_type,
  30                                   unsigned len)
  31 {
  32         int ret;
  33
  34         ret = strncpy_from_user(type, _type, len);
  35         if (ret < 0)
  36                 return ret;
  37         if (ret == 0 || ret >= len)
  38                 return -EINVAL;
  39         if (type[0] == '.')
  40                 return -EPERM;
  41         type[len - 1] = '\0';
  42         return 0;
  43 }
  44
  45 /*
  46  * Extract the description of a new key from userspace and either add it as a
  47  * new key to the specified keyring or update a matching key in that keyring.
  48  *
  49  * If the description is NULL or an empty string, the key type is asked to
  50  * generate one from the payload.
  51  *
  52  * The keyring must be writable so that we can attach the key to it.
  53  *
  54  * If successful, the new key's serial number is returned, otherwise an error
  55  * code is returned.
  56  */
  57 SYSCALL_DEFINE5(add_key, const char __user *, _type,
  58                 const char __user *, _description,
  59                 const void __user *, _payload,
  60                 size_t, plen,
  61                 key_serial_t, ringid)
  62 {
  63         key_ref_t keyring_ref, key_ref;
  64         char type[32], *description;
  65         void *payload;
  66         long ret;
  67         bool vm;
  68
  69         ret = -EINVAL;
  70         if (plen > 1024 * 1024 - 1)
  71                 goto error;
  72
  73         /* draw all the data into kernel space */
  74         ret = key_get_type_from_user(type, _type, sizeof(type));
  75         if (ret < 0)
  76                 goto error;
  77
  78         description = NULL;
  79         if (_description) {
  80                 description = strndup_user(_description, PAGE_SIZE);
  81                 if (IS_ERR(description)) {
  82                         ret = PTR_ERR(description);
  83                         goto error;
  84                 }
  85                 if (!*description) {
  86                         kfree(description);
  87                         description = NULL;
  88                 }
  89         }
  90
  91         /* pull the payload in if one was supplied */
  92         payload = NULL;
  93
  94         vm = false;
  95         if (_payload) {
  96                 ret = -ENOMEM;
  97                 payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
  98                 if (!payload) {
  99                         if (plen <= PAGE_SIZE)
 100                                 goto error2;
 101                         vm = true;
 102                         payload = vmalloc(plen);
 103                         if (!payload)
 104                                 goto error2;
 105                 }
 106
 107                 ret = -EFAULT;
 108                 if (copy_from_user(payload, _payload, plen) != 0)
 109                         goto error3;
 110         }
 111
 112         /* find the target keyring (which must be writable) */
 113         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 114         if (IS_ERR(keyring_ref)) {
 115                 ret = PTR_ERR(keyring_ref);
 116                 goto error3;
 117         }
 118
 119         /* create or update the requested key and add it to the target
 120          * keyring */
 121         key_ref = key_create_or_update(keyring_ref, type, description,
 122                                        payload, plen, KEY_PERM_UNDEF,
 123                                        KEY_ALLOC_IN_QUOTA);
 124         if (!IS_ERR(key_ref)) {
 125                 ret = key_ref_to_ptr(key_ref)->serial;
 126                 key_ref_put(key_ref);
 127         }
 128         else {
 129                 ret = PTR_ERR(key_ref);
 130         }
 131
 132         key_ref_put(keyring_ref);
 133  error3:
 134         if (!vm)
 135                 kfree(payload);
 136         else
 137                 vfree(payload);
 138  error2:
 139         kfree(description);
 140  error:
 141         return ret;
 142 }
 143
 144 /*
 145  * Search the process keyrings and keyring trees linked from those for a
 146  * matching key.  Keyrings must have appropriate Search permission to be
 147  * searched.
 148  *
 149  * If a key is found, it will be attached to the destination keyring if there's
 150  * one specified and the serial number of the key will be returned.
 151  *
 152  * If no key is found, /sbin/request-key will be invoked if _callout_info is
 153  * non-NULL in an attempt to create a key.  The _callout_info string will be
 154  * passed to /sbin/request-key to aid with completing the request.  If the
 155  * _callout_info string is "" then it will be changed to "-".
 156  */
 157 SYSCALL_DEFINE4(request_key, const char __user *, _type,
 158                 const char __user *, _description,
 159                 const char __user *, _callout_info,
 160                 key_serial_t, destringid)
 161 {
 162         struct key_type *ktype;
 163         struct key *key;
 164         key_ref_t dest_ref;
 165         size_t callout_len;
 166         char type[32], *description, *callout_info;
 167         long ret;
 168
 169         /* pull the type into kernel space */
 170         ret = key_get_type_from_user(type, _type, sizeof(type));
 171         if (ret < 0)
 172                 goto error;
 173
 174         /* pull the description into kernel space */
 175         description = strndup_user(_description, PAGE_SIZE);
 176         if (IS_ERR(description)) {
 177                 ret = PTR_ERR(description);
 178                 goto error;
 179         }
 180
 181         /* pull the callout info into kernel space */
 182         callout_info = NULL;
 183         callout_len = 0;
 184         if (_callout_info) {
 185                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
 186                 if (IS_ERR(callout_info)) {
 187                         ret = PTR_ERR(callout_info);
 188                         goto error2;
 189                 }
 190                 callout_len = strlen(callout_info);
 191         }
 192
 193         /* get the destination keyring if specified */
 194         dest_ref = NULL;
 195         if (destringid) {
 196                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 197                                            KEY_WRITE);
 198                 if (IS_ERR(dest_ref)) {
 199                         ret = PTR_ERR(dest_ref);
 200                         goto error3;
 201                 }
 202         }
 203
 204         /* find the key type */
 205         ktype = key_type_lookup(type);
 206         if (IS_ERR(ktype)) {
 207                 ret = PTR_ERR(ktype);
 208                 goto error4;
 209         }
 210
 211         /* do the search */
 212         key = request_key_and_link(ktype, description, callout_info,
 213                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
 214                                    KEY_ALLOC_IN_QUOTA);
 215         if (IS_ERR(key)) {
 216                 ret = PTR_ERR(key);
 217                 goto error5;
 218         }
 219
 220         /* wait for the key to finish being constructed */
 221         ret = wait_for_key_construction(key, 1);
 222         if (ret < 0)
 223                 goto error6;
 224
 225         ret = key->serial;
 226
 227 error6:
 228         key_put(key);
 229 error5:
 230         key_type_put(ktype);
 231 error4:
 232         key_ref_put(dest_ref);
 233 error3:
 234         kfree(callout_info);
 235 error2:
 236         kfree(description);
 237 error:
 238         return ret;
 239 }
 240
 241 /*
 242  * Get the ID of the specified process keyring.
 243  *
 244  * The requested keyring must have search permission to be found.
 245  *
 246  * If successful, the ID of the requested keyring will be returned.
 247  */
 248 long keyctl_get_keyring_ID(key_serial_t id, int create)
 249 {
 250         key_ref_t key_ref;
 251         unsigned long lflags;
 252         long ret;
 253
 254         lflags = create ? KEY_LOOKUP_CREATE : 0;
 255         key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 256         if (IS_ERR(key_ref)) {
 257                 ret = PTR_ERR(key_ref);
 258                 goto error;
 259         }
 260
 261         ret = key_ref_to_ptr(key_ref)->serial;
 262         key_ref_put(key_ref);
 263 error:
 264         return ret;
 265 }
 266
 267 /*
 268  * Join a (named) session keyring.
 269  *
 270  * Create and join an anonymous session keyring or join a named session
 271  * keyring, creating it if necessary.  A named session keyring must have Search
 272  * permission for it to be joined.  Session keyrings without this permit will
 273  * be skipped over.
 274  *
 275  * If successful, the ID of the joined session keyring will be returned.
 276  */
 277 long keyctl_join_session_keyring(const char __user *_name)
 278 {
 279         char *name;
 280         long ret;
 281
 282         /* fetch the name from userspace */
 283         name = NULL;
 284         if (_name) {
 285                 name = strndup_user(_name, PAGE_SIZE);
 286                 if (IS_ERR(name)) {
 287                         ret = PTR_ERR(name);
 288                         goto error;
 289                 }
 290         }
 291
 292         /* join the session */
 293         ret = join_session_keyring(name);
 294         kfree(name);
 295
 296 error:
 297         return ret;
 298 }
 299
 300 /*
 301  * Update a key's data payload from the given data.
 302  *
 303  * The key must grant the caller Write permission and the key type must support
 304  * updating for this to work.  A negative key can be positively instantiated
 305  * with this call.
 306  *
 307  * If successful, 0 will be returned.  If the key type does not support
 308  * updating, then -EOPNOTSUPP will be returned.
 309  */
 310 long keyctl_update_key(key_serial_t id,
 311                        const void __user *_payload,
 312                        size_t plen)
 313 {
 314         key_ref_t key_ref;
 315         void *payload;
 316         long ret;
 317
 318         ret = -EINVAL;
 319         if (plen > PAGE_SIZE)
 320                 goto error;
 321
 322         /* pull the payload in if one was supplied */
 323         payload = NULL;
 324         if (_payload) {
 325                 ret = -ENOMEM;
 326                 payload = kmalloc(plen, GFP_KERNEL);
 327                 if (!payload)
 328                         goto error;
 329
 330                 ret = -EFAULT;
 331                 if (copy_from_user(payload, _payload, plen) != 0)
 332                         goto error2;
 333         }
 334
 335         /* find the target key (which must be writable) */
 336         key_ref = lookup_user_key(id, 0, KEY_WRITE);
 337         if (IS_ERR(key_ref)) {
 338                 ret = PTR_ERR(key_ref);
 339                 goto error2;
 340         }
 341
 342         /* update the key */
 343         ret = key_update(key_ref, payload, plen);
 344
 345         key_ref_put(key_ref);
 346 error2:
 347         kfree(payload);
 348 error:
 349         return ret;
 350 }
 351
 352 /*
 353  * Revoke a key.
 354  *
 355  * The key must be grant the caller Write or Setattr permission for this to
 356  * work.  The key type should give up its quota claim when revoked.  The key
 357  * and any links to the key will be automatically garbage collected after a
 358  * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 359  *
 360  * If successful, 0 is returned.
 361  */
 362 long keyctl_revoke_key(key_serial_t id)
 363 {
 364         key_ref_t key_ref;
 365         long ret;
 366
 367         key_ref = lookup_user_key(id, 0, KEY_WRITE);
 368         if (IS_ERR(key_ref)) {
 369                 ret = PTR_ERR(key_ref);
 370                 if (ret != -EACCES)
 371                         goto error;
 372                 key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 373                 if (IS_ERR(key_ref)) {
 374                         ret = PTR_ERR(key_ref);
 375                         goto error;
 376                 }
 377         }
 378
 379         key_revoke(key_ref_to_ptr(key_ref));
 380         ret = 0;
 381
 382         key_ref_put(key_ref);
 383 error:
 384         return ret;
 385 }
 386
 387 /*
 388  * Invalidate a key.
 389  *
 390  * The key must be grant the caller Invalidate permission for this to work.
 391  * The key and any links to the key will be automatically garbage collected
 392  * immediately.
 393  *
 394  * If successful, 0 is returned.
 395  */
 396 long keyctl_invalidate_key(key_serial_t id)
 397 {
 398         key_ref_t key_ref;
 399         long ret;
 400
 401         kenter("%d", id);
 402
 403         key_ref = lookup_user_key(id, 0, KEY_SEARCH);
 404         if (IS_ERR(key_ref)) {
 405                 ret = PTR_ERR(key_ref);
 406                 goto error;
 407         }
 408
 409         key_invalidate(key_ref_to_ptr(key_ref));
 410         ret = 0;
 411
 412         key_ref_put(key_ref);
 413 error:
 414         kleave(" = %ld", ret);
 415         return ret;
 416 }
 417
 418 /*
 419  * Clear the specified keyring, creating an empty process keyring if one of the
 420  * special keyring IDs is used.
 421  *
 422  * The keyring must grant the caller Write permission for this to work.  If
 423  * successful, 0 will be returned.
 424  */
 425 long keyctl_keyring_clear(key_serial_t ringid)
 426 {
 427         key_ref_t keyring_ref;
 428         long ret;
 429
 430         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 431         if (IS_ERR(keyring_ref)) {
 432                 ret = PTR_ERR(keyring_ref);
 433
 434                 /* Root is permitted to invalidate certain special keyrings */
 435                 if (capable(CAP_SYS_ADMIN)) {
 436                         keyring_ref = lookup_user_key(ringid, 0, 0);
 437                         if (IS_ERR(keyring_ref))
 438                                 goto error;
 439                         if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 440                                      &key_ref_to_ptr(keyring_ref)->flags))
 441                                 goto clear;
 442                         goto error_put;
 443                 }
 444
 445                 goto error;
 446         }
 447
 448 clear:
 449         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 450 error_put:
 451         key_ref_put(keyring_ref);
 452 error:
 453         return ret;
 454 }
 455
 456 /*
 457  * Create a link from a keyring to a key if there's no matching key in the
 458  * keyring, otherwise replace the link to the matching key with a link to the
 459  * new key.
 460  *
 461  * The key must grant the caller Link permission and the the keyring must grant
 462  * the caller Write permission.  Furthermore, if an additional link is created,
 463  * the keyring's quota will be extended.
 464  *
 465  * If successful, 0 will be returned.
 466  */
 467 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 468 {
 469         key_ref_t keyring_ref, key_ref;
 470         long ret;
 471
 472         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 473         if (IS_ERR(keyring_ref)) {
 474                 ret = PTR_ERR(keyring_ref);
 475                 goto error;
 476         }
 477
 478         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 479         if (IS_ERR(key_ref)) {
 480                 ret = PTR_ERR(key_ref);
 481                 goto error2;
 482         }
 483
 484         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 485
 486         key_ref_put(key_ref);
 487 error2:
 488         key_ref_put(keyring_ref);
 489 error:
 490         return ret;
 491 }
 492
 493 /*
 494  * Unlink a key from a keyring.
 495  *
 496  * The keyring must grant the caller Write permission for this to work; the key
 497  * itself need not grant the caller anything.  If the last link to a key is
 498  * removed then that key will be scheduled for destruction.
 499  *
 500  * If successful, 0 will be returned.
 501  */
 502 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 503 {
 504         key_ref_t keyring_ref, key_ref;
 505         long ret;
 506
 507         keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 508         if (IS_ERR(keyring_ref)) {
 509                 ret = PTR_ERR(keyring_ref);
 510                 goto error;
 511         }
 512
 513         key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 514         if (IS_ERR(key_ref)) {
 515                 ret = PTR_ERR(key_ref);
 516                 goto error2;
 517         }
 518
 519         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 520
 521         key_ref_put(key_ref);
 522 error2:
 523         key_ref_put(keyring_ref);
 524 error:
 525         return ret;
 526 }
 527
 528 /*
 529  * Return a description of a key to userspace.
 530  *
 531  * The key must grant the caller View permission for this to work.
 532  *
 533  * If there's a buffer, we place up to buflen bytes of data into it formatted
 534  * in the following way:
 535  *
 536  *      type;uid;gid;perm;description<NUL>
 537  *
 538  * If successful, we return the amount of description available, irrespective
 539  * of how much we may have copied into the buffer.
 540  */
 541 long keyctl_describe_key(key_serial_t keyid,
 542                          char __user *buffer,
 543                          size_t buflen)
 544 {
 545         struct key *key, *instkey;
 546         key_ref_t key_ref;
 547         char *tmpbuf;
 548         long ret;
 549
 550         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 551         if (IS_ERR(key_ref)) {
 552                 /* viewing a key under construction is permitted if we have the
 553                  * authorisation token handy */
 554                 if (PTR_ERR(key_ref) == -EACCES) {
 555                         instkey = key_get_instantiation_authkey(keyid);
 556                         if (!IS_ERR(instkey)) {
 557                                 key_put(instkey);
 558                                 key_ref = lookup_user_key(keyid,
 559                                                           KEY_LOOKUP_PARTIAL,
 560                                                           0);
 561                                 if (!IS_ERR(key_ref))
 562                                         goto okay;
 563                         }
 564                 }
 565
 566                 ret = PTR_ERR(key_ref);
 567                 goto error;
 568         }
 569
 570 okay:
 571         /* calculate how much description we're going to return */
 572         ret = -ENOMEM;
 573         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 574         if (!tmpbuf)
 575                 goto error2;
 576
 577         key = key_ref_to_ptr(key_ref);
 578
 579         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 580                        "%s;%d;%d;%08x;%s",
 581                        key->type->name,
 582                        key->uid,
 583                        key->gid,
 584                        key->perm,
 585                        key->description ?: "");
 586
 587         /* include a NUL char at the end of the data */
 588         if (ret > PAGE_SIZE - 1)
 589                 ret = PAGE_SIZE - 1;
 590         tmpbuf[ret] = 0;
 591         ret++;
 592
 593         /* consider returning the data */
 594         if (buffer && buflen > 0) {
 595                 if (buflen > ret)
 596                         buflen = ret;
 597
 598                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 599                         ret = -EFAULT;
 600         }
 601
 602         kfree(tmpbuf);
 603 error2:
 604         key_ref_put(key_ref);
 605 error:
 606         return ret;
 607 }
 608
 609 /*
 610  * Search the specified keyring and any keyrings it links to for a matching
 611  * key.  Only keyrings that grant the caller Search permission will be searched
 612  * (this includes the starting keyring).  Only keys with Search permission can
 613  * be found.
 614  *
 615  * If successful, the found key will be linked to the destination keyring if
 616  * supplied and the key has Link permission, and the found key ID will be
 617  * returned.
 618  */
 619 long keyctl_keyring_search(key_serial_t ringid,
 620                            const char __user *_type,
 621                            const char __user *_description,
 622                            key_serial_t destringid)
 623 {
 624         struct key_type *ktype;
 625         key_ref_t keyring_ref, key_ref, dest_ref;
 626         char type[32], *description;
 627         long ret;
 628
 629         /* pull the type and description into kernel space */
 630         ret = key_get_type_from_user(type, _type, sizeof(type));
 631         if (ret < 0)
 632                 goto error;
 633
 634         description = strndup_user(_description, PAGE_SIZE);
 635         if (IS_ERR(description)) {
 636                 ret = PTR_ERR(description);
 637                 goto error;
 638         }
 639
 640         /* get the keyring at which to begin the search */
 641         keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 642         if (IS_ERR(keyring_ref)) {
 643                 ret = PTR_ERR(keyring_ref);
 644                 goto error2;
 645         }
 646
 647         /* get the destination keyring if specified */
 648         dest_ref = NULL;
 649         if (destringid) {
 650                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 651                                            KEY_WRITE);
 652                 if (IS_ERR(dest_ref)) {
 653                         ret = PTR_ERR(dest_ref);
 654                         goto error3;
 655                 }
 656         }
 657
 658         /* find the key type */
 659         ktype = key_type_lookup(type);
 660         if (IS_ERR(ktype)) {
 661                 ret = PTR_ERR(ktype);
 662                 goto error4;
 663         }
 664
 665         /* do the search */
 666         key_ref = keyring_search(keyring_ref, ktype, description);
 667         if (IS_ERR(key_ref)) {
 668                 ret = PTR_ERR(key_ref);
 669
 670                 /* treat lack or presence of a negative key the same */
 671                 if (ret == -EAGAIN)
 672                         ret = -ENOKEY;
 673                 goto error5;
 674         }
 675
 676         /* link the resulting key to the destination keyring if we can */
 677         if (dest_ref) {
 678                 ret = key_permission(key_ref, KEY_LINK);
 679                 if (ret < 0)
 680                         goto error6;
 681
 682                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 683                 if (ret < 0)
 684                         goto error6;
 685         }
 686
 687         ret = key_ref_to_ptr(key_ref)->serial;
 688
 689 error6:
 690         key_ref_put(key_ref);
 691 error5:
 692         key_type_put(ktype);
 693 error4:
 694         key_ref_put(dest_ref);
 695 error3:
 696         key_ref_put(keyring_ref);
 697 error2:
 698         kfree(description);
 699 error:
 700         return ret;
 701 }
 702
 703 /*
 704  * Read a key's payload.
 705  *
 706  * The key must either grant the caller Read permission, or it must grant the
 707  * caller Search permission when searched for from the process keyrings.
 708  *
 709  * If successful, we place up to buflen bytes of data into the buffer, if one
 710  * is provided, and return the amount of data that is available in the key,
 711  * irrespective of how much we copied into the buffer.
 712  */
 713 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 714 {
 715         struct key *key;
 716         key_ref_t key_ref;
 717         long ret;
 718
 719         /* find the key first */
 720         key_ref = lookup_user_key(keyid, 0, 0);
 721         if (IS_ERR(key_ref)) {
 722                 ret = -ENOKEY;
 723                 goto error;
 724         }
 725
 726         key = key_ref_to_ptr(key_ref);
 727
 728         /* see if we can read it directly */
 729         ret = key_permission(key_ref, KEY_READ);
 730         if (ret == 0)
 731                 goto can_read_key;
 732         if (ret != -EACCES)
 733                 goto error;
 734
 735         /* we can't; see if it's searchable from this process's keyrings
 736          * - we automatically take account of the fact that it may be
 737          *   dangling off an instantiation key
 738          */
 739         if (!is_key_possessed(key_ref)) {
 740                 ret = -EACCES;
 741                 goto error2;
 742         }
 743
 744         /* the key is probably readable - now try to read it */
 745 can_read_key:
 746         ret = key_validate(key);
 747         if (ret == 0) {
 748                 ret = -EOPNOTSUPP;
 749                 if (key->type->read) {
 750                         /* read the data with the semaphore held (since we
 751                          * might sleep) */
 752                         down_read(&key->sem);
 753                         ret = key->type->read(key, buffer, buflen);
 754                         up_read(&key->sem);
 755                 }
 756         }
 757
 758 error2:
 759         key_put(key);
 760 error:
 761         return ret;
 762 }
 763
 764 /*
 765  * Change the ownership of a key
 766  *
 767  * The key must grant the caller Setattr permission for this to work, though
 768  * the key need not be fully instantiated yet.  For the UID to be changed, or
 769  * for the GID to be changed to a group the caller is not a member of, the
 770  * caller must have sysadmin capability.  If either uid or gid is -1 then that
 771  * attribute is not changed.
 772  *
 773  * If the UID is to be changed, the new user must have sufficient quota to
 774  * accept the key.  The quota deduction will be removed from the old user to
 775  * the new user should the attribute be changed.
 776  *
 777  * If successful, 0 will be returned.
 778  */
 779 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 780 {
 781         struct key_user *newowner, *zapowner = NULL;
 782         struct key *key;
 783         key_ref_t key_ref;
 784         long ret;
 785
 786         ret = 0;
 787         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 788                 goto error;
 789
 790         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 791                                   KEY_SETATTR);
 792         if (IS_ERR(key_ref)) {
 793                 ret = PTR_ERR(key_ref);
 794                 goto error;
 795         }
 796
 797         key = key_ref_to_ptr(key_ref);
 798
 799         /* make the changes with the locks held to prevent chown/chown races */
 800         ret = -EACCES;
 801         down_write(&key->sem);
 802
 803         if (!capable(CAP_SYS_ADMIN)) {
 804                 /* only the sysadmin can chown a key to some other UID */
 805                 if (uid != (uid_t) -1 && key->uid != uid)
 806                         goto error_put;
 807
 808                 /* only the sysadmin can set the key's GID to a group other
 809                  * than one of those that the current process subscribes to */
 810                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 811                         goto error_put;
 812         }
 813
 814         /* change the UID */
 815         if (uid != (uid_t) -1 && uid != key->uid) {
 816                 ret = -ENOMEM;
 817                 newowner = key_user_lookup(uid, current_user_ns());
 818                 if (!newowner)
 819                         goto error_put;
 820
 821                 /* transfer the quota burden to the new user */
 822                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 823                         unsigned maxkeys = (uid == 0) ?
 824                                 key_quota_root_maxkeys : key_quota_maxkeys;
 825                         unsigned maxbytes = (uid == 0) ?
 826                                 key_quota_root_maxbytes : key_quota_maxbytes;
 827
 828                         spin_lock(&newowner->lock);
 829                         if (newowner->qnkeys + 1 >= maxkeys ||
 830                             newowner->qnbytes + key->quotalen >= maxbytes ||
 831                             newowner->qnbytes + key->quotalen <
 832                             newowner->qnbytes)
 833                                 goto quota_overrun;
 834
 835                         newowner->qnkeys++;
 836                         newowner->qnbytes += key->quotalen;
 837                         spin_unlock(&newowner->lock);
 838
 839                         spin_lock(&key->user->lock);
 840                         key->user->qnkeys--;
 841                         key->user->qnbytes -= key->quotalen;
 842                         spin_unlock(&key->user->lock);
 843                 }
 844
 845                 atomic_dec(&key->user->nkeys);
 846                 atomic_inc(&newowner->nkeys);
 847
 848                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 849                         atomic_dec(&key->user->nikeys);
 850                         atomic_inc(&newowner->nikeys);
 851                 }
 852
 853                 zapowner = key->user;
 854                 key->user = newowner;
 855                 key->uid = uid;
 856         }
 857
 858         /* change the GID */
 859         if (gid != (gid_t) -1)
 860                 key->gid = gid;
 861
 862         ret = 0;
 863
 864 error_put:
 865         up_write(&key->sem);
 866         key_put(key);
 867         if (zapowner)
 868                 key_user_put(zapowner);
 869 error:
 870         return ret;
 871
 872 quota_overrun:
 873         spin_unlock(&newowner->lock);
 874         zapowner = newowner;
 875         ret = -EDQUOT;
 876         goto error_put;
 877 }
 878
 879 /*
 880  * Change the permission mask on a key.
 881  *
 882  * The key must grant the caller Setattr permission for this to work, though
 883  * the key need not be fully instantiated yet.  If the caller does not have
 884  * sysadmin capability, it may only change the permission on keys that it owns.
 885  */
 886 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 887 {
 888         struct key *key;
 889         key_ref_t key_ref;
 890         long ret;
 891
 892         ret = -EINVAL;
 893         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 894                 goto error;
 895
 896         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 897                                   KEY_SETATTR);
 898         if (IS_ERR(key_ref)) {
 899                 ret = PTR_ERR(key_ref);
 900                 goto error;
 901         }
 902
 903         key = key_ref_to_ptr(key_ref);
 904
 905         /* make the changes with the locks held to prevent chown/chmod races */
 906         ret = -EACCES;
 907         down_write(&key->sem);
 908
 909         /* if we're not the sysadmin, we can only change a key that we own */
 910         if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 911                 key->perm = perm;
 912                 ret = 0;
 913         }
 914
 915         up_write(&key->sem);
 916         key_put(key);
 917 error:
 918         return ret;
 919 }
 920
 921 /*
 922  * Get the destination keyring for instantiation and check that the caller has
 923  * Write permission on it.
 924  */
 925 static long get_instantiation_keyring(key_serial_t ringid,
 926                                       struct request_key_auth *rka,
 927                                       struct key **_dest_keyring)
 928 {
 929         key_ref_t dkref;
 930
 931         *_dest_keyring = NULL;
 932
 933         /* just return a NULL pointer if we weren't asked to make a link */
 934         if (ringid == 0)
 935                 return 0;
 936
 937         /* if a specific keyring is nominated by ID, then use that */
 938         if (ringid > 0) {
 939                 dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 940                 if (IS_ERR(dkref))
 941                         return PTR_ERR(dkref);
 942                 *_dest_keyring = key_ref_to_ptr(dkref);
 943                 return 0;
 944         }
 945
 946         if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 947                 return -EINVAL;
 948
 949         /* otherwise specify the destination keyring recorded in the
 950          * authorisation key (any KEY_SPEC_*_KEYRING) */
 951         if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 952                 *_dest_keyring = key_get(rka->dest_keyring);
 953                 return 0;
 954         }
 955
 956         return -ENOKEY;
 957 }
 958
 959 /*
 960  * Change the request_key authorisation key on the current process.
 961  */
 962 static int keyctl_change_reqkey_auth(struct key *key)
 963 {
 964         struct cred *new;
 965
 966         new = prepare_creds();
 967         if (!new)
 968                 return -ENOMEM;
 969
 970         key_put(new->request_key_auth);
 971         new->request_key_auth = key_get(key);
 972
 973         return commit_creds(new);
 974 }
 975
 976 /*
 977  * Copy the iovec data from userspace
 978  */
 979 static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
 980                                  unsigned ioc)
 981 {
 982         for (; ioc > 0; ioc--) {
 983                 if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
 984                         return -EFAULT;
 985                 buffer += iov->iov_len;
 986                 iov++;
 987         }
 988         return 0;
 989 }
 990
 991 /*
 992  * Instantiate a key with the specified payload and link the key into the
 993  * destination keyring if one is given.
 994  *
 995  * The caller must have the appropriate instantiation permit set for this to
 996  * work (see keyctl_assume_authority).  No other permissions are required.
 997  *
 998  * If successful, 0 will be returned.
 999  */
1000 long keyctl_instantiate_key_common(key_serial_t id,
1001                                    const struct iovec *payload_iov,
1002                                    unsigned ioc,
1003                                    size_t plen,
1004                                    key_serial_t ringid)
1005 {
1006         const struct cred *cred = current_cred();
1007         struct request_key_auth *rka;
1008         struct key *instkey, *dest_keyring;
1009         void *payload;
1010         long ret;
1011         bool vm = false;
1012
1013         kenter("%d,,%zu,%d", id, plen, ringid);
1014
1015         ret = -EINVAL;
1016         if (plen > 1024 * 1024 - 1)
1017                 goto error;
1018
1019         /* the appropriate instantiation authorisation key must have been
1020          * assumed before calling this */
1021         ret = -EPERM;
1022         instkey = cred->request_key_auth;
1023         if (!instkey)
1024                 goto error;
1025
1026         rka = instkey->payload.data;
1027         if (rka->target_key->serial != id)
1028                 goto error;
1029
1030         /* pull the payload in if one was supplied */
1031         payload = NULL;
1032
1033         if (payload_iov) {
1034                 ret = -ENOMEM;
1035                 payload = kmalloc(plen, GFP_KERNEL);
1036                 if (!payload) {
1037                         if (plen <= PAGE_SIZE)
1038                                 goto error;
1039                         vm = true;
1040                         payload = vmalloc(plen);
1041                         if (!payload)
1042                                 goto error;
1043                 }
1044
1045                 ret = copy_from_user_iovec(payload, payload_iov, ioc);
1046                 if (ret < 0)
1047                         goto error2;
1048         }
1049
1050         /* find the destination keyring amongst those belonging to the
1051          * requesting task */
1052         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1053         if (ret < 0)
1054                 goto error2;
1055
1056         /* instantiate the key and link it into a keyring */
1057         ret = key_instantiate_and_link(rka->target_key, payload, plen,
1058                                        dest_keyring, instkey);
1059
1060         key_put(dest_keyring);
1061
1062         /* discard the assumed authority if it's just been disabled by
1063          * instantiation of the key */
1064         if (ret == 0)
1065                 keyctl_change_reqkey_auth(NULL);
1066
1067 error2:
1068         if (!vm)
1069                 kfree(payload);
1070         else
1071                 vfree(payload);
1072 error:
1073         return ret;
1074 }
1075
1076 /*
1077  * Instantiate a key with the specified payload and link the key into the
1078  * destination keyring if one is given.
1079  *
1080  * The caller must have the appropriate instantiation permit set for this to
1081  * work (see keyctl_assume_authority).  No other permissions are required.
1082  *
1083  * If successful, 0 will be returned.
1084  */
1085 long keyctl_instantiate_key(key_serial_t id,
1086                             const void __user *_payload,
1087                             size_t plen,
1088                             key_serial_t ringid)
1089 {
1090         if (_payload && plen) {
1091                 struct iovec iov[1] = {
1092                         [0].iov_base = (void __user *)_payload,
1093                         [0].iov_len  = plen
1094                 };
1095
1096                 return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1097         }
1098
1099         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1100 }
1101
1102 /*
1103  * Instantiate a key with the specified multipart payload and link the key into
1104  * the destination keyring if one is given.
1105  *
1106  * The caller must have the appropriate instantiation permit set for this to
1107  * work (see keyctl_assume_authority).  No other permissions are required.
1108  *
1109  * If successful, 0 will be returned.
1110  */
1111 long keyctl_instantiate_key_iov(key_serial_t id,
1112                                 const struct iovec __user *_payload_iov,
1113                                 unsigned ioc,
1114                                 key_serial_t ringid)
1115 {
1116         struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1117         long ret;
1118
1119         if (!_payload_iov || !ioc)
1120                 goto no_payload;
1121
1122         ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1123                                     ARRAY_SIZE(iovstack), iovstack, &iov);
1124         if (ret < 0)
1125                 return ret;
1126         if (ret == 0)
1127                 goto no_payload_free;
1128
1129         ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1130
1131         if (iov != iovstack)
1132                 kfree(iov);
1133         return ret;
1134
1135 no_payload_free:
1136         if (iov != iovstack)
1137                 kfree(iov);
1138 no_payload:
1139         return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1140 }
1141
1142 /*
1143  * Negatively instantiate the key with the given timeout (in seconds) and link
1144  * the key into the destination keyring if one is given.
1145  *
1146  * The caller must have the appropriate instantiation permit set for this to
1147  * work (see keyctl_assume_authority).  No other permissions are required.
1148  *
1149  * The key and any links to the key will be automatically garbage collected
1150  * after the timeout expires.
1151  *
1152  * Negative keys are used to rate limit repeated request_key() calls by causing
1153  * them to return -ENOKEY until the negative key expires.
1154  *
1155  * If successful, 0 will be returned.
1156  */
1157 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1158 {
1159         return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1160 }
1161
1162 /*
1163  * Negatively instantiate the key with the given timeout (in seconds) and error
1164  * code and link the key into the destination keyring if one is given.
1165  *
1166  * The caller must have the appropriate instantiation permit set for this to
1167  * work (see keyctl_assume_authority).  No other permissions are required.
1168  *
1169  * The key and any links to the key will be automatically garbage collected
1170  * after the timeout expires.
1171  *
1172  * Negative keys are used to rate limit repeated request_key() calls by causing
1173  * them to return the specified error code until the negative key expires.
1174  *
1175  * If successful, 0 will be returned.
1176  */
1177 long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1178                        key_serial_t ringid)
1179 {
1180         const struct cred *cred = current_cred();
1181         struct request_key_auth *rka;
1182         struct key *instkey, *dest_keyring;
1183         long ret;
1184
1185         kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1186
1187         /* must be a valid error code and mustn't be a kernel special */
1188         if (error <= 0 ||
1189             error >= MAX_ERRNO ||
1190             error == ERESTARTSYS ||
1191             error == ERESTARTNOINTR ||
1192             error == ERESTARTNOHAND ||
1193             error == ERESTART_RESTARTBLOCK)
1194                 return -EINVAL;
1195
1196         /* the appropriate instantiation authorisation key must have been
1197          * assumed before calling this */
1198         ret = -EPERM;
1199         instkey = cred->request_key_auth;
1200         if (!instkey)
1201                 goto error;
1202
1203         rka = instkey->payload.data;
1204         if (rka->target_key->serial != id)
1205                 goto error;
1206
1207         /* find the destination keyring if present (which must also be
1208          * writable) */
1209         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1210         if (ret < 0)
1211                 goto error;
1212
1213         /* instantiate the key and link it into a keyring */
1214         ret = key_reject_and_link(rka->target_key, timeout, error,
1215                                   dest_keyring, instkey);
1216
1217         key_put(dest_keyring);
1218
1219         /* discard the assumed authority if it's just been disabled by
1220          * instantiation of the key */
1221         if (ret == 0)
1222                 keyctl_change_reqkey_auth(NULL);
1223
1224 error:
1225         return ret;
1226 }
1227
1228 /*
1229  * Read or set the default keyring in which request_key() will cache keys and
1230  * return the old setting.
1231  *
1232  * If a process keyring is specified then this will be created if it doesn't
1233  * yet exist.  The old setting will be returned if successful.
1234  */
1235 long keyctl_set_reqkey_keyring(int reqkey_defl)
1236 {
1237         struct cred *new;
1238         int ret, old_setting;
1239
1240         old_setting = current_cred_xxx(jit_keyring);
1241
1242         if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1243                 return old_setting;
1244
1245         new = prepare_creds();
1246         if (!new)
1247                 return -ENOMEM;
1248
1249         switch (reqkey_defl) {
1250         case KEY_REQKEY_DEFL_THREAD_KEYRING:
1251                 ret = install_thread_keyring_to_cred(new);
1252                 if (ret < 0)
1253                         goto error;
1254                 goto set;
1255
1256         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1257                 ret = install_process_keyring_to_cred(new);
1258                 if (ret < 0) {
1259                         if (ret != -EEXIST)
1260                                 goto error;
1261                         ret = 0;
1262                 }
1263                 goto set;
1264
1265         case KEY_REQKEY_DEFL_DEFAULT:
1266         case KEY_REQKEY_DEFL_SESSION_KEYRING:
1267         case KEY_REQKEY_DEFL_USER_KEYRING:
1268         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1269         case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1270                 goto set;
1271
1272         case KEY_REQKEY_DEFL_NO_CHANGE:
1273         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1274         default:
1275                 ret = -EINVAL;
1276                 goto error;
1277         }
1278
1279 set:
1280         new->jit_keyring = reqkey_defl;
1281         commit_creds(new);
1282         return old_setting;
1283 error:
1284         abort_creds(new);
1285         return ret;
1286 }
1287
1288 /*
1289  * Set or clear the timeout on a key.
1290  *
1291  * Either the key must grant the caller Setattr permission or else the caller
1292  * must hold an instantiation authorisation token for the key.
1293  *
1294  * The timeout is either 0 to clear the timeout, or a number of seconds from
1295  * the current time.  The key and any links to the key will be automatically
1296  * garbage collected after the timeout expires.
1297  *
1298  * If successful, 0 is returned.
1299  */
1300 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1301 {
1302         struct key *key, *instkey;
1303         key_ref_t key_ref;
1304         long ret;
1305
1306         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1307                                   KEY_SETATTR);
1308         if (IS_ERR(key_ref)) {
1309                 /* setting the timeout on a key under construction is permitted
1310                  * if we have the authorisation token handy */
1311                 if (PTR_ERR(key_ref) == -EACCES) {
1312                         instkey = key_get_instantiation_authkey(id);
1313                         if (!IS_ERR(instkey)) {
1314                                 key_put(instkey);
1315                                 key_ref = lookup_user_key(id,
1316                                                           KEY_LOOKUP_PARTIAL,
1317                                                           0);
1318                                 if (!IS_ERR(key_ref))
1319                                         goto okay;
1320                         }
1321                 }
1322
1323                 ret = PTR_ERR(key_ref);
1324                 goto error;
1325         }
1326
1327 okay:
1328         key = key_ref_to_ptr(key_ref);
1329         key_set_timeout(key, timeout);
1330         key_put(key);
1331
1332         ret = 0;
1333 error:
1334         return ret;
1335 }
1336
1337 /*
1338  * Assume (or clear) the authority to instantiate the specified key.
1339  *
1340  * This sets the authoritative token currently in force for key instantiation.
1341  * This must be done for a key to be instantiated.  It has the effect of making
1342  * available all the keys from the caller of the request_key() that created a
1343  * key to request_key() calls made by the caller of this function.
1344  *
1345  * The caller must have the instantiation key in their process keyrings with a
1346  * Search permission grant available to the caller.
1347  *
1348  * If the ID given is 0, then the setting will be cleared and 0 returned.
1349  *
1350  * If the ID given has a matching an authorisation key, then that key will be
1351  * set and its ID will be returned.  The authorisation key can be read to get
1352  * the callout information passed to request_key().
1353  */
1354 long keyctl_assume_authority(key_serial_t id)
1355 {
1356         struct key *authkey;
1357         long ret;
1358
1359         /* special key IDs aren't permitted */
1360         ret = -EINVAL;
1361         if (id < 0)
1362                 goto error;
1363
1364         /* we divest ourselves of authority if given an ID of 0 */
1365         if (id == 0) {
1366                 ret = keyctl_change_reqkey_auth(NULL);
1367                 goto error;
1368         }
1369
1370         /* attempt to assume the authority temporarily granted to us whilst we
1371          * instantiate the specified key
1372          * - the authorisation key must be in the current task's keyrings
1373          *   somewhere
1374          */
1375         authkey = key_get_instantiation_authkey(id);
1376         if (IS_ERR(authkey)) {
1377                 ret = PTR_ERR(authkey);
1378                 goto error;
1379         }
1380
1381         ret = keyctl_change_reqkey_auth(authkey);
1382         if (ret < 0)
1383                 goto error;
1384         key_put(authkey);
1385
1386         ret = authkey->serial;
1387 error:
1388         return ret;
1389 }
1390
1391 /*
1392  * Get a key's the LSM security label.
1393  *
1394  * The key must grant the caller View permission for this to work.
1395  *
1396  * If there's a buffer, then up to buflen bytes of data will be placed into it.
1397  *
1398  * If successful, the amount of information available will be returned,
1399  * irrespective of how much was copied (including the terminal NUL).
1400  */
1401 long keyctl_get_security(key_serial_t keyid,
1402                          char __user *buffer,
1403                          size_t buflen)
1404 {
1405         struct key *key, *instkey;
1406         key_ref_t key_ref;
1407         char *context;
1408         long ret;
1409
1410         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1411         if (IS_ERR(key_ref)) {
1412                 if (PTR_ERR(key_ref) != -EACCES)
1413                         return PTR_ERR(key_ref);
1414
1415                 /* viewing a key under construction is also permitted if we
1416                  * have the authorisation token handy */
1417                 instkey = key_get_instantiation_authkey(keyid);
1418                 if (IS_ERR(instkey))
1419                         return PTR_ERR(instkey);
1420                 key_put(instkey);
1421
1422                 key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1423                 if (IS_ERR(key_ref))
1424                         return PTR_ERR(key_ref);
1425         }
1426
1427         key = key_ref_to_ptr(key_ref);
1428         ret = security_key_getsecurity(key, &context);
1429         if (ret == 0) {
1430                 /* if no information was returned, give userspace an empty
1431                  * string */
1432                 ret = 1;
1433                 if (buffer && buflen > 0 &&
1434                     copy_to_user(buffer, "", 1) != 0)
1435                         ret = -EFAULT;
1436         } else if (ret > 0) {
1437                 /* return as much data as there's room for */
1438                 if (buffer && buflen > 0) {
1439                         if (buflen > ret)
1440                                 buflen = ret;
1441
1442                         if (copy_to_user(buffer, context, buflen) != 0)
1443                                 ret = -EFAULT;
1444                 }
1445
1446                 kfree(context);
1447         }
1448
1449         key_ref_put(key_ref);
1450         return ret;
1451 }
1452
1453 /*
1454  * Attempt to install the calling process's session keyring on the process's
1455  * parent process.
1456  *
1457  * The keyring must exist and must grant the caller LINK permission, and the
1458  * parent process must be single-threaded and must have the same effective
1459  * ownership as this process and mustn't be SUID/SGID.
1460  *
1461  * The keyring will be emplaced on the parent when it next resumes userspace.
1462  *
1463  * If successful, 0 will be returned.
1464  */
1465 long keyctl_session_to_parent(void)
1466 {
1467         struct task_struct *me, *parent;
1468         const struct cred *mycred, *pcred;
1469         struct callback_head *newwork, *oldwork;
1470         key_ref_t keyring_r;
1471         struct cred *cred;
1472         int ret;
1473
1474         keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1475         if (IS_ERR(keyring_r))
1476                 return PTR_ERR(keyring_r);
1477
1478         ret = -ENOMEM;
1479
1480         /* our parent is going to need a new cred struct, a new tgcred struct
1481          * and new security data, so we allocate them here to prevent ENOMEM in
1482          * our parent */
1483         cred = cred_alloc_blank();
1484         if (!cred)
1485                 goto error_keyring;
1486         newwork = &cred->rcu;
1487
1488         cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1489         init_task_work(newwork, key_change_session_keyring);
1490
1491         me = current;
1492         rcu_read_lock();
1493         write_lock_irq(&tasklist_lock);
1494
1495         ret = -EPERM;
1496         oldwork = NULL;
1497         parent = me->real_parent;
1498
1499         task_lock(parent);
1500         /* the parent mustn't be init and mustn't be a kernel thread */
1501         if (parent->pid <= 1 || !parent->mm)
1502                 goto unlock;
1503
1504         /* the parent must be single threaded */
1505         if (!thread_group_empty(parent))
1506                 goto unlock;
1507
1508         /* the parent and the child must have different session keyrings or
1509          * there's no point */
1510         mycred = current_cred();
1511         pcred = __task_cred(parent);
1512         if (mycred == pcred ||
1513             mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) {
1514                 ret = 0;
1515                 goto unlock;
1516         }
1517
1518         /* the parent must have the same effective ownership and mustn't be
1519          * SUID/SGID */
1520         if (pcred->uid  != mycred->euid ||
1521             pcred->euid != mycred->euid ||
1522             pcred->suid != mycred->euid ||
1523             pcred->gid  != mycred->egid ||
1524             pcred->egid != mycred->egid ||
1525             pcred->sgid != mycred->egid)
1526                 goto unlock;
1527
1528         /* the keyrings must have the same UID */
1529         if ((pcred->tgcred->session_keyring &&
1530              pcred->tgcred->session_keyring->uid != mycred->euid) ||
1531             mycred->tgcred->session_keyring->uid != mycred->euid)
1532                 goto unlock;
1533
1534         /* cancel an already pending keyring replacement */
1535         oldwork = task_work_cancel(parent, key_change_session_keyring);
1536
1537         /* the replacement session keyring is applied just prior to userspace
1538          * restarting */
1539         ret = task_work_add(parent, newwork, true);
1540         if (!ret)
1541                 newwork = NULL;
1542 unlock:
1543         task_unlock(parent);
1544         write_unlock_irq(&tasklist_lock);
1545         rcu_read_unlock();
1546         if (oldwork)
1547                 put_cred(container_of(oldwork, struct cred, rcu));
1548         if (newwork)
1549                 put_cred(cred);
1550         return ret;
1551
1552 error_keyring:
1553         key_ref_put(keyring_r);
1554         return ret;
1555 }
1556
1557 /*
1558  * The key control system call
1559  */
1560 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1561                 unsigned long, arg4, unsigned long, arg5)
1562 {
1563         switch (option) {
1564         case KEYCTL_GET_KEYRING_ID:
1565                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1566                                              (int) arg3);
1567
1568         case KEYCTL_JOIN_SESSION_KEYRING:
1569                 return keyctl_join_session_keyring((const char __user *) arg2);
1570
1571         case KEYCTL_UPDATE:
1572                 return keyctl_update_key((key_serial_t) arg2,
1573                                          (const void __user *) arg3,
1574                                          (size_t) arg4);
1575
1576         case KEYCTL_REVOKE:
1577                 return keyctl_revoke_key((key_serial_t) arg2);
1578
1579         case KEYCTL_DESCRIBE:
1580                 return keyctl_describe_key((key_serial_t) arg2,
1581                                            (char __user *) arg3,
1582                                            (unsigned) arg4);
1583
1584         case KEYCTL_CLEAR:
1585                 return keyctl_keyring_clear((key_serial_t) arg2);
1586
1587         case KEYCTL_LINK:
1588                 return keyctl_keyring_link((key_serial_t) arg2,
1589                                            (key_serial_t) arg3);
1590
1591         case KEYCTL_UNLINK:
1592                 return keyctl_keyring_unlink((key_serial_t) arg2,
1593                                              (key_serial_t) arg3);
1594
1595         case KEYCTL_SEARCH:
1596                 return keyctl_keyring_search((key_serial_t) arg2,
1597                                              (const char __user *) arg3,
1598                                              (const char __user *) arg4,
1599                                              (key_serial_t) arg5);
1600
1601         case KEYCTL_READ:
1602                 return keyctl_read_key((key_serial_t) arg2,
1603                                        (char __user *) arg3,
1604                                        (size_t) arg4);
1605
1606         case KEYCTL_CHOWN:
1607                 return keyctl_chown_key((key_serial_t) arg2,
1608                                         (uid_t) arg3,
1609                                         (gid_t) arg4);
1610
1611         case KEYCTL_SETPERM:
1612                 return keyctl_setperm_key((key_serial_t) arg2,
1613                                           (key_perm_t) arg3);
1614
1615         case KEYCTL_INSTANTIATE:
1616                 return keyctl_instantiate_key((key_serial_t) arg2,
1617                                               (const void __user *) arg3,
1618                                               (size_t) arg4,
1619                                               (key_serial_t) arg5);
1620
1621         case KEYCTL_NEGATE:
1622                 return keyctl_negate_key((key_serial_t) arg2,
1623                                          (unsigned) arg3,
1624                                          (key_serial_t) arg4);
1625
1626         case KEYCTL_SET_REQKEY_KEYRING:
1627                 return keyctl_set_reqkey_keyring(arg2);
1628
1629         case KEYCTL_SET_TIMEOUT:
1630                 return keyctl_set_timeout((key_serial_t) arg2,
1631                                           (unsigned) arg3);
1632
1633         case KEYCTL_ASSUME_AUTHORITY:
1634                 return keyctl_assume_authority((key_serial_t) arg2);
1635
1636         case KEYCTL_GET_SECURITY:
1637                 return keyctl_get_security((key_serial_t) arg2,
1638                                            (char __user *) arg3,
1639                                            (size_t) arg4);
1640
1641         case KEYCTL_SESSION_TO_PARENT:
1642                 return keyctl_session_to_parent();
1643
1644         case KEYCTL_REJECT:
1645                 return keyctl_reject_key((key_serial_t) arg2,
1646                                          (unsigned) arg3,
1647                                          (unsigned) arg4,
1648                                          (key_serial_t) arg5);
1649
1650         case KEYCTL_INSTANTIATE_IOV:
1651                 return keyctl_instantiate_key_iov(
1652                         (key_serial_t) arg2,
1653                         (const struct iovec __user *) arg3,
1654                         (unsigned) arg4,
1655                         (key_serial_t) arg5);
1656
1657         case KEYCTL_INVALIDATE:
1658                 return keyctl_invalidate_key((key_serial_t) arg2);
1659
1660         default:
1661                 return -EOPNOTSUPP;
1662         }
1663 }