security/keys/keyctl.c

   1 /* keyctl.c: userspace keyctl 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/keyctl.h>
  18 #include <linux/fs.h>
  19 #include <linux/capability.h>
  20 #include <linux/string.h>
  21 #include <linux/err.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/security.h>
  24 #include <asm/uaccess.h>
  25 #include "internal.h"
  26
  27 static int key_get_type_from_user(char *type,
  28                                   const char __user *_type,
  29                                   unsigned len)
  30 {
  31         int ret;
  32
  33         ret = strncpy_from_user(type, _type, len);
  34
  35         if (ret < 0)
  36                 return -EFAULT;
  37
  38         if (ret == 0 || ret >= len)
  39                 return -EINVAL;
  40
  41         if (type[0] == '.')
  42                 return -EPERM;
  43
  44         type[len - 1] = '\0';
  45
  46         return 0;
  47 }
  48
  49 /*****************************************************************************/
  50 /*
  51  * extract the description of a new key from userspace and either add it as a
  52  * new key to the specified keyring or update a matching key in that keyring
  53  * - the keyring must be writable
  54  * - returns the new key's serial number
  55  * - implements add_key()
  56  */
  57 asmlinkage long sys_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 = strndup_user(_description, PAGE_SIZE);
  79         if (IS_ERR(description)) {
  80                 ret = PTR_ERR(description);
  81                 goto error;
  82         }
  83
  84         /* pull the payload in if one was supplied */
  85         payload = NULL;
  86
  87         vm = false;
  88         if (_payload) {
  89                 ret = -ENOMEM;
  90                 payload = kmalloc(plen, GFP_KERNEL);
  91                 if (!payload) {
  92                         if (plen <= PAGE_SIZE)
  93                                 goto error2;
  94                         vm = true;
  95                         payload = vmalloc(plen);
  96                         if (!payload)
  97                                 goto error2;
  98                 }
  99
 100                 ret = -EFAULT;
 101                 if (copy_from_user(payload, _payload, plen) != 0)
 102                         goto error3;
 103         }
 104
 105         /* find the target keyring (which must be writable) */
 106         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 107         if (IS_ERR(keyring_ref)) {
 108                 ret = PTR_ERR(keyring_ref);
 109                 goto error3;
 110         }
 111
 112         /* create or update the requested key and add it to the target
 113          * keyring */
 114         key_ref = key_create_or_update(keyring_ref, type, description,
 115                                        payload, plen, KEY_PERM_UNDEF,
 116                                        KEY_ALLOC_IN_QUOTA);
 117         if (!IS_ERR(key_ref)) {
 118                 ret = key_ref_to_ptr(key_ref)->serial;
 119                 key_ref_put(key_ref);
 120         }
 121         else {
 122                 ret = PTR_ERR(key_ref);
 123         }
 124
 125         key_ref_put(keyring_ref);
 126  error3:
 127         if (!vm)
 128                 kfree(payload);
 129         else
 130                 vfree(payload);
 131  error2:
 132         kfree(description);
 133  error:
 134         return ret;
 135
 136 } /* end sys_add_key() */
 137
 138 /*****************************************************************************/
 139 /*
 140  * search the process keyrings for a matching key
 141  * - nested keyrings may also be searched if they have Search permission
 142  * - if a key is found, it will be attached to the destination keyring if
 143  *   there's one specified
 144  * - /sbin/request-key will be invoked if _callout_info is non-NULL
 145  *   - the _callout_info string will be passed to /sbin/request-key
 146  *   - if the _callout_info string is empty, it will be rendered as "-"
 147  * - implements request_key()
 148  */
 149 asmlinkage long sys_request_key(const char __user *_type,
 150                                 const char __user *_description,
 151                                 const char __user *_callout_info,
 152                                 key_serial_t destringid)
 153 {
 154         struct key_type *ktype;
 155         struct key *key;
 156         key_ref_t dest_ref;
 157         size_t callout_len;
 158         char type[32], *description, *callout_info;
 159         long ret;
 160
 161         /* pull the type into kernel space */
 162         ret = key_get_type_from_user(type, _type, sizeof(type));
 163         if (ret < 0)
 164                 goto error;
 165
 166         /* pull the description into kernel space */
 167         description = strndup_user(_description, PAGE_SIZE);
 168         if (IS_ERR(description)) {
 169                 ret = PTR_ERR(description);
 170                 goto error;
 171         }
 172
 173         /* pull the callout info into kernel space */
 174         callout_info = NULL;
 175         callout_len = 0;
 176         if (_callout_info) {
 177                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
 178                 if (IS_ERR(callout_info)) {
 179                         ret = PTR_ERR(callout_info);
 180                         goto error2;
 181                 }
 182                 callout_len = strlen(callout_info);
 183         }
 184
 185         /* get the destination keyring if specified */
 186         dest_ref = NULL;
 187         if (destringid) {
 188                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 189                 if (IS_ERR(dest_ref)) {
 190                         ret = PTR_ERR(dest_ref);
 191                         goto error3;
 192                 }
 193         }
 194
 195         /* find the key type */
 196         ktype = key_type_lookup(type);
 197         if (IS_ERR(ktype)) {
 198                 ret = PTR_ERR(ktype);
 199                 goto error4;
 200         }
 201
 202         /* do the search */
 203         key = request_key_and_link(ktype, description, callout_info,
 204                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
 205                                    KEY_ALLOC_IN_QUOTA);
 206         if (IS_ERR(key)) {
 207                 ret = PTR_ERR(key);
 208                 goto error5;
 209         }
 210
 211         ret = key->serial;
 212
 213         key_put(key);
 214  error5:
 215         key_type_put(ktype);
 216  error4:
 217         key_ref_put(dest_ref);
 218  error3:
 219         kfree(callout_info);
 220  error2:
 221         kfree(description);
 222  error:
 223         return ret;
 224
 225 } /* end sys_request_key() */
 226
 227 /*****************************************************************************/
 228 /*
 229  * get the ID of the specified process keyring
 230  * - the keyring must have search permission to be found
 231  * - implements keyctl(KEYCTL_GET_KEYRING_ID)
 232  */
 233 long keyctl_get_keyring_ID(key_serial_t id, int create)
 234 {
 235         key_ref_t key_ref;
 236         long ret;
 237
 238         key_ref = lookup_user_key(NULL, id, create, 0, KEY_SEARCH);
 239         if (IS_ERR(key_ref)) {
 240                 ret = PTR_ERR(key_ref);
 241                 goto error;
 242         }
 243
 244         ret = key_ref_to_ptr(key_ref)->serial;
 245         key_ref_put(key_ref);
 246  error:
 247         return ret;
 248
 249 } /* end keyctl_get_keyring_ID() */
 250
 251 /*****************************************************************************/
 252 /*
 253  * join the session keyring
 254  * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
 255  */
 256 long keyctl_join_session_keyring(const char __user *_name)
 257 {
 258         char *name;
 259         long ret;
 260
 261         /* fetch the name from userspace */
 262         name = NULL;
 263         if (_name) {
 264                 name = strndup_user(_name, PAGE_SIZE);
 265                 if (IS_ERR(name)) {
 266                         ret = PTR_ERR(name);
 267                         goto error;
 268                 }
 269         }
 270
 271         /* join the session */
 272         ret = join_session_keyring(name);
 273
 274  error:
 275         return ret;
 276
 277 } /* end keyctl_join_session_keyring() */
 278
 279 /*****************************************************************************/
 280 /*
 281  * update a key's data payload
 282  * - the key must be writable
 283  * - implements keyctl(KEYCTL_UPDATE)
 284  */
 285 long keyctl_update_key(key_serial_t id,
 286                        const void __user *_payload,
 287                        size_t plen)
 288 {
 289         key_ref_t key_ref;
 290         void *payload;
 291         long ret;
 292
 293         ret = -EINVAL;
 294         if (plen > PAGE_SIZE)
 295                 goto error;
 296
 297         /* pull the payload in if one was supplied */
 298         payload = NULL;
 299         if (_payload) {
 300                 ret = -ENOMEM;
 301                 payload = kmalloc(plen, GFP_KERNEL);
 302                 if (!payload)
 303                         goto error;
 304
 305                 ret = -EFAULT;
 306                 if (copy_from_user(payload, _payload, plen) != 0)
 307                         goto error2;
 308         }
 309
 310         /* find the target key (which must be writable) */
 311         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 312         if (IS_ERR(key_ref)) {
 313                 ret = PTR_ERR(key_ref);
 314                 goto error2;
 315         }
 316
 317         /* update the key */
 318         ret = key_update(key_ref, payload, plen);
 319
 320         key_ref_put(key_ref);
 321  error2:
 322         kfree(payload);
 323  error:
 324         return ret;
 325
 326 } /* end keyctl_update_key() */
 327
 328 /*****************************************************************************/
 329 /*
 330  * revoke a key
 331  * - the key must be writable
 332  * - implements keyctl(KEYCTL_REVOKE)
 333  */
 334 long keyctl_revoke_key(key_serial_t id)
 335 {
 336         key_ref_t key_ref;
 337         long ret;
 338
 339         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 340         if (IS_ERR(key_ref)) {
 341                 ret = PTR_ERR(key_ref);
 342                 goto error;
 343         }
 344
 345         key_revoke(key_ref_to_ptr(key_ref));
 346         ret = 0;
 347
 348         key_ref_put(key_ref);
 349  error:
 350         return ret;
 351
 352 } /* end keyctl_revoke_key() */
 353
 354 /*****************************************************************************/
 355 /*
 356  * clear the specified process keyring
 357  * - the keyring must be writable
 358  * - implements keyctl(KEYCTL_CLEAR)
 359  */
 360 long keyctl_keyring_clear(key_serial_t ringid)
 361 {
 362         key_ref_t keyring_ref;
 363         long ret;
 364
 365         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 366         if (IS_ERR(keyring_ref)) {
 367                 ret = PTR_ERR(keyring_ref);
 368                 goto error;
 369         }
 370
 371         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 372
 373         key_ref_put(keyring_ref);
 374  error:
 375         return ret;
 376
 377 } /* end keyctl_keyring_clear() */
 378
 379 /*****************************************************************************/
 380 /*
 381  * link a key into a keyring
 382  * - the keyring must be writable
 383  * - the key must be linkable
 384  * - implements keyctl(KEYCTL_LINK)
 385  */
 386 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 387 {
 388         key_ref_t keyring_ref, key_ref;
 389         long ret;
 390
 391         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 392         if (IS_ERR(keyring_ref)) {
 393                 ret = PTR_ERR(keyring_ref);
 394                 goto error;
 395         }
 396
 397         key_ref = lookup_user_key(NULL, id, 1, 0, KEY_LINK);
 398         if (IS_ERR(key_ref)) {
 399                 ret = PTR_ERR(key_ref);
 400                 goto error2;
 401         }
 402
 403         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 404
 405         key_ref_put(key_ref);
 406  error2:
 407         key_ref_put(keyring_ref);
 408  error:
 409         return ret;
 410
 411 } /* end keyctl_keyring_link() */
 412
 413 /*****************************************************************************/
 414 /*
 415  * unlink the first attachment of a key from a keyring
 416  * - the keyring must be writable
 417  * - we don't need any permissions on the key
 418  * - implements keyctl(KEYCTL_UNLINK)
 419  */
 420 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 421 {
 422         key_ref_t keyring_ref, key_ref;
 423         long ret;
 424
 425         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_WRITE);
 426         if (IS_ERR(keyring_ref)) {
 427                 ret = PTR_ERR(keyring_ref);
 428                 goto error;
 429         }
 430
 431         key_ref = lookup_user_key(NULL, id, 0, 0, 0);
 432         if (IS_ERR(key_ref)) {
 433                 ret = PTR_ERR(key_ref);
 434                 goto error2;
 435         }
 436
 437         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 438
 439         key_ref_put(key_ref);
 440  error2:
 441         key_ref_put(keyring_ref);
 442  error:
 443         return ret;
 444
 445 } /* end keyctl_keyring_unlink() */
 446
 447 /*****************************************************************************/
 448 /*
 449  * describe a user key
 450  * - the key must have view permission
 451  * - if there's a buffer, we place up to buflen bytes of data into it
 452  * - unless there's an error, we return the amount of description available,
 453  *   irrespective of how much we may have copied
 454  * - the description is formatted thus:
 455  *      type;uid;gid;perm;description<NUL>
 456  * - implements keyctl(KEYCTL_DESCRIBE)
 457  */
 458 long keyctl_describe_key(key_serial_t keyid,
 459                          char __user *buffer,
 460                          size_t buflen)
 461 {
 462         struct key *key, *instkey;
 463         key_ref_t key_ref;
 464         char *tmpbuf;
 465         long ret;
 466
 467         key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
 468         if (IS_ERR(key_ref)) {
 469                 /* viewing a key under construction is permitted if we have the
 470                  * authorisation token handy */
 471                 if (PTR_ERR(key_ref) == -EACCES) {
 472                         instkey = key_get_instantiation_authkey(keyid);
 473                         if (!IS_ERR(instkey)) {
 474                                 key_put(instkey);
 475                                 key_ref = lookup_user_key(NULL, keyid,
 476                                                           0, 1, 0);
 477                                 if (!IS_ERR(key_ref))
 478                                         goto okay;
 479                         }
 480                 }
 481
 482                 ret = PTR_ERR(key_ref);
 483                 goto error;
 484         }
 485
 486 okay:
 487         /* calculate how much description we're going to return */
 488         ret = -ENOMEM;
 489         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 490         if (!tmpbuf)
 491                 goto error2;
 492
 493         key = key_ref_to_ptr(key_ref);
 494
 495         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 496                        "%s;%d;%d;%08x;%s",
 497                        key_ref_to_ptr(key_ref)->type->name,
 498                        key_ref_to_ptr(key_ref)->uid,
 499                        key_ref_to_ptr(key_ref)->gid,
 500                        key_ref_to_ptr(key_ref)->perm,
 501                        key_ref_to_ptr(key_ref)->description ?
 502                        key_ref_to_ptr(key_ref)->description : ""
 503                        );
 504
 505         /* include a NUL char at the end of the data */
 506         if (ret > PAGE_SIZE - 1)
 507                 ret = PAGE_SIZE - 1;
 508         tmpbuf[ret] = 0;
 509         ret++;
 510
 511         /* consider returning the data */
 512         if (buffer && buflen > 0) {
 513                 if (buflen > ret)
 514                         buflen = ret;
 515
 516                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 517                         ret = -EFAULT;
 518         }
 519
 520         kfree(tmpbuf);
 521  error2:
 522         key_ref_put(key_ref);
 523  error:
 524         return ret;
 525
 526 } /* end keyctl_describe_key() */
 527
 528 /*****************************************************************************/
 529 /*
 530  * search the specified keyring for a matching key
 531  * - the start keyring must be searchable
 532  * - nested keyrings may also be searched if they are searchable
 533  * - only keys with search permission may be found
 534  * - if a key is found, it will be attached to the destination keyring if
 535  *   there's one specified
 536  * - implements keyctl(KEYCTL_SEARCH)
 537  */
 538 long keyctl_keyring_search(key_serial_t ringid,
 539                            const char __user *_type,
 540                            const char __user *_description,
 541                            key_serial_t destringid)
 542 {
 543         struct key_type *ktype;
 544         key_ref_t keyring_ref, key_ref, dest_ref;
 545         char type[32], *description;
 546         long ret;
 547
 548         /* pull the type and description into kernel space */
 549         ret = key_get_type_from_user(type, _type, sizeof(type));
 550         if (ret < 0)
 551                 goto error;
 552
 553         description = strndup_user(_description, PAGE_SIZE);
 554         if (IS_ERR(description)) {
 555                 ret = PTR_ERR(description);
 556                 goto error;
 557         }
 558
 559         /* get the keyring at which to begin the search */
 560         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_SEARCH);
 561         if (IS_ERR(keyring_ref)) {
 562                 ret = PTR_ERR(keyring_ref);
 563                 goto error2;
 564         }
 565
 566         /* get the destination keyring if specified */
 567         dest_ref = NULL;
 568         if (destringid) {
 569                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 570                 if (IS_ERR(dest_ref)) {
 571                         ret = PTR_ERR(dest_ref);
 572                         goto error3;
 573                 }
 574         }
 575
 576         /* find the key type */
 577         ktype = key_type_lookup(type);
 578         if (IS_ERR(ktype)) {
 579                 ret = PTR_ERR(ktype);
 580                 goto error4;
 581         }
 582
 583         /* do the search */
 584         key_ref = keyring_search(keyring_ref, ktype, description);
 585         if (IS_ERR(key_ref)) {
 586                 ret = PTR_ERR(key_ref);
 587
 588                 /* treat lack or presence of a negative key the same */
 589                 if (ret == -EAGAIN)
 590                         ret = -ENOKEY;
 591                 goto error5;
 592         }
 593
 594         /* link the resulting key to the destination keyring if we can */
 595         if (dest_ref) {
 596                 ret = key_permission(key_ref, KEY_LINK);
 597                 if (ret < 0)
 598                         goto error6;
 599
 600                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 601                 if (ret < 0)
 602                         goto error6;
 603         }
 604
 605         ret = key_ref_to_ptr(key_ref)->serial;
 606
 607  error6:
 608         key_ref_put(key_ref);
 609  error5:
 610         key_type_put(ktype);
 611  error4:
 612         key_ref_put(dest_ref);
 613  error3:
 614         key_ref_put(keyring_ref);
 615  error2:
 616         kfree(description);
 617  error:
 618         return ret;
 619
 620 } /* end keyctl_keyring_search() */
 621
 622 /*****************************************************************************/
 623 /*
 624  * read a user key's payload
 625  * - the keyring must be readable or the key must be searchable from the
 626  *   process's keyrings
 627  * - if there's a buffer, we place up to buflen bytes of data into it
 628  * - unless there's an error, we return the amount of data in the key,
 629  *   irrespective of how much we may have copied
 630  * - implements keyctl(KEYCTL_READ)
 631  */
 632 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 633 {
 634         struct key *key;
 635         key_ref_t key_ref;
 636         long ret;
 637
 638         /* find the key first */
 639         key_ref = lookup_user_key(NULL, keyid, 0, 0, 0);
 640         if (IS_ERR(key_ref)) {
 641                 ret = -ENOKEY;
 642                 goto error;
 643         }
 644
 645         key = key_ref_to_ptr(key_ref);
 646
 647         /* see if we can read it directly */
 648         ret = key_permission(key_ref, KEY_READ);
 649         if (ret == 0)
 650                 goto can_read_key;
 651         if (ret != -EACCES)
 652                 goto error;
 653
 654         /* we can't; see if it's searchable from this process's keyrings
 655          * - we automatically take account of the fact that it may be
 656          *   dangling off an instantiation key
 657          */
 658         if (!is_key_possessed(key_ref)) {
 659                 ret = -EACCES;
 660                 goto error2;
 661         }
 662
 663         /* the key is probably readable - now try to read it */
 664  can_read_key:
 665         ret = key_validate(key);
 666         if (ret == 0) {
 667                 ret = -EOPNOTSUPP;
 668                 if (key->type->read) {
 669                         /* read the data with the semaphore held (since we
 670                          * might sleep) */
 671                         down_read(&key->sem);
 672                         ret = key->type->read(key, buffer, buflen);
 673                         up_read(&key->sem);
 674                 }
 675         }
 676
 677  error2:
 678         key_put(key);
 679  error:
 680         return ret;
 681
 682 } /* end keyctl_read_key() */
 683
 684 /*****************************************************************************/
 685 /*
 686  * change the ownership of a key
 687  * - the keyring owned by the changer
 688  * - if the uid or gid is -1, then that parameter is not changed
 689  * - implements keyctl(KEYCTL_CHOWN)
 690  */
 691 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 692 {
 693         struct key_user *newowner, *zapowner = NULL;
 694         struct key *key;
 695         key_ref_t key_ref;
 696         long ret;
 697
 698         ret = 0;
 699         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 700                 goto error;
 701
 702         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 703         if (IS_ERR(key_ref)) {
 704                 ret = PTR_ERR(key_ref);
 705                 goto error;
 706         }
 707
 708         key = key_ref_to_ptr(key_ref);
 709
 710         /* make the changes with the locks held to prevent chown/chown races */
 711         ret = -EACCES;
 712         down_write(&key->sem);
 713
 714         if (!capable(CAP_SYS_ADMIN)) {
 715                 /* only the sysadmin can chown a key to some other UID */
 716                 if (uid != (uid_t) -1 && key->uid != uid)
 717                         goto error_put;
 718
 719                 /* only the sysadmin can set the key's GID to a group other
 720                  * than one of those that the current process subscribes to */
 721                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 722                         goto error_put;
 723         }
 724
 725         /* change the UID */
 726         if (uid != (uid_t) -1 && uid != key->uid) {
 727                 ret = -ENOMEM;
 728                 newowner = key_user_lookup(uid);
 729                 if (!newowner)
 730                         goto error_put;
 731
 732                 /* transfer the quota burden to the new user */
 733                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 734                         unsigned maxkeys = (uid == 0) ?
 735                                 key_quota_root_maxkeys : key_quota_maxkeys;
 736                         unsigned maxbytes = (uid == 0) ?
 737                                 key_quota_root_maxbytes : key_quota_maxbytes;
 738
 739                         spin_lock(&newowner->lock);
 740                         if (newowner->qnkeys + 1 >= maxkeys ||
 741                             newowner->qnbytes + key->quotalen >= maxbytes ||
 742                             newowner->qnbytes + key->quotalen <
 743                             newowner->qnbytes)
 744                                 goto quota_overrun;
 745
 746                         newowner->qnkeys++;
 747                         newowner->qnbytes += key->quotalen;
 748                         spin_unlock(&newowner->lock);
 749
 750                         spin_lock(&key->user->lock);
 751                         key->user->qnkeys--;
 752                         key->user->qnbytes -= key->quotalen;
 753                         spin_unlock(&key->user->lock);
 754                 }
 755
 756                 atomic_dec(&key->user->nkeys);
 757                 atomic_inc(&newowner->nkeys);
 758
 759                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 760                         atomic_dec(&key->user->nikeys);
 761                         atomic_inc(&newowner->nikeys);
 762                 }
 763
 764                 zapowner = key->user;
 765                 key->user = newowner;
 766                 key->uid = uid;
 767         }
 768
 769         /* change the GID */
 770         if (gid != (gid_t) -1)
 771                 key->gid = gid;
 772
 773         ret = 0;
 774
 775 error_put:
 776         up_write(&key->sem);
 777         key_put(key);
 778         if (zapowner)
 779                 key_user_put(zapowner);
 780 error:
 781         return ret;
 782
 783 quota_overrun:
 784         spin_unlock(&newowner->lock);
 785         zapowner = newowner;
 786         ret = -EDQUOT;
 787         goto error_put;
 788
 789 } /* end keyctl_chown_key() */
 790
 791 /*****************************************************************************/
 792 /*
 793  * change the permission mask on a key
 794  * - the keyring owned by the changer
 795  * - implements keyctl(KEYCTL_SETPERM)
 796  */
 797 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 798 {
 799         struct key *key;
 800         key_ref_t key_ref;
 801         long ret;
 802
 803         ret = -EINVAL;
 804         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 805                 goto error;
 806
 807         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 808         if (IS_ERR(key_ref)) {
 809                 ret = PTR_ERR(key_ref);
 810                 goto error;
 811         }
 812
 813         key = key_ref_to_ptr(key_ref);
 814
 815         /* make the changes with the locks held to prevent chown/chmod races */
 816         ret = -EACCES;
 817         down_write(&key->sem);
 818
 819         /* if we're not the sysadmin, we can only change a key that we own */
 820         if (capable(CAP_SYS_ADMIN) || key->uid == current->fsuid) {
 821                 key->perm = perm;
 822                 ret = 0;
 823         }
 824
 825         up_write(&key->sem);
 826         key_put(key);
 827 error:
 828         return ret;
 829
 830 } /* end keyctl_setperm_key() */
 831
 832 /*****************************************************************************/
 833 /*
 834  * instantiate the key with the specified payload, and, if one is given, link
 835  * the key into the keyring
 836  */
 837 long keyctl_instantiate_key(key_serial_t id,
 838                             const void __user *_payload,
 839                             size_t plen,
 840                             key_serial_t ringid)
 841 {
 842         struct request_key_auth *rka;
 843         struct key *instkey;
 844         key_ref_t keyring_ref;
 845         void *payload;
 846         long ret;
 847         bool vm = false;
 848
 849         ret = -EINVAL;
 850         if (plen > 1024 * 1024 - 1)
 851                 goto error;
 852
 853         /* the appropriate instantiation authorisation key must have been
 854          * assumed before calling this */
 855         ret = -EPERM;
 856         instkey = current->request_key_auth;
 857         if (!instkey)
 858                 goto error;
 859
 860         rka = instkey->payload.data;
 861         if (rka->target_key->serial != id)
 862                 goto error;
 863
 864         /* pull the payload in if one was supplied */
 865         payload = NULL;
 866
 867         if (_payload) {
 868                 ret = -ENOMEM;
 869                 payload = kmalloc(plen, GFP_KERNEL);
 870                 if (!payload) {
 871                         if (plen <= PAGE_SIZE)
 872                                 goto error;
 873                         vm = true;
 874                         payload = vmalloc(plen);
 875                         if (!payload)
 876                                 goto error;
 877                 }
 878
 879                 ret = -EFAULT;
 880                 if (copy_from_user(payload, _payload, plen) != 0)
 881                         goto error2;
 882         }
 883
 884         /* find the destination keyring amongst those belonging to the
 885          * requesting task */
 886         keyring_ref = NULL;
 887         if (ringid) {
 888                 keyring_ref = lookup_user_key(rka->context, ringid, 1, 0,
 889                                               KEY_WRITE);
 890                 if (IS_ERR(keyring_ref)) {
 891                         ret = PTR_ERR(keyring_ref);
 892                         goto error2;
 893                 }
 894         }
 895
 896         /* instantiate the key and link it into a keyring */
 897         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 898                                        key_ref_to_ptr(keyring_ref), instkey);
 899
 900         key_ref_put(keyring_ref);
 901
 902         /* discard the assumed authority if it's just been disabled by
 903          * instantiation of the key */
 904         if (ret == 0) {
 905                 key_put(current->request_key_auth);
 906                 current->request_key_auth = NULL;
 907         }
 908
 909 error2:
 910         if (!vm)
 911                 kfree(payload);
 912         else
 913                 vfree(payload);
 914 error:
 915         return ret;
 916
 917 } /* end keyctl_instantiate_key() */
 918
 919 /*****************************************************************************/
 920 /*
 921  * negatively instantiate the key with the given timeout (in seconds), and, if
 922  * one is given, link the key into the keyring
 923  */
 924 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 925 {
 926         struct request_key_auth *rka;
 927         struct key *instkey;
 928         key_ref_t keyring_ref;
 929         long ret;
 930
 931         /* the appropriate instantiation authorisation key must have been
 932          * assumed before calling this */
 933         ret = -EPERM;
 934         instkey = current->request_key_auth;
 935         if (!instkey)
 936                 goto error;
 937
 938         rka = instkey->payload.data;
 939         if (rka->target_key->serial != id)
 940                 goto error;
 941
 942         /* find the destination keyring if present (which must also be
 943          * writable) */
 944         keyring_ref = NULL;
 945         if (ringid) {
 946                 keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 947                 if (IS_ERR(keyring_ref)) {
 948                         ret = PTR_ERR(keyring_ref);
 949                         goto error;
 950                 }
 951         }
 952
 953         /* instantiate the key and link it into a keyring */
 954         ret = key_negate_and_link(rka->target_key, timeout,
 955                                   key_ref_to_ptr(keyring_ref), instkey);
 956
 957         key_ref_put(keyring_ref);
 958
 959         /* discard the assumed authority if it's just been disabled by
 960          * instantiation of the key */
 961         if (ret == 0) {
 962                 key_put(current->request_key_auth);
 963                 current->request_key_auth = NULL;
 964         }
 965
 966 error:
 967         return ret;
 968
 969 } /* end keyctl_negate_key() */
 970
 971 /*****************************************************************************/
 972 /*
 973  * set the default keyring in which request_key() will cache keys
 974  * - return the old setting
 975  */
 976 long keyctl_set_reqkey_keyring(int reqkey_defl)
 977 {
 978         int ret;
 979
 980         switch (reqkey_defl) {
 981         case KEY_REQKEY_DEFL_THREAD_KEYRING:
 982                 ret = install_thread_keyring(current);
 983                 if (ret < 0)
 984                         return ret;
 985                 goto set;
 986
 987         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 988                 ret = install_process_keyring(current);
 989                 if (ret < 0)
 990                         return ret;
 991
 992         case KEY_REQKEY_DEFL_DEFAULT:
 993         case KEY_REQKEY_DEFL_SESSION_KEYRING:
 994         case KEY_REQKEY_DEFL_USER_KEYRING:
 995         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 996         set:
 997                 current->jit_keyring = reqkey_defl;
 998
 999         case KEY_REQKEY_DEFL_NO_CHANGE:
1000                 return current->jit_keyring;
1001
1002         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1003         default:
1004                 return -EINVAL;
1005         }
1006
1007 } /* end keyctl_set_reqkey_keyring() */
1008
1009 /*****************************************************************************/
1010 /*
1011  * set or clear the timeout for a key
1012  */
1013 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1014 {
1015         struct timespec now;
1016         struct key *key;
1017         key_ref_t key_ref;
1018         time_t expiry;
1019         long ret;
1020
1021         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
1022         if (IS_ERR(key_ref)) {
1023                 ret = PTR_ERR(key_ref);
1024                 goto error;
1025         }
1026
1027         key = key_ref_to_ptr(key_ref);
1028
1029         /* make the changes with the locks held to prevent races */
1030         down_write(&key->sem);
1031
1032         expiry = 0;
1033         if (timeout > 0) {
1034                 now = current_kernel_time();
1035                 expiry = now.tv_sec + timeout;
1036         }
1037
1038         key->expiry = expiry;
1039
1040         up_write(&key->sem);
1041         key_put(key);
1042
1043         ret = 0;
1044 error:
1045         return ret;
1046
1047 } /* end keyctl_set_timeout() */
1048
1049 /*****************************************************************************/
1050 /*
1051  * assume the authority to instantiate the specified key
1052  */
1053 long keyctl_assume_authority(key_serial_t id)
1054 {
1055         struct key *authkey;
1056         long ret;
1057
1058         /* special key IDs aren't permitted */
1059         ret = -EINVAL;
1060         if (id < 0)
1061                 goto error;
1062
1063         /* we divest ourselves of authority if given an ID of 0 */
1064         if (id == 0) {
1065                 key_put(current->request_key_auth);
1066                 current->request_key_auth = NULL;
1067                 ret = 0;
1068                 goto error;
1069         }
1070
1071         /* attempt to assume the authority temporarily granted to us whilst we
1072          * instantiate the specified key
1073          * - the authorisation key must be in the current task's keyrings
1074          *   somewhere
1075          */
1076         authkey = key_get_instantiation_authkey(id);
1077         if (IS_ERR(authkey)) {
1078                 ret = PTR_ERR(authkey);
1079                 goto error;
1080         }
1081
1082         key_put(current->request_key_auth);
1083         current->request_key_auth = authkey;
1084         ret = authkey->serial;
1085
1086 error:
1087         return ret;
1088
1089 } /* end keyctl_assume_authority() */
1090
1091 /*
1092  * get the security label of a key
1093  * - the key must grant us view permission
1094  * - if there's a buffer, we place up to buflen bytes of data into it
1095  * - unless there's an error, we return the amount of information available,
1096  *   irrespective of how much we may have copied (including the terminal NUL)
1097  * - implements keyctl(KEYCTL_GET_SECURITY)
1098  */
1099 long keyctl_get_security(key_serial_t keyid,
1100                          char __user *buffer,
1101                          size_t buflen)
1102 {
1103         struct key *key, *instkey;
1104         key_ref_t key_ref;
1105         char *context;
1106         long ret;
1107
1108         key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
1109         if (IS_ERR(key_ref)) {
1110                 if (PTR_ERR(key_ref) != -EACCES)
1111                         return PTR_ERR(key_ref);
1112
1113                 /* viewing a key under construction is also permitted if we
1114                  * have the authorisation token handy */
1115                 instkey = key_get_instantiation_authkey(keyid);
1116                 if (IS_ERR(instkey))
1117                         return PTR_ERR(key_ref);
1118                 key_put(instkey);
1119
1120                 key_ref = lookup_user_key(NULL, keyid, 0, 1, 0);
1121                 if (IS_ERR(key_ref))
1122                         return PTR_ERR(key_ref);
1123         }
1124
1125         key = key_ref_to_ptr(key_ref);
1126         ret = security_key_getsecurity(key, &context);
1127         if (ret == 0) {
1128                 /* if no information was returned, give userspace an empty
1129                  * string */
1130                 ret = 1;
1131                 if (buffer && buflen > 0 &&
1132                     copy_to_user(buffer, "", 1) != 0)
1133                         ret = -EFAULT;
1134         } else if (ret > 0) {
1135                 /* return as much data as there's room for */
1136                 if (buffer && buflen > 0) {
1137                         if (buflen > ret)
1138                                 buflen = ret;
1139
1140                         if (copy_to_user(buffer, context, buflen) != 0)
1141                                 ret = -EFAULT;
1142                 }
1143
1144                 kfree(context);
1145         }
1146
1147         key_ref_put(key_ref);
1148         return ret;
1149 }
1150
1151 /*****************************************************************************/
1152 /*
1153  * the key control system call
1154  */
1155 asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
1156                            unsigned long arg4, unsigned long arg5)
1157 {
1158         switch (option) {
1159         case KEYCTL_GET_KEYRING_ID:
1160                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1161                                              (int) arg3);
1162
1163         case KEYCTL_JOIN_SESSION_KEYRING:
1164                 return keyctl_join_session_keyring((const char __user *) arg2);
1165
1166         case KEYCTL_UPDATE:
1167                 return keyctl_update_key((key_serial_t) arg2,
1168                                          (const void __user *) arg3,
1169                                          (size_t) arg4);
1170
1171         case KEYCTL_REVOKE:
1172                 return keyctl_revoke_key((key_serial_t) arg2);
1173
1174         case KEYCTL_DESCRIBE:
1175                 return keyctl_describe_key((key_serial_t) arg2,
1176                                            (char __user *) arg3,
1177                                            (unsigned) arg4);
1178
1179         case KEYCTL_CLEAR:
1180                 return keyctl_keyring_clear((key_serial_t) arg2);
1181
1182         case KEYCTL_LINK:
1183                 return keyctl_keyring_link((key_serial_t) arg2,
1184                                            (key_serial_t) arg3);
1185
1186         case KEYCTL_UNLINK:
1187                 return keyctl_keyring_unlink((key_serial_t) arg2,
1188                                              (key_serial_t) arg3);
1189
1190         case KEYCTL_SEARCH:
1191                 return keyctl_keyring_search((key_serial_t) arg2,
1192                                              (const char __user *) arg3,
1193                                              (const char __user *) arg4,
1194                                              (key_serial_t) arg5);
1195
1196         case KEYCTL_READ:
1197                 return keyctl_read_key((key_serial_t) arg2,
1198                                        (char __user *) arg3,
1199                                        (size_t) arg4);
1200
1201         case KEYCTL_CHOWN:
1202                 return keyctl_chown_key((key_serial_t) arg2,
1203                                         (uid_t) arg3,
1204                                         (gid_t) arg4);
1205
1206         case KEYCTL_SETPERM:
1207                 return keyctl_setperm_key((key_serial_t) arg2,
1208                                           (key_perm_t) arg3);
1209
1210         case KEYCTL_INSTANTIATE:
1211                 return keyctl_instantiate_key((key_serial_t) arg2,
1212                                               (const void __user *) arg3,
1213                                               (size_t) arg4,
1214                                               (key_serial_t) arg5);
1215
1216         case KEYCTL_NEGATE:
1217                 return keyctl_negate_key((key_serial_t) arg2,
1218                                          (unsigned) arg3,
1219                                          (key_serial_t) arg4);
1220
1221         case KEYCTL_SET_REQKEY_KEYRING:
1222                 return keyctl_set_reqkey_keyring(arg2);
1223
1224         case KEYCTL_SET_TIMEOUT:
1225                 return keyctl_set_timeout((key_serial_t) arg2,
1226                                           (unsigned) arg3);
1227
1228         case KEYCTL_ASSUME_AUTHORITY:
1229                 return keyctl_assume_authority((key_serial_t) arg2);
1230
1231         case KEYCTL_GET_SECURITY:
1232                 return keyctl_get_security((key_serial_t) arg2,
1233                                            (char *) arg3,
1234                                            (size_t) arg4);
1235
1236         default:
1237                 return -EOPNOTSUPP;
1238         }
1239
1240 } /* end sys_keyctl() */