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/err.h>
  20 #include <asm/uaccess.h>
  21 #include "internal.h"
  22
  23 /*****************************************************************************/
  24 /*
  25  * extract the description of a new key from userspace and either add it as a
  26  * new key to the specified keyring or update a matching key in that keyring
  27  * - the keyring must be writable
  28  * - returns the new key's serial number
  29  * - implements add_key()
  30  */
  31 asmlinkage long sys_add_key(const char __user *_type,
  32                             const char __user *_description,
  33                             const void __user *_payload,
  34                             size_t plen,
  35                             key_serial_t ringid)
  36 {
  37         key_ref_t keyring_ref, key_ref;
  38         char type[32], *description;
  39         void *payload;
  40         long dlen, ret;
  41
  42         ret = -EINVAL;
  43         if (plen > 32767)
  44                 goto error;
  45
  46         /* draw all the data into kernel space */
  47         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
  48         if (ret < 0)
  49                 goto error;
  50         type[31] = '\0';
  51
  52         ret = -EPERM;
  53         if (type[0] == '.')
  54                 goto error;
  55
  56         ret = -EFAULT;
  57         dlen = strnlen_user(_description, PAGE_SIZE - 1);
  58         if (dlen <= 0)
  59                 goto error;
  60
  61         ret = -EINVAL;
  62         if (dlen > PAGE_SIZE - 1)
  63                 goto error;
  64
  65         ret = -ENOMEM;
  66         description = kmalloc(dlen + 1, GFP_KERNEL);
  67         if (!description)
  68                 goto error;
  69
  70         ret = -EFAULT;
  71         if (copy_from_user(description, _description, dlen + 1) != 0)
  72                 goto error2;
  73
  74         /* pull the payload in if one was supplied */
  75         payload = NULL;
  76
  77         if (_payload) {
  78                 ret = -ENOMEM;
  79                 payload = kmalloc(plen, GFP_KERNEL);
  80                 if (!payload)
  81                         goto error2;
  82
  83                 ret = -EFAULT;
  84                 if (copy_from_user(payload, _payload, plen) != 0)
  85                         goto error3;
  86         }
  87
  88         /* find the target keyring (which must be writable) */
  89         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
  90         if (IS_ERR(keyring_ref)) {
  91                 ret = PTR_ERR(keyring_ref);
  92                 goto error3;
  93         }
  94
  95         /* create or update the requested key and add it to the target
  96          * keyring */
  97         key_ref = key_create_or_update(keyring_ref, type, description,
  98                                        payload, plen, 0);
  99         if (!IS_ERR(key_ref)) {
 100                 ret = key_ref_to_ptr(key_ref)->serial;
 101                 key_ref_put(key_ref);
 102         }
 103         else {
 104                 ret = PTR_ERR(key_ref);
 105         }
 106
 107         key_ref_put(keyring_ref);
 108  error3:
 109         kfree(payload);
 110  error2:
 111         kfree(description);
 112  error:
 113         return ret;
 114
 115 } /* end sys_add_key() */
 116
 117 /*****************************************************************************/
 118 /*
 119  * search the process keyrings for a matching key
 120  * - nested keyrings may also be searched if they have Search permission
 121  * - if a key is found, it will be attached to the destination keyring if
 122  *   there's one specified
 123  * - /sbin/request-key will be invoked if _callout_info is non-NULL
 124  *   - the _callout_info string will be passed to /sbin/request-key
 125  *   - if the _callout_info string is empty, it will be rendered as "-"
 126  * - implements request_key()
 127  */
 128 asmlinkage long sys_request_key(const char __user *_type,
 129                                 const char __user *_description,
 130                                 const char __user *_callout_info,
 131                                 key_serial_t destringid)
 132 {
 133         struct key_type *ktype;
 134         struct key *key;
 135         key_ref_t dest_ref;
 136         char type[32], *description, *callout_info;
 137         long dlen, ret;
 138
 139         /* pull the type into kernel space */
 140         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
 141         if (ret < 0)
 142                 goto error;
 143         type[31] = '\0';
 144
 145         ret = -EPERM;
 146         if (type[0] == '.')
 147                 goto error;
 148
 149         /* pull the description into kernel space */
 150         ret = -EFAULT;
 151         dlen = strnlen_user(_description, PAGE_SIZE - 1);
 152         if (dlen <= 0)
 153                 goto error;
 154
 155         ret = -EINVAL;
 156         if (dlen > PAGE_SIZE - 1)
 157                 goto error;
 158
 159         ret = -ENOMEM;
 160         description = kmalloc(dlen + 1, GFP_KERNEL);
 161         if (!description)
 162                 goto error;
 163
 164         ret = -EFAULT;
 165         if (copy_from_user(description, _description, dlen + 1) != 0)
 166                 goto error2;
 167
 168         /* pull the callout info into kernel space */
 169         callout_info = NULL;
 170         if (_callout_info) {
 171                 ret = -EFAULT;
 172                 dlen = strnlen_user(_callout_info, PAGE_SIZE - 1);
 173                 if (dlen <= 0)
 174                         goto error2;
 175
 176                 ret = -EINVAL;
 177                 if (dlen > PAGE_SIZE - 1)
 178                         goto error2;
 179
 180                 ret = -ENOMEM;
 181                 callout_info = kmalloc(dlen + 1, GFP_KERNEL);
 182                 if (!callout_info)
 183                         goto error2;
 184
 185                 ret = -EFAULT;
 186                 if (copy_from_user(callout_info, _callout_info, dlen + 1) != 0)
 187                         goto error3;
 188         }
 189
 190         /* get the destination keyring if specified */
 191         dest_ref = NULL;
 192         if (destringid) {
 193                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 194                 if (IS_ERR(dest_ref)) {
 195                         ret = PTR_ERR(dest_ref);
 196                         goto error3;
 197                 }
 198         }
 199
 200         /* find the key type */
 201         ktype = key_type_lookup(type);
 202         if (IS_ERR(ktype)) {
 203                 ret = PTR_ERR(ktype);
 204                 goto error4;
 205         }
 206
 207         /* do the search */
 208         key = request_key_and_link(ktype, description, callout_info,
 209                                    key_ref_to_ptr(dest_ref));
 210         if (IS_ERR(key)) {
 211                 ret = PTR_ERR(key);
 212                 goto error5;
 213         }
 214
 215         ret = key->serial;
 216
 217         key_put(key);
 218  error5:
 219         key_type_put(ktype);
 220  error4:
 221         key_ref_put(dest_ref);
 222  error3:
 223         kfree(callout_info);
 224  error2:
 225         kfree(description);
 226  error:
 227         return ret;
 228
 229 } /* end sys_request_key() */
 230
 231 /*****************************************************************************/
 232 /*
 233  * get the ID of the specified process keyring
 234  * - the keyring must have search permission to be found
 235  * - implements keyctl(KEYCTL_GET_KEYRING_ID)
 236  */
 237 long keyctl_get_keyring_ID(key_serial_t id, int create)
 238 {
 239         key_ref_t key_ref;
 240         long ret;
 241
 242         key_ref = lookup_user_key(NULL, id, create, 0, KEY_SEARCH);
 243         if (IS_ERR(key_ref)) {
 244                 ret = PTR_ERR(key_ref);
 245                 goto error;
 246         }
 247
 248         ret = key_ref_to_ptr(key_ref)->serial;
 249         key_ref_put(key_ref);
 250  error:
 251         return ret;
 252
 253 } /* end keyctl_get_keyring_ID() */
 254
 255 /*****************************************************************************/
 256 /*
 257  * join the session keyring
 258  * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
 259  */
 260 long keyctl_join_session_keyring(const char __user *_name)
 261 {
 262         char *name;
 263         long nlen, ret;
 264
 265         /* fetch the name from userspace */
 266         name = NULL;
 267         if (_name) {
 268                 ret = -EFAULT;
 269                 nlen = strnlen_user(_name, PAGE_SIZE - 1);
 270                 if (nlen <= 0)
 271                         goto error;
 272
 273                 ret = -EINVAL;
 274                 if (nlen > PAGE_SIZE - 1)
 275                         goto error;
 276
 277                 ret = -ENOMEM;
 278                 name = kmalloc(nlen + 1, GFP_KERNEL);
 279                 if (!name)
 280                         goto error;
 281
 282                 ret = -EFAULT;
 283                 if (copy_from_user(name, _name, nlen + 1) != 0)
 284                         goto error2;
 285         }
 286
 287         /* join the session */
 288         ret = join_session_keyring(name);
 289
 290  error2:
 291         kfree(name);
 292  error:
 293         return ret;
 294
 295 } /* end keyctl_join_session_keyring() */
 296
 297 /*****************************************************************************/
 298 /*
 299  * update a key's data payload
 300  * - the key must be writable
 301  * - implements keyctl(KEYCTL_UPDATE)
 302  */
 303 long keyctl_update_key(key_serial_t id,
 304                        const void __user *_payload,
 305                        size_t plen)
 306 {
 307         key_ref_t key_ref;
 308         void *payload;
 309         long ret;
 310
 311         ret = -EINVAL;
 312         if (plen > PAGE_SIZE)
 313                 goto error;
 314
 315         /* pull the payload in if one was supplied */
 316         payload = NULL;
 317         if (_payload) {
 318                 ret = -ENOMEM;
 319                 payload = kmalloc(plen, GFP_KERNEL);
 320                 if (!payload)
 321                         goto error;
 322
 323                 ret = -EFAULT;
 324                 if (copy_from_user(payload, _payload, plen) != 0)
 325                         goto error2;
 326         }
 327
 328         /* find the target key (which must be writable) */
 329         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 330         if (IS_ERR(key_ref)) {
 331                 ret = PTR_ERR(key_ref);
 332                 goto error2;
 333         }
 334
 335         /* update the key */
 336         ret = key_update(key_ref, payload, plen);
 337
 338         key_ref_put(key_ref);
 339  error2:
 340         kfree(payload);
 341  error:
 342         return ret;
 343
 344 } /* end keyctl_update_key() */
 345
 346 /*****************************************************************************/
 347 /*
 348  * revoke a key
 349  * - the key must be writable
 350  * - implements keyctl(KEYCTL_REVOKE)
 351  */
 352 long keyctl_revoke_key(key_serial_t id)
 353 {
 354         key_ref_t key_ref;
 355         long ret;
 356
 357         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 358         if (IS_ERR(key_ref)) {
 359                 ret = PTR_ERR(key_ref);
 360                 goto error;
 361         }
 362
 363         key_revoke(key_ref_to_ptr(key_ref));
 364         ret = 0;
 365
 366         key_ref_put(key_ref);
 367  error:
 368         return ret;
 369
 370 } /* end keyctl_revoke_key() */
 371
 372 /*****************************************************************************/
 373 /*
 374  * clear the specified process keyring
 375  * - the keyring must be writable
 376  * - implements keyctl(KEYCTL_CLEAR)
 377  */
 378 long keyctl_keyring_clear(key_serial_t ringid)
 379 {
 380         key_ref_t keyring_ref;
 381         long ret;
 382
 383         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 384         if (IS_ERR(keyring_ref)) {
 385                 ret = PTR_ERR(keyring_ref);
 386                 goto error;
 387         }
 388
 389         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 390
 391         key_ref_put(keyring_ref);
 392  error:
 393         return ret;
 394
 395 } /* end keyctl_keyring_clear() */
 396
 397 /*****************************************************************************/
 398 /*
 399  * link a key into a keyring
 400  * - the keyring must be writable
 401  * - the key must be linkable
 402  * - implements keyctl(KEYCTL_LINK)
 403  */
 404 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 405 {
 406         key_ref_t keyring_ref, key_ref;
 407         long ret;
 408
 409         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 410         if (IS_ERR(keyring_ref)) {
 411                 ret = PTR_ERR(keyring_ref);
 412                 goto error;
 413         }
 414
 415         key_ref = lookup_user_key(NULL, id, 1, 0, KEY_LINK);
 416         if (IS_ERR(key_ref)) {
 417                 ret = PTR_ERR(key_ref);
 418                 goto error2;
 419         }
 420
 421         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 422
 423         key_ref_put(key_ref);
 424  error2:
 425         key_ref_put(keyring_ref);
 426  error:
 427         return ret;
 428
 429 } /* end keyctl_keyring_link() */
 430
 431 /*****************************************************************************/
 432 /*
 433  * unlink the first attachment of a key from a keyring
 434  * - the keyring must be writable
 435  * - we don't need any permissions on the key
 436  * - implements keyctl(KEYCTL_UNLINK)
 437  */
 438 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 439 {
 440         key_ref_t keyring_ref, key_ref;
 441         long ret;
 442
 443         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_WRITE);
 444         if (IS_ERR(keyring_ref)) {
 445                 ret = PTR_ERR(keyring_ref);
 446                 goto error;
 447         }
 448
 449         key_ref = lookup_user_key(NULL, id, 0, 0, 0);
 450         if (IS_ERR(key_ref)) {
 451                 ret = PTR_ERR(key_ref);
 452                 goto error2;
 453         }
 454
 455         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 456
 457         key_ref_put(key_ref);
 458  error2:
 459         key_ref_put(keyring_ref);
 460  error:
 461         return ret;
 462
 463 } /* end keyctl_keyring_unlink() */
 464
 465 /*****************************************************************************/
 466 /*
 467  * describe a user key
 468  * - the key must have view permission
 469  * - if there's a buffer, we place up to buflen bytes of data into it
 470  * - unless there's an error, we return the amount of description available,
 471  *   irrespective of how much we may have copied
 472  * - the description is formatted thus:
 473  *      type;uid;gid;perm;description<NUL>
 474  * - implements keyctl(KEYCTL_DESCRIBE)
 475  */
 476 long keyctl_describe_key(key_serial_t keyid,
 477                          char __user *buffer,
 478                          size_t buflen)
 479 {
 480         struct key *key, *instkey;
 481         key_ref_t key_ref;
 482         char *tmpbuf;
 483         long ret;
 484
 485         key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
 486         if (IS_ERR(key_ref)) {
 487                 /* viewing a key under construction is permitted if we have the
 488                  * authorisation token handy */
 489                 if (PTR_ERR(key_ref) == -EACCES) {
 490                         instkey = key_get_instantiation_authkey(keyid);
 491                         if (!IS_ERR(instkey)) {
 492                                 key_put(instkey);
 493                                 key_ref = lookup_user_key(NULL, keyid,
 494                                                           0, 1, 0);
 495                                 if (!IS_ERR(key_ref))
 496                                         goto okay;
 497                         }
 498                 }
 499
 500                 ret = PTR_ERR(key_ref);
 501                 goto error;
 502         }
 503
 504 okay:
 505         /* calculate how much description we're going to return */
 506         ret = -ENOMEM;
 507         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 508         if (!tmpbuf)
 509                 goto error2;
 510
 511         key = key_ref_to_ptr(key_ref);
 512
 513         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 514                        "%s;%d;%d;%08x;%s",
 515                        key_ref_to_ptr(key_ref)->type->name,
 516                        key_ref_to_ptr(key_ref)->uid,
 517                        key_ref_to_ptr(key_ref)->gid,
 518                        key_ref_to_ptr(key_ref)->perm,
 519                        key_ref_to_ptr(key_ref)->description ?
 520                        key_ref_to_ptr(key_ref)->description : ""
 521                        );
 522
 523         /* include a NUL char at the end of the data */
 524         if (ret > PAGE_SIZE - 1)
 525                 ret = PAGE_SIZE - 1;
 526         tmpbuf[ret] = 0;
 527         ret++;
 528
 529         /* consider returning the data */
 530         if (buffer && buflen > 0) {
 531                 if (buflen > ret)
 532                         buflen = ret;
 533
 534                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 535                         ret = -EFAULT;
 536         }
 537
 538         kfree(tmpbuf);
 539  error2:
 540         key_ref_put(key_ref);
 541  error:
 542         return ret;
 543
 544 } /* end keyctl_describe_key() */
 545
 546 /*****************************************************************************/
 547 /*
 548  * search the specified keyring for a matching key
 549  * - the start keyring must be searchable
 550  * - nested keyrings may also be searched if they are searchable
 551  * - only keys with search permission may be found
 552  * - if a key is found, it will be attached to the destination keyring if
 553  *   there's one specified
 554  * - implements keyctl(KEYCTL_SEARCH)
 555  */
 556 long keyctl_keyring_search(key_serial_t ringid,
 557                            const char __user *_type,
 558                            const char __user *_description,
 559                            key_serial_t destringid)
 560 {
 561         struct key_type *ktype;
 562         key_ref_t keyring_ref, key_ref, dest_ref;
 563         char type[32], *description;
 564         long dlen, ret;
 565
 566         /* pull the type and description into kernel space */
 567         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
 568         if (ret < 0)
 569                 goto error;
 570         type[31] = '\0';
 571
 572         ret = -EFAULT;
 573         dlen = strnlen_user(_description, PAGE_SIZE - 1);
 574         if (dlen <= 0)
 575                 goto error;
 576
 577         ret = -EINVAL;
 578         if (dlen > PAGE_SIZE - 1)
 579                 goto error;
 580
 581         ret = -ENOMEM;
 582         description = kmalloc(dlen + 1, GFP_KERNEL);
 583         if (!description)
 584                 goto error;
 585
 586         ret = -EFAULT;
 587         if (copy_from_user(description, _description, dlen + 1) != 0)
 588                 goto error2;
 589
 590         /* get the keyring at which to begin the search */
 591         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_SEARCH);
 592         if (IS_ERR(keyring_ref)) {
 593                 ret = PTR_ERR(keyring_ref);
 594                 goto error2;
 595         }
 596
 597         /* get the destination keyring if specified */
 598         dest_ref = NULL;
 599         if (destringid) {
 600                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 601                 if (IS_ERR(dest_ref)) {
 602                         ret = PTR_ERR(dest_ref);
 603                         goto error3;
 604                 }
 605         }
 606
 607         /* find the key type */
 608         ktype = key_type_lookup(type);
 609         if (IS_ERR(ktype)) {
 610                 ret = PTR_ERR(ktype);
 611                 goto error4;
 612         }
 613
 614         /* do the search */
 615         key_ref = keyring_search(keyring_ref, ktype, description);
 616         if (IS_ERR(key_ref)) {
 617                 ret = PTR_ERR(key_ref);
 618
 619                 /* treat lack or presence of a negative key the same */
 620                 if (ret == -EAGAIN)
 621                         ret = -ENOKEY;
 622                 goto error5;
 623         }
 624
 625         /* link the resulting key to the destination keyring if we can */
 626         if (dest_ref) {
 627                 ret = key_permission(key_ref, KEY_LINK);
 628                 if (ret < 0)
 629                         goto error6;
 630
 631                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 632                 if (ret < 0)
 633                         goto error6;
 634         }
 635
 636         ret = key_ref_to_ptr(key_ref)->serial;
 637
 638  error6:
 639         key_ref_put(key_ref);
 640  error5:
 641         key_type_put(ktype);
 642  error4:
 643         key_ref_put(dest_ref);
 644  error3:
 645         key_ref_put(keyring_ref);
 646  error2:
 647         kfree(description);
 648  error:
 649         return ret;
 650
 651 } /* end keyctl_keyring_search() */
 652
 653 /*****************************************************************************/
 654 /*
 655  * read a user key's payload
 656  * - the keyring must be readable or the key must be searchable from the
 657  *   process's keyrings
 658  * - if there's a buffer, we place up to buflen bytes of data into it
 659  * - unless there's an error, we return the amount of data in the key,
 660  *   irrespective of how much we may have copied
 661  * - implements keyctl(KEYCTL_READ)
 662  */
 663 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 664 {
 665         struct key *key;
 666         key_ref_t key_ref;
 667         long ret;
 668
 669         /* find the key first */
 670         key_ref = lookup_user_key(NULL, keyid, 0, 0, 0);
 671         if (IS_ERR(key_ref)) {
 672                 ret = -ENOKEY;
 673                 goto error;
 674         }
 675
 676         key = key_ref_to_ptr(key_ref);
 677
 678         /* see if we can read it directly */
 679         ret = key_permission(key_ref, KEY_READ);
 680         if (ret == 0)
 681                 goto can_read_key;
 682         if (ret != -EACCES)
 683                 goto error;
 684
 685         /* we can't; see if it's searchable from this process's keyrings
 686          * - we automatically take account of the fact that it may be
 687          *   dangling off an instantiation key
 688          */
 689         if (!is_key_possessed(key_ref)) {
 690                 ret = -EACCES;
 691                 goto error2;
 692         }
 693
 694         /* the key is probably readable - now try to read it */
 695  can_read_key:
 696         ret = key_validate(key);
 697         if (ret == 0) {
 698                 ret = -EOPNOTSUPP;
 699                 if (key->type->read) {
 700                         /* read the data with the semaphore held (since we
 701                          * might sleep) */
 702                         down_read(&key->sem);
 703                         ret = key->type->read(key, buffer, buflen);
 704                         up_read(&key->sem);
 705                 }
 706         }
 707
 708  error2:
 709         key_put(key);
 710  error:
 711         return ret;
 712
 713 } /* end keyctl_read_key() */
 714
 715 /*****************************************************************************/
 716 /*
 717  * change the ownership of a key
 718  * - the keyring owned by the changer
 719  * - if the uid or gid is -1, then that parameter is not changed
 720  * - implements keyctl(KEYCTL_CHOWN)
 721  */
 722 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 723 {
 724         struct key *key;
 725         key_ref_t key_ref;
 726         long ret;
 727
 728         ret = 0;
 729         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 730                 goto error;
 731
 732         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 733         if (IS_ERR(key_ref)) {
 734                 ret = PTR_ERR(key_ref);
 735                 goto error;
 736         }
 737
 738         key = key_ref_to_ptr(key_ref);
 739
 740         /* make the changes with the locks held to prevent chown/chown races */
 741         ret = -EACCES;
 742         down_write(&key->sem);
 743
 744         if (!capable(CAP_SYS_ADMIN)) {
 745                 /* only the sysadmin can chown a key to some other UID */
 746                 if (uid != (uid_t) -1 && key->uid != uid)
 747                         goto no_access;
 748
 749                 /* only the sysadmin can set the key's GID to a group other
 750                  * than one of those that the current process subscribes to */
 751                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 752                         goto no_access;
 753         }
 754
 755         /* change the UID (have to update the quotas) */
 756         if (uid != (uid_t) -1 && uid != key->uid) {
 757                 /* don't support UID changing yet */
 758                 ret = -EOPNOTSUPP;
 759                 goto no_access;
 760         }
 761
 762         /* change the GID */
 763         if (gid != (gid_t) -1)
 764                 key->gid = gid;
 765
 766         ret = 0;
 767
 768  no_access:
 769         up_write(&key->sem);
 770         key_put(key);
 771  error:
 772         return ret;
 773
 774 } /* end keyctl_chown_key() */
 775
 776 /*****************************************************************************/
 777 /*
 778  * change the permission mask on a key
 779  * - the keyring owned by the changer
 780  * - implements keyctl(KEYCTL_SETPERM)
 781  */
 782 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 783 {
 784         struct key *key;
 785         key_ref_t key_ref;
 786         long ret;
 787
 788         ret = -EINVAL;
 789         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 790                 goto error;
 791
 792         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 793         if (IS_ERR(key_ref)) {
 794                 ret = PTR_ERR(key_ref);
 795                 goto error;
 796         }
 797
 798         key = key_ref_to_ptr(key_ref);
 799
 800         /* make the changes with the locks held to prevent chown/chmod races */
 801         ret = -EACCES;
 802         down_write(&key->sem);
 803
 804         /* if we're not the sysadmin, we can only change a key that we own */
 805         if (capable(CAP_SYS_ADMIN) || key->uid == current->fsuid) {
 806                 key->perm = perm;
 807                 ret = 0;
 808         }
 809
 810         up_write(&key->sem);
 811         key_put(key);
 812 error:
 813         return ret;
 814
 815 } /* end keyctl_setperm_key() */
 816
 817 /*****************************************************************************/
 818 /*
 819  * instantiate the key with the specified payload, and, if one is given, link
 820  * the key into the keyring
 821  */
 822 long keyctl_instantiate_key(key_serial_t id,
 823                             const void __user *_payload,
 824                             size_t plen,
 825                             key_serial_t ringid)
 826 {
 827         struct request_key_auth *rka;
 828         struct key *instkey;
 829         key_ref_t keyring_ref;
 830         void *payload;
 831         long ret;
 832
 833         ret = -EINVAL;
 834         if (plen > 32767)
 835                 goto error;
 836
 837         /* the appropriate instantiation authorisation key must have been
 838          * assumed before calling this */
 839         ret = -EPERM;
 840         instkey = current->request_key_auth;
 841         if (!instkey)
 842                 goto error;
 843
 844         rka = instkey->payload.data;
 845         if (rka->target_key->serial != id)
 846                 goto error;
 847
 848         /* pull the payload in if one was supplied */
 849         payload = NULL;
 850
 851         if (_payload) {
 852                 ret = -ENOMEM;
 853                 payload = kmalloc(plen, GFP_KERNEL);
 854                 if (!payload)
 855                         goto error;
 856
 857                 ret = -EFAULT;
 858                 if (copy_from_user(payload, _payload, plen) != 0)
 859                         goto error2;
 860         }
 861
 862         /* find the destination keyring amongst those belonging to the
 863          * requesting task */
 864         keyring_ref = NULL;
 865         if (ringid) {
 866                 keyring_ref = lookup_user_key(rka->context, ringid, 1, 0,
 867                                               KEY_WRITE);
 868                 if (IS_ERR(keyring_ref)) {
 869                         ret = PTR_ERR(keyring_ref);
 870                         goto error2;
 871                 }
 872         }
 873
 874         /* instantiate the key and link it into a keyring */
 875         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 876                                        key_ref_to_ptr(keyring_ref), instkey);
 877
 878         key_ref_put(keyring_ref);
 879
 880         /* discard the assumed authority if it's just been disabled by
 881          * instantiation of the key */
 882         if (ret == 0) {
 883                 key_put(current->request_key_auth);
 884                 current->request_key_auth = NULL;
 885         }
 886
 887 error2:
 888         kfree(payload);
 889 error:
 890         return ret;
 891
 892 } /* end keyctl_instantiate_key() */
 893
 894 /*****************************************************************************/
 895 /*
 896  * negatively instantiate the key with the given timeout (in seconds), and, if
 897  * one is given, link the key into the keyring
 898  */
 899 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 900 {
 901         struct request_key_auth *rka;
 902         struct key *instkey;
 903         key_ref_t keyring_ref;
 904         long ret;
 905
 906         /* the appropriate instantiation authorisation key must have been
 907          * assumed before calling this */
 908         ret = -EPERM;
 909         instkey = current->request_key_auth;
 910         if (!instkey)
 911                 goto error;
 912
 913         rka = instkey->payload.data;
 914         if (rka->target_key->serial != id)
 915                 goto error;
 916
 917         /* find the destination keyring if present (which must also be
 918          * writable) */
 919         keyring_ref = NULL;
 920         if (ringid) {
 921                 keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 922                 if (IS_ERR(keyring_ref)) {
 923                         ret = PTR_ERR(keyring_ref);
 924                         goto error;
 925                 }
 926         }
 927
 928         /* instantiate the key and link it into a keyring */
 929         ret = key_negate_and_link(rka->target_key, timeout,
 930                                   key_ref_to_ptr(keyring_ref), instkey);
 931
 932         key_ref_put(keyring_ref);
 933
 934         /* discard the assumed authority if it's just been disabled by
 935          * instantiation of the key */
 936         if (ret == 0) {
 937                 key_put(current->request_key_auth);
 938                 current->request_key_auth = NULL;
 939         }
 940
 941 error:
 942         return ret;
 943
 944 } /* end keyctl_negate_key() */
 945
 946 /*****************************************************************************/
 947 /*
 948  * set the default keyring in which request_key() will cache keys
 949  * - return the old setting
 950  */
 951 long keyctl_set_reqkey_keyring(int reqkey_defl)
 952 {
 953         int ret;
 954
 955         switch (reqkey_defl) {
 956         case KEY_REQKEY_DEFL_THREAD_KEYRING:
 957                 ret = install_thread_keyring(current);
 958                 if (ret < 0)
 959                         return ret;
 960                 goto set;
 961
 962         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 963                 ret = install_process_keyring(current);
 964                 if (ret < 0)
 965                         return ret;
 966
 967         case KEY_REQKEY_DEFL_DEFAULT:
 968         case KEY_REQKEY_DEFL_SESSION_KEYRING:
 969         case KEY_REQKEY_DEFL_USER_KEYRING:
 970         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 971         set:
 972                 current->jit_keyring = reqkey_defl;
 973
 974         case KEY_REQKEY_DEFL_NO_CHANGE:
 975                 return current->jit_keyring;
 976
 977         case KEY_REQKEY_DEFL_GROUP_KEYRING:
 978         default:
 979                 return -EINVAL;
 980         }
 981
 982 } /* end keyctl_set_reqkey_keyring() */
 983
 984 /*****************************************************************************/
 985 /*
 986  * set or clear the timeout for a key
 987  */
 988 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
 989 {
 990         struct timespec now;
 991         struct key *key;
 992         key_ref_t key_ref;
 993         time_t expiry;
 994         long ret;
 995
 996         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 997         if (IS_ERR(key_ref)) {
 998                 ret = PTR_ERR(key_ref);
 999                 goto error;
1000         }
1001
1002         key = key_ref_to_ptr(key_ref);
1003
1004         /* make the changes with the locks held to prevent races */
1005         down_write(&key->sem);
1006
1007         expiry = 0;
1008         if (timeout > 0) {
1009                 now = current_kernel_time();
1010                 expiry = now.tv_sec + timeout;
1011         }
1012
1013         key->expiry = expiry;
1014
1015         up_write(&key->sem);
1016         key_put(key);
1017
1018         ret = 0;
1019 error:
1020         return ret;
1021
1022 } /* end keyctl_set_timeout() */
1023
1024 /*****************************************************************************/
1025 /*
1026  * assume the authority to instantiate the specified key
1027  */
1028 long keyctl_assume_authority(key_serial_t id)
1029 {
1030         struct key *authkey;
1031         long ret;
1032
1033         /* special key IDs aren't permitted */
1034         ret = -EINVAL;
1035         if (id < 0)
1036                 goto error;
1037
1038         /* we divest ourselves of authority if given an ID of 0 */
1039         if (id == 0) {
1040                 key_put(current->request_key_auth);
1041                 current->request_key_auth = NULL;
1042                 ret = 0;
1043                 goto error;
1044         }
1045
1046         /* attempt to assume the authority temporarily granted to us whilst we
1047          * instantiate the specified key
1048          * - the authorisation key must be in the current task's keyrings
1049          *   somewhere
1050          */
1051         authkey = key_get_instantiation_authkey(id);
1052         if (IS_ERR(authkey)) {
1053                 ret = PTR_ERR(authkey);
1054                 goto error;
1055         }
1056
1057         key_put(current->request_key_auth);
1058         current->request_key_auth = authkey;
1059         ret = authkey->serial;
1060
1061 error:
1062         return ret;
1063
1064 } /* end keyctl_assume_authority() */
1065
1066 /*****************************************************************************/
1067 /*
1068  * the key control system call
1069  */
1070 asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
1071                            unsigned long arg4, unsigned long arg5)
1072 {
1073         switch (option) {
1074         case KEYCTL_GET_KEYRING_ID:
1075                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1076                                              (int) arg3);
1077
1078         case KEYCTL_JOIN_SESSION_KEYRING:
1079                 return keyctl_join_session_keyring((const char __user *) arg2);
1080
1081         case KEYCTL_UPDATE:
1082                 return keyctl_update_key((key_serial_t) arg2,
1083                                          (const void __user *) arg3,
1084                                          (size_t) arg4);
1085
1086         case KEYCTL_REVOKE:
1087                 return keyctl_revoke_key((key_serial_t) arg2);
1088
1089         case KEYCTL_DESCRIBE:
1090                 return keyctl_describe_key((key_serial_t) arg2,
1091                                            (char __user *) arg3,
1092                                            (unsigned) arg4);
1093
1094         case KEYCTL_CLEAR:
1095                 return keyctl_keyring_clear((key_serial_t) arg2);
1096
1097         case KEYCTL_LINK:
1098                 return keyctl_keyring_link((key_serial_t) arg2,
1099                                            (key_serial_t) arg3);
1100
1101         case KEYCTL_UNLINK:
1102                 return keyctl_keyring_unlink((key_serial_t) arg2,
1103                                              (key_serial_t) arg3);
1104
1105         case KEYCTL_SEARCH:
1106                 return keyctl_keyring_search((key_serial_t) arg2,
1107                                              (const char __user *) arg3,
1108                                              (const char __user *) arg4,
1109                                              (key_serial_t) arg5);
1110
1111         case KEYCTL_READ:
1112                 return keyctl_read_key((key_serial_t) arg2,
1113                                        (char __user *) arg3,
1114                                        (size_t) arg4);
1115
1116         case KEYCTL_CHOWN:
1117                 return keyctl_chown_key((key_serial_t) arg2,
1118                                         (uid_t) arg3,
1119                                         (gid_t) arg4);
1120
1121         case KEYCTL_SETPERM:
1122                 return keyctl_setperm_key((key_serial_t) arg2,
1123                                           (key_perm_t) arg3);
1124
1125         case KEYCTL_INSTANTIATE:
1126                 return keyctl_instantiate_key((key_serial_t) arg2,
1127                                               (const void __user *) arg3,
1128                                               (size_t) arg4,
1129                                               (key_serial_t) arg5);
1130
1131         case KEYCTL_NEGATE:
1132                 return keyctl_negate_key((key_serial_t) arg2,
1133                                          (unsigned) arg3,
1134                                          (key_serial_t) arg4);
1135
1136         case KEYCTL_SET_REQKEY_KEYRING:
1137                 return keyctl_set_reqkey_keyring(arg2);
1138
1139         case KEYCTL_SET_TIMEOUT:
1140                 return keyctl_set_timeout((key_serial_t) arg2,
1141                                           (unsigned) arg3);
1142
1143         case KEYCTL_ASSUME_AUTHORITY:
1144                 return keyctl_assume_authority((key_serial_t) arg2);
1145
1146         default:
1147                 return -EOPNOTSUPP;
1148         }
1149
1150 } /* end sys_keyctl() */