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 = -EACCES;
 628                 if (!key_permission(key_ref, KEY_LINK))
 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         if (key_permission(key_ref, KEY_READ))
 680                 goto can_read_key;
 681
 682         /* we can't; see if it's searchable from this process's keyrings
 683          * - we automatically take account of the fact that it may be
 684          *   dangling off an instantiation key
 685          */
 686         if (!is_key_possessed(key_ref)) {
 687                 ret = -EACCES;
 688                 goto error2;
 689         }
 690
 691         /* the key is probably readable - now try to read it */
 692  can_read_key:
 693         ret = key_validate(key);
 694         if (ret == 0) {
 695                 ret = -EOPNOTSUPP;
 696                 if (key->type->read) {
 697                         /* read the data with the semaphore held (since we
 698                          * might sleep) */
 699                         down_read(&key->sem);
 700                         ret = key->type->read(key, buffer, buflen);
 701                         up_read(&key->sem);
 702                 }
 703         }
 704
 705  error2:
 706         key_put(key);
 707  error:
 708         return ret;
 709
 710 } /* end keyctl_read_key() */
 711
 712 /*****************************************************************************/
 713 /*
 714  * change the ownership of a key
 715  * - the keyring owned by the changer
 716  * - if the uid or gid is -1, then that parameter is not changed
 717  * - implements keyctl(KEYCTL_CHOWN)
 718  */
 719 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 720 {
 721         struct key *key;
 722         key_ref_t key_ref;
 723         long ret;
 724
 725         ret = 0;
 726         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 727                 goto error;
 728
 729         key_ref = lookup_user_key(NULL, id, 1, 1, 0);
 730         if (IS_ERR(key_ref)) {
 731                 ret = PTR_ERR(key_ref);
 732                 goto error;
 733         }
 734
 735         key = key_ref_to_ptr(key_ref);
 736
 737         /* make the changes with the locks held to prevent chown/chown races */
 738         ret = -EACCES;
 739         down_write(&key->sem);
 740
 741         if (!capable(CAP_SYS_ADMIN)) {
 742                 /* only the sysadmin can chown a key to some other UID */
 743                 if (uid != (uid_t) -1 && key->uid != uid)
 744                         goto no_access;
 745
 746                 /* only the sysadmin can set the key's GID to a group other
 747                  * than one of those that the current process subscribes to */
 748                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 749                         goto no_access;
 750         }
 751
 752         /* change the UID (have to update the quotas) */
 753         if (uid != (uid_t) -1 && uid != key->uid) {
 754                 /* don't support UID changing yet */
 755                 ret = -EOPNOTSUPP;
 756                 goto no_access;
 757         }
 758
 759         /* change the GID */
 760         if (gid != (gid_t) -1)
 761                 key->gid = gid;
 762
 763         ret = 0;
 764
 765  no_access:
 766         up_write(&key->sem);
 767         key_put(key);
 768  error:
 769         return ret;
 770
 771 } /* end keyctl_chown_key() */
 772
 773 /*****************************************************************************/
 774 /*
 775  * change the permission mask on a key
 776  * - the keyring owned by the changer
 777  * - implements keyctl(KEYCTL_SETPERM)
 778  */
 779 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 780 {
 781         struct key *key;
 782         key_ref_t key_ref;
 783         long ret;
 784
 785         ret = -EINVAL;
 786         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 787                 goto error;
 788
 789         key_ref = lookup_user_key(NULL, id, 1, 1, 0);
 790         if (IS_ERR(key_ref)) {
 791                 ret = PTR_ERR(key_ref);
 792                 goto error;
 793         }
 794
 795         key = key_ref_to_ptr(key_ref);
 796
 797         /* make the changes with the locks held to prevent chown/chmod races */
 798         ret = -EACCES;
 799         down_write(&key->sem);
 800
 801         /* if we're not the sysadmin, we can only change a key that we own */
 802         if (capable(CAP_SYS_ADMIN) || key->uid == current->fsuid) {
 803                 key->perm = perm;
 804                 ret = 0;
 805         }
 806
 807         up_write(&key->sem);
 808         key_put(key);
 809 error:
 810         return ret;
 811
 812 } /* end keyctl_setperm_key() */
 813
 814 /*****************************************************************************/
 815 /*
 816  * instantiate the key with the specified payload, and, if one is given, link
 817  * the key into the keyring
 818  */
 819 long keyctl_instantiate_key(key_serial_t id,
 820                             const void __user *_payload,
 821                             size_t plen,
 822                             key_serial_t ringid)
 823 {
 824         struct request_key_auth *rka;
 825         struct key *instkey;
 826         key_ref_t keyring_ref;
 827         void *payload;
 828         long ret;
 829
 830         ret = -EINVAL;
 831         if (plen > 32767)
 832                 goto error;
 833
 834         /* pull the payload in if one was supplied */
 835         payload = NULL;
 836
 837         if (_payload) {
 838                 ret = -ENOMEM;
 839                 payload = kmalloc(plen, GFP_KERNEL);
 840                 if (!payload)
 841                         goto error;
 842
 843                 ret = -EFAULT;
 844                 if (copy_from_user(payload, _payload, plen) != 0)
 845                         goto error2;
 846         }
 847
 848         /* find the instantiation authorisation key */
 849         instkey = key_get_instantiation_authkey(id);
 850         if (IS_ERR(instkey)) {
 851                 ret = PTR_ERR(instkey);
 852                 goto error2;
 853         }
 854
 855         rka = instkey->payload.data;
 856
 857         /* find the destination keyring amongst those belonging to the
 858          * requesting task */
 859         keyring_ref = NULL;
 860         if (ringid) {
 861                 keyring_ref = lookup_user_key(rka->context, ringid, 1, 0,
 862                                               KEY_WRITE);
 863                 if (IS_ERR(keyring_ref)) {
 864                         ret = PTR_ERR(keyring_ref);
 865                         goto error3;
 866                 }
 867         }
 868
 869         /* instantiate the key and link it into a keyring */
 870         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 871                                        key_ref_to_ptr(keyring_ref), instkey);
 872
 873         key_ref_put(keyring_ref);
 874  error3:
 875         key_put(instkey);
 876  error2:
 877         kfree(payload);
 878  error:
 879         return ret;
 880
 881 } /* end keyctl_instantiate_key() */
 882
 883 /*****************************************************************************/
 884 /*
 885  * negatively instantiate the key with the given timeout (in seconds), and, if
 886  * one is given, link the key into the keyring
 887  */
 888 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 889 {
 890         struct request_key_auth *rka;
 891         struct key *instkey;
 892         key_ref_t keyring_ref;
 893         long ret;
 894
 895         /* find the instantiation authorisation key */
 896         instkey = key_get_instantiation_authkey(id);
 897         if (IS_ERR(instkey)) {
 898                 ret = PTR_ERR(instkey);
 899                 goto error;
 900         }
 901
 902         rka = instkey->payload.data;
 903
 904         /* find the destination keyring if present (which must also be
 905          * writable) */
 906         keyring_ref = NULL;
 907         if (ringid) {
 908                 keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 909                 if (IS_ERR(keyring_ref)) {
 910                         ret = PTR_ERR(keyring_ref);
 911                         goto error2;
 912                 }
 913         }
 914
 915         /* instantiate the key and link it into a keyring */
 916         ret = key_negate_and_link(rka->target_key, timeout,
 917                                   key_ref_to_ptr(keyring_ref), instkey);
 918
 919         key_ref_put(keyring_ref);
 920  error2:
 921         key_put(instkey);
 922  error:
 923         return ret;
 924
 925 } /* end keyctl_negate_key() */
 926
 927 /*****************************************************************************/
 928 /*
 929  * set the default keyring in which request_key() will cache keys
 930  * - return the old setting
 931  */
 932 long keyctl_set_reqkey_keyring(int reqkey_defl)
 933 {
 934         int ret;
 935
 936         switch (reqkey_defl) {
 937         case KEY_REQKEY_DEFL_THREAD_KEYRING:
 938                 ret = install_thread_keyring(current);
 939                 if (ret < 0)
 940                         return ret;
 941                 goto set;
 942
 943         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 944                 ret = install_process_keyring(current);
 945                 if (ret < 0)
 946                         return ret;
 947
 948         case KEY_REQKEY_DEFL_DEFAULT:
 949         case KEY_REQKEY_DEFL_SESSION_KEYRING:
 950         case KEY_REQKEY_DEFL_USER_KEYRING:
 951         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 952         set:
 953                 current->jit_keyring = reqkey_defl;
 954
 955         case KEY_REQKEY_DEFL_NO_CHANGE:
 956                 return current->jit_keyring;
 957
 958         case KEY_REQKEY_DEFL_GROUP_KEYRING:
 959         default:
 960                 return -EINVAL;
 961         }
 962
 963 } /* end keyctl_set_reqkey_keyring() */
 964
 965 /*****************************************************************************/
 966 /*
 967  * the key control system call
 968  */
 969 asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
 970                            unsigned long arg4, unsigned long arg5)
 971 {
 972         switch (option) {
 973         case KEYCTL_GET_KEYRING_ID:
 974                 return keyctl_get_keyring_ID((key_serial_t) arg2,
 975                                              (int) arg3);
 976
 977         case KEYCTL_JOIN_SESSION_KEYRING:
 978                 return keyctl_join_session_keyring((const char __user *) arg2);
 979
 980         case KEYCTL_UPDATE:
 981                 return keyctl_update_key((key_serial_t) arg2,
 982                                          (const void __user *) arg3,
 983                                          (size_t) arg4);
 984
 985         case KEYCTL_REVOKE:
 986                 return keyctl_revoke_key((key_serial_t) arg2);
 987
 988         case KEYCTL_DESCRIBE:
 989                 return keyctl_describe_key((key_serial_t) arg2,
 990                                            (char __user *) arg3,
 991                                            (unsigned) arg4);
 992
 993         case KEYCTL_CLEAR:
 994                 return keyctl_keyring_clear((key_serial_t) arg2);
 995
 996         case KEYCTL_LINK:
 997                 return keyctl_keyring_link((key_serial_t) arg2,
 998                                            (key_serial_t) arg3);
 999
1000         case KEYCTL_UNLINK:
1001                 return keyctl_keyring_unlink((key_serial_t) arg2,
1002                                              (key_serial_t) arg3);
1003
1004         case KEYCTL_SEARCH:
1005                 return keyctl_keyring_search((key_serial_t) arg2,
1006                                              (const char __user *) arg3,
1007                                              (const char __user *) arg4,
1008                                              (key_serial_t) arg5);
1009
1010         case KEYCTL_READ:
1011                 return keyctl_read_key((key_serial_t) arg2,
1012                                        (char __user *) arg3,
1013                                        (size_t) arg4);
1014
1015         case KEYCTL_CHOWN:
1016                 return keyctl_chown_key((key_serial_t) arg2,
1017                                         (uid_t) arg3,
1018                                         (gid_t) arg4);
1019
1020         case KEYCTL_SETPERM:
1021                 return keyctl_setperm_key((key_serial_t) arg2,
1022                                           (key_perm_t) arg3);
1023
1024         case KEYCTL_INSTANTIATE:
1025                 return keyctl_instantiate_key((key_serial_t) arg2,
1026                                               (const void __user *) arg3,
1027                                               (size_t) arg4,
1028                                               (key_serial_t) arg5);
1029
1030         case KEYCTL_NEGATE:
1031                 return keyctl_negate_key((key_serial_t) arg2,
1032                                          (unsigned) arg3,
1033                                          (key_serial_t) arg4);
1034
1035         case KEYCTL_SET_REQKEY_KEYRING:
1036                 return keyctl_set_reqkey_keyring(arg2);
1037
1038         default:
1039                 return -EOPNOTSUPP;
1040         }
1041
1042 } /* end sys_keyctl() */