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/err.h>
  21 #include <asm/uaccess.h>
  22 #include "internal.h"
  23
  24 /*****************************************************************************/
  25 /*
  26  * extract the description of a new key from userspace and either add it as a
  27  * new key to the specified keyring or update a matching key in that keyring
  28  * - the keyring must be writable
  29  * - returns the new key's serial number
  30  * - implements add_key()
  31  */
  32 asmlinkage long sys_add_key(const char __user *_type,
  33                             const char __user *_description,
  34                             const void __user *_payload,
  35                             size_t plen,
  36                             key_serial_t ringid)
  37 {
  38         key_ref_t keyring_ref, key_ref;
  39         char type[32], *description;
  40         void *payload;
  41         long dlen, ret;
  42
  43         ret = -EINVAL;
  44         if (plen > 32767)
  45                 goto error;
  46
  47         /* draw all the data into kernel space */
  48         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
  49         if (ret < 0)
  50                 goto error;
  51         type[31] = '\0';
  52
  53         ret = -EPERM;
  54         if (type[0] == '.')
  55                 goto error;
  56
  57         ret = -EFAULT;
  58         dlen = strnlen_user(_description, PAGE_SIZE - 1);
  59         if (dlen <= 0)
  60                 goto error;
  61
  62         ret = -EINVAL;
  63         if (dlen > PAGE_SIZE - 1)
  64                 goto error;
  65
  66         ret = -ENOMEM;
  67         description = kmalloc(dlen + 1, GFP_KERNEL);
  68         if (!description)
  69                 goto error;
  70         description[dlen] = '\0';
  71
  72         ret = -EFAULT;
  73         if (copy_from_user(description, _description, dlen) != 0)
  74                 goto error2;
  75
  76         /* pull the payload in if one was supplied */
  77         payload = NULL;
  78
  79         if (_payload) {
  80                 ret = -ENOMEM;
  81                 payload = kmalloc(plen, GFP_KERNEL);
  82                 if (!payload)
  83                         goto error2;
  84
  85                 ret = -EFAULT;
  86                 if (copy_from_user(payload, _payload, plen) != 0)
  87                         goto error3;
  88         }
  89
  90         /* find the target keyring (which must be writable) */
  91         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
  92         if (IS_ERR(keyring_ref)) {
  93                 ret = PTR_ERR(keyring_ref);
  94                 goto error3;
  95         }
  96
  97         /* create or update the requested key and add it to the target
  98          * keyring */
  99         key_ref = key_create_or_update(keyring_ref, type, description,
 100                                        payload, plen, 0);
 101         if (!IS_ERR(key_ref)) {
 102                 ret = key_ref_to_ptr(key_ref)->serial;
 103                 key_ref_put(key_ref);
 104         }
 105         else {
 106                 ret = PTR_ERR(key_ref);
 107         }
 108
 109         key_ref_put(keyring_ref);
 110  error3:
 111         kfree(payload);
 112  error2:
 113         kfree(description);
 114  error:
 115         return ret;
 116
 117 } /* end sys_add_key() */
 118
 119 /*****************************************************************************/
 120 /*
 121  * search the process keyrings for a matching key
 122  * - nested keyrings may also be searched if they have Search permission
 123  * - if a key is found, it will be attached to the destination keyring if
 124  *   there's one specified
 125  * - /sbin/request-key will be invoked if _callout_info is non-NULL
 126  *   - the _callout_info string will be passed to /sbin/request-key
 127  *   - if the _callout_info string is empty, it will be rendered as "-"
 128  * - implements request_key()
 129  */
 130 asmlinkage long sys_request_key(const char __user *_type,
 131                                 const char __user *_description,
 132                                 const char __user *_callout_info,
 133                                 key_serial_t destringid)
 134 {
 135         struct key_type *ktype;
 136         struct key *key;
 137         key_ref_t dest_ref;
 138         char type[32], *description, *callout_info;
 139         long dlen, ret;
 140
 141         /* pull the type into kernel space */
 142         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
 143         if (ret < 0)
 144                 goto error;
 145         type[31] = '\0';
 146
 147         ret = -EPERM;
 148         if (type[0] == '.')
 149                 goto error;
 150
 151         /* pull the description into kernel space */
 152         ret = -EFAULT;
 153         dlen = strnlen_user(_description, PAGE_SIZE - 1);
 154         if (dlen <= 0)
 155                 goto error;
 156
 157         ret = -EINVAL;
 158         if (dlen > PAGE_SIZE - 1)
 159                 goto error;
 160
 161         ret = -ENOMEM;
 162         description = kmalloc(dlen + 1, GFP_KERNEL);
 163         if (!description)
 164                 goto error;
 165         description[dlen] = '\0';
 166
 167         ret = -EFAULT;
 168         if (copy_from_user(description, _description, dlen) != 0)
 169                 goto error2;
 170
 171         /* pull the callout info into kernel space */
 172         callout_info = NULL;
 173         if (_callout_info) {
 174                 ret = -EFAULT;
 175                 dlen = strnlen_user(_callout_info, PAGE_SIZE - 1);
 176                 if (dlen <= 0)
 177                         goto error2;
 178
 179                 ret = -EINVAL;
 180                 if (dlen > PAGE_SIZE - 1)
 181                         goto error2;
 182
 183                 ret = -ENOMEM;
 184                 callout_info = kmalloc(dlen + 1, GFP_KERNEL);
 185                 if (!callout_info)
 186                         goto error2;
 187                 callout_info[dlen] = '\0';
 188
 189                 ret = -EFAULT;
 190                 if (copy_from_user(callout_info, _callout_info, dlen) != 0)
 191                         goto error3;
 192         }
 193
 194         /* get the destination keyring if specified */
 195         dest_ref = NULL;
 196         if (destringid) {
 197                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 198                 if (IS_ERR(dest_ref)) {
 199                         ret = PTR_ERR(dest_ref);
 200                         goto error3;
 201                 }
 202         }
 203
 204         /* find the key type */
 205         ktype = key_type_lookup(type);
 206         if (IS_ERR(ktype)) {
 207                 ret = PTR_ERR(ktype);
 208                 goto error4;
 209         }
 210
 211         /* do the search */
 212         key = request_key_and_link(ktype, description, callout_info,
 213                                    key_ref_to_ptr(dest_ref));
 214         if (IS_ERR(key)) {
 215                 ret = PTR_ERR(key);
 216                 goto error5;
 217         }
 218
 219         ret = key->serial;
 220
 221         key_put(key);
 222  error5:
 223         key_type_put(ktype);
 224  error4:
 225         key_ref_put(dest_ref);
 226  error3:
 227         kfree(callout_info);
 228  error2:
 229         kfree(description);
 230  error:
 231         return ret;
 232
 233 } /* end sys_request_key() */
 234
 235 /*****************************************************************************/
 236 /*
 237  * get the ID of the specified process keyring
 238  * - the keyring must have search permission to be found
 239  * - implements keyctl(KEYCTL_GET_KEYRING_ID)
 240  */
 241 long keyctl_get_keyring_ID(key_serial_t id, int create)
 242 {
 243         key_ref_t key_ref;
 244         long ret;
 245
 246         key_ref = lookup_user_key(NULL, id, create, 0, KEY_SEARCH);
 247         if (IS_ERR(key_ref)) {
 248                 ret = PTR_ERR(key_ref);
 249                 goto error;
 250         }
 251
 252         ret = key_ref_to_ptr(key_ref)->serial;
 253         key_ref_put(key_ref);
 254  error:
 255         return ret;
 256
 257 } /* end keyctl_get_keyring_ID() */
 258
 259 /*****************************************************************************/
 260 /*
 261  * join the session keyring
 262  * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
 263  */
 264 long keyctl_join_session_keyring(const char __user *_name)
 265 {
 266         char *name;
 267         long nlen, ret;
 268
 269         /* fetch the name from userspace */
 270         name = NULL;
 271         if (_name) {
 272                 ret = -EFAULT;
 273                 nlen = strnlen_user(_name, PAGE_SIZE - 1);
 274                 if (nlen <= 0)
 275                         goto error;
 276
 277                 ret = -EINVAL;
 278                 if (nlen > PAGE_SIZE - 1)
 279                         goto error;
 280
 281                 ret = -ENOMEM;
 282                 name = kmalloc(nlen + 1, GFP_KERNEL);
 283                 if (!name)
 284                         goto error;
 285                 name[nlen] = '\0';
 286
 287                 ret = -EFAULT;
 288                 if (copy_from_user(name, _name, nlen) != 0)
 289                         goto error2;
 290         }
 291
 292         /* join the session */
 293         ret = join_session_keyring(name);
 294
 295  error2:
 296         kfree(name);
 297  error:
 298         return ret;
 299
 300 } /* end keyctl_join_session_keyring() */
 301
 302 /*****************************************************************************/
 303 /*
 304  * update a key's data payload
 305  * - the key must be writable
 306  * - implements keyctl(KEYCTL_UPDATE)
 307  */
 308 long keyctl_update_key(key_serial_t id,
 309                        const void __user *_payload,
 310                        size_t plen)
 311 {
 312         key_ref_t key_ref;
 313         void *payload;
 314         long ret;
 315
 316         ret = -EINVAL;
 317         if (plen > PAGE_SIZE)
 318                 goto error;
 319
 320         /* pull the payload in if one was supplied */
 321         payload = NULL;
 322         if (_payload) {
 323                 ret = -ENOMEM;
 324                 payload = kmalloc(plen, GFP_KERNEL);
 325                 if (!payload)
 326                         goto error;
 327
 328                 ret = -EFAULT;
 329                 if (copy_from_user(payload, _payload, plen) != 0)
 330                         goto error2;
 331         }
 332
 333         /* find the target key (which must be writable) */
 334         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 335         if (IS_ERR(key_ref)) {
 336                 ret = PTR_ERR(key_ref);
 337                 goto error2;
 338         }
 339
 340         /* update the key */
 341         ret = key_update(key_ref, payload, plen);
 342
 343         key_ref_put(key_ref);
 344  error2:
 345         kfree(payload);
 346  error:
 347         return ret;
 348
 349 } /* end keyctl_update_key() */
 350
 351 /*****************************************************************************/
 352 /*
 353  * revoke a key
 354  * - the key must be writable
 355  * - implements keyctl(KEYCTL_REVOKE)
 356  */
 357 long keyctl_revoke_key(key_serial_t id)
 358 {
 359         key_ref_t key_ref;
 360         long ret;
 361
 362         key_ref = lookup_user_key(NULL, id, 0, 0, KEY_WRITE);
 363         if (IS_ERR(key_ref)) {
 364                 ret = PTR_ERR(key_ref);
 365                 goto error;
 366         }
 367
 368         key_revoke(key_ref_to_ptr(key_ref));
 369         ret = 0;
 370
 371         key_ref_put(key_ref);
 372  error:
 373         return ret;
 374
 375 } /* end keyctl_revoke_key() */
 376
 377 /*****************************************************************************/
 378 /*
 379  * clear the specified process keyring
 380  * - the keyring must be writable
 381  * - implements keyctl(KEYCTL_CLEAR)
 382  */
 383 long keyctl_keyring_clear(key_serial_t ringid)
 384 {
 385         key_ref_t keyring_ref;
 386         long ret;
 387
 388         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 389         if (IS_ERR(keyring_ref)) {
 390                 ret = PTR_ERR(keyring_ref);
 391                 goto error;
 392         }
 393
 394         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 395
 396         key_ref_put(keyring_ref);
 397  error:
 398         return ret;
 399
 400 } /* end keyctl_keyring_clear() */
 401
 402 /*****************************************************************************/
 403 /*
 404  * link a key into a keyring
 405  * - the keyring must be writable
 406  * - the key must be linkable
 407  * - implements keyctl(KEYCTL_LINK)
 408  */
 409 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 410 {
 411         key_ref_t keyring_ref, key_ref;
 412         long ret;
 413
 414         keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 415         if (IS_ERR(keyring_ref)) {
 416                 ret = PTR_ERR(keyring_ref);
 417                 goto error;
 418         }
 419
 420         key_ref = lookup_user_key(NULL, id, 1, 0, KEY_LINK);
 421         if (IS_ERR(key_ref)) {
 422                 ret = PTR_ERR(key_ref);
 423                 goto error2;
 424         }
 425
 426         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 427
 428         key_ref_put(key_ref);
 429  error2:
 430         key_ref_put(keyring_ref);
 431  error:
 432         return ret;
 433
 434 } /* end keyctl_keyring_link() */
 435
 436 /*****************************************************************************/
 437 /*
 438  * unlink the first attachment of a key from a keyring
 439  * - the keyring must be writable
 440  * - we don't need any permissions on the key
 441  * - implements keyctl(KEYCTL_UNLINK)
 442  */
 443 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 444 {
 445         key_ref_t keyring_ref, key_ref;
 446         long ret;
 447
 448         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_WRITE);
 449         if (IS_ERR(keyring_ref)) {
 450                 ret = PTR_ERR(keyring_ref);
 451                 goto error;
 452         }
 453
 454         key_ref = lookup_user_key(NULL, id, 0, 0, 0);
 455         if (IS_ERR(key_ref)) {
 456                 ret = PTR_ERR(key_ref);
 457                 goto error2;
 458         }
 459
 460         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 461
 462         key_ref_put(key_ref);
 463  error2:
 464         key_ref_put(keyring_ref);
 465  error:
 466         return ret;
 467
 468 } /* end keyctl_keyring_unlink() */
 469
 470 /*****************************************************************************/
 471 /*
 472  * describe a user key
 473  * - the key must have view permission
 474  * - if there's a buffer, we place up to buflen bytes of data into it
 475  * - unless there's an error, we return the amount of description available,
 476  *   irrespective of how much we may have copied
 477  * - the description is formatted thus:
 478  *      type;uid;gid;perm;description<NUL>
 479  * - implements keyctl(KEYCTL_DESCRIBE)
 480  */
 481 long keyctl_describe_key(key_serial_t keyid,
 482                          char __user *buffer,
 483                          size_t buflen)
 484 {
 485         struct key *key, *instkey;
 486         key_ref_t key_ref;
 487         char *tmpbuf;
 488         long ret;
 489
 490         key_ref = lookup_user_key(NULL, keyid, 0, 1, KEY_VIEW);
 491         if (IS_ERR(key_ref)) {
 492                 /* viewing a key under construction is permitted if we have the
 493                  * authorisation token handy */
 494                 if (PTR_ERR(key_ref) == -EACCES) {
 495                         instkey = key_get_instantiation_authkey(keyid);
 496                         if (!IS_ERR(instkey)) {
 497                                 key_put(instkey);
 498                                 key_ref = lookup_user_key(NULL, keyid,
 499                                                           0, 1, 0);
 500                                 if (!IS_ERR(key_ref))
 501                                         goto okay;
 502                         }
 503                 }
 504
 505                 ret = PTR_ERR(key_ref);
 506                 goto error;
 507         }
 508
 509 okay:
 510         /* calculate how much description we're going to return */
 511         ret = -ENOMEM;
 512         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 513         if (!tmpbuf)
 514                 goto error2;
 515
 516         key = key_ref_to_ptr(key_ref);
 517
 518         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 519                        "%s;%d;%d;%08x;%s",
 520                        key_ref_to_ptr(key_ref)->type->name,
 521                        key_ref_to_ptr(key_ref)->uid,
 522                        key_ref_to_ptr(key_ref)->gid,
 523                        key_ref_to_ptr(key_ref)->perm,
 524                        key_ref_to_ptr(key_ref)->description ?
 525                        key_ref_to_ptr(key_ref)->description : ""
 526                        );
 527
 528         /* include a NUL char at the end of the data */
 529         if (ret > PAGE_SIZE - 1)
 530                 ret = PAGE_SIZE - 1;
 531         tmpbuf[ret] = 0;
 532         ret++;
 533
 534         /* consider returning the data */
 535         if (buffer && buflen > 0) {
 536                 if (buflen > ret)
 537                         buflen = ret;
 538
 539                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 540                         ret = -EFAULT;
 541         }
 542
 543         kfree(tmpbuf);
 544  error2:
 545         key_ref_put(key_ref);
 546  error:
 547         return ret;
 548
 549 } /* end keyctl_describe_key() */
 550
 551 /*****************************************************************************/
 552 /*
 553  * search the specified keyring for a matching key
 554  * - the start keyring must be searchable
 555  * - nested keyrings may also be searched if they are searchable
 556  * - only keys with search permission may be found
 557  * - if a key is found, it will be attached to the destination keyring if
 558  *   there's one specified
 559  * - implements keyctl(KEYCTL_SEARCH)
 560  */
 561 long keyctl_keyring_search(key_serial_t ringid,
 562                            const char __user *_type,
 563                            const char __user *_description,
 564                            key_serial_t destringid)
 565 {
 566         struct key_type *ktype;
 567         key_ref_t keyring_ref, key_ref, dest_ref;
 568         char type[32], *description;
 569         long dlen, ret;
 570
 571         /* pull the type and description into kernel space */
 572         ret = strncpy_from_user(type, _type, sizeof(type) - 1);
 573         if (ret < 0)
 574                 goto error;
 575         type[31] = '\0';
 576
 577         ret = -EFAULT;
 578         dlen = strnlen_user(_description, PAGE_SIZE - 1);
 579         if (dlen <= 0)
 580                 goto error;
 581
 582         ret = -EINVAL;
 583         if (dlen > PAGE_SIZE - 1)
 584                 goto error;
 585
 586         ret = -ENOMEM;
 587         description = kmalloc(dlen + 1, GFP_KERNEL);
 588         if (!description)
 589                 goto error;
 590         description[dlen] = '\0';
 591
 592         ret = -EFAULT;
 593         if (copy_from_user(description, _description, dlen) != 0)
 594                 goto error2;
 595
 596         /* get the keyring at which to begin the search */
 597         keyring_ref = lookup_user_key(NULL, ringid, 0, 0, KEY_SEARCH);
 598         if (IS_ERR(keyring_ref)) {
 599                 ret = PTR_ERR(keyring_ref);
 600                 goto error2;
 601         }
 602
 603         /* get the destination keyring if specified */
 604         dest_ref = NULL;
 605         if (destringid) {
 606                 dest_ref = lookup_user_key(NULL, destringid, 1, 0, KEY_WRITE);
 607                 if (IS_ERR(dest_ref)) {
 608                         ret = PTR_ERR(dest_ref);
 609                         goto error3;
 610                 }
 611         }
 612
 613         /* find the key type */
 614         ktype = key_type_lookup(type);
 615         if (IS_ERR(ktype)) {
 616                 ret = PTR_ERR(ktype);
 617                 goto error4;
 618         }
 619
 620         /* do the search */
 621         key_ref = keyring_search(keyring_ref, ktype, description);
 622         if (IS_ERR(key_ref)) {
 623                 ret = PTR_ERR(key_ref);
 624
 625                 /* treat lack or presence of a negative key the same */
 626                 if (ret == -EAGAIN)
 627                         ret = -ENOKEY;
 628                 goto error5;
 629         }
 630
 631         /* link the resulting key to the destination keyring if we can */
 632         if (dest_ref) {
 633                 ret = key_permission(key_ref, KEY_LINK);
 634                 if (ret < 0)
 635                         goto error6;
 636
 637                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 638                 if (ret < 0)
 639                         goto error6;
 640         }
 641
 642         ret = key_ref_to_ptr(key_ref)->serial;
 643
 644  error6:
 645         key_ref_put(key_ref);
 646  error5:
 647         key_type_put(ktype);
 648  error4:
 649         key_ref_put(dest_ref);
 650  error3:
 651         key_ref_put(keyring_ref);
 652  error2:
 653         kfree(description);
 654  error:
 655         return ret;
 656
 657 } /* end keyctl_keyring_search() */
 658
 659 /*****************************************************************************/
 660 /*
 661  * read a user key's payload
 662  * - the keyring must be readable or the key must be searchable from the
 663  *   process's keyrings
 664  * - if there's a buffer, we place up to buflen bytes of data into it
 665  * - unless there's an error, we return the amount of data in the key,
 666  *   irrespective of how much we may have copied
 667  * - implements keyctl(KEYCTL_READ)
 668  */
 669 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 670 {
 671         struct key *key;
 672         key_ref_t key_ref;
 673         long ret;
 674
 675         /* find the key first */
 676         key_ref = lookup_user_key(NULL, keyid, 0, 0, 0);
 677         if (IS_ERR(key_ref)) {
 678                 ret = -ENOKEY;
 679                 goto error;
 680         }
 681
 682         key = key_ref_to_ptr(key_ref);
 683
 684         /* see if we can read it directly */
 685         ret = key_permission(key_ref, KEY_READ);
 686         if (ret == 0)
 687                 goto can_read_key;
 688         if (ret != -EACCES)
 689                 goto error;
 690
 691         /* we can't; see if it's searchable from this process's keyrings
 692          * - we automatically take account of the fact that it may be
 693          *   dangling off an instantiation key
 694          */
 695         if (!is_key_possessed(key_ref)) {
 696                 ret = -EACCES;
 697                 goto error2;
 698         }
 699
 700         /* the key is probably readable - now try to read it */
 701  can_read_key:
 702         ret = key_validate(key);
 703         if (ret == 0) {
 704                 ret = -EOPNOTSUPP;
 705                 if (key->type->read) {
 706                         /* read the data with the semaphore held (since we
 707                          * might sleep) */
 708                         down_read(&key->sem);
 709                         ret = key->type->read(key, buffer, buflen);
 710                         up_read(&key->sem);
 711                 }
 712         }
 713
 714  error2:
 715         key_put(key);
 716  error:
 717         return ret;
 718
 719 } /* end keyctl_read_key() */
 720
 721 /*****************************************************************************/
 722 /*
 723  * change the ownership of a key
 724  * - the keyring owned by the changer
 725  * - if the uid or gid is -1, then that parameter is not changed
 726  * - implements keyctl(KEYCTL_CHOWN)
 727  */
 728 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 729 {
 730         struct key *key;
 731         key_ref_t key_ref;
 732         long ret;
 733
 734         ret = 0;
 735         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 736                 goto error;
 737
 738         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 739         if (IS_ERR(key_ref)) {
 740                 ret = PTR_ERR(key_ref);
 741                 goto error;
 742         }
 743
 744         key = key_ref_to_ptr(key_ref);
 745
 746         /* make the changes with the locks held to prevent chown/chown races */
 747         ret = -EACCES;
 748         down_write(&key->sem);
 749
 750         if (!capable(CAP_SYS_ADMIN)) {
 751                 /* only the sysadmin can chown a key to some other UID */
 752                 if (uid != (uid_t) -1 && key->uid != uid)
 753                         goto no_access;
 754
 755                 /* only the sysadmin can set the key's GID to a group other
 756                  * than one of those that the current process subscribes to */
 757                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 758                         goto no_access;
 759         }
 760
 761         /* change the UID (have to update the quotas) */
 762         if (uid != (uid_t) -1 && uid != key->uid) {
 763                 /* don't support UID changing yet */
 764                 ret = -EOPNOTSUPP;
 765                 goto no_access;
 766         }
 767
 768         /* change the GID */
 769         if (gid != (gid_t) -1)
 770                 key->gid = gid;
 771
 772         ret = 0;
 773
 774  no_access:
 775         up_write(&key->sem);
 776         key_put(key);
 777  error:
 778         return ret;
 779
 780 } /* end keyctl_chown_key() */
 781
 782 /*****************************************************************************/
 783 /*
 784  * change the permission mask on a key
 785  * - the keyring owned by the changer
 786  * - implements keyctl(KEYCTL_SETPERM)
 787  */
 788 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 789 {
 790         struct key *key;
 791         key_ref_t key_ref;
 792         long ret;
 793
 794         ret = -EINVAL;
 795         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 796                 goto error;
 797
 798         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
 799         if (IS_ERR(key_ref)) {
 800                 ret = PTR_ERR(key_ref);
 801                 goto error;
 802         }
 803
 804         key = key_ref_to_ptr(key_ref);
 805
 806         /* make the changes with the locks held to prevent chown/chmod races */
 807         ret = -EACCES;
 808         down_write(&key->sem);
 809
 810         /* if we're not the sysadmin, we can only change a key that we own */
 811         if (capable(CAP_SYS_ADMIN) || key->uid == current->fsuid) {
 812                 key->perm = perm;
 813                 ret = 0;
 814         }
 815
 816         up_write(&key->sem);
 817         key_put(key);
 818 error:
 819         return ret;
 820
 821 } /* end keyctl_setperm_key() */
 822
 823 /*****************************************************************************/
 824 /*
 825  * instantiate the key with the specified payload, and, if one is given, link
 826  * the key into the keyring
 827  */
 828 long keyctl_instantiate_key(key_serial_t id,
 829                             const void __user *_payload,
 830                             size_t plen,
 831                             key_serial_t ringid)
 832 {
 833         struct request_key_auth *rka;
 834         struct key *instkey;
 835         key_ref_t keyring_ref;
 836         void *payload;
 837         long ret;
 838
 839         ret = -EINVAL;
 840         if (plen > 32767)
 841                 goto error;
 842
 843         /* the appropriate instantiation authorisation key must have been
 844          * assumed before calling this */
 845         ret = -EPERM;
 846         instkey = current->request_key_auth;
 847         if (!instkey)
 848                 goto error;
 849
 850         rka = instkey->payload.data;
 851         if (rka->target_key->serial != id)
 852                 goto error;
 853
 854         /* pull the payload in if one was supplied */
 855         payload = NULL;
 856
 857         if (_payload) {
 858                 ret = -ENOMEM;
 859                 payload = kmalloc(plen, GFP_KERNEL);
 860                 if (!payload)
 861                         goto error;
 862
 863                 ret = -EFAULT;
 864                 if (copy_from_user(payload, _payload, plen) != 0)
 865                         goto error2;
 866         }
 867
 868         /* find the destination keyring amongst those belonging to the
 869          * requesting task */
 870         keyring_ref = NULL;
 871         if (ringid) {
 872                 keyring_ref = lookup_user_key(rka->context, ringid, 1, 0,
 873                                               KEY_WRITE);
 874                 if (IS_ERR(keyring_ref)) {
 875                         ret = PTR_ERR(keyring_ref);
 876                         goto error2;
 877                 }
 878         }
 879
 880         /* instantiate the key and link it into a keyring */
 881         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 882                                        key_ref_to_ptr(keyring_ref), instkey);
 883
 884         key_ref_put(keyring_ref);
 885
 886         /* discard the assumed authority if it's just been disabled by
 887          * instantiation of the key */
 888         if (ret == 0) {
 889                 key_put(current->request_key_auth);
 890                 current->request_key_auth = NULL;
 891         }
 892
 893 error2:
 894         kfree(payload);
 895 error:
 896         return ret;
 897
 898 } /* end keyctl_instantiate_key() */
 899
 900 /*****************************************************************************/
 901 /*
 902  * negatively instantiate the key with the given timeout (in seconds), and, if
 903  * one is given, link the key into the keyring
 904  */
 905 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 906 {
 907         struct request_key_auth *rka;
 908         struct key *instkey;
 909         key_ref_t keyring_ref;
 910         long ret;
 911
 912         /* the appropriate instantiation authorisation key must have been
 913          * assumed before calling this */
 914         ret = -EPERM;
 915         instkey = current->request_key_auth;
 916         if (!instkey)
 917                 goto error;
 918
 919         rka = instkey->payload.data;
 920         if (rka->target_key->serial != id)
 921                 goto error;
 922
 923         /* find the destination keyring if present (which must also be
 924          * writable) */
 925         keyring_ref = NULL;
 926         if (ringid) {
 927                 keyring_ref = lookup_user_key(NULL, ringid, 1, 0, KEY_WRITE);
 928                 if (IS_ERR(keyring_ref)) {
 929                         ret = PTR_ERR(keyring_ref);
 930                         goto error;
 931                 }
 932         }
 933
 934         /* instantiate the key and link it into a keyring */
 935         ret = key_negate_and_link(rka->target_key, timeout,
 936                                   key_ref_to_ptr(keyring_ref), instkey);
 937
 938         key_ref_put(keyring_ref);
 939
 940         /* discard the assumed authority if it's just been disabled by
 941          * instantiation of the key */
 942         if (ret == 0) {
 943                 key_put(current->request_key_auth);
 944                 current->request_key_auth = NULL;
 945         }
 946
 947 error:
 948         return ret;
 949
 950 } /* end keyctl_negate_key() */
 951
 952 /*****************************************************************************/
 953 /*
 954  * set the default keyring in which request_key() will cache keys
 955  * - return the old setting
 956  */
 957 long keyctl_set_reqkey_keyring(int reqkey_defl)
 958 {
 959         int ret;
 960
 961         switch (reqkey_defl) {
 962         case KEY_REQKEY_DEFL_THREAD_KEYRING:
 963                 ret = install_thread_keyring(current);
 964                 if (ret < 0)
 965                         return ret;
 966                 goto set;
 967
 968         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
 969                 ret = install_process_keyring(current);
 970                 if (ret < 0)
 971                         return ret;
 972
 973         case KEY_REQKEY_DEFL_DEFAULT:
 974         case KEY_REQKEY_DEFL_SESSION_KEYRING:
 975         case KEY_REQKEY_DEFL_USER_KEYRING:
 976         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
 977         set:
 978                 current->jit_keyring = reqkey_defl;
 979
 980         case KEY_REQKEY_DEFL_NO_CHANGE:
 981                 return current->jit_keyring;
 982
 983         case KEY_REQKEY_DEFL_GROUP_KEYRING:
 984         default:
 985                 return -EINVAL;
 986         }
 987
 988 } /* end keyctl_set_reqkey_keyring() */
 989
 990 /*****************************************************************************/
 991 /*
 992  * set or clear the timeout for a key
 993  */
 994 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
 995 {
 996         struct timespec now;
 997         struct key *key;
 998         key_ref_t key_ref;
 999         time_t expiry;
1000         long ret;
1001
1002         key_ref = lookup_user_key(NULL, id, 1, 1, KEY_SETATTR);
1003         if (IS_ERR(key_ref)) {
1004                 ret = PTR_ERR(key_ref);
1005                 goto error;
1006         }
1007
1008         key = key_ref_to_ptr(key_ref);
1009
1010         /* make the changes with the locks held to prevent races */
1011         down_write(&key->sem);
1012
1013         expiry = 0;
1014         if (timeout > 0) {
1015                 now = current_kernel_time();
1016                 expiry = now.tv_sec + timeout;
1017         }
1018
1019         key->expiry = expiry;
1020
1021         up_write(&key->sem);
1022         key_put(key);
1023
1024         ret = 0;
1025 error:
1026         return ret;
1027
1028 } /* end keyctl_set_timeout() */
1029
1030 /*****************************************************************************/
1031 /*
1032  * assume the authority to instantiate the specified key
1033  */
1034 long keyctl_assume_authority(key_serial_t id)
1035 {
1036         struct key *authkey;
1037         long ret;
1038
1039         /* special key IDs aren't permitted */
1040         ret = -EINVAL;
1041         if (id < 0)
1042                 goto error;
1043
1044         /* we divest ourselves of authority if given an ID of 0 */
1045         if (id == 0) {
1046                 key_put(current->request_key_auth);
1047                 current->request_key_auth = NULL;
1048                 ret = 0;
1049                 goto error;
1050         }
1051
1052         /* attempt to assume the authority temporarily granted to us whilst we
1053          * instantiate the specified key
1054          * - the authorisation key must be in the current task's keyrings
1055          *   somewhere
1056          */
1057         authkey = key_get_instantiation_authkey(id);
1058         if (IS_ERR(authkey)) {
1059                 ret = PTR_ERR(authkey);
1060                 goto error;
1061         }
1062
1063         key_put(current->request_key_auth);
1064         current->request_key_auth = authkey;
1065         ret = authkey->serial;
1066
1067 error:
1068         return ret;
1069
1070 } /* end keyctl_assume_authority() */
1071
1072 /*****************************************************************************/
1073 /*
1074  * the key control system call
1075  */
1076 asmlinkage long sys_keyctl(int option, unsigned long arg2, unsigned long arg3,
1077                            unsigned long arg4, unsigned long arg5)
1078 {
1079         switch (option) {
1080         case KEYCTL_GET_KEYRING_ID:
1081                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1082                                              (int) arg3);
1083
1084         case KEYCTL_JOIN_SESSION_KEYRING:
1085                 return keyctl_join_session_keyring((const char __user *) arg2);
1086
1087         case KEYCTL_UPDATE:
1088                 return keyctl_update_key((key_serial_t) arg2,
1089                                          (const void __user *) arg3,
1090                                          (size_t) arg4);
1091
1092         case KEYCTL_REVOKE:
1093                 return keyctl_revoke_key((key_serial_t) arg2);
1094
1095         case KEYCTL_DESCRIBE:
1096                 return keyctl_describe_key((key_serial_t) arg2,
1097                                            (char __user *) arg3,
1098                                            (unsigned) arg4);
1099
1100         case KEYCTL_CLEAR:
1101                 return keyctl_keyring_clear((key_serial_t) arg2);
1102
1103         case KEYCTL_LINK:
1104                 return keyctl_keyring_link((key_serial_t) arg2,
1105                                            (key_serial_t) arg3);
1106
1107         case KEYCTL_UNLINK:
1108                 return keyctl_keyring_unlink((key_serial_t) arg2,
1109                                              (key_serial_t) arg3);
1110
1111         case KEYCTL_SEARCH:
1112                 return keyctl_keyring_search((key_serial_t) arg2,
1113                                              (const char __user *) arg3,
1114                                              (const char __user *) arg4,
1115                                              (key_serial_t) arg5);
1116
1117         case KEYCTL_READ:
1118                 return keyctl_read_key((key_serial_t) arg2,
1119                                        (char __user *) arg3,
1120                                        (size_t) arg4);
1121
1122         case KEYCTL_CHOWN:
1123                 return keyctl_chown_key((key_serial_t) arg2,
1124                                         (uid_t) arg3,
1125                                         (gid_t) arg4);
1126
1127         case KEYCTL_SETPERM:
1128                 return keyctl_setperm_key((key_serial_t) arg2,
1129                                           (key_perm_t) arg3);
1130
1131         case KEYCTL_INSTANTIATE:
1132                 return keyctl_instantiate_key((key_serial_t) arg2,
1133                                               (const void __user *) arg3,
1134                                               (size_t) arg4,
1135                                               (key_serial_t) arg5);
1136
1137         case KEYCTL_NEGATE:
1138                 return keyctl_negate_key((key_serial_t) arg2,
1139                                          (unsigned) arg3,
1140                                          (key_serial_t) arg4);
1141
1142         case KEYCTL_SET_REQKEY_KEYRING:
1143                 return keyctl_set_reqkey_keyring(arg2);
1144
1145         case KEYCTL_SET_TIMEOUT:
1146                 return keyctl_set_timeout((key_serial_t) arg2,
1147                                           (unsigned) arg3);
1148
1149         case KEYCTL_ASSUME_AUTHORITY:
1150                 return keyctl_assume_authority((key_serial_t) arg2);
1151
1152         default:
1153                 return -EOPNOTSUPP;
1154         }
1155
1156 } /* end sys_keyctl() */