security/keys/keyctl.c

   1 /* keyctl.c: userspace keyctl operations
   2  *
   3  * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/keyctl.h>
  18 #include <linux/fs.h>
  19 #include <linux/capability.h>
  20 #include <linux/string.h>
  21 #include <linux/err.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/security.h>
  24 #include <asm/uaccess.h>
  25 #include "internal.h"
  26
  27 static int key_get_type_from_user(char *type,
  28                                   const char __user *_type,
  29                                   unsigned len)
  30 {
  31         int ret;
  32
  33         ret = strncpy_from_user(type, _type, len);
  34
  35         if (ret < 0)
  36                 return -EFAULT;
  37
  38         if (ret == 0 || ret >= len)
  39                 return -EINVAL;
  40
  41         if (type[0] == '.')
  42                 return -EPERM;
  43
  44         type[len - 1] = '\0';
  45
  46         return 0;
  47 }
  48
  49 /*****************************************************************************/
  50 /*
  51  * extract the description of a new key from userspace and either add it as a
  52  * new key to the specified keyring or update a matching key in that keyring
  53  * - the keyring must be writable
  54  * - returns the new key's serial number
  55  * - implements add_key()
  56  */
  57 SYSCALL_DEFINE5(add_key, const char __user *, _type,
  58                 const char __user *, _description,
  59                 const void __user *, _payload,
  60                 size_t, plen,
  61                 key_serial_t, ringid)
  62 {
  63         key_ref_t keyring_ref, key_ref;
  64         char type[32], *description;
  65         void *payload;
  66         long ret;
  67         bool vm;
  68
  69         ret = -EINVAL;
  70         if (plen > 1024 * 1024 - 1)
  71                 goto error;
  72
  73         /* draw all the data into kernel space */
  74         ret = key_get_type_from_user(type, _type, sizeof(type));
  75         if (ret < 0)
  76                 goto error;
  77
  78         description = strndup_user(_description, PAGE_SIZE);
  79         if (IS_ERR(description)) {
  80                 ret = PTR_ERR(description);
  81                 goto error;
  82         }
  83
  84         /* pull the payload in if one was supplied */
  85         payload = NULL;
  86
  87         vm = false;
  88         if (_payload) {
  89                 ret = -ENOMEM;
  90                 payload = kmalloc(plen, GFP_KERNEL);
  91                 if (!payload) {
  92                         if (plen <= PAGE_SIZE)
  93                                 goto error2;
  94                         vm = true;
  95                         payload = vmalloc(plen);
  96                         if (!payload)
  97                                 goto error2;
  98                 }
  99
 100                 ret = -EFAULT;
 101                 if (copy_from_user(payload, _payload, plen) != 0)
 102                         goto error3;
 103         }
 104
 105         /* find the target keyring (which must be writable) */
 106         keyring_ref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
 107         if (IS_ERR(keyring_ref)) {
 108                 ret = PTR_ERR(keyring_ref);
 109                 goto error3;
 110         }
 111
 112         /* create or update the requested key and add it to the target
 113          * keyring */
 114         key_ref = key_create_or_update(keyring_ref, type, description,
 115                                        payload, plen, KEY_PERM_UNDEF,
 116                                        KEY_ALLOC_IN_QUOTA);
 117         if (!IS_ERR(key_ref)) {
 118                 ret = key_ref_to_ptr(key_ref)->serial;
 119                 key_ref_put(key_ref);
 120         }
 121         else {
 122                 ret = PTR_ERR(key_ref);
 123         }
 124
 125         key_ref_put(keyring_ref);
 126  error3:
 127         if (!vm)
 128                 kfree(payload);
 129         else
 130                 vfree(payload);
 131  error2:
 132         kfree(description);
 133  error:
 134         return ret;
 135
 136 } /* end sys_add_key() */
 137
 138 /*****************************************************************************/
 139 /*
 140  * search the process keyrings for a matching key
 141  * - nested keyrings may also be searched if they have Search permission
 142  * - if a key is found, it will be attached to the destination keyring if
 143  *   there's one specified
 144  * - /sbin/request-key will be invoked if _callout_info is non-NULL
 145  *   - the _callout_info string will be passed to /sbin/request-key
 146  *   - if the _callout_info string is empty, it will be rendered as "-"
 147  * - implements request_key()
 148  */
 149 SYSCALL_DEFINE4(request_key, const char __user *, _type,
 150                 const char __user *, _description,
 151                 const char __user *, _callout_info,
 152                 key_serial_t, destringid)
 153 {
 154         struct key_type *ktype;
 155         struct key *key;
 156         key_ref_t dest_ref;
 157         size_t callout_len;
 158         char type[32], *description, *callout_info;
 159         long ret;
 160
 161         /* pull the type into kernel space */
 162         ret = key_get_type_from_user(type, _type, sizeof(type));
 163         if (ret < 0)
 164                 goto error;
 165
 166         /* pull the description into kernel space */
 167         description = strndup_user(_description, PAGE_SIZE);
 168         if (IS_ERR(description)) {
 169                 ret = PTR_ERR(description);
 170                 goto error;
 171         }
 172
 173         /* pull the callout info into kernel space */
 174         callout_info = NULL;
 175         callout_len = 0;
 176         if (_callout_info) {
 177                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
 178                 if (IS_ERR(callout_info)) {
 179                         ret = PTR_ERR(callout_info);
 180                         goto error2;
 181                 }
 182                 callout_len = strlen(callout_info);
 183         }
 184
 185         /* get the destination keyring if specified */
 186         dest_ref = NULL;
 187         if (destringid) {
 188                 dest_ref = lookup_user_key(destringid, 1, 0, KEY_WRITE);
 189                 if (IS_ERR(dest_ref)) {
 190                         ret = PTR_ERR(dest_ref);
 191                         goto error3;
 192                 }
 193         }
 194
 195         /* find the key type */
 196         ktype = key_type_lookup(type);
 197         if (IS_ERR(ktype)) {
 198                 ret = PTR_ERR(ktype);
 199                 goto error4;
 200         }
 201
 202         /* do the search */
 203         key = request_key_and_link(ktype, description, callout_info,
 204                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
 205                                    KEY_ALLOC_IN_QUOTA);
 206         if (IS_ERR(key)) {
 207                 ret = PTR_ERR(key);
 208                 goto error5;
 209         }
 210
 211         ret = key->serial;
 212
 213         key_put(key);
 214  error5:
 215         key_type_put(ktype);
 216  error4:
 217         key_ref_put(dest_ref);
 218  error3:
 219         kfree(callout_info);
 220  error2:
 221         kfree(description);
 222  error:
 223         return ret;
 224
 225 } /* end sys_request_key() */
 226
 227 /*****************************************************************************/
 228 /*
 229  * get the ID of the specified process keyring
 230  * - the keyring must have search permission to be found
 231  * - implements keyctl(KEYCTL_GET_KEYRING_ID)
 232  */
 233 long keyctl_get_keyring_ID(key_serial_t id, int create)
 234 {
 235         key_ref_t key_ref;
 236         long ret;
 237
 238         key_ref = lookup_user_key(id, create, 0, KEY_SEARCH);
 239         if (IS_ERR(key_ref)) {
 240                 ret = PTR_ERR(key_ref);
 241                 goto error;
 242         }
 243
 244         ret = key_ref_to_ptr(key_ref)->serial;
 245         key_ref_put(key_ref);
 246  error:
 247         return ret;
 248
 249 } /* end keyctl_get_keyring_ID() */
 250
 251 /*****************************************************************************/
 252 /*
 253  * join the session keyring
 254  * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
 255  */
 256 long keyctl_join_session_keyring(const char __user *_name)
 257 {
 258         char *name;
 259         long ret;
 260
 261         /* fetch the name from userspace */
 262         name = NULL;
 263         if (_name) {
 264                 name = strndup_user(_name, PAGE_SIZE);
 265                 if (IS_ERR(name)) {
 266                         ret = PTR_ERR(name);
 267                         goto error;
 268                 }
 269         }
 270
 271         /* join the session */
 272         ret = join_session_keyring(name);
 273         kfree(name);
 274
 275  error:
 276         return ret;
 277
 278 } /* end keyctl_join_session_keyring() */
 279
 280 /*****************************************************************************/
 281 /*
 282  * update a key's data payload
 283  * - the key must be writable
 284  * - implements keyctl(KEYCTL_UPDATE)
 285  */
 286 long keyctl_update_key(key_serial_t id,
 287                        const void __user *_payload,
 288                        size_t plen)
 289 {
 290         key_ref_t key_ref;
 291         void *payload;
 292         long ret;
 293
 294         ret = -EINVAL;
 295         if (plen > PAGE_SIZE)
 296                 goto error;
 297
 298         /* pull the payload in if one was supplied */
 299         payload = NULL;
 300         if (_payload) {
 301                 ret = -ENOMEM;
 302                 payload = kmalloc(plen, GFP_KERNEL);
 303                 if (!payload)
 304                         goto error;
 305
 306                 ret = -EFAULT;
 307                 if (copy_from_user(payload, _payload, plen) != 0)
 308                         goto error2;
 309         }
 310
 311         /* find the target key (which must be writable) */
 312         key_ref = lookup_user_key(id, 0, 0, KEY_WRITE);
 313         if (IS_ERR(key_ref)) {
 314                 ret = PTR_ERR(key_ref);
 315                 goto error2;
 316         }
 317
 318         /* update the key */
 319         ret = key_update(key_ref, payload, plen);
 320
 321         key_ref_put(key_ref);
 322  error2:
 323         kfree(payload);
 324  error:
 325         return ret;
 326
 327 } /* end keyctl_update_key() */
 328
 329 /*****************************************************************************/
 330 /*
 331  * revoke a key
 332  * - the key must be writable
 333  * - implements keyctl(KEYCTL_REVOKE)
 334  */
 335 long keyctl_revoke_key(key_serial_t id)
 336 {
 337         key_ref_t key_ref;
 338         long ret;
 339
 340         key_ref = lookup_user_key(id, 0, 0, KEY_WRITE);
 341         if (IS_ERR(key_ref)) {
 342                 ret = PTR_ERR(key_ref);
 343                 goto error;
 344         }
 345
 346         key_revoke(key_ref_to_ptr(key_ref));
 347         ret = 0;
 348
 349         key_ref_put(key_ref);
 350  error:
 351         return ret;
 352
 353 } /* end keyctl_revoke_key() */
 354
 355 /*****************************************************************************/
 356 /*
 357  * clear the specified process keyring
 358  * - the keyring must be writable
 359  * - implements keyctl(KEYCTL_CLEAR)
 360  */
 361 long keyctl_keyring_clear(key_serial_t ringid)
 362 {
 363         key_ref_t keyring_ref;
 364         long ret;
 365
 366         keyring_ref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
 367         if (IS_ERR(keyring_ref)) {
 368                 ret = PTR_ERR(keyring_ref);
 369                 goto error;
 370         }
 371
 372         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 373
 374         key_ref_put(keyring_ref);
 375  error:
 376         return ret;
 377
 378 } /* end keyctl_keyring_clear() */
 379
 380 /*****************************************************************************/
 381 /*
 382  * link a key into a keyring
 383  * - the keyring must be writable
 384  * - the key must be linkable
 385  * - implements keyctl(KEYCTL_LINK)
 386  */
 387 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 388 {
 389         key_ref_t keyring_ref, key_ref;
 390         long ret;
 391
 392         keyring_ref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
 393         if (IS_ERR(keyring_ref)) {
 394                 ret = PTR_ERR(keyring_ref);
 395                 goto error;
 396         }
 397
 398         key_ref = lookup_user_key(id, 1, 0, KEY_LINK);
 399         if (IS_ERR(key_ref)) {
 400                 ret = PTR_ERR(key_ref);
 401                 goto error2;
 402         }
 403
 404         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 405
 406         key_ref_put(key_ref);
 407  error2:
 408         key_ref_put(keyring_ref);
 409  error:
 410         return ret;
 411
 412 } /* end keyctl_keyring_link() */
 413
 414 /*****************************************************************************/
 415 /*
 416  * unlink the first attachment of a key from a keyring
 417  * - the keyring must be writable
 418  * - we don't need any permissions on the key
 419  * - implements keyctl(KEYCTL_UNLINK)
 420  */
 421 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 422 {
 423         key_ref_t keyring_ref, key_ref;
 424         long ret;
 425
 426         keyring_ref = lookup_user_key(ringid, 0, 0, KEY_WRITE);
 427         if (IS_ERR(keyring_ref)) {
 428                 ret = PTR_ERR(keyring_ref);
 429                 goto error;
 430         }
 431
 432         key_ref = lookup_user_key(id, 0, 0, 0);
 433         if (IS_ERR(key_ref)) {
 434                 ret = PTR_ERR(key_ref);
 435                 goto error2;
 436         }
 437
 438         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 439
 440         key_ref_put(key_ref);
 441  error2:
 442         key_ref_put(keyring_ref);
 443  error:
 444         return ret;
 445
 446 } /* end keyctl_keyring_unlink() */
 447
 448 /*****************************************************************************/
 449 /*
 450  * describe a user key
 451  * - the key must have view permission
 452  * - if there's a buffer, we place up to buflen bytes of data into it
 453  * - unless there's an error, we return the amount of description available,
 454  *   irrespective of how much we may have copied
 455  * - the description is formatted thus:
 456  *      type;uid;gid;perm;description<NUL>
 457  * - implements keyctl(KEYCTL_DESCRIBE)
 458  */
 459 long keyctl_describe_key(key_serial_t keyid,
 460                          char __user *buffer,
 461                          size_t buflen)
 462 {
 463         struct key *key, *instkey;
 464         key_ref_t key_ref;
 465         char *tmpbuf;
 466         long ret;
 467
 468         key_ref = lookup_user_key(keyid, 0, 1, KEY_VIEW);
 469         if (IS_ERR(key_ref)) {
 470                 /* viewing a key under construction is permitted if we have the
 471                  * authorisation token handy */
 472                 if (PTR_ERR(key_ref) == -EACCES) {
 473                         instkey = key_get_instantiation_authkey(keyid);
 474                         if (!IS_ERR(instkey)) {
 475                                 key_put(instkey);
 476                                 key_ref = lookup_user_key(keyid,
 477                                                           0, 1, 0);
 478                                 if (!IS_ERR(key_ref))
 479                                         goto okay;
 480                         }
 481                 }
 482
 483                 ret = PTR_ERR(key_ref);
 484                 goto error;
 485         }
 486
 487 okay:
 488         /* calculate how much description we're going to return */
 489         ret = -ENOMEM;
 490         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 491         if (!tmpbuf)
 492                 goto error2;
 493
 494         key = key_ref_to_ptr(key_ref);
 495
 496         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 497                        "%s;%d;%d;%08x;%s",
 498                        key_ref_to_ptr(key_ref)->type->name,
 499                        key_ref_to_ptr(key_ref)->uid,
 500                        key_ref_to_ptr(key_ref)->gid,
 501                        key_ref_to_ptr(key_ref)->perm,
 502                        key_ref_to_ptr(key_ref)->description ?
 503                        key_ref_to_ptr(key_ref)->description : ""
 504                        );
 505
 506         /* include a NUL char at the end of the data */
 507         if (ret > PAGE_SIZE - 1)
 508                 ret = PAGE_SIZE - 1;
 509         tmpbuf[ret] = 0;
 510         ret++;
 511
 512         /* consider returning the data */
 513         if (buffer && buflen > 0) {
 514                 if (buflen > ret)
 515                         buflen = ret;
 516
 517                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 518                         ret = -EFAULT;
 519         }
 520
 521         kfree(tmpbuf);
 522  error2:
 523         key_ref_put(key_ref);
 524  error:
 525         return ret;
 526
 527 } /* end keyctl_describe_key() */
 528
 529 /*****************************************************************************/
 530 /*
 531  * search the specified keyring for a matching key
 532  * - the start keyring must be searchable
 533  * - nested keyrings may also be searched if they are searchable
 534  * - only keys with search permission may be found
 535  * - if a key is found, it will be attached to the destination keyring if
 536  *   there's one specified
 537  * - implements keyctl(KEYCTL_SEARCH)
 538  */
 539 long keyctl_keyring_search(key_serial_t ringid,
 540                            const char __user *_type,
 541                            const char __user *_description,
 542                            key_serial_t destringid)
 543 {
 544         struct key_type *ktype;
 545         key_ref_t keyring_ref, key_ref, dest_ref;
 546         char type[32], *description;
 547         long ret;
 548
 549         /* pull the type and description into kernel space */
 550         ret = key_get_type_from_user(type, _type, sizeof(type));
 551         if (ret < 0)
 552                 goto error;
 553
 554         description = strndup_user(_description, PAGE_SIZE);
 555         if (IS_ERR(description)) {
 556                 ret = PTR_ERR(description);
 557                 goto error;
 558         }
 559
 560         /* get the keyring at which to begin the search */
 561         keyring_ref = lookup_user_key(ringid, 0, 0, KEY_SEARCH);
 562         if (IS_ERR(keyring_ref)) {
 563                 ret = PTR_ERR(keyring_ref);
 564                 goto error2;
 565         }
 566
 567         /* get the destination keyring if specified */
 568         dest_ref = NULL;
 569         if (destringid) {
 570                 dest_ref = lookup_user_key(destringid, 1, 0, KEY_WRITE);
 571                 if (IS_ERR(dest_ref)) {
 572                         ret = PTR_ERR(dest_ref);
 573                         goto error3;
 574                 }
 575         }
 576
 577         /* find the key type */
 578         ktype = key_type_lookup(type);
 579         if (IS_ERR(ktype)) {
 580                 ret = PTR_ERR(ktype);
 581                 goto error4;
 582         }
 583
 584         /* do the search */
 585         key_ref = keyring_search(keyring_ref, ktype, description);
 586         if (IS_ERR(key_ref)) {
 587                 ret = PTR_ERR(key_ref);
 588
 589                 /* treat lack or presence of a negative key the same */
 590                 if (ret == -EAGAIN)
 591                         ret = -ENOKEY;
 592                 goto error5;
 593         }
 594
 595         /* link the resulting key to the destination keyring if we can */
 596         if (dest_ref) {
 597                 ret = key_permission(key_ref, KEY_LINK);
 598                 if (ret < 0)
 599                         goto error6;
 600
 601                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 602                 if (ret < 0)
 603                         goto error6;
 604         }
 605
 606         ret = key_ref_to_ptr(key_ref)->serial;
 607
 608  error6:
 609         key_ref_put(key_ref);
 610  error5:
 611         key_type_put(ktype);
 612  error4:
 613         key_ref_put(dest_ref);
 614  error3:
 615         key_ref_put(keyring_ref);
 616  error2:
 617         kfree(description);
 618  error:
 619         return ret;
 620
 621 } /* end keyctl_keyring_search() */
 622
 623 /*****************************************************************************/
 624 /*
 625  * read a user key's payload
 626  * - the keyring must be readable or the key must be searchable from the
 627  *   process's keyrings
 628  * - if there's a buffer, we place up to buflen bytes of data into it
 629  * - unless there's an error, we return the amount of data in the key,
 630  *   irrespective of how much we may have copied
 631  * - implements keyctl(KEYCTL_READ)
 632  */
 633 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 634 {
 635         struct key *key;
 636         key_ref_t key_ref;
 637         long ret;
 638
 639         /* find the key first */
 640         key_ref = lookup_user_key(keyid, 0, 0, 0);
 641         if (IS_ERR(key_ref)) {
 642                 ret = -ENOKEY;
 643                 goto error;
 644         }
 645
 646         key = key_ref_to_ptr(key_ref);
 647
 648         /* see if we can read it directly */
 649         ret = key_permission(key_ref, KEY_READ);
 650         if (ret == 0)
 651                 goto can_read_key;
 652         if (ret != -EACCES)
 653                 goto error;
 654
 655         /* we can't; see if it's searchable from this process's keyrings
 656          * - we automatically take account of the fact that it may be
 657          *   dangling off an instantiation key
 658          */
 659         if (!is_key_possessed(key_ref)) {
 660                 ret = -EACCES;
 661                 goto error2;
 662         }
 663
 664         /* the key is probably readable - now try to read it */
 665  can_read_key:
 666         ret = key_validate(key);
 667         if (ret == 0) {
 668                 ret = -EOPNOTSUPP;
 669                 if (key->type->read) {
 670                         /* read the data with the semaphore held (since we
 671                          * might sleep) */
 672                         down_read(&key->sem);
 673                         ret = key->type->read(key, buffer, buflen);
 674                         up_read(&key->sem);
 675                 }
 676         }
 677
 678  error2:
 679         key_put(key);
 680  error:
 681         return ret;
 682
 683 } /* end keyctl_read_key() */
 684
 685 /*****************************************************************************/
 686 /*
 687  * change the ownership of a key
 688  * - the keyring owned by the changer
 689  * - if the uid or gid is -1, then that parameter is not changed
 690  * - implements keyctl(KEYCTL_CHOWN)
 691  */
 692 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 693 {
 694         struct key_user *newowner, *zapowner = NULL;
 695         struct key *key;
 696         key_ref_t key_ref;
 697         long ret;
 698
 699         ret = 0;
 700         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 701                 goto error;
 702
 703         key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
 704         if (IS_ERR(key_ref)) {
 705                 ret = PTR_ERR(key_ref);
 706                 goto error;
 707         }
 708
 709         key = key_ref_to_ptr(key_ref);
 710
 711         /* make the changes with the locks held to prevent chown/chown races */
 712         ret = -EACCES;
 713         down_write(&key->sem);
 714
 715         if (!capable(CAP_SYS_ADMIN)) {
 716                 /* only the sysadmin can chown a key to some other UID */
 717                 if (uid != (uid_t) -1 && key->uid != uid)
 718                         goto error_put;
 719
 720                 /* only the sysadmin can set the key's GID to a group other
 721                  * than one of those that the current process subscribes to */
 722                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 723                         goto error_put;
 724         }
 725
 726         /* change the UID */
 727         if (uid != (uid_t) -1 && uid != key->uid) {
 728                 ret = -ENOMEM;
 729                 newowner = key_user_lookup(uid, current_user_ns());
 730                 if (!newowner)
 731                         goto error_put;
 732
 733                 /* transfer the quota burden to the new user */
 734                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 735                         unsigned maxkeys = (uid == 0) ?
 736                                 key_quota_root_maxkeys : key_quota_maxkeys;
 737                         unsigned maxbytes = (uid == 0) ?
 738                                 key_quota_root_maxbytes : key_quota_maxbytes;
 739
 740                         spin_lock(&newowner->lock);
 741                         if (newowner->qnkeys + 1 >= maxkeys ||
 742                             newowner->qnbytes + key->quotalen >= maxbytes ||
 743                             newowner->qnbytes + key->quotalen <
 744                             newowner->qnbytes)
 745                                 goto quota_overrun;
 746
 747                         newowner->qnkeys++;
 748                         newowner->qnbytes += key->quotalen;
 749                         spin_unlock(&newowner->lock);
 750
 751                         spin_lock(&key->user->lock);
 752                         key->user->qnkeys--;
 753                         key->user->qnbytes -= key->quotalen;
 754                         spin_unlock(&key->user->lock);
 755                 }
 756
 757                 atomic_dec(&key->user->nkeys);
 758                 atomic_inc(&newowner->nkeys);
 759
 760                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 761                         atomic_dec(&key->user->nikeys);
 762                         atomic_inc(&newowner->nikeys);
 763                 }
 764
 765                 zapowner = key->user;
 766                 key->user = newowner;
 767                 key->uid = uid;
 768         }
 769
 770         /* change the GID */
 771         if (gid != (gid_t) -1)
 772                 key->gid = gid;
 773
 774         ret = 0;
 775
 776 error_put:
 777         up_write(&key->sem);
 778         key_put(key);
 779         if (zapowner)
 780                 key_user_put(zapowner);
 781 error:
 782         return ret;
 783
 784 quota_overrun:
 785         spin_unlock(&newowner->lock);
 786         zapowner = newowner;
 787         ret = -EDQUOT;
 788         goto error_put;
 789
 790 } /* end keyctl_chown_key() */
 791
 792 /*****************************************************************************/
 793 /*
 794  * change the permission mask on a key
 795  * - the keyring owned by the changer
 796  * - implements keyctl(KEYCTL_SETPERM)
 797  */
 798 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 799 {
 800         struct key *key;
 801         key_ref_t key_ref;
 802         long ret;
 803
 804         ret = -EINVAL;
 805         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 806                 goto error;
 807
 808         key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
 809         if (IS_ERR(key_ref)) {
 810                 ret = PTR_ERR(key_ref);
 811                 goto error;
 812         }
 813
 814         key = key_ref_to_ptr(key_ref);
 815
 816         /* make the changes with the locks held to prevent chown/chmod races */
 817         ret = -EACCES;
 818         down_write(&key->sem);
 819
 820         /* if we're not the sysadmin, we can only change a key that we own */
 821         if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 822                 key->perm = perm;
 823                 ret = 0;
 824         }
 825
 826         up_write(&key->sem);
 827         key_put(key);
 828 error:
 829         return ret;
 830
 831 } /* end keyctl_setperm_key() */
 832
 833 /*
 834  * get the destination keyring for instantiation
 835  */
 836 static long get_instantiation_keyring(key_serial_t ringid,
 837                                       struct request_key_auth *rka,
 838                                       struct key **_dest_keyring)
 839 {
 840         key_ref_t dkref;
 841
 842         *_dest_keyring = NULL;
 843
 844         /* just return a NULL pointer if we weren't asked to make a link */
 845         if (ringid == 0)
 846                 return 0;
 847
 848         /* if a specific keyring is nominated by ID, then use that */
 849         if (ringid > 0) {
 850                 dkref = lookup_user_key(ringid, 1, 0, KEY_WRITE);
 851                 if (IS_ERR(dkref))
 852                         return PTR_ERR(dkref);
 853                 *_dest_keyring = key_ref_to_ptr(dkref);
 854                 return 0;
 855         }
 856
 857         if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 858                 return -EINVAL;
 859
 860         /* otherwise specify the destination keyring recorded in the
 861          * authorisation key (any KEY_SPEC_*_KEYRING) */
 862         if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 863                 *_dest_keyring = rka->dest_keyring;
 864                 return 0;
 865         }
 866
 867         return -ENOKEY;
 868 }
 869
 870 /*
 871  * change the request_key authorisation key on the current process
 872  */
 873 static int keyctl_change_reqkey_auth(struct key *key)
 874 {
 875         struct cred *new;
 876
 877         new = prepare_creds();
 878         if (!new)
 879                 return -ENOMEM;
 880
 881         key_put(new->request_key_auth);
 882         new->request_key_auth = key_get(key);
 883
 884         return commit_creds(new);
 885 }
 886
 887 /*****************************************************************************/
 888 /*
 889  * instantiate the key with the specified payload, and, if one is given, link
 890  * the key into the keyring
 891  */
 892 long keyctl_instantiate_key(key_serial_t id,
 893                             const void __user *_payload,
 894                             size_t plen,
 895                             key_serial_t ringid)
 896 {
 897         const struct cred *cred = current_cred();
 898         struct request_key_auth *rka;
 899         struct key *instkey, *dest_keyring;
 900         void *payload;
 901         long ret;
 902         bool vm = false;
 903
 904         kenter("%d,,%zu,%d", id, plen, ringid);
 905
 906         ret = -EINVAL;
 907         if (plen > 1024 * 1024 - 1)
 908                 goto error;
 909
 910         /* the appropriate instantiation authorisation key must have been
 911          * assumed before calling this */
 912         ret = -EPERM;
 913         instkey = cred->request_key_auth;
 914         if (!instkey)
 915                 goto error;
 916
 917         rka = instkey->payload.data;
 918         if (rka->target_key->serial != id)
 919                 goto error;
 920
 921         /* pull the payload in if one was supplied */
 922         payload = NULL;
 923
 924         if (_payload) {
 925                 ret = -ENOMEM;
 926                 payload = kmalloc(plen, GFP_KERNEL);
 927                 if (!payload) {
 928                         if (plen <= PAGE_SIZE)
 929                                 goto error;
 930                         vm = true;
 931                         payload = vmalloc(plen);
 932                         if (!payload)
 933                                 goto error;
 934                 }
 935
 936                 ret = -EFAULT;
 937                 if (copy_from_user(payload, _payload, plen) != 0)
 938                         goto error2;
 939         }
 940
 941         /* find the destination keyring amongst those belonging to the
 942          * requesting task */
 943         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
 944         if (ret < 0)
 945                 goto error2;
 946
 947         /* instantiate the key and link it into a keyring */
 948         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 949                                        dest_keyring, instkey);
 950
 951         key_put(dest_keyring);
 952
 953         /* discard the assumed authority if it's just been disabled by
 954          * instantiation of the key */
 955         if (ret == 0)
 956                 keyctl_change_reqkey_auth(NULL);
 957
 958 error2:
 959         if (!vm)
 960                 kfree(payload);
 961         else
 962                 vfree(payload);
 963 error:
 964         return ret;
 965
 966 } /* end keyctl_instantiate_key() */
 967
 968 /*****************************************************************************/
 969 /*
 970  * negatively instantiate the key with the given timeout (in seconds), and, if
 971  * one is given, link the key into the keyring
 972  */
 973 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 974 {
 975         const struct cred *cred = current_cred();
 976         struct request_key_auth *rka;
 977         struct key *instkey, *dest_keyring;
 978         long ret;
 979
 980         kenter("%d,%u,%d", id, timeout, ringid);
 981
 982         /* the appropriate instantiation authorisation key must have been
 983          * assumed before calling this */
 984         ret = -EPERM;
 985         instkey = cred->request_key_auth;
 986         if (!instkey)
 987                 goto error;
 988
 989         rka = instkey->payload.data;
 990         if (rka->target_key->serial != id)
 991                 goto error;
 992
 993         /* find the destination keyring if present (which must also be
 994          * writable) */
 995         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
 996         if (ret < 0)
 997                 goto error;
 998
 999         /* instantiate the key and link it into a keyring */
1000         ret = key_negate_and_link(rka->target_key, timeout,
1001                                   dest_keyring, instkey);
1002
1003         key_put(dest_keyring);
1004
1005         /* discard the assumed authority if it's just been disabled by
1006          * instantiation of the key */
1007         if (ret == 0)
1008                 keyctl_change_reqkey_auth(NULL);
1009
1010 error:
1011         return ret;
1012
1013 } /* end keyctl_negate_key() */
1014
1015 /*****************************************************************************/
1016 /*
1017  * set the default keyring in which request_key() will cache keys
1018  * - return the old setting
1019  */
1020 long keyctl_set_reqkey_keyring(int reqkey_defl)
1021 {
1022         struct cred *new;
1023         int ret, old_setting;
1024
1025         old_setting = current_cred_xxx(jit_keyring);
1026
1027         if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1028                 return old_setting;
1029
1030         new = prepare_creds();
1031         if (!new)
1032                 return -ENOMEM;
1033
1034         switch (reqkey_defl) {
1035         case KEY_REQKEY_DEFL_THREAD_KEYRING:
1036                 ret = install_thread_keyring_to_cred(new);
1037                 if (ret < 0)
1038                         goto error;
1039                 goto set;
1040
1041         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1042                 ret = install_process_keyring_to_cred(new);
1043                 if (ret < 0) {
1044                         if (ret != -EEXIST)
1045                                 goto error;
1046                         ret = 0;
1047                 }
1048                 goto set;
1049
1050         case KEY_REQKEY_DEFL_DEFAULT:
1051         case KEY_REQKEY_DEFL_SESSION_KEYRING:
1052         case KEY_REQKEY_DEFL_USER_KEYRING:
1053         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1054         case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1055                 goto set;
1056
1057         case KEY_REQKEY_DEFL_NO_CHANGE:
1058         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1059         default:
1060                 ret = -EINVAL;
1061                 goto error;
1062         }
1063
1064 set:
1065         new->jit_keyring = reqkey_defl;
1066         commit_creds(new);
1067         return old_setting;
1068 error:
1069         abort_creds(new);
1070         return -EINVAL;
1071
1072 } /* end keyctl_set_reqkey_keyring() */
1073
1074 /*****************************************************************************/
1075 /*
1076  * set or clear the timeout for a key
1077  */
1078 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1079 {
1080         struct timespec now;
1081         struct key *key;
1082         key_ref_t key_ref;
1083         time_t expiry;
1084         long ret;
1085
1086         key_ref = lookup_user_key(id, 1, 1, KEY_SETATTR);
1087         if (IS_ERR(key_ref)) {
1088                 ret = PTR_ERR(key_ref);
1089                 goto error;
1090         }
1091
1092         key = key_ref_to_ptr(key_ref);
1093
1094         /* make the changes with the locks held to prevent races */
1095         down_write(&key->sem);
1096
1097         expiry = 0;
1098         if (timeout > 0) {
1099                 now = current_kernel_time();
1100                 expiry = now.tv_sec + timeout;
1101         }
1102
1103         key->expiry = expiry;
1104
1105         up_write(&key->sem);
1106         key_put(key);
1107
1108         ret = 0;
1109 error:
1110         return ret;
1111
1112 } /* end keyctl_set_timeout() */
1113
1114 /*****************************************************************************/
1115 /*
1116  * assume the authority to instantiate the specified key
1117  */
1118 long keyctl_assume_authority(key_serial_t id)
1119 {
1120         struct key *authkey;
1121         long ret;
1122
1123         /* special key IDs aren't permitted */
1124         ret = -EINVAL;
1125         if (id < 0)
1126                 goto error;
1127
1128         /* we divest ourselves of authority if given an ID of 0 */
1129         if (id == 0) {
1130                 ret = keyctl_change_reqkey_auth(NULL);
1131                 goto error;
1132         }
1133
1134         /* attempt to assume the authority temporarily granted to us whilst we
1135          * instantiate the specified key
1136          * - the authorisation key must be in the current task's keyrings
1137          *   somewhere
1138          */
1139         authkey = key_get_instantiation_authkey(id);
1140         if (IS_ERR(authkey)) {
1141                 ret = PTR_ERR(authkey);
1142                 goto error;
1143         }
1144
1145         ret = keyctl_change_reqkey_auth(authkey);
1146         if (ret < 0)
1147                 goto error;
1148         key_put(authkey);
1149
1150         ret = authkey->serial;
1151 error:
1152         return ret;
1153
1154 } /* end keyctl_assume_authority() */
1155
1156 /*
1157  * get the security label of a key
1158  * - the key must grant us view permission
1159  * - if there's a buffer, we place up to buflen bytes of data into it
1160  * - unless there's an error, we return the amount of information available,
1161  *   irrespective of how much we may have copied (including the terminal NUL)
1162  * - implements keyctl(KEYCTL_GET_SECURITY)
1163  */
1164 long keyctl_get_security(key_serial_t keyid,
1165                          char __user *buffer,
1166                          size_t buflen)
1167 {
1168         struct key *key, *instkey;
1169         key_ref_t key_ref;
1170         char *context;
1171         long ret;
1172
1173         key_ref = lookup_user_key(keyid, 0, 1, KEY_VIEW);
1174         if (IS_ERR(key_ref)) {
1175                 if (PTR_ERR(key_ref) != -EACCES)
1176                         return PTR_ERR(key_ref);
1177
1178                 /* viewing a key under construction is also permitted if we
1179                  * have the authorisation token handy */
1180                 instkey = key_get_instantiation_authkey(keyid);
1181                 if (IS_ERR(instkey))
1182                         return PTR_ERR(key_ref);
1183                 key_put(instkey);
1184
1185                 key_ref = lookup_user_key(keyid, 0, 1, 0);
1186                 if (IS_ERR(key_ref))
1187                         return PTR_ERR(key_ref);
1188         }
1189
1190         key = key_ref_to_ptr(key_ref);
1191         ret = security_key_getsecurity(key, &context);
1192         if (ret == 0) {
1193                 /* if no information was returned, give userspace an empty
1194                  * string */
1195                 ret = 1;
1196                 if (buffer && buflen > 0 &&
1197                     copy_to_user(buffer, "", 1) != 0)
1198                         ret = -EFAULT;
1199         } else if (ret > 0) {
1200                 /* return as much data as there's room for */
1201                 if (buffer && buflen > 0) {
1202                         if (buflen > ret)
1203                                 buflen = ret;
1204
1205                         if (copy_to_user(buffer, context, buflen) != 0)
1206                                 ret = -EFAULT;
1207                 }
1208
1209                 kfree(context);
1210         }
1211
1212         key_ref_put(key_ref);
1213         return ret;
1214 }
1215
1216 /*****************************************************************************/
1217 /*
1218  * the key control system call
1219  */
1220 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1221                 unsigned long, arg4, unsigned long, arg5)
1222 {
1223         switch (option) {
1224         case KEYCTL_GET_KEYRING_ID:
1225                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1226                                              (int) arg3);
1227
1228         case KEYCTL_JOIN_SESSION_KEYRING:
1229                 return keyctl_join_session_keyring((const char __user *) arg2);
1230
1231         case KEYCTL_UPDATE:
1232                 return keyctl_update_key((key_serial_t) arg2,
1233                                          (const void __user *) arg3,
1234                                          (size_t) arg4);
1235
1236         case KEYCTL_REVOKE:
1237                 return keyctl_revoke_key((key_serial_t) arg2);
1238
1239         case KEYCTL_DESCRIBE:
1240                 return keyctl_describe_key((key_serial_t) arg2,
1241                                            (char __user *) arg3,
1242                                            (unsigned) arg4);
1243
1244         case KEYCTL_CLEAR:
1245                 return keyctl_keyring_clear((key_serial_t) arg2);
1246
1247         case KEYCTL_LINK:
1248                 return keyctl_keyring_link((key_serial_t) arg2,
1249                                            (key_serial_t) arg3);
1250
1251         case KEYCTL_UNLINK:
1252                 return keyctl_keyring_unlink((key_serial_t) arg2,
1253                                              (key_serial_t) arg3);
1254
1255         case KEYCTL_SEARCH:
1256                 return keyctl_keyring_search((key_serial_t) arg2,
1257                                              (const char __user *) arg3,
1258                                              (const char __user *) arg4,
1259                                              (key_serial_t) arg5);
1260
1261         case KEYCTL_READ:
1262                 return keyctl_read_key((key_serial_t) arg2,
1263                                        (char __user *) arg3,
1264                                        (size_t) arg4);
1265
1266         case KEYCTL_CHOWN:
1267                 return keyctl_chown_key((key_serial_t) arg2,
1268                                         (uid_t) arg3,
1269                                         (gid_t) arg4);
1270
1271         case KEYCTL_SETPERM:
1272                 return keyctl_setperm_key((key_serial_t) arg2,
1273                                           (key_perm_t) arg3);
1274
1275         case KEYCTL_INSTANTIATE:
1276                 return keyctl_instantiate_key((key_serial_t) arg2,
1277                                               (const void __user *) arg3,
1278                                               (size_t) arg4,
1279                                               (key_serial_t) arg5);
1280
1281         case KEYCTL_NEGATE:
1282                 return keyctl_negate_key((key_serial_t) arg2,
1283                                          (unsigned) arg3,
1284                                          (key_serial_t) arg4);
1285
1286         case KEYCTL_SET_REQKEY_KEYRING:
1287                 return keyctl_set_reqkey_keyring(arg2);
1288
1289         case KEYCTL_SET_TIMEOUT:
1290                 return keyctl_set_timeout((key_serial_t) arg2,
1291                                           (unsigned) arg3);
1292
1293         case KEYCTL_ASSUME_AUTHORITY:
1294                 return keyctl_assume_authority((key_serial_t) arg2);
1295
1296         case KEYCTL_GET_SECURITY:
1297                 return keyctl_get_security((key_serial_t) arg2,
1298                                            (char __user *) arg3,
1299                                            (size_t) arg4);
1300
1301         default:
1302                 return -EOPNOTSUPP;
1303         }
1304
1305 } /* end sys_keyctl() */