linux/security/keys/keyctl.c
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   1/* Userspace key control 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
  27static 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        if (ret < 0)
  35                return ret;
  36        if (ret == 0 || ret >= len)
  37                return -EINVAL;
  38        if (type[0] == '.')
  39                return -EPERM;
  40        type[len - 1] = '\0';
  41        return 0;
  42}
  43
  44/*
  45 * Extract the description of a new key from userspace and either add it as a
  46 * new key to the specified keyring or update a matching key in that keyring.
  47 *
  48 * The keyring must be writable so that we can attach the key to it.
  49 *
  50 * If successful, the new key's serial number is returned, otherwise an error
  51 * code is returned.
  52 */
  53SYSCALL_DEFINE5(add_key, const char __user *, _type,
  54                const char __user *, _description,
  55                const void __user *, _payload,
  56                size_t, plen,
  57                key_serial_t, ringid)
  58{
  59        key_ref_t keyring_ref, key_ref;
  60        char type[32], *description;
  61        void *payload;
  62        long ret;
  63        bool vm;
  64
  65        ret = -EINVAL;
  66        if (plen > 1024 * 1024 - 1)
  67                goto error;
  68
  69        /* draw all the data into kernel space */
  70        ret = key_get_type_from_user(type, _type, sizeof(type));
  71        if (ret < 0)
  72                goto error;
  73
  74        description = strndup_user(_description, PAGE_SIZE);
  75        if (IS_ERR(description)) {
  76                ret = PTR_ERR(description);
  77                goto error;
  78        }
  79
  80        /* pull the payload in if one was supplied */
  81        payload = NULL;
  82
  83        vm = false;
  84        if (_payload) {
  85                ret = -ENOMEM;
  86                payload = kmalloc(plen, GFP_KERNEL);
  87                if (!payload) {
  88                        if (plen <= PAGE_SIZE)
  89                                goto error2;
  90                        vm = true;
  91                        payload = vmalloc(plen);
  92                        if (!payload)
  93                                goto error2;
  94                }
  95
  96                ret = -EFAULT;
  97                if (copy_from_user(payload, _payload, plen) != 0)
  98                        goto error3;
  99        }
 100
 101        /* find the target keyring (which must be writable) */
 102        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 103        if (IS_ERR(keyring_ref)) {
 104                ret = PTR_ERR(keyring_ref);
 105                goto error3;
 106        }
 107
 108        /* create or update the requested key and add it to the target
 109         * keyring */
 110        key_ref = key_create_or_update(keyring_ref, type, description,
 111                                       payload, plen, KEY_PERM_UNDEF,
 112                                       KEY_ALLOC_IN_QUOTA);
 113        if (!IS_ERR(key_ref)) {
 114                ret = key_ref_to_ptr(key_ref)->serial;
 115                key_ref_put(key_ref);
 116        }
 117        else {
 118                ret = PTR_ERR(key_ref);
 119        }
 120
 121        key_ref_put(keyring_ref);
 122 error3:
 123        if (!vm)
 124                kfree(payload);
 125        else
 126                vfree(payload);
 127 error2:
 128        kfree(description);
 129 error:
 130        return ret;
 131}
 132
 133/*
 134 * Search the process keyrings and keyring trees linked from those for a
 135 * matching key.  Keyrings must have appropriate Search permission to be
 136 * searched.
 137 *
 138 * If a key is found, it will be attached to the destination keyring if there's
 139 * one specified and the serial number of the key will be returned.
 140 *
 141 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 142 * non-NULL in an attempt to create a key.  The _callout_info string will be
 143 * passed to /sbin/request-key to aid with completing the request.  If the
 144 * _callout_info string is "" then it will be changed to "-".
 145 */
 146SYSCALL_DEFINE4(request_key, const char __user *, _type,
 147                const char __user *, _description,
 148                const char __user *, _callout_info,
 149                key_serial_t, destringid)
 150{
 151        struct key_type *ktype;
 152        struct key *key;
 153        key_ref_t dest_ref;
 154        size_t callout_len;
 155        char type[32], *description, *callout_info;
 156        long ret;
 157
 158        /* pull the type into kernel space */
 159        ret = key_get_type_from_user(type, _type, sizeof(type));
 160        if (ret < 0)
 161                goto error;
 162
 163        /* pull the description into kernel space */
 164        description = strndup_user(_description, PAGE_SIZE);
 165        if (IS_ERR(description)) {
 166                ret = PTR_ERR(description);
 167                goto error;
 168        }
 169
 170        /* pull the callout info into kernel space */
 171        callout_info = NULL;
 172        callout_len = 0;
 173        if (_callout_info) {
 174                callout_info = strndup_user(_callout_info, PAGE_SIZE);
 175                if (IS_ERR(callout_info)) {
 176                        ret = PTR_ERR(callout_info);
 177                        goto error2;
 178                }
 179                callout_len = strlen(callout_info);
 180        }
 181
 182        /* get the destination keyring if specified */
 183        dest_ref = NULL;
 184        if (destringid) {
 185                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 186                                           KEY_WRITE);
 187                if (IS_ERR(dest_ref)) {
 188                        ret = PTR_ERR(dest_ref);
 189                        goto error3;
 190                }
 191        }
 192
 193        /* find the key type */
 194        ktype = key_type_lookup(type);
 195        if (IS_ERR(ktype)) {
 196                ret = PTR_ERR(ktype);
 197                goto error4;
 198        }
 199
 200        /* do the search */
 201        key = request_key_and_link(ktype, description, callout_info,
 202                                   callout_len, NULL, key_ref_to_ptr(dest_ref),
 203                                   KEY_ALLOC_IN_QUOTA);
 204        if (IS_ERR(key)) {
 205                ret = PTR_ERR(key);
 206                goto error5;
 207        }
 208
 209        /* wait for the key to finish being constructed */
 210        ret = wait_for_key_construction(key, 1);
 211        if (ret < 0)
 212                goto error6;
 213
 214        ret = key->serial;
 215
 216error6:
 217        key_put(key);
 218error5:
 219        key_type_put(ktype);
 220error4:
 221        key_ref_put(dest_ref);
 222error3:
 223        kfree(callout_info);
 224error2:
 225        kfree(description);
 226error:
 227        return ret;
 228}
 229
 230/*
 231 * Get the ID of the specified process keyring.
 232 *
 233 * The requested keyring must have search permission to be found.
 234 *
 235 * If successful, the ID of the requested keyring will be returned.
 236 */
 237long keyctl_get_keyring_ID(key_serial_t id, int create)
 238{
 239        key_ref_t key_ref;
 240        unsigned long lflags;
 241        long ret;
 242
 243        lflags = create ? KEY_LOOKUP_CREATE : 0;
 244        key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 245        if (IS_ERR(key_ref)) {
 246                ret = PTR_ERR(key_ref);
 247                goto error;
 248        }
 249
 250        ret = key_ref_to_ptr(key_ref)->serial;
 251        key_ref_put(key_ref);
 252error:
 253        return ret;
 254}
 255
 256/*
 257 * Join a (named) session keyring.
 258 *
 259 * Create and join an anonymous session keyring or join a named session
 260 * keyring, creating it if necessary.  A named session keyring must have Search
 261 * permission for it to be joined.  Session keyrings without this permit will
 262 * be skipped over.
 263 *
 264 * If successful, the ID of the joined session keyring will be returned.
 265 */
 266long keyctl_join_session_keyring(const char __user *_name)
 267{
 268        char *name;
 269        long ret;
 270
 271        /* fetch the name from userspace */
 272        name = NULL;
 273        if (_name) {
 274                name = strndup_user(_name, PAGE_SIZE);
 275                if (IS_ERR(name)) {
 276                        ret = PTR_ERR(name);
 277                        goto error;
 278                }
 279        }
 280
 281        /* join the session */
 282        ret = join_session_keyring(name);
 283        kfree(name);
 284
 285error:
 286        return ret;
 287}
 288
 289/*
 290 * Update a key's data payload from the given data.
 291 *
 292 * The key must grant the caller Write permission and the key type must support
 293 * updating for this to work.  A negative key can be positively instantiated
 294 * with this call.
 295 *
 296 * If successful, 0 will be returned.  If the key type does not support
 297 * updating, then -EOPNOTSUPP will be returned.
 298 */
 299long keyctl_update_key(key_serial_t id,
 300                       const void __user *_payload,
 301                       size_t plen)
 302{
 303        key_ref_t key_ref;
 304        void *payload;
 305        long ret;
 306
 307        ret = -EINVAL;
 308        if (plen > PAGE_SIZE)
 309                goto error;
 310
 311        /* pull the payload in if one was supplied */
 312        payload = NULL;
 313        if (_payload) {
 314                ret = -ENOMEM;
 315                payload = kmalloc(plen, GFP_KERNEL);
 316                if (!payload)
 317                        goto error;
 318
 319                ret = -EFAULT;
 320                if (copy_from_user(payload, _payload, plen) != 0)
 321                        goto error2;
 322        }
 323
 324        /* find the target key (which must be writable) */
 325        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 326        if (IS_ERR(key_ref)) {
 327                ret = PTR_ERR(key_ref);
 328                goto error2;
 329        }
 330
 331        /* update the key */
 332        ret = key_update(key_ref, payload, plen);
 333
 334        key_ref_put(key_ref);
 335error2:
 336        kfree(payload);
 337error:
 338        return ret;
 339}
 340
 341/*
 342 * Revoke a key.
 343 *
 344 * The key must be grant the caller Write or Setattr permission for this to
 345 * work.  The key type should give up its quota claim when revoked.  The key
 346 * and any links to the key will be automatically garbage collected after a
 347 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 348 *
 349 * If successful, 0 is returned.
 350 */
 351long keyctl_revoke_key(key_serial_t id)
 352{
 353        key_ref_t key_ref;
 354        long ret;
 355
 356        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 357        if (IS_ERR(key_ref)) {
 358                ret = PTR_ERR(key_ref);
 359                if (ret != -EACCES)
 360                        goto error;
 361                key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 362                if (IS_ERR(key_ref)) {
 363                        ret = PTR_ERR(key_ref);
 364                        goto error;
 365                }
 366        }
 367
 368        key_revoke(key_ref_to_ptr(key_ref));
 369        ret = 0;
 370
 371        key_ref_put(key_ref);
 372error:
 373        return ret;
 374}
 375
 376/*
 377 * Clear the specified keyring, creating an empty process keyring if one of the
 378 * special keyring IDs is used.
 379 *
 380 * The keyring must grant the caller Write permission for this to work.  If
 381 * successful, 0 will be returned.
 382 */
 383long keyctl_keyring_clear(key_serial_t ringid)
 384{
 385        key_ref_t keyring_ref;
 386        long ret;
 387
 388        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, 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);
 397error:
 398        return ret;
 399}
 400
 401/*
 402 * Create a link from a keyring to a key if there's no matching key in the
 403 * keyring, otherwise replace the link to the matching key with a link to the
 404 * new key.
 405 *
 406 * The key must grant the caller Link permission and the the keyring must grant
 407 * the caller Write permission.  Furthermore, if an additional link is created,
 408 * the keyring's quota will be extended.
 409 *
 410 * If successful, 0 will be returned.
 411 */
 412long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 413{
 414        key_ref_t keyring_ref, key_ref;
 415        long ret;
 416
 417        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 418        if (IS_ERR(keyring_ref)) {
 419                ret = PTR_ERR(keyring_ref);
 420                goto error;
 421        }
 422
 423        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 424        if (IS_ERR(key_ref)) {
 425                ret = PTR_ERR(key_ref);
 426                goto error2;
 427        }
 428
 429        ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 430
 431        key_ref_put(key_ref);
 432error2:
 433        key_ref_put(keyring_ref);
 434error:
 435        return ret;
 436}
 437
 438/*
 439 * Unlink a key from a keyring.
 440 *
 441 * The keyring must grant the caller Write permission for this to work; the key
 442 * itself need not grant the caller anything.  If the last link to a key is
 443 * removed then that key will be scheduled for destruction.
 444 *
 445 * If successful, 0 will be returned.
 446 */
 447long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 448{
 449        key_ref_t keyring_ref, key_ref;
 450        long ret;
 451
 452        keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 453        if (IS_ERR(keyring_ref)) {
 454                ret = PTR_ERR(keyring_ref);
 455                goto error;
 456        }
 457
 458        key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 459        if (IS_ERR(key_ref)) {
 460                ret = PTR_ERR(key_ref);
 461                goto error2;
 462        }
 463
 464        ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 465
 466        key_ref_put(key_ref);
 467error2:
 468        key_ref_put(keyring_ref);
 469error:
 470        return ret;
 471}
 472
 473/*
 474 * Return a description of a key to userspace.
 475 *
 476 * The key must grant the caller View permission for this to work.
 477 *
 478 * If there's a buffer, we place up to buflen bytes of data into it formatted
 479 * in the following way:
 480 *
 481 *      type;uid;gid;perm;description<NUL>
 482 *
 483 * If successful, we return the amount of description available, irrespective
 484 * of how much we may have copied into the buffer.
 485 */
 486long keyctl_describe_key(key_serial_t keyid,
 487                         char __user *buffer,
 488                         size_t buflen)
 489{
 490        struct key *key, *instkey;
 491        key_ref_t key_ref;
 492        char *tmpbuf;
 493        long ret;
 494
 495        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 496        if (IS_ERR(key_ref)) {
 497                /* viewing a key under construction is permitted if we have the
 498                 * authorisation token handy */
 499                if (PTR_ERR(key_ref) == -EACCES) {
 500                        instkey = key_get_instantiation_authkey(keyid);
 501                        if (!IS_ERR(instkey)) {
 502                                key_put(instkey);
 503                                key_ref = lookup_user_key(keyid,
 504                                                          KEY_LOOKUP_PARTIAL,
 505                                                          0);
 506                                if (!IS_ERR(key_ref))
 507                                        goto okay;
 508                        }
 509                }
 510
 511                ret = PTR_ERR(key_ref);
 512                goto error;
 513        }
 514
 515okay:
 516        /* calculate how much description we're going to return */
 517        ret = -ENOMEM;
 518        tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 519        if (!tmpbuf)
 520                goto error2;
 521
 522        key = key_ref_to_ptr(key_ref);
 523
 524        ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 525                       "%s;%d;%d;%08x;%s",
 526                       key->type->name,
 527                       key->uid,
 528                       key->gid,
 529                       key->perm,
 530                       key->description ?: "");
 531
 532        /* include a NUL char at the end of the data */
 533        if (ret > PAGE_SIZE - 1)
 534                ret = PAGE_SIZE - 1;
 535        tmpbuf[ret] = 0;
 536        ret++;
 537
 538        /* consider returning the data */
 539        if (buffer && buflen > 0) {
 540                if (buflen > ret)
 541                        buflen = ret;
 542
 543                if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 544                        ret = -EFAULT;
 545        }
 546
 547        kfree(tmpbuf);
 548error2:
 549        key_ref_put(key_ref);
 550error:
 551        return ret;
 552}
 553
 554/*
 555 * Search the specified keyring and any keyrings it links to for a matching
 556 * key.  Only keyrings that grant the caller Search permission will be searched
 557 * (this includes the starting keyring).  Only keys with Search permission can
 558 * be found.
 559 *
 560 * If successful, the found key will be linked to the destination keyring if
 561 * supplied and the key has Link permission, and the found key ID will be
 562 * returned.
 563 */
 564long keyctl_keyring_search(key_serial_t ringid,
 565                           const char __user *_type,
 566                           const char __user *_description,
 567                           key_serial_t destringid)
 568{
 569        struct key_type *ktype;
 570        key_ref_t keyring_ref, key_ref, dest_ref;
 571        char type[32], *description;
 572        long ret;
 573
 574        /* pull the type and description into kernel space */
 575        ret = key_get_type_from_user(type, _type, sizeof(type));
 576        if (ret < 0)
 577                goto error;
 578
 579        description = strndup_user(_description, PAGE_SIZE);
 580        if (IS_ERR(description)) {
 581                ret = PTR_ERR(description);
 582                goto error;
 583        }
 584
 585        /* get the keyring at which to begin the search */
 586        keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 587        if (IS_ERR(keyring_ref)) {
 588                ret = PTR_ERR(keyring_ref);
 589                goto error2;
 590        }
 591
 592        /* get the destination keyring if specified */
 593        dest_ref = NULL;
 594        if (destringid) {
 595                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 596                                           KEY_WRITE);
 597                if (IS_ERR(dest_ref)) {
 598                        ret = PTR_ERR(dest_ref);
 599                        goto error3;
 600                }
 601        }
 602
 603        /* find the key type */
 604        ktype = key_type_lookup(type);
 605        if (IS_ERR(ktype)) {
 606                ret = PTR_ERR(ktype);
 607                goto error4;
 608        }
 609
 610        /* do the search */
 611        key_ref = keyring_search(keyring_ref, ktype, description);
 612        if (IS_ERR(key_ref)) {
 613                ret = PTR_ERR(key_ref);
 614
 615                /* treat lack or presence of a negative key the same */
 616                if (ret == -EAGAIN)
 617                        ret = -ENOKEY;
 618                goto error5;
 619        }
 620
 621        /* link the resulting key to the destination keyring if we can */
 622        if (dest_ref) {
 623                ret = key_permission(key_ref, KEY_LINK);
 624                if (ret < 0)
 625                        goto error6;
 626
 627                ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 628                if (ret < 0)
 629                        goto error6;
 630        }
 631
 632        ret = key_ref_to_ptr(key_ref)->serial;
 633
 634error6:
 635        key_ref_put(key_ref);
 636error5:
 637        key_type_put(ktype);
 638error4:
 639        key_ref_put(dest_ref);
 640error3:
 641        key_ref_put(keyring_ref);
 642error2:
 643        kfree(description);
 644error:
 645        return ret;
 646}
 647
 648/*
 649 * Read a key's payload.
 650 *
 651 * The key must either grant the caller Read permission, or it must grant the
 652 * caller Search permission when searched for from the process keyrings.
 653 *
 654 * If successful, we place up to buflen bytes of data into the buffer, if one
 655 * is provided, and return the amount of data that is available in the key,
 656 * irrespective of how much we copied into the buffer.
 657 */
 658long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 659{
 660        struct key *key;
 661        key_ref_t key_ref;
 662        long ret;
 663
 664        /* find the key first */
 665        key_ref = lookup_user_key(keyid, 0, 0);
 666        if (IS_ERR(key_ref)) {
 667                ret = -ENOKEY;
 668                goto error;
 669        }
 670
 671        key = key_ref_to_ptr(key_ref);
 672
 673        /* see if we can read it directly */
 674        ret = key_permission(key_ref, KEY_READ);
 675        if (ret == 0)
 676                goto can_read_key;
 677        if (ret != -EACCES)
 678                goto error;
 679
 680        /* we can't; see if it's searchable from this process's keyrings
 681         * - we automatically take account of the fact that it may be
 682         *   dangling off an instantiation key
 683         */
 684        if (!is_key_possessed(key_ref)) {
 685                ret = -EACCES;
 686                goto error2;
 687        }
 688
 689        /* the key is probably readable - now try to read it */
 690can_read_key:
 691        ret = key_validate(key);
 692        if (ret == 0) {
 693                ret = -EOPNOTSUPP;
 694                if (key->type->read) {
 695                        /* read the data with the semaphore held (since we
 696                         * might sleep) */
 697                        down_read(&key->sem);
 698                        ret = key->type->read(key, buffer, buflen);
 699                        up_read(&key->sem);
 700                }
 701        }
 702
 703error2:
 704        key_put(key);
 705error:
 706        return ret;
 707}
 708
 709/*
 710 * Change the ownership of a key
 711 *
 712 * The key must grant the caller Setattr permission for this to work, though
 713 * the key need not be fully instantiated yet.  For the UID to be changed, or
 714 * for the GID to be changed to a group the caller is not a member of, the
 715 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 716 * attribute is not changed.
 717 *
 718 * If the UID is to be changed, the new user must have sufficient quota to
 719 * accept the key.  The quota deduction will be removed from the old user to
 720 * the new user should the attribute be changed.
 721 *
 722 * If successful, 0 will be returned.
 723 */
 724long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 725{
 726        struct key_user *newowner, *zapowner = NULL;
 727        struct key *key;
 728        key_ref_t key_ref;
 729        long ret;
 730
 731        ret = 0;
 732        if (uid == (uid_t) -1 && gid == (gid_t) -1)
 733                goto error;
 734
 735        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 736                                  KEY_SETATTR);
 737        if (IS_ERR(key_ref)) {
 738                ret = PTR_ERR(key_ref);
 739                goto error;
 740        }
 741
 742        key = key_ref_to_ptr(key_ref);
 743
 744        /* make the changes with the locks held to prevent chown/chown races */
 745        ret = -EACCES;
 746        down_write(&key->sem);
 747
 748        if (!capable(CAP_SYS_ADMIN)) {
 749                /* only the sysadmin can chown a key to some other UID */
 750                if (uid != (uid_t) -1 && key->uid != uid)
 751                        goto error_put;
 752
 753                /* only the sysadmin can set the key's GID to a group other
 754                 * than one of those that the current process subscribes to */
 755                if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 756                        goto error_put;
 757        }
 758
 759        /* change the UID */
 760        if (uid != (uid_t) -1 && uid != key->uid) {
 761                ret = -ENOMEM;
 762                newowner = key_user_lookup(uid, current_user_ns());
 763                if (!newowner)
 764                        goto error_put;
 765
 766                /* transfer the quota burden to the new user */
 767                if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 768                        unsigned maxkeys = (uid == 0) ?
 769                                key_quota_root_maxkeys : key_quota_maxkeys;
 770                        unsigned maxbytes = (uid == 0) ?
 771                                key_quota_root_maxbytes : key_quota_maxbytes;
 772
 773                        spin_lock(&newowner->lock);
 774                        if (newowner->qnkeys + 1 >= maxkeys ||
 775                            newowner->qnbytes + key->quotalen >= maxbytes ||
 776                            newowner->qnbytes + key->quotalen <
 777                            newowner->qnbytes)
 778                                goto quota_overrun;
 779
 780                        newowner->qnkeys++;
 781                        newowner->qnbytes += key->quotalen;
 782                        spin_unlock(&newowner->lock);
 783
 784                        spin_lock(&key->user->lock);
 785                        key->user->qnkeys--;
 786                        key->user->qnbytes -= key->quotalen;
 787                        spin_unlock(&key->user->lock);
 788                }
 789
 790                atomic_dec(&key->user->nkeys);
 791                atomic_inc(&newowner->nkeys);
 792
 793                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 794                        atomic_dec(&key->user->nikeys);
 795                        atomic_inc(&newowner->nikeys);
 796                }
 797
 798                zapowner = key->user;
 799                key->user = newowner;
 800                key->uid = uid;
 801        }
 802
 803        /* change the GID */
 804        if (gid != (gid_t) -1)
 805                key->gid = gid;
 806
 807        ret = 0;
 808
 809error_put:
 810        up_write(&key->sem);
 811        key_put(key);
 812        if (zapowner)
 813                key_user_put(zapowner);
 814error:
 815        return ret;
 816
 817quota_overrun:
 818        spin_unlock(&newowner->lock);
 819        zapowner = newowner;
 820        ret = -EDQUOT;
 821        goto error_put;
 822}
 823
 824/*
 825 * Change the permission mask on a key.
 826 *
 827 * The key must grant the caller Setattr permission for this to work, though
 828 * the key need not be fully instantiated yet.  If the caller does not have
 829 * sysadmin capability, it may only change the permission on keys that it owns.
 830 */
 831long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 832{
 833        struct key *key;
 834        key_ref_t key_ref;
 835        long ret;
 836
 837        ret = -EINVAL;
 838        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 839                goto error;
 840
 841        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 842                                  KEY_SETATTR);
 843        if (IS_ERR(key_ref)) {
 844                ret = PTR_ERR(key_ref);
 845                goto error;
 846        }
 847
 848        key = key_ref_to_ptr(key_ref);
 849
 850        /* make the changes with the locks held to prevent chown/chmod races */
 851        ret = -EACCES;
 852        down_write(&key->sem);
 853
 854        /* if we're not the sysadmin, we can only change a key that we own */
 855        if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 856                key->perm = perm;
 857                ret = 0;
 858        }
 859
 860        up_write(&key->sem);
 861        key_put(key);
 862error:
 863        return ret;
 864}
 865
 866/*
 867 * Get the destination keyring for instantiation and check that the caller has
 868 * Write permission on it.
 869 */
 870static long get_instantiation_keyring(key_serial_t ringid,
 871                                      struct request_key_auth *rka,
 872                                      struct key **_dest_keyring)
 873{
 874        key_ref_t dkref;
 875
 876        *_dest_keyring = NULL;
 877
 878        /* just return a NULL pointer if we weren't asked to make a link */
 879        if (ringid == 0)
 880                return 0;
 881
 882        /* if a specific keyring is nominated by ID, then use that */
 883        if (ringid > 0) {
 884                dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 885                if (IS_ERR(dkref))
 886                        return PTR_ERR(dkref);
 887                *_dest_keyring = key_ref_to_ptr(dkref);
 888                return 0;
 889        }
 890
 891        if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 892                return -EINVAL;
 893
 894        /* otherwise specify the destination keyring recorded in the
 895         * authorisation key (any KEY_SPEC_*_KEYRING) */
 896        if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 897                *_dest_keyring = key_get(rka->dest_keyring);
 898                return 0;
 899        }
 900
 901        return -ENOKEY;
 902}
 903
 904/*
 905 * Change the request_key authorisation key on the current process.
 906 */
 907static int keyctl_change_reqkey_auth(struct key *key)
 908{
 909        struct cred *new;
 910
 911        new = prepare_creds();
 912        if (!new)
 913                return -ENOMEM;
 914
 915        key_put(new->request_key_auth);
 916        new->request_key_auth = key_get(key);
 917
 918        return commit_creds(new);
 919}
 920
 921/*
 922 * Copy the iovec data from userspace
 923 */
 924static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
 925                                 unsigned ioc)
 926{
 927        for (; ioc > 0; ioc--) {
 928                if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
 929                        return -EFAULT;
 930                buffer += iov->iov_len;
 931                iov++;
 932        }
 933        return 0;
 934}
 935
 936/*
 937 * Instantiate a key with the specified payload and link the key into the
 938 * destination keyring if one is given.
 939 *
 940 * The caller must have the appropriate instantiation permit set for this to
 941 * work (see keyctl_assume_authority).  No other permissions are required.
 942 *
 943 * If successful, 0 will be returned.
 944 */
 945long keyctl_instantiate_key_common(key_serial_t id,
 946                                   const struct iovec *payload_iov,
 947                                   unsigned ioc,
 948                                   size_t plen,
 949                                   key_serial_t ringid)
 950{
 951        const struct cred *cred = current_cred();
 952        struct request_key_auth *rka;
 953        struct key *instkey, *dest_keyring;
 954        void *payload;
 955        long ret;
 956        bool vm = false;
 957
 958        kenter("%d,,%zu,%d", id, plen, ringid);
 959
 960        ret = -EINVAL;
 961        if (plen > 1024 * 1024 - 1)
 962                goto error;
 963
 964        /* the appropriate instantiation authorisation key must have been
 965         * assumed before calling this */
 966        ret = -EPERM;
 967        instkey = cred->request_key_auth;
 968        if (!instkey)
 969                goto error;
 970
 971        rka = instkey->payload.data;
 972        if (rka->target_key->serial != id)
 973                goto error;
 974
 975        /* pull the payload in if one was supplied */
 976        payload = NULL;
 977
 978        if (payload_iov) {
 979                ret = -ENOMEM;
 980                payload = kmalloc(plen, GFP_KERNEL);
 981                if (!payload) {
 982                        if (plen <= PAGE_SIZE)
 983                                goto error;
 984                        vm = true;
 985                        payload = vmalloc(plen);
 986                        if (!payload)
 987                                goto error;
 988                }
 989
 990                ret = copy_from_user_iovec(payload, payload_iov, ioc);
 991                if (ret < 0)
 992                        goto error2;
 993        }
 994
 995        /* find the destination keyring amongst those belonging to the
 996         * requesting task */
 997        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
 998        if (ret < 0)
 999                goto error2;
1000
1001        /* instantiate the key and link it into a keyring */
1002        ret = key_instantiate_and_link(rka->target_key, payload, plen,
1003                                       dest_keyring, instkey);
1004
1005        key_put(dest_keyring);
1006
1007        /* discard the assumed authority if it's just been disabled by
1008         * instantiation of the key */
1009        if (ret == 0)
1010                keyctl_change_reqkey_auth(NULL);
1011
1012error2:
1013        if (!vm)
1014                kfree(payload);
1015        else
1016                vfree(payload);
1017error:
1018        return ret;
1019}
1020
1021/*
1022 * Instantiate a key with the specified payload and link the key into the
1023 * destination keyring if one is given.
1024 *
1025 * The caller must have the appropriate instantiation permit set for this to
1026 * work (see keyctl_assume_authority).  No other permissions are required.
1027 *
1028 * If successful, 0 will be returned.
1029 */
1030long keyctl_instantiate_key(key_serial_t id,
1031                            const void __user *_payload,
1032                            size_t plen,
1033                            key_serial_t ringid)
1034{
1035        if (_payload && plen) {
1036                struct iovec iov[1] = {
1037                        [0].iov_base = (void __user *)_payload,
1038                        [0].iov_len  = plen
1039                };
1040
1041                return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1042        }
1043
1044        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1045}
1046
1047/*
1048 * Instantiate a key with the specified multipart payload and link the key into
1049 * the destination keyring if one is given.
1050 *
1051 * The caller must have the appropriate instantiation permit set for this to
1052 * work (see keyctl_assume_authority).  No other permissions are required.
1053 *
1054 * If successful, 0 will be returned.
1055 */
1056long keyctl_instantiate_key_iov(key_serial_t id,
1057                                const struct iovec __user *_payload_iov,
1058                                unsigned ioc,
1059                                key_serial_t ringid)
1060{
1061        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1062        long ret;
1063
1064        if (_payload_iov == 0 || ioc == 0)
1065                goto no_payload;
1066
1067        ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1068                                    ARRAY_SIZE(iovstack), iovstack, &iov, 1);
1069        if (ret < 0)
1070                return ret;
1071        if (ret == 0)
1072                goto no_payload_free;
1073
1074        ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1075
1076        if (iov != iovstack)
1077                kfree(iov);
1078        return ret;
1079
1080no_payload_free:
1081        if (iov != iovstack)
1082                kfree(iov);
1083no_payload:
1084        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1085}
1086
1087/*
1088 * Negatively instantiate the key with the given timeout (in seconds) and link
1089 * the key into the destination keyring if one is given.
1090 *
1091 * The caller must have the appropriate instantiation permit set for this to
1092 * work (see keyctl_assume_authority).  No other permissions are required.
1093 *
1094 * The key and any links to the key will be automatically garbage collected
1095 * after the timeout expires.
1096 *
1097 * Negative keys are used to rate limit repeated request_key() calls by causing
1098 * them to return -ENOKEY until the negative key expires.
1099 *
1100 * If successful, 0 will be returned.
1101 */
1102long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1103{
1104        return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1105}
1106
1107/*
1108 * Negatively instantiate the key with the given timeout (in seconds) and error
1109 * code and link the key into the destination keyring if one is given.
1110 *
1111 * The caller must have the appropriate instantiation permit set for this to
1112 * work (see keyctl_assume_authority).  No other permissions are required.
1113 *
1114 * The key and any links to the key will be automatically garbage collected
1115 * after the timeout expires.
1116 *
1117 * Negative keys are used to rate limit repeated request_key() calls by causing
1118 * them to return the specified error code until the negative key expires.
1119 *
1120 * If successful, 0 will be returned.
1121 */
1122long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1123                       key_serial_t ringid)
1124{
1125        const struct cred *cred = current_cred();
1126        struct request_key_auth *rka;
1127        struct key *instkey, *dest_keyring;
1128        long ret;
1129
1130        kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1131
1132        /* must be a valid error code and mustn't be a kernel special */
1133        if (error <= 0 ||
1134            error >= MAX_ERRNO ||
1135            error == ERESTARTSYS ||
1136            error == ERESTARTNOINTR ||
1137            error == ERESTARTNOHAND ||
1138            error == ERESTART_RESTARTBLOCK)
1139                return -EINVAL;
1140
1141        /* the appropriate instantiation authorisation key must have been
1142         * assumed before calling this */
1143        ret = -EPERM;
1144        instkey = cred->request_key_auth;
1145        if (!instkey)
1146                goto error;
1147
1148        rka = instkey->payload.data;
1149        if (rka->target_key->serial != id)
1150                goto error;
1151
1152        /* find the destination keyring if present (which must also be
1153         * writable) */
1154        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1155        if (ret < 0)
1156                goto error;
1157
1158        /* instantiate the key and link it into a keyring */
1159        ret = key_reject_and_link(rka->target_key, timeout, error,
1160                                  dest_keyring, instkey);
1161
1162        key_put(dest_keyring);
1163
1164        /* discard the assumed authority if it's just been disabled by
1165         * instantiation of the key */
1166        if (ret == 0)
1167                keyctl_change_reqkey_auth(NULL);
1168
1169error:
1170        return ret;
1171}
1172
1173/*
1174 * Read or set the default keyring in which request_key() will cache keys and
1175 * return the old setting.
1176 *
1177 * If a process keyring is specified then this will be created if it doesn't
1178 * yet exist.  The old setting will be returned if successful.
1179 */
1180long keyctl_set_reqkey_keyring(int reqkey_defl)
1181{
1182        struct cred *new;
1183        int ret, old_setting;
1184
1185        old_setting = current_cred_xxx(jit_keyring);
1186
1187        if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1188                return old_setting;
1189
1190        new = prepare_creds();
1191        if (!new)
1192                return -ENOMEM;
1193
1194        switch (reqkey_defl) {
1195        case KEY_REQKEY_DEFL_THREAD_KEYRING:
1196                ret = install_thread_keyring_to_cred(new);
1197                if (ret < 0)
1198                        goto error;
1199                goto set;
1200
1201        case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1202                ret = install_process_keyring_to_cred(new);
1203                if (ret < 0) {
1204                        if (ret != -EEXIST)
1205                                goto error;
1206                        ret = 0;
1207                }
1208                goto set;
1209
1210        case KEY_REQKEY_DEFL_DEFAULT:
1211        case KEY_REQKEY_DEFL_SESSION_KEYRING:
1212        case KEY_REQKEY_DEFL_USER_KEYRING:
1213        case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1214        case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1215                goto set;
1216
1217        case KEY_REQKEY_DEFL_NO_CHANGE:
1218        case KEY_REQKEY_DEFL_GROUP_KEYRING:
1219        default:
1220                ret = -EINVAL;
1221                goto error;
1222        }
1223
1224set:
1225        new->jit_keyring = reqkey_defl;
1226        commit_creds(new);
1227        return old_setting;
1228error:
1229        abort_creds(new);
1230        return ret;
1231}
1232
1233/*
1234 * Set or clear the timeout on a key.
1235 *
1236 * Either the key must grant the caller Setattr permission or else the caller
1237 * must hold an instantiation authorisation token for the key.
1238 *
1239 * The timeout is either 0 to clear the timeout, or a number of seconds from
1240 * the current time.  The key and any links to the key will be automatically
1241 * garbage collected after the timeout expires.
1242 *
1243 * If successful, 0 is returned.
1244 */
1245long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1246{
1247        struct timespec now;
1248        struct key *key, *instkey;
1249        key_ref_t key_ref;
1250        time_t expiry;
1251        long ret;
1252
1253        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1254                                  KEY_SETATTR);
1255        if (IS_ERR(key_ref)) {
1256                /* setting the timeout on a key under construction is permitted
1257                 * if we have the authorisation token handy */
1258                if (PTR_ERR(key_ref) == -EACCES) {
1259                        instkey = key_get_instantiation_authkey(id);
1260                        if (!IS_ERR(instkey)) {
1261                                key_put(instkey);
1262                                key_ref = lookup_user_key(id,
1263                                                          KEY_LOOKUP_PARTIAL,
1264                                                          0);
1265                                if (!IS_ERR(key_ref))
1266                                        goto okay;
1267                        }
1268                }
1269
1270                ret = PTR_ERR(key_ref);
1271                goto error;
1272        }
1273
1274okay:
1275        key = key_ref_to_ptr(key_ref);
1276
1277        /* make the changes with the locks held to prevent races */
1278        down_write(&key->sem);
1279
1280        expiry = 0;
1281        if (timeout > 0) {
1282                now = current_kernel_time();
1283                expiry = now.tv_sec + timeout;
1284        }
1285
1286        key->expiry = expiry;
1287        key_schedule_gc(key->expiry + key_gc_delay);
1288
1289        up_write(&key->sem);
1290        key_put(key);
1291
1292        ret = 0;
1293error:
1294        return ret;
1295}
1296
1297/*
1298 * Assume (or clear) the authority to instantiate the specified key.
1299 *
1300 * This sets the authoritative token currently in force for key instantiation.
1301 * This must be done for a key to be instantiated.  It has the effect of making
1302 * available all the keys from the caller of the request_key() that created a
1303 * key to request_key() calls made by the caller of this function.
1304 *
1305 * The caller must have the instantiation key in their process keyrings with a
1306 * Search permission grant available to the caller.
1307 *
1308 * If the ID given is 0, then the setting will be cleared and 0 returned.
1309 *
1310 * If the ID given has a matching an authorisation key, then that key will be
1311 * set and its ID will be returned.  The authorisation key can be read to get
1312 * the callout information passed to request_key().
1313 */
1314long keyctl_assume_authority(key_serial_t id)
1315{
1316        struct key *authkey;
1317        long ret;
1318
1319        /* special key IDs aren't permitted */
1320        ret = -EINVAL;
1321        if (id < 0)
1322                goto error;
1323
1324        /* we divest ourselves of authority if given an ID of 0 */
1325        if (id == 0) {
1326                ret = keyctl_change_reqkey_auth(NULL);
1327                goto error;
1328        }
1329
1330        /* attempt to assume the authority temporarily granted to us whilst we
1331         * instantiate the specified key
1332         * - the authorisation key must be in the current task's keyrings
1333         *   somewhere
1334         */
1335        authkey = key_get_instantiation_authkey(id);
1336        if (IS_ERR(authkey)) {
1337                ret = PTR_ERR(authkey);
1338                goto error;
1339        }
1340
1341        ret = keyctl_change_reqkey_auth(authkey);
1342        if (ret < 0)
1343                goto error;
1344        key_put(authkey);
1345
1346        ret = authkey->serial;
1347error:
1348        return ret;
1349}
1350
1351/*
1352 * Get a key's the LSM security label.
1353 *
1354 * The key must grant the caller View permission for this to work.
1355 *
1356 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1357 *
1358 * If successful, the amount of information available will be returned,
1359 * irrespective of how much was copied (including the terminal NUL).
1360 */
1361long keyctl_get_security(key_serial_t keyid,
1362                         char __user *buffer,
1363                         size_t buflen)
1364{
1365        struct key *key, *instkey;
1366        key_ref_t key_ref;
1367        char *context;
1368        long ret;
1369
1370        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1371        if (IS_ERR(key_ref)) {
1372                if (PTR_ERR(key_ref) != -EACCES)
1373                        return PTR_ERR(key_ref);
1374
1375                /* viewing a key under construction is also permitted if we
1376                 * have the authorisation token handy */
1377                instkey = key_get_instantiation_authkey(keyid);
1378                if (IS_ERR(instkey))
1379                        return PTR_ERR(instkey);
1380                key_put(instkey);
1381
1382                key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1383                if (IS_ERR(key_ref))
1384                        return PTR_ERR(key_ref);
1385        }
1386
1387        key = key_ref_to_ptr(key_ref);
1388        ret = security_key_getsecurity(key, &context);
1389        if (ret == 0) {
1390                /* if no information was returned, give userspace an empty
1391                 * string */
1392                ret = 1;
1393                if (buffer && buflen > 0 &&
1394                    copy_to_user(buffer, "", 1) != 0)
1395                        ret = -EFAULT;
1396        } else if (ret > 0) {
1397                /* return as much data as there's room for */
1398                if (buffer && buflen > 0) {
1399                        if (buflen > ret)
1400                                buflen = ret;
1401
1402                        if (copy_to_user(buffer, context, buflen) != 0)
1403                                ret = -EFAULT;
1404                }
1405
1406                kfree(context);
1407        }
1408
1409        key_ref_put(key_ref);
1410        return ret;
1411}
1412
1413/*
1414 * Attempt to install the calling process's session keyring on the process's
1415 * parent process.
1416 *
1417 * The keyring must exist and must grant the caller LINK permission, and the
1418 * parent process must be single-threaded and must have the same effective
1419 * ownership as this process and mustn't be SUID/SGID.
1420 *
1421 * The keyring will be emplaced on the parent when it next resumes userspace.
1422 *
1423 * If successful, 0 will be returned.
1424 */
1425long keyctl_session_to_parent(void)
1426{
1427#ifdef TIF_NOTIFY_RESUME
1428        struct task_struct *me, *parent;
1429        const struct cred *mycred, *pcred;
1430        struct cred *cred, *oldcred;
1431        key_ref_t keyring_r;
1432        int ret;
1433
1434        keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1435        if (IS_ERR(keyring_r))
1436                return PTR_ERR(keyring_r);
1437
1438        /* our parent is going to need a new cred struct, a new tgcred struct
1439         * and new security data, so we allocate them here to prevent ENOMEM in
1440         * our parent */
1441        ret = -ENOMEM;
1442        cred = cred_alloc_blank();
1443        if (!cred)
1444                goto error_keyring;
1445
1446        cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1447        keyring_r = NULL;
1448
1449        me = current;
1450        rcu_read_lock();
1451        write_lock_irq(&tasklist_lock);
1452
1453        parent = me->real_parent;
1454        ret = -EPERM;
1455
1456        /* the parent mustn't be init and mustn't be a kernel thread */
1457        if (parent->pid <= 1 || !parent->mm)
1458                goto not_permitted;
1459
1460        /* the parent must be single threaded */
1461        if (!thread_group_empty(parent))
1462                goto not_permitted;
1463
1464        /* the parent and the child must have different session keyrings or
1465         * there's no point */
1466        mycred = current_cred();
1467        pcred = __task_cred(parent);
1468        if (mycred == pcred ||
1469            mycred->tgcred->session_keyring == pcred->tgcred->session_keyring)
1470                goto already_same;
1471
1472        /* the parent must have the same effective ownership and mustn't be
1473         * SUID/SGID */
1474        if (pcred->uid  != mycred->euid ||
1475            pcred->euid != mycred->euid ||
1476            pcred->suid != mycred->euid ||
1477            pcred->gid  != mycred->egid ||
1478            pcred->egid != mycred->egid ||
1479            pcred->sgid != mycred->egid)
1480                goto not_permitted;
1481
1482        /* the keyrings must have the same UID */
1483        if ((pcred->tgcred->session_keyring &&
1484             pcred->tgcred->session_keyring->uid != mycred->euid) ||
1485            mycred->tgcred->session_keyring->uid != mycred->euid)
1486                goto not_permitted;
1487
1488        /* if there's an already pending keyring replacement, then we replace
1489         * that */
1490        oldcred = parent->replacement_session_keyring;
1491
1492        /* the replacement session keyring is applied just prior to userspace
1493         * restarting */
1494        parent->replacement_session_keyring = cred;
1495        cred = NULL;
1496        set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);
1497
1498        write_unlock_irq(&tasklist_lock);
1499        rcu_read_unlock();
1500        if (oldcred)
1501                put_cred(oldcred);
1502        return 0;
1503
1504already_same:
1505        ret = 0;
1506not_permitted:
1507        write_unlock_irq(&tasklist_lock);
1508        rcu_read_unlock();
1509        put_cred(cred);
1510        return ret;
1511
1512error_keyring:
1513        key_ref_put(keyring_r);
1514        return ret;
1515
1516#else /* !TIF_NOTIFY_RESUME */
1517        /*
1518         * To be removed when TIF_NOTIFY_RESUME has been implemented on
1519         * m68k/xtensa
1520         */
1521#warning TIF_NOTIFY_RESUME not implemented
1522        return -EOPNOTSUPP;
1523#endif /* !TIF_NOTIFY_RESUME */
1524}
1525
1526/*
1527 * The key control system call
1528 */
1529SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1530                unsigned long, arg4, unsigned long, arg5)
1531{
1532        switch (option) {
1533        case KEYCTL_GET_KEYRING_ID:
1534                return keyctl_get_keyring_ID((key_serial_t) arg2,
1535                                             (int) arg3);
1536
1537        case KEYCTL_JOIN_SESSION_KEYRING:
1538                return keyctl_join_session_keyring((const char __user *) arg2);
1539
1540        case KEYCTL_UPDATE:
1541                return keyctl_update_key((key_serial_t) arg2,
1542                                         (const void __user *) arg3,
1543                                         (size_t) arg4);
1544
1545        case KEYCTL_REVOKE:
1546                return keyctl_revoke_key((key_serial_t) arg2);
1547
1548        case KEYCTL_DESCRIBE:
1549                return keyctl_describe_key((key_serial_t) arg2,
1550                                           (char __user *) arg3,
1551                                           (unsigned) arg4);
1552
1553        case KEYCTL_CLEAR:
1554                return keyctl_keyring_clear((key_serial_t) arg2);
1555
1556        case KEYCTL_LINK:
1557                return keyctl_keyring_link((key_serial_t) arg2,
1558                                           (key_serial_t) arg3);
1559
1560        case KEYCTL_UNLINK:
1561                return keyctl_keyring_unlink((key_serial_t) arg2,
1562                                             (key_serial_t) arg3);
1563
1564        case KEYCTL_SEARCH:
1565                return keyctl_keyring_search((key_serial_t) arg2,
1566                                             (const char __user *) arg3,
1567                                             (const char __user *) arg4,
1568                                             (key_serial_t) arg5);
1569
1570        case KEYCTL_READ:
1571                return keyctl_read_key((key_serial_t) arg2,
1572                                       (char __user *) arg3,
1573                                       (size_t) arg4);
1574
1575        case KEYCTL_CHOWN:
1576                return keyctl_chown_key((key_serial_t) arg2,
1577                                        (uid_t) arg3,
1578                                        (gid_t) arg4);
1579
1580        case KEYCTL_SETPERM:
1581                return keyctl_setperm_key((key_serial_t) arg2,
1582                                          (key_perm_t) arg3);
1583
1584        case KEYCTL_INSTANTIATE:
1585                return keyctl_instantiate_key((key_serial_t) arg2,
1586                                              (const void __user *) arg3,
1587                                              (size_t) arg4,
1588                                              (key_serial_t) arg5);
1589
1590        case KEYCTL_NEGATE:
1591                return keyctl_negate_key((key_serial_t) arg2,
1592                                         (unsigned) arg3,
1593                                         (key_serial_t) arg4);
1594
1595        case KEYCTL_SET_REQKEY_KEYRING:
1596                return keyctl_set_reqkey_keyring(arg2);
1597
1598        case KEYCTL_SET_TIMEOUT:
1599                return keyctl_set_timeout((key_serial_t) arg2,
1600                                          (unsigned) arg3);
1601
1602        case KEYCTL_ASSUME_AUTHORITY:
1603                return keyctl_assume_authority((key_serial_t) arg2);
1604
1605        case KEYCTL_GET_SECURITY:
1606                return keyctl_get_security((key_serial_t) arg2,
1607                                           (char __user *) arg3,
1608                                           (size_t) arg4);
1609
1610        case KEYCTL_SESSION_TO_PARENT:
1611                return keyctl_session_to_parent();
1612
1613        case KEYCTL_REJECT:
1614                return keyctl_reject_key((key_serial_t) arg2,
1615                                         (unsigned) arg3,
1616                                         (unsigned) arg4,
1617                                         (key_serial_t) arg5);
1618
1619        case KEYCTL_INSTANTIATE_IOV:
1620                return keyctl_instantiate_key_iov(
1621                        (key_serial_t) arg2,
1622                        (const struct iovec __user *) arg3,
1623                        (unsigned) arg4,
1624                        (key_serial_t) arg5);
1625
1626        default:
1627                return -EOPNOTSUPP;
1628        }
1629}
1630