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/key.h>
  18#include <linux/keyctl.h>
  19#include <linux/fs.h>
  20#include <linux/capability.h>
  21#include <linux/string.h>
  22#include <linux/err.h>
  23#include <linux/vmalloc.h>
  24#include <linux/security.h>
  25#include <asm/uaccess.h>
  26#include "internal.h"
  27
  28static int key_get_type_from_user(char *type,
  29                                  const char __user *_type,
  30                                  unsigned len)
  31{
  32        int ret;
  33
  34        ret = strncpy_from_user(type, _type, len);
  35        if (ret < 0)
  36                return ret;
  37        if (ret == 0 || ret >= len)
  38                return -EINVAL;
  39        if (type[0] == '.')
  40                return -EPERM;
  41        type[len - 1] = '\0';
  42        return 0;
  43}
  44
  45/*
  46 * Extract the description of a new key from userspace and either add it as a
  47 * new key to the specified keyring or update a matching key in that keyring.
  48 *
  49 * The keyring must be writable so that we can attach the key to it.
  50 *
  51 * If successful, the new key's serial number is returned, otherwise an error
  52 * code is returned.
  53 */
  54SYSCALL_DEFINE5(add_key, const char __user *, _type,
  55                const char __user *, _description,
  56                const void __user *, _payload,
  57                size_t, plen,
  58                key_serial_t, ringid)
  59{
  60        key_ref_t keyring_ref, key_ref;
  61        char type[32], *description;
  62        void *payload;
  63        long ret;
  64        bool vm;
  65
  66        ret = -EINVAL;
  67        if (plen > 1024 * 1024 - 1)
  68                goto error;
  69
  70        /* draw all the data into kernel space */
  71        ret = key_get_type_from_user(type, _type, sizeof(type));
  72        if (ret < 0)
  73                goto error;
  74
  75        description = strndup_user(_description, PAGE_SIZE);
  76        if (IS_ERR(description)) {
  77                ret = PTR_ERR(description);
  78                goto error;
  79        }
  80
  81        /* pull the payload in if one was supplied */
  82        payload = NULL;
  83
  84        vm = false;
  85        if (_payload) {
  86                ret = -ENOMEM;
  87                payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
  88                if (!payload) {
  89                        if (plen <= PAGE_SIZE)
  90                                goto error2;
  91                        vm = true;
  92                        payload = vmalloc(plen);
  93                        if (!payload)
  94                                goto error2;
  95                }
  96
  97                ret = -EFAULT;
  98                if (copy_from_user(payload, _payload, plen) != 0)
  99                        goto error3;
 100        }
 101
 102        /* find the target keyring (which must be writable) */
 103        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 104        if (IS_ERR(keyring_ref)) {
 105                ret = PTR_ERR(keyring_ref);
 106                goto error3;
 107        }
 108
 109        /* create or update the requested key and add it to the target
 110         * keyring */
 111        key_ref = key_create_or_update(keyring_ref, type, description,
 112                                       payload, plen, KEY_PERM_UNDEF,
 113                                       KEY_ALLOC_IN_QUOTA);
 114        if (!IS_ERR(key_ref)) {
 115                ret = key_ref_to_ptr(key_ref)->serial;
 116                key_ref_put(key_ref);
 117        }
 118        else {
 119                ret = PTR_ERR(key_ref);
 120        }
 121
 122        key_ref_put(keyring_ref);
 123 error3:
 124        if (!vm)
 125                kfree(payload);
 126        else
 127                vfree(payload);
 128 error2:
 129        kfree(description);
 130 error:
 131        return ret;
 132}
 133
 134/*
 135 * Search the process keyrings and keyring trees linked from those for a
 136 * matching key.  Keyrings must have appropriate Search permission to be
 137 * searched.
 138 *
 139 * If a key is found, it will be attached to the destination keyring if there's
 140 * one specified and the serial number of the key will be returned.
 141 *
 142 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 143 * non-NULL in an attempt to create a key.  The _callout_info string will be
 144 * passed to /sbin/request-key to aid with completing the request.  If the
 145 * _callout_info string is "" then it will be changed to "-".
 146 */
 147SYSCALL_DEFINE4(request_key, const char __user *, _type,
 148                const char __user *, _description,
 149                const char __user *, _callout_info,
 150                key_serial_t, destringid)
 151{
 152        struct key_type *ktype;
 153        struct key *key;
 154        key_ref_t dest_ref;
 155        size_t callout_len;
 156        char type[32], *description, *callout_info;
 157        long ret;
 158
 159        /* pull the type into kernel space */
 160        ret = key_get_type_from_user(type, _type, sizeof(type));
 161        if (ret < 0)
 162                goto error;
 163
 164        /* pull the description into kernel space */
 165        description = strndup_user(_description, PAGE_SIZE);
 166        if (IS_ERR(description)) {
 167                ret = PTR_ERR(description);
 168                goto error;
 169        }
 170
 171        /* pull the callout info into kernel space */
 172        callout_info = NULL;
 173        callout_len = 0;
 174        if (_callout_info) {
 175                callout_info = strndup_user(_callout_info, PAGE_SIZE);
 176                if (IS_ERR(callout_info)) {
 177                        ret = PTR_ERR(callout_info);
 178                        goto error2;
 179                }
 180                callout_len = strlen(callout_info);
 181        }
 182
 183        /* get the destination keyring if specified */
 184        dest_ref = NULL;
 185        if (destringid) {
 186                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 187                                           KEY_WRITE);
 188                if (IS_ERR(dest_ref)) {
 189                        ret = PTR_ERR(dest_ref);
 190                        goto error3;
 191                }
 192        }
 193
 194        /* find the key type */
 195        ktype = key_type_lookup(type);
 196        if (IS_ERR(ktype)) {
 197                ret = PTR_ERR(ktype);
 198                goto error4;
 199        }
 200
 201        /* do the search */
 202        key = request_key_and_link(ktype, description, callout_info,
 203                                   callout_len, NULL, key_ref_to_ptr(dest_ref),
 204                                   KEY_ALLOC_IN_QUOTA);
 205        if (IS_ERR(key)) {
 206                ret = PTR_ERR(key);
 207                goto error5;
 208        }
 209
 210        /* wait for the key to finish being constructed */
 211        ret = wait_for_key_construction(key, 1);
 212        if (ret < 0)
 213                goto error6;
 214
 215        ret = key->serial;
 216
 217error6:
 218        key_put(key);
 219error5:
 220        key_type_put(ktype);
 221error4:
 222        key_ref_put(dest_ref);
 223error3:
 224        kfree(callout_info);
 225error2:
 226        kfree(description);
 227error:
 228        return ret;
 229}
 230
 231/*
 232 * Get the ID of the specified process keyring.
 233 *
 234 * The requested keyring must have search permission to be found.
 235 *
 236 * If successful, the ID of the requested keyring will be returned.
 237 */
 238long keyctl_get_keyring_ID(key_serial_t id, int create)
 239{
 240        key_ref_t key_ref;
 241        unsigned long lflags;
 242        long ret;
 243
 244        lflags = create ? KEY_LOOKUP_CREATE : 0;
 245        key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 246        if (IS_ERR(key_ref)) {
 247                ret = PTR_ERR(key_ref);
 248                goto error;
 249        }
 250
 251        ret = key_ref_to_ptr(key_ref)->serial;
 252        key_ref_put(key_ref);
 253error:
 254        return ret;
 255}
 256
 257/*
 258 * Join a (named) session keyring.
 259 *
 260 * Create and join an anonymous session keyring or join a named session
 261 * keyring, creating it if necessary.  A named session keyring must have Search
 262 * permission for it to be joined.  Session keyrings without this permit will
 263 * be skipped over.
 264 *
 265 * If successful, the ID of the joined session keyring will be returned.
 266 */
 267long keyctl_join_session_keyring(const char __user *_name)
 268{
 269        char *name;
 270        long ret;
 271
 272        /* fetch the name from userspace */
 273        name = NULL;
 274        if (_name) {
 275                name = strndup_user(_name, PAGE_SIZE);
 276                if (IS_ERR(name)) {
 277                        ret = PTR_ERR(name);
 278                        goto error;
 279                }
 280        }
 281
 282        /* join the session */
 283        ret = join_session_keyring(name);
 284        kfree(name);
 285
 286error:
 287        return ret;
 288}
 289
 290/*
 291 * Update a key's data payload from the given data.
 292 *
 293 * The key must grant the caller Write permission and the key type must support
 294 * updating for this to work.  A negative key can be positively instantiated
 295 * with this call.
 296 *
 297 * If successful, 0 will be returned.  If the key type does not support
 298 * updating, then -EOPNOTSUPP will be returned.
 299 */
 300long keyctl_update_key(key_serial_t id,
 301                       const void __user *_payload,
 302                       size_t plen)
 303{
 304        key_ref_t key_ref;
 305        void *payload;
 306        long ret;
 307
 308        ret = -EINVAL;
 309        if (plen > PAGE_SIZE)
 310                goto error;
 311
 312        /* pull the payload in if one was supplied */
 313        payload = NULL;
 314        if (_payload) {
 315                ret = -ENOMEM;
 316                payload = kmalloc(plen, GFP_KERNEL);
 317                if (!payload)
 318                        goto error;
 319
 320                ret = -EFAULT;
 321                if (copy_from_user(payload, _payload, plen) != 0)
 322                        goto error2;
 323        }
 324
 325        /* find the target key (which must be writable) */
 326        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 327        if (IS_ERR(key_ref)) {
 328                ret = PTR_ERR(key_ref);
 329                goto error2;
 330        }
 331
 332        /* update the key */
 333        ret = key_update(key_ref, payload, plen);
 334
 335        key_ref_put(key_ref);
 336error2:
 337        kfree(payload);
 338error:
 339        return ret;
 340}
 341
 342/*
 343 * Revoke a key.
 344 *
 345 * The key must be grant the caller Write or Setattr permission for this to
 346 * work.  The key type should give up its quota claim when revoked.  The key
 347 * and any links to the key will be automatically garbage collected after a
 348 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 349 *
 350 * If successful, 0 is returned.
 351 */
 352long keyctl_revoke_key(key_serial_t id)
 353{
 354        key_ref_t key_ref;
 355        long ret;
 356
 357        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 358        if (IS_ERR(key_ref)) {
 359                ret = PTR_ERR(key_ref);
 360                if (ret != -EACCES)
 361                        goto error;
 362                key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 363                if (IS_ERR(key_ref)) {
 364                        ret = PTR_ERR(key_ref);
 365                        goto error;
 366                }
 367        }
 368
 369        key_revoke(key_ref_to_ptr(key_ref));
 370        ret = 0;
 371
 372        key_ref_put(key_ref);
 373error:
 374        return ret;
 375}
 376
 377/*
 378 * Invalidate a key.
 379 *
 380 * The key must be grant the caller Invalidate permission for this to work.
 381 * The key and any links to the key will be automatically garbage collected
 382 * immediately.
 383 *
 384 * If successful, 0 is returned.
 385 */
 386long keyctl_invalidate_key(key_serial_t id)
 387{
 388        key_ref_t key_ref;
 389        long ret;
 390
 391        kenter("%d", id);
 392
 393        key_ref = lookup_user_key(id, 0, KEY_SEARCH);
 394        if (IS_ERR(key_ref)) {
 395                ret = PTR_ERR(key_ref);
 396                goto error;
 397        }
 398
 399        key_invalidate(key_ref_to_ptr(key_ref));
 400        ret = 0;
 401
 402        key_ref_put(key_ref);
 403error:
 404        kleave(" = %ld", ret);
 405        return ret;
 406}
 407
 408/*
 409 * Clear the specified keyring, creating an empty process keyring if one of the
 410 * special keyring IDs is used.
 411 *
 412 * The keyring must grant the caller Write permission for this to work.  If
 413 * successful, 0 will be returned.
 414 */
 415long keyctl_keyring_clear(key_serial_t ringid)
 416{
 417        key_ref_t keyring_ref;
 418        long ret;
 419
 420        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 421        if (IS_ERR(keyring_ref)) {
 422                ret = PTR_ERR(keyring_ref);
 423
 424                /* Root is permitted to invalidate certain special keyrings */
 425                if (capable(CAP_SYS_ADMIN)) {
 426                        keyring_ref = lookup_user_key(ringid, 0, 0);
 427                        if (IS_ERR(keyring_ref))
 428                                goto error;
 429                        if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 430                                     &key_ref_to_ptr(keyring_ref)->flags))
 431                                goto clear;
 432                        goto error_put;
 433                }
 434
 435                goto error;
 436        }
 437
 438clear:
 439        ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 440error_put:
 441        key_ref_put(keyring_ref);
 442error:
 443        return ret;
 444}
 445
 446/*
 447 * Create a link from a keyring to a key if there's no matching key in the
 448 * keyring, otherwise replace the link to the matching key with a link to the
 449 * new key.
 450 *
 451 * The key must grant the caller Link permission and the the keyring must grant
 452 * the caller Write permission.  Furthermore, if an additional link is created,
 453 * the keyring's quota will be extended.
 454 *
 455 * If successful, 0 will be returned.
 456 */
 457long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 458{
 459        key_ref_t keyring_ref, key_ref;
 460        long ret;
 461
 462        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 463        if (IS_ERR(keyring_ref)) {
 464                ret = PTR_ERR(keyring_ref);
 465                goto error;
 466        }
 467
 468        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 469        if (IS_ERR(key_ref)) {
 470                ret = PTR_ERR(key_ref);
 471                goto error2;
 472        }
 473
 474        ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 475
 476        key_ref_put(key_ref);
 477error2:
 478        key_ref_put(keyring_ref);
 479error:
 480        return ret;
 481}
 482
 483/*
 484 * Unlink a key from a keyring.
 485 *
 486 * The keyring must grant the caller Write permission for this to work; the key
 487 * itself need not grant the caller anything.  If the last link to a key is
 488 * removed then that key will be scheduled for destruction.
 489 *
 490 * If successful, 0 will be returned.
 491 */
 492long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 493{
 494        key_ref_t keyring_ref, key_ref;
 495        long ret;
 496
 497        keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 498        if (IS_ERR(keyring_ref)) {
 499                ret = PTR_ERR(keyring_ref);
 500                goto error;
 501        }
 502
 503        key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 504        if (IS_ERR(key_ref)) {
 505                ret = PTR_ERR(key_ref);
 506                goto error2;
 507        }
 508
 509        ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 510
 511        key_ref_put(key_ref);
 512error2:
 513        key_ref_put(keyring_ref);
 514error:
 515        return ret;
 516}
 517
 518/*
 519 * Return a description of a key to userspace.
 520 *
 521 * The key must grant the caller View permission for this to work.
 522 *
 523 * If there's a buffer, we place up to buflen bytes of data into it formatted
 524 * in the following way:
 525 *
 526 *      type;uid;gid;perm;description<NUL>
 527 *
 528 * If successful, we return the amount of description available, irrespective
 529 * of how much we may have copied into the buffer.
 530 */
 531long keyctl_describe_key(key_serial_t keyid,
 532                         char __user *buffer,
 533                         size_t buflen)
 534{
 535        struct key *key, *instkey;
 536        key_ref_t key_ref;
 537        char *tmpbuf;
 538        long ret;
 539
 540        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 541        if (IS_ERR(key_ref)) {
 542                /* viewing a key under construction is permitted if we have the
 543                 * authorisation token handy */
 544                if (PTR_ERR(key_ref) == -EACCES) {
 545                        instkey = key_get_instantiation_authkey(keyid);
 546                        if (!IS_ERR(instkey)) {
 547                                key_put(instkey);
 548                                key_ref = lookup_user_key(keyid,
 549                                                          KEY_LOOKUP_PARTIAL,
 550                                                          0);
 551                                if (!IS_ERR(key_ref))
 552                                        goto okay;
 553                        }
 554                }
 555
 556                ret = PTR_ERR(key_ref);
 557                goto error;
 558        }
 559
 560okay:
 561        /* calculate how much description we're going to return */
 562        ret = -ENOMEM;
 563        tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 564        if (!tmpbuf)
 565                goto error2;
 566
 567        key = key_ref_to_ptr(key_ref);
 568
 569        ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 570                       "%s;%d;%d;%08x;%s",
 571                       key->type->name,
 572                       key->uid,
 573                       key->gid,
 574                       key->perm,
 575                       key->description ?: "");
 576
 577        /* include a NUL char at the end of the data */
 578        if (ret > PAGE_SIZE - 1)
 579                ret = PAGE_SIZE - 1;
 580        tmpbuf[ret] = 0;
 581        ret++;
 582
 583        /* consider returning the data */
 584        if (buffer && buflen > 0) {
 585                if (buflen > ret)
 586                        buflen = ret;
 587
 588                if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 589                        ret = -EFAULT;
 590        }
 591
 592        kfree(tmpbuf);
 593error2:
 594        key_ref_put(key_ref);
 595error:
 596        return ret;
 597}
 598
 599/*
 600 * Search the specified keyring and any keyrings it links to for a matching
 601 * key.  Only keyrings that grant the caller Search permission will be searched
 602 * (this includes the starting keyring).  Only keys with Search permission can
 603 * be found.
 604 *
 605 * If successful, the found key will be linked to the destination keyring if
 606 * supplied and the key has Link permission, and the found key ID will be
 607 * returned.
 608 */
 609long keyctl_keyring_search(key_serial_t ringid,
 610                           const char __user *_type,
 611                           const char __user *_description,
 612                           key_serial_t destringid)
 613{
 614        struct key_type *ktype;
 615        key_ref_t keyring_ref, key_ref, dest_ref;
 616        char type[32], *description;
 617        long ret;
 618
 619        /* pull the type and description into kernel space */
 620        ret = key_get_type_from_user(type, _type, sizeof(type));
 621        if (ret < 0)
 622                goto error;
 623
 624        description = strndup_user(_description, PAGE_SIZE);
 625        if (IS_ERR(description)) {
 626                ret = PTR_ERR(description);
 627                goto error;
 628        }
 629
 630        /* get the keyring at which to begin the search */
 631        keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 632        if (IS_ERR(keyring_ref)) {
 633                ret = PTR_ERR(keyring_ref);
 634                goto error2;
 635        }
 636
 637        /* get the destination keyring if specified */
 638        dest_ref = NULL;
 639        if (destringid) {
 640                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 641                                           KEY_WRITE);
 642                if (IS_ERR(dest_ref)) {
 643                        ret = PTR_ERR(dest_ref);
 644                        goto error3;
 645                }
 646        }
 647
 648        /* find the key type */
 649        ktype = key_type_lookup(type);
 650        if (IS_ERR(ktype)) {
 651                ret = PTR_ERR(ktype);
 652                goto error4;
 653        }
 654
 655        /* do the search */
 656        key_ref = keyring_search(keyring_ref, ktype, description);
 657        if (IS_ERR(key_ref)) {
 658                ret = PTR_ERR(key_ref);
 659
 660                /* treat lack or presence of a negative key the same */
 661                if (ret == -EAGAIN)
 662                        ret = -ENOKEY;
 663                goto error5;
 664        }
 665
 666        /* link the resulting key to the destination keyring if we can */
 667        if (dest_ref) {
 668                ret = key_permission(key_ref, KEY_LINK);
 669                if (ret < 0)
 670                        goto error6;
 671
 672                ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 673                if (ret < 0)
 674                        goto error6;
 675        }
 676
 677        ret = key_ref_to_ptr(key_ref)->serial;
 678
 679error6:
 680        key_ref_put(key_ref);
 681error5:
 682        key_type_put(ktype);
 683error4:
 684        key_ref_put(dest_ref);
 685error3:
 686        key_ref_put(keyring_ref);
 687error2:
 688        kfree(description);
 689error:
 690        return ret;
 691}
 692
 693/*
 694 * Read a key's payload.
 695 *
 696 * The key must either grant the caller Read permission, or it must grant the
 697 * caller Search permission when searched for from the process keyrings.
 698 *
 699 * If successful, we place up to buflen bytes of data into the buffer, if one
 700 * is provided, and return the amount of data that is available in the key,
 701 * irrespective of how much we copied into the buffer.
 702 */
 703long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 704{
 705        struct key *key;
 706        key_ref_t key_ref;
 707        long ret;
 708
 709        /* find the key first */
 710        key_ref = lookup_user_key(keyid, 0, 0);
 711        if (IS_ERR(key_ref)) {
 712                ret = -ENOKEY;
 713                goto error;
 714        }
 715
 716        key = key_ref_to_ptr(key_ref);
 717
 718        /* see if we can read it directly */
 719        ret = key_permission(key_ref, KEY_READ);
 720        if (ret == 0)
 721                goto can_read_key;
 722        if (ret != -EACCES)
 723                goto error;
 724
 725        /* we can't; see if it's searchable from this process's keyrings
 726         * - we automatically take account of the fact that it may be
 727         *   dangling off an instantiation key
 728         */
 729        if (!is_key_possessed(key_ref)) {
 730                ret = -EACCES;
 731                goto error2;
 732        }
 733
 734        /* the key is probably readable - now try to read it */
 735can_read_key:
 736        ret = key_validate(key);
 737        if (ret == 0) {
 738                ret = -EOPNOTSUPP;
 739                if (key->type->read) {
 740                        /* read the data with the semaphore held (since we
 741                         * might sleep) */
 742                        down_read(&key->sem);
 743                        ret = key->type->read(key, buffer, buflen);
 744                        up_read(&key->sem);
 745                }
 746        }
 747
 748error2:
 749        key_put(key);
 750error:
 751        return ret;
 752}
 753
 754/*
 755 * Change the ownership of a key
 756 *
 757 * The key must grant the caller Setattr permission for this to work, though
 758 * the key need not be fully instantiated yet.  For the UID to be changed, or
 759 * for the GID to be changed to a group the caller is not a member of, the
 760 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 761 * attribute is not changed.
 762 *
 763 * If the UID is to be changed, the new user must have sufficient quota to
 764 * accept the key.  The quota deduction will be removed from the old user to
 765 * the new user should the attribute be changed.
 766 *
 767 * If successful, 0 will be returned.
 768 */
 769long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 770{
 771        struct key_user *newowner, *zapowner = NULL;
 772        struct key *key;
 773        key_ref_t key_ref;
 774        long ret;
 775
 776        ret = 0;
 777        if (uid == (uid_t) -1 && gid == (gid_t) -1)
 778                goto error;
 779
 780        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 781                                  KEY_SETATTR);
 782        if (IS_ERR(key_ref)) {
 783                ret = PTR_ERR(key_ref);
 784                goto error;
 785        }
 786
 787        key = key_ref_to_ptr(key_ref);
 788
 789        /* make the changes with the locks held to prevent chown/chown races */
 790        ret = -EACCES;
 791        down_write(&key->sem);
 792
 793        if (!capable(CAP_SYS_ADMIN)) {
 794                /* only the sysadmin can chown a key to some other UID */
 795                if (uid != (uid_t) -1 && key->uid != uid)
 796                        goto error_put;
 797
 798                /* only the sysadmin can set the key's GID to a group other
 799                 * than one of those that the current process subscribes to */
 800                if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 801                        goto error_put;
 802        }
 803
 804        /* change the UID */
 805        if (uid != (uid_t) -1 && uid != key->uid) {
 806                ret = -ENOMEM;
 807                newowner = key_user_lookup(uid, current_user_ns());
 808                if (!newowner)
 809                        goto error_put;
 810
 811                /* transfer the quota burden to the new user */
 812                if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 813                        unsigned maxkeys = (uid == 0) ?
 814                                key_quota_root_maxkeys : key_quota_maxkeys;
 815                        unsigned maxbytes = (uid == 0) ?
 816                                key_quota_root_maxbytes : key_quota_maxbytes;
 817
 818                        spin_lock(&newowner->lock);
 819                        if (newowner->qnkeys + 1 >= maxkeys ||
 820                            newowner->qnbytes + key->quotalen >= maxbytes ||
 821                            newowner->qnbytes + key->quotalen <
 822                            newowner->qnbytes)
 823                                goto quota_overrun;
 824
 825                        newowner->qnkeys++;
 826                        newowner->qnbytes += key->quotalen;
 827                        spin_unlock(&newowner->lock);
 828
 829                        spin_lock(&key->user->lock);
 830                        key->user->qnkeys--;
 831                        key->user->qnbytes -= key->quotalen;
 832                        spin_unlock(&key->user->lock);
 833                }
 834
 835                atomic_dec(&key->user->nkeys);
 836                atomic_inc(&newowner->nkeys);
 837
 838                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 839                        atomic_dec(&key->user->nikeys);
 840                        atomic_inc(&newowner->nikeys);
 841                }
 842
 843                zapowner = key->user;
 844                key->user = newowner;
 845                key->uid = uid;
 846        }
 847
 848        /* change the GID */
 849        if (gid != (gid_t) -1)
 850                key->gid = gid;
 851
 852        ret = 0;
 853
 854error_put:
 855        up_write(&key->sem);
 856        key_put(key);
 857        if (zapowner)
 858                key_user_put(zapowner);
 859error:
 860        return ret;
 861
 862quota_overrun:
 863        spin_unlock(&newowner->lock);
 864        zapowner = newowner;
 865        ret = -EDQUOT;
 866        goto error_put;
 867}
 868
 869/*
 870 * Change the permission mask on a key.
 871 *
 872 * The key must grant the caller Setattr permission for this to work, though
 873 * the key need not be fully instantiated yet.  If the caller does not have
 874 * sysadmin capability, it may only change the permission on keys that it owns.
 875 */
 876long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 877{
 878        struct key *key;
 879        key_ref_t key_ref;
 880        long ret;
 881
 882        ret = -EINVAL;
 883        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 884                goto error;
 885
 886        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 887                                  KEY_SETATTR);
 888        if (IS_ERR(key_ref)) {
 889                ret = PTR_ERR(key_ref);
 890                goto error;
 891        }
 892
 893        key = key_ref_to_ptr(key_ref);
 894
 895        /* make the changes with the locks held to prevent chown/chmod races */
 896        ret = -EACCES;
 897        down_write(&key->sem);
 898
 899        /* if we're not the sysadmin, we can only change a key that we own */
 900        if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 901                key->perm = perm;
 902                ret = 0;
 903        }
 904
 905        up_write(&key->sem);
 906        key_put(key);
 907error:
 908        return ret;
 909}
 910
 911/*
 912 * Get the destination keyring for instantiation and check that the caller has
 913 * Write permission on it.
 914 */
 915static long get_instantiation_keyring(key_serial_t ringid,
 916                                      struct request_key_auth *rka,
 917                                      struct key **_dest_keyring)
 918{
 919        key_ref_t dkref;
 920
 921        *_dest_keyring = NULL;
 922
 923        /* just return a NULL pointer if we weren't asked to make a link */
 924        if (ringid == 0)
 925                return 0;
 926
 927        /* if a specific keyring is nominated by ID, then use that */
 928        if (ringid > 0) {
 929                dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 930                if (IS_ERR(dkref))
 931                        return PTR_ERR(dkref);
 932                *_dest_keyring = key_ref_to_ptr(dkref);
 933                return 0;
 934        }
 935
 936        if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 937                return -EINVAL;
 938
 939        /* otherwise specify the destination keyring recorded in the
 940         * authorisation key (any KEY_SPEC_*_KEYRING) */
 941        if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 942                *_dest_keyring = key_get(rka->dest_keyring);
 943                return 0;
 944        }
 945
 946        return -ENOKEY;
 947}
 948
 949/*
 950 * Change the request_key authorisation key on the current process.
 951 */
 952static int keyctl_change_reqkey_auth(struct key *key)
 953{
 954        struct cred *new;
 955
 956        new = prepare_creds();
 957        if (!new)
 958                return -ENOMEM;
 959
 960        key_put(new->request_key_auth);
 961        new->request_key_auth = key_get(key);
 962
 963        return commit_creds(new);
 964}
 965
 966/*
 967 * Copy the iovec data from userspace
 968 */
 969static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
 970                                 unsigned ioc)
 971{
 972        for (; ioc > 0; ioc--) {
 973                if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
 974                        return -EFAULT;
 975                buffer += iov->iov_len;
 976                iov++;
 977        }
 978        return 0;
 979}
 980
 981/*
 982 * Instantiate a key with the specified payload and link the key into the
 983 * destination keyring if one is given.
 984 *
 985 * The caller must have the appropriate instantiation permit set for this to
 986 * work (see keyctl_assume_authority).  No other permissions are required.
 987 *
 988 * If successful, 0 will be returned.
 989 */
 990long keyctl_instantiate_key_common(key_serial_t id,
 991                                   const struct iovec *payload_iov,
 992                                   unsigned ioc,
 993                                   size_t plen,
 994                                   key_serial_t ringid)
 995{
 996        const struct cred *cred = current_cred();
 997        struct request_key_auth *rka;
 998        struct key *instkey, *dest_keyring;
 999        void *payload;
1000        long ret;
1001        bool vm = false;
1002
1003        kenter("%d,,%zu,%d", id, plen, ringid);
1004
1005        ret = -EINVAL;
1006        if (plen > 1024 * 1024 - 1)
1007                goto error;
1008
1009        /* the appropriate instantiation authorisation key must have been
1010         * assumed before calling this */
1011        ret = -EPERM;
1012        instkey = cred->request_key_auth;
1013        if (!instkey)
1014                goto error;
1015
1016        rka = instkey->payload.data;
1017        if (rka->target_key->serial != id)
1018                goto error;
1019
1020        /* pull the payload in if one was supplied */
1021        payload = NULL;
1022
1023        if (payload_iov) {
1024                ret = -ENOMEM;
1025                payload = kmalloc(plen, GFP_KERNEL);
1026                if (!payload) {
1027                        if (plen <= PAGE_SIZE)
1028                                goto error;
1029                        vm = true;
1030                        payload = vmalloc(plen);
1031                        if (!payload)
1032                                goto error;
1033                }
1034
1035                ret = copy_from_user_iovec(payload, payload_iov, ioc);
1036                if (ret < 0)
1037                        goto error2;
1038        }
1039
1040        /* find the destination keyring amongst those belonging to the
1041         * requesting task */
1042        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1043        if (ret < 0)
1044                goto error2;
1045
1046        /* instantiate the key and link it into a keyring */
1047        ret = key_instantiate_and_link(rka->target_key, payload, plen,
1048                                       dest_keyring, instkey);
1049
1050        key_put(dest_keyring);
1051
1052        /* discard the assumed authority if it's just been disabled by
1053         * instantiation of the key */
1054        if (ret == 0)
1055                keyctl_change_reqkey_auth(NULL);
1056
1057error2:
1058        if (!vm)
1059                kfree(payload);
1060        else
1061                vfree(payload);
1062error:
1063        return ret;
1064}
1065
1066/*
1067 * Instantiate a key with the specified payload and link the key into the
1068 * destination keyring if one is given.
1069 *
1070 * The caller must have the appropriate instantiation permit set for this to
1071 * work (see keyctl_assume_authority).  No other permissions are required.
1072 *
1073 * If successful, 0 will be returned.
1074 */
1075long keyctl_instantiate_key(key_serial_t id,
1076                            const void __user *_payload,
1077                            size_t plen,
1078                            key_serial_t ringid)
1079{
1080        if (_payload && plen) {
1081                struct iovec iov[1] = {
1082                        [0].iov_base = (void __user *)_payload,
1083                        [0].iov_len  = plen
1084                };
1085
1086                return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1087        }
1088
1089        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1090}
1091
1092/*
1093 * Instantiate a key with the specified multipart payload and link the key into
1094 * the destination keyring if one is given.
1095 *
1096 * The caller must have the appropriate instantiation permit set for this to
1097 * work (see keyctl_assume_authority).  No other permissions are required.
1098 *
1099 * If successful, 0 will be returned.
1100 */
1101long keyctl_instantiate_key_iov(key_serial_t id,
1102                                const struct iovec __user *_payload_iov,
1103                                unsigned ioc,
1104                                key_serial_t ringid)
1105{
1106        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1107        long ret;
1108
1109        if (!_payload_iov || !ioc)
1110                goto no_payload;
1111
1112        ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1113                                    ARRAY_SIZE(iovstack), iovstack, &iov);
1114        if (ret < 0)
1115                return ret;
1116        if (ret == 0)
1117                goto no_payload_free;
1118
1119        ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1120
1121        if (iov != iovstack)
1122                kfree(iov);
1123        return ret;
1124
1125no_payload_free:
1126        if (iov != iovstack)
1127                kfree(iov);
1128no_payload:
1129        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1130}
1131
1132/*
1133 * Negatively instantiate the key with the given timeout (in seconds) and link
1134 * the key into the destination keyring if one is given.
1135 *
1136 * The caller must have the appropriate instantiation permit set for this to
1137 * work (see keyctl_assume_authority).  No other permissions are required.
1138 *
1139 * The key and any links to the key will be automatically garbage collected
1140 * after the timeout expires.
1141 *
1142 * Negative keys are used to rate limit repeated request_key() calls by causing
1143 * them to return -ENOKEY until the negative key expires.
1144 *
1145 * If successful, 0 will be returned.
1146 */
1147long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1148{
1149        return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1150}
1151
1152/*
1153 * Negatively instantiate the key with the given timeout (in seconds) and error
1154 * code and link the key into the destination keyring if one is given.
1155 *
1156 * The caller must have the appropriate instantiation permit set for this to
1157 * work (see keyctl_assume_authority).  No other permissions are required.
1158 *
1159 * The key and any links to the key will be automatically garbage collected
1160 * after the timeout expires.
1161 *
1162 * Negative keys are used to rate limit repeated request_key() calls by causing
1163 * them to return the specified error code until the negative key expires.
1164 *
1165 * If successful, 0 will be returned.
1166 */
1167long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1168                       key_serial_t ringid)
1169{
1170        const struct cred *cred = current_cred();
1171        struct request_key_auth *rka;
1172        struct key *instkey, *dest_keyring;
1173        long ret;
1174
1175        kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1176
1177        /* must be a valid error code and mustn't be a kernel special */
1178        if (error <= 0 ||
1179            error >= MAX_ERRNO ||
1180            error == ERESTARTSYS ||
1181            error == ERESTARTNOINTR ||
1182            error == ERESTARTNOHAND ||
1183            error == ERESTART_RESTARTBLOCK)
1184                return -EINVAL;
1185
1186        /* the appropriate instantiation authorisation key must have been
1187         * assumed before calling this */
1188        ret = -EPERM;
1189        instkey = cred->request_key_auth;
1190        if (!instkey)
1191                goto error;
1192
1193        rka = instkey->payload.data;
1194        if (rka->target_key->serial != id)
1195                goto error;
1196
1197        /* find the destination keyring if present (which must also be
1198         * writable) */
1199        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1200        if (ret < 0)
1201                goto error;
1202
1203        /* instantiate the key and link it into a keyring */
1204        ret = key_reject_and_link(rka->target_key, timeout, error,
1205                                  dest_keyring, instkey);
1206
1207        key_put(dest_keyring);
1208
1209        /* discard the assumed authority if it's just been disabled by
1210         * instantiation of the key */
1211        if (ret == 0)
1212                keyctl_change_reqkey_auth(NULL);
1213
1214error:
1215        return ret;
1216}
1217
1218/*
1219 * Read or set the default keyring in which request_key() will cache keys and
1220 * return the old setting.
1221 *
1222 * If a process keyring is specified then this will be created if it doesn't
1223 * yet exist.  The old setting will be returned if successful.
1224 */
1225long keyctl_set_reqkey_keyring(int reqkey_defl)
1226{
1227        struct cred *new;
1228        int ret, old_setting;
1229
1230        old_setting = current_cred_xxx(jit_keyring);
1231
1232        if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1233                return old_setting;
1234
1235        new = prepare_creds();
1236        if (!new)
1237                return -ENOMEM;
1238
1239        switch (reqkey_defl) {
1240        case KEY_REQKEY_DEFL_THREAD_KEYRING:
1241                ret = install_thread_keyring_to_cred(new);
1242                if (ret < 0)
1243                        goto error;
1244                goto set;
1245
1246        case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1247                ret = install_process_keyring_to_cred(new);
1248                if (ret < 0) {
1249                        if (ret != -EEXIST)
1250                                goto error;
1251                        ret = 0;
1252                }
1253                goto set;
1254
1255        case KEY_REQKEY_DEFL_DEFAULT:
1256        case KEY_REQKEY_DEFL_SESSION_KEYRING:
1257        case KEY_REQKEY_DEFL_USER_KEYRING:
1258        case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1259        case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1260                goto set;
1261
1262        case KEY_REQKEY_DEFL_NO_CHANGE:
1263        case KEY_REQKEY_DEFL_GROUP_KEYRING:
1264        default:
1265                ret = -EINVAL;
1266                goto error;
1267        }
1268
1269set:
1270        new->jit_keyring = reqkey_defl;
1271        commit_creds(new);
1272        return old_setting;
1273error:
1274        abort_creds(new);
1275        return ret;
1276}
1277
1278/*
1279 * Set or clear the timeout on a key.
1280 *
1281 * Either the key must grant the caller Setattr permission or else the caller
1282 * must hold an instantiation authorisation token for the key.
1283 *
1284 * The timeout is either 0 to clear the timeout, or a number of seconds from
1285 * the current time.  The key and any links to the key will be automatically
1286 * garbage collected after the timeout expires.
1287 *
1288 * If successful, 0 is returned.
1289 */
1290long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1291{
1292        struct key *key, *instkey;
1293        key_ref_t key_ref;
1294        long ret;
1295
1296        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1297                                  KEY_SETATTR);
1298        if (IS_ERR(key_ref)) {
1299                /* setting the timeout on a key under construction is permitted
1300                 * if we have the authorisation token handy */
1301                if (PTR_ERR(key_ref) == -EACCES) {
1302                        instkey = key_get_instantiation_authkey(id);
1303                        if (!IS_ERR(instkey)) {
1304                                key_put(instkey);
1305                                key_ref = lookup_user_key(id,
1306                                                          KEY_LOOKUP_PARTIAL,
1307                                                          0);
1308                                if (!IS_ERR(key_ref))
1309                                        goto okay;
1310                        }
1311                }
1312
1313                ret = PTR_ERR(key_ref);
1314                goto error;
1315        }
1316
1317okay:
1318        key = key_ref_to_ptr(key_ref);
1319        key_set_timeout(key, timeout);
1320        key_put(key);
1321
1322        ret = 0;
1323error:
1324        return ret;
1325}
1326
1327/*
1328 * Assume (or clear) the authority to instantiate the specified key.
1329 *
1330 * This sets the authoritative token currently in force for key instantiation.
1331 * This must be done for a key to be instantiated.  It has the effect of making
1332 * available all the keys from the caller of the request_key() that created a
1333 * key to request_key() calls made by the caller of this function.
1334 *
1335 * The caller must have the instantiation key in their process keyrings with a
1336 * Search permission grant available to the caller.
1337 *
1338 * If the ID given is 0, then the setting will be cleared and 0 returned.
1339 *
1340 * If the ID given has a matching an authorisation key, then that key will be
1341 * set and its ID will be returned.  The authorisation key can be read to get
1342 * the callout information passed to request_key().
1343 */
1344long keyctl_assume_authority(key_serial_t id)
1345{
1346        struct key *authkey;
1347        long ret;
1348
1349        /* special key IDs aren't permitted */
1350        ret = -EINVAL;
1351        if (id < 0)
1352                goto error;
1353
1354        /* we divest ourselves of authority if given an ID of 0 */
1355        if (id == 0) {
1356                ret = keyctl_change_reqkey_auth(NULL);
1357                goto error;
1358        }
1359
1360        /* attempt to assume the authority temporarily granted to us whilst we
1361         * instantiate the specified key
1362         * - the authorisation key must be in the current task's keyrings
1363         *   somewhere
1364         */
1365        authkey = key_get_instantiation_authkey(id);
1366        if (IS_ERR(authkey)) {
1367                ret = PTR_ERR(authkey);
1368                goto error;
1369        }
1370
1371        ret = keyctl_change_reqkey_auth(authkey);
1372        if (ret < 0)
1373                goto error;
1374        key_put(authkey);
1375
1376        ret = authkey->serial;
1377error:
1378        return ret;
1379}
1380
1381/*
1382 * Get a key's the LSM security label.
1383 *
1384 * The key must grant the caller View permission for this to work.
1385 *
1386 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1387 *
1388 * If successful, the amount of information available will be returned,
1389 * irrespective of how much was copied (including the terminal NUL).
1390 */
1391long keyctl_get_security(key_serial_t keyid,
1392                         char __user *buffer,
1393                         size_t buflen)
1394{
1395        struct key *key, *instkey;
1396        key_ref_t key_ref;
1397        char *context;
1398        long ret;
1399
1400        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1401        if (IS_ERR(key_ref)) {
1402                if (PTR_ERR(key_ref) != -EACCES)
1403                        return PTR_ERR(key_ref);
1404
1405                /* viewing a key under construction is also permitted if we
1406                 * have the authorisation token handy */
1407                instkey = key_get_instantiation_authkey(keyid);
1408                if (IS_ERR(instkey))
1409                        return PTR_ERR(instkey);
1410                key_put(instkey);
1411
1412                key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1413                if (IS_ERR(key_ref))
1414                        return PTR_ERR(key_ref);
1415        }
1416
1417        key = key_ref_to_ptr(key_ref);
1418        ret = security_key_getsecurity(key, &context);
1419        if (ret == 0) {
1420                /* if no information was returned, give userspace an empty
1421                 * string */
1422                ret = 1;
1423                if (buffer && buflen > 0 &&
1424                    copy_to_user(buffer, "", 1) != 0)
1425                        ret = -EFAULT;
1426        } else if (ret > 0) {
1427                /* return as much data as there's room for */
1428                if (buffer && buflen > 0) {
1429                        if (buflen > ret)
1430                                buflen = ret;
1431
1432                        if (copy_to_user(buffer, context, buflen) != 0)
1433                                ret = -EFAULT;
1434                }
1435
1436                kfree(context);
1437        }
1438
1439        key_ref_put(key_ref);
1440        return ret;
1441}
1442
1443/*
1444 * Attempt to install the calling process's session keyring on the process's
1445 * parent process.
1446 *
1447 * The keyring must exist and must grant the caller LINK permission, and the
1448 * parent process must be single-threaded and must have the same effective
1449 * ownership as this process and mustn't be SUID/SGID.
1450 *
1451 * The keyring will be emplaced on the parent when it next resumes userspace.
1452 *
1453 * If successful, 0 will be returned.
1454 */
1455long keyctl_session_to_parent(void)
1456{
1457        struct task_struct *me, *parent;
1458        const struct cred *mycred, *pcred;
1459        struct callback_head *newwork, *oldwork;
1460        key_ref_t keyring_r;
1461        struct cred *cred;
1462        int ret;
1463
1464        keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1465        if (IS_ERR(keyring_r))
1466                return PTR_ERR(keyring_r);
1467
1468        ret = -ENOMEM;
1469
1470        /* our parent is going to need a new cred struct, a new tgcred struct
1471         * and new security data, so we allocate them here to prevent ENOMEM in
1472         * our parent */
1473        cred = cred_alloc_blank();
1474        if (!cred)
1475                goto error_keyring;
1476        newwork = &cred->rcu;
1477
1478        cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1479        init_task_work(newwork, key_change_session_keyring);
1480
1481        me = current;
1482        rcu_read_lock();
1483        write_lock_irq(&tasklist_lock);
1484
1485        ret = -EPERM;
1486        oldwork = NULL;
1487        parent = me->real_parent;
1488
1489        task_lock(parent);
1490        /* the parent mustn't be init and mustn't be a kernel thread */
1491        if (parent->pid <= 1 || !parent->mm)
1492                goto unlock;
1493
1494        /* the parent must be single threaded */
1495        if (!thread_group_empty(parent))
1496                goto unlock;
1497
1498        /* the parent and the child must have different session keyrings or
1499         * there's no point */
1500        mycred = current_cred();
1501        pcred = __task_cred(parent);
1502        if (mycred == pcred ||
1503            mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) {
1504                ret = 0;
1505                goto unlock;
1506        }
1507
1508        /* the parent must have the same effective ownership and mustn't be
1509         * SUID/SGID */
1510        if (pcred->uid  != mycred->euid ||
1511            pcred->euid != mycred->euid ||
1512            pcred->suid != mycred->euid ||
1513            pcred->gid  != mycred->egid ||
1514            pcred->egid != mycred->egid ||
1515            pcred->sgid != mycred->egid)
1516                goto unlock;
1517
1518        /* the keyrings must have the same UID */
1519        if ((pcred->tgcred->session_keyring &&
1520             pcred->tgcred->session_keyring->uid != mycred->euid) ||
1521            mycred->tgcred->session_keyring->uid != mycred->euid)
1522                goto unlock;
1523
1524        /* cancel an already pending keyring replacement */
1525        oldwork = task_work_cancel(parent, key_change_session_keyring);
1526
1527        /* the replacement session keyring is applied just prior to userspace
1528         * restarting */
1529        ret = task_work_add(parent, newwork, true);
1530        if (!ret)
1531                newwork = NULL;
1532unlock:
1533        task_unlock(parent);
1534        write_unlock_irq(&tasklist_lock);
1535        rcu_read_unlock();
1536        if (oldwork)
1537                put_cred(container_of(oldwork, struct cred, rcu));
1538        if (newwork)
1539                put_cred(cred);
1540        return ret;
1541
1542error_keyring:
1543        key_ref_put(keyring_r);
1544        return ret;
1545}
1546
1547/*
1548 * The key control system call
1549 */
1550SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1551                unsigned long, arg4, unsigned long, arg5)
1552{
1553        switch (option) {
1554        case KEYCTL_GET_KEYRING_ID:
1555                return keyctl_get_keyring_ID((key_serial_t) arg2,
1556                                             (int) arg3);
1557
1558        case KEYCTL_JOIN_SESSION_KEYRING:
1559                return keyctl_join_session_keyring((const char __user *) arg2);
1560
1561        case KEYCTL_UPDATE:
1562                return keyctl_update_key((key_serial_t) arg2,
1563                                         (const void __user *) arg3,
1564                                         (size_t) arg4);
1565
1566        case KEYCTL_REVOKE:
1567                return keyctl_revoke_key((key_serial_t) arg2);
1568
1569        case KEYCTL_DESCRIBE:
1570                return keyctl_describe_key((key_serial_t) arg2,
1571                                           (char __user *) arg3,
1572                                           (unsigned) arg4);
1573
1574        case KEYCTL_CLEAR:
1575                return keyctl_keyring_clear((key_serial_t) arg2);
1576
1577        case KEYCTL_LINK:
1578                return keyctl_keyring_link((key_serial_t) arg2,
1579                                           (key_serial_t) arg3);
1580
1581        case KEYCTL_UNLINK:
1582                return keyctl_keyring_unlink((key_serial_t) arg2,
1583                                             (key_serial_t) arg3);
1584
1585        case KEYCTL_SEARCH:
1586                return keyctl_keyring_search((key_serial_t) arg2,
1587                                             (const char __user *) arg3,
1588                                             (const char __user *) arg4,
1589                                             (key_serial_t) arg5);
1590
1591        case KEYCTL_READ:
1592                return keyctl_read_key((key_serial_t) arg2,
1593                                       (char __user *) arg3,
1594                                       (size_t) arg4);
1595
1596        case KEYCTL_CHOWN:
1597                return keyctl_chown_key((key_serial_t) arg2,
1598                                        (uid_t) arg3,
1599                                        (gid_t) arg4);
1600
1601        case KEYCTL_SETPERM:
1602                return keyctl_setperm_key((key_serial_t) arg2,
1603                                          (key_perm_t) arg3);
1604
1605        case KEYCTL_INSTANTIATE:
1606                return keyctl_instantiate_key((key_serial_t) arg2,
1607                                              (const void __user *) arg3,
1608                                              (size_t) arg4,
1609                                              (key_serial_t) arg5);
1610
1611        case KEYCTL_NEGATE:
1612                return keyctl_negate_key((key_serial_t) arg2,
1613                                         (unsigned) arg3,
1614                                         (key_serial_t) arg4);
1615
1616        case KEYCTL_SET_REQKEY_KEYRING:
1617                return keyctl_set_reqkey_keyring(arg2);
1618
1619        case KEYCTL_SET_TIMEOUT:
1620                return keyctl_set_timeout((key_serial_t) arg2,
1621                                          (unsigned) arg3);
1622
1623        case KEYCTL_ASSUME_AUTHORITY:
1624                return keyctl_assume_authority((key_serial_t) arg2);
1625
1626        case KEYCTL_GET_SECURITY:
1627                return keyctl_get_security((key_serial_t) arg2,
1628                                           (char __user *) arg3,
1629                                           (size_t) arg4);
1630
1631        case KEYCTL_SESSION_TO_PARENT:
1632                return keyctl_session_to_parent();
1633
1634        case KEYCTL_REJECT:
1635                return keyctl_reject_key((key_serial_t) arg2,
1636                                         (unsigned) arg3,
1637                                         (unsigned) arg4,
1638                                         (key_serial_t) arg5);
1639
1640        case KEYCTL_INSTANTIATE_IOV:
1641                return keyctl_instantiate_key_iov(
1642                        (key_serial_t) arg2,
1643                        (const struct iovec __user *) arg3,
1644                        (unsigned) arg4,
1645                        (key_serial_t) arg5);
1646
1647        case KEYCTL_INVALIDATE:
1648                return keyctl_invalidate_key((key_serial_t) arg2);
1649
1650        default:
1651                return -EOPNOTSUPP;
1652        }
1653}
1654
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