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 * If the description is NULL or an empty string, the key type is asked to
  50 * generate one from the payload.
  51 *
  52 * The keyring must be writable so that we can attach the key to it.
  53 *
  54 * If successful, the new key's serial number is returned, otherwise an error
  55 * code is returned.
  56 */
  57SYSCALL_DEFINE5(add_key, const char __user *, _type,
  58                const char __user *, _description,
  59                const void __user *, _payload,
  60                size_t, plen,
  61                key_serial_t, ringid)
  62{
  63        key_ref_t keyring_ref, key_ref;
  64        char type[32], *description;
  65        void *payload;
  66        long ret;
  67        bool vm;
  68
  69        ret = -EINVAL;
  70        if (plen > 1024 * 1024 - 1)
  71                goto error;
  72
  73        /* draw all the data into kernel space */
  74        ret = key_get_type_from_user(type, _type, sizeof(type));
  75        if (ret < 0)
  76                goto error;
  77
  78        description = NULL;
  79        if (_description) {
  80                description = strndup_user(_description, PAGE_SIZE);
  81                if (IS_ERR(description)) {
  82                        ret = PTR_ERR(description);
  83                        goto error;
  84                }
  85                if (!*description) {
  86                        kfree(description);
  87                        description = NULL;
  88                }
  89        }
  90
  91        /* pull the payload in if one was supplied */
  92        payload = NULL;
  93
  94        vm = false;
  95        if (_payload) {
  96                ret = -ENOMEM;
  97                payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
  98                if (!payload) {
  99                        if (plen <= PAGE_SIZE)
 100                                goto error2;
 101                        vm = true;
 102                        payload = vmalloc(plen);
 103                        if (!payload)
 104                                goto error2;
 105                }
 106
 107                ret = -EFAULT;
 108                if (copy_from_user(payload, _payload, plen) != 0)
 109                        goto error3;
 110        }
 111
 112        /* find the target keyring (which must be writable) */
 113        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 114        if (IS_ERR(keyring_ref)) {
 115                ret = PTR_ERR(keyring_ref);
 116                goto error3;
 117        }
 118
 119        /* create or update the requested key and add it to the target
 120         * keyring */
 121        key_ref = key_create_or_update(keyring_ref, type, description,
 122                                       payload, plen, KEY_PERM_UNDEF,
 123                                       KEY_ALLOC_IN_QUOTA);
 124        if (!IS_ERR(key_ref)) {
 125                ret = key_ref_to_ptr(key_ref)->serial;
 126                key_ref_put(key_ref);
 127        }
 128        else {
 129                ret = PTR_ERR(key_ref);
 130        }
 131
 132        key_ref_put(keyring_ref);
 133 error3:
 134        if (!vm)
 135                kfree(payload);
 136        else
 137                vfree(payload);
 138 error2:
 139        kfree(description);
 140 error:
 141        return ret;
 142}
 143
 144/*
 145 * Search the process keyrings and keyring trees linked from those for a
 146 * matching key.  Keyrings must have appropriate Search permission to be
 147 * searched.
 148 *
 149 * If a key is found, it will be attached to the destination keyring if there's
 150 * one specified and the serial number of the key will be returned.
 151 *
 152 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 153 * non-NULL in an attempt to create a key.  The _callout_info string will be
 154 * passed to /sbin/request-key to aid with completing the request.  If the
 155 * _callout_info string is "" then it will be changed to "-".
 156 */
 157SYSCALL_DEFINE4(request_key, const char __user *, _type,
 158                const char __user *, _description,
 159                const char __user *, _callout_info,
 160                key_serial_t, destringid)
 161{
 162        struct key_type *ktype;
 163        struct key *key;
 164        key_ref_t dest_ref;
 165        size_t callout_len;
 166        char type[32], *description, *callout_info;
 167        long ret;
 168
 169        /* pull the type into kernel space */
 170        ret = key_get_type_from_user(type, _type, sizeof(type));
 171        if (ret < 0)
 172                goto error;
 173
 174        /* pull the description into kernel space */
 175        description = strndup_user(_description, PAGE_SIZE);
 176        if (IS_ERR(description)) {
 177                ret = PTR_ERR(description);
 178                goto error;
 179        }
 180
 181        /* pull the callout info into kernel space */
 182        callout_info = NULL;
 183        callout_len = 0;
 184        if (_callout_info) {
 185                callout_info = strndup_user(_callout_info, PAGE_SIZE);
 186                if (IS_ERR(callout_info)) {
 187                        ret = PTR_ERR(callout_info);
 188                        goto error2;
 189                }
 190                callout_len = strlen(callout_info);
 191        }
 192
 193        /* get the destination keyring if specified */
 194        dest_ref = NULL;
 195        if (destringid) {
 196                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 197                                           KEY_WRITE);
 198                if (IS_ERR(dest_ref)) {
 199                        ret = PTR_ERR(dest_ref);
 200                        goto error3;
 201                }
 202        }
 203
 204        /* find the key type */
 205        ktype = key_type_lookup(type);
 206        if (IS_ERR(ktype)) {
 207                ret = PTR_ERR(ktype);
 208                goto error4;
 209        }
 210
 211        /* do the search */
 212        key = request_key_and_link(ktype, description, callout_info,
 213                                   callout_len, NULL, key_ref_to_ptr(dest_ref),
 214                                   KEY_ALLOC_IN_QUOTA);
 215        if (IS_ERR(key)) {
 216                ret = PTR_ERR(key);
 217                goto error5;
 218        }
 219
 220        /* wait for the key to finish being constructed */
 221        ret = wait_for_key_construction(key, 1);
 222        if (ret < 0)
 223                goto error6;
 224
 225        ret = key->serial;
 226
 227error6:
 228        key_put(key);
 229error5:
 230        key_type_put(ktype);
 231error4:
 232        key_ref_put(dest_ref);
 233error3:
 234        kfree(callout_info);
 235error2:
 236        kfree(description);
 237error:
 238        return ret;
 239}
 240
 241/*
 242 * Get the ID of the specified process keyring.
 243 *
 244 * The requested keyring must have search permission to be found.
 245 *
 246 * If successful, the ID of the requested keyring will be returned.
 247 */
 248long keyctl_get_keyring_ID(key_serial_t id, int create)
 249{
 250        key_ref_t key_ref;
 251        unsigned long lflags;
 252        long ret;
 253
 254        lflags = create ? KEY_LOOKUP_CREATE : 0;
 255        key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 256        if (IS_ERR(key_ref)) {
 257                ret = PTR_ERR(key_ref);
 258                goto error;
 259        }
 260
 261        ret = key_ref_to_ptr(key_ref)->serial;
 262        key_ref_put(key_ref);
 263error:
 264        return ret;
 265}
 266
 267/*
 268 * Join a (named) session keyring.
 269 *
 270 * Create and join an anonymous session keyring or join a named session
 271 * keyring, creating it if necessary.  A named session keyring must have Search
 272 * permission for it to be joined.  Session keyrings without this permit will
 273 * be skipped over.
 274 *
 275 * If successful, the ID of the joined session keyring will be returned.
 276 */
 277long keyctl_join_session_keyring(const char __user *_name)
 278{
 279        char *name;
 280        long ret;
 281
 282        /* fetch the name from userspace */
 283        name = NULL;
 284        if (_name) {
 285                name = strndup_user(_name, PAGE_SIZE);
 286                if (IS_ERR(name)) {
 287                        ret = PTR_ERR(name);
 288                        goto error;
 289                }
 290        }
 291
 292        /* join the session */
 293        ret = join_session_keyring(name);
 294        kfree(name);
 295
 296error:
 297        return ret;
 298}
 299
 300/*
 301 * Update a key's data payload from the given data.
 302 *
 303 * The key must grant the caller Write permission and the key type must support
 304 * updating for this to work.  A negative key can be positively instantiated
 305 * with this call.
 306 *
 307 * If successful, 0 will be returned.  If the key type does not support
 308 * updating, then -EOPNOTSUPP will be returned.
 309 */
 310long keyctl_update_key(key_serial_t id,
 311                       const void __user *_payload,
 312                       size_t plen)
 313{
 314        key_ref_t key_ref;
 315        void *payload;
 316        long ret;
 317
 318        ret = -EINVAL;
 319        if (plen > PAGE_SIZE)
 320                goto error;
 321
 322        /* pull the payload in if one was supplied */
 323        payload = NULL;
 324        if (_payload) {
 325                ret = -ENOMEM;
 326                payload = kmalloc(plen, GFP_KERNEL);
 327                if (!payload)
 328                        goto error;
 329
 330                ret = -EFAULT;
 331                if (copy_from_user(payload, _payload, plen) != 0)
 332                        goto error2;
 333        }
 334
 335        /* find the target key (which must be writable) */
 336        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 337        if (IS_ERR(key_ref)) {
 338                ret = PTR_ERR(key_ref);
 339                goto error2;
 340        }
 341
 342        /* update the key */
 343        ret = key_update(key_ref, payload, plen);
 344
 345        key_ref_put(key_ref);
 346error2:
 347        kfree(payload);
 348error:
 349        return ret;
 350}
 351
 352/*
 353 * Revoke a key.
 354 *
 355 * The key must be grant the caller Write or Setattr permission for this to
 356 * work.  The key type should give up its quota claim when revoked.  The key
 357 * and any links to the key will be automatically garbage collected after a
 358 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 359 *
 360 * If successful, 0 is returned.
 361 */
 362long keyctl_revoke_key(key_serial_t id)
 363{
 364        key_ref_t key_ref;
 365        long ret;
 366
 367        key_ref = lookup_user_key(id, 0, KEY_WRITE);
 368        if (IS_ERR(key_ref)) {
 369                ret = PTR_ERR(key_ref);
 370                if (ret != -EACCES)
 371                        goto error;
 372                key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 373                if (IS_ERR(key_ref)) {
 374                        ret = PTR_ERR(key_ref);
 375                        goto error;
 376                }
 377        }
 378
 379        key_revoke(key_ref_to_ptr(key_ref));
 380        ret = 0;
 381
 382        key_ref_put(key_ref);
 383error:
 384        return ret;
 385}
 386
 387/*
 388 * Invalidate a key.
 389 *
 390 * The key must be grant the caller Invalidate permission for this to work.
 391 * The key and any links to the key will be automatically garbage collected
 392 * immediately.
 393 *
 394 * If successful, 0 is returned.
 395 */
 396long keyctl_invalidate_key(key_serial_t id)
 397{
 398        key_ref_t key_ref;
 399        long ret;
 400
 401        kenter("%d", id);
 402
 403        key_ref = lookup_user_key(id, 0, KEY_SEARCH);
 404        if (IS_ERR(key_ref)) {
 405                ret = PTR_ERR(key_ref);
 406                goto error;
 407        }
 408
 409        key_invalidate(key_ref_to_ptr(key_ref));
 410        ret = 0;
 411
 412        key_ref_put(key_ref);
 413error:
 414        kleave(" = %ld", ret);
 415        return ret;
 416}
 417
 418/*
 419 * Clear the specified keyring, creating an empty process keyring if one of the
 420 * special keyring IDs is used.
 421 *
 422 * The keyring must grant the caller Write permission for this to work.  If
 423 * successful, 0 will be returned.
 424 */
 425long keyctl_keyring_clear(key_serial_t ringid)
 426{
 427        key_ref_t keyring_ref;
 428        long ret;
 429
 430        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 431        if (IS_ERR(keyring_ref)) {
 432                ret = PTR_ERR(keyring_ref);
 433
 434                /* Root is permitted to invalidate certain special keyrings */
 435                if (capable(CAP_SYS_ADMIN)) {
 436                        keyring_ref = lookup_user_key(ringid, 0, 0);
 437                        if (IS_ERR(keyring_ref))
 438                                goto error;
 439                        if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 440                                     &key_ref_to_ptr(keyring_ref)->flags))
 441                                goto clear;
 442                        goto error_put;
 443                }
 444
 445                goto error;
 446        }
 447
 448clear:
 449        ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 450error_put:
 451        key_ref_put(keyring_ref);
 452error:
 453        return ret;
 454}
 455
 456/*
 457 * Create a link from a keyring to a key if there's no matching key in the
 458 * keyring, otherwise replace the link to the matching key with a link to the
 459 * new key.
 460 *
 461 * The key must grant the caller Link permission and the the keyring must grant
 462 * the caller Write permission.  Furthermore, if an additional link is created,
 463 * the keyring's quota will be extended.
 464 *
 465 * If successful, 0 will be returned.
 466 */
 467long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 468{
 469        key_ref_t keyring_ref, key_ref;
 470        long ret;
 471
 472        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 473        if (IS_ERR(keyring_ref)) {
 474                ret = PTR_ERR(keyring_ref);
 475                goto error;
 476        }
 477
 478        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 479        if (IS_ERR(key_ref)) {
 480                ret = PTR_ERR(key_ref);
 481                goto error2;
 482        }
 483
 484        ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 485
 486        key_ref_put(key_ref);
 487error2:
 488        key_ref_put(keyring_ref);
 489error:
 490        return ret;
 491}
 492
 493/*
 494 * Unlink a key from a keyring.
 495 *
 496 * The keyring must grant the caller Write permission for this to work; the key
 497 * itself need not grant the caller anything.  If the last link to a key is
 498 * removed then that key will be scheduled for destruction.
 499 *
 500 * If successful, 0 will be returned.
 501 */
 502long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 503{
 504        key_ref_t keyring_ref, key_ref;
 505        long ret;
 506
 507        keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 508        if (IS_ERR(keyring_ref)) {
 509                ret = PTR_ERR(keyring_ref);
 510                goto error;
 511        }
 512
 513        key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 514        if (IS_ERR(key_ref)) {
 515                ret = PTR_ERR(key_ref);
 516                goto error2;
 517        }
 518
 519        ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 520
 521        key_ref_put(key_ref);
 522error2:
 523        key_ref_put(keyring_ref);
 524error:
 525        return ret;
 526}
 527
 528/*
 529 * Return a description of a key to userspace.
 530 *
 531 * The key must grant the caller View permission for this to work.
 532 *
 533 * If there's a buffer, we place up to buflen bytes of data into it formatted
 534 * in the following way:
 535 *
 536 *      type;uid;gid;perm;description<NUL>
 537 *
 538 * If successful, we return the amount of description available, irrespective
 539 * of how much we may have copied into the buffer.
 540 */
 541long keyctl_describe_key(key_serial_t keyid,
 542                         char __user *buffer,
 543                         size_t buflen)
 544{
 545        struct key *key, *instkey;
 546        key_ref_t key_ref;
 547        char *tmpbuf;
 548        long ret;
 549
 550        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 551        if (IS_ERR(key_ref)) {
 552                /* viewing a key under construction is permitted if we have the
 553                 * authorisation token handy */
 554                if (PTR_ERR(key_ref) == -EACCES) {
 555                        instkey = key_get_instantiation_authkey(keyid);
 556                        if (!IS_ERR(instkey)) {
 557                                key_put(instkey);
 558                                key_ref = lookup_user_key(keyid,
 559                                                          KEY_LOOKUP_PARTIAL,
 560                                                          0);
 561                                if (!IS_ERR(key_ref))
 562                                        goto okay;
 563                        }
 564                }
 565
 566                ret = PTR_ERR(key_ref);
 567                goto error;
 568        }
 569
 570okay:
 571        /* calculate how much description we're going to return */
 572        ret = -ENOMEM;
 573        tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 574        if (!tmpbuf)
 575                goto error2;
 576
 577        key = key_ref_to_ptr(key_ref);
 578
 579        ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 580                       "%s;%d;%d;%08x;%s",
 581                       key->type->name,
 582                       from_kuid_munged(current_user_ns(), key->uid),
 583                       from_kgid_munged(current_user_ns(), key->gid),
 584                       key->perm,
 585                       key->description ?: "");
 586
 587        /* include a NUL char at the end of the data */
 588        if (ret > PAGE_SIZE - 1)
 589                ret = PAGE_SIZE - 1;
 590        tmpbuf[ret] = 0;
 591        ret++;
 592
 593        /* consider returning the data */
 594        if (buffer && buflen > 0) {
 595                if (buflen > ret)
 596                        buflen = ret;
 597
 598                if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 599                        ret = -EFAULT;
 600        }
 601
 602        kfree(tmpbuf);
 603error2:
 604        key_ref_put(key_ref);
 605error:
 606        return ret;
 607}
 608
 609/*
 610 * Search the specified keyring and any keyrings it links to for a matching
 611 * key.  Only keyrings that grant the caller Search permission will be searched
 612 * (this includes the starting keyring).  Only keys with Search permission can
 613 * be found.
 614 *
 615 * If successful, the found key will be linked to the destination keyring if
 616 * supplied and the key has Link permission, and the found key ID will be
 617 * returned.
 618 */
 619long keyctl_keyring_search(key_serial_t ringid,
 620                           const char __user *_type,
 621                           const char __user *_description,
 622                           key_serial_t destringid)
 623{
 624        struct key_type *ktype;
 625        key_ref_t keyring_ref, key_ref, dest_ref;
 626        char type[32], *description;
 627        long ret;
 628
 629        /* pull the type and description into kernel space */
 630        ret = key_get_type_from_user(type, _type, sizeof(type));
 631        if (ret < 0)
 632                goto error;
 633
 634        description = strndup_user(_description, PAGE_SIZE);
 635        if (IS_ERR(description)) {
 636                ret = PTR_ERR(description);
 637                goto error;
 638        }
 639
 640        /* get the keyring at which to begin the search */
 641        keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 642        if (IS_ERR(keyring_ref)) {
 643                ret = PTR_ERR(keyring_ref);
 644                goto error2;
 645        }
 646
 647        /* get the destination keyring if specified */
 648        dest_ref = NULL;
 649        if (destringid) {
 650                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 651                                           KEY_WRITE);
 652                if (IS_ERR(dest_ref)) {
 653                        ret = PTR_ERR(dest_ref);
 654                        goto error3;
 655                }
 656        }
 657
 658        /* find the key type */
 659        ktype = key_type_lookup(type);
 660        if (IS_ERR(ktype)) {
 661                ret = PTR_ERR(ktype);
 662                goto error4;
 663        }
 664
 665        /* do the search */
 666        key_ref = keyring_search(keyring_ref, ktype, description);
 667        if (IS_ERR(key_ref)) {
 668                ret = PTR_ERR(key_ref);
 669
 670                /* treat lack or presence of a negative key the same */
 671                if (ret == -EAGAIN)
 672                        ret = -ENOKEY;
 673                goto error5;
 674        }
 675
 676        /* link the resulting key to the destination keyring if we can */
 677        if (dest_ref) {
 678                ret = key_permission(key_ref, KEY_LINK);
 679                if (ret < 0)
 680                        goto error6;
 681
 682                ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 683                if (ret < 0)
 684                        goto error6;
 685        }
 686
 687        ret = key_ref_to_ptr(key_ref)->serial;
 688
 689error6:
 690        key_ref_put(key_ref);
 691error5:
 692        key_type_put(ktype);
 693error4:
 694        key_ref_put(dest_ref);
 695error3:
 696        key_ref_put(keyring_ref);
 697error2:
 698        kfree(description);
 699error:
 700        return ret;
 701}
 702
 703/*
 704 * Read a key's payload.
 705 *
 706 * The key must either grant the caller Read permission, or it must grant the
 707 * caller Search permission when searched for from the process keyrings.
 708 *
 709 * If successful, we place up to buflen bytes of data into the buffer, if one
 710 * is provided, and return the amount of data that is available in the key,
 711 * irrespective of how much we copied into the buffer.
 712 */
 713long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 714{
 715        struct key *key;
 716        key_ref_t key_ref;
 717        long ret;
 718
 719        /* find the key first */
 720        key_ref = lookup_user_key(keyid, 0, 0);
 721        if (IS_ERR(key_ref)) {
 722                ret = -ENOKEY;
 723                goto error;
 724        }
 725
 726        key = key_ref_to_ptr(key_ref);
 727
 728        /* see if we can read it directly */
 729        ret = key_permission(key_ref, KEY_READ);
 730        if (ret == 0)
 731                goto can_read_key;
 732        if (ret != -EACCES)
 733                goto error;
 734
 735        /* we can't; see if it's searchable from this process's keyrings
 736         * - we automatically take account of the fact that it may be
 737         *   dangling off an instantiation key
 738         */
 739        if (!is_key_possessed(key_ref)) {
 740                ret = -EACCES;
 741                goto error2;
 742        }
 743
 744        /* the key is probably readable - now try to read it */
 745can_read_key:
 746        ret = key_validate(key);
 747        if (ret == 0) {
 748                ret = -EOPNOTSUPP;
 749                if (key->type->read) {
 750                        /* read the data with the semaphore held (since we
 751                         * might sleep) */
 752                        down_read(&key->sem);
 753                        ret = key->type->read(key, buffer, buflen);
 754                        up_read(&key->sem);
 755                }
 756        }
 757
 758error2:
 759        key_put(key);
 760error:
 761        return ret;
 762}
 763
 764/*
 765 * Change the ownership of a key
 766 *
 767 * The key must grant the caller Setattr permission for this to work, though
 768 * the key need not be fully instantiated yet.  For the UID to be changed, or
 769 * for the GID to be changed to a group the caller is not a member of, the
 770 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 771 * attribute is not changed.
 772 *
 773 * If the UID is to be changed, the new user must have sufficient quota to
 774 * accept the key.  The quota deduction will be removed from the old user to
 775 * the new user should the attribute be changed.
 776 *
 777 * If successful, 0 will be returned.
 778 */
 779long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
 780{
 781        struct key_user *newowner, *zapowner = NULL;
 782        struct key *key;
 783        key_ref_t key_ref;
 784        long ret;
 785        kuid_t uid;
 786        kgid_t gid;
 787
 788        uid = make_kuid(current_user_ns(), user);
 789        gid = make_kgid(current_user_ns(), group);
 790        ret = -EINVAL;
 791        if ((user != (uid_t) -1) && !uid_valid(uid))
 792                goto error;
 793        if ((group != (gid_t) -1) && !gid_valid(gid))
 794                goto error;
 795
 796        ret = 0;
 797        if (user == (uid_t) -1 && group == (gid_t) -1)
 798                goto error;
 799
 800        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 801                                  KEY_SETATTR);
 802        if (IS_ERR(key_ref)) {
 803                ret = PTR_ERR(key_ref);
 804                goto error;
 805        }
 806
 807        key = key_ref_to_ptr(key_ref);
 808
 809        /* make the changes with the locks held to prevent chown/chown races */
 810        ret = -EACCES;
 811        down_write(&key->sem);
 812
 813        if (!capable(CAP_SYS_ADMIN)) {
 814                /* only the sysadmin can chown a key to some other UID */
 815                if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
 816                        goto error_put;
 817
 818                /* only the sysadmin can set the key's GID to a group other
 819                 * than one of those that the current process subscribes to */
 820                if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
 821                        goto error_put;
 822        }
 823
 824        /* change the UID */
 825        if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
 826                ret = -ENOMEM;
 827                newowner = key_user_lookup(uid);
 828                if (!newowner)
 829                        goto error_put;
 830
 831                /* transfer the quota burden to the new user */
 832                if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 833                        unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
 834                                key_quota_root_maxkeys : key_quota_maxkeys;
 835                        unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
 836                                key_quota_root_maxbytes : key_quota_maxbytes;
 837
 838                        spin_lock(&newowner->lock);
 839                        if (newowner->qnkeys + 1 >= maxkeys ||
 840                            newowner->qnbytes + key->quotalen >= maxbytes ||
 841                            newowner->qnbytes + key->quotalen <
 842                            newowner->qnbytes)
 843                                goto quota_overrun;
 844
 845                        newowner->qnkeys++;
 846                        newowner->qnbytes += key->quotalen;
 847                        spin_unlock(&newowner->lock);
 848
 849                        spin_lock(&key->user->lock);
 850                        key->user->qnkeys--;
 851                        key->user->qnbytes -= key->quotalen;
 852                        spin_unlock(&key->user->lock);
 853                }
 854
 855                atomic_dec(&key->user->nkeys);
 856                atomic_inc(&newowner->nkeys);
 857
 858                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 859                        atomic_dec(&key->user->nikeys);
 860                        atomic_inc(&newowner->nikeys);
 861                }
 862
 863                zapowner = key->user;
 864                key->user = newowner;
 865                key->uid = uid;
 866        }
 867
 868        /* change the GID */
 869        if (group != (gid_t) -1)
 870                key->gid = gid;
 871
 872        ret = 0;
 873
 874error_put:
 875        up_write(&key->sem);
 876        key_put(key);
 877        if (zapowner)
 878                key_user_put(zapowner);
 879error:
 880        return ret;
 881
 882quota_overrun:
 883        spin_unlock(&newowner->lock);
 884        zapowner = newowner;
 885        ret = -EDQUOT;
 886        goto error_put;
 887}
 888
 889/*
 890 * Change the permission mask on a key.
 891 *
 892 * The key must grant the caller Setattr permission for this to work, though
 893 * the key need not be fully instantiated yet.  If the caller does not have
 894 * sysadmin capability, it may only change the permission on keys that it owns.
 895 */
 896long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 897{
 898        struct key *key;
 899        key_ref_t key_ref;
 900        long ret;
 901
 902        ret = -EINVAL;
 903        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 904                goto error;
 905
 906        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 907                                  KEY_SETATTR);
 908        if (IS_ERR(key_ref)) {
 909                ret = PTR_ERR(key_ref);
 910                goto error;
 911        }
 912
 913        key = key_ref_to_ptr(key_ref);
 914
 915        /* make the changes with the locks held to prevent chown/chmod races */
 916        ret = -EACCES;
 917        down_write(&key->sem);
 918
 919        /* if we're not the sysadmin, we can only change a key that we own */
 920        if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
 921                key->perm = perm;
 922                ret = 0;
 923        }
 924
 925        up_write(&key->sem);
 926        key_put(key);
 927error:
 928        return ret;
 929}
 930
 931/*
 932 * Get the destination keyring for instantiation and check that the caller has
 933 * Write permission on it.
 934 */
 935static long get_instantiation_keyring(key_serial_t ringid,
 936                                      struct request_key_auth *rka,
 937                                      struct key **_dest_keyring)
 938{
 939        key_ref_t dkref;
 940
 941        *_dest_keyring = NULL;
 942
 943        /* just return a NULL pointer if we weren't asked to make a link */
 944        if (ringid == 0)
 945                return 0;
 946
 947        /* if a specific keyring is nominated by ID, then use that */
 948        if (ringid > 0) {
 949                dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 950                if (IS_ERR(dkref))
 951                        return PTR_ERR(dkref);
 952                *_dest_keyring = key_ref_to_ptr(dkref);
 953                return 0;
 954        }
 955
 956        if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 957                return -EINVAL;
 958
 959        /* otherwise specify the destination keyring recorded in the
 960         * authorisation key (any KEY_SPEC_*_KEYRING) */
 961        if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 962                *_dest_keyring = key_get(rka->dest_keyring);
 963                return 0;
 964        }
 965
 966        return -ENOKEY;
 967}
 968
 969/*
 970 * Change the request_key authorisation key on the current process.
 971 */
 972static int keyctl_change_reqkey_auth(struct key *key)
 973{
 974        struct cred *new;
 975
 976        new = prepare_creds();
 977        if (!new)
 978                return -ENOMEM;
 979
 980        key_put(new->request_key_auth);
 981        new->request_key_auth = key_get(key);
 982
 983        return commit_creds(new);
 984}
 985
 986/*
 987 * Copy the iovec data from userspace
 988 */
 989static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
 990                                 unsigned ioc)
 991{
 992        for (; ioc > 0; ioc--) {
 993                if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
 994                        return -EFAULT;
 995                buffer += iov->iov_len;
 996                iov++;
 997        }
 998        return 0;
 999}
1000
1001/*
1002 * Instantiate a key with the specified payload and link the key into the
1003 * destination keyring if one is given.
1004 *
1005 * The caller must have the appropriate instantiation permit set for this to
1006 * work (see keyctl_assume_authority).  No other permissions are required.
1007 *
1008 * If successful, 0 will be returned.
1009 */
1010long keyctl_instantiate_key_common(key_serial_t id,
1011                                   const struct iovec *payload_iov,
1012                                   unsigned ioc,
1013                                   size_t plen,
1014                                   key_serial_t ringid)
1015{
1016        const struct cred *cred = current_cred();
1017        struct request_key_auth *rka;
1018        struct key *instkey, *dest_keyring;
1019        void *payload;
1020        long ret;
1021        bool vm = false;
1022
1023        kenter("%d,,%zu,%d", id, plen, ringid);
1024
1025        ret = -EINVAL;
1026        if (plen > 1024 * 1024 - 1)
1027                goto error;
1028
1029        /* the appropriate instantiation authorisation key must have been
1030         * assumed before calling this */
1031        ret = -EPERM;
1032        instkey = cred->request_key_auth;
1033        if (!instkey)
1034                goto error;
1035
1036        rka = instkey->payload.data;
1037        if (rka->target_key->serial != id)
1038                goto error;
1039
1040        /* pull the payload in if one was supplied */
1041        payload = NULL;
1042
1043        if (payload_iov) {
1044                ret = -ENOMEM;
1045                payload = kmalloc(plen, GFP_KERNEL);
1046                if (!payload) {
1047                        if (plen <= PAGE_SIZE)
1048                                goto error;
1049                        vm = true;
1050                        payload = vmalloc(plen);
1051                        if (!payload)
1052                                goto error;
1053                }
1054
1055                ret = copy_from_user_iovec(payload, payload_iov, ioc);
1056                if (ret < 0)
1057                        goto error2;
1058        }
1059
1060        /* find the destination keyring amongst those belonging to the
1061         * requesting task */
1062        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1063        if (ret < 0)
1064                goto error2;
1065
1066        /* instantiate the key and link it into a keyring */
1067        ret = key_instantiate_and_link(rka->target_key, payload, plen,
1068                                       dest_keyring, instkey);
1069
1070        key_put(dest_keyring);
1071
1072        /* discard the assumed authority if it's just been disabled by
1073         * instantiation of the key */
1074        if (ret == 0)
1075                keyctl_change_reqkey_auth(NULL);
1076
1077error2:
1078        if (!vm)
1079                kfree(payload);
1080        else
1081                vfree(payload);
1082error:
1083        return ret;
1084}
1085
1086/*
1087 * Instantiate a key with the specified payload and link the key into the
1088 * destination keyring if one is given.
1089 *
1090 * The caller must have the appropriate instantiation permit set for this to
1091 * work (see keyctl_assume_authority).  No other permissions are required.
1092 *
1093 * If successful, 0 will be returned.
1094 */
1095long keyctl_instantiate_key(key_serial_t id,
1096                            const void __user *_payload,
1097                            size_t plen,
1098                            key_serial_t ringid)
1099{
1100        if (_payload && plen) {
1101                struct iovec iov[1] = {
1102                        [0].iov_base = (void __user *)_payload,
1103                        [0].iov_len  = plen
1104                };
1105
1106                return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1107        }
1108
1109        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1110}
1111
1112/*
1113 * Instantiate a key with the specified multipart payload and link the key into
1114 * the destination keyring if one is given.
1115 *
1116 * The caller must have the appropriate instantiation permit set for this to
1117 * work (see keyctl_assume_authority).  No other permissions are required.
1118 *
1119 * If successful, 0 will be returned.
1120 */
1121long keyctl_instantiate_key_iov(key_serial_t id,
1122                                const struct iovec __user *_payload_iov,
1123                                unsigned ioc,
1124                                key_serial_t ringid)
1125{
1126        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1127        long ret;
1128
1129        if (!_payload_iov || !ioc)
1130                goto no_payload;
1131
1132        ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1133                                    ARRAY_SIZE(iovstack), iovstack, &iov);
1134        if (ret < 0)
1135                return ret;
1136        if (ret == 0)
1137                goto no_payload_free;
1138
1139        ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1140
1141        if (iov != iovstack)
1142                kfree(iov);
1143        return ret;
1144
1145no_payload_free:
1146        if (iov != iovstack)
1147                kfree(iov);
1148no_payload:
1149        return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1150}
1151
1152/*
1153 * Negatively instantiate the key with the given timeout (in seconds) and link
1154 * 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 -ENOKEY until the negative key expires.
1164 *
1165 * If successful, 0 will be returned.
1166 */
1167long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1168{
1169        return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1170}
1171
1172/*
1173 * Negatively instantiate the key with the given timeout (in seconds) and error
1174 * code and link the key into the destination keyring if one is given.
1175 *
1176 * The caller must have the appropriate instantiation permit set for this to
1177 * work (see keyctl_assume_authority).  No other permissions are required.
1178 *
1179 * The key and any links to the key will be automatically garbage collected
1180 * after the timeout expires.
1181 *
1182 * Negative keys are used to rate limit repeated request_key() calls by causing
1183 * them to return the specified error code until the negative key expires.
1184 *
1185 * If successful, 0 will be returned.
1186 */
1187long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1188                       key_serial_t ringid)
1189{
1190        const struct cred *cred = current_cred();
1191        struct request_key_auth *rka;
1192        struct key *instkey, *dest_keyring;
1193        long ret;
1194
1195        kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1196
1197        /* must be a valid error code and mustn't be a kernel special */
1198        if (error <= 0 ||
1199            error >= MAX_ERRNO ||
1200            error == ERESTARTSYS ||
1201            error == ERESTARTNOINTR ||
1202            error == ERESTARTNOHAND ||
1203            error == ERESTART_RESTARTBLOCK)
1204                return -EINVAL;
1205
1206        /* the appropriate instantiation authorisation key must have been
1207         * assumed before calling this */
1208        ret = -EPERM;
1209        instkey = cred->request_key_auth;
1210        if (!instkey)
1211                goto error;
1212
1213        rka = instkey->payload.data;
1214        if (rka->target_key->serial != id)
1215                goto error;
1216
1217        /* find the destination keyring if present (which must also be
1218         * writable) */
1219        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1220        if (ret < 0)
1221                goto error;
1222
1223        /* instantiate the key and link it into a keyring */
1224        ret = key_reject_and_link(rka->target_key, timeout, error,
1225                                  dest_keyring, instkey);
1226
1227        key_put(dest_keyring);
1228
1229        /* discard the assumed authority if it's just been disabled by
1230         * instantiation of the key */
1231        if (ret == 0)
1232                keyctl_change_reqkey_auth(NULL);
1233
1234error:
1235        return ret;
1236}
1237
1238/*
1239 * Read or set the default keyring in which request_key() will cache keys and
1240 * return the old setting.
1241 *
1242 * If a process keyring is specified then this will be created if it doesn't
1243 * yet exist.  The old setting will be returned if successful.
1244 */
1245long keyctl_set_reqkey_keyring(int reqkey_defl)
1246{
1247        struct cred *new;
1248        int ret, old_setting;
1249
1250        old_setting = current_cred_xxx(jit_keyring);
1251
1252        if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1253                return old_setting;
1254
1255        new = prepare_creds();
1256        if (!new)
1257                return -ENOMEM;
1258
1259        switch (reqkey_defl) {
1260        case KEY_REQKEY_DEFL_THREAD_KEYRING:
1261                ret = install_thread_keyring_to_cred(new);
1262                if (ret < 0)
1263                        goto error;
1264                goto set;
1265
1266        case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1267                ret = install_process_keyring_to_cred(new);
1268                if (ret < 0) {
1269                        if (ret != -EEXIST)
1270                                goto error;
1271                        ret = 0;
1272                }
1273                goto set;
1274
1275        case KEY_REQKEY_DEFL_DEFAULT:
1276        case KEY_REQKEY_DEFL_SESSION_KEYRING:
1277        case KEY_REQKEY_DEFL_USER_KEYRING:
1278        case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1279        case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1280                goto set;
1281
1282        case KEY_REQKEY_DEFL_NO_CHANGE:
1283        case KEY_REQKEY_DEFL_GROUP_KEYRING:
1284        default:
1285                ret = -EINVAL;
1286                goto error;
1287        }
1288
1289set:
1290        new->jit_keyring = reqkey_defl;
1291        commit_creds(new);
1292        return old_setting;
1293error:
1294        abort_creds(new);
1295        return ret;
1296}
1297
1298/*
1299 * Set or clear the timeout on a key.
1300 *
1301 * Either the key must grant the caller Setattr permission or else the caller
1302 * must hold an instantiation authorisation token for the key.
1303 *
1304 * The timeout is either 0 to clear the timeout, or a number of seconds from
1305 * the current time.  The key and any links to the key will be automatically
1306 * garbage collected after the timeout expires.
1307 *
1308 * If successful, 0 is returned.
1309 */
1310long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1311{
1312        struct key *key, *instkey;
1313        key_ref_t key_ref;
1314        long ret;
1315
1316        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1317                                  KEY_SETATTR);
1318        if (IS_ERR(key_ref)) {
1319                /* setting the timeout on a key under construction is permitted
1320                 * if we have the authorisation token handy */
1321                if (PTR_ERR(key_ref) == -EACCES) {
1322                        instkey = key_get_instantiation_authkey(id);
1323                        if (!IS_ERR(instkey)) {
1324                                key_put(instkey);
1325                                key_ref = lookup_user_key(id,
1326                                                          KEY_LOOKUP_PARTIAL,
1327                                                          0);
1328                                if (!IS_ERR(key_ref))
1329                                        goto okay;
1330                        }
1331                }
1332
1333                ret = PTR_ERR(key_ref);
1334                goto error;
1335        }
1336
1337okay:
1338        key = key_ref_to_ptr(key_ref);
1339        key_set_timeout(key, timeout);
1340        key_put(key);
1341
1342        ret = 0;
1343error:
1344        return ret;
1345}
1346
1347/*
1348 * Assume (or clear) the authority to instantiate the specified key.
1349 *
1350 * This sets the authoritative token currently in force for key instantiation.
1351 * This must be done for a key to be instantiated.  It has the effect of making
1352 * available all the keys from the caller of the request_key() that created a
1353 * key to request_key() calls made by the caller of this function.
1354 *
1355 * The caller must have the instantiation key in their process keyrings with a
1356 * Search permission grant available to the caller.
1357 *
1358 * If the ID given is 0, then the setting will be cleared and 0 returned.
1359 *
1360 * If the ID given has a matching an authorisation key, then that key will be
1361 * set and its ID will be returned.  The authorisation key can be read to get
1362 * the callout information passed to request_key().
1363 */
1364long keyctl_assume_authority(key_serial_t id)
1365{
1366        struct key *authkey;
1367        long ret;
1368
1369        /* special key IDs aren't permitted */
1370        ret = -EINVAL;
1371        if (id < 0)
1372                goto error;
1373
1374        /* we divest ourselves of authority if given an ID of 0 */
1375        if (id == 0) {
1376                ret = keyctl_change_reqkey_auth(NULL);
1377                goto error;
1378        }
1379
1380        /* attempt to assume the authority temporarily granted to us whilst we
1381         * instantiate the specified key
1382         * - the authorisation key must be in the current task's keyrings
1383         *   somewhere
1384         */
1385        authkey = key_get_instantiation_authkey(id);
1386        if (IS_ERR(authkey)) {
1387                ret = PTR_ERR(authkey);
1388                goto error;
1389        }
1390
1391        ret = keyctl_change_reqkey_auth(authkey);
1392        if (ret < 0)
1393                goto error;
1394        key_put(authkey);
1395
1396        ret = authkey->serial;
1397error:
1398        return ret;
1399}
1400
1401/*
1402 * Get a key's the LSM security label.
1403 *
1404 * The key must grant the caller View permission for this to work.
1405 *
1406 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1407 *
1408 * If successful, the amount of information available will be returned,
1409 * irrespective of how much was copied (including the terminal NUL).
1410 */
1411long keyctl_get_security(key_serial_t keyid,
1412                         char __user *buffer,
1413                         size_t buflen)
1414{
1415        struct key *key, *instkey;
1416        key_ref_t key_ref;
1417        char *context;
1418        long ret;
1419
1420        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1421        if (IS_ERR(key_ref)) {
1422                if (PTR_ERR(key_ref) != -EACCES)
1423                        return PTR_ERR(key_ref);
1424
1425                /* viewing a key under construction is also permitted if we
1426                 * have the authorisation token handy */
1427                instkey = key_get_instantiation_authkey(keyid);
1428                if (IS_ERR(instkey))
1429                        return PTR_ERR(instkey);
1430                key_put(instkey);
1431
1432                key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1433                if (IS_ERR(key_ref))
1434                        return PTR_ERR(key_ref);
1435        }
1436
1437        key = key_ref_to_ptr(key_ref);
1438        ret = security_key_getsecurity(key, &context);
1439        if (ret == 0) {
1440                /* if no information was returned, give userspace an empty
1441                 * string */
1442                ret = 1;
1443                if (buffer && buflen > 0 &&
1444                    copy_to_user(buffer, "", 1) != 0)
1445                        ret = -EFAULT;
1446        } else if (ret > 0) {
1447                /* return as much data as there's room for */
1448                if (buffer && buflen > 0) {
1449                        if (buflen > ret)
1450                                buflen = ret;
1451
1452                        if (copy_to_user(buffer, context, buflen) != 0)
1453                                ret = -EFAULT;
1454                }
1455
1456                kfree(context);
1457        }
1458
1459        key_ref_put(key_ref);
1460        return ret;
1461}
1462
1463/*
1464 * Attempt to install the calling process's session keyring on the process's
1465 * parent process.
1466 *
1467 * The keyring must exist and must grant the caller LINK permission, and the
1468 * parent process must be single-threaded and must have the same effective
1469 * ownership as this process and mustn't be SUID/SGID.
1470 *
1471 * The keyring will be emplaced on the parent when it next resumes userspace.
1472 *
1473 * If successful, 0 will be returned.
1474 */
1475long keyctl_session_to_parent(void)
1476{
1477        struct task_struct *me, *parent;
1478        const struct cred *mycred, *pcred;
1479        struct callback_head *newwork, *oldwork;
1480        key_ref_t keyring_r;
1481        struct cred *cred;
1482        int ret;
1483
1484        keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1485        if (IS_ERR(keyring_r))
1486                return PTR_ERR(keyring_r);
1487
1488        ret = -ENOMEM;
1489
1490        /* our parent is going to need a new cred struct, a new tgcred struct
1491         * and new security data, so we allocate them here to prevent ENOMEM in
1492         * our parent */
1493        cred = cred_alloc_blank();
1494        if (!cred)
1495                goto error_keyring;
1496        newwork = &cred->rcu;
1497
1498        cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1499        init_task_work(newwork, key_change_session_keyring);
1500
1501        me = current;
1502        rcu_read_lock();
1503        write_lock_irq(&tasklist_lock);
1504
1505        ret = -EPERM;
1506        oldwork = NULL;
1507        parent = me->real_parent;
1508
1509        /* the parent mustn't be init and mustn't be a kernel thread */
1510        if (parent->pid <= 1 || !parent->mm)
1511                goto unlock;
1512
1513        /* the parent must be single threaded */
1514        if (!thread_group_empty(parent))
1515                goto unlock;
1516
1517        /* the parent and the child must have different session keyrings or
1518         * there's no point */
1519        mycred = current_cred();
1520        pcred = __task_cred(parent);
1521        if (mycred == pcred ||
1522            mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) {
1523                ret = 0;
1524                goto unlock;
1525        }
1526
1527        /* the parent must have the same effective ownership and mustn't be
1528         * SUID/SGID */
1529        if (!uid_eq(pcred->uid,  mycred->euid) ||
1530            !uid_eq(pcred->euid, mycred->euid) ||
1531            !uid_eq(pcred->suid, mycred->euid) ||
1532            !gid_eq(pcred->gid,  mycred->egid) ||
1533            !gid_eq(pcred->egid, mycred->egid) ||
1534            !gid_eq(pcred->sgid, mycred->egid))
1535                goto unlock;
1536
1537        /* the keyrings must have the same UID */
1538        if ((pcred->tgcred->session_keyring &&
1539             !uid_eq(pcred->tgcred->session_keyring->uid, mycred->euid)) ||
1540            !uid_eq(mycred->tgcred->session_keyring->uid, mycred->euid))
1541                goto unlock;
1542
1543        /* cancel an already pending keyring replacement */
1544        oldwork = task_work_cancel(parent, key_change_session_keyring);
1545
1546        /* the replacement session keyring is applied just prior to userspace
1547         * restarting */
1548        ret = task_work_add(parent, newwork, true);
1549        if (!ret)
1550                newwork = NULL;
1551unlock:
1552        write_unlock_irq(&tasklist_lock);
1553        rcu_read_unlock();
1554        if (oldwork)
1555                put_cred(container_of(oldwork, struct cred, rcu));
1556        if (newwork)
1557                put_cred(cred);
1558        return ret;
1559
1560error_keyring:
1561        key_ref_put(keyring_r);
1562        return ret;
1563}
1564
1565/*
1566 * The key control system call
1567 */
1568SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1569                unsigned long, arg4, unsigned long, arg5)
1570{
1571        switch (option) {
1572        case KEYCTL_GET_KEYRING_ID:
1573                return keyctl_get_keyring_ID((key_serial_t) arg2,
1574                                             (int) arg3);
1575
1576        case KEYCTL_JOIN_SESSION_KEYRING:
1577                return keyctl_join_session_keyring((const char __user *) arg2);
1578
1579        case KEYCTL_UPDATE:
1580                return keyctl_update_key((key_serial_t) arg2,
1581                                         (const void __user *) arg3,
1582                                         (size_t) arg4);
1583
1584        case KEYCTL_REVOKE:
1585                return keyctl_revoke_key((key_serial_t) arg2);
1586
1587        case KEYCTL_DESCRIBE:
1588                return keyctl_describe_key((key_serial_t) arg2,
1589                                           (char __user *) arg3,
1590                                           (unsigned) arg4);
1591
1592        case KEYCTL_CLEAR:
1593                return keyctl_keyring_clear((key_serial_t) arg2);
1594
1595        case KEYCTL_LINK:
1596                return keyctl_keyring_link((key_serial_t) arg2,
1597                                           (key_serial_t) arg3);
1598
1599        case KEYCTL_UNLINK:
1600                return keyctl_keyring_unlink((key_serial_t) arg2,
1601                                             (key_serial_t) arg3);
1602
1603        case KEYCTL_SEARCH:
1604                return keyctl_keyring_search((key_serial_t) arg2,
1605                                             (const char __user *) arg3,
1606                                             (const char __user *) arg4,
1607                                             (key_serial_t) arg5);
1608
1609        case KEYCTL_READ:
1610                return keyctl_read_key((key_serial_t) arg2,
1611                                       (char __user *) arg3,
1612                                       (size_t) arg4);
1613
1614        case KEYCTL_CHOWN:
1615                return keyctl_chown_key((key_serial_t) arg2,
1616                                        (uid_t) arg3,
1617                                        (gid_t) arg4);
1618
1619        case KEYCTL_SETPERM:
1620                return keyctl_setperm_key((key_serial_t) arg2,
1621                                          (key_perm_t) arg3);
1622
1623        case KEYCTL_INSTANTIATE:
1624                return keyctl_instantiate_key((key_serial_t) arg2,
1625                                              (const void __user *) arg3,
1626                                              (size_t) arg4,
1627                                              (key_serial_t) arg5);
1628
1629        case KEYCTL_NEGATE:
1630                return keyctl_negate_key((key_serial_t) arg2,
1631                                         (unsigned) arg3,
1632                                         (key_serial_t) arg4);
1633
1634        case KEYCTL_SET_REQKEY_KEYRING:
1635                return keyctl_set_reqkey_keyring(arg2);
1636
1637        case KEYCTL_SET_TIMEOUT:
1638                return keyctl_set_timeout((key_serial_t) arg2,
1639                                          (unsigned) arg3);
1640
1641        case KEYCTL_ASSUME_AUTHORITY:
1642                return keyctl_assume_authority((key_serial_t) arg2);
1643
1644        case KEYCTL_GET_SECURITY:
1645                return keyctl_get_security((key_serial_t) arg2,
1646                                           (char __user *) arg3,
1647                                           (size_t) arg4);
1648
1649        case KEYCTL_SESSION_TO_PARENT:
1650                return keyctl_session_to_parent();
1651
1652        case KEYCTL_REJECT:
1653                return keyctl_reject_key((key_serial_t) arg2,
1654                                         (unsigned) arg3,
1655                                         (unsigned) arg4,
1656                                         (key_serial_t) arg5);
1657
1658        case KEYCTL_INSTANTIATE_IOV:
1659                return keyctl_instantiate_key_iov(
1660                        (key_serial_t) arg2,
1661                        (const struct iovec __user *) arg3,
1662                        (unsigned) arg4,
1663                        (key_serial_t) arg5);
1664
1665        case KEYCTL_INVALIDATE:
1666                return keyctl_invalidate_key((key_serial_t) arg2);
1667
1668        default:
1669                return -EOPNOTSUPP;
1670        }
1671}
1672
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