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 <linux/uio.h>
  26#include <asm/uaccess.h>
  27#include "internal.h"
  28
  29#define KEY_MAX_DESC_SIZE 4096
  30
  31static int key_get_type_from_user(char *type,
  32                                  const char __user *_type,
  33                                  unsigned len)
  34{
  35        int ret;
  36
  37        ret = strncpy_from_user(type, _type, len);
  38        if (ret < 0)
  39                return ret;
  40        if (ret == 0 || ret >= len)
  41                return -EINVAL;
  42        if (type[0] == '.')
  43                return -EPERM;
  44        type[len - 1] = '\0';
  45        return 0;
  46}
  47
  48/*
  49 * Extract the description of a new key from userspace and either add it as a
  50 * new key to the specified keyring or update a matching key in that keyring.
  51 *
  52 * If the description is NULL or an empty string, the key type is asked to
  53 * generate one from the payload.
  54 *
  55 * The keyring must be writable so that we can attach the key to it.
  56 *
  57 * If successful, the new key's serial number is returned, otherwise an error
  58 * code is returned.
  59 */
  60SYSCALL_DEFINE5(add_key, const char __user *, _type,
  61                const char __user *, _description,
  62                const void __user *, _payload,
  63                size_t, plen,
  64                key_serial_t, ringid)
  65{
  66        key_ref_t keyring_ref, key_ref;
  67        char type[32], *description;
  68        void *payload;
  69        long ret;
  70
  71        ret = -EINVAL;
  72        if (plen > 1024 * 1024 - 1)
  73                goto error;
  74
  75        /* draw all the data into kernel space */
  76        ret = key_get_type_from_user(type, _type, sizeof(type));
  77        if (ret < 0)
  78                goto error;
  79
  80        description = NULL;
  81        if (_description) {
  82                description = strndup_user(_description, KEY_MAX_DESC_SIZE);
  83                if (IS_ERR(description)) {
  84                        ret = PTR_ERR(description);
  85                        goto error;
  86                }
  87                if (!*description) {
  88                        kfree(description);
  89                        description = NULL;
  90                } else if ((description[0] == '.') &&
  91                           (strncmp(type, "keyring", 7) == 0)) {
  92                        ret = -EPERM;
  93                        goto error2;
  94                }
  95        }
  96
  97        /* pull the payload in if one was supplied */
  98        payload = NULL;
  99
 100        if (_payload) {
 101                ret = -ENOMEM;
 102                payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
 103                if (!payload) {
 104                        if (plen <= PAGE_SIZE)
 105                                goto error2;
 106                        payload = vmalloc(plen);
 107                        if (!payload)
 108                                goto error2;
 109                }
 110
 111                ret = -EFAULT;
 112                if (copy_from_user(payload, _payload, plen) != 0)
 113                        goto error3;
 114        }
 115
 116        /* find the target keyring (which must be writable) */
 117        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 118        if (IS_ERR(keyring_ref)) {
 119                ret = PTR_ERR(keyring_ref);
 120                goto error3;
 121        }
 122
 123        /* create or update the requested key and add it to the target
 124         * keyring */
 125        key_ref = key_create_or_update(keyring_ref, type, description,
 126                                       payload, plen, KEY_PERM_UNDEF,
 127                                       KEY_ALLOC_IN_QUOTA);
 128        if (!IS_ERR(key_ref)) {
 129                ret = key_ref_to_ptr(key_ref)->serial;
 130                key_ref_put(key_ref);
 131        }
 132        else {
 133                ret = PTR_ERR(key_ref);
 134        }
 135
 136        key_ref_put(keyring_ref);
 137 error3:
 138        kvfree(payload);
 139 error2:
 140        kfree(description);
 141 error:
 142        return ret;
 143}
 144
 145/*
 146 * Search the process keyrings and keyring trees linked from those for a
 147 * matching key.  Keyrings must have appropriate Search permission to be
 148 * searched.
 149 *
 150 * If a key is found, it will be attached to the destination keyring if there's
 151 * one specified and the serial number of the key will be returned.
 152 *
 153 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 154 * non-NULL in an attempt to create a key.  The _callout_info string will be
 155 * passed to /sbin/request-key to aid with completing the request.  If the
 156 * _callout_info string is "" then it will be changed to "-".
 157 */
 158SYSCALL_DEFINE4(request_key, const char __user *, _type,
 159                const char __user *, _description,
 160                const char __user *, _callout_info,
 161                key_serial_t, destringid)
 162{
 163        struct key_type *ktype;
 164        struct key *key;
 165        key_ref_t dest_ref;
 166        size_t callout_len;
 167        char type[32], *description, *callout_info;
 168        long ret;
 169
 170        /* pull the type into kernel space */
 171        ret = key_get_type_from_user(type, _type, sizeof(type));
 172        if (ret < 0)
 173                goto error;
 174
 175        /* pull the description into kernel space */
 176        description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 177        if (IS_ERR(description)) {
 178                ret = PTR_ERR(description);
 179                goto error;
 180        }
 181
 182        /* pull the callout info into kernel space */
 183        callout_info = NULL;
 184        callout_len = 0;
 185        if (_callout_info) {
 186                callout_info = strndup_user(_callout_info, PAGE_SIZE);
 187                if (IS_ERR(callout_info)) {
 188                        ret = PTR_ERR(callout_info);
 189                        goto error2;
 190                }
 191                callout_len = strlen(callout_info);
 192        }
 193
 194        /* get the destination keyring if specified */
 195        dest_ref = NULL;
 196        if (destringid) {
 197                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 198                                           KEY_NEED_WRITE);
 199                if (IS_ERR(dest_ref)) {
 200                        ret = PTR_ERR(dest_ref);
 201                        goto error3;
 202                }
 203        }
 204
 205        /* find the key type */
 206        ktype = key_type_lookup(type);
 207        if (IS_ERR(ktype)) {
 208                ret = PTR_ERR(ktype);
 209                goto error4;
 210        }
 211
 212        /* do the search */
 213        key = request_key_and_link(ktype, description, callout_info,
 214                                   callout_len, NULL, key_ref_to_ptr(dest_ref),
 215                                   KEY_ALLOC_IN_QUOTA);
 216        if (IS_ERR(key)) {
 217                ret = PTR_ERR(key);
 218                goto error5;
 219        }
 220
 221        /* wait for the key to finish being constructed */
 222        ret = wait_for_key_construction(key, 1);
 223        if (ret < 0)
 224                goto error6;
 225
 226        ret = key->serial;
 227
 228error6:
 229        key_put(key);
 230error5:
 231        key_type_put(ktype);
 232error4:
 233        key_ref_put(dest_ref);
 234error3:
 235        kfree(callout_info);
 236error2:
 237        kfree(description);
 238error:
 239        return ret;
 240}
 241
 242/*
 243 * Get the ID of the specified process keyring.
 244 *
 245 * The requested keyring must have search permission to be found.
 246 *
 247 * If successful, the ID of the requested keyring will be returned.
 248 */
 249long keyctl_get_keyring_ID(key_serial_t id, int create)
 250{
 251        key_ref_t key_ref;
 252        unsigned long lflags;
 253        long ret;
 254
 255        lflags = create ? KEY_LOOKUP_CREATE : 0;
 256        key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
 257        if (IS_ERR(key_ref)) {
 258                ret = PTR_ERR(key_ref);
 259                goto error;
 260        }
 261
 262        ret = key_ref_to_ptr(key_ref)->serial;
 263        key_ref_put(key_ref);
 264error:
 265        return ret;
 266}
 267
 268/*
 269 * Join a (named) session keyring.
 270 *
 271 * Create and join an anonymous session keyring or join a named session
 272 * keyring, creating it if necessary.  A named session keyring must have Search
 273 * permission for it to be joined.  Session keyrings without this permit will
 274 * be skipped over.
 275 *
 276 * If successful, the ID of the joined session keyring will be returned.
 277 */
 278long keyctl_join_session_keyring(const char __user *_name)
 279{
 280        char *name;
 281        long ret;
 282
 283        /* fetch the name from userspace */
 284        name = NULL;
 285        if (_name) {
 286                name = strndup_user(_name, KEY_MAX_DESC_SIZE);
 287                if (IS_ERR(name)) {
 288                        ret = PTR_ERR(name);
 289                        goto error;
 290                }
 291        }
 292
 293        /* join the session */
 294        ret = join_session_keyring(name);
 295        kfree(name);
 296
 297error:
 298        return ret;
 299}
 300
 301/*
 302 * Update a key's data payload from the given data.
 303 *
 304 * The key must grant the caller Write permission and the key type must support
 305 * updating for this to work.  A negative key can be positively instantiated
 306 * with this call.
 307 *
 308 * If successful, 0 will be returned.  If the key type does not support
 309 * updating, then -EOPNOTSUPP will be returned.
 310 */
 311long keyctl_update_key(key_serial_t id,
 312                       const void __user *_payload,
 313                       size_t plen)
 314{
 315        key_ref_t key_ref;
 316        void *payload;
 317        long ret;
 318
 319        ret = -EINVAL;
 320        if (plen > PAGE_SIZE)
 321                goto error;
 322
 323        /* pull the payload in if one was supplied */
 324        payload = NULL;
 325        if (_payload) {
 326                ret = -ENOMEM;
 327                payload = kmalloc(plen, GFP_KERNEL);
 328                if (!payload)
 329                        goto error;
 330
 331                ret = -EFAULT;
 332                if (copy_from_user(payload, _payload, plen) != 0)
 333                        goto error2;
 334        }
 335
 336        /* find the target key (which must be writable) */
 337        key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
 338        if (IS_ERR(key_ref)) {
 339                ret = PTR_ERR(key_ref);
 340                goto error2;
 341        }
 342
 343        /* update the key */
 344        ret = key_update(key_ref, payload, plen);
 345
 346        key_ref_put(key_ref);
 347error2:
 348        kfree(payload);
 349error:
 350        return ret;
 351}
 352
 353/*
 354 * Revoke a key.
 355 *
 356 * The key must be grant the caller Write or Setattr permission for this to
 357 * work.  The key type should give up its quota claim when revoked.  The key
 358 * and any links to the key will be automatically garbage collected after a
 359 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 360 *
 361 * Keys with KEY_FLAG_KEEP set should not be revoked.
 362 *
 363 * If successful, 0 is returned.
 364 */
 365long keyctl_revoke_key(key_serial_t id)
 366{
 367        key_ref_t key_ref;
 368        struct key *key;
 369        long ret;
 370
 371        key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
 372        if (IS_ERR(key_ref)) {
 373                ret = PTR_ERR(key_ref);
 374                if (ret != -EACCES)
 375                        goto error;
 376                key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
 377                if (IS_ERR(key_ref)) {
 378                        ret = PTR_ERR(key_ref);
 379                        goto error;
 380                }
 381        }
 382
 383        key = key_ref_to_ptr(key_ref);
 384        ret = 0;
 385        if (test_bit(KEY_FLAG_KEEP, &key->flags))
 386                ret = -EPERM;
 387        else
 388                key_revoke(key);
 389
 390        key_ref_put(key_ref);
 391error:
 392        return ret;
 393}
 394
 395/*
 396 * Invalidate a key.
 397 *
 398 * The key must be grant the caller Invalidate permission for this to work.
 399 * The key and any links to the key will be automatically garbage collected
 400 * immediately.
 401 *
 402 * Keys with KEY_FLAG_KEEP set should not be invalidated.
 403 *
 404 * If successful, 0 is returned.
 405 */
 406long keyctl_invalidate_key(key_serial_t id)
 407{
 408        key_ref_t key_ref;
 409        struct key *key;
 410        long ret;
 411
 412        kenter("%d", id);
 413
 414        key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
 415        if (IS_ERR(key_ref)) {
 416                ret = PTR_ERR(key_ref);
 417
 418                /* Root is permitted to invalidate certain special keys */
 419                if (capable(CAP_SYS_ADMIN)) {
 420                        key_ref = lookup_user_key(id, 0, 0);
 421                        if (IS_ERR(key_ref))
 422                                goto error;
 423                        if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
 424                                     &key_ref_to_ptr(key_ref)->flags))
 425                                goto invalidate;
 426                        goto error_put;
 427                }
 428
 429                goto error;
 430        }
 431
 432invalidate:
 433        key = key_ref_to_ptr(key_ref);
 434        ret = 0;
 435        if (test_bit(KEY_FLAG_KEEP, &key->flags))
 436                ret = -EPERM;
 437        else
 438                key_invalidate(key);
 439error_put:
 440        key_ref_put(key_ref);
 441error:
 442        kleave(" = %ld", ret);
 443        return ret;
 444}
 445
 446/*
 447 * Clear the specified keyring, creating an empty process keyring if one of the
 448 * special keyring IDs is used.
 449 *
 450 * The keyring must grant the caller Write permission and not have
 451 * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
 452 */
 453long keyctl_keyring_clear(key_serial_t ringid)
 454{
 455        key_ref_t keyring_ref;
 456        struct key *keyring;
 457        long ret;
 458
 459        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 460        if (IS_ERR(keyring_ref)) {
 461                ret = PTR_ERR(keyring_ref);
 462
 463                /* Root is permitted to invalidate certain special keyrings */
 464                if (capable(CAP_SYS_ADMIN)) {
 465                        keyring_ref = lookup_user_key(ringid, 0, 0);
 466                        if (IS_ERR(keyring_ref))
 467                                goto error;
 468                        if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 469                                     &key_ref_to_ptr(keyring_ref)->flags))
 470                                goto clear;
 471                        goto error_put;
 472                }
 473
 474                goto error;
 475        }
 476
 477clear:
 478        keyring = key_ref_to_ptr(keyring_ref);
 479        if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
 480                ret = -EPERM;
 481        else
 482                ret = keyring_clear(keyring);
 483error_put:
 484        key_ref_put(keyring_ref);
 485error:
 486        return ret;
 487}
 488
 489/*
 490 * Create a link from a keyring to a key if there's no matching key in the
 491 * keyring, otherwise replace the link to the matching key with a link to the
 492 * new key.
 493 *
 494 * The key must grant the caller Link permission and the the keyring must grant
 495 * the caller Write permission.  Furthermore, if an additional link is created,
 496 * the keyring's quota will be extended.
 497 *
 498 * If successful, 0 will be returned.
 499 */
 500long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 501{
 502        key_ref_t keyring_ref, key_ref;
 503        long ret;
 504
 505        keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 506        if (IS_ERR(keyring_ref)) {
 507                ret = PTR_ERR(keyring_ref);
 508                goto error;
 509        }
 510
 511        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
 512        if (IS_ERR(key_ref)) {
 513                ret = PTR_ERR(key_ref);
 514                goto error2;
 515        }
 516
 517        ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 518
 519        key_ref_put(key_ref);
 520error2:
 521        key_ref_put(keyring_ref);
 522error:
 523        return ret;
 524}
 525
 526/*
 527 * Unlink a key from a keyring.
 528 *
 529 * The keyring must grant the caller Write permission for this to work; the key
 530 * itself need not grant the caller anything.  If the last link to a key is
 531 * removed then that key will be scheduled for destruction.
 532 *
 533 * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
 534 *
 535 * If successful, 0 will be returned.
 536 */
 537long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 538{
 539        key_ref_t keyring_ref, key_ref;
 540        struct key *keyring, *key;
 541        long ret;
 542
 543        keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
 544        if (IS_ERR(keyring_ref)) {
 545                ret = PTR_ERR(keyring_ref);
 546                goto error;
 547        }
 548
 549        key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 550        if (IS_ERR(key_ref)) {
 551                ret = PTR_ERR(key_ref);
 552                goto error2;
 553        }
 554
 555        keyring = key_ref_to_ptr(keyring_ref);
 556        key = key_ref_to_ptr(key_ref);
 557        if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
 558            test_bit(KEY_FLAG_KEEP, &key->flags))
 559                ret = -EPERM;
 560        else
 561                ret = key_unlink(keyring, key);
 562
 563        key_ref_put(key_ref);
 564error2:
 565        key_ref_put(keyring_ref);
 566error:
 567        return ret;
 568}
 569
 570/*
 571 * Return a description of a key to userspace.
 572 *
 573 * The key must grant the caller View permission for this to work.
 574 *
 575 * If there's a buffer, we place up to buflen bytes of data into it formatted
 576 * in the following way:
 577 *
 578 *      type;uid;gid;perm;description<NUL>
 579 *
 580 * If successful, we return the amount of description available, irrespective
 581 * of how much we may have copied into the buffer.
 582 */
 583long keyctl_describe_key(key_serial_t keyid,
 584                         char __user *buffer,
 585                         size_t buflen)
 586{
 587        struct key *key, *instkey;
 588        key_ref_t key_ref;
 589        char *infobuf;
 590        long ret;
 591        int desclen, infolen;
 592
 593        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
 594        if (IS_ERR(key_ref)) {
 595                /* viewing a key under construction is permitted if we have the
 596                 * authorisation token handy */
 597                if (PTR_ERR(key_ref) == -EACCES) {
 598                        instkey = key_get_instantiation_authkey(keyid);
 599                        if (!IS_ERR(instkey)) {
 600                                key_put(instkey);
 601                                key_ref = lookup_user_key(keyid,
 602                                                          KEY_LOOKUP_PARTIAL,
 603                                                          0);
 604                                if (!IS_ERR(key_ref))
 605                                        goto okay;
 606                        }
 607                }
 608
 609                ret = PTR_ERR(key_ref);
 610                goto error;
 611        }
 612
 613okay:
 614        key = key_ref_to_ptr(key_ref);
 615        desclen = strlen(key->description);
 616
 617        /* calculate how much information we're going to return */
 618        ret = -ENOMEM;
 619        infobuf = kasprintf(GFP_KERNEL,
 620                            "%s;%d;%d;%08x;",
 621                            key->type->name,
 622                            from_kuid_munged(current_user_ns(), key->uid),
 623                            from_kgid_munged(current_user_ns(), key->gid),
 624                            key->perm);
 625        if (!infobuf)
 626                goto error2;
 627        infolen = strlen(infobuf);
 628        ret = infolen + desclen + 1;
 629
 630        /* consider returning the data */
 631        if (buffer && buflen >= ret) {
 632                if (copy_to_user(buffer, infobuf, infolen) != 0 ||
 633                    copy_to_user(buffer + infolen, key->description,
 634                                 desclen + 1) != 0)
 635                        ret = -EFAULT;
 636        }
 637
 638        kfree(infobuf);
 639error2:
 640        key_ref_put(key_ref);
 641error:
 642        return ret;
 643}
 644
 645/*
 646 * Search the specified keyring and any keyrings it links to for a matching
 647 * key.  Only keyrings that grant the caller Search permission will be searched
 648 * (this includes the starting keyring).  Only keys with Search permission can
 649 * be found.
 650 *
 651 * If successful, the found key will be linked to the destination keyring if
 652 * supplied and the key has Link permission, and the found key ID will be
 653 * returned.
 654 */
 655long keyctl_keyring_search(key_serial_t ringid,
 656                           const char __user *_type,
 657                           const char __user *_description,
 658                           key_serial_t destringid)
 659{
 660        struct key_type *ktype;
 661        key_ref_t keyring_ref, key_ref, dest_ref;
 662        char type[32], *description;
 663        long ret;
 664
 665        /* pull the type and description into kernel space */
 666        ret = key_get_type_from_user(type, _type, sizeof(type));
 667        if (ret < 0)
 668                goto error;
 669
 670        description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 671        if (IS_ERR(description)) {
 672                ret = PTR_ERR(description);
 673                goto error;
 674        }
 675
 676        /* get the keyring at which to begin the search */
 677        keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
 678        if (IS_ERR(keyring_ref)) {
 679                ret = PTR_ERR(keyring_ref);
 680                goto error2;
 681        }
 682
 683        /* get the destination keyring if specified */
 684        dest_ref = NULL;
 685        if (destringid) {
 686                dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 687                                           KEY_NEED_WRITE);
 688                if (IS_ERR(dest_ref)) {
 689                        ret = PTR_ERR(dest_ref);
 690                        goto error3;
 691                }
 692        }
 693
 694        /* find the key type */
 695        ktype = key_type_lookup(type);
 696        if (IS_ERR(ktype)) {
 697                ret = PTR_ERR(ktype);
 698                goto error4;
 699        }
 700
 701        /* do the search */
 702        key_ref = keyring_search(keyring_ref, ktype, description);
 703        if (IS_ERR(key_ref)) {
 704                ret = PTR_ERR(key_ref);
 705
 706                /* treat lack or presence of a negative key the same */
 707                if (ret == -EAGAIN)
 708                        ret = -ENOKEY;
 709                goto error5;
 710        }
 711
 712        /* link the resulting key to the destination keyring if we can */
 713        if (dest_ref) {
 714                ret = key_permission(key_ref, KEY_NEED_LINK);
 715                if (ret < 0)
 716                        goto error6;
 717
 718                ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 719                if (ret < 0)
 720                        goto error6;
 721        }
 722
 723        ret = key_ref_to_ptr(key_ref)->serial;
 724
 725error6:
 726        key_ref_put(key_ref);
 727error5:
 728        key_type_put(ktype);
 729error4:
 730        key_ref_put(dest_ref);
 731error3:
 732        key_ref_put(keyring_ref);
 733error2:
 734        kfree(description);
 735error:
 736        return ret;
 737}
 738
 739/*
 740 * Read a key's payload.
 741 *
 742 * The key must either grant the caller Read permission, or it must grant the
 743 * caller Search permission when searched for from the process keyrings.
 744 *
 745 * If successful, we place up to buflen bytes of data into the buffer, if one
 746 * is provided, and return the amount of data that is available in the key,
 747 * irrespective of how much we copied into the buffer.
 748 */
 749long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 750{
 751        struct key *key;
 752        key_ref_t key_ref;
 753        long ret;
 754
 755        /* find the key first */
 756        key_ref = lookup_user_key(keyid, 0, 0);
 757        if (IS_ERR(key_ref)) {
 758                ret = -ENOKEY;
 759                goto error;
 760        }
 761
 762        key = key_ref_to_ptr(key_ref);
 763
 764        /* see if we can read it directly */
 765        ret = key_permission(key_ref, KEY_NEED_READ);
 766        if (ret == 0)
 767                goto can_read_key;
 768        if (ret != -EACCES)
 769                goto error;
 770
 771        /* we can't; see if it's searchable from this process's keyrings
 772         * - we automatically take account of the fact that it may be
 773         *   dangling off an instantiation key
 774         */
 775        if (!is_key_possessed(key_ref)) {
 776                ret = -EACCES;
 777                goto error2;
 778        }
 779
 780        /* the key is probably readable - now try to read it */
 781can_read_key:
 782        ret = -EOPNOTSUPP;
 783        if (key->type->read) {
 784                /* Read the data with the semaphore held (since we might sleep)
 785                 * to protect against the key being updated or revoked.
 786                 */
 787                down_read(&key->sem);
 788                ret = key_validate(key);
 789                if (ret == 0)
 790                        ret = key->type->read(key, buffer, buflen);
 791                up_read(&key->sem);
 792        }
 793
 794error2:
 795        key_put(key);
 796error:
 797        return ret;
 798}
 799
 800/*
 801 * Change the ownership of a key
 802 *
 803 * The key must grant the caller Setattr permission for this to work, though
 804 * the key need not be fully instantiated yet.  For the UID to be changed, or
 805 * for the GID to be changed to a group the caller is not a member of, the
 806 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 807 * attribute is not changed.
 808 *
 809 * If the UID is to be changed, the new user must have sufficient quota to
 810 * accept the key.  The quota deduction will be removed from the old user to
 811 * the new user should the attribute be changed.
 812 *
 813 * If successful, 0 will be returned.
 814 */
 815long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
 816{
 817        struct key_user *newowner, *zapowner = NULL;
 818        struct key *key;
 819        key_ref_t key_ref;
 820        long ret;
 821        kuid_t uid;
 822        kgid_t gid;
 823
 824        uid = make_kuid(current_user_ns(), user);
 825        gid = make_kgid(current_user_ns(), group);
 826        ret = -EINVAL;
 827        if ((user != (uid_t) -1) && !uid_valid(uid))
 828                goto error;
 829        if ((group != (gid_t) -1) && !gid_valid(gid))
 830                goto error;
 831
 832        ret = 0;
 833        if (user == (uid_t) -1 && group == (gid_t) -1)
 834                goto error;
 835
 836        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 837                                  KEY_NEED_SETATTR);
 838        if (IS_ERR(key_ref)) {
 839                ret = PTR_ERR(key_ref);
 840                goto error;
 841        }
 842
 843        key = key_ref_to_ptr(key_ref);
 844
 845        /* make the changes with the locks held to prevent chown/chown races */
 846        ret = -EACCES;
 847        down_write(&key->sem);
 848
 849        if (!capable(CAP_SYS_ADMIN)) {
 850                /* only the sysadmin can chown a key to some other UID */
 851                if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
 852                        goto error_put;
 853
 854                /* only the sysadmin can set the key's GID to a group other
 855                 * than one of those that the current process subscribes to */
 856                if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
 857                        goto error_put;
 858        }
 859
 860        /* change the UID */
 861        if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
 862                ret = -ENOMEM;
 863                newowner = key_user_lookup(uid);
 864                if (!newowner)
 865                        goto error_put;
 866
 867                /* transfer the quota burden to the new user */
 868                if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 869                        unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
 870                                key_quota_root_maxkeys : key_quota_maxkeys;
 871                        unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
 872                                key_quota_root_maxbytes : key_quota_maxbytes;
 873
 874                        spin_lock(&newowner->lock);
 875                        if (newowner->qnkeys + 1 >= maxkeys ||
 876                            newowner->qnbytes + key->quotalen >= maxbytes ||
 877                            newowner->qnbytes + key->quotalen <
 878                            newowner->qnbytes)
 879                                goto quota_overrun;
 880
 881                        newowner->qnkeys++;
 882                        newowner->qnbytes += key->quotalen;
 883                        spin_unlock(&newowner->lock);
 884
 885                        spin_lock(&key->user->lock);
 886                        key->user->qnkeys--;
 887                        key->user->qnbytes -= key->quotalen;
 888                        spin_unlock(&key->user->lock);
 889                }
 890
 891                atomic_dec(&key->user->nkeys);
 892                atomic_inc(&newowner->nkeys);
 893
 894                if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 895                        atomic_dec(&key->user->nikeys);
 896                        atomic_inc(&newowner->nikeys);
 897                }
 898
 899                zapowner = key->user;
 900                key->user = newowner;
 901                key->uid = uid;
 902        }
 903
 904        /* change the GID */
 905        if (group != (gid_t) -1)
 906                key->gid = gid;
 907
 908        ret = 0;
 909
 910error_put:
 911        up_write(&key->sem);
 912        key_put(key);
 913        if (zapowner)
 914                key_user_put(zapowner);
 915error:
 916        return ret;
 917
 918quota_overrun:
 919        spin_unlock(&newowner->lock);
 920        zapowner = newowner;
 921        ret = -EDQUOT;
 922        goto error_put;
 923}
 924
 925/*
 926 * Change the permission mask on a key.
 927 *
 928 * The key must grant the caller Setattr permission for this to work, though
 929 * the key need not be fully instantiated yet.  If the caller does not have
 930 * sysadmin capability, it may only change the permission on keys that it owns.
 931 */
 932long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 933{
 934        struct key *key;
 935        key_ref_t key_ref;
 936        long ret;
 937
 938        ret = -EINVAL;
 939        if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 940                goto error;
 941
 942        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 943                                  KEY_NEED_SETATTR);
 944        if (IS_ERR(key_ref)) {
 945                ret = PTR_ERR(key_ref);
 946                goto error;
 947        }
 948
 949        key = key_ref_to_ptr(key_ref);
 950
 951        /* make the changes with the locks held to prevent chown/chmod races */
 952        ret = -EACCES;
 953        down_write(&key->sem);
 954
 955        /* if we're not the sysadmin, we can only change a key that we own */
 956        if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
 957                key->perm = perm;
 958                ret = 0;
 959        }
 960
 961        up_write(&key->sem);
 962        key_put(key);
 963error:
 964        return ret;
 965}
 966
 967/*
 968 * Get the destination keyring for instantiation and check that the caller has
 969 * Write permission on it.
 970 */
 971static long get_instantiation_keyring(key_serial_t ringid,
 972                                      struct request_key_auth *rka,
 973                                      struct key **_dest_keyring)
 974{
 975        key_ref_t dkref;
 976
 977        *_dest_keyring = NULL;
 978
 979        /* just return a NULL pointer if we weren't asked to make a link */
 980        if (ringid == 0)
 981                return 0;
 982
 983        /* if a specific keyring is nominated by ID, then use that */
 984        if (ringid > 0) {
 985                dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 986                if (IS_ERR(dkref))
 987                        return PTR_ERR(dkref);
 988                *_dest_keyring = key_ref_to_ptr(dkref);
 989                return 0;
 990        }
 991
 992        if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 993                return -EINVAL;
 994
 995        /* otherwise specify the destination keyring recorded in the
 996         * authorisation key (any KEY_SPEC_*_KEYRING) */
 997        if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 998                *_dest_keyring = key_get(rka->dest_keyring);
 999                return 0;
1000        }
1001
1002        return -ENOKEY;
1003}
1004
1005/*
1006 * Change the request_key authorisation key on the current process.
1007 */
1008static int keyctl_change_reqkey_auth(struct key *key)
1009{
1010        struct cred *new;
1011
1012        new = prepare_creds();
1013        if (!new)
1014                return -ENOMEM;
1015
1016        key_put(new->request_key_auth);
1017        new->request_key_auth = key_get(key);
1018
1019        return commit_creds(new);
1020}
1021
1022/*
1023 * Instantiate a key with the specified payload and link the key into the
1024 * destination keyring if one is given.
1025 *
1026 * The caller must have the appropriate instantiation permit set for this to
1027 * work (see keyctl_assume_authority).  No other permissions are required.
1028 *
1029 * If successful, 0 will be returned.
1030 */
1031long keyctl_instantiate_key_common(key_serial_t id,
1032                                   struct iov_iter *from,
1033                                   key_serial_t ringid)
1034{
1035        const struct cred *cred = current_cred();
1036        struct request_key_auth *rka;
1037        struct key *instkey, *dest_keyring;
1038        size_t plen = from ? iov_iter_count(from) : 0;
1039        void *payload;
1040        long ret;
1041
1042        kenter("%d,,%zu,%d", id, plen, ringid);
1043
1044        if (!plen)
1045                from = NULL;
1046
1047        ret = -EINVAL;
1048        if (plen > 1024 * 1024 - 1)
1049                goto error;
1050
1051        /* the appropriate instantiation authorisation key must have been
1052         * assumed before calling this */
1053        ret = -EPERM;
1054        instkey = cred->request_key_auth;
1055        if (!instkey)
1056                goto error;
1057
1058        rka = instkey->payload.data[0];
1059        if (rka->target_key->serial != id)
1060                goto error;
1061
1062        /* pull the payload in if one was supplied */
1063        payload = NULL;
1064
1065        if (from) {
1066                ret = -ENOMEM;
1067                payload = kmalloc(plen, GFP_KERNEL);
1068                if (!payload) {
1069                        if (plen <= PAGE_SIZE)
1070                                goto error;
1071                        payload = vmalloc(plen);
1072                        if (!payload)
1073                                goto error;
1074                }
1075
1076                ret = -EFAULT;
1077                if (copy_from_iter(payload, plen, from) != plen)
1078                        goto error2;
1079        }
1080
1081        /* find the destination keyring amongst those belonging to the
1082         * requesting task */
1083        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1084        if (ret < 0)
1085                goto error2;
1086
1087        /* instantiate the key and link it into a keyring */
1088        ret = key_instantiate_and_link(rka->target_key, payload, plen,
1089                                       dest_keyring, instkey);
1090
1091        key_put(dest_keyring);
1092
1093        /* discard the assumed authority if it's just been disabled by
1094         * instantiation of the key */
1095        if (ret == 0)
1096                keyctl_change_reqkey_auth(NULL);
1097
1098error2:
1099        kvfree(payload);
1100error:
1101        return ret;
1102}
1103
1104/*
1105 * Instantiate a key with the specified payload and link the key into the
1106 * destination keyring if one is given.
1107 *
1108 * The caller must have the appropriate instantiation permit set for this to
1109 * work (see keyctl_assume_authority).  No other permissions are required.
1110 *
1111 * If successful, 0 will be returned.
1112 */
1113long keyctl_instantiate_key(key_serial_t id,
1114                            const void __user *_payload,
1115                            size_t plen,
1116                            key_serial_t ringid)
1117{
1118        if (_payload && plen) {
1119                struct iovec iov;
1120                struct iov_iter from;
1121                int ret;
1122
1123                ret = import_single_range(WRITE, (void __user *)_payload, plen,
1124                                          &iov, &from);
1125                if (unlikely(ret))
1126                        return ret;
1127
1128                return keyctl_instantiate_key_common(id, &from, ringid);
1129        }
1130
1131        return keyctl_instantiate_key_common(id, NULL, ringid);
1132}
1133
1134/*
1135 * Instantiate a key with the specified multipart payload and link the key into
1136 * the destination keyring if one is given.
1137 *
1138 * The caller must have the appropriate instantiation permit set for this to
1139 * work (see keyctl_assume_authority).  No other permissions are required.
1140 *
1141 * If successful, 0 will be returned.
1142 */
1143long keyctl_instantiate_key_iov(key_serial_t id,
1144                                const struct iovec __user *_payload_iov,
1145                                unsigned ioc,
1146                                key_serial_t ringid)
1147{
1148        struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1149        struct iov_iter from;
1150        long ret;
1151
1152        if (!_payload_iov)
1153                ioc = 0;
1154
1155        ret = import_iovec(WRITE, _payload_iov, ioc,
1156                                    ARRAY_SIZE(iovstack), &iov, &from);
1157        if (ret < 0)
1158                return ret;
1159        ret = keyctl_instantiate_key_common(id, &from, ringid);
1160        kfree(iov);
1161        return ret;
1162}
1163
1164/*
1165 * Negatively instantiate the key with the given timeout (in seconds) and link
1166 * the key into the destination keyring if one is given.
1167 *
1168 * The caller must have the appropriate instantiation permit set for this to
1169 * work (see keyctl_assume_authority).  No other permissions are required.
1170 *
1171 * The key and any links to the key will be automatically garbage collected
1172 * after the timeout expires.
1173 *
1174 * Negative keys are used to rate limit repeated request_key() calls by causing
1175 * them to return -ENOKEY until the negative key expires.
1176 *
1177 * If successful, 0 will be returned.
1178 */
1179long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1180{
1181        return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1182}
1183
1184/*
1185 * Negatively instantiate the key with the given timeout (in seconds) and error
1186 * code and link the key into the destination keyring if one is given.
1187 *
1188 * The caller must have the appropriate instantiation permit set for this to
1189 * work (see keyctl_assume_authority).  No other permissions are required.
1190 *
1191 * The key and any links to the key will be automatically garbage collected
1192 * after the timeout expires.
1193 *
1194 * Negative keys are used to rate limit repeated request_key() calls by causing
1195 * them to return the specified error code until the negative key expires.
1196 *
1197 * If successful, 0 will be returned.
1198 */
1199long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1200                       key_serial_t ringid)
1201{
1202        const struct cred *cred = current_cred();
1203        struct request_key_auth *rka;
1204        struct key *instkey, *dest_keyring;
1205        long ret;
1206
1207        kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1208
1209        /* must be a valid error code and mustn't be a kernel special */
1210        if (error <= 0 ||
1211            error >= MAX_ERRNO ||
1212            error == ERESTARTSYS ||
1213            error == ERESTARTNOINTR ||
1214            error == ERESTARTNOHAND ||
1215            error == ERESTART_RESTARTBLOCK)
1216                return -EINVAL;
1217
1218        /* the appropriate instantiation authorisation key must have been
1219         * assumed before calling this */
1220        ret = -EPERM;
1221        instkey = cred->request_key_auth;
1222        if (!instkey)
1223                goto error;
1224
1225        rka = instkey->payload.data[0];
1226        if (rka->target_key->serial != id)
1227                goto error;
1228
1229        /* find the destination keyring if present (which must also be
1230         * writable) */
1231        ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1232        if (ret < 0)
1233                goto error;
1234
1235        /* instantiate the key and link it into a keyring */
1236        ret = key_reject_and_link(rka->target_key, timeout, error,
1237                                  dest_keyring, instkey);
1238
1239        key_put(dest_keyring);
1240
1241        /* discard the assumed authority if it's just been disabled by
1242         * instantiation of the key */
1243        if (ret == 0)
1244                keyctl_change_reqkey_auth(NULL);
1245
1246error:
1247        return ret;
1248}
1249
1250/*
1251 * Read or set the default keyring in which request_key() will cache keys and
1252 * return the old setting.
1253 *
1254 * If a process keyring is specified then this will be created if it doesn't
1255 * yet exist.  The old setting will be returned if successful.
1256 */
1257long keyctl_set_reqkey_keyring(int reqkey_defl)
1258{
1259        struct cred *new;
1260        int ret, old_setting;
1261
1262        old_setting = current_cred_xxx(jit_keyring);
1263
1264        if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1265                return old_setting;
1266
1267        new = prepare_creds();
1268        if (!new)
1269                return -ENOMEM;
1270
1271        switch (reqkey_defl) {
1272        case KEY_REQKEY_DEFL_THREAD_KEYRING:
1273                ret = install_thread_keyring_to_cred(new);
1274                if (ret < 0)
1275                        goto error;
1276                goto set;
1277
1278        case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1279                ret = install_process_keyring_to_cred(new);
1280                if (ret < 0) {
1281                        if (ret != -EEXIST)
1282                                goto error;
1283                        ret = 0;
1284                }
1285                goto set;
1286
1287        case KEY_REQKEY_DEFL_DEFAULT:
1288        case KEY_REQKEY_DEFL_SESSION_KEYRING:
1289        case KEY_REQKEY_DEFL_USER_KEYRING:
1290        case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1291        case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1292                goto set;
1293
1294        case KEY_REQKEY_DEFL_NO_CHANGE:
1295        case KEY_REQKEY_DEFL_GROUP_KEYRING:
1296        default:
1297                ret = -EINVAL;
1298                goto error;
1299        }
1300
1301set:
1302        new->jit_keyring = reqkey_defl;
1303        commit_creds(new);
1304        return old_setting;
1305error:
1306        abort_creds(new);
1307        return ret;
1308}
1309
1310/*
1311 * Set or clear the timeout on a key.
1312 *
1313 * Either the key must grant the caller Setattr permission or else the caller
1314 * must hold an instantiation authorisation token for the key.
1315 *
1316 * The timeout is either 0 to clear the timeout, or a number of seconds from
1317 * the current time.  The key and any links to the key will be automatically
1318 * garbage collected after the timeout expires.
1319 *
1320 * Keys with KEY_FLAG_KEEP set should not be timed out.
1321 *
1322 * If successful, 0 is returned.
1323 */
1324long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1325{
1326        struct key *key, *instkey;
1327        key_ref_t key_ref;
1328        long ret;
1329
1330        key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1331                                  KEY_NEED_SETATTR);
1332        if (IS_ERR(key_ref)) {
1333                /* setting the timeout on a key under construction is permitted
1334                 * if we have the authorisation token handy */
1335                if (PTR_ERR(key_ref) == -EACCES) {
1336                        instkey = key_get_instantiation_authkey(id);
1337                        if (!IS_ERR(instkey)) {
1338                                key_put(instkey);
1339                                key_ref = lookup_user_key(id,
1340                                                          KEY_LOOKUP_PARTIAL,
1341                                                          0);
1342                                if (!IS_ERR(key_ref))
1343                                        goto okay;
1344                        }
1345                }
1346
1347                ret = PTR_ERR(key_ref);
1348                goto error;
1349        }
1350
1351okay:
1352        key = key_ref_to_ptr(key_ref);
1353        ret = 0;
1354        if (test_bit(KEY_FLAG_KEEP, &key->flags))
1355                ret = -EPERM;
1356        else
1357                key_set_timeout(key, timeout);
1358        key_put(key);
1359
1360error:
1361        return ret;
1362}
1363
1364/*
1365 * Assume (or clear) the authority to instantiate the specified key.
1366 *
1367 * This sets the authoritative token currently in force for key instantiation.
1368 * This must be done for a key to be instantiated.  It has the effect of making
1369 * available all the keys from the caller of the request_key() that created a
1370 * key to request_key() calls made by the caller of this function.
1371 *
1372 * The caller must have the instantiation key in their process keyrings with a
1373 * Search permission grant available to the caller.
1374 *
1375 * If the ID given is 0, then the setting will be cleared and 0 returned.
1376 *
1377 * If the ID given has a matching an authorisation key, then that key will be
1378 * set and its ID will be returned.  The authorisation key can be read to get
1379 * the callout information passed to request_key().
1380 */
1381long keyctl_assume_authority(key_serial_t id)
1382{
1383        struct key *authkey;
1384        long ret;
1385
1386        /* special key IDs aren't permitted */
1387        ret = -EINVAL;
1388        if (id < 0)
1389                goto error;
1390
1391        /* we divest ourselves of authority if given an ID of 0 */
1392        if (id == 0) {
1393                ret = keyctl_change_reqkey_auth(NULL);
1394                goto error;
1395        }
1396
1397        /* attempt to assume the authority temporarily granted to us whilst we
1398         * instantiate the specified key
1399         * - the authorisation key must be in the current task's keyrings
1400         *   somewhere
1401         */
1402        authkey = key_get_instantiation_authkey(id);
1403        if (IS_ERR(authkey)) {
1404                ret = PTR_ERR(authkey);
1405                goto error;
1406        }
1407
1408        ret = keyctl_change_reqkey_auth(authkey);
1409        if (ret < 0)
1410                goto error;
1411        key_put(authkey);
1412
1413        ret = authkey->serial;
1414error:
1415        return ret;
1416}
1417
1418/*
1419 * Get a key's the LSM security label.
1420 *
1421 * The key must grant the caller View permission for this to work.
1422 *
1423 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1424 *
1425 * If successful, the amount of information available will be returned,
1426 * irrespective of how much was copied (including the terminal NUL).
1427 */
1428long keyctl_get_security(key_serial_t keyid,
1429                         char __user *buffer,
1430                         size_t buflen)
1431{
1432        struct key *key, *instkey;
1433        key_ref_t key_ref;
1434        char *context;
1435        long ret;
1436
1437        key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1438        if (IS_ERR(key_ref)) {
1439                if (PTR_ERR(key_ref) != -EACCES)
1440                        return PTR_ERR(key_ref);
1441
1442                /* viewing a key under construction is also permitted if we
1443                 * have the authorisation token handy */
1444                instkey = key_get_instantiation_authkey(keyid);
1445                if (IS_ERR(instkey))
1446                        return PTR_ERR(instkey);
1447                key_put(instkey);
1448
1449                key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1450                if (IS_ERR(key_ref))
1451                        return PTR_ERR(key_ref);
1452        }
1453
1454        key = key_ref_to_ptr(key_ref);
1455        ret = security_key_getsecurity(key, &context);
1456        if (ret == 0) {
1457                /* if no information was returned, give userspace an empty
1458                 * string */
1459                ret = 1;
1460                if (buffer && buflen > 0 &&
1461                    copy_to_user(buffer, "", 1) != 0)
1462                        ret = -EFAULT;
1463        } else if (ret > 0) {
1464                /* return as much data as there's room for */
1465                if (buffer && buflen > 0) {
1466                        if (buflen > ret)
1467                                buflen = ret;
1468
1469                        if (copy_to_user(buffer, context, buflen) != 0)
1470                                ret = -EFAULT;
1471                }
1472
1473                kfree(context);
1474        }
1475
1476        key_ref_put(key_ref);
1477        return ret;
1478}
1479
1480/*
1481 * Attempt to install the calling process's session keyring on the process's
1482 * parent process.
1483 *
1484 * The keyring must exist and must grant the caller LINK permission, and the
1485 * parent process must be single-threaded and must have the same effective
1486 * ownership as this process and mustn't be SUID/SGID.
1487 *
1488 * The keyring will be emplaced on the parent when it next resumes userspace.
1489 *
1490 * If successful, 0 will be returned.
1491 */
1492long keyctl_session_to_parent(void)
1493{
1494        struct task_struct *me, *parent;
1495        const struct cred *mycred, *pcred;
1496        struct callback_head *newwork, *oldwork;
1497        key_ref_t keyring_r;
1498        struct cred *cred;
1499        int ret;
1500
1501        keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1502        if (IS_ERR(keyring_r))
1503                return PTR_ERR(keyring_r);
1504
1505        ret = -ENOMEM;
1506
1507        /* our parent is going to need a new cred struct, a new tgcred struct
1508         * and new security data, so we allocate them here to prevent ENOMEM in
1509         * our parent */
1510        cred = cred_alloc_blank();
1511        if (!cred)
1512                goto error_keyring;
1513        newwork = &cred->rcu;
1514
1515        cred->session_keyring = key_ref_to_ptr(keyring_r);
1516        keyring_r = NULL;
1517        init_task_work(newwork, key_change_session_keyring);
1518
1519        me = current;
1520        rcu_read_lock();
1521        write_lock_irq(&tasklist_lock);
1522
1523        ret = -EPERM;
1524        oldwork = NULL;
1525        parent = me->real_parent;
1526
1527        /* the parent mustn't be init and mustn't be a kernel thread */
1528        if (parent->pid <= 1 || !parent->mm)
1529                goto unlock;
1530
1531        /* the parent must be single threaded */
1532        if (!thread_group_empty(parent))
1533                goto unlock;
1534
1535        /* the parent and the child must have different session keyrings or
1536         * there's no point */
1537        mycred = current_cred();
1538        pcred = __task_cred(parent);
1539        if (mycred == pcred ||
1540            mycred->session_keyring == pcred->session_keyring) {
1541                ret = 0;
1542                goto unlock;
1543        }
1544
1545        /* the parent must have the same effective ownership and mustn't be
1546         * SUID/SGID */
1547        if (!uid_eq(pcred->uid,  mycred->euid) ||
1548            !uid_eq(pcred->euid, mycred->euid) ||
1549            !uid_eq(pcred->suid, mycred->euid) ||
1550            !gid_eq(pcred->gid,  mycred->egid) ||
1551            !gid_eq(pcred->egid, mycred->egid) ||
1552            !gid_eq(pcred->sgid, mycred->egid))
1553                goto unlock;
1554
1555        /* the keyrings must have the same UID */
1556        if ((pcred->session_keyring &&
1557             !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1558            !uid_eq(mycred->session_keyring->uid, mycred->euid))
1559                goto unlock;
1560
1561        /* cancel an already pending keyring replacement */
1562        oldwork = task_work_cancel(parent, key_change_session_keyring);
1563
1564        /* the replacement session keyring is applied just prior to userspace
1565         * restarting */
1566        ret = task_work_add(parent, newwork, true);
1567        if (!ret)
1568                newwork = NULL;
1569unlock:
1570        write_unlock_irq(&tasklist_lock);
1571        rcu_read_unlock();
1572        if (oldwork)
1573                put_cred(container_of(oldwork, struct cred, rcu));
1574        if (newwork)
1575                put_cred(cred);
1576        return ret;
1577
1578error_keyring:
1579        key_ref_put(keyring_r);
1580        return ret;
1581}
1582
1583/*
1584 * The key control system call
1585 */
1586SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1587                unsigned long, arg4, unsigned long, arg5)
1588{
1589        switch (option) {
1590        case KEYCTL_GET_KEYRING_ID:
1591                return keyctl_get_keyring_ID((key_serial_t) arg2,
1592                                             (int) arg3);
1593
1594        case KEYCTL_JOIN_SESSION_KEYRING:
1595                return keyctl_join_session_keyring((const char __user *) arg2);
1596
1597        case KEYCTL_UPDATE:
1598                return keyctl_update_key((key_serial_t) arg2,
1599                                         (const void __user *) arg3,
1600                                         (size_t) arg4);
1601
1602        case KEYCTL_REVOKE:
1603                return keyctl_revoke_key((key_serial_t) arg2);
1604
1605        case KEYCTL_DESCRIBE:
1606                return keyctl_describe_key((key_serial_t) arg2,
1607                                           (char __user *) arg3,
1608                                           (unsigned) arg4);
1609
1610        case KEYCTL_CLEAR:
1611                return keyctl_keyring_clear((key_serial_t) arg2);
1612
1613        case KEYCTL_LINK:
1614                return keyctl_keyring_link((key_serial_t) arg2,
1615                                           (key_serial_t) arg3);
1616
1617        case KEYCTL_UNLINK:
1618                return keyctl_keyring_unlink((key_serial_t) arg2,
1619                                             (key_serial_t) arg3);
1620
1621        case KEYCTL_SEARCH:
1622                return keyctl_keyring_search((key_serial_t) arg2,
1623                                             (const char __user *) arg3,
1624                                             (const char __user *) arg4,
1625                                             (key_serial_t) arg5);
1626
1627        case KEYCTL_READ:
1628                return keyctl_read_key((key_serial_t) arg2,
1629                                       (char __user *) arg3,
1630                                       (size_t) arg4);
1631
1632        case KEYCTL_CHOWN:
1633                return keyctl_chown_key((key_serial_t) arg2,
1634                                        (uid_t) arg3,
1635                                        (gid_t) arg4);
1636
1637        case KEYCTL_SETPERM:
1638                return keyctl_setperm_key((key_serial_t) arg2,
1639                                          (key_perm_t) arg3);
1640
1641        case KEYCTL_INSTANTIATE:
1642                return keyctl_instantiate_key((key_serial_t) arg2,
1643                                              (const void __user *) arg3,
1644                                              (size_t) arg4,
1645                                              (key_serial_t) arg5);
1646
1647        case KEYCTL_NEGATE:
1648                return keyctl_negate_key((key_serial_t) arg2,
1649                                         (unsigned) arg3,
1650                                         (key_serial_t) arg4);
1651
1652        case KEYCTL_SET_REQKEY_KEYRING:
1653                return keyctl_set_reqkey_keyring(arg2);
1654
1655        case KEYCTL_SET_TIMEOUT:
1656                return keyctl_set_timeout((key_serial_t) arg2,
1657                                          (unsigned) arg3);
1658
1659        case KEYCTL_ASSUME_AUTHORITY:
1660                return keyctl_assume_authority((key_serial_t) arg2);
1661
1662        case KEYCTL_GET_SECURITY:
1663                return keyctl_get_security((key_serial_t) arg2,
1664                                           (char __user *) arg3,
1665                                           (size_t) arg4);
1666
1667        case KEYCTL_SESSION_TO_PARENT:
1668                return keyctl_session_to_parent();
1669
1670        case KEYCTL_REJECT:
1671                return keyctl_reject_key((key_serial_t) arg2,
1672                                         (unsigned) arg3,
1673                                         (unsigned) arg4,
1674                                         (key_serial_t) arg5);
1675
1676        case KEYCTL_INSTANTIATE_IOV:
1677                return keyctl_instantiate_key_iov(
1678                        (key_serial_t) arg2,
1679                        (const struct iovec __user *) arg3,
1680                        (unsigned) arg4,
1681                        (key_serial_t) arg5);
1682
1683        case KEYCTL_INVALIDATE:
1684                return keyctl_invalidate_key((key_serial_t) arg2);
1685
1686        case KEYCTL_GET_PERSISTENT:
1687                return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1688
1689        case KEYCTL_DH_COMPUTE:
1690                return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
1691                                         (char __user *) arg3, (size_t) arg4,
1692                                         (void __user *) arg5);
1693
1694        default:
1695                return -EOPNOTSUPP;
1696        }
1697}
1698