security/keys/keyctl.c

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