security/keys/keyctl.c

   1 /* keyctl.c: userspace keyctl operations
   2  *
   3  * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/init.h>
  14 #include <linux/sched.h>
  15 #include <linux/slab.h>
  16 #include <linux/syscalls.h>
  17 #include <linux/keyctl.h>
  18 #include <linux/fs.h>
  19 #include <linux/capability.h>
  20 #include <linux/string.h>
  21 #include <linux/err.h>
  22 #include <linux/vmalloc.h>
  23 #include <linux/security.h>
  24 #include <asm/uaccess.h>
  25 #include "internal.h"
  26
  27 static int key_get_type_from_user(char *type,
  28                                   const char __user *_type,
  29                                   unsigned len)
  30 {
  31         int ret;
  32
  33         ret = strncpy_from_user(type, _type, len);
  34
  35         if (ret < 0)
  36                 return -EFAULT;
  37
  38         if (ret == 0 || ret >= len)
  39                 return -EINVAL;
  40
  41         if (type[0] == '.')
  42                 return -EPERM;
  43
  44         type[len - 1] = '\0';
  45
  46         return 0;
  47 }
  48
  49 /*****************************************************************************/
  50 /*
  51  * extract the description of a new key from userspace and either add it as a
  52  * new key to the specified keyring or update a matching key in that keyring
  53  * - the keyring must be writable
  54  * - returns the new key's serial number
  55  * - implements add_key()
  56  */
  57 SYSCALL_DEFINE5(add_key, const char __user *, _type,
  58                 const char __user *, _description,
  59                 const void __user *, _payload,
  60                 size_t, plen,
  61                 key_serial_t, ringid)
  62 {
  63         key_ref_t keyring_ref, key_ref;
  64         char type[32], *description;
  65         void *payload;
  66         long ret;
  67         bool vm;
  68
  69         ret = -EINVAL;
  70         if (plen > 1024 * 1024 - 1)
  71                 goto error;
  72
  73         /* draw all the data into kernel space */
  74         ret = key_get_type_from_user(type, _type, sizeof(type));
  75         if (ret < 0)
  76                 goto error;
  77
  78         description = strndup_user(_description, PAGE_SIZE);
  79         if (IS_ERR(description)) {
  80                 ret = PTR_ERR(description);
  81                 goto error;
  82         }
  83
  84         /* pull the payload in if one was supplied */
  85         payload = NULL;
  86
  87         vm = false;
  88         if (_payload) {
  89                 ret = -ENOMEM;
  90                 payload = kmalloc(plen, GFP_KERNEL);
  91                 if (!payload) {
  92                         if (plen <= PAGE_SIZE)
  93                                 goto error2;
  94                         vm = true;
  95                         payload = vmalloc(plen);
  96                         if (!payload)
  97                                 goto error2;
  98                 }
  99
 100                 ret = -EFAULT;
 101                 if (copy_from_user(payload, _payload, plen) != 0)
 102                         goto error3;
 103         }
 104
 105         /* find the target keyring (which must be writable) */
 106         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 107         if (IS_ERR(keyring_ref)) {
 108                 ret = PTR_ERR(keyring_ref);
 109                 goto error3;
 110         }
 111
 112         /* create or update the requested key and add it to the target
 113          * keyring */
 114         key_ref = key_create_or_update(keyring_ref, type, description,
 115                                        payload, plen, KEY_PERM_UNDEF,
 116                                        KEY_ALLOC_IN_QUOTA);
 117         if (!IS_ERR(key_ref)) {
 118                 ret = key_ref_to_ptr(key_ref)->serial;
 119                 key_ref_put(key_ref);
 120         }
 121         else {
 122                 ret = PTR_ERR(key_ref);
 123         }
 124
 125         key_ref_put(keyring_ref);
 126  error3:
 127         if (!vm)
 128                 kfree(payload);
 129         else
 130                 vfree(payload);
 131  error2:
 132         kfree(description);
 133  error:
 134         return ret;
 135
 136 } /* end sys_add_key() */
 137
 138 /*****************************************************************************/
 139 /*
 140  * search the process keyrings for a matching key
 141  * - nested keyrings may also be searched if they have Search permission
 142  * - if a key is found, it will be attached to the destination keyring if
 143  *   there's one specified
 144  * - /sbin/request-key will be invoked if _callout_info is non-NULL
 145  *   - the _callout_info string will be passed to /sbin/request-key
 146  *   - if the _callout_info string is empty, it will be rendered as "-"
 147  * - implements request_key()
 148  */
 149 SYSCALL_DEFINE4(request_key, const char __user *, _type,
 150                 const char __user *, _description,
 151                 const char __user *, _callout_info,
 152                 key_serial_t, destringid)
 153 {
 154         struct key_type *ktype;
 155         struct key *key;
 156         key_ref_t dest_ref;
 157         size_t callout_len;
 158         char type[32], *description, *callout_info;
 159         long ret;
 160
 161         /* pull the type into kernel space */
 162         ret = key_get_type_from_user(type, _type, sizeof(type));
 163         if (ret < 0)
 164                 goto error;
 165
 166         /* pull the description into kernel space */
 167         description = strndup_user(_description, PAGE_SIZE);
 168         if (IS_ERR(description)) {
 169                 ret = PTR_ERR(description);
 170                 goto error;
 171         }
 172
 173         /* pull the callout info into kernel space */
 174         callout_info = NULL;
 175         callout_len = 0;
 176         if (_callout_info) {
 177                 callout_info = strndup_user(_callout_info, PAGE_SIZE);
 178                 if (IS_ERR(callout_info)) {
 179                         ret = PTR_ERR(callout_info);
 180                         goto error2;
 181                 }
 182                 callout_len = strlen(callout_info);
 183         }
 184
 185         /* get the destination keyring if specified */
 186         dest_ref = NULL;
 187         if (destringid) {
 188                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 189                                            KEY_WRITE);
 190                 if (IS_ERR(dest_ref)) {
 191                         ret = PTR_ERR(dest_ref);
 192                         goto error3;
 193                 }
 194         }
 195
 196         /* find the key type */
 197         ktype = key_type_lookup(type);
 198         if (IS_ERR(ktype)) {
 199                 ret = PTR_ERR(ktype);
 200                 goto error4;
 201         }
 202
 203         /* do the search */
 204         key = request_key_and_link(ktype, description, callout_info,
 205                                    callout_len, NULL, key_ref_to_ptr(dest_ref),
 206                                    KEY_ALLOC_IN_QUOTA);
 207         if (IS_ERR(key)) {
 208                 ret = PTR_ERR(key);
 209                 goto error5;
 210         }
 211
 212         ret = key->serial;
 213
 214         key_put(key);
 215  error5:
 216         key_type_put(ktype);
 217  error4:
 218         key_ref_put(dest_ref);
 219  error3:
 220         kfree(callout_info);
 221  error2:
 222         kfree(description);
 223  error:
 224         return ret;
 225
 226 } /* end sys_request_key() */
 227
 228 /*****************************************************************************/
 229 /*
 230  * get the ID of the specified process keyring
 231  * - the keyring must have search permission to be found
 232  * - implements keyctl(KEYCTL_GET_KEYRING_ID)
 233  */
 234 long keyctl_get_keyring_ID(key_serial_t id, int create)
 235 {
 236         key_ref_t key_ref;
 237         unsigned long lflags;
 238         long ret;
 239
 240         lflags = create ? KEY_LOOKUP_CREATE : 0;
 241         key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 242         if (IS_ERR(key_ref)) {
 243                 ret = PTR_ERR(key_ref);
 244                 goto error;
 245         }
 246
 247         ret = key_ref_to_ptr(key_ref)->serial;
 248         key_ref_put(key_ref);
 249  error:
 250         return ret;
 251
 252 } /* end keyctl_get_keyring_ID() */
 253
 254 /*****************************************************************************/
 255 /*
 256  * join the session keyring
 257  * - implements keyctl(KEYCTL_JOIN_SESSION_KEYRING)
 258  */
 259 long keyctl_join_session_keyring(const char __user *_name)
 260 {
 261         char *name;
 262         long ret;
 263
 264         /* fetch the name from userspace */
 265         name = NULL;
 266         if (_name) {
 267                 name = strndup_user(_name, PAGE_SIZE);
 268                 if (IS_ERR(name)) {
 269                         ret = PTR_ERR(name);
 270                         goto error;
 271                 }
 272         }
 273
 274         /* join the session */
 275         ret = join_session_keyring(name);
 276         kfree(name);
 277
 278  error:
 279         return ret;
 280
 281 } /* end keyctl_join_session_keyring() */
 282
 283 /*****************************************************************************/
 284 /*
 285  * update a key's data payload
 286  * - the key must be writable
 287  * - implements keyctl(KEYCTL_UPDATE)
 288  */
 289 long keyctl_update_key(key_serial_t id,
 290                        const void __user *_payload,
 291                        size_t plen)
 292 {
 293         key_ref_t key_ref;
 294         void *payload;
 295         long ret;
 296
 297         ret = -EINVAL;
 298         if (plen > PAGE_SIZE)
 299                 goto error;
 300
 301         /* pull the payload in if one was supplied */
 302         payload = NULL;
 303         if (_payload) {
 304                 ret = -ENOMEM;
 305                 payload = kmalloc(plen, GFP_KERNEL);
 306                 if (!payload)
 307                         goto error;
 308
 309                 ret = -EFAULT;
 310                 if (copy_from_user(payload, _payload, plen) != 0)
 311                         goto error2;
 312         }
 313
 314         /* find the target key (which must be writable) */
 315         key_ref = lookup_user_key(id, 0, KEY_WRITE);
 316         if (IS_ERR(key_ref)) {
 317                 ret = PTR_ERR(key_ref);
 318                 goto error2;
 319         }
 320
 321         /* update the key */
 322         ret = key_update(key_ref, payload, plen);
 323
 324         key_ref_put(key_ref);
 325  error2:
 326         kfree(payload);
 327  error:
 328         return ret;
 329
 330 } /* end keyctl_update_key() */
 331
 332 /*****************************************************************************/
 333 /*
 334  * revoke a key
 335  * - the key must be writable
 336  * - implements keyctl(KEYCTL_REVOKE)
 337  */
 338 long keyctl_revoke_key(key_serial_t id)
 339 {
 340         key_ref_t key_ref;
 341         long ret;
 342
 343         key_ref = lookup_user_key(id, 0, KEY_WRITE);
 344         if (IS_ERR(key_ref)) {
 345                 ret = PTR_ERR(key_ref);
 346                 if (ret != -EACCES)
 347                         goto error;
 348                 key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 349                 if (IS_ERR(key_ref)) {
 350                         ret = PTR_ERR(key_ref);
 351                         goto error;
 352                 }
 353         }
 354
 355         key_revoke(key_ref_to_ptr(key_ref));
 356         ret = 0;
 357
 358         key_ref_put(key_ref);
 359  error:
 360         return ret;
 361
 362 } /* end keyctl_revoke_key() */
 363
 364 /*****************************************************************************/
 365 /*
 366  * clear the specified process keyring
 367  * - the keyring must be writable
 368  * - implements keyctl(KEYCTL_CLEAR)
 369  */
 370 long keyctl_keyring_clear(key_serial_t ringid)
 371 {
 372         key_ref_t keyring_ref;
 373         long ret;
 374
 375         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 376         if (IS_ERR(keyring_ref)) {
 377                 ret = PTR_ERR(keyring_ref);
 378                 goto error;
 379         }
 380
 381         ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 382
 383         key_ref_put(keyring_ref);
 384  error:
 385         return ret;
 386
 387 } /* end keyctl_keyring_clear() */
 388
 389 /*****************************************************************************/
 390 /*
 391  * link a key into a keyring
 392  * - the keyring must be writable
 393  * - the key must be linkable
 394  * - implements keyctl(KEYCTL_LINK)
 395  */
 396 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 397 {
 398         key_ref_t keyring_ref, key_ref;
 399         long ret;
 400
 401         keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 402         if (IS_ERR(keyring_ref)) {
 403                 ret = PTR_ERR(keyring_ref);
 404                 goto error;
 405         }
 406
 407         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 408         if (IS_ERR(key_ref)) {
 409                 ret = PTR_ERR(key_ref);
 410                 goto error2;
 411         }
 412
 413         ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 414
 415         key_ref_put(key_ref);
 416  error2:
 417         key_ref_put(keyring_ref);
 418  error:
 419         return ret;
 420
 421 } /* end keyctl_keyring_link() */
 422
 423 /*****************************************************************************/
 424 /*
 425  * unlink the first attachment of a key from a keyring
 426  * - the keyring must be writable
 427  * - we don't need any permissions on the key
 428  * - implements keyctl(KEYCTL_UNLINK)
 429  */
 430 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 431 {
 432         key_ref_t keyring_ref, key_ref;
 433         long ret;
 434
 435         keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 436         if (IS_ERR(keyring_ref)) {
 437                 ret = PTR_ERR(keyring_ref);
 438                 goto error;
 439         }
 440
 441         key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 442         if (IS_ERR(key_ref)) {
 443                 ret = PTR_ERR(key_ref);
 444                 goto error2;
 445         }
 446
 447         ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 448
 449         key_ref_put(key_ref);
 450  error2:
 451         key_ref_put(keyring_ref);
 452  error:
 453         return ret;
 454
 455 } /* end keyctl_keyring_unlink() */
 456
 457 /*****************************************************************************/
 458 /*
 459  * describe a user key
 460  * - the key must have view permission
 461  * - if there's a buffer, we place up to buflen bytes of data into it
 462  * - unless there's an error, we return the amount of description available,
 463  *   irrespective of how much we may have copied
 464  * - the description is formatted thus:
 465  *      type;uid;gid;perm;description<NUL>
 466  * - implements keyctl(KEYCTL_DESCRIBE)
 467  */
 468 long keyctl_describe_key(key_serial_t keyid,
 469                          char __user *buffer,
 470                          size_t buflen)
 471 {
 472         struct key *key, *instkey;
 473         key_ref_t key_ref;
 474         char *tmpbuf;
 475         long ret;
 476
 477         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 478         if (IS_ERR(key_ref)) {
 479                 /* viewing a key under construction is permitted if we have the
 480                  * authorisation token handy */
 481                 if (PTR_ERR(key_ref) == -EACCES) {
 482                         instkey = key_get_instantiation_authkey(keyid);
 483                         if (!IS_ERR(instkey)) {
 484                                 key_put(instkey);
 485                                 key_ref = lookup_user_key(keyid,
 486                                                           KEY_LOOKUP_PARTIAL,
 487                                                           0);
 488                                 if (!IS_ERR(key_ref))
 489                                         goto okay;
 490                         }
 491                 }
 492
 493                 ret = PTR_ERR(key_ref);
 494                 goto error;
 495         }
 496
 497 okay:
 498         /* calculate how much description we're going to return */
 499         ret = -ENOMEM;
 500         tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 501         if (!tmpbuf)
 502                 goto error2;
 503
 504         key = key_ref_to_ptr(key_ref);
 505
 506         ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 507                        "%s;%d;%d;%08x;%s",
 508                        key_ref_to_ptr(key_ref)->type->name,
 509                        key_ref_to_ptr(key_ref)->uid,
 510                        key_ref_to_ptr(key_ref)->gid,
 511                        key_ref_to_ptr(key_ref)->perm,
 512                        key_ref_to_ptr(key_ref)->description ?
 513                        key_ref_to_ptr(key_ref)->description : ""
 514                        );
 515
 516         /* include a NUL char at the end of the data */
 517         if (ret > PAGE_SIZE - 1)
 518                 ret = PAGE_SIZE - 1;
 519         tmpbuf[ret] = 0;
 520         ret++;
 521
 522         /* consider returning the data */
 523         if (buffer && buflen > 0) {
 524                 if (buflen > ret)
 525                         buflen = ret;
 526
 527                 if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 528                         ret = -EFAULT;
 529         }
 530
 531         kfree(tmpbuf);
 532  error2:
 533         key_ref_put(key_ref);
 534  error:
 535         return ret;
 536
 537 } /* end keyctl_describe_key() */
 538
 539 /*****************************************************************************/
 540 /*
 541  * search the specified keyring for a matching key
 542  * - the start keyring must be searchable
 543  * - nested keyrings may also be searched if they are searchable
 544  * - only keys with search permission may be found
 545  * - if a key is found, it will be attached to the destination keyring if
 546  *   there's one specified
 547  * - implements keyctl(KEYCTL_SEARCH)
 548  */
 549 long keyctl_keyring_search(key_serial_t ringid,
 550                            const char __user *_type,
 551                            const char __user *_description,
 552                            key_serial_t destringid)
 553 {
 554         struct key_type *ktype;
 555         key_ref_t keyring_ref, key_ref, dest_ref;
 556         char type[32], *description;
 557         long ret;
 558
 559         /* pull the type and description into kernel space */
 560         ret = key_get_type_from_user(type, _type, sizeof(type));
 561         if (ret < 0)
 562                 goto error;
 563
 564         description = strndup_user(_description, PAGE_SIZE);
 565         if (IS_ERR(description)) {
 566                 ret = PTR_ERR(description);
 567                 goto error;
 568         }
 569
 570         /* get the keyring at which to begin the search */
 571         keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 572         if (IS_ERR(keyring_ref)) {
 573                 ret = PTR_ERR(keyring_ref);
 574                 goto error2;
 575         }
 576
 577         /* get the destination keyring if specified */
 578         dest_ref = NULL;
 579         if (destringid) {
 580                 dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 581                                            KEY_WRITE);
 582                 if (IS_ERR(dest_ref)) {
 583                         ret = PTR_ERR(dest_ref);
 584                         goto error3;
 585                 }
 586         }
 587
 588         /* find the key type */
 589         ktype = key_type_lookup(type);
 590         if (IS_ERR(ktype)) {
 591                 ret = PTR_ERR(ktype);
 592                 goto error4;
 593         }
 594
 595         /* do the search */
 596         key_ref = keyring_search(keyring_ref, ktype, description);
 597         if (IS_ERR(key_ref)) {
 598                 ret = PTR_ERR(key_ref);
 599
 600                 /* treat lack or presence of a negative key the same */
 601                 if (ret == -EAGAIN)
 602                         ret = -ENOKEY;
 603                 goto error5;
 604         }
 605
 606         /* link the resulting key to the destination keyring if we can */
 607         if (dest_ref) {
 608                 ret = key_permission(key_ref, KEY_LINK);
 609                 if (ret < 0)
 610                         goto error6;
 611
 612                 ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 613                 if (ret < 0)
 614                         goto error6;
 615         }
 616
 617         ret = key_ref_to_ptr(key_ref)->serial;
 618
 619  error6:
 620         key_ref_put(key_ref);
 621  error5:
 622         key_type_put(ktype);
 623  error4:
 624         key_ref_put(dest_ref);
 625  error3:
 626         key_ref_put(keyring_ref);
 627  error2:
 628         kfree(description);
 629  error:
 630         return ret;
 631
 632 } /* end keyctl_keyring_search() */
 633
 634 /*****************************************************************************/
 635 /*
 636  * read a user key's payload
 637  * - the keyring must be readable or the key must be searchable from the
 638  *   process's keyrings
 639  * - if there's a buffer, we place up to buflen bytes of data into it
 640  * - unless there's an error, we return the amount of data in the key,
 641  *   irrespective of how much we may have copied
 642  * - implements keyctl(KEYCTL_READ)
 643  */
 644 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 645 {
 646         struct key *key;
 647         key_ref_t key_ref;
 648         long ret;
 649
 650         /* find the key first */
 651         key_ref = lookup_user_key(keyid, 0, 0);
 652         if (IS_ERR(key_ref)) {
 653                 ret = -ENOKEY;
 654                 goto error;
 655         }
 656
 657         key = key_ref_to_ptr(key_ref);
 658
 659         /* see if we can read it directly */
 660         ret = key_permission(key_ref, KEY_READ);
 661         if (ret == 0)
 662                 goto can_read_key;
 663         if (ret != -EACCES)
 664                 goto error;
 665
 666         /* we can't; see if it's searchable from this process's keyrings
 667          * - we automatically take account of the fact that it may be
 668          *   dangling off an instantiation key
 669          */
 670         if (!is_key_possessed(key_ref)) {
 671                 ret = -EACCES;
 672                 goto error2;
 673         }
 674
 675         /* the key is probably readable - now try to read it */
 676  can_read_key:
 677         ret = key_validate(key);
 678         if (ret == 0) {
 679                 ret = -EOPNOTSUPP;
 680                 if (key->type->read) {
 681                         /* read the data with the semaphore held (since we
 682                          * might sleep) */
 683                         down_read(&key->sem);
 684                         ret = key->type->read(key, buffer, buflen);
 685                         up_read(&key->sem);
 686                 }
 687         }
 688
 689  error2:
 690         key_put(key);
 691  error:
 692         return ret;
 693
 694 } /* end keyctl_read_key() */
 695
 696 /*****************************************************************************/
 697 /*
 698  * change the ownership of a key
 699  * - the keyring owned by the changer
 700  * - if the uid or gid is -1, then that parameter is not changed
 701  * - implements keyctl(KEYCTL_CHOWN)
 702  */
 703 long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 704 {
 705         struct key_user *newowner, *zapowner = NULL;
 706         struct key *key;
 707         key_ref_t key_ref;
 708         long ret;
 709
 710         ret = 0;
 711         if (uid == (uid_t) -1 && gid == (gid_t) -1)
 712                 goto error;
 713
 714         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 715                                   KEY_SETATTR);
 716         if (IS_ERR(key_ref)) {
 717                 ret = PTR_ERR(key_ref);
 718                 goto error;
 719         }
 720
 721         key = key_ref_to_ptr(key_ref);
 722
 723         /* make the changes with the locks held to prevent chown/chown races */
 724         ret = -EACCES;
 725         down_write(&key->sem);
 726
 727         if (!capable(CAP_SYS_ADMIN)) {
 728                 /* only the sysadmin can chown a key to some other UID */
 729                 if (uid != (uid_t) -1 && key->uid != uid)
 730                         goto error_put;
 731
 732                 /* only the sysadmin can set the key's GID to a group other
 733                  * than one of those that the current process subscribes to */
 734                 if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 735                         goto error_put;
 736         }
 737
 738         /* change the UID */
 739         if (uid != (uid_t) -1 && uid != key->uid) {
 740                 ret = -ENOMEM;
 741                 newowner = key_user_lookup(uid, current_user_ns());
 742                 if (!newowner)
 743                         goto error_put;
 744
 745                 /* transfer the quota burden to the new user */
 746                 if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 747                         unsigned maxkeys = (uid == 0) ?
 748                                 key_quota_root_maxkeys : key_quota_maxkeys;
 749                         unsigned maxbytes = (uid == 0) ?
 750                                 key_quota_root_maxbytes : key_quota_maxbytes;
 751
 752                         spin_lock(&newowner->lock);
 753                         if (newowner->qnkeys + 1 >= maxkeys ||
 754                             newowner->qnbytes + key->quotalen >= maxbytes ||
 755                             newowner->qnbytes + key->quotalen <
 756                             newowner->qnbytes)
 757                                 goto quota_overrun;
 758
 759                         newowner->qnkeys++;
 760                         newowner->qnbytes += key->quotalen;
 761                         spin_unlock(&newowner->lock);
 762
 763                         spin_lock(&key->user->lock);
 764                         key->user->qnkeys--;
 765                         key->user->qnbytes -= key->quotalen;
 766                         spin_unlock(&key->user->lock);
 767                 }
 768
 769                 atomic_dec(&key->user->nkeys);
 770                 atomic_inc(&newowner->nkeys);
 771
 772                 if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 773                         atomic_dec(&key->user->nikeys);
 774                         atomic_inc(&newowner->nikeys);
 775                 }
 776
 777                 zapowner = key->user;
 778                 key->user = newowner;
 779                 key->uid = uid;
 780         }
 781
 782         /* change the GID */
 783         if (gid != (gid_t) -1)
 784                 key->gid = gid;
 785
 786         ret = 0;
 787
 788 error_put:
 789         up_write(&key->sem);
 790         key_put(key);
 791         if (zapowner)
 792                 key_user_put(zapowner);
 793 error:
 794         return ret;
 795
 796 quota_overrun:
 797         spin_unlock(&newowner->lock);
 798         zapowner = newowner;
 799         ret = -EDQUOT;
 800         goto error_put;
 801
 802 } /* end keyctl_chown_key() */
 803
 804 /*****************************************************************************/
 805 /*
 806  * change the permission mask on a key
 807  * - the keyring owned by the changer
 808  * - implements keyctl(KEYCTL_SETPERM)
 809  */
 810 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 811 {
 812         struct key *key;
 813         key_ref_t key_ref;
 814         long ret;
 815
 816         ret = -EINVAL;
 817         if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 818                 goto error;
 819
 820         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 821                                   KEY_SETATTR);
 822         if (IS_ERR(key_ref)) {
 823                 ret = PTR_ERR(key_ref);
 824                 goto error;
 825         }
 826
 827         key = key_ref_to_ptr(key_ref);
 828
 829         /* make the changes with the locks held to prevent chown/chmod races */
 830         ret = -EACCES;
 831         down_write(&key->sem);
 832
 833         /* if we're not the sysadmin, we can only change a key that we own */
 834         if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 835                 key->perm = perm;
 836                 ret = 0;
 837         }
 838
 839         up_write(&key->sem);
 840         key_put(key);
 841 error:
 842         return ret;
 843
 844 } /* end keyctl_setperm_key() */
 845
 846 /*
 847  * get the destination keyring for instantiation
 848  */
 849 static long get_instantiation_keyring(key_serial_t ringid,
 850                                       struct request_key_auth *rka,
 851                                       struct key **_dest_keyring)
 852 {
 853         key_ref_t dkref;
 854
 855         *_dest_keyring = NULL;
 856
 857         /* just return a NULL pointer if we weren't asked to make a link */
 858         if (ringid == 0)
 859                 return 0;
 860
 861         /* if a specific keyring is nominated by ID, then use that */
 862         if (ringid > 0) {
 863                 dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 864                 if (IS_ERR(dkref))
 865                         return PTR_ERR(dkref);
 866                 *_dest_keyring = key_ref_to_ptr(dkref);
 867                 return 0;
 868         }
 869
 870         if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 871                 return -EINVAL;
 872
 873         /* otherwise specify the destination keyring recorded in the
 874          * authorisation key (any KEY_SPEC_*_KEYRING) */
 875         if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 876                 *_dest_keyring = rka->dest_keyring;
 877                 return 0;
 878         }
 879
 880         return -ENOKEY;
 881 }
 882
 883 /*
 884  * change the request_key authorisation key on the current process
 885  */
 886 static int keyctl_change_reqkey_auth(struct key *key)
 887 {
 888         struct cred *new;
 889
 890         new = prepare_creds();
 891         if (!new)
 892                 return -ENOMEM;
 893
 894         key_put(new->request_key_auth);
 895         new->request_key_auth = key_get(key);
 896
 897         return commit_creds(new);
 898 }
 899
 900 /*****************************************************************************/
 901 /*
 902  * instantiate the key with the specified payload, and, if one is given, link
 903  * the key into the keyring
 904  */
 905 long keyctl_instantiate_key(key_serial_t id,
 906                             const void __user *_payload,
 907                             size_t plen,
 908                             key_serial_t ringid)
 909 {
 910         const struct cred *cred = current_cred();
 911         struct request_key_auth *rka;
 912         struct key *instkey, *dest_keyring;
 913         void *payload;
 914         long ret;
 915         bool vm = false;
 916
 917         kenter("%d,,%zu,%d", id, plen, ringid);
 918
 919         ret = -EINVAL;
 920         if (plen > 1024 * 1024 - 1)
 921                 goto error;
 922
 923         /* the appropriate instantiation authorisation key must have been
 924          * assumed before calling this */
 925         ret = -EPERM;
 926         instkey = cred->request_key_auth;
 927         if (!instkey)
 928                 goto error;
 929
 930         rka = instkey->payload.data;
 931         if (rka->target_key->serial != id)
 932                 goto error;
 933
 934         /* pull the payload in if one was supplied */
 935         payload = NULL;
 936
 937         if (_payload) {
 938                 ret = -ENOMEM;
 939                 payload = kmalloc(plen, GFP_KERNEL);
 940                 if (!payload) {
 941                         if (plen <= PAGE_SIZE)
 942                                 goto error;
 943                         vm = true;
 944                         payload = vmalloc(plen);
 945                         if (!payload)
 946                                 goto error;
 947                 }
 948
 949                 ret = -EFAULT;
 950                 if (copy_from_user(payload, _payload, plen) != 0)
 951                         goto error2;
 952         }
 953
 954         /* find the destination keyring amongst those belonging to the
 955          * requesting task */
 956         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
 957         if (ret < 0)
 958                 goto error2;
 959
 960         /* instantiate the key and link it into a keyring */
 961         ret = key_instantiate_and_link(rka->target_key, payload, plen,
 962                                        dest_keyring, instkey);
 963
 964         key_put(dest_keyring);
 965
 966         /* discard the assumed authority if it's just been disabled by
 967          * instantiation of the key */
 968         if (ret == 0)
 969                 keyctl_change_reqkey_auth(NULL);
 970
 971 error2:
 972         if (!vm)
 973                 kfree(payload);
 974         else
 975                 vfree(payload);
 976 error:
 977         return ret;
 978
 979 } /* end keyctl_instantiate_key() */
 980
 981 /*****************************************************************************/
 982 /*
 983  * negatively instantiate the key with the given timeout (in seconds), and, if
 984  * one is given, link the key into the keyring
 985  */
 986 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
 987 {
 988         const struct cred *cred = current_cred();
 989         struct request_key_auth *rka;
 990         struct key *instkey, *dest_keyring;
 991         long ret;
 992
 993         kenter("%d,%u,%d", id, timeout, ringid);
 994
 995         /* the appropriate instantiation authorisation key must have been
 996          * assumed before calling this */
 997         ret = -EPERM;
 998         instkey = cred->request_key_auth;
 999         if (!instkey)
1000                 goto error;
1001
1002         rka = instkey->payload.data;
1003         if (rka->target_key->serial != id)
1004                 goto error;
1005
1006         /* find the destination keyring if present (which must also be
1007          * writable) */
1008         ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1009         if (ret < 0)
1010                 goto error;
1011
1012         /* instantiate the key and link it into a keyring */
1013         ret = key_negate_and_link(rka->target_key, timeout,
1014                                   dest_keyring, instkey);
1015
1016         key_put(dest_keyring);
1017
1018         /* discard the assumed authority if it's just been disabled by
1019          * instantiation of the key */
1020         if (ret == 0)
1021                 keyctl_change_reqkey_auth(NULL);
1022
1023 error:
1024         return ret;
1025
1026 } /* end keyctl_negate_key() */
1027
1028 /*****************************************************************************/
1029 /*
1030  * set the default keyring in which request_key() will cache keys
1031  * - return the old setting
1032  */
1033 long keyctl_set_reqkey_keyring(int reqkey_defl)
1034 {
1035         struct cred *new;
1036         int ret, old_setting;
1037
1038         old_setting = current_cred_xxx(jit_keyring);
1039
1040         if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1041                 return old_setting;
1042
1043         new = prepare_creds();
1044         if (!new)
1045                 return -ENOMEM;
1046
1047         switch (reqkey_defl) {
1048         case KEY_REQKEY_DEFL_THREAD_KEYRING:
1049                 ret = install_thread_keyring_to_cred(new);
1050                 if (ret < 0)
1051                         goto error;
1052                 goto set;
1053
1054         case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1055                 ret = install_process_keyring_to_cred(new);
1056                 if (ret < 0) {
1057                         if (ret != -EEXIST)
1058                                 goto error;
1059                         ret = 0;
1060                 }
1061                 goto set;
1062
1063         case KEY_REQKEY_DEFL_DEFAULT:
1064         case KEY_REQKEY_DEFL_SESSION_KEYRING:
1065         case KEY_REQKEY_DEFL_USER_KEYRING:
1066         case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1067         case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1068                 goto set;
1069
1070         case KEY_REQKEY_DEFL_NO_CHANGE:
1071         case KEY_REQKEY_DEFL_GROUP_KEYRING:
1072         default:
1073                 ret = -EINVAL;
1074                 goto error;
1075         }
1076
1077 set:
1078         new->jit_keyring = reqkey_defl;
1079         commit_creds(new);
1080         return old_setting;
1081 error:
1082         abort_creds(new);
1083         return -EINVAL;
1084
1085 } /* end keyctl_set_reqkey_keyring() */
1086
1087 /*****************************************************************************/
1088 /*
1089  * set or clear the timeout for a key
1090  */
1091 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1092 {
1093         struct timespec now;
1094         struct key *key;
1095         key_ref_t key_ref;
1096         time_t expiry;
1097         long ret;
1098
1099         key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1100                                   KEY_SETATTR);
1101         if (IS_ERR(key_ref)) {
1102                 ret = PTR_ERR(key_ref);
1103                 goto error;
1104         }
1105
1106         key = key_ref_to_ptr(key_ref);
1107
1108         /* make the changes with the locks held to prevent races */
1109         down_write(&key->sem);
1110
1111         expiry = 0;
1112         if (timeout > 0) {
1113                 now = current_kernel_time();
1114                 expiry = now.tv_sec + timeout;
1115         }
1116
1117         key->expiry = expiry;
1118         key_schedule_gc(key->expiry + key_gc_delay);
1119
1120         up_write(&key->sem);
1121         key_put(key);
1122
1123         ret = 0;
1124 error:
1125         return ret;
1126
1127 } /* end keyctl_set_timeout() */
1128
1129 /*****************************************************************************/
1130 /*
1131  * assume the authority to instantiate the specified key
1132  */
1133 long keyctl_assume_authority(key_serial_t id)
1134 {
1135         struct key *authkey;
1136         long ret;
1137
1138         /* special key IDs aren't permitted */
1139         ret = -EINVAL;
1140         if (id < 0)
1141                 goto error;
1142
1143         /* we divest ourselves of authority if given an ID of 0 */
1144         if (id == 0) {
1145                 ret = keyctl_change_reqkey_auth(NULL);
1146                 goto error;
1147         }
1148
1149         /* attempt to assume the authority temporarily granted to us whilst we
1150          * instantiate the specified key
1151          * - the authorisation key must be in the current task's keyrings
1152          *   somewhere
1153          */
1154         authkey = key_get_instantiation_authkey(id);
1155         if (IS_ERR(authkey)) {
1156                 ret = PTR_ERR(authkey);
1157                 goto error;
1158         }
1159
1160         ret = keyctl_change_reqkey_auth(authkey);
1161         if (ret < 0)
1162                 goto error;
1163         key_put(authkey);
1164
1165         ret = authkey->serial;
1166 error:
1167         return ret;
1168
1169 } /* end keyctl_assume_authority() */
1170
1171 /*
1172  * get the security label of a key
1173  * - the key must grant us view permission
1174  * - if there's a buffer, we place up to buflen bytes of data into it
1175  * - unless there's an error, we return the amount of information available,
1176  *   irrespective of how much we may have copied (including the terminal NUL)
1177  * - implements keyctl(KEYCTL_GET_SECURITY)
1178  */
1179 long keyctl_get_security(key_serial_t keyid,
1180                          char __user *buffer,
1181                          size_t buflen)
1182 {
1183         struct key *key, *instkey;
1184         key_ref_t key_ref;
1185         char *context;
1186         long ret;
1187
1188         key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1189         if (IS_ERR(key_ref)) {
1190                 if (PTR_ERR(key_ref) != -EACCES)
1191                         return PTR_ERR(key_ref);
1192
1193                 /* viewing a key under construction is also permitted if we
1194                  * have the authorisation token handy */
1195                 instkey = key_get_instantiation_authkey(keyid);
1196                 if (IS_ERR(instkey))
1197                         return PTR_ERR(key_ref);
1198                 key_put(instkey);
1199
1200                 key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1201                 if (IS_ERR(key_ref))
1202                         return PTR_ERR(key_ref);
1203         }
1204
1205         key = key_ref_to_ptr(key_ref);
1206         ret = security_key_getsecurity(key, &context);
1207         if (ret == 0) {
1208                 /* if no information was returned, give userspace an empty
1209                  * string */
1210                 ret = 1;
1211                 if (buffer && buflen > 0 &&
1212                     copy_to_user(buffer, "", 1) != 0)
1213                         ret = -EFAULT;
1214         } else if (ret > 0) {
1215                 /* return as much data as there's room for */
1216                 if (buffer && buflen > 0) {
1217                         if (buflen > ret)
1218                                 buflen = ret;
1219
1220                         if (copy_to_user(buffer, context, buflen) != 0)
1221                                 ret = -EFAULT;
1222                 }
1223
1224                 kfree(context);
1225         }
1226
1227         key_ref_put(key_ref);
1228         return ret;
1229 }
1230
1231 /*
1232  * attempt to install the calling process's session keyring on the process's
1233  * parent process
1234  * - the keyring must exist and must grant us LINK permission
1235  * - implements keyctl(KEYCTL_SESSION_TO_PARENT)
1236  */
1237 long keyctl_session_to_parent(void)
1238 {
1239         struct task_struct *me, *parent;
1240         const struct cred *mycred, *pcred;
1241         struct cred *cred, *oldcred;
1242         key_ref_t keyring_r;
1243         int ret;
1244
1245         keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1246         if (IS_ERR(keyring_r))
1247                 return PTR_ERR(keyring_r);
1248
1249         /* our parent is going to need a new cred struct, a new tgcred struct
1250          * and new security data, so we allocate them here to prevent ENOMEM in
1251          * our parent */
1252         ret = -ENOMEM;
1253         cred = cred_alloc_blank();
1254         if (!cred)
1255                 goto error_keyring;
1256
1257         cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1258         keyring_r = NULL;
1259
1260         me = current;
1261         write_lock_irq(&tasklist_lock);
1262
1263         parent = me->real_parent;
1264         ret = -EPERM;
1265
1266         /* the parent mustn't be init and mustn't be a kernel thread */
1267         if (parent->pid <= 1 || !parent->mm)
1268                 goto not_permitted;
1269
1270         /* the parent must be single threaded */
1271         if (atomic_read(&parent->signal->count) != 1)
1272                 goto not_permitted;
1273
1274         /* the parent and the child must have different session keyrings or
1275          * there's no point */
1276         mycred = current_cred();
1277         pcred = __task_cred(parent);
1278         if (mycred == pcred ||
1279             mycred->tgcred->session_keyring == pcred->tgcred->session_keyring)
1280                 goto already_same;
1281
1282         /* the parent must have the same effective ownership and mustn't be
1283          * SUID/SGID */
1284         if (pcred-> uid != mycred->euid ||
1285             pcred->euid != mycred->euid ||
1286             pcred->suid != mycred->euid ||
1287             pcred-> gid != mycred->egid ||
1288             pcred->egid != mycred->egid ||
1289             pcred->sgid != mycred->egid)
1290                 goto not_permitted;
1291
1292         /* the keyrings must have the same UID */
1293         if (pcred ->tgcred->session_keyring->uid != mycred->euid ||
1294             mycred->tgcred->session_keyring->uid != mycred->euid)
1295                 goto not_permitted;
1296
1297         /* the LSM must permit the replacement of the parent's keyring with the
1298          * keyring from this process */
1299         ret = security_key_session_to_parent(mycred, pcred,
1300                                              key_ref_to_ptr(keyring_r));
1301         if (ret < 0)
1302                 goto not_permitted;
1303
1304         /* if there's an already pending keyring replacement, then we replace
1305          * that */
1306         oldcred = parent->replacement_session_keyring;
1307
1308         /* the replacement session keyring is applied just prior to userspace
1309          * restarting */
1310         parent->replacement_session_keyring = cred;
1311         cred = NULL;
1312         set_ti_thread_flag(task_thread_info(parent), TIF_NOTIFY_RESUME);
1313
1314         write_unlock_irq(&tasklist_lock);
1315         if (oldcred)
1316                 put_cred(oldcred);
1317         return 0;
1318
1319 already_same:
1320         ret = 0;
1321 not_permitted:
1322         write_unlock_irq(&tasklist_lock);
1323         put_cred(cred);
1324         return ret;
1325
1326 error_keyring:
1327         key_ref_put(keyring_r);
1328         return ret;
1329 }
1330
1331 /*****************************************************************************/
1332 /*
1333  * the key control system call
1334  */
1335 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1336                 unsigned long, arg4, unsigned long, arg5)
1337 {
1338         switch (option) {
1339         case KEYCTL_GET_KEYRING_ID:
1340                 return keyctl_get_keyring_ID((key_serial_t) arg2,
1341                                              (int) arg3);
1342
1343         case KEYCTL_JOIN_SESSION_KEYRING:
1344                 return keyctl_join_session_keyring((const char __user *) arg2);
1345
1346         case KEYCTL_UPDATE:
1347                 return keyctl_update_key((key_serial_t) arg2,
1348                                          (const void __user *) arg3,
1349                                          (size_t) arg4);
1350
1351         case KEYCTL_REVOKE:
1352                 return keyctl_revoke_key((key_serial_t) arg2);
1353
1354         case KEYCTL_DESCRIBE:
1355                 return keyctl_describe_key((key_serial_t) arg2,
1356                                            (char __user *) arg3,
1357                                            (unsigned) arg4);
1358
1359         case KEYCTL_CLEAR:
1360                 return keyctl_keyring_clear((key_serial_t) arg2);
1361
1362         case KEYCTL_LINK:
1363                 return keyctl_keyring_link((key_serial_t) arg2,
1364                                            (key_serial_t) arg3);
1365
1366         case KEYCTL_UNLINK:
1367                 return keyctl_keyring_unlink((key_serial_t) arg2,
1368                                              (key_serial_t) arg3);
1369
1370         case KEYCTL_SEARCH:
1371                 return keyctl_keyring_search((key_serial_t) arg2,
1372                                              (const char __user *) arg3,
1373                                              (const char __user *) arg4,
1374                                              (key_serial_t) arg5);
1375
1376         case KEYCTL_READ:
1377                 return keyctl_read_key((key_serial_t) arg2,
1378                                        (char __user *) arg3,
1379                                        (size_t) arg4);
1380
1381         case KEYCTL_CHOWN:
1382                 return keyctl_chown_key((key_serial_t) arg2,
1383                                         (uid_t) arg3,
1384                                         (gid_t) arg4);
1385
1386         case KEYCTL_SETPERM:
1387                 return keyctl_setperm_key((key_serial_t) arg2,
1388                                           (key_perm_t) arg3);
1389
1390         case KEYCTL_INSTANTIATE:
1391                 return keyctl_instantiate_key((key_serial_t) arg2,
1392                                               (const void __user *) arg3,
1393                                               (size_t) arg4,
1394                                               (key_serial_t) arg5);
1395
1396         case KEYCTL_NEGATE:
1397                 return keyctl_negate_key((key_serial_t) arg2,
1398                                          (unsigned) arg3,
1399                                          (key_serial_t) arg4);
1400
1401         case KEYCTL_SET_REQKEY_KEYRING:
1402                 return keyctl_set_reqkey_keyring(arg2);
1403
1404         case KEYCTL_SET_TIMEOUT:
1405                 return keyctl_set_timeout((key_serial_t) arg2,
1406                                           (unsigned) arg3);
1407
1408         case KEYCTL_ASSUME_AUTHORITY:
1409                 return keyctl_assume_authority((key_serial_t) arg2);
1410
1411         case KEYCTL_GET_SECURITY:
1412                 return keyctl_get_security((key_serial_t) arg2,
1413                                            (char __user *) arg3,
1414                                            (size_t) arg4);
1415
1416         case KEYCTL_SESSION_TO_PARENT:
1417                 return keyctl_session_to_parent();
1418
1419         default:
1420                 return -EOPNOTSUPP;
1421         }
1422
1423 } /* end sys_keyctl() */