1// SPDX-License-Identifier: GPL-2.0-or-later
   2/* Userspace key control operations
   3 *
   4 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
   5 * Written by David Howells (dhowells@redhat.com)
   6 */
   7
   8#include <linux/init.h>
   9#include <linux/sched.h>
  10#include <linux/sched/task.h>
  11#include <linux/slab.h>
  12#include <linux/syscalls.h>
  13#include <linux/key.h>
  14#include <linux/keyctl.h>
  15#include <linux/fs.h>
  16#include <linux/capability.h>
  17#include <linux/cred.h>
  18#include <linux/string.h>
  19#include <linux/err.h>
  20#include <linux/vmalloc.h>
  21#include <linux/security.h>
  22#include <linux/uio.h>
  23#include <linux/uaccess.h>
  24#include <keys/request_key_auth-type.h>
  25#include "internal.h"
  26
  27#define KEY_MAX_DESC_SIZE 4096
  28
  29static const unsigned char keyrings_capabilities[2] = {
  30	[0] = (KEYCTL_CAPS0_CAPABILITIES |
  31	       (IS_ENABLED(CONFIG_PERSISTENT_KEYRINGS)	? KEYCTL_CAPS0_PERSISTENT_KEYRINGS : 0) |
  32	       (IS_ENABLED(CONFIG_KEY_DH_OPERATIONS)	? KEYCTL_CAPS0_DIFFIE_HELLMAN : 0) |
  33	       (IS_ENABLED(CONFIG_ASYMMETRIC_KEY_TYPE)	? KEYCTL_CAPS0_PUBLIC_KEY : 0) |
  34	       (IS_ENABLED(CONFIG_BIG_KEYS)		? KEYCTL_CAPS0_BIG_KEY : 0) |
  35	       KEYCTL_CAPS0_INVALIDATE |
  36	       KEYCTL_CAPS0_RESTRICT_KEYRING |
  37	       KEYCTL_CAPS0_MOVE
  38	       ),
  39	[1] = (KEYCTL_CAPS1_NS_KEYRING_NAME |
  40	       KEYCTL_CAPS1_NS_KEY_TAG |
  41	       (IS_ENABLED(CONFIG_KEY_NOTIFICATIONS)	? KEYCTL_CAPS1_NOTIFICATIONS : 0)
  42	       ),
  43};
  44
  45static int key_get_type_from_user(char *type,
  46				  const char __user *_type,
  47				  unsigned len)
  48{
  49	int ret;
  50
  51	ret = strncpy_from_user(type, _type, len);
  52	if (ret < 0)
  53		return ret;
  54	if (ret == 0 || ret >= len)
  55		return -EINVAL;
  56	if (type[0] == '.')
  57		return -EPERM;
  58	type[len - 1] = '\0';
  59	return 0;
  60}
  61
  62/*
  63 * Extract the description of a new key from userspace and either add it as a
  64 * new key to the specified keyring or update a matching key in that keyring.
  65 *
  66 * If the description is NULL or an empty string, the key type is asked to
  67 * generate one from the payload.
  68 *
  69 * The keyring must be writable so that we can attach the key to it.
  70 *
  71 * If successful, the new key's serial number is returned, otherwise an error
  72 * code is returned.
  73 */
  74SYSCALL_DEFINE5(add_key, const char __user *, _type,
  75		const char __user *, _description,
  76		const void __user *, _payload,
  77		size_t, plen,
  78		key_serial_t, ringid)
  79{
  80	key_ref_t keyring_ref, key_ref;
  81	char type[32], *description;
  82	void *payload;
  83	long ret;
  84
  85	ret = -EINVAL;
  86	if (plen > 1024 * 1024 - 1)
  87		goto error;
  88
  89	/* draw all the data into kernel space */
  90	ret = key_get_type_from_user(type, _type, sizeof(type));
  91	if (ret < 0)
  92		goto error;
  93
  94	description = NULL;
  95	if (_description) {
  96		description = strndup_user(_description, KEY_MAX_DESC_SIZE);
  97		if (IS_ERR(description)) {
  98			ret = PTR_ERR(description);
  99			goto error;
 100		}
 101		if (!*description) {
 102			kfree(description);
 103			description = NULL;
 104		} else if ((description[0] == '.') &&
 105			   (strncmp(type, "keyring", 7) == 0)) {
 106			ret = -EPERM;
 107			goto error2;
 108		}
 109	}
 110
 111	/* pull the payload in if one was supplied */
 112	payload = NULL;
 113
 114	if (plen) {
 115		ret = -ENOMEM;
 116		payload = kvmalloc(plen, GFP_KERNEL);
 117		if (!payload)
 118			goto error2;
 119
 120		ret = -EFAULT;
 121		if (copy_from_user(payload, _payload, plen) != 0)
 122			goto error3;
 123	}
 124
 125	/* find the target keyring (which must be writable) */
 126	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 127	if (IS_ERR(keyring_ref)) {
 128		ret = PTR_ERR(keyring_ref);
 129		goto error3;
 130	}
 131
 132	/* create or update the requested key and add it to the target
 133	 * keyring */
 134	key_ref = key_create_or_update(keyring_ref, type, description,
 135				       payload, plen, KEY_PERM_UNDEF,
 136				       KEY_ALLOC_IN_QUOTA);
 137	if (!IS_ERR(key_ref)) {
 138		ret = key_ref_to_ptr(key_ref)->serial;
 139		key_ref_put(key_ref);
 140	}
 141	else {
 142		ret = PTR_ERR(key_ref);
 143	}
 144
 145	key_ref_put(keyring_ref);
 146 error3:
 147	kvfree_sensitive(payload, plen);
 148 error2:
 149	kfree(description);
 150 error:
 151	return ret;
 152}
 153
 154/*
 155 * Search the process keyrings and keyring trees linked from those for a
 156 * matching key.  Keyrings must have appropriate Search permission to be
 157 * searched.
 158 *
 159 * If a key is found, it will be attached to the destination keyring if there's
 160 * one specified and the serial number of the key will be returned.
 161 *
 162 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 163 * non-NULL in an attempt to create a key.  The _callout_info string will be
 164 * passed to /sbin/request-key to aid with completing the request.  If the
 165 * _callout_info string is "" then it will be changed to "-".
 166 */
 167SYSCALL_DEFINE4(request_key, const char __user *, _type,
 168		const char __user *, _description,
 169		const char __user *, _callout_info,
 170		key_serial_t, destringid)
 171{
 172	struct key_type *ktype;
 173	struct key *key;
 174	key_ref_t dest_ref;
 175	size_t callout_len;
 176	char type[32], *description, *callout_info;
 177	long ret;
 178
 179	/* pull the type into kernel space */
 180	ret = key_get_type_from_user(type, _type, sizeof(type));
 181	if (ret < 0)
 182		goto error;
 183
 184	/* pull the description into kernel space */
 185	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 186	if (IS_ERR(description)) {
 187		ret = PTR_ERR(description);
 188		goto error;
 189	}
 190
 191	/* pull the callout info into kernel space */
 192	callout_info = NULL;
 193	callout_len = 0;
 194	if (_callout_info) {
 195		callout_info = strndup_user(_callout_info, PAGE_SIZE);
 196		if (IS_ERR(callout_info)) {
 197			ret = PTR_ERR(callout_info);
 198			goto error2;
 199		}
 200		callout_len = strlen(callout_info);
 201	}
 202
 203	/* get the destination keyring if specified */
 204	dest_ref = NULL;
 205	if (destringid) {
 206		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 207					   KEY_NEED_WRITE);
 208		if (IS_ERR(dest_ref)) {
 209			ret = PTR_ERR(dest_ref);
 210			goto error3;
 211		}
 212	}
 213
 214	/* find the key type */
 215	ktype = key_type_lookup(type);
 216	if (IS_ERR(ktype)) {
 217		ret = PTR_ERR(ktype);
 218		goto error4;
 219	}
 220
 221	/* do the search */
 222	key = request_key_and_link(ktype, description, NULL, callout_info,
 223				   callout_len, NULL, key_ref_to_ptr(dest_ref),
 224				   KEY_ALLOC_IN_QUOTA);
 225	if (IS_ERR(key)) {
 226		ret = PTR_ERR(key);
 227		goto error5;
 228	}
 229
 230	/* wait for the key to finish being constructed */
 231	ret = wait_for_key_construction(key, 1);
 232	if (ret < 0)
 233		goto error6;
 234
 235	ret = key->serial;
 236
 237error6:
 238 	key_put(key);
 239error5:
 240	key_type_put(ktype);
 241error4:
 242	key_ref_put(dest_ref);
 243error3:
 244	kfree(callout_info);
 245error2:
 246	kfree(description);
 247error:
 248	return ret;
 249}
 250
 251/*
 252 * Get the ID of the specified process keyring.
 253 *
 254 * The requested keyring must have search permission to be found.
 255 *
 256 * If successful, the ID of the requested keyring will be returned.
 257 */
 258long keyctl_get_keyring_ID(key_serial_t id, int create)
 259{
 260	key_ref_t key_ref;
 261	unsigned long lflags;
 262	long ret;
 263
 264	lflags = create ? KEY_LOOKUP_CREATE : 0;
 265	key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
 266	if (IS_ERR(key_ref)) {
 267		ret = PTR_ERR(key_ref);
 268		goto error;
 269	}
 270
 271	ret = key_ref_to_ptr(key_ref)->serial;
 272	key_ref_put(key_ref);
 273error:
 274	return ret;
 275}
 276
 277/*
 278 * Join a (named) session keyring.
 279 *
 280 * Create and join an anonymous session keyring or join a named session
 281 * keyring, creating it if necessary.  A named session keyring must have Search
 282 * permission for it to be joined.  Session keyrings without this permit will
 283 * be skipped over.  It is not permitted for userspace to create or join
 284 * keyrings whose name begin with a dot.
 285 *
 286 * If successful, the ID of the joined session keyring will be returned.
 287 */
 288long keyctl_join_session_keyring(const char __user *_name)
 289{
 290	char *name;
 291	long ret;
 292
 293	/* fetch the name from userspace */
 294	name = NULL;
 295	if (_name) {
 296		name = strndup_user(_name, KEY_MAX_DESC_SIZE);
 297		if (IS_ERR(name)) {
 298			ret = PTR_ERR(name);
 299			goto error;
 300		}
 301
 302		ret = -EPERM;
 303		if (name[0] == '.')
 304			goto error_name;
 305	}
 306
 307	/* join the session */
 308	ret = join_session_keyring(name);
 309error_name:
 310	kfree(name);
 311error:
 312	return ret;
 313}
 314
 315/*
 316 * Update a key's data payload from the given data.
 317 *
 318 * The key must grant the caller Write permission and the key type must support
 319 * updating for this to work.  A negative key can be positively instantiated
 320 * with this call.
 321 *
 322 * If successful, 0 will be returned.  If the key type does not support
 323 * updating, then -EOPNOTSUPP will be returned.
 324 */
 325long keyctl_update_key(key_serial_t id,
 326		       const void __user *_payload,
 327		       size_t plen)
 328{
 329	key_ref_t key_ref;
 330	void *payload;
 331	long ret;
 332
 333	ret = -EINVAL;
 334	if (plen > PAGE_SIZE)
 335		goto error;
 336
 337	/* pull the payload in if one was supplied */
 338	payload = NULL;
 339	if (plen) {
 340		ret = -ENOMEM;
 341		payload = kvmalloc(plen, GFP_KERNEL);
 342		if (!payload)
 343			goto error;
 344
 345		ret = -EFAULT;
 346		if (copy_from_user(payload, _payload, plen) != 0)
 347			goto error2;
 348	}
 349
 350	/* find the target key (which must be writable) */
 351	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
 352	if (IS_ERR(key_ref)) {
 353		ret = PTR_ERR(key_ref);
 354		goto error2;
 355	}
 356
 357	/* update the key */
 358	ret = key_update(key_ref, payload, plen);
 359
 360	key_ref_put(key_ref);
 361error2:
 362	kvfree_sensitive(payload, plen);
 363error:
 364	return ret;
 365}
 366
 367/*
 368 * Revoke a key.
 369 *
 370 * The key must be grant the caller Write or Setattr permission for this to
 371 * work.  The key type should give up its quota claim when revoked.  The key
 372 * and any links to the key will be automatically garbage collected after a
 373 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 374 *
 375 * Keys with KEY_FLAG_KEEP set should not be revoked.
 376 *
 377 * If successful, 0 is returned.
 378 */
 379long keyctl_revoke_key(key_serial_t id)
 380{
 381	key_ref_t key_ref;
 382	struct key *key;
 383	long ret;
 384
 385	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
 386	if (IS_ERR(key_ref)) {
 387		ret = PTR_ERR(key_ref);
 388		if (ret != -EACCES)
 389			goto error;
 390		key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
 391		if (IS_ERR(key_ref)) {
 392			ret = PTR_ERR(key_ref);
 393			goto error;
 394		}
 395	}
 396
 397	key = key_ref_to_ptr(key_ref);
 398	ret = 0;
 399	if (test_bit(KEY_FLAG_KEEP, &key->flags))
 400		ret = -EPERM;
 401	else
 402		key_revoke(key);
 403
 404	key_ref_put(key_ref);
 405error:
 406	return ret;
 407}
 408
 409/*
 410 * Invalidate a key.
 411 *
 412 * The key must be grant the caller Invalidate permission for this to work.
 413 * The key and any links to the key will be automatically garbage collected
 414 * immediately.
 415 *
 416 * Keys with KEY_FLAG_KEEP set should not be invalidated.
 417 *
 418 * If successful, 0 is returned.
 419 */
 420long keyctl_invalidate_key(key_serial_t id)
 421{
 422	key_ref_t key_ref;
 423	struct key *key;
 424	long ret;
 425
 426	kenter("%d", id);
 427
 428	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
 429	if (IS_ERR(key_ref)) {
 430		ret = PTR_ERR(key_ref);
 431
 432		/* Root is permitted to invalidate certain special keys */
 433		if (capable(CAP_SYS_ADMIN)) {
 434			key_ref = lookup_user_key(id, 0, KEY_SYSADMIN_OVERRIDE);
 435			if (IS_ERR(key_ref))
 436				goto error;
 437			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
 438				     &key_ref_to_ptr(key_ref)->flags))
 439				goto invalidate;
 440			goto error_put;
 441		}
 442
 443		goto error;
 444	}
 445
 446invalidate:
 447	key = key_ref_to_ptr(key_ref);
 448	ret = 0;
 449	if (test_bit(KEY_FLAG_KEEP, &key->flags))
 450		ret = -EPERM;
 451	else
 452		key_invalidate(key);
 453error_put:
 454	key_ref_put(key_ref);
 455error:
 456	kleave(" = %ld", ret);
 457	return ret;
 458}
 459
 460/*
 461 * Clear the specified keyring, creating an empty process keyring if one of the
 462 * special keyring IDs is used.
 463 *
 464 * The keyring must grant the caller Write permission and not have
 465 * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
 466 */
 467long keyctl_keyring_clear(key_serial_t ringid)
 468{
 469	key_ref_t keyring_ref;
 470	struct key *keyring;
 471	long ret;
 472
 473	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 474	if (IS_ERR(keyring_ref)) {
 475		ret = PTR_ERR(keyring_ref);
 476
 477		/* Root is permitted to invalidate certain special keyrings */
 478		if (capable(CAP_SYS_ADMIN)) {
 479			keyring_ref = lookup_user_key(ringid, 0,
 480						      KEY_SYSADMIN_OVERRIDE);
 481			if (IS_ERR(keyring_ref))
 482				goto error;
 483			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 484				     &key_ref_to_ptr(keyring_ref)->flags))
 485				goto clear;
 486			goto error_put;
 487		}
 488
 489		goto error;
 490	}
 491
 492clear:
 493	keyring = key_ref_to_ptr(keyring_ref);
 494	if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
 495		ret = -EPERM;
 496	else
 497		ret = keyring_clear(keyring);
 498error_put:
 499	key_ref_put(keyring_ref);
 500error:
 501	return ret;
 502}
 503
 504/*
 505 * Create a link from a keyring to a key if there's no matching key in the
 506 * keyring, otherwise replace the link to the matching key with a link to the
 507 * new key.
 508 *
 509 * The key must grant the caller Link permission and the the keyring must grant
 510 * the caller Write permission.  Furthermore, if an additional link is created,
 511 * the keyring's quota will be extended.
 512 *
 513 * If successful, 0 will be returned.
 514 */
 515long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 516{
 517	key_ref_t keyring_ref, key_ref;
 518	long ret;
 519
 520	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 521	if (IS_ERR(keyring_ref)) {
 522		ret = PTR_ERR(keyring_ref);
 523		goto error;
 524	}
 525
 526	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
 527	if (IS_ERR(key_ref)) {
 528		ret = PTR_ERR(key_ref);
 529		goto error2;
 530	}
 531
 532	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 533
 534	key_ref_put(key_ref);
 535error2:
 536	key_ref_put(keyring_ref);
 537error:
 538	return ret;
 539}
 540
 541/*
 542 * Unlink a key from a keyring.
 543 *
 544 * The keyring must grant the caller Write permission for this to work; the key
 545 * itself need not grant the caller anything.  If the last link to a key is
 546 * removed then that key will be scheduled for destruction.
 547 *
 548 * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
 549 *
 550 * If successful, 0 will be returned.
 551 */
 552long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 553{
 554	key_ref_t keyring_ref, key_ref;
 555	struct key *keyring, *key;
 556	long ret;
 557
 558	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
 559	if (IS_ERR(keyring_ref)) {
 560		ret = PTR_ERR(keyring_ref);
 561		goto error;
 562	}
 563
 564	key_ref = lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_UNLINK);
 565	if (IS_ERR(key_ref)) {
 566		ret = PTR_ERR(key_ref);
 567		goto error2;
 568	}
 569
 570	keyring = key_ref_to_ptr(keyring_ref);
 571	key = key_ref_to_ptr(key_ref);
 572	if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
 573	    test_bit(KEY_FLAG_KEEP, &key->flags))
 574		ret = -EPERM;
 575	else
 576		ret = key_unlink(keyring, key);
 577
 578	key_ref_put(key_ref);
 579error2:
 580	key_ref_put(keyring_ref);
 581error:
 582	return ret;
 583}
 584
 585/*
 586 * Move a link to a key from one keyring to another, displacing any matching
 587 * key from the destination keyring.
 588 *
 589 * The key must grant the caller Link permission and both keyrings must grant
 590 * the caller Write permission.  There must also be a link in the from keyring
 591 * to the key.  If both keyrings are the same, nothing is done.
 592 *
 593 * If successful, 0 will be returned.
 594 */
 595long keyctl_keyring_move(key_serial_t id, key_serial_t from_ringid,
 596			 key_serial_t to_ringid, unsigned int flags)
 597{
 598	key_ref_t key_ref, from_ref, to_ref;
 599	long ret;
 600
 601	if (flags & ~KEYCTL_MOVE_EXCL)
 602		return -EINVAL;
 603
 604	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
 605	if (IS_ERR(key_ref))
 606		return PTR_ERR(key_ref);
 607
 608	from_ref = lookup_user_key(from_ringid, 0, KEY_NEED_WRITE);
 609	if (IS_ERR(from_ref)) {
 610		ret = PTR_ERR(from_ref);
 611		goto error2;
 612	}
 613
 614	to_ref = lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 615	if (IS_ERR(to_ref)) {
 616		ret = PTR_ERR(to_ref);
 617		goto error3;
 618	}
 619
 620	ret = key_move(key_ref_to_ptr(key_ref), key_ref_to_ptr(from_ref),
 621		       key_ref_to_ptr(to_ref), flags);
 622
 623	key_ref_put(to_ref);
 624error3:
 625	key_ref_put(from_ref);
 626error2:
 627	key_ref_put(key_ref);
 628	return ret;
 629}
 630
 631/*
 632 * Return a description of a key to userspace.
 633 *
 634 * The key must grant the caller View permission for this to work.
 635 *
 636 * If there's a buffer, we place up to buflen bytes of data into it formatted
 637 * in the following way:
 638 *
 639 *	type;uid;gid;perm;description<NUL>
 640 *
 641 * If successful, we return the amount of description available, irrespective
 642 * of how much we may have copied into the buffer.
 643 */
 644long keyctl_describe_key(key_serial_t keyid,
 645			 char __user *buffer,
 646			 size_t buflen)
 647{
 648	struct key *key, *instkey;
 649	key_ref_t key_ref;
 650	char *infobuf;
 651	long ret;
 652	int desclen, infolen;
 653
 654	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
 655	if (IS_ERR(key_ref)) {
 656		/* viewing a key under construction is permitted if we have the
 657		 * authorisation token handy */
 658		if (PTR_ERR(key_ref) == -EACCES) {
 659			instkey = key_get_instantiation_authkey(keyid);
 660			if (!IS_ERR(instkey)) {
 661				key_put(instkey);
 662				key_ref = lookup_user_key(keyid,
 663							  KEY_LOOKUP_PARTIAL,
 664							  KEY_AUTHTOKEN_OVERRIDE);
 665				if (!IS_ERR(key_ref))
 666					goto okay;
 667			}
 668		}
 669
 670		ret = PTR_ERR(key_ref);
 671		goto error;
 672	}
 673
 674okay:
 675	key = key_ref_to_ptr(key_ref);
 676	desclen = strlen(key->description);
 677
 678	/* calculate how much information we're going to return */
 679	ret = -ENOMEM;
 680	infobuf = kasprintf(GFP_KERNEL,
 681			    "%s;%d;%d;%08x;",
 682			    key->type->name,
 683			    from_kuid_munged(current_user_ns(), key->uid),
 684			    from_kgid_munged(current_user_ns(), key->gid),
 685			    key->perm);
 686	if (!infobuf)
 687		goto error2;
 688	infolen = strlen(infobuf);
 689	ret = infolen + desclen + 1;
 690
 691	/* consider returning the data */
 692	if (buffer && buflen >= ret) {
 693		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
 694		    copy_to_user(buffer + infolen, key->description,
 695				 desclen + 1) != 0)
 696			ret = -EFAULT;
 697	}
 698
 699	kfree(infobuf);
 700error2:
 701	key_ref_put(key_ref);
 702error:
 703	return ret;
 704}
 705
 706/*
 707 * Search the specified keyring and any keyrings it links to for a matching
 708 * key.  Only keyrings that grant the caller Search permission will be searched
 709 * (this includes the starting keyring).  Only keys with Search permission can
 710 * be found.
 711 *
 712 * If successful, the found key will be linked to the destination keyring if
 713 * supplied and the key has Link permission, and the found key ID will be
 714 * returned.
 715 */
 716long keyctl_keyring_search(key_serial_t ringid,
 717			   const char __user *_type,
 718			   const char __user *_description,
 719			   key_serial_t destringid)
 720{
 721	struct key_type *ktype;
 722	key_ref_t keyring_ref, key_ref, dest_ref;
 723	char type[32], *description;
 724	long ret;
 725
 726	/* pull the type and description into kernel space */
 727	ret = key_get_type_from_user(type, _type, sizeof(type));
 728	if (ret < 0)
 729		goto error;
 730
 731	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 732	if (IS_ERR(description)) {
 733		ret = PTR_ERR(description);
 734		goto error;
 735	}
 736
 737	/* get the keyring at which to begin the search */
 738	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
 739	if (IS_ERR(keyring_ref)) {
 740		ret = PTR_ERR(keyring_ref);
 741		goto error2;
 742	}
 743
 744	/* get the destination keyring if specified */
 745	dest_ref = NULL;
 746	if (destringid) {
 747		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 748					   KEY_NEED_WRITE);
 749		if (IS_ERR(dest_ref)) {
 750			ret = PTR_ERR(dest_ref);
 751			goto error3;
 752		}
 753	}
 754
 755	/* find the key type */
 756	ktype = key_type_lookup(type);
 757	if (IS_ERR(ktype)) {
 758		ret = PTR_ERR(ktype);
 759		goto error4;
 760	}
 761
 762	/* do the search */
 763	key_ref = keyring_search(keyring_ref, ktype, description, true);
 764	if (IS_ERR(key_ref)) {
 765		ret = PTR_ERR(key_ref);
 766
 767		/* treat lack or presence of a negative key the same */
 768		if (ret == -EAGAIN)
 769			ret = -ENOKEY;
 770		goto error5;
 771	}
 772
 773	/* link the resulting key to the destination keyring if we can */
 774	if (dest_ref) {
 775		ret = key_permission(key_ref, KEY_NEED_LINK);
 776		if (ret < 0)
 777			goto error6;
 778
 779		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 780		if (ret < 0)
 781			goto error6;
 782	}
 783
 784	ret = key_ref_to_ptr(key_ref)->serial;
 785
 786error6:
 787	key_ref_put(key_ref);
 788error5:
 789	key_type_put(ktype);
 790error4:
 791	key_ref_put(dest_ref);
 792error3:
 793	key_ref_put(keyring_ref);
 794error2:
 795	kfree(description);
 796error:
 797	return ret;
 798}
 799
 800/*
 801 * Call the read method
 802 */
 803static long __keyctl_read_key(struct key *key, char *buffer, size_t buflen)
 804{
 805	long ret;
 806
 807	down_read(&key->sem);
 808	ret = key_validate(key);
 809	if (ret == 0)
 810		ret = key->type->read(key, buffer, buflen);
 811	up_read(&key->sem);
 812	return ret;
 813}
 814
 815/*
 816 * Read a key's payload.
 817 *
 818 * The key must either grant the caller Read permission, or it must grant the
 819 * caller Search permission when searched for from the process keyrings.
 820 *
 821 * If successful, we place up to buflen bytes of data into the buffer, if one
 822 * is provided, and return the amount of data that is available in the key,
 823 * irrespective of how much we copied into the buffer.
 824 */
 825long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 826{
 827	struct key *key;
 828	key_ref_t key_ref;
 829	long ret;
 830	char *key_data = NULL;
 831	size_t key_data_len;
 832
 833	/* find the key first */
 834	key_ref = lookup_user_key(keyid, 0, KEY_DEFER_PERM_CHECK);
 835	if (IS_ERR(key_ref)) {
 836		ret = -ENOKEY;
 837		goto out;
 838	}
 839
 840	key = key_ref_to_ptr(key_ref);
 841
 842	ret = key_read_state(key);
 843	if (ret < 0)
 844		goto key_put_out; /* Negatively instantiated */
 845
 846	/* see if we can read it directly */
 847	ret = key_permission(key_ref, KEY_NEED_READ);
 848	if (ret == 0)
 849		goto can_read_key;
 850	if (ret != -EACCES)
 851		goto key_put_out;
 852
 853	/* we can't; see if it's searchable from this process's keyrings
 854	 * - we automatically take account of the fact that it may be
 855	 *   dangling off an instantiation key
 856	 */
 857	if (!is_key_possessed(key_ref)) {
 858		ret = -EACCES;
 859		goto key_put_out;
 860	}
 861
 862	/* the key is probably readable - now try to read it */
 863can_read_key:
 864	if (!key->type->read) {
 865		ret = -EOPNOTSUPP;
 866		goto key_put_out;
 867	}
 868
 869	if (!buffer || !buflen) {
 870		/* Get the key length from the read method */
 871		ret = __keyctl_read_key(key, NULL, 0);
 872		goto key_put_out;
 873	}
 874
 875	/*
 876	 * Read the data with the semaphore held (since we might sleep)
 877	 * to protect against the key being updated or revoked.
 878	 *
 879	 * Allocating a temporary buffer to hold the keys before
 880	 * transferring them to user buffer to avoid potential
 881	 * deadlock involving page fault and mmap_lock.
 882	 *
 883	 * key_data_len = (buflen <= PAGE_SIZE)
 884	 *		? buflen : actual length of key data
 885	 *
 886	 * This prevents allocating arbitrary large buffer which can
 887	 * be much larger than the actual key length. In the latter case,
 888	 * at least 2 passes of this loop is required.
 889	 */
 890	key_data_len = (buflen <= PAGE_SIZE) ? buflen : 0;
 891	for (;;) {
 892		if (key_data_len) {
 893			key_data = kvmalloc(key_data_len, GFP_KERNEL);
 894			if (!key_data) {
 895				ret = -ENOMEM;
 896				goto key_put_out;
 897			}
 898		}
 899
 900		ret = __keyctl_read_key(key, key_data, key_data_len);
 901
 902		/*
 903		 * Read methods will just return the required length without
 904		 * any copying if the provided length isn't large enough.
 905		 */
 906		if (ret <= 0 || ret > buflen)
 907			break;
 908
 909		/*
 910		 * The key may change (unlikely) in between 2 consecutive
 911		 * __keyctl_read_key() calls. In this case, we reallocate
 912		 * a larger buffer and redo the key read when
 913		 * key_data_len < ret <= buflen.
 914		 */
 915		if (ret > key_data_len) {
 916			if (unlikely(key_data))
 917				kvfree_sensitive(key_data, key_data_len);
 918			key_data_len = ret;
 919			continue;	/* Allocate buffer */
 920		}
 921
 922		if (copy_to_user(buffer, key_data, ret))
 923			ret = -EFAULT;
 924		break;
 925	}
 926	kvfree_sensitive(key_data, key_data_len);
 927
 928key_put_out:
 929	key_put(key);
 930out:
 931	return ret;
 932}
 933
 934/*
 935 * Change the ownership of a key
 936 *
 937 * The key must grant the caller Setattr permission for this to work, though
 938 * the key need not be fully instantiated yet.  For the UID to be changed, or
 939 * for the GID to be changed to a group the caller is not a member of, the
 940 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 941 * attribute is not changed.
 942 *
 943 * If the UID is to be changed, the new user must have sufficient quota to
 944 * accept the key.  The quota deduction will be removed from the old user to
 945 * the new user should the attribute be changed.
 946 *
 947 * If successful, 0 will be returned.
 948 */
 949long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
 950{
 951	struct key_user *newowner, *zapowner = NULL;
 952	struct key *key;
 953	key_ref_t key_ref;
 954	long ret;
 955	kuid_t uid;
 956	kgid_t gid;
 957
 958	uid = make_kuid(current_user_ns(), user);
 959	gid = make_kgid(current_user_ns(), group);
 960	ret = -EINVAL;
 961	if ((user != (uid_t) -1) && !uid_valid(uid))
 962		goto error;
 963	if ((group != (gid_t) -1) && !gid_valid(gid))
 964		goto error;
 965
 966	ret = 0;
 967	if (user == (uid_t) -1 && group == (gid_t) -1)
 968		goto error;
 969
 970	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 971				  KEY_NEED_SETATTR);
 972	if (IS_ERR(key_ref)) {
 973		ret = PTR_ERR(key_ref);
 974		goto error;
 975	}
 976
 977	key = key_ref_to_ptr(key_ref);
 978
 979	/* make the changes with the locks held to prevent chown/chown races */
 980	ret = -EACCES;
 981	down_write(&key->sem);
 982
 983	if (!capable(CAP_SYS_ADMIN)) {
 
 
 984		/* only the sysadmin can chown a key to some other UID */
 985		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
 986			goto error_put;
 987
 988		/* only the sysadmin can set the key's GID to a group other
 989		 * than one of those that the current process subscribes to */
 990		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
 
 
 
 991			goto error_put;
 992	}
 993
 994	/* change the UID */
 995	if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
 996		ret = -ENOMEM;
 997		newowner = key_user_lookup(uid);
 998		if (!newowner)
 999			goto error_put;
1000
1001		/* transfer the quota burden to the new user */
1002		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
1003			unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
1004				key_quota_root_maxkeys : key_quota_maxkeys;
1005			unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
1006				key_quota_root_maxbytes : key_quota_maxbytes;
1007
1008			spin_lock(&newowner->lock);
1009			if (newowner->qnkeys + 1 > maxkeys ||
1010			    newowner->qnbytes + key->quotalen > maxbytes ||
1011			    newowner->qnbytes + key->quotalen <
1012			    newowner->qnbytes)
1013				goto quota_overrun;
1014
1015			newowner->qnkeys++;
1016			newowner->qnbytes += key->quotalen;
1017			spin_unlock(&newowner->lock);
1018
1019			spin_lock(&key->user->lock);
1020			key->user->qnkeys--;
1021			key->user->qnbytes -= key->quotalen;
1022			spin_unlock(&key->user->lock);
1023		}
1024
1025		atomic_dec(&key->user->nkeys);
1026		atomic_inc(&newowner->nkeys);
1027
1028		if (key->state != KEY_IS_UNINSTANTIATED) {
1029			atomic_dec(&key->user->nikeys);
1030			atomic_inc(&newowner->nikeys);
1031		}
1032
1033		zapowner = key->user;
1034		key->user = newowner;
1035		key->uid = uid;
1036	}
1037
1038	/* change the GID */
1039	if (group != (gid_t) -1)
1040		key->gid = gid;
1041
1042	notify_key(key, NOTIFY_KEY_SETATTR, 0);
1043	ret = 0;
1044
1045error_put:
1046	up_write(&key->sem);
1047	key_put(key);
1048	if (zapowner)
1049		key_user_put(zapowner);
1050error:
1051	return ret;
1052
1053quota_overrun:
1054	spin_unlock(&newowner->lock);
1055	zapowner = newowner;
1056	ret = -EDQUOT;
1057	goto error_put;
1058}
1059
1060/*
1061 * Change the permission mask on a key.
1062 *
1063 * The key must grant the caller Setattr permission for this to work, though
1064 * the key need not be fully instantiated yet.  If the caller does not have
1065 * sysadmin capability, it may only change the permission on keys that it owns.
1066 */
1067long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
1068{
1069	struct key *key;
1070	key_ref_t key_ref;
1071	long ret;
1072
1073	ret = -EINVAL;
1074	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
1075		goto error;
1076
1077	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1078				  KEY_NEED_SETATTR);
1079	if (IS_ERR(key_ref)) {
1080		ret = PTR_ERR(key_ref);
1081		goto error;
1082	}
1083
1084	key = key_ref_to_ptr(key_ref);
1085
1086	/* make the changes with the locks held to prevent chown/chmod races */
1087	ret = -EACCES;
1088	down_write(&key->sem);
1089
1090	/* if we're not the sysadmin, we can only change a key that we own */
1091	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
1092		key->perm = perm;
1093		notify_key(key, NOTIFY_KEY_SETATTR, 0);
1094		ret = 0;
1095	}
1096
1097	up_write(&key->sem);
1098	key_put(key);
1099error:
1100	return ret;
1101}
1102
1103/*
1104 * Get the destination keyring for instantiation and check that the caller has
1105 * Write permission on it.
1106 */
1107static long get_instantiation_keyring(key_serial_t ringid,
1108				      struct request_key_auth *rka,
1109				      struct key **_dest_keyring)
1110{
1111	key_ref_t dkref;
1112
1113	*_dest_keyring = NULL;
1114
1115	/* just return a NULL pointer if we weren't asked to make a link */
1116	if (ringid == 0)
1117		return 0;
1118
1119	/* if a specific keyring is nominated by ID, then use that */
1120	if (ringid > 0) {
1121		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
1122		if (IS_ERR(dkref))
1123			return PTR_ERR(dkref);
1124		*_dest_keyring = key_ref_to_ptr(dkref);
1125		return 0;
1126	}
1127
1128	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
1129		return -EINVAL;
1130
1131	/* otherwise specify the destination keyring recorded in the
1132	 * authorisation key (any KEY_SPEC_*_KEYRING) */
1133	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
1134		*_dest_keyring = key_get(rka->dest_keyring);
1135		return 0;
1136	}
1137
1138	return -ENOKEY;
1139}
1140
1141/*
1142 * Change the request_key authorisation key on the current process.
1143 */
1144static int keyctl_change_reqkey_auth(struct key *key)
1145{
1146	struct cred *new;
1147
1148	new = prepare_creds();
1149	if (!new)
1150		return -ENOMEM;
1151
1152	key_put(new->request_key_auth);
1153	new->request_key_auth = key_get(key);
1154
1155	return commit_creds(new);
1156}
1157
1158/*
1159 * Instantiate a key with the specified payload and link the key into the
1160 * destination keyring if one is given.
1161 *
1162 * The caller must have the appropriate instantiation permit set for this to
1163 * work (see keyctl_assume_authority).  No other permissions are required.
1164 *
1165 * If successful, 0 will be returned.
1166 */
1167long keyctl_instantiate_key_common(key_serial_t id,
1168				   struct iov_iter *from,
1169				   key_serial_t ringid)
1170{
1171	const struct cred *cred = current_cred();
1172	struct request_key_auth *rka;
1173	struct key *instkey, *dest_keyring;
1174	size_t plen = from ? iov_iter_count(from) : 0;
1175	void *payload;
1176	long ret;
1177
1178	kenter("%d,,%zu,%d", id, plen, ringid);
1179
1180	if (!plen)
1181		from = NULL;
1182
1183	ret = -EINVAL;
1184	if (plen > 1024 * 1024 - 1)
1185		goto error;
1186
1187	/* the appropriate instantiation authorisation key must have been
1188	 * assumed before calling this */
1189	ret = -EPERM;
1190	instkey = cred->request_key_auth;
1191	if (!instkey)
1192		goto error;
1193
1194	rka = instkey->payload.data[0];
1195	if (rka->target_key->serial != id)
1196		goto error;
1197
1198	/* pull the payload in if one was supplied */
1199	payload = NULL;
1200
1201	if (from) {
1202		ret = -ENOMEM;
1203		payload = kvmalloc(plen, GFP_KERNEL);
1204		if (!payload)
1205			goto error;
1206
1207		ret = -EFAULT;
1208		if (!copy_from_iter_full(payload, plen, from))
1209			goto error2;
1210	}
1211
1212	/* find the destination keyring amongst those belonging to the
1213	 * requesting task */
1214	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1215	if (ret < 0)
1216		goto error2;
1217
1218	/* instantiate the key and link it into a keyring */
1219	ret = key_instantiate_and_link(rka->target_key, payload, plen,
1220				       dest_keyring, instkey);
1221
1222	key_put(dest_keyring);
1223
1224	/* discard the assumed authority if it's just been disabled by
1225	 * instantiation of the key */
1226	if (ret == 0)
1227		keyctl_change_reqkey_auth(NULL);
1228
1229error2:
1230	kvfree_sensitive(payload, plen);
1231error:
1232	return ret;
1233}
1234
1235/*
1236 * Instantiate a key with the specified payload and link the key into the
1237 * destination keyring if one is given.
1238 *
1239 * The caller must have the appropriate instantiation permit set for this to
1240 * work (see keyctl_assume_authority).  No other permissions are required.
1241 *
1242 * If successful, 0 will be returned.
1243 */
1244long keyctl_instantiate_key(key_serial_t id,
1245			    const void __user *_payload,
1246			    size_t plen,
1247			    key_serial_t ringid)
1248{
1249	if (_payload && plen) {
1250		struct iovec iov;
1251		struct iov_iter from;
1252		int ret;
1253
1254		ret = import_single_range(WRITE, (void __user *)_payload, plen,
1255					  &iov, &from);
1256		if (unlikely(ret))
1257			return ret;
1258
1259		return keyctl_instantiate_key_common(id, &from, ringid);
1260	}
1261
1262	return keyctl_instantiate_key_common(id, NULL, ringid);
1263}
1264
1265/*
1266 * Instantiate a key with the specified multipart payload and link the key into
1267 * the destination keyring if one is given.
1268 *
1269 * The caller must have the appropriate instantiation permit set for this to
1270 * work (see keyctl_assume_authority).  No other permissions are required.
1271 *
1272 * If successful, 0 will be returned.
1273 */
1274long keyctl_instantiate_key_iov(key_serial_t id,
1275				const struct iovec __user *_payload_iov,
1276				unsigned ioc,
1277				key_serial_t ringid)
1278{
1279	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1280	struct iov_iter from;
1281	long ret;
1282
1283	if (!_payload_iov)
1284		ioc = 0;
1285
1286	ret = import_iovec(WRITE, _payload_iov, ioc,
1287				    ARRAY_SIZE(iovstack), &iov, &from);
1288	if (ret < 0)
1289		return ret;
1290	ret = keyctl_instantiate_key_common(id, &from, ringid);
1291	kfree(iov);
1292	return ret;
1293}
1294
1295/*
1296 * Negatively instantiate the key with the given timeout (in seconds) and link
1297 * the key into the destination keyring if one is given.
1298 *
1299 * The caller must have the appropriate instantiation permit set for this to
1300 * work (see keyctl_assume_authority).  No other permissions are required.
1301 *
1302 * The key and any links to the key will be automatically garbage collected
1303 * after the timeout expires.
1304 *
1305 * Negative keys are used to rate limit repeated request_key() calls by causing
1306 * them to return -ENOKEY until the negative key expires.
1307 *
1308 * If successful, 0 will be returned.
1309 */
1310long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1311{
1312	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1313}
1314
1315/*
1316 * Negatively instantiate the key with the given timeout (in seconds) and error
1317 * code and link the key into the destination keyring if one is given.
1318 *
1319 * The caller must have the appropriate instantiation permit set for this to
1320 * work (see keyctl_assume_authority).  No other permissions are required.
1321 *
1322 * The key and any links to the key will be automatically garbage collected
1323 * after the timeout expires.
1324 *
1325 * Negative keys are used to rate limit repeated request_key() calls by causing
1326 * them to return the specified error code until the negative key expires.
1327 *
1328 * If successful, 0 will be returned.
1329 */
1330long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1331		       key_serial_t ringid)
1332{
1333	const struct cred *cred = current_cred();
1334	struct request_key_auth *rka;
1335	struct key *instkey, *dest_keyring;
1336	long ret;
1337
1338	kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1339
1340	/* must be a valid error code and mustn't be a kernel special */
1341	if (error <= 0 ||
1342	    error >= MAX_ERRNO ||
1343	    error == ERESTARTSYS ||
1344	    error == ERESTARTNOINTR ||
1345	    error == ERESTARTNOHAND ||
1346	    error == ERESTART_RESTARTBLOCK)
1347		return -EINVAL;
1348
1349	/* the appropriate instantiation authorisation key must have been
1350	 * assumed before calling this */
1351	ret = -EPERM;
1352	instkey = cred->request_key_auth;
1353	if (!instkey)
1354		goto error;
1355
1356	rka = instkey->payload.data[0];
1357	if (rka->target_key->serial != id)
1358		goto error;
1359
1360	/* find the destination keyring if present (which must also be
1361	 * writable) */
1362	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1363	if (ret < 0)
1364		goto error;
1365
1366	/* instantiate the key and link it into a keyring */
1367	ret = key_reject_and_link(rka->target_key, timeout, error,
1368				  dest_keyring, instkey);
1369
1370	key_put(dest_keyring);
1371
1372	/* discard the assumed authority if it's just been disabled by
1373	 * instantiation of the key */
1374	if (ret == 0)
1375		keyctl_change_reqkey_auth(NULL);
1376
1377error:
1378	return ret;
1379}
1380
1381/*
1382 * Read or set the default keyring in which request_key() will cache keys and
1383 * return the old setting.
1384 *
1385 * If a thread or process keyring is specified then it will be created if it
1386 * doesn't yet exist.  The old setting will be returned if successful.
1387 */
1388long keyctl_set_reqkey_keyring(int reqkey_defl)
1389{
1390	struct cred *new;
1391	int ret, old_setting;
1392
1393	old_setting = current_cred_xxx(jit_keyring);
1394
1395	if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1396		return old_setting;
1397
1398	new = prepare_creds();
1399	if (!new)
1400		return -ENOMEM;
1401
1402	switch (reqkey_defl) {
1403	case KEY_REQKEY_DEFL_THREAD_KEYRING:
1404		ret = install_thread_keyring_to_cred(new);
1405		if (ret < 0)
1406			goto error;
1407		goto set;
1408
1409	case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1410		ret = install_process_keyring_to_cred(new);
1411		if (ret < 0)
1412			goto error;
1413		goto set;
1414
1415	case KEY_REQKEY_DEFL_DEFAULT:
1416	case KEY_REQKEY_DEFL_SESSION_KEYRING:
1417	case KEY_REQKEY_DEFL_USER_KEYRING:
1418	case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1419	case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1420		goto set;
1421
1422	case KEY_REQKEY_DEFL_NO_CHANGE:
1423	case KEY_REQKEY_DEFL_GROUP_KEYRING:
1424	default:
1425		ret = -EINVAL;
1426		goto error;
1427	}
1428
1429set:
1430	new->jit_keyring = reqkey_defl;
1431	commit_creds(new);
1432	return old_setting;
1433error:
1434	abort_creds(new);
1435	return ret;
1436}
1437
1438/*
1439 * Set or clear the timeout on a key.
1440 *
1441 * Either the key must grant the caller Setattr permission or else the caller
1442 * must hold an instantiation authorisation token for the key.
1443 *
1444 * The timeout is either 0 to clear the timeout, or a number of seconds from
1445 * the current time.  The key and any links to the key will be automatically
1446 * garbage collected after the timeout expires.
1447 *
1448 * Keys with KEY_FLAG_KEEP set should not be timed out.
1449 *
1450 * If successful, 0 is returned.
1451 */
1452long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1453{
1454	struct key *key, *instkey;
1455	key_ref_t key_ref;
1456	long ret;
1457
1458	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1459				  KEY_NEED_SETATTR);
1460	if (IS_ERR(key_ref)) {
1461		/* setting the timeout on a key under construction is permitted
1462		 * if we have the authorisation token handy */
1463		if (PTR_ERR(key_ref) == -EACCES) {
1464			instkey = key_get_instantiation_authkey(id);
1465			if (!IS_ERR(instkey)) {
1466				key_put(instkey);
1467				key_ref = lookup_user_key(id,
1468							  KEY_LOOKUP_PARTIAL,
1469							  KEY_AUTHTOKEN_OVERRIDE);
1470				if (!IS_ERR(key_ref))
1471					goto okay;
1472			}
1473		}
1474
1475		ret = PTR_ERR(key_ref);
1476		goto error;
1477	}
1478
1479okay:
1480	key = key_ref_to_ptr(key_ref);
1481	ret = 0;
1482	if (test_bit(KEY_FLAG_KEEP, &key->flags)) {
1483		ret = -EPERM;
1484	} else {
1485		key_set_timeout(key, timeout);
1486		notify_key(key, NOTIFY_KEY_SETATTR, 0);
1487	}
1488	key_put(key);
1489
1490error:
1491	return ret;
1492}
1493
1494/*
1495 * Assume (or clear) the authority to instantiate the specified key.
1496 *
1497 * This sets the authoritative token currently in force for key instantiation.
1498 * This must be done for a key to be instantiated.  It has the effect of making
1499 * available all the keys from the caller of the request_key() that created a
1500 * key to request_key() calls made by the caller of this function.
1501 *
1502 * The caller must have the instantiation key in their process keyrings with a
1503 * Search permission grant available to the caller.
1504 *
1505 * If the ID given is 0, then the setting will be cleared and 0 returned.
1506 *
1507 * If the ID given has a matching an authorisation key, then that key will be
1508 * set and its ID will be returned.  The authorisation key can be read to get
1509 * the callout information passed to request_key().
1510 */
1511long keyctl_assume_authority(key_serial_t id)
1512{
1513	struct key *authkey;
1514	long ret;
1515
1516	/* special key IDs aren't permitted */
1517	ret = -EINVAL;
1518	if (id < 0)
1519		goto error;
1520
1521	/* we divest ourselves of authority if given an ID of 0 */
1522	if (id == 0) {
1523		ret = keyctl_change_reqkey_auth(NULL);
1524		goto error;
1525	}
1526
1527	/* attempt to assume the authority temporarily granted to us whilst we
1528	 * instantiate the specified key
1529	 * - the authorisation key must be in the current task's keyrings
1530	 *   somewhere
1531	 */
1532	authkey = key_get_instantiation_authkey(id);
1533	if (IS_ERR(authkey)) {
1534		ret = PTR_ERR(authkey);
1535		goto error;
1536	}
1537
1538	ret = keyctl_change_reqkey_auth(authkey);
1539	if (ret == 0)
1540		ret = authkey->serial;
1541	key_put(authkey);
1542error:
1543	return ret;
1544}
1545
1546/*
1547 * Get a key's the LSM security label.
1548 *
1549 * The key must grant the caller View permission for this to work.
1550 *
1551 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1552 *
1553 * If successful, the amount of information available will be returned,
1554 * irrespective of how much was copied (including the terminal NUL).
1555 */
1556long keyctl_get_security(key_serial_t keyid,
1557			 char __user *buffer,
1558			 size_t buflen)
1559{
1560	struct key *key, *instkey;
1561	key_ref_t key_ref;
1562	char *context;
1563	long ret;
1564
1565	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1566	if (IS_ERR(key_ref)) {
1567		if (PTR_ERR(key_ref) != -EACCES)
1568			return PTR_ERR(key_ref);
1569
1570		/* viewing a key under construction is also permitted if we
1571		 * have the authorisation token handy */
1572		instkey = key_get_instantiation_authkey(keyid);
1573		if (IS_ERR(instkey))
1574			return PTR_ERR(instkey);
1575		key_put(instkey);
1576
1577		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL,
1578					  KEY_AUTHTOKEN_OVERRIDE);
1579		if (IS_ERR(key_ref))
1580			return PTR_ERR(key_ref);
1581	}
1582
1583	key = key_ref_to_ptr(key_ref);
1584	ret = security_key_getsecurity(key, &context);
1585	if (ret == 0) {
1586		/* if no information was returned, give userspace an empty
1587		 * string */
1588		ret = 1;
1589		if (buffer && buflen > 0 &&
1590		    copy_to_user(buffer, "", 1) != 0)
1591			ret = -EFAULT;
1592	} else if (ret > 0) {
1593		/* return as much data as there's room for */
1594		if (buffer && buflen > 0) {
1595			if (buflen > ret)
1596				buflen = ret;
1597
1598			if (copy_to_user(buffer, context, buflen) != 0)
1599				ret = -EFAULT;
1600		}
1601
1602		kfree(context);
1603	}
1604
1605	key_ref_put(key_ref);
1606	return ret;
1607}
1608
1609/*
1610 * Attempt to install the calling process's session keyring on the process's
1611 * parent process.
1612 *
1613 * The keyring must exist and must grant the caller LINK permission, and the
1614 * parent process must be single-threaded and must have the same effective
1615 * ownership as this process and mustn't be SUID/SGID.
1616 *
1617 * The keyring will be emplaced on the parent when it next resumes userspace.
1618 *
1619 * If successful, 0 will be returned.
1620 */
1621long keyctl_session_to_parent(void)
1622{
1623	struct task_struct *me, *parent;
1624	const struct cred *mycred, *pcred;
1625	struct callback_head *newwork, *oldwork;
1626	key_ref_t keyring_r;
1627	struct cred *cred;
1628	int ret;
1629
1630	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1631	if (IS_ERR(keyring_r))
1632		return PTR_ERR(keyring_r);
1633
1634	ret = -ENOMEM;
1635
1636	/* our parent is going to need a new cred struct, a new tgcred struct
1637	 * and new security data, so we allocate them here to prevent ENOMEM in
1638	 * our parent */
1639	cred = cred_alloc_blank();
1640	if (!cred)
1641		goto error_keyring;
1642	newwork = &cred->rcu;
1643
1644	cred->session_keyring = key_ref_to_ptr(keyring_r);
1645	keyring_r = NULL;
1646	init_task_work(newwork, key_change_session_keyring);
1647
1648	me = current;
1649	rcu_read_lock();
1650	write_lock_irq(&tasklist_lock);
1651
1652	ret = -EPERM;
1653	oldwork = NULL;
1654	parent = rcu_dereference_protected(me->real_parent,
1655					   lockdep_is_held(&tasklist_lock));
1656
1657	/* the parent mustn't be init and mustn't be a kernel thread */
1658	if (parent->pid <= 1 || !parent->mm)
1659		goto unlock;
1660
1661	/* the parent must be single threaded */
1662	if (!thread_group_empty(parent))
1663		goto unlock;
1664
1665	/* the parent and the child must have different session keyrings or
1666	 * there's no point */
1667	mycred = current_cred();
1668	pcred = __task_cred(parent);
1669	if (mycred == pcred ||
1670	    mycred->session_keyring == pcred->session_keyring) {
1671		ret = 0;
1672		goto unlock;
1673	}
1674
1675	/* the parent must have the same effective ownership and mustn't be
1676	 * SUID/SGID */
1677	if (!uid_eq(pcred->uid,	 mycred->euid) ||
1678	    !uid_eq(pcred->euid, mycred->euid) ||
1679	    !uid_eq(pcred->suid, mycred->euid) ||
1680	    !gid_eq(pcred->gid,	 mycred->egid) ||
1681	    !gid_eq(pcred->egid, mycred->egid) ||
1682	    !gid_eq(pcred->sgid, mycred->egid))
1683		goto unlock;
1684
1685	/* the keyrings must have the same UID */
1686	if ((pcred->session_keyring &&
1687	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1688	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
1689		goto unlock;
1690
1691	/* cancel an already pending keyring replacement */
1692	oldwork = task_work_cancel(parent, key_change_session_keyring);
1693
1694	/* the replacement session keyring is applied just prior to userspace
1695	 * restarting */
1696	ret = task_work_add(parent, newwork, true);
1697	if (!ret)
1698		newwork = NULL;
1699unlock:
1700	write_unlock_irq(&tasklist_lock);
1701	rcu_read_unlock();
1702	if (oldwork)
1703		put_cred(container_of(oldwork, struct cred, rcu));
1704	if (newwork)
1705		put_cred(cred);
1706	return ret;
1707
1708error_keyring:
1709	key_ref_put(keyring_r);
1710	return ret;
1711}
1712
1713/*
1714 * Apply a restriction to a given keyring.
1715 *
1716 * The caller must have Setattr permission to change keyring restrictions.
1717 *
1718 * The requested type name may be a NULL pointer to reject all attempts
1719 * to link to the keyring.  In this case, _restriction must also be NULL.
1720 * Otherwise, both _type and _restriction must be non-NULL.
1721 *
1722 * Returns 0 if successful.
1723 */
1724long keyctl_restrict_keyring(key_serial_t id, const char __user *_type,
1725			     const char __user *_restriction)
1726{
1727	key_ref_t key_ref;
1728	char type[32];
1729	char *restriction = NULL;
1730	long ret;
1731
1732	key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
1733	if (IS_ERR(key_ref))
1734		return PTR_ERR(key_ref);
1735
1736	ret = -EINVAL;
1737	if (_type) {
1738		if (!_restriction)
1739			goto error;
1740
1741		ret = key_get_type_from_user(type, _type, sizeof(type));
1742		if (ret < 0)
1743			goto error;
1744
1745		restriction = strndup_user(_restriction, PAGE_SIZE);
1746		if (IS_ERR(restriction)) {
1747			ret = PTR_ERR(restriction);
1748			goto error;
1749		}
1750	} else {
1751		if (_restriction)
1752			goto error;
1753	}
1754
1755	ret = keyring_restrict(key_ref, _type ? type : NULL, restriction);
1756	kfree(restriction);
1757error:
1758	key_ref_put(key_ref);
1759	return ret;
1760}
1761
1762#ifdef CONFIG_KEY_NOTIFICATIONS
1763/*
1764 * Watch for changes to a key.
1765 *
1766 * The caller must have View permission to watch a key or keyring.
1767 */
1768long keyctl_watch_key(key_serial_t id, int watch_queue_fd, int watch_id)
1769{
1770	struct watch_queue *wqueue;
1771	struct watch_list *wlist = NULL;
1772	struct watch *watch = NULL;
1773	struct key *key;
1774	key_ref_t key_ref;
1775	long ret;
1776
1777	if (watch_id < -1 || watch_id > 0xff)
1778		return -EINVAL;
1779
1780	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_VIEW);
1781	if (IS_ERR(key_ref))
1782		return PTR_ERR(key_ref);
1783	key = key_ref_to_ptr(key_ref);
1784
1785	wqueue = get_watch_queue(watch_queue_fd);
1786	if (IS_ERR(wqueue)) {
1787		ret = PTR_ERR(wqueue);
1788		goto err_key;
1789	}
1790
1791	if (watch_id >= 0) {
1792		ret = -ENOMEM;
1793		if (!key->watchers) {
1794			wlist = kzalloc(sizeof(*wlist), GFP_KERNEL);
1795			if (!wlist)
1796				goto err_wqueue;
1797			init_watch_list(wlist, NULL);
1798		}
1799
1800		watch = kzalloc(sizeof(*watch), GFP_KERNEL);
1801		if (!watch)
1802			goto err_wlist;
1803
1804		init_watch(watch, wqueue);
1805		watch->id	= key->serial;
1806		watch->info_id	= (u32)watch_id << WATCH_INFO_ID__SHIFT;
1807
1808		ret = security_watch_key(key);
1809		if (ret < 0)
1810			goto err_watch;
1811
1812		down_write(&key->sem);
1813		if (!key->watchers) {
1814			key->watchers = wlist;
1815			wlist = NULL;
1816		}
1817
1818		ret = add_watch_to_object(watch, key->watchers);
1819		up_write(&key->sem);
1820
1821		if (ret == 0)
1822			watch = NULL;
1823	} else {
1824		ret = -EBADSLT;
1825		if (key->watchers) {
1826			down_write(&key->sem);
1827			ret = remove_watch_from_object(key->watchers,
1828						       wqueue, key_serial(key),
1829						       false);
1830			up_write(&key->sem);
1831		}
1832	}
1833
1834err_watch:
1835	kfree(watch);
1836err_wlist:
1837	kfree(wlist);
1838err_wqueue:
1839	put_watch_queue(wqueue);
1840err_key:
1841	key_put(key);
1842	return ret;
1843}
1844#endif /* CONFIG_KEY_NOTIFICATIONS */
1845
1846/*
1847 * Get keyrings subsystem capabilities.
1848 */
1849long keyctl_capabilities(unsigned char __user *_buffer, size_t buflen)
1850{
1851	size_t size = buflen;
1852
1853	if (size > 0) {
1854		if (size > sizeof(keyrings_capabilities))
1855			size = sizeof(keyrings_capabilities);
1856		if (copy_to_user(_buffer, keyrings_capabilities, size) != 0)
1857			return -EFAULT;
1858		if (size < buflen &&
1859		    clear_user(_buffer + size, buflen - size) != 0)
1860			return -EFAULT;
1861	}
1862
1863	return sizeof(keyrings_capabilities);
1864}
1865
1866/*
1867 * The key control system call
1868 */
1869SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1870		unsigned long, arg4, unsigned long, arg5)
1871{
1872	switch (option) {
1873	case KEYCTL_GET_KEYRING_ID:
1874		return keyctl_get_keyring_ID((key_serial_t) arg2,
1875					     (int) arg3);
1876
1877	case KEYCTL_JOIN_SESSION_KEYRING:
1878		return keyctl_join_session_keyring((const char __user *) arg2);
1879
1880	case KEYCTL_UPDATE:
1881		return keyctl_update_key((key_serial_t) arg2,
1882					 (const void __user *) arg3,
1883					 (size_t) arg4);
1884
1885	case KEYCTL_REVOKE:
1886		return keyctl_revoke_key((key_serial_t) arg2);
1887
1888	case KEYCTL_DESCRIBE:
1889		return keyctl_describe_key((key_serial_t) arg2,
1890					   (char __user *) arg3,
1891					   (unsigned) arg4);
1892
1893	case KEYCTL_CLEAR:
1894		return keyctl_keyring_clear((key_serial_t) arg2);
1895
1896	case KEYCTL_LINK:
1897		return keyctl_keyring_link((key_serial_t) arg2,
1898					   (key_serial_t) arg3);
1899
1900	case KEYCTL_UNLINK:
1901		return keyctl_keyring_unlink((key_serial_t) arg2,
1902					     (key_serial_t) arg3);
1903
1904	case KEYCTL_SEARCH:
1905		return keyctl_keyring_search((key_serial_t) arg2,
1906					     (const char __user *) arg3,
1907					     (const char __user *) arg4,
1908					     (key_serial_t) arg5);
1909
1910	case KEYCTL_READ:
1911		return keyctl_read_key((key_serial_t) arg2,
1912				       (char __user *) arg3,
1913				       (size_t) arg4);
1914
1915	case KEYCTL_CHOWN:
1916		return keyctl_chown_key((key_serial_t) arg2,
1917					(uid_t) arg3,
1918					(gid_t) arg4);
1919
1920	case KEYCTL_SETPERM:
1921		return keyctl_setperm_key((key_serial_t) arg2,
1922					  (key_perm_t) arg3);
1923
1924	case KEYCTL_INSTANTIATE:
1925		return keyctl_instantiate_key((key_serial_t) arg2,
1926					      (const void __user *) arg3,
1927					      (size_t) arg4,
1928					      (key_serial_t) arg5);
1929
1930	case KEYCTL_NEGATE:
1931		return keyctl_negate_key((key_serial_t) arg2,
1932					 (unsigned) arg3,
1933					 (key_serial_t) arg4);
1934
1935	case KEYCTL_SET_REQKEY_KEYRING:
1936		return keyctl_set_reqkey_keyring(arg2);
1937
1938	case KEYCTL_SET_TIMEOUT:
1939		return keyctl_set_timeout((key_serial_t) arg2,
1940					  (unsigned) arg3);
1941
1942	case KEYCTL_ASSUME_AUTHORITY:
1943		return keyctl_assume_authority((key_serial_t) arg2);
1944
1945	case KEYCTL_GET_SECURITY:
1946		return keyctl_get_security((key_serial_t) arg2,
1947					   (char __user *) arg3,
1948					   (size_t) arg4);
1949
1950	case KEYCTL_SESSION_TO_PARENT:
1951		return keyctl_session_to_parent();
1952
1953	case KEYCTL_REJECT:
1954		return keyctl_reject_key((key_serial_t) arg2,
1955					 (unsigned) arg3,
1956					 (unsigned) arg4,
1957					 (key_serial_t) arg5);
1958
1959	case KEYCTL_INSTANTIATE_IOV:
1960		return keyctl_instantiate_key_iov(
1961			(key_serial_t) arg2,
1962			(const struct iovec __user *) arg3,
1963			(unsigned) arg4,
1964			(key_serial_t) arg5);
1965
1966	case KEYCTL_INVALIDATE:
1967		return keyctl_invalidate_key((key_serial_t) arg2);
1968
1969	case KEYCTL_GET_PERSISTENT:
1970		return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1971
1972	case KEYCTL_DH_COMPUTE:
1973		return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
1974					 (char __user *) arg3, (size_t) arg4,
1975					 (struct keyctl_kdf_params __user *) arg5);
1976
1977	case KEYCTL_RESTRICT_KEYRING:
1978		return keyctl_restrict_keyring((key_serial_t) arg2,
1979					       (const char __user *) arg3,
1980					       (const char __user *) arg4);
1981
1982	case KEYCTL_PKEY_QUERY:
1983		if (arg3 != 0)
1984			return -EINVAL;
1985		return keyctl_pkey_query((key_serial_t)arg2,
1986					 (const char __user *)arg4,
1987					 (struct keyctl_pkey_query __user *)arg5);
1988
1989	case KEYCTL_PKEY_ENCRYPT:
1990	case KEYCTL_PKEY_DECRYPT:
1991	case KEYCTL_PKEY_SIGN:
1992		return keyctl_pkey_e_d_s(
1993			option,
1994			(const struct keyctl_pkey_params __user *)arg2,
1995			(const char __user *)arg3,
1996			(const void __user *)arg4,
1997			(void __user *)arg5);
1998
1999	case KEYCTL_PKEY_VERIFY:
2000		return keyctl_pkey_verify(
2001			(const struct keyctl_pkey_params __user *)arg2,
2002			(const char __user *)arg3,
2003			(const void __user *)arg4,
2004			(const void __user *)arg5);
2005
2006	case KEYCTL_MOVE:
2007		return keyctl_keyring_move((key_serial_t)arg2,
2008					   (key_serial_t)arg3,
2009					   (key_serial_t)arg4,
2010					   (unsigned int)arg5);
2011
2012	case KEYCTL_CAPABILITIES:
2013		return keyctl_capabilities((unsigned char __user *)arg2, (size_t)arg3);
2014
2015	case KEYCTL_WATCH_KEY:
2016		return keyctl_watch_key((key_serial_t)arg2, (int)arg3, (int)arg4);
2017
2018	default:
2019		return -EOPNOTSUPP;
2020	}
2021}