1/* Userspace key control operations
   2 *
   3 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/init.h>
  14#include <linux/sched.h>
  15#include <linux/slab.h>
  16#include <linux/syscalls.h>
  17#include <linux/key.h>
  18#include <linux/keyctl.h>
  19#include <linux/fs.h>
  20#include <linux/capability.h>
  21#include <linux/string.h>
  22#include <linux/err.h>
  23#include <linux/vmalloc.h>
  24#include <linux/security.h>
 
  25#include <asm/uaccess.h>
  26#include "internal.h"
  27
  28static int key_get_type_from_user(char *type,
  29				  const char __user *_type,
  30				  unsigned len)
  31{
  32	int ret;
  33
  34	ret = strncpy_from_user(type, _type, len);
  35	if (ret < 0)
  36		return ret;
  37	if (ret == 0 || ret >= len)
  38		return -EINVAL;
  39	if (type[0] == '.')
  40		return -EPERM;
  41	type[len - 1] = '\0';
  42	return 0;
  43}
  44
  45/*
  46 * Extract the description of a new key from userspace and either add it as a
  47 * new key to the specified keyring or update a matching key in that keyring.
  48 *
 
 
 
  49 * The keyring must be writable so that we can attach the key to it.
  50 *
  51 * If successful, the new key's serial number is returned, otherwise an error
  52 * code is returned.
  53 */
  54SYSCALL_DEFINE5(add_key, const char __user *, _type,
  55		const char __user *, _description,
  56		const void __user *, _payload,
  57		size_t, plen,
  58		key_serial_t, ringid)
  59{
  60	key_ref_t keyring_ref, key_ref;
  61	char type[32], *description;
  62	void *payload;
  63	long ret;
  64	bool vm;
  65
  66	ret = -EINVAL;
  67	if (plen > 1024 * 1024 - 1)
  68		goto error;
  69
  70	/* draw all the data into kernel space */
  71	ret = key_get_type_from_user(type, _type, sizeof(type));
  72	if (ret < 0)
  73		goto error;
  74
  75	description = strndup_user(_description, PAGE_SIZE);
  76	if (IS_ERR(description)) {
  77		ret = PTR_ERR(description);
  78		goto error;
 
 
 
 
 
 
 
  79	}
  80
  81	/* pull the payload in if one was supplied */
  82	payload = NULL;
  83
  84	vm = false;
  85	if (_payload) {
  86		ret = -ENOMEM;
  87		payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
  88		if (!payload) {
  89			if (plen <= PAGE_SIZE)
  90				goto error2;
  91			vm = true;
  92			payload = vmalloc(plen);
  93			if (!payload)
  94				goto error2;
  95		}
  96
  97		ret = -EFAULT;
  98		if (copy_from_user(payload, _payload, plen) != 0)
  99			goto error3;
 100	}
 101
 102	/* find the target keyring (which must be writable) */
 103	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 104	if (IS_ERR(keyring_ref)) {
 105		ret = PTR_ERR(keyring_ref);
 106		goto error3;
 107	}
 108
 109	/* create or update the requested key and add it to the target
 110	 * keyring */
 111	key_ref = key_create_or_update(keyring_ref, type, description,
 112				       payload, plen, KEY_PERM_UNDEF,
 113				       KEY_ALLOC_IN_QUOTA);
 114	if (!IS_ERR(key_ref)) {
 115		ret = key_ref_to_ptr(key_ref)->serial;
 116		key_ref_put(key_ref);
 117	}
 118	else {
 119		ret = PTR_ERR(key_ref);
 120	}
 121
 122	key_ref_put(keyring_ref);
 123 error3:
 124	if (!vm)
 125		kfree(payload);
 126	else
 127		vfree(payload);
 128 error2:
 129	kfree(description);
 130 error:
 131	return ret;
 132}
 133
 134/*
 135 * Search the process keyrings and keyring trees linked from those for a
 136 * matching key.  Keyrings must have appropriate Search permission to be
 137 * searched.
 138 *
 139 * If a key is found, it will be attached to the destination keyring if there's
 140 * one specified and the serial number of the key will be returned.
 141 *
 142 * If no key is found, /sbin/request-key will be invoked if _callout_info is
 143 * non-NULL in an attempt to create a key.  The _callout_info string will be
 144 * passed to /sbin/request-key to aid with completing the request.  If the
 145 * _callout_info string is "" then it will be changed to "-".
 146 */
 147SYSCALL_DEFINE4(request_key, const char __user *, _type,
 148		const char __user *, _description,
 149		const char __user *, _callout_info,
 150		key_serial_t, destringid)
 151{
 152	struct key_type *ktype;
 153	struct key *key;
 154	key_ref_t dest_ref;
 155	size_t callout_len;
 156	char type[32], *description, *callout_info;
 157	long ret;
 158
 159	/* pull the type into kernel space */
 160	ret = key_get_type_from_user(type, _type, sizeof(type));
 161	if (ret < 0)
 162		goto error;
 163
 164	/* pull the description into kernel space */
 165	description = strndup_user(_description, PAGE_SIZE);
 166	if (IS_ERR(description)) {
 167		ret = PTR_ERR(description);
 168		goto error;
 169	}
 170
 171	/* pull the callout info into kernel space */
 172	callout_info = NULL;
 173	callout_len = 0;
 174	if (_callout_info) {
 175		callout_info = strndup_user(_callout_info, PAGE_SIZE);
 176		if (IS_ERR(callout_info)) {
 177			ret = PTR_ERR(callout_info);
 178			goto error2;
 179		}
 180		callout_len = strlen(callout_info);
 181	}
 182
 183	/* get the destination keyring if specified */
 184	dest_ref = NULL;
 185	if (destringid) {
 186		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 187					   KEY_WRITE);
 188		if (IS_ERR(dest_ref)) {
 189			ret = PTR_ERR(dest_ref);
 190			goto error3;
 191		}
 192	}
 193
 194	/* find the key type */
 195	ktype = key_type_lookup(type);
 196	if (IS_ERR(ktype)) {
 197		ret = PTR_ERR(ktype);
 198		goto error4;
 199	}
 200
 201	/* do the search */
 202	key = request_key_and_link(ktype, description, callout_info,
 203				   callout_len, NULL, key_ref_to_ptr(dest_ref),
 204				   KEY_ALLOC_IN_QUOTA);
 205	if (IS_ERR(key)) {
 206		ret = PTR_ERR(key);
 207		goto error5;
 208	}
 209
 210	/* wait for the key to finish being constructed */
 211	ret = wait_for_key_construction(key, 1);
 212	if (ret < 0)
 213		goto error6;
 214
 215	ret = key->serial;
 216
 217error6:
 218 	key_put(key);
 219error5:
 220	key_type_put(ktype);
 221error4:
 222	key_ref_put(dest_ref);
 223error3:
 224	kfree(callout_info);
 225error2:
 226	kfree(description);
 227error:
 228	return ret;
 229}
 230
 231/*
 232 * Get the ID of the specified process keyring.
 233 *
 234 * The requested keyring must have search permission to be found.
 235 *
 236 * If successful, the ID of the requested keyring will be returned.
 237 */
 238long keyctl_get_keyring_ID(key_serial_t id, int create)
 239{
 240	key_ref_t key_ref;
 241	unsigned long lflags;
 242	long ret;
 243
 244	lflags = create ? KEY_LOOKUP_CREATE : 0;
 245	key_ref = lookup_user_key(id, lflags, KEY_SEARCH);
 246	if (IS_ERR(key_ref)) {
 247		ret = PTR_ERR(key_ref);
 248		goto error;
 249	}
 250
 251	ret = key_ref_to_ptr(key_ref)->serial;
 252	key_ref_put(key_ref);
 253error:
 254	return ret;
 255}
 256
 257/*
 258 * Join a (named) session keyring.
 259 *
 260 * Create and join an anonymous session keyring or join a named session
 261 * keyring, creating it if necessary.  A named session keyring must have Search
 262 * permission for it to be joined.  Session keyrings without this permit will
 263 * be skipped over.
 264 *
 265 * If successful, the ID of the joined session keyring will be returned.
 266 */
 267long keyctl_join_session_keyring(const char __user *_name)
 268{
 269	char *name;
 270	long ret;
 271
 272	/* fetch the name from userspace */
 273	name = NULL;
 274	if (_name) {
 275		name = strndup_user(_name, PAGE_SIZE);
 276		if (IS_ERR(name)) {
 277			ret = PTR_ERR(name);
 278			goto error;
 279		}
 280	}
 281
 282	/* join the session */
 283	ret = join_session_keyring(name);
 284	kfree(name);
 285
 286error:
 287	return ret;
 288}
 289
 290/*
 291 * Update a key's data payload from the given data.
 292 *
 293 * The key must grant the caller Write permission and the key type must support
 294 * updating for this to work.  A negative key can be positively instantiated
 295 * with this call.
 296 *
 297 * If successful, 0 will be returned.  If the key type does not support
 298 * updating, then -EOPNOTSUPP will be returned.
 299 */
 300long keyctl_update_key(key_serial_t id,
 301		       const void __user *_payload,
 302		       size_t plen)
 303{
 304	key_ref_t key_ref;
 305	void *payload;
 306	long ret;
 307
 308	ret = -EINVAL;
 309	if (plen > PAGE_SIZE)
 310		goto error;
 311
 312	/* pull the payload in if one was supplied */
 313	payload = NULL;
 314	if (_payload) {
 315		ret = -ENOMEM;
 316		payload = kmalloc(plen, GFP_KERNEL);
 317		if (!payload)
 318			goto error;
 319
 320		ret = -EFAULT;
 321		if (copy_from_user(payload, _payload, plen) != 0)
 322			goto error2;
 323	}
 324
 325	/* find the target key (which must be writable) */
 326	key_ref = lookup_user_key(id, 0, KEY_WRITE);
 327	if (IS_ERR(key_ref)) {
 328		ret = PTR_ERR(key_ref);
 329		goto error2;
 330	}
 331
 332	/* update the key */
 333	ret = key_update(key_ref, payload, plen);
 334
 335	key_ref_put(key_ref);
 336error2:
 337	kfree(payload);
 338error:
 339	return ret;
 340}
 341
 342/*
 343 * Revoke a key.
 344 *
 345 * The key must be grant the caller Write or Setattr permission for this to
 346 * work.  The key type should give up its quota claim when revoked.  The key
 347 * and any links to the key will be automatically garbage collected after a
 348 * certain amount of time (/proc/sys/kernel/keys/gc_delay).
 349 *
 350 * If successful, 0 is returned.
 351 */
 352long keyctl_revoke_key(key_serial_t id)
 353{
 354	key_ref_t key_ref;
 355	long ret;
 356
 357	key_ref = lookup_user_key(id, 0, KEY_WRITE);
 358	if (IS_ERR(key_ref)) {
 359		ret = PTR_ERR(key_ref);
 360		if (ret != -EACCES)
 361			goto error;
 362		key_ref = lookup_user_key(id, 0, KEY_SETATTR);
 363		if (IS_ERR(key_ref)) {
 364			ret = PTR_ERR(key_ref);
 365			goto error;
 366		}
 367	}
 368
 369	key_revoke(key_ref_to_ptr(key_ref));
 370	ret = 0;
 371
 372	key_ref_put(key_ref);
 373error:
 374	return ret;
 375}
 376
 377/*
 378 * Invalidate a key.
 379 *
 380 * The key must be grant the caller Invalidate permission for this to work.
 381 * The key and any links to the key will be automatically garbage collected
 382 * immediately.
 383 *
 384 * If successful, 0 is returned.
 385 */
 386long keyctl_invalidate_key(key_serial_t id)
 387{
 388	key_ref_t key_ref;
 389	long ret;
 390
 391	kenter("%d", id);
 392
 393	key_ref = lookup_user_key(id, 0, KEY_SEARCH);
 394	if (IS_ERR(key_ref)) {
 395		ret = PTR_ERR(key_ref);
 396		goto error;
 397	}
 398
 399	key_invalidate(key_ref_to_ptr(key_ref));
 400	ret = 0;
 401
 402	key_ref_put(key_ref);
 403error:
 404	kleave(" = %ld", ret);
 405	return ret;
 406}
 407
 408/*
 409 * Clear the specified keyring, creating an empty process keyring if one of the
 410 * special keyring IDs is used.
 411 *
 412 * The keyring must grant the caller Write permission for this to work.  If
 413 * successful, 0 will be returned.
 414 */
 415long keyctl_keyring_clear(key_serial_t ringid)
 416{
 417	key_ref_t keyring_ref;
 418	long ret;
 419
 420	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 421	if (IS_ERR(keyring_ref)) {
 422		ret = PTR_ERR(keyring_ref);
 423
 424		/* Root is permitted to invalidate certain special keyrings */
 425		if (capable(CAP_SYS_ADMIN)) {
 426			keyring_ref = lookup_user_key(ringid, 0, 0);
 427			if (IS_ERR(keyring_ref))
 428				goto error;
 429			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 430				     &key_ref_to_ptr(keyring_ref)->flags))
 431				goto clear;
 432			goto error_put;
 433		}
 434
 435		goto error;
 436	}
 437
 438clear:
 439	ret = keyring_clear(key_ref_to_ptr(keyring_ref));
 440error_put:
 441	key_ref_put(keyring_ref);
 442error:
 443	return ret;
 444}
 445
 446/*
 447 * Create a link from a keyring to a key if there's no matching key in the
 448 * keyring, otherwise replace the link to the matching key with a link to the
 449 * new key.
 450 *
 451 * The key must grant the caller Link permission and the the keyring must grant
 452 * the caller Write permission.  Furthermore, if an additional link is created,
 453 * the keyring's quota will be extended.
 454 *
 455 * If successful, 0 will be returned.
 456 */
 457long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 458{
 459	key_ref_t keyring_ref, key_ref;
 460	long ret;
 461
 462	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 463	if (IS_ERR(keyring_ref)) {
 464		ret = PTR_ERR(keyring_ref);
 465		goto error;
 466	}
 467
 468	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_LINK);
 469	if (IS_ERR(key_ref)) {
 470		ret = PTR_ERR(key_ref);
 471		goto error2;
 472	}
 473
 474	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 475
 476	key_ref_put(key_ref);
 477error2:
 478	key_ref_put(keyring_ref);
 479error:
 480	return ret;
 481}
 482
 483/*
 484 * Unlink a key from a keyring.
 485 *
 486 * The keyring must grant the caller Write permission for this to work; the key
 487 * itself need not grant the caller anything.  If the last link to a key is
 488 * removed then that key will be scheduled for destruction.
 489 *
 490 * If successful, 0 will be returned.
 491 */
 492long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 493{
 494	key_ref_t keyring_ref, key_ref;
 495	long ret;
 496
 497	keyring_ref = lookup_user_key(ringid, 0, KEY_WRITE);
 498	if (IS_ERR(keyring_ref)) {
 499		ret = PTR_ERR(keyring_ref);
 500		goto error;
 501	}
 502
 503	key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 504	if (IS_ERR(key_ref)) {
 505		ret = PTR_ERR(key_ref);
 506		goto error2;
 507	}
 508
 509	ret = key_unlink(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 510
 511	key_ref_put(key_ref);
 512error2:
 513	key_ref_put(keyring_ref);
 514error:
 515	return ret;
 516}
 517
 518/*
 519 * Return a description of a key to userspace.
 520 *
 521 * The key must grant the caller View permission for this to work.
 522 *
 523 * If there's a buffer, we place up to buflen bytes of data into it formatted
 524 * in the following way:
 525 *
 526 *	type;uid;gid;perm;description<NUL>
 527 *
 528 * If successful, we return the amount of description available, irrespective
 529 * of how much we may have copied into the buffer.
 530 */
 531long keyctl_describe_key(key_serial_t keyid,
 532			 char __user *buffer,
 533			 size_t buflen)
 534{
 535	struct key *key, *instkey;
 536	key_ref_t key_ref;
 537	char *tmpbuf;
 538	long ret;
 539
 540	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
 541	if (IS_ERR(key_ref)) {
 542		/* viewing a key under construction is permitted if we have the
 543		 * authorisation token handy */
 544		if (PTR_ERR(key_ref) == -EACCES) {
 545			instkey = key_get_instantiation_authkey(keyid);
 546			if (!IS_ERR(instkey)) {
 547				key_put(instkey);
 548				key_ref = lookup_user_key(keyid,
 549							  KEY_LOOKUP_PARTIAL,
 550							  0);
 551				if (!IS_ERR(key_ref))
 552					goto okay;
 553			}
 554		}
 555
 556		ret = PTR_ERR(key_ref);
 557		goto error;
 558	}
 559
 560okay:
 561	/* calculate how much description we're going to return */
 562	ret = -ENOMEM;
 563	tmpbuf = kmalloc(PAGE_SIZE, GFP_KERNEL);
 564	if (!tmpbuf)
 565		goto error2;
 566
 567	key = key_ref_to_ptr(key_ref);
 568
 569	ret = snprintf(tmpbuf, PAGE_SIZE - 1,
 570		       "%s;%d;%d;%08x;%s",
 571		       key->type->name,
 572		       key->uid,
 573		       key->gid,
 574		       key->perm,
 575		       key->description ?: "");
 576
 577	/* include a NUL char at the end of the data */
 578	if (ret > PAGE_SIZE - 1)
 579		ret = PAGE_SIZE - 1;
 580	tmpbuf[ret] = 0;
 581	ret++;
 582
 583	/* consider returning the data */
 584	if (buffer && buflen > 0) {
 585		if (buflen > ret)
 586			buflen = ret;
 587
 588		if (copy_to_user(buffer, tmpbuf, buflen) != 0)
 589			ret = -EFAULT;
 590	}
 591
 592	kfree(tmpbuf);
 593error2:
 594	key_ref_put(key_ref);
 595error:
 596	return ret;
 597}
 598
 599/*
 600 * Search the specified keyring and any keyrings it links to for a matching
 601 * key.  Only keyrings that grant the caller Search permission will be searched
 602 * (this includes the starting keyring).  Only keys with Search permission can
 603 * be found.
 604 *
 605 * If successful, the found key will be linked to the destination keyring if
 606 * supplied and the key has Link permission, and the found key ID will be
 607 * returned.
 608 */
 609long keyctl_keyring_search(key_serial_t ringid,
 610			   const char __user *_type,
 611			   const char __user *_description,
 612			   key_serial_t destringid)
 613{
 614	struct key_type *ktype;
 615	key_ref_t keyring_ref, key_ref, dest_ref;
 616	char type[32], *description;
 617	long ret;
 618
 619	/* pull the type and description into kernel space */
 620	ret = key_get_type_from_user(type, _type, sizeof(type));
 621	if (ret < 0)
 622		goto error;
 623
 624	description = strndup_user(_description, PAGE_SIZE);
 625	if (IS_ERR(description)) {
 626		ret = PTR_ERR(description);
 627		goto error;
 628	}
 629
 630	/* get the keyring at which to begin the search */
 631	keyring_ref = lookup_user_key(ringid, 0, KEY_SEARCH);
 632	if (IS_ERR(keyring_ref)) {
 633		ret = PTR_ERR(keyring_ref);
 634		goto error2;
 635	}
 636
 637	/* get the destination keyring if specified */
 638	dest_ref = NULL;
 639	if (destringid) {
 640		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 641					   KEY_WRITE);
 642		if (IS_ERR(dest_ref)) {
 643			ret = PTR_ERR(dest_ref);
 644			goto error3;
 645		}
 646	}
 647
 648	/* find the key type */
 649	ktype = key_type_lookup(type);
 650	if (IS_ERR(ktype)) {
 651		ret = PTR_ERR(ktype);
 652		goto error4;
 653	}
 654
 655	/* do the search */
 656	key_ref = keyring_search(keyring_ref, ktype, description);
 657	if (IS_ERR(key_ref)) {
 658		ret = PTR_ERR(key_ref);
 659
 660		/* treat lack or presence of a negative key the same */
 661		if (ret == -EAGAIN)
 662			ret = -ENOKEY;
 663		goto error5;
 664	}
 665
 666	/* link the resulting key to the destination keyring if we can */
 667	if (dest_ref) {
 668		ret = key_permission(key_ref, KEY_LINK);
 669		if (ret < 0)
 670			goto error6;
 671
 672		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 673		if (ret < 0)
 674			goto error6;
 675	}
 676
 677	ret = key_ref_to_ptr(key_ref)->serial;
 678
 679error6:
 680	key_ref_put(key_ref);
 681error5:
 682	key_type_put(ktype);
 683error4:
 684	key_ref_put(dest_ref);
 685error3:
 686	key_ref_put(keyring_ref);
 687error2:
 688	kfree(description);
 689error:
 690	return ret;
 691}
 692
 693/*
 694 * Read a key's payload.
 695 *
 696 * The key must either grant the caller Read permission, or it must grant the
 697 * caller Search permission when searched for from the process keyrings.
 698 *
 699 * If successful, we place up to buflen bytes of data into the buffer, if one
 700 * is provided, and return the amount of data that is available in the key,
 701 * irrespective of how much we copied into the buffer.
 702 */
 703long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 704{
 705	struct key *key;
 706	key_ref_t key_ref;
 707	long ret;
 708
 709	/* find the key first */
 710	key_ref = lookup_user_key(keyid, 0, 0);
 711	if (IS_ERR(key_ref)) {
 712		ret = -ENOKEY;
 713		goto error;
 714	}
 715
 716	key = key_ref_to_ptr(key_ref);
 717
 718	/* see if we can read it directly */
 719	ret = key_permission(key_ref, KEY_READ);
 720	if (ret == 0)
 721		goto can_read_key;
 722	if (ret != -EACCES)
 723		goto error;
 724
 725	/* we can't; see if it's searchable from this process's keyrings
 726	 * - we automatically take account of the fact that it may be
 727	 *   dangling off an instantiation key
 728	 */
 729	if (!is_key_possessed(key_ref)) {
 730		ret = -EACCES;
 731		goto error2;
 732	}
 733
 734	/* the key is probably readable - now try to read it */
 735can_read_key:
 736	ret = key_validate(key);
 737	if (ret == 0) {
 738		ret = -EOPNOTSUPP;
 739		if (key->type->read) {
 740			/* read the data with the semaphore held (since we
 741			 * might sleep) */
 742			down_read(&key->sem);
 743			ret = key->type->read(key, buffer, buflen);
 744			up_read(&key->sem);
 745		}
 746	}
 747
 748error2:
 749	key_put(key);
 750error:
 751	return ret;
 752}
 753
 754/*
 755 * Change the ownership of a key
 756 *
 757 * The key must grant the caller Setattr permission for this to work, though
 758 * the key need not be fully instantiated yet.  For the UID to be changed, or
 759 * for the GID to be changed to a group the caller is not a member of, the
 760 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 761 * attribute is not changed.
 762 *
 763 * If the UID is to be changed, the new user must have sufficient quota to
 764 * accept the key.  The quota deduction will be removed from the old user to
 765 * the new user should the attribute be changed.
 766 *
 767 * If successful, 0 will be returned.
 768 */
 769long keyctl_chown_key(key_serial_t id, uid_t uid, gid_t gid)
 770{
 771	struct key_user *newowner, *zapowner = NULL;
 772	struct key *key;
 773	key_ref_t key_ref;
 774	long ret;
 
 
 
 
 
 
 
 
 
 
 775
 776	ret = 0;
 777	if (uid == (uid_t) -1 && gid == (gid_t) -1)
 778		goto error;
 779
 780	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 781				  KEY_SETATTR);
 782	if (IS_ERR(key_ref)) {
 783		ret = PTR_ERR(key_ref);
 784		goto error;
 785	}
 786
 787	key = key_ref_to_ptr(key_ref);
 788
 789	/* make the changes with the locks held to prevent chown/chown races */
 790	ret = -EACCES;
 791	down_write(&key->sem);
 792
 793	if (!capable(CAP_SYS_ADMIN)) {
 794		/* only the sysadmin can chown a key to some other UID */
 795		if (uid != (uid_t) -1 && key->uid != uid)
 796			goto error_put;
 797
 798		/* only the sysadmin can set the key's GID to a group other
 799		 * than one of those that the current process subscribes to */
 800		if (gid != (gid_t) -1 && gid != key->gid && !in_group_p(gid))
 801			goto error_put;
 802	}
 803
 804	/* change the UID */
 805	if (uid != (uid_t) -1 && uid != key->uid) {
 806		ret = -ENOMEM;
 807		newowner = key_user_lookup(uid, current_user_ns());
 808		if (!newowner)
 809			goto error_put;
 810
 811		/* transfer the quota burden to the new user */
 812		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 813			unsigned maxkeys = (uid == 0) ?
 814				key_quota_root_maxkeys : key_quota_maxkeys;
 815			unsigned maxbytes = (uid == 0) ?
 816				key_quota_root_maxbytes : key_quota_maxbytes;
 817
 818			spin_lock(&newowner->lock);
 819			if (newowner->qnkeys + 1 >= maxkeys ||
 820			    newowner->qnbytes + key->quotalen >= maxbytes ||
 821			    newowner->qnbytes + key->quotalen <
 822			    newowner->qnbytes)
 823				goto quota_overrun;
 824
 825			newowner->qnkeys++;
 826			newowner->qnbytes += key->quotalen;
 827			spin_unlock(&newowner->lock);
 828
 829			spin_lock(&key->user->lock);
 830			key->user->qnkeys--;
 831			key->user->qnbytes -= key->quotalen;
 832			spin_unlock(&key->user->lock);
 833		}
 834
 835		atomic_dec(&key->user->nkeys);
 836		atomic_inc(&newowner->nkeys);
 837
 838		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 839			atomic_dec(&key->user->nikeys);
 840			atomic_inc(&newowner->nikeys);
 841		}
 842
 843		zapowner = key->user;
 844		key->user = newowner;
 845		key->uid = uid;
 846	}
 847
 848	/* change the GID */
 849	if (gid != (gid_t) -1)
 850		key->gid = gid;
 851
 852	ret = 0;
 853
 854error_put:
 855	up_write(&key->sem);
 856	key_put(key);
 857	if (zapowner)
 858		key_user_put(zapowner);
 859error:
 860	return ret;
 861
 862quota_overrun:
 863	spin_unlock(&newowner->lock);
 864	zapowner = newowner;
 865	ret = -EDQUOT;
 866	goto error_put;
 867}
 868
 869/*
 870 * Change the permission mask on a key.
 871 *
 872 * The key must grant the caller Setattr permission for this to work, though
 873 * the key need not be fully instantiated yet.  If the caller does not have
 874 * sysadmin capability, it may only change the permission on keys that it owns.
 875 */
 876long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 877{
 878	struct key *key;
 879	key_ref_t key_ref;
 880	long ret;
 881
 882	ret = -EINVAL;
 883	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 884		goto error;
 885
 886	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 887				  KEY_SETATTR);
 888	if (IS_ERR(key_ref)) {
 889		ret = PTR_ERR(key_ref);
 890		goto error;
 891	}
 892
 893	key = key_ref_to_ptr(key_ref);
 894
 895	/* make the changes with the locks held to prevent chown/chmod races */
 896	ret = -EACCES;
 897	down_write(&key->sem);
 898
 899	/* if we're not the sysadmin, we can only change a key that we own */
 900	if (capable(CAP_SYS_ADMIN) || key->uid == current_fsuid()) {
 901		key->perm = perm;
 902		ret = 0;
 903	}
 904
 905	up_write(&key->sem);
 906	key_put(key);
 907error:
 908	return ret;
 909}
 910
 911/*
 912 * Get the destination keyring for instantiation and check that the caller has
 913 * Write permission on it.
 914 */
 915static long get_instantiation_keyring(key_serial_t ringid,
 916				      struct request_key_auth *rka,
 917				      struct key **_dest_keyring)
 918{
 919	key_ref_t dkref;
 920
 921	*_dest_keyring = NULL;
 922
 923	/* just return a NULL pointer if we weren't asked to make a link */
 924	if (ringid == 0)
 925		return 0;
 926
 927	/* if a specific keyring is nominated by ID, then use that */
 928	if (ringid > 0) {
 929		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_WRITE);
 930		if (IS_ERR(dkref))
 931			return PTR_ERR(dkref);
 932		*_dest_keyring = key_ref_to_ptr(dkref);
 933		return 0;
 934	}
 935
 936	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 937		return -EINVAL;
 938
 939	/* otherwise specify the destination keyring recorded in the
 940	 * authorisation key (any KEY_SPEC_*_KEYRING) */
 941	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 942		*_dest_keyring = key_get(rka->dest_keyring);
 943		return 0;
 944	}
 945
 946	return -ENOKEY;
 947}
 948
 949/*
 950 * Change the request_key authorisation key on the current process.
 951 */
 952static int keyctl_change_reqkey_auth(struct key *key)
 953{
 954	struct cred *new;
 955
 956	new = prepare_creds();
 957	if (!new)
 958		return -ENOMEM;
 959
 960	key_put(new->request_key_auth);
 961	new->request_key_auth = key_get(key);
 962
 963	return commit_creds(new);
 964}
 965
 966/*
 967 * Copy the iovec data from userspace
 968 */
 969static long copy_from_user_iovec(void *buffer, const struct iovec *iov,
 970				 unsigned ioc)
 971{
 972	for (; ioc > 0; ioc--) {
 973		if (copy_from_user(buffer, iov->iov_base, iov->iov_len) != 0)
 974			return -EFAULT;
 975		buffer += iov->iov_len;
 976		iov++;
 977	}
 978	return 0;
 979}
 980
 981/*
 982 * Instantiate a key with the specified payload and link the key into the
 983 * destination keyring if one is given.
 984 *
 985 * The caller must have the appropriate instantiation permit set for this to
 986 * work (see keyctl_assume_authority).  No other permissions are required.
 987 *
 988 * If successful, 0 will be returned.
 989 */
 990long keyctl_instantiate_key_common(key_serial_t id,
 991				   const struct iovec *payload_iov,
 992				   unsigned ioc,
 993				   size_t plen,
 994				   key_serial_t ringid)
 995{
 996	const struct cred *cred = current_cred();
 997	struct request_key_auth *rka;
 998	struct key *instkey, *dest_keyring;
 999	void *payload;
1000	long ret;
1001	bool vm = false;
1002
1003	kenter("%d,,%zu,%d", id, plen, ringid);
1004
1005	ret = -EINVAL;
1006	if (plen > 1024 * 1024 - 1)
1007		goto error;
1008
1009	/* the appropriate instantiation authorisation key must have been
1010	 * assumed before calling this */
1011	ret = -EPERM;
1012	instkey = cred->request_key_auth;
1013	if (!instkey)
1014		goto error;
1015
1016	rka = instkey->payload.data;
1017	if (rka->target_key->serial != id)
1018		goto error;
1019
1020	/* pull the payload in if one was supplied */
1021	payload = NULL;
1022
1023	if (payload_iov) {
1024		ret = -ENOMEM;
1025		payload = kmalloc(plen, GFP_KERNEL);
1026		if (!payload) {
1027			if (plen <= PAGE_SIZE)
1028				goto error;
1029			vm = true;
1030			payload = vmalloc(plen);
1031			if (!payload)
1032				goto error;
1033		}
1034
1035		ret = copy_from_user_iovec(payload, payload_iov, ioc);
1036		if (ret < 0)
1037			goto error2;
1038	}
1039
1040	/* find the destination keyring amongst those belonging to the
1041	 * requesting task */
1042	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1043	if (ret < 0)
1044		goto error2;
1045
1046	/* instantiate the key and link it into a keyring */
1047	ret = key_instantiate_and_link(rka->target_key, payload, plen,
1048				       dest_keyring, instkey);
1049
1050	key_put(dest_keyring);
1051
1052	/* discard the assumed authority if it's just been disabled by
1053	 * instantiation of the key */
1054	if (ret == 0)
1055		keyctl_change_reqkey_auth(NULL);
1056
1057error2:
1058	if (!vm)
1059		kfree(payload);
1060	else
1061		vfree(payload);
1062error:
1063	return ret;
1064}
1065
1066/*
1067 * Instantiate a key with the specified payload and link the key into the
1068 * destination keyring if one is given.
1069 *
1070 * The caller must have the appropriate instantiation permit set for this to
1071 * work (see keyctl_assume_authority).  No other permissions are required.
1072 *
1073 * If successful, 0 will be returned.
1074 */
1075long keyctl_instantiate_key(key_serial_t id,
1076			    const void __user *_payload,
1077			    size_t plen,
1078			    key_serial_t ringid)
1079{
1080	if (_payload && plen) {
1081		struct iovec iov[1] = {
1082			[0].iov_base = (void __user *)_payload,
1083			[0].iov_len  = plen
1084		};
1085
1086		return keyctl_instantiate_key_common(id, iov, 1, plen, ringid);
1087	}
1088
1089	return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1090}
1091
1092/*
1093 * Instantiate a key with the specified multipart payload and link the key into
1094 * the destination keyring if one is given.
1095 *
1096 * The caller must have the appropriate instantiation permit set for this to
1097 * work (see keyctl_assume_authority).  No other permissions are required.
1098 *
1099 * If successful, 0 will be returned.
1100 */
1101long keyctl_instantiate_key_iov(key_serial_t id,
1102				const struct iovec __user *_payload_iov,
1103				unsigned ioc,
1104				key_serial_t ringid)
1105{
1106	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1107	long ret;
1108
1109	if (_payload_iov == 0 || ioc == 0)
1110		goto no_payload;
1111
1112	ret = rw_copy_check_uvector(WRITE, _payload_iov, ioc,
1113				    ARRAY_SIZE(iovstack), iovstack, &iov);
1114	if (ret < 0)
1115		return ret;
1116	if (ret == 0)
1117		goto no_payload_free;
1118
1119	ret = keyctl_instantiate_key_common(id, iov, ioc, ret, ringid);
1120
1121	if (iov != iovstack)
1122		kfree(iov);
1123	return ret;
1124
1125no_payload_free:
1126	if (iov != iovstack)
1127		kfree(iov);
1128no_payload:
1129	return keyctl_instantiate_key_common(id, NULL, 0, 0, ringid);
1130}
1131
1132/*
1133 * Negatively instantiate the key with the given timeout (in seconds) and link
1134 * the key into the destination keyring if one is given.
1135 *
1136 * The caller must have the appropriate instantiation permit set for this to
1137 * work (see keyctl_assume_authority).  No other permissions are required.
1138 *
1139 * The key and any links to the key will be automatically garbage collected
1140 * after the timeout expires.
1141 *
1142 * Negative keys are used to rate limit repeated request_key() calls by causing
1143 * them to return -ENOKEY until the negative key expires.
1144 *
1145 * If successful, 0 will be returned.
1146 */
1147long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1148{
1149	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1150}
1151
1152/*
1153 * Negatively instantiate the key with the given timeout (in seconds) and error
1154 * code and link the key into the destination keyring if one is given.
1155 *
1156 * The caller must have the appropriate instantiation permit set for this to
1157 * work (see keyctl_assume_authority).  No other permissions are required.
1158 *
1159 * The key and any links to the key will be automatically garbage collected
1160 * after the timeout expires.
1161 *
1162 * Negative keys are used to rate limit repeated request_key() calls by causing
1163 * them to return the specified error code until the negative key expires.
1164 *
1165 * If successful, 0 will be returned.
1166 */
1167long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1168		       key_serial_t ringid)
1169{
1170	const struct cred *cred = current_cred();
1171	struct request_key_auth *rka;
1172	struct key *instkey, *dest_keyring;
1173	long ret;
1174
1175	kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1176
1177	/* must be a valid error code and mustn't be a kernel special */
1178	if (error <= 0 ||
1179	    error >= MAX_ERRNO ||
1180	    error == ERESTARTSYS ||
1181	    error == ERESTARTNOINTR ||
1182	    error == ERESTARTNOHAND ||
1183	    error == ERESTART_RESTARTBLOCK)
1184		return -EINVAL;
1185
1186	/* the appropriate instantiation authorisation key must have been
1187	 * assumed before calling this */
1188	ret = -EPERM;
1189	instkey = cred->request_key_auth;
1190	if (!instkey)
1191		goto error;
1192
1193	rka = instkey->payload.data;
1194	if (rka->target_key->serial != id)
1195		goto error;
1196
1197	/* find the destination keyring if present (which must also be
1198	 * writable) */
1199	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1200	if (ret < 0)
1201		goto error;
1202
1203	/* instantiate the key and link it into a keyring */
1204	ret = key_reject_and_link(rka->target_key, timeout, error,
1205				  dest_keyring, instkey);
1206
1207	key_put(dest_keyring);
1208
1209	/* discard the assumed authority if it's just been disabled by
1210	 * instantiation of the key */
1211	if (ret == 0)
1212		keyctl_change_reqkey_auth(NULL);
1213
1214error:
1215	return ret;
1216}
1217
1218/*
1219 * Read or set the default keyring in which request_key() will cache keys and
1220 * return the old setting.
1221 *
1222 * If a process keyring is specified then this will be created if it doesn't
1223 * yet exist.  The old setting will be returned if successful.
1224 */
1225long keyctl_set_reqkey_keyring(int reqkey_defl)
1226{
1227	struct cred *new;
1228	int ret, old_setting;
1229
1230	old_setting = current_cred_xxx(jit_keyring);
1231
1232	if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1233		return old_setting;
1234
1235	new = prepare_creds();
1236	if (!new)
1237		return -ENOMEM;
1238
1239	switch (reqkey_defl) {
1240	case KEY_REQKEY_DEFL_THREAD_KEYRING:
1241		ret = install_thread_keyring_to_cred(new);
1242		if (ret < 0)
1243			goto error;
1244		goto set;
1245
1246	case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1247		ret = install_process_keyring_to_cred(new);
1248		if (ret < 0) {
1249			if (ret != -EEXIST)
1250				goto error;
1251			ret = 0;
1252		}
1253		goto set;
1254
1255	case KEY_REQKEY_DEFL_DEFAULT:
1256	case KEY_REQKEY_DEFL_SESSION_KEYRING:
1257	case KEY_REQKEY_DEFL_USER_KEYRING:
1258	case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1259	case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1260		goto set;
1261
1262	case KEY_REQKEY_DEFL_NO_CHANGE:
1263	case KEY_REQKEY_DEFL_GROUP_KEYRING:
1264	default:
1265		ret = -EINVAL;
1266		goto error;
1267	}
1268
1269set:
1270	new->jit_keyring = reqkey_defl;
1271	commit_creds(new);
1272	return old_setting;
1273error:
1274	abort_creds(new);
1275	return ret;
1276}
1277
1278/*
1279 * Set or clear the timeout on a key.
1280 *
1281 * Either the key must grant the caller Setattr permission or else the caller
1282 * must hold an instantiation authorisation token for the key.
1283 *
1284 * The timeout is either 0 to clear the timeout, or a number of seconds from
1285 * the current time.  The key and any links to the key will be automatically
1286 * garbage collected after the timeout expires.
1287 *
1288 * If successful, 0 is returned.
1289 */
1290long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1291{
1292	struct key *key, *instkey;
1293	key_ref_t key_ref;
1294	long ret;
1295
1296	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1297				  KEY_SETATTR);
1298	if (IS_ERR(key_ref)) {
1299		/* setting the timeout on a key under construction is permitted
1300		 * if we have the authorisation token handy */
1301		if (PTR_ERR(key_ref) == -EACCES) {
1302			instkey = key_get_instantiation_authkey(id);
1303			if (!IS_ERR(instkey)) {
1304				key_put(instkey);
1305				key_ref = lookup_user_key(id,
1306							  KEY_LOOKUP_PARTIAL,
1307							  0);
1308				if (!IS_ERR(key_ref))
1309					goto okay;
1310			}
1311		}
1312
1313		ret = PTR_ERR(key_ref);
1314		goto error;
1315	}
1316
1317okay:
1318	key = key_ref_to_ptr(key_ref);
1319	key_set_timeout(key, timeout);
1320	key_put(key);
1321
1322	ret = 0;
1323error:
1324	return ret;
1325}
1326
1327/*
1328 * Assume (or clear) the authority to instantiate the specified key.
1329 *
1330 * This sets the authoritative token currently in force for key instantiation.
1331 * This must be done for a key to be instantiated.  It has the effect of making
1332 * available all the keys from the caller of the request_key() that created a
1333 * key to request_key() calls made by the caller of this function.
1334 *
1335 * The caller must have the instantiation key in their process keyrings with a
1336 * Search permission grant available to the caller.
1337 *
1338 * If the ID given is 0, then the setting will be cleared and 0 returned.
1339 *
1340 * If the ID given has a matching an authorisation key, then that key will be
1341 * set and its ID will be returned.  The authorisation key can be read to get
1342 * the callout information passed to request_key().
1343 */
1344long keyctl_assume_authority(key_serial_t id)
1345{
1346	struct key *authkey;
1347	long ret;
1348
1349	/* special key IDs aren't permitted */
1350	ret = -EINVAL;
1351	if (id < 0)
1352		goto error;
1353
1354	/* we divest ourselves of authority if given an ID of 0 */
1355	if (id == 0) {
1356		ret = keyctl_change_reqkey_auth(NULL);
1357		goto error;
1358	}
1359
1360	/* attempt to assume the authority temporarily granted to us whilst we
1361	 * instantiate the specified key
1362	 * - the authorisation key must be in the current task's keyrings
1363	 *   somewhere
1364	 */
1365	authkey = key_get_instantiation_authkey(id);
1366	if (IS_ERR(authkey)) {
1367		ret = PTR_ERR(authkey);
1368		goto error;
1369	}
1370
1371	ret = keyctl_change_reqkey_auth(authkey);
1372	if (ret < 0)
1373		goto error;
1374	key_put(authkey);
1375
1376	ret = authkey->serial;
1377error:
1378	return ret;
1379}
1380
1381/*
1382 * Get a key's the LSM security label.
1383 *
1384 * The key must grant the caller View permission for this to work.
1385 *
1386 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1387 *
1388 * If successful, the amount of information available will be returned,
1389 * irrespective of how much was copied (including the terminal NUL).
1390 */
1391long keyctl_get_security(key_serial_t keyid,
1392			 char __user *buffer,
1393			 size_t buflen)
1394{
1395	struct key *key, *instkey;
1396	key_ref_t key_ref;
1397	char *context;
1398	long ret;
1399
1400	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_VIEW);
1401	if (IS_ERR(key_ref)) {
1402		if (PTR_ERR(key_ref) != -EACCES)
1403			return PTR_ERR(key_ref);
1404
1405		/* viewing a key under construction is also permitted if we
1406		 * have the authorisation token handy */
1407		instkey = key_get_instantiation_authkey(keyid);
1408		if (IS_ERR(instkey))
1409			return PTR_ERR(instkey);
1410		key_put(instkey);
1411
1412		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1413		if (IS_ERR(key_ref))
1414			return PTR_ERR(key_ref);
1415	}
1416
1417	key = key_ref_to_ptr(key_ref);
1418	ret = security_key_getsecurity(key, &context);
1419	if (ret == 0) {
1420		/* if no information was returned, give userspace an empty
1421		 * string */
1422		ret = 1;
1423		if (buffer && buflen > 0 &&
1424		    copy_to_user(buffer, "", 1) != 0)
1425			ret = -EFAULT;
1426	} else if (ret > 0) {
1427		/* return as much data as there's room for */
1428		if (buffer && buflen > 0) {
1429			if (buflen > ret)
1430				buflen = ret;
1431
1432			if (copy_to_user(buffer, context, buflen) != 0)
1433				ret = -EFAULT;
1434		}
1435
1436		kfree(context);
1437	}
1438
1439	key_ref_put(key_ref);
1440	return ret;
1441}
1442
1443/*
1444 * Attempt to install the calling process's session keyring on the process's
1445 * parent process.
1446 *
1447 * The keyring must exist and must grant the caller LINK permission, and the
1448 * parent process must be single-threaded and must have the same effective
1449 * ownership as this process and mustn't be SUID/SGID.
1450 *
1451 * The keyring will be emplaced on the parent when it next resumes userspace.
1452 *
1453 * If successful, 0 will be returned.
1454 */
1455long keyctl_session_to_parent(void)
1456{
1457	struct task_struct *me, *parent;
1458	const struct cred *mycred, *pcred;
1459	struct task_work *newwork, *oldwork;
1460	key_ref_t keyring_r;
1461	struct cred *cred;
1462	int ret;
1463
1464	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_LINK);
1465	if (IS_ERR(keyring_r))
1466		return PTR_ERR(keyring_r);
1467
1468	ret = -ENOMEM;
1469	newwork = kmalloc(sizeof(struct task_work), GFP_KERNEL);
1470	if (!newwork)
1471		goto error_keyring;
1472
1473	/* our parent is going to need a new cred struct, a new tgcred struct
1474	 * and new security data, so we allocate them here to prevent ENOMEM in
1475	 * our parent */
1476	cred = cred_alloc_blank();
1477	if (!cred)
1478		goto error_newwork;
 
1479
1480	cred->tgcred->session_keyring = key_ref_to_ptr(keyring_r);
1481	init_task_work(newwork, key_change_session_keyring, cred);
 
1482
1483	me = current;
1484	rcu_read_lock();
1485	write_lock_irq(&tasklist_lock);
1486
1487	ret = -EPERM;
1488	oldwork = NULL;
1489	parent = me->real_parent;
1490
1491	/* the parent mustn't be init and mustn't be a kernel thread */
1492	if (parent->pid <= 1 || !parent->mm)
1493		goto unlock;
1494
1495	/* the parent must be single threaded */
1496	if (!thread_group_empty(parent))
1497		goto unlock;
1498
1499	/* the parent and the child must have different session keyrings or
1500	 * there's no point */
1501	mycred = current_cred();
1502	pcred = __task_cred(parent);
1503	if (mycred == pcred ||
1504	    mycred->tgcred->session_keyring == pcred->tgcred->session_keyring) {
1505		ret = 0;
1506		goto unlock;
1507	}
1508
1509	/* the parent must have the same effective ownership and mustn't be
1510	 * SUID/SGID */
1511	if (pcred->uid	!= mycred->euid	||
1512	    pcred->euid	!= mycred->euid	||
1513	    pcred->suid	!= mycred->euid	||
1514	    pcred->gid	!= mycred->egid	||
1515	    pcred->egid	!= mycred->egid	||
1516	    pcred->sgid	!= mycred->egid)
1517		goto unlock;
1518
1519	/* the keyrings must have the same UID */
1520	if ((pcred->tgcred->session_keyring &&
1521	     pcred->tgcred->session_keyring->uid != mycred->euid) ||
1522	    mycred->tgcred->session_keyring->uid != mycred->euid)
1523		goto unlock;
1524
1525	/* cancel an already pending keyring replacement */
1526	oldwork = task_work_cancel(parent, key_change_session_keyring);
1527
1528	/* the replacement session keyring is applied just prior to userspace
1529	 * restarting */
1530	ret = task_work_add(parent, newwork, true);
1531	if (!ret)
1532		newwork = NULL;
1533unlock:
1534	write_unlock_irq(&tasklist_lock);
1535	rcu_read_unlock();
1536	if (oldwork) {
1537		put_cred(oldwork->data);
1538		kfree(oldwork);
1539	}
1540	if (newwork) {
1541		put_cred(newwork->data);
1542		kfree(newwork);
1543	}
1544	return ret;
1545
1546error_newwork:
1547	kfree(newwork);
1548error_keyring:
1549	key_ref_put(keyring_r);
1550	return ret;
1551}
1552
1553/*
1554 * The key control system call
1555 */
1556SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1557		unsigned long, arg4, unsigned long, arg5)
1558{
1559	switch (option) {
1560	case KEYCTL_GET_KEYRING_ID:
1561		return keyctl_get_keyring_ID((key_serial_t) arg2,
1562					     (int) arg3);
1563
1564	case KEYCTL_JOIN_SESSION_KEYRING:
1565		return keyctl_join_session_keyring((const char __user *) arg2);
1566
1567	case KEYCTL_UPDATE:
1568		return keyctl_update_key((key_serial_t) arg2,
1569					 (const void __user *) arg3,
1570					 (size_t) arg4);
1571
1572	case KEYCTL_REVOKE:
1573		return keyctl_revoke_key((key_serial_t) arg2);
1574
1575	case KEYCTL_DESCRIBE:
1576		return keyctl_describe_key((key_serial_t) arg2,
1577					   (char __user *) arg3,
1578					   (unsigned) arg4);
1579
1580	case KEYCTL_CLEAR:
1581		return keyctl_keyring_clear((key_serial_t) arg2);
1582
1583	case KEYCTL_LINK:
1584		return keyctl_keyring_link((key_serial_t) arg2,
1585					   (key_serial_t) arg3);
1586
1587	case KEYCTL_UNLINK:
1588		return keyctl_keyring_unlink((key_serial_t) arg2,
1589					     (key_serial_t) arg3);
1590
1591	case KEYCTL_SEARCH:
1592		return keyctl_keyring_search((key_serial_t) arg2,
1593					     (const char __user *) arg3,
1594					     (const char __user *) arg4,
1595					     (key_serial_t) arg5);
1596
1597	case KEYCTL_READ:
1598		return keyctl_read_key((key_serial_t) arg2,
1599				       (char __user *) arg3,
1600				       (size_t) arg4);
1601
1602	case KEYCTL_CHOWN:
1603		return keyctl_chown_key((key_serial_t) arg2,
1604					(uid_t) arg3,
1605					(gid_t) arg4);
1606
1607	case KEYCTL_SETPERM:
1608		return keyctl_setperm_key((key_serial_t) arg2,
1609					  (key_perm_t) arg3);
1610
1611	case KEYCTL_INSTANTIATE:
1612		return keyctl_instantiate_key((key_serial_t) arg2,
1613					      (const void __user *) arg3,
1614					      (size_t) arg4,
1615					      (key_serial_t) arg5);
1616
1617	case KEYCTL_NEGATE:
1618		return keyctl_negate_key((key_serial_t) arg2,
1619					 (unsigned) arg3,
1620					 (key_serial_t) arg4);
1621
1622	case KEYCTL_SET_REQKEY_KEYRING:
1623		return keyctl_set_reqkey_keyring(arg2);
1624
1625	case KEYCTL_SET_TIMEOUT:
1626		return keyctl_set_timeout((key_serial_t) arg2,
1627					  (unsigned) arg3);
1628
1629	case KEYCTL_ASSUME_AUTHORITY:
1630		return keyctl_assume_authority((key_serial_t) arg2);
1631
1632	case KEYCTL_GET_SECURITY:
1633		return keyctl_get_security((key_serial_t) arg2,
1634					   (char __user *) arg3,
1635					   (size_t) arg4);
1636
1637	case KEYCTL_SESSION_TO_PARENT:
1638		return keyctl_session_to_parent();
1639
1640	case KEYCTL_REJECT:
1641		return keyctl_reject_key((key_serial_t) arg2,
1642					 (unsigned) arg3,
1643					 (unsigned) arg4,
1644					 (key_serial_t) arg5);
1645
1646	case KEYCTL_INSTANTIATE_IOV:
1647		return keyctl_instantiate_key_iov(
1648			(key_serial_t) arg2,
1649			(const struct iovec __user *) arg3,
1650			(unsigned) arg4,
1651			(key_serial_t) arg5);
1652
1653	case KEYCTL_INVALIDATE:
1654		return keyctl_invalidate_key((key_serial_t) arg2);
 
 
 
1655
1656	default:
1657		return -EOPNOTSUPP;
1658	}
1659}