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