1/* Userspace key control operations
   2 *
   3 * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
   4 * Written by David Howells (dhowells@redhat.com)
   5 *
   6 * This program is free software; you can redistribute it and/or
   7 * modify it under the terms of the GNU General Public License
   8 * as published by the Free Software Foundation; either version
   9 * 2 of the License, or (at your option) any later version.
  10 */
  11
  12#include <linux/module.h>
  13#include <linux/init.h>
  14#include <linux/sched.h>
  15#include <linux/slab.h>
  16#include <linux/syscalls.h>
  17#include <linux/key.h>
  18#include <linux/keyctl.h>
  19#include <linux/fs.h>
  20#include <linux/capability.h>
  21#include <linux/string.h>
  22#include <linux/err.h>
  23#include <linux/vmalloc.h>
  24#include <linux/security.h>
  25#include <linux/uio.h>
  26#include <asm/uaccess.h>
  27#include "internal.h"
  28
  29#define KEY_MAX_DESC_SIZE 4096
  30
  31static int key_get_type_from_user(char *type,
  32				  const char __user *_type,
  33				  unsigned len)
  34{
  35	int ret;
  36
  37	ret = strncpy_from_user(type, _type, len);
  38	if (ret < 0)
  39		return ret;
  40	if (ret == 0 || ret >= len)
  41		return -EINVAL;
  42	if (type[0] == '.')
  43		return -EPERM;
  44	type[len - 1] = '\0';
  45	return 0;
  46}
  47
  48/*
  49 * Extract the description of a new key from userspace and either add it as a
  50 * new key to the specified keyring or update a matching key in that keyring.
  51 *
  52 * If the description is NULL or an empty string, the key type is asked to
  53 * generate one from the payload.
  54 *
  55 * The keyring must be writable so that we can attach the key to it.
  56 *
  57 * If successful, the new key's serial number is returned, otherwise an error
  58 * code is returned.
  59 */
  60SYSCALL_DEFINE5(add_key, const char __user *, _type,
  61		const char __user *, _description,
  62		const void __user *, _payload,
  63		size_t, plen,
  64		key_serial_t, ringid)
  65{
  66	key_ref_t keyring_ref, key_ref;
  67	char type[32], *description;
  68	void *payload;
  69	long ret;
 
  70
  71	ret = -EINVAL;
  72	if (plen > 1024 * 1024 - 1)
  73		goto error;
  74
  75	/* draw all the data into kernel space */
  76	ret = key_get_type_from_user(type, _type, sizeof(type));
  77	if (ret < 0)
  78		goto error;
  79
  80	description = NULL;
  81	if (_description) {
  82		description = strndup_user(_description, KEY_MAX_DESC_SIZE);
  83		if (IS_ERR(description)) {
  84			ret = PTR_ERR(description);
  85			goto error;
  86		}
  87		if (!*description) {
  88			kfree(description);
  89			description = NULL;
  90		} else if ((description[0] == '.') &&
  91			   (strncmp(type, "keyring", 7) == 0)) {
  92			ret = -EPERM;
  93			goto error2;
  94		}
  95	}
  96
  97	/* pull the payload in if one was supplied */
  98	payload = NULL;
  99
 
 100	if (_payload) {
 101		ret = -ENOMEM;
 102		payload = kmalloc(plen, GFP_KERNEL | __GFP_NOWARN);
 103		if (!payload) {
 104			if (plen <= PAGE_SIZE)
 105				goto error2;
 
 106			payload = vmalloc(plen);
 107			if (!payload)
 108				goto error2;
 109		}
 110
 111		ret = -EFAULT;
 112		if (copy_from_user(payload, _payload, plen) != 0)
 113			goto error3;
 114	}
 115
 116	/* find the target keyring (which must be writable) */
 117	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 118	if (IS_ERR(keyring_ref)) {
 119		ret = PTR_ERR(keyring_ref);
 120		goto error3;
 121	}
 122
 123	/* create or update the requested key and add it to the target
 124	 * keyring */
 125	key_ref = key_create_or_update(keyring_ref, type, description,
 126				       payload, plen, KEY_PERM_UNDEF,
 127				       KEY_ALLOC_IN_QUOTA);
 128	if (!IS_ERR(key_ref)) {
 129		ret = key_ref_to_ptr(key_ref)->serial;
 130		key_ref_put(key_ref);
 131	}
 132	else {
 133		ret = PTR_ERR(key_ref);
 134	}
 135
 136	key_ref_put(keyring_ref);
 137 error3:
 138	kvfree(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, KEY_MAX_DESC_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_NEED_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_NEED_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, KEY_MAX_DESC_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_NEED_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 * Keys with KEY_FLAG_KEEP set should not be revoked.
 362 *
 363 * If successful, 0 is returned.
 364 */
 365long keyctl_revoke_key(key_serial_t id)
 366{
 367	key_ref_t key_ref;
 368	struct key *key;
 369	long ret;
 370
 371	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
 372	if (IS_ERR(key_ref)) {
 373		ret = PTR_ERR(key_ref);
 374		if (ret != -EACCES)
 375			goto error;
 376		key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
 377		if (IS_ERR(key_ref)) {
 378			ret = PTR_ERR(key_ref);
 379			goto error;
 380		}
 381	}
 382
 383	key = key_ref_to_ptr(key_ref);
 384	ret = 0;
 385	if (test_bit(KEY_FLAG_KEEP, &key->flags))
 386		ret = -EPERM;
 387	else
 388		key_revoke(key);
 389
 390	key_ref_put(key_ref);
 391error:
 392	return ret;
 393}
 394
 395/*
 396 * Invalidate a key.
 397 *
 398 * The key must be grant the caller Invalidate permission for this to work.
 399 * The key and any links to the key will be automatically garbage collected
 400 * immediately.
 401 *
 402 * Keys with KEY_FLAG_KEEP set should not be invalidated.
 403 *
 404 * If successful, 0 is returned.
 405 */
 406long keyctl_invalidate_key(key_serial_t id)
 407{
 408	key_ref_t key_ref;
 409	struct key *key;
 410	long ret;
 411
 412	kenter("%d", id);
 413
 414	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
 415	if (IS_ERR(key_ref)) {
 416		ret = PTR_ERR(key_ref);
 417
 418		/* Root is permitted to invalidate certain special keys */
 419		if (capable(CAP_SYS_ADMIN)) {
 420			key_ref = lookup_user_key(id, 0, 0);
 421			if (IS_ERR(key_ref))
 422				goto error;
 423			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
 424				     &key_ref_to_ptr(key_ref)->flags))
 425				goto invalidate;
 426			goto error_put;
 427		}
 428
 429		goto error;
 430	}
 431
 432invalidate:
 433	key = key_ref_to_ptr(key_ref);
 434	ret = 0;
 435	if (test_bit(KEY_FLAG_KEEP, &key->flags))
 436		ret = -EPERM;
 437	else
 438		key_invalidate(key);
 439error_put:
 440	key_ref_put(key_ref);
 441error:
 442	kleave(" = %ld", ret);
 443	return ret;
 444}
 445
 446/*
 447 * Clear the specified keyring, creating an empty process keyring if one of the
 448 * special keyring IDs is used.
 449 *
 450 * The keyring must grant the caller Write permission and not have
 451 * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
 452 */
 453long keyctl_keyring_clear(key_serial_t ringid)
 454{
 455	key_ref_t keyring_ref;
 456	struct key *keyring;
 457	long ret;
 458
 459	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 460	if (IS_ERR(keyring_ref)) {
 461		ret = PTR_ERR(keyring_ref);
 462
 463		/* Root is permitted to invalidate certain special keyrings */
 464		if (capable(CAP_SYS_ADMIN)) {
 465			keyring_ref = lookup_user_key(ringid, 0, 0);
 466			if (IS_ERR(keyring_ref))
 467				goto error;
 468			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
 469				     &key_ref_to_ptr(keyring_ref)->flags))
 470				goto clear;
 471			goto error_put;
 472		}
 473
 474		goto error;
 475	}
 476
 477clear:
 478	keyring = key_ref_to_ptr(keyring_ref);
 479	if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
 480		ret = -EPERM;
 481	else
 482		ret = keyring_clear(keyring);
 483error_put:
 484	key_ref_put(keyring_ref);
 485error:
 486	return ret;
 487}
 488
 489/*
 490 * Create a link from a keyring to a key if there's no matching key in the
 491 * keyring, otherwise replace the link to the matching key with a link to the
 492 * new key.
 493 *
 494 * The key must grant the caller Link permission and the the keyring must grant
 495 * the caller Write permission.  Furthermore, if an additional link is created,
 496 * the keyring's quota will be extended.
 497 *
 498 * If successful, 0 will be returned.
 499 */
 500long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
 501{
 502	key_ref_t keyring_ref, key_ref;
 503	long ret;
 504
 505	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 506	if (IS_ERR(keyring_ref)) {
 507		ret = PTR_ERR(keyring_ref);
 508		goto error;
 509	}
 510
 511	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
 512	if (IS_ERR(key_ref)) {
 513		ret = PTR_ERR(key_ref);
 514		goto error2;
 515	}
 516
 517	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
 518
 519	key_ref_put(key_ref);
 520error2:
 521	key_ref_put(keyring_ref);
 522error:
 523	return ret;
 524}
 525
 526/*
 527 * Unlink a key from a keyring.
 528 *
 529 * The keyring must grant the caller Write permission for this to work; the key
 530 * itself need not grant the caller anything.  If the last link to a key is
 531 * removed then that key will be scheduled for destruction.
 532 *
 533 * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
 534 *
 535 * If successful, 0 will be returned.
 536 */
 537long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
 538{
 539	key_ref_t keyring_ref, key_ref;
 540	struct key *keyring, *key;
 541	long ret;
 542
 543	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
 544	if (IS_ERR(keyring_ref)) {
 545		ret = PTR_ERR(keyring_ref);
 546		goto error;
 547	}
 548
 549	key_ref = lookup_user_key(id, KEY_LOOKUP_FOR_UNLINK, 0);
 550	if (IS_ERR(key_ref)) {
 551		ret = PTR_ERR(key_ref);
 552		goto error2;
 553	}
 554
 555	keyring = key_ref_to_ptr(keyring_ref);
 556	key = key_ref_to_ptr(key_ref);
 557	if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
 558	    test_bit(KEY_FLAG_KEEP, &key->flags))
 559		ret = -EPERM;
 560	else
 561		ret = key_unlink(keyring, key);
 562
 563	key_ref_put(key_ref);
 564error2:
 565	key_ref_put(keyring_ref);
 566error:
 567	return ret;
 568}
 569
 570/*
 571 * Return a description of a key to userspace.
 572 *
 573 * The key must grant the caller View permission for this to work.
 574 *
 575 * If there's a buffer, we place up to buflen bytes of data into it formatted
 576 * in the following way:
 577 *
 578 *	type;uid;gid;perm;description<NUL>
 579 *
 580 * If successful, we return the amount of description available, irrespective
 581 * of how much we may have copied into the buffer.
 582 */
 583long keyctl_describe_key(key_serial_t keyid,
 584			 char __user *buffer,
 585			 size_t buflen)
 586{
 587	struct key *key, *instkey;
 588	key_ref_t key_ref;
 589	char *infobuf;
 590	long ret;
 591	int desclen, infolen;
 592
 593	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
 594	if (IS_ERR(key_ref)) {
 595		/* viewing a key under construction is permitted if we have the
 596		 * authorisation token handy */
 597		if (PTR_ERR(key_ref) == -EACCES) {
 598			instkey = key_get_instantiation_authkey(keyid);
 599			if (!IS_ERR(instkey)) {
 600				key_put(instkey);
 601				key_ref = lookup_user_key(keyid,
 602							  KEY_LOOKUP_PARTIAL,
 603							  0);
 604				if (!IS_ERR(key_ref))
 605					goto okay;
 606			}
 607		}
 608
 609		ret = PTR_ERR(key_ref);
 610		goto error;
 611	}
 612
 613okay:
 614	key = key_ref_to_ptr(key_ref);
 615	desclen = strlen(key->description);
 616
 617	/* calculate how much information we're going to return */
 618	ret = -ENOMEM;
 619	infobuf = kasprintf(GFP_KERNEL,
 620			    "%s;%d;%d;%08x;",
 621			    key->type->name,
 622			    from_kuid_munged(current_user_ns(), key->uid),
 623			    from_kgid_munged(current_user_ns(), key->gid),
 624			    key->perm);
 625	if (!infobuf)
 626		goto error2;
 627	infolen = strlen(infobuf);
 628	ret = infolen + desclen + 1;
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 629
 630	/* consider returning the data */
 631	if (buffer && buflen >= ret) {
 632		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
 633		    copy_to_user(buffer + infolen, key->description,
 634				 desclen + 1) != 0)
 
 635			ret = -EFAULT;
 636	}
 637
 638	kfree(infobuf);
 639error2:
 640	key_ref_put(key_ref);
 641error:
 642	return ret;
 643}
 644
 645/*
 646 * Search the specified keyring and any keyrings it links to for a matching
 647 * key.  Only keyrings that grant the caller Search permission will be searched
 648 * (this includes the starting keyring).  Only keys with Search permission can
 649 * be found.
 650 *
 651 * If successful, the found key will be linked to the destination keyring if
 652 * supplied and the key has Link permission, and the found key ID will be
 653 * returned.
 654 */
 655long keyctl_keyring_search(key_serial_t ringid,
 656			   const char __user *_type,
 657			   const char __user *_description,
 658			   key_serial_t destringid)
 659{
 660	struct key_type *ktype;
 661	key_ref_t keyring_ref, key_ref, dest_ref;
 662	char type[32], *description;
 663	long ret;
 664
 665	/* pull the type and description into kernel space */
 666	ret = key_get_type_from_user(type, _type, sizeof(type));
 667	if (ret < 0)
 668		goto error;
 669
 670	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
 671	if (IS_ERR(description)) {
 672		ret = PTR_ERR(description);
 673		goto error;
 674	}
 675
 676	/* get the keyring at which to begin the search */
 677	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
 678	if (IS_ERR(keyring_ref)) {
 679		ret = PTR_ERR(keyring_ref);
 680		goto error2;
 681	}
 682
 683	/* get the destination keyring if specified */
 684	dest_ref = NULL;
 685	if (destringid) {
 686		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
 687					   KEY_NEED_WRITE);
 688		if (IS_ERR(dest_ref)) {
 689			ret = PTR_ERR(dest_ref);
 690			goto error3;
 691		}
 692	}
 693
 694	/* find the key type */
 695	ktype = key_type_lookup(type);
 696	if (IS_ERR(ktype)) {
 697		ret = PTR_ERR(ktype);
 698		goto error4;
 699	}
 700
 701	/* do the search */
 702	key_ref = keyring_search(keyring_ref, ktype, description);
 703	if (IS_ERR(key_ref)) {
 704		ret = PTR_ERR(key_ref);
 705
 706		/* treat lack or presence of a negative key the same */
 707		if (ret == -EAGAIN)
 708			ret = -ENOKEY;
 709		goto error5;
 710	}
 711
 712	/* link the resulting key to the destination keyring if we can */
 713	if (dest_ref) {
 714		ret = key_permission(key_ref, KEY_NEED_LINK);
 715		if (ret < 0)
 716			goto error6;
 717
 718		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
 719		if (ret < 0)
 720			goto error6;
 721	}
 722
 723	ret = key_ref_to_ptr(key_ref)->serial;
 724
 725error6:
 726	key_ref_put(key_ref);
 727error5:
 728	key_type_put(ktype);
 729error4:
 730	key_ref_put(dest_ref);
 731error3:
 732	key_ref_put(keyring_ref);
 733error2:
 734	kfree(description);
 735error:
 736	return ret;
 737}
 738
 739/*
 740 * Read a key's payload.
 741 *
 742 * The key must either grant the caller Read permission, or it must grant the
 743 * caller Search permission when searched for from the process keyrings.
 744 *
 745 * If successful, we place up to buflen bytes of data into the buffer, if one
 746 * is provided, and return the amount of data that is available in the key,
 747 * irrespective of how much we copied into the buffer.
 748 */
 749long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
 750{
 751	struct key *key;
 752	key_ref_t key_ref;
 753	long ret;
 754
 755	/* find the key first */
 756	key_ref = lookup_user_key(keyid, 0, 0);
 757	if (IS_ERR(key_ref)) {
 758		ret = -ENOKEY;
 759		goto error;
 760	}
 761
 762	key = key_ref_to_ptr(key_ref);
 763
 764	/* see if we can read it directly */
 765	ret = key_permission(key_ref, KEY_NEED_READ);
 766	if (ret == 0)
 767		goto can_read_key;
 768	if (ret != -EACCES)
 769		goto error;
 770
 771	/* we can't; see if it's searchable from this process's keyrings
 772	 * - we automatically take account of the fact that it may be
 773	 *   dangling off an instantiation key
 774	 */
 775	if (!is_key_possessed(key_ref)) {
 776		ret = -EACCES;
 777		goto error2;
 778	}
 779
 780	/* the key is probably readable - now try to read it */
 781can_read_key:
 782	ret = -EOPNOTSUPP;
 783	if (key->type->read) {
 784		/* Read the data with the semaphore held (since we might sleep)
 785		 * to protect against the key being updated or revoked.
 786		 */
 787		down_read(&key->sem);
 788		ret = key_validate(key);
 789		if (ret == 0)
 790			ret = key->type->read(key, buffer, buflen);
 791		up_read(&key->sem);
 
 792	}
 793
 794error2:
 795	key_put(key);
 796error:
 797	return ret;
 798}
 799
 800/*
 801 * Change the ownership of a key
 802 *
 803 * The key must grant the caller Setattr permission for this to work, though
 804 * the key need not be fully instantiated yet.  For the UID to be changed, or
 805 * for the GID to be changed to a group the caller is not a member of, the
 806 * caller must have sysadmin capability.  If either uid or gid is -1 then that
 807 * attribute is not changed.
 808 *
 809 * If the UID is to be changed, the new user must have sufficient quota to
 810 * accept the key.  The quota deduction will be removed from the old user to
 811 * the new user should the attribute be changed.
 812 *
 813 * If successful, 0 will be returned.
 814 */
 815long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
 816{
 817	struct key_user *newowner, *zapowner = NULL;
 818	struct key *key;
 819	key_ref_t key_ref;
 820	long ret;
 821	kuid_t uid;
 822	kgid_t gid;
 823
 824	uid = make_kuid(current_user_ns(), user);
 825	gid = make_kgid(current_user_ns(), group);
 826	ret = -EINVAL;
 827	if ((user != (uid_t) -1) && !uid_valid(uid))
 828		goto error;
 829	if ((group != (gid_t) -1) && !gid_valid(gid))
 830		goto error;
 831
 832	ret = 0;
 833	if (user == (uid_t) -1 && group == (gid_t) -1)
 834		goto error;
 835
 836	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 837				  KEY_NEED_SETATTR);
 838	if (IS_ERR(key_ref)) {
 839		ret = PTR_ERR(key_ref);
 840		goto error;
 841	}
 842
 843	key = key_ref_to_ptr(key_ref);
 844
 845	/* make the changes with the locks held to prevent chown/chown races */
 846	ret = -EACCES;
 847	down_write(&key->sem);
 848
 849	if (!capable(CAP_SYS_ADMIN)) {
 850		/* only the sysadmin can chown a key to some other UID */
 851		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
 852			goto error_put;
 853
 854		/* only the sysadmin can set the key's GID to a group other
 855		 * than one of those that the current process subscribes to */
 856		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
 857			goto error_put;
 858	}
 859
 860	/* change the UID */
 861	if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
 862		ret = -ENOMEM;
 863		newowner = key_user_lookup(uid);
 864		if (!newowner)
 865			goto error_put;
 866
 867		/* transfer the quota burden to the new user */
 868		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
 869			unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
 870				key_quota_root_maxkeys : key_quota_maxkeys;
 871			unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
 872				key_quota_root_maxbytes : key_quota_maxbytes;
 873
 874			spin_lock(&newowner->lock);
 875			if (newowner->qnkeys + 1 >= maxkeys ||
 876			    newowner->qnbytes + key->quotalen >= maxbytes ||
 877			    newowner->qnbytes + key->quotalen <
 878			    newowner->qnbytes)
 879				goto quota_overrun;
 880
 881			newowner->qnkeys++;
 882			newowner->qnbytes += key->quotalen;
 883			spin_unlock(&newowner->lock);
 884
 885			spin_lock(&key->user->lock);
 886			key->user->qnkeys--;
 887			key->user->qnbytes -= key->quotalen;
 888			spin_unlock(&key->user->lock);
 889		}
 890
 891		atomic_dec(&key->user->nkeys);
 892		atomic_inc(&newowner->nkeys);
 893
 894		if (test_bit(KEY_FLAG_INSTANTIATED, &key->flags)) {
 895			atomic_dec(&key->user->nikeys);
 896			atomic_inc(&newowner->nikeys);
 897		}
 898
 899		zapowner = key->user;
 900		key->user = newowner;
 901		key->uid = uid;
 902	}
 903
 904	/* change the GID */
 905	if (group != (gid_t) -1)
 906		key->gid = gid;
 907
 908	ret = 0;
 909
 910error_put:
 911	up_write(&key->sem);
 912	key_put(key);
 913	if (zapowner)
 914		key_user_put(zapowner);
 915error:
 916	return ret;
 917
 918quota_overrun:
 919	spin_unlock(&newowner->lock);
 920	zapowner = newowner;
 921	ret = -EDQUOT;
 922	goto error_put;
 923}
 924
 925/*
 926 * Change the permission mask on a key.
 927 *
 928 * The key must grant the caller Setattr permission for this to work, though
 929 * the key need not be fully instantiated yet.  If the caller does not have
 930 * sysadmin capability, it may only change the permission on keys that it owns.
 931 */
 932long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
 933{
 934	struct key *key;
 935	key_ref_t key_ref;
 936	long ret;
 937
 938	ret = -EINVAL;
 939	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
 940		goto error;
 941
 942	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
 943				  KEY_NEED_SETATTR);
 944	if (IS_ERR(key_ref)) {
 945		ret = PTR_ERR(key_ref);
 946		goto error;
 947	}
 948
 949	key = key_ref_to_ptr(key_ref);
 950
 951	/* make the changes with the locks held to prevent chown/chmod races */
 952	ret = -EACCES;
 953	down_write(&key->sem);
 954
 955	/* if we're not the sysadmin, we can only change a key that we own */
 956	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
 957		key->perm = perm;
 958		ret = 0;
 959	}
 960
 961	up_write(&key->sem);
 962	key_put(key);
 963error:
 964	return ret;
 965}
 966
 967/*
 968 * Get the destination keyring for instantiation and check that the caller has
 969 * Write permission on it.
 970 */
 971static long get_instantiation_keyring(key_serial_t ringid,
 972				      struct request_key_auth *rka,
 973				      struct key **_dest_keyring)
 974{
 975	key_ref_t dkref;
 976
 977	*_dest_keyring = NULL;
 978
 979	/* just return a NULL pointer if we weren't asked to make a link */
 980	if (ringid == 0)
 981		return 0;
 982
 983	/* if a specific keyring is nominated by ID, then use that */
 984	if (ringid > 0) {
 985		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
 986		if (IS_ERR(dkref))
 987			return PTR_ERR(dkref);
 988		*_dest_keyring = key_ref_to_ptr(dkref);
 989		return 0;
 990	}
 991
 992	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
 993		return -EINVAL;
 994
 995	/* otherwise specify the destination keyring recorded in the
 996	 * authorisation key (any KEY_SPEC_*_KEYRING) */
 997	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
 998		*_dest_keyring = key_get(rka->dest_keyring);
 999		return 0;
1000	}
1001
1002	return -ENOKEY;
1003}
1004
1005/*
1006 * Change the request_key authorisation key on the current process.
1007 */
1008static int keyctl_change_reqkey_auth(struct key *key)
1009{
1010	struct cred *new;
1011
1012	new = prepare_creds();
1013	if (!new)
1014		return -ENOMEM;
1015
1016	key_put(new->request_key_auth);
1017	new->request_key_auth = key_get(key);
1018
1019	return commit_creds(new);
1020}
1021
1022/*
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
1023 * Instantiate a key with the specified payload and link the key into the
1024 * destination keyring if one is given.
1025 *
1026 * The caller must have the appropriate instantiation permit set for this to
1027 * work (see keyctl_assume_authority).  No other permissions are required.
1028 *
1029 * If successful, 0 will be returned.
1030 */
1031long keyctl_instantiate_key_common(key_serial_t id,
1032				   struct iov_iter *from,
 
 
1033				   key_serial_t ringid)
1034{
1035	const struct cred *cred = current_cred();
1036	struct request_key_auth *rka;
1037	struct key *instkey, *dest_keyring;
1038	size_t plen = from ? iov_iter_count(from) : 0;
1039	void *payload;
1040	long ret;
 
1041
1042	kenter("%d,,%zu,%d", id, plen, ringid);
1043
1044	if (!plen)
1045		from = NULL;
1046
1047	ret = -EINVAL;
1048	if (plen > 1024 * 1024 - 1)
1049		goto error;
1050
1051	/* the appropriate instantiation authorisation key must have been
1052	 * assumed before calling this */
1053	ret = -EPERM;
1054	instkey = cred->request_key_auth;
1055	if (!instkey)
1056		goto error;
1057
1058	rka = instkey->payload.data[0];
1059	if (rka->target_key->serial != id)
1060		goto error;
1061
1062	/* pull the payload in if one was supplied */
1063	payload = NULL;
1064
1065	if (from) {
1066		ret = -ENOMEM;
1067		payload = kmalloc(plen, GFP_KERNEL);
1068		if (!payload) {
1069			if (plen <= PAGE_SIZE)
1070				goto error;
 
1071			payload = vmalloc(plen);
1072			if (!payload)
1073				goto error;
1074		}
1075
1076		ret = -EFAULT;
1077		if (copy_from_iter(payload, plen, from) != plen)
1078			goto error2;
1079	}
1080
1081	/* find the destination keyring amongst those belonging to the
1082	 * requesting task */
1083	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1084	if (ret < 0)
1085		goto error2;
1086
1087	/* instantiate the key and link it into a keyring */
1088	ret = key_instantiate_and_link(rka->target_key, payload, plen,
1089				       dest_keyring, instkey);
1090
1091	key_put(dest_keyring);
1092
1093	/* discard the assumed authority if it's just been disabled by
1094	 * instantiation of the key */
1095	if (ret == 0)
1096		keyctl_change_reqkey_auth(NULL);
1097
1098error2:
1099	kvfree(payload);
 
 
 
1100error:
1101	return ret;
1102}
1103
1104/*
1105 * Instantiate a key with the specified payload and link the key into the
1106 * destination keyring if one is given.
1107 *
1108 * The caller must have the appropriate instantiation permit set for this to
1109 * work (see keyctl_assume_authority).  No other permissions are required.
1110 *
1111 * If successful, 0 will be returned.
1112 */
1113long keyctl_instantiate_key(key_serial_t id,
1114			    const void __user *_payload,
1115			    size_t plen,
1116			    key_serial_t ringid)
1117{
1118	if (_payload && plen) {
1119		struct iovec iov;
1120		struct iov_iter from;
1121		int ret;
1122
1123		ret = import_single_range(WRITE, (void __user *)_payload, plen,
1124					  &iov, &from);
1125		if (unlikely(ret))
1126			return ret;
1127
1128		return keyctl_instantiate_key_common(id, &from, ringid);
1129	}
1130
1131	return keyctl_instantiate_key_common(id, NULL, ringid);
1132}
1133
1134/*
1135 * Instantiate a key with the specified multipart payload and link the key into
1136 * the destination keyring if one is given.
1137 *
1138 * The caller must have the appropriate instantiation permit set for this to
1139 * work (see keyctl_assume_authority).  No other permissions are required.
1140 *
1141 * If successful, 0 will be returned.
1142 */
1143long keyctl_instantiate_key_iov(key_serial_t id,
1144				const struct iovec __user *_payload_iov,
1145				unsigned ioc,
1146				key_serial_t ringid)
1147{
1148	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1149	struct iov_iter from;
1150	long ret;
1151
1152	if (!_payload_iov)
1153		ioc = 0;
1154
1155	ret = import_iovec(WRITE, _payload_iov, ioc,
1156				    ARRAY_SIZE(iovstack), &iov, &from);
1157	if (ret < 0)
1158		return ret;
1159	ret = keyctl_instantiate_key_common(id, &from, ringid);
1160	kfree(iov);
 
 
 
 
 
1161	return ret;
 
 
 
 
 
 
1162}
1163
1164/*
1165 * Negatively instantiate the key with the given timeout (in seconds) and link
1166 * the key into the destination keyring if one is given.
1167 *
1168 * The caller must have the appropriate instantiation permit set for this to
1169 * work (see keyctl_assume_authority).  No other permissions are required.
1170 *
1171 * The key and any links to the key will be automatically garbage collected
1172 * after the timeout expires.
1173 *
1174 * Negative keys are used to rate limit repeated request_key() calls by causing
1175 * them to return -ENOKEY until the negative key expires.
1176 *
1177 * If successful, 0 will be returned.
1178 */
1179long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1180{
1181	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1182}
1183
1184/*
1185 * Negatively instantiate the key with the given timeout (in seconds) and error
1186 * code and link the key into the destination keyring if one is given.
1187 *
1188 * The caller must have the appropriate instantiation permit set for this to
1189 * work (see keyctl_assume_authority).  No other permissions are required.
1190 *
1191 * The key and any links to the key will be automatically garbage collected
1192 * after the timeout expires.
1193 *
1194 * Negative keys are used to rate limit repeated request_key() calls by causing
1195 * them to return the specified error code until the negative key expires.
1196 *
1197 * If successful, 0 will be returned.
1198 */
1199long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1200		       key_serial_t ringid)
1201{
1202	const struct cred *cred = current_cred();
1203	struct request_key_auth *rka;
1204	struct key *instkey, *dest_keyring;
1205	long ret;
1206
1207	kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1208
1209	/* must be a valid error code and mustn't be a kernel special */
1210	if (error <= 0 ||
1211	    error >= MAX_ERRNO ||
1212	    error == ERESTARTSYS ||
1213	    error == ERESTARTNOINTR ||
1214	    error == ERESTARTNOHAND ||
1215	    error == ERESTART_RESTARTBLOCK)
1216		return -EINVAL;
1217
1218	/* the appropriate instantiation authorisation key must have been
1219	 * assumed before calling this */
1220	ret = -EPERM;
1221	instkey = cred->request_key_auth;
1222	if (!instkey)
1223		goto error;
1224
1225	rka = instkey->payload.data[0];
1226	if (rka->target_key->serial != id)
1227		goto error;
1228
1229	/* find the destination keyring if present (which must also be
1230	 * writable) */
1231	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1232	if (ret < 0)
1233		goto error;
1234
1235	/* instantiate the key and link it into a keyring */
1236	ret = key_reject_and_link(rka->target_key, timeout, error,
1237				  dest_keyring, instkey);
1238
1239	key_put(dest_keyring);
1240
1241	/* discard the assumed authority if it's just been disabled by
1242	 * instantiation of the key */
1243	if (ret == 0)
1244		keyctl_change_reqkey_auth(NULL);
1245
1246error:
1247	return ret;
1248}
1249
1250/*
1251 * Read or set the default keyring in which request_key() will cache keys and
1252 * return the old setting.
1253 *
1254 * If a process keyring is specified then this will be created if it doesn't
1255 * yet exist.  The old setting will be returned if successful.
1256 */
1257long keyctl_set_reqkey_keyring(int reqkey_defl)
1258{
1259	struct cred *new;
1260	int ret, old_setting;
1261
1262	old_setting = current_cred_xxx(jit_keyring);
1263
1264	if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1265		return old_setting;
1266
1267	new = prepare_creds();
1268	if (!new)
1269		return -ENOMEM;
1270
1271	switch (reqkey_defl) {
1272	case KEY_REQKEY_DEFL_THREAD_KEYRING:
1273		ret = install_thread_keyring_to_cred(new);
1274		if (ret < 0)
1275			goto error;
1276		goto set;
1277
1278	case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1279		ret = install_process_keyring_to_cred(new);
1280		if (ret < 0) {
1281			if (ret != -EEXIST)
1282				goto error;
1283			ret = 0;
1284		}
1285		goto set;
1286
1287	case KEY_REQKEY_DEFL_DEFAULT:
1288	case KEY_REQKEY_DEFL_SESSION_KEYRING:
1289	case KEY_REQKEY_DEFL_USER_KEYRING:
1290	case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1291	case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1292		goto set;
1293
1294	case KEY_REQKEY_DEFL_NO_CHANGE:
1295	case KEY_REQKEY_DEFL_GROUP_KEYRING:
1296	default:
1297		ret = -EINVAL;
1298		goto error;
1299	}
1300
1301set:
1302	new->jit_keyring = reqkey_defl;
1303	commit_creds(new);
1304	return old_setting;
1305error:
1306	abort_creds(new);
1307	return ret;
1308}
1309
1310/*
1311 * Set or clear the timeout on a key.
1312 *
1313 * Either the key must grant the caller Setattr permission or else the caller
1314 * must hold an instantiation authorisation token for the key.
1315 *
1316 * The timeout is either 0 to clear the timeout, or a number of seconds from
1317 * the current time.  The key and any links to the key will be automatically
1318 * garbage collected after the timeout expires.
1319 *
1320 * Keys with KEY_FLAG_KEEP set should not be timed out.
1321 *
1322 * If successful, 0 is returned.
1323 */
1324long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1325{
 
1326	struct key *key, *instkey;
1327	key_ref_t key_ref;
 
1328	long ret;
1329
1330	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1331				  KEY_NEED_SETATTR);
1332	if (IS_ERR(key_ref)) {
1333		/* setting the timeout on a key under construction is permitted
1334		 * if we have the authorisation token handy */
1335		if (PTR_ERR(key_ref) == -EACCES) {
1336			instkey = key_get_instantiation_authkey(id);
1337			if (!IS_ERR(instkey)) {
1338				key_put(instkey);
1339				key_ref = lookup_user_key(id,
1340							  KEY_LOOKUP_PARTIAL,
1341							  0);
1342				if (!IS_ERR(key_ref))
1343					goto okay;
1344			}
1345		}
1346
1347		ret = PTR_ERR(key_ref);
1348		goto error;
1349	}
1350
1351okay:
1352	key = key_ref_to_ptr(key_ref);
1353	ret = 0;
1354	if (test_bit(KEY_FLAG_KEEP, &key->flags))
1355		ret = -EPERM;
1356	else
1357		key_set_timeout(key, timeout);
 
 
 
 
 
 
 
 
 
1358	key_put(key);
1359
 
1360error:
1361	return ret;
1362}
1363
1364/*
1365 * Assume (or clear) the authority to instantiate the specified key.
1366 *
1367 * This sets the authoritative token currently in force for key instantiation.
1368 * This must be done for a key to be instantiated.  It has the effect of making
1369 * available all the keys from the caller of the request_key() that created a
1370 * key to request_key() calls made by the caller of this function.
1371 *
1372 * The caller must have the instantiation key in their process keyrings with a
1373 * Search permission grant available to the caller.
1374 *
1375 * If the ID given is 0, then the setting will be cleared and 0 returned.
1376 *
1377 * If the ID given has a matching an authorisation key, then that key will be
1378 * set and its ID will be returned.  The authorisation key can be read to get
1379 * the callout information passed to request_key().
1380 */
1381long keyctl_assume_authority(key_serial_t id)
1382{
1383	struct key *authkey;
1384	long ret;
1385
1386	/* special key IDs aren't permitted */
1387	ret = -EINVAL;
1388	if (id < 0)
1389		goto error;
1390
1391	/* we divest ourselves of authority if given an ID of 0 */
1392	if (id == 0) {
1393		ret = keyctl_change_reqkey_auth(NULL);
1394		goto error;
1395	}
1396
1397	/* attempt to assume the authority temporarily granted to us whilst we
1398	 * instantiate the specified key
1399	 * - the authorisation key must be in the current task's keyrings
1400	 *   somewhere
1401	 */
1402	authkey = key_get_instantiation_authkey(id);
1403	if (IS_ERR(authkey)) {
1404		ret = PTR_ERR(authkey);
1405		goto error;
1406	}
1407
1408	ret = keyctl_change_reqkey_auth(authkey);
1409	if (ret < 0)
1410		goto error;
1411	key_put(authkey);
1412
1413	ret = authkey->serial;
1414error:
1415	return ret;
1416}
1417
1418/*
1419 * Get a key's the LSM security label.
1420 *
1421 * The key must grant the caller View permission for this to work.
1422 *
1423 * If there's a buffer, then up to buflen bytes of data will be placed into it.
1424 *
1425 * If successful, the amount of information available will be returned,
1426 * irrespective of how much was copied (including the terminal NUL).
1427 */
1428long keyctl_get_security(key_serial_t keyid,
1429			 char __user *buffer,
1430			 size_t buflen)
1431{
1432	struct key *key, *instkey;
1433	key_ref_t key_ref;
1434	char *context;
1435	long ret;
1436
1437	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1438	if (IS_ERR(key_ref)) {
1439		if (PTR_ERR(key_ref) != -EACCES)
1440			return PTR_ERR(key_ref);
1441
1442		/* viewing a key under construction is also permitted if we
1443		 * have the authorisation token handy */
1444		instkey = key_get_instantiation_authkey(keyid);
1445		if (IS_ERR(instkey))
1446			return PTR_ERR(instkey);
1447		key_put(instkey);
1448
1449		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, 0);
1450		if (IS_ERR(key_ref))
1451			return PTR_ERR(key_ref);
1452	}
1453
1454	key = key_ref_to_ptr(key_ref);
1455	ret = security_key_getsecurity(key, &context);
1456	if (ret == 0) {
1457		/* if no information was returned, give userspace an empty
1458		 * string */
1459		ret = 1;
1460		if (buffer && buflen > 0 &&
1461		    copy_to_user(buffer, "", 1) != 0)
1462			ret = -EFAULT;
1463	} else if (ret > 0) {
1464		/* return as much data as there's room for */
1465		if (buffer && buflen > 0) {
1466			if (buflen > ret)
1467				buflen = ret;
1468
1469			if (copy_to_user(buffer, context, buflen) != 0)
1470				ret = -EFAULT;
1471		}
1472
1473		kfree(context);
1474	}
1475
1476	key_ref_put(key_ref);
1477	return ret;
1478}
1479
1480/*
1481 * Attempt to install the calling process's session keyring on the process's
1482 * parent process.
1483 *
1484 * The keyring must exist and must grant the caller LINK permission, and the
1485 * parent process must be single-threaded and must have the same effective
1486 * ownership as this process and mustn't be SUID/SGID.
1487 *
1488 * The keyring will be emplaced on the parent when it next resumes userspace.
1489 *
1490 * If successful, 0 will be returned.
1491 */
1492long keyctl_session_to_parent(void)
1493{
 
1494	struct task_struct *me, *parent;
1495	const struct cred *mycred, *pcred;
1496	struct callback_head *newwork, *oldwork;
1497	key_ref_t keyring_r;
1498	struct cred *cred;
1499	int ret;
1500
1501	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1502	if (IS_ERR(keyring_r))
1503		return PTR_ERR(keyring_r);
1504
1505	ret = -ENOMEM;
1506
1507	/* our parent is going to need a new cred struct, a new tgcred struct
1508	 * and new security data, so we allocate them here to prevent ENOMEM in
1509	 * our parent */
 
1510	cred = cred_alloc_blank();
1511	if (!cred)
1512		goto error_keyring;
1513	newwork = &cred->rcu;
1514
1515	cred->session_keyring = key_ref_to_ptr(keyring_r);
1516	keyring_r = NULL;
1517	init_task_work(newwork, key_change_session_keyring);
1518
1519	me = current;
1520	rcu_read_lock();
1521	write_lock_irq(&tasklist_lock);
1522
1523	ret = -EPERM;
1524	oldwork = NULL;
1525	parent = me->real_parent;
 
1526
1527	/* the parent mustn't be init and mustn't be a kernel thread */
1528	if (parent->pid <= 1 || !parent->mm)
1529		goto unlock;
1530
1531	/* the parent must be single threaded */
1532	if (!thread_group_empty(parent))
1533		goto unlock;
1534
1535	/* the parent and the child must have different session keyrings or
1536	 * there's no point */
1537	mycred = current_cred();
1538	pcred = __task_cred(parent);
1539	if (mycred == pcred ||
1540	    mycred->session_keyring == pcred->session_keyring) {
1541		ret = 0;
1542		goto unlock;
1543	}
1544
1545	/* the parent must have the same effective ownership and mustn't be
1546	 * SUID/SGID */
1547	if (!uid_eq(pcred->uid,	 mycred->euid) ||
1548	    !uid_eq(pcred->euid, mycred->euid) ||
1549	    !uid_eq(pcred->suid, mycred->euid) ||
1550	    !gid_eq(pcred->gid,	 mycred->egid) ||
1551	    !gid_eq(pcred->egid, mycred->egid) ||
1552	    !gid_eq(pcred->sgid, mycred->egid))
1553		goto unlock;
1554
1555	/* the keyrings must have the same UID */
1556	if ((pcred->session_keyring &&
1557	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1558	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
1559		goto unlock;
1560
1561	/* cancel an already pending keyring replacement */
1562	oldwork = task_work_cancel(parent, key_change_session_keyring);
 
1563
1564	/* the replacement session keyring is applied just prior to userspace
1565	 * restarting */
1566	ret = task_work_add(parent, newwork, true);
1567	if (!ret)
1568		newwork = NULL;
1569unlock:
 
 
 
 
 
 
 
 
 
1570	write_unlock_irq(&tasklist_lock);
1571	rcu_read_unlock();
1572	if (oldwork)
1573		put_cred(container_of(oldwork, struct cred, rcu));
1574	if (newwork)
1575		put_cred(cred);
1576	return ret;
1577
1578error_keyring:
1579	key_ref_put(keyring_r);
1580	return ret;
 
 
 
 
 
 
 
 
 
1581}
1582
1583/*
1584 * The key control system call
1585 */
1586SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1587		unsigned long, arg4, unsigned long, arg5)
1588{
1589	switch (option) {
1590	case KEYCTL_GET_KEYRING_ID:
1591		return keyctl_get_keyring_ID((key_serial_t) arg2,
1592					     (int) arg3);
1593
1594	case KEYCTL_JOIN_SESSION_KEYRING:
1595		return keyctl_join_session_keyring((const char __user *) arg2);
1596
1597	case KEYCTL_UPDATE:
1598		return keyctl_update_key((key_serial_t) arg2,
1599					 (const void __user *) arg3,
1600					 (size_t) arg4);
1601
1602	case KEYCTL_REVOKE:
1603		return keyctl_revoke_key((key_serial_t) arg2);
1604
1605	case KEYCTL_DESCRIBE:
1606		return keyctl_describe_key((key_serial_t) arg2,
1607					   (char __user *) arg3,
1608					   (unsigned) arg4);
1609
1610	case KEYCTL_CLEAR:
1611		return keyctl_keyring_clear((key_serial_t) arg2);
1612
1613	case KEYCTL_LINK:
1614		return keyctl_keyring_link((key_serial_t) arg2,
1615					   (key_serial_t) arg3);
1616
1617	case KEYCTL_UNLINK:
1618		return keyctl_keyring_unlink((key_serial_t) arg2,
1619					     (key_serial_t) arg3);
1620
1621	case KEYCTL_SEARCH:
1622		return keyctl_keyring_search((key_serial_t) arg2,
1623					     (const char __user *) arg3,
1624					     (const char __user *) arg4,
1625					     (key_serial_t) arg5);
1626
1627	case KEYCTL_READ:
1628		return keyctl_read_key((key_serial_t) arg2,
1629				       (char __user *) arg3,
1630				       (size_t) arg4);
1631
1632	case KEYCTL_CHOWN:
1633		return keyctl_chown_key((key_serial_t) arg2,
1634					(uid_t) arg3,
1635					(gid_t) arg4);
1636
1637	case KEYCTL_SETPERM:
1638		return keyctl_setperm_key((key_serial_t) arg2,
1639					  (key_perm_t) arg3);
1640
1641	case KEYCTL_INSTANTIATE:
1642		return keyctl_instantiate_key((key_serial_t) arg2,
1643					      (const void __user *) arg3,
1644					      (size_t) arg4,
1645					      (key_serial_t) arg5);
1646
1647	case KEYCTL_NEGATE:
1648		return keyctl_negate_key((key_serial_t) arg2,
1649					 (unsigned) arg3,
1650					 (key_serial_t) arg4);
1651
1652	case KEYCTL_SET_REQKEY_KEYRING:
1653		return keyctl_set_reqkey_keyring(arg2);
1654
1655	case KEYCTL_SET_TIMEOUT:
1656		return keyctl_set_timeout((key_serial_t) arg2,
1657					  (unsigned) arg3);
1658
1659	case KEYCTL_ASSUME_AUTHORITY:
1660		return keyctl_assume_authority((key_serial_t) arg2);
1661
1662	case KEYCTL_GET_SECURITY:
1663		return keyctl_get_security((key_serial_t) arg2,
1664					   (char __user *) arg3,
1665					   (size_t) arg4);
1666
1667	case KEYCTL_SESSION_TO_PARENT:
1668		return keyctl_session_to_parent();
1669
1670	case KEYCTL_REJECT:
1671		return keyctl_reject_key((key_serial_t) arg2,
1672					 (unsigned) arg3,
1673					 (unsigned) arg4,
1674					 (key_serial_t) arg5);
1675
1676	case KEYCTL_INSTANTIATE_IOV:
1677		return keyctl_instantiate_key_iov(
1678			(key_serial_t) arg2,
1679			(const struct iovec __user *) arg3,
1680			(unsigned) arg4,
1681			(key_serial_t) arg5);
1682
1683	case KEYCTL_INVALIDATE:
1684		return keyctl_invalidate_key((key_serial_t) arg2);
1685
1686	case KEYCTL_GET_PERSISTENT:
1687		return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1688
1689	default:
1690		return -EOPNOTSUPP;
1691	}
1692}