xref: /linux/security/keys/keyctl.c (revision 3839a7460721b87501134697b7b90c45dcc7825d)
1 // SPDX-License-Identifier: GPL-2.0-or-later
2 /* Userspace key control operations
3  *
4  * Copyright (C) 2004-5 Red Hat, Inc. All Rights Reserved.
5  * Written by David Howells (dhowells@redhat.com)
6  */
7 
8 #include <linux/init.h>
9 #include <linux/sched.h>
10 #include <linux/sched/task.h>
11 #include <linux/slab.h>
12 #include <linux/syscalls.h>
13 #include <linux/key.h>
14 #include <linux/keyctl.h>
15 #include <linux/fs.h>
16 #include <linux/capability.h>
17 #include <linux/cred.h>
18 #include <linux/string.h>
19 #include <linux/err.h>
20 #include <linux/vmalloc.h>
21 #include <linux/security.h>
22 #include <linux/uio.h>
23 #include <linux/uaccess.h>
24 #include <keys/request_key_auth-type.h>
25 #include "internal.h"
26 
27 #define KEY_MAX_DESC_SIZE 4096
28 
29 static const unsigned char keyrings_capabilities[2] = {
30 	[0] = (KEYCTL_CAPS0_CAPABILITIES |
31 	       (IS_ENABLED(CONFIG_PERSISTENT_KEYRINGS)	? KEYCTL_CAPS0_PERSISTENT_KEYRINGS : 0) |
32 	       (IS_ENABLED(CONFIG_KEY_DH_OPERATIONS)	? KEYCTL_CAPS0_DIFFIE_HELLMAN : 0) |
33 	       (IS_ENABLED(CONFIG_ASYMMETRIC_KEY_TYPE)	? KEYCTL_CAPS0_PUBLIC_KEY : 0) |
34 	       (IS_ENABLED(CONFIG_BIG_KEYS)		? KEYCTL_CAPS0_BIG_KEY : 0) |
35 	       KEYCTL_CAPS0_INVALIDATE |
36 	       KEYCTL_CAPS0_RESTRICT_KEYRING |
37 	       KEYCTL_CAPS0_MOVE
38 	       ),
39 	[1] = (KEYCTL_CAPS1_NS_KEYRING_NAME |
40 	       KEYCTL_CAPS1_NS_KEY_TAG |
41 	       (IS_ENABLED(CONFIG_KEY_NOTIFICATIONS)	? KEYCTL_CAPS1_NOTIFICATIONS : 0)
42 	       ),
43 };
44 
45 static int key_get_type_from_user(char *type,
46 				  const char __user *_type,
47 				  unsigned len)
48 {
49 	int ret;
50 
51 	ret = strncpy_from_user(type, _type, len);
52 	if (ret < 0)
53 		return ret;
54 	if (ret == 0 || ret >= len)
55 		return -EINVAL;
56 	if (type[0] == '.')
57 		return -EPERM;
58 	type[len - 1] = '\0';
59 	return 0;
60 }
61 
62 /*
63  * Extract the description of a new key from userspace and either add it as a
64  * new key to the specified keyring or update a matching key in that keyring.
65  *
66  * If the description is NULL or an empty string, the key type is asked to
67  * generate one from the payload.
68  *
69  * The keyring must be writable so that we can attach the key to it.
70  *
71  * If successful, the new key's serial number is returned, otherwise an error
72  * code is returned.
73  */
74 SYSCALL_DEFINE5(add_key, const char __user *, _type,
75 		const char __user *, _description,
76 		const void __user *, _payload,
77 		size_t, plen,
78 		key_serial_t, ringid)
79 {
80 	key_ref_t keyring_ref, key_ref;
81 	char type[32], *description;
82 	void *payload;
83 	long ret;
84 
85 	ret = -EINVAL;
86 	if (plen > 1024 * 1024 - 1)
87 		goto error;
88 
89 	/* draw all the data into kernel space */
90 	ret = key_get_type_from_user(type, _type, sizeof(type));
91 	if (ret < 0)
92 		goto error;
93 
94 	description = NULL;
95 	if (_description) {
96 		description = strndup_user(_description, KEY_MAX_DESC_SIZE);
97 		if (IS_ERR(description)) {
98 			ret = PTR_ERR(description);
99 			goto error;
100 		}
101 		if (!*description) {
102 			kfree(description);
103 			description = NULL;
104 		} else if ((description[0] == '.') &&
105 			   (strncmp(type, "keyring", 7) == 0)) {
106 			ret = -EPERM;
107 			goto error2;
108 		}
109 	}
110 
111 	/* pull the payload in if one was supplied */
112 	payload = NULL;
113 
114 	if (plen) {
115 		ret = -ENOMEM;
116 		payload = kvmalloc(plen, GFP_KERNEL);
117 		if (!payload)
118 			goto error2;
119 
120 		ret = -EFAULT;
121 		if (copy_from_user(payload, _payload, plen) != 0)
122 			goto error3;
123 	}
124 
125 	/* find the target keyring (which must be writable) */
126 	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
127 	if (IS_ERR(keyring_ref)) {
128 		ret = PTR_ERR(keyring_ref);
129 		goto error3;
130 	}
131 
132 	/* create or update the requested key and add it to the target
133 	 * keyring */
134 	key_ref = key_create_or_update(keyring_ref, type, description,
135 				       payload, plen, KEY_PERM_UNDEF,
136 				       KEY_ALLOC_IN_QUOTA);
137 	if (!IS_ERR(key_ref)) {
138 		ret = key_ref_to_ptr(key_ref)->serial;
139 		key_ref_put(key_ref);
140 	}
141 	else {
142 		ret = PTR_ERR(key_ref);
143 	}
144 
145 	key_ref_put(keyring_ref);
146  error3:
147 	kvfree_sensitive(payload, plen);
148  error2:
149 	kfree(description);
150  error:
151 	return ret;
152 }
153 
154 /*
155  * Search the process keyrings and keyring trees linked from those for a
156  * matching key.  Keyrings must have appropriate Search permission to be
157  * searched.
158  *
159  * If a key is found, it will be attached to the destination keyring if there's
160  * one specified and the serial number of the key will be returned.
161  *
162  * If no key is found, /sbin/request-key will be invoked if _callout_info is
163  * non-NULL in an attempt to create a key.  The _callout_info string will be
164  * passed to /sbin/request-key to aid with completing the request.  If the
165  * _callout_info string is "" then it will be changed to "-".
166  */
167 SYSCALL_DEFINE4(request_key, const char __user *, _type,
168 		const char __user *, _description,
169 		const char __user *, _callout_info,
170 		key_serial_t, destringid)
171 {
172 	struct key_type *ktype;
173 	struct key *key;
174 	key_ref_t dest_ref;
175 	size_t callout_len;
176 	char type[32], *description, *callout_info;
177 	long ret;
178 
179 	/* pull the type into kernel space */
180 	ret = key_get_type_from_user(type, _type, sizeof(type));
181 	if (ret < 0)
182 		goto error;
183 
184 	/* pull the description into kernel space */
185 	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
186 	if (IS_ERR(description)) {
187 		ret = PTR_ERR(description);
188 		goto error;
189 	}
190 
191 	/* pull the callout info into kernel space */
192 	callout_info = NULL;
193 	callout_len = 0;
194 	if (_callout_info) {
195 		callout_info = strndup_user(_callout_info, PAGE_SIZE);
196 		if (IS_ERR(callout_info)) {
197 			ret = PTR_ERR(callout_info);
198 			goto error2;
199 		}
200 		callout_len = strlen(callout_info);
201 	}
202 
203 	/* get the destination keyring if specified */
204 	dest_ref = NULL;
205 	if (destringid) {
206 		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
207 					   KEY_NEED_WRITE);
208 		if (IS_ERR(dest_ref)) {
209 			ret = PTR_ERR(dest_ref);
210 			goto error3;
211 		}
212 	}
213 
214 	/* find the key type */
215 	ktype = key_type_lookup(type);
216 	if (IS_ERR(ktype)) {
217 		ret = PTR_ERR(ktype);
218 		goto error4;
219 	}
220 
221 	/* do the search */
222 	key = request_key_and_link(ktype, description, NULL, callout_info,
223 				   callout_len, NULL, key_ref_to_ptr(dest_ref),
224 				   KEY_ALLOC_IN_QUOTA);
225 	if (IS_ERR(key)) {
226 		ret = PTR_ERR(key);
227 		goto error5;
228 	}
229 
230 	/* wait for the key to finish being constructed */
231 	ret = wait_for_key_construction(key, 1);
232 	if (ret < 0)
233 		goto error6;
234 
235 	ret = key->serial;
236 
237 error6:
238  	key_put(key);
239 error5:
240 	key_type_put(ktype);
241 error4:
242 	key_ref_put(dest_ref);
243 error3:
244 	kfree(callout_info);
245 error2:
246 	kfree(description);
247 error:
248 	return ret;
249 }
250 
251 /*
252  * Get the ID of the specified process keyring.
253  *
254  * The requested keyring must have search permission to be found.
255  *
256  * If successful, the ID of the requested keyring will be returned.
257  */
258 long keyctl_get_keyring_ID(key_serial_t id, int create)
259 {
260 	key_ref_t key_ref;
261 	unsigned long lflags;
262 	long ret;
263 
264 	lflags = create ? KEY_LOOKUP_CREATE : 0;
265 	key_ref = lookup_user_key(id, lflags, KEY_NEED_SEARCH);
266 	if (IS_ERR(key_ref)) {
267 		ret = PTR_ERR(key_ref);
268 		goto error;
269 	}
270 
271 	ret = key_ref_to_ptr(key_ref)->serial;
272 	key_ref_put(key_ref);
273 error:
274 	return ret;
275 }
276 
277 /*
278  * Join a (named) session keyring.
279  *
280  * Create and join an anonymous session keyring or join a named session
281  * keyring, creating it if necessary.  A named session keyring must have Search
282  * permission for it to be joined.  Session keyrings without this permit will
283  * be skipped over.  It is not permitted for userspace to create or join
284  * keyrings whose name begin with a dot.
285  *
286  * If successful, the ID of the joined session keyring will be returned.
287  */
288 long keyctl_join_session_keyring(const char __user *_name)
289 {
290 	char *name;
291 	long ret;
292 
293 	/* fetch the name from userspace */
294 	name = NULL;
295 	if (_name) {
296 		name = strndup_user(_name, KEY_MAX_DESC_SIZE);
297 		if (IS_ERR(name)) {
298 			ret = PTR_ERR(name);
299 			goto error;
300 		}
301 
302 		ret = -EPERM;
303 		if (name[0] == '.')
304 			goto error_name;
305 	}
306 
307 	/* join the session */
308 	ret = join_session_keyring(name);
309 error_name:
310 	kfree(name);
311 error:
312 	return ret;
313 }
314 
315 /*
316  * Update a key's data payload from the given data.
317  *
318  * The key must grant the caller Write permission and the key type must support
319  * updating for this to work.  A negative key can be positively instantiated
320  * with this call.
321  *
322  * If successful, 0 will be returned.  If the key type does not support
323  * updating, then -EOPNOTSUPP will be returned.
324  */
325 long keyctl_update_key(key_serial_t id,
326 		       const void __user *_payload,
327 		       size_t plen)
328 {
329 	key_ref_t key_ref;
330 	void *payload;
331 	long ret;
332 
333 	ret = -EINVAL;
334 	if (plen > PAGE_SIZE)
335 		goto error;
336 
337 	/* pull the payload in if one was supplied */
338 	payload = NULL;
339 	if (plen) {
340 		ret = -ENOMEM;
341 		payload = kvmalloc(plen, GFP_KERNEL);
342 		if (!payload)
343 			goto error;
344 
345 		ret = -EFAULT;
346 		if (copy_from_user(payload, _payload, plen) != 0)
347 			goto error2;
348 	}
349 
350 	/* find the target key (which must be writable) */
351 	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
352 	if (IS_ERR(key_ref)) {
353 		ret = PTR_ERR(key_ref);
354 		goto error2;
355 	}
356 
357 	/* update the key */
358 	ret = key_update(key_ref, payload, plen);
359 
360 	key_ref_put(key_ref);
361 error2:
362 	kvfree_sensitive(payload, plen);
363 error:
364 	return ret;
365 }
366 
367 /*
368  * Revoke a key.
369  *
370  * The key must be grant the caller Write or Setattr permission for this to
371  * work.  The key type should give up its quota claim when revoked.  The key
372  * and any links to the key will be automatically garbage collected after a
373  * certain amount of time (/proc/sys/kernel/keys/gc_delay).
374  *
375  * Keys with KEY_FLAG_KEEP set should not be revoked.
376  *
377  * If successful, 0 is returned.
378  */
379 long keyctl_revoke_key(key_serial_t id)
380 {
381 	key_ref_t key_ref;
382 	struct key *key;
383 	long ret;
384 
385 	key_ref = lookup_user_key(id, 0, KEY_NEED_WRITE);
386 	if (IS_ERR(key_ref)) {
387 		ret = PTR_ERR(key_ref);
388 		if (ret != -EACCES)
389 			goto error;
390 		key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
391 		if (IS_ERR(key_ref)) {
392 			ret = PTR_ERR(key_ref);
393 			goto error;
394 		}
395 	}
396 
397 	key = key_ref_to_ptr(key_ref);
398 	ret = 0;
399 	if (test_bit(KEY_FLAG_KEEP, &key->flags))
400 		ret = -EPERM;
401 	else
402 		key_revoke(key);
403 
404 	key_ref_put(key_ref);
405 error:
406 	return ret;
407 }
408 
409 /*
410  * Invalidate a key.
411  *
412  * The key must be grant the caller Invalidate permission for this to work.
413  * The key and any links to the key will be automatically garbage collected
414  * immediately.
415  *
416  * Keys with KEY_FLAG_KEEP set should not be invalidated.
417  *
418  * If successful, 0 is returned.
419  */
420 long keyctl_invalidate_key(key_serial_t id)
421 {
422 	key_ref_t key_ref;
423 	struct key *key;
424 	long ret;
425 
426 	kenter("%d", id);
427 
428 	key_ref = lookup_user_key(id, 0, KEY_NEED_SEARCH);
429 	if (IS_ERR(key_ref)) {
430 		ret = PTR_ERR(key_ref);
431 
432 		/* Root is permitted to invalidate certain special keys */
433 		if (capable(CAP_SYS_ADMIN)) {
434 			key_ref = lookup_user_key(id, 0, KEY_SYSADMIN_OVERRIDE);
435 			if (IS_ERR(key_ref))
436 				goto error;
437 			if (test_bit(KEY_FLAG_ROOT_CAN_INVAL,
438 				     &key_ref_to_ptr(key_ref)->flags))
439 				goto invalidate;
440 			goto error_put;
441 		}
442 
443 		goto error;
444 	}
445 
446 invalidate:
447 	key = key_ref_to_ptr(key_ref);
448 	ret = 0;
449 	if (test_bit(KEY_FLAG_KEEP, &key->flags))
450 		ret = -EPERM;
451 	else
452 		key_invalidate(key);
453 error_put:
454 	key_ref_put(key_ref);
455 error:
456 	kleave(" = %ld", ret);
457 	return ret;
458 }
459 
460 /*
461  * Clear the specified keyring, creating an empty process keyring if one of the
462  * special keyring IDs is used.
463  *
464  * The keyring must grant the caller Write permission and not have
465  * KEY_FLAG_KEEP set for this to work.  If successful, 0 will be returned.
466  */
467 long keyctl_keyring_clear(key_serial_t ringid)
468 {
469 	key_ref_t keyring_ref;
470 	struct key *keyring;
471 	long ret;
472 
473 	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
474 	if (IS_ERR(keyring_ref)) {
475 		ret = PTR_ERR(keyring_ref);
476 
477 		/* Root is permitted to invalidate certain special keyrings */
478 		if (capable(CAP_SYS_ADMIN)) {
479 			keyring_ref = lookup_user_key(ringid, 0,
480 						      KEY_SYSADMIN_OVERRIDE);
481 			if (IS_ERR(keyring_ref))
482 				goto error;
483 			if (test_bit(KEY_FLAG_ROOT_CAN_CLEAR,
484 				     &key_ref_to_ptr(keyring_ref)->flags))
485 				goto clear;
486 			goto error_put;
487 		}
488 
489 		goto error;
490 	}
491 
492 clear:
493 	keyring = key_ref_to_ptr(keyring_ref);
494 	if (test_bit(KEY_FLAG_KEEP, &keyring->flags))
495 		ret = -EPERM;
496 	else
497 		ret = keyring_clear(keyring);
498 error_put:
499 	key_ref_put(keyring_ref);
500 error:
501 	return ret;
502 }
503 
504 /*
505  * Create a link from a keyring to a key if there's no matching key in the
506  * keyring, otherwise replace the link to the matching key with a link to the
507  * new key.
508  *
509  * The key must grant the caller Link permission and the the keyring must grant
510  * the caller Write permission.  Furthermore, if an additional link is created,
511  * the keyring's quota will be extended.
512  *
513  * If successful, 0 will be returned.
514  */
515 long keyctl_keyring_link(key_serial_t id, key_serial_t ringid)
516 {
517 	key_ref_t keyring_ref, key_ref;
518 	long ret;
519 
520 	keyring_ref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
521 	if (IS_ERR(keyring_ref)) {
522 		ret = PTR_ERR(keyring_ref);
523 		goto error;
524 	}
525 
526 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
527 	if (IS_ERR(key_ref)) {
528 		ret = PTR_ERR(key_ref);
529 		goto error2;
530 	}
531 
532 	ret = key_link(key_ref_to_ptr(keyring_ref), key_ref_to_ptr(key_ref));
533 
534 	key_ref_put(key_ref);
535 error2:
536 	key_ref_put(keyring_ref);
537 error:
538 	return ret;
539 }
540 
541 /*
542  * Unlink a key from a keyring.
543  *
544  * The keyring must grant the caller Write permission for this to work; the key
545  * itself need not grant the caller anything.  If the last link to a key is
546  * removed then that key will be scheduled for destruction.
547  *
548  * Keys or keyrings with KEY_FLAG_KEEP set should not be unlinked.
549  *
550  * If successful, 0 will be returned.
551  */
552 long keyctl_keyring_unlink(key_serial_t id, key_serial_t ringid)
553 {
554 	key_ref_t keyring_ref, key_ref;
555 	struct key *keyring, *key;
556 	long ret;
557 
558 	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_WRITE);
559 	if (IS_ERR(keyring_ref)) {
560 		ret = PTR_ERR(keyring_ref);
561 		goto error;
562 	}
563 
564 	key_ref = lookup_user_key(id, KEY_LOOKUP_PARTIAL, KEY_NEED_UNLINK);
565 	if (IS_ERR(key_ref)) {
566 		ret = PTR_ERR(key_ref);
567 		goto error2;
568 	}
569 
570 	keyring = key_ref_to_ptr(keyring_ref);
571 	key = key_ref_to_ptr(key_ref);
572 	if (test_bit(KEY_FLAG_KEEP, &keyring->flags) &&
573 	    test_bit(KEY_FLAG_KEEP, &key->flags))
574 		ret = -EPERM;
575 	else
576 		ret = key_unlink(keyring, key);
577 
578 	key_ref_put(key_ref);
579 error2:
580 	key_ref_put(keyring_ref);
581 error:
582 	return ret;
583 }
584 
585 /*
586  * Move a link to a key from one keyring to another, displacing any matching
587  * key from the destination keyring.
588  *
589  * The key must grant the caller Link permission and both keyrings must grant
590  * the caller Write permission.  There must also be a link in the from keyring
591  * to the key.  If both keyrings are the same, nothing is done.
592  *
593  * If successful, 0 will be returned.
594  */
595 long keyctl_keyring_move(key_serial_t id, key_serial_t from_ringid,
596 			 key_serial_t to_ringid, unsigned int flags)
597 {
598 	key_ref_t key_ref, from_ref, to_ref;
599 	long ret;
600 
601 	if (flags & ~KEYCTL_MOVE_EXCL)
602 		return -EINVAL;
603 
604 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_LINK);
605 	if (IS_ERR(key_ref))
606 		return PTR_ERR(key_ref);
607 
608 	from_ref = lookup_user_key(from_ringid, 0, KEY_NEED_WRITE);
609 	if (IS_ERR(from_ref)) {
610 		ret = PTR_ERR(from_ref);
611 		goto error2;
612 	}
613 
614 	to_ref = lookup_user_key(to_ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
615 	if (IS_ERR(to_ref)) {
616 		ret = PTR_ERR(to_ref);
617 		goto error3;
618 	}
619 
620 	ret = key_move(key_ref_to_ptr(key_ref), key_ref_to_ptr(from_ref),
621 		       key_ref_to_ptr(to_ref), flags);
622 
623 	key_ref_put(to_ref);
624 error3:
625 	key_ref_put(from_ref);
626 error2:
627 	key_ref_put(key_ref);
628 	return ret;
629 }
630 
631 /*
632  * Return a description of a key to userspace.
633  *
634  * The key must grant the caller View permission for this to work.
635  *
636  * If there's a buffer, we place up to buflen bytes of data into it formatted
637  * in the following way:
638  *
639  *	type;uid;gid;perm;description<NUL>
640  *
641  * If successful, we return the amount of description available, irrespective
642  * of how much we may have copied into the buffer.
643  */
644 long keyctl_describe_key(key_serial_t keyid,
645 			 char __user *buffer,
646 			 size_t buflen)
647 {
648 	struct key *key, *instkey;
649 	key_ref_t key_ref;
650 	char *infobuf;
651 	long ret;
652 	int desclen, infolen;
653 
654 	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
655 	if (IS_ERR(key_ref)) {
656 		/* viewing a key under construction is permitted if we have the
657 		 * authorisation token handy */
658 		if (PTR_ERR(key_ref) == -EACCES) {
659 			instkey = key_get_instantiation_authkey(keyid);
660 			if (!IS_ERR(instkey)) {
661 				key_put(instkey);
662 				key_ref = lookup_user_key(keyid,
663 							  KEY_LOOKUP_PARTIAL,
664 							  KEY_AUTHTOKEN_OVERRIDE);
665 				if (!IS_ERR(key_ref))
666 					goto okay;
667 			}
668 		}
669 
670 		ret = PTR_ERR(key_ref);
671 		goto error;
672 	}
673 
674 okay:
675 	key = key_ref_to_ptr(key_ref);
676 	desclen = strlen(key->description);
677 
678 	/* calculate how much information we're going to return */
679 	ret = -ENOMEM;
680 	infobuf = kasprintf(GFP_KERNEL,
681 			    "%s;%d;%d;%08x;",
682 			    key->type->name,
683 			    from_kuid_munged(current_user_ns(), key->uid),
684 			    from_kgid_munged(current_user_ns(), key->gid),
685 			    key->perm);
686 	if (!infobuf)
687 		goto error2;
688 	infolen = strlen(infobuf);
689 	ret = infolen + desclen + 1;
690 
691 	/* consider returning the data */
692 	if (buffer && buflen >= ret) {
693 		if (copy_to_user(buffer, infobuf, infolen) != 0 ||
694 		    copy_to_user(buffer + infolen, key->description,
695 				 desclen + 1) != 0)
696 			ret = -EFAULT;
697 	}
698 
699 	kfree(infobuf);
700 error2:
701 	key_ref_put(key_ref);
702 error:
703 	return ret;
704 }
705 
706 /*
707  * Search the specified keyring and any keyrings it links to for a matching
708  * key.  Only keyrings that grant the caller Search permission will be searched
709  * (this includes the starting keyring).  Only keys with Search permission can
710  * be found.
711  *
712  * If successful, the found key will be linked to the destination keyring if
713  * supplied and the key has Link permission, and the found key ID will be
714  * returned.
715  */
716 long keyctl_keyring_search(key_serial_t ringid,
717 			   const char __user *_type,
718 			   const char __user *_description,
719 			   key_serial_t destringid)
720 {
721 	struct key_type *ktype;
722 	key_ref_t keyring_ref, key_ref, dest_ref;
723 	char type[32], *description;
724 	long ret;
725 
726 	/* pull the type and description into kernel space */
727 	ret = key_get_type_from_user(type, _type, sizeof(type));
728 	if (ret < 0)
729 		goto error;
730 
731 	description = strndup_user(_description, KEY_MAX_DESC_SIZE);
732 	if (IS_ERR(description)) {
733 		ret = PTR_ERR(description);
734 		goto error;
735 	}
736 
737 	/* get the keyring at which to begin the search */
738 	keyring_ref = lookup_user_key(ringid, 0, KEY_NEED_SEARCH);
739 	if (IS_ERR(keyring_ref)) {
740 		ret = PTR_ERR(keyring_ref);
741 		goto error2;
742 	}
743 
744 	/* get the destination keyring if specified */
745 	dest_ref = NULL;
746 	if (destringid) {
747 		dest_ref = lookup_user_key(destringid, KEY_LOOKUP_CREATE,
748 					   KEY_NEED_WRITE);
749 		if (IS_ERR(dest_ref)) {
750 			ret = PTR_ERR(dest_ref);
751 			goto error3;
752 		}
753 	}
754 
755 	/* find the key type */
756 	ktype = key_type_lookup(type);
757 	if (IS_ERR(ktype)) {
758 		ret = PTR_ERR(ktype);
759 		goto error4;
760 	}
761 
762 	/* do the search */
763 	key_ref = keyring_search(keyring_ref, ktype, description, true);
764 	if (IS_ERR(key_ref)) {
765 		ret = PTR_ERR(key_ref);
766 
767 		/* treat lack or presence of a negative key the same */
768 		if (ret == -EAGAIN)
769 			ret = -ENOKEY;
770 		goto error5;
771 	}
772 
773 	/* link the resulting key to the destination keyring if we can */
774 	if (dest_ref) {
775 		ret = key_permission(key_ref, KEY_NEED_LINK);
776 		if (ret < 0)
777 			goto error6;
778 
779 		ret = key_link(key_ref_to_ptr(dest_ref), key_ref_to_ptr(key_ref));
780 		if (ret < 0)
781 			goto error6;
782 	}
783 
784 	ret = key_ref_to_ptr(key_ref)->serial;
785 
786 error6:
787 	key_ref_put(key_ref);
788 error5:
789 	key_type_put(ktype);
790 error4:
791 	key_ref_put(dest_ref);
792 error3:
793 	key_ref_put(keyring_ref);
794 error2:
795 	kfree(description);
796 error:
797 	return ret;
798 }
799 
800 /*
801  * Call the read method
802  */
803 static long __keyctl_read_key(struct key *key, char *buffer, size_t buflen)
804 {
805 	long ret;
806 
807 	down_read(&key->sem);
808 	ret = key_validate(key);
809 	if (ret == 0)
810 		ret = key->type->read(key, buffer, buflen);
811 	up_read(&key->sem);
812 	return ret;
813 }
814 
815 /*
816  * Read a key's payload.
817  *
818  * The key must either grant the caller Read permission, or it must grant the
819  * caller Search permission when searched for from the process keyrings.
820  *
821  * If successful, we place up to buflen bytes of data into the buffer, if one
822  * is provided, and return the amount of data that is available in the key,
823  * irrespective of how much we copied into the buffer.
824  */
825 long keyctl_read_key(key_serial_t keyid, char __user *buffer, size_t buflen)
826 {
827 	struct key *key;
828 	key_ref_t key_ref;
829 	long ret;
830 	char *key_data = NULL;
831 	size_t key_data_len;
832 
833 	/* find the key first */
834 	key_ref = lookup_user_key(keyid, 0, KEY_DEFER_PERM_CHECK);
835 	if (IS_ERR(key_ref)) {
836 		ret = -ENOKEY;
837 		goto out;
838 	}
839 
840 	key = key_ref_to_ptr(key_ref);
841 
842 	ret = key_read_state(key);
843 	if (ret < 0)
844 		goto key_put_out; /* Negatively instantiated */
845 
846 	/* see if we can read it directly */
847 	ret = key_permission(key_ref, KEY_NEED_READ);
848 	if (ret == 0)
849 		goto can_read_key;
850 	if (ret != -EACCES)
851 		goto key_put_out;
852 
853 	/* we can't; see if it's searchable from this process's keyrings
854 	 * - we automatically take account of the fact that it may be
855 	 *   dangling off an instantiation key
856 	 */
857 	if (!is_key_possessed(key_ref)) {
858 		ret = -EACCES;
859 		goto key_put_out;
860 	}
861 
862 	/* the key is probably readable - now try to read it */
863 can_read_key:
864 	if (!key->type->read) {
865 		ret = -EOPNOTSUPP;
866 		goto key_put_out;
867 	}
868 
869 	if (!buffer || !buflen) {
870 		/* Get the key length from the read method */
871 		ret = __keyctl_read_key(key, NULL, 0);
872 		goto key_put_out;
873 	}
874 
875 	/*
876 	 * Read the data with the semaphore held (since we might sleep)
877 	 * to protect against the key being updated or revoked.
878 	 *
879 	 * Allocating a temporary buffer to hold the keys before
880 	 * transferring them to user buffer to avoid potential
881 	 * deadlock involving page fault and mmap_lock.
882 	 *
883 	 * key_data_len = (buflen <= PAGE_SIZE)
884 	 *		? buflen : actual length of key data
885 	 *
886 	 * This prevents allocating arbitrary large buffer which can
887 	 * be much larger than the actual key length. In the latter case,
888 	 * at least 2 passes of this loop is required.
889 	 */
890 	key_data_len = (buflen <= PAGE_SIZE) ? buflen : 0;
891 	for (;;) {
892 		if (key_data_len) {
893 			key_data = kvmalloc(key_data_len, GFP_KERNEL);
894 			if (!key_data) {
895 				ret = -ENOMEM;
896 				goto key_put_out;
897 			}
898 		}
899 
900 		ret = __keyctl_read_key(key, key_data, key_data_len);
901 
902 		/*
903 		 * Read methods will just return the required length without
904 		 * any copying if the provided length isn't large enough.
905 		 */
906 		if (ret <= 0 || ret > buflen)
907 			break;
908 
909 		/*
910 		 * The key may change (unlikely) in between 2 consecutive
911 		 * __keyctl_read_key() calls. In this case, we reallocate
912 		 * a larger buffer and redo the key read when
913 		 * key_data_len < ret <= buflen.
914 		 */
915 		if (ret > key_data_len) {
916 			if (unlikely(key_data))
917 				kvfree_sensitive(key_data, key_data_len);
918 			key_data_len = ret;
919 			continue;	/* Allocate buffer */
920 		}
921 
922 		if (copy_to_user(buffer, key_data, ret))
923 			ret = -EFAULT;
924 		break;
925 	}
926 	kvfree_sensitive(key_data, key_data_len);
927 
928 key_put_out:
929 	key_put(key);
930 out:
931 	return ret;
932 }
933 
934 /*
935  * Change the ownership of a key
936  *
937  * The key must grant the caller Setattr permission for this to work, though
938  * the key need not be fully instantiated yet.  For the UID to be changed, or
939  * for the GID to be changed to a group the caller is not a member of, the
940  * caller must have sysadmin capability.  If either uid or gid is -1 then that
941  * attribute is not changed.
942  *
943  * If the UID is to be changed, the new user must have sufficient quota to
944  * accept the key.  The quota deduction will be removed from the old user to
945  * the new user should the attribute be changed.
946  *
947  * If successful, 0 will be returned.
948  */
949 long keyctl_chown_key(key_serial_t id, uid_t user, gid_t group)
950 {
951 	struct key_user *newowner, *zapowner = NULL;
952 	struct key *key;
953 	key_ref_t key_ref;
954 	long ret;
955 	kuid_t uid;
956 	kgid_t gid;
957 
958 	uid = make_kuid(current_user_ns(), user);
959 	gid = make_kgid(current_user_ns(), group);
960 	ret = -EINVAL;
961 	if ((user != (uid_t) -1) && !uid_valid(uid))
962 		goto error;
963 	if ((group != (gid_t) -1) && !gid_valid(gid))
964 		goto error;
965 
966 	ret = 0;
967 	if (user == (uid_t) -1 && group == (gid_t) -1)
968 		goto error;
969 
970 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
971 				  KEY_NEED_SETATTR);
972 	if (IS_ERR(key_ref)) {
973 		ret = PTR_ERR(key_ref);
974 		goto error;
975 	}
976 
977 	key = key_ref_to_ptr(key_ref);
978 
979 	/* make the changes with the locks held to prevent chown/chown races */
980 	ret = -EACCES;
981 	down_write(&key->sem);
982 
983 	if (!capable(CAP_SYS_ADMIN)) {
984 		/* only the sysadmin can chown a key to some other UID */
985 		if (user != (uid_t) -1 && !uid_eq(key->uid, uid))
986 			goto error_put;
987 
988 		/* only the sysadmin can set the key's GID to a group other
989 		 * than one of those that the current process subscribes to */
990 		if (group != (gid_t) -1 && !gid_eq(gid, key->gid) && !in_group_p(gid))
991 			goto error_put;
992 	}
993 
994 	/* change the UID */
995 	if (user != (uid_t) -1 && !uid_eq(uid, key->uid)) {
996 		ret = -ENOMEM;
997 		newowner = key_user_lookup(uid);
998 		if (!newowner)
999 			goto error_put;
1000 
1001 		/* transfer the quota burden to the new user */
1002 		if (test_bit(KEY_FLAG_IN_QUOTA, &key->flags)) {
1003 			unsigned maxkeys = uid_eq(uid, GLOBAL_ROOT_UID) ?
1004 				key_quota_root_maxkeys : key_quota_maxkeys;
1005 			unsigned maxbytes = uid_eq(uid, GLOBAL_ROOT_UID) ?
1006 				key_quota_root_maxbytes : key_quota_maxbytes;
1007 
1008 			spin_lock(&newowner->lock);
1009 			if (newowner->qnkeys + 1 > maxkeys ||
1010 			    newowner->qnbytes + key->quotalen > maxbytes ||
1011 			    newowner->qnbytes + key->quotalen <
1012 			    newowner->qnbytes)
1013 				goto quota_overrun;
1014 
1015 			newowner->qnkeys++;
1016 			newowner->qnbytes += key->quotalen;
1017 			spin_unlock(&newowner->lock);
1018 
1019 			spin_lock(&key->user->lock);
1020 			key->user->qnkeys--;
1021 			key->user->qnbytes -= key->quotalen;
1022 			spin_unlock(&key->user->lock);
1023 		}
1024 
1025 		atomic_dec(&key->user->nkeys);
1026 		atomic_inc(&newowner->nkeys);
1027 
1028 		if (key->state != KEY_IS_UNINSTANTIATED) {
1029 			atomic_dec(&key->user->nikeys);
1030 			atomic_inc(&newowner->nikeys);
1031 		}
1032 
1033 		zapowner = key->user;
1034 		key->user = newowner;
1035 		key->uid = uid;
1036 	}
1037 
1038 	/* change the GID */
1039 	if (group != (gid_t) -1)
1040 		key->gid = gid;
1041 
1042 	notify_key(key, NOTIFY_KEY_SETATTR, 0);
1043 	ret = 0;
1044 
1045 error_put:
1046 	up_write(&key->sem);
1047 	key_put(key);
1048 	if (zapowner)
1049 		key_user_put(zapowner);
1050 error:
1051 	return ret;
1052 
1053 quota_overrun:
1054 	spin_unlock(&newowner->lock);
1055 	zapowner = newowner;
1056 	ret = -EDQUOT;
1057 	goto error_put;
1058 }
1059 
1060 /*
1061  * Change the permission mask on a key.
1062  *
1063  * The key must grant the caller Setattr permission for this to work, though
1064  * the key need not be fully instantiated yet.  If the caller does not have
1065  * sysadmin capability, it may only change the permission on keys that it owns.
1066  */
1067 long keyctl_setperm_key(key_serial_t id, key_perm_t perm)
1068 {
1069 	struct key *key;
1070 	key_ref_t key_ref;
1071 	long ret;
1072 
1073 	ret = -EINVAL;
1074 	if (perm & ~(KEY_POS_ALL | KEY_USR_ALL | KEY_GRP_ALL | KEY_OTH_ALL))
1075 		goto error;
1076 
1077 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1078 				  KEY_NEED_SETATTR);
1079 	if (IS_ERR(key_ref)) {
1080 		ret = PTR_ERR(key_ref);
1081 		goto error;
1082 	}
1083 
1084 	key = key_ref_to_ptr(key_ref);
1085 
1086 	/* make the changes with the locks held to prevent chown/chmod races */
1087 	ret = -EACCES;
1088 	down_write(&key->sem);
1089 
1090 	/* if we're not the sysadmin, we can only change a key that we own */
1091 	if (capable(CAP_SYS_ADMIN) || uid_eq(key->uid, current_fsuid())) {
1092 		key->perm = perm;
1093 		notify_key(key, NOTIFY_KEY_SETATTR, 0);
1094 		ret = 0;
1095 	}
1096 
1097 	up_write(&key->sem);
1098 	key_put(key);
1099 error:
1100 	return ret;
1101 }
1102 
1103 /*
1104  * Get the destination keyring for instantiation and check that the caller has
1105  * Write permission on it.
1106  */
1107 static long get_instantiation_keyring(key_serial_t ringid,
1108 				      struct request_key_auth *rka,
1109 				      struct key **_dest_keyring)
1110 {
1111 	key_ref_t dkref;
1112 
1113 	*_dest_keyring = NULL;
1114 
1115 	/* just return a NULL pointer if we weren't asked to make a link */
1116 	if (ringid == 0)
1117 		return 0;
1118 
1119 	/* if a specific keyring is nominated by ID, then use that */
1120 	if (ringid > 0) {
1121 		dkref = lookup_user_key(ringid, KEY_LOOKUP_CREATE, KEY_NEED_WRITE);
1122 		if (IS_ERR(dkref))
1123 			return PTR_ERR(dkref);
1124 		*_dest_keyring = key_ref_to_ptr(dkref);
1125 		return 0;
1126 	}
1127 
1128 	if (ringid == KEY_SPEC_REQKEY_AUTH_KEY)
1129 		return -EINVAL;
1130 
1131 	/* otherwise specify the destination keyring recorded in the
1132 	 * authorisation key (any KEY_SPEC_*_KEYRING) */
1133 	if (ringid >= KEY_SPEC_REQUESTOR_KEYRING) {
1134 		*_dest_keyring = key_get(rka->dest_keyring);
1135 		return 0;
1136 	}
1137 
1138 	return -ENOKEY;
1139 }
1140 
1141 /*
1142  * Change the request_key authorisation key on the current process.
1143  */
1144 static int keyctl_change_reqkey_auth(struct key *key)
1145 {
1146 	struct cred *new;
1147 
1148 	new = prepare_creds();
1149 	if (!new)
1150 		return -ENOMEM;
1151 
1152 	key_put(new->request_key_auth);
1153 	new->request_key_auth = key_get(key);
1154 
1155 	return commit_creds(new);
1156 }
1157 
1158 /*
1159  * Instantiate a key with the specified payload and link the key into the
1160  * destination keyring if one is given.
1161  *
1162  * The caller must have the appropriate instantiation permit set for this to
1163  * work (see keyctl_assume_authority).  No other permissions are required.
1164  *
1165  * If successful, 0 will be returned.
1166  */
1167 long keyctl_instantiate_key_common(key_serial_t id,
1168 				   struct iov_iter *from,
1169 				   key_serial_t ringid)
1170 {
1171 	const struct cred *cred = current_cred();
1172 	struct request_key_auth *rka;
1173 	struct key *instkey, *dest_keyring;
1174 	size_t plen = from ? iov_iter_count(from) : 0;
1175 	void *payload;
1176 	long ret;
1177 
1178 	kenter("%d,,%zu,%d", id, plen, ringid);
1179 
1180 	if (!plen)
1181 		from = NULL;
1182 
1183 	ret = -EINVAL;
1184 	if (plen > 1024 * 1024 - 1)
1185 		goto error;
1186 
1187 	/* the appropriate instantiation authorisation key must have been
1188 	 * assumed before calling this */
1189 	ret = -EPERM;
1190 	instkey = cred->request_key_auth;
1191 	if (!instkey)
1192 		goto error;
1193 
1194 	rka = instkey->payload.data[0];
1195 	if (rka->target_key->serial != id)
1196 		goto error;
1197 
1198 	/* pull the payload in if one was supplied */
1199 	payload = NULL;
1200 
1201 	if (from) {
1202 		ret = -ENOMEM;
1203 		payload = kvmalloc(plen, GFP_KERNEL);
1204 		if (!payload)
1205 			goto error;
1206 
1207 		ret = -EFAULT;
1208 		if (!copy_from_iter_full(payload, plen, from))
1209 			goto error2;
1210 	}
1211 
1212 	/* find the destination keyring amongst those belonging to the
1213 	 * requesting task */
1214 	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1215 	if (ret < 0)
1216 		goto error2;
1217 
1218 	/* instantiate the key and link it into a keyring */
1219 	ret = key_instantiate_and_link(rka->target_key, payload, plen,
1220 				       dest_keyring, instkey);
1221 
1222 	key_put(dest_keyring);
1223 
1224 	/* discard the assumed authority if it's just been disabled by
1225 	 * instantiation of the key */
1226 	if (ret == 0)
1227 		keyctl_change_reqkey_auth(NULL);
1228 
1229 error2:
1230 	kvfree_sensitive(payload, plen);
1231 error:
1232 	return ret;
1233 }
1234 
1235 /*
1236  * Instantiate a key with the specified payload and link the key into the
1237  * destination keyring if one is given.
1238  *
1239  * The caller must have the appropriate instantiation permit set for this to
1240  * work (see keyctl_assume_authority).  No other permissions are required.
1241  *
1242  * If successful, 0 will be returned.
1243  */
1244 long keyctl_instantiate_key(key_serial_t id,
1245 			    const void __user *_payload,
1246 			    size_t plen,
1247 			    key_serial_t ringid)
1248 {
1249 	if (_payload && plen) {
1250 		struct iovec iov;
1251 		struct iov_iter from;
1252 		int ret;
1253 
1254 		ret = import_single_range(WRITE, (void __user *)_payload, plen,
1255 					  &iov, &from);
1256 		if (unlikely(ret))
1257 			return ret;
1258 
1259 		return keyctl_instantiate_key_common(id, &from, ringid);
1260 	}
1261 
1262 	return keyctl_instantiate_key_common(id, NULL, ringid);
1263 }
1264 
1265 /*
1266  * Instantiate a key with the specified multipart payload and link the key into
1267  * the destination keyring if one is given.
1268  *
1269  * The caller must have the appropriate instantiation permit set for this to
1270  * work (see keyctl_assume_authority).  No other permissions are required.
1271  *
1272  * If successful, 0 will be returned.
1273  */
1274 long keyctl_instantiate_key_iov(key_serial_t id,
1275 				const struct iovec __user *_payload_iov,
1276 				unsigned ioc,
1277 				key_serial_t ringid)
1278 {
1279 	struct iovec iovstack[UIO_FASTIOV], *iov = iovstack;
1280 	struct iov_iter from;
1281 	long ret;
1282 
1283 	if (!_payload_iov)
1284 		ioc = 0;
1285 
1286 	ret = import_iovec(WRITE, _payload_iov, ioc,
1287 				    ARRAY_SIZE(iovstack), &iov, &from);
1288 	if (ret < 0)
1289 		return ret;
1290 	ret = keyctl_instantiate_key_common(id, &from, ringid);
1291 	kfree(iov);
1292 	return ret;
1293 }
1294 
1295 /*
1296  * Negatively instantiate the key with the given timeout (in seconds) and link
1297  * the key into the destination keyring if one is given.
1298  *
1299  * The caller must have the appropriate instantiation permit set for this to
1300  * work (see keyctl_assume_authority).  No other permissions are required.
1301  *
1302  * The key and any links to the key will be automatically garbage collected
1303  * after the timeout expires.
1304  *
1305  * Negative keys are used to rate limit repeated request_key() calls by causing
1306  * them to return -ENOKEY until the negative key expires.
1307  *
1308  * If successful, 0 will be returned.
1309  */
1310 long keyctl_negate_key(key_serial_t id, unsigned timeout, key_serial_t ringid)
1311 {
1312 	return keyctl_reject_key(id, timeout, ENOKEY, ringid);
1313 }
1314 
1315 /*
1316  * Negatively instantiate the key with the given timeout (in seconds) and error
1317  * code and link the key into the destination keyring if one is given.
1318  *
1319  * The caller must have the appropriate instantiation permit set for this to
1320  * work (see keyctl_assume_authority).  No other permissions are required.
1321  *
1322  * The key and any links to the key will be automatically garbage collected
1323  * after the timeout expires.
1324  *
1325  * Negative keys are used to rate limit repeated request_key() calls by causing
1326  * them to return the specified error code until the negative key expires.
1327  *
1328  * If successful, 0 will be returned.
1329  */
1330 long keyctl_reject_key(key_serial_t id, unsigned timeout, unsigned error,
1331 		       key_serial_t ringid)
1332 {
1333 	const struct cred *cred = current_cred();
1334 	struct request_key_auth *rka;
1335 	struct key *instkey, *dest_keyring;
1336 	long ret;
1337 
1338 	kenter("%d,%u,%u,%d", id, timeout, error, ringid);
1339 
1340 	/* must be a valid error code and mustn't be a kernel special */
1341 	if (error <= 0 ||
1342 	    error >= MAX_ERRNO ||
1343 	    error == ERESTARTSYS ||
1344 	    error == ERESTARTNOINTR ||
1345 	    error == ERESTARTNOHAND ||
1346 	    error == ERESTART_RESTARTBLOCK)
1347 		return -EINVAL;
1348 
1349 	/* the appropriate instantiation authorisation key must have been
1350 	 * assumed before calling this */
1351 	ret = -EPERM;
1352 	instkey = cred->request_key_auth;
1353 	if (!instkey)
1354 		goto error;
1355 
1356 	rka = instkey->payload.data[0];
1357 	if (rka->target_key->serial != id)
1358 		goto error;
1359 
1360 	/* find the destination keyring if present (which must also be
1361 	 * writable) */
1362 	ret = get_instantiation_keyring(ringid, rka, &dest_keyring);
1363 	if (ret < 0)
1364 		goto error;
1365 
1366 	/* instantiate the key and link it into a keyring */
1367 	ret = key_reject_and_link(rka->target_key, timeout, error,
1368 				  dest_keyring, instkey);
1369 
1370 	key_put(dest_keyring);
1371 
1372 	/* discard the assumed authority if it's just been disabled by
1373 	 * instantiation of the key */
1374 	if (ret == 0)
1375 		keyctl_change_reqkey_auth(NULL);
1376 
1377 error:
1378 	return ret;
1379 }
1380 
1381 /*
1382  * Read or set the default keyring in which request_key() will cache keys and
1383  * return the old setting.
1384  *
1385  * If a thread or process keyring is specified then it will be created if it
1386  * doesn't yet exist.  The old setting will be returned if successful.
1387  */
1388 long keyctl_set_reqkey_keyring(int reqkey_defl)
1389 {
1390 	struct cred *new;
1391 	int ret, old_setting;
1392 
1393 	old_setting = current_cred_xxx(jit_keyring);
1394 
1395 	if (reqkey_defl == KEY_REQKEY_DEFL_NO_CHANGE)
1396 		return old_setting;
1397 
1398 	new = prepare_creds();
1399 	if (!new)
1400 		return -ENOMEM;
1401 
1402 	switch (reqkey_defl) {
1403 	case KEY_REQKEY_DEFL_THREAD_KEYRING:
1404 		ret = install_thread_keyring_to_cred(new);
1405 		if (ret < 0)
1406 			goto error;
1407 		goto set;
1408 
1409 	case KEY_REQKEY_DEFL_PROCESS_KEYRING:
1410 		ret = install_process_keyring_to_cred(new);
1411 		if (ret < 0)
1412 			goto error;
1413 		goto set;
1414 
1415 	case KEY_REQKEY_DEFL_DEFAULT:
1416 	case KEY_REQKEY_DEFL_SESSION_KEYRING:
1417 	case KEY_REQKEY_DEFL_USER_KEYRING:
1418 	case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
1419 	case KEY_REQKEY_DEFL_REQUESTOR_KEYRING:
1420 		goto set;
1421 
1422 	case KEY_REQKEY_DEFL_NO_CHANGE:
1423 	case KEY_REQKEY_DEFL_GROUP_KEYRING:
1424 	default:
1425 		ret = -EINVAL;
1426 		goto error;
1427 	}
1428 
1429 set:
1430 	new->jit_keyring = reqkey_defl;
1431 	commit_creds(new);
1432 	return old_setting;
1433 error:
1434 	abort_creds(new);
1435 	return ret;
1436 }
1437 
1438 /*
1439  * Set or clear the timeout on a key.
1440  *
1441  * Either the key must grant the caller Setattr permission or else the caller
1442  * must hold an instantiation authorisation token for the key.
1443  *
1444  * The timeout is either 0 to clear the timeout, or a number of seconds from
1445  * the current time.  The key and any links to the key will be automatically
1446  * garbage collected after the timeout expires.
1447  *
1448  * Keys with KEY_FLAG_KEEP set should not be timed out.
1449  *
1450  * If successful, 0 is returned.
1451  */
1452 long keyctl_set_timeout(key_serial_t id, unsigned timeout)
1453 {
1454 	struct key *key, *instkey;
1455 	key_ref_t key_ref;
1456 	long ret;
1457 
1458 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE | KEY_LOOKUP_PARTIAL,
1459 				  KEY_NEED_SETATTR);
1460 	if (IS_ERR(key_ref)) {
1461 		/* setting the timeout on a key under construction is permitted
1462 		 * if we have the authorisation token handy */
1463 		if (PTR_ERR(key_ref) == -EACCES) {
1464 			instkey = key_get_instantiation_authkey(id);
1465 			if (!IS_ERR(instkey)) {
1466 				key_put(instkey);
1467 				key_ref = lookup_user_key(id,
1468 							  KEY_LOOKUP_PARTIAL,
1469 							  KEY_AUTHTOKEN_OVERRIDE);
1470 				if (!IS_ERR(key_ref))
1471 					goto okay;
1472 			}
1473 		}
1474 
1475 		ret = PTR_ERR(key_ref);
1476 		goto error;
1477 	}
1478 
1479 okay:
1480 	key = key_ref_to_ptr(key_ref);
1481 	ret = 0;
1482 	if (test_bit(KEY_FLAG_KEEP, &key->flags)) {
1483 		ret = -EPERM;
1484 	} else {
1485 		key_set_timeout(key, timeout);
1486 		notify_key(key, NOTIFY_KEY_SETATTR, 0);
1487 	}
1488 	key_put(key);
1489 
1490 error:
1491 	return ret;
1492 }
1493 
1494 /*
1495  * Assume (or clear) the authority to instantiate the specified key.
1496  *
1497  * This sets the authoritative token currently in force for key instantiation.
1498  * This must be done for a key to be instantiated.  It has the effect of making
1499  * available all the keys from the caller of the request_key() that created a
1500  * key to request_key() calls made by the caller of this function.
1501  *
1502  * The caller must have the instantiation key in their process keyrings with a
1503  * Search permission grant available to the caller.
1504  *
1505  * If the ID given is 0, then the setting will be cleared and 0 returned.
1506  *
1507  * If the ID given has a matching an authorisation key, then that key will be
1508  * set and its ID will be returned.  The authorisation key can be read to get
1509  * the callout information passed to request_key().
1510  */
1511 long keyctl_assume_authority(key_serial_t id)
1512 {
1513 	struct key *authkey;
1514 	long ret;
1515 
1516 	/* special key IDs aren't permitted */
1517 	ret = -EINVAL;
1518 	if (id < 0)
1519 		goto error;
1520 
1521 	/* we divest ourselves of authority if given an ID of 0 */
1522 	if (id == 0) {
1523 		ret = keyctl_change_reqkey_auth(NULL);
1524 		goto error;
1525 	}
1526 
1527 	/* attempt to assume the authority temporarily granted to us whilst we
1528 	 * instantiate the specified key
1529 	 * - the authorisation key must be in the current task's keyrings
1530 	 *   somewhere
1531 	 */
1532 	authkey = key_get_instantiation_authkey(id);
1533 	if (IS_ERR(authkey)) {
1534 		ret = PTR_ERR(authkey);
1535 		goto error;
1536 	}
1537 
1538 	ret = keyctl_change_reqkey_auth(authkey);
1539 	if (ret == 0)
1540 		ret = authkey->serial;
1541 	key_put(authkey);
1542 error:
1543 	return ret;
1544 }
1545 
1546 /*
1547  * Get a key's the LSM security label.
1548  *
1549  * The key must grant the caller View permission for this to work.
1550  *
1551  * If there's a buffer, then up to buflen bytes of data will be placed into it.
1552  *
1553  * If successful, the amount of information available will be returned,
1554  * irrespective of how much was copied (including the terminal NUL).
1555  */
1556 long keyctl_get_security(key_serial_t keyid,
1557 			 char __user *buffer,
1558 			 size_t buflen)
1559 {
1560 	struct key *key, *instkey;
1561 	key_ref_t key_ref;
1562 	char *context;
1563 	long ret;
1564 
1565 	key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL, KEY_NEED_VIEW);
1566 	if (IS_ERR(key_ref)) {
1567 		if (PTR_ERR(key_ref) != -EACCES)
1568 			return PTR_ERR(key_ref);
1569 
1570 		/* viewing a key under construction is also permitted if we
1571 		 * have the authorisation token handy */
1572 		instkey = key_get_instantiation_authkey(keyid);
1573 		if (IS_ERR(instkey))
1574 			return PTR_ERR(instkey);
1575 		key_put(instkey);
1576 
1577 		key_ref = lookup_user_key(keyid, KEY_LOOKUP_PARTIAL,
1578 					  KEY_AUTHTOKEN_OVERRIDE);
1579 		if (IS_ERR(key_ref))
1580 			return PTR_ERR(key_ref);
1581 	}
1582 
1583 	key = key_ref_to_ptr(key_ref);
1584 	ret = security_key_getsecurity(key, &context);
1585 	if (ret == 0) {
1586 		/* if no information was returned, give userspace an empty
1587 		 * string */
1588 		ret = 1;
1589 		if (buffer && buflen > 0 &&
1590 		    copy_to_user(buffer, "", 1) != 0)
1591 			ret = -EFAULT;
1592 	} else if (ret > 0) {
1593 		/* return as much data as there's room for */
1594 		if (buffer && buflen > 0) {
1595 			if (buflen > ret)
1596 				buflen = ret;
1597 
1598 			if (copy_to_user(buffer, context, buflen) != 0)
1599 				ret = -EFAULT;
1600 		}
1601 
1602 		kfree(context);
1603 	}
1604 
1605 	key_ref_put(key_ref);
1606 	return ret;
1607 }
1608 
1609 /*
1610  * Attempt to install the calling process's session keyring on the process's
1611  * parent process.
1612  *
1613  * The keyring must exist and must grant the caller LINK permission, and the
1614  * parent process must be single-threaded and must have the same effective
1615  * ownership as this process and mustn't be SUID/SGID.
1616  *
1617  * The keyring will be emplaced on the parent when it next resumes userspace.
1618  *
1619  * If successful, 0 will be returned.
1620  */
1621 long keyctl_session_to_parent(void)
1622 {
1623 	struct task_struct *me, *parent;
1624 	const struct cred *mycred, *pcred;
1625 	struct callback_head *newwork, *oldwork;
1626 	key_ref_t keyring_r;
1627 	struct cred *cred;
1628 	int ret;
1629 
1630 	keyring_r = lookup_user_key(KEY_SPEC_SESSION_KEYRING, 0, KEY_NEED_LINK);
1631 	if (IS_ERR(keyring_r))
1632 		return PTR_ERR(keyring_r);
1633 
1634 	ret = -ENOMEM;
1635 
1636 	/* our parent is going to need a new cred struct, a new tgcred struct
1637 	 * and new security data, so we allocate them here to prevent ENOMEM in
1638 	 * our parent */
1639 	cred = cred_alloc_blank();
1640 	if (!cred)
1641 		goto error_keyring;
1642 	newwork = &cred->rcu;
1643 
1644 	cred->session_keyring = key_ref_to_ptr(keyring_r);
1645 	keyring_r = NULL;
1646 	init_task_work(newwork, key_change_session_keyring);
1647 
1648 	me = current;
1649 	rcu_read_lock();
1650 	write_lock_irq(&tasklist_lock);
1651 
1652 	ret = -EPERM;
1653 	oldwork = NULL;
1654 	parent = rcu_dereference_protected(me->real_parent,
1655 					   lockdep_is_held(&tasklist_lock));
1656 
1657 	/* the parent mustn't be init and mustn't be a kernel thread */
1658 	if (parent->pid <= 1 || !parent->mm)
1659 		goto unlock;
1660 
1661 	/* the parent must be single threaded */
1662 	if (!thread_group_empty(parent))
1663 		goto unlock;
1664 
1665 	/* the parent and the child must have different session keyrings or
1666 	 * there's no point */
1667 	mycred = current_cred();
1668 	pcred = __task_cred(parent);
1669 	if (mycred == pcred ||
1670 	    mycred->session_keyring == pcred->session_keyring) {
1671 		ret = 0;
1672 		goto unlock;
1673 	}
1674 
1675 	/* the parent must have the same effective ownership and mustn't be
1676 	 * SUID/SGID */
1677 	if (!uid_eq(pcred->uid,	 mycred->euid) ||
1678 	    !uid_eq(pcred->euid, mycred->euid) ||
1679 	    !uid_eq(pcred->suid, mycred->euid) ||
1680 	    !gid_eq(pcred->gid,	 mycred->egid) ||
1681 	    !gid_eq(pcred->egid, mycred->egid) ||
1682 	    !gid_eq(pcred->sgid, mycred->egid))
1683 		goto unlock;
1684 
1685 	/* the keyrings must have the same UID */
1686 	if ((pcred->session_keyring &&
1687 	     !uid_eq(pcred->session_keyring->uid, mycred->euid)) ||
1688 	    !uid_eq(mycred->session_keyring->uid, mycred->euid))
1689 		goto unlock;
1690 
1691 	/* cancel an already pending keyring replacement */
1692 	oldwork = task_work_cancel(parent, key_change_session_keyring);
1693 
1694 	/* the replacement session keyring is applied just prior to userspace
1695 	 * restarting */
1696 	ret = task_work_add(parent, newwork, true);
1697 	if (!ret)
1698 		newwork = NULL;
1699 unlock:
1700 	write_unlock_irq(&tasklist_lock);
1701 	rcu_read_unlock();
1702 	if (oldwork)
1703 		put_cred(container_of(oldwork, struct cred, rcu));
1704 	if (newwork)
1705 		put_cred(cred);
1706 	return ret;
1707 
1708 error_keyring:
1709 	key_ref_put(keyring_r);
1710 	return ret;
1711 }
1712 
1713 /*
1714  * Apply a restriction to a given keyring.
1715  *
1716  * The caller must have Setattr permission to change keyring restrictions.
1717  *
1718  * The requested type name may be a NULL pointer to reject all attempts
1719  * to link to the keyring.  In this case, _restriction must also be NULL.
1720  * Otherwise, both _type and _restriction must be non-NULL.
1721  *
1722  * Returns 0 if successful.
1723  */
1724 long keyctl_restrict_keyring(key_serial_t id, const char __user *_type,
1725 			     const char __user *_restriction)
1726 {
1727 	key_ref_t key_ref;
1728 	char type[32];
1729 	char *restriction = NULL;
1730 	long ret;
1731 
1732 	key_ref = lookup_user_key(id, 0, KEY_NEED_SETATTR);
1733 	if (IS_ERR(key_ref))
1734 		return PTR_ERR(key_ref);
1735 
1736 	ret = -EINVAL;
1737 	if (_type) {
1738 		if (!_restriction)
1739 			goto error;
1740 
1741 		ret = key_get_type_from_user(type, _type, sizeof(type));
1742 		if (ret < 0)
1743 			goto error;
1744 
1745 		restriction = strndup_user(_restriction, PAGE_SIZE);
1746 		if (IS_ERR(restriction)) {
1747 			ret = PTR_ERR(restriction);
1748 			goto error;
1749 		}
1750 	} else {
1751 		if (_restriction)
1752 			goto error;
1753 	}
1754 
1755 	ret = keyring_restrict(key_ref, _type ? type : NULL, restriction);
1756 	kfree(restriction);
1757 error:
1758 	key_ref_put(key_ref);
1759 	return ret;
1760 }
1761 
1762 #ifdef CONFIG_KEY_NOTIFICATIONS
1763 /*
1764  * Watch for changes to a key.
1765  *
1766  * The caller must have View permission to watch a key or keyring.
1767  */
1768 long keyctl_watch_key(key_serial_t id, int watch_queue_fd, int watch_id)
1769 {
1770 	struct watch_queue *wqueue;
1771 	struct watch_list *wlist = NULL;
1772 	struct watch *watch = NULL;
1773 	struct key *key;
1774 	key_ref_t key_ref;
1775 	long ret;
1776 
1777 	if (watch_id < -1 || watch_id > 0xff)
1778 		return -EINVAL;
1779 
1780 	key_ref = lookup_user_key(id, KEY_LOOKUP_CREATE, KEY_NEED_VIEW);
1781 	if (IS_ERR(key_ref))
1782 		return PTR_ERR(key_ref);
1783 	key = key_ref_to_ptr(key_ref);
1784 
1785 	wqueue = get_watch_queue(watch_queue_fd);
1786 	if (IS_ERR(wqueue)) {
1787 		ret = PTR_ERR(wqueue);
1788 		goto err_key;
1789 	}
1790 
1791 	if (watch_id >= 0) {
1792 		ret = -ENOMEM;
1793 		if (!key->watchers) {
1794 			wlist = kzalloc(sizeof(*wlist), GFP_KERNEL);
1795 			if (!wlist)
1796 				goto err_wqueue;
1797 			init_watch_list(wlist, NULL);
1798 		}
1799 
1800 		watch = kzalloc(sizeof(*watch), GFP_KERNEL);
1801 		if (!watch)
1802 			goto err_wlist;
1803 
1804 		init_watch(watch, wqueue);
1805 		watch->id	= key->serial;
1806 		watch->info_id	= (u32)watch_id << WATCH_INFO_ID__SHIFT;
1807 
1808 		ret = security_watch_key(key);
1809 		if (ret < 0)
1810 			goto err_watch;
1811 
1812 		down_write(&key->sem);
1813 		if (!key->watchers) {
1814 			key->watchers = wlist;
1815 			wlist = NULL;
1816 		}
1817 
1818 		ret = add_watch_to_object(watch, key->watchers);
1819 		up_write(&key->sem);
1820 
1821 		if (ret == 0)
1822 			watch = NULL;
1823 	} else {
1824 		ret = -EBADSLT;
1825 		if (key->watchers) {
1826 			down_write(&key->sem);
1827 			ret = remove_watch_from_object(key->watchers,
1828 						       wqueue, key_serial(key),
1829 						       false);
1830 			up_write(&key->sem);
1831 		}
1832 	}
1833 
1834 err_watch:
1835 	kfree(watch);
1836 err_wlist:
1837 	kfree(wlist);
1838 err_wqueue:
1839 	put_watch_queue(wqueue);
1840 err_key:
1841 	key_put(key);
1842 	return ret;
1843 }
1844 #endif /* CONFIG_KEY_NOTIFICATIONS */
1845 
1846 /*
1847  * Get keyrings subsystem capabilities.
1848  */
1849 long keyctl_capabilities(unsigned char __user *_buffer, size_t buflen)
1850 {
1851 	size_t size = buflen;
1852 
1853 	if (size > 0) {
1854 		if (size > sizeof(keyrings_capabilities))
1855 			size = sizeof(keyrings_capabilities);
1856 		if (copy_to_user(_buffer, keyrings_capabilities, size) != 0)
1857 			return -EFAULT;
1858 		if (size < buflen &&
1859 		    clear_user(_buffer + size, buflen - size) != 0)
1860 			return -EFAULT;
1861 	}
1862 
1863 	return sizeof(keyrings_capabilities);
1864 }
1865 
1866 /*
1867  * The key control system call
1868  */
1869 SYSCALL_DEFINE5(keyctl, int, option, unsigned long, arg2, unsigned long, arg3,
1870 		unsigned long, arg4, unsigned long, arg5)
1871 {
1872 	switch (option) {
1873 	case KEYCTL_GET_KEYRING_ID:
1874 		return keyctl_get_keyring_ID((key_serial_t) arg2,
1875 					     (int) arg3);
1876 
1877 	case KEYCTL_JOIN_SESSION_KEYRING:
1878 		return keyctl_join_session_keyring((const char __user *) arg2);
1879 
1880 	case KEYCTL_UPDATE:
1881 		return keyctl_update_key((key_serial_t) arg2,
1882 					 (const void __user *) arg3,
1883 					 (size_t) arg4);
1884 
1885 	case KEYCTL_REVOKE:
1886 		return keyctl_revoke_key((key_serial_t) arg2);
1887 
1888 	case KEYCTL_DESCRIBE:
1889 		return keyctl_describe_key((key_serial_t) arg2,
1890 					   (char __user *) arg3,
1891 					   (unsigned) arg4);
1892 
1893 	case KEYCTL_CLEAR:
1894 		return keyctl_keyring_clear((key_serial_t) arg2);
1895 
1896 	case KEYCTL_LINK:
1897 		return keyctl_keyring_link((key_serial_t) arg2,
1898 					   (key_serial_t) arg3);
1899 
1900 	case KEYCTL_UNLINK:
1901 		return keyctl_keyring_unlink((key_serial_t) arg2,
1902 					     (key_serial_t) arg3);
1903 
1904 	case KEYCTL_SEARCH:
1905 		return keyctl_keyring_search((key_serial_t) arg2,
1906 					     (const char __user *) arg3,
1907 					     (const char __user *) arg4,
1908 					     (key_serial_t) arg5);
1909 
1910 	case KEYCTL_READ:
1911 		return keyctl_read_key((key_serial_t) arg2,
1912 				       (char __user *) arg3,
1913 				       (size_t) arg4);
1914 
1915 	case KEYCTL_CHOWN:
1916 		return keyctl_chown_key((key_serial_t) arg2,
1917 					(uid_t) arg3,
1918 					(gid_t) arg4);
1919 
1920 	case KEYCTL_SETPERM:
1921 		return keyctl_setperm_key((key_serial_t) arg2,
1922 					  (key_perm_t) arg3);
1923 
1924 	case KEYCTL_INSTANTIATE:
1925 		return keyctl_instantiate_key((key_serial_t) arg2,
1926 					      (const void __user *) arg3,
1927 					      (size_t) arg4,
1928 					      (key_serial_t) arg5);
1929 
1930 	case KEYCTL_NEGATE:
1931 		return keyctl_negate_key((key_serial_t) arg2,
1932 					 (unsigned) arg3,
1933 					 (key_serial_t) arg4);
1934 
1935 	case KEYCTL_SET_REQKEY_KEYRING:
1936 		return keyctl_set_reqkey_keyring(arg2);
1937 
1938 	case KEYCTL_SET_TIMEOUT:
1939 		return keyctl_set_timeout((key_serial_t) arg2,
1940 					  (unsigned) arg3);
1941 
1942 	case KEYCTL_ASSUME_AUTHORITY:
1943 		return keyctl_assume_authority((key_serial_t) arg2);
1944 
1945 	case KEYCTL_GET_SECURITY:
1946 		return keyctl_get_security((key_serial_t) arg2,
1947 					   (char __user *) arg3,
1948 					   (size_t) arg4);
1949 
1950 	case KEYCTL_SESSION_TO_PARENT:
1951 		return keyctl_session_to_parent();
1952 
1953 	case KEYCTL_REJECT:
1954 		return keyctl_reject_key((key_serial_t) arg2,
1955 					 (unsigned) arg3,
1956 					 (unsigned) arg4,
1957 					 (key_serial_t) arg5);
1958 
1959 	case KEYCTL_INSTANTIATE_IOV:
1960 		return keyctl_instantiate_key_iov(
1961 			(key_serial_t) arg2,
1962 			(const struct iovec __user *) arg3,
1963 			(unsigned) arg4,
1964 			(key_serial_t) arg5);
1965 
1966 	case KEYCTL_INVALIDATE:
1967 		return keyctl_invalidate_key((key_serial_t) arg2);
1968 
1969 	case KEYCTL_GET_PERSISTENT:
1970 		return keyctl_get_persistent((uid_t)arg2, (key_serial_t)arg3);
1971 
1972 	case KEYCTL_DH_COMPUTE:
1973 		return keyctl_dh_compute((struct keyctl_dh_params __user *) arg2,
1974 					 (char __user *) arg3, (size_t) arg4,
1975 					 (struct keyctl_kdf_params __user *) arg5);
1976 
1977 	case KEYCTL_RESTRICT_KEYRING:
1978 		return keyctl_restrict_keyring((key_serial_t) arg2,
1979 					       (const char __user *) arg3,
1980 					       (const char __user *) arg4);
1981 
1982 	case KEYCTL_PKEY_QUERY:
1983 		if (arg3 != 0)
1984 			return -EINVAL;
1985 		return keyctl_pkey_query((key_serial_t)arg2,
1986 					 (const char __user *)arg4,
1987 					 (struct keyctl_pkey_query __user *)arg5);
1988 
1989 	case KEYCTL_PKEY_ENCRYPT:
1990 	case KEYCTL_PKEY_DECRYPT:
1991 	case KEYCTL_PKEY_SIGN:
1992 		return keyctl_pkey_e_d_s(
1993 			option,
1994 			(const struct keyctl_pkey_params __user *)arg2,
1995 			(const char __user *)arg3,
1996 			(const void __user *)arg4,
1997 			(void __user *)arg5);
1998 
1999 	case KEYCTL_PKEY_VERIFY:
2000 		return keyctl_pkey_verify(
2001 			(const struct keyctl_pkey_params __user *)arg2,
2002 			(const char __user *)arg3,
2003 			(const void __user *)arg4,
2004 			(const void __user *)arg5);
2005 
2006 	case KEYCTL_MOVE:
2007 		return keyctl_keyring_move((key_serial_t)arg2,
2008 					   (key_serial_t)arg3,
2009 					   (key_serial_t)arg4,
2010 					   (unsigned int)arg5);
2011 
2012 	case KEYCTL_CAPABILITIES:
2013 		return keyctl_capabilities((unsigned char __user *)arg2, (size_t)arg3);
2014 
2015 	case KEYCTL_WATCH_KEY:
2016 		return keyctl_watch_key((key_serial_t)arg2, (int)arg3, (int)arg4);
2017 
2018 	default:
2019 		return -EOPNOTSUPP;
2020 	}
2021 }
2022