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2024-02-20 102a0743326a03cd1a1202ceda21e175b7d3575c 
 kernel/security/keys/request_key.c
....@@ -1,30 +1,55 @@
1
+// SPDX-License-Identifier: GPL-2.0-or-later
12 /* Request a key from userspace
23  *
34  * Copyright (C) 2004-2007 Red Hat, Inc. All Rights Reserved.
45  * Written by David Howells (dhowells@redhat.com)
56  *
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
- *
117  * See Documentation/security/keys/request-key.rst
128  */
139 
14
-#include <linux/module.h>
10
+#include <linux/export.h>
1511 #include <linux/sched.h>
1612 #include <linux/kmod.h>
1713 #include <linux/err.h>
1814 #include <linux/keyctl.h>
1915 #include <linux/slab.h>
16
+#include <net/net_namespace.h>
2017 #include "internal.h"
2118 #include <keys/request_key_auth-type.h>
2219 
2320 #define key_negative_timeout	60	/* default timeout on a negative key's existence */
2421 
22
+static struct key *check_cached_key(struct keyring_search_context *ctx)
23
+{
24
+#ifdef CONFIG_KEYS_REQUEST_CACHE
25
+	struct key *key = current->cached_requested_key;
26
+
27
+	if (key &&
28
+	    ctx->match_data.cmp(key, &ctx->match_data) &&
29
+	    !(key->flags & ((1 << KEY_FLAG_INVALIDATED) |
30
+			    (1 << KEY_FLAG_REVOKED))))
31
+		return key_get(key);
32
+#endif
33
+	return NULL;
34
+}
35
+
36
+static void cache_requested_key(struct key *key)
37
+{
38
+#ifdef CONFIG_KEYS_REQUEST_CACHE
39
+	struct task_struct *t = current;
40
+
41
+	/* Do not cache key if it is a kernel thread */
42
+	if (!(t->flags & PF_KTHREAD)) {
43
+		key_put(t->cached_requested_key);
44
+		t->cached_requested_key = key_get(key);
45
+		set_tsk_thread_flag(t, TIF_NOTIFY_RESUME);
46
+	}
47
+#endif
48
+}
49
+
2550 /**
2651  * complete_request_key - Complete the construction of a key.
27
- * @auth_key: The authorisation key.
52
+ * @authkey: The authorisation key.
2853  * @error: The success or failute of the construction.
2954  *
3055  * Complete the attempt to construct a key.  The key will be negated
....@@ -96,7 +121,7 @@
96121 	struct request_key_auth *rka = get_request_key_auth(authkey);
97122 	const struct cred *cred = current_cred();
98123 	key_serial_t prkey, sskey;
99
-	struct key *key = rka->target_key, *keyring, *session;
124
+	struct key *key = rka->target_key, *keyring, *session, *user_session;
100125 	char *argv[9], *envp[3], uid_str[12], gid_str[12];
101126 	char key_str[12], keyring_str[3][12];
102127 	char desc[20];
....@@ -104,9 +129,9 @@
104129 
105130 	kenter("{%d},{%d},%s", key->serial, authkey->serial, rka->op);
106131 
107
-	ret = install_user_keyrings();
132
+	ret = look_up_user_keyrings(NULL, &user_session);
108133 	if (ret < 0)
109
-		goto error_alloc;
134
+		goto error_us;
110135 
111136 	/* allocate a new session keyring */
112137 	sprintf(desc, "_req.%u", key->serial);
....@@ -142,12 +167,10 @@
142167 		prkey = cred->process_keyring->serial;
143168 	sprintf(keyring_str[1], "%d", prkey);
144169 
145
-	rcu_read_lock();
146
-	session = rcu_dereference(cred->session_keyring);
170
+	session = cred->session_keyring;
147171 	if (!session)
148
-		session = cred->user->session_keyring;
172
+		session = user_session;
149173 	sskey = session->serial;
150
-	rcu_read_unlock();
151174 
152175 	sprintf(keyring_str[2], "%d", sskey);
153176 
....@@ -188,6 +211,8 @@
188211 	key_put(keyring);
189212 
190213 error_alloc:
214
+	key_put(user_session);
215
+error_us:
191216 	complete_request_key(authkey, ret);
192217 	kleave(" = %d", ret);
193218 	return ret;
....@@ -224,7 +249,7 @@
224249 	/* check that the actor called complete_request_key() prior to
225250 	 * returning an error */
226251 	WARN_ON(ret < 0 &&
227
-		!test_bit(KEY_FLAG_REVOKED, &authkey->flags));
252
+		!test_bit(KEY_FLAG_INVALIDATED, &authkey->flags));
228253 
229254 	key_put(authkey);
230255 	kleave(" = %d", ret);
....@@ -273,32 +298,36 @@
273298 				}
274299 			}
275300 
301
+			fallthrough;
276302 		case KEY_REQKEY_DEFL_THREAD_KEYRING:
277303 			dest_keyring = key_get(cred->thread_keyring);
278304 			if (dest_keyring)
279305 				break;
280306 
307
+			fallthrough;
281308 		case KEY_REQKEY_DEFL_PROCESS_KEYRING:
282309 			dest_keyring = key_get(cred->process_keyring);
283310 			if (dest_keyring)
284311 				break;
285312 
313
+			fallthrough;
286314 		case KEY_REQKEY_DEFL_SESSION_KEYRING:
287
-			rcu_read_lock();
288
-			dest_keyring = key_get(
289
-				rcu_dereference(cred->session_keyring));
290
-			rcu_read_unlock();
315
+			dest_keyring = key_get(cred->session_keyring);
291316 
292317 			if (dest_keyring)
293318 				break;
294319 
320
+			fallthrough;
295321 		case KEY_REQKEY_DEFL_USER_SESSION_KEYRING:
296
-			dest_keyring =
297
-				key_get(cred->user->session_keyring);
322
+			ret = look_up_user_keyrings(NULL, &dest_keyring);
323
+			if (ret < 0)
324
+				return ret;
298325 			break;
299326 
300327 		case KEY_REQKEY_DEFL_USER_KEYRING:
301
-			dest_keyring = key_get(cred->user->uid_keyring);
328
+			ret = look_up_user_keyrings(&dest_keyring, NULL);
329
+			if (ret < 0)
330
+				return ret;
302331 			break;
303332 
304333 		case KEY_REQKEY_DEFL_GROUP_KEYRING:
....@@ -343,7 +372,7 @@
343372 			       struct key_user *user,
344373 			       struct key **_key)
345374 {
346
-	struct assoc_array_edit *edit;
375
+	struct assoc_array_edit *edit = NULL;
347376 	struct key *key;
348377 	key_perm_t perm;
349378 	key_ref_t key_ref;
....@@ -372,26 +401,39 @@
372401 	set_bit(KEY_FLAG_USER_CONSTRUCT, &key->flags);
373402 
374403 	if (dest_keyring) {
375
-		ret = __key_link_begin(dest_keyring, &ctx->index_key, &edit);
404
+		ret = __key_link_lock(dest_keyring, &key->index_key);
376405 		if (ret < 0)
377
-			goto link_prealloc_failed;
406
+			goto link_lock_failed;
378407 	}
379408 
380
-	/* attach the key to the destination keyring under lock, but we do need
409
+	/*
410
+	 * Attach the key to the destination keyring under lock, but we do need
381411 	 * to do another check just in case someone beat us to it whilst we
382
-	 * waited for locks */
412
+	 * waited for locks.
413
+	 *
414
+	 * The caller might specify a comparison function which looks for keys
415
+	 * that do not exactly match but are still equivalent from the caller's
416
+	 * perspective. The __key_link_begin() operation must be done only after
417
+	 * an actual key is determined.
418
+	 */
383419 	mutex_lock(&key_construction_mutex);
384420 
385
-	key_ref = search_process_keyrings(ctx);
421
+	rcu_read_lock();
422
+	key_ref = search_process_keyrings_rcu(ctx);
423
+	rcu_read_unlock();
386424 	if (!IS_ERR(key_ref))
387425 		goto key_already_present;
388426 
389
-	if (dest_keyring)
390
-		__key_link(key, &edit);
427
+	if (dest_keyring) {
428
+		ret = __key_link_begin(dest_keyring, &key->index_key, &edit);
429
+		if (ret < 0)
430
+			goto link_alloc_failed;
431
+		__key_link(dest_keyring, key, &edit);
432
+	}
391433 
392434 	mutex_unlock(&key_construction_mutex);
393435 	if (dest_keyring)
394
-		__key_link_end(dest_keyring, &ctx->index_key, edit);
436
+		__key_link_end(dest_keyring, &key->index_key, edit);
395437 	mutex_unlock(&user->cons_lock);
396438 	*_key = key;
397439 	kleave(" = 0 [%d]", key_serial(key));
....@@ -404,10 +446,13 @@
404446 	mutex_unlock(&key_construction_mutex);
405447 	key = key_ref_to_ptr(key_ref);
406448 	if (dest_keyring) {
449
+		ret = __key_link_begin(dest_keyring, &key->index_key, &edit);
450
+		if (ret < 0)
451
+			goto link_alloc_failed_unlocked;
407452 		ret = __key_link_check_live_key(dest_keyring, key);
408453 		if (ret == 0)
409
-			__key_link(key, &edit);
410
-		__key_link_end(dest_keyring, &ctx->index_key, edit);
454
+			__key_link(dest_keyring, key, &edit);
455
+		__key_link_end(dest_keyring, &key->index_key, edit);
411456 		if (ret < 0)
412457 			goto link_check_failed;
413458 	}
....@@ -422,7 +467,11 @@
422467 	kleave(" = %d [linkcheck]", ret);
423468 	return ret;
424469 
425
-link_prealloc_failed:
470
+link_alloc_failed:
471
+	mutex_unlock(&key_construction_mutex);
472
+link_alloc_failed_unlocked:
473
+	__key_link_end(dest_keyring, &key->index_key, edit);
474
+link_lock_failed:
426475 	mutex_unlock(&user->cons_lock);
427476 	key_put(key);
428477 	kleave(" = %d [prelink]", ret);
....@@ -497,16 +546,18 @@
497546  * request_key_and_link - Request a key and cache it in a keyring.
498547  * @type: The type of key we want.
499548  * @description: The searchable description of the key.
549
+ * @domain_tag: The domain in which the key operates.
500550  * @callout_info: The data to pass to the instantiation upcall (or NULL).
501551  * @callout_len: The length of callout_info.
502552  * @aux: Auxiliary data for the upcall.
503553  * @dest_keyring: Where to cache the key.
504554  * @flags: Flags to key_alloc().
505555  *
506
- * A key matching the specified criteria is searched for in the process's
507
- * keyrings and returned with its usage count incremented if found.  Otherwise,
508
- * if callout_info is not NULL, a key will be allocated and some service
509
- * (probably in userspace) will be asked to instantiate it.
556
+ * A key matching the specified criteria (type, description, domain_tag) is
557
+ * searched for in the process's keyrings and returned with its usage count
558
+ * incremented if found.  Otherwise, if callout_info is not NULL, a key will be
559
+ * allocated and some service (probably in userspace) will be asked to
560
+ * instantiate it.
510561  *
511562  * If successfully found or created, the key will be linked to the destination
512563  * keyring if one is provided.
....@@ -522,6 +573,7 @@
522573  */
523574 struct key *request_key_and_link(struct key_type *type,
524575 				 const char *description,
576
+				 struct key_tag *domain_tag,
525577 				 const void *callout_info,
526578 				 size_t callout_len,
527579 				 void *aux,
....@@ -530,6 +582,7 @@
530582 {
531583 	struct keyring_search_context ctx = {
532584 		.index_key.type		= type,
585
+		.index_key.domain_tag	= domain_tag,
533586 		.index_key.description	= description,
534587 		.index_key.desc_len	= strlen(description),
535588 		.cred			= current_cred(),
....@@ -537,7 +590,8 @@
537590 		.match_data.raw_data	= description,
538591 		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
539592 		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
540
-					   KEYRING_SEARCH_SKIP_EXPIRED),
593
+					   KEYRING_SEARCH_SKIP_EXPIRED |
594
+					   KEYRING_SEARCH_RECURSE),
541595 	};
542596 	struct key *key;
543597 	key_ref_t key_ref;
....@@ -555,10 +609,26 @@
555609 		}
556610 	}
557611 
612
+	key = check_cached_key(&ctx);
613
+	if (key)
614
+		goto error_free;
615
+
558616 	/* search all the process keyrings for a key */
559
-	key_ref = search_process_keyrings(&ctx);
617
+	rcu_read_lock();
618
+	key_ref = search_process_keyrings_rcu(&ctx);
619
+	rcu_read_unlock();
560620 
561621 	if (!IS_ERR(key_ref)) {
622
+		if (dest_keyring) {
623
+			ret = key_task_permission(key_ref, current_cred(),
624
+						  KEY_NEED_LINK);
625
+			if (ret < 0) {
626
+				key_ref_put(key_ref);
627
+				key = ERR_PTR(ret);
628
+				goto error_free;
629
+			}
630
+		}
631
+
562632 		key = key_ref_to_ptr(key_ref);
563633 		if (dest_keyring) {
564634 			ret = key_link(dest_keyring, key);
....@@ -568,6 +638,9 @@
568638 				goto error_free;
569639 			}
570640 		}
641
+
642
+		/* Only cache the key on immediate success */
643
+		cache_requested_key(key);
571644 	} else if (PTR_ERR(key_ref) != -EAGAIN) {
572645 		key = ERR_CAST(key_ref);
573646 	} else  {
....@@ -616,9 +689,10 @@
616689 EXPORT_SYMBOL(wait_for_key_construction);
617690 
618691 /**
619
- * request_key - Request a key and wait for construction
692
+ * request_key_tag - Request a key and wait for construction
620693  * @type: Type of key.
621694  * @description: The searchable description of the key.
695
+ * @domain_tag: The domain in which the key operates.
622696  * @callout_info: The data to pass to the instantiation upcall (or NULL).
623697  *
624698  * As for request_key_and_link() except that it does not add the returned key
....@@ -629,9 +703,10 @@
629703  * Furthermore, it then works as wait_for_key_construction() to wait for the
630704  * completion of keys undergoing construction with a non-interruptible wait.
631705  */
632
-struct key *request_key(struct key_type *type,
633
-			const char *description,
634
-			const char *callout_info)
706
+struct key *request_key_tag(struct key_type *type,
707
+			    const char *description,
708
+			    struct key_tag *domain_tag,
709
+			    const char *callout_info)
635710 {
636711 	struct key *key;
637712 	size_t callout_len = 0;
....@@ -639,7 +714,8 @@
639714 
640715 	if (callout_info)
641716 		callout_len = strlen(callout_info);
642
-	key = request_key_and_link(type, description, callout_info, callout_len,
717
+	key = request_key_and_link(type, description, domain_tag,
718
+				   callout_info, callout_len,
643719 				   NULL, NULL, KEY_ALLOC_IN_QUOTA);
644720 	if (!IS_ERR(key)) {
645721 		ret = wait_for_key_construction(key, false);
....@@ -650,12 +726,13 @@
650726 	}
651727 	return key;
652728 }
653
-EXPORT_SYMBOL(request_key);
729
+EXPORT_SYMBOL(request_key_tag);
654730 
655731 /**
656732  * request_key_with_auxdata - Request a key with auxiliary data for the upcaller
657733  * @type: The type of key we want.
658734  * @description: The searchable description of the key.
735
+ * @domain_tag: The domain in which the key operates.
659736  * @callout_info: The data to pass to the instantiation upcall (or NULL).
660737  * @callout_len: The length of callout_info.
661738  * @aux: Auxiliary data for the upcall.
....@@ -668,6 +745,7 @@
668745  */
669746 struct key *request_key_with_auxdata(struct key_type *type,
670747 				     const char *description,
748
+				     struct key_tag *domain_tag,
671749 				     const void *callout_info,
672750 				     size_t callout_len,
673751 				     void *aux)
....@@ -675,7 +753,8 @@
675753 	struct key *key;
676754 	int ret;
677755 
678
-	key = request_key_and_link(type, description, callout_info, callout_len,
756
+	key = request_key_and_link(type, description, domain_tag,
757
+				   callout_info, callout_len,
679758 				   aux, NULL, KEY_ALLOC_IN_QUOTA);
680759 	if (!IS_ERR(key)) {
681760 		ret = wait_for_key_construction(key, false);
....@@ -688,52 +767,55 @@
688767 }
689768 EXPORT_SYMBOL(request_key_with_auxdata);
690769 
691
-/*
692
- * request_key_async - Request a key (allow async construction)
693
- * @type: Type of key.
694
- * @description: The searchable description of the key.
695
- * @callout_info: The data to pass to the instantiation upcall (or NULL).
696
- * @callout_len: The length of callout_info.
770
+/**
771
+ * request_key_rcu - Request key from RCU-read-locked context
772
+ * @type: The type of key we want.
773
+ * @description: The name of the key we want.
774
+ * @domain_tag: The domain in which the key operates.
697775  *
698
- * As for request_key_and_link() except that it does not add the returned key
699
- * to a keyring if found, new keys are always allocated in the user's quota and
700
- * no auxiliary data can be passed.
776
+ * Request a key from a context that we may not sleep in (such as RCU-mode
777
+ * pathwalk).  Keys under construction are ignored.
701778  *
702
- * The caller should call wait_for_key_construction() to wait for the
703
- * completion of the returned key if it is still undergoing construction.
779
+ * Return a pointer to the found key if successful, -ENOKEY if we couldn't find
780
+ * a key or some other error if the key found was unsuitable or inaccessible.
704781  */
705
-struct key *request_key_async(struct key_type *type,
706
-			      const char *description,
707
-			      const void *callout_info,
708
-			      size_t callout_len)
782
+struct key *request_key_rcu(struct key_type *type,
783
+			    const char *description,
784
+			    struct key_tag *domain_tag)
709785 {
710
-	return request_key_and_link(type, description, callout_info,
711
-				    callout_len, NULL, NULL,
712
-				    KEY_ALLOC_IN_QUOTA);
713
-}
714
-EXPORT_SYMBOL(request_key_async);
786
+	struct keyring_search_context ctx = {
787
+		.index_key.type		= type,
788
+		.index_key.domain_tag	= domain_tag,
789
+		.index_key.description	= description,
790
+		.index_key.desc_len	= strlen(description),
791
+		.cred			= current_cred(),
792
+		.match_data.cmp		= key_default_cmp,
793
+		.match_data.raw_data	= description,
794
+		.match_data.lookup_type	= KEYRING_SEARCH_LOOKUP_DIRECT,
795
+		.flags			= (KEYRING_SEARCH_DO_STATE_CHECK |
796
+					   KEYRING_SEARCH_SKIP_EXPIRED),
797
+	};
798
+	struct key *key;
799
+	key_ref_t key_ref;
715800 
716
-/*
717
- * request a key with auxiliary data for the upcaller (allow async construction)
718
- * @type: Type of key.
719
- * @description: The searchable description of the key.
720
- * @callout_info: The data to pass to the instantiation upcall (or NULL).
721
- * @callout_len: The length of callout_info.
722
- * @aux: Auxiliary data for the upcall.
723
- *
724
- * As for request_key_and_link() except that it does not add the returned key
725
- * to a keyring if found and new keys are always allocated in the user's quota.
726
- *
727
- * The caller should call wait_for_key_construction() to wait for the
728
- * completion of the returned key if it is still undergoing construction.
729
- */
730
-struct key *request_key_async_with_auxdata(struct key_type *type,
731
-					   const char *description,
732
-					   const void *callout_info,
733
-					   size_t callout_len,
734
-					   void *aux)
735
-{
736
-	return request_key_and_link(type, description, callout_info,
737
-				    callout_len, aux, NULL, KEY_ALLOC_IN_QUOTA);
801
+	kenter("%s,%s", type->name, description);
802
+
803
+	key = check_cached_key(&ctx);
804
+	if (key)
805
+		return key;
806
+
807
+	/* search all the process keyrings for a key */
808
+	key_ref = search_process_keyrings_rcu(&ctx);
809
+	if (IS_ERR(key_ref)) {
810
+		key = ERR_CAST(key_ref);
811
+		if (PTR_ERR(key_ref) == -EAGAIN)
812
+			key = ERR_PTR(-ENOKEY);
813
+	} else {
814
+		key = key_ref_to_ptr(key_ref);
815
+		cache_requested_key(key);
816
+	}
817
+
818
+	kleave(" = %p", key);
819
+	return key;
738820 }
739
-EXPORT_SYMBOL(request_key_async_with_auxdata);
821
+EXPORT_SYMBOL(request_key_rcu);