aboutsummaryrefslogtreecommitdiff
path: root/block/blk-crypto-profile.c
blob: 96c511967386d56fa4eb6eaeaef16fe838235b77 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
// SPDX-License-Identifier: GPL-2.0
/*
 * Copyright 2019 Google LLC
 */

/**
 * DOC: blk-crypto profiles
 *
 * 'struct blk_crypto_profile' contains all generic inline encryption-related
 * state for a particular inline encryption device.  blk_crypto_profile serves
 * as the way that drivers for inline encryption hardware expose their crypto
 * capabilities and certain functions (e.g., functions to program and evict
 * keys) to upper layers.  Device drivers that want to support inline encryption
 * construct a crypto profile, then associate it with the disk's request_queue.
 *
 * If the device has keyslots, then its blk_crypto_profile also handles managing
 * these keyslots in a device-independent way, using the driver-provided
 * functions to program and evict keys as needed.  This includes keeping track
 * of which key and how many I/O requests are using each keyslot, getting
 * keyslots for I/O requests, and handling key eviction requests.
 *
 * For more information, see Documentation/block/inline-encryption.rst.
 */

#define pr_fmt(fmt) "blk-crypto: " fmt

#include <linux/blk-crypto-profile.h>
#include <linux/device.h>
#include <linux/atomic.h>
#include <linux/mutex.h>
#include <linux/pm_runtime.h>
#include <linux/wait.h>
#include <linux/blkdev.h>
#include <linux/blk-integrity.h>

struct blk_crypto_keyslot {
	atomic_t slot_refs;
	struct list_head idle_slot_node;
	struct hlist_node hash_node;
	const struct blk_crypto_key *key;
	struct blk_crypto_profile *profile;
};

static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile)
{
	/*
	 * Calling into the driver requires profile->lock held and the device
	 * resumed.  But we must resume the device first, since that can acquire
	 * and release profile->lock via blk_crypto_reprogram_all_keys().
	 */
	if (profile->dev)
		pm_runtime_get_sync(profile->dev);
	down_write(&profile->lock);
}

static inline void blk_crypto_hw_exit(struct blk_crypto_profile *profile)
{
	up_write(&profile->lock);
	if (profile->dev)
		pm_runtime_put_sync(profile->dev);
}

/**
 * blk_crypto_profile_init() - Initialize a blk_crypto_profile
 * @profile: the blk_crypto_profile to initialize
 * @num_slots: the number of keyslots
 *
 * Storage drivers must call this when starting to set up a blk_crypto_profile,
 * before filling in additional fields.
 *
 * Return: 0 on success, or else a negative error code.
 */
int blk_crypto_profile_init(struct blk_crypto_profile *profile,
			    unsigned int num_slots)
{
	unsigned int slot;
	unsigned int i;
	unsigned int slot_hashtable_size;

	memset(profile, 0, sizeof(*profile));
	init_rwsem(&profile->lock);

	if (num_slots == 0)
		return 0;

	/* Initialize keyslot management data. */

	profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]),
				  GFP_KERNEL);
	if (!profile->slots)
		return -ENOMEM;

	profile->num_slots = num_slots;

	init_waitqueue_head(&profile->idle_slots_wait_queue);
	INIT_LIST_HEAD(&profile->idle_slots);

	for (slot = 0; slot < num_slots; slot++) {
		profile->slots[slot].profile = profile;
		list_add_tail(&profile->slots[slot].idle_slot_node,
			      &profile->idle_slots);
	}

	spin_lock_init(&profile->idle_slots_lock);

	slot_hashtable_size = roundup_pow_of_two(num_slots);
	/*
	 * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
	 * buckets.  This only makes a difference when there is only 1 keyslot.
	 */
	if (slot_hashtable_size < 2)
		slot_hashtable_size = 2;

	profile->log_slot_ht_size = ilog2(slot_hashtable_size);
	profile->slot_hashtable =
		kvmalloc_array(slot_hashtable_size,
			       sizeof(profile->slot_hashtable[0]), GFP_KERNEL);
	if (!profile->slot_hashtable)
		goto err_destroy;
	for (i = 0; i < slot_hashtable_size; i++)
		INIT_HLIST_HEAD(&profile->slot_hashtable[i]);

	return 0;

err_destroy:
	blk_crypto_profile_destroy(profile);
	return -ENOMEM;
}
EXPORT_SYMBOL_GPL(blk_crypto_profile_init);

static void blk_crypto_profile_destroy_callback(void *profile)
{
	blk_crypto_profile_destroy(profile);
}

/**
 * devm_blk_crypto_profile_init() - Resource-managed blk_crypto_profile_init()
 * @dev: the device which owns the blk_crypto_profile
 * @profile: the blk_crypto_profile to initialize
 * @num_slots: the number of keyslots
 *
 * Like blk_crypto_profile_init(), but causes blk_crypto_profile_destroy() to be
 * called automatically on driver detach.
 *
 * Return: 0 on success, or else a negative error code.
 */
int devm_blk_crypto_profile_init(struct device *dev,
				 struct blk_crypto_profile *profile,
				 unsigned int num_slots)
{
	int err = blk_crypto_profile_init(profile, num_slots);

	if (err)
		return err;

	return devm_add_action_or_reset(dev,
					blk_crypto_profile_destroy_callback,
					profile);
}
EXPORT_SYMBOL_GPL(devm_blk_crypto_profile_init);

static inline struct hlist_head *
blk_crypto_hash_bucket_for_key(struct blk_crypto_profile *profile,
			       const struct blk_crypto_key *key)
{
	return &profile->slot_hashtable[
			hash_ptr(key, profile->log_slot_ht_size)];
}

static void
blk_crypto_remove_slot_from_lru_list(struct blk_crypto_keyslot *slot)
{
	struct blk_crypto_profile *profile = slot->profile;
	unsigned long flags;

	spin_lock_irqsave(&profile->idle_slots_lock, flags);
	list_del(&slot->idle_slot_node);
	spin_unlock_irqrestore(&profile->idle_slots_lock, flags);
}

static struct blk_crypto_keyslot *
blk_crypto_find_keyslot(struct blk_crypto_profile *profile,
			const struct blk_crypto_key *key)
{
	const struct hlist_head *head =
		blk_crypto_hash_bucket_for_key(profile, key);
	struct blk_crypto_keyslot *slotp;

	hlist_for_each_entry(slotp, head, hash_node) {
		if (slotp->key == key)
			return slotp;
	}
	return NULL;
}

static struct blk_crypto_keyslot *
blk_crypto_find_and_grab_keyslot(struct blk_crypto_profile *profile,
				 const struct blk_crypto_key *key)
{
	struct blk_crypto_keyslot *slot;

	slot = blk_crypto_find_keyslot(profile, key);
	if (!slot)
		return NULL;
	if (atomic_inc_return(&slot->slot_refs) == 1) {
		/* Took first reference to this slot; remove it from LRU list */
		blk_crypto_remove_slot_from_lru_list(slot);
	}
	return slot;
}

/**
 * blk_crypto_keyslot_index() - Get the index of a keyslot
 * @slot: a keyslot that blk_crypto_get_keyslot() returned
 *
 * Return: the 0-based index of the keyslot within the device's keyslots.
 */
unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot)
{
	return slot - slot->profile->slots;
}
EXPORT_SYMBOL_GPL(blk_crypto_keyslot_index);

/**
 * blk_crypto_get_keyslot() - Get a keyslot for a key, if needed.
 * @profile: the crypto profile of the device the key will be used on
 * @key: the key that will be used
 * @slot_ptr: If a keyslot is allocated, an opaque pointer to the keyslot struct
 *	      will be stored here; otherwise NULL will be stored here.
 *
 * If the device has keyslots, this gets a keyslot that's been programmed with
 * the specified key.  If the key is already in a slot, this reuses it;
 * otherwise this waits for a slot to become idle and programs the key into it.
 *
 * This must be paired with a call to blk_crypto_put_keyslot().
 *
 * Context: Process context. Takes and releases profile->lock.
 * Return: BLK_STS_OK on success, meaning that either a keyslot was allocated or
 *	   one wasn't needed; or a blk_status_t error on failure.
 */
blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile,
				    const struct blk_crypto_key *key,
				    struct blk_crypto_keyslot **slot_ptr)
{
	struct blk_crypto_keyslot *slot;
	int slot_idx;
	int err;

	*slot_ptr = NULL;

	/*
	 * If the device has no concept of "keyslots", then there is no need to
	 * get one.
	 */
	if (profile->num_slots == 0)
		return BLK_STS_OK;

	down_read(&profile->lock);
	slot = blk_crypto_find_and_grab_keyslot(profile, key);
	up_read(&profile->lock);
	if (slot)
		goto success;

	for (;;) {
		blk_crypto_hw_enter(profile);
		slot = blk_crypto_find_and_grab_keyslot(profile, key);
		if (slot) {
			blk_crypto_hw_exit(profile);
			goto success;
		}

		/*
		 * If we're here, that means there wasn't a slot that was
		 * already programmed with the key. So try to program it.
		 */
		if (!list_empty(&profile->idle_slots))
			break;

		blk_crypto_hw_exit(profile);
		wait_event(profile->idle_slots_wait_queue,
			   !list_empty(&profile->idle_slots));
	}

	slot = list_first_entry(&profile->idle_slots, struct blk_crypto_keyslot,
				idle_slot_node);
	slot_idx = blk_crypto_keyslot_index(slot);

	err = profile->ll_ops.keyslot_program(profile, key, slot_idx);
	if (err) {
		wake_up(&profile->idle_slots_wait_queue);
		blk_crypto_hw_exit(profile);
		return errno_to_blk_status(err);
	}

	/* Move this slot to the hash list for the new key. */
	if (slot->key)
		hlist_del(&slot->hash_node);
	slot->key = key;
	hlist_add_head(&slot->hash_node,
		       blk_crypto_hash_bucket_for_key(profile, key));

	atomic_set(&slot->slot_refs, 1);

	blk_crypto_remove_slot_from_lru_list(slot);

	blk_crypto_hw_exit(profile);
success:
	*slot_ptr = slot;
	return BLK_STS_OK;
}

/**
 * blk_crypto_put_keyslot() - Release a reference to a keyslot
 * @slot: The keyslot to release the reference of (may be NULL).
 *
 * Context: Any context.
 */
void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot)
{
	struct blk_crypto_profile *profile;
	unsigned long flags;

	if (!slot)
		return;

	profile = slot->profile;

	if (atomic_dec_and_lock_irqsave(&slot->slot_refs,
					&profile->idle_slots_lock, flags)) {
		list_add_tail(&slot->idle_slot_node, &profile->idle_slots);
		spin_unlock_irqrestore(&profile->idle_slots_lock, flags);
		wake_up(&profile->idle_slots_wait_queue);
	}
}

/**
 * __blk_crypto_cfg_supported() - Check whether the given crypto profile
 *				  supports the given crypto configuration.
 * @profile: the crypto profile to check
 * @cfg: the crypto configuration to check for
 *
 * Return: %true if @profile supports the given @cfg.
 */
bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile,
				const struct blk_crypto_config *cfg)
{
	if (!profile)
		return false;
	if (!(profile->modes_supported[cfg->crypto_mode] & cfg->data_unit_size))
		return false;
	if (profile->max_dun_bytes_supported < cfg->dun_bytes)
		return false;
	return true;
}

/**
 * __blk_crypto_evict_key() - Evict a key from a device.
 * @profile: the crypto profile of the device
 * @key: the key to evict.  It must not still be used in any I/O.
 *
 * If the device has keyslots, this finds the keyslot (if any) that contains the
 * specified key and calls the driver's keyslot_evict function to evict it.
 *
 * Otherwise, this just calls the driver's keyslot_evict function if it is
 * implemented, passing just the key (without any particular keyslot).  This
 * allows layered devices to evict the key from their underlying devices.
 *
 * Context: Process context. Takes and releases profile->lock.
 * Return: 0 on success or if there's no keyslot with the specified key, -EBUSY
 *	   if the keyslot is still in use, or another -errno value on other
 *	   error.
 */
int __blk_crypto_evict_key(struct blk_crypto_profile *profile,
			   const struct blk_crypto_key *key)
{
	struct blk_crypto_keyslot *slot;
	int err = 0;

	if (profile->num_slots == 0) {
		if (profile->ll_ops.keyslot_evict) {
			blk_crypto_hw_enter(profile);
			err = profile->ll_ops.keyslot_evict(profile, key, -1);
			blk_crypto_hw_exit(profile);
			return err;
		}
		return 0;
	}

	blk_crypto_hw_enter(profile);
	slot = blk_crypto_find_keyslot(profile, key);
	if (!slot)
		goto out_unlock;

	if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) {
		err = -EBUSY;
		goto out_unlock;
	}
	err = profile->ll_ops.keyslot_evict(profile, key,
					    blk_crypto_keyslot_index(slot));
	if (err)
		goto out_unlock;

	hlist_del(&slot->hash_node);
	slot->key = NULL;
	err = 0;
out_unlock:
	blk_crypto_hw_exit(profile);
	return err;
}

/**
 * blk_crypto_reprogram_all_keys() - Re-program all keyslots.
 * @profile: The crypto profile
 *
 * Re-program all keyslots that are supposed to have a key programmed.  This is
 * intended only for use by drivers for hardware that loses its keys on reset.
 *
 * Context: Process context. Takes and releases profile->lock.
 */
void blk_crypto_reprogram_all_keys(struct blk_crypto_profile *profile)
{
	unsigned int slot;

	if (profile->num_slots == 0)
		return;

	/* This is for device initialization, so don't resume the device */
	down_write(&profile->lock);
	for (slot = 0; slot < profile->num_slots; slot++) {
		const struct blk_crypto_key *key = profile->slots[slot].key;
		int err;

		if (!key)
			continue;

		err = profile->ll_ops.keyslot_program(profile, key, slot);
		WARN_ON(err);
	}
	up_write(&profile->lock);
}
EXPORT_SYMBOL_GPL(blk_crypto_reprogram_all_keys);

void blk_crypto_profile_destroy(struct blk_crypto_profile *profile)
{
	if (!profile)
		return;
	kvfree(profile->slot_hashtable);
	kvfree_sensitive(profile->slots,
			 sizeof(profile->slots[0]) * profile->num_slots);
	memzero_explicit(profile, sizeof(*profile));
}
EXPORT_SYMBOL_GPL(blk_crypto_profile_destroy);

bool blk_crypto_register(struct blk_crypto_profile *profile,
			 struct request_queue *q)
{
	if (blk_integrity_queue_supports_integrity(q)) {
		pr_warn("Integrity and hardware inline encryption are not supported together. Disabling hardware inline encryption.\n");
		return false;
	}
	q->crypto_profile = profile;
	return true;
}
EXPORT_SYMBOL_GPL(blk_crypto_register);

/**
 * blk_crypto_intersect_capabilities() - restrict supported crypto capabilities
 *					 by child device
 * @parent: the crypto profile for the parent device
 * @child: the crypto profile for the child device, or NULL
 *
 * This clears all crypto capabilities in @parent that aren't set in @child.  If
 * @child is NULL, then this clears all parent capabilities.
 *
 * Only use this when setting up the crypto profile for a layered device, before
 * it's been exposed yet.
 */
void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent,
				       const struct blk_crypto_profile *child)
{
	if (child) {
		unsigned int i;

		parent->max_dun_bytes_supported =
			min(parent->max_dun_bytes_supported,
			    child->max_dun_bytes_supported);
		for (i = 0; i < ARRAY_SIZE(child->modes_supported); i++)
			parent->modes_supported[i] &= child->modes_supported[i];
	} else {
		parent->max_dun_bytes_supported = 0;
		memset(parent->modes_supported, 0,
		       sizeof(parent->modes_supported));
	}
}
EXPORT_SYMBOL_GPL(blk_crypto_intersect_capabilities);

/**
 * blk_crypto_has_capabilities() - Check whether @target supports at least all
 *				   the crypto capabilities that @reference does.
 * @target: the target profile
 * @reference: the reference profile
 *
 * Return: %true if @target supports all the crypto capabilities of @reference.
 */
bool blk_crypto_has_capabilities(const struct blk_crypto_profile *target,
				 const struct blk_crypto_profile *reference)
{
	int i;

	if (!reference)
		return true;

	if (!target)
		return false;

	for (i = 0; i < ARRAY_SIZE(target->modes_supported); i++) {
		if (reference->modes_supported[i] & ~target->modes_supported[i])
			return false;
	}

	if (reference->max_dun_bytes_supported >
	    target->max_dun_bytes_supported)
		return false;

	return true;
}
EXPORT_SYMBOL_GPL(blk_crypto_has_capabilities);

/**
 * blk_crypto_update_capabilities() - Update the capabilities of a crypto
 *				      profile to match those of another crypto
 *				      profile.
 * @dst: The crypto profile whose capabilities to update.
 * @src: The crypto profile whose capabilities this function will update @dst's
 *	 capabilities to.
 *
 * Blk-crypto requires that crypto capabilities that were
 * advertised when a bio was created continue to be supported by the
 * device until that bio is ended. This is turn means that a device cannot
 * shrink its advertised crypto capabilities without any explicit
 * synchronization with upper layers. So if there's no such explicit
 * synchronization, @src must support all the crypto capabilities that
 * @dst does (i.e. we need blk_crypto_has_capabilities(@src, @dst)).
 *
 * Note also that as long as the crypto capabilities are being expanded, the
 * order of updates becoming visible is not important because it's alright
 * for blk-crypto to see stale values - they only cause blk-crypto to
 * believe that a crypto capability isn't supported when it actually is (which
 * might result in blk-crypto-fallback being used if available, or the bio being
 * failed).
 */
void blk_crypto_update_capabilities(struct blk_crypto_profile *dst,
				    const struct blk_crypto_profile *src)
{
	memcpy(dst->modes_supported, src->modes_supported,
	       sizeof(dst->modes_supported));

	dst->max_dun_bytes_supported = src->max_dun_bytes_supported;
}
EXPORT_SYMBOL_GPL(blk_crypto_update_capabilities);