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1// SPDX-License-Identifier: GPL-2.0
2/*
3 * Copyright 2019 Google LLC
4 */
5
6/**
7 * DOC: blk-crypto profiles
8 *
9 * 'struct blk_crypto_profile' contains all generic inline encryption-related
10 * state for a particular inline encryption device. blk_crypto_profile serves
11 * as the way that drivers for inline encryption hardware expose their crypto
12 * capabilities and certain functions (e.g., functions to program and evict
13 * keys) to upper layers. Device drivers that want to support inline encryption
14 * construct a crypto profile, then associate it with the disk's request_queue.
15 *
16 * If the device has keyslots, then its blk_crypto_profile also handles managing
17 * these keyslots in a device-independent way, using the driver-provided
18 * functions to program and evict keys as needed. This includes keeping track
19 * of which key and how many I/O requests are using each keyslot, getting
20 * keyslots for I/O requests, and handling key eviction requests.
21 *
22 * For more information, see Documentation/block/inline-encryption.rst.
23 */
24
25#define pr_fmt(fmt) "blk-crypto: " fmt
26
27#include <linux/blk-crypto-profile.h>
28#include <linux/device.h>
29#include <linux/atomic.h>
30#include <linux/mutex.h>
31#include <linux/pm_runtime.h>
32#include <linux/wait.h>
33#include <linux/blkdev.h>
34#include <linux/blk-integrity.h>
35#include "blk-crypto-internal.h"
36
37struct blk_crypto_keyslot {
38 atomic_t slot_refs;
39 struct list_head idle_slot_node;
40 struct hlist_node hash_node;
41 const struct blk_crypto_key *key;
42 struct blk_crypto_profile *profile;
43};
44
45static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile)
46{
47 /*
48 * Calling into the driver requires profile->lock held and the device
49 * resumed. But we must resume the device first, since that can acquire
50 * and release profile->lock via blk_crypto_reprogram_all_keys().
51 */
52 if (profile->dev)
53 pm_runtime_get_sync(profile->dev);
54 down_write(&profile->lock);
55}
56
57static inline void blk_crypto_hw_exit(struct blk_crypto_profile *profile)
58{
59 up_write(&profile->lock);
60 if (profile->dev)
61 pm_runtime_put_sync(profile->dev);
62}
63
64/**
65 * blk_crypto_profile_init() - Initialize a blk_crypto_profile
66 * @profile: the blk_crypto_profile to initialize
67 * @num_slots: the number of keyslots
68 *
69 * Storage drivers must call this when starting to set up a blk_crypto_profile,
70 * before filling in additional fields.
71 *
72 * Return: 0 on success, or else a negative error code.
73 */
74int blk_crypto_profile_init(struct blk_crypto_profile *profile,
75 unsigned int num_slots)
76{
77 unsigned int slot;
78 unsigned int i;
79 unsigned int slot_hashtable_size;
80
81 memset(profile, 0, sizeof(*profile));
82 init_rwsem(&profile->lock);
83
84 if (num_slots == 0)
85 return 0;
86
87 /* Initialize keyslot management data. */
88
89 profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]),
90 GFP_KERNEL);
91 if (!profile->slots)
92 return -ENOMEM;
93
94 profile->num_slots = num_slots;
95
96 init_waitqueue_head(&profile->idle_slots_wait_queue);
97 INIT_LIST_HEAD(&profile->idle_slots);
98
99 for (slot = 0; slot < num_slots; slot++) {
100 profile->slots[slot].profile = profile;
101 list_add_tail(&profile->slots[slot].idle_slot_node,
102 &profile->idle_slots);
103 }
104
105 spin_lock_init(&profile->idle_slots_lock);
106
107 slot_hashtable_size = roundup_pow_of_two(num_slots);
108 /*
109 * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2
110 * buckets. This only makes a difference when there is only 1 keyslot.
111 */
112 if (slot_hashtable_size < 2)
113 slot_hashtable_size = 2;
114
115 profile->log_slot_ht_size = ilog2(slot_hashtable_size);
116 profile->slot_hashtable =
117 kvmalloc_array(slot_hashtable_size,
118 sizeof(profile->slot_hashtable[0]), GFP_KERNEL);
119 if (!profile->slot_hashtable)
120 goto err_destroy;
121 for (i = 0; i < slot_hashtable_size; i++)
122 INIT_HLIST_HEAD(&profile->slot_hashtable[i]);
123
124 return 0;
125
126err_destroy:
127 blk_crypto_profile_destroy(profile);
128 return -ENOMEM;
129}
130EXPORT_SYMBOL_GPL(blk_crypto_profile_init);
131
132static void blk_crypto_profile_destroy_callback(void *profile)
133{
134 blk_crypto_profile_destroy(profile);
135}
136
137/**
138 * devm_blk_crypto_profile_init() - Resource-managed blk_crypto_profile_init()
139 * @dev: the device which owns the blk_crypto_profile
140 * @profile: the blk_crypto_profile to initialize
141 * @num_slots: the number of keyslots
142 *
143 * Like blk_crypto_profile_init(), but causes blk_crypto_profile_destroy() to be
144 * called automatically on driver detach.
145 *
146 * Return: 0 on success, or else a negative error code.
147 */
148int devm_blk_crypto_profile_init(struct device *dev,
149 struct blk_crypto_profile *profile,
150 unsigned int num_slots)
151{
152 int err = blk_crypto_profile_init(profile, num_slots);
153
154 if (err)
155 return err;
156
157 return devm_add_action_or_reset(dev,
158 blk_crypto_profile_destroy_callback,
159 profile);
160}
161EXPORT_SYMBOL_GPL(devm_blk_crypto_profile_init);
162
163static inline struct hlist_head *
164blk_crypto_hash_bucket_for_key(struct blk_crypto_profile *profile,
165 const struct blk_crypto_key *key)
166{
167 return &profile->slot_hashtable[
168 hash_ptr(key, profile->log_slot_ht_size)];
169}
170
171static void
172blk_crypto_remove_slot_from_lru_list(struct blk_crypto_keyslot *slot)
173{
174 struct blk_crypto_profile *profile = slot->profile;
175 unsigned long flags;
176
177 spin_lock_irqsave(&profile->idle_slots_lock, flags);
178 list_del(&slot->idle_slot_node);
179 spin_unlock_irqrestore(&profile->idle_slots_lock, flags);
180}
181
182static struct blk_crypto_keyslot *
183blk_crypto_find_keyslot(struct blk_crypto_profile *profile,
184 const struct blk_crypto_key *key)
185{
186 const struct hlist_head *head =
187 blk_crypto_hash_bucket_for_key(profile, key);
188 struct blk_crypto_keyslot *slotp;
189
190 hlist_for_each_entry(slotp, head, hash_node) {
191 if (slotp->key == key)
192 return slotp;
193 }
194 return NULL;
195}
196
197static struct blk_crypto_keyslot *
198blk_crypto_find_and_grab_keyslot(struct blk_crypto_profile *profile,
199 const struct blk_crypto_key *key)
200{
201 struct blk_crypto_keyslot *slot;
202
203 slot = blk_crypto_find_keyslot(profile, key);
204 if (!slot)
205 return NULL;
206 if (atomic_inc_return(&slot->slot_refs) == 1) {
207 /* Took first reference to this slot; remove it from LRU list */
208 blk_crypto_remove_slot_from_lru_list(slot);
209 }
210 return slot;
211}
212
213/**
214 * blk_crypto_keyslot_index() - Get the index of a keyslot
215 * @slot: a keyslot that blk_crypto_get_keyslot() returned
216 *
217 * Return: the 0-based index of the keyslot within the device's keyslots.
218 */
219unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot)
220{
221 return slot - slot->profile->slots;
222}
223EXPORT_SYMBOL_GPL(blk_crypto_keyslot_index);
224
225/**
226 * blk_crypto_get_keyslot() - Get a keyslot for a key, if needed.
227 * @profile: the crypto profile of the device the key will be used on
228 * @key: the key that will be used
229 * @slot_ptr: If a keyslot is allocated, an opaque pointer to the keyslot struct
230 * will be stored here; otherwise NULL will be stored here.
231 *
232 * If the device has keyslots, this gets a keyslot that's been programmed with
233 * the specified key. If the key is already in a slot, this reuses it;
234 * otherwise this waits for a slot to become idle and programs the key into it.
235 *
236 * This must be paired with a call to blk_crypto_put_keyslot().
237 *
238 * Context: Process context. Takes and releases profile->lock.
239 * Return: BLK_STS_OK on success, meaning that either a keyslot was allocated or
240 * one wasn't needed; or a blk_status_t error on failure.
241 */
242blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile,
243 const struct blk_crypto_key *key,
244 struct blk_crypto_keyslot **slot_ptr)
245{
246 struct blk_crypto_keyslot *slot;
247 int slot_idx;
248 int err;
249
250 *slot_ptr = NULL;
251
252 /*
253 * If the device has no concept of "keyslots", then there is no need to
254 * get one.
255 */
256 if (profile->num_slots == 0)
257 return BLK_STS_OK;
258
259 down_read(&profile->lock);
260 slot = blk_crypto_find_and_grab_keyslot(profile, key);
261 up_read(&profile->lock);
262 if (slot)
263 goto success;
264
265 for (;;) {
266 blk_crypto_hw_enter(profile);
267 slot = blk_crypto_find_and_grab_keyslot(profile, key);
268 if (slot) {
269 blk_crypto_hw_exit(profile);
270 goto success;
271 }
272
273 /*
274 * If we're here, that means there wasn't a slot that was
275 * already programmed with the key. So try to program it.
276 */
277 if (!list_empty(&profile->idle_slots))
278 break;
279
280 blk_crypto_hw_exit(profile);
281 wait_event(profile->idle_slots_wait_queue,
282 !list_empty(&profile->idle_slots));
283 }
284
285 slot = list_first_entry(&profile->idle_slots, struct blk_crypto_keyslot,
286 idle_slot_node);
287 slot_idx = blk_crypto_keyslot_index(slot);
288
289 err = profile->ll_ops.keyslot_program(profile, key, slot_idx);
290 if (err) {
291 wake_up(&profile->idle_slots_wait_queue);
292 blk_crypto_hw_exit(profile);
293 return errno_to_blk_status(err);
294 }
295
296 /* Move this slot to the hash list for the new key. */
297 if (slot->key)
298 hlist_del(&slot->hash_node);
299 slot->key = key;
300 hlist_add_head(&slot->hash_node,
301 blk_crypto_hash_bucket_for_key(profile, key));
302
303 atomic_set(&slot->slot_refs, 1);
304
305 blk_crypto_remove_slot_from_lru_list(slot);
306
307 blk_crypto_hw_exit(profile);
308success:
309 *slot_ptr = slot;
310 return BLK_STS_OK;
311}
312
313/**
314 * blk_crypto_put_keyslot() - Release a reference to a keyslot
315 * @slot: The keyslot to release the reference of (may be NULL).
316 *
317 * Context: Any context.
318 */
319void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot)
320{
321 struct blk_crypto_profile *profile;
322 unsigned long flags;
323
324 if (!slot)
325 return;
326
327 profile = slot->profile;
328
329 if (atomic_dec_and_lock_irqsave(&slot->slot_refs,
330 &profile->idle_slots_lock, flags)) {
331 list_add_tail(&slot->idle_slot_node, &profile->idle_slots);
332 spin_unlock_irqrestore(&profile->idle_slots_lock, flags);
333 wake_up(&profile->idle_slots_wait_queue);
334 }
335}
336
337/**
338 * __blk_crypto_cfg_supported() - Check whether the given crypto profile
339 * supports the given crypto configuration.
340 * @profile: the crypto profile to check
341 * @cfg: the crypto configuration to check for
342 *
343 * Return: %true if @profile supports the given @cfg.
344 */
345bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile,
346 const struct blk_crypto_config *cfg)
347{
348 if (!profile)
349 return false;
350 if (!(profile->modes_supported[cfg->crypto_mode] & cfg->data_unit_size))
351 return false;
352 if (profile->max_dun_bytes_supported < cfg->dun_bytes)
353 return false;
354 return true;
355}
356
357/**
358 * __blk_crypto_evict_key() - Evict a key from a device.
359 * @profile: the crypto profile of the device
360 * @key: the key to evict. It must not still be used in any I/O.
361 *
362 * If the device has keyslots, this finds the keyslot (if any) that contains the
363 * specified key and calls the driver's keyslot_evict function to evict it.
364 *
365 * Otherwise, this just calls the driver's keyslot_evict function if it is
366 * implemented, passing just the key (without any particular keyslot). This
367 * allows layered devices to evict the key from their underlying devices.
368 *
369 * Context: Process context. Takes and releases profile->lock.
370 * Return: 0 on success or if there's no keyslot with the specified key, -EBUSY
371 * if the keyslot is still in use, or another -errno value on other
372 * error.
373 */
374int __blk_crypto_evict_key(struct blk_crypto_profile *profile,
375 const struct blk_crypto_key *key)
376{
377 struct blk_crypto_keyslot *slot;
378 int err = 0;
379
380 if (profile->num_slots == 0) {
381 if (profile->ll_ops.keyslot_evict) {
382 blk_crypto_hw_enter(profile);
383 err = profile->ll_ops.keyslot_evict(profile, key, -1);
384 blk_crypto_hw_exit(profile);
385 return err;
386 }
387 return 0;
388 }
389
390 blk_crypto_hw_enter(profile);
391 slot = blk_crypto_find_keyslot(profile, key);
392 if (!slot)
393 goto out_unlock;
394
395 if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) {
396 err = -EBUSY;
397 goto out_unlock;
398 }
399 err = profile->ll_ops.keyslot_evict(profile, key,
400 blk_crypto_keyslot_index(slot));
401 if (err)
402 goto out_unlock;
403
404 hlist_del(&slot->hash_node);
405 slot->key = NULL;
406 err = 0;
407out_unlock:
408 blk_crypto_hw_exit(profile);
409 return err;
410}
411
412/**
413 * blk_crypto_reprogram_all_keys() - Re-program all keyslots.
414 * @profile: The crypto profile
415 *
416 * Re-program all keyslots that are supposed to have a key programmed. This is
417 * intended only for use by drivers for hardware that loses its keys on reset.
418 *
419 * Context: Process context. Takes and releases profile->lock.
420 */
421void blk_crypto_reprogram_all_keys(struct blk_crypto_profile *profile)
422{
423 unsigned int slot;
424
425 if (profile->num_slots == 0)
426 return;
427
428 /* This is for device initialization, so don't resume the device */
429 down_write(&profile->lock);
430 for (slot = 0; slot < profile->num_slots; slot++) {
431 const struct blk_crypto_key *key = profile->slots[slot].key;
432 int err;
433
434 if (!key)
435 continue;
436
437 err = profile->ll_ops.keyslot_program(profile, key, slot);
438 WARN_ON(err);
439 }
440 up_write(&profile->lock);
441}
442EXPORT_SYMBOL_GPL(blk_crypto_reprogram_all_keys);
443
444void blk_crypto_profile_destroy(struct blk_crypto_profile *profile)
445{
446 if (!profile)
447 return;
448 kvfree(profile->slot_hashtable);
449 kvfree_sensitive(profile->slots,
450 sizeof(profile->slots[0]) * profile->num_slots);
451 memzero_explicit(profile, sizeof(*profile));
452}
453EXPORT_SYMBOL_GPL(blk_crypto_profile_destroy);
454
455bool blk_crypto_register(struct blk_crypto_profile *profile,
456 struct request_queue *q)
457{
458 if (blk_integrity_queue_supports_integrity(q)) {
459 pr_warn("Integrity and hardware inline encryption are not supported together. Disabling hardware inline encryption.\n");
460 return false;
461 }
462 q->crypto_profile = profile;
463 return true;
464}
465EXPORT_SYMBOL_GPL(blk_crypto_register);
466
467/**
468 * blk_crypto_intersect_capabilities() - restrict supported crypto capabilities
469 * by child device
470 * @parent: the crypto profile for the parent device
471 * @child: the crypto profile for the child device, or NULL
472 *
473 * This clears all crypto capabilities in @parent that aren't set in @child. If
474 * @child is NULL, then this clears all parent capabilities.
475 *
476 * Only use this when setting up the crypto profile for a layered device, before
477 * it's been exposed yet.
478 */
479void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent,
480 const struct blk_crypto_profile *child)
481{
482 if (child) {
483 unsigned int i;
484
485 parent->max_dun_bytes_supported =
486 min(parent->max_dun_bytes_supported,
487 child->max_dun_bytes_supported);
488 for (i = 0; i < ARRAY_SIZE(child->modes_supported); i++)
489 parent->modes_supported[i] &= child->modes_supported[i];
490 } else {
491 parent->max_dun_bytes_supported = 0;
492 memset(parent->modes_supported, 0,
493 sizeof(parent->modes_supported));
494 }
495}
496EXPORT_SYMBOL_GPL(blk_crypto_intersect_capabilities);
497
498/**
499 * blk_crypto_has_capabilities() - Check whether @target supports at least all
500 * the crypto capabilities that @reference does.
501 * @target: the target profile
502 * @reference: the reference profile
503 *
504 * Return: %true if @target supports all the crypto capabilities of @reference.
505 */
506bool blk_crypto_has_capabilities(const struct blk_crypto_profile *target,
507 const struct blk_crypto_profile *reference)
508{
509 int i;
510
511 if (!reference)
512 return true;
513
514 if (!target)
515 return false;
516
517 for (i = 0; i < ARRAY_SIZE(target->modes_supported); i++) {
518 if (reference->modes_supported[i] & ~target->modes_supported[i])
519 return false;
520 }
521
522 if (reference->max_dun_bytes_supported >
523 target->max_dun_bytes_supported)
524 return false;
525
526 return true;
527}
528EXPORT_SYMBOL_GPL(blk_crypto_has_capabilities);
529
530/**
531 * blk_crypto_update_capabilities() - Update the capabilities of a crypto
532 * profile to match those of another crypto
533 * profile.
534 * @dst: The crypto profile whose capabilities to update.
535 * @src: The crypto profile whose capabilities this function will update @dst's
536 * capabilities to.
537 *
538 * Blk-crypto requires that crypto capabilities that were
539 * advertised when a bio was created continue to be supported by the
540 * device until that bio is ended. This is turn means that a device cannot
541 * shrink its advertised crypto capabilities without any explicit
542 * synchronization with upper layers. So if there's no such explicit
543 * synchronization, @src must support all the crypto capabilities that
544 * @dst does (i.e. we need blk_crypto_has_capabilities(@src, @dst)).
545 *
546 * Note also that as long as the crypto capabilities are being expanded, the
547 * order of updates becoming visible is not important because it's alright
548 * for blk-crypto to see stale values - they only cause blk-crypto to
549 * believe that a crypto capability isn't supported when it actually is (which
550 * might result in blk-crypto-fallback being used if available, or the bio being
551 * failed).
552 */
553void blk_crypto_update_capabilities(struct blk_crypto_profile *dst,
554 const struct blk_crypto_profile *src)
555{
556 memcpy(dst->modes_supported, src->modes_supported,
557 sizeof(dst->modes_supported));
558
559 dst->max_dun_bytes_supported = src->max_dun_bytes_supported;
560}
561EXPORT_SYMBOL_GPL(blk_crypto_update_capabilities);