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

source code of linux/block/blk-crypto-profile.c