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 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(&profile->lockdep_key); 89 __init_rwsem(&profile->lock, "&profile->lock", &profile->lockdep_key); 90 91 if (num_slots == 0) 92 return 0; 93 94 /* Initialize keyslot management data. */ 95 96 profile->slots = kvcalloc(num_slots, 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(&profile->idle_slots); 105 106 for (slot = 0; slot < num_slots; slot++) { 107 profile->slots[slot].profile = profile; 108 list_add_tail(&profile->slots[slot].idle_slot_node, 109 &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(slot_hashtable_size, 125 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(key, 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(&slot->idle_slot_node); 186 spin_unlock_irqrestore(&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(&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(&profile->lock); 266 slot = blk_crypto_find_and_grab_keyslot(profile, key); 267 up_read(&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(&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(err); 300 } 301 302 /* Move this slot to the hash list for the new key. */ 303 if (slot->key) 304 hlist_del(&slot->hash_node); 305 slot->key = key; 306 hlist_add_head(&slot->hash_node, 307 blk_crypto_hash_bucket_for_key(profile, key)); 308 309 atomic_set(&slot->slot_refs, 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(&slot->idle_slot_node, &profile->idle_slots); 333 spin_unlock_irqrestore(&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(&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(&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(&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(&profile->lockdep_key); 446 kvfree(profile->slot_hashtable); 447 kvfree_sensitive(profile->slots, 448 sizeof(profile->slots[0]) * profile->num_slots); 449 memzero_explicit(profile, 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