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 37 struct 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 45 static 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 57 static 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 */ 74 int 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 = kvzalloc_objs(profile->slots[0], num_slots); 97 if (!profile->slots) 98 goto err_destroy; 99 100 profile->num_slots = num_slots; 101 102 init_waitqueue_head(&profile->idle_slots_wait_queue); 103 INIT_LIST_HEAD(&profile->idle_slots); 104 105 for (slot = 0; slot < num_slots; slot++) { 106 profile->slots[slot].profile = profile; 107 list_add_tail(&profile->slots[slot].idle_slot_node, 108 &profile->idle_slots); 109 } 110 111 spin_lock_init(&profile->idle_slots_lock); 112 113 slot_hashtable_size = roundup_pow_of_two(num_slots); 114 /* 115 * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2 116 * buckets. This only makes a difference when there is only 1 keyslot. 117 */ 118 if (slot_hashtable_size < 2) 119 slot_hashtable_size = 2; 120 121 profile->log_slot_ht_size = ilog2(slot_hashtable_size); 122 profile->slot_hashtable = 123 kvmalloc_objs(profile->slot_hashtable[0], slot_hashtable_size); 124 if (!profile->slot_hashtable) 125 goto err_destroy; 126 for (i = 0; i < slot_hashtable_size; i++) 127 INIT_HLIST_HEAD(&profile->slot_hashtable[i]); 128 129 return 0; 130 131 err_destroy: 132 blk_crypto_profile_destroy(profile); 133 return -ENOMEM; 134 } 135 EXPORT_SYMBOL_GPL(blk_crypto_profile_init); 136 137 static void blk_crypto_profile_destroy_callback(void *profile) 138 { 139 blk_crypto_profile_destroy(profile); 140 } 141 142 /** 143 * devm_blk_crypto_profile_init() - Resource-managed blk_crypto_profile_init() 144 * @dev: the device which owns the blk_crypto_profile 145 * @profile: the blk_crypto_profile to initialize 146 * @num_slots: the number of keyslots 147 * 148 * Like blk_crypto_profile_init(), but causes blk_crypto_profile_destroy() to be 149 * called automatically on driver detach. 150 * 151 * Return: 0 on success, or else a negative error code. 152 */ 153 int devm_blk_crypto_profile_init(struct device *dev, 154 struct blk_crypto_profile *profile, 155 unsigned int num_slots) 156 { 157 int err = blk_crypto_profile_init(profile, num_slots); 158 159 if (err) 160 return err; 161 162 return devm_add_action_or_reset(dev, 163 blk_crypto_profile_destroy_callback, 164 profile); 165 } 166 EXPORT_SYMBOL_GPL(devm_blk_crypto_profile_init); 167 168 static inline struct hlist_head * 169 blk_crypto_hash_bucket_for_key(struct blk_crypto_profile *profile, 170 const struct blk_crypto_key *key) 171 { 172 return &profile->slot_hashtable[ 173 hash_ptr(key, profile->log_slot_ht_size)]; 174 } 175 176 static void 177 blk_crypto_remove_slot_from_lru_list(struct blk_crypto_keyslot *slot) 178 { 179 struct blk_crypto_profile *profile = slot->profile; 180 unsigned long flags; 181 182 spin_lock_irqsave(&profile->idle_slots_lock, flags); 183 list_del(&slot->idle_slot_node); 184 spin_unlock_irqrestore(&profile->idle_slots_lock, flags); 185 } 186 187 static struct blk_crypto_keyslot * 188 blk_crypto_find_keyslot(struct blk_crypto_profile *profile, 189 const struct blk_crypto_key *key) 190 { 191 const struct hlist_head *head = 192 blk_crypto_hash_bucket_for_key(profile, key); 193 struct blk_crypto_keyslot *slotp; 194 195 hlist_for_each_entry(slotp, head, hash_node) { 196 if (slotp->key == key) 197 return slotp; 198 } 199 return NULL; 200 } 201 202 static struct blk_crypto_keyslot * 203 blk_crypto_find_and_grab_keyslot(struct blk_crypto_profile *profile, 204 const struct blk_crypto_key *key) 205 { 206 struct blk_crypto_keyslot *slot; 207 208 slot = blk_crypto_find_keyslot(profile, key); 209 if (!slot) 210 return NULL; 211 if (atomic_inc_return(&slot->slot_refs) == 1) { 212 /* Took first reference to this slot; remove it from LRU list */ 213 blk_crypto_remove_slot_from_lru_list(slot); 214 } 215 return slot; 216 } 217 218 /** 219 * blk_crypto_keyslot_index() - Get the index of a keyslot 220 * @slot: a keyslot that blk_crypto_get_keyslot() returned 221 * 222 * Return: the 0-based index of the keyslot within the device's keyslots. 223 */ 224 unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot) 225 { 226 return slot - slot->profile->slots; 227 } 228 EXPORT_SYMBOL_GPL(blk_crypto_keyslot_index); 229 230 /** 231 * blk_crypto_get_keyslot() - Get a keyslot for a key, if needed. 232 * @profile: the crypto profile of the device the key will be used on 233 * @key: the key that will be used 234 * @slot_ptr: If a keyslot is allocated, an opaque pointer to the keyslot struct 235 * will be stored here. blk_crypto_put_keyslot() must be called 236 * later to release it. Otherwise, NULL will be stored here. 237 * 238 * If the device has keyslots, this gets a keyslot that's been programmed with 239 * the specified key. If the key is already in a slot, this reuses it; 240 * otherwise this waits for a slot to become idle and programs the key into it. 241 * 242 * Context: Process context. Takes and releases profile->lock. 243 * Return: BLK_STS_OK on success, meaning that either a keyslot was allocated or 244 * one wasn't needed; or a blk_status_t error on failure. 245 */ 246 blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, 247 const struct blk_crypto_key *key, 248 struct blk_crypto_keyslot **slot_ptr) 249 { 250 struct blk_crypto_keyslot *slot; 251 int slot_idx; 252 int err; 253 254 *slot_ptr = NULL; 255 256 /* 257 * If the device has no concept of "keyslots", then there is no need to 258 * get one. 259 */ 260 if (profile->num_slots == 0) 261 return BLK_STS_OK; 262 263 down_read(&profile->lock); 264 slot = blk_crypto_find_and_grab_keyslot(profile, key); 265 up_read(&profile->lock); 266 if (slot) 267 goto success; 268 269 for (;;) { 270 blk_crypto_hw_enter(profile); 271 slot = blk_crypto_find_and_grab_keyslot(profile, key); 272 if (slot) { 273 blk_crypto_hw_exit(profile); 274 goto success; 275 } 276 277 /* 278 * If we're here, that means there wasn't a slot that was 279 * already programmed with the key. So try to program it. 280 */ 281 if (!list_empty(&profile->idle_slots)) 282 break; 283 284 blk_crypto_hw_exit(profile); 285 wait_event(profile->idle_slots_wait_queue, 286 !list_empty(&profile->idle_slots)); 287 } 288 289 slot = list_first_entry(&profile->idle_slots, struct blk_crypto_keyslot, 290 idle_slot_node); 291 slot_idx = blk_crypto_keyslot_index(slot); 292 293 err = profile->ll_ops.keyslot_program(profile, key, slot_idx); 294 if (err) { 295 wake_up(&profile->idle_slots_wait_queue); 296 blk_crypto_hw_exit(profile); 297 return errno_to_blk_status(err); 298 } 299 300 /* Move this slot to the hash list for the new key. */ 301 if (slot->key) 302 hlist_del(&slot->hash_node); 303 slot->key = key; 304 hlist_add_head(&slot->hash_node, 305 blk_crypto_hash_bucket_for_key(profile, key)); 306 307 atomic_set(&slot->slot_refs, 1); 308 309 blk_crypto_remove_slot_from_lru_list(slot); 310 311 blk_crypto_hw_exit(profile); 312 success: 313 *slot_ptr = slot; 314 return BLK_STS_OK; 315 } 316 317 /** 318 * blk_crypto_put_keyslot() - Release a reference to a keyslot 319 * @slot: The keyslot to release the reference of 320 * 321 * Context: Any context. 322 */ 323 void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot) 324 { 325 struct blk_crypto_profile *profile = slot->profile; 326 unsigned long flags; 327 328 if (atomic_dec_and_lock_irqsave(&slot->slot_refs, 329 &profile->idle_slots_lock, flags)) { 330 list_add_tail(&slot->idle_slot_node, &profile->idle_slots); 331 spin_unlock_irqrestore(&profile->idle_slots_lock, flags); 332 wake_up(&profile->idle_slots_wait_queue); 333 } 334 } 335 336 /** 337 * __blk_crypto_cfg_supported() - Check whether the given crypto profile 338 * supports the given crypto configuration. 339 * @profile: the crypto profile to check 340 * @cfg: the crypto configuration to check for 341 * 342 * Return: %true if @profile supports the given @cfg. 343 */ 344 bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, 345 const struct blk_crypto_config *cfg) 346 { 347 if (!profile) 348 return false; 349 if (!(profile->modes_supported[cfg->crypto_mode] & cfg->data_unit_size)) 350 return false; 351 if (profile->max_dun_bytes_supported < cfg->dun_bytes) 352 return false; 353 if (!(profile->key_types_supported & cfg->key_type)) 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 */ 363 int __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)); 397 out_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; 404 out: 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 */ 418 void 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 } 439 EXPORT_SYMBOL_GPL(blk_crypto_reprogram_all_keys); 440 441 void 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 } 451 EXPORT_SYMBOL_GPL(blk_crypto_profile_destroy); 452 453 bool 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 } 463 EXPORT_SYMBOL_GPL(blk_crypto_register); 464 465 /** 466 * blk_crypto_derive_sw_secret() - Derive software secret from wrapped key 467 * @bdev: a block device that supports hardware-wrapped keys 468 * @eph_key: a hardware-wrapped key in ephemerally-wrapped form 469 * @eph_key_size: size of @eph_key in bytes 470 * @sw_secret: (output) the software secret 471 * 472 * Given a hardware-wrapped key in ephemerally-wrapped form (the same form that 473 * it is used for I/O), ask the hardware to derive the secret which software can 474 * use for cryptographic tasks other than inline encryption. This secret is 475 * guaranteed to be cryptographically isolated from the inline encryption key, 476 * i.e. derived with a different KDF context. 477 * 478 * Return: 0 on success, -EOPNOTSUPP if the block device doesn't support 479 * hardware-wrapped keys, -EBADMSG if the key isn't a valid 480 * ephemerally-wrapped key, or another -errno code. 481 */ 482 int blk_crypto_derive_sw_secret(struct block_device *bdev, 483 const u8 *eph_key, size_t eph_key_size, 484 u8 sw_secret[BLK_CRYPTO_SW_SECRET_SIZE]) 485 { 486 struct blk_crypto_profile *profile = 487 bdev_get_queue(bdev)->crypto_profile; 488 int err; 489 490 if (!profile) 491 return -EOPNOTSUPP; 492 if (!(profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED)) 493 return -EOPNOTSUPP; 494 if (!profile->ll_ops.derive_sw_secret) 495 return -EOPNOTSUPP; 496 blk_crypto_hw_enter(profile); 497 err = profile->ll_ops.derive_sw_secret(profile, eph_key, eph_key_size, 498 sw_secret); 499 blk_crypto_hw_exit(profile); 500 return err; 501 } 502 EXPORT_SYMBOL_GPL(blk_crypto_derive_sw_secret); 503 504 int blk_crypto_import_key(struct blk_crypto_profile *profile, 505 const u8 *raw_key, size_t raw_key_size, 506 u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]) 507 { 508 int ret; 509 510 if (!profile) 511 return -EOPNOTSUPP; 512 if (!(profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED)) 513 return -EOPNOTSUPP; 514 if (!profile->ll_ops.import_key) 515 return -EOPNOTSUPP; 516 blk_crypto_hw_enter(profile); 517 ret = profile->ll_ops.import_key(profile, raw_key, raw_key_size, 518 lt_key); 519 blk_crypto_hw_exit(profile); 520 return ret; 521 } 522 EXPORT_SYMBOL_GPL(blk_crypto_import_key); 523 524 int blk_crypto_generate_key(struct blk_crypto_profile *profile, 525 u8 lt_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]) 526 { 527 int ret; 528 529 if (!profile) 530 return -EOPNOTSUPP; 531 if (!(profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED)) 532 return -EOPNOTSUPP; 533 if (!profile->ll_ops.generate_key) 534 return -EOPNOTSUPP; 535 blk_crypto_hw_enter(profile); 536 ret = profile->ll_ops.generate_key(profile, lt_key); 537 blk_crypto_hw_exit(profile); 538 return ret; 539 } 540 EXPORT_SYMBOL_GPL(blk_crypto_generate_key); 541 542 int blk_crypto_prepare_key(struct blk_crypto_profile *profile, 543 const u8 *lt_key, size_t lt_key_size, 544 u8 eph_key[BLK_CRYPTO_MAX_HW_WRAPPED_KEY_SIZE]) 545 { 546 int ret; 547 548 if (!profile) 549 return -EOPNOTSUPP; 550 if (!(profile->key_types_supported & BLK_CRYPTO_KEY_TYPE_HW_WRAPPED)) 551 return -EOPNOTSUPP; 552 if (!profile->ll_ops.prepare_key) 553 return -EOPNOTSUPP; 554 blk_crypto_hw_enter(profile); 555 ret = profile->ll_ops.prepare_key(profile, lt_key, lt_key_size, 556 eph_key); 557 blk_crypto_hw_exit(profile); 558 return ret; 559 } 560 EXPORT_SYMBOL_GPL(blk_crypto_prepare_key); 561 562 /** 563 * blk_crypto_intersect_capabilities() - restrict supported crypto capabilities 564 * by child device 565 * @parent: the crypto profile for the parent device 566 * @child: the crypto profile for the child device, or NULL 567 * 568 * This clears all crypto capabilities in @parent that aren't set in @child. If 569 * @child is NULL, then this clears all parent capabilities. 570 * 571 * Only use this when setting up the crypto profile for a layered device, before 572 * it's been exposed yet. 573 */ 574 void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent, 575 const struct blk_crypto_profile *child) 576 { 577 if (child) { 578 unsigned int i; 579 580 parent->max_dun_bytes_supported = 581 min(parent->max_dun_bytes_supported, 582 child->max_dun_bytes_supported); 583 for (i = 0; i < ARRAY_SIZE(child->modes_supported); i++) 584 parent->modes_supported[i] &= child->modes_supported[i]; 585 parent->key_types_supported &= child->key_types_supported; 586 } else { 587 parent->max_dun_bytes_supported = 0; 588 memset(parent->modes_supported, 0, 589 sizeof(parent->modes_supported)); 590 parent->key_types_supported = 0; 591 } 592 } 593 EXPORT_SYMBOL_GPL(blk_crypto_intersect_capabilities); 594 595 /** 596 * blk_crypto_has_capabilities() - Check whether @target supports at least all 597 * the crypto capabilities that @reference does. 598 * @target: the target profile 599 * @reference: the reference profile 600 * 601 * Return: %true if @target supports all the crypto capabilities of @reference. 602 */ 603 bool blk_crypto_has_capabilities(const struct blk_crypto_profile *target, 604 const struct blk_crypto_profile *reference) 605 { 606 int i; 607 608 if (!reference) 609 return true; 610 611 if (!target) 612 return false; 613 614 for (i = 0; i < ARRAY_SIZE(target->modes_supported); i++) { 615 if (reference->modes_supported[i] & ~target->modes_supported[i]) 616 return false; 617 } 618 619 if (reference->max_dun_bytes_supported > 620 target->max_dun_bytes_supported) 621 return false; 622 623 if (reference->key_types_supported & ~target->key_types_supported) 624 return false; 625 626 return true; 627 } 628 EXPORT_SYMBOL_GPL(blk_crypto_has_capabilities); 629 630 /** 631 * blk_crypto_update_capabilities() - Update the capabilities of a crypto 632 * profile to match those of another crypto 633 * profile. 634 * @dst: The crypto profile whose capabilities to update. 635 * @src: The crypto profile whose capabilities this function will update @dst's 636 * capabilities to. 637 * 638 * Blk-crypto requires that crypto capabilities that were 639 * advertised when a bio was created continue to be supported by the 640 * device until that bio is ended. This is turn means that a device cannot 641 * shrink its advertised crypto capabilities without any explicit 642 * synchronization with upper layers. So if there's no such explicit 643 * synchronization, @src must support all the crypto capabilities that 644 * @dst does (i.e. we need blk_crypto_has_capabilities(@src, @dst)). 645 * 646 * Note also that as long as the crypto capabilities are being expanded, the 647 * order of updates becoming visible is not important because it's alright 648 * for blk-crypto to see stale values - they only cause blk-crypto to 649 * believe that a crypto capability isn't supported when it actually is (which 650 * might result in blk-crypto-fallback being used if available, or the bio being 651 * failed). 652 */ 653 void blk_crypto_update_capabilities(struct blk_crypto_profile *dst, 654 const struct blk_crypto_profile *src) 655 { 656 memcpy(dst->modes_supported, src->modes_supported, 657 sizeof(dst->modes_supported)); 658 659 dst->max_dun_bytes_supported = src->max_dun_bytes_supported; 660 dst->key_types_supported = src->key_types_supported; 661 } 662 EXPORT_SYMBOL_GPL(blk_crypto_update_capabilities); 663