block/blk-crypto-profile.c

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