| // SPDX-License-Identifier: GPL-2.0 |
| /* |
| * Copyright 2019 Google LLC |
| */ |
| |
| /** |
| * DOC: The Keyslot Manager |
| * |
| * Many devices with inline encryption support have a limited number of "slots" |
| * into which encryption contexts may be programmed, and requests can be tagged |
| * with a slot number to specify the key to use for en/decryption. |
| * |
| * As the number of slots is limited, and programming keys is expensive on |
| * many inline encryption hardware, we don't want to program the same key into |
| * multiple slots - if multiple requests are using the same key, we want to |
| * program just one slot with that key and use that slot for all requests. |
| * |
| * The keyslot manager manages these keyslots appropriately, and also acts as |
| * an abstraction between the inline encryption hardware and the upper layers. |
| * |
| * Lower layer devices will set up a keyslot manager in their request queue |
| * and tell it how to perform device specific operations like programming/ |
| * evicting keys from keyslots. |
| * |
| * Upper layers will call blk_ksm_get_slot_for_key() to program a |
| * key into some slot in the inline encryption hardware. |
| */ |
| |
| #define pr_fmt(fmt) "blk-crypto: " fmt |
| |
| #include <linux/keyslot-manager.h> |
| #include <linux/device.h> |
| #include <linux/atomic.h> |
| #include <linux/mutex.h> |
| #include <linux/pm_runtime.h> |
| #include <linux/wait.h> |
| #include <linux/blkdev.h> |
| |
| struct blk_ksm_keyslot { |
| atomic_t slot_refs; |
| struct list_head idle_slot_node; |
| struct hlist_node hash_node; |
| const struct blk_crypto_key *key; |
| struct blk_keyslot_manager *ksm; |
| }; |
| |
| static inline void blk_ksm_hw_enter(struct blk_keyslot_manager *ksm) |
| { |
| /* |
| * Calling into the driver requires ksm->lock held and the device |
| * resumed. But we must resume the device first, since that can acquire |
| * and release ksm->lock via blk_ksm_reprogram_all_keys(). |
| */ |
| if (ksm->dev) |
| pm_runtime_get_sync(ksm->dev); |
| down_write(&ksm->lock); |
| } |
| |
| static inline void blk_ksm_hw_exit(struct blk_keyslot_manager *ksm) |
| { |
| up_write(&ksm->lock); |
| if (ksm->dev) |
| pm_runtime_put_sync(ksm->dev); |
| } |
| |
| static inline bool blk_ksm_is_passthrough(struct blk_keyslot_manager *ksm) |
| { |
| return ksm->num_slots == 0; |
| } |
| |
| /** |
| * blk_ksm_init() - Initialize a keyslot manager |
| * @ksm: The keyslot_manager to initialize. |
| * @num_slots: The number of key slots to manage. |
| * |
| * Allocate memory for keyslots and initialize a keyslot manager. Called by |
| * e.g. storage drivers to set up a keyslot manager in their request_queue. |
| * |
| * Return: 0 on success, or else a negative error code. |
| */ |
| int blk_ksm_init(struct blk_keyslot_manager *ksm, unsigned int num_slots) |
| { |
| unsigned int slot; |
| unsigned int i; |
| unsigned int slot_hashtable_size; |
| |
| memset(ksm, 0, sizeof(*ksm)); |
| |
| if (num_slots == 0) |
| return -EINVAL; |
| |
| ksm->slots = kvcalloc(num_slots, sizeof(ksm->slots[0]), GFP_KERNEL); |
| if (!ksm->slots) |
| return -ENOMEM; |
| |
| ksm->num_slots = num_slots; |
| |
| init_rwsem(&ksm->lock); |
| |
| init_waitqueue_head(&ksm->idle_slots_wait_queue); |
| INIT_LIST_HEAD(&ksm->idle_slots); |
| |
| for (slot = 0; slot < num_slots; slot++) { |
| ksm->slots[slot].ksm = ksm; |
| list_add_tail(&ksm->slots[slot].idle_slot_node, |
| &ksm->idle_slots); |
| } |
| |
| spin_lock_init(&ksm->idle_slots_lock); |
| |
| slot_hashtable_size = roundup_pow_of_two(num_slots); |
| /* |
| * hash_ptr() assumes bits != 0, so ensure the hash table has at least 2 |
| * buckets. This only makes a difference when there is only 1 keyslot. |
| */ |
| if (slot_hashtable_size < 2) |
| slot_hashtable_size = 2; |
| |
| ksm->log_slot_ht_size = ilog2(slot_hashtable_size); |
| ksm->slot_hashtable = kvmalloc_array(slot_hashtable_size, |
| sizeof(ksm->slot_hashtable[0]), |
| GFP_KERNEL); |
| if (!ksm->slot_hashtable) |
| goto err_destroy_ksm; |
| for (i = 0; i < slot_hashtable_size; i++) |
| INIT_HLIST_HEAD(&ksm->slot_hashtable[i]); |
| |
| return 0; |
| |
| err_destroy_ksm: |
| blk_ksm_destroy(ksm); |
| return -ENOMEM; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_init); |
| |
| static void blk_ksm_destroy_callback(void *ksm) |
| { |
| blk_ksm_destroy(ksm); |
| } |
| |
| /** |
| * devm_blk_ksm_init() - Resource-managed blk_ksm_init() |
| * @dev: The device which owns the blk_keyslot_manager. |
| * @ksm: The blk_keyslot_manager to initialize. |
| * @num_slots: The number of key slots to manage. |
| * |
| * Like blk_ksm_init(), but causes blk_ksm_destroy() to be called automatically |
| * on driver detach. |
| * |
| * Return: 0 on success, or else a negative error code. |
| */ |
| int devm_blk_ksm_init(struct device *dev, struct blk_keyslot_manager *ksm, |
| unsigned int num_slots) |
| { |
| int err = blk_ksm_init(ksm, num_slots); |
| |
| if (err) |
| return err; |
| |
| return devm_add_action_or_reset(dev, blk_ksm_destroy_callback, ksm); |
| } |
| EXPORT_SYMBOL_GPL(devm_blk_ksm_init); |
| |
| static inline struct hlist_head * |
| blk_ksm_hash_bucket_for_key(struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_key *key) |
| { |
| return &ksm->slot_hashtable[hash_ptr(key, ksm->log_slot_ht_size)]; |
| } |
| |
| static void blk_ksm_remove_slot_from_lru_list(struct blk_ksm_keyslot *slot) |
| { |
| struct blk_keyslot_manager *ksm = slot->ksm; |
| unsigned long flags; |
| |
| spin_lock_irqsave(&ksm->idle_slots_lock, flags); |
| list_del(&slot->idle_slot_node); |
| spin_unlock_irqrestore(&ksm->idle_slots_lock, flags); |
| } |
| |
| static struct blk_ksm_keyslot *blk_ksm_find_keyslot( |
| struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_key *key) |
| { |
| const struct hlist_head *head = blk_ksm_hash_bucket_for_key(ksm, key); |
| struct blk_ksm_keyslot *slotp; |
| |
| hlist_for_each_entry(slotp, head, hash_node) { |
| if (slotp->key == key) |
| return slotp; |
| } |
| return NULL; |
| } |
| |
| static struct blk_ksm_keyslot *blk_ksm_find_and_grab_keyslot( |
| struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_key *key) |
| { |
| struct blk_ksm_keyslot *slot; |
| |
| slot = blk_ksm_find_keyslot(ksm, key); |
| if (!slot) |
| return NULL; |
| if (atomic_inc_return(&slot->slot_refs) == 1) { |
| /* Took first reference to this slot; remove it from LRU list */ |
| blk_ksm_remove_slot_from_lru_list(slot); |
| } |
| return slot; |
| } |
| |
| unsigned int blk_ksm_get_slot_idx(struct blk_ksm_keyslot *slot) |
| { |
| return slot - slot->ksm->slots; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_get_slot_idx); |
| |
| /** |
| * blk_ksm_get_slot_for_key() - Program a key into a keyslot. |
| * @ksm: The keyslot manager to program the key into. |
| * @key: Pointer to the key object to program, including the raw key, crypto |
| * mode, and data unit size. |
| * @slot_ptr: A pointer to return the pointer of the allocated keyslot. |
| * |
| * Get a keyslot that's been programmed with the specified key. If one already |
| * exists, return it with incremented refcount. Otherwise, wait for a keyslot |
| * to become idle and program it. |
| * |
| * Context: Process context. Takes and releases ksm->lock. |
| * Return: BLK_STS_OK on success (and keyslot is set to the pointer of the |
| * allocated keyslot), or some other blk_status_t otherwise (and |
| * keyslot is set to NULL). |
| */ |
| blk_status_t blk_ksm_get_slot_for_key(struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_key *key, |
| struct blk_ksm_keyslot **slot_ptr) |
| { |
| struct blk_ksm_keyslot *slot; |
| int slot_idx; |
| int err; |
| |
| *slot_ptr = NULL; |
| |
| if (blk_ksm_is_passthrough(ksm)) |
| return BLK_STS_OK; |
| |
| down_read(&ksm->lock); |
| slot = blk_ksm_find_and_grab_keyslot(ksm, key); |
| up_read(&ksm->lock); |
| if (slot) |
| goto success; |
| |
| for (;;) { |
| blk_ksm_hw_enter(ksm); |
| slot = blk_ksm_find_and_grab_keyslot(ksm, key); |
| if (slot) { |
| blk_ksm_hw_exit(ksm); |
| goto success; |
| } |
| |
| /* |
| * If we're here, that means there wasn't a slot that was |
| * already programmed with the key. So try to program it. |
| */ |
| if (!list_empty(&ksm->idle_slots)) |
| break; |
| |
| blk_ksm_hw_exit(ksm); |
| wait_event(ksm->idle_slots_wait_queue, |
| !list_empty(&ksm->idle_slots)); |
| } |
| |
| slot = list_first_entry(&ksm->idle_slots, struct blk_ksm_keyslot, |
| idle_slot_node); |
| slot_idx = blk_ksm_get_slot_idx(slot); |
| |
| err = ksm->ksm_ll_ops.keyslot_program(ksm, key, slot_idx); |
| if (err) { |
| wake_up(&ksm->idle_slots_wait_queue); |
| blk_ksm_hw_exit(ksm); |
| return errno_to_blk_status(err); |
| } |
| |
| /* Move this slot to the hash list for the new key. */ |
| if (slot->key) |
| hlist_del(&slot->hash_node); |
| slot->key = key; |
| hlist_add_head(&slot->hash_node, blk_ksm_hash_bucket_for_key(ksm, key)); |
| |
| atomic_set(&slot->slot_refs, 1); |
| |
| blk_ksm_remove_slot_from_lru_list(slot); |
| |
| blk_ksm_hw_exit(ksm); |
| success: |
| *slot_ptr = slot; |
| return BLK_STS_OK; |
| } |
| |
| /** |
| * blk_ksm_put_slot() - Release a reference to a slot |
| * @slot: The keyslot to release the reference of. |
| * |
| * Context: Any context. |
| */ |
| void blk_ksm_put_slot(struct blk_ksm_keyslot *slot) |
| { |
| struct blk_keyslot_manager *ksm; |
| unsigned long flags; |
| |
| if (!slot) |
| return; |
| |
| ksm = slot->ksm; |
| |
| if (atomic_dec_and_lock_irqsave(&slot->slot_refs, |
| &ksm->idle_slots_lock, flags)) { |
| list_add_tail(&slot->idle_slot_node, &ksm->idle_slots); |
| spin_unlock_irqrestore(&ksm->idle_slots_lock, flags); |
| wake_up(&ksm->idle_slots_wait_queue); |
| } |
| } |
| |
| /** |
| * blk_ksm_crypto_cfg_supported() - Find out if a crypto configuration is |
| * supported by a ksm. |
| * @ksm: The keyslot manager to check |
| * @cfg: The crypto configuration to check for. |
| * |
| * Checks for crypto_mode/data unit size/dun bytes support. |
| * |
| * Return: Whether or not this ksm supports the specified crypto config. |
| */ |
| bool blk_ksm_crypto_cfg_supported(struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_config *cfg) |
| { |
| if (!ksm) |
| return false; |
| if (!(ksm->crypto_modes_supported[cfg->crypto_mode] & |
| cfg->data_unit_size)) |
| return false; |
| if (ksm->max_dun_bytes_supported < cfg->dun_bytes) |
| return false; |
| if (cfg->is_hw_wrapped) { |
| if (!(ksm->features & BLK_CRYPTO_FEATURE_WRAPPED_KEYS)) |
| return false; |
| } else { |
| if (!(ksm->features & BLK_CRYPTO_FEATURE_STANDARD_KEYS)) |
| return false; |
| } |
| return true; |
| } |
| |
| /** |
| * blk_ksm_evict_key() - Evict a key from the lower layer device. |
| * @ksm: The keyslot manager to evict from |
| * @key: The key to evict |
| * |
| * Find the keyslot that the specified key was programmed into, and evict that |
| * slot from the lower layer device. The slot must not be in use by any |
| * in-flight IO when this function is called. |
| * |
| * Context: Process context. Takes and releases ksm->lock. |
| * Return: 0 on success or if there's no keyslot with the specified key, -EBUSY |
| * if the keyslot is still in use, or another -errno value on other |
| * error. |
| */ |
| int blk_ksm_evict_key(struct blk_keyslot_manager *ksm, |
| const struct blk_crypto_key *key) |
| { |
| struct blk_ksm_keyslot *slot; |
| int err = 0; |
| |
| if (blk_ksm_is_passthrough(ksm)) { |
| if (ksm->ksm_ll_ops.keyslot_evict) { |
| blk_ksm_hw_enter(ksm); |
| err = ksm->ksm_ll_ops.keyslot_evict(ksm, key, -1); |
| blk_ksm_hw_exit(ksm); |
| return err; |
| } |
| return 0; |
| } |
| |
| blk_ksm_hw_enter(ksm); |
| slot = blk_ksm_find_keyslot(ksm, key); |
| if (!slot) |
| goto out_unlock; |
| |
| if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) { |
| err = -EBUSY; |
| goto out_unlock; |
| } |
| err = ksm->ksm_ll_ops.keyslot_evict(ksm, key, |
| blk_ksm_get_slot_idx(slot)); |
| if (err) |
| goto out_unlock; |
| |
| hlist_del(&slot->hash_node); |
| slot->key = NULL; |
| err = 0; |
| out_unlock: |
| blk_ksm_hw_exit(ksm); |
| return err; |
| } |
| |
| /** |
| * blk_ksm_reprogram_all_keys() - Re-program all keyslots. |
| * @ksm: The keyslot manager |
| * |
| * Re-program all keyslots that are supposed to have a key programmed. This is |
| * intended only for use by drivers for hardware that loses its keys on reset. |
| * |
| * Context: Process context. Takes and releases ksm->lock. |
| */ |
| void blk_ksm_reprogram_all_keys(struct blk_keyslot_manager *ksm) |
| { |
| unsigned int slot; |
| |
| if (blk_ksm_is_passthrough(ksm)) |
| return; |
| |
| /* This is for device initialization, so don't resume the device */ |
| down_write(&ksm->lock); |
| for (slot = 0; slot < ksm->num_slots; slot++) { |
| const struct blk_crypto_key *key = ksm->slots[slot].key; |
| int err; |
| |
| if (!key) |
| continue; |
| |
| err = ksm->ksm_ll_ops.keyslot_program(ksm, key, slot); |
| WARN_ON(err); |
| } |
| up_write(&ksm->lock); |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_reprogram_all_keys); |
| |
| void blk_ksm_destroy(struct blk_keyslot_manager *ksm) |
| { |
| if (!ksm) |
| return; |
| kvfree(ksm->slot_hashtable); |
| memzero_explicit(ksm->slots, sizeof(ksm->slots[0]) * ksm->num_slots); |
| kvfree(ksm->slots); |
| memzero_explicit(ksm, sizeof(*ksm)); |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_destroy); |
| |
| bool blk_ksm_register(struct blk_keyslot_manager *ksm, struct request_queue *q) |
| { |
| if (blk_integrity_queue_supports_integrity(q)) { |
| pr_warn("Integrity and hardware inline encryption are not supported together. Disabling hardware inline encryption.\n"); |
| return false; |
| } |
| q->ksm = ksm; |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_register); |
| |
| void blk_ksm_unregister(struct request_queue *q) |
| { |
| q->ksm = NULL; |
| } |
| |
| /** |
| * blk_ksm_derive_raw_secret() - Derive software secret from wrapped key |
| * @ksm: The keyslot manager |
| * @wrapped_key: The wrapped key |
| * @wrapped_key_size: Size of the wrapped key in bytes |
| * @secret: (output) the software secret |
| * @secret_size: (output) the number of secret bytes to derive |
| * |
| * Given a hardware-wrapped key, ask the hardware to derive a secret which |
| * software can use for cryptographic tasks other than inline encryption. The |
| * derived secret is guaranteed to be cryptographically isolated from the key |
| * with which any inline encryption with this wrapped key would actually be |
| * done. I.e., both will be derived from the unwrapped key. |
| * |
| * Return: 0 on success, -EOPNOTSUPP if hardware-wrapped keys are unsupported, |
| * or another -errno code. |
| */ |
| int blk_ksm_derive_raw_secret(struct blk_keyslot_manager *ksm, |
| const u8 *wrapped_key, |
| unsigned int wrapped_key_size, |
| u8 *secret, unsigned int secret_size) |
| { |
| int err; |
| |
| if (ksm->ksm_ll_ops.derive_raw_secret) { |
| blk_ksm_hw_enter(ksm); |
| err = ksm->ksm_ll_ops.derive_raw_secret(ksm, wrapped_key, |
| wrapped_key_size, |
| secret, secret_size); |
| blk_ksm_hw_exit(ksm); |
| } else { |
| err = -EOPNOTSUPP; |
| } |
| |
| return err; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_derive_raw_secret); |
| |
| /** |
| * blk_ksm_intersect_modes() - restrict supported modes by child device |
| * @parent: The keyslot manager for parent device |
| * @child: The keyslot manager for child device, or NULL |
| * |
| * Clear any crypto mode support bits in @parent that aren't set in @child. |
| * If @child is NULL, then all parent bits are cleared. |
| * |
| * Only use this when setting up the keyslot manager for a layered device, |
| * before it's been exposed yet. |
| */ |
| void blk_ksm_intersect_modes(struct blk_keyslot_manager *parent, |
| const struct blk_keyslot_manager *child) |
| { |
| if (child) { |
| unsigned int i; |
| |
| parent->max_dun_bytes_supported = |
| min(parent->max_dun_bytes_supported, |
| child->max_dun_bytes_supported); |
| for (i = 0; i < ARRAY_SIZE(child->crypto_modes_supported); |
| i++) { |
| parent->crypto_modes_supported[i] &= |
| child->crypto_modes_supported[i]; |
| } |
| parent->features &= child->features; |
| } else { |
| parent->max_dun_bytes_supported = 0; |
| memset(parent->crypto_modes_supported, 0, |
| sizeof(parent->crypto_modes_supported)); |
| parent->features = 0; |
| } |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_intersect_modes); |
| |
| /** |
| * blk_ksm_is_superset() - Check if a KSM supports a superset of crypto modes |
| * and DUN bytes that another KSM supports. Here, |
| * "superset" refers to the mathematical meaning of the |
| * word - i.e. if two KSMs have the *same* capabilities, |
| * they *are* considered supersets of each other. |
| * @ksm_superset: The KSM that we want to verify is a superset |
| * @ksm_subset: The KSM that we want to verify is a subset |
| * |
| * Return: True if @ksm_superset supports a superset of the crypto modes and DUN |
| * bytes that @ksm_subset supports. |
| */ |
| bool blk_ksm_is_superset(struct blk_keyslot_manager *ksm_superset, |
| struct blk_keyslot_manager *ksm_subset) |
| { |
| int i; |
| |
| if (!ksm_subset) |
| return true; |
| |
| if (!ksm_superset) |
| return false; |
| |
| for (i = 0; i < ARRAY_SIZE(ksm_superset->crypto_modes_supported); i++) { |
| if (ksm_subset->crypto_modes_supported[i] & |
| (~ksm_superset->crypto_modes_supported[i])) { |
| return false; |
| } |
| } |
| |
| if (ksm_subset->max_dun_bytes_supported > |
| ksm_superset->max_dun_bytes_supported) { |
| return false; |
| } |
| |
| if (ksm_subset->features & ~ksm_superset->features) |
| return false; |
| |
| return true; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_is_superset); |
| |
| /** |
| * blk_ksm_update_capabilities() - Update the restrictions of a KSM to those of |
| * another KSM |
| * @target_ksm: The KSM whose restrictions to update. |
| * @reference_ksm: The KSM to whose restrictions this function will update |
| * @target_ksm's restrictions to. |
| * |
| * Blk-crypto requires that crypto capabilities that were |
| * advertised when a bio was created continue to be supported by the |
| * device until that bio is ended. This is turn means that a device cannot |
| * shrink its advertised crypto capabilities without any explicit |
| * synchronization with upper layers. So if there's no such explicit |
| * synchronization, @reference_ksm must support all the crypto capabilities that |
| * @target_ksm does |
| * (i.e. we need blk_ksm_is_superset(@reference_ksm, @target_ksm) == true). |
| * |
| * Note also that as long as the crypto capabilities are being expanded, the |
| * order of updates becoming visible is not important because it's alright |
| * for blk-crypto to see stale values - they only cause blk-crypto to |
| * believe that a crypto capability isn't supported when it actually is (which |
| * might result in blk-crypto-fallback being used if available, or the bio being |
| * failed). |
| */ |
| void blk_ksm_update_capabilities(struct blk_keyslot_manager *target_ksm, |
| struct blk_keyslot_manager *reference_ksm) |
| { |
| memcpy(target_ksm->crypto_modes_supported, |
| reference_ksm->crypto_modes_supported, |
| sizeof(target_ksm->crypto_modes_supported)); |
| |
| target_ksm->max_dun_bytes_supported = |
| reference_ksm->max_dun_bytes_supported; |
| |
| target_ksm->features = reference_ksm->features; |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_update_capabilities); |
| |
| /** |
| * blk_ksm_init_passthrough() - Init a passthrough keyslot manager |
| * @ksm: The keyslot manager to init |
| * |
| * Initialize a passthrough keyslot manager. |
| * Called by e.g. storage drivers to set up a keyslot manager in their |
| * request_queue, when the storage driver wants to manage its keys by itself. |
| * This is useful for inline encryption hardware that doesn't have the concept |
| * of keyslots, and for layered devices. |
| */ |
| void blk_ksm_init_passthrough(struct blk_keyslot_manager *ksm) |
| { |
| memset(ksm, 0, sizeof(*ksm)); |
| init_rwsem(&ksm->lock); |
| } |
| EXPORT_SYMBOL_GPL(blk_ksm_init_passthrough); |