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Diffstat (limited to 'block/keyslot-manager.c')
| -rw-r--r-- | block/keyslot-manager.c | 578 |
1 files changed, 0 insertions, 578 deletions
diff --git a/block/keyslot-manager.c b/block/keyslot-manager.c deleted file mode 100644 index 2c4a55bea6ca..000000000000 --- a/block/keyslot-manager.c +++ /dev/null @@ -1,578 +0,0 @@ -// 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; - 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); - kvfree_sensitive(ksm->slots, sizeof(ksm->slots[0]) * ksm->num_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_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]; - } - } else { - parent->max_dun_bytes_supported = 0; - memset(parent->crypto_modes_supported, 0, - sizeof(parent->crypto_modes_supported)); - } -} -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; - } - - 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; -} -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); |