diff options
Diffstat (limited to 'block/blk-crypto-profile.c')
| -rw-r--r-- | block/blk-crypto-profile.c | 565 |
1 files changed, 565 insertions, 0 deletions
diff --git a/block/blk-crypto-profile.c b/block/blk-crypto-profile.c new file mode 100644 index 000000000..aa7fc1436 --- /dev/null +++ b/block/blk-crypto-profile.c @@ -0,0 +1,565 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2019 Google LLC + */ + +/** + * DOC: blk-crypto profiles + * + * 'struct blk_crypto_profile' contains all generic inline encryption-related + * state for a particular inline encryption device. blk_crypto_profile serves + * as the way that drivers for inline encryption hardware expose their crypto + * capabilities and certain functions (e.g., functions to program and evict + * keys) to upper layers. Device drivers that want to support inline encryption + * construct a crypto profile, then associate it with the disk's request_queue. + * + * If the device has keyslots, then its blk_crypto_profile also handles managing + * these keyslots in a device-independent way, using the driver-provided + * functions to program and evict keys as needed. This includes keeping track + * of which key and how many I/O requests are using each keyslot, getting + * keyslots for I/O requests, and handling key eviction requests. + * + * For more information, see Documentation/block/inline-encryption.rst. + */ + +#define pr_fmt(fmt) "blk-crypto: " fmt + +#include <linux/blk-crypto-profile.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> +#include <linux/blk-integrity.h> +#include "blk-crypto-internal.h" + +struct blk_crypto_keyslot { + atomic_t slot_refs; + struct list_head idle_slot_node; + struct hlist_node hash_node; + const struct blk_crypto_key *key; + struct blk_crypto_profile *profile; +}; + +static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile) +{ + /* + * Calling into the driver requires profile->lock held and the device + * resumed. But we must resume the device first, since that can acquire + * and release profile->lock via blk_crypto_reprogram_all_keys(). + */ + if (profile->dev) + pm_runtime_get_sync(profile->dev); + down_write(&profile->lock); +} + +static inline void blk_crypto_hw_exit(struct blk_crypto_profile *profile) +{ + up_write(&profile->lock); + if (profile->dev) + pm_runtime_put_sync(profile->dev); +} + +/** + * blk_crypto_profile_init() - Initialize a blk_crypto_profile + * @profile: the blk_crypto_profile to initialize + * @num_slots: the number of keyslots + * + * Storage drivers must call this when starting to set up a blk_crypto_profile, + * before filling in additional fields. + * + * Return: 0 on success, or else a negative error code. + */ +int blk_crypto_profile_init(struct blk_crypto_profile *profile, + unsigned int num_slots) +{ + unsigned int slot; + unsigned int i; + unsigned int slot_hashtable_size; + + memset(profile, 0, sizeof(*profile)); + + /* + * profile->lock of an underlying device can nest inside profile->lock + * of a device-mapper device, so use a dynamic lock class to avoid + * false-positive lockdep reports. + */ + lockdep_register_key(&profile->lockdep_key); + __init_rwsem(&profile->lock, "&profile->lock", &profile->lockdep_key); + + if (num_slots == 0) + return 0; + + /* Initialize keyslot management data. */ + + profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]), + GFP_KERNEL); + if (!profile->slots) + goto err_destroy; + + profile->num_slots = num_slots; + + init_waitqueue_head(&profile->idle_slots_wait_queue); + INIT_LIST_HEAD(&profile->idle_slots); + + for (slot = 0; slot < num_slots; slot++) { + profile->slots[slot].profile = profile; + list_add_tail(&profile->slots[slot].idle_slot_node, + &profile->idle_slots); + } + + spin_lock_init(&profile->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; + + profile->log_slot_ht_size = ilog2(slot_hashtable_size); + profile->slot_hashtable = + kvmalloc_array(slot_hashtable_size, + sizeof(profile->slot_hashtable[0]), GFP_KERNEL); + if (!profile->slot_hashtable) + goto err_destroy; + for (i = 0; i < slot_hashtable_size; i++) + INIT_HLIST_HEAD(&profile->slot_hashtable[i]); + + return 0; + +err_destroy: + blk_crypto_profile_destroy(profile); + return -ENOMEM; +} +EXPORT_SYMBOL_GPL(blk_crypto_profile_init); + +static void blk_crypto_profile_destroy_callback(void *profile) +{ + blk_crypto_profile_destroy(profile); +} + +/** + * devm_blk_crypto_profile_init() - Resource-managed blk_crypto_profile_init() + * @dev: the device which owns the blk_crypto_profile + * @profile: the blk_crypto_profile to initialize + * @num_slots: the number of keyslots + * + * Like blk_crypto_profile_init(), but causes blk_crypto_profile_destroy() to be + * called automatically on driver detach. + * + * Return: 0 on success, or else a negative error code. + */ +int devm_blk_crypto_profile_init(struct device *dev, + struct blk_crypto_profile *profile, + unsigned int num_slots) +{ + int err = blk_crypto_profile_init(profile, num_slots); + + if (err) + return err; + + return devm_add_action_or_reset(dev, + blk_crypto_profile_destroy_callback, + profile); +} +EXPORT_SYMBOL_GPL(devm_blk_crypto_profile_init); + +static inline struct hlist_head * +blk_crypto_hash_bucket_for_key(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key) +{ + return &profile->slot_hashtable[ + hash_ptr(key, profile->log_slot_ht_size)]; +} + +static void +blk_crypto_remove_slot_from_lru_list(struct blk_crypto_keyslot *slot) +{ + struct blk_crypto_profile *profile = slot->profile; + unsigned long flags; + + spin_lock_irqsave(&profile->idle_slots_lock, flags); + list_del(&slot->idle_slot_node); + spin_unlock_irqrestore(&profile->idle_slots_lock, flags); +} + +static struct blk_crypto_keyslot * +blk_crypto_find_keyslot(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key) +{ + const struct hlist_head *head = + blk_crypto_hash_bucket_for_key(profile, key); + struct blk_crypto_keyslot *slotp; + + hlist_for_each_entry(slotp, head, hash_node) { + if (slotp->key == key) + return slotp; + } + return NULL; +} + +static struct blk_crypto_keyslot * +blk_crypto_find_and_grab_keyslot(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key) +{ + struct blk_crypto_keyslot *slot; + + slot = blk_crypto_find_keyslot(profile, 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_crypto_remove_slot_from_lru_list(slot); + } + return slot; +} + +/** + * blk_crypto_keyslot_index() - Get the index of a keyslot + * @slot: a keyslot that blk_crypto_get_keyslot() returned + * + * Return: the 0-based index of the keyslot within the device's keyslots. + */ +unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot) +{ + return slot - slot->profile->slots; +} +EXPORT_SYMBOL_GPL(blk_crypto_keyslot_index); + +/** + * blk_crypto_get_keyslot() - Get a keyslot for a key, if needed. + * @profile: the crypto profile of the device the key will be used on + * @key: the key that will be used + * @slot_ptr: If a keyslot is allocated, an opaque pointer to the keyslot struct + * will be stored here; otherwise NULL will be stored here. + * + * If the device has keyslots, this gets a keyslot that's been programmed with + * the specified key. If the key is already in a slot, this reuses it; + * otherwise this waits for a slot to become idle and programs the key into it. + * + * This must be paired with a call to blk_crypto_put_keyslot(). + * + * Context: Process context. Takes and releases profile->lock. + * Return: BLK_STS_OK on success, meaning that either a keyslot was allocated or + * one wasn't needed; or a blk_status_t error on failure. + */ +blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key, + struct blk_crypto_keyslot **slot_ptr) +{ + struct blk_crypto_keyslot *slot; + int slot_idx; + int err; + + *slot_ptr = NULL; + + /* + * If the device has no concept of "keyslots", then there is no need to + * get one. + */ + if (profile->num_slots == 0) + return BLK_STS_OK; + + down_read(&profile->lock); + slot = blk_crypto_find_and_grab_keyslot(profile, key); + up_read(&profile->lock); + if (slot) + goto success; + + for (;;) { + blk_crypto_hw_enter(profile); + slot = blk_crypto_find_and_grab_keyslot(profile, key); + if (slot) { + blk_crypto_hw_exit(profile); + 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(&profile->idle_slots)) + break; + + blk_crypto_hw_exit(profile); + wait_event(profile->idle_slots_wait_queue, + !list_empty(&profile->idle_slots)); + } + + slot = list_first_entry(&profile->idle_slots, struct blk_crypto_keyslot, + idle_slot_node); + slot_idx = blk_crypto_keyslot_index(slot); + + err = profile->ll_ops.keyslot_program(profile, key, slot_idx); + if (err) { + wake_up(&profile->idle_slots_wait_queue); + blk_crypto_hw_exit(profile); + 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_crypto_hash_bucket_for_key(profile, key)); + + atomic_set(&slot->slot_refs, 1); + + blk_crypto_remove_slot_from_lru_list(slot); + + blk_crypto_hw_exit(profile); +success: + *slot_ptr = slot; + return BLK_STS_OK; +} + +/** + * blk_crypto_put_keyslot() - Release a reference to a keyslot + * @slot: The keyslot to release the reference of (may be NULL). + * + * Context: Any context. + */ +void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot) +{ + struct blk_crypto_profile *profile; + unsigned long flags; + + if (!slot) + return; + + profile = slot->profile; + + if (atomic_dec_and_lock_irqsave(&slot->slot_refs, + &profile->idle_slots_lock, flags)) { + list_add_tail(&slot->idle_slot_node, &profile->idle_slots); + spin_unlock_irqrestore(&profile->idle_slots_lock, flags); + wake_up(&profile->idle_slots_wait_queue); + } +} + +/** + * __blk_crypto_cfg_supported() - Check whether the given crypto profile + * supports the given crypto configuration. + * @profile: the crypto profile to check + * @cfg: the crypto configuration to check for + * + * Return: %true if @profile supports the given @cfg. + */ +bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, + const struct blk_crypto_config *cfg) +{ + if (!profile) + return false; + if (!(profile->modes_supported[cfg->crypto_mode] & cfg->data_unit_size)) + return false; + if (profile->max_dun_bytes_supported < cfg->dun_bytes) + return false; + return true; +} + +/* + * This is an internal function that evicts a key from an inline encryption + * device that can be either a real device or the blk-crypto-fallback "device". + * It is used only by blk_crypto_evict_key(); see that function for details. + */ +int __blk_crypto_evict_key(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key) +{ + struct blk_crypto_keyslot *slot; + int err; + + if (profile->num_slots == 0) { + if (profile->ll_ops.keyslot_evict) { + blk_crypto_hw_enter(profile); + err = profile->ll_ops.keyslot_evict(profile, key, -1); + blk_crypto_hw_exit(profile); + return err; + } + return 0; + } + + blk_crypto_hw_enter(profile); + slot = blk_crypto_find_keyslot(profile, key); + if (!slot) { + /* + * Not an error, since a key not in use by I/O is not guaranteed + * to be in a keyslot. There can be more keys than keyslots. + */ + err = 0; + goto out; + } + + if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) { + /* BUG: key is still in use by I/O */ + err = -EBUSY; + goto out_remove; + } + err = profile->ll_ops.keyslot_evict(profile, key, + blk_crypto_keyslot_index(slot)); +out_remove: + /* + * Callers free the key even on error, so unlink the key from the hash + * table and clear slot->key even on error. + */ + hlist_del(&slot->hash_node); + slot->key = NULL; +out: + blk_crypto_hw_exit(profile); + return err; +} + +/** + * blk_crypto_reprogram_all_keys() - Re-program all keyslots. + * @profile: The crypto profile + * + * 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 profile->lock. + */ +void blk_crypto_reprogram_all_keys(struct blk_crypto_profile *profile) +{ + unsigned int slot; + + if (profile->num_slots == 0) + return; + + /* This is for device initialization, so don't resume the device */ + down_write(&profile->lock); + for (slot = 0; slot < profile->num_slots; slot++) { + const struct blk_crypto_key *key = profile->slots[slot].key; + int err; + + if (!key) + continue; + + err = profile->ll_ops.keyslot_program(profile, key, slot); + WARN_ON(err); + } + up_write(&profile->lock); +} +EXPORT_SYMBOL_GPL(blk_crypto_reprogram_all_keys); + +void blk_crypto_profile_destroy(struct blk_crypto_profile *profile) +{ + if (!profile) + return; + lockdep_unregister_key(&profile->lockdep_key); + kvfree(profile->slot_hashtable); + kvfree_sensitive(profile->slots, + sizeof(profile->slots[0]) * profile->num_slots); + memzero_explicit(profile, sizeof(*profile)); +} +EXPORT_SYMBOL_GPL(blk_crypto_profile_destroy); + +bool blk_crypto_register(struct blk_crypto_profile *profile, + 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->crypto_profile = profile; + return true; +} +EXPORT_SYMBOL_GPL(blk_crypto_register); + +/** + * blk_crypto_intersect_capabilities() - restrict supported crypto capabilities + * by child device + * @parent: the crypto profile for the parent device + * @child: the crypto profile for the child device, or NULL + * + * This clears all crypto capabilities in @parent that aren't set in @child. If + * @child is NULL, then this clears all parent capabilities. + * + * Only use this when setting up the crypto profile for a layered device, before + * it's been exposed yet. + */ +void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent, + const struct blk_crypto_profile *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->modes_supported); i++) + parent->modes_supported[i] &= child->modes_supported[i]; + } else { + parent->max_dun_bytes_supported = 0; + memset(parent->modes_supported, 0, + sizeof(parent->modes_supported)); + } +} +EXPORT_SYMBOL_GPL(blk_crypto_intersect_capabilities); + +/** + * blk_crypto_has_capabilities() - Check whether @target supports at least all + * the crypto capabilities that @reference does. + * @target: the target profile + * @reference: the reference profile + * + * Return: %true if @target supports all the crypto capabilities of @reference. + */ +bool blk_crypto_has_capabilities(const struct blk_crypto_profile *target, + const struct blk_crypto_profile *reference) +{ + int i; + + if (!reference) + return true; + + if (!target) + return false; + + for (i = 0; i < ARRAY_SIZE(target->modes_supported); i++) { + if (reference->modes_supported[i] & ~target->modes_supported[i]) + return false; + } + + if (reference->max_dun_bytes_supported > + target->max_dun_bytes_supported) + return false; + + return true; +} +EXPORT_SYMBOL_GPL(blk_crypto_has_capabilities); + +/** + * blk_crypto_update_capabilities() - Update the capabilities of a crypto + * profile to match those of another crypto + * profile. + * @dst: The crypto profile whose capabilities to update. + * @src: The crypto profile whose capabilities this function will update @dst's + * capabilities 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, @src must support all the crypto capabilities that + * @dst does (i.e. we need blk_crypto_has_capabilities(@src, @dst)). + * + * 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_crypto_update_capabilities(struct blk_crypto_profile *dst, + const struct blk_crypto_profile *src) +{ + memcpy(dst->modes_supported, src->modes_supported, + sizeof(dst->modes_supported)); + + dst->max_dun_bytes_supported = src->max_dun_bytes_supported; +} +EXPORT_SYMBOL_GPL(blk_crypto_update_capabilities); |