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560 lines
16 KiB
560 lines
16 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* Copyright 2019 Google LLC |
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*/ |
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|
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/** |
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* DOC: blk-crypto profiles |
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* |
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* 'struct blk_crypto_profile' contains all generic inline encryption-related |
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* state for a particular inline encryption device. blk_crypto_profile serves |
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* as the way that drivers for inline encryption hardware expose their crypto |
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* capabilities and certain functions (e.g., functions to program and evict |
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* keys) to upper layers. Device drivers that want to support inline encryption |
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* construct a crypto profile, then associate it with the disk's request_queue. |
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* |
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* If the device has keyslots, then its blk_crypto_profile also handles managing |
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* these keyslots in a device-independent way, using the driver-provided |
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* functions to program and evict keys as needed. This includes keeping track |
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* of which key and how many I/O requests are using each keyslot, getting |
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* keyslots for I/O requests, and handling key eviction requests. |
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* |
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* For more information, see Documentation/block/inline-encryption.rst. |
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*/ |
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#define pr_fmt(fmt) "blk-crypto: " fmt |
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#include <linux/blk-crypto-profile.h> |
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#include <linux/device.h> |
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#include <linux/atomic.h> |
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#include <linux/mutex.h> |
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#include <linux/pm_runtime.h> |
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#include <linux/wait.h> |
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#include <linux/blkdev.h> |
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#include <linux/blk-integrity.h> |
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struct blk_crypto_keyslot { |
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atomic_t slot_refs; |
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struct list_head idle_slot_node; |
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struct hlist_node hash_node; |
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const struct blk_crypto_key *key; |
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struct blk_crypto_profile *profile; |
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}; |
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static inline void blk_crypto_hw_enter(struct blk_crypto_profile *profile) |
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{ |
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/* |
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* Calling into the driver requires profile->lock held and the device |
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* resumed. But we must resume the device first, since that can acquire |
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* and release profile->lock via blk_crypto_reprogram_all_keys(). |
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*/ |
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if (profile->dev) |
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pm_runtime_get_sync(profile->dev); |
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down_write(&profile->lock); |
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} |
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static inline void blk_crypto_hw_exit(struct blk_crypto_profile *profile) |
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{ |
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up_write(&profile->lock); |
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if (profile->dev) |
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pm_runtime_put_sync(profile->dev); |
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} |
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/** |
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* blk_crypto_profile_init() - Initialize a blk_crypto_profile |
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* @profile: the blk_crypto_profile to initialize |
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* @num_slots: the number of keyslots |
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* |
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* Storage drivers must call this when starting to set up a blk_crypto_profile, |
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* before filling in additional fields. |
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* |
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* Return: 0 on success, or else a negative error code. |
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*/ |
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int blk_crypto_profile_init(struct blk_crypto_profile *profile, |
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unsigned int num_slots) |
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{ |
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unsigned int slot; |
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unsigned int i; |
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unsigned int slot_hashtable_size; |
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memset(profile, 0, sizeof(*profile)); |
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init_rwsem(&profile->lock); |
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if (num_slots == 0) |
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return 0; |
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/* Initialize keyslot management data. */ |
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profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]), |
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GFP_KERNEL); |
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if (!profile->slots) |
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return -ENOMEM; |
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profile->num_slots = num_slots; |
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init_waitqueue_head(&profile->idle_slots_wait_queue); |
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INIT_LIST_HEAD(&profile->idle_slots); |
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for (slot = 0; slot < num_slots; slot++) { |
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profile->slots[slot].profile = profile; |
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list_add_tail(&profile->slots[slot].idle_slot_node, |
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&profile->idle_slots); |
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} |
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spin_lock_init(&profile->idle_slots_lock); |
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slot_hashtable_size = roundup_pow_of_two(num_slots); |
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/* |
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* hash_ptr() assumes bits != 0, so ensure the hash table has at least 2 |
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* buckets. This only makes a difference when there is only 1 keyslot. |
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*/ |
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if (slot_hashtable_size < 2) |
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slot_hashtable_size = 2; |
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profile->log_slot_ht_size = ilog2(slot_hashtable_size); |
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profile->slot_hashtable = |
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kvmalloc_array(slot_hashtable_size, |
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sizeof(profile->slot_hashtable[0]), GFP_KERNEL); |
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if (!profile->slot_hashtable) |
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goto err_destroy; |
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for (i = 0; i < slot_hashtable_size; i++) |
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INIT_HLIST_HEAD(&profile->slot_hashtable[i]); |
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return 0; |
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err_destroy: |
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blk_crypto_profile_destroy(profile); |
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return -ENOMEM; |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_profile_init); |
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static void blk_crypto_profile_destroy_callback(void *profile) |
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{ |
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blk_crypto_profile_destroy(profile); |
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} |
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/** |
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* devm_blk_crypto_profile_init() - Resource-managed blk_crypto_profile_init() |
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* @dev: the device which owns the blk_crypto_profile |
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* @profile: the blk_crypto_profile to initialize |
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* @num_slots: the number of keyslots |
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* |
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* Like blk_crypto_profile_init(), but causes blk_crypto_profile_destroy() to be |
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* called automatically on driver detach. |
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* |
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* Return: 0 on success, or else a negative error code. |
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*/ |
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int devm_blk_crypto_profile_init(struct device *dev, |
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struct blk_crypto_profile *profile, |
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unsigned int num_slots) |
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{ |
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int err = blk_crypto_profile_init(profile, num_slots); |
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if (err) |
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return err; |
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return devm_add_action_or_reset(dev, |
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blk_crypto_profile_destroy_callback, |
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profile); |
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} |
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EXPORT_SYMBOL_GPL(devm_blk_crypto_profile_init); |
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static inline struct hlist_head * |
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blk_crypto_hash_bucket_for_key(struct blk_crypto_profile *profile, |
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const struct blk_crypto_key *key) |
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{ |
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return &profile->slot_hashtable[ |
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hash_ptr(key, profile->log_slot_ht_size)]; |
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} |
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static void |
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blk_crypto_remove_slot_from_lru_list(struct blk_crypto_keyslot *slot) |
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{ |
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struct blk_crypto_profile *profile = slot->profile; |
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unsigned long flags; |
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spin_lock_irqsave(&profile->idle_slots_lock, flags); |
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list_del(&slot->idle_slot_node); |
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spin_unlock_irqrestore(&profile->idle_slots_lock, flags); |
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} |
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static struct blk_crypto_keyslot * |
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blk_crypto_find_keyslot(struct blk_crypto_profile *profile, |
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const struct blk_crypto_key *key) |
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{ |
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const struct hlist_head *head = |
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blk_crypto_hash_bucket_for_key(profile, key); |
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struct blk_crypto_keyslot *slotp; |
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hlist_for_each_entry(slotp, head, hash_node) { |
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if (slotp->key == key) |
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return slotp; |
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} |
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return NULL; |
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} |
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static struct blk_crypto_keyslot * |
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blk_crypto_find_and_grab_keyslot(struct blk_crypto_profile *profile, |
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const struct blk_crypto_key *key) |
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{ |
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struct blk_crypto_keyslot *slot; |
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slot = blk_crypto_find_keyslot(profile, key); |
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if (!slot) |
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return NULL; |
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if (atomic_inc_return(&slot->slot_refs) == 1) { |
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/* Took first reference to this slot; remove it from LRU list */ |
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blk_crypto_remove_slot_from_lru_list(slot); |
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} |
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return slot; |
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} |
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/** |
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* blk_crypto_keyslot_index() - Get the index of a keyslot |
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* @slot: a keyslot that blk_crypto_get_keyslot() returned |
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* |
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* Return: the 0-based index of the keyslot within the device's keyslots. |
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*/ |
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unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot) |
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{ |
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return slot - slot->profile->slots; |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_keyslot_index); |
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/** |
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* blk_crypto_get_keyslot() - Get a keyslot for a key, if needed. |
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* @profile: the crypto profile of the device the key will be used on |
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* @key: the key that will be used |
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* @slot_ptr: If a keyslot is allocated, an opaque pointer to the keyslot struct |
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* will be stored here; otherwise NULL will be stored here. |
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* |
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* If the device has keyslots, this gets a keyslot that's been programmed with |
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* the specified key. If the key is already in a slot, this reuses it; |
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* otherwise this waits for a slot to become idle and programs the key into it. |
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* |
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* This must be paired with a call to blk_crypto_put_keyslot(). |
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* |
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* Context: Process context. Takes and releases profile->lock. |
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* Return: BLK_STS_OK on success, meaning that either a keyslot was allocated or |
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* one wasn't needed; or a blk_status_t error on failure. |
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*/ |
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blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, |
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const struct blk_crypto_key *key, |
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struct blk_crypto_keyslot **slot_ptr) |
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{ |
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struct blk_crypto_keyslot *slot; |
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int slot_idx; |
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int err; |
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*slot_ptr = NULL; |
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/* |
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* If the device has no concept of "keyslots", then there is no need to |
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* get one. |
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*/ |
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if (profile->num_slots == 0) |
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return BLK_STS_OK; |
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down_read(&profile->lock); |
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slot = blk_crypto_find_and_grab_keyslot(profile, key); |
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up_read(&profile->lock); |
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if (slot) |
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goto success; |
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for (;;) { |
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blk_crypto_hw_enter(profile); |
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slot = blk_crypto_find_and_grab_keyslot(profile, key); |
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if (slot) { |
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blk_crypto_hw_exit(profile); |
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goto success; |
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} |
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/* |
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* If we're here, that means there wasn't a slot that was |
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* already programmed with the key. So try to program it. |
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*/ |
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if (!list_empty(&profile->idle_slots)) |
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break; |
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blk_crypto_hw_exit(profile); |
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wait_event(profile->idle_slots_wait_queue, |
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!list_empty(&profile->idle_slots)); |
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} |
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slot = list_first_entry(&profile->idle_slots, struct blk_crypto_keyslot, |
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idle_slot_node); |
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slot_idx = blk_crypto_keyslot_index(slot); |
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err = profile->ll_ops.keyslot_program(profile, key, slot_idx); |
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if (err) { |
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wake_up(&profile->idle_slots_wait_queue); |
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blk_crypto_hw_exit(profile); |
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return errno_to_blk_status(err); |
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} |
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/* Move this slot to the hash list for the new key. */ |
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if (slot->key) |
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hlist_del(&slot->hash_node); |
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slot->key = key; |
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hlist_add_head(&slot->hash_node, |
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blk_crypto_hash_bucket_for_key(profile, key)); |
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atomic_set(&slot->slot_refs, 1); |
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blk_crypto_remove_slot_from_lru_list(slot); |
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blk_crypto_hw_exit(profile); |
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success: |
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*slot_ptr = slot; |
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return BLK_STS_OK; |
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} |
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/** |
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* blk_crypto_put_keyslot() - Release a reference to a keyslot |
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* @slot: The keyslot to release the reference of (may be NULL). |
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* |
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* Context: Any context. |
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*/ |
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void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot) |
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{ |
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struct blk_crypto_profile *profile; |
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unsigned long flags; |
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if (!slot) |
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return; |
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profile = slot->profile; |
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if (atomic_dec_and_lock_irqsave(&slot->slot_refs, |
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&profile->idle_slots_lock, flags)) { |
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list_add_tail(&slot->idle_slot_node, &profile->idle_slots); |
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spin_unlock_irqrestore(&profile->idle_slots_lock, flags); |
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wake_up(&profile->idle_slots_wait_queue); |
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} |
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} |
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/** |
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* __blk_crypto_cfg_supported() - Check whether the given crypto profile |
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* supports the given crypto configuration. |
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* @profile: the crypto profile to check |
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* @cfg: the crypto configuration to check for |
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* |
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* Return: %true if @profile supports the given @cfg. |
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*/ |
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bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, |
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const struct blk_crypto_config *cfg) |
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{ |
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if (!profile) |
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return false; |
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if (!(profile->modes_supported[cfg->crypto_mode] & cfg->data_unit_size)) |
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return false; |
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if (profile->max_dun_bytes_supported < cfg->dun_bytes) |
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return false; |
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return true; |
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} |
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/** |
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* __blk_crypto_evict_key() - Evict a key from a device. |
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* @profile: the crypto profile of the device |
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* @key: the key to evict. It must not still be used in any I/O. |
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* |
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* If the device has keyslots, this finds the keyslot (if any) that contains the |
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* specified key and calls the driver's keyslot_evict function to evict it. |
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* |
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* Otherwise, this just calls the driver's keyslot_evict function if it is |
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* implemented, passing just the key (without any particular keyslot). This |
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* allows layered devices to evict the key from their underlying devices. |
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* |
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* Context: Process context. Takes and releases profile->lock. |
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* Return: 0 on success or if there's no keyslot with the specified key, -EBUSY |
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* if the keyslot is still in use, or another -errno value on other |
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* error. |
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*/ |
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int __blk_crypto_evict_key(struct blk_crypto_profile *profile, |
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const struct blk_crypto_key *key) |
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{ |
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struct blk_crypto_keyslot *slot; |
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int err = 0; |
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if (profile->num_slots == 0) { |
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if (profile->ll_ops.keyslot_evict) { |
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blk_crypto_hw_enter(profile); |
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err = profile->ll_ops.keyslot_evict(profile, key, -1); |
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blk_crypto_hw_exit(profile); |
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return err; |
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} |
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return 0; |
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} |
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blk_crypto_hw_enter(profile); |
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slot = blk_crypto_find_keyslot(profile, key); |
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if (!slot) |
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goto out_unlock; |
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if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) { |
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err = -EBUSY; |
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goto out_unlock; |
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} |
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err = profile->ll_ops.keyslot_evict(profile, key, |
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blk_crypto_keyslot_index(slot)); |
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if (err) |
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goto out_unlock; |
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hlist_del(&slot->hash_node); |
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slot->key = NULL; |
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err = 0; |
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out_unlock: |
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blk_crypto_hw_exit(profile); |
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return err; |
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} |
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/** |
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* blk_crypto_reprogram_all_keys() - Re-program all keyslots. |
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* @profile: The crypto profile |
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* |
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* Re-program all keyslots that are supposed to have a key programmed. This is |
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* intended only for use by drivers for hardware that loses its keys on reset. |
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* |
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* Context: Process context. Takes and releases profile->lock. |
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*/ |
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void blk_crypto_reprogram_all_keys(struct blk_crypto_profile *profile) |
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{ |
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unsigned int slot; |
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if (profile->num_slots == 0) |
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return; |
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/* This is for device initialization, so don't resume the device */ |
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down_write(&profile->lock); |
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for (slot = 0; slot < profile->num_slots; slot++) { |
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const struct blk_crypto_key *key = profile->slots[slot].key; |
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int err; |
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if (!key) |
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continue; |
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err = profile->ll_ops.keyslot_program(profile, key, slot); |
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WARN_ON(err); |
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} |
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up_write(&profile->lock); |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_reprogram_all_keys); |
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void blk_crypto_profile_destroy(struct blk_crypto_profile *profile) |
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{ |
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if (!profile) |
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return; |
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kvfree(profile->slot_hashtable); |
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kvfree_sensitive(profile->slots, |
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sizeof(profile->slots[0]) * profile->num_slots); |
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memzero_explicit(profile, sizeof(*profile)); |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_profile_destroy); |
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bool blk_crypto_register(struct blk_crypto_profile *profile, |
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struct request_queue *q) |
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{ |
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if (blk_integrity_queue_supports_integrity(q)) { |
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pr_warn("Integrity and hardware inline encryption are not supported together. Disabling hardware inline encryption.\n"); |
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return false; |
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} |
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q->crypto_profile = profile; |
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return true; |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_register); |
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/** |
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* blk_crypto_intersect_capabilities() - restrict supported crypto capabilities |
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* by child device |
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* @parent: the crypto profile for the parent device |
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* @child: the crypto profile for the child device, or NULL |
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* |
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* This clears all crypto capabilities in @parent that aren't set in @child. If |
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* @child is NULL, then this clears all parent capabilities. |
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* |
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* Only use this when setting up the crypto profile for a layered device, before |
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* it's been exposed yet. |
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*/ |
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void blk_crypto_intersect_capabilities(struct blk_crypto_profile *parent, |
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const struct blk_crypto_profile *child) |
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{ |
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if (child) { |
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unsigned int i; |
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parent->max_dun_bytes_supported = |
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min(parent->max_dun_bytes_supported, |
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child->max_dun_bytes_supported); |
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for (i = 0; i < ARRAY_SIZE(child->modes_supported); i++) |
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parent->modes_supported[i] &= child->modes_supported[i]; |
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} else { |
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parent->max_dun_bytes_supported = 0; |
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memset(parent->modes_supported, 0, |
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sizeof(parent->modes_supported)); |
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} |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_intersect_capabilities); |
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|
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/** |
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* blk_crypto_has_capabilities() - Check whether @target supports at least all |
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* the crypto capabilities that @reference does. |
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* @target: the target profile |
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* @reference: the reference profile |
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* |
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* Return: %true if @target supports all the crypto capabilities of @reference. |
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*/ |
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bool blk_crypto_has_capabilities(const struct blk_crypto_profile *target, |
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const struct blk_crypto_profile *reference) |
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{ |
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int i; |
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|
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if (!reference) |
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return true; |
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if (!target) |
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return false; |
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for (i = 0; i < ARRAY_SIZE(target->modes_supported); i++) { |
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if (reference->modes_supported[i] & ~target->modes_supported[i]) |
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return false; |
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} |
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if (reference->max_dun_bytes_supported > |
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target->max_dun_bytes_supported) |
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return false; |
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return true; |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_has_capabilities); |
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|
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/** |
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* blk_crypto_update_capabilities() - Update the capabilities of a crypto |
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* profile to match those of another crypto |
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* profile. |
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* @dst: The crypto profile whose capabilities to update. |
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* @src: The crypto profile whose capabilities this function will update @dst's |
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* capabilities to. |
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* |
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* Blk-crypto requires that crypto capabilities that were |
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* advertised when a bio was created continue to be supported by the |
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* device until that bio is ended. This is turn means that a device cannot |
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* shrink its advertised crypto capabilities without any explicit |
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* synchronization with upper layers. So if there's no such explicit |
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* synchronization, @src must support all the crypto capabilities that |
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* @dst does (i.e. we need blk_crypto_has_capabilities(@src, @dst)). |
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* |
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* Note also that as long as the crypto capabilities are being expanded, the |
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* order of updates becoming visible is not important because it's alright |
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* for blk-crypto to see stale values - they only cause blk-crypto to |
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* believe that a crypto capability isn't supported when it actually is (which |
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* might result in blk-crypto-fallback being used if available, or the bio being |
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* failed). |
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*/ |
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void blk_crypto_update_capabilities(struct blk_crypto_profile *dst, |
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const struct blk_crypto_profile *src) |
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{ |
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memcpy(dst->modes_supported, src->modes_supported, |
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sizeof(dst->modes_supported)); |
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|
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dst->max_dun_bytes_supported = src->max_dun_bytes_supported; |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_update_capabilities);
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