560 lines
16 KiB
C
560 lines
16 KiB
C
// 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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* 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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#include "blk-crypto-internal.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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/*
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* profile->lock of an underlying device can nest inside profile->lock
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* of a device-mapper device, so use a dynamic lock class to avoid
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* false-positive lockdep reports.
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*/
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lockdep_register_key(&profile->lockdep_key);
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__init_rwsem(&profile->lock, "&profile->lock", &profile->lockdep_key);
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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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goto err_destroy;
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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. blk_crypto_put_keyslot() must be called
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* later to release it. 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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* 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
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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 = slot->profile;
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unsigned long flags;
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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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* This is an internal function that evicts a key from an inline encryption
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* device that can be either a real device or the blk-crypto-fallback "device".
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* It is used only by blk_crypto_evict_key(); see that function for details.
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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;
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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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/*
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* Not an error, since a key not in use by I/O is not guaranteed
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* to be in a keyslot. There can be more keys than keyslots.
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*/
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err = 0;
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goto out;
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}
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if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) {
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/* BUG: key is still in use by I/O */
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err = -EBUSY;
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goto out_remove;
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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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out_remove:
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/*
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* Callers free the key even on error, so unlink the key from the hash
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* table and clear slot->key even on error.
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*/
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hlist_del(&slot->hash_node);
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slot->key = NULL;
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out:
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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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lockdep_unregister_key(&profile->lockdep_key);
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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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* 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)
|
|
{
|
|
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);
|