// 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>
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));
init_rwsem(&profile->lock);
if (num_slots == 0)
return 0;
/* Initialize keyslot management data. */
profile->slots = kvcalloc(num_slots, sizeof(profile->slots[0]),
GFP_KERNEL);
if (!profile->slots)
return -ENOMEM;
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;
}
/**
* __blk_crypto_evict_key() - Evict a key from a device.
* @profile: the crypto profile of the device
* @key: the key to evict. It must not still be used in any I/O.
*
* If the device has keyslots, this finds the keyslot (if any) that contains the
* specified key and calls the driver's keyslot_evict function to evict it.
*
* Otherwise, this just calls the driver's keyslot_evict function if it is
* implemented, passing just the key (without any particular keyslot). This
* allows layered devices to evict the key from their underlying devices.
*
* Context: Process context. Takes and releases profile->lock.
* Return: 0 on success or if there's no keyslot with the specified key, -EBUSY
* if the keyslot is still in use, or another -errno value on other
* error.
*/
int __blk_crypto_evict_key(struct blk_crypto_profile *profile,
const struct blk_crypto_key *key)
{
struct blk_crypto_keyslot *slot;
int err = 0;
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)
goto out_unlock;
if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) {
err = -EBUSY;
goto out_unlock;
}
err = profile->ll_ops.keyslot_evict(profile, key,
blk_crypto_keyslot_index(slot));
if (err)
goto out_unlock;
hlist_del(&slot->hash_node);
slot->key = NULL;
err = 0;
out_unlock:
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;
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);
