@@ -185,6 +185,13 @@ config BLK_SED_OPAL
Enabling this option enables users to setup/unlock/lock
Locking ranges for SED devices using the Opal protocol.
+config BLK_INLINE_ENCRYPTION
+ bool "Enable inline encryption support in block layer"
+ help
+ Build the blk-crypto subsystem. Enabling this lets the
+ block layer handle encryption, so users can take
+ advantage of inline encryption hardware if present.
+
menu "Partition Types"
source "block/partitions/Kconfig"
@@ -37,3 +37,4 @@ obj-$(CONFIG_BLK_DEBUG_FS) += blk-mq-debugfs.o
obj-$(CONFIG_BLK_DEBUG_FS_ZONED)+= blk-mq-debugfs-zoned.o
obj-$(CONFIG_BLK_SED_OPAL) += sed-opal.o
obj-$(CONFIG_BLK_PM) += blk-pm.o
+obj-$(CONFIG_BLK_INLINE_ENCRYPTION) += keyslot-manager.o
new file mode 100644
@@ -0,0 +1,377 @@
+// SPDX-License-Identifier: GPL-2.0
+/*
+ * Copyright 2019 Google LLC
+ */
+
+/**
+ * DOC: The Keyslot Manager
+ *
+ * Many devices with inline encryption support have a limited number of "slots"
+ * into which encryption contexts may be programmed, and requests can be tagged
+ * with a slot number to specify the key to use for en/decryption.
+ *
+ * As the number of slots are limited, and programming keys is expensive on
+ * many inline encryption hardware, we don't want to program the same key into
+ * multiple slots - if multiple requests are using the same key, we want to
+ * program just one slot with that key and use that slot for all requests.
+ *
+ * The keyslot manager manages these keyslots appropriately, and also acts as
+ * an abstraction between the inline encryption hardware and the upper layers.
+ *
+ * Lower layer devices will set up a keyslot manager in their request queue
+ * and tell it how to perform device specific operations like programming/
+ * evicting keys from keyslots.
+ *
+ * Upper layers will call blk_ksm_get_slot_for_key() to program a
+ * key into some slot in the inline encryption hardware.
+ */
+#include <crypto/algapi.h>
+#include <linux/keyslot-manager.h>
+#include <linux/atomic.h>
+#include <linux/mutex.h>
+#include <linux/pm_runtime.h>
+#include <linux/wait.h>
+#include <linux/blkdev.h>
+
+struct blk_ksm_keyslot {
+ atomic_t slot_refs;
+ struct list_head idle_slot_node;
+ struct hlist_node hash_node;
+ struct blk_crypto_key key;
+ struct keyslot_manager *ksm;
+};
+
+static inline void blk_ksm_hw_enter(struct keyslot_manager *ksm)
+{
+ /*
+ * Calling into the driver requires ksm->lock held and the device
+ * resumed. But we must resume the device first, since that can acquire
+ * and release ksm->lock via blk_ksm_reprogram_all_keys().
+ */
+ if (ksm->dev)
+ pm_runtime_get_sync(ksm->dev);
+ down_write(&ksm->lock);
+}
+
+static inline void blk_ksm_hw_exit(struct keyslot_manager *ksm)
+{
+ up_write(&ksm->lock);
+ if (ksm->dev)
+ pm_runtime_put_sync(ksm->dev);
+}
+
+/**
+ * blk_ksm_init() - Initialize a keyslot manager
+ * @ksm: The keyslot_manager to initialize.
+ * @dev: Device for runtime power management (NULL if none)
+ * @num_slots: The number of key slots to manage.
+ *
+ * Allocate memory for keyslots and initialize a keyslot manager. Called by
+ * e.g. storage drivers to set up a keyslot manager in their request_queue.
+ *
+ * Return: 0 on success, or else a negative error code.
+ */
+int blk_ksm_init(struct keyslot_manager *ksm, struct device *dev,
+ unsigned int num_slots)
+{
+ unsigned int slot;
+ unsigned int i;
+
+ memset(ksm, 0, sizeof(*ksm));
+
+ if (num_slots == 0)
+ return -EINVAL;
+
+ ksm->slots = kvcalloc(num_slots, sizeof(ksm->slots[0]), GFP_KERNEL);
+ if (!ksm->slots)
+ return -ENOMEM;
+
+ ksm->num_slots = num_slots;
+ ksm->dev = dev;
+
+ init_rwsem(&ksm->lock);
+
+ init_waitqueue_head(&ksm->idle_slots_wait_queue);
+ INIT_LIST_HEAD(&ksm->idle_slots);
+
+ for (slot = 0; slot < num_slots; slot++) {
+ ksm->slots[slot].ksm = ksm;
+ list_add_tail(&ksm->slots[slot].idle_slot_node,
+ &ksm->idle_slots);
+ }
+
+ spin_lock_init(&ksm->idle_slots_lock);
+
+ ksm->slot_hashtable_size = roundup_pow_of_two(num_slots);
+ ksm->slot_hashtable = kvmalloc_array(ksm->slot_hashtable_size,
+ sizeof(ksm->slot_hashtable[0]),
+ GFP_KERNEL);
+ if (!ksm->slot_hashtable)
+ goto err_destroy_ksm;
+ for (i = 0; i < ksm->slot_hashtable_size; i++)
+ INIT_HLIST_HEAD(&ksm->slot_hashtable[i]);
+
+ return 0;
+
+err_destroy_ksm:
+ blk_ksm_destroy(ksm);
+ return -ENOMEM;
+}
+EXPORT_SYMBOL_GPL(blk_ksm_init);
+
+static inline struct hlist_head *
+blk_ksm_hash_bucket_for_key(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key)
+{
+ return &ksm->slot_hashtable[key->hash & (ksm->slot_hashtable_size - 1)];
+}
+
+static void blk_ksm_remove_slot_from_lru_list(struct blk_ksm_keyslot *slot)
+{
+ struct keyslot_manager *ksm = slot->ksm;
+ unsigned long flags;
+
+ spin_lock_irqsave(&ksm->idle_slots_lock, flags);
+ list_del(&slot->idle_slot_node);
+ spin_unlock_irqrestore(&ksm->idle_slots_lock, flags);
+}
+
+static struct blk_ksm_keyslot *blk_ksm_find_keyslot(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key)
+{
+ const struct hlist_head *head = blk_ksm_hash_bucket_for_key(ksm, key);
+ struct blk_ksm_keyslot *slotp;
+
+ hlist_for_each_entry(slotp, head, hash_node) {
+ if (slotp->key.hash == key->hash &&
+ slotp->key.crypto_mode == key->crypto_mode &&
+ slotp->key.data_unit_size == key->data_unit_size &&
+ !crypto_memneq(slotp->key.raw, key->raw, key->size))
+ return slotp;
+ }
+ return NULL;
+}
+
+static struct blk_ksm_keyslot *blk_ksm_find_and_grab_keyslot(
+ struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key)
+{
+ struct blk_ksm_keyslot *slot;
+
+ slot = blk_ksm_find_keyslot(ksm, key);
+ if (!slot)
+ return NULL;
+ if (atomic_inc_return(&slot->slot_refs) == 1) {
+ /* Took first reference to this slot; remove it from LRU list */
+ blk_ksm_remove_slot_from_lru_list(slot);
+ }
+ return slot;
+}
+
+unsigned int blk_ksm_get_slot_idx(struct blk_ksm_keyslot *slot)
+{
+ return slot - slot->ksm->slots;
+}
+EXPORT_SYMBOL_GPL(blk_ksm_get_slot_idx);
+
+/**
+ * blk_ksm_get_slot_for_key() - Program a key into a keyslot.
+ * @ksm: The keyslot manager to program the key into.
+ * @key: Pointer to the key object to program, including the raw key, crypto
+ * mode, and data unit size.
+ * @keyslot: A pointer to return the pointer of the allocated keyslot.
+ *
+ * Get a keyslot that's been programmed with the specified key. If one already
+ * exists, return it with incremented refcount. Otherwise, wait for a keyslot
+ * to become idle and program it.
+ *
+ * Context: Process context. Takes and releases ksm->lock.
+ * Return: BLK_STATUS_OK on success (and keyslot is set to the pointer of the
+ * allocated keyslot), and BLK_STATUS_IOERR otherwise (and keyslot is
+ * set to NULL).
+ */
+blk_status_t blk_ksm_get_slot_for_key(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key,
+ struct blk_ksm_keyslot **slot_ptr)
+{
+ struct blk_ksm_keyslot *slot;
+ int slot_idx;
+ blk_status_t err;
+
+ *slot_ptr = NULL;
+ down_read(&ksm->lock);
+ slot = blk_ksm_find_and_grab_keyslot(ksm, key);
+ up_read(&ksm->lock);
+ if (slot)
+ goto success;
+
+ for (;;) {
+ blk_ksm_hw_enter(ksm);
+ slot = blk_ksm_find_and_grab_keyslot(ksm, key);
+ if (slot) {
+ blk_ksm_hw_exit(ksm);
+ goto success;
+ }
+
+ /*
+ * If we're here, that means there wasn't a slot that was
+ * already programmed with the key. So try to program it.
+ */
+ if (!list_empty(&ksm->idle_slots))
+ break;
+
+ blk_ksm_hw_exit(ksm);
+ wait_event(ksm->idle_slots_wait_queue,
+ !list_empty(&ksm->idle_slots));
+ }
+
+ slot = list_first_entry(&ksm->idle_slots, struct blk_ksm_keyslot,
+ idle_slot_node);
+ slot_idx = blk_ksm_get_slot_idx(slot);
+
+ err = ksm->ksm_ll_ops.keyslot_program(ksm, key, slot_idx);
+ if (err != BLK_STS_OK) {
+ wake_up(&ksm->idle_slots_wait_queue);
+ blk_ksm_hw_exit(ksm);
+ return err;
+ }
+
+ /* Move this slot to the hash list for the new key. */
+ if (slot->key.crypto_mode != BLK_ENCRYPTION_MODE_INVALID)
+ hlist_del(&slot->hash_node);
+ hlist_add_head(&slot->hash_node, blk_ksm_hash_bucket_for_key(ksm, key));
+
+ atomic_set(&slot->slot_refs, 1);
+ slot->key = *key;
+
+ blk_ksm_remove_slot_from_lru_list(slot);
+
+ blk_ksm_hw_exit(ksm);
+success:
+ *slot_ptr = slot;
+ return BLK_STS_OK;
+}
+
+/**
+ * blk_ksm_put_slot() - Release a reference to a slot
+ * @slot: The keyslot to release the reference of.
+ *
+ * Context: Any context.
+ */
+void blk_ksm_put_slot(struct blk_ksm_keyslot *slot)
+{
+ struct keyslot_manager *ksm = slot->ksm;
+ unsigned long flags;
+
+ if (!slot)
+ return;
+
+ if (atomic_dec_and_lock_irqsave(&slot->slot_refs,
+ &ksm->idle_slots_lock, flags)) {
+ list_add_tail(&slot->idle_slot_node,
+ &ksm->idle_slots);
+ spin_unlock_irqrestore(&ksm->idle_slots_lock, flags);
+ wake_up(&ksm->idle_slots_wait_queue);
+ }
+}
+
+/**
+ * blk_ksm_crypto_key_supported() - Find out if the crypto_mode, dusize, dun
+ * bytes of a crypto_key are supported by a
+ * ksm.
+ * @ksm: The keyslot manager to check
+ * @key: The key whose crypto_mode, dusize and dun bytes to check for.
+ *
+ * Checks for crypto_mode/data unit size/dun bytes support.
+ *
+ * Return: Whether or not this ksm supports the specified crypto key.
+ */
+bool blk_ksm_crypto_key_supported(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key)
+{
+ if (!ksm)
+ return false;
+ return (ksm->crypto_modes_supported[key->crypto_mode] &
+ key->data_unit_size) &&
+ (ksm->max_dun_bytes_supported >= key->dun_bytes);
+}
+
+/**
+ * blk_ksm_evict_key() - Evict a key from the lower layer device.
+ * @ksm: The keyslot manager to evict from
+ * @key: The key to evict
+ *
+ * Find the keyslot that the specified key was programmed into, and evict that
+ * slot from the lower layer device if that slot is not currently in use.
+ *
+ * Context: Process context. Takes and releases ksm->lock.
+ * Return: 0 on success or if there's no keyslot with the specified key, -EBUSY
+ * if the key is still in use, or another -errno value on other error.
+ */
+int blk_ksm_evict_key(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key)
+{
+ struct blk_ksm_keyslot *slot;
+ int err = 0;
+
+ blk_ksm_hw_enter(ksm);
+ slot = blk_ksm_find_keyslot(ksm, key);
+ if (!slot)
+ goto out_unlock;
+
+ if (atomic_read(&slot->slot_refs) != 0) {
+ err = -EBUSY;
+ goto out_unlock;
+ }
+ err = ksm->ksm_ll_ops.keyslot_evict(ksm, key,
+ blk_ksm_get_slot_idx(slot));
+ if (err)
+ goto out_unlock;
+
+ hlist_del(&slot->hash_node);
+ memzero_explicit(&slot->key, sizeof(slot->key));
+ err = 0;
+out_unlock:
+ blk_ksm_hw_exit(ksm);
+ return err;
+}
+
+/**
+ * blk_ksm_reprogram_all_keys() - Re-program all keyslots.
+ * @ksm: The keyslot manager
+ *
+ * Re-program all keyslots that are supposed to have a key programmed. This is
+ * intended only for use by drivers for hardware that loses its keys on reset.
+ *
+ * Context: Process context. Takes and releases ksm->lock.
+ */
+void blk_ksm_reprogram_all_keys(struct keyslot_manager *ksm)
+{
+ unsigned int slot;
+
+ /* This is for device initialization, so don't resume the device */
+ down_write(&ksm->lock);
+ for (slot = 0; slot < ksm->num_slots; slot++) {
+ const struct blk_ksm_keyslot *slotp = &ksm->slots[slot];
+ int err;
+
+ if (slotp->key.crypto_mode == BLK_ENCRYPTION_MODE_INVALID)
+ continue;
+
+ err = ksm->ksm_ll_ops.keyslot_program(ksm, &slotp->key, slot);
+ WARN_ON(err);
+ }
+ up_write(&ksm->lock);
+}
+EXPORT_SYMBOL_GPL(blk_ksm_reprogram_all_keys);
+
+void blk_ksm_destroy(struct keyslot_manager *ksm)
+{
+ if (!ksm)
+ return;
+ kvfree(ksm->slot_hashtable);
+ memzero_explicit(ksm->slots, sizeof(ksm->slots[0]) * ksm->num_slots);
+ kvfree(ksm->slots);
+ memzero_explicit(ksm, sizeof(*ksm));
+}
+EXPORT_SYMBOL_GPL(blk_ksm_destroy);
new file mode 100644
@@ -0,0 +1,45 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#ifndef __LINUX_BLK_CRYPTO_H
+#define __LINUX_BLK_CRYPTO_H
+
+enum blk_crypto_mode_num {
+ BLK_ENCRYPTION_MODE_INVALID,
+ BLK_ENCRYPTION_MODE_AES_256_XTS,
+ BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV,
+ BLK_ENCRYPTION_MODE_ADIANTUM,
+ BLK_ENCRYPTION_MODE_MAX,
+};
+
+#define BLK_CRYPTO_MAX_KEY_SIZE 64
+
+/**
+ * struct blk_crypto_key - an inline encryption key
+ * @crypto_mode: encryption algorithm this key is for
+ * @data_unit_size: the data unit size for all encryption/decryptions with this
+ * key. This is the size in bytes of each individual plaintext and
+ * ciphertext. This is always a power of 2. It might be e.g. the
+ * filesystem block size or the disk sector size.
+ * @data_unit_size_bits: log2 of data_unit_size
+ * @dun_bytes: the number of bytes of DUN used when using this key
+ * @size: size of this key in bytes (determined by @crypto_mode)
+ * @hash: hash of this key, for keyslot manager use only
+ * @raw: the raw bytes of this key. Only the first @size bytes are used.
+ *
+ * A blk_crypto_key is immutable once created, and many bios can reference it at
+ * the same time. It must not be freed until all bios using it have completed.
+ */
+struct blk_crypto_key {
+ enum blk_crypto_mode_num crypto_mode;
+ unsigned int data_unit_size;
+ unsigned int data_unit_size_bits;
+ unsigned int dun_bytes;
+ unsigned int size;
+ unsigned int hash;
+ u8 raw[BLK_CRYPTO_MAX_KEY_SIZE];
+};
+
+#endif /* __LINUX_BLK_CRYPTO_H */
@@ -43,6 +43,7 @@ struct pr_ops;
struct rq_qos;
struct blk_queue_stats;
struct blk_stat_callback;
+struct keyslot_manager;
#define BLKDEV_MIN_RQ 4
#define BLKDEV_MAX_RQ 128 /* Default maximum */
@@ -474,6 +475,11 @@ struct request_queue {
unsigned int dma_pad_mask;
unsigned int dma_alignment;
+#ifdef CONFIG_BLK_INLINE_ENCRYPTION
+ /* Inline crypto capabilities */
+ struct keyslot_manager *ksm;
+#endif
+
unsigned int rq_timeout;
int poll_nsec;
new file mode 100644
@@ -0,0 +1,108 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright 2019 Google LLC
+ */
+
+#ifndef __LINUX_KEYSLOT_MANAGER_H
+#define __LINUX_KEYSLOT_MANAGER_H
+
+#include <linux/bio.h>
+#include <linux/blk-crypto.h>
+
+struct keyslot_manager;
+
+/**
+ * struct keyslot_mgmt_ll_ops - functions to manage keyslots in hardware
+ * @keyslot_program: Program the specified key into the specified slot in the
+ * inline encryption hardware.
+ * @keyslot_evict: Evict key from the specified keyslot in the hardware.
+ * The key is provided so that e.g. dm layers can evict
+ * keys from the devices that they map over.
+ * Returns 0 on success, -errno otherwise.
+ *
+ * This structure should be provided by storage device drivers when they set up
+ * a keyslot manager - this structure holds the function ptrs that the keyslot
+ * manager will use to manipulate keyslots in the hardware.
+ */
+struct keyslot_mgmt_ll_ops {
+ blk_status_t (*keyslot_program)(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key,
+ unsigned int slot);
+ int (*keyslot_evict)(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key,
+ unsigned int slot);
+};
+
+struct keyslot_manager {
+ /*
+ * The struct keyslot_mgmt_ll_ops that this keyslot manager will use
+ * to perform operations like programming and evicting keys on the
+ * device
+ */
+ struct keyslot_mgmt_ll_ops ksm_ll_ops;
+
+ /*
+ * The maximum number of bytes supported for specifying the data unit
+ * number.
+ */
+ unsigned int max_dun_bytes_supported;
+
+ /*
+ * Array of size BLK_ENCRYPTION_MODE_MAX of bitmasks that represents
+ * whether a crypto mode and data unit size are supported. The i'th
+ * bit of crypto_mode_supported[crypto_mode] is set iff a data unit
+ * size of (1 << i) is supported. We only support data unit sizes
+ * that are powers of 2.
+ */
+ unsigned int crypto_modes_supported[BLK_ENCRYPTION_MODE_MAX];
+
+ /* Device for runtime power management (NULL if none) */
+ struct device *dev;
+
+ /* Here onwards are *private* fields for internal keyslot manager use */
+
+ unsigned int num_slots;
+
+ /* Protects programming and evicting keys from the device */
+ struct rw_semaphore lock;
+
+ /* List of idle slots, with least recently used slot at front */
+ wait_queue_head_t idle_slots_wait_queue;
+ struct list_head idle_slots;
+ spinlock_t idle_slots_lock;
+
+ /*
+ * Hash table which maps key hashes to keyslots, so that we can find a
+ * key's keyslot in O(1) time rather than O(num_slots). Protected by
+ * 'lock'. A cryptographic hash function is used so that timing attacks
+ * can't leak information about the raw keys.
+ */
+ struct hlist_head *slot_hashtable;
+ unsigned int slot_hashtable_size;
+
+ /* Per-keyslot data */
+ struct blk_ksm_keyslot *slots;
+};
+
+int blk_ksm_init(struct keyslot_manager *ksm, struct device *dev,
+ unsigned int num_slots);
+
+blk_status_t blk_ksm_get_slot_for_key(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key,
+ struct blk_ksm_keyslot **slot_ptr);
+
+unsigned int blk_ksm_get_slot_idx(struct blk_ksm_keyslot *slot);
+
+void blk_ksm_put_slot(struct blk_ksm_keyslot *slot);
+
+bool blk_ksm_crypto_key_supported(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key);
+
+int blk_ksm_evict_key(struct keyslot_manager *ksm,
+ const struct blk_crypto_key *key);
+
+void blk_ksm_reprogram_all_keys(struct keyslot_manager *ksm);
+
+void blk_ksm_destroy(struct keyslot_manager *ksm);
+
+#endif /* __LINUX_KEYSLOT_MANAGER_H */