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Inline Encryption hardware allows software to specify an encryption context (an encryption key, crypto algorithm, data unit num, data unit size) along with a data transfer request to a storage device, and the inline encryption hardware will use that context to en/decrypt the data. The inline encryption hardware is part of the storage device, and it conceptually sits on the data path between system memory and the storage device. Inline Encryption hardware implementations often function around the concept of "keyslots". These implementations often have a limited number of "keyslots", each of which can hold a key (we say that a key can be "programmed" into a keyslot). Requests made to the storage device may have a keyslot and a data unit number associated with them, and the inline encryption hardware will en/decrypt the data in the requests using the key programmed into that associated keyslot and the data unit number specified with the request. As keyslots are limited, and programming keys may be expensive in many implementations, and multiple requests may use exactly the same encryption contexts, we introduce a Keyslot Manager to efficiently manage keyslots. We also introduce a blk_crypto_key, which will represent the key that's programmed into keyslots managed by keyslot managers. The keyslot manager also functions as the interface that upper layers will use to program keys into inline encryption hardware. For more information on the Keyslot Manager, refer to documentation found in block/keyslot-manager.c and linux/keyslot-manager.h. Co-developed-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Satya Tangirala <satyat@google.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Reviewed-by: Christoph Hellwig <hch@lst.de> Signed-off-by: Jens Axboe <axboe@kernel.dk>
107 lines
3.3 KiB
C
107 lines
3.3 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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#ifndef __LINUX_KEYSLOT_MANAGER_H
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#define __LINUX_KEYSLOT_MANAGER_H
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#include <linux/bio.h>
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#include <linux/blk-crypto.h>
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struct blk_keyslot_manager;
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/**
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* struct blk_ksm_ll_ops - functions to manage keyslots in hardware
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* @keyslot_program: Program the specified key into the specified slot in the
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* inline encryption hardware.
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* @keyslot_evict: Evict key from the specified keyslot in the hardware.
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* The key is provided so that e.g. dm layers can evict
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* keys from the devices that they map over.
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* Returns 0 on success, -errno otherwise.
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*
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* This structure should be provided by storage device drivers when they set up
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* a keyslot manager - this structure holds the function ptrs that the keyslot
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* manager will use to manipulate keyslots in the hardware.
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*/
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struct blk_ksm_ll_ops {
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int (*keyslot_program)(struct blk_keyslot_manager *ksm,
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const struct blk_crypto_key *key,
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unsigned int slot);
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int (*keyslot_evict)(struct blk_keyslot_manager *ksm,
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const struct blk_crypto_key *key,
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unsigned int slot);
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};
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struct blk_keyslot_manager {
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/*
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* The struct blk_ksm_ll_ops that this keyslot manager will use
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* to perform operations like programming and evicting keys on the
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* device
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*/
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struct blk_ksm_ll_ops ksm_ll_ops;
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/*
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* The maximum number of bytes supported for specifying the data unit
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* number.
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*/
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unsigned int max_dun_bytes_supported;
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/*
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* Array of size BLK_ENCRYPTION_MODE_MAX of bitmasks that represents
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* whether a crypto mode and data unit size are supported. The i'th
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* bit of crypto_mode_supported[crypto_mode] is set iff a data unit
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* size of (1 << i) is supported. We only support data unit sizes
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* that are powers of 2.
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*/
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unsigned int crypto_modes_supported[BLK_ENCRYPTION_MODE_MAX];
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/* Device for runtime power management (NULL if none) */
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struct device *dev;
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/* Here onwards are *private* fields for internal keyslot manager use */
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unsigned int num_slots;
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/* Protects programming and evicting keys from the device */
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struct rw_semaphore lock;
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/* List of idle slots, with least recently used slot at front */
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wait_queue_head_t idle_slots_wait_queue;
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struct list_head idle_slots;
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spinlock_t idle_slots_lock;
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/*
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* Hash table which maps struct *blk_crypto_key to keyslots, so that we
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* can find a key's keyslot in O(1) time rather than O(num_slots).
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* Protected by 'lock'.
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*/
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struct hlist_head *slot_hashtable;
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unsigned int log_slot_ht_size;
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/* Per-keyslot data */
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struct blk_ksm_keyslot *slots;
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};
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int blk_ksm_init(struct blk_keyslot_manager *ksm, unsigned int num_slots);
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blk_status_t blk_ksm_get_slot_for_key(struct blk_keyslot_manager *ksm,
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const struct blk_crypto_key *key,
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struct blk_ksm_keyslot **slot_ptr);
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unsigned int blk_ksm_get_slot_idx(struct blk_ksm_keyslot *slot);
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void blk_ksm_put_slot(struct blk_ksm_keyslot *slot);
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bool blk_ksm_crypto_cfg_supported(struct blk_keyslot_manager *ksm,
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const struct blk_crypto_config *cfg);
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int blk_ksm_evict_key(struct blk_keyslot_manager *ksm,
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const struct blk_crypto_key *key);
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void blk_ksm_reprogram_all_keys(struct blk_keyslot_manager *ksm);
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void blk_ksm_destroy(struct blk_keyslot_manager *ksm);
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#endif /* __LINUX_KEYSLOT_MANAGER_H */
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