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d3b17a2437
Introduce blk_ksm_update_capabilities() to update the capabilities of a keyslot manager (ksm) in-place. The pointer to a ksm in a device's request queue may not be easily replaced, because upper layers like the filesystem might access it (e.g. for programming keys/checking capabilities) at the same time the device wants to replace that request queue's ksm (and free the old ksm's memory). This function allows the device to update the capabilities of the ksm in its request queue directly. Devices can safely update the ksm this way without any synchronization with upper layers *only* if the updated (new) ksm continues to support all the crypto capabilities that the old ksm did (see description below for blk_ksm_is_superset() for why this is so). Also introduce blk_ksm_is_superset() which checks whether one ksm's capabilities are a (not necessarily strict) superset of another ksm's. The blk-crypto framework requires that crypto capabilities that were advertised when a bio was created continue to be supported by the device until that bio is ended - in practice this probably means that a device's advertised crypto capabilities can *never* "shrink" (since there's no synchronization between bio creation and when a device may want to change its advertised capabilities) - so a previously advertised crypto capability must always continue to be supported. This function can be used to check that a new ksm is a valid replacement for an old ksm. Signed-off-by: Satya Tangirala <satyat@google.com> Reviewed-by: Eric Biggers <ebiggers@google.com> Acked-by: Jens Axboe <axboe@kernel.dk> Signed-off-by: Mike Snitzer <snitzer@redhat.com>
118 lines
3.7 KiB
C
118 lines
3.7 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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void blk_ksm_intersect_modes(struct blk_keyslot_manager *parent,
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const struct blk_keyslot_manager *child);
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void blk_ksm_init_passthrough(struct blk_keyslot_manager *ksm);
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bool blk_ksm_is_superset(struct blk_keyslot_manager *ksm_superset,
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struct blk_keyslot_manager *ksm_subset);
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void blk_ksm_update_capabilities(struct blk_keyslot_manager *target_ksm,
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struct blk_keyslot_manager *reference_ksm);
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#endif /* __LINUX_KEYSLOT_MANAGER_H */
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