From: Christoph Hellwig hch@lst.de

commit fce3caea0f241f5d34855c82c399d5e0e2d91f07 upstream.

Switch all public blk-crypto interfaces to use struct block_device arguments to specify the device they operate on instead of th request_queue, which is a block layer implementation detail.

Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Eric Biggers ebiggers@google.com Link: https://lore.kernel.org/r/20221114042944.1009870-2-hch@lst.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Eric Biggers ebiggers@google.com --- Documentation/block/inline-encryption.rst | 12 ++++++------ block/blk-crypto.c | 24 +++++++++++++---------- drivers/md/dm-table.c | 2 +- fs/crypto/inline_crypt.c | 8 +++----- include/linux/blk-crypto.h | 11 ++++------- 5 files changed, 28 insertions(+), 29 deletions(-)

diff --git a/Documentation/block/inline-encryption.rst b/Documentation/block/inline-encryption.rst index 4d151fbe20583..f9bf18ea65093 100644 --- a/Documentation/block/inline-encryption.rst +++ b/Documentation/block/inline-encryption.rst @@ -142,7 +142,7 @@ Therefore, we also introduce *blk-crypto-fallback*, which is an implementation of inline encryption using the kernel crypto API. blk-crypto-fallback is built into the block layer, so it works on any block device without any special setup. Essentially, when a bio with an encryption context is submitted to a -request_queue that doesn't support that encryption context, the block layer will +block_device that doesn't support that encryption context, the block layer will handle en/decryption of the bio using blk-crypto-fallback.

For encryption, the data cannot be encrypted in-place, as callers usually rely @@ -187,7 +187,7 @@ API presented to users of the block layer

``blk_crypto_config_supported()`` allows users to check ahead of time whether inline encryption with particular crypto settings will work on a particular -request_queue -- either via hardware or via blk-crypto-fallback. This function +block_device -- either via hardware or via blk-crypto-fallback. This function takes in a ``struct blk_crypto_config`` which is like blk_crypto_key, but omits the actual bytes of the key and instead just contains the algorithm, data unit size, etc. This function can be useful if blk-crypto-fallback is disabled. @@ -195,7 +195,7 @@ size, etc. This function can be useful if blk-crypto-fallback is disabled. ``blk_crypto_init_key()`` allows users to initialize a blk_crypto_key.

Users must call ``blk_crypto_start_using_key()`` before actually starting to use -a blk_crypto_key on a request_queue (even if ``blk_crypto_config_supported()`` +a blk_crypto_key on a block_device (even if ``blk_crypto_config_supported()`` was called earlier). This is needed to initialize blk-crypto-fallback if it will be needed. This must not be called from the data path, as this may have to allocate resources, which may deadlock in that case. @@ -207,7 +207,7 @@ for en/decryption. Users don't need to worry about freeing the bio_crypt_ctx later, as that happens automatically when the bio is freed or reset.

Finally, when done using inline encryption with a blk_crypto_key on a -request_queue, users must call ``blk_crypto_evict_key()``. This ensures that +block_device, users must call ``blk_crypto_evict_key()``. This ensures that the key is evicted from all keyslots it may be programmed into and unlinked from any kernel data structures it may be linked into.

@@ -221,9 +221,9 @@ as follows: 5. ``blk_crypto_evict_key()`` (after all I/O has completed) 6. Zeroize the blk_crypto_key (this has no dedicated function)

-If a blk_crypto_key is being used on multiple request_queues, then +If a blk_crypto_key is being used on multiple block_devices, then ``blk_crypto_config_supported()`` (if used), ``blk_crypto_start_using_key()``, -and ``blk_crypto_evict_key()`` must be called on each request_queue. +and ``blk_crypto_evict_key()`` must be called on each block_device.

API presented to device drivers =============================== diff --git a/block/blk-crypto.c b/block/blk-crypto.c index a496aaef85ba4..0047436b63371 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -354,20 +354,21 @@ int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key,

/* * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the - * request queue it's submitted to supports inline crypto, or the + * block_device it's submitted to supports inline crypto, or the * blk-crypto-fallback is enabled and supports the cfg). */ -bool blk_crypto_config_supported(struct request_queue *q, +bool blk_crypto_config_supported(struct block_device *bdev, const struct blk_crypto_config *cfg) { return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || - __blk_crypto_cfg_supported(q->crypto_profile, cfg); + __blk_crypto_cfg_supported(bdev_get_queue(bdev)->crypto_profile, + cfg); }

/** * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device + * @bdev: block device to operate on * @key: A key to use on the device - * @q: the request queue for the device * * Upper layers must call this function to ensure that either the hardware * supports the key's crypto settings, or the crypto API fallback has transforms @@ -379,10 +380,11 @@ bool blk_crypto_config_supported(struct request_queue *q, * blk-crypto-fallback is either disabled or the needed algorithm * is disabled in the crypto API; or another -errno code. */ -int blk_crypto_start_using_key(const struct blk_crypto_key *key, - struct request_queue *q) +int blk_crypto_start_using_key(struct block_device *bdev, + const struct blk_crypto_key *key) { - if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg)) + if (__blk_crypto_cfg_supported(bdev_get_queue(bdev)->crypto_profile, + &key->crypto_cfg)) return 0; return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode); } @@ -390,7 +392,7 @@ int blk_crypto_start_using_key(const struct blk_crypto_key *key, /** * blk_crypto_evict_key() - Evict a key from any inline encryption hardware * it may have been programmed into - * @q: The request queue who's associated inline encryption hardware this key + * @bdev: The block_device who's associated inline encryption hardware this key * might have been programmed into * @key: The key to evict * @@ -400,14 +402,16 @@ int blk_crypto_start_using_key(const struct blk_crypto_key *key, * * Return: 0 on success or if the key wasn't in any keyslot; -errno on error. */ -int blk_crypto_evict_key(struct request_queue *q, +int blk_crypto_evict_key(struct block_device *bdev, const struct blk_crypto_key *key) { + struct request_queue *q = bdev_get_queue(bdev); + if (__blk_crypto_cfg_supported(q->crypto_profile, &key->crypto_cfg)) return __blk_crypto_evict_key(q->crypto_profile, key);

/* - * If the request_queue didn't support the key, then blk-crypto-fallback + * If the block_device didn't support the key, then blk-crypto-fallback * may have been used, so try to evict the key from blk-crypto-fallback. */ return blk_crypto_fallback_evict_key(key); diff --git a/drivers/md/dm-table.c b/drivers/md/dm-table.c index 32b2d3b99d786..c571f2385b57f 100644 --- a/drivers/md/dm-table.c +++ b/drivers/md/dm-table.c @@ -1214,7 +1214,7 @@ static int dm_keyslot_evict_callback(struct dm_target *ti, struct dm_dev *dev, struct dm_keyslot_evict_args *args = data; int err;

- err = blk_crypto_evict_key(bdev_get_queue(dev->bdev), args->key); + err = blk_crypto_evict_key(dev->bdev, args->key); if (!args->err) args->err = err; /* Always try to evict the key from all devices. */ diff --git a/fs/crypto/inline_crypt.c b/fs/crypto/inline_crypt.c index cea8b14007e6a..55c4d8c23d30d 100644 --- a/fs/crypto/inline_crypt.c +++ b/fs/crypto/inline_crypt.c @@ -139,8 +139,7 @@ int fscrypt_select_encryption_impl(struct fscrypt_info *ci) return PTR_ERR(devs);

for (i = 0; i < num_devs; i++) { - if (!blk_crypto_config_supported(bdev_get_queue(devs[i]), - &crypto_cfg)) + if (!blk_crypto_config_supported(devs[i], &crypto_cfg)) goto out_free_devs; }

@@ -184,8 +183,7 @@ int fscrypt_prepare_inline_crypt_key(struct fscrypt_prepared_key *prep_key, goto fail; } for (i = 0; i < num_devs; i++) { - err = blk_crypto_start_using_key(blk_key, - bdev_get_queue(devs[i])); + err = blk_crypto_start_using_key(devs[i], blk_key); if (err) break; } @@ -224,7 +222,7 @@ void fscrypt_destroy_inline_crypt_key(struct super_block *sb, devs = fscrypt_get_devices(sb, &num_devs); if (!IS_ERR(devs)) { for (i = 0; i < num_devs; i++) - blk_crypto_evict_key(bdev_get_queue(devs[i]), blk_key); + blk_crypto_evict_key(devs[i], blk_key); kfree(devs); } kfree_sensitive(blk_key); diff --git a/include/linux/blk-crypto.h b/include/linux/blk-crypto.h index 69b24fe92cbf1..561ca92e204d5 100644 --- a/include/linux/blk-crypto.h +++ b/include/linux/blk-crypto.h @@ -71,9 +71,6 @@ struct bio_crypt_ctx { #include <linux/blk_types.h> #include <linux/blkdev.h>

-struct request; -struct request_queue; - #ifdef CONFIG_BLK_INLINE_ENCRYPTION

static inline bool bio_has_crypt_ctx(struct bio *bio) @@ -94,13 +91,13 @@ int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key, unsigned int dun_bytes, unsigned int data_unit_size);

-int blk_crypto_start_using_key(const struct blk_crypto_key *key, - struct request_queue *q); +int blk_crypto_start_using_key(struct block_device *bdev, + const struct blk_crypto_key *key);

-int blk_crypto_evict_key(struct request_queue *q, +int blk_crypto_evict_key(struct block_device *bdev, const struct blk_crypto_key *key);

-bool blk_crypto_config_supported(struct request_queue *q, +bool blk_crypto_config_supported(struct block_device *bdev, const struct blk_crypto_config *cfg);

#else /* CONFIG_BLK_INLINE_ENCRYPTION */

From: Christoph Hellwig hch@lst.de

commit 3569788c08235c6f3e9e6ca724b2df44787ff487 upstream.

blk_crypto_get_keyslot, blk_crypto_put_keyslot, __blk_crypto_evict_key and __blk_crypto_cfg_supported are only used internally by the blk-crypto code, so move the out of blk-crypto-profile.h, which is included by drivers that supply blk-crypto functionality.

Signed-off-by: Christoph Hellwig hch@lst.de Reviewed-by: Eric Biggers ebiggers@google.com Link: https://lore.kernel.org/r/20221114042944.1009870-4-hch@lst.de Signed-off-by: Jens Axboe axboe@kernel.dk Signed-off-by: Eric Biggers ebiggers@google.com --- block/blk-crypto-internal.h | 12 ++++++++++++ include/linux/blk-crypto-profile.h | 12 ------------ 2 files changed, 12 insertions(+), 12 deletions(-)

diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index e6818ffaddbf8..d31fa80454e49 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -65,6 +65,18 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) return rq->crypt_ctx; }

+blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key, + struct blk_crypto_keyslot **slot_ptr); + +void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot); + +int __blk_crypto_evict_key(struct blk_crypto_profile *profile, + const struct blk_crypto_key *key); + +bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, + const struct blk_crypto_config *cfg); + #else /* CONFIG_BLK_INLINE_ENCRYPTION */

static inline int blk_crypto_sysfs_register(struct request_queue *q) diff --git a/include/linux/blk-crypto-profile.h b/include/linux/blk-crypto-profile.h index bbab65bd54288..e6802b69cdd64 100644 --- a/include/linux/blk-crypto-profile.h +++ b/include/linux/blk-crypto-profile.h @@ -138,18 +138,6 @@ int devm_blk_crypto_profile_init(struct device *dev,

unsigned int blk_crypto_keyslot_index(struct blk_crypto_keyslot *slot);

-blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, - const struct blk_crypto_key *key, - struct blk_crypto_keyslot **slot_ptr); - -void blk_crypto_put_keyslot(struct blk_crypto_keyslot *slot); - -bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, - const struct blk_crypto_config *cfg); - -int __blk_crypto_evict_key(struct blk_crypto_profile *profile, - const struct blk_crypto_key *key); - void blk_crypto_reprogram_all_keys(struct blk_crypto_profile *profile);

void blk_crypto_profile_destroy(struct blk_crypto_profile *profile);

From: Eric Biggers ebiggers@google.com

commit 9cd1e566676bbcb8a126acd921e4e194e6339603 upstream.

Once all I/O using a blk_crypto_key has completed, filesystems can call blk_crypto_evict_key(). However, the block layer currently doesn't call blk_crypto_put_keyslot() until the request is being freed, which happens after upper layers have been told (via bio_endio()) the I/O has completed. This causes a race condition where blk_crypto_evict_key() can see 'slot_refs != 0' without there being an actual bug.

This makes __blk_crypto_evict_key() hit the 'WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)' and return without doing anything, eventually causing a use-after-free in blk_crypto_reprogram_all_keys(). (This is a very rare bug and has only been seen when per-file keys are being used with fscrypt.)

There are two options to fix this: either release the keyslot before bio_endio() is called on the request's last bio, or make __blk_crypto_evict_key() ignore slot_refs. Let's go with the first solution, since it preserves the ability to report bugs (via WARN_ON_ONCE) where a key is evicted while still in-use.

Fixes: a892c8d52c02 ("block: Inline encryption support for blk-mq") Cc: stable@vger.kernel.org Reviewed-by: Nathan Huckleberry nhuck@google.com Reviewed-by: Christoph Hellwig hch@lst.de Signed-off-by: Eric Biggers ebiggers@google.com Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk --- block/blk-crypto-internal.h | 25 +++++++++++++++++++++---- block/blk-crypto.c | 24 ++++++++++++------------ block/blk-merge.c | 2 ++ block/blk-mq.c | 15 ++++++++++++++- 4 files changed, 49 insertions(+), 17 deletions(-)

diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index d31fa80454e49..8ac5597dc69c3 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -65,6 +65,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) return rq->crypt_ctx; }

+static inline bool blk_crypto_rq_has_keyslot(struct request *rq) +{ + return rq->crypt_keyslot; +} + blk_status_t blk_crypto_get_keyslot(struct blk_crypto_profile *profile, const struct blk_crypto_key *key, struct blk_crypto_keyslot **slot_ptr); @@ -117,6 +122,11 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) return false; }

+static inline bool blk_crypto_rq_has_keyslot(struct request *rq) +{ + return false; +} + #endif /* CONFIG_BLK_INLINE_ENCRYPTION */

void __bio_crypt_advance(struct bio *bio, unsigned int bytes); @@ -151,14 +161,21 @@ static inline bool blk_crypto_bio_prep(struct bio **bio_ptr) return true; }

-blk_status_t __blk_crypto_init_request(struct request *rq); -static inline blk_status_t blk_crypto_init_request(struct request *rq) +blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq); +static inline blk_status_t blk_crypto_rq_get_keyslot(struct request *rq) { if (blk_crypto_rq_is_encrypted(rq)) - return __blk_crypto_init_request(rq); + return __blk_crypto_rq_get_keyslot(rq); return BLK_STS_OK; }

+void __blk_crypto_rq_put_keyslot(struct request *rq); +static inline void blk_crypto_rq_put_keyslot(struct request *rq) +{ + if (blk_crypto_rq_has_keyslot(rq)) + __blk_crypto_rq_put_keyslot(rq); +} + void __blk_crypto_free_request(struct request *rq); static inline void blk_crypto_free_request(struct request *rq) { @@ -197,7 +214,7 @@ static inline blk_status_t blk_crypto_insert_cloned_request(struct request *rq) {

if (blk_crypto_rq_is_encrypted(rq)) - return blk_crypto_init_request(rq); + return blk_crypto_rq_get_keyslot(rq); return BLK_STS_OK; }

diff --git a/block/blk-crypto.c b/block/blk-crypto.c index 6a461f4d676a3..19d81abf94fd8 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -218,27 +218,27 @@ static bool bio_crypt_check_alignment(struct bio *bio) return true; }

-blk_status_t __blk_crypto_init_request(struct request *rq) +blk_status_t __blk_crypto_rq_get_keyslot(struct request *rq) { return blk_crypto_get_keyslot(rq->q->crypto_profile, rq->crypt_ctx->bc_key, &rq->crypt_keyslot); }

-/** - * __blk_crypto_free_request - Uninitialize the crypto fields of a request. - * - * @rq: The request whose crypto fields to uninitialize. - * - * Completely uninitializes the crypto fields of a request. If a keyslot has - * been programmed into some inline encryption hardware, that keyslot is - * released. The rq->crypt_ctx is also freed. - */ -void __blk_crypto_free_request(struct request *rq) +void __blk_crypto_rq_put_keyslot(struct request *rq) { blk_crypto_put_keyslot(rq->crypt_keyslot); + rq->crypt_keyslot = NULL; +} + +void __blk_crypto_free_request(struct request *rq) +{ + /* The keyslot, if one was needed, should have been released earlier. */ + if (WARN_ON_ONCE(rq->crypt_keyslot)) + __blk_crypto_rq_put_keyslot(rq); + mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); - blk_crypto_rq_set_defaults(rq); + rq->crypt_ctx = NULL; }

/** diff --git a/block/blk-merge.c b/block/blk-merge.c index 17ac532105a97..cc7f6a4a255c9 100644 --- a/block/blk-merge.c +++ b/block/blk-merge.c @@ -863,6 +863,8 @@ static struct request *attempt_merge(struct request_queue *q, if (!blk_discard_mergable(req)) elv_merge_requests(q, req, next);

+ blk_crypto_rq_put_keyslot(next); + /* * 'next' is going away, so update stats accordingly */ diff --git a/block/blk-mq.c b/block/blk-mq.c index 1b04a1c48ee50..b3ebf604b1dd5 100644 --- a/block/blk-mq.c +++ b/block/blk-mq.c @@ -808,6 +808,12 @@ static void blk_complete_request(struct request *req) req->q->integrity.profile->complete_fn(req, total_bytes); #endif

+ /* + * Upper layers may call blk_crypto_evict_key() anytime after the last + * bio_endio(). Therefore, the keyslot must be released before that. + */ + blk_crypto_rq_put_keyslot(req); + blk_account_io_completion(req, total_bytes);

do { @@ -873,6 +879,13 @@ bool blk_update_request(struct request *req, blk_status_t error, req->q->integrity.profile->complete_fn(req, nr_bytes); #endif

+ /* + * Upper layers may call blk_crypto_evict_key() anytime after the last + * bio_endio(). Therefore, the keyslot must be released before that. + */ + if (blk_crypto_rq_has_keyslot(req) && nr_bytes >= blk_rq_bytes(req)) + __blk_crypto_rq_put_keyslot(req); + if (unlikely(error && !blk_rq_is_passthrough(req) && !(req->rq_flags & RQF_QUIET)) && !test_bit(GD_DEAD, &req->q->disk->state)) { @@ -2955,7 +2968,7 @@ void blk_mq_submit_bio(struct bio *bio)

blk_mq_bio_to_request(rq, bio, nr_segs);

- ret = blk_crypto_init_request(rq); + ret = blk_crypto_rq_get_keyslot(rq); if (ret != BLK_STS_OK) { bio->bi_status = ret; bio_endio(bio);

From: Eric Biggers ebiggers@google.com

commit 5c7cb94452901a93e90c2230632e2c12a681bc92 upstream.

If blk_crypto_evict_key() sees that the key is still in-use (due to a bug) or that ->keyslot_evict failed, it currently just returns while leaving the key linked into the keyslot management structures.

However, blk_crypto_evict_key() is only called in contexts such as inode eviction where failure is not an option. So actually the caller proceeds with freeing the blk_crypto_key regardless of the return value of blk_crypto_evict_key().

These two assumptions don't match, and the result is that there can be a use-after-free in blk_crypto_reprogram_all_keys() after one of these errors occurs. (Note, these errors *shouldn't* happen; we're just talking about what happens if they do anyway.)

Fix this by making blk_crypto_evict_key() unlink the key from the keyslot management structures even on failure.

Also improve some comments.

Fixes: 1b2628397058 ("block: Keyslot Manager for Inline Encryption") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers ebiggers@google.com Reviewed-by: Christoph Hellwig hch@lst.de Link: https://lore.kernel.org/r/20230315183907.53675-2-ebiggers@kernel.org Signed-off-by: Jens Axboe axboe@kernel.dk --- block/blk-crypto-profile.c | 46 +++++++++++++++++--------------------- block/blk-crypto.c | 28 ++++++++++++++++------- 2 files changed, 41 insertions(+), 33 deletions(-)

diff --git a/block/blk-crypto-profile.c b/block/blk-crypto-profile.c index 0307fb0d95d34..3290c03c9918d 100644 --- a/block/blk-crypto-profile.c +++ b/block/blk-crypto-profile.c @@ -354,28 +354,16 @@ bool __blk_crypto_cfg_supported(struct blk_crypto_profile *profile, 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. +/* + * This is an internal function that evicts a key from an inline encryption + * device that can be either a real device or the blk-crypto-fallback "device". + * It is used only by blk_crypto_evict_key(); see that function for details. */ int __blk_crypto_evict_key(struct blk_crypto_profile *profile, const struct blk_crypto_key *key) { struct blk_crypto_keyslot *slot; - int err = 0; + int err;

if (profile->num_slots == 0) { if (profile->ll_ops.keyslot_evict) { @@ -389,22 +377,30 @@ int __blk_crypto_evict_key(struct blk_crypto_profile *profile,

blk_crypto_hw_enter(profile); slot = blk_crypto_find_keyslot(profile, key); - if (!slot) - goto out_unlock; + if (!slot) { + /* + * Not an error, since a key not in use by I/O is not guaranteed + * to be in a keyslot. There can be more keys than keyslots. + */ + err = 0; + goto out; + }

if (WARN_ON_ONCE(atomic_read(&slot->slot_refs) != 0)) { + /* BUG: key is still in use by I/O */ err = -EBUSY; - goto out_unlock; + goto out_remove; } err = profile->ll_ops.keyslot_evict(profile, key, blk_crypto_keyslot_index(slot)); - if (err) - goto out_unlock; - +out_remove: + /* + * Callers free the key even on error, so unlink the key from the hash + * table and clear slot->key even on error. + */ hlist_del(&slot->hash_node); slot->key = NULL; - err = 0; -out_unlock: +out: blk_crypto_hw_exit(profile); return err; } diff --git a/block/blk-crypto.c b/block/blk-crypto.c index 099381d221542..6733286d506f6 100644 --- a/block/blk-crypto.c +++ b/block/blk-crypto.c @@ -394,15 +394,19 @@ int blk_crypto_start_using_key(struct block_device *bdev, }

/** - * blk_crypto_evict_key() - Evict a key from any inline encryption hardware - * it may have been programmed into - * @bdev: The block_device who's associated inline encryption hardware this key - * might have been programmed into - * @key: The key to evict + * blk_crypto_evict_key() - Evict a blk_crypto_key from a block_device + * @bdev: a block_device on which I/O using the key may have been done + * @key: the key to evict * - * Upper layers (filesystems) must call this function to ensure that a key is - * evicted from any hardware that it might have been programmed into. The key - * must not be in use by any in-flight IO when this function is called. + * For a given block_device, this function removes the given blk_crypto_key from + * the keyslot management structures and evicts it from any underlying hardware + * keyslot(s) or blk-crypto-fallback keyslot it may have been programmed into. + * + * Upper layers must call this before freeing the blk_crypto_key. It must be + * called for every block_device the key may have been used on. The key must no + * longer be in use by any I/O when this function is called. + * + * Context: May sleep. */ void blk_crypto_evict_key(struct block_device *bdev, const struct blk_crypto_key *key) @@ -414,6 +418,14 @@ void blk_crypto_evict_key(struct block_device *bdev, err = __blk_crypto_evict_key(q->crypto_profile, key); else err = blk_crypto_fallback_evict_key(key); + /* + * An error can only occur here if the key failed to be evicted from a + * keyslot (due to a hardware or driver issue) or is allegedly still in + * use by I/O (due to a kernel bug). Even in these cases, the key is + * still unlinked from the keyslot management structures, and the caller + * is allowed and expected to free it right away. There's nothing + * callers can do to handle errors, so just log them and return void. + */ if (err) pr_warn_ratelimited("%pg: error %d evicting key\n", bdev, err); }