From 20f01f163203666010ee1560852590a0c0572726 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Mon, 24 Jan 2022 13:59:38 -0800 Subject: blk-crypto: show crypto capabilities in sysfs Add sysfs files that expose the inline encryption capabilities of request queues: /sys/block/$disk/queue/crypto/max_dun_bits /sys/block/$disk/queue/crypto/modes/$mode /sys/block/$disk/queue/crypto/num_keyslots Userspace can use these new files to decide what encryption settings to use, or whether to use inline encryption at all. This also brings the crypto capabilities in line with the other queue properties, which are already discoverable via the queue directory in sysfs. Design notes: - Place the new files in a new subdirectory "crypto" to group them together and to avoid complicating the main "queue" directory. This also makes it possible to replace "crypto" with a symlink later if we ever make the blk_crypto_profiles into real kobjects (see below). - It was necessary to define a new kobject that corresponds to the crypto subdirectory. For now, this kobject just contains a pointer to the blk_crypto_profile. Note that multiple queues (and hence multiple such kobjects) may refer to the same blk_crypto_profile. An alternative design would more closely match the current kernel data structures: the blk_crypto_profile could be a kobject itself, located directly under the host controller device's kobject, while /sys/block/$disk/queue/crypto would be a symlink to it. I decided not to do that for now because it would require a lot more changes, such as no longer embedding blk_crypto_profile in other structures, and also because I'm not sure we can rule out moving the crypto capabilities into 'struct queue_limits' in the future. (Even if multiple queues share the same crypto engine, maybe the supported data unit sizes could differ due to other queue properties.) It would also still be possible to switch to that design later without breaking userspace, by replacing the directory with a symlink. - Use "max_dun_bits" instead of "max_dun_bytes". Currently, the kernel internally stores this value in bytes, but that's an implementation detail. It probably makes more sense to talk about this value in bits, and choosing bits is more future-proof. - "modes" is a sub-subdirectory, since there may be multiple supported crypto modes, sysfs is supposed to have one value per file, and it makes sense to group all the mode files together. - Each mode had to be named. The crypto API names like "xts(aes)" are not appropriate because they don't specify the key size. Therefore, I assigned new names. The exact names chosen are arbitrary, but they happen to match the names used in log messages in fs/crypto/. - The "num_keyslots" file is a bit different from the others in that it is only useful to know for performance reasons. However, it's included as it can still be useful. For example, a user might not want to use inline encryption if there aren't very many keyslots. Reviewed-by: Hannes Reinecke Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20220124215938.2769-4-ebiggers@kernel.org Signed-off-by: Jens Axboe --- block/blk-crypto-internal.h | 12 ++++++++++++ 1 file changed, 12 insertions(+) (limited to 'block/blk-crypto-internal.h') diff --git a/block/blk-crypto-internal.h b/block/blk-crypto-internal.h index 2fb0d65a464c..e6818ffaddbf 100644 --- a/block/blk-crypto-internal.h +++ b/block/blk-crypto-internal.h @@ -11,6 +11,7 @@ /* Represents a crypto mode supported by blk-crypto */ struct blk_crypto_mode { + const char *name; /* name of this mode, shown in sysfs */ const char *cipher_str; /* crypto API name (for fallback case) */ unsigned int keysize; /* key size in bytes */ unsigned int ivsize; /* iv size in bytes */ @@ -20,6 +21,10 @@ extern const struct blk_crypto_mode blk_crypto_modes[]; #ifdef CONFIG_BLK_INLINE_ENCRYPTION +int blk_crypto_sysfs_register(struct request_queue *q); + +void blk_crypto_sysfs_unregister(struct request_queue *q); + void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], unsigned int inc); @@ -62,6 +67,13 @@ static inline bool blk_crypto_rq_is_encrypted(struct request *rq) #else /* CONFIG_BLK_INLINE_ENCRYPTION */ +static inline int blk_crypto_sysfs_register(struct request_queue *q) +{ + return 0; +} + +static inline void blk_crypto_sysfs_unregister(struct request_queue *q) { } + static inline bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio) { -- cgit v1.2.3