diff options
Diffstat (limited to 'block/blk-crypto.c')
| -rw-r--r-- | block/blk-crypto.c | 376 |
1 files changed, 376 insertions, 0 deletions
diff --git a/block/blk-crypto.c b/block/blk-crypto.c new file mode 100644 index 000000000000..25b981257f5f --- /dev/null +++ b/block/blk-crypto.c @@ -0,0 +1,376 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * Copyright 2019 Google LLC + */ + +/* + * Refer to Documentation/block/inline-encryption.rst for detailed explanation. + */ + +#define pr_fmt(fmt) "blk-crypto: " fmt + +#include <linux/bio.h> +#include <linux/blkdev.h> +#include <linux/keyslot-manager.h> +#include <linux/module.h> +#include <linux/slab.h> + +#include "blk-crypto-internal.h" + +const struct blk_crypto_mode blk_crypto_modes[] = { + [BLK_ENCRYPTION_MODE_AES_256_XTS] = { + .keysize = 64, + .ivsize = 16, + }, + [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = { + .keysize = 16, + .ivsize = 16, + }, + [BLK_ENCRYPTION_MODE_ADIANTUM] = { + .keysize = 32, + .ivsize = 32, + }, +}; + +/* + * This number needs to be at least (the number of threads doing IO + * concurrently) * (maximum recursive depth of a bio), so that we don't + * deadlock on crypt_ctx allocations. The default is chosen to be the same + * as the default number of post read contexts in both EXT4 and F2FS. + */ +static int num_prealloc_crypt_ctxs = 128; + +module_param(num_prealloc_crypt_ctxs, int, 0444); +MODULE_PARM_DESC(num_prealloc_crypt_ctxs, + "Number of bio crypto contexts to preallocate"); + +static struct kmem_cache *bio_crypt_ctx_cache; +static mempool_t *bio_crypt_ctx_pool; + +static int __init bio_crypt_ctx_init(void) +{ + size_t i; + + bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0); + if (!bio_crypt_ctx_cache) + goto out_no_mem; + + bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs, + bio_crypt_ctx_cache); + if (!bio_crypt_ctx_pool) + goto out_no_mem; + + /* This is assumed in various places. */ + BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0); + + /* Sanity check that no algorithm exceeds the defined limits. */ + for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) { + BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE); + BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE); + } + + return 0; +out_no_mem: + panic("Failed to allocate mem for bio crypt ctxs\n"); +} +subsys_initcall(bio_crypt_ctx_init); + +void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key, + const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask) +{ + struct bio_crypt_ctx *bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); + + bc->bc_key = key; + memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun)); + + bio->bi_crypt_context = bc; +} + +void __bio_crypt_free_ctx(struct bio *bio) +{ + mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool); + bio->bi_crypt_context = NULL; +} + +void __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask) +{ + dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); + *dst->bi_crypt_context = *src->bi_crypt_context; +} +EXPORT_SYMBOL_GPL(__bio_crypt_clone); + +/* Increments @dun by @inc, treating @dun as a multi-limb integer. */ +void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], + unsigned int inc) +{ + int i; + + for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { + dun[i] += inc; + /* + * If the addition in this limb overflowed, then we need to + * carry 1 into the next limb. Else the carry is 0. + */ + if (dun[i] < inc) + inc = 1; + else + inc = 0; + } +} + +void __bio_crypt_advance(struct bio *bio, unsigned int bytes) +{ + struct bio_crypt_ctx *bc = bio->bi_crypt_context; + + bio_crypt_dun_increment(bc->bc_dun, + bytes >> bc->bc_key->data_unit_size_bits); +} + +/* + * Returns true if @bc->bc_dun plus @bytes converted to data units is equal to + * @next_dun, treating the DUNs as multi-limb integers. + */ +bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc, + unsigned int bytes, + const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) +{ + int i; + unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits; + + for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { + if (bc->bc_dun[i] + carry != next_dun[i]) + return false; + /* + * If the addition in this limb overflowed, then we need to + * carry 1 into the next limb. Else the carry is 0. + */ + if ((bc->bc_dun[i] + carry) < carry) + carry = 1; + else + carry = 0; + } + + /* If the DUN wrapped through 0, don't treat it as contiguous. */ + return carry == 0; +} + +/* + * Checks that two bio crypt contexts are compatible - i.e. that + * they are mergeable except for data_unit_num continuity. + */ +static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1, + struct bio_crypt_ctx *bc2) +{ + if (!bc1) + return !bc2; + + return bc2 && bc1->bc_key == bc2->bc_key; +} + +bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio) +{ + return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context); +} + +/* + * Checks that two bio crypt contexts are compatible, and also + * that their data_unit_nums are continuous (and can hence be merged) + * in the order @bc1 followed by @bc2. + */ +bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes, + struct bio_crypt_ctx *bc2) +{ + if (!bio_crypt_ctx_compatible(bc1, bc2)) + return false; + + return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun); +} + +/* Check that all I/O segments are data unit aligned. */ +static bool bio_crypt_check_alignment(struct bio *bio) +{ + const unsigned int data_unit_size = + bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size; + struct bvec_iter iter; + struct bio_vec bv; + + bio_for_each_segment(bv, bio, iter) { + if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) + return false; + } + + return true; +} + +blk_status_t __blk_crypto_init_request(struct request *rq) +{ + return blk_ksm_get_slot_for_key(rq->q->ksm, 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) +{ + blk_ksm_put_slot(rq->crypt_keyslot); + mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); + blk_crypto_rq_set_defaults(rq); +} + +/** + * __blk_crypto_bio_prep - Prepare bio for inline encryption + * + * @bio_ptr: pointer to original bio pointer + * + * Succeeds if the bio doesn't have inline encryption enabled or if the bio + * crypt context provided for the bio is supported by the underlying device's + * inline encryption hardware. Ends the bio with error otherwise. + * + * Caller must ensure bio has bio_crypt_ctx. + * + * Return: true on success; false on error (and bio->bi_status will be set + * appropriately, and bio_endio() will have been called so bio + * submission should abort). + */ +bool __blk_crypto_bio_prep(struct bio **bio_ptr) +{ + struct bio *bio = *bio_ptr; + const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key; + blk_status_t blk_st = BLK_STS_IOERR; + + /* Error if bio has no data. */ + if (WARN_ON_ONCE(!bio_has_data(bio))) + goto fail; + + if (!bio_crypt_check_alignment(bio)) + goto fail; + + /* + * Success if device supports the encryption context. + */ + if (!blk_ksm_crypto_cfg_supported(bio->bi_disk->queue->ksm, + &bc_key->crypto_cfg)) { + blk_st = BLK_STS_NOTSUPP; + goto fail; + } + + return true; +fail: + (*bio_ptr)->bi_status = blk_st; + bio_endio(*bio_ptr); + return false; +} + +/** + * __blk_crypto_rq_bio_prep - Prepare a request's crypt_ctx when its first bio + * is inserted + * + * @rq: The request to prepare + * @bio: The first bio being inserted into the request + * @gfp_mask: gfp mask + */ +void __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, + gfp_t gfp_mask) +{ + if (!rq->crypt_ctx) + rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); + *rq->crypt_ctx = *bio->bi_crypt_context; +} + +/** + * blk_crypto_init_key() - Prepare a key for use with blk-crypto + * @blk_key: Pointer to the blk_crypto_key to initialize. + * @raw_key: Pointer to the raw key. Must be the correct length for the chosen + * @crypto_mode; see blk_crypto_modes[]. + * @crypto_mode: identifier for the encryption algorithm to use + * @dun_bytes: number of bytes that will be used to specify the DUN when this + * key is used + * @data_unit_size: the data unit size to use for en/decryption + * + * Return: 0 on success, -errno on failure. The caller is responsible for + * zeroizing both blk_key and raw_key when done with them. + */ +int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key, + enum blk_crypto_mode_num crypto_mode, + unsigned int dun_bytes, + unsigned int data_unit_size) +{ + const struct blk_crypto_mode *mode; + + memset(blk_key, 0, sizeof(*blk_key)); + + if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes)) + return -EINVAL; + + mode = &blk_crypto_modes[crypto_mode]; + if (mode->keysize == 0) + return -EINVAL; + + if (dun_bytes == 0 || dun_bytes > BLK_CRYPTO_MAX_IV_SIZE) + return -EINVAL; + + if (!is_power_of_2(data_unit_size)) + return -EINVAL; + + blk_key->crypto_cfg.crypto_mode = crypto_mode; + blk_key->crypto_cfg.dun_bytes = dun_bytes; + blk_key->crypto_cfg.data_unit_size = data_unit_size; + blk_key->data_unit_size_bits = ilog2(data_unit_size); + blk_key->size = mode->keysize; + memcpy(blk_key->raw, raw_key, mode->keysize); + + return 0; +} + +bool blk_crypto_config_supported(struct request_queue *q, + const struct blk_crypto_config *cfg) +{ + return blk_ksm_crypto_cfg_supported(q->ksm, cfg); +} + +/** + * blk_crypto_start_using_key() - Start using a blk_crypto_key on a device + * @key: A key to use on the device + * @q: the request queue for the device + * + * Upper layers must call this function to ensure that the hardware supports + * the key's crypto settings. + * + * Return: 0 on success; -ENOPKG if the hardware doesn't support the key + */ +int blk_crypto_start_using_key(const struct blk_crypto_key *key, + struct request_queue *q) +{ + if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) + return 0; + return -ENOPKG; +} + +/** + * 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 + * might have been programmed into + * @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. + * + * Return: 0 on success or if key is not present in the q's ksm, -err on error. + */ +int blk_crypto_evict_key(struct request_queue *q, + const struct blk_crypto_key *key) +{ + if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) + return blk_ksm_evict_key(q->ksm, key); + + return 0; +} |