| // 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/blk-crypto-profile.h> |
| #include <linux/module.h> |
| #include <linux/ratelimit.h> |
| #include <linux/slab.h> |
| |
| #include "blk-crypto-internal.h" |
| |
| const struct blk_crypto_mode blk_crypto_modes[] = { |
| [BLK_ENCRYPTION_MODE_AES_256_XTS] = { |
| .name = "AES-256-XTS", |
| .cipher_str = "xts(aes)", |
| .keysize = 64, |
| .ivsize = 16, |
| }, |
| [BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = { |
| .name = "AES-128-CBC-ESSIV", |
| .cipher_str = "essiv(cbc(aes),sha256)", |
| .keysize = 16, |
| .ivsize = 16, |
| }, |
| [BLK_ENCRYPTION_MODE_ADIANTUM] = { |
| .name = "Adiantum", |
| .cipher_str = "adiantum(xchacha12,aes)", |
| .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; |
| |
| /* |
| * The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so |
| * that the mempool_alloc() can't fail. |
| */ |
| WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM)); |
| |
| 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; |
| } |
| |
| int __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); |
| if (!dst->bi_crypt_context) |
| return -ENOMEM; |
| *dst->bi_crypt_context = *src->bi_crypt_context; |
| return 0; |
| } |
| |
| /* 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_rq_get_keyslot(struct request *rq) |
| { |
| return blk_crypto_get_keyslot(rq->q->crypto_profile, |
| rq->crypt_ctx->bc_key, |
| &rq->crypt_keyslot); |
| } |
| |
| 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); |
| rq->crypt_ctx = NULL; |
| } |
| |
| /** |
| * __blk_crypto_bio_prep - Prepare bio for inline encryption |
| * |
| * @bio_ptr: pointer to original bio pointer |
| * |
| * If the bio crypt context provided for the bio is supported by the underlying |
| * device's inline encryption hardware, do nothing. |
| * |
| * Otherwise, try to perform en/decryption for this bio by falling back to the |
| * kernel crypto API. When the crypto API fallback is used for encryption, |
| * blk-crypto may choose to split the bio into 2 - the first one that will |
| * continue to be processed and the second one that will be resubmitted via |
| * submit_bio_noacct. A bounce bio will be allocated to encrypt the contents |
| * of the aforementioned "first one", and *bio_ptr will be updated to this |
| * bounce bio. |
| * |
| * 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; |
| |
| /* Error if bio has no data. */ |
| if (WARN_ON_ONCE(!bio_has_data(bio))) { |
| bio->bi_status = BLK_STS_IOERR; |
| goto fail; |
| } |
| |
| if (!bio_crypt_check_alignment(bio)) { |
| bio->bi_status = BLK_STS_IOERR; |
| goto fail; |
| } |
| |
| /* |
| * Success if device supports the encryption context, or if we succeeded |
| * in falling back to the crypto API. |
| */ |
| if (blk_crypto_config_supported_natively(bio->bi_bdev, |
| &bc_key->crypto_cfg)) |
| return true; |
| if (blk_crypto_fallback_bio_prep(bio_ptr)) |
| return true; |
| fail: |
| bio_endio(*bio_ptr); |
| return false; |
| } |
| |
| int __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); |
| if (!rq->crypt_ctx) |
| return -ENOMEM; |
| } |
| *rq->crypt_ctx = *bio->bi_crypt_context; |
| return 0; |
| } |
| |
| /** |
| * 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 > mode->ivsize) |
| 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_natively(struct block_device *bdev, |
| const struct blk_crypto_config *cfg) |
| { |
| return __blk_crypto_cfg_supported(bdev_get_queue(bdev)->crypto_profile, |
| cfg); |
| } |
| |
| /* |
| * Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either 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 block_device *bdev, |
| const struct blk_crypto_config *cfg) |
| { |
| return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || |
| blk_crypto_config_supported_natively(bdev, 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 |
| * |
| * 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 |
| * for the needed mode allocated and ready to go. This function may allocate |
| * an skcipher, and *should not* be called from the data path, since that might |
| * cause a deadlock |
| * |
| * Return: 0 on success; -ENOPKG if the hardware doesn't support the key and |
| * 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(struct block_device *bdev, |
| const struct blk_crypto_key *key) |
| { |
| if (blk_crypto_config_supported_natively(bdev, &key->crypto_cfg)) |
| return 0; |
| return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode); |
| } |
| |
| /** |
| * 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 |
| * |
| * 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) |
| { |
| struct request_queue *q = bdev_get_queue(bdev); |
| int err; |
| |
| if (blk_crypto_config_supported_natively(bdev, &key->crypto_cfg)) |
| 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); |
| } |
| EXPORT_SYMBOL_GPL(blk_crypto_evict_key); |