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412 lines
12 KiB
412 lines
12 KiB
// 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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/* |
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* Refer to Documentation/block/inline-encryption.rst for detailed explanation. |
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*/ |
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#define pr_fmt(fmt) "blk-crypto: " fmt |
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#include <linux/bio.h> |
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#include <linux/blkdev.h> |
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#include <linux/keyslot-manager.h> |
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#include <linux/module.h> |
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#include <linux/slab.h> |
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#include "blk-crypto-internal.h" |
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const struct blk_crypto_mode blk_crypto_modes[] = { |
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[BLK_ENCRYPTION_MODE_AES_256_XTS] = { |
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.cipher_str = "xts(aes)", |
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.keysize = 64, |
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.ivsize = 16, |
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}, |
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[BLK_ENCRYPTION_MODE_AES_128_CBC_ESSIV] = { |
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.cipher_str = "essiv(cbc(aes),sha256)", |
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.keysize = 16, |
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.ivsize = 16, |
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}, |
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[BLK_ENCRYPTION_MODE_ADIANTUM] = { |
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.cipher_str = "adiantum(xchacha12,aes)", |
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.keysize = 32, |
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.ivsize = 32, |
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}, |
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}; |
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/* |
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* This number needs to be at least (the number of threads doing IO |
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* concurrently) * (maximum recursive depth of a bio), so that we don't |
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* deadlock on crypt_ctx allocations. The default is chosen to be the same |
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* as the default number of post read contexts in both EXT4 and F2FS. |
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*/ |
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static int num_prealloc_crypt_ctxs = 128; |
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module_param(num_prealloc_crypt_ctxs, int, 0444); |
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MODULE_PARM_DESC(num_prealloc_crypt_ctxs, |
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"Number of bio crypto contexts to preallocate"); |
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static struct kmem_cache *bio_crypt_ctx_cache; |
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static mempool_t *bio_crypt_ctx_pool; |
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static int __init bio_crypt_ctx_init(void) |
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{ |
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size_t i; |
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bio_crypt_ctx_cache = KMEM_CACHE(bio_crypt_ctx, 0); |
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if (!bio_crypt_ctx_cache) |
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goto out_no_mem; |
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bio_crypt_ctx_pool = mempool_create_slab_pool(num_prealloc_crypt_ctxs, |
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bio_crypt_ctx_cache); |
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if (!bio_crypt_ctx_pool) |
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goto out_no_mem; |
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/* This is assumed in various places. */ |
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BUILD_BUG_ON(BLK_ENCRYPTION_MODE_INVALID != 0); |
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/* Sanity check that no algorithm exceeds the defined limits. */ |
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for (i = 0; i < BLK_ENCRYPTION_MODE_MAX; i++) { |
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BUG_ON(blk_crypto_modes[i].keysize > BLK_CRYPTO_MAX_KEY_SIZE); |
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BUG_ON(blk_crypto_modes[i].ivsize > BLK_CRYPTO_MAX_IV_SIZE); |
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} |
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return 0; |
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out_no_mem: |
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panic("Failed to allocate mem for bio crypt ctxs\n"); |
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} |
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subsys_initcall(bio_crypt_ctx_init); |
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void bio_crypt_set_ctx(struct bio *bio, const struct blk_crypto_key *key, |
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const u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], gfp_t gfp_mask) |
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{ |
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struct bio_crypt_ctx *bc; |
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/* |
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* The caller must use a gfp_mask that contains __GFP_DIRECT_RECLAIM so |
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* that the mempool_alloc() can't fail. |
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*/ |
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WARN_ON_ONCE(!(gfp_mask & __GFP_DIRECT_RECLAIM)); |
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bc = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); |
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bc->bc_key = key; |
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memcpy(bc->bc_dun, dun, sizeof(bc->bc_dun)); |
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bio->bi_crypt_context = bc; |
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} |
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void __bio_crypt_free_ctx(struct bio *bio) |
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{ |
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mempool_free(bio->bi_crypt_context, bio_crypt_ctx_pool); |
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bio->bi_crypt_context = NULL; |
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} |
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int __bio_crypt_clone(struct bio *dst, struct bio *src, gfp_t gfp_mask) |
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{ |
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dst->bi_crypt_context = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); |
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if (!dst->bi_crypt_context) |
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return -ENOMEM; |
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*dst->bi_crypt_context = *src->bi_crypt_context; |
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return 0; |
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} |
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EXPORT_SYMBOL_GPL(__bio_crypt_clone); |
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/* Increments @dun by @inc, treating @dun as a multi-limb integer. */ |
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void bio_crypt_dun_increment(u64 dun[BLK_CRYPTO_DUN_ARRAY_SIZE], |
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unsigned int inc) |
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{ |
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int i; |
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for (i = 0; inc && i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { |
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dun[i] += inc; |
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/* |
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* If the addition in this limb overflowed, then we need to |
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* carry 1 into the next limb. Else the carry is 0. |
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*/ |
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if (dun[i] < inc) |
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inc = 1; |
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else |
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inc = 0; |
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} |
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} |
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void __bio_crypt_advance(struct bio *bio, unsigned int bytes) |
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{ |
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struct bio_crypt_ctx *bc = bio->bi_crypt_context; |
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bio_crypt_dun_increment(bc->bc_dun, |
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bytes >> bc->bc_key->data_unit_size_bits); |
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} |
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/* |
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* Returns true if @bc->bc_dun plus @bytes converted to data units is equal to |
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* @next_dun, treating the DUNs as multi-limb integers. |
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*/ |
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bool bio_crypt_dun_is_contiguous(const struct bio_crypt_ctx *bc, |
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unsigned int bytes, |
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const u64 next_dun[BLK_CRYPTO_DUN_ARRAY_SIZE]) |
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{ |
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int i; |
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unsigned int carry = bytes >> bc->bc_key->data_unit_size_bits; |
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for (i = 0; i < BLK_CRYPTO_DUN_ARRAY_SIZE; i++) { |
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if (bc->bc_dun[i] + carry != next_dun[i]) |
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return false; |
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/* |
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* If the addition in this limb overflowed, then we need to |
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* carry 1 into the next limb. Else the carry is 0. |
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*/ |
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if ((bc->bc_dun[i] + carry) < carry) |
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carry = 1; |
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else |
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carry = 0; |
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} |
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/* If the DUN wrapped through 0, don't treat it as contiguous. */ |
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return carry == 0; |
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} |
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/* |
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* Checks that two bio crypt contexts are compatible - i.e. that |
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* they are mergeable except for data_unit_num continuity. |
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*/ |
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static bool bio_crypt_ctx_compatible(struct bio_crypt_ctx *bc1, |
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struct bio_crypt_ctx *bc2) |
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{ |
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if (!bc1) |
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return !bc2; |
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return bc2 && bc1->bc_key == bc2->bc_key; |
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} |
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bool bio_crypt_rq_ctx_compatible(struct request *rq, struct bio *bio) |
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{ |
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return bio_crypt_ctx_compatible(rq->crypt_ctx, bio->bi_crypt_context); |
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} |
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/* |
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* Checks that two bio crypt contexts are compatible, and also |
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* that their data_unit_nums are continuous (and can hence be merged) |
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* in the order @bc1 followed by @bc2. |
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*/ |
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bool bio_crypt_ctx_mergeable(struct bio_crypt_ctx *bc1, unsigned int bc1_bytes, |
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struct bio_crypt_ctx *bc2) |
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{ |
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if (!bio_crypt_ctx_compatible(bc1, bc2)) |
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return false; |
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return !bc1 || bio_crypt_dun_is_contiguous(bc1, bc1_bytes, bc2->bc_dun); |
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} |
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/* Check that all I/O segments are data unit aligned. */ |
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static bool bio_crypt_check_alignment(struct bio *bio) |
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{ |
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const unsigned int data_unit_size = |
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bio->bi_crypt_context->bc_key->crypto_cfg.data_unit_size; |
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struct bvec_iter iter; |
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struct bio_vec bv; |
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bio_for_each_segment(bv, bio, iter) { |
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if (!IS_ALIGNED(bv.bv_len | bv.bv_offset, data_unit_size)) |
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return false; |
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} |
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return true; |
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} |
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blk_status_t __blk_crypto_init_request(struct request *rq) |
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{ |
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return blk_ksm_get_slot_for_key(rq->q->ksm, rq->crypt_ctx->bc_key, |
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&rq->crypt_keyslot); |
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} |
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/** |
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* __blk_crypto_free_request - Uninitialize the crypto fields of a request. |
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* |
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* @rq: The request whose crypto fields to uninitialize. |
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* |
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* Completely uninitializes the crypto fields of a request. If a keyslot has |
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* been programmed into some inline encryption hardware, that keyslot is |
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* released. The rq->crypt_ctx is also freed. |
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*/ |
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void __blk_crypto_free_request(struct request *rq) |
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{ |
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blk_ksm_put_slot(rq->crypt_keyslot); |
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mempool_free(rq->crypt_ctx, bio_crypt_ctx_pool); |
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blk_crypto_rq_set_defaults(rq); |
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} |
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/** |
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* __blk_crypto_bio_prep - Prepare bio for inline encryption |
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* |
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* @bio_ptr: pointer to original bio pointer |
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* |
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* If the bio crypt context provided for the bio is supported by the underlying |
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* device's inline encryption hardware, do nothing. |
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* |
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* Otherwise, try to perform en/decryption for this bio by falling back to the |
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* kernel crypto API. When the crypto API fallback is used for encryption, |
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* blk-crypto may choose to split the bio into 2 - the first one that will |
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* continue to be processed and the second one that will be resubmitted via |
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* submit_bio_noacct. A bounce bio will be allocated to encrypt the contents |
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* of the aforementioned "first one", and *bio_ptr will be updated to this |
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* bounce bio. |
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* |
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* Caller must ensure bio has bio_crypt_ctx. |
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* |
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* Return: true on success; false on error (and bio->bi_status will be set |
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* appropriately, and bio_endio() will have been called so bio |
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* submission should abort). |
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*/ |
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bool __blk_crypto_bio_prep(struct bio **bio_ptr) |
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{ |
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struct bio *bio = *bio_ptr; |
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const struct blk_crypto_key *bc_key = bio->bi_crypt_context->bc_key; |
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/* Error if bio has no data. */ |
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if (WARN_ON_ONCE(!bio_has_data(bio))) { |
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bio->bi_status = BLK_STS_IOERR; |
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goto fail; |
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} |
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if (!bio_crypt_check_alignment(bio)) { |
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bio->bi_status = BLK_STS_IOERR; |
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goto fail; |
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} |
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/* |
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* Success if device supports the encryption context, or if we succeeded |
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* in falling back to the crypto API. |
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*/ |
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if (blk_ksm_crypto_cfg_supported(bio->bi_bdev->bd_disk->queue->ksm, |
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&bc_key->crypto_cfg)) |
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return true; |
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if (blk_crypto_fallback_bio_prep(bio_ptr)) |
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return true; |
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fail: |
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bio_endio(*bio_ptr); |
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return false; |
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} |
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int __blk_crypto_rq_bio_prep(struct request *rq, struct bio *bio, |
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gfp_t gfp_mask) |
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{ |
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if (!rq->crypt_ctx) { |
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rq->crypt_ctx = mempool_alloc(bio_crypt_ctx_pool, gfp_mask); |
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if (!rq->crypt_ctx) |
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return -ENOMEM; |
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} |
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*rq->crypt_ctx = *bio->bi_crypt_context; |
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return 0; |
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} |
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/** |
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* blk_crypto_init_key() - Prepare a key for use with blk-crypto |
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* @blk_key: Pointer to the blk_crypto_key to initialize. |
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* @raw_key: Pointer to the raw key. Must be the correct length for the chosen |
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* @crypto_mode; see blk_crypto_modes[]. |
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* @crypto_mode: identifier for the encryption algorithm to use |
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* @dun_bytes: number of bytes that will be used to specify the DUN when this |
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* key is used |
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* @data_unit_size: the data unit size to use for en/decryption |
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* |
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* Return: 0 on success, -errno on failure. The caller is responsible for |
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* zeroizing both blk_key and raw_key when done with them. |
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*/ |
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int blk_crypto_init_key(struct blk_crypto_key *blk_key, const u8 *raw_key, |
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enum blk_crypto_mode_num crypto_mode, |
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unsigned int dun_bytes, |
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unsigned int data_unit_size) |
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{ |
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const struct blk_crypto_mode *mode; |
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memset(blk_key, 0, sizeof(*blk_key)); |
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if (crypto_mode >= ARRAY_SIZE(blk_crypto_modes)) |
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return -EINVAL; |
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mode = &blk_crypto_modes[crypto_mode]; |
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if (mode->keysize == 0) |
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return -EINVAL; |
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if (dun_bytes == 0 || dun_bytes > mode->ivsize) |
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return -EINVAL; |
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if (!is_power_of_2(data_unit_size)) |
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return -EINVAL; |
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blk_key->crypto_cfg.crypto_mode = crypto_mode; |
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blk_key->crypto_cfg.dun_bytes = dun_bytes; |
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blk_key->crypto_cfg.data_unit_size = data_unit_size; |
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blk_key->data_unit_size_bits = ilog2(data_unit_size); |
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blk_key->size = mode->keysize; |
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memcpy(blk_key->raw, raw_key, mode->keysize); |
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return 0; |
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} |
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/* |
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* Check if bios with @cfg can be en/decrypted by blk-crypto (i.e. either the |
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* request queue it's submitted to supports inline crypto, or the |
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* blk-crypto-fallback is enabled and supports the cfg). |
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*/ |
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bool blk_crypto_config_supported(struct request_queue *q, |
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const struct blk_crypto_config *cfg) |
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{ |
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return IS_ENABLED(CONFIG_BLK_INLINE_ENCRYPTION_FALLBACK) || |
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blk_ksm_crypto_cfg_supported(q->ksm, cfg); |
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} |
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/** |
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* blk_crypto_start_using_key() - Start using a blk_crypto_key on a device |
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* @key: A key to use on the device |
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* @q: the request queue for the device |
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* |
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* Upper layers must call this function to ensure that either the hardware |
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* supports the key's crypto settings, or the crypto API fallback has transforms |
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* for the needed mode allocated and ready to go. This function may allocate |
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* an skcipher, and *should not* be called from the data path, since that might |
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* cause a deadlock |
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* |
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* Return: 0 on success; -ENOPKG if the hardware doesn't support the key and |
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* blk-crypto-fallback is either disabled or the needed algorithm |
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* is disabled in the crypto API; or another -errno code. |
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*/ |
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int blk_crypto_start_using_key(const struct blk_crypto_key *key, |
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struct request_queue *q) |
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{ |
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if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) |
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return 0; |
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return blk_crypto_fallback_start_using_mode(key->crypto_cfg.crypto_mode); |
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} |
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/** |
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* blk_crypto_evict_key() - Evict a key from any inline encryption hardware |
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* it may have been programmed into |
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* @q: The request queue who's associated inline encryption hardware this key |
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* might have been programmed into |
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* @key: The key to evict |
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* |
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* Upper layers (filesystems) must call this function to ensure that a key is |
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* evicted from any hardware that it might have been programmed into. The key |
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* must not be in use by any in-flight IO when this function is called. |
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* |
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* Return: 0 on success or if key is not present in the q's ksm, -err on error. |
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*/ |
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int blk_crypto_evict_key(struct request_queue *q, |
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const struct blk_crypto_key *key) |
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{ |
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if (blk_ksm_crypto_cfg_supported(q->ksm, &key->crypto_cfg)) |
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return blk_ksm_evict_key(q->ksm, key); |
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/* |
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* If the request queue's associated inline encryption hardware didn't |
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* have support for the key, then the key might have been programmed |
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* into the fallback keyslot manager, so try to evict from there. |
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*/ |
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return blk_crypto_fallback_evict_key(key); |
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} |
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EXPORT_SYMBOL_GPL(blk_crypto_evict_key);
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