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106 lines
2.5 KiB
106 lines
2.5 KiB
// SPDX-License-Identifier: GPL-2.0 |
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/* |
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* OFB: Output FeedBack mode |
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* |
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* Copyright (C) 2018 ARM Limited or its affiliates. |
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* All rights reserved. |
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*/ |
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#include <crypto/algapi.h> |
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#include <crypto/internal/cipher.h> |
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#include <crypto/internal/skcipher.h> |
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#include <linux/err.h> |
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#include <linux/init.h> |
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#include <linux/kernel.h> |
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#include <linux/module.h> |
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static int crypto_ofb_crypt(struct skcipher_request *req) |
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{ |
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struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); |
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struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); |
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const unsigned int bsize = crypto_cipher_blocksize(cipher); |
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struct skcipher_walk walk; |
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int err; |
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err = skcipher_walk_virt(&walk, req, false); |
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while (walk.nbytes >= bsize) { |
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const u8 *src = walk.src.virt.addr; |
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u8 *dst = walk.dst.virt.addr; |
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u8 * const iv = walk.iv; |
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unsigned int nbytes = walk.nbytes; |
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do { |
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crypto_cipher_encrypt_one(cipher, iv, iv); |
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crypto_xor_cpy(dst, src, iv, bsize); |
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dst += bsize; |
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src += bsize; |
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} while ((nbytes -= bsize) >= bsize); |
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err = skcipher_walk_done(&walk, nbytes); |
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} |
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if (walk.nbytes) { |
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crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv); |
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crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv, |
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walk.nbytes); |
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err = skcipher_walk_done(&walk, 0); |
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} |
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return err; |
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} |
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static int crypto_ofb_create(struct crypto_template *tmpl, struct rtattr **tb) |
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{ |
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struct skcipher_instance *inst; |
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struct crypto_alg *alg; |
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int err; |
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inst = skcipher_alloc_instance_simple(tmpl, tb); |
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if (IS_ERR(inst)) |
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return PTR_ERR(inst); |
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alg = skcipher_ialg_simple(inst); |
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/* OFB mode is a stream cipher. */ |
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inst->alg.base.cra_blocksize = 1; |
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/* |
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* To simplify the implementation, configure the skcipher walk to only |
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* give a partial block at the very end, never earlier. |
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*/ |
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inst->alg.chunksize = alg->cra_blocksize; |
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inst->alg.encrypt = crypto_ofb_crypt; |
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inst->alg.decrypt = crypto_ofb_crypt; |
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err = skcipher_register_instance(tmpl, inst); |
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if (err) |
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inst->free(inst); |
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return err; |
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} |
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static struct crypto_template crypto_ofb_tmpl = { |
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.name = "ofb", |
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.create = crypto_ofb_create, |
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.module = THIS_MODULE, |
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}; |
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static int __init crypto_ofb_module_init(void) |
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{ |
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return crypto_register_template(&crypto_ofb_tmpl); |
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} |
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static void __exit crypto_ofb_module_exit(void) |
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{ |
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crypto_unregister_template(&crypto_ofb_tmpl); |
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} |
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subsys_initcall(crypto_ofb_module_init); |
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module_exit(crypto_ofb_module_exit); |
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MODULE_LICENSE("GPL"); |
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MODULE_DESCRIPTION("OFB block cipher mode of operation"); |
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MODULE_ALIAS_CRYPTO("ofb"); |
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MODULE_IMPORT_NS(CRYPTO_INTERNAL);
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