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1// SPDX-License-Identifier: GPL-2.0-or-later2/*3 * PCBC: Propagating Cipher Block Chaining mode4 *5 * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.6 * Written by David Howells (dhowells@redhat.com)7 *8 * Derived from cbc.c9 * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>10 */11 12#include <crypto/algapi.h>13#include <crypto/internal/cipher.h>14#include <crypto/internal/skcipher.h>15#include <linux/err.h>16#include <linux/init.h>17#include <linux/kernel.h>18#include <linux/module.h>19 20static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,21 struct skcipher_walk *walk,22 struct crypto_cipher *tfm)23{24 int bsize = crypto_cipher_blocksize(tfm);25 unsigned int nbytes = walk->nbytes;26 u8 *src = walk->src.virt.addr;27 u8 *dst = walk->dst.virt.addr;28 u8 * const iv = walk->iv;29 30 do {31 crypto_xor(iv, src, bsize);32 crypto_cipher_encrypt_one(tfm, dst, iv);33 crypto_xor_cpy(iv, dst, src, bsize);34 35 src += bsize;36 dst += bsize;37 } while ((nbytes -= bsize) >= bsize);38 39 return nbytes;40}41 42static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,43 struct skcipher_walk *walk,44 struct crypto_cipher *tfm)45{46 int bsize = crypto_cipher_blocksize(tfm);47 unsigned int nbytes = walk->nbytes;48 u8 *src = walk->src.virt.addr;49 u8 * const iv = walk->iv;50 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];51 52 do {53 memcpy(tmpbuf, src, bsize);54 crypto_xor(iv, src, bsize);55 crypto_cipher_encrypt_one(tfm, src, iv);56 crypto_xor_cpy(iv, tmpbuf, src, bsize);57 58 src += bsize;59 } while ((nbytes -= bsize) >= bsize);60 61 return nbytes;62}63 64static int crypto_pcbc_encrypt(struct skcipher_request *req)65{66 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);67 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);68 struct skcipher_walk walk;69 unsigned int nbytes;70 int err;71 72 err = skcipher_walk_virt(&walk, req, false);73 74 while (walk.nbytes) {75 if (walk.src.virt.addr == walk.dst.virt.addr)76 nbytes = crypto_pcbc_encrypt_inplace(req, &walk,77 cipher);78 else79 nbytes = crypto_pcbc_encrypt_segment(req, &walk,80 cipher);81 err = skcipher_walk_done(&walk, nbytes);82 }83 84 return err;85}86 87static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,88 struct skcipher_walk *walk,89 struct crypto_cipher *tfm)90{91 int bsize = crypto_cipher_blocksize(tfm);92 unsigned int nbytes = walk->nbytes;93 u8 *src = walk->src.virt.addr;94 u8 *dst = walk->dst.virt.addr;95 u8 * const iv = walk->iv;96 97 do {98 crypto_cipher_decrypt_one(tfm, dst, src);99 crypto_xor(dst, iv, bsize);100 crypto_xor_cpy(iv, dst, src, bsize);101 102 src += bsize;103 dst += bsize;104 } while ((nbytes -= bsize) >= bsize);105 106 return nbytes;107}108 109static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,110 struct skcipher_walk *walk,111 struct crypto_cipher *tfm)112{113 int bsize = crypto_cipher_blocksize(tfm);114 unsigned int nbytes = walk->nbytes;115 u8 *src = walk->src.virt.addr;116 u8 * const iv = walk->iv;117 u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));118 119 do {120 memcpy(tmpbuf, src, bsize);121 crypto_cipher_decrypt_one(tfm, src, src);122 crypto_xor(src, iv, bsize);123 crypto_xor_cpy(iv, src, tmpbuf, bsize);124 125 src += bsize;126 } while ((nbytes -= bsize) >= bsize);127 128 return nbytes;129}130 131static int crypto_pcbc_decrypt(struct skcipher_request *req)132{133 struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);134 struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);135 struct skcipher_walk walk;136 unsigned int nbytes;137 int err;138 139 err = skcipher_walk_virt(&walk, req, false);140 141 while (walk.nbytes) {142 if (walk.src.virt.addr == walk.dst.virt.addr)143 nbytes = crypto_pcbc_decrypt_inplace(req, &walk,144 cipher);145 else146 nbytes = crypto_pcbc_decrypt_segment(req, &walk,147 cipher);148 err = skcipher_walk_done(&walk, nbytes);149 }150 151 return err;152}153 154static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)155{156 struct skcipher_instance *inst;157 int err;158 159 inst = skcipher_alloc_instance_simple(tmpl, tb);160 if (IS_ERR(inst))161 return PTR_ERR(inst);162 163 inst->alg.encrypt = crypto_pcbc_encrypt;164 inst->alg.decrypt = crypto_pcbc_decrypt;165 166 err = skcipher_register_instance(tmpl, inst);167 if (err)168 inst->free(inst);169 170 return err;171}172 173static struct crypto_template crypto_pcbc_tmpl = {174 .name = "pcbc",175 .create = crypto_pcbc_create,176 .module = THIS_MODULE,177};178 179static int __init crypto_pcbc_module_init(void)180{181 return crypto_register_template(&crypto_pcbc_tmpl);182}183 184static void __exit crypto_pcbc_module_exit(void)185{186 crypto_unregister_template(&crypto_pcbc_tmpl);187}188 189subsys_initcall(crypto_pcbc_module_init);190module_exit(crypto_pcbc_module_exit);191 192MODULE_LICENSE("GPL");193MODULE_DESCRIPTION("PCBC block cipher mode of operation");194MODULE_ALIAS_CRYPTO("pcbc");195MODULE_IMPORT_NS(CRYPTO_INTERNAL);196