// SPDX-License-Identifier: GPL-2.0-or-later /* * PCBC: Propagating Cipher Block Chaining mode * * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved. * Written by David Howells (dhowells@redhat.com) * * Derived from cbc.c * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au> */ #include <crypto/algapi.h> #include <crypto/internal/skcipher.h> #include <linux/err.h> #include <linux/init.h> #include <linux/kernel.h> #include <linux/module.h> static int crypto_pcbc_encrypt_segment(struct skcipher_request *req, struct skcipher_walk *walk, struct crypto_cipher *tfm) { int bsize = crypto_cipher_blocksize(tfm); unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; u8 * const iv = walk->iv; do { crypto_xor(iv, src, bsize); crypto_cipher_encrypt_one(tfm, dst, iv); crypto_xor_cpy(iv, dst, src, bsize); src += bsize; dst += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req, struct skcipher_walk *walk, struct crypto_cipher *tfm) { int bsize = crypto_cipher_blocksize(tfm); unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 * const iv = walk->iv; u8 tmpbuf[MAX_CIPHER_BLOCKSIZE]; do { memcpy(tmpbuf, src, bsize); crypto_xor(iv, src, bsize); crypto_cipher_encrypt_one(tfm, src, iv); crypto_xor_cpy(iv, tmpbuf, src, bsize); src += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_pcbc_encrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); struct skcipher_walk walk; unsigned int nbytes; int err; err = skcipher_walk_virt(&walk, req, false); while ((nbytes = walk.nbytes)) { if (walk.src.virt.addr == walk.dst.virt.addr) nbytes = crypto_pcbc_encrypt_inplace(req, &walk, cipher); else nbytes = crypto_pcbc_encrypt_segment(req, &walk, cipher); err = skcipher_walk_done(&walk, nbytes); } return err; } static int crypto_pcbc_decrypt_segment(struct skcipher_request *req, struct skcipher_walk *walk, struct crypto_cipher *tfm) { int bsize = crypto_cipher_blocksize(tfm); unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 *dst = walk->dst.virt.addr; u8 * const iv = walk->iv; do { crypto_cipher_decrypt_one(tfm, dst, src); crypto_xor(dst, iv, bsize); crypto_xor_cpy(iv, dst, src, bsize); src += bsize; dst += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req, struct skcipher_walk *walk, struct crypto_cipher *tfm) { int bsize = crypto_cipher_blocksize(tfm); unsigned int nbytes = walk->nbytes; u8 *src = walk->src.virt.addr; u8 * const iv = walk->iv; u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32)); do { memcpy(tmpbuf, src, bsize); crypto_cipher_decrypt_one(tfm, src, src); crypto_xor(src, iv, bsize); crypto_xor_cpy(iv, src, tmpbuf, bsize); src += bsize; } while ((nbytes -= bsize) >= bsize); return nbytes; } static int crypto_pcbc_decrypt(struct skcipher_request *req) { struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req); struct crypto_cipher *cipher = skcipher_cipher_simple(tfm); struct skcipher_walk walk; unsigned int nbytes; int err; err = skcipher_walk_virt(&walk, req, false); while ((nbytes = walk.nbytes)) { if (walk.src.virt.addr == walk.dst.virt.addr) nbytes = crypto_pcbc_decrypt_inplace(req, &walk, cipher); else nbytes = crypto_pcbc_decrypt_segment(req, &walk, cipher); err = skcipher_walk_done(&walk, nbytes); } return err; } static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb) { struct skcipher_instance *inst; struct crypto_alg *alg; int err; inst = skcipher_alloc_instance_simple(tmpl, tb, &alg); if (IS_ERR(inst)) return PTR_ERR(inst); inst->alg.encrypt = crypto_pcbc_encrypt; inst->alg.decrypt = crypto_pcbc_decrypt; err = skcipher_register_instance(tmpl, inst); if (err) inst->free(inst); crypto_mod_put(alg); return err; } static struct crypto_template crypto_pcbc_tmpl = { .name = "pcbc", .create = crypto_pcbc_create, .module = THIS_MODULE, }; static int __init crypto_pcbc_module_init(void) { return crypto_register_template(&crypto_pcbc_tmpl); } static void __exit crypto_pcbc_module_exit(void) { crypto_unregister_template(&crypto_pcbc_tmpl); } subsys_initcall(crypto_pcbc_module_init); module_exit(crypto_pcbc_module_exit); MODULE_LICENSE("GPL"); MODULE_DESCRIPTION("PCBC block cipher mode of operation"); MODULE_ALIAS_CRYPTO("pcbc");