the-tree/crypto/pcbc.c

0001 // SPDX-License-Identifier: GPL-2.0-or-later
0002 /*
0003  * PCBC: Propagating Cipher Block Chaining mode
0004  *
0005  * Copyright (C) 2006 Red Hat, Inc. All Rights Reserved.
0006  * Written by David Howells (dhowells@redhat.com)
0007  *
0008  * Derived from cbc.c
0009  * - Copyright (c) 2006 Herbert Xu <herbert@gondor.apana.org.au>
0010  */
0011
0012 #include <crypto/algapi.h>
0013 #include <crypto/internal/cipher.h>
0014 #include <crypto/internal/skcipher.h>
0015 #include <linux/err.h>
0016 #include <linux/init.h>
0017 #include <linux/kernel.h>
0018 #include <linux/module.h>
0019
0020 static int crypto_pcbc_encrypt_segment(struct skcipher_request *req,
0021                        struct skcipher_walk *walk,
0022                        struct crypto_cipher *tfm)
0023 {
0024     int bsize = crypto_cipher_blocksize(tfm);
0025     unsigned int nbytes = walk->nbytes;
0026     u8 *src = walk->src.virt.addr;
0027     u8 *dst = walk->dst.virt.addr;
0028     u8 * const iv = walk->iv;
0029
0030     do {
0031         crypto_xor(iv, src, bsize);
0032         crypto_cipher_encrypt_one(tfm, dst, iv);
0033         crypto_xor_cpy(iv, dst, src, bsize);
0034
0035         src += bsize;
0036         dst += bsize;
0037     } while ((nbytes -= bsize) >= bsize);
0038
0039     return nbytes;
0040 }
0041
0042 static int crypto_pcbc_encrypt_inplace(struct skcipher_request *req,
0043                        struct skcipher_walk *walk,
0044                        struct crypto_cipher *tfm)
0045 {
0046     int bsize = crypto_cipher_blocksize(tfm);
0047     unsigned int nbytes = walk->nbytes;
0048     u8 *src = walk->src.virt.addr;
0049     u8 * const iv = walk->iv;
0050     u8 tmpbuf[MAX_CIPHER_BLOCKSIZE];
0051
0052     do {
0053         memcpy(tmpbuf, src, bsize);
0054         crypto_xor(iv, src, bsize);
0055         crypto_cipher_encrypt_one(tfm, src, iv);
0056         crypto_xor_cpy(iv, tmpbuf, src, bsize);
0057
0058         src += bsize;
0059     } while ((nbytes -= bsize) >= bsize);
0060
0061     return nbytes;
0062 }
0063
0064 static int crypto_pcbc_encrypt(struct skcipher_request *req)
0065 {
0066     struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
0067     struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
0068     struct skcipher_walk walk;
0069     unsigned int nbytes;
0070     int err;
0071
0072     err = skcipher_walk_virt(&walk, req, false);
0073
0074     while ((nbytes = walk.nbytes)) {
0075         if (walk.src.virt.addr == walk.dst.virt.addr)
0076             nbytes = crypto_pcbc_encrypt_inplace(req, &walk,
0077                                  cipher);
0078         else
0079             nbytes = crypto_pcbc_encrypt_segment(req, &walk,
0080                                  cipher);
0081         err = skcipher_walk_done(&walk, nbytes);
0082     }
0083
0084     return err;
0085 }
0086
0087 static int crypto_pcbc_decrypt_segment(struct skcipher_request *req,
0088                        struct skcipher_walk *walk,
0089                        struct crypto_cipher *tfm)
0090 {
0091     int bsize = crypto_cipher_blocksize(tfm);
0092     unsigned int nbytes = walk->nbytes;
0093     u8 *src = walk->src.virt.addr;
0094     u8 *dst = walk->dst.virt.addr;
0095     u8 * const iv = walk->iv;
0096
0097     do {
0098         crypto_cipher_decrypt_one(tfm, dst, src);
0099         crypto_xor(dst, iv, bsize);
0100         crypto_xor_cpy(iv, dst, src, bsize);
0101
0102         src += bsize;
0103         dst += bsize;
0104     } while ((nbytes -= bsize) >= bsize);
0105
0106     return nbytes;
0107 }
0108
0109 static int crypto_pcbc_decrypt_inplace(struct skcipher_request *req,
0110                        struct skcipher_walk *walk,
0111                        struct crypto_cipher *tfm)
0112 {
0113     int bsize = crypto_cipher_blocksize(tfm);
0114     unsigned int nbytes = walk->nbytes;
0115     u8 *src = walk->src.virt.addr;
0116     u8 * const iv = walk->iv;
0117     u8 tmpbuf[MAX_CIPHER_BLOCKSIZE] __aligned(__alignof__(u32));
0118
0119     do {
0120         memcpy(tmpbuf, src, bsize);
0121         crypto_cipher_decrypt_one(tfm, src, src);
0122         crypto_xor(src, iv, bsize);
0123         crypto_xor_cpy(iv, src, tmpbuf, bsize);
0124
0125         src += bsize;
0126     } while ((nbytes -= bsize) >= bsize);
0127
0128     return nbytes;
0129 }
0130
0131 static int crypto_pcbc_decrypt(struct skcipher_request *req)
0132 {
0133     struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
0134     struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
0135     struct skcipher_walk walk;
0136     unsigned int nbytes;
0137     int err;
0138
0139     err = skcipher_walk_virt(&walk, req, false);
0140
0141     while ((nbytes = walk.nbytes)) {
0142         if (walk.src.virt.addr == walk.dst.virt.addr)
0143             nbytes = crypto_pcbc_decrypt_inplace(req, &walk,
0144                                  cipher);
0145         else
0146             nbytes = crypto_pcbc_decrypt_segment(req, &walk,
0147                                  cipher);
0148         err = skcipher_walk_done(&walk, nbytes);
0149     }
0150
0151     return err;
0152 }
0153
0154 static int crypto_pcbc_create(struct crypto_template *tmpl, struct rtattr **tb)
0155 {
0156     struct skcipher_instance *inst;
0157     int err;
0158
0159     inst = skcipher_alloc_instance_simple(tmpl, tb);
0160     if (IS_ERR(inst))
0161         return PTR_ERR(inst);
0162
0163     inst->alg.encrypt = crypto_pcbc_encrypt;
0164     inst->alg.decrypt = crypto_pcbc_decrypt;
0165
0166     err = skcipher_register_instance(tmpl, inst);
0167     if (err)
0168         inst->free(inst);
0169
0170     return err;
0171 }
0172
0173 static struct crypto_template crypto_pcbc_tmpl = {
0174     .name = "pcbc",
0175     .create = crypto_pcbc_create,
0176     .module = THIS_MODULE,
0177 };
0178
0179 static int __init crypto_pcbc_module_init(void)
0180 {
0181     return crypto_register_template(&crypto_pcbc_tmpl);
0182 }
0183
0184 static void __exit crypto_pcbc_module_exit(void)
0185 {
0186     crypto_unregister_template(&crypto_pcbc_tmpl);
0187 }
0188
0189 subsys_initcall(crypto_pcbc_module_init);
0190 module_exit(crypto_pcbc_module_exit);
0191
0192 MODULE_LICENSE("GPL");
0193 MODULE_DESCRIPTION("PCBC block cipher mode of operation");
0194 MODULE_ALIAS_CRYPTO("pcbc");
0195 MODULE_IMPORT_NS(CRYPTO_INTERNAL);