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![Ard Biesheuvel](/assets/img/avatar_default.png)
The cipher routines in the crypto API are mostly intended for templates implementing skcipher modes generically in software, and shouldn't be used outside of the crypto subsystem. So move the prototypes and all related definitions to a new header file under include/crypto/internal. Also, let's use the new module namespace feature to move the symbol exports into a new namespace CRYPTO_INTERNAL. Signed-off-by: Ard Biesheuvel <ardb@kernel.org> Acked-by: Eric Biggers <ebiggers@google.com> Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>
223 lines
5.2 KiB
C
223 lines
5.2 KiB
C
// SPDX-License-Identifier: GPL-2.0-or-later
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/*
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* CBC: Cipher Block Chaining mode
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*
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* Copyright (c) 2006-2016 Herbert Xu <herbert@gondor.apana.org.au>
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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/log2.h>
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#include <linux/module.h>
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static int crypto_cbc_encrypt_segment(struct skcipher_walk *walk,
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struct crypto_skcipher *skcipher)
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{
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unsigned int bsize = crypto_skcipher_blocksize(skcipher);
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
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unsigned int nbytes = walk->nbytes;
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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struct crypto_cipher *cipher;
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struct crypto_tfm *tfm;
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u8 *iv = walk->iv;
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cipher = skcipher_cipher_simple(skcipher);
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tfm = crypto_cipher_tfm(cipher);
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fn = crypto_cipher_alg(cipher)->cia_encrypt;
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do {
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crypto_xor(iv, src, bsize);
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fn(tfm, dst, iv);
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memcpy(iv, dst, bsize);
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src += bsize;
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dst += bsize;
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} while ((nbytes -= bsize) >= bsize);
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return nbytes;
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}
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static int crypto_cbc_encrypt_inplace(struct skcipher_walk *walk,
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struct crypto_skcipher *skcipher)
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{
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unsigned int bsize = crypto_skcipher_blocksize(skcipher);
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
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unsigned int nbytes = walk->nbytes;
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u8 *src = walk->src.virt.addr;
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struct crypto_cipher *cipher;
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struct crypto_tfm *tfm;
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u8 *iv = walk->iv;
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cipher = skcipher_cipher_simple(skcipher);
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tfm = crypto_cipher_tfm(cipher);
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fn = crypto_cipher_alg(cipher)->cia_encrypt;
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do {
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crypto_xor(src, iv, bsize);
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fn(tfm, src, src);
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iv = src;
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src += bsize;
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} while ((nbytes -= bsize) >= bsize);
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memcpy(walk->iv, iv, bsize);
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return nbytes;
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}
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static int crypto_cbc_encrypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
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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) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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err = crypto_cbc_encrypt_inplace(&walk, skcipher);
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else
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err = crypto_cbc_encrypt_segment(&walk, skcipher);
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err = skcipher_walk_done(&walk, err);
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}
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return err;
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}
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static int crypto_cbc_decrypt_segment(struct skcipher_walk *walk,
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struct crypto_skcipher *skcipher)
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{
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unsigned int bsize = crypto_skcipher_blocksize(skcipher);
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
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unsigned int nbytes = walk->nbytes;
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u8 *src = walk->src.virt.addr;
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u8 *dst = walk->dst.virt.addr;
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struct crypto_cipher *cipher;
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struct crypto_tfm *tfm;
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u8 *iv = walk->iv;
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cipher = skcipher_cipher_simple(skcipher);
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tfm = crypto_cipher_tfm(cipher);
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fn = crypto_cipher_alg(cipher)->cia_decrypt;
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do {
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fn(tfm, dst, src);
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crypto_xor(dst, iv, bsize);
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iv = src;
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src += bsize;
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dst += bsize;
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} while ((nbytes -= bsize) >= bsize);
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memcpy(walk->iv, iv, bsize);
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return nbytes;
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}
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static int crypto_cbc_decrypt_inplace(struct skcipher_walk *walk,
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struct crypto_skcipher *skcipher)
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{
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unsigned int bsize = crypto_skcipher_blocksize(skcipher);
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void (*fn)(struct crypto_tfm *, u8 *, const u8 *);
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unsigned int nbytes = walk->nbytes;
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u8 *src = walk->src.virt.addr;
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u8 last_iv[MAX_CIPHER_BLOCKSIZE];
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struct crypto_cipher *cipher;
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struct crypto_tfm *tfm;
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cipher = skcipher_cipher_simple(skcipher);
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tfm = crypto_cipher_tfm(cipher);
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fn = crypto_cipher_alg(cipher)->cia_decrypt;
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/* Start of the last block. */
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src += nbytes - (nbytes & (bsize - 1)) - bsize;
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memcpy(last_iv, src, bsize);
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for (;;) {
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fn(tfm, src, src);
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if ((nbytes -= bsize) < bsize)
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break;
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crypto_xor(src, src - bsize, bsize);
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src -= bsize;
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}
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crypto_xor(src, walk->iv, bsize);
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memcpy(walk->iv, last_iv, bsize);
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return nbytes;
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}
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static int crypto_cbc_decrypt(struct skcipher_request *req)
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{
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struct crypto_skcipher *skcipher = crypto_skcipher_reqtfm(req);
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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) {
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if (walk.src.virt.addr == walk.dst.virt.addr)
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err = crypto_cbc_decrypt_inplace(&walk, skcipher);
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else
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err = crypto_cbc_decrypt_segment(&walk, skcipher);
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err = skcipher_walk_done(&walk, err);
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}
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return err;
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}
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static int crypto_cbc_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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err = -EINVAL;
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if (!is_power_of_2(alg->cra_blocksize))
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goto out_free_inst;
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inst->alg.encrypt = crypto_cbc_encrypt;
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inst->alg.decrypt = crypto_cbc_decrypt;
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err = skcipher_register_instance(tmpl, inst);
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if (err) {
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out_free_inst:
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inst->free(inst);
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}
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return err;
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}
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static struct crypto_template crypto_cbc_tmpl = {
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.name = "cbc",
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.create = crypto_cbc_create,
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.module = THIS_MODULE,
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};
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static int __init crypto_cbc_module_init(void)
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{
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return crypto_register_template(&crypto_cbc_tmpl);
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}
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static void __exit crypto_cbc_module_exit(void)
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{
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crypto_unregister_template(&crypto_cbc_tmpl);
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}
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subsys_initcall(crypto_cbc_module_init);
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module_exit(crypto_cbc_module_exit);
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MODULE_LICENSE("GPL");
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MODULE_DESCRIPTION("CBC block cipher mode of operation");
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MODULE_ALIAS_CRYPTO("cbc");
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