[linux.git] / crypto / ofb.c

// SPDX-License-Identifier: GPL-2.0

/*
 * OFB: Output FeedBack mode
 *
 * Copyright (C) 2018 ARM Limited or its affiliates.
 * All rights reserved.
 */

#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_ofb_crypt(struct skcipher_request *req)
{
	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
	struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
	const unsigned int bsize = crypto_cipher_blocksize(cipher);
	struct skcipher_walk walk;
	int err;

	err = skcipher_walk_virt(&walk, req, false);

	while (walk.nbytes >= bsize) {
		const u8 *src = walk.src.virt.addr;
		u8 *dst = walk.dst.virt.addr;
		u8 * const iv = walk.iv;
		unsigned int nbytes = walk.nbytes;

		do {
			crypto_cipher_encrypt_one(cipher, iv, iv);
			crypto_xor_cpy(dst, src, iv, bsize);
			dst += bsize;
			src += bsize;
		} while ((nbytes -= bsize) >= bsize);

		err = skcipher_walk_done(&walk, nbytes);
	}

	if (walk.nbytes) {
		crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
		crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
			       walk.nbytes);
		err = skcipher_walk_done(&walk, 0);
	}
	return err;
}

static int crypto_ofb_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);
	if (IS_ERR(inst))
		return PTR_ERR(inst);

	alg = skcipher_ialg_simple(inst);

	/* OFB mode is a stream cipher. */
	inst->alg.base.cra_blocksize = 1;

	/*
	 * To simplify the implementation, configure the skcipher walk to only
	 * give a partial block at the very end, never earlier.
	 */
	inst->alg.chunksize = alg->cra_blocksize;

	inst->alg.encrypt = crypto_ofb_crypt;
	inst->alg.decrypt = crypto_ofb_crypt;

	err = skcipher_register_instance(tmpl, inst);
	if (err)
		inst->free(inst);

	return err;
}

static struct crypto_template crypto_ofb_tmpl = {
	.name = "ofb",
	.create = crypto_ofb_create,
	.module = THIS_MODULE,
};

static int __init crypto_ofb_module_init(void)
{
	return crypto_register_template(&crypto_ofb_tmpl);
}

static void __exit crypto_ofb_module_exit(void)
{
	crypto_unregister_template(&crypto_ofb_tmpl);
}

subsys_initcall(crypto_ofb_module_init);
module_exit(crypto_ofb_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("OFB block cipher mode of operation");
MODULE_ALIAS_CRYPTO("ofb");
Commit	Line	Data
e497c518 GBY	1	// SPDX-License-Identifier: GPL-2.0
	2
	3	/*
	4	* OFB: Output FeedBack mode
	5	*
	6	* Copyright (C) 2018 ARM Limited or its affiliates.
	7	* All rights reserved.
e497c518 GBY	8	*/
	9
	10	#include <crypto/algapi.h>
	11	#include <crypto/internal/skcipher.h>
	12	#include <linux/err.h>
	13	#include <linux/init.h>
	14	#include <linux/kernel.h>
	15	#include <linux/module.h>
e497c518	16
b3e3e2db	17	static int crypto_ofb_crypt(struct skcipher_request *req)
e497c518	18	{
e497c518	19	struct crypto_skcipher *tfm = crypto_skcipher_reqtfm(req);
21f3ca6c	20	struct crypto_cipher *cipher = skcipher_cipher_simple(tfm);
b3e3e2db EB	21	const unsigned int bsize = crypto_cipher_blocksize(cipher);
	22	struct skcipher_walk walk;
	23	int err;
e497c518	24
b3e3e2db	25	err = skcipher_walk_virt(&walk, req, false);
e497c518	26
b3e3e2db EB	27	while (walk.nbytes >= bsize) {
	28	const u8 *src = walk.src.virt.addr;
	29	u8 *dst = walk.dst.virt.addr;
	30	u8 * const iv = walk.iv;
	31	unsigned int nbytes = walk.nbytes;
e497c518	32
b3e3e2db EB	33	do {
	34	crypto_cipher_encrypt_one(cipher, iv, iv);
	35	crypto_xor_cpy(dst, src, iv, bsize);
	36	dst += bsize;
	37	src += bsize;
	38	} while ((nbytes -= bsize) >= bsize);
e497c518	39
b3e3e2db EB	40	err = skcipher_walk_done(&walk, nbytes);
b3e3e2db EB	41	}
e497c518	42
b3e3e2db EB	43	if (walk.nbytes) {
	44	crypto_cipher_encrypt_one(cipher, walk.iv, walk.iv);
	45	crypto_xor_cpy(walk.dst.virt.addr, walk.src.virt.addr, walk.iv,
	46	walk.nbytes);
	47	err = skcipher_walk_done(&walk, 0);
	48	}
	49	return err;
e497c518 GBY	50	}
e497c518 GBY	51
e497c518 GBY	52	static int crypto_ofb_create(struct crypto_template tmpl, struct rtattr *tb)
	53	{
	54	struct skcipher_instance *inst;
e497c518	55	struct crypto_alg *alg;
e497c518 GBY	56	int err;
e497c518 GBY	57
b3c16bfc	58	inst = skcipher_alloc_instance_simple(tmpl, tb);
21f3ca6c EB	59	if (IS_ERR(inst))
21f3ca6c EB	60	return PTR_ERR(inst);
e497c518	61
b3c16bfc HX	62	alg = skcipher_ialg_simple(inst);
b3c16bfc HX	63
b3e3e2db EB	64	/* OFB mode is a stream cipher. */
	65	inst->alg.base.cra_blocksize = 1;
	66
	67	/*
	68	* To simplify the implementation, configure the skcipher walk to only
	69	* give a partial block at the very end, never earlier.
	70	*/
	71	inst->alg.chunksize = alg->cra_blocksize;
	72
b3e3e2db EB	73	inst->alg.encrypt = crypto_ofb_crypt;
b3e3e2db EB	74	inst->alg.decrypt = crypto_ofb_crypt;
e497c518	75
e497c518 GBY	76	err = skcipher_register_instance(tmpl, inst);
e497c518 GBY	77	if (err)
21f3ca6c	78	inst->free(inst);
e497c518	79
e497c518	80	return err;
e497c518 GBY	81	}
	82
	83	static struct crypto_template crypto_ofb_tmpl = {
	84	.name = "ofb",
	85	.create = crypto_ofb_create,
	86	.module = THIS_MODULE,
	87	};
	88
	89	static int __init crypto_ofb_module_init(void)
	90	{
	91	return crypto_register_template(&crypto_ofb_tmpl);
	92	}
	93
	94	static void __exit crypto_ofb_module_exit(void)
	95	{
	96	crypto_unregister_template(&crypto_ofb_tmpl);
	97	}
	98
c4741b23	99	subsys_initcall(crypto_ofb_module_init);
e497c518 GBY	100	module_exit(crypto_ofb_module_exit);
	101
	102	MODULE_LICENSE("GPL");
21f3ca6c	103	MODULE_DESCRIPTION("OFB block cipher mode of operation");
e497c518	104	MODULE_ALIAS_CRYPTO("ofb");