[linux.git] / crypto / cmac.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * CMAC: Cipher Block Mode for Authentication
 *
 * Copyright © 2013 Jussi Kivilinna <[email protected]>
 *
 * Based on work by:
 *  Copyright © 2013 Tom St Denis <[email protected]>
 * Based on crypto/xcbc.c:
 *  Copyright © 2006 USAGI/WIDE Project,
 *   Author: Kazunori Miyazawa <[email protected]>
 */

#include <crypto/internal/cipher.h>
#include <crypto/internal/hash.h>
#include <linux/err.h>
#include <linux/kernel.h>
#include <linux/module.h>

/*
 * +------------------------
 * | <parent tfm>
 * +------------------------
 * | cmac_tfm_ctx
 * +------------------------
 * | consts (block size * 2)
 * +------------------------
 */
struct cmac_tfm_ctx {
	struct crypto_cipher *child;
	__be64 consts[];
};

/*
 * +------------------------
 * | <shash desc>
 * +------------------------
 * | cmac_desc_ctx
 * +------------------------
 * | odds (block size)
 * +------------------------
 * | prev (block size)
 * +------------------------
 */
struct cmac_desc_ctx {
	unsigned int len;
	u8 odds[];
};

static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
				     const u8 *inkey, unsigned int keylen)
{
	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
	unsigned int bs = crypto_shash_blocksize(parent);
	__be64 *consts = ctx->consts;
	u64 _const[2];
	int i, err = 0;
	u8 msb_mask, gfmask;

	err = crypto_cipher_setkey(ctx->child, inkey, keylen);
	if (err)
		return err;

	/* encrypt the zero block */
	memset(consts, 0, bs);
	crypto_cipher_encrypt_one(ctx->child, (u8 *)consts, (u8 *)consts);

	switch (bs) {
	case 16:
		gfmask = 0x87;
		_const[0] = be64_to_cpu(consts[1]);
		_const[1] = be64_to_cpu(consts[0]);

		/* gf(2^128) multiply zero-ciphertext with u and u^2 */
		for (i = 0; i < 4; i += 2) {
			msb_mask = ((s64)_const[1] >> 63) & gfmask;
			_const[1] = (_const[1] << 1) | (_const[0] >> 63);
			_const[0] = (_const[0] << 1) ^ msb_mask;

			consts[i + 0] = cpu_to_be64(_const[1]);
			consts[i + 1] = cpu_to_be64(_const[0]);
		}

		break;
	case 8:
		gfmask = 0x1B;
		_const[0] = be64_to_cpu(consts[0]);

		/* gf(2^64) multiply zero-ciphertext with u and u^2 */
		for (i = 0; i < 2; i++) {
			msb_mask = ((s64)_const[0] >> 63) & gfmask;
			_const[0] = (_const[0] << 1) ^ msb_mask;

			consts[i] = cpu_to_be64(_const[0]);
		}

		break;
	}

	return 0;
}

static int crypto_cmac_digest_init(struct shash_desc *pdesc)
{
	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	int bs = crypto_shash_blocksize(pdesc->tfm);
	u8 *prev = &ctx->odds[bs];

	ctx->len = 0;
	memset(prev, 0, bs);

	return 0;
}

static int crypto_cmac_digest_update(struct shash_desc *pdesc, const u8 *p,
				     unsigned int len)
{
	struct crypto_shash *parent = pdesc->tfm;
	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	struct crypto_cipher *tfm = tctx->child;
	int bs = crypto_shash_blocksize(parent);
	u8 *odds = ctx->odds;
	u8 *prev = odds + bs;

	/* checking the data can fill the block */
	if ((ctx->len + len) <= bs) {
		memcpy(odds + ctx->len, p, len);
		ctx->len += len;
		return 0;
	}

	/* filling odds with new data and encrypting it */
	memcpy(odds + ctx->len, p, bs - ctx->len);
	len -= bs - ctx->len;
	p += bs - ctx->len;

	crypto_xor(prev, odds, bs);
	crypto_cipher_encrypt_one(tfm, prev, prev);

	/* clearing the length */
	ctx->len = 0;

	/* encrypting the rest of data */
	while (len > bs) {
		crypto_xor(prev, p, bs);
		crypto_cipher_encrypt_one(tfm, prev, prev);
		p += bs;
		len -= bs;
	}

	/* keeping the surplus of blocksize */
	if (len) {
		memcpy(odds, p, len);
		ctx->len = len;
	}

	return 0;
}

static int crypto_cmac_digest_final(struct shash_desc *pdesc, u8 *out)
{
	struct crypto_shash *parent = pdesc->tfm;
	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	struct crypto_cipher *tfm = tctx->child;
	int bs = crypto_shash_blocksize(parent);
	u8 *odds = ctx->odds;
	u8 *prev = odds + bs;
	unsigned int offset = 0;

	if (ctx->len != bs) {
		unsigned int rlen;
		u8 *p = odds + ctx->len;

		*p = 0x80;
		p++;

		rlen = bs - ctx->len - 1;
		if (rlen)
			memset(p, 0, rlen);

		offset += bs;
	}

	crypto_xor(prev, odds, bs);
	crypto_xor(prev, (const u8 *)tctx->consts + offset, bs);

	crypto_cipher_encrypt_one(tfm, out, prev);

	return 0;
}

static int cmac_init_tfm(struct crypto_shash *tfm)
{
	struct shash_instance *inst = shash_alg_instance(tfm);
	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
	struct crypto_cipher_spawn *spawn;
	struct crypto_cipher *cipher;

	spawn = shash_instance_ctx(inst);
	cipher = crypto_spawn_cipher(spawn);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	ctx->child = cipher;

	return 0;
}

static int cmac_clone_tfm(struct crypto_shash *tfm, struct crypto_shash *otfm)
{
	struct cmac_tfm_ctx *octx = crypto_shash_ctx(otfm);
	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
	struct crypto_cipher *cipher;

	cipher = crypto_clone_cipher(octx->child);
	if (IS_ERR(cipher))
		return PTR_ERR(cipher);

	ctx->child = cipher;

	return 0;
}

static void cmac_exit_tfm(struct crypto_shash *tfm)
{
	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
	crypto_free_cipher(ctx->child);
}

static int cmac_create(struct crypto_template *tmpl, struct rtattr **tb)
{
	struct shash_instance *inst;
	struct crypto_cipher_spawn *spawn;
	struct crypto_alg *alg;
	u32 mask;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
	if (err)
		return err;

	inst = kzalloc(sizeof(*inst) + sizeof(*spawn), GFP_KERNEL);
	if (!inst)
		return -ENOMEM;
	spawn = shash_instance_ctx(inst);

	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
				 crypto_attr_alg_name(tb[1]), 0, mask);
	if (err)
		goto err_free_inst;
	alg = crypto_spawn_cipher_alg(spawn);

	switch (alg->cra_blocksize) {
	case 16:
	case 8:
		break;
	default:
		err = -EINVAL;
		goto err_free_inst;
	}

	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
	if (err)
		goto err_free_inst;

	inst->alg.base.cra_priority = alg->cra_priority;
	inst->alg.base.cra_blocksize = alg->cra_blocksize;
	inst->alg.base.cra_ctxsize = sizeof(struct cmac_tfm_ctx) +
				     alg->cra_blocksize * 2;

	inst->alg.digestsize = alg->cra_blocksize;
	inst->alg.descsize = sizeof(struct cmac_desc_ctx) +
			     alg->cra_blocksize * 2;
	inst->alg.init = crypto_cmac_digest_init;
	inst->alg.update = crypto_cmac_digest_update;
	inst->alg.final = crypto_cmac_digest_final;
	inst->alg.setkey = crypto_cmac_digest_setkey;
	inst->alg.init_tfm = cmac_init_tfm;
	inst->alg.clone_tfm = cmac_clone_tfm;
	inst->alg.exit_tfm = cmac_exit_tfm;

	inst->free = shash_free_singlespawn_instance;

	err = shash_register_instance(tmpl, inst);
	if (err) {
err_free_inst:
		shash_free_singlespawn_instance(inst);
	}
	return err;
}

static struct crypto_template crypto_cmac_tmpl = {
	.name = "cmac",
	.create = cmac_create,
	.module = THIS_MODULE,
};

static int __init crypto_cmac_module_init(void)
{
	return crypto_register_template(&crypto_cmac_tmpl);
}

static void __exit crypto_cmac_module_exit(void)
{
	crypto_unregister_template(&crypto_cmac_tmpl);
}

subsys_initcall(crypto_cmac_module_init);
module_exit(crypto_cmac_module_exit);

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("CMAC keyed hash algorithm");
MODULE_ALIAS_CRYPTO("cmac");
MODULE_IMPORT_NS(CRYPTO_INTERNAL);
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
93b5e86a JK	2	/*
	3	* CMAC: Cipher Block Mode for Authentication
	4	*
	5	* Copyright © 2013 Jussi Kivilinna <[email protected]>
	6	*
	7	* Based on work by:
	8	* Copyright © 2013 Tom St Denis <[email protected]>
	9	* Based on crypto/xcbc.c:
	10	* Copyright © 2006 USAGI/WIDE Project,
	11	* Author: Kazunori Miyazawa <[email protected]>
93b5e86a JK	12	*/
93b5e86a JK	13
0eb76ba2	14	#include <crypto/internal/cipher.h>
93b5e86a JK	15	#include <crypto/internal/hash.h>
	16	#include <linux/err.h>
	17	#include <linux/kernel.h>
	18	#include <linux/module.h>
	19
	20	/*
	21	* +------------------------
	22	* \| <parent tfm>
	23	* +------------------------
	24	* \| cmac_tfm_ctx
	25	* +------------------------
	26	* \| consts (block size * 2)
	27	* +------------------------
	28	*/
	29	struct cmac_tfm_ctx {
	30	struct crypto_cipher *child;
f9dc9f2e	31	__be64 consts[];
93b5e86a JK	32	};
	33
	34	/*
	35	* +------------------------
	36	* \| <shash desc>
	37	* +------------------------
	38	* \| cmac_desc_ctx
	39	* +------------------------
	40	* \| odds (block size)
	41	* +------------------------
	42	* \| prev (block size)
	43	* +------------------------
	44	*/
	45	struct cmac_desc_ctx {
	46	unsigned int len;
f9dc9f2e	47	u8 odds[];
93b5e86a JK	48	};
	49
	50	static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
	51	const u8 *inkey, unsigned int keylen)
	52	{
93b5e86a JK	53	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
93b5e86a JK	54	unsigned int bs = crypto_shash_blocksize(parent);
f9dc9f2e	55	__be64 *consts = ctx->consts;
93b5e86a JK	56	u64 _const[2];
	57	int i, err = 0;
	58	u8 msb_mask, gfmask;
	59
	60	err = crypto_cipher_setkey(ctx->child, inkey, keylen);
	61	if (err)
	62	return err;
	63
	64	/* encrypt the zero block */
	65	memset(consts, 0, bs);
	66	crypto_cipher_encrypt_one(ctx->child, (u8 )consts, (u8 )consts);
	67
	68	switch (bs) {
	69	case 16:
	70	gfmask = 0x87;
	71	_const[0] = be64_to_cpu(consts[1]);
	72	_const[1] = be64_to_cpu(consts[0]);
	73
	74	/* gf(2^128) multiply zero-ciphertext with u and u^2 */
	75	for (i = 0; i < 4; i += 2) {
	76	msb_mask = ((s64)_const[1] >> 63) & gfmask;
	77	_const[1] = (_const[1] << 1) \| (_const[0] >> 63);
	78	_const[0] = (_const[0] << 1) ^ msb_mask;
	79
	80	consts[i + 0] = cpu_to_be64(_const[1]);
	81	consts[i + 1] = cpu_to_be64(_const[0]);
	82	}
	83
	84	break;
	85	case 8:
	86	gfmask = 0x1B;
	87	_const[0] = be64_to_cpu(consts[0]);
	88
	89	/* gf(2^64) multiply zero-ciphertext with u and u^2 */
	90	for (i = 0; i < 2; i++) {
	91	msb_mask = ((s64)_const[0] >> 63) & gfmask;
	92	_const[0] = (_const[0] << 1) ^ msb_mask;
	93
	94	consts[i] = cpu_to_be64(_const[0]);
	95	}
	96
	97	break;
	98	}
	99
	100	return 0;
	101	}
	102
	103	static int crypto_cmac_digest_init(struct shash_desc *pdesc)
	104	{
93b5e86a JK	105	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
93b5e86a JK	106	int bs = crypto_shash_blocksize(pdesc->tfm);
f9dc9f2e	107	u8 *prev = &ctx->odds[bs];
93b5e86a JK	108
	109	ctx->len = 0;
	110	memset(prev, 0, bs);
	111
	112	return 0;
	113	}
	114
	115	static int crypto_cmac_digest_update(struct shash_desc pdesc, const u8 p,
	116	unsigned int len)
	117	{
	118	struct crypto_shash *parent = pdesc->tfm;
93b5e86a JK	119	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	120	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	121	struct crypto_cipher *tfm = tctx->child;
	122	int bs = crypto_shash_blocksize(parent);
f9dc9f2e	123	u8 *odds = ctx->odds;
93b5e86a JK	124	u8 *prev = odds + bs;
	125
	126	/* checking the data can fill the block */
	127	if ((ctx->len + len) <= bs) {
	128	memcpy(odds + ctx->len, p, len);
	129	ctx->len += len;
	130	return 0;
	131	}
	132
	133	/* filling odds with new data and encrypting it */
	134	memcpy(odds + ctx->len, p, bs - ctx->len);
	135	len -= bs - ctx->len;
	136	p += bs - ctx->len;
	137
	138	crypto_xor(prev, odds, bs);
	139	crypto_cipher_encrypt_one(tfm, prev, prev);
	140
	141	/* clearing the length */
	142	ctx->len = 0;
	143
	144	/* encrypting the rest of data */
	145	while (len > bs) {
	146	crypto_xor(prev, p, bs);
	147	crypto_cipher_encrypt_one(tfm, prev, prev);
	148	p += bs;
	149	len -= bs;
	150	}
	151
	152	/* keeping the surplus of blocksize */
	153	if (len) {
	154	memcpy(odds, p, len);
	155	ctx->len = len;
	156	}
	157
	158	return 0;
	159	}
	160
	161	static int crypto_cmac_digest_final(struct shash_desc pdesc, u8 out)
	162	{
	163	struct crypto_shash *parent = pdesc->tfm;
93b5e86a JK	164	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
	165	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	166	struct crypto_cipher *tfm = tctx->child;
	167	int bs = crypto_shash_blocksize(parent);
f9dc9f2e	168	u8 *odds = ctx->odds;
93b5e86a JK	169	u8 *prev = odds + bs;
	170	unsigned int offset = 0;
	171
	172	if (ctx->len != bs) {
	173	unsigned int rlen;
	174	u8 *p = odds + ctx->len;
	175
	176	*p = 0x80;
	177	p++;
	178
	179	rlen = bs - ctx->len - 1;
	180	if (rlen)
	181	memset(p, 0, rlen);
	182
	183	offset += bs;
	184	}
	185
	186	crypto_xor(prev, odds, bs);
f9dc9f2e	187	crypto_xor(prev, (const u8 *)tctx->consts + offset, bs);
93b5e86a JK	188
	189	crypto_cipher_encrypt_one(tfm, out, prev);
	190
	191	return 0;
	192	}
	193
cf2eddc9	194	static int cmac_init_tfm(struct crypto_shash *tfm)
93b5e86a	195	{
cf2eddc9 HX	196	struct shash_instance *inst = shash_alg_instance(tfm);
	197	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
	198	struct crypto_cipher_spawn *spawn;
93b5e86a	199	struct crypto_cipher *cipher;
93b5e86a	200
cf2eddc9	201	spawn = shash_instance_ctx(inst);
93b5e86a JK	202	cipher = crypto_spawn_cipher(spawn);
	203	if (IS_ERR(cipher))
	204	return PTR_ERR(cipher);
	205
	206	ctx->child = cipher;
	207
	208	return 0;
ed51bba1 HX	209	}
	210
	211	static int cmac_clone_tfm(struct crypto_shash tfm, struct crypto_shash otfm)
	212	{
	213	struct cmac_tfm_ctx *octx = crypto_shash_ctx(otfm);
	214	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
	215	struct crypto_cipher *cipher;
	216
	217	cipher = crypto_clone_cipher(octx->child);
	218	if (IS_ERR(cipher))
	219	return PTR_ERR(cipher);
	220
	221	ctx->child = cipher;
	222
	223	return 0;
	224	}
93b5e86a	225
cf2eddc9	226	static void cmac_exit_tfm(struct crypto_shash *tfm)
93b5e86a	227	{
cf2eddc9	228	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(tfm);
93b5e86a JK	229	crypto_free_cipher(ctx->child);
	230	}
	231
	232	static int cmac_create(struct crypto_template tmpl, struct rtattr *tb)
	233	{
	234	struct shash_instance *inst;
1d0459cd	235	struct crypto_cipher_spawn *spawn;
93b5e86a	236	struct crypto_alg *alg;
7bcb2c99	237	u32 mask;
93b5e86a JK	238	int err;
93b5e86a JK	239
7bcb2c99	240	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
93b5e86a JK	241	if (err)
	242	return err;
	243
1d0459cd EB	244	inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
	245	if (!inst)
	246	return -ENOMEM;
	247	spawn = shash_instance_ctx(inst);
	248
	249	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
7bcb2c99	250	crypto_attr_alg_name(tb[1]), 0, mask);
1d0459cd EB	251	if (err)
	252	goto err_free_inst;
	253	alg = crypto_spawn_cipher_alg(spawn);
93b5e86a JK	254
	255	switch (alg->cra_blocksize) {
	256	case 16:
	257	case 8:
	258	break;
	259	default:
48ee41bf	260	err = -EINVAL;
1d0459cd	261	goto err_free_inst;
93b5e86a JK	262	}
93b5e86a JK	263
1d0459cd	264	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
93b5e86a	265	if (err)
1d0459cd	266	goto err_free_inst;
93b5e86a	267
93b5e86a JK	268	inst->alg.base.cra_priority = alg->cra_priority;
93b5e86a JK	269	inst->alg.base.cra_blocksize = alg->cra_blocksize;
f9dc9f2e EB	270	inst->alg.base.cra_ctxsize = sizeof(struct cmac_tfm_ctx) +
f9dc9f2e EB	271	alg->cra_blocksize * 2;
93b5e86a JK	272
93b5e86a JK	273	inst->alg.digestsize = alg->cra_blocksize;
f9dc9f2e EB	274	inst->alg.descsize = sizeof(struct cmac_desc_ctx) +
f9dc9f2e EB	275	alg->cra_blocksize * 2;
93b5e86a JK	276	inst->alg.init = crypto_cmac_digest_init;
	277	inst->alg.update = crypto_cmac_digest_update;
	278	inst->alg.final = crypto_cmac_digest_final;
	279	inst->alg.setkey = crypto_cmac_digest_setkey;
cf2eddc9	280	inst->alg.init_tfm = cmac_init_tfm;
ed51bba1	281	inst->alg.clone_tfm = cmac_clone_tfm;
cf2eddc9	282	inst->alg.exit_tfm = cmac_exit_tfm;
93b5e86a	283
a39c66cc EB	284	inst->free = shash_free_singlespawn_instance;
a39c66cc EB	285
93b5e86a JK	286	err = shash_register_instance(tmpl, inst);
93b5e86a JK	287	if (err) {
1d0459cd	288	err_free_inst:
a39c66cc	289	shash_free_singlespawn_instance(inst);
93b5e86a	290	}
93b5e86a JK	291	return err;
	292	}
	293
	294	static struct crypto_template crypto_cmac_tmpl = {
	295	.name = "cmac",
	296	.create = cmac_create,
93b5e86a JK	297	.module = THIS_MODULE,
	298	};
	299
	300	static int __init crypto_cmac_module_init(void)
	301	{
	302	return crypto_register_template(&crypto_cmac_tmpl);
	303	}
	304
	305	static void __exit crypto_cmac_module_exit(void)
	306	{
	307	crypto_unregister_template(&crypto_cmac_tmpl);
	308	}
	309
c4741b23	310	subsys_initcall(crypto_cmac_module_init);
93b5e86a JK	311	module_exit(crypto_cmac_module_exit);
	312
	313	MODULE_LICENSE("GPL");
	314	MODULE_DESCRIPTION("CMAC keyed hash algorithm");
4943ba16	315	MODULE_ALIAS_CRYPTO("cmac");
0eb76ba2	316	MODULE_IMPORT_NS(CRYPTO_INTERNAL);