[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/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;
	u8 ctx[];
};

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

static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
				     const u8 *inkey, unsigned int keylen)
{
	unsigned long alignmask = crypto_shash_alignmask(parent);
	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
	unsigned int bs = crypto_shash_blocksize(parent);
	__be64 *consts = PTR_ALIGN((void *)ctx->ctx,
				   (alignmask | (__alignof__(__be64) - 1)) + 1);
	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)
{
	unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	int bs = crypto_shash_blocksize(pdesc->tfm);
	u8 *prev = PTR_ALIGN((void *)ctx->ctx, alignmask + 1) + 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;
	unsigned long alignmask = crypto_shash_alignmask(parent);
	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 = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
	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;
	unsigned long alignmask = crypto_shash_alignmask(parent);
	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 *consts = PTR_ALIGN((void *)tctx->ctx,
			       (alignmask | (__alignof__(__be64) - 1)) + 1);
	u8 *odds = PTR_ALIGN((void *)ctx->ctx, alignmask + 1);
	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, consts + offset, bs);

	crypto_cipher_encrypt_one(tfm, out, prev);

	return 0;
}

static int cmac_init_tfm(struct crypto_tfm *tfm)
{
	struct crypto_cipher *cipher;
	struct crypto_instance *inst = (void *)tfm->__crt_alg;
	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);

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

	ctx->child = cipher;

	return 0;
};

static void cmac_exit_tfm(struct crypto_tfm *tfm)
{
	struct cmac_tfm_ctx *ctx = crypto_tfm_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;
	unsigned long alignmask;
	int err;

	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
	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, 0);
	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;

	alignmask = alg->cra_alignmask;
	inst->alg.base.cra_alignmask = alignmask;
	inst->alg.base.cra_priority = alg->cra_priority;
	inst->alg.base.cra_blocksize = alg->cra_blocksize;

	inst->alg.digestsize = alg->cra_blocksize;
	inst->alg.descsize =
		ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
		+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
		+ alg->cra_blocksize * 2;

	inst->alg.base.cra_ctxsize =
		ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment())
		+ ((alignmask | (__alignof__(__be64) - 1)) &
		   ~(crypto_tfm_ctx_alignment() - 1))
		+ alg->cra_blocksize * 2;

	inst->alg.base.cra_init = cmac_init_tfm;
	inst->alg.base.cra_exit = cmac_exit_tfm;

	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;

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

static struct crypto_template crypto_cmac_tmpl = {
	.name = "cmac",
	.create = cmac_create,
	.free = shash_free_instance,
	.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");
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	*/
	13
	14	#include <crypto/internal/hash.h>
	15	#include <linux/err.h>
	16	#include <linux/kernel.h>
	17	#include <linux/module.h>
	18
	19	/*
	20	* +------------------------
	21	* \| <parent tfm>
	22	* +------------------------
	23	* \| cmac_tfm_ctx
	24	* +------------------------
	25	* \| consts (block size * 2)
	26	* +------------------------
	27	*/
	28	struct cmac_tfm_ctx {
	29	struct crypto_cipher *child;
	30	u8 ctx[];
	31	};
	32
	33	/*
	34	* +------------------------
	35	* \| <shash desc>
	36	* +------------------------
	37	* \| cmac_desc_ctx
	38	* +------------------------
	39	* \| odds (block size)
	40	* +------------------------
	41	* \| prev (block size)
	42	* +------------------------
	43	*/
	44	struct cmac_desc_ctx {
	45	unsigned int len;
	46	u8 ctx[];
	47	};
	48
	49	static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
	50	const u8 *inkey, unsigned int keylen)
	51	{
	52	unsigned long alignmask = crypto_shash_alignmask(parent);
	53	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
	54	unsigned int bs = crypto_shash_blocksize(parent);
f16743e0 EB	55	__be64 consts = PTR_ALIGN((void )ctx->ctx,
f16743e0 EB	56	(alignmask \| (__alignof__(__be64) - 1)) + 1);
93b5e86a JK	57	u64 _const[2];
	58	int i, err = 0;
	59	u8 msb_mask, gfmask;
	60
	61	err = crypto_cipher_setkey(ctx->child, inkey, keylen);
	62	if (err)
	63	return err;
	64
	65	/* encrypt the zero block */
	66	memset(consts, 0, bs);
	67	crypto_cipher_encrypt_one(ctx->child, (u8 )consts, (u8 )consts);
	68
	69	switch (bs) {
	70	case 16:
	71	gfmask = 0x87;
	72	_const[0] = be64_to_cpu(consts[1]);
	73	_const[1] = be64_to_cpu(consts[0]);
	74
	75	/* gf(2^128) multiply zero-ciphertext with u and u^2 */
	76	for (i = 0; i < 4; i += 2) {
	77	msb_mask = ((s64)_const[1] >> 63) & gfmask;
	78	_const[1] = (_const[1] << 1) \| (_const[0] >> 63);
	79	_const[0] = (_const[0] << 1) ^ msb_mask;
	80
	81	consts[i + 0] = cpu_to_be64(_const[1]);
	82	consts[i + 1] = cpu_to_be64(_const[0]);
	83	}
	84
	85	break;
	86	case 8:
	87	gfmask = 0x1B;
	88	_const[0] = be64_to_cpu(consts[0]);
	89
	90	/* gf(2^64) multiply zero-ciphertext with u and u^2 */
	91	for (i = 0; i < 2; i++) {
	92	msb_mask = ((s64)_const[0] >> 63) & gfmask;
	93	_const[0] = (_const[0] << 1) ^ msb_mask;
	94
	95	consts[i] = cpu_to_be64(_const[0]);
	96	}
	97
	98	break;
	99	}
	100
	101	return 0;
	102	}
	103
	104	static int crypto_cmac_digest_init(struct shash_desc *pdesc)
	105	{
	106	unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
	107	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	108	int bs = crypto_shash_blocksize(pdesc->tfm);
	109	u8 prev = PTR_ALIGN((void )ctx->ctx, alignmask + 1) + bs;
	110
	111	ctx->len = 0;
	112	memset(prev, 0, bs);
	113
	114	return 0;
	115	}
	116
	117	static int crypto_cmac_digest_update(struct shash_desc pdesc, const u8 p,
	118	unsigned int len)
	119	{
	120	struct crypto_shash *parent = pdesc->tfm;
121	unsigned long alignmask = crypto_shash_alignmask(parent);
122	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
123	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
124	struct crypto_cipher *tfm = tctx->child;
125	int bs = crypto_shash_blocksize(parent);
126	u8 odds = PTR_ALIGN((void )ctx->ctx, alignmask + 1);
127	u8 *prev = odds + bs;
128
129	/* checking the data can fill the block */
130	if ((ctx->len + len) <= bs) {
131	memcpy(odds + ctx->len, p, len);
132	ctx->len += len;
133	return 0;
134	}
135
136	/* filling odds with new data and encrypting it */
137	memcpy(odds + ctx->len, p, bs - ctx->len);
138	len -= bs - ctx->len;
139	p += bs - ctx->len;
140
141	crypto_xor(prev, odds, bs);
142	crypto_cipher_encrypt_one(tfm, prev, prev);
143
144	/* clearing the length */
145	ctx->len = 0;
146
147	/* encrypting the rest of data */
148	while (len > bs) {
149	crypto_xor(prev, p, bs);
150	crypto_cipher_encrypt_one(tfm, prev, prev);
151	p += bs;
152	len -= bs;
153	}
154
155	/* keeping the surplus of blocksize */
156	if (len) {
157	memcpy(odds, p, len);
158	ctx->len = len;
159	}
160
161	return 0;
162	}
163
164	static int crypto_cmac_digest_final(struct shash_desc pdesc, u8 out)
165	{
166	struct crypto_shash *parent = pdesc->tfm;
167	unsigned long alignmask = crypto_shash_alignmask(parent);
168	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
169	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
170	struct crypto_cipher *tfm = tctx->child;
171	int bs = crypto_shash_blocksize(parent);
f16743e0 EB	172	u8 consts = PTR_ALIGN((void )tctx->ctx,
f16743e0 EB	173	(alignmask \| (__alignof__(__be64) - 1)) + 1);
93b5e86a JK	174	u8 odds = PTR_ALIGN((void )ctx->ctx, alignmask + 1);
	175	u8 *prev = odds + bs;
	176	unsigned int offset = 0;
	177
	178	if (ctx->len != bs) {
	179	unsigned int rlen;
	180	u8 *p = odds + ctx->len;
	181
	182	*p = 0x80;
	183	p++;
	184
	185	rlen = bs - ctx->len - 1;
	186	if (rlen)
	187	memset(p, 0, rlen);
	188
	189	offset += bs;
	190	}
	191
	192	crypto_xor(prev, odds, bs);
	193	crypto_xor(prev, consts + offset, bs);
	194
	195	crypto_cipher_encrypt_one(tfm, out, prev);
	196
	197	return 0;
	198	}
	199
	200	static int cmac_init_tfm(struct crypto_tfm *tfm)
	201	{
	202	struct crypto_cipher *cipher;
	203	struct crypto_instance inst = (void )tfm->__crt_alg;
	204	struct crypto_spawn *spawn = crypto_instance_ctx(inst);
	205	struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
	206
	207	cipher = crypto_spawn_cipher(spawn);
	208	if (IS_ERR(cipher))
	209	return PTR_ERR(cipher);
	210
	211	ctx->child = cipher;
	212
	213	return 0;
	214	};
	215
	216	static void cmac_exit_tfm(struct crypto_tfm *tfm)
	217	{
	218	struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
	219	crypto_free_cipher(ctx->child);
	220	}
	221
	222	static int cmac_create(struct crypto_template tmpl, struct rtattr *tb)
	223	{
	224	struct shash_instance *inst;
1d0459cd	225	struct crypto_cipher_spawn *spawn;
93b5e86a JK	226	struct crypto_alg *alg;
	227	unsigned long alignmask;
	228	int err;
	229
	230	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH);
	231	if (err)
	232	return err;
	233
1d0459cd EB	234	inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
	235	if (!inst)
	236	return -ENOMEM;
	237	spawn = shash_instance_ctx(inst);
	238
	239	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
	240	crypto_attr_alg_name(tb[1]), 0, 0);
	241	if (err)
	242	goto err_free_inst;
	243	alg = crypto_spawn_cipher_alg(spawn);
93b5e86a JK	244
	245	switch (alg->cra_blocksize) {
	246	case 16:
	247	case 8:
	248	break;
	249	default:
48ee41bf	250	err = -EINVAL;
1d0459cd	251	goto err_free_inst;
93b5e86a JK	252	}
93b5e86a JK	253
1d0459cd	254	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
93b5e86a	255	if (err)
1d0459cd	256	goto err_free_inst;
93b5e86a	257
db91af0f	258	alignmask = alg->cra_alignmask;
93b5e86a JK	259	inst->alg.base.cra_alignmask = alignmask;
	260	inst->alg.base.cra_priority = alg->cra_priority;
	261	inst->alg.base.cra_blocksize = alg->cra_blocksize;
	262
	263	inst->alg.digestsize = alg->cra_blocksize;
	264	inst->alg.descsize =
	265	ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
	266	+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
	267	+ alg->cra_blocksize * 2;
	268
	269	inst->alg.base.cra_ctxsize =
f16743e0 EB	270	ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment())
	271	+ ((alignmask \| (__alignof__(__be64) - 1)) &
	272	~(crypto_tfm_ctx_alignment() - 1))
93b5e86a JK	273	+ alg->cra_blocksize * 2;
	274
	275	inst->alg.base.cra_init = cmac_init_tfm;
	276	inst->alg.base.cra_exit = cmac_exit_tfm;
	277
	278	inst->alg.init = crypto_cmac_digest_init;
	279	inst->alg.update = crypto_cmac_digest_update;
	280	inst->alg.final = crypto_cmac_digest_final;
	281	inst->alg.setkey = crypto_cmac_digest_setkey;
	282
	283	err = shash_register_instance(tmpl, inst);
	284	if (err) {
1d0459cd	285	err_free_inst:
93b5e86a JK	286	shash_free_instance(shash_crypto_instance(inst));
93b5e86a JK	287	}
93b5e86a JK	288	return err;
	289	}
	290
	291	static struct crypto_template crypto_cmac_tmpl = {
	292	.name = "cmac",
	293	.create = cmac_create,
	294	.free = shash_free_instance,
	295	.module = THIS_MODULE,
	296	};
	297
	298	static int __init crypto_cmac_module_init(void)
	299	{
	300	return crypto_register_template(&crypto_cmac_tmpl);
	301	}
	302
	303	static void __exit crypto_cmac_module_exit(void)
	304	{
	305	crypto_unregister_template(&crypto_cmac_tmpl);
	306	}
	307
c4741b23	308	subsys_initcall(crypto_cmac_module_init);
93b5e86a JK	309	module_exit(crypto_cmac_module_exit);
	310
	311	MODULE_LICENSE("GPL");
	312	MODULE_DESCRIPTION("CMAC keyed hash algorithm");
4943ba16	313	MODULE_ALIAS_CRYPTO("cmac");