[linux-block.git] / crypto / cmac.c

// SPDX-License-Identifier: GPL-2.0-or-later
/*
 * CMAC: Cipher Block Mode for Authentication
 *
 * Copyright © 2013 Jussi Kivilinna <jussi.kivilinna@iki.fi>
 *
 * Based on work by:
 *  Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
 * Based on crypto/xcbc.c:
 *  Copyright © 2006 USAGI/WIDE Project,
 *   Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
 */

#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;
	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_cipher_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;
	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;

	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;

	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 <jussi.kivilinna@iki.fi>
	6	*
	7	* Based on work by:
	8	* Copyright © 2013 Tom St Denis <tstdenis@elliptictech.com>
	9	* Based on crypto/xcbc.c:
	10	* Copyright © 2006 USAGI/WIDE Project,
	11	* Author: Kazunori Miyazawa <miyazawa@linux-ipv6.org>
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;
	31	u8 ctx[];
	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;
	47	u8 ctx[];
	48	};
	49
	50	static int crypto_cmac_digest_setkey(struct crypto_shash *parent,
	51	const u8 *inkey, unsigned int keylen)
	52	{
	53	unsigned long alignmask = crypto_shash_alignmask(parent);
	54	struct cmac_tfm_ctx *ctx = crypto_shash_ctx(parent);
	55	unsigned int bs = crypto_shash_blocksize(parent);
f16743e0 EB	56	__be64 consts = PTR_ALIGN((void )ctx->ctx,
f16743e0 EB	57	(alignmask \| (__alignof__(__be64) - 1)) + 1);
93b5e86a JK	58	u64 _const[2];
	59	int i, err = 0;
	60	u8 msb_mask, gfmask;
	61
	62	err = crypto_cipher_setkey(ctx->child, inkey, keylen);
	63	if (err)
	64	return err;
	65
	66	/* encrypt the zero block */
	67	memset(consts, 0, bs);
	68	crypto_cipher_encrypt_one(ctx->child, (u8 )consts, (u8 )consts);
	69
	70	switch (bs) {
	71	case 16:
	72	gfmask = 0x87;
	73	_const[0] = be64_to_cpu(consts[1]);
	74	_const[1] = be64_to_cpu(consts[0]);
	75
	76	/* gf(2^128) multiply zero-ciphertext with u and u^2 */
	77	for (i = 0; i < 4; i += 2) {
	78	msb_mask = ((s64)_const[1] >> 63) & gfmask;
	79	_const[1] = (_const[1] << 1) \| (_const[0] >> 63);
	80	_const[0] = (_const[0] << 1) ^ msb_mask;
	81
	82	consts[i + 0] = cpu_to_be64(_const[1]);
	83	consts[i + 1] = cpu_to_be64(_const[0]);
	84	}
	85
	86	break;
	87	case 8:
	88	gfmask = 0x1B;
	89	_const[0] = be64_to_cpu(consts[0]);
	90
	91	/* gf(2^64) multiply zero-ciphertext with u and u^2 */
	92	for (i = 0; i < 2; i++) {
	93	msb_mask = ((s64)_const[0] >> 63) & gfmask;
	94	_const[0] = (_const[0] << 1) ^ msb_mask;
	95
	96	consts[i] = cpu_to_be64(_const[0]);
	97	}
	98
	99	break;
	100	}
	101
	102	return 0;
	103	}
	104
	105	static int crypto_cmac_digest_init(struct shash_desc *pdesc)
	106	{
	107	unsigned long alignmask = crypto_shash_alignmask(pdesc->tfm);
	108	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
	109	int bs = crypto_shash_blocksize(pdesc->tfm);
	110	u8 prev = PTR_ALIGN((void )ctx->ctx, alignmask + 1) + bs;
	111
	112	ctx->len = 0;
	113	memset(prev, 0, bs);
	114
	115	return 0;
	116	}
	117
	118	static int crypto_cmac_digest_update(struct shash_desc pdesc, const u8 p,
	119	unsigned int len)
	120	{
	121	struct crypto_shash *parent = pdesc->tfm;
122	unsigned long alignmask = crypto_shash_alignmask(parent);
123	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
124	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
125	struct crypto_cipher *tfm = tctx->child;
126	int bs = crypto_shash_blocksize(parent);
127	u8 odds = PTR_ALIGN((void )ctx->ctx, alignmask + 1);
128	u8 *prev = odds + bs;
129
130	/* checking the data can fill the block */
131	if ((ctx->len + len) <= bs) {
132	memcpy(odds + ctx->len, p, len);
133	ctx->len += len;
134	return 0;
135	}
136
137	/* filling odds with new data and encrypting it */
138	memcpy(odds + ctx->len, p, bs - ctx->len);
139	len -= bs - ctx->len;
140	p += bs - ctx->len;
141
142	crypto_xor(prev, odds, bs);
143	crypto_cipher_encrypt_one(tfm, prev, prev);
144
145	/* clearing the length */
146	ctx->len = 0;
147
148	/* encrypting the rest of data */
149	while (len > bs) {
150	crypto_xor(prev, p, bs);
151	crypto_cipher_encrypt_one(tfm, prev, prev);
152	p += bs;
153	len -= bs;
154	}
155
156	/* keeping the surplus of blocksize */
157	if (len) {
158	memcpy(odds, p, len);
159	ctx->len = len;
160	}
161
162	return 0;
163	}
164
165	static int crypto_cmac_digest_final(struct shash_desc pdesc, u8 out)
166	{
167	struct crypto_shash *parent = pdesc->tfm;
168	unsigned long alignmask = crypto_shash_alignmask(parent);
169	struct cmac_tfm_ctx *tctx = crypto_shash_ctx(parent);
170	struct cmac_desc_ctx *ctx = shash_desc_ctx(pdesc);
171	struct crypto_cipher *tfm = tctx->child;
172	int bs = crypto_shash_blocksize(parent);
f16743e0 EB	173	u8 consts = PTR_ALIGN((void )tctx->ctx,
f16743e0 EB	174	(alignmask \| (__alignof__(__be64) - 1)) + 1);
93b5e86a JK	175	u8 odds = PTR_ALIGN((void )ctx->ctx, alignmask + 1);
	176	u8 *prev = odds + bs;
	177	unsigned int offset = 0;
	178
	179	if (ctx->len != bs) {
	180	unsigned int rlen;
	181	u8 *p = odds + ctx->len;
	182
	183	*p = 0x80;
	184	p++;
	185
	186	rlen = bs - ctx->len - 1;
	187	if (rlen)
	188	memset(p, 0, rlen);
	189
	190	offset += bs;
	191	}
	192
	193	crypto_xor(prev, odds, bs);
	194	crypto_xor(prev, consts + offset, bs);
	195
	196	crypto_cipher_encrypt_one(tfm, out, prev);
	197
	198	return 0;
	199	}
	200
	201	static int cmac_init_tfm(struct crypto_tfm *tfm)
	202	{
	203	struct crypto_cipher *cipher;
	204	struct crypto_instance inst = (void )tfm->__crt_alg;
d5ed3b65	205	struct crypto_cipher_spawn *spawn = crypto_instance_ctx(inst);
93b5e86a JK	206	struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
	207
	208	cipher = crypto_spawn_cipher(spawn);
	209	if (IS_ERR(cipher))
	210	return PTR_ERR(cipher);
	211
	212	ctx->child = cipher;
	213
	214	return 0;
	215	};
	216
	217	static void cmac_exit_tfm(struct crypto_tfm *tfm)
	218	{
	219	struct cmac_tfm_ctx *ctx = crypto_tfm_ctx(tfm);
	220	crypto_free_cipher(ctx->child);
	221	}
	222
	223	static int cmac_create(struct crypto_template tmpl, struct rtattr *tb)
	224	{
	225	struct shash_instance *inst;
1d0459cd	226	struct crypto_cipher_spawn *spawn;
93b5e86a JK	227	struct crypto_alg *alg;
93b5e86a JK	228	unsigned long alignmask;
7bcb2c99	229	u32 mask;
93b5e86a JK	230	int err;
93b5e86a JK	231
7bcb2c99	232	err = crypto_check_attr_type(tb, CRYPTO_ALG_TYPE_SHASH, &mask);
93b5e86a JK	233	if (err)
	234	return err;
	235
1d0459cd EB	236	inst = kzalloc(sizeof(inst) + sizeof(spawn), GFP_KERNEL);
	237	if (!inst)
	238	return -ENOMEM;
	239	spawn = shash_instance_ctx(inst);
	240
	241	err = crypto_grab_cipher(spawn, shash_crypto_instance(inst),
7bcb2c99	242	crypto_attr_alg_name(tb[1]), 0, mask);
1d0459cd EB	243	if (err)
	244	goto err_free_inst;
	245	alg = crypto_spawn_cipher_alg(spawn);
93b5e86a JK	246
	247	switch (alg->cra_blocksize) {
	248	case 16:
	249	case 8:
	250	break;
	251	default:
48ee41bf	252	err = -EINVAL;
1d0459cd	253	goto err_free_inst;
93b5e86a JK	254	}
93b5e86a JK	255
1d0459cd	256	err = crypto_inst_setname(shash_crypto_instance(inst), tmpl->name, alg);
93b5e86a	257	if (err)
1d0459cd	258	goto err_free_inst;
93b5e86a	259
db91af0f	260	alignmask = alg->cra_alignmask;
93b5e86a JK	261	inst->alg.base.cra_alignmask = alignmask;
	262	inst->alg.base.cra_priority = alg->cra_priority;
	263	inst->alg.base.cra_blocksize = alg->cra_blocksize;
	264
	265	inst->alg.digestsize = alg->cra_blocksize;
	266	inst->alg.descsize =
	267	ALIGN(sizeof(struct cmac_desc_ctx), crypto_tfm_ctx_alignment())
	268	+ (alignmask & ~(crypto_tfm_ctx_alignment() - 1))
	269	+ alg->cra_blocksize * 2;
	270
	271	inst->alg.base.cra_ctxsize =
f16743e0 EB	272	ALIGN(sizeof(struct cmac_tfm_ctx), crypto_tfm_ctx_alignment())
	273	+ ((alignmask \| (__alignof__(__be64) - 1)) &
	274	~(crypto_tfm_ctx_alignment() - 1))
93b5e86a JK	275	+ alg->cra_blocksize * 2;
	276
	277	inst->alg.base.cra_init = cmac_init_tfm;
	278	inst->alg.base.cra_exit = cmac_exit_tfm;
	279
	280	inst->alg.init = crypto_cmac_digest_init;
	281	inst->alg.update = crypto_cmac_digest_update;
	282	inst->alg.final = crypto_cmac_digest_final;
	283	inst->alg.setkey = crypto_cmac_digest_setkey;
	284
a39c66cc EB	285	inst->free = shash_free_singlespawn_instance;
a39c66cc EB	286
93b5e86a JK	287	err = shash_register_instance(tmpl, inst);
93b5e86a JK	288	if (err) {
1d0459cd	289	err_free_inst:
a39c66cc	290	shash_free_singlespawn_instance(inst);
93b5e86a	291	}
93b5e86a JK	292	return err;
	293	}
	294
	295	static struct crypto_template crypto_cmac_tmpl = {
	296	.name = "cmac",
	297	.create = cmac_create,
93b5e86a JK	298	.module = THIS_MODULE,
	299	};
	300
	301	static int __init crypto_cmac_module_init(void)
	302	{
	303	return crypto_register_template(&crypto_cmac_tmpl);
	304	}
	305
	306	static void __exit crypto_cmac_module_exit(void)
	307	{
	308	crypto_unregister_template(&crypto_cmac_tmpl);
	309	}
	310
c4741b23	311	subsys_initcall(crypto_cmac_module_init);
93b5e86a JK	312	module_exit(crypto_cmac_module_exit);
	313
	314	MODULE_LICENSE("GPL");
	315	MODULE_DESCRIPTION("CMAC keyed hash algorithm");
4943ba16	316	MODULE_ALIAS_CRYPTO("cmac");
0eb76ba2	317	MODULE_IMPORT_NS(CRYPTO_INTERNAL);