[linux.git] / crypto / ecdh.c

// SPDX-License-Identifier: GPL-2.0-or-later
/* ECDH key-agreement protocol
 *
 * Copyright (c) 2016, Intel Corporation
 * Authors: Salvator Benedetto <[email protected]>
 */

#include <linux/module.h>
#include <crypto/internal/ecc.h>
#include <crypto/internal/kpp.h>
#include <crypto/kpp.h>
#include <crypto/ecdh.h>
#include <linux/scatterlist.h>

struct ecdh_ctx {
	unsigned int curve_id;
	unsigned int ndigits;
	u64 private_key[ECC_MAX_DIGITS];
};

static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
{
	return kpp_tfm_ctx(tfm);
}

static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
			   unsigned int len)
{
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	struct ecdh params;
	int ret = 0;

	if (crypto_ecdh_decode_key(buf, len, &params) < 0 ||
	    params.key_size > sizeof(u64) * ctx->ndigits)
		return -EINVAL;

	memset(ctx->private_key, 0, sizeof(ctx->private_key));

	if (!params.key || !params.key_size)
		return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
				       ctx->private_key);

	ecc_digits_from_bytes(params.key, params.key_size,
			      ctx->private_key, ctx->ndigits);

	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
			     ctx->private_key, params.key_size) < 0) {
		memzero_explicit(ctx->private_key, params.key_size);
		ret = -EINVAL;
	}

	return ret;
}

static int ecdh_compute_value(struct kpp_request *req)
{
	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	u64 *public_key;
	u64 *shared_secret = NULL;
	void *buf;
	size_t copied, nbytes, public_key_sz;
	int ret = -ENOMEM;

	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
	/* Public part is a point thus it has both coordinates */
	public_key_sz = 2 * nbytes;

	public_key = kmalloc(public_key_sz, GFP_KERNEL);
	if (!public_key)
		return -ENOMEM;

	if (req->src) {
		shared_secret = kmalloc(nbytes, GFP_KERNEL);
		if (!shared_secret)
			goto free_pubkey;

		/* from here on it's invalid parameters */
		ret = -EINVAL;

		/* must have exactly two points to be on the curve */
		if (public_key_sz != req->src_len)
			goto free_all;

		copied = sg_copy_to_buffer(req->src,
					   sg_nents_for_len(req->src,
							    public_key_sz),
					   public_key, public_key_sz);
		if (copied != public_key_sz)
			goto free_all;

		ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
						ctx->private_key, public_key,
						shared_secret);

		buf = shared_secret;
	} else {
		ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
				       ctx->private_key, public_key);
		buf = public_key;
		nbytes = public_key_sz;
	}

	if (ret < 0)
		goto free_all;

	/* might want less than we've got */
	nbytes = min_t(size_t, nbytes, req->dst_len);
	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
								nbytes),
				     buf, nbytes);
	if (copied != nbytes)
		ret = -EINVAL;

	/* fall through */
free_all:
	kfree_sensitive(shared_secret);
free_pubkey:
	kfree(public_key);
	return ret;
}

static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
{
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);

	/* Public key is made of two coordinates, add one to the left shift */
	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
}

static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm)
{
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);

	ctx->curve_id = ECC_CURVE_NIST_P192;
	ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS;

	return 0;
}

static struct kpp_alg ecdh_nist_p192 = {
	.set_secret = ecdh_set_secret,
	.generate_public_key = ecdh_compute_value,
	.compute_shared_secret = ecdh_compute_value,
	.max_size = ecdh_max_size,
	.init = ecdh_nist_p192_init_tfm,
	.base = {
		.cra_name = "ecdh-nist-p192",
		.cra_driver_name = "ecdh-nist-p192-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecdh_ctx),
	},
};

static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
{
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);

	ctx->curve_id = ECC_CURVE_NIST_P256;
	ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS;

	return 0;
}

static struct kpp_alg ecdh_nist_p256 = {
	.set_secret = ecdh_set_secret,
	.generate_public_key = ecdh_compute_value,
	.compute_shared_secret = ecdh_compute_value,
	.max_size = ecdh_max_size,
	.init = ecdh_nist_p256_init_tfm,
	.base = {
		.cra_name = "ecdh-nist-p256",
		.cra_driver_name = "ecdh-nist-p256-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecdh_ctx),
	},
};

static int ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm)
{
	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);

	ctx->curve_id = ECC_CURVE_NIST_P384;
	ctx->ndigits = ECC_CURVE_NIST_P384_DIGITS;

	return 0;
}

static struct kpp_alg ecdh_nist_p384 = {
	.set_secret = ecdh_set_secret,
	.generate_public_key = ecdh_compute_value,
	.compute_shared_secret = ecdh_compute_value,
	.max_size = ecdh_max_size,
	.init = ecdh_nist_p384_init_tfm,
	.base = {
		.cra_name = "ecdh-nist-p384",
		.cra_driver_name = "ecdh-nist-p384-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecdh_ctx),
	},
};

static bool ecdh_nist_p192_registered;

static int __init ecdh_init(void)
{
	int ret;

	/* NIST p192 will fail to register in FIPS mode */
	ret = crypto_register_kpp(&ecdh_nist_p192);
	ecdh_nist_p192_registered = ret == 0;

	ret = crypto_register_kpp(&ecdh_nist_p256);
	if (ret)
		goto nist_p256_error;

	ret = crypto_register_kpp(&ecdh_nist_p384);
	if (ret)
		goto nist_p384_error;

	return 0;

nist_p384_error:
	crypto_unregister_kpp(&ecdh_nist_p256);

nist_p256_error:
	if (ecdh_nist_p192_registered)
		crypto_unregister_kpp(&ecdh_nist_p192);
	return ret;
}

static void __exit ecdh_exit(void)
{
	if (ecdh_nist_p192_registered)
		crypto_unregister_kpp(&ecdh_nist_p192);
	crypto_unregister_kpp(&ecdh_nist_p256);
	crypto_unregister_kpp(&ecdh_nist_p384);
}

subsys_initcall(ecdh_init);
module_exit(ecdh_exit);
MODULE_ALIAS_CRYPTO("ecdh");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ECDH generic algorithm");
Commit	Line	Data
2874c5fd	1	// SPDX-License-Identifier: GPL-2.0-or-later
3c4b2390 SB	2	/* ECDH key-agreement protocol
	3	*
	4	* Copyright (c) 2016, Intel Corporation
	5	* Authors: Salvator Benedetto <[email protected]>
3c4b2390 SB	6	*/
	7
	8	#include <linux/module.h>
a745d3ac	9	#include <crypto/internal/ecc.h>
3c4b2390 SB	10	#include <crypto/internal/kpp.h>
	11	#include <crypto/kpp.h>
	12	#include <crypto/ecdh.h>
	13	#include <linux/scatterlist.h>
3c4b2390 SB	14
	15	struct ecdh_ctx {
	16	unsigned int curve_id;
	17	unsigned int ndigits;
	18	u64 private_key[ECC_MAX_DIGITS];
3c4b2390 SB	19	};
	20
	21	static inline struct ecdh_ctx ecdh_get_ctx(struct crypto_kpp tfm)
	22	{
	23	return kpp_tfm_ctx(tfm);
	24	}
	25
5527dfb6 EB	26	static int ecdh_set_secret(struct crypto_kpp tfm, const void buf,
5527dfb6 EB	27	unsigned int len)
3c4b2390 SB	28	{
	29	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	30	struct ecdh params;
bd955a4e	31	int ret = 0;
3c4b2390	32
0aa171e9	33	if (crypto_ecdh_decode_key(buf, len, &params) < 0 \|\|
6763f5ea	34	params.key_size > sizeof(u64) * ctx->ndigits)
3c4b2390 SB	35	return -EINVAL;
3c4b2390 SB	36
73e5984e JV	37	memset(ctx->private_key, 0, sizeof(ctx->private_key));
73e5984e JV	38
6755fd26 TA	39	if (!params.key \|\| !params.key_size)
	40	return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
	41	ctx->private_key);
	42
01474b70 SB	43	ecc_digits_from_bytes(params.key, params.key_size,
01474b70 SB	44	ctx->private_key, ctx->ndigits);
3c4b2390	45
17858b14	46	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
01474b70	47	ctx->private_key, params.key_size) < 0) {
17858b14	48	memzero_explicit(ctx->private_key, params.key_size);
bd955a4e	49	ret = -EINVAL;
17858b14	50	}
bd955a4e SB	51
bd955a4e SB	52	return ret;
3c4b2390 SB	53	}
	54
	55	static int ecdh_compute_value(struct kpp_request *req)
	56	{
3c4b2390 SB	57	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
3c4b2390 SB	58	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
952035ba TA	59	u64 *public_key;
952035ba TA	60	u64 *shared_secret = NULL;
3c4b2390	61	void *buf;
952035ba TA	62	size_t copied, nbytes, public_key_sz;
952035ba TA	63	int ret = -ENOMEM;
3c4b2390 SB	64
3c4b2390 SB	65	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
952035ba TA	66	/* Public part is a point thus it has both coordinates */
	67	public_key_sz = 2 * nbytes;
	68
	69	public_key = kmalloc(public_key_sz, GFP_KERNEL);
	70	if (!public_key)
	71	return -ENOMEM;
3c4b2390 SB	72
3c4b2390 SB	73	if (req->src) {
952035ba TA	74	shared_secret = kmalloc(nbytes, GFP_KERNEL);
	75	if (!shared_secret)
	76	goto free_pubkey;
	77
95ec01ba JB	78	/* from here on it's invalid parameters */
	79	ret = -EINVAL;
	80
	81	/* must have exactly two points to be on the curve */
	82	if (public_key_sz != req->src_len)
	83	goto free_all;
	84
	85	copied = sg_copy_to_buffer(req->src,
	86	sg_nents_for_len(req->src,
	87	public_key_sz),
	88	public_key, public_key_sz);
	89	if (copied != public_key_sz)
952035ba	90	goto free_all;
3c4b2390	91
8f44df15	92	ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
952035ba TA	93	ctx->private_key, public_key,
952035ba TA	94	shared_secret);
3c4b2390	95
952035ba	96	buf = shared_secret;
3c4b2390	97	} else {
7380c56d	98	ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
952035ba TA	99	ctx->private_key, public_key);
	100	buf = public_key;
	101	nbytes = public_key_sz;
3c4b2390 SB	102	}
	103
	104	if (ret < 0)
952035ba	105	goto free_all;
3c4b2390	106
95ec01ba JB	107	/* might want less than we've got */
	108	nbytes = min_t(size_t, nbytes, req->dst_len);
	109	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
	110	nbytes),
	111	buf, nbytes);
3c4b2390	112	if (copied != nbytes)
952035ba	113	ret = -EINVAL;
3c4b2390	114
952035ba TA	115	/* fall through */
952035ba TA	116	free_all:
453431a5	117	kfree_sensitive(shared_secret);
952035ba TA	118	free_pubkey:
952035ba TA	119	kfree(public_key);
3c4b2390 SB	120	return ret;
	121	}
	122
d0efb48b	123	static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
3c4b2390 SB	124	{
3c4b2390 SB	125	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
3c4b2390	126
d0efb48b TA	127	/* Public key is made of two coordinates, add one to the left shift */
d0efb48b TA	128	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
3c4b2390 SB	129	}
3c4b2390 SB	130
6763f5ea MY	131	static int ecdh_nist_p192_init_tfm(struct crypto_kpp *tfm)
	132	{
	133	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	134
	135	ctx->curve_id = ECC_CURVE_NIST_P192;
	136	ctx->ndigits = ECC_CURVE_NIST_P192_DIGITS;
	137
	138	return 0;
	139	}
	140
	141	static struct kpp_alg ecdh_nist_p192 = {
3c4b2390 SB	142	.set_secret = ecdh_set_secret,
	143	.generate_public_key = ecdh_compute_value,
	144	.compute_shared_secret = ecdh_compute_value,
	145	.max_size = ecdh_max_size,
6763f5ea	146	.init = ecdh_nist_p192_init_tfm,
3c4b2390	147	.base = {
6763f5ea	148	.cra_name = "ecdh-nist-p192",
c5ae16f5	149	.cra_driver_name = "ecdh-nist-p192-generic",
3c4b2390 SB	150	.cra_priority = 100,
	151	.cra_module = THIS_MODULE,
	152	.cra_ctxsize = sizeof(struct ecdh_ctx),
	153	},
	154	};
	155
6763f5ea MY	156	static int ecdh_nist_p256_init_tfm(struct crypto_kpp *tfm)
	157	{
	158	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	159
	160	ctx->curve_id = ECC_CURVE_NIST_P256;
	161	ctx->ndigits = ECC_CURVE_NIST_P256_DIGITS;
	162
	163	return 0;
	164	}
	165
	166	static struct kpp_alg ecdh_nist_p256 = {
	167	.set_secret = ecdh_set_secret,
	168	.generate_public_key = ecdh_compute_value,
	169	.compute_shared_secret = ecdh_compute_value,
	170	.max_size = ecdh_max_size,
	171	.init = ecdh_nist_p256_init_tfm,
	172	.base = {
	173	.cra_name = "ecdh-nist-p256",
c5ae16f5	174	.cra_driver_name = "ecdh-nist-p256-generic",
6763f5ea MY	175	.cra_priority = 100,
	176	.cra_module = THIS_MODULE,
	177	.cra_ctxsize = sizeof(struct ecdh_ctx),
	178	},
	179	};
	180
81541325 HT	181	static int ecdh_nist_p384_init_tfm(struct crypto_kpp *tfm)
	182	{
	183	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	184
	185	ctx->curve_id = ECC_CURVE_NIST_P384;
	186	ctx->ndigits = ECC_CURVE_NIST_P384_DIGITS;
	187
	188	return 0;
	189	}
	190
	191	static struct kpp_alg ecdh_nist_p384 = {
	192	.set_secret = ecdh_set_secret,
	193	.generate_public_key = ecdh_compute_value,
	194	.compute_shared_secret = ecdh_compute_value,
	195	.max_size = ecdh_max_size,
	196	.init = ecdh_nist_p384_init_tfm,
	197	.base = {
	198	.cra_name = "ecdh-nist-p384",
	199	.cra_driver_name = "ecdh-nist-p384-generic",
	200	.cra_priority = 100,
	201	.cra_module = THIS_MODULE,
	202	.cra_ctxsize = sizeof(struct ecdh_ctx),
	203	},
	204	};
	205
6763f5ea MY	206	static bool ecdh_nist_p192_registered;
6763f5ea MY	207
33837be3	208	static int __init ecdh_init(void)
3c4b2390	209	{
6763f5ea MY	210	int ret;
6763f5ea MY	211
6889fc21	212	/* NIST p192 will fail to register in FIPS mode */
6763f5ea MY	213	ret = crypto_register_kpp(&ecdh_nist_p192);
	214	ecdh_nist_p192_registered = ret == 0;
	215
8fd28fa5 HT	216	ret = crypto_register_kpp(&ecdh_nist_p256);
	217	if (ret)
	218	goto nist_p256_error;
	219
81541325 HT	220	ret = crypto_register_kpp(&ecdh_nist_p384);
	221	if (ret)
	222	goto nist_p384_error;
	223
8fd28fa5 HT	224	return 0;
8fd28fa5 HT	225
81541325 HT	226	nist_p384_error:
	227	crypto_unregister_kpp(&ecdh_nist_p256);
	228
8fd28fa5 HT	229	nist_p256_error:
	230	if (ecdh_nist_p192_registered)
	231	crypto_unregister_kpp(&ecdh_nist_p192);
	232	return ret;
3c4b2390 SB	233	}
3c4b2390 SB	234
33837be3	235	static void __exit ecdh_exit(void)
3c4b2390	236	{
6763f5ea MY	237	if (ecdh_nist_p192_registered)
	238	crypto_unregister_kpp(&ecdh_nist_p192);
	239	crypto_unregister_kpp(&ecdh_nist_p256);
81541325	240	crypto_unregister_kpp(&ecdh_nist_p384);
3c4b2390 SB	241	}
3c4b2390 SB	242
c4741b23	243	subsys_initcall(ecdh_init);
3c4b2390 SB	244	module_exit(ecdh_exit);
	245	MODULE_ALIAS_CRYPTO("ecdh");
	246	MODULE_LICENSE("GPL");
	247	MODULE_DESCRIPTION("ECDH generic algorithm");