[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/kpp.h>
#include <crypto/kpp.h>
#include <crypto/ecdh.h>
#include <linux/scatterlist.h>
#include "ecc.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;

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

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

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

	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);
		return -EINVAL;
	}
	return 0;
}

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