[thirdparty/kernel/stable.git] / crypto / ecdh.c

/* ECDH key-agreement protocol
 *
 * Copyright (c) 2016, Intel Corporation
 * Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License
 * as published by the Free Software Foundation; either version
 * 2 of the License, or (at your option) any later version.
 */

#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 unsigned int ecdh_supported_curve(unsigned int curve_id)
{
	switch (curve_id) {
	case ECC_CURVE_NIST_P192: return ECC_CURVE_NIST_P192_DIGITS;
	case ECC_CURVE_NIST_P256: return ECC_CURVE_NIST_P256_DIGITS;
	default: return 0;
	}
}

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;
	unsigned int ndigits;

	if (crypto_ecdh_decode_key(buf, len, &params) < 0)
		return -EINVAL;

	ndigits = ecdh_supported_curve(params.curve_id);
	if (!ndigits)
		return -EINVAL;

	ctx->curve_id = params.curve_id;
	ctx->ndigits = ndigits;

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

	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
			     (const u64 *)params.key, params.key_size) < 0)
		return -EINVAL;

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

	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:
	kzfree(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 struct kpp_alg ecdh = {
	.set_secret = ecdh_set_secret,
	.generate_public_key = ecdh_compute_value,
	.compute_shared_secret = ecdh_compute_value,
	.max_size = ecdh_max_size,
	.base = {
		.cra_name = "ecdh",
		.cra_driver_name = "ecdh-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct ecdh_ctx),
	},
};

static int ecdh_init(void)
{
	return crypto_register_kpp(&ecdh);
}

static void ecdh_exit(void)
{
	crypto_unregister_kpp(&ecdh);
}

subsys_initcall(ecdh_init);
module_exit(ecdh_exit);
MODULE_ALIAS_CRYPTO("ecdh");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("ECDH generic algorithm");
Commit	Line	Data
3c4b2390 SB	1	/* ECDH key-agreement protocol
	2	*
	3	* Copyright (c) 2016, Intel Corporation
	4	* Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
	5	*
	6	* This program is free software; you can redistribute it and/or
c0ca1215	7	* modify it under the terms of the GNU General Public License
3c4b2390	8	* as published by the Free Software Foundation; either version
c0ca1215	9	* 2 of the License, or (at your option) any later version.
3c4b2390 SB	10	*/
	11
	12	#include <linux/module.h>
	13	#include <crypto/internal/kpp.h>
	14	#include <crypto/kpp.h>
	15	#include <crypto/ecdh.h>
	16	#include <linux/scatterlist.h>
	17	#include "ecc.h"
	18
	19	struct ecdh_ctx {
	20	unsigned int curve_id;
	21	unsigned int ndigits;
	22	u64 private_key[ECC_MAX_DIGITS];
3c4b2390 SB	23	};
	24
	25	static inline struct ecdh_ctx ecdh_get_ctx(struct crypto_kpp tfm)
	26	{
	27	return kpp_tfm_ctx(tfm);
	28	}
	29
	30	static unsigned int ecdh_supported_curve(unsigned int curve_id)
	31	{
	32	switch (curve_id) {
d5c3b178 KC	33	case ECC_CURVE_NIST_P192: return ECC_CURVE_NIST_P192_DIGITS;
d5c3b178 KC	34	case ECC_CURVE_NIST_P256: return ECC_CURVE_NIST_P256_DIGITS;
3c4b2390 SB	35	default: return 0;
	36	}
	37	}
	38
5527dfb6 EB	39	static int ecdh_set_secret(struct crypto_kpp tfm, const void buf,
5527dfb6 EB	40	unsigned int len)
3c4b2390 SB	41	{
	42	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
	43	struct ecdh params;
	44	unsigned int ndigits;
	45
	46	if (crypto_ecdh_decode_key(buf, len, &params) < 0)
	47	return -EINVAL;
	48
	49	ndigits = ecdh_supported_curve(params.curve_id);
	50	if (!ndigits)
	51	return -EINVAL;
	52
	53	ctx->curve_id = params.curve_id;
	54	ctx->ndigits = ndigits;
	55
6755fd26 TA	56	if (!params.key \|\| !params.key_size)
	57	return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
	58	ctx->private_key);
	59
3c4b2390	60	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
ad269597	61	(const u64 *)params.key, params.key_size) < 0)
3c4b2390 SB	62	return -EINVAL;
	63
	64	memcpy(ctx->private_key, params.key, params.key_size);
	65
	66	return 0;
	67	}
	68
	69	static int ecdh_compute_value(struct kpp_request *req)
	70	{
3c4b2390 SB	71	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
3c4b2390 SB	72	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
952035ba TA	73	u64 *public_key;
952035ba TA	74	u64 *shared_secret = NULL;
3c4b2390	75	void *buf;
952035ba TA	76	size_t copied, nbytes, public_key_sz;
952035ba TA	77	int ret = -ENOMEM;
3c4b2390 SB	78
3c4b2390 SB	79	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
952035ba TA	80	/* Public part is a point thus it has both coordinates */
	81	public_key_sz = 2 * nbytes;
	82
	83	public_key = kmalloc(public_key_sz, GFP_KERNEL);
	84	if (!public_key)
	85	return -ENOMEM;
3c4b2390 SB	86
3c4b2390 SB	87	if (req->src) {
952035ba TA	88	shared_secret = kmalloc(nbytes, GFP_KERNEL);
	89	if (!shared_secret)
	90	goto free_pubkey;
	91
95ec01ba JB	92	/* from here on it's invalid parameters */
	93	ret = -EINVAL;
	94
	95	/* must have exactly two points to be on the curve */
	96	if (public_key_sz != req->src_len)
	97	goto free_all;
	98
	99	copied = sg_copy_to_buffer(req->src,
	100	sg_nents_for_len(req->src,
	101	public_key_sz),
	102	public_key, public_key_sz);
	103	if (copied != public_key_sz)
952035ba	104	goto free_all;
3c4b2390	105
8f44df15	106	ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
952035ba TA	107	ctx->private_key, public_key,
952035ba TA	108	shared_secret);
3c4b2390	109
952035ba	110	buf = shared_secret;
3c4b2390	111	} else {
7380c56d	112	ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
952035ba TA	113	ctx->private_key, public_key);
	114	buf = public_key;
	115	nbytes = public_key_sz;
3c4b2390 SB	116	}
	117
	118	if (ret < 0)
952035ba	119	goto free_all;
3c4b2390	120
95ec01ba JB	121	/* might want less than we've got */
	122	nbytes = min_t(size_t, nbytes, req->dst_len);
	123	copied = sg_copy_from_buffer(req->dst, sg_nents_for_len(req->dst,
	124	nbytes),
	125	buf, nbytes);
3c4b2390	126	if (copied != nbytes)
952035ba	127	ret = -EINVAL;
3c4b2390	128
952035ba TA	129	/* fall through */
	130	free_all:
	131	kzfree(shared_secret);
	132	free_pubkey:
	133	kfree(public_key);
3c4b2390 SB	134	return ret;
	135	}
	136
d0efb48b	137	static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
3c4b2390 SB	138	{
3c4b2390 SB	139	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
3c4b2390	140
d0efb48b TA	141	/* Public key is made of two coordinates, add one to the left shift */
d0efb48b TA	142	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
3c4b2390 SB	143	}
3c4b2390 SB	144
3c4b2390 SB	145	static struct kpp_alg ecdh = {
	146	.set_secret = ecdh_set_secret,
	147	.generate_public_key = ecdh_compute_value,
	148	.compute_shared_secret = ecdh_compute_value,
	149	.max_size = ecdh_max_size,
3c4b2390 SB	150	.base = {
	151	.cra_name = "ecdh",
	152	.cra_driver_name = "ecdh-generic",
	153	.cra_priority = 100,
	154	.cra_module = THIS_MODULE,
	155	.cra_ctxsize = sizeof(struct ecdh_ctx),
	156	},
	157	};
	158
	159	static int ecdh_init(void)
	160	{
	161	return crypto_register_kpp(&ecdh);
	162	}
	163
	164	static void ecdh_exit(void)
	165	{
	166	crypto_unregister_kpp(&ecdh);
	167	}
	168
c4741b23	169	subsys_initcall(ecdh_init);
3c4b2390 SB	170	module_exit(ecdh_exit);
	171	MODULE_ALIAS_CRYPTO("ecdh");
	172	MODULE_LICENSE("GPL");
	173	MODULE_DESCRIPTION("ECDH generic algorithm");