[linux-block.git] / net / bluetooth / ecdh_helper.c

/*
 * ECDH helper functions - KPP wrappings
 *
 * Copyright (C) 2017 Intel Corporation
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation;
 *
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
 * IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
 * CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
 * WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
 * ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
 * OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
 *
 * ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
 * COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
 * SOFTWARE IS DISCLAIMED.
 */
#include "ecdh_helper.h"

#include <linux/scatterlist.h>
#include <crypto/ecdh.h>

struct ecdh_completion {
	struct completion completion;
	int err;
};

static void ecdh_complete(struct crypto_async_request *req, int err)
{
	struct ecdh_completion *res = req->data;

	if (err == -EINPROGRESS)
		return;

	res->err = err;
	complete(&res->completion);
}

static inline void swap_digits(u64 *in, u64 *out, unsigned int ndigits)
{
	int i;

	for (i = 0; i < ndigits; i++)
		out[i] = __swab64(in[ndigits - 1 - i]);
}

/* compute_ecdh_secret() - function assumes that the private key was
 *                         already set.
 * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
 * @public_key:   pair's ecc public key.
 * secret:        memory where the ecdh computed shared secret will be saved.
 *
 * Return: zero on success; error code in case of error.
 */
int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64],
			u8 secret[32])
{
	struct kpp_request *req;
	u8 *tmp;
	struct ecdh_completion result;
	struct scatterlist src, dst;
	int err;

	tmp = kmalloc(64, GFP_KERNEL);
	if (!tmp)
		return -ENOMEM;

	req = kpp_request_alloc(tfm, GFP_KERNEL);
	if (!req) {
		err = -ENOMEM;
		goto free_tmp;
	}

	init_completion(&result.completion);

	swap_digits((u64 *)public_key, (u64 *)tmp, 4); /* x */
	swap_digits((u64 *)&public_key[32], (u64 *)&tmp[32], 4); /* y */

	sg_init_one(&src, tmp, 64);
	sg_init_one(&dst, secret, 32);
	kpp_request_set_input(req, &src, 64);
	kpp_request_set_output(req, &dst, 32);
	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
				 ecdh_complete, &result);
	err = crypto_kpp_compute_shared_secret(req);
	if (err == -EINPROGRESS) {
		wait_for_completion(&result.completion);
		err = result.err;
	}
	if (err < 0) {
		pr_err("alg: ecdh: compute shared secret failed. err %d\n",
		       err);
		goto free_all;
	}

	swap_digits((u64 *)secret, (u64 *)tmp, 4);
	memcpy(secret, tmp, 32);

free_all:
	kpp_request_free(req);
free_tmp:
	kfree_sensitive(tmp);
	return err;
}

/* set_ecdh_privkey() - set or generate ecc private key.
 *
 * Function generates an ecc private key in the crypto subsystem when receiving
 * a NULL private key or sets the received key when not NULL.
 *
 * @tfm:           KPP tfm handle allocated with crypto_alloc_kpp().
 * @private_key:   user's ecc private key. When not NULL, the key is expected
 *                 in little endian format.
 *
 * Return: zero on success; error code in case of error.
 */
int set_ecdh_privkey(struct crypto_kpp *tfm, const u8 private_key[32])
{
	u8 *buf, *tmp = NULL;
	unsigned int buf_len;
	int err;
	struct ecdh p = {0};

	if (private_key) {
		tmp = kmalloc(32, GFP_KERNEL);
		if (!tmp)
			return -ENOMEM;
		swap_digits((u64 *)private_key, (u64 *)tmp, 4);
		p.key = tmp;
		p.key_size = 32;
	}

	buf_len = crypto_ecdh_key_len(&p);
	buf = kmalloc(buf_len, GFP_KERNEL);
	if (!buf) {
		err = -ENOMEM;
		goto free_tmp;
	}

	err = crypto_ecdh_encode_key(buf, buf_len, &p);
	if (err)
		goto free_all;

	err = crypto_kpp_set_secret(tfm, buf, buf_len);
	/* fall through */
free_all:
	kfree_sensitive(buf);
free_tmp:
	kfree_sensitive(tmp);
	return err;
}

/* generate_ecdh_public_key() - function assumes that the private key was
 *                              already set.
 *
 * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
 * @public_key:   memory where the computed ecc public key will be saved.
 *
 * Return: zero on success; error code in case of error.
 */
int generate_ecdh_public_key(struct crypto_kpp *tfm, u8 public_key[64])
{
	struct kpp_request *req;
	u8 *tmp;
	struct ecdh_completion result;
	struct scatterlist dst;
	int err;

	tmp = kmalloc(64, GFP_KERNEL);
	if (!tmp)
		return -ENOMEM;

	req = kpp_request_alloc(tfm, GFP_KERNEL);
	if (!req) {
		err = -ENOMEM;
		goto free_tmp;
	}

	init_completion(&result.completion);
	sg_init_one(&dst, tmp, 64);
	kpp_request_set_input(req, NULL, 0);
	kpp_request_set_output(req, &dst, 64);
	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
				 ecdh_complete, &result);

	err = crypto_kpp_generate_public_key(req);
	if (err == -EINPROGRESS) {
		wait_for_completion(&result.completion);
		err = result.err;
	}
	if (err < 0)
		goto free_all;

	/* The public key is handed back in little endian as expected by
	 * the Security Manager Protocol.
	 */
	swap_digits((u64 *)tmp, (u64 *)public_key, 4); /* x */
	swap_digits((u64 *)&tmp[32], (u64 *)&public_key[32], 4); /* y */

free_all:
	kpp_request_free(req);
free_tmp:
	kfree(tmp);
	return err;
}

/* generate_ecdh_keys() - generate ecc key pair.
 *
 * @tfm:          KPP tfm handle allocated with crypto_alloc_kpp().
 * @public_key:   memory where the computed ecc public key will be saved.
 *
 * Return: zero on success; error code in case of error.
 */
int generate_ecdh_keys(struct crypto_kpp *tfm, u8 public_key[64])
{
	int err;

	err = set_ecdh_privkey(tfm, NULL);
	if (err)
		return err;

	return generate_ecdh_public_key(tfm, public_key);
}
Commit	Line	Data
58771c1c SB	1	/*
	2	* ECDH helper functions - KPP wrappings
	3	*
	4	* Copyright (C) 2017 Intel Corporation
	5	*
	6	* This program is free software; you can redistribute it and/or modify
	7	* it under the terms of the GNU General Public License version 2 as
	8	* published by the Free Software Foundation;
	9	*
	10	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
	11	* OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
	12	* FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT OF THIRD PARTY RIGHTS.
	13	* IN NO EVENT SHALL THE COPYRIGHT HOLDER(S) AND AUTHOR(S) BE LIABLE FOR ANY
	14	* CLAIM, OR ANY SPECIAL INDIRECT OR CONSEQUENTIAL DAMAGES, OR ANY DAMAGES
	15	* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
	16	* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
	17	* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
	18	*
	19	* ALL LIABILITY, INCLUDING LIABILITY FOR INFRINGEMENT OF ANY PATENTS,
	20	* COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS, RELATING TO USE OF THIS
	21	* SOFTWARE IS DISCLAIMED.
	22	*/
	23	#include "ecdh_helper.h"
	24
58771c1c	25	#include <linux/scatterlist.h>
58771c1c SB	26	#include <crypto/ecdh.h>
	27
	28	struct ecdh_completion {
	29	struct completion completion;
	30	int err;
	31	};
	32
	33	static void ecdh_complete(struct crypto_async_request *req, int err)
	34	{
	35	struct ecdh_completion *res = req->data;
	36
	37	if (err == -EINPROGRESS)
	38	return;
	39
	40	res->err = err;
	41	complete(&res->completion);
	42	}
	43
	44	static inline void swap_digits(u64 in, u64 out, unsigned int ndigits)
	45	{
	46	int i;
	47
	48	for (i = 0; i < ndigits; i++)
	49	out[i] = __swab64(in[ndigits - 1 - i]);
	50	}
	51
c0153b0b TA	52	/* compute_ecdh_secret() - function assumes that the private key was
	53	* already set.
	54	* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
	55	* @public_key: pair's ecc public key.
	56	* secret: memory where the ecdh computed shared secret will be saved.
	57	*
	58	* Return: zero on success; error code in case of error.
	59	*/
a2976416	60	int compute_ecdh_secret(struct crypto_kpp *tfm, const u8 public_key[64],
c0153b0b	61	u8 secret[32])
58771c1c	62	{
58771c1c	63	struct kpp_request *req;
c0153b0b	64	u8 *tmp;
58771c1c SB	65	struct ecdh_completion result;
58771c1c SB	66	struct scatterlist src, dst;
a2976416	67	int err;
58771c1c	68
763d9a30 SB	69	tmp = kmalloc(64, GFP_KERNEL);
763d9a30 SB	70	if (!tmp)
a2976416	71	return -ENOMEM;
763d9a30	72
58771c1c	73	req = kpp_request_alloc(tfm, GFP_KERNEL);
a2976416 TA	74	if (!req) {
a2976416 TA	75	err = -ENOMEM;
47eb2ac8	76	goto free_tmp;
a2976416	77	}
58771c1c SB	78
	79	init_completion(&result.completion);
	80
58771c1c SB	81	swap_digits((u64 )public_key, (u64 )tmp, 4); /* x */
	82	swap_digits((u64 )&public_key[32], (u64 )&tmp[32], 4); /* y */
	83
	84	sg_init_one(&src, tmp, 64);
	85	sg_init_one(&dst, secret, 32);
	86	kpp_request_set_input(req, &src, 64);
	87	kpp_request_set_output(req, &dst, 32);
	88	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
	89	ecdh_complete, &result);
	90	err = crypto_kpp_compute_shared_secret(req);
	91	if (err == -EINPROGRESS) {
	92	wait_for_completion(&result.completion);
	93	err = result.err;
	94	}
	95	if (err < 0) {
	96	pr_err("alg: ecdh: compute shared secret failed. err %d\n",
	97	err);
	98	goto free_all;
	99	}
	100
	101	swap_digits((u64 )secret, (u64 )tmp, 4);
	102	memcpy(secret, tmp, 32);
	103
	104	free_all:
58771c1c	105	kpp_request_free(req);
763d9a30	106	free_tmp:
453431a5	107	kfree_sensitive(tmp);
a2976416	108	return err;
58771c1c SB	109	}
58771c1c SB	110
c0153b0b TA	111	/* set_ecdh_privkey() - set or generate ecc private key.
	112	*
	113	* Function generates an ecc private key in the crypto subsystem when receiving
	114	* a NULL private key or sets the received key when not NULL.
	115	*
	116	* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
	117	* @private_key: user's ecc private key. When not NULL, the key is expected
	118	* in little endian format.
	119	*
	120	* Return: zero on success; error code in case of error.
	121	*/
	122	int set_ecdh_privkey(struct crypto_kpp *tfm, const u8 private_key[32])
	123	{
	124	u8 buf, tmp = NULL;
	125	unsigned int buf_len;
	126	int err;
	127	struct ecdh p = {0};
	128
c0153b0b TA	129	if (private_key) {
	130	tmp = kmalloc(32, GFP_KERNEL);
	131	if (!tmp)
	132	return -ENOMEM;
	133	swap_digits((u64 )private_key, (u64 )tmp, 4);
	134	p.key = tmp;
	135	p.key_size = 32;
	136	}
	137
	138	buf_len = crypto_ecdh_key_len(&p);
	139	buf = kmalloc(buf_len, GFP_KERNEL);
	140	if (!buf) {
	141	err = -ENOMEM;
	142	goto free_tmp;
	143	}
	144
	145	err = crypto_ecdh_encode_key(buf, buf_len, &p);
	146	if (err)
	147	goto free_all;
	148
	149	err = crypto_kpp_set_secret(tfm, buf, buf_len);
	150	/* fall through */
	151	free_all:
453431a5	152	kfree_sensitive(buf);
c0153b0b	153	free_tmp:
453431a5	154	kfree_sensitive(tmp);
c0153b0b TA	155	return err;
	156	}
	157
	158	/* generate_ecdh_public_key() - function assumes that the private key was
	159	* already set.
	160	*
	161	* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
	162	* @public_key: memory where the computed ecc public key will be saved.
	163	*
	164	* Return: zero on success; error code in case of error.
	165	*/
	166	int generate_ecdh_public_key(struct crypto_kpp *tfm, u8 public_key[64])
58771c1c	167	{
58771c1c	168	struct kpp_request *req;
c0153b0b	169	u8 *tmp;
58771c1c SB	170	struct ecdh_completion result;
58771c1c SB	171	struct scatterlist dst;
a2976416	172	int err;
58771c1c	173
763d9a30 SB	174	tmp = kmalloc(64, GFP_KERNEL);
763d9a30 SB	175	if (!tmp)
a2976416	176	return -ENOMEM;
763d9a30	177
58771c1c	178	req = kpp_request_alloc(tfm, GFP_KERNEL);
a2976416 TA	179	if (!req) {
a2976416 TA	180	err = -ENOMEM;
47eb2ac8	181	goto free_tmp;
a2976416	182	}
58771c1c SB	183
58771c1c SB	184	init_completion(&result.completion);
c0153b0b TA	185	sg_init_one(&dst, tmp, 64);
	186	kpp_request_set_input(req, NULL, 0);
	187	kpp_request_set_output(req, &dst, 64);
	188	kpp_request_set_callback(req, CRYPTO_TFM_REQ_MAY_BACKLOG,
	189	ecdh_complete, &result);
58771c1c	190
c0153b0b TA	191	err = crypto_kpp_generate_public_key(req);
	192	if (err == -EINPROGRESS) {
	193	wait_for_completion(&result.completion);
	194	err = result.err;
	195	}
	196	if (err < 0)
	197	goto free_all;
	198
	199	/* The public key is handed back in little endian as expected by
	200	* the Security Manager Protocol.
58771c1c SB	201	*/
	202	swap_digits((u64 )tmp, (u64 )public_key, 4); /* x */
	203	swap_digits((u64 )&tmp[32], (u64 )&public_key[32], 4); /* y */
58771c1c SB	204
58771c1c SB	205	free_all:
58771c1c	206	kpp_request_free(req);
763d9a30 SB	207	free_tmp:
763d9a30 SB	208	kfree(tmp);
a2976416	209	return err;
58771c1c	210	}
c0153b0b TA	211
	212	/* generate_ecdh_keys() - generate ecc key pair.
	213	*
	214	* @tfm: KPP tfm handle allocated with crypto_alloc_kpp().
	215	* @public_key: memory where the computed ecc public key will be saved.
	216	*
	217	* Return: zero on success; error code in case of error.
	218	*/
	219	int generate_ecdh_keys(struct crypto_kpp *tfm, u8 public_key[64])
	220	{
	221	int err;
	222
	223	err = set_ecdh_privkey(tfm, NULL);
	224	if (err)
	225	return err;
	226
	227	return generate_ecdh_public_key(tfm, public_key);
	228	}