1// SPDX-License-Identifier: GPL-2.0-or-later
  2/* ECDH key-agreement protocol
  3 *
  4 * Copyright (c) 2016, Intel Corporation
  5 * Authors: Salvator Benedetto <salvatore.benedetto@intel.com>
 
 
 
 
 
  6 */
  7
  8#include <linux/module.h>
  9#include <crypto/internal/ecc.h>
 10#include <crypto/internal/kpp.h>
 11#include <crypto/kpp.h>
 12#include <crypto/ecdh.h>
 13#include <linux/scatterlist.h>
 
 14
 15struct ecdh_ctx {
 16	unsigned int curve_id;
 17	unsigned int ndigits;
 18	u64 private_key[ECC_MAX_DIGITS];
 19};
 20
 21static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
 22{
 23	return kpp_tfm_ctx(tfm);
 24}
 25
 
 
 
 
 
 
 
 
 
 26static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 27			   unsigned int len)
 28{
 29	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
 30	struct ecdh params;
 
 
 
 
 31
 32	if (crypto_ecdh_decode_key(buf, len, &params) < 0 ||
 33	    params.key_size > sizeof(u64) * ctx->ndigits)
 34		return -EINVAL;
 35
 
 
 
 36	if (!params.key || !params.key_size)
 37		return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
 38				       ctx->private_key);
 39
 40	memcpy(ctx->private_key, params.key, params.key_size);
 41
 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	}
 
 
 47	return 0;
 48}
 49
 50static int ecdh_compute_value(struct kpp_request *req)
 51{
 52	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
 53	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
 54	u64 *public_key;
 55	u64 *shared_secret = NULL;
 56	void *buf;
 57	size_t copied, nbytes, public_key_sz;
 58	int ret = -ENOMEM;
 59
 60	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
 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;
 67
 68	if (req->src) {
 69		shared_secret = kmalloc(nbytes, GFP_KERNEL);
 70		if (!shared_secret)
 71			goto free_pubkey;
 72
 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)
 85			goto free_all;
 86
 87		ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
 88						ctx->private_key, public_key,
 89						shared_secret);
 90
 91		buf = shared_secret;
 92	} else {
 93		ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
 94				       ctx->private_key, public_key);
 95		buf = public_key;
 96		nbytes = public_key_sz;
 97	}
 98
 99	if (ret < 0)
100		goto free_all;
101
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);
107	if (copied != nbytes)
108		ret = -EINVAL;
109
110	/* fall through */
111free_all:
112	kfree_sensitive(shared_secret);
113free_pubkey:
114	kfree(public_key);
115	return ret;
116}
117
118static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
119{
120	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
121
122	/* Public key is made of two coordinates, add one to the left shift */
123	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
124}
125
126static 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
136static struct kpp_alg ecdh_nist_p192 = {
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,
141	.init = ecdh_nist_p192_init_tfm,
142	.base = {
143		.cra_name = "ecdh-nist-p192",
144		.cra_driver_name = "ecdh-nist-p192-generic",
145		.cra_priority = 100,
146		.cra_module = THIS_MODULE,
147		.cra_ctxsize = sizeof(struct ecdh_ctx),
148	},
149};
150
151static 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
161static 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",
169		.cra_driver_name = "ecdh-nist-p256-generic",
170		.cra_priority = 100,
171		.cra_module = THIS_MODULE,
172		.cra_ctxsize = sizeof(struct ecdh_ctx),
173	},
174};
175
176static 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
186static 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
201static bool ecdh_nist_p192_registered;
202
203static int __init ecdh_init(void)
204{
205	int ret;
206
207	/* NIST p192 will fail to register in FIPS mode */
208	ret = crypto_register_kpp(&ecdh_nist_p192);
209	ecdh_nist_p192_registered = ret == 0;
210
211	ret = crypto_register_kpp(&ecdh_nist_p256);
212	if (ret)
213		goto nist_p256_error;
214
215	ret = crypto_register_kpp(&ecdh_nist_p384);
216	if (ret)
217		goto nist_p384_error;
218
219	return 0;
220
221nist_p384_error:
222	crypto_unregister_kpp(&ecdh_nist_p256);
223
224nist_p256_error:
225	if (ecdh_nist_p192_registered)
226		crypto_unregister_kpp(&ecdh_nist_p192);
227	return ret;
228}
229
230static void __exit ecdh_exit(void)
231{
232	if (ecdh_nist_p192_registered)
233		crypto_unregister_kpp(&ecdh_nist_p192);
234	crypto_unregister_kpp(&ecdh_nist_p256);
235	crypto_unregister_kpp(&ecdh_nist_p384);
236}
237
238subsys_initcall(ecdh_init);
239module_exit(ecdh_exit);
240MODULE_ALIAS_CRYPTO("ecdh");
241MODULE_LICENSE("GPL");
242MODULE_DESCRIPTION("ECDH generic algorithm");

 
  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
  7 * modify it under the terms of the GNU General Public License
  8 * as published by the Free Software Foundation; either version
  9 * 2 of the License, or (at your option) any later version.
 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
 19struct ecdh_ctx {
 20	unsigned int curve_id;
 21	unsigned int ndigits;
 22	u64 private_key[ECC_MAX_DIGITS];
 23};
 24
 25static inline struct ecdh_ctx *ecdh_get_ctx(struct crypto_kpp *tfm)
 26{
 27	return kpp_tfm_ctx(tfm);
 28}
 29
 30static unsigned int ecdh_supported_curve(unsigned int curve_id)
 31{
 32	switch (curve_id) {
 33	case ECC_CURVE_NIST_P192: return 3;
 34	case ECC_CURVE_NIST_P256: return 4;
 35	default: return 0;
 36	}
 37}
 38
 39static int ecdh_set_secret(struct crypto_kpp *tfm, const void *buf,
 40			   unsigned int len)
 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
 56	if (!params.key || !params.key_size)
 57		return ecc_gen_privkey(ctx->curve_id, ctx->ndigits,
 58				       ctx->private_key);
 59
 
 
 60	if (ecc_is_key_valid(ctx->curve_id, ctx->ndigits,
 61			     (const u64 *)params.key, params.key_size) < 0)
 
 62		return -EINVAL;
 63
 64	memcpy(ctx->private_key, params.key, params.key_size);
 65
 66	return 0;
 67}
 68
 69static int ecdh_compute_value(struct kpp_request *req)
 70{
 71	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
 72	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
 73	u64 *public_key;
 74	u64 *shared_secret = NULL;
 75	void *buf;
 76	size_t copied, nbytes, public_key_sz;
 77	int ret = -ENOMEM;
 78
 79	nbytes = ctx->ndigits << ECC_DIGITS_TO_BYTES_SHIFT;
 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;
 86
 87	if (req->src) {
 88		shared_secret = kmalloc(nbytes, GFP_KERNEL);
 89		if (!shared_secret)
 90			goto free_pubkey;
 91
 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)
104			goto free_all;
105
106		ret = crypto_ecdh_shared_secret(ctx->curve_id, ctx->ndigits,
107						ctx->private_key, public_key,
108						shared_secret);
109
110		buf = shared_secret;
111	} else {
112		ret = ecc_make_pub_key(ctx->curve_id, ctx->ndigits,
113				       ctx->private_key, public_key);
114		buf = public_key;
115		nbytes = public_key_sz;
116	}
117
118	if (ret < 0)
119		goto free_all;
120
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);
126	if (copied != nbytes)
127		ret = -EINVAL;
128
129	/* fall through */
130free_all:
131	kzfree(shared_secret);
132free_pubkey:
133	kfree(public_key);
134	return ret;
135}
136
137static unsigned int ecdh_max_size(struct crypto_kpp *tfm)
138{
139	struct ecdh_ctx *ctx = ecdh_get_ctx(tfm);
140
141	/* Public key is made of two coordinates, add one to the left shift */
142	return ctx->ndigits << (ECC_DIGITS_TO_BYTES_SHIFT + 1);
143}
144
145static 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,
 
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
159static int ecdh_init(void)
160{
161	return crypto_register_kpp(&ecdh);
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
162}
163
164static void ecdh_exit(void)
165{
166	crypto_unregister_kpp(&ecdh);
 
 
 
167}
168
169module_init(ecdh_init);
170module_exit(ecdh_exit);
171MODULE_ALIAS_CRYPTO("ecdh");
172MODULE_LICENSE("GPL");
173MODULE_DESCRIPTION("ECDH generic algorithm");