[people/arne_f/kernel.git] / crypto / dh.c

/*  Diffie-Hellman Key Agreement Method [RFC2631]
 *
 * Copyright (c) 2016, Intel Corporation
 * Authors: Salvatore 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/dh.h>
#include <linux/mpi.h>

struct dh_ctx {
	MPI p;
	MPI g;
	MPI xa;
};

static inline void dh_clear_params(struct dh_ctx *ctx)
{
	mpi_free(ctx->p);
	mpi_free(ctx->g);
	ctx->p = NULL;
	ctx->g = NULL;
}

static void dh_free_ctx(struct dh_ctx *ctx)
{
	dh_clear_params(ctx);
	mpi_free(ctx->xa);
	ctx->xa = NULL;
}

/*
 * If base is g we compute the public key
 *	ya = g^xa mod p; [RFC2631 sec 2.1.1]
 * else if base if the counterpart public key we compute the shared secret
 *	ZZ = yb^xa mod p; [RFC2631 sec 2.1.1]
 */
static int _compute_val(const struct dh_ctx *ctx, MPI base, MPI val)
{
	/* val = base^xa mod p */
	return mpi_powm(val, base, ctx->xa, ctx->p);
}

static inline struct dh_ctx *dh_get_ctx(struct crypto_kpp *tfm)
{
	return kpp_tfm_ctx(tfm);
}

static int dh_check_params_length(unsigned int p_len)
{
	return (p_len < 1536) ? -EINVAL : 0;
}

static int dh_set_params(struct dh_ctx *ctx, struct dh *params)
{
	if (unlikely(!params->p || !params->g))
		return -EINVAL;

	if (dh_check_params_length(params->p_size << 3))
		return -EINVAL;

	ctx->p = mpi_read_raw_data(params->p, params->p_size);
	if (!ctx->p)
		return -EINVAL;

	ctx->g = mpi_read_raw_data(params->g, params->g_size);
	if (!ctx->g) {
		mpi_free(ctx->p);
		return -EINVAL;
	}

	return 0;
}

static int dh_set_secret(struct crypto_kpp *tfm, const void *buf,
			 unsigned int len)
{
	struct dh_ctx *ctx = dh_get_ctx(tfm);
	struct dh params;

	/* Free the old MPI key if any */
	dh_free_ctx(ctx);

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

	if (dh_set_params(ctx, &params) < 0)
		return -EINVAL;

	ctx->xa = mpi_read_raw_data(params.key, params.key_size);
	if (!ctx->xa) {
		dh_clear_params(ctx);
		return -EINVAL;
	}

	return 0;
}

static int dh_compute_value(struct kpp_request *req)
{
	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
	struct dh_ctx *ctx = dh_get_ctx(tfm);
	MPI base, val = mpi_alloc(0);
	int ret = 0;
	int sign;

	if (!val)
		return -ENOMEM;

	if (unlikely(!ctx->xa)) {
		ret = -EINVAL;
		goto err_free_val;
	}

	if (req->src) {
		base = mpi_read_raw_from_sgl(req->src, req->src_len);
		if (!base) {
			ret = -EINVAL;
			goto err_free_val;
		}
	} else {
		base = ctx->g;
	}

	ret = _compute_val(ctx, base, val);
	if (ret)
		goto err_free_base;

	ret = mpi_write_to_sgl(val, req->dst, req->dst_len, &sign);
	if (ret)
		goto err_free_base;

	if (sign < 0)
		ret = -EBADMSG;
err_free_base:
	if (req->src)
		mpi_free(base);
err_free_val:
	mpi_free(val);
	return ret;
}

static unsigned int dh_max_size(struct crypto_kpp *tfm)
{
	struct dh_ctx *ctx = dh_get_ctx(tfm);

	return mpi_get_size(ctx->p);
}

static void dh_exit_tfm(struct crypto_kpp *tfm)
{
	struct dh_ctx *ctx = dh_get_ctx(tfm);

	dh_free_ctx(ctx);
}

static struct kpp_alg dh = {
	.set_secret = dh_set_secret,
	.generate_public_key = dh_compute_value,
	.compute_shared_secret = dh_compute_value,
	.max_size = dh_max_size,
	.exit = dh_exit_tfm,
	.base = {
		.cra_name = "dh",
		.cra_driver_name = "dh-generic",
		.cra_priority = 100,
		.cra_module = THIS_MODULE,
		.cra_ctxsize = sizeof(struct dh_ctx),
	},
};

static int dh_init(void)
{
	return crypto_register_kpp(&dh);
}

static void dh_exit(void)
{
	crypto_unregister_kpp(&dh);
}

module_init(dh_init);
module_exit(dh_exit);
MODULE_ALIAS_CRYPTO("dh");
MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("DH generic algorithm");
Commit	Line	Data
802c7f1c SB	1	/* Diffie-Hellman Key Agreement Method [RFC2631]
	2	*
	3	* Copyright (c) 2016, Intel Corporation
	4	* Authors: Salvatore 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
802c7f1c	8	* as published by the Free Software Foundation; either version
c0ca1215	9	* 2 of the License, or (at your option) any later version.
802c7f1c SB	10	*/
	11
	12	#include <linux/module.h>
	13	#include <crypto/internal/kpp.h>
	14	#include <crypto/kpp.h>
	15	#include <crypto/dh.h>
	16	#include <linux/mpi.h>
	17
	18	struct dh_ctx {
	19	MPI p;
	20	MPI g;
	21	MPI xa;
	22	};
	23
	24	static inline void dh_clear_params(struct dh_ctx *ctx)
	25	{
	26	mpi_free(ctx->p);
	27	mpi_free(ctx->g);
	28	ctx->p = NULL;
	29	ctx->g = NULL;
	30	}
	31
	32	static void dh_free_ctx(struct dh_ctx *ctx)
	33	{
	34	dh_clear_params(ctx);
	35	mpi_free(ctx->xa);
	36	ctx->xa = NULL;
	37	}
	38
	39	/*
	40	* If base is g we compute the public key
	41	* ya = g^xa mod p; [RFC2631 sec 2.1.1]
	42	* else if base if the counterpart public key we compute the shared secret
	43	* ZZ = yb^xa mod p; [RFC2631 sec 2.1.1]
	44	*/
	45	static int _compute_val(const struct dh_ctx *ctx, MPI base, MPI val)
	46	{
	47	/* val = base^xa mod p */
	48	return mpi_powm(val, base, ctx->xa, ctx->p);
	49	}
	50
	51	static inline struct dh_ctx dh_get_ctx(struct crypto_kpp tfm)
	52	{
	53	return kpp_tfm_ctx(tfm);
	54	}
	55
	56	static int dh_check_params_length(unsigned int p_len)
	57	{
	58	return (p_len < 1536) ? -EINVAL : 0;
	59	}
	60
	61	static int dh_set_params(struct dh_ctx ctx, struct dh params)
	62	{
	63	if (unlikely(!params->p \|\| !params->g))
	64	return -EINVAL;
	65
	66	if (dh_check_params_length(params->p_size << 3))
	67	return -EINVAL;
	68
	69	ctx->p = mpi_read_raw_data(params->p, params->p_size);
	70	if (!ctx->p)
	71	return -EINVAL;
	72
	73	ctx->g = mpi_read_raw_data(params->g, params->g_size);
74	if (!ctx->g) {
75	mpi_free(ctx->p);
76	return -EINVAL;
77	}
78
79	return 0;
80	}
81
5527dfb6 EB	82	static int dh_set_secret(struct crypto_kpp tfm, const void buf,
5527dfb6 EB	83	unsigned int len)
802c7f1c SB	84	{
	85	struct dh_ctx *ctx = dh_get_ctx(tfm);
	86	struct dh params;
	87
ee34e264 TDA	88	/* Free the old MPI key if any */
	89	dh_free_ctx(ctx);
	90
802c7f1c SB	91	if (crypto_dh_decode_key(buf, len, &params) < 0)
	92	return -EINVAL;
	93
	94	if (dh_set_params(ctx, &params) < 0)
	95	return -EINVAL;
	96
	97	ctx->xa = mpi_read_raw_data(params.key, params.key_size);
	98	if (!ctx->xa) {
	99	dh_clear_params(ctx);
	100	return -EINVAL;
	101	}
	102
	103	return 0;
	104	}
	105
	106	static int dh_compute_value(struct kpp_request *req)
	107	{
	108	struct crypto_kpp *tfm = crypto_kpp_reqtfm(req);
	109	struct dh_ctx *ctx = dh_get_ctx(tfm);
	110	MPI base, val = mpi_alloc(0);
	111	int ret = 0;
	112	int sign;
	113
	114	if (!val)
	115	return -ENOMEM;
	116
	117	if (unlikely(!ctx->xa)) {
	118	ret = -EINVAL;
	119	goto err_free_val;
	120	}
	121
	122	if (req->src) {
	123	base = mpi_read_raw_from_sgl(req->src, req->src_len);
	124	if (!base) {
8edda7d2	125	ret = -EINVAL;
802c7f1c SB	126	goto err_free_val;
	127	}
	128	} else {
	129	base = ctx->g;
	130	}
	131
	132	ret = _compute_val(ctx, base, val);
	133	if (ret)
	134	goto err_free_base;
	135
9b45b7bb	136	ret = mpi_write_to_sgl(val, req->dst, req->dst_len, &sign);
802c7f1c SB	137	if (ret)
	138	goto err_free_base;
	139
	140	if (sign < 0)
	141	ret = -EBADMSG;
	142	err_free_base:
	143	if (req->src)
	144	mpi_free(base);
	145	err_free_val:
	146	mpi_free(val);
	147	return ret;
	148	}
	149
7f691050	150	static unsigned int dh_max_size(struct crypto_kpp *tfm)
802c7f1c SB	151	{
	152	struct dh_ctx *ctx = dh_get_ctx(tfm);
	153
	154	return mpi_get_size(ctx->p);
	155	}
	156
	157	static void dh_exit_tfm(struct crypto_kpp *tfm)
	158	{
	159	struct dh_ctx *ctx = dh_get_ctx(tfm);
	160
	161	dh_free_ctx(ctx);
	162	}
	163
	164	static struct kpp_alg dh = {
	165	.set_secret = dh_set_secret,
	166	.generate_public_key = dh_compute_value,
	167	.compute_shared_secret = dh_compute_value,
	168	.max_size = dh_max_size,
	169	.exit = dh_exit_tfm,
	170	.base = {
	171	.cra_name = "dh",
	172	.cra_driver_name = "dh-generic",
	173	.cra_priority = 100,
	174	.cra_module = THIS_MODULE,
	175	.cra_ctxsize = sizeof(struct dh_ctx),
	176	},
	177	};
	178
	179	static int dh_init(void)
	180	{
	181	return crypto_register_kpp(&dh);
	182	}
	183
	184	static void dh_exit(void)
	185	{
	186	crypto_unregister_kpp(&dh);
	187	}
	188
	189	module_init(dh_init);
	190	module_exit(dh_exit);
	191	MODULE_ALIAS_CRYPTO("dh");
	192	MODULE_LICENSE("GPL");
	193	MODULE_DESCRIPTION("DH generic algorithm");