crypto/rsa_helper.c

/*
 * RSA key extract helper
 *
 * Copyright (c) 2015, Intel Corporation
 * Authors: Tadeusz Struk <tadeusz.struk@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/kernel.h>
#include <linux/export.h>
#include <linux/err.h>
#include <linux/fips.h>
#include <crypto/internal/rsa.h>
#include "rsapubkey-asn1.h"
#include "rsaprivkey-asn1.h"

int rsa_get_n(void *context, size_t hdrlen, unsigned char tag,
	      const void *value, size_t vlen)
{
	struct rsa_key *key = context;
	const u8 *ptr = value;
	size_t n_sz = vlen;

	/* invalid key provided */
	if (!value || !vlen)
		return -EINVAL;

	if (fips_enabled) {
		while (!*ptr && n_sz) {
			ptr++;
			n_sz--;
		}

		/* In FIPS mode only allow key size 2K & 3K */
		if (n_sz != 256 && n_sz != 384) {
			pr_err("RSA: key size not allowed in FIPS mode\n");
			return -EINVAL;
		}
	}

	key->n = value;
	key->n_sz = vlen;

	return 0;
}

int rsa_get_e(void *context, size_t hdrlen, unsigned char tag,
	      const void *value, size_t vlen)
{
	struct rsa_key *key = context;

	/* invalid key provided */
	if (!value || !key->n_sz || !vlen || vlen > key->n_sz)
		return -EINVAL;

	key->e = value;
	key->e_sz = vlen;

	return 0;
}

int rsa_get_d(void *context, size_t hdrlen, unsigned char tag,
	      const void *value, size_t vlen)
{
	struct rsa_key *key = context;

	/* invalid key provided */
	if (!value || !key->n_sz || !vlen || vlen > key->n_sz)
		return -EINVAL;

	key->d = value;
	key->d_sz = vlen;

	return 0;
}

/**
 * rsa_parse_pub_key() - decodes the BER encoded buffer and stores in the
 *                       provided struct rsa_key, pointers to the raw key as is,
 *                       so that the caller can copy it or MPI parse it, etc.
 *
 * @rsa_key:	struct rsa_key key representation
 * @key:	key in BER format
 * @key_len:	length of key
 *
 * Return:	0 on success or error code in case of error
 */
int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
		      unsigned int key_len)
{
	return asn1_ber_decoder(&rsapubkey_decoder, rsa_key, key, key_len);
}
EXPORT_SYMBOL_GPL(rsa_parse_pub_key);

/**
 * rsa_parse_priv_key() - decodes the BER encoded buffer and stores in the
 *                        provided struct rsa_key, pointers to the raw key
 *                        as is, so that the caller can copy it or MPI parse it,
 *                        etc.
 *
 * @rsa_key:	struct rsa_key key representation
 * @key:	key in BER format
 * @key_len:	length of key
 *
 * Return:	0 on success or error code in case of error
 */
int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
		       unsigned int key_len)
{
	return asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len);
}
EXPORT_SYMBOL_GPL(rsa_parse_priv_key);