crypto/rsa_helper.c

   1 /*
   2  * RSA key extract helper
   3  *
   4  * Copyright (c) 2015, Intel Corporation
   5  * Authors: Tadeusz Struk <tadeusz.struk@intel.com>
   6  *
   7  * This program is free software; you can redistribute it and/or modify it
   8  * under the terms of the GNU General Public License as published by the Free
   9  * Software Foundation; either version 2 of the License, or (at your option)
  10  * any later version.
  11  *
  12  */
  13 #include <linux/kernel.h>
  14 #include <linux/export.h>
  15 #include <linux/err.h>
  16 #include <linux/fips.h>
  17 #include <crypto/internal/rsa.h>
  18 #include "rsakey-asn1.h"
  19
  20 int rsa_get_n(void *context, size_t hdrlen, unsigned char tag,
  21               const void *value, size_t vlen)
  22 {
  23         struct rsa_key *key = context;
  24
  25         key->n = mpi_read_raw_data(value, vlen);
  26
  27         if (!key->n)
  28                 return -ENOMEM;
  29
  30         /* In FIPS mode only allow key size 2K & 3K */
  31         if (fips_enabled && (mpi_get_size(key->n) != 256 &&
  32                              mpi_get_size(key->n) != 384)) {
  33                 pr_err("RSA: key size not allowed in FIPS mode\n");
  34                 mpi_free(key->n);
  35                 key->n = NULL;
  36                 return -EINVAL;
  37         }
  38         return 0;
  39 }
  40
  41 int rsa_get_e(void *context, size_t hdrlen, unsigned char tag,
  42               const void *value, size_t vlen)
  43 {
  44         struct rsa_key *key = context;
  45
  46         key->e = mpi_read_raw_data(value, vlen);
  47
  48         if (!key->e)
  49                 return -ENOMEM;
  50
  51         return 0;
  52 }
  53
  54 int rsa_get_d(void *context, size_t hdrlen, unsigned char tag,
  55               const void *value, size_t vlen)
  56 {
  57         struct rsa_key *key = context;
  58
  59         key->d = mpi_read_raw_data(value, vlen);
  60
  61         if (!key->d)
  62                 return -ENOMEM;
  63
  64         /* In FIPS mode only allow key size 2K & 3K */
  65         if (fips_enabled && (mpi_get_size(key->d) != 256 &&
  66                              mpi_get_size(key->d) != 384)) {
  67                 pr_err("RSA: key size not allowed in FIPS mode\n");
  68                 mpi_free(key->d);
  69                 key->d = NULL;
  70                 return -EINVAL;
  71         }
  72         return 0;
  73 }
  74
  75 static void free_mpis(struct rsa_key *key)
  76 {
  77         mpi_free(key->n);
  78         mpi_free(key->e);
  79         mpi_free(key->d);
  80         key->n = NULL;
  81         key->e = NULL;
  82         key->d = NULL;
  83 }
  84
  85 /**
  86  * rsa_free_key() - frees rsa key allocated by rsa_parse_key()
  87  *
  88  * @rsa_key:    struct rsa_key key representation
  89  */
  90 void rsa_free_key(struct rsa_key *key)
  91 {
  92         free_mpis(key);
  93 }
  94 EXPORT_SYMBOL_GPL(rsa_free_key);
  95
  96 /**
  97  * rsa_parse_key() - extracts an rsa key from BER encoded buffer
  98  *                   and stores it in the provided struct rsa_key
  99  *
 100  * @rsa_key:    struct rsa_key key representation
 101  * @key:        key in BER format
 102  * @key_len:    length of key
 103  *
 104  * Return:      0 on success or error code in case of error
 105  */
 106 int rsa_parse_key(struct rsa_key *rsa_key, const void *key,
 107                   unsigned int key_len)
 108 {
 109         int ret;
 110
 111         free_mpis(rsa_key);
 112         ret = asn1_ber_decoder(&rsakey_decoder, rsa_key, key, key_len);
 113         if (ret < 0)
 114                 goto error;
 115
 116         return 0;
 117 error:
 118         free_mpis(rsa_key);
 119         return ret;
 120 }
 121 EXPORT_SYMBOL_GPL(rsa_parse_key);