diff mbox

[v3] crypto: rsa - return raw integers for the ASN.1 parser

Message ID 1465309269-2214-1-git-send-email-tudor-dan.ambarus@nxp.com (mailing list archive)
State Changes Requested
Delegated to: Herbert Xu
Headers show

Commit Message

Tudor Ambarus June 7, 2016, 2:21 p.m. UTC 
Return the raw key with no other processing so that the caller
can copy it or MPI parse it, etc.

The scope is to have only one ANS.1 parser for all RSA
implementations.

Update the RSA software implementation so that it does
the MPI conversion on top.

Signed-off-by: Tudor Ambarus <tudor-dan.ambarus@nxp.com>
---
 crypto/rsa.c                  | 119 ++++++++++++++++++++++++++-------------
 crypto/rsa_helper.c           | 128 +++++++++++++++++++++---------------------
 include/crypto/internal/rsa.h |  22 ++++++--
 3 files changed, 161 insertions(+), 108 deletions(-)

Comments

Stephan Mueller June 7, 2016, 2:33 p.m. UTC | #1 
Am Dienstag, 7. Juni 2016, 17:21:09 schrieb Tudor Ambarus:

Hi Tudor,

> Return the raw key with no other processing so that the caller
> can copy it or MPI parse it, etc.
> 
> The scope is to have only one ANS.1 parser for all RSA
> implementations.
> 
> Update the RSA software implementation so that it does
> the MPI conversion on top.
> 
> Signed-off-by: Tudor Ambarus <tudor-dan.ambarus@nxp.com>
> ---
>  crypto/rsa.c                  | 119 ++++++++++++++++++++++++++-------------
> crypto/rsa_helper.c           | 128
> +++++++++++++++++++++--------------------- include/crypto/internal/rsa.h | 
> 22 ++++++--
>  3 files changed, 161 insertions(+), 108 deletions(-)
> 
> diff --git a/crypto/rsa.c b/crypto/rsa.c
> index 77d737f..ea78d61 100644
> --- a/crypto/rsa.c
> +++ b/crypto/rsa.c
> @@ -14,12 +14,24 @@
>  #include <crypto/internal/akcipher.h>
>  #include <crypto/akcipher.h>
>  #include <crypto/algapi.h>
> +#include <linux/mpi.h>
> +
> +struct rsa_mpi_key {
> +	MPI n;
> +	MPI e;
> +	MPI d;
> +};
> +
> +struct rsa_ctx {
> +	struct rsa_key key;
> +	struct rsa_mpi_key mpi_key;
> +};
> 
>  /*
>   * RSAEP function [RFC3447 sec 5.1.1]
>   * c = m^e mod n;
>   */
> -static int _rsa_enc(const struct rsa_key *key, MPI c, MPI m)
> +static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)
>  {
>  	/* (1) Validate 0 <= m < n */
>  	if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
> @@ -33,7 +45,7 @@ static int _rsa_enc(const struct rsa_key *key, MPI c, MPI
> m) * RSADP function [RFC3447 sec 5.1.2]
>   * m = c^d mod n;
>   */
> -static int _rsa_dec(const struct rsa_key *key, MPI m, MPI c)
> +static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c)
>  {
>  	/* (1) Validate 0 <= c < n */
>  	if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
> @@ -47,7 +59,7 @@ static int _rsa_dec(const struct rsa_key *key, MPI m, MPI
> c) * RSASP1 function [RFC3447 sec 5.2.1]
>   * s = m^d mod n
>   */
> -static int _rsa_sign(const struct rsa_key *key, MPI s, MPI m)
> +static int _rsa_sign(const struct rsa_mpi_key *key, MPI s, MPI m)
>  {
>  	/* (1) Validate 0 <= m < n */
>  	if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
> @@ -61,7 +73,7 @@ static int _rsa_sign(const struct rsa_key *key, MPI s, MPI
> m) * RSAVP1 function [RFC3447 sec 5.2.2]
>   * m = s^e mod n;
>   */
> -static int _rsa_verify(const struct rsa_key *key, MPI m, MPI s)
> +static int _rsa_verify(const struct rsa_mpi_key *key, MPI m, MPI s)
>  {
>  	/* (1) Validate 0 <= s < n */
>  	if (mpi_cmp_ui(s, 0) < 0 || mpi_cmp(s, key->n) >= 0)
> @@ -71,15 +83,17 @@ static int _rsa_verify(const struct rsa_key *key, MPI m,
> MPI s) return mpi_powm(m, s, key->e, key->n);
>  }
> 
> -static inline struct rsa_key *rsa_get_key(struct crypto_akcipher *tfm)
> +static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
>  {
> -	return akcipher_tfm_ctx(tfm);
> +	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> +
> +	return &ctx->mpi_key;
>  }
> 
>  static int rsa_enc(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
> -	const struct rsa_key *pkey = rsa_get_key(tfm);
> +	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
>  	MPI m, c = mpi_alloc(0);
>  	int ret = 0;
>  	int sign;
> @@ -118,7 +132,7 @@ err_free_c:
>  static int rsa_dec(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
> -	const struct rsa_key *pkey = rsa_get_key(tfm);
> +	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
>  	MPI c, m = mpi_alloc(0);
>  	int ret = 0;
>  	int sign;
> @@ -156,7 +170,7 @@ err_free_m:
>  static int rsa_sign(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
> -	const struct rsa_key *pkey = rsa_get_key(tfm);
> +	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
>  	MPI m, s = mpi_alloc(0);
>  	int ret = 0;
>  	int sign;
> @@ -195,7 +209,7 @@ err_free_s:
>  static int rsa_verify(struct akcipher_request *req)
>  {
>  	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
> -	const struct rsa_key *pkey = rsa_get_key(tfm);
> +	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
>  	MPI s, m = mpi_alloc(0);
>  	int ret = 0;
>  	int sign;
> @@ -233,67 +247,94 @@ err_free_m:
>  	return ret;
>  }
> 
> -static int rsa_check_key_length(unsigned int len)
> +static void rsa_free_mpi_key(struct rsa_mpi_key *key)
>  {
> -	switch (len) {
> -	case 512:
> -	case 1024:
> -	case 1536:
> -	case 2048:
> -	case 3072:
> -	case 4096:
> -		return 0;
> -	}
> -
> -	return -EINVAL;
> +	mpi_free(key->d);
> +	mpi_free(key->e);
> +	mpi_free(key->n);
> +	key->d = NULL;
> +	key->e = NULL;
> +	key->n = NULL;
>  }
> 
>  static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
>  			   unsigned int keylen)
>  {
> -	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
> +	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> +	struct rsa_key *pkey = &ctx->key;
> +	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
>  	int ret;
> 
> +	/* Free the old MPI key if any */
> +	rsa_free_mpi_key(mpi_key);
> +
>  	ret = rsa_parse_pub_key(pkey, key, keylen);
>  	if (ret)
>  		return ret;
> 
> -	if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
> -		rsa_free_key(pkey);
> -		ret = -EINVAL;
> -	}
> -	return ret;
> +	mpi_key->e = mpi_read_raw_data(pkey->e, pkey->e_sz);
> +	if (!mpi_key->e)
> +		goto err;
> +
> +	mpi_key->n = mpi_read_raw_data(pkey->n, pkey->n_sz);
> +	if (!mpi_key->n)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	rsa_free_mpi_key(mpi_key);
> +	return -ENOMEM;
>  }
> 
>  static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
>  			    unsigned int keylen)
>  {
> -	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
> +	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> +	struct rsa_key *pkey = &ctx->key;
> +	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
>  	int ret;
> 
> +	/* Free the old MPI key if any */
> +	rsa_free_mpi_key(mpi_key);
> +
>  	ret = rsa_parse_priv_key(pkey, key, keylen);
>  	if (ret)
>  		return ret;
> 
> -	if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
> -		rsa_free_key(pkey);
> -		ret = -EINVAL;
> -	}
> -	return ret;
> +	mpi_key->d = mpi_read_raw_data(pkey->d, pkey->n_sz);
> +	if (!mpi_key->d)
> +		goto err;
> +
> +	mpi_key->e = mpi_read_raw_data(pkey->e, pkey->e_sz);
> +	if (!mpi_key->e)
> +		goto err;
> +
> +	mpi_key->n = mpi_read_raw_data(pkey->n, pkey->n_sz);
> +	if (!mpi_key->n)
> +		goto err;
> +
> +	return 0;
> +
> +err:
> +	rsa_free_mpi_key(mpi_key);
> +	return -ENOMEM;
>  }
> 
>  static int rsa_max_size(struct crypto_akcipher *tfm)
>  {
> -	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
> +	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> +	struct rsa_key *pkey = &ctx->key;
> 
> -	return pkey->n ? mpi_get_size(pkey->n) : -EINVAL;
> +	return pkey->n ? pkey->n_sz : -EINVAL;
>  }
> 
>  static void rsa_exit_tfm(struct crypto_akcipher *tfm)
>  {
> -	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
> +	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
> +	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
> 
> -	rsa_free_key(pkey);
> +	rsa_free_mpi_key(mpi_key);
>  }
> 
>  static struct akcipher_alg rsa = {
> @@ -310,7 +351,7 @@ static struct akcipher_alg rsa = {
>  		.cra_driver_name = "rsa-generic",
>  		.cra_priority = 100,
>  		.cra_module = THIS_MODULE,
> -		.cra_ctxsize = sizeof(struct rsa_key),
> +		.cra_ctxsize = sizeof(struct rsa_ctx),
>  	},
>  };
> 
> diff --git a/crypto/rsa_helper.c b/crypto/rsa_helper.c
> index d226f48..f0677b7 100644
> --- a/crypto/rsa_helper.c
> +++ b/crypto/rsa_helper.c
> @@ -18,24 +18,50 @@
>  #include "rsapubkey-asn1.h"
>  #include "rsaprivkey-asn1.h"
> 
> +static int rsa_check_key_length(unsigned int len)
> +{
> +	switch (len) {
> +	case 512:
> +	case 1024:
> +	case 1536:
> +	case 2048:
> +	case 3072:
> +	case 4096:
> +		return 0;
> +	}
> +
> +	return -EINVAL;
> +}
> +
>  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;
> +	int ret;
> 
> -	key->n = mpi_read_raw_data(value, vlen);
> +	while (!*ptr && vlen) {
> +		ptr++;
> +		vlen--;
> +	}

As you do this operation 3 times, isn't an inline better here?

> 
> -	if (!key->n)
> -		return -ENOMEM;
> +	/* invalid key provided */
> +	if (!ptr)
> +		return -EINVAL;

Hm, you check the pointer here, but you dereference it already above. So, I 
guess you want to move that check to the beginning of the function?
> 
>  	/* In FIPS mode only allow key size 2K & 3K */
> -	if (fips_enabled && (mpi_get_size(key->n) != 256 &&
> -			     mpi_get_size(key->n) != 384)) {
> +	if (fips_enabled && (vlen != 256 && vlen != 384)) {
>  		pr_err("RSA: key size not allowed in FIPS mode\n");
> -		mpi_free(key->n);
> -		key->n = NULL;
>  		return -EINVAL;
>  	}
> +	/* invalid key size provided */
> +	ret = rsa_check_key_length(vlen << 3);
> +	if (ret)
> +		return ret;
> +
> +	key->n = ptr;
> +	key->n_sz = vlen;
> +
>  	return 0;
>  }
> 
> @@ -43,11 +69,19 @@ int rsa_get_e(void *context, size_t hdrlen, unsigned
> char tag, const void *value, size_t vlen)
>  {
>  	struct rsa_key *key = context;
> +	const u8 *ptr = value;
> +
> +	while (!*ptr && vlen) {
> +		ptr++;
> +		vlen--;
> +	}

No NULL check for ptr? Is it always guaranteed that there is no NULL 
considering that this may be exposed to user space?
> 
> -	key->e = mpi_read_raw_data(value, vlen);
> +	/* invalid key provided */
> +	if (!ptr || !key->n_sz || !vlen || vlen > key->n_sz)
> +		return -EINVAL;

Ah, here we have that check -- again, I would assume it should move up.
> 
> -	if (!key->e)
> -		return -ENOMEM;
> +	key->e = ptr;
> +	key->e_sz = vlen;
> 
>  	return 0;
>  }
> @@ -56,47 +90,33 @@ int rsa_get_d(void *context, size_t hdrlen, unsigned
> char tag, const void *value, size_t vlen)
>  {
>  	struct rsa_key *key = context;
> +	const u8 *ptr = value;
> 
> -	key->d = mpi_read_raw_data(value, vlen);
> +	while (!*ptr && vlen) {
> +		ptr++;
> +		vlen--;
> +	}

Same here.
> 
> -	if (!key->d)
> -		return -ENOMEM;
> +	/* invalid key provided */
> +	if (!ptr || !key->n_sz || !vlen || vlen > key->n_sz)
> +		return -EINVAL;
> 
>  	/* In FIPS mode only allow key size 2K & 3K */
> -	if (fips_enabled && (mpi_get_size(key->d) != 256 &&
> -			     mpi_get_size(key->d) != 384)) {
> +	if (fips_enabled && (vlen != 256 && vlen != 384)) {
>  		pr_err("RSA: key size not allowed in FIPS mode\n");
> -		mpi_free(key->d);
> -		key->d = NULL;
>  		return -EINVAL;
>  	}
> -	return 0;
> -}
> 
> -static void free_mpis(struct rsa_key *key)
> -{
> -	mpi_free(key->n);
> -	mpi_free(key->e);
> -	mpi_free(key->d);
> -	key->n = NULL;
> -	key->e = NULL;
> -	key->d = NULL;
> -}
> +	key->d = ptr;
> +	key->d_sz = vlen;
> 
> -/**
> - * rsa_free_key() - frees rsa key allocated by rsa_parse_key()
> - *
> - * @rsa_key:	struct rsa_key key representation
> - */
> -void rsa_free_key(struct rsa_key *key)
> -{
> -	free_mpis(key);
> +	return 0;
>  }
> -EXPORT_SYMBOL_GPL(rsa_free_key);
> 
>  /**
> - * rsa_parse_pub_key() - extracts an rsa public key from BER encoded buffer
> - *			 and stores it in the provided struct rsa_key
> + * 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
> @@ -107,23 +127,15 @@ EXPORT_SYMBOL_GPL(rsa_free_key);
>  int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
>  		      unsigned int key_len)
>  {
> -	int ret;
> -
> -	free_mpis(rsa_key);
> -	ret = asn1_ber_decoder(&rsapubkey_decoder, rsa_key, key, key_len);
> -	if (ret < 0)
> -		goto error;
> -
> -	return 0;
> -error:
> -	free_mpis(rsa_key);
> -	return ret;
> +	return asn1_ber_decoder(&rsapubkey_decoder, rsa_key, key, key_len);
>  }
>  EXPORT_SYMBOL_GPL(rsa_parse_pub_key);
> 
>  /**
> - * rsa_parse_pub_key() - extracts an rsa private key from BER encoded
> buffer - *			 and stores it in the provided struct rsa_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
> @@ -134,16 +146,6 @@ EXPORT_SYMBOL_GPL(rsa_parse_pub_key);
>  int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
>  		       unsigned int key_len)
>  {
> -	int ret;
> -
> -	free_mpis(rsa_key);
> -	ret = asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len);
> -	if (ret < 0)
> -		goto error;
> -
> -	return 0;
> -error:
> -	free_mpis(rsa_key);
> -	return ret;
> +	return asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len);
>  }
>  EXPORT_SYMBOL_GPL(rsa_parse_priv_key);
> diff --git a/include/crypto/internal/rsa.h b/include/crypto/internal/rsa.h
> index c7585bd..d6c042a 100644
> --- a/include/crypto/internal/rsa.h
> +++ b/include/crypto/internal/rsa.h
> @@ -12,12 +12,24 @@
>   */
>  #ifndef _RSA_HELPER_
>  #define _RSA_HELPER_
> -#include <linux/mpi.h>
> +#include <linux/types.h>
> 
> +/**
> + * rsa_key - RSA key structure
> + * @n           : RSA modulus raw byte stream
> + * @e           : RSA public exponent raw byte stream
> + * @d           : RSA private exponent raw byte stream
> + * @n_sz        : length in bytes of RSA modulus n
> + * @e_sz        : length in bytes of RSA public exponent
> + * @d_sz        : length in bytes of RSA private exponent
> + */
>  struct rsa_key {
> -	MPI n;
> -	MPI e;
> -	MPI d;
> +	const u8 *n;
> +	const u8 *e;
> +	const u8 *d;
> +	size_t n_sz;
> +	size_t e_sz;
> +	size_t d_sz;
>  };
> 
>  int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
> @@ -26,7 +38,5 @@ int rsa_parse_pub_key(struct rsa_key *rsa_key, const void
> *key, int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
>  		       unsigned int key_len);
> 
> -void rsa_free_key(struct rsa_key *rsa_key);
> -
>  extern struct crypto_template rsa_pkcs1pad_tmpl;
>  #endif


Ciao
Stephan
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Tudor Ambarus June 8, 2016, 10:20 a.m. UTC | #2 
Hi Stephan,

> >  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;
> > +	int ret;
> >
> > -	key->n = mpi_read_raw_data(value, vlen);
> > +	while (!*ptr && vlen) {
> > +		ptr++;
> > +		vlen--;
> > +	}
> 
> As you do this operation 3 times, isn't an inline better here?

Actually this operation makes sense only for n to determine its length.
I will remove the while from rsa_get_e/d. 

> 
> >
> > -	if (!key->n)
> > -		return -ENOMEM;
> > +	/* invalid key provided */
> > +	if (!ptr)
> > +		return -EINVAL;
> 
> Hm, you check the pointer here, but you dereference it already above. So, I
> guess you want to move that check to the beginning of the function?

Sure. Thank you for reviewing!
ta
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diff mbox

Patch

diff --git a/crypto/rsa.c b/crypto/rsa.c
index 77d737f..ea78d61 100644
--- a/crypto/rsa.c
+++ b/crypto/rsa.c
@@ -14,12 +14,24 @@ 
 #include <crypto/internal/akcipher.h>
 #include <crypto/akcipher.h>
 #include <crypto/algapi.h>
+#include <linux/mpi.h>
+
+struct rsa_mpi_key {
+	MPI n;
+	MPI e;
+	MPI d;
+};
+
+struct rsa_ctx {
+	struct rsa_key key;
+	struct rsa_mpi_key mpi_key;
+};
 
 /*
  * RSAEP function [RFC3447 sec 5.1.1]
  * c = m^e mod n;
  */
-static int _rsa_enc(const struct rsa_key *key, MPI c, MPI m)
+static int _rsa_enc(const struct rsa_mpi_key *key, MPI c, MPI m)
 {
 	/* (1) Validate 0 <= m < n */
 	if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
@@ -33,7 +45,7 @@  static int _rsa_enc(const struct rsa_key *key, MPI c, MPI m)
  * RSADP function [RFC3447 sec 5.1.2]
  * m = c^d mod n;
  */
-static int _rsa_dec(const struct rsa_key *key, MPI m, MPI c)
+static int _rsa_dec(const struct rsa_mpi_key *key, MPI m, MPI c)
 {
 	/* (1) Validate 0 <= c < n */
 	if (mpi_cmp_ui(c, 0) < 0 || mpi_cmp(c, key->n) >= 0)
@@ -47,7 +59,7 @@  static int _rsa_dec(const struct rsa_key *key, MPI m, MPI c)
  * RSASP1 function [RFC3447 sec 5.2.1]
  * s = m^d mod n
  */
-static int _rsa_sign(const struct rsa_key *key, MPI s, MPI m)
+static int _rsa_sign(const struct rsa_mpi_key *key, MPI s, MPI m)
 {
 	/* (1) Validate 0 <= m < n */
 	if (mpi_cmp_ui(m, 0) < 0 || mpi_cmp(m, key->n) >= 0)
@@ -61,7 +73,7 @@  static int _rsa_sign(const struct rsa_key *key, MPI s, MPI m)
  * RSAVP1 function [RFC3447 sec 5.2.2]
  * m = s^e mod n;
  */
-static int _rsa_verify(const struct rsa_key *key, MPI m, MPI s)
+static int _rsa_verify(const struct rsa_mpi_key *key, MPI m, MPI s)
 {
 	/* (1) Validate 0 <= s < n */
 	if (mpi_cmp_ui(s, 0) < 0 || mpi_cmp(s, key->n) >= 0)
@@ -71,15 +83,17 @@  static int _rsa_verify(const struct rsa_key *key, MPI m, MPI s)
 	return mpi_powm(m, s, key->e, key->n);
 }
 
-static inline struct rsa_key *rsa_get_key(struct crypto_akcipher *tfm)
+static inline struct rsa_mpi_key *rsa_get_key(struct crypto_akcipher *tfm)
 {
-	return akcipher_tfm_ctx(tfm);
+	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
+
+	return &ctx->mpi_key;
 }
 
 static int rsa_enc(struct akcipher_request *req)
 {
 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
-	const struct rsa_key *pkey = rsa_get_key(tfm);
+	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
 	MPI m, c = mpi_alloc(0);
 	int ret = 0;
 	int sign;
@@ -118,7 +132,7 @@  err_free_c:
 static int rsa_dec(struct akcipher_request *req)
 {
 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
-	const struct rsa_key *pkey = rsa_get_key(tfm);
+	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
 	MPI c, m = mpi_alloc(0);
 	int ret = 0;
 	int sign;
@@ -156,7 +170,7 @@  err_free_m:
 static int rsa_sign(struct akcipher_request *req)
 {
 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
-	const struct rsa_key *pkey = rsa_get_key(tfm);
+	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
 	MPI m, s = mpi_alloc(0);
 	int ret = 0;
 	int sign;
@@ -195,7 +209,7 @@  err_free_s:
 static int rsa_verify(struct akcipher_request *req)
 {
 	struct crypto_akcipher *tfm = crypto_akcipher_reqtfm(req);
-	const struct rsa_key *pkey = rsa_get_key(tfm);
+	const struct rsa_mpi_key *pkey = rsa_get_key(tfm);
 	MPI s, m = mpi_alloc(0);
 	int ret = 0;
 	int sign;
@@ -233,67 +247,94 @@  err_free_m:
 	return ret;
 }
 
-static int rsa_check_key_length(unsigned int len)
+static void rsa_free_mpi_key(struct rsa_mpi_key *key)
 {
-	switch (len) {
-	case 512:
-	case 1024:
-	case 1536:
-	case 2048:
-	case 3072:
-	case 4096:
-		return 0;
-	}
-
-	return -EINVAL;
+	mpi_free(key->d);
+	mpi_free(key->e);
+	mpi_free(key->n);
+	key->d = NULL;
+	key->e = NULL;
+	key->n = NULL;
 }
 
 static int rsa_set_pub_key(struct crypto_akcipher *tfm, const void *key,
 			   unsigned int keylen)
 {
-	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
+	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct rsa_key *pkey = &ctx->key;
+	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
 	int ret;
 
+	/* Free the old MPI key if any */
+	rsa_free_mpi_key(mpi_key);
+
 	ret = rsa_parse_pub_key(pkey, key, keylen);
 	if (ret)
 		return ret;
 
-	if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
-		rsa_free_key(pkey);
-		ret = -EINVAL;
-	}
-	return ret;
+	mpi_key->e = mpi_read_raw_data(pkey->e, pkey->e_sz);
+	if (!mpi_key->e)
+		goto err;
+
+	mpi_key->n = mpi_read_raw_data(pkey->n, pkey->n_sz);
+	if (!mpi_key->n)
+		goto err;
+
+	return 0;
+
+err:
+	rsa_free_mpi_key(mpi_key);
+	return -ENOMEM;
 }
 
 static int rsa_set_priv_key(struct crypto_akcipher *tfm, const void *key,
 			    unsigned int keylen)
 {
-	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
+	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct rsa_key *pkey = &ctx->key;
+	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
 	int ret;
 
+	/* Free the old MPI key if any */
+	rsa_free_mpi_key(mpi_key);
+
 	ret = rsa_parse_priv_key(pkey, key, keylen);
 	if (ret)
 		return ret;
 
-	if (rsa_check_key_length(mpi_get_size(pkey->n) << 3)) {
-		rsa_free_key(pkey);
-		ret = -EINVAL;
-	}
-	return ret;
+	mpi_key->d = mpi_read_raw_data(pkey->d, pkey->n_sz);
+	if (!mpi_key->d)
+		goto err;
+
+	mpi_key->e = mpi_read_raw_data(pkey->e, pkey->e_sz);
+	if (!mpi_key->e)
+		goto err;
+
+	mpi_key->n = mpi_read_raw_data(pkey->n, pkey->n_sz);
+	if (!mpi_key->n)
+		goto err;
+
+	return 0;
+
+err:
+	rsa_free_mpi_key(mpi_key);
+	return -ENOMEM;
 }
 
 static int rsa_max_size(struct crypto_akcipher *tfm)
 {
-	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
+	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct rsa_key *pkey = &ctx->key;
 
-	return pkey->n ? mpi_get_size(pkey->n) : -EINVAL;
+	return pkey->n ? pkey->n_sz : -EINVAL;
 }
 
 static void rsa_exit_tfm(struct crypto_akcipher *tfm)
 {
-	struct rsa_key *pkey = akcipher_tfm_ctx(tfm);
+	struct rsa_ctx *ctx = akcipher_tfm_ctx(tfm);
+	struct rsa_mpi_key *mpi_key = &ctx->mpi_key;
 
-	rsa_free_key(pkey);
+	rsa_free_mpi_key(mpi_key);
 }
 
 static struct akcipher_alg rsa = {
@@ -310,7 +351,7 @@  static struct akcipher_alg rsa = {
 		.cra_driver_name = "rsa-generic",
 		.cra_priority = 100,
 		.cra_module = THIS_MODULE,
-		.cra_ctxsize = sizeof(struct rsa_key),
+		.cra_ctxsize = sizeof(struct rsa_ctx),
 	},
 };
 
diff --git a/crypto/rsa_helper.c b/crypto/rsa_helper.c
index d226f48..f0677b7 100644
--- a/crypto/rsa_helper.c
+++ b/crypto/rsa_helper.c
@@ -18,24 +18,50 @@ 
 #include "rsapubkey-asn1.h"
 #include "rsaprivkey-asn1.h"
 
+static int rsa_check_key_length(unsigned int len)
+{
+	switch (len) {
+	case 512:
+	case 1024:
+	case 1536:
+	case 2048:
+	case 3072:
+	case 4096:
+		return 0;
+	}
+
+	return -EINVAL;
+}
+
 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;
+	int ret;
 
-	key->n = mpi_read_raw_data(value, vlen);
+	while (!*ptr && vlen) {
+		ptr++;
+		vlen--;
+	}
 
-	if (!key->n)
-		return -ENOMEM;
+	/* invalid key provided */
+	if (!ptr)
+		return -EINVAL;
 
 	/* In FIPS mode only allow key size 2K & 3K */
-	if (fips_enabled && (mpi_get_size(key->n) != 256 &&
-			     mpi_get_size(key->n) != 384)) {
+	if (fips_enabled && (vlen != 256 && vlen != 384)) {
 		pr_err("RSA: key size not allowed in FIPS mode\n");
-		mpi_free(key->n);
-		key->n = NULL;
 		return -EINVAL;
 	}
+	/* invalid key size provided */
+	ret = rsa_check_key_length(vlen << 3);
+	if (ret)
+		return ret;
+
+	key->n = ptr;
+	key->n_sz = vlen;
+
 	return 0;
 }
 
@@ -43,11 +69,19 @@  int rsa_get_e(void *context, size_t hdrlen, unsigned char tag,
 	      const void *value, size_t vlen)
 {
 	struct rsa_key *key = context;
+	const u8 *ptr = value;
+
+	while (!*ptr && vlen) {
+		ptr++;
+		vlen--;
+	}
 
-	key->e = mpi_read_raw_data(value, vlen);
+	/* invalid key provided */
+	if (!ptr || !key->n_sz || !vlen || vlen > key->n_sz)
+		return -EINVAL;
 
-	if (!key->e)
-		return -ENOMEM;
+	key->e = ptr;
+	key->e_sz = vlen;
 
 	return 0;
 }
@@ -56,47 +90,33 @@  int rsa_get_d(void *context, size_t hdrlen, unsigned char tag,
 	      const void *value, size_t vlen)
 {
 	struct rsa_key *key = context;
+	const u8 *ptr = value;
 
-	key->d = mpi_read_raw_data(value, vlen);
+	while (!*ptr && vlen) {
+		ptr++;
+		vlen--;
+	}
 
-	if (!key->d)
-		return -ENOMEM;
+	/* invalid key provided */
+	if (!ptr || !key->n_sz || !vlen || vlen > key->n_sz)
+		return -EINVAL;
 
 	/* In FIPS mode only allow key size 2K & 3K */
-	if (fips_enabled && (mpi_get_size(key->d) != 256 &&
-			     mpi_get_size(key->d) != 384)) {
+	if (fips_enabled && (vlen != 256 && vlen != 384)) {
 		pr_err("RSA: key size not allowed in FIPS mode\n");
-		mpi_free(key->d);
-		key->d = NULL;
 		return -EINVAL;
 	}
-	return 0;
-}
 
-static void free_mpis(struct rsa_key *key)
-{
-	mpi_free(key->n);
-	mpi_free(key->e);
-	mpi_free(key->d);
-	key->n = NULL;
-	key->e = NULL;
-	key->d = NULL;
-}
+	key->d = ptr;
+	key->d_sz = vlen;
 
-/**
- * rsa_free_key() - frees rsa key allocated by rsa_parse_key()
- *
- * @rsa_key:	struct rsa_key key representation
- */
-void rsa_free_key(struct rsa_key *key)
-{
-	free_mpis(key);
+	return 0;
 }
-EXPORT_SYMBOL_GPL(rsa_free_key);
 
 /**
- * rsa_parse_pub_key() - extracts an rsa public key from BER encoded buffer
- *			 and stores it in the provided struct rsa_key
+ * 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
@@ -107,23 +127,15 @@  EXPORT_SYMBOL_GPL(rsa_free_key);
 int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
 		      unsigned int key_len)
 {
-	int ret;
-
-	free_mpis(rsa_key);
-	ret = asn1_ber_decoder(&rsapubkey_decoder, rsa_key, key, key_len);
-	if (ret < 0)
-		goto error;
-
-	return 0;
-error:
-	free_mpis(rsa_key);
-	return ret;
+	return asn1_ber_decoder(&rsapubkey_decoder, rsa_key, key, key_len);
 }
 EXPORT_SYMBOL_GPL(rsa_parse_pub_key);
 
 /**
- * rsa_parse_pub_key() - extracts an rsa private key from BER encoded buffer
- *			 and stores it in the provided struct rsa_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
@@ -134,16 +146,6 @@  EXPORT_SYMBOL_GPL(rsa_parse_pub_key);
 int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
 		       unsigned int key_len)
 {
-	int ret;
-
-	free_mpis(rsa_key);
-	ret = asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len);
-	if (ret < 0)
-		goto error;
-
-	return 0;
-error:
-	free_mpis(rsa_key);
-	return ret;
+	return asn1_ber_decoder(&rsaprivkey_decoder, rsa_key, key, key_len);
 }
 EXPORT_SYMBOL_GPL(rsa_parse_priv_key);
diff --git a/include/crypto/internal/rsa.h b/include/crypto/internal/rsa.h
index c7585bd..d6c042a 100644
--- a/include/crypto/internal/rsa.h
+++ b/include/crypto/internal/rsa.h
@@ -12,12 +12,24 @@ 
  */
 #ifndef _RSA_HELPER_
 #define _RSA_HELPER_
-#include <linux/mpi.h>
+#include <linux/types.h>
 
+/**
+ * rsa_key - RSA key structure
+ * @n           : RSA modulus raw byte stream
+ * @e           : RSA public exponent raw byte stream
+ * @d           : RSA private exponent raw byte stream
+ * @n_sz        : length in bytes of RSA modulus n
+ * @e_sz        : length in bytes of RSA public exponent
+ * @d_sz        : length in bytes of RSA private exponent
+ */
 struct rsa_key {
-	MPI n;
-	MPI e;
-	MPI d;
+	const u8 *n;
+	const u8 *e;
+	const u8 *d;
+	size_t n_sz;
+	size_t e_sz;
+	size_t d_sz;
 };
 
 int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
@@ -26,7 +38,5 @@  int rsa_parse_pub_key(struct rsa_key *rsa_key, const void *key,
 int rsa_parse_priv_key(struct rsa_key *rsa_key, const void *key,
 		       unsigned int key_len);
 
-void rsa_free_key(struct rsa_key *rsa_key);
-
 extern struct crypto_template rsa_pkcs1pad_tmpl;
 #endif