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

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>
Signed-off-by: Herbert Xu <herbert@gondor.apana.org.au>

1 files changed, 39 insertions, 72 deletions

diff --git a/crypto/rsa_helper.c b/crypto/rsa_helper.c
index d226f48d09076..583656af4fe28 100644
--- a/crypto/rsa_helper.c
+++ b/crypto/rsa_helper.c
@@ -22,20 +22,29 @@ 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;
 
-	key->n = mpi_read_raw_data(value, vlen);
-
-	if (!key->n)
-		return -ENOMEM;
-
-	/* In FIPS mode only allow key size 2K & 3K */
-	if (fips_enabled && (mpi_get_size(key->n) != 256 &&
-			     mpi_get_size(key->n) != 384)) {
-		pr_err("RSA: key size not allowed in FIPS mode\n");
-		mpi_free(key->n);
-		key->n = NULL;
+	/* 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;
 }
 
@@ -44,10 +53,12 @@ int rsa_get_e(void *context, size_t hdrlen, unsigned char tag,
 {
 	struct rsa_key *key = context;
 
-	key->e = mpi_read_raw_data(value, vlen);
+	/* invalid key provided */
+	if (!value || !key->n_sz || !vlen || vlen > key->n_sz)
+		return -EINVAL;
 
-	if (!key->e)
-		return -ENOMEM;
+	key->e = value;
+	key->e_sz = vlen;
 
 	return 0;
 }
@@ -57,46 +68,20 @@ int rsa_get_d(void *context, size_t hdrlen, unsigned char tag,
 {
 	struct rsa_key *key = context;
 
-	key->d = mpi_read_raw_data(value, vlen);
-
-	if (!key->d)
-		return -ENOMEM;
-
-	/* In FIPS mode only allow key size 2K & 3K */
-	if (fips_enabled && (mpi_get_size(key->d) != 256 &&
-			     mpi_get_size(key->d) != 384)) {
-		pr_err("RSA: key size not allowed in FIPS mode\n");
-		mpi_free(key->d);
-		key->d = NULL;
+	/* invalid key provided */
+	if (!value || !key->n_sz || !vlen || vlen > key->n_sz)
 		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 = value;
+	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 +92,15 @@ 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 +111,6 @@ 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);