1 files changed, 188 insertions, 107 deletions

diff --git a/src/crypto/rsa.c b/src/crypto/rsa.c
index 2d288a953..19472c121 100644
--- a/src/crypto/rsa.c
+++ b/src/crypto/rsa.c
@@ -47,6 +47,28 @@ FILE_LICENCE ( GPL2_OR_LATER_OR_UBDL );
 #define EINFO_EACCES_VERIFY \
 	__einfo_uniqify ( EINFO_EACCES, 0x01, "RSA signature incorrect" )
 
+/** An RSA context */
+struct rsa_context {
+	/** Allocated memory */
+	void *dynamic;
+	/** Modulus */
+	bigint_element_t *modulus0;
+	/** Modulus size */
+	unsigned int size;
+	/** Modulus length */
+	size_t max_len;
+	/** Exponent */
+	bigint_element_t *exponent0;
+	/** Exponent size */
+	unsigned int exponent_size;
+	/** Input buffer */
+	bigint_element_t *input0;
+	/** Output buffer */
+	bigint_element_t *output0;
+	/** Temporary working space for modular exponentiation */
+	void *tmp;
+};
+
 /**
  * Identify RSA prefix
  *
@@ -69,10 +91,9 @@ rsa_find_prefix ( struct digest_algorithm *digest ) {
  *
  * @v context		RSA context
  */
-static void rsa_free ( struct rsa_context *context ) {
+static inline void rsa_free ( struct rsa_context *context ) {
 
 	free ( context->dynamic );
-	context->dynamic = NULL;
 }
 
 /**
@@ -98,9 +119,6 @@ static int rsa_alloc ( struct rsa_context *context, size_t modulus_len,
 		uint8_t tmp[tmp_len];
 	} __attribute__ (( packed )) *dynamic;
 
-	/* Free any existing dynamic storage */
-	rsa_free ( context );
-
 	/* Allocate dynamic storage */
 	dynamic = malloc ( sizeof ( *dynamic ) );
 	if ( ! dynamic )
@@ -231,12 +249,12 @@ static int rsa_parse_mod_exp ( struct asn1_cursor *modulus,
 /**
  * Initialise RSA cipher
  *
- * @v ctx		RSA context
+ * @v context		RSA context
  * @v key		Key
  * @ret rc		Return status code
  */
-static int rsa_init ( void *ctx, const struct asn1_cursor *key ) {
-	struct rsa_context *context = ctx;
+static int rsa_init ( struct rsa_context *context,
+		      const struct asn1_cursor *key ) {
 	struct asn1_cursor modulus;
 	struct asn1_cursor exponent;
 	int rc;
@@ -277,13 +295,22 @@ static int rsa_init ( void *ctx, const struct asn1_cursor *key ) {
 /**
  * Calculate RSA maximum output length
  *
- * @v ctx		RSA context
+ * @v key		Key
  * @ret max_len		Maximum output length
  */
-static size_t rsa_max_len ( void *ctx ) {
-	struct rsa_context *context = ctx;
+static size_t rsa_max_len ( const struct asn1_cursor *key ) {
+	struct asn1_cursor modulus;
+	struct asn1_cursor exponent;
+	int rc;
 
-	return context->max_len;
+	/* Parse moduli and exponents */
+	if ( ( rc = rsa_parse_mod_exp ( &modulus, &exponent, key ) ) != 0 ) {
+		/* Return a zero maximum length on error */
+		return 0;
+	}
+
+	/* Output length can never exceed modulus length */
+	return modulus.len;
 }
 
 /**
@@ -314,111 +341,147 @@ static void rsa_cipher ( struct rsa_context *context,
 /**
  * Encrypt using RSA
  *
- * @v ctx		RSA context
+ * @v key		Key
  * @v plaintext		Plaintext
  * @v plaintext_len	Length of plaintext
  * @v ciphertext	Ciphertext
  * @ret ciphertext_len	Length of ciphertext, or negative error
  */
-static int rsa_encrypt ( void *ctx, const void *plaintext,
+static int rsa_encrypt ( const struct asn1_cursor *key, const void *plaintext,
 			 size_t plaintext_len, void *ciphertext ) {
-	struct rsa_context *context = ctx;
+	struct rsa_context context;
 	void *temp;
 	uint8_t *encoded;
-	size_t max_len = ( context->max_len - 11 );
-	size_t random_nz_len = ( max_len - plaintext_len + 8 );
+	size_t max_len;
+	size_t random_nz_len;
 	int rc;
 
+	DBGC ( &context, "RSA %p encrypting:\n", &context );
+	DBGC_HDA ( &context, 0, plaintext, plaintext_len );
+
+	/* Initialise context */
+	if ( ( rc = rsa_init ( &context, key ) ) != 0 )
+		goto err_init;
+
+	/* Calculate lengths */
+	max_len = ( context.max_len - 11 );
+	random_nz_len = ( max_len - plaintext_len + 8 );
+
 	/* Sanity check */
 	if ( plaintext_len > max_len ) {
-		DBGC ( context, "RSA %p plaintext too long (%zd bytes, max "
-		       "%zd)\n", context, plaintext_len, max_len );
-		return -ERANGE;
+		DBGC ( &context, "RSA %p plaintext too long (%zd bytes, max "
+		       "%zd)\n", &context, plaintext_len, max_len );
+		rc = -ERANGE;
+		goto err_sanity;
 	}
-	DBGC ( context, "RSA %p encrypting:\n", context );
-	DBGC_HDA ( context, 0, plaintext, plaintext_len );
 
 	/* Construct encoded message (using the big integer output
 	 * buffer as temporary storage)
 	 */
-	temp = context->output0;
+	temp = context.output0;
 	encoded = temp;
 	encoded[0] = 0x00;
 	encoded[1] = 0x02;
 	if ( ( rc = get_random_nz ( &encoded[2], random_nz_len ) ) != 0 ) {
-		DBGC ( context, "RSA %p could not generate random data: %s\n",
-		       context, strerror ( rc ) );
-		return rc;
+		DBGC ( &context, "RSA %p could not generate random data: %s\n",
+		       &context, strerror ( rc ) );
+		goto err_random;
 	}
 	encoded[ 2 + random_nz_len ] = 0x00;
-	memcpy ( &encoded[ context->max_len - plaintext_len ],
+	memcpy ( &encoded[ context.max_len - plaintext_len ],
 		 plaintext, plaintext_len );
 
 	/* Encipher the encoded message */
-	rsa_cipher ( context, encoded, ciphertext );
-	DBGC ( context, "RSA %p encrypted:\n", context );
-	DBGC_HDA ( context, 0, ciphertext, context->max_len );
+	rsa_cipher ( &context, encoded, ciphertext );
+	DBGC ( &context, "RSA %p encrypted:\n", &context );
+	DBGC_HDA ( &context, 0, ciphertext, context.max_len );
+
+	/* Free context */
+	rsa_free ( &context );
 
-	return context->max_len;
+	return context.max_len;
+
+ err_random:
+ err_sanity:
+	rsa_free ( &context );
+ err_init:
+	return rc;
 }
 
 /**
  * Decrypt using RSA
  *
- * @v ctx		RSA context
+ * @v key		Key
  * @v ciphertext	Ciphertext
  * @v ciphertext_len	Ciphertext length
  * @v plaintext		Plaintext
  * @ret plaintext_len	Plaintext length, or negative error
  */
-static int rsa_decrypt ( void *ctx, const void *ciphertext,
+static int rsa_decrypt ( const struct asn1_cursor *key, const void *ciphertext,
 			 size_t ciphertext_len, void *plaintext ) {
-	struct rsa_context *context = ctx;
+	struct rsa_context context;
 	void *temp;
 	uint8_t *encoded;
 	uint8_t *end;
 	uint8_t *zero;
 	uint8_t *start;
 	size_t plaintext_len;
+	int rc;
+
+	DBGC ( &context, "RSA %p decrypting:\n", &context );
+	DBGC_HDA ( &context, 0, ciphertext, ciphertext_len );
+
+	/* Initialise context */
+	if ( ( rc = rsa_init ( &context, key ) ) != 0 )
+		goto err_init;
 
 	/* Sanity check */
-	if ( ciphertext_len != context->max_len ) {
-		DBGC ( context, "RSA %p ciphertext incorrect length (%zd "
+	if ( ciphertext_len != context.max_len ) {
+		DBGC ( &context, "RSA %p ciphertext incorrect length (%zd "
 		       "bytes, should be %zd)\n",
-		       context, ciphertext_len, context->max_len );
-		return -ERANGE;
+		       &context, ciphertext_len, context.max_len );
+		rc = -ERANGE;
+		goto err_sanity;
 	}
-	DBGC ( context, "RSA %p decrypting:\n", context );
-	DBGC_HDA ( context, 0, ciphertext, ciphertext_len );
 
 	/* Decipher the message (using the big integer input buffer as
 	 * temporary storage)
 	 */
-	temp = context->input0;
+	temp = context.input0;
 	encoded = temp;
-	rsa_cipher ( context, ciphertext, encoded );
+	rsa_cipher ( &context, ciphertext, encoded );
 
 	/* Parse the message */
-	end = ( encoded + context->max_len );
-	if ( ( encoded[0] != 0x00 ) || ( encoded[1] != 0x02 ) )
-		goto invalid;
+	end = ( encoded + context.max_len );
+	if ( ( encoded[0] != 0x00 ) || ( encoded[1] != 0x02 ) ) {
+		rc = -EINVAL;
+		goto err_invalid;
+	}
 	zero = memchr ( &encoded[2], 0, ( end - &encoded[2] ) );
-	if ( ! zero )
-		goto invalid;
+	if ( ! zero ) {
+		rc = -EINVAL;
+		goto err_invalid;
+	}
 	start = ( zero + 1 );
 	plaintext_len = ( end - start );
 
 	/* Copy out message */
 	memcpy ( plaintext, start, plaintext_len );
-	DBGC ( context, "RSA %p decrypted:\n", context );
-	DBGC_HDA ( context, 0, plaintext, plaintext_len );
+	DBGC ( &context, "RSA %p decrypted:\n", &context );
+	DBGC_HDA ( &context, 0, plaintext, plaintext_len );
+
+	/* Free context */
+	rsa_free ( &context );
 
 	return plaintext_len;
 
- invalid:
-	DBGC ( context, "RSA %p invalid decrypted message:\n", context );
-	DBGC_HDA ( context, 0, encoded, context->max_len );
-	return -EINVAL;
+ err_invalid:
+	DBGC ( &context, "RSA %p invalid decrypted message:\n", &context );
+	DBGC_HDA ( &context, 0, encoded, context.max_len );
+ err_sanity:
+	rsa_free ( &context );
+ err_init:
+	return rc;
 }
 
 /**
@@ -452,9 +515,9 @@ static int rsa_encode_digest ( struct rsa_context *context,
 	/* Sanity check */
 	max_len = ( context->max_len - 11 );
 	if ( digestinfo_len > max_len ) {
-		DBGC ( context, "RSA %p %s digestInfo too long (%zd bytes, max"
-		       "%zd)\n",
-		       context, digest->name, digestinfo_len, max_len );
+		DBGC ( context, "RSA %p %s digestInfo too long (%zd bytes, "
+		       "max %zd)\n", context, digest->name, digestinfo_len,
+		       max_len );
 		return -ERANGE;
 	}
 	DBGC ( context, "RSA %p encoding %s digest:\n",
@@ -482,104 +545,125 @@ static int rsa_encode_digest ( struct rsa_context *context,
 /**
  * Sign digest value using RSA
  *
- * @v ctx		RSA context
+ * @v key		Key
  * @v digest		Digest algorithm
  * @v value		Digest value
  * @v signature		Signature
  * @ret signature_len	Signature length, or negative error
  */
-static int rsa_sign ( void *ctx, struct digest_algorithm *digest,
-		      const void *value, void *signature ) {
-	struct rsa_context *context = ctx;
+static int rsa_sign ( const struct asn1_cursor *key,
+		      struct digest_algorithm *digest, const void *value,
+		      void *signature ) {
+	struct rsa_context context;
 	void *temp;
 	int rc;
 
-	DBGC ( context, "RSA %p signing %s digest:\n", context, digest->name );
-	DBGC_HDA ( context, 0, value, digest->digestsize );
+	DBGC ( &context, "RSA %p signing %s digest:\n",
+	       &context, digest->name );
+	DBGC_HDA ( &context, 0, value, digest->digestsize );
+
+	/* Initialise context */
+	if ( ( rc = rsa_init ( &context, key ) ) != 0 )
+		goto err_init;
 
 	/* Encode digest (using the big integer output buffer as
 	 * temporary storage)
 	 */
-	temp = context->output0;
-	if ( ( rc = rsa_encode_digest ( context, digest, value, temp ) ) != 0 )
-		return rc;
+	temp = context.output0;
+	if ( ( rc = rsa_encode_digest ( &context, digest, value, temp ) ) != 0 )
+		goto err_encode;
 
 	/* Encipher the encoded digest */
-	rsa_cipher ( context, temp, signature );
-	DBGC ( context, "RSA %p signed %s digest:\n", context, digest->name );
-	DBGC_HDA ( context, 0, signature, context->max_len );
+	rsa_cipher ( &context, temp, signature );
+	DBGC ( &context, "RSA %p signed %s digest:\n", &context, digest->name );
+	DBGC_HDA ( &context, 0, signature, context.max_len );
+
+	/* Free context */
+	rsa_free ( &context );
 
-	return context->max_len;
+	return context.max_len;
+
+ err_encode:
+	rsa_free ( &context );
+ err_init:
+	return rc;
 }
 
 /**
  * Verify signed digest value using RSA
  *
- * @v ctx		RSA context
+ * @v key		Key
  * @v digest		Digest algorithm
  * @v value		Digest value
  * @v signature		Signature
  * @v signature_len	Signature length
  * @ret rc		Return status code
  */
-static int rsa_verify ( void *ctx, struct digest_algorithm *digest,
-			const void *value, const void *signature,
-			size_t signature_len ) {
-	struct rsa_context *context = ctx;
+static int rsa_verify ( const struct asn1_cursor *key,
+			struct digest_algorithm *digest, const void *value,
+			const void *signature, size_t signature_len ) {
+	struct rsa_context context;
 	void *temp;
 	void *expected;
 	void *actual;
 	int rc;
 
+	DBGC ( &context, "RSA %p verifying %s digest:\n",
+	       &context, digest->name );
+	DBGC_HDA ( &context, 0, value, digest->digestsize );
+	DBGC_HDA ( &context, 0, signature, signature_len );
+
+	/* Initialise context */
+	if ( ( rc = rsa_init ( &context, key ) ) != 0 )
+		goto err_init;
+
 	/* Sanity check */
-	if ( signature_len != context->max_len ) {
-		DBGC ( context, "RSA %p signature incorrect length (%zd "
+	if ( signature_len != context.max_len ) {
+		DBGC ( &context, "RSA %p signature incorrect length (%zd "
 		       "bytes, should be %zd)\n",
-		       context, signature_len, context->max_len );
-		return -ERANGE;
+		       &context, signature_len, context.max_len );
+		rc = -ERANGE;
+		goto err_sanity;
 	}
-	DBGC ( context, "RSA %p verifying %s digest:\n",
-	       context, digest->name );
-	DBGC_HDA ( context, 0, value, digest->digestsize );
-	DBGC_HDA ( context, 0, signature, signature_len );
 
 	/* Decipher the signature (using the big integer input buffer
 	 * as temporary storage)
 	 */
-	temp = context->input0;
+	temp = context.input0;
 	expected = temp;
-	rsa_cipher ( context, signature, expected );
-	DBGC ( context, "RSA %p deciphered signature:\n", context );
-	DBGC_HDA ( context, 0, expected, context->max_len );
+	rsa_cipher ( &context, signature, expected );
+	DBGC ( &context, "RSA %p deciphered signature:\n", &context );
+	DBGC_HDA ( &context, 0, expected, context.max_len );
 
 	/* Encode digest (using the big integer output buffer as
 	 * temporary storage)
 	 */
-	temp = context->output0;
+	temp = context.output0;
 	actual = temp;
-	if ( ( rc = rsa_encode_digest ( context, digest, value, actual ) ) !=0 )
-		return rc;
+	if ( ( rc = rsa_encode_digest ( &context, digest, value,
+					actual ) ) != 0 )
+		goto err_encode;
 
 	/* Verify the signature */
-	if ( memcmp ( actual, expected, context->max_len ) != 0 ) {
-		DBGC ( context, "RSA %p signature verification failed\n",
-		       context );
-		return -EACCES_VERIFY;
+	if ( memcmp ( actual, expected, context.max_len ) != 0 ) {
+		DBGC ( &context, "RSA %p signature verification failed\n",
+		       &context );
+		rc = -EACCES_VERIFY;
+		goto err_verify;
 	}
 
-	DBGC ( context, "RSA %p signature verified successfully\n", context );
-	return 0;
-}
+	/* Free context */
+	rsa_free ( &context );
 
-/**
- * Finalise RSA cipher
- *
- * @v ctx		RSA context
- */
-static void rsa_final ( void *ctx ) {
-	struct rsa_context *context = ctx;
+	DBGC ( &context, "RSA %p signature verified successfully\n", &context );
+	return 0;
 
-	rsa_free ( context );
+ err_verify:
+ err_encode:
+ err_sanity:
+	rsa_free ( &context );
+ err_init:
+	return rc;
 }
 
 /**
@@ -615,14 +699,11 @@ static int rsa_match ( const struct asn1_cursor *private_key,
 /** RSA public-key algorithm */
 struct pubkey_algorithm rsa_algorithm = {
 	.name		= "rsa",
-	.ctxsize	= RSA_CTX_SIZE,
-	.init		= rsa_init,
 	.max_len	= rsa_max_len,
 	.encrypt	= rsa_encrypt,
 	.decrypt	= rsa_decrypt,
 	.sign		= rsa_sign,
 	.verify		= rsa_verify,
-	.final		= rsa_final,
 	.match		= rsa_match,
 };