libmbedtls: support mbedtls bignum functions

Implement bignum function based on mbedtls.

Acked-by: Etienne Carriere <etienne.carriere@linaro.org>
Signed-off-by: Edison Ai <edison.ai@arm.com>
Signed-off-by: Jens Wiklander <jens.wiklander@linaro.org>

4 files changed, 109 insertions, 53 deletions

diff --git a/lib/libmbedtls/core/bignum.c b/lib/libmbedtls/core/bignum.c
new file mode 100644
index 00000000..61f6c5c6
--- /dev/null
+++ b/lib/libmbedtls/core/bignum.c
@@ -0,0 +1,101 @@
+// SPDX-License-Identifier: BSD-2-Clause
+/*
+ * Copyright (C) 2018, ARM Limited
+ * Copyright (C) 2019, Linaro Limited
+ */
+
+#include <assert.h>
+#include <crypto/crypto.h>
+#include <kernel/panic.h>
+#include <mbedtls/bignum.h>
+#include <stdlib.h>
+#include <string.h>
+#include <util.h>
+
+#define ciL		(sizeof(mbedtls_mpi_uint))	/* chars in limb  */
+#define biL		(ciL << 3)			/* bits  in limb  */
+#define BITS_TO_LIMBS(i) ((i) / biL + ((i) % biL != 0))
+
+size_t crypto_bignum_num_bytes(struct bignum *a)
+{
+	assert(a != NULL);
+	return mbedtls_mpi_size((const mbedtls_mpi *)a);
+}
+
+size_t crypto_bignum_num_bits(struct bignum *a)
+{
+	assert(a != NULL);
+	return mbedtls_mpi_bitlen((const mbedtls_mpi *)a);
+}
+
+int32_t crypto_bignum_compare(struct bignum *a, struct bignum *b)
+{
+	int ret = 0;
+
+	assert(a != NULL);
+	assert(b != NULL);
+	ret = mbedtls_mpi_cmp_mpi((const mbedtls_mpi *)a,
+				  (const mbedtls_mpi *)b);
+	return CMP_TRILEAN(ret, 0);
+}
+
+void crypto_bignum_bn2bin(const struct bignum *from, uint8_t *to)
+{
+	size_t len = 0;
+
+	assert(from != NULL);
+	assert(to != NULL);
+	len = crypto_bignum_num_bytes((struct bignum *)from);
+	if (mbedtls_mpi_write_binary((mbedtls_mpi *)from, to, len))
+		panic();
+}
+
+TEE_Result crypto_bignum_bin2bn(const uint8_t *from, size_t fromsize,
+			 struct bignum *to)
+{
+	assert(from != NULL);
+	assert(to != NULL);
+	if (mbedtls_mpi_read_binary((mbedtls_mpi *)to, from, fromsize))
+		return TEE_ERROR_BAD_PARAMETERS;
+	return TEE_SUCCESS;
+}
+
+void crypto_bignum_copy(struct bignum *to, const struct bignum *from)
+{
+	assert(from != NULL);
+	assert(to != NULL);
+	if (mbedtls_mpi_copy((mbedtls_mpi *)to, (const mbedtls_mpi *)from))
+		panic();
+}
+
+struct bignum *crypto_bignum_allocate(size_t size_bits)
+{
+	mbedtls_mpi *bn = NULL;
+
+	if (size_bits > CFG_CORE_BIGNUM_MAX_BITS)
+		size_bits = CFG_CORE_BIGNUM_MAX_BITS;
+
+	bn = calloc(1, sizeof(mbedtls_mpi));
+	if (!bn)
+		return NULL;
+	mbedtls_mpi_init(bn);
+	if (mbedtls_mpi_grow(bn, BITS_TO_LIMBS(size_bits)) != 0) {
+		free(bn);
+		return NULL;
+	}
+
+	return (struct bignum *)bn;
+}
+
+void crypto_bignum_free(struct bignum *s)
+{
+	mbedtls_mpi_free((mbedtls_mpi *)s);
+	free(s);
+}
+
+void crypto_bignum_clear(struct bignum *s)
+{
+	mbedtls_mpi *bn = (mbedtls_mpi *)s;
+
+	memset(bn->p, 0, mbedtls_mpi_size((const mbedtls_mpi *)bn));
+}
diff --git a/lib/libmbedtls/core/stubbed.c b/lib/libmbedtls/core/stubbed.c
index 0cc6bc3c..b7e393cd 100644
--- a/lib/libmbedtls/core/stubbed.c
+++ b/lib/libmbedtls/core/stubbed.c
@@ -15,59 +15,6 @@
  * Asymmetric algorithms
  ******************************************************************************/
 
-#if defined(CFG_CRYPTO_RSA) || defined(CFG_CRYPTO_DSA) || \
-    defined(CFG_CRYPTO_DH) || defined(CFG_CRYPTO_ECC)
-struct bignum *crypto_bignum_allocate(size_t size_bits __unused)
-{
-	return NULL;
-}
-
-TEE_Result crypto_bignum_bin2bn(const uint8_t *from __unused,
-				size_t fromsize __unused,
-				struct bignum *to __unused)
-{
-	return TEE_ERROR_NOT_IMPLEMENTED;
-}
-
-size_t crypto_bignum_num_bytes(struct bignum *a __unused)
-{
-	return 0;
-}
-
-size_t crypto_bignum_num_bits(struct bignum *a __unused)
-{
-	return 0;
-}
-
-void crypto_bignum_bn2bin(const struct bignum *from __unused,
-			  uint8_t *to __unused)
-{
-}
-
-void crypto_bignum_copy(struct bignum *to __unused,
-			const struct bignum *from __unused)
-{
-}
-
-void crypto_bignum_free(struct bignum *a)
-{
-	if (a)
-		panic();
-}
-
-void crypto_bignum_clear(struct bignum *a __unused)
-{
-}
-
-/* return -1 if a<b, 0 if a==b, +1 if a>b */
-int32_t crypto_bignum_compare(struct bignum *a __unused,
-			      struct bignum *b __unused)
-{
-	return -1;
-}
-#endif
-
-
 #if defined(CFG_CRYPTO_RSA)
 TEE_Result crypto_acipher_alloc_rsa_keypair(struct rsa_keypair *s __unused,
 					    size_t key_size_bits __unused)
diff --git a/lib/libmbedtls/core/sub.mk b/lib/libmbedtls/core/sub.mk
index cf65453d..2cc79bd6 100644
--- a/lib/libmbedtls/core/sub.mk
+++ b/lib/libmbedtls/core/sub.mk
@@ -21,3 +21,6 @@ endif
 
 srcs-$(CFG_CRYPTO_HMAC) += hmac.c
 srcs-$(CFG_CRYPTO_CMAC) += aes_cmac.c
+
+srcs-$(call cfg-one-enabled, CFG_CRYPTO_RSA CFG_CRYPTO_DSA \
+			     CFG_CRYPTO_DH CFG_CRYPTO_ECC) += bignum.c
diff --git a/lib/libmbedtls/include/mbedtls_config_kernel.h b/lib/libmbedtls/include/mbedtls_config_kernel.h
index bb7b3787..7a803d61 100644
--- a/lib/libmbedtls/include/mbedtls_config_kernel.h
+++ b/lib/libmbedtls/include/mbedtls_config_kernel.h
@@ -63,6 +63,11 @@
 #define MBEDTLS_CIPHER_C
 #endif
 
+#if defined(CFG_CRYPTO_RSA) || defined(CFG_CRYPTO_DSA) || \
+    defined(CFG_CRYPTO_DH) || defined(CFG_CRYPTO_ECC)
+#define MBEDTLS_BIGNUM_C
+#endif
+
 #endif /*CFG_CRYPTOLIB_NAME_mbedtls*/
 
 #include <mbedtls/check_config.h>