[nrf noup] boot: bootutil: Add shared crypto functions for ECDSA

* Add functions for ecdsa_verify_secp256r1 and sha256 to use the shared
crypto API
* Add Kconfig and CMake variables for selecting shared crypto when using
ecdsa
* Add custom section to project for placing the API section in the
correct location in flash

Signed-off-by: Sigvart Hovland <[email protected]>
(cherry picked from commit 0341ae4)

Author: sigvartmh

boot/bootutil/include/bootutil/sha256.h

@@ -49,6 +49,10 @@
     #include <cc310_glue.h>
 #endif /* MCUBOOT_USE_CC310 */
 
+#ifdef MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
+    #include <bl_crypto.h>
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #include <stdint.h>
 
 #ifdef __cplusplus
@@ -119,6 +123,29 @@ static inline void bootutil_sha256_finish(bootutil_sha256_context *ctx,
 }
 #endif /* MCUBOOT_USE_CC310 */
 
+#ifdef MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
+typedef bl_sha256_ctx_t bootutil_sha256_context;
+
+static inline void bootutil_sha256_init(bootutil_sha256_context *ctx)
+{
+    bl_sha256_init(ctx);
+}
+
+static inline void bootutil_sha256_update(bootutil_sha256_context *ctx,
+                                          const void * data,
+                                          uint32_t data_len)
+{
+    bl_sha256_update(ctx, data, data_len);
+
+}
+
+static inline void bootutil_sha256_finish(bootutil_sha256_context *ctx,
+                                          uint8_t * output)
+{
+    bl_sha256_finalize(ctx, output);
+}
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #ifdef __cplusplus
 }
 #endif

boot/bootutil/src/image_ec256.c

@@ -34,6 +34,11 @@
 #include "cc310_glue.h"
 #define NUM_ECC_BYTES (4*8)
 #endif
+#ifdef MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
+#include "bl_crypto.h"
+#define NUM_ECC_BYTES (4*8)
+#endif
+
 #include "bootutil_priv.h"
 
 /*
@@ -183,6 +188,7 @@ bootutil_verify_sig(uint8_t *hash, uint32_t hlen, uint8_t *sig, size_t slen,
     }
 }
 #endif /* MCUBOOT_USE_TINYCRYPT */
+
 #ifdef MCUBOOT_USE_CC310
 int
 bootutil_verify_sig(uint8_t *hash,
@@ -227,4 +233,50 @@ bootutil_verify_sig(uint8_t *hash,
     return rc;
 }
 #endif /* MCUBOOT_USE_CC310 */
+
+#ifdef MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
+int
+bootutil_verify_sig(uint8_t *hash,
+                    uint32_t hlen,
+                    uint8_t *sig,
+                    size_t slen,
+                    uint8_t key_id)
+{
+    int rc;
+    uint8_t *pubkey;
+    uint8_t *end;
+    uint8_t signature[2 * NUM_ECC_BYTES];
+
+    pubkey = (uint8_t *)bootutil_keys[key_id].key;
+    end = pubkey + *bootutil_keys[key_id].len;
+
+    rc = bootutil_import_key(&pubkey, end);
+    if (rc) {
+        return -1;
+    }
+
+    /* Decode signature */
+    rc = bootutil_decode_sig(signature, sig, sig + slen);
+    if (rc) {
+        return -1;
+    }
+
+    /*
+     * This is simplified, as the hash length is also 32 bytes.
+     */
+    if (hlen != NUM_ECC_BYTES) {
+        return -1;
+    }
+
+    /* Initialize and verify in one go */
+    rc = bl_secp256r1_validate(hash, hlen, pubkey, signature);
+
+    if(rc != 0 /*CRYS_OK*/){
+        return -2;
+    }
+
+    return rc;
+}
+#endif /* MCUBOOT_USE_NRF_EXTERNAL_CRYPTO */
+
 #endif /* MCUBOOT_SIGN_EC256 */

boot/zephyr/CMakeLists.txt

@@ -74,6 +74,8 @@ if(CONFIG_BOOT_USE_NRF_CC310_BL)
 set(NRFXLIB_DIR ${MCUBOOT_DIR}/../nrfxlib)
 assert_exists(NRFXLIB_DIR)
 endif()
+set(NRF_EXTERNAL_CRYPTO_DIR "${MCUBOOT_DIR}/../nrf/subsys/bootloader/bl_crypto")
+assert_exists(NRF_EXTERNAL_CRYPTO_DIR)
 
 zephyr_library_include_directories(
   include
@@ -136,6 +138,8 @@ if(CONFIG_BOOT_SIGNATURE_TYPE_ECDSA_P256)
     zephyr_library_sources(${NRF_DIR}/cc310_glue.c)
     zephyr_library_include_directories(${NRF_DIR})
     zephyr_link_libraries(nrfxlib_crypto)
+  elseif(CONFIG_BOOT_USE_NRF_EXTERNAL_CRYPTO)
+    zephyr_include_directories(${BL_CRYPTO_DIR}/../include)
   endif()
 
   # Since here we are not using Zephyr's mbedTLS but rather our own, we need

boot/zephyr/Kconfig

@@ -47,6 +47,17 @@ config BOOT_USE_NRF_CC310_BL
 	bool
 	default n
 
+config BOOT_USE_NRF_EXTERNAL_CRYPTO
+	bool
+	# Hidden option
+	default n
+	# When building for ECDSA, we use our own copy of mbedTLS, so the
+	# Zephyr one must not be enabled or the MBEDTLS_CONFIG_FILE macros
+	# will collide.
+	depends on ! MBEDTLS
+	help
+	  Use Shared crypto for crypto primitives.
+
 menu "MCUBoot settings"
 
 choice
@@ -76,19 +87,28 @@ config BOOT_SIGNATURE_TYPE_ED25519
 if BOOT_SIGNATURE_TYPE_ECDSA_P256
 choice
 	prompt "Ecdsa implementation"
+	default BOOT_NRF_EXTERNAL_CRYPTO if SECURE_BOOT
 	default BOOT_CC310 if HAS_HW_NRF_CC310
 	default BOOT_TINYCRYPT
+
 config BOOT_TINYCRYPT
 	bool "Use tinycrypt"
 	select BOOT_USE_TINYCRYPT
+
 config BOOT_CC310
 	bool "Use CC310"
 	select BOOT_USE_NRF_CC310_BL if HAS_HW_NRF_CC310
-	select NRF_CC310_BL if HAS_HW_NRF_CC310
 	select NRFXLIB_CRYPTO if SOC_FAMILY_NRF
 	select BOOT_USE_CC310
+
+config BOOT_NRF_EXTERNAL_CRYPTO
+	bool "Use Shared Crypto from bootloader"
+	select BOOT_USE_NRF_EXTERNAL_CRYPTO
+	depends on SECURE_BOOT
+
 endchoice
-endif
+endif #BOOT_SIGNATURE_TYPE_ECDSA_P256
+
 endchoice
 
 config BOOT_SIGNATURE_KEY_FILE

boot/zephyr/include/mcuboot_config/mcuboot_config.h

@@ -38,9 +38,8 @@
 #define MCUBOOT_USE_TINYCRYPT
 #elif defined(CONFIG_BOOT_USE_CC310)
 #define MCUBOOT_USE_CC310
-#ifdef CONFIG_BOOT_USE_NRF_CC310_BL
-#define MCUBOOT_USE_NRF_CC310_BL
-#endif
+#elif defined(CONFIG_BOOT_USE_NRF_EXTERNAL_CRYPTO)
+#define MCUBOOT_USE_NRF_EXTERNAL_CRYPTO
 #endif
 
 #ifdef CONFIG_BOOT_VALIDATE_SLOT0