Merge branch 'feature/signature_verify_updates_v3.1' into 'release/v3.1'

secure boot: Support signed app verification without hardware secure boot  (backport v3.1)

See merge request idf/esp-idf!3184

components/bootloader_support/component.mk

@@ -12,7 +12,7 @@ COMPONENT_SRCDIRS := src
 #
 # Secure boot signing key support
 #
-ifdef CONFIG_SECURE_BOOT_ENABLED
+ifdef CONFIG_SECURE_SIGNED_APPS
 
 # this path is created relative to the component build directory
 SECURE_BOOT_VERIFICATION_KEY := $(abspath signature_verification_key.bin)

components/bootloader_support/include/esp_secure_boot.h

@@ -17,6 +17,14 @@
 #include <esp_err.h>
 #include "soc/efuse_reg.h"
 
+#include "sdkconfig.h"
+
+#ifdef CONFIG_SECURE_BOOT_ENABLED
+#if !defined(CONFIG_SECURE_SIGNED_ON_BOOT) || !defined(CONFIG_SECURE_SIGNED_ON_UPDATE) || !defined(CONFIG_SECURE_SIGNED_APPS)
+#error "internal sdkconfig error, secure boot should always enable all signature options"
+#endif
+#endif
+
 #ifdef __cplusplus
 extern "C" {
 #endif

components/bootloader_support/src/esp_image_format.c

@@ -24,6 +24,20 @@
 #include <bootloader_random.h>
 #include <bootloader_sha.h>
 
+/* Checking signatures as part of verifying images is necessary:
+   - Always if secure boot is enabled
+   - Differently in bootloader and/or app, depending on kconfig
+*/
+#ifdef BOOTLOADER_BUILD
+#ifdef CONFIG_SECURE_SIGNED_ON_BOOT
+#define SECURE_BOOT_CHECK_SIGNATURE
+#endif
+#else /* !BOOTLOADER_BUILD */
+#ifdef CONFIG_SECURE_SIGNED_ON_UPDATE
+#define SECURE_BOOT_CHECK_SIGNATURE
+#endif
+#endif
+
 static const char *TAG = "esp_image";
 
 #define HASH_LEN 32 /* SHA-256 digest length */
@@ -107,7 +121,7 @@ esp_err_t esp_image_load(esp_image_load_mode_t mode, const esp_partition_pos_t *
     }
 
     // Calculate SHA-256 of image if secure boot is on, or if image has a hash appended
-#ifdef CONFIG_SECURE_BOOT_ENABLED
+#ifdef SECURE_BOOT_CHECK_SIGNATURE
     if (1) {
 #else
     if (data->image.hash_appended) {
@@ -174,7 +188,7 @@ goto err;
        rewritten the header - rely on esptool.py having verified the bootloader at flashing time, instead.
     */
     if (!is_bootloader) {
-#ifdef CONFIG_SECURE_BOOT_ENABLED
+#ifdef SECURE_BOOT_CHECK_SIGNATURE
         // secure boot images have a signature appended
         err = verify_secure_boot_signature(sha_handle, data);
 #else
@@ -182,7 +196,7 @@ goto err;
         if (sha_handle != NULL && !esp_cpu_in_ocd_debug_mode()) {
             err = verify_simple_hash(sha_handle, data);
         }
-#endif // CONFIG_SECURE_BOOT_ENABLED
+#endif // SECURE_BOOT_CHECK_SIGNATURE
     } else { // is_bootloader
         // bootloader may still have a sha256 digest handle open
         if (sha_handle != NULL) {
@@ -492,6 +506,8 @@ static esp_err_t verify_secure_boot_signature(bootloader_sha256_handle_t sha_han
 {
     uint8_t image_hash[HASH_LEN] = { 0 };
 
+    ESP_LOGI(TAG, "Verifying image signature...");
+
     // For secure boot, we calculate the signature hash over the whole file, which includes any "simple" hash
     // appended to the image for corruption detection
     if (data->image.hash_appended) {