secure boot: Enable based on sdkconfig, remove "secure boot flag" from binary image

components/bootloader/Kconfig.projbuild

@@ -28,6 +28,12 @@ config LOG_BOOTLOADER_LEVEL
     default 4 if LOG_BOOTLOADER_LEVEL_DEBUG
     default 5 if LOG_BOOTLOADER_LEVEL_VERBOSE
 
+endmenu
+
+
+
+menu "Secure boot configuration"
+
 choice SECURE_BOOTLOADER
     bool "Secure bootloader"
     default SECURE_BOOTLOADER_DISABLED
@@ -78,8 +84,35 @@ config SECURE_BOOT_SIGNING_KEY
 
         See docs/security/secure-boot.rst for details.
 
+config SECURE_BOOT_DISABLE_JTAG
+	   bool "First boot: Permanently disable JTAG"
+	   depends on SECURE_BOOTLOADER_ENABLED
+	   default Y
+	   help
+	      Bootloader permanently disable JTAG (across entire chip) when enabling secure boot. This happens on first boot of the bootloader.
+
+		  It is recommended this option remains set for production environments.
+
+config SECURE_BOOT_DISABLE_UART_BOOTLOADER
+ 	   bool "First boot: Permanently disable UART bootloader"
+	   depends on SECURE_BOOTLOADER_ENABLED
+	   default Y
+	   help
+	      Bootloader permanently disables UART and other bootloader modes when enabling secure boot. This happens on first boot.
+
+		  It is recommended this option remains set for production environments.
+
+config SECURE_BOOT_TEST_MODE
+	   bool "Test mode: don't actually enable secure boot"
+	   depends on SECURE_BOOTLOADER_ENABLED
+	   default N
+	   help
+		  If this option is set, all permanent secure boot changes (via Efuse) are disabled.
+
+		  This option is for testing purposes only - it effectively completely disables secure boot protection.
+
 config SECURE_BOOTLOADER_ENABLED
     bool
     default SECURE_BOOTLOADER_ONE_TIME_FLASH || SECURE_BOOTLOADER_REFLASHABLE
 
-endmenu
+endmenu

components/bootloader/src/main/bootloader_start.c

@@ -316,17 +316,17 @@ void bootloader_main()
 
     ESP_LOGI(TAG, "Loading app partition at offset %08x", load_part_pos);
 
-    if(fhdr.secure_boot_flag == 0x01) {
-        /* Generate secure digest from this bootloader to protect future
-         modifications */
-        err = esp_secure_boot_permanently_enable();
-        if (err != ESP_OK){
-            ESP_LOGE(TAG, "Bootloader digest generation failed (%d). SECURE BOOT IS NOT ENABLED.", err);
-            /* Allow booting to continue, as the failure is probably
-               due to user-configured EFUSEs for testing...
-            */
-        }
+#ifdef CONFIG_SECURE_BOOTLOADER_ENABLED
+    /* Generate secure digest from this bootloader to protect future
+       modifications */
+    err = esp_secure_boot_permanently_enable();
+    if (err != ESP_OK) {
+        ESP_LOGE(TAG, "Bootloader digest generation failed (%d). SECURE BOOT IS NOT ENABLED.", err);
+        /* Allow booting to continue, as the failure is probably
+           due to user-configured EFUSEs for testing...
+        */
     }
+#endif
 
     if(fhdr.encrypt_flag == 0x01) {
         /* encrypt flash */
@@ -354,12 +354,16 @@ static void unpack_load_app(const esp_partition_pos_t* partition)
             ESP_LOGE(TAG, "Failed to verify app image @ 0x%x (%d)", partition->offset, err);
             return;
         }
+#ifdef CONFIG_SECURE_BOOTLOADER_ENABLED
+        ESP_LOGI(TAG, "Verifying app signature @ 0x%x (length 0x%x)", partition->offset, image_length);
         err = esp_secure_boot_verify_signature(partition->offset, image_length);
         if (err != ESP_OK) {
             ESP_LOGE(TAG, "App image @ 0x%x failed signature verification (%d)", partition->offset, err);
             return;
         }
+        ESP_LOGD(TAG, "App signature is valid");
     }
+#endif
 
     if (esp_image_load_header(partition->offset, &image_header) != ESP_OK) {
         ESP_LOGE(TAG, "Failed to load app image header @ 0x%x", partition->offset);

components/bootloader_support/include/esp_image_format.h

@@ -64,8 +64,7 @@ typedef struct {
     uint8_t spi_size: 4;   /* flash chip size (esp_image_flash_size_t as uint8_t) */
     uint32_t entry_addr;
     uint8_t encrypt_flag;    /* encrypt flag */
-    uint8_t secure_boot_flag; /* secure boot flag */
-    uint8_t extra_header[14]; /* ESP32 additional header, unused by second bootloader */
+    uint8_t extra_header[15]; /* ESP32 additional header, unused by second bootloader */
 }  esp_image_header_t;
 
 /* Header of binary image segment */

components/bootloader_support/include/esp_secure_boot.h

@@ -32,7 +32,7 @@
  * @return true if secure boot is enabled.
  */
 static inline bool esp_secure_boot_enabled(void) {
-    return REG_GET_FIELD(EFUSE_BLK0_RDATA6_REG, EFUSE_RD_ABS_DONE_0);
+    return REG_READ(EFUSE_BLK0_RDATA6_REG) & EFUSE_RD_ABS_DONE_0;
 }
 
 

components/bootloader_support/src/secure_boot.c

@@ -110,12 +110,16 @@ static bool secure_boot_generate(uint32_t image_len){
 /* Burn values written to the efuse write registers */
 static inline void burn_efuses()
 {
+#ifdef CONFIG_SECURE_BOOT_TEST_MODE
+    ESP_LOGE(TAG, "SECURE BOOT TEST MODE. Not really burning any efuses!");
+#else
     REG_WRITE(EFUSE_CONF_REG, 0x5A5A);  /* efuse_pgm_op_ena, force no rd/wr disable */
     REG_WRITE(EFUSE_CMD_REG,  0x02);    /* efuse_pgm_cmd */
     while (REG_READ(EFUSE_CMD_REG));    /* wait for efuse_pagm_cmd=0 */
     REG_WRITE(EFUSE_CONF_REG, 0x5AA5);  /* efuse_read_op_ena, release force */
     REG_WRITE(EFUSE_CMD_REG,  0x01);    /* efuse_read_cmd */
     while (REG_READ(EFUSE_CMD_REG));    /* wait for efuse_read_cmd=0 */
+#endif
 }
 
 esp_err_t esp_secure_boot_permanently_enable(void) {
@@ -185,10 +189,22 @@ esp_err_t esp_secure_boot_permanently_enable(void) {
         return ESP_ERR_INVALID_STATE;
     }
 
-    ESP_LOGI(TAG, "blowing secure boot efuse & disabling JTAG...");
+    ESP_LOGI(TAG, "blowing secure boot efuse...");
     ESP_LOGD(TAG, "before updating, EFUSE_BLK0_RDATA6 %x", REG_READ(EFUSE_BLK0_RDATA6_REG));
-    REG_WRITE(EFUSE_BLK0_WDATA6_REG,
-                EFUSE_RD_ABS_DONE_0 | EFUSE_RD_DISABLE_JTAG);
+
+    uint32_t new_wdata6 = EFUSE_RD_ABS_DONE_0;
+
+    #ifdef CONFIG_SECURE_BOOT_DISABLE_JTAG
+    ESP_LOGI(TAG, "disabling JTAG...");
+    new_wdata6 |= EFUSE_RD_DISABLE_JTAG;
+    #endif
+
+    #ifdef CONFIG_SECURE_BOOT_DISABLE_UART_BOOTLOADER
+    ESP_LOGI(TAG, "disabling UART bootloader...");
+    new_wdata6 |= EFUSE_RD_CONSOLE_DEBUG_DISABLE_S;
+    #endif
+
+    REG_WRITE(EFUSE_BLK0_WDATA6_REG, new_wdata6);
     burn_efuses();
     uint32_t after = REG_READ(EFUSE_BLK0_RDATA6_REG);
     ESP_LOGD(TAG, "after updating, EFUSE_BLK0_RDATA6 %x", after);
@@ -196,7 +212,11 @@ esp_err_t esp_secure_boot_permanently_enable(void) {
         ESP_LOGI(TAG, "secure boot is now enabled for bootloader image");
         return ESP_OK;
     } else {
+#ifdef CONFIG_SECURE_BOOT_TEST_MODE
+        ESP_LOGE(TAG, "secure boot not enabled due to test mode");
+#else
         ESP_LOGE(TAG, "secure boot not enabled for bootloader image, EFUSE_RD_ABS_DONE_0 is probably write protected!");
+#endif
         return ESP_ERR_INVALID_STATE;
     }
 }