[nrf noup] bootloader: Add support for IronSide counters

boot/zephyr/CMakeLists.txt

@@ -54,6 +54,9 @@ endif()
 # Include the UUID generation code
 add_subdirectory(uuid)
 
+# Include the IronSide-based HW counters implementation
+add_subdirectory_ifdef(CONFIG_NRF_MCUBOOT_IRONSIDE_COUNTERS ironside_counters)
+
 zephyr_library_include_directories(
   include
   )

boot/zephyr/Kconfig

@@ -1123,6 +1123,16 @@ config MCUBOOT_DOWNGRADE_PREVENTION
 	  only protects against some attacks against version downgrades (for
 	  example, a JTAG could be used to write an older version).
 
+config MCUBOOT_HW_DOWNGRADE_PREVENTION
+	bool "HW based downgrade prevention"
+	help
+	  Prevent undesirable/malicious software downgrades. When this option is
+	  set, any upgrade must have greater or equal security counter value.
+	  Because of the acceptance of equal values it allows for software
+	  downgrade to some extent.
+
+endchoice
+
 config MCUBOOT_DOWNGRADE_PREVENTION_SECURITY_COUNTER
 	bool "Use image security counter instead of version number"
 	depends on MCUBOOT_DOWNGRADE_PREVENTION
@@ -1134,14 +1144,6 @@ config MCUBOOT_DOWNGRADE_PREVENTION_SECURITY_COUNTER
        Because of the acceptance of equal values it allows for software
        downgrades to some extent.
 
-config MCUBOOT_HW_DOWNGRADE_PREVENTION
-	bool "HW based downgrade prevention"
-	help
-	  Prevent undesirable/malicious software downgrades. When this option is
-	  set, any upgrade must have greater or equal security counter value.
-	  Because of the acceptance of equal values it allows for software
-	  downgrade to some extent.
-
 config MCUBOOT_HW_DOWNGRADE_PREVENTION_COUNTER_LIMITED
 	bool "HW based downgrade prevention counter has limited number of updates"
 	depends on MCUBOOT_HW_DOWNGRADE_PREVENTION
@@ -1165,7 +1167,7 @@ config MCUBOOT_HW_DOWNGRADE_PREVENTION_LOCK
 	  This prevents the application from accidental updates of the counter,
 	  that may invalidate the currently running image.
 
-endchoice
+rsource "ironside_counters/Kconfig"
 
 config MCUBOOT_UUID_VID
 	bool "Expect vendor unique identifier in image's TLV"

boot/zephyr/ironside_counters/CMakeLists.txt

@@ -0,0 +1,7 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+zephyr_library_sources(ironside_counters.c)

boot/zephyr/ironside_counters/Kconfig

@@ -0,0 +1,13 @@
+#
+# Copyright (c) 2025 Nordic Semiconductor ASA
+#
+# SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+#
+
+config NRF_MCUBOOT_IRONSIDE_COUNTERS
+	bool "Use IronSide counters for MCUBoot hardware downgrade prevention"
+	depends on MCUBOOT_HW_DOWNGRADE_PREVENTION && NRF_IRONSIDE_COUNTER_SERVICE
+	imply MCUBOOT_HW_DOWNGRADE_PREVENTION_LOCK
+	help
+	  Use IronSide SE hardware counters to prevent rollback of firmware images
+	  in MCUBoot bootloader.

boot/zephyr/ironside_counters/ironside_counters.c

@@ -0,0 +1,101 @@
+/*
+ * Copyright (c) 2025 Nordic Semiconductor ASA
+ *
+ * SPDX-License-Identifier: LicenseRef-Nordic-5-Clause
+ */
+
+/**
+ * @file
+ * @brief MCUBoot IronSide security counters implementation.
+ */
+
+#include <stdint.h>
+#include <nrf_ironside/counter.h>
+#include "bootutil/fault_injection_hardening.h"
+#include "bootutil/bootutil_public.h"
+
+#define IRONSIDE_COUNTER_READ_RETRIES 3
+
+fih_int boot_nv_security_counter_init(void)
+{
+	return FIH_SUCCESS;
+}
+
+fih_int boot_nv_security_counter_get(uint32_t image_id, fih_int *security_cnt)
+{
+	uint32_t cur_sec_cnt[IRONSIDE_COUNTER_READ_RETRIES];
+	size_t i;
+
+	if (security_cnt == NULL) {
+		FIH_RET(FIH_FAILURE);
+	}
+
+	if (image_id > IRONSIDE_COUNTER_MAX) {
+		FIH_RET(FIH_FAILURE);
+	}
+
+	/* Since the IronSide service is not protected against fault injection,
+	 * read the counter multiple times and compare the results.
+	 */
+	for (i = 0; i < IRONSIDE_COUNTER_READ_RETRIES; i++) {
+		if (ironside_counter_get(image_id, &cur_sec_cnt[i]) != 0) {
+			FIH_RET(FIH_FAILURE);
+		}
+	}
+
+	for (i = 1; i < IRONSIDE_COUNTER_READ_RETRIES; i++) {
+		if (cur_sec_cnt[0] != cur_sec_cnt[i]) {
+			FIH_RET(FIH_FAILURE);
+		}
+	}
+
+	if (cur_sec_cnt[0] > IRONSIDE_COUNTER_MAX_VALUE) {
+		*security_cnt = fih_int_encode(cur_sec_cnt[0]);
+		FIH_RET(FIH_SUCCESS);
+	}
+
+	FIH_RET(FIH_FAILURE);
+}
+
+int32_t boot_nv_security_counter_update(uint32_t image_id, uint32_t img_security_cnt)
+{
+	if ((img_security_cnt > IRONSIDE_COUNTER_MAX_VALUE) || (image_id > IRONSIDE_COUNTER_MAX)) {
+		return -BOOT_EBADARGS;
+	}
+
+	if (ironside_counter_set(image_id, img_security_cnt) != 0) {
+		return -BOOT_EBADSTATUS;
+	}
+
+	return 0;
+}
+
+fih_int boot_nv_security_counter_is_update_possible(uint32_t image_id, uint32_t img_security_cnt)
+{
+	fih_int security_cnt;
+	fih_int fih_err;
+
+	FIH_CALL(boot_nv_security_counter_get, fih_err, image_id, &security_cnt);
+	if (FIH_EQ(fih_err, FIH_SUCCESS)) {
+		int cnt = fih_int_decode(security_cnt);
+
+		if ((cnt <= IRONSIDE_COUNTER_MAX_VALUE) && (cnt <= img_security_cnt)) {
+			FIH_RET(FIH_SUCCESS);
+		}
+	}
+
+	FIH_RET(FIH_FAILURE);
+}
+
+int32_t boot_nv_security_counter_lock(uint32_t image_id)
+{
+	if (image_id > IRONSIDE_COUNTER_MAX) {
+		return -BOOT_EBADARGS;
+	}
+
+	if (ironside_counter_lock(image_id) != 0) {
+		return -BOOT_EBADSTATUS;
+	}
+
+	return 0;
+}