Strict instance boot checks

When strict boot is active, ensure the instance image is provisioned
during the first, and only the first, boot of the instance. This
prevents and instance from being forked.

Bug: 217376291
Test: atest MicrodroidTests
Change-Id: I648b7df3b3368a3766f9f4e76b8f70f59d05659a

microdroid_manager/src/main.rs

@@ -61,6 +61,8 @@ const EXTRA_IDSIG_PATH_PATTERN: &str = "/dev/block/by-name/extra-idsig-*";
 const DM_MOUNTED_APK_PATH: &str = "/dev/block/mapper/microdroid-apk";
 const APKDMVERITY_BIN: &str = "/system/bin/apkdmverity";
 const ZIPFUSE_BIN: &str = "/system/bin/zipfuse";
+const AVF_STRICT_BOOT: &str = "/sys/firmware/devicetree/base/chosen/avf,strict-boot";
+const AVF_NEW_INSTANCE: &str = "/sys/firmware/devicetree/base/chosen/avf,new-instance";
 
 /// The CID representing the host VM
 const VMADDR_CID_HOST: u32 = 2;
@@ -193,12 +195,35 @@ fn dice_derivation(verified_data: MicrodroidData, payload_config_path: &str) ->
     Ok(())
 }
 
+fn is_strict_boot() -> bool {
+    Path::new(AVF_STRICT_BOOT).exists()
+}
+
+fn is_new_instance() -> bool {
+    Path::new(AVF_NEW_INSTANCE).exists()
+}
+
 fn try_run_payload(service: &Strong<dyn IVirtualMachineService>) -> Result<i32> {
     let metadata = load_metadata().context("Failed to load payload metadata")?;
 
     let mut instance = InstanceDisk::new().context("Failed to load instance.img")?;
     let saved_data = instance.read_microdroid_data().context("Failed to read identity data")?;
 
+    if is_strict_boot() {
+        // Provisioning must happen on the first boot and never again.
+        if is_new_instance() {
+            ensure!(
+                saved_data.is_none(),
+                MicrodroidError::InvalidConfig("Found instance data on first boot.".to_string())
+            );
+        } else {
+            ensure!(
+                saved_data.is_some(),
+                MicrodroidError::InvalidConfig("Instance data not found.".to_string())
+            );
+        };
+    }
+
     // Verify the payload before using it.
     let verified_data =
         verify_payload(&metadata, saved_data.as_ref()).context("Payload verification failed")?;