Only allow debuggable Microdroid VMs to mount /vendor

Until the verification of the /vendor partition we restrict the usage of
the feature to only debuggable VMs. If a non-debuggable Microdroid VM
is requested to mount /vendor, first_stage_init will crash and the VM
won't boot.

Bug: 285855436
Test: vm run-microdroid --debug none --vendor test_vendor.img
Change-Id: I9d44ad5c1d971bac1a9173c291ce61b628f2f8e9
diff --git a/init/first_stage_init.cpp b/init/first_stage_init.cpp
index e871da2..7fabbac 100644
--- a/init/first_stage_init.cpp
+++ b/init/first_stage_init.cpp
@@ -357,6 +357,18 @@
 
     LOG(INFO) << "init first stage started!";
 
+    // We only allow /vendor partition in debuggable Microdrod until it is verified during boot.
+    // TODO(b/285855436): remove this check.
+    if (IsMicrodroid()) {
+        bool mount_vendor =
+                cmdline.find("androidboot.microdroid.mount_vendor=1") != std::string::npos;
+        bool debuggable =
+                bootconfig.find("androidboot.microdroid.debuggable = \"1\"") != std::string::npos;
+        if (mount_vendor && !debuggable) {
+            LOG(FATAL) << "Attempted to mount /vendor partition for non-debuggable Microdroid VM";
+        }
+    }
+
     auto old_root_dir = std::unique_ptr<DIR, decltype(&closedir)>{opendir("/"), closedir};
     if (!old_root_dir) {
         PLOG(ERROR) << "Could not opendir(\"/\"), not freeing ramdisk";