MM: Check if Secretkeeper is supported from DT
Virtmgr sets a prop in DT to indicate that Secretkeeper HAL is
supported. Use that as the single source of information from host. This
eliminates the vulnerability that arises when host gives different
answers if asked multiple times.
Test: atest MicrodroidTests#encryptedStorageIsPersistent
Bug: 291213394
Change-Id: I0bb71df64462c90dbf197b9630e7c57a94216388
diff --git a/microdroid_manager/src/main.rs b/microdroid_manager/src/main.rs
index 9a9a1f8..2386bd4 100644
--- a/microdroid_manager/src/main.rs
+++ b/microdroid_manager/src/main.rs
@@ -72,6 +72,7 @@
"/proc/device-tree/virtualization/guest/debug-microdroid,no-verified-boot";
const SECRETKEEPER_KEY: &str = "/proc/device-tree/avf/secretkeeper_public_key";
const INSTANCE_ID_PATH: &str = "/proc/device-tree/avf/untrusted/instance-id";
+const DEFER_ROLLBACK_PROTECTION: &str = "/proc/device-tree/avf/untrusted/defer-rollback-protection";
const ENCRYPTEDSTORE_BIN: &str = "/system/bin/encryptedstore";
const ZIPFUSE_BIN: &str = "/system/bin/zipfuse";
@@ -161,6 +162,10 @@
Ok(instance_id)
}
+fn should_defer_rollback_protection() -> bool {
+ Path::new(DEFER_ROLLBACK_PROTECTION).exists()
+}
+
fn main() -> Result<()> {
// If debuggable, print full backtrace to console log with stdio_to_kmsg
if is_debuggable()? {
@@ -299,10 +304,10 @@
let dice = DiceDriver::new(Path::new("/dev/open-dice0"), is_strict_boot())
.context("Failed to load DICE")?;
- // TODO(b/291306122): Checking with host about Secretkeeper support multiple times introduces
- // a whole range of security vulnerability since host can give different answers. Guest should
- // check only once and the same answer should be known to pVM Firmware and Microdroid.
- let instance_data = if let Some(_sk) = vm_secret::is_sk_supported(service)? {
+ // Microdroid skips checking payload against instance image iff the device supports
+ // secretkeeper. In that case Microdroid use VmSecret::V2, which provide protection against
+ // rollback of boot images and packages.
+ let instance_data = if should_defer_rollback_protection() {
verify_payload(&metadata, None)?
} else {
verify_payload_with_instance_img(&metadata, &dice)?