Add guest OS capability: SecretkeeperProtection
Not all guest OS are capable of interacting with Secretkeeper. Add a
capability "secretkeeper_protection" (which can be extracted from vbmeta
property "com.android.virt.cap"). Add this property to Microdroid
kernel.
pvmfw will have check if the guest OS has this capability & ensures the
rollback_index > 0 if the guest OS has it. Note that this will be
factored in while pvmfw check if updated guest OS should be accepted.
Bug: 291213374
Test: avbtool.py --info microdroid_kernel & check if property is
present.
Test: #payload_with_multiple_capabilities
Change-Id: I99c159d3d65005ec02729b47620ac05ab8d1ec5e
diff --git a/microdroid/Android.bp b/microdroid/Android.bp
index bac93a4..b494cfa 100644
--- a/microdroid/Android.bp
+++ b/microdroid/Android.bp
@@ -418,6 +418,7 @@
],
properties: [
"rollback_index",
+ "props",
],
}
@@ -447,6 +448,12 @@
soong_config_variables: {
release_avf_enable_llpvm_changes: {
rollback_index: 1,
+ props: [
+ {
+ name: "com.android.virt.cap",
+ value: "secretkeeper_protection",
+ },
+ ],
},
},
}
@@ -487,6 +494,12 @@
soong_config_variables: {
release_avf_enable_llpvm_changes: {
rollback_index: 1,
+ props: [
+ {
+ name: "com.android.virt.cap",
+ value: "secretkeeper_protection",
+ },
+ ],
},
},
}
diff --git a/pvmfw/avb/Android.bp b/pvmfw/avb/Android.bp
index f7362d8..6df1c4d 100644
--- a/pvmfw/avb/Android.bp
+++ b/pvmfw/avb/Android.bp
@@ -43,6 +43,7 @@
":test_image_with_multiple_props",
":test_image_with_duplicated_capability",
":test_image_with_rollback_index_5",
+ ":test_image_with_multiple_capabilities",
":unsigned_test_image",
],
prefer_rlib: true,
@@ -204,3 +205,17 @@
salt: "1211",
rollback_index: 5,
}
+
+avb_add_hash_footer {
+ name: "test_image_with_multiple_capabilities",
+ src: ":unsigned_test_image",
+ partition_name: "boot",
+ private_key: ":pvmfw_sign_key",
+ salt: "2134",
+ props: [
+ {
+ name: "com.android.virt.cap",
+ value: "remote_attest|secretkeeper_protection",
+ },
+ ],
+}
diff --git a/pvmfw/avb/src/verify.rs b/pvmfw/avb/src/verify.rs
index 1a16f9d..492d387 100644
--- a/pvmfw/avb/src/verify.rs
+++ b/pvmfw/avb/src/verify.rs
@@ -43,6 +43,13 @@
pub rollback_index: u64,
}
+impl VerifiedBootData<'_> {
+ /// Returns whether the kernel have the given capability
+ pub fn has_capability(&self, cap: Capability) -> bool {
+ self.capabilities.contains(&cap)
+ }
+}
+
/// This enum corresponds to the `DebugLevel` in `VirtualMachineConfig`.
#[derive(Clone, Copy, Debug, PartialEq, Eq)]
pub enum DebugLevel {
@@ -53,15 +60,18 @@
}
/// VM Capability.
-#[derive(Debug, PartialEq, Eq)]
+#[derive(Copy, Clone, Debug, PartialEq, Eq)]
pub enum Capability {
/// Remote attestation.
RemoteAttest,
+ /// Secretkeeper protected secrets.
+ SecretkeeperProtection,
}
impl Capability {
const KEY: &[u8] = b"com.android.virt.cap";
const REMOTE_ATTEST: &[u8] = b"remote_attest";
+ const SECRETKEEPER_PROTECTION: &[u8] = b"secretkeeper_protection";
const SEPARATOR: u8 = b'|';
fn get_capabilities(property_value: &[u8]) -> Result<Vec<Self>, PvmfwVerifyError> {
@@ -70,6 +80,7 @@
for v in property_value.split(|b| *b == Self::SEPARATOR) {
let cap = match v {
Self::REMOTE_ATTEST => Self::RemoteAttest,
+ Self::SECRETKEEPER_PROTECTION => Self::SecretkeeperProtection,
_ => return Err(PvmfwVerifyError::UnknownVbmetaProperty),
};
if res.contains(&cap) {
diff --git a/pvmfw/avb/tests/api_test.rs b/pvmfw/avb/tests/api_test.rs
index 46f5228..6344433 100644
--- a/pvmfw/avb/tests/api_test.rs
+++ b/pvmfw/avb/tests/api_test.rs
@@ -32,6 +32,7 @@
const TEST_IMG_WITH_NON_INITRD_HASHDESC_PATH: &str = "test_image_with_non_initrd_hashdesc.img";
const TEST_IMG_WITH_INITRD_AND_NON_INITRD_DESC_PATH: &str =
"test_image_with_initrd_and_non_initrd_desc.img";
+const TEST_IMG_WITH_MULTIPLE_CAPABILITIES: &str = "test_image_with_multiple_capabilities.img";
const UNSIGNED_TEST_IMG_PATH: &str = "unsigned_test.img";
const RANDOM_FOOTER_POS: usize = 30;
@@ -409,3 +410,18 @@
assert_eq!(expected_boot_data, verified_boot_data);
Ok(())
}
+
+#[test]
+fn payload_with_multiple_capabilities() -> Result<()> {
+ let public_key = load_trusted_public_key()?;
+ let verified_boot_data = verify_payload(
+ &fs::read(TEST_IMG_WITH_MULTIPLE_CAPABILITIES)?,
+ /* initrd= */ None,
+ &public_key,
+ )
+ .map_err(|e| anyhow!("Verification failed. Error: {}", e))?;
+
+ assert!(verified_boot_data.has_capability(Capability::RemoteAttest));
+ assert!(verified_boot_data.has_capability(Capability::SecretkeeperProtection));
+ Ok(())
+}
diff --git a/pvmfw/src/main.rs b/pvmfw/src/main.rs
index d39d51c..b8cbf1b 100644
--- a/pvmfw/src/main.rs
+++ b/pvmfw/src/main.rs
@@ -112,10 +112,22 @@
info!("Please disregard any previous libavb ERROR about initrd_normal.");
}
- if verified_boot_data.capabilities.contains(&Capability::RemoteAttest) {
+ if verified_boot_data.has_capability(Capability::RemoteAttest) {
info!("Service VM capable of remote attestation detected");
}
+ if verified_boot_data.has_capability(Capability::SecretkeeperProtection) {
+ info!("Guest OS is capable of Secretkeeper protection");
+ // For Secretkeeper based Antirollback protection, rollback_index of the image > 0
+ if verified_boot_data.rollback_index == 0 {
+ error!(
+ "Expected positive rollback_index, found {:?}",
+ verified_boot_data.rollback_index
+ );
+ return Err(RebootReason::InvalidPayload);
+ };
+ }
+
let next_bcc = heap::aligned_boxed_slice(NEXT_BCC_SIZE, GUEST_PAGE_SIZE).ok_or_else(|| {
error!("Failed to allocate the next-stage BCC");
RebootReason::InternalError
