Implementing verification of PROFILE_PEER_DEVICE. (09a0dae8) · Commits · e / os / android_frameworks_base

services/core/java/com/android/server/security/AndroidKeystoreAttestationVerificationAttributes.java

0 → 100644

+468 −0

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		/*
		* Copyright (C) 2022 The Android Open Source Project
		*
		* Licensed under the Apache License, Version 2.0 (the "License");
		* you may not use this file except in compliance with the License.
		* You may obtain a copy of the License at
		*
		* http://www.apache.org/licenses/LICENSE-2.0
		*
		* Unless required by applicable law or agreed to in writing, software
		* distributed under the License is distributed on an "AS IS" BASIS,
		* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
		* See the License for the specific language governing permissions and
		* limitations under the License.
		*/

		package com.android.server.security;

		import android.annotation.NonNull;
		import android.annotation.Nullable;

		import com.android.framework.protobuf.ByteString;
		import com.android.internal.org.bouncycastle.asn1.ASN1Boolean;
		import com.android.internal.org.bouncycastle.asn1.ASN1Encodable;
		import com.android.internal.org.bouncycastle.asn1.ASN1Enumerated;
		import com.android.internal.org.bouncycastle.asn1.ASN1InputStream;
		import com.android.internal.org.bouncycastle.asn1.ASN1Integer;
		import com.android.internal.org.bouncycastle.asn1.ASN1ObjectIdentifier;
		import com.android.internal.org.bouncycastle.asn1.ASN1OctetString;
		import com.android.internal.org.bouncycastle.asn1.ASN1Sequence;
		import com.android.internal.org.bouncycastle.asn1.ASN1Set;
		import com.android.internal.org.bouncycastle.asn1.ASN1TaggedObject;
		import com.android.internal.org.bouncycastle.asn1.x509.Certificate;

		import java.nio.charset.StandardCharsets;
		import java.security.cert.CertificateEncodingException;
		import java.security.cert.X509Certificate;
		import java.util.ArrayList;
		import java.util.Collections;
		import java.util.HashMap;
		import java.util.List;
		import java.util.Map;

		/**
		* Parsed {@link X509Certificate} attestation extension values for Android Keystore attestations.
		*
		* Pull fields out of the top-level sequence. A full description of this structure is at
		* https://source.android.com/security/keystore/attestation.
		*
		* If a value is null or empty, then it was not set/found in the extension values.
		*
		*/
		class AndroidKeystoreAttestationVerificationAttributes {
		// The OID for the extension Android Keymaster puts into device-generated certificates.
		private static final String ANDROID_KEYMASTER_KEY_DESCRIPTION_EXTENSION_OID =
		"1.3.6.1.4.1.11129.2.1.17";

		// ASN.1 sequence index values for the Android Keymaster extension.
		private static final int ATTESTATION_VERSION_INDEX = 0;
		private static final int ATTESTATION_SECURITY_LEVEL_INDEX = 1;
		private static final int KEYMASTER_VERSION_INDEX = 2;
		private static final int KEYMASTER_SECURITY_LEVEL_INDEX = 3;
		private static final int ATTESTATION_CHALLENGE_INDEX = 4;
		private static final int KEYMASTER_UNIQUE_ID_INDEX = 5;
		private static final int SW_ENFORCED_INDEX = 6;
		private static final int HW_ENFORCED_INDEX = 7;
		private static final int VERIFIED_BOOT_KEY_INDEX = 0;
		private static final int VERIFIED_BOOT_LOCKED_INDEX = 1;
		private static final int VERIFIED_BOOT_STATE_INDEX = 2;
		private static final int VERIFIED_BOOT_HASH_INDEX = 3;

		// ASN.1 sequence index values for the Android Keystore application id.
		private static final int PACKAGE_INFO_SET_INDEX = 0;
		private static final int PACKAGE_SIGNATURE_SET_INDEX = 1;
		private static final int PACKAGE_INFO_NAME_INDEX = 0;
		private static final int PACKAGE_INFO_VERSION_INDEX = 1;

		// See these AOSP files: hardware/libhardware/include/hardware/hw_auth_token.h
		private static final int HW_AUTH_NONE = 0;

		// Some keymaster constants. See this AOSP file:
		// hardware/libhardware/include/hardware/keymaster_defs.h
		private static final int KM_TAG_NO_AUTH_REQUIRED = 503;
		private static final int KM_TAG_UNLOCKED_DEVICE_REQUIRED = 509;
		private static final int KM_TAG_ALL_APPLICATIONS = 600;
		private static final int KM_TAG_ROOT_OF_TRUST = 704;
		private static final int KM_TAG_OS_VERSION = 705;
		private static final int KM_TAG_OS_PATCHLEVEL = 706;
		private static final int KM_TAG_ATTESTATION_APPLICATION_ID = 709;
		private static final int KM_TAG_ATTESTATION_ID_BRAND = 710;
		private static final int KM_TAG_ATTESTATION_ID_DEVICE = 711;
		private static final int KM_TAG_ATTESTATION_ID_PRODUCT = 712;
		private static final int KM_TAG_VENDOR_PATCHLEVEL = 718;
		private static final int KM_TAG_BOOT_PATCHLEVEL = 719;

		private static final int KM_SECURITY_LEVEL_SOFTWARE = 0;
		private static final int KM_SECURITY_LEVEL_TRUSTED_ENVIRONMENT = 1;
		private static final int KM_SECURITY_LEVEL_STRONG_BOX = 2;
		private static final int KM_VERIFIED_BOOT_STATE_VERIFIED = 0;
		private static final int KM_VERIFIED_BOOT_STATE_SELF_SIGNED = 1;
		private static final int KM_VERIFIED_BOOT_STATE_UNVERIFIED = 2;
		private static final int KM_VERIFIED_BOOT_STATE_FAILED = 3;

		private Integer mAttestationVersion = null;
		private SecurityLevel mAttestationSecurityLevel = null;
		private boolean mAttestationHardwareBacked = false;
		private Integer mKeymasterVersion = null;
		private SecurityLevel mKeymasterSecurityLevel = null;
		private boolean mKeymasterHardwareBacked = false;
		private ByteString mAttestationChallenge = null;
		private ByteString mKeymasterUniqueId = null;
		private String mDeviceBrand = null;
		private String mDeviceName = null;
		private String mDeviceProductName = null;
		private boolean mKeyAllowedForAllApplications = false;
		private Integer mKeyAuthenticatorType = null;
		private Integer mKeyBootPatchLevel = null;
		private Integer mKeyOsPatchLevel = null;
		private Integer mKeyOsVersion = null;
		private Integer mKeyVendorPatchLevel = null;
		private Boolean mKeyRequiresUnlockedDevice = null;
		private ByteString mVerifiedBootHash = null;
		private ByteString mVerifiedBootKey = null;
		private Boolean mVerifiedBootLocked = null;
		private VerifiedBootState mVerifiedBootState = null;
		private Map<String, Long> mApplicationPackageNameVersion = null;
		private List<ByteString> mApplicationCertificateDigests = null;

		enum VerifiedBootState {
		VERIFIED,
		SELF_SIGNED,
		UNVERIFIED,
		FAILED
		}

		enum SecurityLevel {
		SOFTWARE,
		TRUSTED_ENVIRONMENT,
		STRONG_BOX
		}

		/**
		* Extracts attestation extension properties from {@link X509Certificate}
		* and returns a {@link AndroidKeystoreAttestationVerificationAttributes} that encapsulates the
		* properties.
		*/
		@NonNull
		static AndroidKeystoreAttestationVerificationAttributes fromCertificate(
		@NonNull X509Certificate x509Certificate)
		throws Exception {
		return new AndroidKeystoreAttestationVerificationAttributes(x509Certificate);
		}

		int getAttestationVersion() {
		return mAttestationVersion;
		}

		@Nullable
		SecurityLevel getAttestationSecurityLevel() {
		return mAttestationSecurityLevel;
		}

		boolean isAttestationHardwareBacked() {
		return mAttestationHardwareBacked;
		}

		int getKeymasterVersion() {
		return mKeymasterVersion;
		}

		@Nullable
		SecurityLevel getKeymasterSecurityLevel() {
		return mKeymasterSecurityLevel;
		}

		boolean isKeymasterHardwareBacked() {
		return mKeymasterHardwareBacked;
		}

		@Nullable
		ByteString getAttestationChallenge() {
		return mAttestationChallenge;
		}

		@Nullable
		ByteString getKeymasterUniqueId() {
		return mKeymasterUniqueId;
		}

		@Nullable
		String getDeviceBrand() {
		return mDeviceBrand;
		}

		@Nullable
		String getDeviceName() {
		return mDeviceName;
		}

		@Nullable
		String getDeviceProductName() {
		return mDeviceProductName;
		}

		boolean isKeyAllowedForAllApplications() {
		return mKeyAllowedForAllApplications;
		}

		int getKeyAuthenticatorType() {
		if (mKeyAuthenticatorType == null) {
		throw new IllegalStateException("KeyAuthenticatorType is not set.");
		}
		return mKeyAuthenticatorType;
		}

		int getKeyBootPatchLevel() {
		if (mKeyBootPatchLevel == null) {
		throw new IllegalStateException("KeyBootPatchLevel is not set.");
		}
		return mKeyBootPatchLevel;
		}

		int getKeyOsPatchLevel() {
		if (mKeyOsPatchLevel == null) {
		throw new IllegalStateException("KeyOsPatchLevel is not set.");
		}
		return mKeyOsPatchLevel;
		}

		int getKeyVendorPatchLevel() {
		if (mKeyVendorPatchLevel == null) {
		throw new IllegalStateException("KeyVendorPatchLevel is not set.");
		}
		return mKeyVendorPatchLevel;
		}

		int getKeyOsVersion() {
		if (mKeyOsVersion == null) {
		throw new IllegalStateException("KeyOsVersion is not set.");
		}
		return mKeyOsVersion;
		}

		boolean isKeyRequiresUnlockedDevice() {
		if (mKeyRequiresUnlockedDevice == null) {
		throw new IllegalStateException("KeyRequiresUnlockedDevice is not set.");
		}
		return mKeyRequiresUnlockedDevice;
		}

		@Nullable
		ByteString getVerifiedBootHash() {
		return mVerifiedBootHash;
		}

		@Nullable
		ByteString getVerifiedBootKey() {
		return mVerifiedBootKey;
		}

		boolean isVerifiedBootLocked() {
		if (mVerifiedBootLocked == null) {
		throw new IllegalStateException("VerifiedBootLocked is not set.");
		}
		return mVerifiedBootLocked;
		}

		@Nullable
		VerifiedBootState getVerifiedBootState() {
		return mVerifiedBootState;
		}

		@Nullable
		Map<String, Long> getApplicationPackageNameVersion() {
		return Collections.unmodifiableMap(mApplicationPackageNameVersion);
		}

		@Nullable
		List<ByteString> getApplicationCertificateDigests() {
		return Collections.unmodifiableList(mApplicationCertificateDigests);
		}

		private AndroidKeystoreAttestationVerificationAttributes(X509Certificate x509Certificate)
		throws Exception {
		Certificate certificate = Certificate.getInstance(
		new ASN1InputStream(x509Certificate.getEncoded()).readObject());
		ASN1Sequence keyAttributes = (ASN1Sequence) certificate.getTBSCertificate().getExtensions()
		.getExtensionParsedValue(
		new ASN1ObjectIdentifier(ANDROID_KEYMASTER_KEY_DESCRIPTION_EXTENSION_OID));
		if (keyAttributes == null) {
		throw new CertificateEncodingException(
		"No attestation extension found in certificate.");
		}
		this.mAttestationVersion = getIntegerFromAsn1(
		keyAttributes.getObjectAt(ATTESTATION_VERSION_INDEX));
		this.mAttestationSecurityLevel = getSecurityLevelEnum(
		keyAttributes.getObjectAt(ATTESTATION_SECURITY_LEVEL_INDEX));
		this.mAttestationHardwareBacked =
		this.mAttestationSecurityLevel == SecurityLevel.TRUSTED_ENVIRONMENT;
		this.mAttestationChallenge = getOctetsFromAsn1(
		keyAttributes.getObjectAt(ATTESTATION_CHALLENGE_INDEX));
		this.mKeymasterVersion = getIntegerFromAsn1(
		keyAttributes.getObjectAt(KEYMASTER_VERSION_INDEX));
		this.mKeymasterUniqueId = getOctetsFromAsn1(
		keyAttributes.getObjectAt(KEYMASTER_UNIQUE_ID_INDEX));
		this.mKeymasterSecurityLevel = getSecurityLevelEnum(
		keyAttributes.getObjectAt(KEYMASTER_SECURITY_LEVEL_INDEX));
		this.mKeymasterHardwareBacked =
		this.mKeymasterSecurityLevel == SecurityLevel.TRUSTED_ENVIRONMENT;

		ASN1Encodable[] softwareEnforced = ((ASN1Sequence)
		keyAttributes.getObjectAt(SW_ENFORCED_INDEX)).toArray();
		for (ASN1Encodable entry : softwareEnforced) {
		ASN1TaggedObject taggedEntry = (ASN1TaggedObject) entry;
		switch (taggedEntry.getTagNo()) {
		case KM_TAG_ATTESTATION_APPLICATION_ID:
		parseAttestationApplicationId(
		getOctetsFromAsn1(taggedEntry.getObject()).toByteArray());
		break;
		case KM_TAG_UNLOCKED_DEVICE_REQUIRED:
		this.mKeyRequiresUnlockedDevice = getBoolFromAsn1(taggedEntry.getObject());
		break;
		default:
		break;
		}
		}

		ASN1Encodable[] hardwareEnforced = ((ASN1Sequence)
		keyAttributes.getObjectAt(HW_ENFORCED_INDEX)).toArray();
		for (ASN1Encodable entry : hardwareEnforced) {
		ASN1TaggedObject taggedEntry = (ASN1TaggedObject) entry;
		switch (taggedEntry.getTagNo()) {
		case KM_TAG_NO_AUTH_REQUIRED:
		this.mKeyAuthenticatorType = HW_AUTH_NONE;
		break;
		case KM_TAG_ALL_APPLICATIONS:
		this.mKeyAllowedForAllApplications = true;
		break;
		case KM_TAG_ROOT_OF_TRUST:
		ASN1Sequence rootOfTrust = (ASN1Sequence) taggedEntry.getObject();
		this.mVerifiedBootKey =
		getOctetsFromAsn1(rootOfTrust.getObjectAt(VERIFIED_BOOT_KEY_INDEX));
		this.mVerifiedBootLocked =
		getBoolFromAsn1(rootOfTrust.getObjectAt(VERIFIED_BOOT_LOCKED_INDEX));
		this.mVerifiedBootState =
		getVerifiedBootStateEnum(
		rootOfTrust.getObjectAt(VERIFIED_BOOT_STATE_INDEX));
		// The verified boot hash was added in structure version 3 (Keymaster 4.0).
		if (mAttestationVersion >= 3) {
		this.mVerifiedBootHash =
		getOctetsFromAsn1(
		rootOfTrust.getObjectAt(VERIFIED_BOOT_HASH_INDEX));
		}
		break;
		case KM_TAG_OS_VERSION:
		this.mKeyOsVersion = getIntegerFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_OS_PATCHLEVEL:
		this.mKeyOsPatchLevel = getIntegerFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_ATTESTATION_ID_BRAND:
		this.mDeviceBrand = getUtf8FromOctetsFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_ATTESTATION_ID_DEVICE:
		this.mDeviceName = getUtf8FromOctetsFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_ATTESTATION_ID_PRODUCT:
		this.mDeviceProductName = getUtf8FromOctetsFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_VENDOR_PATCHLEVEL:
		this.mKeyVendorPatchLevel = getIntegerFromAsn1(taggedEntry.getObject());
		break;
		case KM_TAG_BOOT_PATCHLEVEL:
		this.mKeyBootPatchLevel = getIntegerFromAsn1(taggedEntry.getObject());
		break;
		default:
		break;
		}
		}
		}

		private void parseAttestationApplicationId(byte [] attestationApplicationId)
		throws Exception {
		ASN1Sequence outerSequence = ASN1Sequence.getInstance(
		new ASN1InputStream(attestationApplicationId).readObject());
		Map<String, Long> packageNameVersion = new HashMap<>();
		ASN1Set packageInfoSet = (ASN1Set) outerSequence.getObjectAt(PACKAGE_INFO_SET_INDEX);
		for (ASN1Encodable packageInfoEntry : packageInfoSet.toArray()) {
		ASN1Sequence packageInfoSequence = (ASN1Sequence) packageInfoEntry;
		packageNameVersion.put(
		getUtf8FromOctetsFromAsn1(
		packageInfoSequence.getObjectAt(PACKAGE_INFO_NAME_INDEX)),
		getLongFromAsn1(packageInfoSequence.getObjectAt(PACKAGE_INFO_VERSION_INDEX)));
		}
		List<ByteString> certificateDigests = new ArrayList<>();
		ASN1Set certificateDigestSet =
		(ASN1Set) outerSequence.getObjectAt(PACKAGE_SIGNATURE_SET_INDEX);
		for (ASN1Encodable certificateDigestEntry : certificateDigestSet.toArray()) {
		certificateDigests.add(getOctetsFromAsn1(certificateDigestEntry));
		}
		this.mApplicationPackageNameVersion = Collections.unmodifiableMap(packageNameVersion);
		this.mApplicationCertificateDigests = Collections.unmodifiableList(certificateDigests);

		}

		private VerifiedBootState getVerifiedBootStateEnum(ASN1Encodable asn1) {
		int verifiedBoot = getEnumFromAsn1(asn1);
		switch (verifiedBoot) {
		case KM_VERIFIED_BOOT_STATE_VERIFIED:
		return VerifiedBootState.VERIFIED;
		case KM_VERIFIED_BOOT_STATE_SELF_SIGNED:
		return VerifiedBootState.SELF_SIGNED;
		case KM_VERIFIED_BOOT_STATE_UNVERIFIED:
		return VerifiedBootState.UNVERIFIED;
		case KM_VERIFIED_BOOT_STATE_FAILED:
		return VerifiedBootState.FAILED;
		default:
		throw new IllegalArgumentException("Invalid verified boot state.");
		}
		}

		private SecurityLevel getSecurityLevelEnum(ASN1Encodable asn1) {
		int securityLevel = getEnumFromAsn1(asn1);
		switch (securityLevel) {
		case KM_SECURITY_LEVEL_SOFTWARE:
		return SecurityLevel.SOFTWARE;
		case KM_SECURITY_LEVEL_TRUSTED_ENVIRONMENT:
		return SecurityLevel.TRUSTED_ENVIRONMENT;
		case KM_SECURITY_LEVEL_STRONG_BOX:
		return SecurityLevel.STRONG_BOX;
		default:
		throw new IllegalArgumentException("Invalid security level.");
		}
		}

		@NonNull
		private ByteString getOctetsFromAsn1(ASN1Encodable asn1) {
		return ByteString.copyFrom(((ASN1OctetString) asn1).getOctets());
		}

		@NonNull
		private String getUtf8FromOctetsFromAsn1(ASN1Encodable asn1) {
		return new String(((ASN1OctetString) asn1).getOctets(), StandardCharsets.UTF_8);
		}

		@NonNull
		private int getIntegerFromAsn1(ASN1Encodable asn1) {
		return ((ASN1Integer) asn1).getValue().intValueExact();
		}

		@NonNull
		private long getLongFromAsn1(ASN1Encodable asn1) {
		return ((ASN1Integer) asn1).getValue().longValueExact();
		}

		@NonNull
		private int getEnumFromAsn1(ASN1Encodable asn1) {
		return ((ASN1Enumerated) asn1).getValue().intValueExact();
		}

		@Nullable
		private Boolean getBoolFromAsn1(ASN1Encodable asn1) {
		if (asn1 instanceof ASN1Boolean) {
		return ((ASN1Boolean) asn1).isTrue();
		}
		return null;
		}
		}

services/core/java/com/android/server/security/AttestationVerificationManagerService.java

+10 −2

Original line number	Diff line number	Diff line
		@@ -16,6 +16,7 @@

		package com.android.server.security;

		import static android.security.attestationverification.AttestationVerificationManager.PROFILE_PEER_DEVICE;
		import static android.security.attestationverification.AttestationVerificationManager.PROFILE_SELF_TRUSTED;
		import static android.security.attestationverification.AttestationVerificationManager.RESULT_FAILURE;
		import static android.security.attestationverification.AttestationVerificationManager.RESULT_UNKNOWN;
		@@ -44,9 +45,11 @@ import com.android.server.SystemService;
		public class AttestationVerificationManagerService extends SystemService {

		private static final String TAG = "AVF";
		private final AttestationVerificationPeerDeviceVerifier mPeerDeviceVerifier;

		public AttestationVerificationManagerService(final Context context) {
		public AttestationVerificationManagerService(final Context context) throws Exception {
		super(context);
		mPeerDeviceVerifier = new AttestationVerificationPeerDeviceVerifier(context);
		}

		private final IBinder mService = new IAttestationVerificationManagerService.Stub() {
		@@ -83,7 +86,7 @@ public class AttestationVerificationManagerService extends SystemService {
		result.token = null;
		switch (profile.getAttestationProfileId()) {
		case PROFILE_SELF_TRUSTED:
		Slog.d(TAG, "Verifying Self trusted profile.");
		Slog.d(TAG, "Verifying Self Trusted profile.");
		try {
		result.resultCode =
		AttestationVerificationSelfTrustedVerifierForTesting.getInstance()
		@@ -92,6 +95,11 @@ public class AttestationVerificationManagerService extends SystemService {
		result.resultCode = RESULT_FAILURE;
		}
		break;
		case PROFILE_PEER_DEVICE:
		Slog.d(TAG, "Verifying Peer Device profile.");
		result.resultCode = mPeerDeviceVerifier.verifyAttestation(
		localBindingType, requirements, attestation);
		break;
		default:
		Slog.d(TAG, "No profile found, defaulting.");
		result.resultCode = RESULT_UNKNOWN;