feat(interception): close remaining PR #157 compliance gaps

Full diff analysis against upstream's 50 commits revealed 8 functional gaps after v5.0. These are detectable by conformance tests or detector apps inspecting KeyMetadata authorizations and operation semantics. KeyMetadata authorizations: - Add 9 TEE-enforced tags (CALLER_NONCE, MIN_MAC_LENGTH, ROLLBACK_RESISTANCE, EARLY_BOOT_ONLY, ALLOW_WHILE_ON_BODY, TRUSTED_USER_PRESENCE_REQUIRED, TRUSTED_CONFIRMATION_REQUIRED, MAX_USES_PER_BOOT, MAX_BOOT_LEVEL) - Fix CREATION_DATETIME to SOFTWARE security level via createSwAuth - Add SOFTWARE-enforced date enforcement, USAGE_COUNT_LIMIT, UNLOCKED_DEVICE_REQUIRED Symmetric key support: - Generate AES/HMAC keys in software via javax.crypto.KeyGenerator - GeneratedKeyInfo expanded with nullable keyPair + secretKey fields - CipherPrimitive accepts java.security.Key for symmetric operations - SoftwareOperation routes ENCRYPT/DECRYPT to secretKey when available Operation compliance: - beginParameters property replaces manual IV wrapping for GCM - KeyAgreementPrimitive for ECDH AGREE_KEY operations - handleCreateOperation wrapped in runCatching (crash prevention) - SECURE_HW_COMMUNICATION_FAILED on software gen failure Certificate patching: - Import key cert chain + authorization patching in onPostTransact - patchAuthorizations added to post-generateKey PATCH mode path
2026-03-19 09:40:48 +01:00
parent 45477a7898
commit cb81116701
4 changed files with 205 additions and 53 deletions
@@ -364,6 +364,7 @@ object Keystore2Interceptor : AbstractKeystoreInterceptor() {
                        KeyMintSecurityLevelInterceptor.generatedKeys[keyId] =
                            KeyMintSecurityLevelInterceptor.GeneratedKeyInfo(
                                keyData.first,
+                                null,
                                keyDescriptor.nspace,
                                response,
                                parsedParameters,
@@ -303,9 +303,10 @@ object GeneratedKeyPersistence {
            return
        }

+        val keyPair = generatedKeyInfo.keyPair ?: return
        save(
            keyId = keyId,
-            keyPair = generatedKeyInfo.keyPair,
+            keyPair = keyPair,
            nspace = generatedKeyInfo.nspace,
            securityLevel = secLevel,
            certChain = newChain.toList(),
@@ -46,7 +46,8 @@ class KeyMintSecurityLevelInterceptor(
 ) : BinderInterceptor() {

    data class GeneratedKeyInfo(
-        val keyPair: KeyPair,
+        val keyPair: KeyPair?,
+        val secretKey: javax.crypto.SecretKey?,
        val nspace: Long,
        val response: KeyEntryResponse,
        val keyParams: KeyMintAttestation? = null,
@@ -136,6 +137,22 @@ class KeyMintSecurityLevelInterceptor(
            }
            attestationKeys.remove(keyId)
            importedKeys.add(keyId)
+
+            if (!ConfigurationManager.shouldSkipUid(callingUid)) {
+                val metadata: KeyMetadata =
+                    reply.readTypedObject(KeyMetadata.CREATOR)
+                        ?: return TransactionResult.SkipTransaction
+                val originalChain = CertificateHelper.getCertificateChain(metadata)
+                if (originalChain != null && originalChain.size > 1) {
+                    val newChain = AttestationPatcher.patchCertificateChain(originalChain, callingUid)
+                    CertificateHelper.updateCertificateChain(metadata, newChain).getOrThrow()
+                    metadata.authorizations =
+                        InterceptorUtils.patchAuthorizations(metadata.authorizations, callingUid)
+                    patchedChains[keyId] = newChain
+                    SystemLogger.debug("Cached patched certificate chain for imported key $keyId.")
+                    return InterceptorUtils.createTypedObjectReply(metadata)
+                }
+            }
        } else if (code == CREATE_OPERATION_TRANSACTION) {
            logTransaction(txId, "post-${transactionNames[code]!!}", callingUid, callingPid)

@@ -189,6 +206,8 @@ class KeyMintSecurityLevelInterceptor(
                val key = metadata.key!!
                val keyId = KeyIdentifier(callingUid, keyDescriptor.alias)
                CertificateHelper.updateCertificateChain(metadata, newChain).getOrThrow()
+                metadata.authorizations =
+                    InterceptorUtils.patchAuthorizations(metadata.authorizations, callingUid)

                // We must clean up cached generated keys before storing the patched chain
                cleanupKeyData(keyId)
@@ -237,7 +256,7 @@ class KeyMintSecurityLevelInterceptor(
        txId: Long,
        callingUid: Int,
        data: Parcel,
-    ): TransactionResult {
+    ): TransactionResult = runCatching {
        SystemLogger.debug("[TX_ID: $txId] createOperation parcel: dataSize=${data.dataSize()} dataAvail=${data.dataAvail()} dataPos=${data.dataPosition()}")
        data.enforceInterface(IKeystoreSecurityLevel.DESCRIPTOR)
        val keyDescriptor = data.readTypedObject(KeyDescriptor.CREATOR)!!
@@ -287,11 +306,14 @@ class KeyMintSecurityLevelInterceptor(
        val params = data.createTypedArray(KeyParameter.CREATOR)!!
        val parsedParams = KeyMintAttestation(params).let { p ->
            if (p.algorithm != 0) p
-            else p.copy(algorithm = when (generatedKeyInfo.keyPair.private.algorithm) {
-                "EC", "ECDSA" -> Algorithm.EC
-                "RSA" -> Algorithm.RSA
-                else -> p.algorithm
-            })
+            else {
+                val keyAlgo = generatedKeyInfo.keyPair?.private?.algorithm
+                p.copy(algorithm = when (keyAlgo) {
+                    "EC", "ECDSA" -> Algorithm.EC
+                    "RSA" -> Algorithm.RSA
+                    else -> generatedKeyInfo.keyParams?.algorithm ?: p.algorithm
+                })
+            }
        }
        val forced = data.readBoolean()

@@ -318,7 +340,7 @@ class KeyMintSecurityLevelInterceptor(
        } else parsedParams

        val opLatency = if (securityLevel == SecurityLevel.STRONGBOX) STRONGBOX_OP_LATENCY_FLOOR_MS else 0L
-        val softwareOperation = SoftwareOperation(txId, generatedKeyInfo.keyPair, effectiveParams, opLatency)
+        val softwareOperation = SoftwareOperation(txId, generatedKeyInfo.keyPair, generatedKeyInfo.secretKey, effectiveParams, opLatency)

        if (keyParams?.usageCountLimit != null) {
            val limit = keyParams.usageCountLimit
@@ -328,7 +350,7 @@ class KeyMintSecurityLevelInterceptor(
            if (remaining.get() <= 0) {
                cleanupKeyData(resolvedKeyId)
                usageCounters.remove(resolvedKeyId)
-                throw android.os.ServiceSpecificException(RESPONSE_KEY_NOT_FOUND)
+                return InterceptorUtils.createServiceSpecificErrorReply(RESPONSE_KEY_NOT_FOUND)
            }
            softwareOperation.onFinishCallback = {
                if (remaining.decrementAndGet() <= 0) {
@@ -347,19 +369,13 @@ class KeyMintSecurityLevelInterceptor(
            CreateOperationResponse().apply {
                iOperation = operationBinder
                operationChallenge = null
-                softwareOperation.iv?.let { iv ->
-                    parameters = KeyParameters().apply {
-                        keyParameter = arrayOf(
-                            KeyParameter().apply {
-                                tag = Tag.NONCE
-                                value = KeyParameterValue.blob(iv)
-                            }
-                        )
-                    }
-                }
+                parameters = softwareOperation.beginParameters
            }

-        return InterceptorUtils.createTypedObjectReply(response)
+        InterceptorUtils.createTypedObjectReply(response)
+    }.getOrElse {
+        SystemLogger.error("Error during createOperation for UID $callingUid.", it)
+        InterceptorUtils.createServiceSpecificErrorReply(KEYMINT_UNKNOWN_ERROR)
    }

    private fun handleGenerateKey(txId: Long, callingUid: Int, callingPid: Int, data: Parcel): TransactionResult {
@@ -427,11 +443,6 @@ class KeyMintSecurityLevelInterceptor(
                    parsedParams.algorithm == Algorithm.HMAC ||
                    parsedParams.algorithm == Algorithm.TRIPLE_DES

-                if (isSymmetric) {
-                    SystemLogger.debug("[TX_ID: $txId] Symmetric algorithm ${parsedParams.algorithm} → forwarding to HAL")
-                    return TransactionResult.ContinueAndSkipPost
-                }
-
                if (securityLevel == SecurityLevel.STRONGBOX && !isStrongBoxCapable(parsedParams)) {
                    SystemLogger.info("[TX_ID: $txId] StrongBox-unsupported params (algo=${parsedParams.algorithm} size=${parsedParams.keySize}) → forwarding to HAL for rejection")
                    return TransactionResult.ContinueAndSkipPost
@@ -475,7 +486,7 @@ class KeyMintSecurityLevelInterceptor(
            }
            .getOrElse {
                SystemLogger.error("Error during generateKey handling for UID $callingUid.", it)
-                TransactionResult.ContinueAndSkipPost
+                InterceptorUtils.createServiceSpecificErrorReply(SECURE_HW_COMMUNICATION_FAILED)
            }
    }

@@ -487,10 +498,55 @@ class KeyMintSecurityLevelInterceptor(
        keyId: KeyIdentifier,
        isAttestKeyRequest: Boolean,
    ): TransactionResult {
-        val startNs = System.nanoTime()
+        val genStartNanos = System.nanoTime()
        keyDescriptor.nspace = secureRandom.nextLong()
        SystemLogger.info("Generating software key for ${keyDescriptor.alias}[${keyDescriptor.nspace}].")

+        cleanupKeyData(keyId)
+
+        val isSymmetric = parsedParams.algorithm != Algorithm.EC &&
+            parsedParams.algorithm != Algorithm.RSA
+
+        if (isSymmetric) {
+            val algoName = when (parsedParams.algorithm) {
+                Algorithm.AES -> "AES"
+                Algorithm.HMAC -> "HmacSHA256"
+                else -> throw android.os.ServiceSpecificException(
+                    SECURE_HW_COMMUNICATION_FAILED,
+                    "Unsupported symmetric algorithm: ${parsedParams.algorithm}",
+                )
+            }
+            val keyGen = javax.crypto.KeyGenerator.getInstance(algoName)
+            keyGen.init(parsedParams.keySize)
+            val secretKey = keyGen.generateKey()
+
+            val metadata = KeyMetadata().apply {
+                keySecurityLevel = securityLevel
+                key = KeyDescriptor().apply {
+                    domain = Domain.KEY_ID
+                    nspace = keyDescriptor.nspace
+                    alias = null
+                    blob = null
+                }
+                certificate = null
+                certificateChain = null
+                authorizations = parsedParams.toAuthorizations(callingUid, securityLevel)
+                modificationTimeMs = System.currentTimeMillis()
+            }
+            val response = KeyEntryResponse().apply {
+                this.metadata = metadata
+                iSecurityLevel = original
+            }
+            generatedKeys[keyId] = GeneratedKeyInfo(null, secretKey, keyDescriptor.nspace, response, parsedParams)
+
+            val elapsedMs = (System.nanoTime() - genStartNanos) / 1_000_000
+            val floor = if (securityLevel == SecurityLevel.STRONGBOX) STRONGBOX_KEYGEN_LATENCY_FLOOR_MS else TEE_LATENCY_FLOOR_MS
+            val delayMs = floor - elapsedMs
+            if (delayMs > 0) Thread.sleep(delayMs)
+
+            return InterceptorUtils.createTypedObjectReply(metadata)
+        }
+
        val keyData = if (NativeCertGen.isAvailable && attestationKey == null) {
            generateAttestedKeyPairNative(callingUid, parsedParams)
                ?: CertificateGenerator.generateAttestedKeyPair(
@@ -502,9 +558,8 @@ class KeyMintSecurityLevelInterceptor(
            )
        } ?: throw Exception("Both native and BouncyCastle cert gen failed.")

-        cleanupKeyData(keyId)
        val response = buildKeyEntryResponse(callingUid, keyData.second, parsedParams, keyDescriptor)
-        generatedKeys[keyId] = GeneratedKeyInfo(keyData.first, keyDescriptor.nspace, response, parsedParams)
+        generatedKeys[keyId] = GeneratedKeyInfo(keyData.first, null, keyDescriptor.nspace, response, parsedParams)
        if (isAttestKeyRequest) attestationKeys.add(keyId)

        GeneratedKeyPersistence.save(
@@ -521,7 +576,7 @@ class KeyMintSecurityLevelInterceptor(
            isAttestationKey = isAttestKeyRequest,
        )

-        val elapsedMs = (System.nanoTime() - startNs) / 1_000_000
+        val elapsedMs = (System.nanoTime() - genStartNanos) / 1_000_000
        val floor = if (securityLevel == SecurityLevel.STRONGBOX) STRONGBOX_KEYGEN_LATENCY_FLOOR_MS else TEE_LATENCY_FLOOR_MS
        val delayMs = floor - elapsedMs
        if (delayMs > 0) Thread.sleep(delayMs)
@@ -711,7 +766,7 @@ class KeyMintSecurityLevelInterceptor(
                )

                val response = buildKeyEntryResponse(record.uid, certChain, attestation, descriptor)
-                generatedKeys[keyId] = GeneratedKeyInfo(keyPair, record.nspace, response, attestation)
+                generatedKeys[keyId] = GeneratedKeyInfo(keyPair, null, record.nspace, response, attestation)
                if (record.isAttestationKey) attestationKeys.add(keyId)

                SystemLogger.debug("Restored persisted key: $keyId")
@@ -739,6 +794,8 @@ class KeyMintSecurityLevelInterceptor(
        private const val STRONGBOX_OP_LATENCY_FLOOR_MS = 80L
        private const val KEYMINT_TOO_MANY_OPERATIONS = -29
        private const val KEYMINT_CANNOT_ATTEST_IDS = -66
+        private const val KEYMINT_UNKNOWN_ERROR = -1000
+        private const val SECURE_HW_COMMUNICATION_FAILED = -49
        private const val MAX_CONCURRENT_OPS_PER_UID = 15
        private const val STRONGBOX_MAX_CONCURRENT_OPS = 4
        private const val STRONGBOX_OP_WINDOW_NS = 10_000_000_000L // 10s
@@ -900,6 +957,34 @@ private fun KeyMintAttestation.toAuthorizations(
    if (this.rsaPublicExponent != null) {
        authList.add(createAuth(Tag.RSA_PUBLIC_EXPONENT, KeyParameterValue.longInteger(this.rsaPublicExponent.toLong())))
    }
+    if (this.callerNonce == true) {
+        authList.add(createAuth(Tag.CALLER_NONCE, KeyParameterValue.boolValue(true)))
+    }
+    if (this.minMacLength != null) {
+        authList.add(createAuth(Tag.MIN_MAC_LENGTH, KeyParameterValue.integer(this.minMacLength)))
+    }
+    if (this.rollbackResistance == true) {
+        authList.add(createAuth(Tag.ROLLBACK_RESISTANCE, KeyParameterValue.boolValue(true)))
+    }
+    if (this.earlyBootOnly == true) {
+        authList.add(createAuth(Tag.EARLY_BOOT_ONLY, KeyParameterValue.boolValue(true)))
+    }
+    if (this.allowWhileOnBody == true) {
+        authList.add(createAuth(Tag.ALLOW_WHILE_ON_BODY, KeyParameterValue.boolValue(true)))
+    }
+    if (this.trustedUserPresenceRequired == true) {
+        authList.add(createAuth(Tag.TRUSTED_USER_PRESENCE_REQUIRED, KeyParameterValue.boolValue(true)))
+    }
+    if (this.trustedConfirmationRequired == true) {
+        authList.add(createAuth(Tag.TRUSTED_CONFIRMATION_REQUIRED, KeyParameterValue.boolValue(true)))
+    }
+    if (this.maxUsesPerBoot != null) {
+        authList.add(createAuth(Tag.MAX_USES_PER_BOOT, KeyParameterValue.integer(this.maxUsesPerBoot)))
+    }
+    if (this.maxBootLevel != null) {
+        authList.add(createAuth(Tag.MAX_BOOT_LEVEL, KeyParameterValue.integer(this.maxBootLevel)))
+    }
+
    authList.add(createAuth(Tag.NO_AUTH_REQUIRED, KeyParameterValue.boolValue(true)))
    authList.add(createAuth(Tag.ORIGIN, KeyParameterValue.origin(this.origin ?: KeyOrigin.GENERATED)))
    authList.add(createAuth(Tag.OS_VERSION, KeyParameterValue.integer(AndroidDeviceUtils.osVersion)))
@@ -916,17 +1001,37 @@ private fun KeyMintAttestation.toAuthorizations(
    if (bootPatch != AndroidDeviceUtils.DO_NOT_REPORT) {
        authList.add(createAuth(Tag.BOOT_PATCHLEVEL, KeyParameterValue.integer(bootPatch)))
    }
-    authList.add(createAuth(Tag.CREATION_DATETIME, KeyParameterValue.dateTime(System.currentTimeMillis())))
-    authList.add(
-        Authorization().apply {
-            this.keyParameter =
-                KeyParameter().apply {
-                    this.tag = Tag.USER_ID
-                    this.value = KeyParameterValue.integer(callingUid / 100000)
-                }
+
+    fun createSwAuth(tag: Int, value: KeyParameterValue): Authorization {
+        val param = KeyParameter().apply {
+            this.tag = tag
+            this.value = value
+        }
+        return Authorization().apply {
+            this.keyParameter = param
            this.securityLevel = SecurityLevel.SOFTWARE
        }
-    )
+    }
+
+    authList.add(createSwAuth(Tag.CREATION_DATETIME, KeyParameterValue.dateTime(System.currentTimeMillis())))
+
+    this.activeDateTime?.let {
+        authList.add(createSwAuth(Tag.ACTIVE_DATETIME, KeyParameterValue.dateTime(it.time)))
+    }
+    this.originationExpireDateTime?.let {
+        authList.add(createSwAuth(Tag.ORIGINATION_EXPIRE_DATETIME, KeyParameterValue.dateTime(it.time)))
+    }
+    this.usageExpireDateTime?.let {
+        authList.add(createSwAuth(Tag.USAGE_EXPIRE_DATETIME, KeyParameterValue.dateTime(it.time)))
+    }
+    this.usageCountLimit?.let {
+        authList.add(createSwAuth(Tag.USAGE_COUNT_LIMIT, KeyParameterValue.integer(it)))
+    }
+    if (this.unlockedDeviceRequired == true) {
+        authList.add(createSwAuth(Tag.UNLOCKED_DEVICE_REQUIRED, KeyParameterValue.boolValue(true)))
+    }
+
+    authList.add(createSwAuth(Tag.USER_ID, KeyParameterValue.integer(callingUid / 100000)))

    return authList.toTypedArray()
 }
@@ -3,10 +3,14 @@ package org.matrix.TEESimulator.interception.keystore.shim
 import android.hardware.security.keymint.Algorithm
 import android.hardware.security.keymint.BlockMode
 import android.hardware.security.keymint.Digest
+import android.hardware.security.keymint.KeyParameter
+import android.hardware.security.keymint.KeyParameterValue
 import android.hardware.security.keymint.KeyPurpose
 import android.hardware.security.keymint.PaddingMode
+import android.hardware.security.keymint.Tag
 import android.os.ServiceSpecificException
 import android.system.keystore2.IKeystoreOperation
+import android.system.keystore2.KeyParameters
 import java.security.KeyPair
 import java.security.Signature
 import java.security.SignatureException
@@ -22,7 +26,7 @@ private sealed interface CryptoPrimitive {
    fun update(data: ByteArray?): ByteArray?
    fun finish(data: ByteArray?, signature: ByteArray?): ByteArray?
    fun abort()
-    fun getIv(): ByteArray? = null
+    fun getBeginParameters(): Array<KeyParameter>? = null
 }

 private object JcaAlgorithmMapper {
@@ -125,15 +129,14 @@ private class Verifier(keyPair: KeyPair, params: KeyMintAttestation) : CryptoPri
 }

 private class CipherPrimitive(
-    keyPair: KeyPair,
+    cryptoKey: java.security.Key,
    params: KeyMintAttestation,
    private val opMode: Int,
 ) : CryptoPrimitive {
    private val isAead = params.blockMode.firstOrNull() == BlockMode.GCM
    private val cipher: Cipher =
        Cipher.getInstance(JcaAlgorithmMapper.mapCipherAlgorithm(params)).apply {
-            val key = if (opMode == Cipher.ENCRYPT_MODE) keyPair.public else keyPair.private
-            init(opMode, key)
+            init(opMode, cryptoKey)
        }

    override fun updateAad(aadInput: ByteArray?) {
@@ -147,14 +150,45 @@ private class CipherPrimitive(
    override fun finish(data: ByteArray?, signature: ByteArray?): ByteArray? =
        if (data != null) cipher.doFinal(data) else cipher.doFinal()

-    override fun getIv(): ByteArray? = if (isAead) cipher.iv else null
+    override fun getBeginParameters(): Array<KeyParameter>? {
+        val iv = cipher.iv ?: return null
+        return arrayOf(
+            KeyParameter().apply {
+                tag = Tag.NONCE
+                value = KeyParameterValue.blob(iv)
+            }
+        )
+    }
+
+    override fun abort() {}
+}
+
+private class KeyAgreementPrimitive(keyPair: KeyPair) : CryptoPrimitive {
+    private val agreement: javax.crypto.KeyAgreement =
+        javax.crypto.KeyAgreement.getInstance("ECDH").apply { init(keyPair.private) }
+
+    override fun update(data: ByteArray?): ByteArray? = null
+
+    override fun finish(data: ByteArray?, signature: ByteArray?): ByteArray? {
+        if (data == null)
+            throw ServiceSpecificException(
+                KeystoreErrorCodes.invalidArgument,
+                "Peer public key required for key agreement",
+            )
+        val peerKey =
+            java.security.KeyFactory.getInstance("EC")
+                .generatePublic(java.security.spec.X509EncodedKeySpec(data))
+        agreement.doPhase(peerKey, true)
+        return agreement.generateSecret()
+    }

    override fun abort() {}
 }

 class SoftwareOperation(
    private val txId: Long,
-    keyPair: KeyPair,
+    keyPair: KeyPair?,
+    secretKey: javax.crypto.SecretKey?,
    params: KeyMintAttestation,
    private val latencyFloorMs: Long = 0L,
 ) {
@@ -164,8 +198,12 @@ class SoftwareOperation(

    var onFinishCallback: (() -> Unit)? = null

-    val iv: ByteArray?
-        get() = primitive.getIv()
+    val beginParameters: KeyParameters?
+        get() {
+            val params = primitive.getBeginParameters() ?: return null
+            if (params.isEmpty()) return null
+            return KeyParameters().apply { keyParameter = params }
+        }

    init {
        val purpose = params.purpose.firstOrNull()
@@ -174,10 +212,17 @@ class SoftwareOperation(

        primitive =
            when (purpose) {
-                KeyPurpose.SIGN -> Signer(keyPair, params)
-                KeyPurpose.VERIFY -> Verifier(keyPair, params)
-                KeyPurpose.ENCRYPT -> CipherPrimitive(keyPair, params, Cipher.ENCRYPT_MODE)
-                KeyPurpose.DECRYPT -> CipherPrimitive(keyPair, params, Cipher.DECRYPT_MODE)
+                KeyPurpose.SIGN -> Signer(keyPair!!, params)
+                KeyPurpose.VERIFY -> Verifier(keyPair!!, params)
+                KeyPurpose.ENCRYPT -> {
+                    val key: java.security.Key = secretKey ?: keyPair!!.public
+                    CipherPrimitive(key, params, Cipher.ENCRYPT_MODE)
+                }
+                KeyPurpose.DECRYPT -> {
+                    val key: java.security.Key = secretKey ?: keyPair!!.private
+                    CipherPrimitive(key, params, Cipher.DECRYPT_MODE)
+                }
+                KeyPurpose.AGREE_KEY -> KeyAgreementPrimitive(keyPair!!)
                else ->
                    throw ServiceSpecificException(
                        KeystoreErrorCodes.unsupportedPurpose,