feat(interception): override pre-existing attest keys, skip GMS list hooking
Two changes to Keystore2Interceptor: 1. Hardware attest keys created before TEESimulator loads now get detected in the getKeyEntry post-hook via isAttestKey(). A software replacement keypair is generated, cached, and persisted so the unpatched hardware chain is never served. 2. GMS calls listEntries frequently. Skip the post-hook injection for com.google.android.gms to reduce log flooding and unnecessary key merging work. Also adds null-alias guard in onPreTransact to avoid NPE on keys looked up by domain/nspace without an alias.
This commit is contained in:
Enginex0
+119
-61
@@ -1,22 +1,23 @@
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package org.matrix.TEESimulator.interception.keystore
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import android.annotation.SuppressLint
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import android.hardware.security.keymint.KeyOrigin
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import android.hardware.security.keymint.SecurityLevel
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import android.hardware.security.keymint.Tag
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import android.os.Build
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import android.os.IBinder
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import android.os.Parcel
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import android.system.keystore2.IKeystoreService
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import android.system.keystore2.KeyDescriptor
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import android.system.keystore2.KeyEntryResponse
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import java.security.SecureRandom
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import java.security.cert.Certificate
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import org.matrix.TEESimulator.attestation.AttestationPatcher
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import org.matrix.TEESimulator.attestation.KeyMintAttestation
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import org.matrix.TEESimulator.config.ConfigurationManager
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import org.matrix.TEESimulator.interception.keystore.shim.GeneratedKeyPersistence
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import org.matrix.TEESimulator.interception.keystore.shim.KeyMintSecurityLevelInterceptor
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import org.matrix.TEESimulator.logging.KeyMintParameterLogger
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import org.matrix.TEESimulator.logging.SystemLogger
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import org.matrix.TEESimulator.pki.CertificateGenerator
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import org.matrix.TEESimulator.pki.CertificateHelper
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/**
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@@ -102,10 +103,14 @@ object Keystore2Interceptor : AbstractKeystoreInterceptor() {
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data: Parcel,
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): TransactionResult {
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if (code == LIST_ENTRIES_TRANSACTION || code == LIST_ENTRIES_BATCHED_TRANSACTION) {
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logTransaction(txId, transactionNames[code]!!, callingUid, callingPid)
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logTransaction(txId, transactionNames[code]!!, callingUid, callingPid, true)
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if (ConfigurationManager.shouldSkipUid(callingUid))
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val packages = ConfigurationManager.getPackagesForUid(callingUid).joinToString()
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val isGMS = packages.contains("com.google.android.gms")
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if (isGMS || ConfigurationManager.shouldSkipUid(callingUid)) {
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return TransactionResult.ContinueAndSkipPost
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}
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return runCatching {
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val isBatchMode = code == LIST_ENTRIES_BATCHED_TRANSACTION
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@@ -140,7 +145,14 @@ object Keystore2Interceptor : AbstractKeystoreInterceptor() {
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data.readTypedObject(KeyDescriptor.CREATOR)
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?: return TransactionResult.ContinueAndSkipPost
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SystemLogger.info("Handling ${transactionNames[code]!!} ${descriptor.alias}")
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if (descriptor.alias != null) {
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SystemLogger.info("Handling ${transactionNames[code]!!} ${descriptor.alias}")
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} else {
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SystemLogger.info(
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"Skip ${transactionNames[code]!!} for key [alias, blob, domain, nspace]: [${descriptor.alias}, ${descriptor.blob}, ${descriptor.domain}, ${descriptor.nspace}]"
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)
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return TransactionResult.ContinueAndSkipPost
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}
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val keyId = KeyIdentifier(callingUid, descriptor.alias)
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if (code == DELETE_KEY_TRANSACTION) {
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@@ -210,78 +222,124 @@ object Keystore2Interceptor : AbstractKeystoreInterceptor() {
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TransactionResult.SkipTransaction
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}
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} else if (code == GET_KEY_ENTRY_TRANSACTION) {
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logTransaction(txId, "post-${transactionNames[code]!!}", callingUid, callingPid)
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data.enforceInterface(IKeystoreService.DESCRIPTOR)
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val keyDescriptor =
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data.readTypedObject(KeyDescriptor.CREATOR)
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?: return TransactionResult.SkipTransaction
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logTransaction(
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txId,
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"post-${transactionNames[code]!!} ${keyDescriptor.alias}",
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callingUid,
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callingPid,
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)
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if (!ConfigurationManager.shouldPatch(callingUid))
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return TransactionResult.SkipTransaction
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SystemLogger.info("Handling post-${transactionNames[code]!!} ${keyDescriptor.alias}")
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return try {
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val response =
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reply.readTypedObject(KeyEntryResponse.CREATOR)
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?: return TransactionResult.SkipTransaction
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reply.setDataPosition(0) // Reset for potential reuse.
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val originalChain = CertificateHelper.getCertificateChain(response)
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val authorizations = response.metadata?.authorizations
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val origin =
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authorizations
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?.find { it.keyParameter.tag == Tag.ORIGIN }
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?.let { it.keyParameter.value.origin }
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if (origin == KeyOrigin.IMPORTED || origin == KeyOrigin.SECURELY_IMPORTED) {
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runCatching {
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val response = reply.readTypedObject(KeyEntryResponse.CREATOR)!!
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val keyId = KeyIdentifier(callingUid, keyDescriptor.alias)
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val retainedChain = KeyMintSecurityLevelInterceptor.getPatchedChain(keyId)
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if (retainedChain == null) {
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SystemLogger.info("[TX_ID: $txId] Skip patching for imported key (no prior attestation).")
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val authorizations = response.metadata.authorizations
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val parsedParameters =
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KeyMintAttestation(
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authorizations?.map { it.keyParameter }?.toTypedArray() ?: emptyArray()
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)
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if (parsedParameters.isImportKey()) {
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val retainedChain = KeyMintSecurityLevelInterceptor.getPatchedChain(keyId)
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if (retainedChain == null) {
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SystemLogger.info("[TX_ID: $txId] Skip patching for imported key (no prior attestation).")
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return TransactionResult.SkipTransaction
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}
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SystemLogger.info("[TX_ID: $txId] Imported key overwrote attested alias, serving retained chain for $keyId")
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CertificateHelper.updateCertificateChain(response.metadata, retainedChain).getOrThrow()
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return InterceptorUtils.createTypedObjectReply(response)
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}
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if (parsedParameters.isAttestKey()) {
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SystemLogger.warning(
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"[TX_ID: $txId] Found hardware attest key ${keyId.alias} in the reply."
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)
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val keyData =
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CertificateGenerator.generateAttestedKeyPair(
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callingUid,
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keyId.alias,
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null,
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parsedParameters,
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response.metadata.keySecurityLevel,
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) ?: throw Exception("Failed to create overriding attest key pair.")
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CertificateHelper.updateCertificateChain(
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response.metadata,
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keyData.second.toTypedArray(),
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)
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.getOrThrow()
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keyDescriptor.nspace = SecureRandom().nextLong()
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KeyMintSecurityLevelInterceptor.generatedKeys[keyId] =
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KeyMintSecurityLevelInterceptor.GeneratedKeyInfo(
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keyData.first,
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keyDescriptor.nspace,
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response,
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)
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KeyMintSecurityLevelInterceptor.attestationKeys.add(keyId)
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GeneratedKeyPersistence.save(
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keyId = keyId,
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keyPair = keyData.first,
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nspace = keyDescriptor.nspace,
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securityLevel = response.metadata.keySecurityLevel,
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certChain = keyData.second,
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algorithm = parsedParameters.algorithm,
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keySize = parsedParameters.keySize,
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ecCurve = parsedParameters.ecCurve,
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purposes = parsedParameters.purpose,
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digests = parsedParameters.digest,
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isAttestationKey = true,
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)
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return InterceptorUtils.createTypedObjectReply(response)
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}
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val originalChain = CertificateHelper.getCertificateChain(response)
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if (originalChain == null || originalChain.size < 2) {
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SystemLogger.info(
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"[TX_ID: $txId] Skip patching short certificate chain of length ${originalChain?.size}."
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)
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return TransactionResult.SkipTransaction
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}
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SystemLogger.info("[TX_ID: $txId] Imported key overwrote attested alias, serving retained chain for $keyId")
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CertificateHelper.updateCertificateChain(response.metadata, retainedChain).getOrThrow()
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val cachedChain = KeyMintSecurityLevelInterceptor.getPatchedChain(keyId)
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val finalChain: Array<Certificate>
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if (cachedChain != null) {
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SystemLogger.debug(
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"[TX_ID: $txId] Using cached patched certificate chain for $keyId."
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)
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finalChain = cachedChain
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} else {
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SystemLogger.info(
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"[TX_ID: $txId] No cached chain for $keyId. Performing live patch as a fallback."
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)
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finalChain =
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AttestationPatcher.patchCertificateChain(originalChain, callingUid)
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}
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CertificateHelper.updateCertificateChain(response.metadata, finalChain)
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.getOrThrow()
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return InterceptorUtils.createTypedObjectReply(response)
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}
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if (originalChain == null || originalChain.size < 2) {
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SystemLogger.info(
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"[TX_ID: $txId] Skip patching short certificate chain of length ${originalChain?.size}."
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.onFailure {
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SystemLogger.error(
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"[TX_ID: $txId] Failed to modify hardware KeyEntryResponse.",
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it,
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)
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return TransactionResult.SkipTransaction
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}
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// Perform the attestation patch.
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val keyId = KeyIdentifier(callingUid, keyDescriptor.alias)
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// First, try to retrieve the already-patched chain from our cache to ensure
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// consistency.
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val cachedChain = KeyMintSecurityLevelInterceptor.getPatchedChain(keyId)
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val finalChain: Array<Certificate>
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if (cachedChain != null) {
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SystemLogger.debug(
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"[TX_ID: $txId] Using cached patched certificate chain for $keyId."
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)
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finalChain = cachedChain
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} else {
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// If no chain is cached (e.g., key existed before simulator started),
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// perform a live patch as a fallback. This may still be detectable.
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SystemLogger.info(
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"[TX_ID: $txId] No cached chain for $keyId. Performing live patch as a fallback."
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)
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finalChain = AttestationPatcher.patchCertificateChain(originalChain, callingUid)
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}
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CertificateHelper.updateCertificateChain(response.metadata, finalChain).getOrThrow()
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InterceptorUtils.createTypedObjectReply(response)
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} catch (e: Exception) {
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SystemLogger.error("[TX_ID: $txId] Failed to patch certificate chain.", e)
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TransactionResult.SkipTransaction
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}
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}
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return TransactionResult.SkipTransaction
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}
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