binder: abstract out key/cert config

This change allows certificates and keys to be configured in
a custom way.

Bug: 199344157
Fixes: 200195645
Test: pass

Change-Id: I7b88f21652142fd78e99bc5352f1e78000ca050f
diff --git a/libs/binder/tests/Android.bp b/libs/binder/tests/Android.bp
index 1968058..6f3c6e2 100644
--- a/libs/binder/tests/Android.bp
+++ b/libs/binder/tests/Android.bp
@@ -153,6 +153,7 @@
 
     srcs: [
         "binderRpcTest.cpp",
+        "RpcAuthTesting.cpp",
         "RpcCertificateVerifierSimple.cpp",
     ],
     shared_libs: [
diff --git a/libs/binder/tests/RpcAuthTesting.cpp b/libs/binder/tests/RpcAuthTesting.cpp
new file mode 100644
index 0000000..76f7bce
--- /dev/null
+++ b/libs/binder/tests/RpcAuthTesting.cpp
@@ -0,0 +1,73 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+#include "RpcAuthTesting.h"
+#include "../Utils.h" // for TEST_AND_RETURN
+
+namespace android {
+
+bssl::UniquePtr<EVP_PKEY> makeKeyPairForSelfSignedCert() {
+    bssl::UniquePtr<EC_KEY> ec_key(EC_KEY_new_by_curve_name(NID_X9_62_prime256v1));
+    if (ec_key == nullptr || !EC_KEY_generate_key(ec_key.get())) {
+        ALOGE("Failed to generate key pair.");
+        return nullptr;
+    }
+    bssl::UniquePtr<EVP_PKEY> pkey(EVP_PKEY_new());
+    // Use set1 instead of assign to avoid leaking ec_key when assign fails. set1 increments
+    // the refcount of the ec_key, so it is okay to release it at the end of this function.
+    if (pkey == nullptr || !EVP_PKEY_set1_EC_KEY(pkey.get(), ec_key.get())) {
+        ALOGE("Failed to assign key pair.");
+        return nullptr;
+    }
+    return pkey;
+}
+
+bssl::UniquePtr<X509> makeSelfSignedCert(EVP_PKEY* pkey, const uint32_t validSeconds) {
+    bssl::UniquePtr<X509> x509(X509_new());
+    bssl::UniquePtr<BIGNUM> serial(BN_new());
+    bssl::UniquePtr<BIGNUM> serialLimit(BN_new());
+    TEST_AND_RETURN(nullptr, BN_lshift(serialLimit.get(), BN_value_one(), 128));
+    TEST_AND_RETURN(nullptr, BN_rand_range(serial.get(), serialLimit.get()));
+    TEST_AND_RETURN(nullptr, BN_to_ASN1_INTEGER(serial.get(), X509_get_serialNumber(x509.get())));
+    TEST_AND_RETURN(nullptr, X509_gmtime_adj(X509_getm_notBefore(x509.get()), 0));
+    TEST_AND_RETURN(nullptr, X509_gmtime_adj(X509_getm_notAfter(x509.get()), validSeconds));
+
+    X509_NAME* subject = X509_get_subject_name(x509.get());
+    TEST_AND_RETURN(nullptr,
+                    X509_NAME_add_entry_by_txt(subject, "O", MBSTRING_ASC,
+                                               reinterpret_cast<const uint8_t*>("Android"), -1, -1,
+                                               0));
+    TEST_AND_RETURN(nullptr,
+                    X509_NAME_add_entry_by_txt(subject, "CN", MBSTRING_ASC,
+                                               reinterpret_cast<const uint8_t*>("BinderRPC"), -1,
+                                               -1, 0));
+    TEST_AND_RETURN(nullptr, X509_set_issuer_name(x509.get(), subject));
+
+    TEST_AND_RETURN(nullptr, X509_set_pubkey(x509.get(), pkey));
+    TEST_AND_RETURN(nullptr, X509_sign(x509.get(), pkey, EVP_sha256()));
+    return x509;
+}
+
+status_t RpcAuthSelfSigned::configure(SSL_CTX* ctx) {
+    auto pkey = makeKeyPairForSelfSignedCert();
+    TEST_AND_RETURN(UNKNOWN_ERROR, pkey != nullptr);
+    auto cert = makeSelfSignedCert(pkey.get(), mValidSeconds);
+    TEST_AND_RETURN(UNKNOWN_ERROR, cert != nullptr);
+    TEST_AND_RETURN(INVALID_OPERATION, SSL_CTX_use_PrivateKey(ctx, pkey.get()));
+    TEST_AND_RETURN(INVALID_OPERATION, SSL_CTX_use_certificate(ctx, cert.get()));
+    return OK;
+}
+
+} // namespace android
diff --git a/libs/binder/tests/RpcAuthTesting.h b/libs/binder/tests/RpcAuthTesting.h
new file mode 100644
index 0000000..fdc731d
--- /dev/null
+++ b/libs/binder/tests/RpcAuthTesting.h
@@ -0,0 +1,38 @@
+/*
+ * Copyright (C) 2021 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.
+ */
+
+#pragma once
+
+#include <binder/RpcAuth.h>
+
+namespace android {
+
+constexpr const uint32_t kCertValidSeconds = 30 * (60 * 60 * 24); // 30 days
+bssl::UniquePtr<EVP_PKEY> makeKeyPairForSelfSignedCert();
+bssl::UniquePtr<X509> makeSelfSignedCert(EVP_PKEY* pKey, uint32_t validSeconds);
+
+// An implementation of RpcAuth that generates a key pair and a self-signed
+// certificate every time configure() is called.
+class RpcAuthSelfSigned : public RpcAuth {
+public:
+    RpcAuthSelfSigned(uint32_t validSeconds = kCertValidSeconds) : mValidSeconds(validSeconds) {}
+    status_t configure(SSL_CTX* ctx) override;
+
+private:
+    const uint32_t mValidSeconds;
+};
+
+} // namespace android
diff --git a/libs/binder/tests/binderRpcTest.cpp b/libs/binder/tests/binderRpcTest.cpp
index cc1d2fa..05c5030 100644
--- a/libs/binder/tests/binderRpcTest.cpp
+++ b/libs/binder/tests/binderRpcTest.cpp
@@ -48,8 +48,9 @@
 
 #include "../FdTrigger.h"
 #include "../RpcSocketAddress.h" // for testing preconnected clients
-#include "../RpcState.h"   // for debugging
-#include "../vm_sockets.h" // for VMADDR_*
+#include "../RpcState.h"         // for debugging
+#include "../vm_sockets.h"       // for VMADDR_*
+#include "RpcAuthTesting.h"
 #include "RpcCertificateVerifierSimple.h"
 
 using namespace std::chrono_literals;
@@ -71,7 +72,8 @@
 }
 
 static inline std::unique_ptr<RpcTransportCtxFactory> newFactory(
-        RpcSecurity rpcSecurity, std::shared_ptr<RpcCertificateVerifier> verifier = nullptr) {
+        RpcSecurity rpcSecurity, std::shared_ptr<RpcCertificateVerifier> verifier = nullptr,
+        std::unique_ptr<RpcAuth> auth = nullptr) {
     switch (rpcSecurity) {
         case RpcSecurity::RAW:
             return RpcTransportCtxFactoryRaw::make();
@@ -79,7 +81,10 @@
             if (verifier == nullptr) {
                 verifier = std::make_shared<RpcCertificateVerifierSimple>();
             }
-            return RpcTransportCtxFactoryTls::make(std::move(verifier));
+            if (auth == nullptr) {
+                auth = std::make_unique<RpcAuthSelfSigned>();
+            }
+            return RpcTransportCtxFactoryTls::make(std::move(verifier), std::move(auth));
         }
         default:
             LOG_ALWAYS_FATAL("Unknown RpcSecurity %d", rpcSecurity);