Require proper DICE if StrongBox is present

If a decice provides a StrongBox KeyMint instance then the default IRPC
instance is required to use a proper, non-degenerate DICE chain.

Expose a function to check whether the CSR contains a proper DICE chain
and use that from VTS to implement the test.

Bug: 302204396
Test: atest VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I90cf070bc2279fc52e0a8e7fd0039d3fdb68c1d7

security/keymint/support/include/remote_prov/remote_prov_utils.h

@@ -183,4 +183,7 @@ ErrMsgOr<std::unique_ptr<cppbor::Array>> verifyProductionCsr(
         const cppbor::Array& keysToSign, const std::vector<uint8_t>& csr,
         IRemotelyProvisionedComponent* provisionable, const std::vector<uint8_t>& challenge);
 
+/** Checks whether the CSR has a proper DICE chain. */
+ErrMsgOr<bool> isCsrWithProperDiceChain(const std::vector<uint8_t>& csr);
+
 }  // namespace aidl::android::hardware::security::keymint::remote_prov

security/keymint/support/remote_prov_utils.cpp

@@ -1081,4 +1081,40 @@ ErrMsgOr<std::unique_ptr<cppbor::Array>> verifyProductionCsr(
     return verifyCsr(keysToSign, csr, provisionable, challenge, /*isFactory=*/false);
 }
 
+ErrMsgOr<bool> isCsrWithProperDiceChain(const std::vector<uint8_t>& csr) {
+    auto [parsedRequest, _, csrErrMsg] = cppbor::parse(csr);
+    if (!parsedRequest) {
+        return csrErrMsg;
+    }
+    if (!parsedRequest->asArray()) {
+        return "AuthenticatedRequest is not a CBOR array.";
+    }
+    if (parsedRequest->asArray()->size() != 4U) {
+        return "AuthenticatedRequest must contain version, UDS certificates, DICE chain, and "
+               "signed data. However, the parsed AuthenticatedRequest has " +
+               std::to_string(parsedRequest->asArray()->size()) + " entries.";
+    }
+
+    auto version = parsedRequest->asArray()->get(0)->asUint();
+    auto diceCertChain = parsedRequest->asArray()->get(2)->asArray();
+
+    if (!version || version->value() != 1U) {
+        return "AuthenticatedRequest version must be an unsigned integer and must be equal to 1.";
+    }
+    if (!diceCertChain) {
+        return "AuthenticatedRequest DiceCertChain must be an Array.";
+    }
+
+    // DICE chain is [ pubkey, + DiceChainEntry ].
+    auto diceChainKind = getDiceChainKind();
+    if (!diceChainKind) {
+        return diceChainKind.message();
+    }
+
+    auto encodedDiceChain = diceCertChain->encode();
+    auto chain = hwtrust::DiceChain::Verify(encodedDiceChain, *diceChainKind);
+    if (!chain.ok()) return chain.error().message();
+    return chain->IsProper();
+}
+
 }  // namespace aidl::android::hardware::security::keymint::remote_prov

security/rkp/aidl/vts/functional/VtsRemotelyProvisionedComponentTests.cpp

@@ -55,8 +55,12 @@ constexpr int32_t VERSION_WITH_SUPPORTED_NUM_KEYS_IN_CSR = 3;
 
 constexpr uint8_t MIN_CHALLENGE_SIZE = 0;
 constexpr uint8_t MAX_CHALLENGE_SIZE = 64;
+const string DEFAULT_INSTANCE_NAME =
+        "android.hardware.security.keymint.IRemotelyProvisionedComponent/default";
 const string RKP_VM_INSTANCE_NAME =
         "android.hardware.security.keymint.IRemotelyProvisionedComponent/avf";
+const string KEYMINT_STRONGBOX_INSTANCE_NAME =
+        "android.hardware.security.keymint.IKeyMintDevice/strongbox";
 
 #define INSTANTIATE_REM_PROV_AIDL_TEST(name)                                         \
     GTEST_ALLOW_UNINSTANTIATED_PARAMETERIZED_TEST(name);                             \
@@ -230,6 +234,37 @@ TEST(NonParameterizedTests, eachRpcHasAUniqueId) {
     }
 }
 
+/**
+ * Verify that the default implementation supports DICE if there is a StrongBox KeyMint instance
+ * on the device.
+ */
+// @VsrTest = 3.10-015
+TEST(NonParameterizedTests, requireDiceOnDefaultInstanceIfStrongboxPresent) {
+    int vsr_api_level = get_vsr_api_level();
+    if (vsr_api_level < 35) {
+        GTEST_SKIP() << "Applies only to VSR API level 35 or newer, this device is: "
+                     << vsr_api_level;
+    }
+
+    if (!AServiceManager_isDeclared(KEYMINT_STRONGBOX_INSTANCE_NAME.c_str())) {
+        GTEST_SKIP() << "Strongbox is not present on this device.";
+    }
+
+    ::ndk::SpAIBinder binder(AServiceManager_waitForService(DEFAULT_INSTANCE_NAME.c_str()));
+    std::shared_ptr<IRemotelyProvisionedComponent> rpc =
+            IRemotelyProvisionedComponent::fromBinder(binder);
+    ASSERT_NE(rpc, nullptr);
+
+    bytevec challenge = randomBytes(64);
+    bytevec csr;
+    auto status = rpc->generateCertificateRequestV2({} /* keysToSign */, challenge, &csr);
+    EXPECT_TRUE(status.isOk()) << status.getDescription();
+
+    auto result = isCsrWithProperDiceChain(csr);
+    ASSERT_TRUE(result) << result.message();
+    ASSERT_TRUE(*result);
+}
+
 using GetHardwareInfoTests = VtsRemotelyProvisionedComponentTests;
 
 INSTANTIATE_REM_PROV_AIDL_TEST(GetHardwareInfoTests);