Add a utility to JSON-format a CSR with build info
We need both the build fingerprint as well as the CSR when uploading
data to the APFE provisioning server. Add a utility function to format
the output as a JSON blob so that it may be easily collected in the
factory in a serialized data format, then later uploaded.
Test: libkeymint_remote_prov_support_test
Test: VtsAidlKeyMintTargetTest
Test: VtsHalRemotelyProvisionedComponentTargetTest
Bug: 191301285
Change-Id: I751c5461876d83251869539f1a395ba13cb5cf84
diff --git a/security/keymint/support/Android.bp b/security/keymint/support/Android.bp
index c2dba04..9e218b6 100644
--- a/security/keymint/support/Android.bp
+++ b/security/keymint/support/Android.bp
@@ -57,9 +57,11 @@
"include",
],
shared_libs: [
+ "libbase",
"libcppbor_external",
"libcppcose_rkp",
"libcrypto",
+ "libjsoncpp",
],
}
@@ -71,9 +73,11 @@
"libgtest_main",
],
shared_libs: [
+ "libbase",
"libcppbor_external",
"libcppcose_rkp",
"libcrypto",
+ "libjsoncpp",
"libkeymaster_portable",
"libkeymint_remote_prov_support",
],
diff --git a/security/keymint/support/include/remote_prov/remote_prov_utils.h b/security/keymint/support/include/remote_prov/remote_prov_utils.h
index b02d273..406b7a9 100644
--- a/security/keymint/support/include/remote_prov/remote_prov_utils.h
+++ b/security/keymint/support/include/remote_prov/remote_prov_utils.h
@@ -87,4 +87,26 @@
*/
ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc);
+struct JsonOutput {
+ static JsonOutput Ok(std::string json) { return {std::move(json), ""}; }
+ static JsonOutput Error(std::string error) { return {"", std::move(error)}; }
+
+ std::string output;
+ std::string error; // if non-empty, this describes what went wrong
+};
+
+/**
+ * Take a given certificate request and output a JSON blob containing both the
+ * build fingerprint and certificate request. This data may be serialized, then
+ * later uploaded to the remote provisioning service. The input csr is not
+ * validated, only encoded.
+ *
+ * Output format:
+ * {
+ * "build_fingerprint": <string>
+ * "csr": <base64 CBOR CSR>
+ * }
+ */
+JsonOutput jsonEncodeCsrWithBuild(const cppbor::Array& csr);
+
} // namespace aidl::android::hardware::security::keymint::remote_prov
diff --git a/security/keymint/support/remote_prov_utils.cpp b/security/keymint/support/remote_prov_utils.cpp
index 982a1eb..0cbee51 100644
--- a/security/keymint/support/remote_prov_utils.cpp
+++ b/security/keymint/support/remote_prov_utils.cpp
@@ -14,13 +14,15 @@
* limitations under the License.
*/
+#include <iterator>
#include <tuple>
-#include <remote_prov/remote_prov_utils.h>
-
-#include <openssl/rand.h>
-
+#include <android-base/properties.h>
#include <cppbor.h>
+#include <json/json.h>
+#include <openssl/base64.h>
+#include <openssl/rand.h>
+#include <remote_prov/remote_prov_utils.h>
namespace aidl::android::hardware::security::keymint::remote_prov {
@@ -180,4 +182,36 @@
return result;
}
+JsonOutput jsonEncodeCsrWithBuild(const cppbor::Array& csr) {
+ const std::string kFingerprintProp = "ro.build.fingerprint";
+
+ if (!::android::base::WaitForPropertyCreation(kFingerprintProp)) {
+ return JsonOutput::Error("Unable to read build fingerprint");
+ }
+
+ bytevec csrCbor = csr.encode();
+ size_t base64Length;
+ int rc = EVP_EncodedLength(&base64Length, csrCbor.size());
+ if (!rc) {
+ return JsonOutput::Error("Error getting base64 length. Size overflow?");
+ }
+
+ std::vector<char> base64(base64Length);
+ rc = EVP_EncodeBlock(reinterpret_cast<uint8_t*>(base64.data()), csrCbor.data(), csrCbor.size());
+ ++rc; // Account for NUL, which BoringSSL does not for some reason.
+ if (rc != base64Length) {
+ return JsonOutput::Error("Error writing base64. Expected " + std::to_string(base64Length) +
+ " bytes to be written, but " + std::to_string(rc) +
+ " bytes were actually written.");
+ }
+
+ Json::Value json(Json::objectValue);
+ json["build_fingerprint"] = ::android::base::GetProperty(kFingerprintProp, /*default=*/"");
+ json["csr"] = base64.data(); // Boring writes a NUL-terminated c-string
+
+ Json::StreamWriterBuilder factory;
+ factory["indentation"] = ""; // disable pretty formatting
+ return JsonOutput::Ok(Json::writeString(factory, json));
+}
+
} // namespace aidl::android::hardware::security::keymint::remote_prov
diff --git a/security/keymint/support/remote_prov_utils_test.cpp b/security/keymint/support/remote_prov_utils_test.cpp
index c360c06..8697c51 100644
--- a/security/keymint/support/remote_prov_utils_test.cpp
+++ b/security/keymint/support/remote_prov_utils_test.cpp
@@ -14,6 +14,7 @@
* limitations under the License.
*/
+#include <android-base/properties.h>
#include <cppbor_parse.h>
#include <gmock/gmock.h>
#include <gtest/gtest.h>
@@ -23,6 +24,7 @@
#include <openssl/curve25519.h>
#include <remote_prov/remote_prov_utils.h>
#include <cstdint>
+#include "cppbor.h"
#include "keymaster/cppcose/cppcose.h"
namespace aidl::android::hardware::security::keymint::remote_prov {
@@ -80,5 +82,20 @@
EXPECT_THAT(eekPub, ElementsAreArray(geek->getBstrValue(CoseKey::PUBKEY_X).value_or(empty)));
}
+TEST(RemoteProvUtilsTest, JsonEncodeCsr) {
+ cppbor::Array array;
+ array.add(1);
+
+ auto [json, error] = jsonEncodeCsrWithBuild(array);
+
+ ASSERT_TRUE(error.empty()) << error;
+
+ std::string expected = R"({"build_fingerprint":")" +
+ ::android::base::GetProperty("ro.build.fingerprint", /*default=*/"") +
+ R"(","csr":"gQE="})";
+
+ ASSERT_EQ(json, expected);
+}
+
} // namespace
} // namespace aidl::android::hardware::security::keymint::remote_prov