mirror of
https://github.com/Evolution-X/hardware_interfaces
synced 2026-02-01 22:04:26 +00:00
81880284af
This change modifies the VTS tests to validate the structure of the CBOR Web Token (CWT) which contains the public key as one of several fields in the map. It only validates the subset of fields expected to be seen in the VTS tests. The ones related to the actual BCC will not be present in test mode due to the security guarantees of the interface. Additionally, the test will also now check that the first key in the BCC array matches the public key that should be self-signed in the certificate located in the second index of the BCC array. Test: atest VtsHalRemotelyProvisionedComponentTargetTest Change-Id: I9e7769861529b8095d77ce8fee3c78222579d38c
243 lines
10 KiB
C++
243 lines
10 KiB
C++
/*
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* Copyright (c) 2019, The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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#include <iterator>
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#include <tuple>
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#include <android-base/properties.h>
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#include <cppbor.h>
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#include <json/json.h>
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#include <openssl/base64.h>
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#include <openssl/rand.h>
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#include <remote_prov/remote_prov_utils.h>
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namespace aidl::android::hardware::security::keymint::remote_prov {
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constexpr uint32_t kBccPayloadIssuer = 1;
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constexpr uint32_t kBccPayloadSubject = 2;
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constexpr int32_t kBccPayloadSubjPubKey = -4670552;
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constexpr int32_t kBccPayloadKeyUsage = -4670553;
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bytevec kTestMacKey(32 /* count */, 0 /* byte value */);
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bytevec randomBytes(size_t numBytes) {
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bytevec retval(numBytes);
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RAND_bytes(retval.data(), numBytes);
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return retval;
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}
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ErrMsgOr<EekChain> generateEekChain(size_t length, const bytevec& eekId) {
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if (length < 2) {
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return "EEK chain must contain at least 2 certs.";
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}
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auto eekChain = cppbor::Array();
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bytevec prev_priv_key;
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for (size_t i = 0; i < length - 1; ++i) {
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bytevec pub_key(ED25519_PUBLIC_KEY_LEN);
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bytevec priv_key(ED25519_PRIVATE_KEY_LEN);
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ED25519_keypair(pub_key.data(), priv_key.data());
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// The first signing key is self-signed.
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if (prev_priv_key.empty()) prev_priv_key = priv_key;
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auto coseSign1 = constructCoseSign1(prev_priv_key,
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cppbor::Map() /* payload CoseKey */
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.add(CoseKey::KEY_TYPE, OCTET_KEY_PAIR)
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.add(CoseKey::ALGORITHM, EDDSA)
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.add(CoseKey::CURVE, ED25519)
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.add(CoseKey::PUBKEY_X, pub_key)
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.canonicalize()
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.encode(),
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{} /* AAD */);
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if (!coseSign1) return coseSign1.moveMessage();
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eekChain.add(coseSign1.moveValue());
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prev_priv_key = priv_key;
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}
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bytevec pub_key(X25519_PUBLIC_VALUE_LEN);
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bytevec priv_key(X25519_PRIVATE_KEY_LEN);
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X25519_keypair(pub_key.data(), priv_key.data());
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auto coseSign1 = constructCoseSign1(prev_priv_key,
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cppbor::Map() /* payload CoseKey */
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.add(CoseKey::KEY_TYPE, OCTET_KEY_PAIR)
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.add(CoseKey::KEY_ID, eekId)
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.add(CoseKey::ALGORITHM, ECDH_ES_HKDF_256)
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.add(CoseKey::CURVE, cppcose::X25519)
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.add(CoseKey::PUBKEY_X, pub_key)
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.canonicalize()
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.encode(),
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{} /* AAD */);
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if (!coseSign1) return coseSign1.moveMessage();
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eekChain.add(coseSign1.moveValue());
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return EekChain{eekChain.encode(), pub_key, priv_key};
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}
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bytevec getProdEekChain() {
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bytevec prodEek;
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prodEek.reserve(1 + sizeof(kCoseEncodedRootCert) + sizeof(kCoseEncodedGeekCert));
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// In CBOR encoding, 0x82 indicates an array of two items
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prodEek.push_back(0x82);
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prodEek.insert(prodEek.end(), std::begin(kCoseEncodedRootCert), std::end(kCoseEncodedRootCert));
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prodEek.insert(prodEek.end(), std::begin(kCoseEncodedGeekCert), std::end(kCoseEncodedGeekCert));
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return prodEek;
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}
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ErrMsgOr<bytevec> validatePayloadAndFetchPubKey(const cppbor::Map* payload) {
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const auto& issuer = payload->get(kBccPayloadIssuer);
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if (!issuer || !issuer->asTstr()) return "Issuer is not present or not a tstr.";
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const auto& subject = payload->get(kBccPayloadSubject);
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if (!subject || !subject->asTstr()) return "Subject is not present or not a tstr.";
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const auto& keyUsage = payload->get(kBccPayloadKeyUsage);
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if (!keyUsage || !keyUsage->asBstr()) return "Key usage is not present or not a bstr.";
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const auto& serializedKey = payload->get(kBccPayloadSubjPubKey);
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if (!serializedKey || !serializedKey->asBstr()) return "Key is not present or not a bstr.";
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return serializedKey->asBstr()->value();
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}
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ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(const cppbor::Array* coseSign1,
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const bytevec& signingCoseKey, const bytevec& aad) {
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if (!coseSign1 || coseSign1->size() != kCoseSign1EntryCount) {
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return "Invalid COSE_Sign1";
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}
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const cppbor::Bstr* protectedParams = coseSign1->get(kCoseSign1ProtectedParams)->asBstr();
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const cppbor::Map* unprotectedParams = coseSign1->get(kCoseSign1UnprotectedParams)->asMap();
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const cppbor::Bstr* payload = coseSign1->get(kCoseSign1Payload)->asBstr();
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const cppbor::Bstr* signature = coseSign1->get(kCoseSign1Signature)->asBstr();
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if (!protectedParams || !unprotectedParams || !payload || !signature) {
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return "Invalid COSE_Sign1";
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}
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auto [parsedProtParams, _, errMsg] = cppbor::parse(protectedParams);
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if (!parsedProtParams) {
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return errMsg + " when parsing protected params.";
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}
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if (!parsedProtParams->asMap()) {
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return "Protected params must be a map";
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}
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auto& algorithm = parsedProtParams->asMap()->get(ALGORITHM);
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if (!algorithm || !algorithm->asInt() || algorithm->asInt()->value() != EDDSA) {
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return "Unsupported signature algorithm";
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}
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auto [parsedPayload, __, payloadErrMsg] = cppbor::parse(payload);
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if (!parsedPayload) return payloadErrMsg + " when parsing key";
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if (!parsedPayload->asMap()) return "CWT must be a map";
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auto serializedKey = validatePayloadAndFetchPubKey(parsedPayload->asMap());
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if (!serializedKey) {
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return "CWT validation failed: " + serializedKey.moveMessage();
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}
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bool selfSigned = signingCoseKey.empty();
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auto key = CoseKey::parseEd25519(selfSigned ? *serializedKey : signingCoseKey);
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if (!key) return "Bad signing key: " + key.moveMessage();
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bytevec signatureInput =
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cppbor::Array().add("Signature1").add(*protectedParams).add(aad).add(*payload).encode();
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if (!ED25519_verify(signatureInput.data(), signatureInput.size(), signature->value().data(),
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key->getBstrValue(CoseKey::PUBKEY_X)->data())) {
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return "Signature verification failed";
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}
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return serializedKey.moveValue();
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}
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ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
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if (!bcc || bcc->size() == 0) return "Invalid BCC";
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std::vector<BccEntryData> result;
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const auto& devicePubKey = bcc->get(0);
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if (!devicePubKey->asMap()) return "Invalid device public key at the 1st entry in the BCC";
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bytevec prevKey;
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for (size_t i = 1; i < bcc->size(); ++i) {
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const cppbor::Array* entry = bcc->get(i)->asArray();
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if (!entry || entry->size() != kCoseSign1EntryCount) {
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return "Invalid BCC entry " + std::to_string(i) + ": " + prettyPrint(entry);
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}
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auto payload = verifyAndParseCoseSign1Cwt(entry, std::move(prevKey), bytevec{} /* AAD */);
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if (!payload) {
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return "Failed to verify entry " + std::to_string(i) + ": " + payload.moveMessage();
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}
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auto& certProtParms = entry->get(kCoseSign1ProtectedParams);
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if (!certProtParms || !certProtParms->asBstr()) return "Invalid prot params";
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auto [parsedProtParms, _, errMsg] = cppbor::parse(certProtParms->asBstr()->value());
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if (!parsedProtParms || !parsedProtParms->asMap()) return "Invalid prot params";
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result.push_back(BccEntryData{*payload});
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// This entry's public key is the signing key for the next entry.
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prevKey = payload.moveValue();
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if (i == 1) {
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auto [parsedRootKey, _, errMsg] = cppbor::parse(prevKey);
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if (!parsedRootKey || !parsedRootKey->asMap()) return "Invalid payload entry in BCC.";
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if (*parsedRootKey != *devicePubKey) {
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return "Device public key doesn't match BCC root.";
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}
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}
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}
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return result;
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}
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JsonOutput jsonEncodeCsrWithBuild(const cppbor::Array& csr) {
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const std::string kFingerprintProp = "ro.build.fingerprint";
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if (!::android::base::WaitForPropertyCreation(kFingerprintProp)) {
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return JsonOutput::Error("Unable to read build fingerprint");
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}
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bytevec csrCbor = csr.encode();
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size_t base64Length;
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int rc = EVP_EncodedLength(&base64Length, csrCbor.size());
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if (!rc) {
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return JsonOutput::Error("Error getting base64 length. Size overflow?");
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}
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std::vector<char> base64(base64Length);
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rc = EVP_EncodeBlock(reinterpret_cast<uint8_t*>(base64.data()), csrCbor.data(), csrCbor.size());
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++rc; // Account for NUL, which BoringSSL does not for some reason.
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if (rc != base64Length) {
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return JsonOutput::Error("Error writing base64. Expected " + std::to_string(base64Length) +
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" bytes to be written, but " + std::to_string(rc) +
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" bytes were actually written.");
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}
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Json::Value json(Json::objectValue);
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json["build_fingerprint"] = ::android::base::GetProperty(kFingerprintProp, /*default=*/"");
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json["csr"] = base64.data(); // Boring writes a NUL-terminated c-string
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Json::StreamWriterBuilder factory;
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factory["indentation"] = ""; // disable pretty formatting
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return JsonOutput::Ok(Json::writeString(factory, json));
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}
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} // namespace aidl::android::hardware::security::keymint::remote_prov
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