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Merge "Include the CWT validation in VTS testing." am: 608099fd88

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Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1965500

Change-Id: I33b1326c643c262d3ac09a245e8d959b81347fa7
This commit is contained in:
Treehugger Robot 2022-02-02 02:27:46 +00:00 committed by Automerger Merge Worker
commit 769c2bf958
1 changed files with 34 additions and 9 deletions
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43
security/keymint/support/remote_prov_utils.cpp
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@ -26,6 +26,11 @@
namespace aidl::android::hardware::security::keymint::remote_prov {
constexpr uint32_t kBccPayloadIssuer = 1;
constexpr uint32_t kBccPayloadSubject = 2;
constexpr int32_t kBccPayloadSubjPubKey = -4670552;
constexpr int32_t kBccPayloadKeyUsage = -4670553;
bytevec kTestMacKey(32 /* count */, 0 /* byte value */);
bytevec randomBytes(size_t numBytes) {
@ -98,6 +103,18 @@ bytevec getProdEekChain() {
return prodEek;
}
ErrMsgOr<bytevec> validatePayloadAndFetchPubKey(const cppbor::Map* payload) {
const auto& issuer = payload->get(kBccPayloadIssuer);
if (!issuer || !issuer->asTstr()) return "Issuer is not present or not a tstr.";
const auto& subject = payload->get(kBccPayloadSubject);
if (!subject || !subject->asTstr()) return "Subject is not present or not a tstr.";
const auto& keyUsage = payload->get(kBccPayloadKeyUsage);
if (!keyUsage || !keyUsage->asBstr()) return "Key usage is not present or not a bstr.";
const auto& serializedKey = payload->get(kBccPayloadSubjPubKey);
if (!serializedKey || !serializedKey->asBstr()) return "Key is not present or not a bstr.";
return serializedKey->asBstr()->value();
}
ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(const cppbor::Array* coseSign1,
const bytevec& signingCoseKey, const bytevec& aad) {
if (!coseSign1 || coseSign1->size() != kCoseSign1EntryCount) {
@ -126,18 +143,16 @@ ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(const cppbor::Array* coseSign1,
return "Unsupported signature algorithm";
}
// TODO(jbires): Handle CWTs as the CoseSign1 payload in a less hacky way. Since the CWT payload
// is extremely remote provisioning specific, probably just make a separate
// function there.
auto [parsedPayload, __, payloadErrMsg] = cppbor::parse(payload);
if (!parsedPayload) return payloadErrMsg + " when parsing key";
if (!parsedPayload->asMap()) return "CWT must be a map";
auto serializedKey = parsedPayload->asMap()->get(-4670552)->clone();
if (!serializedKey || !serializedKey->asBstr()) return "Could not find key entry";
auto serializedKey = validatePayloadAndFetchPubKey(parsedPayload->asMap());
if (!serializedKey) {
return "CWT validation failed: " + serializedKey.moveMessage();
}
bool selfSigned = signingCoseKey.empty();
auto key =
CoseKey::parseEd25519(selfSigned ? serializedKey->asBstr()->value() : signingCoseKey);
auto key = CoseKey::parseEd25519(selfSigned ? *serializedKey : signingCoseKey);
if (!key) return "Bad signing key: " + key.moveMessage();
bytevec signatureInput =
@ -148,7 +163,7 @@ ErrMsgOr<bytevec> verifyAndParseCoseSign1Cwt(const cppbor::Array* coseSign1,
return "Signature verification failed";
}
return serializedKey->asBstr()->value();
return serializedKey.moveValue();
}
ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
@ -156,8 +171,11 @@ ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
std::vector<BccEntryData> result;
const auto& devicePubKey = bcc->get(0);
if (!devicePubKey->asMap()) return "Invalid device public key at the 1st entry in the BCC";
bytevec prevKey;
// TODO(jbires): Actually process the pubKey at the start of the new bcc entry
for (size_t i = 1; i < bcc->size(); ++i) {
const cppbor::Array* entry = bcc->get(i)->asArray();
if (!entry || entry->size() != kCoseSign1EntryCount) {
@ -177,6 +195,13 @@ ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
// This entry's public key is the signing key for the next entry.
prevKey = payload.moveValue();
if (i == 1) {
auto [parsedRootKey, _, errMsg] = cppbor::parse(prevKey);
if (!parsedRootKey || !parsedRootKey->asMap()) return "Invalid payload entry in BCC.";
if (*parsedRootKey != *devicePubKey) {
return "Device public key doesn't match BCC root.";
}
}
}
return result;