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Commit 52d01598 authored by Max Bires's avatar Max Bires Committed by Automerger Merge Worker
Browse files

Include the CWT validation in VTS testing. am: b326f33f 

Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/2962595



Change-Id: I2e337aa9985e21b3bdd02f1d32dd6cde7fd501a3
Signed-off-by: default avatarAutomerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>
parents bd701ebc b326f33f

security/keymint/support/remote_prov_utils.cpp

+34 −9
Original line number Diff line number Diff line
@@ -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;