Merge "Include the CWT validation in VTS testing." am: 608099fd88 am: 769c2bf958
Original change: https://android-review.googlesource.com/c/platform/hardware/interfaces/+/1965500
Change-Id: Ifcfe72ac6c82f30bee36c886cae1e696a84ea67f
diff --git a/security/keymint/support/remote_prov_utils.cpp b/security/keymint/support/remote_prov_utils.cpp
index 0cbee51..35cb891 100644
--- a/security/keymint/support/remote_prov_utils.cpp
+++ b/security/keymint/support/remote_prov_utils.cpp
@@ -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 @@
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 @@
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 @@
return "Signature verification failed";
}
- return serializedKey->asBstr()->value();
+ return serializedKey.moveValue();
}
ErrMsgOr<std::vector<BccEntryData>> validateBcc(const cppbor::Array* bcc) {
@@ -156,8 +171,11 @@
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 @@
// 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;