Add more EEK variant tests and related fixes

 - Test with deliberately-invalid EEK in request:
    - corrupt signature
    - missing initial self-signed cert
 - Test with different sizes of EEK chain.

These tests will only really take effect when we have a valid GEEK to
test with.

Other changes:
 - Fix encoding of KeyUsage bitset.
 - Add a made-up allowed-root pubkey for prod mode. This needs to be
   replaced with the real GEEK when available.
 - Fix generateEek() so that the first private key isn't used for
   all signing operations.

Test: VtsHalRemotelyProvisionedComponentTargetTest
Change-Id: I833894d33cd1757b7a0cfcf18f79b61e4e56a556

1 files changed, 17 insertions, 2 deletions

diff --git a/security/keymint/aidl/default/RemotelyProvisionedComponent.cpp b/security/keymint/aidl/default/RemotelyProvisionedComponent.cpp
index 4dbaa05d54..ca06abc48e 100644
--- a/security/keymint/aidl/default/RemotelyProvisionedComponent.cpp
+++ b/security/keymint/aidl/default/RemotelyProvisionedComponent.cpp
@@ -46,6 +46,14 @@ using namespace keymaster;
 
 namespace {
 
+// Hard-coded set of acceptable public keys that can act as roots of EEK chains.
+inline const vector<bytevec> kAuthorizedEekRoots = {
+        // TODO(drysdale): replace this random value with real root pubkey(s).
+        {0x5c, 0xea, 0x4b, 0xd2, 0x31, 0x27, 0x15, 0x5e, 0x62, 0x94, 0x70,
+         0x53, 0x94, 0x43, 0x0f, 0x9a, 0x89, 0xd5, 0xc5, 0x0f, 0x82, 0x9b,
+         0xcd, 0x10, 0xe0, 0x79, 0xef, 0xf3, 0xfa, 0x40, 0xeb, 0x0a},
+};
+
 constexpr auto STATUS_FAILED = RemotelyProvisionedComponent::STATUS_FAILED;
 constexpr auto STATUS_INVALID_EEK = RemotelyProvisionedComponent::STATUS_INVALID_EEK;
 constexpr auto STATUS_INVALID_MAC = RemotelyProvisionedComponent::STATUS_INVALID_MAC;
@@ -135,6 +143,13 @@ StatusOr<std::pair<bytevec /* EEK pub */, bytevec /* EEK ID */>> validateAndExtr
                           "Failed to validate EEK chain: " + cosePubKey.moveMessage());
         }
         lastPubKey = *std::move(cosePubKey);
+
+        // In prod mode the first pubkey should match a well-known Google public key.
+        if (!testMode && i == 0 &&
+            std::find(kAuthorizedEekRoots.begin(), kAuthorizedEekRoots.end(), lastPubKey) ==
+                    kAuthorizedEekRoots.end()) {
+            return Status(STATUS_INVALID_EEK, "Unrecognized root of EEK chain");
+        }
     }
 
     auto eek = CoseKey::parseX25519(lastPubKey, true /* requireKid */);
@@ -417,8 +432,8 @@ RemotelyProvisionedComponent::generateBcc() {
                                 .add(1 /* Issuer */, "Issuer")
                                 .add(2 /* Subject */, "Subject")
                                 .add(-4670552 /* Subject Pub Key */, coseKey)
-                                .add(-4670553 /* Key Usage */,
-                                     std::vector<uint8_t>(0x05) /* Big endian order */)
+                                .add(-4670553 /* Key Usage (little-endian order) */,
+                                     std::vector<uint8_t>{0x20} /* keyCertSign = 1<<5 */)
                                 .canonicalize()
                                 .encode();
     auto coseSign1 = constructCoseSign1(privKey,       /* signing key */