KeyStore: use security level to chose keymaster device
Keymaster4 introduces security levels. Android devices
may have multiple keymaster implementations, one for each
possible security level, where the presence of a strong
security level implies the presence of all lower levels.
This patch adds code that enumerates all keymaster device
implementations available from ServiceManager and populates
Keystore's keymaster device database with at most one keymaster
implementation per security level. It gives precedence to
newer versions if multiple implementations exist for the same security
level.
The security level is chosen by a set of flags passed to the keystore
operations generate, import, addRngEntropy.
For existing keys the right security level is chosen by the blob flags.
To that end a new flag KEYSTORE_FLAG_STRONGBOX was added, and the
security level is expressed through a combination of
KEYSTORE_FLAG_FALLBACK (F) and KEYSTORE_FLAG_STRONGBOX (S).
Encoding is as follows:
F S
Software 1 X (don't care)
TEE 0 0
Strongbox 0 1
Some operations in keystore cli2 where amended with the optional
--seclevel flags. Allowing the user to chose the security level for the
given operation. Possible options are "software", "strongbox", and "tee"
where tee is the default value.
Test: Existing KeyStore CTS tests run
Change-Id: I01ef238f5e7067e480cf9b171630237236046bb1
diff --git a/keystore/blob.h b/keystore/blob.h
index 5335037..665e07a 100644
--- a/keystore/blob.h
+++ b/keystore/blob.h
@@ -22,6 +22,7 @@
#include <openssl/aes.h>
#include <openssl/md5.h>
+#include <keystore/keymaster_types.h>
#include <keystore/keystore.h>
constexpr size_t kValueSize = 32768;
@@ -117,6 +118,9 @@
BlobType getType() const { return BlobType(mBlob.type); }
void setType(BlobType type) { mBlob.type = uint8_t(type); }
+ keystore::SecurityLevel getSecurityLevel() const;
+ void setSecurityLevel(keystore::SecurityLevel);
+
ResponseCode writeBlob(const std::string& filename, const uint8_t* aes_key, State state,
Entropy* entropy);
ResponseCode readBlob(const std::string& filename, const uint8_t* aes_key, State state);