decrypt: AOSP 10 requires the use of fscrypt
fscrypt aosp doc: https://source.android.com/security/encryption/file-based
kernel fscrypt doc: https://www.kernel.org/doc/html/v4.18/filesystems/fscrypt.html
This commit implements the ability for TWRP to use fscrypt to decrypt
files on the fscrypt implementation. It has been implemented mostly
in a new successor library to e4crypt called libtwrpfscrypt. Most of the
code was ported from AOSP vold.
Notable updates include:
- updated policy storage by libtar
- lookup of fbe policies by libtwrpfscrypt
- threaded keystore operations
Big thanks to Dees_Troy for the initial trailblazing
of encryption in TWRP.
Change-Id: I69cd2eba3693a9914e00213d4943229635d0cdae
diff --git a/crypto/fscrypt/Weaver1.h b/crypto/fscrypt/Weaver1.h
new file mode 100644
index 0000000..22f401e
--- /dev/null
+++ b/crypto/fscrypt/Weaver1.h
@@ -0,0 +1,64 @@
+/*
+ * Copyright (C) 2017 Team Win Recovery Project
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+/* To the best of my knowledge there is no native implementation for
+ * Weaver so I made this by looking at the IWeaver.h file that gets
+ * compiled by the build system. I took the information from this header
+ * file and looked at keymaster source to get an idea of the proper way
+ * to write the functions.
+ */
+
+#ifndef TWRP_WEAVER_H
+#define TWRP_WEAVER_H
+
+#include <memory>
+#include <string>
+#include <utility>
+
+#include <android/hardware/weaver/1.0/IWeaver.h>
+#include "Utils.h"
+
+namespace android {
+namespace vold {
+using ::android::hardware::weaver::V1_0::IWeaver;
+
+// Wrapper for a Weaver device
+class Weaver {
+ public:
+ Weaver();
+ // false if we failed to open the weaver device.
+ explicit operator bool() { return mDevice.get() != nullptr; }
+
+ bool GetSlots(uint32_t* slots);
+ bool GetKeySize(uint32_t* keySize);
+ bool GetValueSize(uint32_t* valueSize);
+ // TODO: we should return more information about the status including time delays before the next retry
+ bool WeaverVerify(const uint32_t slot, const void* weaver_key, std::vector<uint8_t>* payload);
+
+ private:
+ sp<hardware::weaver::V1_0::IWeaver> mDevice;
+ hardware::weaver::V1_0::WeaverConfig config;
+ bool GottenConfig;
+
+ bool GetConfig();
+
+ DISALLOW_COPY_AND_ASSIGN(Weaver);
+};
+
+} // namespace vold
+} // namespace android
+
+#endif