platform_system_vold/Keymaster.h
Paul Crowley 0572080814 Password security for FBE disk encryption keys
Added a new call change_user_key which changes the way that disk
encryption keys are protected; a key can now be protected with a
combination of an auth token and a secret which is a hashed password.
Both of these are passed to unlock_user_key.

This change introduces a security bug, b/26948053, which must be fixed
before we ship.

Bug: 22950892
Change-Id: Iac1e45bb6f86f2af5c472c70a0fe3228b02115bf
2016-02-08 20:03:57 +00:00

111 lines
3.9 KiB
C++

/*
* Copyright (C) 2016 The Android Open Source 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.
*/
#ifndef ANDROID_VOLD_KEYMASTER1_H
#define ANDROID_VOLD_KEYMASTER1_H
#include <string>
#include <hardware/hardware.h>
#include <hardware/keymaster1.h>
#include <keymaster/authorization_set.h>
namespace android {
namespace vold {
using namespace keymaster;
// C++ wrappers to the keymaster1 C interface.
// This is tailored to the needs of KeyStorage, but could be extended to be
// a more general interface.
// Wrapper for a keymaster_operation_handle_t representing an
// ongoing Keymaster operation. Aborts the operation
// in the destructor if it is unfinished. Methods log failures
// to LOG(ERROR).
class KeymasterOperation {
public:
~KeymasterOperation() { if (mDevice) mDevice->abort(mDevice, mOpHandle); }
// Is this instance valid? This is false if creation fails, and becomes
// false on finish or if an update fails.
explicit operator bool() {return mDevice != nullptr;}
// Call "update" repeatedly until all of the input is consumed, and
// concatenate the output. Return true on success.
bool updateCompletely(const std::string &input, std::string &output);
// Finish; pass nullptr for the "output" param.
bool finish();
// Finish and write the output to this string.
bool finishWithOutput(std::string &output);
// Move constructor
KeymasterOperation(KeymasterOperation&& rhs) {
mOpHandle = rhs.mOpHandle;
mDevice = rhs.mDevice;
rhs.mDevice = nullptr;
}
private:
KeymasterOperation(keymaster1_device_t *d, keymaster_operation_handle_t h):
mDevice {d}, mOpHandle {h} {}
keymaster1_device_t *mDevice;
keymaster_operation_handle_t mOpHandle;
DISALLOW_COPY_AND_ASSIGN(KeymasterOperation);
friend class Keymaster;
};
// Wrapper for a keymaster1_device_t representing an open connection
// to the keymaster, which is closed in the destructor.
class Keymaster {
public:
Keymaster();
~Keymaster() { if (mDevice) keymaster1_close(mDevice); }
// false if we failed to open the keymaster device.
explicit operator bool() {return mDevice != nullptr;}
// Generate a key in the keymaster from the given params.
bool generateKey(const AuthorizationSet &inParams, std::string &key);
// If the keymaster supports it, permanently delete a key.
bool deleteKey(const std::string &key);
// Begin a new cryptographic operation, collecting output parameters.
KeymasterOperation begin(
keymaster_purpose_t purpose,
const std::string &key,
const AuthorizationSet &inParams,
AuthorizationSet &outParams);
// Begin a new cryptographic operation; don't collect output parameters.
KeymasterOperation begin(
keymaster_purpose_t purpose,
const std::string &key,
const AuthorizationSet &inParams);
private:
keymaster1_device_t *mDevice;
DISALLOW_COPY_AND_ASSIGN(Keymaster);
};
template <keymaster_tag_t Tag>
inline AuthorizationSetBuilder& addStringParam(AuthorizationSetBuilder &&params,
TypedTag<KM_BYTES, Tag> tag, const std::string& val) {
return params.Authorization(tag, val.data(), val.size());
}
template <keymaster_tag_t Tag>
inline void addStringParam(AuthorizationSetBuilder &params,
TypedTag<KM_BYTES, Tag> tag, const std::string& val) {
params.Authorization(tag, val.data(), val.size());
}
} // namespace vold
} // namespace android
#endif