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Ethan Yonkere9afc3d2018-08-30 15:16:27 -05001/*
2 * Copyright (C) 2016 The Android Open Source Project
3 *
4 * Licensed under the Apache License, Version 2.0 (the "License");
5 * you may not use this file except in compliance with the License.
6 * You may obtain a copy of the License at
7 *
8 * http://www.apache.org/licenses/LICENSE-2.0
9 *
10 * Unless required by applicable law or agreed to in writing, software
11 * distributed under the License is distributed on an "AS IS" BASIS,
12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13 * See the License for the specific language governing permissions and
14 * limitations under the License.
15 */
16
17#ifndef ANDROID_TWRP_KEYMASTER_H
18#define ANDROID_TWRP_KEYMASTER_H
19
20#include "KeyBuffer.h"
21
22#include <memory>
23#include <string>
24#include <utility>
25
26#include <android-base/macros.h>
27#include <keymasterV4_0/Keymaster.h>
28#include <keymasterV4_0/authorization_set.h>
29
30namespace android {
31namespace vold {
32
33namespace km = ::android::hardware::keymaster::V4_0;
34using KmDevice = km::support::Keymaster;
35
36// C++ wrappers to the Keymaster hidl interface.
37// This is tailored to the needs of KeyStorage, but could be extended to be
38// a more general interface.
39
40// Wrapper for a Keymaster operation handle representing an
41// ongoing Keymaster operation. Aborts the operation
42// in the destructor if it is unfinished. Methods log failures
43// to LOG(ERROR).
44class KeymasterOperation {
45 public:
46 ~KeymasterOperation();
47 // Is this instance valid? This is false if creation fails, and becomes
48 // false on finish or if an update fails.
49 explicit operator bool() { return mError == km::ErrorCode::OK; }
50 km::ErrorCode errorCode() { return mError; }
51 // Call "update" repeatedly until all of the input is consumed, and
52 // concatenate the output. Return true on success.
53 template <class TI, class TO>
54 bool updateCompletely(TI& input, TO* output) {
55 if (output) output->clear();
56 return updateCompletely(input.data(), input.size(), [&](const char* b, size_t n) {
57 if (output) std::copy(b, b + n, std::back_inserter(*output));
58 });
59 }
60
61 // Finish and write the output to this string, unless pointer is null.
62 bool finish(std::string* output);
63 // Move constructor
64 KeymasterOperation(KeymasterOperation&& rhs) { *this = std::move(rhs); }
65 // Construct an object in an error state for error returns
66 KeymasterOperation() : mDevice{nullptr}, mOpHandle{0}, mError{km::ErrorCode::UNKNOWN_ERROR} {}
67 // Move Assignment
68 KeymasterOperation& operator=(KeymasterOperation&& rhs) {
69 mDevice = rhs.mDevice;
70 rhs.mDevice = nullptr;
71
72 mOpHandle = rhs.mOpHandle;
73 rhs.mOpHandle = 0;
74
75 mError = rhs.mError;
76 rhs.mError = km::ErrorCode::UNKNOWN_ERROR;
77
78 return *this;
79 }
80
81 private:
82 KeymasterOperation(KmDevice* d, uint64_t h)
83 : mDevice{d}, mOpHandle{h}, mError{km::ErrorCode::OK} {}
84 KeymasterOperation(km::ErrorCode error) : mDevice{nullptr}, mOpHandle{0}, mError{error} {}
85
86 bool updateCompletely(const char* input, size_t inputLen,
87 const std::function<void(const char*, size_t)> consumer);
88
89 KmDevice* mDevice;
90 uint64_t mOpHandle;
91 km::ErrorCode mError;
92 DISALLOW_COPY_AND_ASSIGN(KeymasterOperation);
93 friend class Keymaster;
94};
95
96// Wrapper for a Keymaster device for methods that start a KeymasterOperation or are not
97// part of one.
98class Keymaster {
99 public:
100 Keymaster();
101 // false if we failed to open the keymaster device.
102 explicit operator bool() { return mDevice.get() != nullptr; }
103 // Generate a key in the keymaster from the given params.
104 bool generateKey(const km::AuthorizationSet& inParams, std::string* key);
105 // If the keymaster supports it, permanently delete a key.
106 bool deleteKey(const std::string& key);
107 // Replace stored key blob in response to KM_ERROR_KEY_REQUIRES_UPGRADE.
108 bool upgradeKey(const std::string& oldKey, const km::AuthorizationSet& inParams,
109 std::string* newKey);
110 // Begin a new cryptographic operation, collecting output parameters if pointer is non-null
111 KeymasterOperation begin(km::KeyPurpose purpose, const std::string& key,
112 const km::AuthorizationSet& inParams,
113 const km::HardwareAuthToken& authToken,
114 km::AuthorizationSet* outParams);
115 bool isSecure();
116
117 private:
118 std::unique_ptr<KmDevice> mDevice;
119 DISALLOW_COPY_AND_ASSIGN(Keymaster);
120 static bool hmacKeyGenerated;
121};
122
123} // namespace vold
124} // namespace android
125
126// FIXME no longer needed now cryptfs is in C++.
127
128/*
129 * The following functions provide C bindings to keymaster services
130 * needed by cryptfs scrypt. The compatibility check checks whether
131 * the keymaster implementation is considered secure, i.e., TEE backed.
132 * The create_key function generates an RSA key for signing.
133 * The sign_object function signes an object with the given keymaster
134 * key.
135 */
136
137/* Return values for keymaster_sign_object_for_cryptfs_scrypt */
138
139enum class KeymasterSignResult {
140 ok = 0,
141 error = -1,
142 upgrade = -2,
143};
144
Ethan Yonker98661c12018-10-17 08:39:28 -0500145//int keymaster_compatibility_cryptfs_scrypt();
146/*int keymaster_create_key_for_cryptfs_scrypt(uint32_t rsa_key_size, uint64_t rsa_exponent,
Ethan Yonkere9afc3d2018-08-30 15:16:27 -0500147 uint32_t ratelimit, uint8_t* key_buffer,
Ethan Yonker98661c12018-10-17 08:39:28 -0500148 uint32_t key_buffer_size, uint32_t* key_out_size);*/
Ethan Yonkere9afc3d2018-08-30 15:16:27 -0500149
150int keymaster_upgrade_key_for_cryptfs_scrypt(uint32_t rsa_key_size, uint64_t rsa_exponent,
151 uint32_t ratelimit, const uint8_t* key_blob,
152 size_t key_blob_size, uint8_t* key_buffer,
153 uint32_t key_buffer_size, uint32_t* key_out_size);
154
155KeymasterSignResult keymaster_sign_object_for_cryptfs_scrypt(
156 const uint8_t* key_blob, size_t key_blob_size, uint32_t ratelimit, const uint8_t* object,
157 const size_t object_size, uint8_t** signature_buffer, size_t* signature_buffer_size);
158
159#endif