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1/*
2 * Copyright 2014 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 SYSTEM_KEYMASTER_ANDROID_KEYMASTER_UTILS_H_
18#define SYSTEM_KEYMASTER_ANDROID_KEYMASTER_UTILS_H_
19
20#include <stdint.h>
21#include <string.h>
22#include <time.h> // for time_t.
23
24#include <UniquePtr.h>
25
26#include <hardware/keymaster_defs.h>
27#include <keymaster/serializable.h>
28
29namespace keymaster {
30
31/**
32 * Convert the specified time value into "Java time", which is a signed 64-bit integer representing
33 * elapsed milliseconds since Jan 1, 1970.
34 */
35inline int64_t java_time(time_t time) {
36 // The exact meaning of a time_t value is implementation-dependent. If this code is ported to a
37 // platform that doesn't define it as "seconds since Jan 1, 1970 UTC", this function will have
38 // to be revised.
39 return time * 1000;
40}
41
42/*
43 * Array Manipulation functions. This set of templated inline functions provides some nice tools
44 * for operating on c-style arrays. C-style arrays actually do have a defined size associated with
45 * them, as long as they are not allowed to decay to a pointer. These template methods exploit this
46 * to allow size-based array operations without explicitly specifying the size. If passed a pointer
47 * rather than an array, they'll fail to compile.
48 */
49
50/**
51 * Return the size in bytes of the array \p a.
52 */
53template <typename T, size_t N> inline size_t array_size(const T(&a)[N]) {
54 return sizeof(a);
55}
56
57/**
58 * Return the number of elements in array \p a.
59 */
60template <typename T, size_t N> inline size_t array_length(const T(&)[N]) {
61 return N;
62}
63
64/**
65 * Duplicate the array \p a. The memory for the new array is allocated and the caller takes
66 * responsibility.
67 */
68template <typename T> inline T* dup_array(const T* a, size_t n) {
69 T* dup = new (std::nothrow) T[n];
70 if (dup)
71 for (size_t i = 0; i < n; ++i)
72 dup[i] = a[i];
73 return dup;
74}
75
76/**
77 * Duplicate the array \p a. The memory for the new array is allocated and the caller takes
78 * responsibility. Note that the dup is necessarily returned as a pointer, so size is lost. Call
79 * array_length() on the original array to discover the size.
80 */
81template <typename T, size_t N> inline T* dup_array(const T(&a)[N]) {
82 return dup_array(a, N);
83}
84
85/**
86 * Duplicate the buffer \p buf. The memory for the new buffer is allocated and the caller takes
87 * responsibility.
88 */
89uint8_t* dup_buffer(const void* buf, size_t size);
90
91/**
92 * Copy the contents of array \p arr to \p dest.
93 */
94template <typename T, size_t N> inline void copy_array(const T(&arr)[N], T* dest) {
95 for (size_t i = 0; i < N; ++i)
96 dest[i] = arr[i];
97}
98
99/**
100 * Search array \p a for value \p val, returning true if found. Note that this function is
101 * early-exit, meaning that it should not be used in contexts where timing analysis attacks could be
102 * a concern.
103 */
104template <typename T, size_t N> inline bool array_contains(const T(&a)[N], T val) {
105 for (size_t i = 0; i < N; ++i) {
106 if (a[i] == val) {
107 return true;
108 }
109 }
110 return false;
111}
112
113/**
114 * Variant of memset() that uses GCC-specific pragmas to disable optimizations, so effect is not
115 * optimized away. This is important because we often need to wipe blocks of sensitive data from
116 * memory. As an additional convenience, this implementation avoids writing to NULL pointers.
117 */
118#ifdef __clang__
119#define OPTNONE __attribute__((optnone))
120#else // not __clang__
121#define OPTNONE __attribute__((optimize("O0")))
122#endif // not __clang__
123inline OPTNONE void* memset_s(void* s, int c, size_t n) {
124 if (!s)
125 return s;
126 return memset(s, c, n);
127}
128#undef OPTNONE
129
130/**
131 * Variant of memcmp that has the same runtime regardless of whether the data matches (i.e. doesn't
132 * short-circuit). Not an exact equivalent to memcmp because it doesn't return <0 if p1 < p2, just
133 * 0 for match and non-zero for non-match.
134 */
135int memcmp_s(const void* p1, const void* p2, size_t length);
136
137/**
138 * Eraser clears buffers. Construct it with a buffer or object and the destructor will ensure that
139 * it is zeroed.
140 */
141class Eraser {
142 public:
143 /* Not implemented. If this gets used, we want a link error. */
144 template <typename T> explicit Eraser(T* t);
145
146 template <typename T>
147 explicit Eraser(T& t)
148 : buf_(reinterpret_cast<uint8_t*>(&t)), size_(sizeof(t)) {}
149
150 template <size_t N> explicit Eraser(uint8_t(&arr)[N]) : buf_(arr), size_(N) {}
151
152 Eraser(void* buf, size_t size) : buf_(static_cast<uint8_t*>(buf)), size_(size) {}
153 ~Eraser() { memset_s(buf_, 0, size_); }
154
155 private:
156 Eraser(const Eraser&);
157 void operator=(const Eraser&);
158
159 uint8_t* buf_;
160 size_t size_;
161};
162
163/**
164 * ArrayWrapper is a trivial wrapper around a C-style array that provides begin() and end()
165 * methods. This is primarily to facilitate range-based iteration on arrays. It does not copy, nor
166 * does it take ownership; it just holds pointers.
167 */
168template <typename T> class ArrayWrapper {
169 public:
170 ArrayWrapper(T* array, size_t size) : begin_(array), end_(array + size) {}
171
172 T* begin() { return begin_; }
173 T* end() { return end_; }
174
175 private:
176 T* begin_;
177 T* end_;
178};
179
180/**
181 * Convert any unsigned integer from network to host order. We implement this here rather than
182 * using the functions from arpa/inet.h because the TEE doesn't have inet.h. This isn't the most
183 * efficient implementation, but the compiler should unroll the loop and tighten it up.
184 */
185template <typename T> T ntoh(T t) {
186 const uint8_t* byte_ptr = reinterpret_cast<const uint8_t*>(&t);
187 T retval = 0;
188 for (size_t i = 0; i < sizeof(t); ++i) {
189 retval <<= 8;
190 retval |= byte_ptr[i];
191 }
192 return retval;
193}
194
195/**
196 * Convert any unsigned integer from host to network order. We implement this here rather than
197 * using the functions from arpa/inet.h because the TEE doesn't have inet.h. This isn't the most
198 * efficient implementation, but the compiler should unroll the loop and tighten it up.
199 */
200template <typename T> T hton(T t) {
201 T retval;
202 uint8_t* byte_ptr = reinterpret_cast<uint8_t*>(&retval);
203 for (size_t i = sizeof(t); i > 0; --i) {
204 byte_ptr[i - 1] = t & 0xFF;
205 t >>= 8;
206 }
207 return retval;
208}
209
210/**
211 * KeymasterKeyBlob is a very simple extension of the C struct keymaster_key_blob_t. It manages its
212 * own memory, which makes avoiding memory leaks much easier.
213 */
214struct KeymasterKeyBlob : public keymaster_key_blob_t {
215 KeymasterKeyBlob() {
216 key_material = nullptr;
217 key_material_size = 0;
218 }
219
220 KeymasterKeyBlob(const uint8_t* data, size_t size) {
221 key_material_size = 0;
222 key_material = dup_buffer(data, size);
223 if (key_material)
224 key_material_size = size;
225 }
226
227 explicit KeymasterKeyBlob(size_t size) {
228 key_material_size = 0;
229 key_material = new (std::nothrow) uint8_t[size];
230 if (key_material)
231 key_material_size = size;
232 }
233
234 explicit KeymasterKeyBlob(const keymaster_key_blob_t& blob) {
235 key_material_size = 0;
236 key_material = dup_buffer(blob.key_material, blob.key_material_size);
237 if (key_material)
238 key_material_size = blob.key_material_size;
239 }
240
241 KeymasterKeyBlob(const KeymasterKeyBlob& blob) {
242 key_material_size = 0;
243 key_material = dup_buffer(blob.key_material, blob.key_material_size);
244 if (key_material)
245 key_material_size = blob.key_material_size;
246 }
247
248 void operator=(const KeymasterKeyBlob& blob) {
249 Clear();
250 key_material = dup_buffer(blob.key_material, blob.key_material_size);
251 key_material_size = blob.key_material_size;
252 }
253
254 ~KeymasterKeyBlob() { Clear(); }
255
256 const uint8_t* begin() const { return key_material; }
257 const uint8_t* end() const { return key_material + key_material_size; }
258
259 void Clear() {
260 memset_s(const_cast<uint8_t*>(key_material), 0, key_material_size);
261 delete[] key_material;
262 key_material = nullptr;
263 key_material_size = 0;
264 }
265
266 const uint8_t* Reset(size_t new_size) {
267 Clear();
268 key_material = new (std::nothrow) uint8_t[new_size];
269 if (key_material)
270 key_material_size = new_size;
271 return key_material;
272 }
273
274 // The key_material in keymaster_key_blob_t is const, which is the right thing in most
275 // circumstances, but occasionally we do need to write into it. This method exposes a non-const
276 // version of the pointer. Use sparingly.
277 uint8_t* writable_data() { return const_cast<uint8_t*>(key_material); }
278
279 keymaster_key_blob_t release() {
280 keymaster_key_blob_t tmp = {key_material, key_material_size};
281 key_material = nullptr;
282 key_material_size = 0;
283 return tmp;
284 }
285
286 size_t SerializedSize() const { return sizeof(uint32_t) + key_material_size; }
287 uint8_t* Serialize(uint8_t* buf, const uint8_t* end) const {
288 return append_size_and_data_to_buf(buf, end, key_material, key_material_size);
289 }
290
291 bool Deserialize(const uint8_t** buf_ptr, const uint8_t* end) {
292 Clear();
293 UniquePtr<uint8_t[]> tmp;
294 if (!copy_size_and_data_from_buf(buf_ptr, end, &key_material_size, &tmp)) {
295 key_material = nullptr;
296 key_material_size = 0;
297 return false;
298 }
299 key_material = tmp.release();
300 return true;
301 }
302};
303
304} // namespace keymaster
305
306#endif // SYSTEM_KEYMASTER_ANDROID_KEYMASTER_UTILS_H_
307
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