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path: root/soft/SoftGateKeeper.h (plain)
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1/*
2 * Copyright 2015 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
18#ifndef SOFT_GATEKEEPER_H_
19#define SOFT_GATEKEEPER_H_
20
21extern "C" {
22#include <openssl/rand.h>
23#include <openssl/sha.h>
24#include <openssl/hmac.h>
25
26#include <crypto_scrypt.h>
27}
28
29#include <android-base/memory.h>
30#include <gatekeeper/gatekeeper.h>
31
32#include <iostream>
33#include <unordered_map>
34#include <memory>
35
36#define HMAC_SHA_256_KEY_SIZE 32
37
38namespace gatekeeper {
39
40struct fast_hash_t {
41 uint64_t salt;
42 uint8_t digest[SHA256_DIGEST_LENGTH];
43};
44
45class SoftGateKeeper : public GateKeeper {
46public:
47 static const uint32_t SIGNATURE_LENGTH_BYTES = 32;
48
49 // scrypt params
50 static const uint64_t N = 16384;
51 static const uint32_t r = 8;
52 static const uint32_t p = 1;
53
54 static const int MAX_UINT_32_CHARS = 11;
55
56 SoftGateKeeper() {
57 key_.reset(new uint8_t[SIGNATURE_LENGTH_BYTES]);
58 memset(key_.get(), 0, SIGNATURE_LENGTH_BYTES);
59 }
60
61 virtual ~SoftGateKeeper() {
62 }
63
64 virtual bool GetAuthTokenKey(const uint8_t **auth_token_key,
65 uint32_t *length) const {
66 if (auth_token_key == NULL || length == NULL) return false;
67 uint8_t *auth_token_key_copy = new uint8_t[SIGNATURE_LENGTH_BYTES];
68 memcpy(auth_token_key_copy, key_.get(), SIGNATURE_LENGTH_BYTES);
69
70 *auth_token_key = auth_token_key_copy;
71 *length = SIGNATURE_LENGTH_BYTES;
72 return true;
73 }
74
75 virtual void GetPasswordKey(const uint8_t **password_key, uint32_t *length) {
76 if (password_key == NULL || length == NULL) return;
77 uint8_t *password_key_copy = new uint8_t[SIGNATURE_LENGTH_BYTES];
78 memcpy(password_key_copy, key_.get(), SIGNATURE_LENGTH_BYTES);
79
80 *password_key = password_key_copy;
81 *length = SIGNATURE_LENGTH_BYTES;
82 }
83
84 virtual void ComputePasswordSignature(uint8_t *signature, uint32_t signature_length,
85 const uint8_t *, uint32_t, const uint8_t *password,
86 uint32_t password_length, salt_t salt) const {
87 if (signature == NULL) return;
88 crypto_scrypt(password, password_length, reinterpret_cast<uint8_t *>(&salt),
89 sizeof(salt), N, r, p, signature, signature_length);
90 }
91
92 virtual void GetRandom(void *random, uint32_t requested_length) const {
93 if (random == NULL) return;
94 RAND_pseudo_bytes((uint8_t *) random, requested_length);
95 }
96
97 virtual void ComputeSignature(uint8_t *signature, uint32_t signature_length,
98 const uint8_t *key, uint32_t key_length, const uint8_t *message, const uint32_t length) const {
99 if (signature == NULL) return;
100 uint8_t buf[HMAC_SHA_256_KEY_SIZE];
101 size_t buf_len;
102 HMAC(EVP_sha256(), key, key_length, message, length, buf, (unsigned int *)&buf_len);
103 size_t to_write = buf_len;
104 if (buf_len > signature_length) to_write = signature_length;
105 memset(signature, 0, signature_length);
106 memcpy(signature, buf, to_write);
107 }
108
109 virtual uint64_t GetMillisecondsSinceBoot() const {
110 struct timespec time;
111 int res = clock_gettime(CLOCK_BOOTTIME, &time);
112 if (res < 0) return 0;
113 return (time.tv_sec * 1000) + (time.tv_nsec / 1000 / 1000);
114 }
115
116 virtual bool IsHardwareBacked() const {
117 return true;
118 }
119
120 virtual bool GetFailureRecord(uint32_t uid, secure_id_t user_id, failure_record_t *record,
121 bool /* secure */) {
122 failure_record_t *stored = &failure_map_[uid];
123 if (user_id != stored->secure_user_id) {
124 stored->secure_user_id = user_id;
125 stored->last_checked_timestamp = 0;
126 stored->failure_counter = 0;
127 }
128 memcpy(record, stored, sizeof(*record));
129 return true;
130 }
131
132 virtual bool ClearFailureRecord(uint32_t uid, secure_id_t user_id, bool /* secure */) {
133 failure_record_t *stored = &failure_map_[uid];
134 stored->secure_user_id = user_id;
135 stored->last_checked_timestamp = 0;
136 stored->failure_counter = 0;
137 return true;
138 }
139
140 virtual bool WriteFailureRecord(uint32_t uid, failure_record_t *record, bool /* secure */) {
141 failure_map_[uid] = *record;
142 return true;
143 }
144
145 fast_hash_t ComputeFastHash(const SizedBuffer &password, uint64_t salt) {
146 fast_hash_t fast_hash;
147 size_t digest_size = password.length + sizeof(salt);
148 std::unique_ptr<uint8_t[]> digest(new uint8_t[digest_size]);
149 memcpy(digest.get(), &salt, sizeof(salt));
150 memcpy(digest.get() + sizeof(salt), password.buffer.get(), password.length);
151
152 SHA256(digest.get(), digest_size, (uint8_t *) &fast_hash.digest);
153
154 fast_hash.salt = salt;
155 return fast_hash;
156 }
157
158 bool VerifyFast(const fast_hash_t &fast_hash, const SizedBuffer &password) {
159 fast_hash_t computed = ComputeFastHash(password, fast_hash.salt);
160 return memcmp(computed.digest, fast_hash.digest, SHA256_DIGEST_LENGTH) == 0;
161 }
162
163 bool DoVerify(const password_handle_t *expected_handle, const SizedBuffer &password) {
164 uint64_t user_id = android::base::get_unaligned<secure_id_t>(&expected_handle->user_id);
165 FastHashMap::const_iterator it = fast_hash_map_.find(user_id);
166 if (it != fast_hash_map_.end() && VerifyFast(it->second, password)) {
167 return true;
168 } else {
169 if (GateKeeper::DoVerify(expected_handle, password)) {
170 uint64_t salt;
171 GetRandom(&salt, sizeof(salt));
172 fast_hash_map_[user_id] = ComputeFastHash(password, salt);
173 return true;
174 }
175 }
176
177 return false;
178 }
179
180private:
181
182 typedef std::unordered_map<uint32_t, failure_record_t> FailureRecordMap;
183 typedef std::unordered_map<uint64_t, fast_hash_t> FastHashMap;
184
185 std::unique_ptr<uint8_t[]> key_;
186 FailureRecordMap failure_map_;
187 FastHashMap fast_hash_map_;
188};
189}
190
191#endif // SOFT_GATEKEEPER_H_
192
generated by cgit at 2024-05-10 01:50:03 (GMT)