1 /*
2 **
3 ** Copyright 2017, The Android Open Source Project
4 **
5 ** Licensed under the Apache License, Version 2.0 (the "License");
6 ** you may not use this file except in compliance with the License.
7 ** You may obtain a copy of the License at
8 **
9 ** http://www.apache.org/licenses/LICENSE-2.0
10 **
11 ** Unless required by applicable law or agreed to in writing, software
12 ** distributed under the License is distributed on an "AS IS" BASIS,
13 ** WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
14 ** See the License for the specific language governing permissions and
15 ** limitations under the License.
16 */
17
18 #include <keymaster/legacy_support/keymaster1_legacy_support.h>
19
20 #include <android-base/logging.h>
21
22 #include <assert.h>
23
24 #include <algorithm>
25 #include <vector>
26
27 namespace keymaster {
28
make_vector(const T * array,size_t len)29 template <typename T> std::vector<T> make_vector(const T* array, size_t len) {
30 return std::vector<T>(array, array + len);
31 }
32
33 // This helper class implements just enough of the C++ standard collection interface to be able to
34 // accept push_back calls, and it does nothing but count them. It's useful when you want to count
35 // insertions but not actually store anything. It's used in digest_set_is_full below to count the
36 // size of a set intersection.
37 struct PushbackCounter {
38 struct value_type {
39 // NOLINTNEXTLINE(google-explicit-constructor)
value_typekeymaster::PushbackCounter::value_type40 template <typename T> value_type(const T&) {}
41 };
push_backkeymaster::PushbackCounter42 void push_back(const value_type&) { ++count; }
43 size_t count = 0;
44 };
45
46 static std::vector<keymaster_digest_t> full_digest_list = {
47 KM_DIGEST_MD5, KM_DIGEST_SHA1, KM_DIGEST_SHA_2_224,
48 KM_DIGEST_SHA_2_256, KM_DIGEST_SHA_2_384, KM_DIGEST_SHA_2_512};
49
digest_set_is_full(Iter begin,Iter end)50 template <typename Iter> static bool digest_set_is_full(Iter begin, Iter end) {
51 PushbackCounter counter;
52 std::set_intersection(begin, end, full_digest_list.begin(), full_digest_list.end(),
53 std::back_inserter(counter));
54 return counter.count == full_digest_list.size();
55 }
56
add_digests(const keymaster1_device_t * dev,keymaster_algorithm_t algorithm,keymaster_purpose_t purpose,Keymaster1LegacySupport::DigestMap * map,bool * supports_all)57 static keymaster_error_t add_digests(const keymaster1_device_t* dev, keymaster_algorithm_t algorithm,
58 keymaster_purpose_t purpose,
59 Keymaster1LegacySupport::DigestMap* map, bool* supports_all) {
60 auto key = std::make_pair(algorithm, purpose);
61
62 keymaster_digest_t* digests;
63 size_t digests_length;
64 keymaster_error_t error =
65 dev->get_supported_digests(dev, algorithm, purpose, &digests, &digests_length);
66 if (error != KM_ERROR_OK) {
67 LOG(ERROR) << "Error " << error << " getting supported digests from keymaster1 device";
68 return error;
69 }
70 std::unique_ptr<keymaster_digest_t, Malloc_Delete> digests_deleter(digests);
71
72 auto digest_vec = make_vector(digests, digests_length);
73 *supports_all = digest_set_is_full(digest_vec.begin(), digest_vec.end());
74 (*map)[key] = std::move(digest_vec);
75 return error;
76 }
77
map_digests(const keymaster1_device_t * dev,Keymaster1LegacySupport::DigestMap * map,bool * supports_all)78 static keymaster_error_t map_digests(const keymaster1_device_t* dev,
79 Keymaster1LegacySupport::DigestMap* map,
80 bool* supports_all) {
81 map->clear();
82 *supports_all = true;
83
84 keymaster_algorithm_t sig_algorithms[] = {KM_ALGORITHM_RSA, KM_ALGORITHM_EC, KM_ALGORITHM_HMAC};
85 keymaster_purpose_t sig_purposes[] = {KM_PURPOSE_SIGN, KM_PURPOSE_VERIFY};
86 for (auto algorithm : sig_algorithms)
87 for (auto purpose : sig_purposes) {
88 bool alg_purpose_supports_all;
89 keymaster_error_t error =
90 add_digests(dev, algorithm, purpose, map, &alg_purpose_supports_all);
91 if (error != KM_ERROR_OK)
92 return error;
93 *supports_all &= alg_purpose_supports_all;
94 }
95
96 keymaster_algorithm_t crypt_algorithms[] = {KM_ALGORITHM_RSA};
97 keymaster_purpose_t crypt_purposes[] = {KM_PURPOSE_ENCRYPT, KM_PURPOSE_DECRYPT};
98 for (auto algorithm : crypt_algorithms)
99 for (auto purpose : crypt_purposes) {
100 bool alg_purpose_supports_all;
101 keymaster_error_t error =
102 add_digests(dev, algorithm, purpose, map, &alg_purpose_supports_all);
103 if (error != KM_ERROR_OK)
104 return error;
105 *supports_all &= alg_purpose_supports_all;
106 }
107
108 return KM_ERROR_OK;
109 }
110
Keymaster1LegacySupport(const keymaster1_device_t * dev)111 Keymaster1LegacySupport::Keymaster1LegacySupport(const keymaster1_device_t* dev) {
112 map_digests(dev, &device_digests_, &supports_all_);
113 }
114
contains(const Collection & c,const Value & v)115 template <typename Collection, typename Value> bool contains(const Collection& c, const Value& v) {
116 return std::find(c.begin(), c.end(), v) != c.end();
117 }
118
119 template <typename T>
findUnsupportedDigest(keymaster_algorithm_t algorithm,keymaster_purpose_t purpose,keymaster_digest_t digest,const T & params,const Keymaster1LegacySupport::DigestMap & digest_map)120 static bool findUnsupportedDigest(keymaster_algorithm_t algorithm,
121 keymaster_purpose_t purpose,
122 keymaster_digest_t digest,
123 const T& params,
124 const Keymaster1LegacySupport::DigestMap& digest_map) {
125 auto supported_digests = digest_map.find(std::make_pair(algorithm, purpose));
126 if (supported_digests == digest_map.end())
127 // Invalid algorith/purpose pair (e.g. EC encrypt). Let the error be handled by HW module.
128 return false;
129
130 if (digest != KM_DIGEST_NONE && !contains(supported_digests->second, digest)) {
131 LOG(WARNING) << "Digest " << digest << " requested but not supported by KM1 hal";
132 return true;
133 }
134
135 for (auto& entry : params)
136 if (entry.tag == TAG_DIGEST)
137 if (!contains(supported_digests->second, entry.enumerated)) {
138 LOG(WARNING) << "Digest " << entry.enumerated << " requested but not supported by KM1 hal";
139 return true;
140 }
141 return false;
142 }
143
144 template <typename T>
requiresSoftwareDigesting(keymaster_algorithm_t algorithm,keymaster_purpose_t purpose,keymaster_digest_t digest,const T & params,const Keymaster1LegacySupport::DigestMap & digest_map)145 bool requiresSoftwareDigesting(keymaster_algorithm_t algorithm, keymaster_purpose_t purpose,
146 keymaster_digest_t digest,
147 const T& params,
148 const Keymaster1LegacySupport::DigestMap& digest_map) {
149 switch (algorithm) {
150 case KM_ALGORITHM_AES:
151 case KM_ALGORITHM_TRIPLE_DES:
152 LOG(WARNING) << "Not performing software digesting for symmetric cipher keys";
153 return false;
154 case KM_ALGORITHM_HMAC:
155 case KM_ALGORITHM_RSA:
156 case KM_ALGORITHM_EC:
157 break;
158 }
159
160 if (!findUnsupportedDigest(algorithm, purpose, digest, params, digest_map)) {
161 LOG(DEBUG) << "Requested digest(s) supported for algorithm " << algorithm << " and purpose " << purpose;
162 return false;
163 }
164
165 return true;
166 }
RequiresSoftwareDigesting(const AuthorizationSet & key_description) const167 bool Keymaster1LegacySupport::RequiresSoftwareDigesting(
168 const AuthorizationSet& key_description) const {
169
170 keymaster_algorithm_t algorithm;
171 if (!key_description.GetTagValue(TAG_ALGORITHM, &algorithm)) {
172 // The hardware module will return an error during keygen.
173 return false;
174 }
175
176 if (supports_all_) return false;
177
178 bool has_purpose = false;
179 for (auto& entry : key_description)
180 if (entry.tag == TAG_PURPOSE) {
181 has_purpose = true;
182 keymaster_purpose_t purpose = static_cast<keymaster_purpose_t>(entry.enumerated);
183 if (requiresSoftwareDigesting(algorithm, purpose, KM_DIGEST_NONE, key_description,
184 device_digests_))
185 return true;
186 }
187
188 return !has_purpose;
189 }
190
RequiresSoftwareDigesting(const keymaster_digest_t digest,const AuthProxy & key_description) const191 bool Keymaster1LegacySupport::RequiresSoftwareDigesting(const keymaster_digest_t digest,
192 const AuthProxy& key_description) const {
193
194 keymaster_algorithm_t algorithm;
195 if (!key_description.GetTagValue(TAG_ALGORITHM, &algorithm)) {
196 // The hardware module will return an error during keygen.
197 return false;
198 }
199
200 if (supports_all_) return false;
201
202 bool has_purpose = false;
203 for (auto& entry : key_description) {
204 if (entry.tag == TAG_PURPOSE) {
205 has_purpose = true;
206 keymaster_purpose_t purpose = static_cast<keymaster_purpose_t>(entry.enumerated);
207 if (requiresSoftwareDigesting(algorithm, purpose, digest, key_description,
208 device_digests_))
209 return true;
210 }
211 }
212
213 /*
214 * If the key does not have a purpose it is unusable, i.e., for private key operations.
215 * The public key operations which don't need purpose authorization may as well be done
216 * in software. This also addresses a bug by which begin operation on keys without purpose and
217 * unauthorized digest which is also not supported by the wrapped KM1 device fail with
218 * KM_UNSUPPORTED_DIGEST although they should not fail during the begin operation.
219 * If it has a purpose and we reach this point we did not find unsupported digests, and
220 * therefore do not required software digesting.
221 */
222 return !has_purpose;
223 }
224
225 template<>
226 keymaster_error_t
GenerateKey(const AuthorizationSet & key_description,KeymasterKeyBlob * key_blob,AuthorizationSet * hw_enforced,AuthorizationSet * sw_enforced) const227 Keymaster1ArbitrationFactory<EcdsaKeymaster1KeyFactory>::GenerateKey(
228 const AuthorizationSet& key_description,
229 KeymasterKeyBlob* key_blob, AuthorizationSet* hw_enforced,
230 AuthorizationSet* sw_enforced) const {
231 if (legacy_support_.RequiresSoftwareDigesting(key_description)) {
232 return software_digest_factory_.GenerateKey(key_description, key_blob, hw_enforced,
233 sw_enforced);
234 } else {
235 AuthorizationSet mutable_key_description = key_description;
236 keymaster_ec_curve_t curve;
237 if (key_description.GetTagValue(TAG_EC_CURVE, &curve)) {
238 // Keymaster1 doesn't know about EC curves. We need to translate to key size.
239 uint32_t key_size_from_curve;
240 keymaster_error_t error = EcCurveToKeySize(curve, &key_size_from_curve);
241 if (error != KM_ERROR_OK) {
242 return error;
243 }
244
245 uint32_t key_size_from_desc;
246 if (key_description.GetTagValue(TAG_KEY_SIZE, &key_size_from_desc)) {
247 if (key_size_from_desc != key_size_from_curve) {
248 return KM_ERROR_INVALID_ARGUMENT;
249 }
250 } else {
251 mutable_key_description.push_back(TAG_KEY_SIZE, key_size_from_curve);
252 }
253 }
254
255 return passthrough_factory_.GenerateKey(mutable_key_description, key_blob, hw_enforced,
256 sw_enforced);
257 }
258 }
259
260 template<>
261 keymaster_error_t
LoadKey(KeymasterKeyBlob && key_material,const AuthorizationSet & additional_params,AuthorizationSet && hw_enforced,AuthorizationSet && sw_enforced,UniquePtr<Key> * key) const262 Keymaster1ArbitrationFactory<EcdsaKeymaster1KeyFactory>::LoadKey(KeymasterKeyBlob&& key_material,
263 const AuthorizationSet& additional_params,
264 AuthorizationSet&& hw_enforced,
265 AuthorizationSet&& sw_enforced,
266 UniquePtr<Key>* key) const {
267 keymaster_digest_t digest;
268 if (!additional_params.GetTagValue(TAG_DIGEST, &digest)) {
269 digest = KM_DIGEST_NONE;
270 }
271 bool requires_software_digesting = legacy_support_.RequiresSoftwareDigesting(digest,
272 AuthProxy(hw_enforced, sw_enforced));
273 auto rc = software_digest_factory_.LoadKey(move(key_material), additional_params,
274 move(hw_enforced), move(sw_enforced), key);
275 if (rc != KM_ERROR_OK) return rc;
276 if (!requires_software_digesting) {
277 (*key)->key_factory() = & passthrough_factory_;
278 }
279 return KM_ERROR_OK;
280 }
281
282 template<>
283 keymaster_error_t
LoadKey(KeymasterKeyBlob && key_material,const AuthorizationSet & additional_params,AuthorizationSet && hw_enforced,AuthorizationSet && sw_enforced,UniquePtr<Key> * key) const284 Keymaster1ArbitrationFactory<RsaKeymaster1KeyFactory>::LoadKey(KeymasterKeyBlob&& key_material,
285 const AuthorizationSet& additional_params,
286 AuthorizationSet&& hw_enforced,
287 AuthorizationSet&& sw_enforced,
288 UniquePtr<Key>* key) const {
289 keymaster_digest_t digest;
290 if (!additional_params.GetTagValue(TAG_DIGEST, &digest)) {
291 digest = KM_DIGEST_NONE;
292 }
293 bool requires_software_digesting = legacy_support_.RequiresSoftwareDigesting(digest,
294 AuthProxy(hw_enforced, sw_enforced));
295 auto rc = software_digest_factory_.LoadKey(move(key_material), additional_params,
296 move(hw_enforced), move(sw_enforced), key);
297 if (rc != KM_ERROR_OK) return rc;
298 if (!requires_software_digesting) {
299 (*key)->key_factory() = & passthrough_factory_;
300 }
301 return KM_ERROR_OK;
302 }
303
304
305 } // namespace keymaster
306