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 #include <keymaster/authorization_set.h>
18 #include <keymaster/key.h>
19 #include <keymaster/operation.h>
20
21
22 namespace keymaster {
23
supported(keymaster_padding_t padding) const24 bool OperationFactory::supported(keymaster_padding_t padding) const {
25 size_t padding_count;
26 const keymaster_padding_t* supported_paddings = SupportedPaddingModes(&padding_count);
27 for (size_t i = 0; i < padding_count; ++i)
28 if (padding == supported_paddings[i])
29 return true;
30 return false;
31 }
32
supported(keymaster_block_mode_t block_mode) const33 bool OperationFactory::supported(keymaster_block_mode_t block_mode) const {
34 size_t block_mode_count;
35 const keymaster_block_mode_t* supported_block_modes = SupportedBlockModes(&block_mode_count);
36 for (size_t i = 0; i < block_mode_count; ++i)
37 if (block_mode == supported_block_modes[i])
38 return true;
39 return false;
40 }
41
supported(keymaster_digest_t digest) const42 bool OperationFactory::supported(keymaster_digest_t digest) const {
43 size_t digest_count;
44 const keymaster_digest_t* supported_digests = SupportedDigests(&digest_count);
45 for (size_t i = 0; i < digest_count; ++i)
46 if (digest == supported_digests[i])
47 return true;
48 return false;
49 }
50
is_public_key_algorithm(keymaster_algorithm_t algorithm)51 inline bool is_public_key_algorithm(keymaster_algorithm_t algorithm) {
52 switch (algorithm) {
53 case KM_ALGORITHM_HMAC:
54 case KM_ALGORITHM_AES:
55 case KM_ALGORITHM_TRIPLE_DES:
56 return false;
57 case KM_ALGORITHM_RSA:
58 case KM_ALGORITHM_EC:
59 return true;
60 }
61
62 // Unreachable.
63 assert(false);
64 return false;
65 }
66
is_public_key_operation() const67 bool OperationFactory::is_public_key_operation() const {
68 KeyType key_type = registry_key();
69
70 if (!is_public_key_algorithm(key_type.algorithm))
71 return false;
72
73 switch (key_type.purpose) {
74 case KM_PURPOSE_VERIFY:
75 case KM_PURPOSE_ENCRYPT:
76 case KM_PURPOSE_WRAP:
77 return true;
78 case KM_PURPOSE_SIGN:
79 case KM_PURPOSE_DECRYPT:
80 case KM_PURPOSE_DERIVE_KEY:
81 return false;
82 };
83
84 // Unreachable.
85 assert(false);
86 return false;
87 }
88
GetAndValidatePadding(const AuthorizationSet & begin_params,const Key & key,keymaster_padding_t * padding,keymaster_error_t * error) const89 bool OperationFactory::GetAndValidatePadding(const AuthorizationSet& begin_params, const Key& key,
90 keymaster_padding_t* padding,
91 keymaster_error_t* error) const {
92 *error = KM_ERROR_UNSUPPORTED_PADDING_MODE;
93 if (!begin_params.GetTagValue(TAG_PADDING, padding)) {
94 LOG_E("%d padding modes specified in begin params", begin_params.GetTagCount(TAG_PADDING));
95 return false;
96 } else if (!supported(*padding)) {
97 LOG_E("Padding mode %d not supported", *padding);
98 return false;
99 } else if (
100 // If it's a public key operation, all padding modes are authorized.
101 !is_public_key_operation() &&
102 // Otherwise the key needs to authorize the specific mode.
103 !key.authorizations().Contains(TAG_PADDING, *padding) &&
104 !key.authorizations().Contains(TAG_PADDING_OLD, *padding)) {
105 LOG_E("Padding mode %d was specified, but not authorized by key", *padding);
106 *error = KM_ERROR_INCOMPATIBLE_PADDING_MODE;
107 return false;
108 }
109
110 *error = KM_ERROR_OK;
111 return true;
112 }
113
GetAndValidateDigest(const AuthorizationSet & begin_params,const Key & key,keymaster_digest_t * digest,keymaster_error_t * error) const114 bool OperationFactory::GetAndValidateDigest(const AuthorizationSet& begin_params, const Key& key,
115 keymaster_digest_t* digest,
116 keymaster_error_t* error) const {
117 *error = KM_ERROR_UNSUPPORTED_DIGEST;
118 if (!begin_params.GetTagValue(TAG_DIGEST, digest)) {
119 LOG_E("%d digests specified in begin params", begin_params.GetTagCount(TAG_DIGEST));
120 return false;
121 } else if (!supported(*digest)) {
122 LOG_E("Digest %d not supported", *digest);
123 return false;
124 } else if (
125 // If it's a public key operation, all digests are authorized.
126 !is_public_key_operation() &&
127 // Otherwise the key needs to authorize the specific digest.
128 !key.authorizations().Contains(TAG_DIGEST, *digest) &&
129 !key.authorizations().Contains(TAG_DIGEST_OLD, *digest)) {
130 LOG_E("Digest %d was specified, but not authorized by key", *digest);
131 *error = KM_ERROR_INCOMPATIBLE_DIGEST;
132 return false;
133 }
134 *error = KM_ERROR_OK;
135 return true;
136 }
137
UpdateForFinish(const AuthorizationSet & input_params,const Buffer & input)138 keymaster_error_t Operation::UpdateForFinish(const AuthorizationSet& input_params,
139 const Buffer& input) {
140 if (!input_params.empty() || input.available_read()) {
141 size_t input_consumed;
142 Buffer output;
143 AuthorizationSet output_params;
144 keymaster_error_t error =
145 Update(input_params, input, &output_params, &output, &input_consumed);
146 if (error != KM_ERROR_OK)
147 return error;
148 assert(input_consumed == input.available_read());
149 assert(output_params.empty());
150 assert(output.available_read() == 0);
151 }
152
153 return KM_ERROR_OK;
154 }
155
156 } // namespace keymaster
157