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 "hmac_operation.h"
18
19 #include <keymaster/new>
20
21 #include <openssl/evp.h>
22 #include <openssl/hmac.h>
23
24 #include <keymaster/km_openssl/hmac_key.h>
25 #include <keymaster/km_openssl/openssl_err.h>
26 #include <keymaster/km_openssl/openssl_utils.h>
27
28 #if defined(OPENSSL_IS_BORINGSSL)
29 #include <openssl/mem.h>
30 typedef size_t openssl_size_t;
31 #else
32 typedef int openssl_size_t;
33 #endif
34
35 namespace keymaster {
36
CreateOperation(Key && key,const AuthorizationSet & begin_params,keymaster_error_t * error) const37 OperationPtr HmacOperationFactory::CreateOperation(Key&& key, const AuthorizationSet& begin_params,
38 keymaster_error_t* error) const {
39 uint32_t min_mac_length_bits;
40 if (!key.authorizations().GetTagValue(TAG_MIN_MAC_LENGTH, &min_mac_length_bits)) {
41 LOG_E("HMAC key must have KM_TAG_MIN_MAC_LENGTH", 0);
42 *error = KM_ERROR_INVALID_KEY_BLOB;
43 return nullptr;
44 }
45
46 uint32_t mac_length_bits = UINT32_MAX;
47 if (begin_params.GetTagValue(TAG_MAC_LENGTH, &mac_length_bits)) {
48 if (purpose() == KM_PURPOSE_VERIFY) {
49 LOG_E("MAC length may not be specified for verify", 0);
50 *error = KM_ERROR_INVALID_ARGUMENT;
51 return nullptr;
52 }
53 } else {
54 if (purpose() == KM_PURPOSE_SIGN) {
55 *error = KM_ERROR_MISSING_MAC_LENGTH;
56 return nullptr;
57 }
58 }
59
60 keymaster_digest_t digest;
61 if (!key.authorizations().GetTagValue(TAG_DIGEST, &digest)) {
62 LOG_E("%d digests found in HMAC key authorizations; must be exactly 1",
63 begin_params.GetTagCount(TAG_DIGEST));
64 *error = KM_ERROR_INVALID_KEY_BLOB;
65 return nullptr;
66 }
67
68 UniquePtr<HmacOperation> op(new (std::nothrow) HmacOperation(
69 move(key), purpose(), digest, mac_length_bits / 8, min_mac_length_bits / 8));
70 if (!op.get())
71 *error = KM_ERROR_MEMORY_ALLOCATION_FAILED;
72 else
73 *error = op->error();
74
75 if (*error != KM_ERROR_OK) return nullptr;
76
77 return move(op);
78 }
79
80 static keymaster_digest_t supported_digests[] = {KM_DIGEST_SHA1, KM_DIGEST_SHA_2_224,
81 KM_DIGEST_SHA_2_256, KM_DIGEST_SHA_2_384,
82 KM_DIGEST_SHA_2_512};
SupportedDigests(size_t * digest_count) const83 const keymaster_digest_t* HmacOperationFactory::SupportedDigests(size_t* digest_count) const {
84 *digest_count = array_length(supported_digests);
85 return supported_digests;
86 }
87
HmacOperation(Key && key,keymaster_purpose_t purpose,keymaster_digest_t digest,size_t mac_length,size_t min_mac_length)88 HmacOperation::HmacOperation(Key&& key, keymaster_purpose_t purpose, keymaster_digest_t digest,
89 size_t mac_length, size_t min_mac_length)
90 : Operation(purpose, key.hw_enforced_move(), key.sw_enforced_move()), error_(KM_ERROR_OK),
91 mac_length_(mac_length), min_mac_length_(min_mac_length) {
92 // Initialize CTX first, so dtor won't crash even if we error out later.
93 HMAC_CTX_init(&ctx_);
94
95 const EVP_MD* md = nullptr;
96 switch (digest) {
97 case KM_DIGEST_NONE:
98 case KM_DIGEST_MD5:
99 error_ = KM_ERROR_UNSUPPORTED_DIGEST;
100 break;
101 case KM_DIGEST_SHA1:
102 md = EVP_sha1();
103 break;
104 case KM_DIGEST_SHA_2_224:
105 md = EVP_sha224();
106 break;
107 case KM_DIGEST_SHA_2_256:
108 md = EVP_sha256();
109 break;
110 case KM_DIGEST_SHA_2_384:
111 md = EVP_sha384();
112 break;
113 case KM_DIGEST_SHA_2_512:
114 md = EVP_sha512();
115 break;
116 }
117
118 if (md == nullptr) {
119 error_ = KM_ERROR_UNSUPPORTED_DIGEST;
120 return;
121 }
122
123 if (purpose == KM_PURPOSE_SIGN) {
124 if (mac_length > EVP_MD_size(md) || mac_length < kMinHmacLengthBits / 8) {
125 error_ = KM_ERROR_UNSUPPORTED_MAC_LENGTH;
126 return;
127 }
128 if (mac_length < min_mac_length) {
129 error_ = KM_ERROR_INVALID_MAC_LENGTH;
130 return;
131 }
132 }
133
134 KeymasterKeyBlob blob = key.key_material_move();
135 HMAC_Init_ex(&ctx_, blob.key_material, blob.key_material_size, md, nullptr /* engine */);
136 }
137
~HmacOperation()138 HmacOperation::~HmacOperation() {
139 HMAC_CTX_cleanup(&ctx_);
140 }
141
Begin(const AuthorizationSet &,AuthorizationSet *)142 keymaster_error_t HmacOperation::Begin(const AuthorizationSet& /* input_params */,
143 AuthorizationSet* /* output_params */) {
144 auto rc = GenerateRandom(reinterpret_cast<uint8_t*>(&operation_handle_),
145 (size_t)sizeof(operation_handle_));
146 if (rc != KM_ERROR_OK) return rc;
147
148 return error_;
149 }
150
Update(const AuthorizationSet &,const Buffer & input,AuthorizationSet *,Buffer *,size_t * input_consumed)151 keymaster_error_t HmacOperation::Update(const AuthorizationSet& /* additional_params */,
152 const Buffer& input, AuthorizationSet* /* output_params */,
153 Buffer* /* output */, size_t* input_consumed) {
154 if (!HMAC_Update(&ctx_, input.peek_read(), input.available_read()))
155 return TranslateLastOpenSslError();
156 *input_consumed = input.available_read();
157 return KM_ERROR_OK;
158 }
159
Abort()160 keymaster_error_t HmacOperation::Abort() {
161 return KM_ERROR_OK;
162 }
163
Finish(const AuthorizationSet & additional_params,const Buffer & input,const Buffer & signature,AuthorizationSet *,Buffer * output)164 keymaster_error_t HmacOperation::Finish(const AuthorizationSet& additional_params,
165 const Buffer& input, const Buffer& signature,
166 AuthorizationSet* /* output_params */, Buffer* output) {
167 keymaster_error_t error = UpdateForFinish(additional_params, input);
168 if (error != KM_ERROR_OK) return error;
169
170 uint8_t digest[EVP_MAX_MD_SIZE];
171 unsigned int digest_len;
172 if (!HMAC_Final(&ctx_, digest, &digest_len)) return TranslateLastOpenSslError();
173
174 switch (purpose()) {
175 case KM_PURPOSE_SIGN:
176 if (mac_length_ > digest_len) return KM_ERROR_UNSUPPORTED_MAC_LENGTH;
177 if (!output->reserve(mac_length_) || !output->write(digest, mac_length_))
178 return KM_ERROR_MEMORY_ALLOCATION_FAILED;
179 return KM_ERROR_OK;
180 case KM_PURPOSE_VERIFY: {
181 size_t siglen = signature.available_read();
182 if (siglen > digest_len || siglen < kMinHmacLengthBits / 8)
183 return KM_ERROR_UNSUPPORTED_MAC_LENGTH;
184 if (siglen < min_mac_length_) return KM_ERROR_INVALID_MAC_LENGTH;
185 if (CRYPTO_memcmp(signature.peek_read(), digest, siglen) != 0)
186 return KM_ERROR_VERIFICATION_FAILED;
187 return KM_ERROR_OK;
188 }
189 default:
190 return KM_ERROR_UNSUPPORTED_PURPOSE;
191 }
192 }
193
194 } // namespace keymaster
195