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_SECURITY_KEYSTORE_KEYMASTER_TAGS_H_ 18#define SYSTEM_SECURITY_KEYSTORE_KEYMASTER_TAGS_H_ 19 20/** 21 * This header contains various definitions that make working with keymaster tags safer and easier. 22 * 23 * It makes use of a fair amount of template metaprogramming. The metaprogramming serves the purpose 24 * of making it impossible to make certain classes of mistakes when operating on keymaster 25 * authorizations. For example, it's an error to create a KeyParameter with tag == Tag::PURPOSE 26 * and then to assign Algorithm::RSA to algorithm element of its union. But because the user 27 * must choose the union field, there could be a mismatch which the compiler has now way to 28 * diagnose. 29 * 30 * The machinery in this header solves these problems by describing which union field corresponds 31 * to which Tag. Central to this mechanism is the template TypedTag. It has zero size and binds a 32 * numeric Tag to a type that the compiler understands. By means of the macro DECLARE_TYPED_TAG, 33 * we declare types for each of the tags defined in hardware/interfaces/keymaster/2.0/types.hal. 34 * 35 * The macro DECLARE_TYPED_TAG(name) generates a typename TAG_name_t and a zero sized instance 36 * TAG_name. Once these typed tags have been declared we define metafunctions mapping the each tag 37 * to its value c++ type and the correct union element of KeyParameter. This is done by means of 38 * the macros MAKE_TAG_*VALUE_ACCESSOR, which generates TypedTag2ValueType, a metafunction mapping 39 * a typed tag to the corresponding c++ type, and access function, accessTagValue returning a 40 * reference to the correct element of KeyParameter. 41 * E.g.: 42 * given "KeyParameter param;" then "accessTagValue(TAG_PURPOSE, param)" 43 * yields a reference to param.f.purpose 44 * If used in an assignment the compiler can now check the compatibility of the assigned value. 45 * 46 * For convenience we also provide the constructor like function Authorization(). 47 * Authorization takes a typed tag and a value and checks at compile time whether the value given 48 * is suitable for the given tag. At runtime it creates a new KeyParameter initialized with the 49 * given tag and value and returns it by value. 50 * 51 * The second convenience function, authorizationValue, allows access to the KeyParameter value in 52 * a safe way. It takes a typed tag and a KeyParameter and returns a reference to the value wrapped 53 * by NullOr. NullOr has out-of-band information about whether it is save to access the wrapped 54 * reference. 55 * E.g.: 56 * auto param = Authorization(TAG_ALGORITM, Algorithm::RSA); 57 * auto value1 = authorizationValue(TAG_PURPOSE, param); 58 * auto value2 = authorizationValue(TAG_ALGORITM, param); 59 * value1.isOk() yields false, but value2.isOk() yields true, thus value2.value() is save to access. 60 */ 61 62#include <android/hardware/keymaster/3.0/IHwKeymasterDevice.h> 63#include <hardware/hw_auth_token.h> 64#include <type_traits> 65 66namespace keymaster { 67namespace ng { 68 69using ::android::hardware::keymaster::V3_0::Algorithm; 70using ::android::hardware::keymaster::V3_0::BlockMode; 71using ::android::hardware::keymaster::V3_0::Digest; 72using ::android::hardware::keymaster::V3_0::EcCurve; 73using ::android::hardware::keymaster::V3_0::ErrorCode; 74using ::android::hardware::keymaster::V3_0::HardwareAuthToken; 75using ::android::hardware::keymaster::V3_0::HardwareAuthenticatorType; 76using ::android::hardware::keymaster::V3_0::IKeymasterDevice; 77using ::android::hardware::keymaster::V3_0::KeyBlobUsageRequirements; 78using ::android::hardware::keymaster::V3_0::KeyCharacteristics; 79using ::android::hardware::keymaster::V3_0::KeyDerivationFunction; 80using ::android::hardware::keymaster::V3_0::KeyFormat; 81using ::android::hardware::keymaster::V3_0::KeyOrigin; 82using ::android::hardware::keymaster::V3_0::KeyParameter; 83using ::android::hardware::keymaster::V3_0::KeyPurpose; 84using ::android::hardware::keymaster::V3_0::PaddingMode; 85using ::android::hardware::keymaster::V3_0::Tag; 86using ::android::hardware::keymaster::V3_0::TagType; 87 88using ::android::hardware::hidl_vec; 89using ::android::hardware::Return; 90using ::android::hardware::Status; 91 92// The following create the numeric values that KM_TAG_PADDING and KM_TAG_DIGEST used to have. We 93// need these old values to be able to support old keys that use them. 94static const int32_t KM_TAG_DIGEST_OLD = static_cast<int32_t>(TagType::ENUM) | 5; 95static const int32_t KM_TAG_PADDING_OLD = static_cast<int32_t>(TagType::ENUM) | 7; 96 97constexpr TagType typeFromTag(Tag tag) { 98 return static_cast<TagType>(static_cast<uint32_t>(tag) & static_cast<uint32_t>(0xf0000000)); 99} 100 101/** 102 * TypedTag is a templatized version of Tag, which provides compile-time checking of 103 * keymaster tag types. Instances are convertible to Tag, so they can be used wherever 104 * Tag is expected, and because they encode the tag type it's possible to create 105 * function overloads that only operate on tags with a particular type. 106 */ 107template <TagType tag_type, Tag tag> struct TypedTag { 108 inline TypedTag() { 109 // Ensure that it's impossible to create a TypedTag instance whose 'tag' doesn't have type 110 // 'tag_type'. Attempting to instantiate a tag with the wrong type will result in a compile 111 // error (no match for template specialization StaticAssert<false>), with no run-time cost. 112 static_assert(typeFromTag(tag) == tag_type, "mismatch between tag and tag_type"); 113 } 114 operator Tag() const { return tag; } 115}; 116 117template <Tag tag> struct Tag2TypedTag { typedef TypedTag<typeFromTag(tag), tag> type; }; 118 119template <Tag tag> struct Tag2String; 120 121#define _TAGS_STRINGIFY(x) #x 122#define TAGS_STRINGIFY(x) _TAGS_STRINGIFY(x) 123 124#define DECLARE_TYPED_TAG(name) \ 125 typedef typename Tag2TypedTag<Tag::name>::type TAG_##name##_t; \ 126 extern TAG_##name##_t TAG_##name; \ 127 template <> struct Tag2String<Tag::name> { \ 128 static const char* value() { return "Tag::" TAGS_STRINGIFY(name); } \ 129 } 130 131DECLARE_TYPED_TAG(INVALID); 132DECLARE_TYPED_TAG(KEY_SIZE); 133DECLARE_TYPED_TAG(MAC_LENGTH); 134DECLARE_TYPED_TAG(CALLER_NONCE); 135DECLARE_TYPED_TAG(MIN_MAC_LENGTH); 136DECLARE_TYPED_TAG(RSA_PUBLIC_EXPONENT); 137DECLARE_TYPED_TAG(ECIES_SINGLE_HASH_MODE); 138DECLARE_TYPED_TAG(INCLUDE_UNIQUE_ID); 139DECLARE_TYPED_TAG(ACTIVE_DATETIME); 140DECLARE_TYPED_TAG(ORIGINATION_EXPIRE_DATETIME); 141DECLARE_TYPED_TAG(USAGE_EXPIRE_DATETIME); 142DECLARE_TYPED_TAG(MIN_SECONDS_BETWEEN_OPS); 143DECLARE_TYPED_TAG(MAX_USES_PER_BOOT); 144DECLARE_TYPED_TAG(ALL_USERS); 145DECLARE_TYPED_TAG(USER_ID); 146DECLARE_TYPED_TAG(USER_SECURE_ID); 147DECLARE_TYPED_TAG(NO_AUTH_REQUIRED); 148DECLARE_TYPED_TAG(AUTH_TIMEOUT); 149DECLARE_TYPED_TAG(ALLOW_WHILE_ON_BODY); 150DECLARE_TYPED_TAG(ALL_APPLICATIONS); 151DECLARE_TYPED_TAG(APPLICATION_ID); 152DECLARE_TYPED_TAG(APPLICATION_DATA); 153DECLARE_TYPED_TAG(CREATION_DATETIME); 154DECLARE_TYPED_TAG(ROLLBACK_RESISTANT); 155DECLARE_TYPED_TAG(ROOT_OF_TRUST); 156DECLARE_TYPED_TAG(ASSOCIATED_DATA); 157DECLARE_TYPED_TAG(NONCE); 158DECLARE_TYPED_TAG(AUTH_TOKEN); 159DECLARE_TYPED_TAG(BOOTLOADER_ONLY); 160DECLARE_TYPED_TAG(OS_VERSION); 161DECLARE_TYPED_TAG(OS_PATCHLEVEL); 162DECLARE_TYPED_TAG(UNIQUE_ID); 163DECLARE_TYPED_TAG(ATTESTATION_CHALLENGE); 164DECLARE_TYPED_TAG(ATTESTATION_APPLICATION_ID); 165DECLARE_TYPED_TAG(RESET_SINCE_ID_ROTATION); 166 167DECLARE_TYPED_TAG(PURPOSE); 168DECLARE_TYPED_TAG(ALGORITHM); 169DECLARE_TYPED_TAG(BLOCK_MODE); 170DECLARE_TYPED_TAG(DIGEST); 171DECLARE_TYPED_TAG(PADDING); 172DECLARE_TYPED_TAG(BLOB_USAGE_REQUIREMENTS); 173DECLARE_TYPED_TAG(ORIGIN); 174DECLARE_TYPED_TAG(USER_AUTH_TYPE); 175DECLARE_TYPED_TAG(KDF); 176DECLARE_TYPED_TAG(EC_CURVE); 177 178template <typename... Elems> struct MetaList {}; 179 180using all_tags_t = MetaList< 181 TAG_INVALID_t, TAG_KEY_SIZE_t, TAG_MAC_LENGTH_t, TAG_CALLER_NONCE_t, TAG_MIN_MAC_LENGTH_t, 182 TAG_RSA_PUBLIC_EXPONENT_t, TAG_ECIES_SINGLE_HASH_MODE_t, TAG_INCLUDE_UNIQUE_ID_t, 183 TAG_ACTIVE_DATETIME_t, TAG_ORIGINATION_EXPIRE_DATETIME_t, TAG_USAGE_EXPIRE_DATETIME_t, 184 TAG_MIN_SECONDS_BETWEEN_OPS_t, TAG_MAX_USES_PER_BOOT_t, TAG_ALL_USERS_t, TAG_USER_ID_t, 185 TAG_USER_SECURE_ID_t, TAG_NO_AUTH_REQUIRED_t, TAG_AUTH_TIMEOUT_t, TAG_ALLOW_WHILE_ON_BODY_t, 186 TAG_ALL_APPLICATIONS_t, TAG_APPLICATION_ID_t, TAG_APPLICATION_DATA_t, TAG_CREATION_DATETIME_t, 187 TAG_ROLLBACK_RESISTANT_t, TAG_ROOT_OF_TRUST_t, TAG_ASSOCIATED_DATA_t, TAG_NONCE_t, 188 TAG_AUTH_TOKEN_t, TAG_BOOTLOADER_ONLY_t, TAG_OS_VERSION_t, TAG_OS_PATCHLEVEL_t, TAG_UNIQUE_ID_t, 189 TAG_ATTESTATION_CHALLENGE_t, TAG_ATTESTATION_APPLICATION_ID_t, TAG_RESET_SINCE_ID_ROTATION_t, 190 TAG_PURPOSE_t, TAG_ALGORITHM_t, TAG_BLOCK_MODE_t, TAG_DIGEST_t, TAG_PADDING_t, 191 TAG_BLOB_USAGE_REQUIREMENTS_t, TAG_ORIGIN_t, TAG_USER_AUTH_TYPE_t, TAG_KDF_t, TAG_EC_CURVE_t>; 192 193/* implementation in keystore_utils.cpp */ 194extern const char* stringifyTag(Tag tag); 195 196template <typename TypedTagType> struct TypedTag2ValueType; 197 198#define MAKE_TAG_VALUE_ACCESSOR(tag_type, field_name) \ 199 template <Tag tag> struct TypedTag2ValueType<TypedTag<tag_type, tag>> { \ 200 typedef decltype(static_cast<KeyParameter*>(nullptr)->field_name) type; \ 201 }; \ 202 template <Tag tag> \ 203 inline auto accessTagValue(TypedTag<tag_type, tag>, const KeyParameter& param) \ 204 ->const decltype(param.field_name)& { \ 205 return param.field_name; \ 206 } \ 207 template <Tag tag> \ 208 inline auto accessTagValue(TypedTag<tag_type, tag>, KeyParameter& param) \ 209 ->decltype(param.field_name)& { \ 210 return param.field_name; \ 211 } 212 213MAKE_TAG_VALUE_ACCESSOR(TagType::ULONG, f.longInteger) 214MAKE_TAG_VALUE_ACCESSOR(TagType::ULONG_REP, f.longInteger) 215MAKE_TAG_VALUE_ACCESSOR(TagType::DATE, f.dateTime) 216MAKE_TAG_VALUE_ACCESSOR(TagType::UINT, f.integer) 217MAKE_TAG_VALUE_ACCESSOR(TagType::UINT_REP, f.integer) 218MAKE_TAG_VALUE_ACCESSOR(TagType::BOOL, f.boolValue) 219MAKE_TAG_VALUE_ACCESSOR(TagType::BYTES, blob) 220MAKE_TAG_VALUE_ACCESSOR(TagType::BIGNUM, blob) 221 222#define MAKE_TAG_ENUM_VALUE_ACCESSOR(typed_tag, field_name) \ 223 template <> struct TypedTag2ValueType<decltype(typed_tag)> { \ 224 typedef decltype(static_cast<KeyParameter*>(nullptr)->field_name) type; \ 225 }; \ 226 inline auto accessTagValue(decltype(typed_tag), const KeyParameter& param) \ 227 ->const decltype(param.field_name)& { \ 228 return param.field_name; \ 229 } \ 230 inline auto accessTagValue(decltype(typed_tag), KeyParameter& param) \ 231 ->decltype(param.field_name)& { \ 232 return param.field_name; \ 233 } 234 235MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_ALGORITHM, f.algorithm) 236MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_BLOB_USAGE_REQUIREMENTS, f.keyBlobUsageRequirements) 237MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_BLOCK_MODE, f.blockMode) 238MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_DIGEST, f.digest) 239MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_EC_CURVE, f.ecCurve) 240MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_KDF, f.keyDerivationFunction) 241MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_ORIGIN, f.origin) 242MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_PADDING, f.paddingMode) 243MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_PURPOSE, f.purpose) 244MAKE_TAG_ENUM_VALUE_ACCESSOR(TAG_USER_AUTH_TYPE, f.hardwareAuthenticatorType) 245 246template <TagType tag_type, Tag tag, typename ValueT> 247inline KeyParameter makeKeyParameter(TypedTag<tag_type, tag> ttag, ValueT&& value) { 248 KeyParameter param; 249 param.tag = tag; 250 param.f.longInteger = 0; 251 accessTagValue(ttag, param) = std::forward<ValueT>(value); 252 return param; 253} 254 255// the boolean case 256template <Tag tag> inline KeyParameter makeKeyParameter(TypedTag<TagType::BOOL, tag>) { 257 KeyParameter param; 258 param.tag = tag; 259 param.f.boolValue = true; 260 return param; 261} 262 263template <typename... Pack> struct FirstOrNoneHelper; 264template <typename First> struct FirstOrNoneHelper<First> { typedef First type; }; 265template <> struct FirstOrNoneHelper<> { 266 struct type {}; 267}; 268 269template <typename... Pack> using FirstOrNone = typename FirstOrNoneHelper<Pack...>::type; 270 271template <TagType tag_type, Tag tag, typename... Args> 272inline KeyParameter Authorization(TypedTag<tag_type, tag> ttag, Args&&... args) { 273 static_assert(tag_type != TagType::BOOL || (sizeof...(args) == 0), 274 "TagType::BOOL Authorizations do not take parameters. Presence is truth."); 275 static_assert(tag_type == TagType::BOOL || (sizeof...(args) == 1), 276 "Authorization other then TagType::BOOL take exactly one parameter."); 277 static_assert( 278 tag_type == TagType::BOOL || 279 std::is_convertible<std::remove_cv_t<std::remove_reference_t<FirstOrNone<Args...>>>, 280 typename TypedTag2ValueType<TypedTag<tag_type, tag>>::type>::value, 281 "Invalid argument type for given tag."); 282 283 return makeKeyParameter(ttag, std::forward<Args>(args)...); 284} 285 286/** 287 * This class wraps a (mostly return) value and stores whether or not the wrapped value is valid out 288 * of band. Note that if the wrapped value is a reference it is unsafe to access the value if 289 * !isOk(). If the wrapped type is a pointer or value and !isOk(), it is still safe to access the 290 * wrapped value. In this case the pointer will be NULL though, and the value will be default 291 * constructed. 292 */ 293template <typename ValueT> class NullOr { 294 template <typename T> struct reference_initializer { 295 static T&& init() { return *static_cast<std::remove_reference_t<T>*>(nullptr); } 296 }; 297 template <typename T> struct pointer_initializer { 298 static T init() { return nullptr; } 299 }; 300 template <typename T> struct value_initializer { 301 static T init() { return T(); } 302 }; 303 template <typename T> 304 using initializer_t = 305 std::conditional_t<std::is_lvalue_reference<T>::value, reference_initializer<T>, 306 std::conditional_t<std::is_pointer<T>::value, pointer_initializer<T>, 307 value_initializer<T>>>; 308 309 public: 310 NullOr() : value_(initializer_t<ValueT>::init()), null_(true) {} 311 NullOr(ValueT&& value) : value_(std::forward<ValueT>(value)), null_(false) {} 312 313 bool isOk() const { return !null_; } 314 315 const ValueT& value() const & { return value_; } 316 ValueT& value() & { return value_; } 317 ValueT&& value() && { return std::move(value_); } 318 319 private: 320 ValueT value_; 321 bool null_; 322}; 323 324template <typename T> std::remove_reference_t<T> NullOrOr(T&& v) { 325 if (v.isOk()) return v; 326 return {}; 327} 328 329template <typename Head, typename... Tail> 330std::remove_reference_t<Head> NullOrOr(Head&& head, Tail&&... tail) { 331 if (head.isOk()) return head; 332 return NullOrOr(std::forward<Tail>(tail)...); 333} 334 335template <typename Default, typename Wrapped> 336std::remove_reference_t<Wrapped> defaultOr(NullOr<Wrapped>&& optional, Default&& def) { 337 static_assert(std::is_convertible<std::remove_reference_t<Default>, 338 std::remove_reference_t<Wrapped>>::value, 339 "Type of default value must match the type wrapped by NullOr"); 340 if (optional.isOk()) return optional.value(); 341 return def; 342} 343 344template <TagType tag_type, Tag tag> 345inline NullOr<const typename TypedTag2ValueType<TypedTag<tag_type, tag>>::type&> 346authorizationValue(TypedTag<tag_type, tag> ttag, const KeyParameter& param) { 347 if (tag != param.tag) return {}; 348 return accessTagValue(ttag, param); 349} 350 351} // namespace ng 352} // namespace keymaster 353 354#endif // SYSTEM_SECURITY_KEYSTORE_KEYMASTER_TAGS_H_ 355