1 /* 2 * Copyright (C) 2016 The Android Open Source Project 3 * 4 * Permission is hereby granted, free of charge, to any person 5 * obtaining a copy of this software and associated documentation 6 * files (the "Software"), to deal in the Software without 7 * restriction, including without limitation the rights to use, copy, 8 * modify, merge, publish, distribute, sublicense, and/or sell copies 9 * of the Software, and to permit persons to whom the Software is 10 * furnished to do so, subject to the following conditions: 11 * 12 * The above copyright notice and this permission notice shall be 13 * included in all copies or substantial portions of the Software. 14 * 15 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, 16 * EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF 17 * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND 18 * NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 19 * BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN 20 * ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN 21 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE 22 * SOFTWARE. 23 */ 24 25 #if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) 26 #error "Never include this file directly, include libavb.h instead." 27 #endif 28 29 #ifndef AVB_SLOT_VERIFY_H_ 30 #define AVB_SLOT_VERIFY_H_ 31 32 #include "avb_ops.h" 33 #include "avb_vbmeta_image.h" 34 35 #ifdef __cplusplus 36 extern "C" { 37 #endif 38 39 /* Return codes used in avb_slot_verify(), see that function for 40 * documentation for each field. 41 * 42 * Use avb_slot_verify_result_to_string() to get a textual 43 * representation usable for error/debug output. 44 */ 45 typedef enum { 46 AVB_SLOT_VERIFY_RESULT_OK, 47 AVB_SLOT_VERIFY_RESULT_ERROR_OOM, 48 AVB_SLOT_VERIFY_RESULT_ERROR_IO, 49 AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, 50 AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX, 51 AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, 52 AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA, 53 AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION, 54 AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT 55 } AvbSlotVerifyResult; 56 57 /* Various error handling modes for when verification fails using a 58 * hashtree at runtime inside the HLOS. 59 * 60 * AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE means that the OS 61 * will invalidate the current slot and restart. 62 * 63 * AVB_HASHTREE_ERROR_MODE_RESTART means that the OS will restart. 64 * 65 * AVB_HASHTREE_ERROR_MODE_EIO means that an EIO error will be 66 * returned to applications. 67 * 68 * AVB_HASHTREE_ERROR_MODE_LOGGING means that errors will be logged 69 * and corrupt data may be returned to applications. This mode should 70 * be used ONLY for diagnostics and debugging. It cannot be used 71 * unless AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is also 72 * used. 73 * 74 * AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO means that either 75 * AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO is used 76 * depending on state. This mode implements a state machine whereby 77 * AVB_HASHTREE_ERROR_MODE_RESTART is used by default and when 78 * AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION is passed the 79 * mode transitions to AVB_HASHTREE_ERROR_MODE_EIO. When a new OS has been 80 * detected the device transitions back to the AVB_HASHTREE_ERROR_MODE_RESTART 81 * mode. To do this persistent storage is needed - specifically this means that 82 * the passed in AvbOps will need to have the read_persistent_value() and 83 * write_persistent_value() operations implemented. The name of the persistent 84 * value used is "avb.managed_verity_mode" and 32 bytes of storage is needed. 85 */ 86 typedef enum { 87 AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, 88 AVB_HASHTREE_ERROR_MODE_RESTART, 89 AVB_HASHTREE_ERROR_MODE_EIO, 90 AVB_HASHTREE_ERROR_MODE_LOGGING, 91 AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO 92 } AvbHashtreeErrorMode; 93 94 /* Flags that influence how avb_slot_verify() works. 95 * 96 * If AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is NOT set then 97 * avb_slot_verify() will bail out as soon as an error is encountered 98 * and |out_data| is set only if AVB_SLOT_VERIFY_RESULT_OK is 99 * returned. 100 * 101 * Otherwise if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set 102 * avb_slot_verify() will continue verification efforts and |out_data| 103 * is also set if AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, 104 * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, or 105 * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned. It is 106 * undefined which error is returned if more than one distinct error 107 * is encountered. It is guaranteed that AVB_SLOT_VERIFY_RESULT_OK is 108 * returned if, and only if, there are no errors. This mode is needed 109 * to boot valid but unverified slots when the device is unlocked. 110 * 111 * Also, if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set the 112 * contents loaded from |requested_partition| will be the contents of 113 * the entire partition instead of just the size specified in the hash 114 * descriptor. 115 * 116 * The AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION flag 117 * should be set if using AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO 118 * and the reason the boot loader is running is because the device 119 * was restarted by the dm-verity driver. 120 */ 121 typedef enum { 122 AVB_SLOT_VERIFY_FLAGS_NONE = 0, 123 AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR = (1 << 0), 124 AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION = (1 << 1) 125 } AvbSlotVerifyFlags; 126 127 /* Get a textual representation of |result|. */ 128 const char* avb_slot_verify_result_to_string(AvbSlotVerifyResult result); 129 130 /* Maximum number of rollback index locations supported. */ 131 #define AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS 32 132 133 /* AvbPartitionData contains data loaded from partitions when using 134 * avb_slot_verify(). The |partition_name| field contains the name of 135 * the partition (without A/B suffix), |data| points to the loaded 136 * data which is |data_size| bytes long. If |preloaded| is set to true, 137 * this structure dose not own |data|. The caller of |avb_slot_verify| 138 * needs to make sure that the preloaded data outlives this 139 * |AvbPartitionData| structure. 140 * 141 * Note that this is strictly less than the partition size - it's only 142 * the image stored there, not the entire partition nor any of the 143 * metadata. 144 */ 145 typedef struct { 146 char* partition_name; 147 uint8_t* data; 148 size_t data_size; 149 bool preloaded; 150 } AvbPartitionData; 151 152 /* AvbVBMetaData contains a vbmeta struct loaded from a partition when 153 * using avb_slot_verify(). The |partition_name| field contains the 154 * name of the partition (without A/B suffix), |vbmeta_data| points to 155 * the loaded data which is |vbmeta_size| bytes long. 156 * 157 * The |verify_result| field contains the result of 158 * avb_vbmeta_image_verify() on the data. This is guaranteed to be 159 * AVB_VBMETA_VERIFY_RESULT_OK for all vbmeta images if 160 * avb_slot_verify() returns AVB_SLOT_VERIFY_RESULT_OK. 161 * 162 * You can use avb_descriptor_get_all(), avb_descriptor_foreach(), and 163 * avb_vbmeta_image_header_to_host_byte_order() with this data. 164 */ 165 typedef struct { 166 char* partition_name; 167 uint8_t* vbmeta_data; 168 size_t vbmeta_size; 169 AvbVBMetaVerifyResult verify_result; 170 } AvbVBMetaData; 171 172 /* AvbSlotVerifyData contains data needed to boot a particular slot 173 * and is returned by avb_slot_verify() if partitions in a slot are 174 * successfully verified. 175 * 176 * All data pointed to by this struct - including data in each item in 177 * the |partitions| array - will be freed when the 178 * avb_slot_verify_data_free() function is called. 179 * 180 * The |ab_suffix| field is the copy of the of |ab_suffix| field 181 * passed to avb_slot_verify(). It is the A/B suffix of the slot. This 182 * value includes the leading underscore - typical values are "" (if 183 * no slots are in use), "_a" (for the first slot), and "_b" (for the 184 * second slot). 185 * 186 * The VBMeta images that were checked are available in the 187 * |vbmeta_images| field. The field |num_vbmeta_images| contains the 188 * number of elements in this array. The first element - 189 * vbmeta_images[0] - is guaranteed to be from the partition with the 190 * top-level vbmeta struct. This is usually the "vbmeta" partition in 191 * the requested slot but if there is no "vbmeta" partition it can 192 * also be the "boot" partition. 193 * 194 * The partitions loaded and verified from from the slot are 195 * accessible in the |loaded_partitions| array. The field 196 * |num_loaded_partitions| contains the number of elements in this 197 * array. The order of partitions in this array may not necessarily be 198 * the same order as in the passed-in |requested_partitions| array. 199 * 200 * Rollback indexes for the verified slot are stored in the 201 * |rollback_indexes| field. Note that avb_slot_verify() will NEVER 202 * modify stored_rollback_index[n] locations e.g. it will never use 203 * the write_rollback_index() AvbOps operation. Instead it is the job 204 * of the caller of avb_slot_verify() to do this based on e.g. A/B 205 * policy and other factors. See libavb_ab/avb_ab_flow.c for an 206 * example of how to do this. 207 * 208 * The |cmdline| field is a NUL-terminated string in UTF-8 resulting 209 * from concatenating all |AvbKernelCmdlineDescriptor| and then 210 * performing proper substitution of the variables 211 * $(ANDROID_SYSTEM_PARTUUID), $(ANDROID_BOOT_PARTUUID), and 212 * $(ANDROID_VBMETA_PARTUUID) using the 213 * get_unique_guid_for_partition() operation in |AvbOps|. Additionally 214 * $(ANDROID_VERITY_MODE) will be replaced with the proper dm-verity 215 * option depending on the value of |hashtree_error_mode|. 216 * 217 * Additionally, the |cmdline| field will have the following kernel 218 * command-line options set (unless verification is disabled, see 219 * below): 220 * 221 * androidboot.veritymode: This is set to 'disabled' if the 222 * AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED flag is set in top-level 223 * vbmeta struct. Otherwise it is set to 'enforcing' if the 224 * passed-in hashtree error mode is AVB_HASHTREE_ERROR_MODE_RESTART 225 * or AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, 'eio' if it's 226 * set to AVB_HASHTREE_ERROR_MODE_EIO, and 'logging' if it's set to 227 * AVB_HASHTREE_ERROR_MODE_LOGGING. 228 * 229 * androidboot.veritymode.managed: This is set to 'yes' only 230 * if hashtree validation isn't disabled and the passed-in hashtree 231 * error mode is AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO. 232 * 233 * androidboot.vbmeta.invalidate_on_error: This is set to 'yes' only 234 * if hashtree validation isn't disabled and the passed-in hashtree 235 * error mode is AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE. 236 * 237 * androidboot.vbmeta.device_state: set to "locked" or "unlocked" 238 * depending on the result of the result of AvbOps's 239 * read_is_unlocked() function. 240 * 241 * androidboot.vbmeta.{hash_alg, size, digest}: Will be set to 242 * the digest of all images in |vbmeta_images|. 243 * 244 * androidboot.vbmeta.device: This is set to the value 245 * PARTUUID=$(ANDROID_VBMETA_PARTUUID) before substitution so it 246 * will end up pointing to the vbmeta partition for the verified 247 * slot. If there is no vbmeta partition it will point to the boot 248 * partition of the verified slot. 249 * 250 * androidboot.vbmeta.avb_version: This is set to the decimal value 251 * of AVB_VERSION_MAJOR followed by a dot followed by the decimal 252 * value of AVB_VERSION_MINOR, for example "1.0" or "1.4". This 253 * version number represents the vbmeta file format version 254 * supported by libavb copy used in the boot loader. This is not 255 * necessarily the same version number of the on-disk metadata for 256 * the slot that was verified. 257 * 258 * Note that androidboot.slot_suffix is not set in the |cmdline| field 259 * in |AvbSlotVerifyData| - you will have to set this yourself. 260 * 261 * If the |AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED| flag is set 262 * in the top-level vbmeta struct then only the top-level vbmeta 263 * struct is verified and descriptors will not processed. The return 264 * value will be set accordingly (if this flag is set via 'avbctl 265 * disable-verification' then the return value will be 266 * |AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION|) and 267 * |AvbSlotVerifyData| is returned. Additionally all partitions in the 268 * |requested_partitions| are loaded and the |cmdline| field is set to 269 * "root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)" and the GUID for the 270 * appropriate system partition is substituted in. Note that none of 271 * the androidboot.* options mentioned above will be set. 272 * 273 * The |resolved_hashtree_error_mode| is the the value of the passed 274 * avb_slot_verify()'s |hashtree_error_mode| parameter except that it never has 275 * the value AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO. If this value was 276 * passed in, then the restart/eio state machine is used resulting in 277 * |resolved_hashtree_error_mode| being set to either 278 * AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO. If set to 279 * AVB_HASHTREE_ERROR_MODE_EIO the boot loader should present a RED warning 280 * screen for the user to click through before continuing to boot. 281 * 282 * This struct may grow in the future without it being considered an 283 * ABI break. 284 */ 285 typedef struct { 286 char* ab_suffix; 287 AvbVBMetaData* vbmeta_images; 288 size_t num_vbmeta_images; 289 AvbPartitionData* loaded_partitions; 290 size_t num_loaded_partitions; 291 char* cmdline; 292 uint64_t rollback_indexes[AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS]; 293 AvbHashtreeErrorMode resolved_hashtree_error_mode; 294 } AvbSlotVerifyData; 295 296 /* Calculates a digest of all vbmeta images in |data| using 297 * the digest indicated by |digest_type|. Stores the result 298 * in |out_digest| which must be large enough to hold a digest 299 * of the requested type. 300 */ 301 void avb_slot_verify_data_calculate_vbmeta_digest(AvbSlotVerifyData* data, 302 AvbDigestType digest_type, 303 uint8_t* out_digest); 304 305 /* Frees a |AvbSlotVerifyData| including all data it points to. */ 306 void avb_slot_verify_data_free(AvbSlotVerifyData* data); 307 308 /* Performs a full verification of the slot identified by |ab_suffix| 309 * and load and verify the contents of the partitions whose name is in 310 * the NULL-terminated string array |requested_partitions| (each 311 * partition must use hash verification). If not using A/B, pass an 312 * empty string (e.g. "", not NULL) for |ab_suffix|. This parameter 313 * must include the leading underscore, for example "_a" should be 314 * used to refer to the first slot. 315 * 316 * Typically the |requested_partitions| array only contains a single 317 * item for the boot partition, 'boot'. 318 * 319 * Verification includes loading and verifying data from the 'vbmeta', 320 * the requested hash partitions, and possibly other partitions (with 321 * |ab_suffix| appended), inspecting rollback indexes, and checking if 322 * the public key used to sign the data is acceptable. The functions 323 * in |ops| will be used to do this. 324 * 325 * If |out_data| is not NULL, it will be set to a newly allocated 326 * |AvbSlotVerifyData| struct containing all the data needed to 327 * actually boot the slot. This data structure should be freed with 328 * avb_slot_verify_data_free() when you are done with it. See below 329 * for when this is returned. 330 * 331 * The |flags| parameter is used to influence the semantics of 332 * avb_slot_verify() - for example the 333 * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR flag can be used to 334 * ignore verification errors which is something needed in the 335 * UNLOCKED state. See the AvbSlotVerifyFlags enumeration for details. 336 * 337 * The |hashtree_error_mode| parameter should be set to the desired error 338 * handling mode. See the AvbHashtreeErrorMode enumeration for details. 339 * 340 * Also note that |out_data| is never set if 341 * AVB_SLOT_VERIFY_RESULT_ERROR_OOM, AVB_SLOT_VERIFY_RESULT_ERROR_IO, 342 * or AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned. 343 * 344 * AVB_SLOT_VERIFY_RESULT_OK is returned if everything is verified 345 * correctly and all public keys are accepted. 346 * 347 * AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED is returned if 348 * everything is verified correctly out but one or more public keys 349 * are not accepted. This includes the case where integrity data is 350 * not signed. 351 * 352 * AVB_SLOT_VERIFY_RESULT_ERROR_OOM is returned if unable to 353 * allocate memory. 354 * 355 * AVB_SLOT_VERIFY_RESULT_ERROR_IO is returned if an I/O error 356 * occurred while trying to load data or get a rollback index. 357 * 358 * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION is returned if the data 359 * did not verify, e.g. the digest didn't match or signature checks 360 * failed. 361 * 362 * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned if a 363 * rollback index was less than its stored value. 364 * 365 * AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned if some 366 * of the metadata is invalid or inconsistent. 367 * 368 * AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION is returned if 369 * some of the metadata requires a newer version of libavb than what 370 * is in use. 371 * 372 * AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT is returned if the 373 * caller passed invalid parameters, for example trying to use 374 * AVB_HASHTREE_ERROR_MODE_LOGGING without 375 * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR. 376 */ 377 AvbSlotVerifyResult avb_slot_verify(AvbOps* ops, 378 const char* const* requested_partitions, 379 const char* ab_suffix, 380 AvbSlotVerifyFlags flags, 381 AvbHashtreeErrorMode hashtree_error_mode, 382 AvbSlotVerifyData** out_data); 383 384 #ifdef __cplusplus 385 } 386 #endif 387 388 #endif /* AVB_SLOT_VERIFY_H_ */ 389