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