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Diffstat (limited to 'lib/libavb/avb_slot_verify.h')
| -rw-r--r-- | lib/libavb/avb_slot_verify.h | 341 |
1 files changed, 341 insertions, 0 deletions
diff --git a/lib/libavb/avb_slot_verify.h b/lib/libavb/avb_slot_verify.h new file mode 100644 index 0000000000..d603060469 --- /dev/null +++ b/lib/libavb/avb_slot_verify.h @@ -0,0 +1,341 @@ +/* + * Copyright (C) 2016 The Android Open Source Project + * + * SPDX-License-Identifier: MIT + */ + +#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION) +#error "Never include this file directly, include libavb.h instead." +#endif + +#ifndef AVB_SLOT_VERIFY_H_ +#define AVB_SLOT_VERIFY_H_ + +#include "avb_ops.h" +#include "avb_vbmeta_image.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* Return codes used in avb_slot_verify(), see that function for + * documentation for each field. + * + * Use avb_slot_verify_result_to_string() to get a textual + * representation usable for error/debug output. + */ +typedef enum { + AVB_SLOT_VERIFY_RESULT_OK, + AVB_SLOT_VERIFY_RESULT_ERROR_OOM, + AVB_SLOT_VERIFY_RESULT_ERROR_IO, + AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, + AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX, + AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, + AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA, + AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION, + AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT +} AvbSlotVerifyResult; + +/* Various error handling modes for when verification fails using a + * hashtree at runtime inside the HLOS. + * + * AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE means that the OS + * will invalidate the current slot and restart. + * + * AVB_HASHTREE_ERROR_MODE_RESTART means that the OS will restart. + * + * AVB_HASHTREE_ERROR_MODE_EIO means that an EIO error will be + * returned to applications. + * + * AVB_HASHTREE_ERROR_MODE_LOGGING means that errors will be logged + * and corrupt data may be returned to applications. This mode should + * be used ONLY for diagnostics and debugging. It cannot be used + * unless AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is also + * used. + */ +typedef enum { + AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, + AVB_HASHTREE_ERROR_MODE_RESTART, + AVB_HASHTREE_ERROR_MODE_EIO, + AVB_HASHTREE_ERROR_MODE_LOGGING +} AvbHashtreeErrorMode; + +/* Flags that influence how avb_slot_verify() works. + * + * If AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is NOT set then + * avb_slot_verify() will bail out as soon as an error is encountered + * and |out_data| is set only if AVB_SLOT_VERIFY_RESULT_OK is + * returned. + * + * Otherwise if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set + * avb_slot_verify() will continue verification efforts and |out_data| + * is also set if AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED, + * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION, or + * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned. It is + * undefined which error is returned if more than one distinct error + * is encountered. It is guaranteed that AVB_SLOT_VERIFY_RESULT_OK is + * returned if, and only if, there are no errors. This mode is needed + * to boot valid but unverified slots when the device is unlocked. + * + * Also, if AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR is set the + * contents loaded from |requested_partition| will be the contents of + * the entire partition instead of just the size specified in the hash + * descriptor. + */ +typedef enum { + AVB_SLOT_VERIFY_FLAGS_NONE = 0, + AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR = (1 << 0) +} AvbSlotVerifyFlags; + +/* Get a textual representation of |result|. */ +const char* avb_slot_verify_result_to_string(AvbSlotVerifyResult result); + +/* Maximum number of rollback index locations supported. */ +#define AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS 32 + +/* AvbPartitionData contains data loaded from partitions when using + * avb_slot_verify(). The |partition_name| field contains the name of + * the partition (without A/B suffix), |data| points to the loaded + * data which is |data_size| bytes long. If |preloaded| is set to true, + * this structure dose not own |data|. The caller of |avb_slot_verify| + * needs to make sure that the preloaded data outlives this + * |AvbPartitionData| structure. + * + * Note that this is strictly less than the partition size - it's only + * the image stored there, not the entire partition nor any of the + * metadata. + */ +typedef struct { + char* partition_name; + uint8_t* data; + size_t data_size; + bool preloaded; +} AvbPartitionData; + +/* AvbVBMetaData contains a vbmeta struct loaded from a partition when + * using avb_slot_verify(). The |partition_name| field contains the + * name of the partition (without A/B suffix), |vbmeta_data| points to + * the loaded data which is |vbmeta_size| bytes long. + * + * The |verify_result| field contains the result of + * avb_vbmeta_image_verify() on the data. This is guaranteed to be + * AVB_VBMETA_VERIFY_RESULT_OK for all vbmeta images if + * avb_slot_verify() returns AVB_SLOT_VERIFY_RESULT_OK. + * + * You can use avb_descriptor_get_all(), avb_descriptor_foreach(), and + * avb_vbmeta_image_header_to_host_byte_order() with this data. + */ +typedef struct { + char* partition_name; + uint8_t* vbmeta_data; + size_t vbmeta_size; + AvbVBMetaVerifyResult verify_result; +} AvbVBMetaData; + +/* AvbSlotVerifyData contains data needed to boot a particular slot + * and is returned by avb_slot_verify() if partitions in a slot are + * successfully verified. + * + * All data pointed to by this struct - including data in each item in + * the |partitions| array - will be freed when the + * avb_slot_verify_data_free() function is called. + * + * The |ab_suffix| field is the copy of the of |ab_suffix| field + * passed to avb_slot_verify(). It is the A/B suffix of the slot. This + * value includes the leading underscore - typical values are "" (if + * no slots are in use), "_a" (for the first slot), and "_b" (for the + * second slot). + * + * The VBMeta images that were checked are available in the + * |vbmeta_images| field. The field |num_vbmeta_images| contains the + * number of elements in this array. The first element - + * vbmeta_images[0] - is guaranteed to be from the partition with the + * top-level vbmeta struct. This is usually the "vbmeta" partition in + * the requested slot but if there is no "vbmeta" partition it can + * also be the "boot" partition. + * + * The partitions loaded and verified from from the slot are + * accessible in the |loaded_partitions| array. The field + * |num_loaded_partitions| contains the number of elements in this + * array. The order of partitions in this array may not necessarily be + * the same order as in the passed-in |requested_partitions| array. + * + * Rollback indexes for the verified slot are stored in the + * |rollback_indexes| field. Note that avb_slot_verify() will NEVER + * modify stored_rollback_index[n] locations e.g. it will never use + * the write_rollback_index() AvbOps operation. Instead it is the job + * of the caller of avb_slot_verify() to do this based on e.g. A/B + * policy and other factors. See libavb_ab/avb_ab_flow.c for an + * example of how to do this. + * + * The |cmdline| field is a NUL-terminated string in UTF-8 resulting + * from concatenating all |AvbKernelCmdlineDescriptor| and then + * performing proper substitution of the variables + * $(ANDROID_SYSTEM_PARTUUID), $(ANDROID_BOOT_PARTUUID), and + * $(ANDROID_VBMETA_PARTUUID) using the + * get_unique_guid_for_partition() operation in |AvbOps|. Additionally + * $(ANDROID_VERITY_MODE) will be replaced with the proper dm-verity + * option depending on the value of |hashtree_error_mode|. + * + * Additionally, the |cmdline| field will have the following kernel + * command-line options set (unless verification is disabled, see + * below): + * + * androidboot.veritymode: This is set to 'disabled' if the + * AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED flag is set in top-level + * vbmeta struct. Otherwise it is set to 'enforcing' if the + * passed-in hashtree error mode is AVB_HASHTREE_ERROR_MODE_RESTART + * or AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, 'eio' if it's + * set to AVB_HASHTREE_ERROR_MODE_EIO, and 'logging' if it's set to + * AVB_HASHTREE_ERROR_MODE_LOGGING. + * + * androidboot.vbmeta.invalidate_on_error: This is set to 'yes' only + * if hashtree validation isn't disabled and the passed-in hashtree + * error mode is AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE. + * + * androidboot.vbmeta.device_state: set to "locked" or "unlocked" + * depending on the result of the result of AvbOps's + * read_is_unlocked() function. + * + * androidboot.vbmeta.{hash_alg, size, digest}: Will be set to + * the digest of all images in |vbmeta_images|. + * + * androidboot.vbmeta.device: This is set to the value + * PARTUUID=$(ANDROID_VBMETA_PARTUUID) before substitution so it + * will end up pointing to the vbmeta partition for the verified + * slot. If there is no vbmeta partition it will point to the boot + * partition of the verified slot. + * + * androidboot.vbmeta.avb_version: This is set to the decimal value + * of AVB_VERSION_MAJOR followed by a dot followed by the decimal + * value of AVB_VERSION_MINOR, for example "1.0" or "1.4". This + * version number represents the vbmeta file format version + * supported by libavb copy used in the boot loader. This is not + * necessarily the same version number of the on-disk metadata for + * the slot that was verified. + * + * Note that androidboot.slot_suffix is not set in the |cmdline| field + * in |AvbSlotVerifyData| - you will have to set this yourself. + * + * If the |AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED| flag is set + * in the top-level vbmeta struct then only the top-level vbmeta + * struct is verified and descriptors will not processed. The return + * value will be set accordingly (if this flag is set via 'avbctl + * disable-verification' then the return value will be + * |AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION|) and + * |AvbSlotVerifyData| is returned. Additionally all partitions in the + * |requested_partitions| are loaded and the |cmdline| field is set to + * "root=PARTUUID=$(ANDROID_SYSTEM_PARTUUID)" and the GUID for the + * appropriate system partition is substituted in. Note that none of + * the androidboot.* options mentioned above will be set. + * + * This struct may grow in the future without it being considered an + * ABI break. + */ +typedef struct { + char* ab_suffix; + AvbVBMetaData* vbmeta_images; + size_t num_vbmeta_images; + AvbPartitionData* loaded_partitions; + size_t num_loaded_partitions; + char* cmdline; + uint64_t rollback_indexes[AVB_MAX_NUMBER_OF_ROLLBACK_INDEX_LOCATIONS]; +} AvbSlotVerifyData; + +/* Calculates a digest of all vbmeta images in |data| using + * the digest indicated by |digest_type|. Stores the result + * in |out_digest| which must be large enough to hold a digest + * of the requested type. + */ +void avb_slot_verify_data_calculate_vbmeta_digest(AvbSlotVerifyData* data, + AvbDigestType digest_type, + uint8_t* out_digest); + +/* Frees a |AvbSlotVerifyData| including all data it points to. */ +void avb_slot_verify_data_free(AvbSlotVerifyData* data); + +/* Performs a full verification of the slot identified by |ab_suffix| + * and load and verify the contents of the partitions whose name is in + * the NULL-terminated string array |requested_partitions| (each + * partition must use hash verification). If not using A/B, pass an + * empty string (e.g. "", not NULL) for |ab_suffix|. This parameter + * must include the leading underscore, for example "_a" should be + * used to refer to the first slot. + * + * Typically the |requested_partitions| array only contains a single + * item for the boot partition, 'boot'. + * + * Verification includes loading and verifying data from the 'vbmeta', + * the requested hash partitions, and possibly other partitions (with + * |ab_suffix| appended), inspecting rollback indexes, and checking if + * the public key used to sign the data is acceptable. The functions + * in |ops| will be used to do this. + * + * If |out_data| is not NULL, it will be set to a newly allocated + * |AvbSlotVerifyData| struct containing all the data needed to + * actually boot the slot. This data structure should be freed with + * avb_slot_verify_data_free() when you are done with it. See below + * for when this is returned. + * + * The |flags| parameter is used to influence the semantics of + * avb_slot_verify() - for example the + * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR flag can be used to + * ignore verification errors which is something needed in the + * UNLOCKED state. See the AvbSlotVerifyFlags enumeration for details. + * + * The |hashtree_error_mode| parameter should be set to the desired + * error handling mode when hashtree validation fails inside the + * HLOS. This value isn't used by libavb per se - it is forwarded to + * the HLOS through the androidboot.veritymode and + * androidboot.vbmeta.invalidate_on_error cmdline parameters. See the + * AvbHashtreeErrorMode enumeration for details. + * + * Also note that |out_data| is never set if + * AVB_SLOT_VERIFY_RESULT_ERROR_OOM, AVB_SLOT_VERIFY_RESULT_ERROR_IO, + * or AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned. + * + * AVB_SLOT_VERIFY_RESULT_OK is returned if everything is verified + * correctly and all public keys are accepted. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_PUBLIC_KEY_REJECTED is returned if + * everything is verified correctly out but one or more public keys + * are not accepted. This includes the case where integrity data is + * not signed. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_OOM is returned if unable to + * allocate memory. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_IO is returned if an I/O error + * occurred while trying to load data or get a rollback index. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_VERIFICATION is returned if the data + * did not verify, e.g. the digest didn't match or signature checks + * failed. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_ROLLBACK_INDEX is returned if a + * rollback index was less than its stored value. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_METADATA is returned if some + * of the metadata is invalid or inconsistent. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_UNSUPPORTED_VERSION is returned if + * some of the metadata requires a newer version of libavb than what + * is in use. + * + * AVB_SLOT_VERIFY_RESULT_ERROR_INVALID_ARGUMENT is returned if the + * caller passed invalid parameters, for example trying to use + * AVB_HASHTREE_ERROR_MODE_LOGGING without + * AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR. + */ +AvbSlotVerifyResult avb_slot_verify(AvbOps* ops, + const char* const* requested_partitions, + const char* ab_suffix, + AvbSlotVerifyFlags flags, + AvbHashtreeErrorMode hashtree_error_mode, + AvbSlotVerifyData** out_data); + +#ifdef __cplusplus +} +#endif + +#endif /* AVB_SLOT_VERIFY_H_ */ |