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/*
* Copyright (C) 2016 The Android Open Source Project
*
* Permission is hereby granted, free of charge, to any person
* obtaining a copy of this software and associated documentation
* files (the "Software"), to deal in the Software without
* restriction, including without limitation the rights to use, copy,
* modify, merge, publish, distribute, sublicense, and/or sell copies
* of the Software, and to permit persons to whom the Software is
* furnished to do so, subject to the following conditions:
*
* The above copyright notice and this permission notice shall be
* included in all copies or substantial portions of the Software.
*
* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
* SOFTWARE.
*/
#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.
*
* AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO means that either
* AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO is used
* depending on state. This mode implements a state machine whereby
* AVB_HASHTREE_ERROR_MODE_RESTART is used by default and when
* AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION is passed the
* mode transitions to AVB_HASHTREE_ERROR_MODE_EIO. When a new OS has been
* detected the device transitions back to the AVB_HASHTREE_ERROR_MODE_RESTART
* mode. To do this persistent storage is needed - specifically this means that
* the passed in AvbOps will need to have the read_persistent_value() and
* write_persistent_value() operations implemented. The name of the persistent
* value used is "avb.managed_verity_mode" and 32 bytes of storage is needed.
*/
typedef enum {
AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE,
AVB_HASHTREE_ERROR_MODE_RESTART,
AVB_HASHTREE_ERROR_MODE_EIO,
AVB_HASHTREE_ERROR_MODE_LOGGING,
AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO
} 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.
*
* The AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION flag
* should be set if using AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO
* and the reason the boot loader is running is because the device
* was restarted by the dm-verity driver.
*/
typedef enum {
AVB_SLOT_VERIFY_FLAGS_NONE = 0,
AVB_SLOT_VERIFY_FLAGS_ALLOW_VERIFICATION_ERROR = (1 << 0),
AVB_SLOT_VERIFY_FLAGS_RESTART_CAUSED_BY_HASHTREE_CORRUPTION = (1 << 1)
} 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
* $(ANDROID_VERITY_MODE) will be replaced with the proper dm-verity
* option depending on the value of |hashtree_error_mode|.
*
* Additionally, the |cmdline| field will have the following kernel
* command-line options set (unless verification is disabled, see
* below):
*
* androidboot.veritymode: This is set to 'disabled' if the
* AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED flag is set in top-level
* vbmeta struct. Otherwise it is set to 'enforcing' if the
* passed-in hashtree error mode is AVB_HASHTREE_ERROR_MODE_RESTART
* or AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE, 'eio' if it's
* set to AVB_HASHTREE_ERROR_MODE_EIO, and 'logging' if it's set to
* AVB_HASHTREE_ERROR_MODE_LOGGING.
*
* androidboot.veritymode.managed: This is set to 'yes' only
* if hashtree validation isn't disabled and the passed-in hashtree
* error mode is AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO.
*
* androidboot.vbmeta.invalidate_on_error: This is set to 'yes' only
* if hashtree validation isn't disabled and the passed-in hashtree
* error mode is AVB_HASHTREE_ERROR_MODE_RESTART_AND_INVALIDATE.
*
* androidboot.vbmeta.device_state: set to "locked" or "unlocked"
* depending on the result of the result of AvbOps's
* read_is_unlocked() function.
*
* androidboot.vbmeta.{hash_alg, size, digest}: Will be set to
* the digest of all images in |vbmeta_images|.
*
* androidboot.vbmeta.device: This is set to the value
* PARTUUID=$(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.
*
* The |resolved_hashtree_error_mode| is the the value of the passed
* avb_slot_verify()'s |hashtree_error_mode| parameter except that it never has
* the value AVB_HASHTREE_ERROR_MODE_MANAGED_RESTART_AND_EIO. If this value was
* passed in, then the restart/eio state machine is used resulting in
* |resolved_hashtree_error_mode| being set to either
* AVB_HASHTREE_ERROR_MODE_RESTART or AVB_HASHTREE_ERROR_MODE_EIO. If set to
* AVB_HASHTREE_ERROR_MODE_EIO the boot loader should present a RED warning
* screen for the user to click through before continuing to boot.
*
* 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];
AvbHashtreeErrorMode resolved_hashtree_error_mode;
} 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. 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_ */