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Diffstat (limited to 'lib/libavb/avb_ops.h')
| -rw-r--r-- | lib/libavb/avb_ops.h | 293 |
1 files changed, 293 insertions, 0 deletions
diff --git a/lib/libavb/avb_ops.h b/lib/libavb/avb_ops.h new file mode 100644 index 0000000000..36134346f6 --- /dev/null +++ b/lib/libavb/avb_ops.h @@ -0,0 +1,293 @@ +/* + * 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_OPS_H_ +#define AVB_OPS_H_ + +#include "avb_sysdeps.h" + +#ifdef __cplusplus +extern "C" { +#endif + +/* Well-known names of named persistent values. */ +#define AVB_NPV_PERSISTENT_DIGEST_PREFIX "avb.persistent_digest." + +/* Return codes used for I/O operations. + * + * AVB_IO_RESULT_OK is returned if the requested operation was + * successful. + * + * AVB_IO_RESULT_ERROR_IO is returned if the underlying hardware (disk + * or other subsystem) encountered an I/O error. + * + * AVB_IO_RESULT_ERROR_OOM is returned if unable to allocate memory. + * + * AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION is returned if the requested + * partition does not exist. + * + * AVB_IO_RESULT_ERROR_RANGE_OUTSIDE_PARTITION is returned if the + * range of bytes requested to be read or written is outside the range + * of the partition. + * + * AVB_IO_RESULT_ERROR_NO_SUCH_VALUE is returned if a named persistent value + * does not exist. + * + * AVB_IO_RESULT_ERROR_INVALID_VALUE_SIZE is returned if a named persistent + * value size is not supported or does not match the expected size. + * + * AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE is returned if a buffer is too small + * for the requested operation. + */ +typedef enum { + AVB_IO_RESULT_OK, + AVB_IO_RESULT_ERROR_OOM, + AVB_IO_RESULT_ERROR_IO, + AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION, + AVB_IO_RESULT_ERROR_RANGE_OUTSIDE_PARTITION, + AVB_IO_RESULT_ERROR_NO_SUCH_VALUE, + AVB_IO_RESULT_ERROR_INVALID_VALUE_SIZE, + AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE, +} AvbIOResult; + +struct AvbOps; +typedef struct AvbOps AvbOps; + +/* Forward-declaration of operations in libavb_ab. */ +struct AvbABOps; + +/* Forward-declaration of operations in libavb_atx. */ +struct AvbAtxOps; + +/* High-level operations/functions/methods that are platform + * dependent. + * + * Operations may be added in the future so when implementing it + * always make sure to zero out sizeof(AvbOps) bytes of the struct to + * ensure that unimplemented operations are set to NULL. + */ +struct AvbOps { + /* This pointer can be used by the application/bootloader using + * libavb and is typically used in each operation to get a pointer + * to platform-specific resources. It cannot be used by libraries. + */ + void* user_data; + + /* If libavb_ab is used, this should point to the + * AvbABOps. Otherwise it must be set to NULL. + */ + struct AvbABOps* ab_ops; + + /* If libavb_atx is used, this should point to the + * AvbAtxOps. Otherwise it must be set to NULL. + */ + struct AvbAtxOps* atx_ops; + + /* Reads |num_bytes| from offset |offset| from partition with name + * |partition| (NUL-terminated UTF-8 string). If |offset| is + * negative, its absolute value should be interpreted as the number + * of bytes from the end of the partition. + * + * This function returns AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION if + * there is no partition with the given name, + * AVB_IO_RESULT_ERROR_RANGE_OUTSIDE_PARTITION if the requested + * |offset| is outside the partition, and AVB_IO_RESULT_ERROR_IO if + * there was an I/O error from the underlying I/O subsystem. If the + * operation succeeds as requested AVB_IO_RESULT_OK is returned and + * the data is available in |buffer|. + * + * The only time partial I/O may occur is if reading beyond the end + * of the partition. In this case the value returned in + * |out_num_read| may be smaller than |num_bytes|. + */ + AvbIOResult (*read_from_partition)(AvbOps* ops, + const char* partition, + int64_t offset, + size_t num_bytes, + void* buffer, + size_t* out_num_read); + + /* Gets the starting pointer of a partition that is pre-loaded in memory, and + * save it to |out_pointer|. The preloaded partition is expected to be + * |num_bytes|, where the actual preloaded byte count is returned in + * |out_num_bytes_preloaded|. |out_num_bytes_preloaded| must be no larger than + * |num_bytes|. + * + * This provides an alternative way to access a partition that is preloaded + * into memory without a full memory copy. When this function pointer is not + * set (has value NULL), or when the |out_pointer| is set to NULL as a result, + * |read_from_partition| will be used as the fallback. This function is mainly + * used for accessing the entire partition content to calculate its hash. + * + * Preloaded partition data must outlive the lifespan of the + * |AvbSlotVerifyData| structure that |avb_slot_verify| outputs. + */ + AvbIOResult (*get_preloaded_partition)(AvbOps* ops, + const char* partition, + size_t num_bytes, + uint8_t** out_pointer, + size_t* out_num_bytes_preloaded); + + /* Writes |num_bytes| from |bffer| at offset |offset| to partition + * with name |partition| (NUL-terminated UTF-8 string). If |offset| + * is negative, its absolute value should be interpreted as the + * number of bytes from the end of the partition. + * + * This function returns AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION if + * there is no partition with the given name, + * AVB_IO_RESULT_ERROR_RANGE_OUTSIDE_PARTITION if the requested + * byterange goes outside the partition, and AVB_IO_RESULT_ERROR_IO + * if there was an I/O error from the underlying I/O subsystem. If + * the operation succeeds as requested AVB_IO_RESULT_OK is + * returned. + * + * This function never does any partial I/O, it either transfers all + * of the requested bytes or returns an error. + */ + AvbIOResult (*write_to_partition)(AvbOps* ops, + const char* partition, + int64_t offset, + size_t num_bytes, + const void* buffer); + + /* Checks if the given public key used to sign the 'vbmeta' + * partition is trusted. Boot loaders typically compare this with + * embedded key material generated with 'avbtool + * extract_public_key'. + * + * The public key is in the array pointed to by |public_key_data| + * and is of |public_key_length| bytes. + * + * If there is no public key metadata (set with the avbtool option + * --public_key_metadata) then |public_key_metadata| will be set to + * NULL. Otherwise this field points to the data which is + * |public_key_metadata_length| bytes long. + * + * If AVB_IO_RESULT_OK is returned then |out_is_trusted| is set - + * true if trusted or false if untrusted. + */ + AvbIOResult (*validate_vbmeta_public_key)(AvbOps* ops, + const uint8_t* public_key_data, + size_t public_key_length, + const uint8_t* public_key_metadata, + size_t public_key_metadata_length, + bool* out_is_trusted); + + /* Gets the rollback index corresponding to the location given by + * |rollback_index_location|. The value is returned in + * |out_rollback_index|. Returns AVB_IO_RESULT_OK if the rollback + * index was retrieved, otherwise an error code. + * + * A device may have a limited amount of rollback index locations (say, + * one or four) so may error out if |rollback_index_location| exceeds + * this number. + */ + AvbIOResult (*read_rollback_index)(AvbOps* ops, + size_t rollback_index_location, + uint64_t* out_rollback_index); + + /* Sets the rollback index corresponding to the location given by + * |rollback_index_location| to |rollback_index|. Returns + * AVB_IO_RESULT_OK if the rollback index was set, otherwise an + * error code. + * + * A device may have a limited amount of rollback index locations (say, + * one or four) so may error out if |rollback_index_location| exceeds + * this number. + */ + AvbIOResult (*write_rollback_index)(AvbOps* ops, + size_t rollback_index_location, + uint64_t rollback_index); + + /* Gets whether the device is unlocked. The value is returned in + * |out_is_unlocked| (true if unlocked, false otherwise). Returns + * AVB_IO_RESULT_OK if the state was retrieved, otherwise an error + * code. + */ + AvbIOResult (*read_is_device_unlocked)(AvbOps* ops, bool* out_is_unlocked); + + /* Gets the unique partition GUID for a partition with name in + * |partition| (NUL-terminated UTF-8 string). The GUID is copied as + * a string into |guid_buf| of size |guid_buf_size| and will be NUL + * terminated. The string must be lower-case and properly + * hyphenated. For example: + * + * 527c1c6d-6361-4593-8842-3c78fcd39219 + * + * Returns AVB_IO_RESULT_OK on success, otherwise an error code. + */ + AvbIOResult (*get_unique_guid_for_partition)(AvbOps* ops, + const char* partition, + char* guid_buf, + size_t guid_buf_size); + + /* Gets the size of a partition with the name in |partition| + * (NUL-terminated UTF-8 string). Returns the value in + * |out_size_num_bytes|. + * + * Returns AVB_IO_RESULT_OK on success, otherwise an error code. + */ + AvbIOResult (*get_size_of_partition)(AvbOps* ops, + const char* partition, + uint64_t* out_size_num_bytes); + + /* Reads a persistent value corresponding to the given |name|. The value is + * returned in |out_buffer| which must point to |buffer_size| bytes. On + * success |out_num_bytes_read| contains the number of bytes read into + * |out_buffer|. If AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE is returned, + * |out_num_bytes_read| contains the number of bytes that would have been read + * which can be used to allocate a buffer. + * + * The |buffer_size| may be zero and the |out_buffer| may be NULL, but if + * |out_buffer| is NULL then |buffer_size| *must* be zero. + * + * Returns AVB_IO_RESULT_OK on success, otherwise an error code. + * + * If the value does not exist, is not supported, or is not populated, returns + * AVB_IO_RESULT_ERROR_NO_SUCH_VALUE. If |buffer_size| is smaller than the + * size of the stored value, returns AVB_IO_RESULT_ERROR_INSUFFICIENT_SPACE. + * + * This operation is currently only used to support persistent digests. If a + * device does not use persistent digests this function pointer can be set to + * NULL. + */ + AvbIOResult (*read_persistent_value)(AvbOps* ops, + const char* name, + size_t buffer_size, + uint8_t* out_buffer, + size_t* out_num_bytes_read); + + /* Writes a persistent value corresponding to the given |name|. The value is + * supplied in |value| which must point to |value_size| bytes. Any existing + * value with the same name is overwritten. If |value_size| is zero, future + * calls to |read_persistent_value| will return + * AVB_IO_RESULT_ERROR_NO_SUCH_VALUE. + * + * Returns AVB_IO_RESULT_OK on success, otherwise an error code. + * + * If the value |name| is not supported, returns + * AVB_IO_RESULT_ERROR_NO_SUCH_VALUE. If the |value_size| is not supported, + * returns AVB_IO_RESULT_ERROR_INVALID_VALUE_SIZE. + * + * This operation is currently only used to support persistent digests. If a + * device does not use persistent digests this function pointer can be set to + * NULL. + */ + AvbIOResult (*write_persistent_value)(AvbOps* ops, + const char* name, + size_t value_size, + const uint8_t* value); +}; + +#ifdef __cplusplus +} +#endif + +#endif /* AVB_OPS_H_ */ |