src/bsp/lk/lib/libavb/avb_ops.h

/*
 * 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_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|.
     *
     * If the partition doesn't exist the AVB_IO_RESULT_ERROR_NO_SUCH_PARTITION
     * error code should be returned.
     *
     * 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_ */