| /* |
| * 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_VBMETA_IMAGE_H_ |
| #define AVB_VBMETA_IMAGE_H_ |
| |
| #include "avb_sysdeps.h" |
| |
| #ifdef __cplusplus |
| extern "C" { |
| #endif |
| |
| #include "avb_crypto.h" |
| #include "avb_descriptor.h" |
| |
| /* Size of the vbmeta image header. */ |
| #define AVB_VBMETA_IMAGE_HEADER_SIZE 256 |
| |
| /* Magic for the vbmeta image header. */ |
| #define AVB_MAGIC "AVB0" |
| #define AVB_MAGIC_LEN 4 |
| |
| /* Maximum size of the release string including the terminating NUL byte. */ |
| #define AVB_RELEASE_STRING_SIZE 48 |
| |
| /* Flags for the vbmeta image. |
| * |
| * AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED: If this flag is set, |
| * hashtree image verification will be disabled. |
| * |
| * AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED: If this flag is set, |
| * verification will be disabled and descriptors will not be parsed. |
| */ |
| typedef enum { |
| AVB_VBMETA_IMAGE_FLAGS_HASHTREE_DISABLED = (1 << 0), |
| AVB_VBMETA_IMAGE_FLAGS_VERIFICATION_DISABLED = (1 << 1) |
| } AvbVBMetaImageFlags; |
| |
| /* Binary format for header of the vbmeta image. |
| * |
| * The vbmeta image consists of three blocks: |
| * |
| * +-----------------------------------------+ |
| * | Header data - fixed size | |
| * +-----------------------------------------+ |
| * | Authentication data - variable size | |
| * +-----------------------------------------+ |
| * | Auxiliary data - variable size | |
| * +-----------------------------------------+ |
| * |
| * The "Header data" block is described by this struct and is always |
| * |AVB_VBMETA_IMAGE_HEADER_SIZE| bytes long. |
| * |
| * The "Authentication data" block is |authentication_data_block_size| |
| * bytes long and contains the hash and signature used to authenticate |
| * the vbmeta image. The type of the hash and signature is defined by |
| * the |algorithm_type| field. |
| * |
| * The "Auxiliary data" is |auxiliary_data_block_size| bytes long and |
| * contains the auxiliary data including the public key used to make |
| * the signature and descriptors. |
| * |
| * The public key is at offset |public_key_offset| with size |
| * |public_key_size| in this block. The size of the public key data is |
| * defined by the |algorithm_type| field. The format of the public key |
| * data is described in the |AvbRSAPublicKeyHeader| struct. |
| * |
| * The descriptors starts at |descriptors_offset| from the beginning |
| * of the "Auxiliary Data" block and take up |descriptors_size| |
| * bytes. Each descriptor is stored as a |AvbDescriptor| with tag and |
| * number of bytes following. The number of descriptors can be |
| * determined by walking this data until |descriptors_size| is |
| * exhausted. |
| * |
| * The size of each of the "Authentication data" and "Auxiliary data" |
| * blocks must be divisible by 64. This is to ensure proper alignment. |
| * |
| * Descriptors are free-form blocks stored in a part of the vbmeta |
| * image subject to the same integrity checks as the rest of the |
| * image. See the documentation for |AvbDescriptor| for well-known |
| * descriptors. See avb_descriptor_foreach() for a convenience |
| * function to iterate over descriptors. |
| * |
| * This struct is versioned, see the |required_libavb_version_major| |
| * and |required_libavb_version_minor| fields. This represents the |
| * minimum version of libavb required to verify the header and depends |
| * on the features (e.g. algorithms, descriptors) used. Note that this |
| * may be 1.0 even if generated by an avbtool from 1.4 but where no |
| * features introduced after 1.0 has been used. See the "Versioning |
| * and compatibility" section in the README.md file for more details. |
| * |
| * All fields are stored in network byte order when serialized. To |
| * generate a copy with fields swapped to native byte order, use the |
| * function avb_vbmeta_image_header_to_host_byte_order(). |
| * |
| * Before reading and/or using any of this data, you MUST verify it |
| * using avb_vbmeta_image_verify() and reject it unless it's signed by |
| * a known good public key. |
| */ |
| typedef struct AvbVBMetaImageHeader { |
| /* 0: Four bytes equal to "AVB0" (AVB_MAGIC). */ |
| uint8_t magic[AVB_MAGIC_LEN]; |
| |
| /* 4: The major version of libavb required for this header. */ |
| uint32_t required_libavb_version_major; |
| /* 8: The minor version of libavb required for this header. */ |
| uint32_t required_libavb_version_minor; |
| |
| /* 12: The size of the signature block. */ |
| uint64_t authentication_data_block_size; |
| /* 20: The size of the auxiliary data block. */ |
| uint64_t auxiliary_data_block_size; |
| |
| /* 28: The verification algorithm used, see |AvbAlgorithmType| enum. */ |
| uint32_t algorithm_type; |
| |
| /* 32: Offset into the "Authentication data" block of hash data. */ |
| uint64_t hash_offset; |
| /* 40: Length of the hash data. */ |
| uint64_t hash_size; |
| |
| /* 48: Offset into the "Authentication data" block of signature data. */ |
| uint64_t signature_offset; |
| /* 56: Length of the signature data. */ |
| uint64_t signature_size; |
| |
| /* 64: Offset into the "Auxiliary data" block of public key data. */ |
| uint64_t public_key_offset; |
| /* 72: Length of the public key data. */ |
| uint64_t public_key_size; |
| |
| /* 80: Offset into the "Auxiliary data" block of public key metadata. */ |
| uint64_t public_key_metadata_offset; |
| /* 88: Length of the public key metadata. Must be set to zero if there |
| * is no public key metadata. |
| */ |
| uint64_t public_key_metadata_size; |
| |
| /* 96: Offset into the "Auxiliary data" block of descriptor data. */ |
| uint64_t descriptors_offset; |
| /* 104: Length of descriptor data. */ |
| uint64_t descriptors_size; |
| |
| /* 112: The rollback index which can be used to prevent rollback to |
| * older versions. |
| */ |
| uint64_t rollback_index; |
| |
| /* 120: Flags from the AvbVBMetaImageFlags enumeration. This must be |
| * set to zero if the vbmeta image is not a top-level image. |
| */ |
| uint32_t flags; |
| |
| /* 124: The location of the rollback index defined in this header. |
| * Only valid for the main vbmeta. For chained partitions, the rollback |
| * index location must be specified in the AvbChainPartitionDescriptor |
| * and this value must be set to 0. |
| */ |
| uint32_t rollback_index_location; |
| |
| /* 128: The release string from avbtool, e.g. "avbtool 1.0.0" or |
| * "avbtool 1.0.0 xyz_board Git-234abde89". Is guaranteed to be NUL |
| * terminated. Applications must not make assumptions about how this |
| * string is formatted. |
| */ |
| uint8_t release_string[AVB_RELEASE_STRING_SIZE]; |
| |
| /* 176: Padding to ensure struct is size AVB_VBMETA_IMAGE_HEADER_SIZE |
| * bytes. This must be set to zeroes. |
| */ |
| uint8_t reserved[80]; |
| } AVB_ATTR_PACKED AvbVBMetaImageHeader; |
| |
| /* Copies |src| to |dest|, byte-swapping fields in the process. |
| * |
| * Make sure you've verified |src| using avb_vbmeta_image_verify() |
| * before accessing the data and/or using this function. |
| */ |
| void avb_vbmeta_image_header_to_host_byte_order(const AvbVBMetaImageHeader* src, |
| AvbVBMetaImageHeader* dest); |
| |
| /* Return codes used in avb_vbmeta_image_verify(). |
| * |
| * AVB_VBMETA_VERIFY_RESULT_OK is returned if the vbmeta image header |
| * is valid, the hash is correct and the signature is correct. Keep in |
| * mind that you still need to check that you know the public key used |
| * to sign the image, see avb_vbmeta_image_verify() for details. |
| * |
| * AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED is returned if the vbmeta |
| * image header is valid but there is no signature or hash. |
| * |
| * AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER is returned if the |
| * header of the vbmeta image is invalid, for example, invalid magic |
| * or inconsistent data. |
| * |
| * AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION is returned if a) the |
| * vbmeta image requires a minimum version of libavb which exceeds the |
| * version of libavb used; or b) the vbmeta image major version |
| * differs from the major version of libavb in use. |
| * |
| * AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH is returned if the hash |
| * stored in the "Authentication data" block does not match the |
| * calculated hash. |
| * |
| * AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH is returned if the |
| * signature stored in the "Authentication data" block is invalid or |
| * doesn't match the public key stored in the vbmeta image. |
| */ |
| typedef enum { |
| AVB_VBMETA_VERIFY_RESULT_OK, |
| AVB_VBMETA_VERIFY_RESULT_OK_NOT_SIGNED, |
| AVB_VBMETA_VERIFY_RESULT_INVALID_VBMETA_HEADER, |
| AVB_VBMETA_VERIFY_RESULT_UNSUPPORTED_VERSION, |
| AVB_VBMETA_VERIFY_RESULT_HASH_MISMATCH, |
| AVB_VBMETA_VERIFY_RESULT_SIGNATURE_MISMATCH, |
| } AvbVBMetaVerifyResult; |
| |
| /* Get a textual representation of |result|. */ |
| const char* avb_vbmeta_verify_result_to_string(AvbVBMetaVerifyResult result); |
| |
| /* Checks that vbmeta image at |data| of size |length| is a valid |
| * vbmeta image. The complete contents of the vbmeta image must be |
| * passed in. It's fine if |length| is bigger than the actual image, |
| * typically callers of this function will load the entire contents of |
| * the 'vbmeta_a' or 'vbmeta_b' partition and pass in its length (for |
| * example, 1 MiB). |
| * |
| * See the |AvbVBMetaImageHeader| struct for information about the |
| * three blocks (header, authentication, auxiliary) that make up a |
| * vbmeta image. |
| * |
| * If the function returns |AVB_VBMETA_VERIFY_RESULT_OK| and |
| * |out_public_key_data| is non-NULL, it will be set to point inside |
| * |data| for where the serialized public key data is stored and |
| * |out_public_key_length|, if non-NULL, will be set to the length of |
| * the public key data. If there is no public key in the metadata then |
| * |out_public_key_data| is set to NULL. |
| * |
| * See the |AvbVBMetaVerifyResult| enum for possible return values. |
| * |
| * VERY IMPORTANT: |
| * |
| * 1. Even if |AVB_VBMETA_VERIFY_RESULT_OK| is returned, you still |
| * need to check that the public key embedded in the image |
| * matches a known key! You can use 'avbtool extract_public_key' |
| * to extract the key (at build time, then store it along your |
| * code) and compare it to what is returned in |
| * |out_public_key_data|. |
| * |
| * 2. You need to check the |rollback_index| field against a stored |
| * value in NVRAM and reject the vbmeta image if the value in |
| * NVRAM is bigger than |rollback_index|. You must also update |
| * the value stored in NVRAM to the smallest value of |
| * |rollback_index| field from boot images in all bootable and |
| * authentic slots marked as GOOD. |
| * |
| * This is a low-level function to only verify the vbmeta data - you |
| * are likely looking for avb_slot_verify() instead for verifying |
| * integrity data for a whole set of partitions. |
| */ |
| AvbVBMetaVerifyResult avb_vbmeta_image_verify( |
| const uint8_t* data, |
| size_t length, |
| const uint8_t** out_public_key_data, |
| size_t* out_public_key_length) AVB_ATTR_WARN_UNUSED_RESULT; |
| |
| #ifdef __cplusplus |
| } |
| #endif |
| |
| #endif /* AVB_VBMETA_IMAGE_H_ */ |