1 /* SPDX-License-Identifier: MIT */
2 /*
3  * Copyright (C) 2016 The Android Open Source Project
4  */
5 
6 #if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION)
7 #error "Never include this file directly, include libavb.h instead."
8 #endif
9 
10 #ifndef AVB_HASH_DESCRIPTOR_H_
11 #define AVB_HASH_DESCRIPTOR_H_
12 
13 #include "avb_descriptor.h"
14 
15 #ifdef __cplusplus
16 extern "C" {
17 #endif
18 
19 /* Flags for hash descriptors.
20  *
21  * AVB_HASH_DESCRIPTOR_FLAGS_DO_NOT_USE_AB: Do not apply the default A/B
22  *   partition logic to this partition. This is intentionally a negative boolean
23  *   because A/B should be both the default and most used in practice.
24  */
25 typedef enum {
26   AVB_HASH_DESCRIPTOR_FLAGS_DO_NOT_USE_AB = (1 << 0),
27 } AvbHashDescriptorFlags;
28 
29 /* A descriptor containing information about hash for an image.
30  *
31  * This descriptor is typically used for boot partitions to verify the
32  * entire kernel+initramfs image before executing it.
33  *
34  * Following this struct are |partition_name_len| bytes of the
35  * partition name (UTF-8 encoded), |salt_len| bytes of salt, and then
36  * |digest_len| bytes of the digest.
37  *
38  * The |reserved| field is for future expansion and must be set to NUL
39  * bytes.
40  *
41  * Changes in v1.1:
42  *   - flags field is added which supports AVB_HASH_DESCRIPTOR_FLAGS_USE_AB
43  *   - digest_len may be zero, which indicates the use of a persistent digest
44  */
45 typedef struct AvbHashDescriptor {
46   AvbDescriptor parent_descriptor;
47   uint64_t image_size;
48   uint8_t hash_algorithm[32];
49   uint32_t partition_name_len;
50   uint32_t salt_len;
51   uint32_t digest_len;
52   uint32_t flags;
53   uint8_t reserved[60];
54 } AVB_ATTR_PACKED AvbHashDescriptor;
55 
56 /* Copies |src| to |dest| and validates, byte-swapping fields in the
57  * process if needed. Returns true if valid, false if invalid.
58  *
59  * Data following the struct is not validated nor copied.
60  */
61 bool avb_hash_descriptor_validate_and_byteswap(const AvbHashDescriptor* src,
62                                                AvbHashDescriptor* dest)
63     AVB_ATTR_WARN_UNUSED_RESULT;
64 
65 #ifdef __cplusplus
66 }
67 #endif
68 
69 #endif /* AVB_HASH_DESCRIPTOR_H_ */
70