path: root/libavb/avb_descriptor.h (plain)
blob: 5d0f0c699fe18f68d7504f2f9842a685ae3a53ec

1	/*
2	* Copyright (C) 2016 The Android Open Source Project
3	*
4	* Permission is hereby granted, free of charge, to any person
5	* obtaining a copy of this software and associated documentation
6	* files (the "Software"), to deal in the Software without
7	* restriction, including without limitation the rights to use, copy,
8	* modify, merge, publish, distribute, sublicense, and/or sell copies
9	* of the Software, and to permit persons to whom the Software is
10	* furnished to do so, subject to the following conditions:
11	*
12	* The above copyright notice and this permission notice shall be
13	* included in all copies or substantial portions of the Software.
14	*
15	* THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
16	* EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
17	* MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
18	* NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS
19	* BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN
20	* ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
21	* CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
22	* SOFTWARE.
23	*/
24
25	#if !defined(AVB_INSIDE_LIBAVB_H) && !defined(AVB_COMPILATION)
26	#error "Never include this file directly, include libavb.h instead."
27	#endif
28
29	#ifndef AVB_DESCRIPTOR_H_
30	#define AVB_DESCRIPTOR_H_
31
32	#include "avb_sysdeps.h"
33
34	#ifdef __cplusplus
35	extern "C" {
36	#endif
37
38	/* Well-known descriptor tags.
39	*
40	* AVB_DESCRIPTOR_TAG_PROPERTY: see |AvbPropertyDescriptor| struct.
41	* AVB_DESCRIPTOR_TAG_HASHTREE: see |AvbHashtreeDescriptor| struct.
42	* AVB_DESCRIPTOR_TAG_HASH: see |AvbHashDescriptor| struct.
43	* AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE: see |AvbKernelCmdlineDescriptor| struct.
44	* AVB_DESCRIPTOR_TAG_CHAIN_PARTITION: see |AvbChainPartitionDescriptor| struct.
45	*/
46	typedef enum {
47	AVB_DESCRIPTOR_TAG_PROPERTY,
48	AVB_DESCRIPTOR_TAG_HASHTREE,
49	AVB_DESCRIPTOR_TAG_HASH,
50	AVB_DESCRIPTOR_TAG_KERNEL_CMDLINE,
51	AVB_DESCRIPTOR_TAG_CHAIN_PARTITION,
52	} AvbDescriptorTag;
53
54	/* The header for a serialized descriptor.
55	*
56	* A descriptor always have two fields, a |tag| (denoting its type,
57	* see the |AvbDescriptorTag| enumeration) and the size of the bytes
58	* following, |num_bytes_following|.
59	*
60	* For padding, |num_bytes_following| is always a multiple of 8.
61	*/
62	typedef struct AvbDescriptor {
63	uint64_t tag;
64	uint64_t num_bytes_following;
65	} AVB_ATTR_PACKED AvbDescriptor;
66
67	/* Copies |src| to |dest| and validates, byte-swapping fields in the
68	* process if needed. Returns true if valid, false if invalid.
69	*
70	* Data following the struct is not validated nor copied.
71	*/
72	bool avb_descriptor_validate_and_byteswap(
73	const AvbDescriptor* src, AvbDescriptor* dest) AVB_ATTR_WARN_UNUSED_RESULT;
74
75	/* Signature for callback function used in avb_descriptor_foreach().
76	* The passed in descriptor is given by |descriptor| and the
77	* |user_data| passed to avb_descriptor_foreach() function is in
78	* |user_data|. Return true to continue iterating, false to stop
79	* iterating.
80	*
81	* Note that |descriptor| points into the image passed to
82	* avb_descriptor_foreach() - all fields need to be byteswapped!
83	*/
84	typedef bool AvbDescriptorForeachFunc(const AvbDescriptor* descriptor,
85	void* user_data);
86
87	/* Convenience function to iterate over all descriptors in an vbmeta
88	* image.
89	*
90	* The function given by |foreach_func| will be called for each
91	* descriptor. The given function should return true to continue
92	* iterating, false to stop.
93	*
94	* The |user_data| parameter will be passed to |foreach_func|.
95	*
96	* Returns false if the iteration was short-circuited, that is if
97	* an invocation of |foreach_func| returned false.
98	*
99	* Before using this function, you MUST verify |image_data| with
100	* avb_vbmeta_image_verify() and reject it unless it's signed by a known
101	* good public key. Additionally, |image_data| must be word-aligned.
102	*/
103	bool avb_descriptor_foreach(const uint8_t* image_data,
104	size_t image_size,
105	AvbDescriptorForeachFunc foreach_func,
106	void* user_data);
107
108	/* Gets all descriptors in a vbmeta image.
109	*
110	* The return value is a NULL-pointer terminated array of
111	* AvbDescriptor pointers. Free with avb_free() when you are done with
112	* it. If |out_num_descriptors| is non-NULL, the number of descriptors
113	* will be returned there.
114	*
115	* Note that each AvbDescriptor pointer in the array points into
116	* |image_data| - all fields need to be byteswapped!
117	*
118	* Before using this function, you MUST verify |image_data| with
119	* avb_vbmeta_image_verify() and reject it unless it's signed by a known
120	* good public key. Additionally, |image_data| must be word-aligned.
121	*/
122	const AvbDescriptor** avb_descriptor_get_all(const uint8_t* image_data,
123	size_t image_size,
124	size_t* out_num_descriptors)
125	AVB_ATTR_WARN_UNUSED_RESULT;
126
127	#ifdef __cplusplus
128	}
129	#endif
130
131	#endif /* AVB_DESCRIPTOR_H_ */
132