1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
|
/*
* img4.c
* Functions for handling the new IMG4 format
*
* Copyright (c) 2013 Nikias Bassen. All Rights Reserved.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* This library is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*/
#include <stdlib.h>
#include <string.h>
#include "img4.h"
#define ASN1_CONSTRUCTED 0x20
#define ASN1_SEQUENCE 0x10
#define ASN1_CONTEXT_SPECIFIC 0x80
#define ASN1_IA5_STRING 0x16
#define IMG4_MAGIC "IMG4"
#define IMG4_MAGIC_SIZE 4
static unsigned char* asn1_create_element_header(unsigned char type, unsigned int size, unsigned char** data, unsigned int *data_size)
{
unsigned char buf[6];
unsigned int off = 0;
if (!type || size == 0 || !data || !data_size) {
return NULL;
}
buf[off++] = type;
// first, calculate the size
if (size >= 0x1000000) {
// 1+4 bytes length
buf[off++] = 0x84;
buf[off++] = (size >> 24) & 0xFF;
buf[off++] = (size >> 16) & 0xFF;
buf[off++] = (size >> 8) & 0xFF;
buf[off++] = size & 0xFF;
} else if (size >= 0x10000) {
// 1+3 bytes length
buf[off++] = 0x83;
buf[off++] = (size >> 16) & 0xFF;
buf[off++] = (size >> 8) & 0xFF;
buf[off++] = size & 0xFF;
} else if (size >= 0x100) {
// 1+2 bytes length
buf[off++] = 0x82;
buf[off++] = (size >> 8) & 0xFF;
buf[off++] = (size & 0xFF);
} else if (size >= 0x80) {
// 1+1 byte length
buf[off++] = 0x81;
buf[off++] = (size & 0xFF);
} else {
// 1 byte length
buf[off++] = size & 0xFF;
}
*data = malloc(off);
memcpy(*data, buf, off);
*data_size = off;
return *data;
}
int img4_stitch_component(const char* component_name, const unsigned char* component_data, unsigned int component_size, const unsigned char* blob, unsigned int blob_size, unsigned char** img4_data, unsigned int *img4_size)
{
unsigned char* magic_header = NULL;
unsigned int magic_header_size = 0;
unsigned char* blob_header = NULL;
unsigned int blob_header_size = 0;
unsigned char* img4header = NULL;
unsigned int img4header_size = 0;
unsigned int content_size;
unsigned char* outbuf;
unsigned char* p;
if (!component_name || !component_data || component_size == 0 || !blob || blob_size == 0 || !img4_data || !img4_size) {
return -1;
}
/* first we need check if we have to change the tag for the given component */
// FIXME: write proper ASN1 handling code for this
if (strcmp(component_name, "RestoreKernelCache") == 0) {
memcpy((char*)component_data+0xD, "rkrn", 4);
} else if (strcmp(component_name, "RestoreDeviceTree") == 0) {
memcpy((char*)component_data+0xD, "rdtr", 4);
} else if (strcmp(component_name, "RestoreSEP") == 0) {
memcpy((char*)component_data+0xD, "rsep", 4);
}
// create element header for the "IMG4" magic
asn1_create_element_header(ASN1_IA5_STRING, IMG4_MAGIC_SIZE, &magic_header, &magic_header_size);
// create element header for the blob (ApImg4Ticket)
asn1_create_element_header(ASN1_CONTEXT_SPECIFIC|ASN1_CONSTRUCTED, blob_size, &blob_header, &blob_header_size);
// calculate the size for the final IMG4 file (asn1 sequence)
content_size = magic_header_size + IMG4_MAGIC_SIZE + component_size + blob_header_size + blob_size;
// create element header for the final IMG4 asn1 blob
asn1_create_element_header(ASN1_SEQUENCE|ASN1_CONSTRUCTED, content_size, &img4header, &img4header_size);
outbuf = (unsigned char*)malloc(img4header_size + content_size);
if (!outbuf) {
if (magic_header) {
free(magic_header);
}
if (blob_header) {
free(blob_header);
}
if (img4header) {
free(img4header);
}
return -1;
}
p = outbuf;
// now put everything together
memcpy(p, img4header, img4header_size);
p += img4header_size;
memcpy(p, magic_header, magic_header_size);
p += magic_header_size;
memcpy(p, IMG4_MAGIC, IMG4_MAGIC_SIZE);
p += IMG4_MAGIC_SIZE;
memcpy(p, component_data, component_size);
p += component_size;
memcpy(p, blob_header, blob_header_size);
p += blob_header_size;
memcpy(p, blob, blob_size);
p += blob_size;
*img4_data = outbuf;
*img4_size = (p - outbuf);
if (magic_header) {
free(magic_header);
}
if (blob_header) {
free(blob_header);
}
if (img4header) {
free(img4header);
}
return 0;
}
|
