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
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
|
/* Copyright 2015 The Chromium OS Authors. All rights reserved.
* Use of this source code is governed by a BSD-style license that can be
* found in the LICENSE file.
*
* This utility wraps around "cgpt" execution to work with NAND. If the target
* device is an MTD device, this utility will read the GPT structures from
* FMAP, invokes "cgpt" on that, and writes the result back to NOR flash. */
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <inttypes.h>
#include <limits.h>
#include <linux/major.h>
#include <stdbool.h>
#include <stdlib.h>
#include <stdint.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/sysmacros.h>
#include <sys/types.h>
#include <unistd.h>
#include "2sysincludes.h"
#include "2common.h"
#include "2sha.h"
#include "cgpt.h"
#include "cgpt_nor.h"
#include "file_keys.h"
// Check if cmdline |argv| has "-D". "-D" signifies that GPT structs are stored
// off device, and hence we should not wrap around cgpt.
static bool has_dash_D(int argc, const char *const argv[]) {
int i;
// We go from 2, because the second arg is a cgpt command such as "create".
for (i = 2; i < argc; ++i) {
if (strcmp("-D", argv[i]) == 0) {
return true;
}
}
return false;
}
// Check if |device_path| is an MTD device based on its major number being 90.
static bool is_mtd(const char *device_path) {
struct stat stat;
if (lstat(device_path, &stat) != 0) {
return false;
}
if (major(stat.st_rdev) != MTD_CHAR_MAJOR) {
return false;
}
return true;
}
// Return the element in |argv| that is an MTD device.
static const char *find_mtd_device(int argc, const char *const argv[]) {
int i;
for (i = 2; i < argc; ++i) {
if (is_mtd(argv[i])) {
return argv[i];
}
}
return NULL;
}
static int wrap_cgpt(int argc,
const char *const argv[],
const char *mtd_device) {
uint8_t original_hash[VB2_SHA1_DIGEST_SIZE];
uint8_t modified_hash[VB2_SHA1_DIGEST_SIZE];
int ret = 0;
// Create a temp dir to work in.
ret++;
char temp_dir[] = "/tmp/cgpt_wrapper.XXXXXX";
if (ReadNorFlash(temp_dir) != 0) {
return ret;
}
char rw_gpt_path[PATH_MAX];
if (snprintf(rw_gpt_path, sizeof(rw_gpt_path), "%s/rw_gpt", temp_dir) < 0) {
goto cleanup;
}
if (VB2_SUCCESS != DigestFile(rw_gpt_path, VB2_HASH_SHA1,
original_hash, sizeof(original_hash))) {
Error("Cannot compute original GPT digest.\n");
goto cleanup;
}
// Obtain the MTD size.
ret++;
uint64_t drive_size = 0;
if (GetMtdSize(mtd_device, &drive_size) != 0) {
Error("Cannot get the size of %s.\n", mtd_device);
goto cleanup;
}
// Launch cgpt on "rw_gpt" with -D size.
ret++;
const char** my_argv = calloc(argc + 2 + 1, sizeof(char *));
if (my_argv == NULL) {
errno = ENOMEM;
goto cleanup;
}
memcpy(my_argv, argv, sizeof(char *) * argc);
char *real_cgpt;
if (asprintf(&real_cgpt, "%s.bin", argv[0]) == -1) {
free(my_argv);
goto cleanup;
}
my_argv[0] = real_cgpt;
int i;
for (i = 2; i < argc; ++i) {
if (strcmp(my_argv[i], mtd_device) == 0) {
my_argv[i] = rw_gpt_path;
}
}
my_argv[argc] = "-D";
char size[32];
snprintf(size, sizeof(size), "%" PRIu64, drive_size);
my_argv[argc + 1] = size;
i = ForkExecV(NULL, my_argv);
free(real_cgpt);
free(my_argv);
if (i != 0) {
Error("Cannot exec cgpt to modify rw_gpt.\n");
goto cleanup;
}
// Write back "rw_gpt" to NOR flash in two chunks.
ret++;
if (VB2_SUCCESS == DigestFile(rw_gpt_path, VB2_HASH_SHA1,
modified_hash, sizeof(modified_hash))) {
if (memcmp(original_hash, modified_hash, VB2_SHA1_DIGEST_SIZE) != 0) {
ret = WriteNorFlash(temp_dir);
} else {
ret = 0;
}
}
cleanup:
RemoveDir(temp_dir);
return ret;
}
int main(int argc, const char *argv[]) {
char resolved_cgpt[PATH_MAX];
pid_t pid = getpid();
char exe_link[40];
int retval = 0;
if (argc < 1) {
return -1;
}
const char *orig_argv0 = argv[0];
snprintf(exe_link, sizeof(exe_link), "/proc/%d/exe", pid);
memset(resolved_cgpt, 0, sizeof(resolved_cgpt));
if (readlink(exe_link, resolved_cgpt, sizeof(resolved_cgpt) - 1) == -1) {
perror("readlink");
return -1;
}
argv[0] = resolved_cgpt;
if (argc > 2 && !has_dash_D(argc, argv)) {
const char *mtd_device = find_mtd_device(argc, argv);
if (mtd_device) {
retval = wrap_cgpt(argc, argv, mtd_device);
goto cleanup;
}
}
// Forward to cgpt as-is. Real cgpt has been renamed cgpt.bin.
char *real_cgpt;
if (asprintf(&real_cgpt, "%s.bin", argv[0]) == -1) {
retval = -1;
goto cleanup;
}
argv[0] = real_cgpt;
if (execv(argv[0], (char * const *)argv) == -1) {
err(-2, "execv(%s) failed", real_cgpt);
}
free(real_cgpt);
retval = -2;
cleanup:
argv[0] = orig_argv0;
return retval;
}
|
