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
|
#include <errno.h>
#include <stdio.h>
#include <stdint.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ioctl.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <linux/fs.h>
static int set_immutable(const char *path, int immutable)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
if (immutable)
flags |= FS_IMMUTABLE_FL;
else
flags &= ~FS_IMMUTABLE_FL;
rc = ioctl(fd, FS_IOC_SETFLAGS, &flags);
error = errno;
close(fd);
errno = error;
return rc;
}
static int get_immutable(const char *path)
{
unsigned int flags;
int fd;
int rc;
int error;
fd = open(path, O_RDONLY);
if (fd < 0)
return fd;
rc = ioctl(fd, FS_IOC_GETFLAGS, &flags);
if (rc < 0) {
error = errno;
close(fd);
errno = error;
return rc;
}
close(fd);
if (flags & FS_IMMUTABLE_FL)
return 1;
return 0;
}
int main(int argc, char **argv)
{
const char *path;
char buf[5];
int fd, rc;
if (argc < 2) {
fprintf(stderr, "usage: %s <path>\n", argv[0]);
return EXIT_FAILURE;
}
path = argv[1];
/* attributes: EFI_VARIABLE_NON_VOLATILE |
* EFI_VARIABLE_BOOTSERVICE_ACCESS |
* EFI_VARIABLE_RUNTIME_ACCESS
*/
*(uint32_t *)buf = 0x7;
buf[4] = 0;
/* create a test variable */
fd = open(path, O_WRONLY | O_CREAT, 0600);
if (fd < 0) {
perror("open(O_WRONLY)");
return EXIT_FAILURE;
}
rc = write(fd, buf, sizeof(buf));
if (rc != sizeof(buf)) {
perror("write");
return EXIT_FAILURE;
}
close(fd);
rc = get_immutable(path);
if (rc < 0) {
perror("ioctl(FS_IOC_GETFLAGS)");
return EXIT_FAILURE;
} else if (rc) {
rc = set_immutable(path, 0);
if (rc < 0) {
perror("ioctl(FS_IOC_SETFLAGS)");
return EXIT_FAILURE;
}
}
fd = open(path, O_RDONLY);
if (fd < 0) {
perror("open");
return EXIT_FAILURE;
}
if (unlink(path) < 0) {
perror("unlink");
return EXIT_FAILURE;
}
rc = read(fd, buf, sizeof(buf));
if (rc > 0) {
fprintf(stderr, "reading from an unlinked variable "
"shouldn't be possible\n");
return EXIT_FAILURE;
}
return EXIT_SUCCESS;
}
|
