1 | // SPDX-License-Identifier: GPL-2.0 |
2 | #include <errno.h> |
3 | #include <stdio.h> |
4 | #include <stdint.h> |
5 | #include <stdlib.h> |
6 | #include <unistd.h> |
7 | #include <sys/ioctl.h> |
8 | #include <sys/types.h> |
9 | #include <sys/stat.h> |
10 | #include <fcntl.h> |
11 | #include <linux/fs.h> |
12 | |
13 | static int set_immutable(const char *path, int immutable) |
14 | { |
15 | unsigned int flags; |
16 | int fd; |
17 | int rc; |
18 | int error; |
19 | |
20 | fd = open(path, O_RDONLY); |
21 | if (fd < 0) |
22 | return fd; |
23 | |
24 | rc = ioctl(fd, FS_IOC_GETFLAGS, &flags); |
25 | if (rc < 0) { |
26 | error = errno; |
27 | close(fd); |
28 | errno = error; |
29 | return rc; |
30 | } |
31 | |
32 | if (immutable) |
33 | flags |= FS_IMMUTABLE_FL; |
34 | else |
35 | flags &= ~FS_IMMUTABLE_FL; |
36 | |
37 | rc = ioctl(fd, FS_IOC_SETFLAGS, &flags); |
38 | error = errno; |
39 | close(fd); |
40 | errno = error; |
41 | return rc; |
42 | } |
43 | |
44 | static int get_immutable(const char *path) |
45 | { |
46 | unsigned int flags; |
47 | int fd; |
48 | int rc; |
49 | int error; |
50 | |
51 | fd = open(path, O_RDONLY); |
52 | if (fd < 0) |
53 | return fd; |
54 | |
55 | rc = ioctl(fd, FS_IOC_GETFLAGS, &flags); |
56 | if (rc < 0) { |
57 | error = errno; |
58 | close(fd); |
59 | errno = error; |
60 | return rc; |
61 | } |
62 | close(fd); |
63 | if (flags & FS_IMMUTABLE_FL) |
64 | return 1; |
65 | return 0; |
66 | } |
67 | |
68 | int main(int argc, char **argv) |
69 | { |
70 | const char *path; |
71 | char buf[5]; |
72 | int fd, rc; |
73 | |
74 | if (argc < 2) { |
75 | fprintf(stderr, "usage: %s <path>\n" , argv[0]); |
76 | return EXIT_FAILURE; |
77 | } |
78 | |
79 | path = argv[1]; |
80 | |
81 | /* attributes: EFI_VARIABLE_NON_VOLATILE | |
82 | * EFI_VARIABLE_BOOTSERVICE_ACCESS | |
83 | * EFI_VARIABLE_RUNTIME_ACCESS |
84 | */ |
85 | *(uint32_t *)buf = 0x7; |
86 | buf[4] = 0; |
87 | |
88 | /* create a test variable */ |
89 | fd = open(path, O_WRONLY | O_CREAT, 0600); |
90 | if (fd < 0) { |
91 | perror("open(O_WRONLY)" ); |
92 | return EXIT_FAILURE; |
93 | } |
94 | |
95 | rc = write(fd, buf, sizeof(buf)); |
96 | if (rc != sizeof(buf)) { |
97 | perror("write" ); |
98 | return EXIT_FAILURE; |
99 | } |
100 | |
101 | close(fd); |
102 | |
103 | rc = get_immutable(path); |
104 | if (rc < 0) { |
105 | perror("ioctl(FS_IOC_GETFLAGS)" ); |
106 | return EXIT_FAILURE; |
107 | } else if (rc) { |
108 | rc = set_immutable(path, immutable: 0); |
109 | if (rc < 0) { |
110 | perror("ioctl(FS_IOC_SETFLAGS)" ); |
111 | return EXIT_FAILURE; |
112 | } |
113 | } |
114 | |
115 | fd = open(path, O_RDONLY); |
116 | if (fd < 0) { |
117 | perror("open" ); |
118 | return EXIT_FAILURE; |
119 | } |
120 | |
121 | if (unlink(path) < 0) { |
122 | perror("unlink" ); |
123 | return EXIT_FAILURE; |
124 | } |
125 | |
126 | rc = read(fd, buf, sizeof(buf)); |
127 | if (rc > 0) { |
128 | fprintf(stderr, "reading from an unlinked variable " |
129 | "shouldn't be possible\n" ); |
130 | return EXIT_FAILURE; |
131 | } |
132 | |
133 | return EXIT_SUCCESS; |
134 | } |
135 | |