]>
Commit | Line | Data |
---|---|---|
b2441318 | 1 | // SPDX-License-Identifier: GPL-2.0 |
db181ce0 EB |
2 | #define _GNU_SOURCE |
3 | #include <sched.h> | |
4 | #include <stdio.h> | |
5 | #include <errno.h> | |
6 | #include <string.h> | |
7 | #include <sys/types.h> | |
8 | #include <sys/mount.h> | |
9 | #include <sys/wait.h> | |
4a44a19b EB |
10 | #include <sys/vfs.h> |
11 | #include <sys/statvfs.h> | |
db181ce0 EB |
12 | #include <stdlib.h> |
13 | #include <unistd.h> | |
14 | #include <fcntl.h> | |
15 | #include <grp.h> | |
16 | #include <stdbool.h> | |
17 | #include <stdarg.h> | |
18 | ||
19 | #ifndef CLONE_NEWNS | |
20 | # define CLONE_NEWNS 0x00020000 | |
21 | #endif | |
22 | #ifndef CLONE_NEWUTS | |
23 | # define CLONE_NEWUTS 0x04000000 | |
24 | #endif | |
25 | #ifndef CLONE_NEWIPC | |
26 | # define CLONE_NEWIPC 0x08000000 | |
27 | #endif | |
28 | #ifndef CLONE_NEWNET | |
29 | # define CLONE_NEWNET 0x40000000 | |
30 | #endif | |
31 | #ifndef CLONE_NEWUSER | |
32 | # define CLONE_NEWUSER 0x10000000 | |
33 | #endif | |
34 | #ifndef CLONE_NEWPID | |
35 | # define CLONE_NEWPID 0x20000000 | |
36 | #endif | |
37 | ||
4a44a19b EB |
38 | #ifndef MS_REC |
39 | # define MS_REC 16384 | |
40 | #endif | |
db181ce0 | 41 | #ifndef MS_RELATIME |
4a44a19b | 42 | # define MS_RELATIME (1 << 21) |
db181ce0 EB |
43 | #endif |
44 | #ifndef MS_STRICTATIME | |
4a44a19b | 45 | # define MS_STRICTATIME (1 << 24) |
db181ce0 EB |
46 | #endif |
47 | ||
48 | static void die(char *fmt, ...) | |
49 | { | |
50 | va_list ap; | |
51 | va_start(ap, fmt); | |
52 | vfprintf(stderr, fmt, ap); | |
53 | va_end(ap); | |
54 | exit(EXIT_FAILURE); | |
55 | } | |
56 | ||
db86da7c | 57 | static void vmaybe_write_file(bool enoent_ok, char *filename, char *fmt, va_list ap) |
db181ce0 EB |
58 | { |
59 | char buf[4096]; | |
60 | int fd; | |
61 | ssize_t written; | |
62 | int buf_len; | |
db181ce0 | 63 | |
db181ce0 | 64 | buf_len = vsnprintf(buf, sizeof(buf), fmt, ap); |
db181ce0 EB |
65 | if (buf_len < 0) { |
66 | die("vsnprintf failed: %s\n", | |
67 | strerror(errno)); | |
68 | } | |
69 | if (buf_len >= sizeof(buf)) { | |
70 | die("vsnprintf output truncated\n"); | |
71 | } | |
72 | ||
73 | fd = open(filename, O_WRONLY); | |
74 | if (fd < 0) { | |
db86da7c EB |
75 | if ((errno == ENOENT) && enoent_ok) |
76 | return; | |
db181ce0 EB |
77 | die("open of %s failed: %s\n", |
78 | filename, strerror(errno)); | |
79 | } | |
80 | written = write(fd, buf, buf_len); | |
81 | if (written != buf_len) { | |
82 | if (written >= 0) { | |
83 | die("short write to %s\n", filename); | |
84 | } else { | |
85 | die("write to %s failed: %s\n", | |
86 | filename, strerror(errno)); | |
87 | } | |
88 | } | |
89 | if (close(fd) != 0) { | |
90 | die("close of %s failed: %s\n", | |
91 | filename, strerror(errno)); | |
92 | } | |
93 | } | |
94 | ||
db86da7c EB |
95 | static void maybe_write_file(char *filename, char *fmt, ...) |
96 | { | |
97 | va_list ap; | |
98 | ||
99 | va_start(ap, fmt); | |
100 | vmaybe_write_file(true, filename, fmt, ap); | |
101 | va_end(ap); | |
102 | ||
103 | } | |
104 | ||
105 | static void write_file(char *filename, char *fmt, ...) | |
106 | { | |
107 | va_list ap; | |
108 | ||
109 | va_start(ap, fmt); | |
110 | vmaybe_write_file(false, filename, fmt, ap); | |
111 | va_end(ap); | |
112 | ||
113 | } | |
114 | ||
4a44a19b EB |
115 | static int read_mnt_flags(const char *path) |
116 | { | |
117 | int ret; | |
118 | struct statvfs stat; | |
119 | int mnt_flags; | |
120 | ||
121 | ret = statvfs(path, &stat); | |
122 | if (ret != 0) { | |
123 | die("statvfs of %s failed: %s\n", | |
124 | path, strerror(errno)); | |
125 | } | |
126 | if (stat.f_flag & ~(ST_RDONLY | ST_NOSUID | ST_NODEV | \ | |
127 | ST_NOEXEC | ST_NOATIME | ST_NODIRATIME | ST_RELATIME | \ | |
128 | ST_SYNCHRONOUS | ST_MANDLOCK)) { | |
129 | die("Unrecognized mount flags\n"); | |
130 | } | |
131 | mnt_flags = 0; | |
132 | if (stat.f_flag & ST_RDONLY) | |
133 | mnt_flags |= MS_RDONLY; | |
134 | if (stat.f_flag & ST_NOSUID) | |
135 | mnt_flags |= MS_NOSUID; | |
136 | if (stat.f_flag & ST_NODEV) | |
137 | mnt_flags |= MS_NODEV; | |
138 | if (stat.f_flag & ST_NOEXEC) | |
139 | mnt_flags |= MS_NOEXEC; | |
140 | if (stat.f_flag & ST_NOATIME) | |
141 | mnt_flags |= MS_NOATIME; | |
142 | if (stat.f_flag & ST_NODIRATIME) | |
143 | mnt_flags |= MS_NODIRATIME; | |
144 | if (stat.f_flag & ST_RELATIME) | |
145 | mnt_flags |= MS_RELATIME; | |
146 | if (stat.f_flag & ST_SYNCHRONOUS) | |
147 | mnt_flags |= MS_SYNCHRONOUS; | |
148 | if (stat.f_flag & ST_MANDLOCK) | |
149 | mnt_flags |= ST_MANDLOCK; | |
150 | ||
151 | return mnt_flags; | |
152 | } | |
153 | ||
db181ce0 EB |
154 | static void create_and_enter_userns(void) |
155 | { | |
156 | uid_t uid; | |
157 | gid_t gid; | |
158 | ||
159 | uid = getuid(); | |
160 | gid = getgid(); | |
161 | ||
162 | if (unshare(CLONE_NEWUSER) !=0) { | |
163 | die("unshare(CLONE_NEWUSER) failed: %s\n", | |
164 | strerror(errno)); | |
165 | } | |
166 | ||
db86da7c | 167 | maybe_write_file("/proc/self/setgroups", "deny"); |
db181ce0 EB |
168 | write_file("/proc/self/uid_map", "0 %d 1", uid); |
169 | write_file("/proc/self/gid_map", "0 %d 1", gid); | |
170 | ||
db181ce0 EB |
171 | if (setgid(0) != 0) { |
172 | die ("setgid(0) failed %s\n", | |
173 | strerror(errno)); | |
174 | } | |
175 | if (setuid(0) != 0) { | |
176 | die("setuid(0) failed %s\n", | |
177 | strerror(errno)); | |
178 | } | |
179 | } | |
180 | ||
181 | static | |
4a44a19b EB |
182 | bool test_unpriv_remount(const char *fstype, const char *mount_options, |
183 | int mount_flags, int remount_flags, int invalid_flags) | |
db181ce0 EB |
184 | { |
185 | pid_t child; | |
186 | ||
187 | child = fork(); | |
188 | if (child == -1) { | |
189 | die("fork failed: %s\n", | |
190 | strerror(errno)); | |
191 | } | |
192 | if (child != 0) { /* parent */ | |
193 | pid_t pid; | |
194 | int status; | |
195 | pid = waitpid(child, &status, 0); | |
196 | if (pid == -1) { | |
197 | die("waitpid failed: %s\n", | |
198 | strerror(errno)); | |
199 | } | |
200 | if (pid != child) { | |
201 | die("waited for %d got %d\n", | |
202 | child, pid); | |
203 | } | |
204 | if (!WIFEXITED(status)) { | |
205 | die("child did not terminate cleanly\n"); | |
206 | } | |
207 | return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false; | |
208 | } | |
209 | ||
210 | create_and_enter_userns(); | |
211 | if (unshare(CLONE_NEWNS) != 0) { | |
212 | die("unshare(CLONE_NEWNS) failed: %s\n", | |
213 | strerror(errno)); | |
214 | } | |
215 | ||
4a44a19b EB |
216 | if (mount("testing", "/tmp", fstype, mount_flags, mount_options) != 0) { |
217 | die("mount of %s with options '%s' on /tmp failed: %s\n", | |
218 | fstype, | |
219 | mount_options? mount_options : "", | |
220 | strerror(errno)); | |
db181ce0 EB |
221 | } |
222 | ||
223 | create_and_enter_userns(); | |
224 | ||
225 | if (unshare(CLONE_NEWNS) != 0) { | |
226 | die("unshare(CLONE_NEWNS) failed: %s\n", | |
227 | strerror(errno)); | |
228 | } | |
229 | ||
230 | if (mount("/tmp", "/tmp", "none", | |
231 | MS_REMOUNT | MS_BIND | remount_flags, NULL) != 0) { | |
232 | /* system("cat /proc/self/mounts"); */ | |
233 | die("remount of /tmp failed: %s\n", | |
234 | strerror(errno)); | |
235 | } | |
236 | ||
237 | if (mount("/tmp", "/tmp", "none", | |
238 | MS_REMOUNT | MS_BIND | invalid_flags, NULL) == 0) { | |
239 | /* system("cat /proc/self/mounts"); */ | |
240 | die("remount of /tmp with invalid flags " | |
241 | "succeeded unexpectedly\n"); | |
242 | } | |
243 | exit(EXIT_SUCCESS); | |
244 | } | |
245 | ||
246 | static bool test_unpriv_remount_simple(int mount_flags) | |
247 | { | |
4a44a19b | 248 | return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags, 0); |
db181ce0 EB |
249 | } |
250 | ||
251 | static bool test_unpriv_remount_atime(int mount_flags, int invalid_flags) | |
252 | { | |
4a44a19b EB |
253 | return test_unpriv_remount("ramfs", NULL, mount_flags, mount_flags, |
254 | invalid_flags); | |
255 | } | |
256 | ||
257 | static bool test_priv_mount_unpriv_remount(void) | |
258 | { | |
259 | pid_t child; | |
260 | int ret; | |
261 | const char *orig_path = "/dev"; | |
262 | const char *dest_path = "/tmp"; | |
263 | int orig_mnt_flags, remount_mnt_flags; | |
264 | ||
265 | child = fork(); | |
266 | if (child == -1) { | |
267 | die("fork failed: %s\n", | |
268 | strerror(errno)); | |
269 | } | |
270 | if (child != 0) { /* parent */ | |
271 | pid_t pid; | |
272 | int status; | |
273 | pid = waitpid(child, &status, 0); | |
274 | if (pid == -1) { | |
275 | die("waitpid failed: %s\n", | |
276 | strerror(errno)); | |
277 | } | |
278 | if (pid != child) { | |
279 | die("waited for %d got %d\n", | |
280 | child, pid); | |
281 | } | |
282 | if (!WIFEXITED(status)) { | |
283 | die("child did not terminate cleanly\n"); | |
284 | } | |
285 | return WEXITSTATUS(status) == EXIT_SUCCESS ? true : false; | |
286 | } | |
287 | ||
288 | orig_mnt_flags = read_mnt_flags(orig_path); | |
289 | ||
290 | create_and_enter_userns(); | |
291 | ret = unshare(CLONE_NEWNS); | |
292 | if (ret != 0) { | |
293 | die("unshare(CLONE_NEWNS) failed: %s\n", | |
294 | strerror(errno)); | |
295 | } | |
296 | ||
297 | ret = mount(orig_path, dest_path, "bind", MS_BIND | MS_REC, NULL); | |
298 | if (ret != 0) { | |
299 | die("recursive bind mount of %s onto %s failed: %s\n", | |
300 | orig_path, dest_path, strerror(errno)); | |
301 | } | |
302 | ||
303 | ret = mount(dest_path, dest_path, "none", | |
304 | MS_REMOUNT | MS_BIND | orig_mnt_flags , NULL); | |
305 | if (ret != 0) { | |
306 | /* system("cat /proc/self/mounts"); */ | |
307 | die("remount of /tmp failed: %s\n", | |
308 | strerror(errno)); | |
309 | } | |
310 | ||
311 | remount_mnt_flags = read_mnt_flags(dest_path); | |
312 | if (orig_mnt_flags != remount_mnt_flags) { | |
313 | die("Mount flags unexpectedly changed during remount of %s originally mounted on %s\n", | |
314 | dest_path, orig_path); | |
315 | } | |
316 | exit(EXIT_SUCCESS); | |
db181ce0 EB |
317 | } |
318 | ||
319 | int main(int argc, char **argv) | |
320 | { | |
4a44a19b | 321 | if (!test_unpriv_remount_simple(MS_RDONLY)) { |
db181ce0 EB |
322 | die("MS_RDONLY malfunctions\n"); |
323 | } | |
4a44a19b | 324 | if (!test_unpriv_remount("devpts", "newinstance", MS_NODEV, MS_NODEV, 0)) { |
db181ce0 EB |
325 | die("MS_NODEV malfunctions\n"); |
326 | } | |
4a44a19b | 327 | if (!test_unpriv_remount_simple(MS_NOSUID)) { |
db181ce0 EB |
328 | die("MS_NOSUID malfunctions\n"); |
329 | } | |
4a44a19b | 330 | if (!test_unpriv_remount_simple(MS_NOEXEC)) { |
db181ce0 EB |
331 | die("MS_NOEXEC malfunctions\n"); |
332 | } | |
4a44a19b EB |
333 | if (!test_unpriv_remount_atime(MS_RELATIME, |
334 | MS_NOATIME)) | |
db181ce0 EB |
335 | { |
336 | die("MS_RELATIME malfunctions\n"); | |
337 | } | |
4a44a19b EB |
338 | if (!test_unpriv_remount_atime(MS_STRICTATIME, |
339 | MS_NOATIME)) | |
db181ce0 EB |
340 | { |
341 | die("MS_STRICTATIME malfunctions\n"); | |
342 | } | |
4a44a19b EB |
343 | if (!test_unpriv_remount_atime(MS_NOATIME, |
344 | MS_STRICTATIME)) | |
db181ce0 | 345 | { |
4a44a19b | 346 | die("MS_NOATIME malfunctions\n"); |
db181ce0 | 347 | } |
4a44a19b EB |
348 | if (!test_unpriv_remount_atime(MS_RELATIME|MS_NODIRATIME, |
349 | MS_NOATIME)) | |
db181ce0 | 350 | { |
4a44a19b | 351 | die("MS_RELATIME|MS_NODIRATIME malfunctions\n"); |
db181ce0 | 352 | } |
4a44a19b EB |
353 | if (!test_unpriv_remount_atime(MS_STRICTATIME|MS_NODIRATIME, |
354 | MS_NOATIME)) | |
db181ce0 | 355 | { |
4a44a19b | 356 | die("MS_STRICTATIME|MS_NODIRATIME malfunctions\n"); |
db181ce0 | 357 | } |
4a44a19b EB |
358 | if (!test_unpriv_remount_atime(MS_NOATIME|MS_NODIRATIME, |
359 | MS_STRICTATIME)) | |
db181ce0 | 360 | { |
4a44a19b | 361 | die("MS_NOATIME|MS_DIRATIME malfunctions\n"); |
db181ce0 | 362 | } |
4a44a19b | 363 | if (!test_unpriv_remount("ramfs", NULL, MS_STRICTATIME, 0, MS_NOATIME)) |
db181ce0 EB |
364 | { |
365 | die("Default atime malfunctions\n"); | |
366 | } | |
4a44a19b EB |
367 | if (!test_priv_mount_unpriv_remount()) { |
368 | die("Mount flags unexpectedly changed after remount\n"); | |
369 | } | |
db181ce0 EB |
370 | return EXIT_SUCCESS; |
371 | } |