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d7ccca2e LP |
1 | /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/ |
2 | ||
3 | /*** | |
4 | This file is part of systemd. | |
5 | ||
6 | Copyright 2010 Lennart Poettering | |
7 | ||
8 | systemd is free software; you can redistribute it and/or modify it | |
5430f7f2 LP |
9 | under the terms of the GNU Lesser General Public License as published by |
10 | the Free Software Foundation; either version 2.1 of the License, or | |
d7ccca2e LP |
11 | (at your option) any later version. |
12 | ||
13 | systemd is distributed in the hope that it will be useful, but | |
14 | WITHOUT ANY WARRANTY; without even the implied warranty of | |
15 | MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU | |
5430f7f2 | 16 | Lesser General Public License for more details. |
d7ccca2e | 17 | |
5430f7f2 | 18 | You should have received a copy of the GNU Lesser General Public License |
d7ccca2e LP |
19 | along with systemd; If not, see <http://www.gnu.org/licenses/>. |
20 | ***/ | |
21 | ||
22 | #include <unistd.h> | |
23 | #include <stdio.h> | |
24 | #include <errno.h> | |
25 | #include <string.h> | |
d7ccca2e LP |
26 | #include <fcntl.h> |
27 | #include <sys/mount.h> | |
28 | ||
73f860db | 29 | #include "systemd/sd-id128.h" |
81527be1 | 30 | |
b6e66135 | 31 | #include "machine-id-setup.h" |
d7ccca2e LP |
32 | #include "macro.h" |
33 | #include "util.h" | |
49e942b2 | 34 | #include "mkdir.h" |
d7ccca2e | 35 | #include "log.h" |
d4eb120a | 36 | #include "virt.h" |
a5c32cff | 37 | #include "fileio.h" |
fe970a8a | 38 | #include "path-util.h" |
0b452006 | 39 | #include "process-util.h" |
8d41a963 | 40 | |
34f750b7 | 41 | static int shorten_uuid(char destination[34], const char source[36]) { |
09b967ea LP |
42 | unsigned i, j; |
43 | ||
c6ac7e4b LP |
44 | assert(destination); |
45 | assert(source); | |
46 | ||
47 | /* Converts a UUID into a machine ID, by lowercasing it and | |
48 | * removing dashes. Validates everything. */ | |
49 | ||
09b967ea LP |
50 | for (i = 0, j = 0; i < 36 && j < 32; i++) { |
51 | int t; | |
52 | ||
53 | t = unhexchar(source[i]); | |
54 | if (t < 0) | |
55 | continue; | |
56 | ||
57 | destination[j++] = hexchar(t); | |
58 | } | |
59 | ||
c6ac7e4b LP |
60 | if (i != 36 || j != 32) |
61 | return -EINVAL; | |
62 | ||
63 | destination[32] = '\n'; | |
64 | destination[33] = 0; | |
65 | return 0; | |
66 | } | |
67 | ||
68 | static int read_machine_id(int fd, char id[34]) { | |
69 | char id_to_validate[34]; | |
70 | int r; | |
71 | ||
72 | assert(fd >= 0); | |
73 | assert(id); | |
74 | ||
75 | /* Reads a machine ID from a file, validates it, and returns | |
76 | * it. The returned ID ends in a newline. */ | |
77 | ||
78 | r = loop_read_exact(fd, id_to_validate, 33, false); | |
79 | if (r < 0) | |
80 | return r; | |
81 | ||
82 | if (id_to_validate[32] != '\n') | |
83 | return -EINVAL; | |
84 | ||
85 | id_to_validate[32] = 0; | |
86 | ||
87 | if (!id128_is_valid(id_to_validate)) | |
88 | return -EINVAL; | |
89 | ||
90 | memcpy(id, id_to_validate, 32); | |
91 | id[32] = '\n'; | |
92 | id[33] = 0; | |
93 | return 0; | |
94 | } | |
09b967ea | 95 | |
c6ac7e4b LP |
96 | static int write_machine_id(int fd, char id[34]) { |
97 | assert(fd >= 0); | |
98 | assert(id); | |
99 | ||
100 | if (lseek(fd, 0, SEEK_SET) < 0) | |
101 | return -errno; | |
102 | ||
103 | return loop_write(fd, id, 33, false); | |
09b967ea LP |
104 | } |
105 | ||
c6ac7e4b | 106 | static int generate_machine_id(char id[34], const char *root) { |
87d2c1ff LP |
107 | int fd, r; |
108 | unsigned char *p; | |
109 | sd_id128_t buf; | |
5dd6d0f8 | 110 | char *q; |
5dd6d0f8 | 111 | const char *vm_id, *dbus_machine_id; |
d7ccca2e LP |
112 | |
113 | assert(id); | |
114 | ||
5dd6d0f8 LP |
115 | if (isempty(root)) |
116 | dbus_machine_id = "/var/lib/dbus/machine-id"; | |
117 | else | |
63c372cb | 118 | dbus_machine_id = strjoina(root, "/var/lib/dbus/machine-id"); |
92f2f92e | 119 | |
d7ccca2e | 120 | /* First, try reading the D-Bus machine id, unless it is a symlink */ |
92f2f92e | 121 | fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); |
8d41a963 | 122 | if (fd >= 0) { |
c6ac7e4b | 123 | r = read_machine_id(fd, id); |
03e334a1 | 124 | safe_close(fd); |
d7ccca2e | 125 | |
c6ac7e4b LP |
126 | if (r >= 0) { |
127 | log_info("Initializing machine ID from D-Bus machine ID."); | |
128 | return 0; | |
d7ccca2e LP |
129 | } |
130 | } | |
131 | ||
5dd6d0f8 LP |
132 | if (isempty(root)) { |
133 | /* If that didn't work, see if we are running in a container, | |
134 | * and a machine ID was passed in via $container_uuid the way | |
135 | * libvirt/LXC does it */ | |
136 | r = detect_container(NULL); | |
ab94af92 | 137 | if (r > 0) { |
5dd6d0f8 | 138 | _cleanup_free_ char *e = NULL; |
0b36bbc4 | 139 | |
5dd6d0f8 LP |
140 | r = getenv_for_pid(1, "container_uuid", &e); |
141 | if (r > 0) { | |
c6ac7e4b LP |
142 | r = shorten_uuid(id, e); |
143 | if (r >= 0) { | |
144 | log_info("Initializing machine ID from container UUID."); | |
145 | return 0; | |
0b36bbc4 LP |
146 | } |
147 | } | |
5dd6d0f8 LP |
148 | |
149 | } else { | |
150 | /* If we are not running in a container, see if we are | |
151 | * running in qemu/kvm and a machine ID was passed in | |
152 | * via -uuid on the qemu/kvm command line */ | |
153 | ||
154 | r = detect_vm(&vm_id); | |
155 | if (r > 0 && streq(vm_id, "kvm")) { | |
a6dcc7e5 | 156 | char uuid[36]; |
5dd6d0f8 LP |
157 | |
158 | fd = open("/sys/class/dmi/id/product_uuid", O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); | |
159 | if (fd >= 0) { | |
a6dcc7e5 | 160 | r = loop_read_exact(fd, uuid, 36, false); |
5dd6d0f8 LP |
161 | safe_close(fd); |
162 | ||
a6dcc7e5 | 163 | if (r >= 0) { |
5dd6d0f8 LP |
164 | r = shorten_uuid(id, uuid); |
165 | if (r >= 0) { | |
166 | log_info("Initializing machine ID from KVM UUID."); | |
167 | return 0; | |
168 | } | |
169 | } | |
170 | } | |
171 | } | |
0b36bbc4 | 172 | } |
d4eb120a LP |
173 | } |
174 | ||
d7ccca2e | 175 | /* If that didn't work, generate a random machine id */ |
87d2c1ff | 176 | r = sd_id128_randomize(&buf); |
23bbb0de MS |
177 | if (r < 0) |
178 | return log_error_errno(r, "Failed to open /dev/urandom: %m"); | |
d7ccca2e | 179 | |
87d2c1ff | 180 | for (p = buf.bytes, q = id; p < buf.bytes + sizeof(buf); p++, q += 2) { |
d7ccca2e LP |
181 | q[0] = hexchar(*p >> 4); |
182 | q[1] = hexchar(*p & 15); | |
183 | } | |
184 | ||
185 | id[32] = '\n'; | |
186 | id[33] = 0; | |
187 | ||
188 | log_info("Initializing machine ID from random generator."); | |
189 | ||
190 | return 0; | |
191 | } | |
192 | ||
c6ac7e4b LP |
193 | int machine_id_setup(const char *root) { |
194 | const char *etc_machine_id, *run_machine_id; | |
195 | _cleanup_close_ int fd = -1; | |
196 | bool writable = true; | |
197 | char id[34]; /* 32 + \n + \0 */ | |
198 | int r; | |
9496e375 | 199 | |
c6ac7e4b LP |
200 | if (isempty(root)) { |
201 | etc_machine_id = "/etc/machine-id"; | |
202 | run_machine_id = "/run/machine-id"; | |
203 | } else { | |
204 | char *x; | |
9496e375 | 205 | |
c6ac7e4b LP |
206 | x = strjoina(root, "/etc/machine-id"); |
207 | etc_machine_id = path_kill_slashes(x); | |
9496e375 | 208 | |
c6ac7e4b LP |
209 | x = strjoina(root, "/run/machine-id"); |
210 | run_machine_id = path_kill_slashes(x); | |
9496e375 DR |
211 | } |
212 | ||
c6ac7e4b LP |
213 | RUN_WITH_UMASK(0000) { |
214 | /* We create this 0444, to indicate that this isn't really | |
215 | * something you should ever modify. Of course, since the file | |
216 | * will be owned by root it doesn't matter much, but maybe | |
217 | * people look. */ | |
9496e375 | 218 | |
c6ac7e4b LP |
219 | mkdir_parents(etc_machine_id, 0755); |
220 | fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); | |
221 | if (fd < 0) { | |
222 | int old_errno = errno; | |
223 | ||
224 | fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
225 | if (fd < 0) { | |
226 | if (old_errno == EROFS && errno == ENOENT) | |
227 | log_error_errno(errno, | |
228 | "System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n" | |
229 | "Booting up is supported only when:\n" | |
230 | "1) /etc/machine-id exists and is populated.\n" | |
231 | "2) /etc/machine-id exists and is empty.\n" | |
232 | "3) /etc/machine-id is missing and /etc is writable.\n"); | |
233 | else | |
234 | log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); | |
235 | ||
236 | return -errno; | |
237 | } | |
9496e375 | 238 | |
c6ac7e4b LP |
239 | writable = false; |
240 | } | |
241 | } | |
242 | ||
243 | if (read_machine_id(fd, id) >= 0) | |
9496e375 DR |
244 | return 0; |
245 | ||
c6ac7e4b LP |
246 | /* Hmm, so, the id currently stored is not useful, then let's |
247 | * generate one */ | |
248 | ||
249 | r = generate_machine_id(id, root); | |
250 | if (r < 0) | |
251 | return r; | |
252 | ||
253 | if (writable) | |
254 | if (write_machine_id(fd, id) >= 0) | |
255 | return 0; | |
256 | ||
257 | fd = safe_close(fd); | |
258 | ||
259 | /* Hmm, we couldn't write it? So let's write it to | |
260 | * /run/machine-id as a replacement */ | |
261 | ||
262 | RUN_WITH_UMASK(0022) { | |
263 | r = write_string_file(run_machine_id, id); | |
264 | } | |
265 | if (r < 0) { | |
266 | (void) unlink(run_machine_id); | |
267 | return log_error_errno(r, "Cannot write %s: %m", run_machine_id); | |
268 | } | |
269 | ||
270 | /* And now, let's mount it over */ | |
271 | if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) { | |
272 | (void) unlink_noerrno(run_machine_id); | |
273 | return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); | |
274 | } | |
275 | ||
276 | log_info("Installed transient %s file.", etc_machine_id); | |
277 | ||
278 | /* Mark the mount read-only */ | |
279 | if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) | |
280 | log_warning_errno(errno, "Failed to make transient %s read-only: %m", etc_machine_id); | |
281 | ||
282 | return 0; | |
9496e375 DR |
283 | } |
284 | ||
979ef53a DR |
285 | int machine_id_commit(const char *root) { |
286 | _cleanup_close_ int fd = -1, initial_mntns_fd = -1; | |
287 | const char *etc_machine_id; | |
288 | char id[34]; /* 32 + \n + \0 */ | |
289 | int r; | |
290 | ||
291 | if (isempty(root)) | |
292 | etc_machine_id = "/etc/machine-id"; | |
293 | else { | |
294 | char *x; | |
295 | ||
63c372cb | 296 | x = strjoina(root, "/etc/machine-id"); |
979ef53a DR |
297 | etc_machine_id = path_kill_slashes(x); |
298 | } | |
299 | ||
300 | r = path_is_mount_point(etc_machine_id, false); | |
301 | if (r < 0) | |
f131770b | 302 | return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id); |
979ef53a DR |
303 | if (r == 0) { |
304 | log_debug("%s is is not a mount point. Nothing to do.", etc_machine_id); | |
305 | return 0; | |
306 | } | |
307 | ||
308 | /* Read existing machine-id */ | |
309 | fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
310 | if (fd < 0) | |
311 | return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); | |
312 | ||
c6ac7e4b | 313 | r = read_machine_id(fd, id); |
979ef53a DR |
314 | if (r < 0) |
315 | return log_error_errno(r, "We didn't find a valid machine ID in %s.", etc_machine_id); | |
316 | ||
c6878637 | 317 | r = fd_is_temporary_fs(fd); |
979ef53a DR |
318 | if (r < 0) |
319 | return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id); | |
320 | if (r == 0) { | |
321 | log_error("%s is not on a temporary file system.", etc_machine_id); | |
322 | return -EROFS; | |
323 | } | |
324 | ||
325 | fd = safe_close(fd); | |
326 | ||
327 | /* Store current mount namespace */ | |
328 | r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL); | |
329 | if (r < 0) | |
330 | return log_error_errno(r, "Can't fetch current mount namespace: %m"); | |
331 | ||
332 | /* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */ | |
333 | if (unshare(CLONE_NEWNS) < 0) | |
334 | return log_error_errno(errno, "Failed to enter new namespace: %m"); | |
335 | ||
336 | if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) | |
337 | return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m"); | |
338 | ||
339 | if (umount(etc_machine_id) < 0) | |
340 | return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id); | |
341 | ||
342 | /* Update a persistent version of etc_machine_id */ | |
343 | fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); | |
344 | if (fd < 0) | |
345 | return log_error_errno(errno, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m", etc_machine_id); | |
346 | ||
347 | r = write_machine_id(fd, id); | |
348 | if (r < 0) | |
349 | return log_error_errno(r, "Cannot write %s: %m", etc_machine_id); | |
350 | ||
351 | fd = safe_close(fd); | |
352 | ||
353 | /* Return to initial namespace and proceed a lazy tmpfs unmount */ | |
354 | r = namespace_enter(-1, initial_mntns_fd, -1, -1); | |
355 | if (r < 0) | |
356 | return log_warning_errno(r, "Failed to switch back to initial mount namespace: %m.\nWe'll keep transient %s file until next reboot.", etc_machine_id); | |
357 | ||
358 | if (umount2(etc_machine_id, MNT_DETACH) < 0) | |
359 | return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id); | |
360 | ||
361 | return 0; | |
362 | } |