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52ad194e | 1 | /* SPDX-License-Identifier: LGPL-2.1+ */ |
663996b3 | 2 | |
663996b3 | 3 | #include <fcntl.h> |
6300502b | 4 | #include <sched.h> |
663996b3 | 5 | #include <sys/mount.h> |
6300502b | 6 | #include <unistd.h> |
663996b3 | 7 | |
6300502b | 8 | #include "sd-id128.h" |
663996b3 | 9 | |
db2df898 MP |
10 | #include "alloc-util.h" |
11 | #include "fd-util.h" | |
db2df898 | 12 | #include "fs-util.h" |
5a920b42 | 13 | #include "id128-util.h" |
6300502b | 14 | #include "log.h" |
db2df898 | 15 | #include "machine-id-setup.h" |
663996b3 | 16 | #include "macro.h" |
663996b3 | 17 | #include "mkdir.h" |
6e866b33 | 18 | #include "mountpoint-util.h" |
60f067b4 | 19 | #include "path-util.h" |
e3bff60a | 20 | #include "process-util.h" |
db2df898 MP |
21 | #include "stat-util.h" |
22 | #include "string-util.h" | |
23 | #include "umask-util.h" | |
6300502b MP |
24 | #include "util.h" |
25 | #include "virt.h" | |
663996b3 | 26 | |
5a920b42 | 27 | static int generate_machine_id(const char *root, sd_id128_t *ret) { |
6300502b | 28 | const char *dbus_machine_id; |
5a920b42 MP |
29 | _cleanup_close_ int fd = -1; |
30 | int r; | |
663996b3 | 31 | |
5a920b42 | 32 | assert(ret); |
60f067b4 | 33 | |
663996b3 | 34 | /* First, try reading the D-Bus machine id, unless it is a symlink */ |
5a920b42 | 35 | dbus_machine_id = prefix_roota(root, "/var/lib/dbus/machine-id"); |
60f067b4 | 36 | fd = open(dbus_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY|O_NOFOLLOW); |
663996b3 | 37 | if (fd >= 0) { |
5a920b42 | 38 | if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0) { |
e3bff60a MP |
39 | log_info("Initializing machine ID from D-Bus machine ID."); |
40 | return 0; | |
663996b3 | 41 | } |
5a920b42 MP |
42 | |
43 | fd = safe_close(fd); | |
663996b3 MS |
44 | } |
45 | ||
5eef597e MP |
46 | if (isempty(root)) { |
47 | /* If that didn't work, see if we are running in a container, | |
48 | * and a machine ID was passed in via $container_uuid the way | |
49 | * libvirt/LXC does it */ | |
6300502b MP |
50 | |
51 | if (detect_container() > 0) { | |
5eef597e | 52 | _cleanup_free_ char *e = NULL; |
60f067b4 | 53 | |
5a920b42 MP |
54 | if (getenv_for_pid(1, "container_uuid", &e) > 0 && |
55 | sd_id128_from_string(e, ret) >= 0) { | |
56 | log_info("Initializing machine ID from container UUID."); | |
57 | return 0; | |
60f067b4 | 58 | } |
5eef597e | 59 | |
6300502b MP |
60 | } else if (detect_vm() == VIRTUALIZATION_KVM) { |
61 | ||
5eef597e MP |
62 | /* If we are not running in a container, see if we are |
63 | * running in qemu/kvm and a machine ID was passed in | |
64 | * via -uuid on the qemu/kvm command line */ | |
65 | ||
5a920b42 MP |
66 | if (id128_read("/sys/class/dmi/id/product_uuid", ID128_UUID, ret) >= 0) { |
67 | log_info("Initializing machine ID from KVM UUID."); | |
68 | return 0; | |
5eef597e | 69 | } |
60f067b4 | 70 | } |
663996b3 MS |
71 | } |
72 | ||
73 | /* If that didn't work, generate a random machine id */ | |
5a920b42 | 74 | r = sd_id128_randomize(ret); |
f47781d8 | 75 | if (r < 0) |
6e866b33 | 76 | return log_error_errno(r, "Failed to generate randomized machine ID: %m"); |
663996b3 MS |
77 | |
78 | log_info("Initializing machine ID from random generator."); | |
663996b3 MS |
79 | return 0; |
80 | } | |
81 | ||
5a920b42 | 82 | int machine_id_setup(const char *root, sd_id128_t machine_id, sd_id128_t *ret) { |
e3bff60a MP |
83 | const char *etc_machine_id, *run_machine_id; |
84 | _cleanup_close_ int fd = -1; | |
5a920b42 | 85 | bool writable; |
e3bff60a | 86 | int r; |
f47781d8 | 87 | |
aa27b158 | 88 | etc_machine_id = prefix_roota(root, "/etc/machine-id"); |
f47781d8 | 89 | |
e3bff60a MP |
90 | RUN_WITH_UMASK(0000) { |
91 | /* We create this 0444, to indicate that this isn't really | |
92 | * something you should ever modify. Of course, since the file | |
93 | * will be owned by root it doesn't matter much, but maybe | |
94 | * people look. */ | |
f47781d8 | 95 | |
5a920b42 | 96 | (void) mkdir_parents(etc_machine_id, 0755); |
e3bff60a MP |
97 | fd = open(etc_machine_id, O_RDWR|O_CREAT|O_CLOEXEC|O_NOCTTY, 0444); |
98 | if (fd < 0) { | |
99 | int old_errno = errno; | |
100 | ||
101 | fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
102 | if (fd < 0) { | |
103 | if (old_errno == EROFS && errno == ENOENT) | |
1d42b86d | 104 | return log_error_errno(errno, |
e3bff60a MP |
105 | "System cannot boot: Missing /etc/machine-id and /etc is mounted read-only.\n" |
106 | "Booting up is supported only when:\n" | |
107 | "1) /etc/machine-id exists and is populated.\n" | |
108 | "2) /etc/machine-id exists and is empty.\n" | |
109 | "3) /etc/machine-id is missing and /etc is writable.\n"); | |
110 | else | |
6e866b33 | 111 | return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); |
e3bff60a MP |
112 | } |
113 | ||
114 | writable = false; | |
5a920b42 MP |
115 | } else |
116 | writable = true; | |
e3bff60a MP |
117 | } |
118 | ||
5a920b42 MP |
119 | /* A we got a valid machine ID argument, that's what counts */ |
120 | if (sd_id128_is_null(machine_id)) { | |
f47781d8 | 121 | |
5a920b42 MP |
122 | /* Try to read any existing machine ID */ |
123 | if (id128_read_fd(fd, ID128_PLAIN, ret) >= 0) | |
124 | return 0; | |
e3bff60a | 125 | |
5a920b42 MP |
126 | /* Hmm, so, the id currently stored is not useful, then let's generate one */ |
127 | r = generate_machine_id(root, &machine_id); | |
4c89c718 MP |
128 | if (r < 0) |
129 | return r; | |
2897b343 | 130 | } |
5a920b42 | 131 | |
2897b343 | 132 | if (writable) { |
5a920b42 | 133 | if (lseek(fd, 0, SEEK_SET) == (off_t) -1) |
2897b343 MP |
134 | return log_error_errno(errno, "Failed to seek %s: %m", etc_machine_id); |
135 | ||
136 | if (ftruncate(fd, 0) < 0) | |
137 | return log_error_errno(errno, "Failed to truncate %s: %m", etc_machine_id); | |
e3bff60a | 138 | |
5a920b42 MP |
139 | if (id128_write_fd(fd, ID128_PLAIN, machine_id, true) >= 0) |
140 | goto finish; | |
2897b343 | 141 | } |
e3bff60a MP |
142 | |
143 | fd = safe_close(fd); | |
144 | ||
5a920b42 | 145 | /* Hmm, we couldn't write it? So let's write it to /run/machine-id as a replacement */ |
e3bff60a | 146 | |
5a920b42 MP |
147 | run_machine_id = prefix_roota(root, "/run/machine-id"); |
148 | ||
149 | RUN_WITH_UMASK(0022) | |
150 | r = id128_write(run_machine_id, ID128_PLAIN, machine_id, false); | |
151 | if (r < 0) { | |
152 | (void) unlink(run_machine_id); | |
153 | return log_error_errno(r, "Cannot write %s: %m", run_machine_id); | |
e3bff60a MP |
154 | } |
155 | ||
156 | /* And now, let's mount it over */ | |
157 | if (mount(run_machine_id, etc_machine_id, NULL, MS_BIND, NULL) < 0) { | |
158 | (void) unlink_noerrno(run_machine_id); | |
159 | return log_error_errno(errno, "Failed to mount %s: %m", etc_machine_id); | |
160 | } | |
161 | ||
162 | log_info("Installed transient %s file.", etc_machine_id); | |
163 | ||
164 | /* Mark the mount read-only */ | |
165 | if (mount(NULL, etc_machine_id, NULL, MS_BIND|MS_RDONLY|MS_REMOUNT, NULL) < 0) | |
5a920b42 MP |
166 | log_warning_errno(errno, "Failed to make transient %s read-only, ignoring: %m", etc_machine_id); |
167 | ||
168 | finish: | |
169 | if (ret) | |
170 | *ret = machine_id; | |
e3bff60a MP |
171 | |
172 | return 0; | |
f47781d8 MP |
173 | } |
174 | ||
175 | int machine_id_commit(const char *root) { | |
176 | _cleanup_close_ int fd = -1, initial_mntns_fd = -1; | |
177 | const char *etc_machine_id; | |
5a920b42 | 178 | sd_id128_t id; |
f47781d8 MP |
179 | int r; |
180 | ||
5a920b42 MP |
181 | /* Replaces a tmpfs bind mount of /etc/machine-id by a proper file, atomically. For this, the umount is removed |
182 | * in a mount namespace, a new file is created at the right place. Afterwards the mount is also removed in the | |
183 | * original mount namespace, thus revealing the file that was just created. */ | |
184 | ||
aa27b158 | 185 | etc_machine_id = prefix_roota(root, "/etc/machine-id"); |
f47781d8 | 186 | |
2897b343 | 187 | r = path_is_mount_point(etc_machine_id, NULL, 0); |
f47781d8 | 188 | if (r < 0) |
e735f4d4 | 189 | return log_error_errno(r, "Failed to determine whether %s is a mount point: %m", etc_machine_id); |
f47781d8 | 190 | if (r == 0) { |
5a920b42 | 191 | log_debug("%s is not a mount point. Nothing to do.", etc_machine_id); |
f47781d8 MP |
192 | return 0; |
193 | } | |
194 | ||
195 | /* Read existing machine-id */ | |
196 | fd = open(etc_machine_id, O_RDONLY|O_CLOEXEC|O_NOCTTY); | |
197 | if (fd < 0) | |
198 | return log_error_errno(errno, "Cannot open %s: %m", etc_machine_id); | |
199 | ||
e3bff60a | 200 | r = fd_is_temporary_fs(fd); |
f47781d8 MP |
201 | if (r < 0) |
202 | return log_error_errno(r, "Failed to determine whether %s is on a temporary file system: %m", etc_machine_id); | |
6e866b33 MB |
203 | if (r == 0) |
204 | return log_error_errno(SYNTHETIC_ERRNO(EROFS), | |
205 | "%s is not on a temporary file system.", | |
206 | etc_machine_id); | |
f47781d8 | 207 | |
5a920b42 MP |
208 | r = id128_read_fd(fd, ID128_PLAIN, &id); |
209 | if (r < 0) | |
6e866b33 | 210 | return log_error_errno(r, "We didn't find a valid machine ID in %s: %m", etc_machine_id); |
5a920b42 | 211 | |
f47781d8 MP |
212 | fd = safe_close(fd); |
213 | ||
214 | /* Store current mount namespace */ | |
13d276d0 | 215 | r = namespace_open(0, NULL, &initial_mntns_fd, NULL, NULL, NULL); |
f47781d8 MP |
216 | if (r < 0) |
217 | return log_error_errno(r, "Can't fetch current mount namespace: %m"); | |
218 | ||
219 | /* Switch to a new mount namespace, isolate ourself and unmount etc_machine_id in our new namespace */ | |
220 | if (unshare(CLONE_NEWNS) < 0) | |
221 | return log_error_errno(errno, "Failed to enter new namespace: %m"); | |
222 | ||
223 | if (mount(NULL, "/", NULL, MS_SLAVE | MS_REC, NULL) < 0) | |
224 | return log_error_errno(errno, "Couldn't make-rslave / mountpoint in our private namespace: %m"); | |
225 | ||
226 | if (umount(etc_machine_id) < 0) | |
227 | return log_error_errno(errno, "Failed to unmount transient %s file in our private namespace: %m", etc_machine_id); | |
228 | ||
229 | /* Update a persistent version of etc_machine_id */ | |
5a920b42 | 230 | r = id128_write(etc_machine_id, ID128_PLAIN, id, true); |
f47781d8 | 231 | if (r < 0) |
5a920b42 | 232 | return log_error_errno(r, "Cannot write %s. This is mandatory to get a persistent machine ID: %m", etc_machine_id); |
f47781d8 MP |
233 | |
234 | /* Return to initial namespace and proceed a lazy tmpfs unmount */ | |
13d276d0 | 235 | r = namespace_enter(-1, initial_mntns_fd, -1, -1, -1); |
f47781d8 MP |
236 | if (r < 0) |
237 | 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); | |
238 | ||
239 | if (umount2(etc_machine_id, MNT_DETACH) < 0) | |
240 | return log_warning_errno(errno, "Failed to unmount transient %s file: %m.\nWe keep that mount until next reboot.", etc_machine_id); | |
241 | ||
242 | return 0; | |
243 | } |