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git.ipfire.org Git - thirdparty/systemd.git/blob - src/core/machine-id-setup.c
1 /*-*- Mode: C; c-basic-offset: 8; indent-tabs-mode: nil -*-*/
4 This file is part of systemd.
6 Copyright 2010 Lennart Poettering
8 systemd is free software; you can redistribute it and/or modify it
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
11 (at your option) any later version.
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
16 Lesser General Public License for more details.
18 You should have received a copy of the GNU Lesser General Public License
19 along with systemd; If not, see <http://www.gnu.org/licenses/>.
27 #include <sys/mount.h>
29 #include "systemd/sd-id128.h"
31 #include "machine-id-setup.h"
38 #include "path-util.h"
39 #include "process-util.h"
41 static int shorten_uuid ( char destination
[ 34 ], const char source
[ 36 ]) {
47 /* Converts a UUID into a machine ID, by lowercasing it and
48 * removing dashes. Validates everything. */
50 for ( i
= 0 , j
= 0 ; i
< 36 && j
< 32 ; i
++) {
53 t
= unhexchar ( source
[ i
]);
57 destination
[ j
++] = hexchar ( t
);
60 if ( i
!= 36 || j
!= 32 )
63 destination
[ 32 ] = ' \n ' ;
68 static int read_machine_id ( int fd
, char id
[ 34 ]) {
69 char id_to_validate
[ 34 ];
75 /* Reads a machine ID from a file, validates it, and returns
76 * it. The returned ID ends in a newline. */
78 r
= loop_read_exact ( fd
, id_to_validate
, 33 , false );
82 if ( id_to_validate
[ 32 ] != ' \n ' )
85 id_to_validate
[ 32 ] = 0 ;
87 if (! id128_is_valid ( id_to_validate
))
90 memcpy ( id
, id_to_validate
, 32 );
96 static int write_machine_id ( int fd
, char id
[ 34 ]) {
100 if ( lseek ( fd
, 0 , SEEK_SET
) < 0 )
103 return loop_write ( fd
, id
, 33 , false );
106 static int generate_machine_id ( char id
[ 34 ], const char * root
) {
111 const char * vm_id
, * dbus_machine_id
;
116 dbus_machine_id
= "/var/lib/dbus/machine-id" ;
118 dbus_machine_id
= strjoina ( root
, "/var/lib/dbus/machine-id" );
120 /* First, try reading the D-Bus machine id, unless it is a symlink */
121 fd
= open ( dbus_machine_id
, O_RDONLY
| O_CLOEXEC
| O_NOCTTY
| O_NOFOLLOW
);
123 r
= read_machine_id ( fd
, id
);
127 log_info ( "Initializing machine ID from D-Bus machine ID." );
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
);
138 _cleanup_free_
char * e
= NULL
;
140 r
= getenv_for_pid ( 1 , "container_uuid" , & e
);
142 r
= shorten_uuid ( id
, e
);
144 log_info ( "Initializing machine ID from container UUID." );
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 */
154 r
= detect_vm (& vm_id
);
155 if ( r
> 0 && streq ( vm_id
, "kvm" )) {
158 fd
= open ( "/sys/class/dmi/id/product_uuid" , O_RDONLY
| O_CLOEXEC
| O_NOCTTY
| O_NOFOLLOW
);
160 r
= loop_read_exact ( fd
, uuid
, 36 , false );
164 r
= shorten_uuid ( id
, uuid
);
166 log_info ( "Initializing machine ID from KVM UUID." );
175 /* If that didn't work, generate a random machine id */
176 r
= sd_id128_randomize (& buf
);
178 return log_error_errno ( r
, "Failed to open /dev/urandom: %m" );
180 for ( p
= buf
. bytes
, q
= id
; p
< buf
. bytes
+ sizeof ( buf
); p
++, q
+= 2 ) {
181 q
[ 0 ] = hexchar (* p
>> 4 );
182 q
[ 1 ] = hexchar (* p
& 15 );
188 log_info ( "Initializing machine ID from random generator." );
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 */
201 etc_machine_id
= "/etc/machine-id" ;
202 run_machine_id
= "/run/machine-id" ;
206 x
= strjoina ( root
, "/etc/machine-id" );
207 etc_machine_id
= path_kill_slashes ( x
);
209 x
= strjoina ( root
, "/run/machine-id" );
210 run_machine_id
= path_kill_slashes ( x
);
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
219 mkdir_parents ( etc_machine_id
, 0755 );
220 fd
= open ( etc_machine_id
, O_RDWR
| O_CREAT
| O_CLOEXEC
| O_NOCTTY
, 0444 );
222 int old_errno
= errno
;
224 fd
= open ( etc_machine_id
, O_RDONLY
| O_CLOEXEC
| O_NOCTTY
);
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 " );
234 log_error_errno ( errno
, "Cannot open %s: %m" , etc_machine_id
);
243 if ( read_machine_id ( fd
, id
) >= 0 )
246 /* Hmm, so, the id currently stored is not useful, then let's
249 r
= generate_machine_id ( id
, root
);
254 if ( write_machine_id ( fd
, id
) >= 0 )
259 /* Hmm, we couldn't write it? So let's write it to
260 * /run/machine-id as a replacement */
262 RUN_WITH_UMASK ( 0022 ) {
263 r
= write_string_file ( run_machine_id
, id
, WRITE_STRING_FILE_CREATE
);
266 ( void ) unlink ( run_machine_id
);
267 return log_error_errno ( r
, "Cannot write %s: %m" , run_machine_id
);
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
);
276 log_info ( "Installed transient %s file." , etc_machine_id
);
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
);
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 */
292 etc_machine_id
= "/etc/machine-id" ;
296 x
= strjoina ( root
, "/etc/machine-id" );
297 etc_machine_id
= path_kill_slashes ( x
);
300 r
= path_is_mount_point ( etc_machine_id
, 0 );
302 return log_error_errno ( r
, "Failed to determine whether %s is a mount point: %m" , etc_machine_id
);
304 log_debug ( "%s is is not a mount point. Nothing to do." , etc_machine_id
);
308 /* Read existing machine-id */
309 fd
= open ( etc_machine_id
, O_RDONLY
| O_CLOEXEC
| O_NOCTTY
);
311 return log_error_errno ( errno
, "Cannot open %s: %m" , etc_machine_id
);
313 r
= read_machine_id ( fd
, id
);
315 return log_error_errno ( r
, "We didn't find a valid machine ID in %s." , etc_machine_id
);
317 r
= fd_is_temporary_fs ( fd
);
319 return log_error_errno ( r
, "Failed to determine whether %s is on a temporary file system: %m" , etc_machine_id
);
321 log_error ( "%s is not on a temporary file system." , etc_machine_id
);
327 /* Store current mount namespace */
328 r
= namespace_open ( 0 , NULL
, & initial_mntns_fd
, NULL
, NULL
, NULL
);
330 return log_error_errno ( r
, "Can't fetch current mount namespace: %m" );
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" );
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" );
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
);
342 /* Update a persistent version of etc_machine_id */
343 fd
= open ( etc_machine_id
, O_RDWR
| O_CREAT
| O_CLOEXEC
| O_NOCTTY
, 0444 );
345 return log_error_errno ( errno
, "Cannot open for writing %s. This is mandatory to get a persistent machine-id: %m" , etc_machine_id
);
347 r
= write_machine_id ( fd
, id
);
349 return log_error_errno ( r
, "Cannot write %s: %m" , etc_machine_id
);
353 /* Return to initial namespace and proceed a lazy tmpfs unmount */
354 r
= namespace_enter (- 1 , initial_mntns_fd
, - 1 , - 1 , - 1 );
356 return log_warning_errno ( r
, "Failed to switch back to initial mount namespace: %m. \n We'll keep transient %s file until next reboot." , etc_machine_id
);
358 if ( umount2 ( etc_machine_id
, MNT_DETACH
) < 0 )
359 return log_warning_errno ( errno
, "Failed to unmount transient %s file: %m. \n We keep that mount until next reboot." , etc_machine_id
);