]>
git.ipfire.org Git - thirdparty/systemd.git/blob - src/udev/udev-node.c
2 * Copyright (C) 2003-2013 Kay Sievers <kay@vrfy.org>
4 * This program is free software: you can redistribute it and/or modify
5 * it under the terms of the GNU General Public License as published by
6 * the Free Software Foundation, either version 2 of the License, or
7 * (at your option) any later version.
9 * This program is distributed in the hope that it will be useful,
10 * but WITHOUT ANY WARRANTY; without even the implied warranty of
11 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
12 * GNU General Public License for more details.
14 * You should have received a copy of the GNU General Public License
15 * along with this program. If not, see <http://www.gnu.org/licenses/>.
28 #include "formats-util.h"
29 #include "selinux-util.h"
30 #include "smack-util.h"
31 #include "string-util.h"
34 static int node_symlink(struct udev_device
*dev
, const char *node
, const char *slink
) {
36 char target
[UTIL_PATH_SIZE
];
39 char slink_tmp
[UTIL_PATH_SIZE
+ 32];
44 /* use relative link */
46 while (node
[i
] && (node
[i
] == slink
[i
])) {
53 while (slink
[i
] != '\0') {
55 l
= strpcpy(&s
, l
, "../");
58 l
= strscpy(s
, l
, &node
[tail
]);
64 /* preserve link with correct target, do not replace node of other device */
65 if (lstat(slink
, &stats
) == 0) {
66 if (S_ISBLK(stats
.st_mode
) || S_ISCHR(stats
.st_mode
)) {
67 log_error("conflicting device node '%s' found, link to '%s' will not be created", slink
, node
);
69 } else if (S_ISLNK(stats
.st_mode
)) {
70 char buf
[UTIL_PATH_SIZE
];
73 len
= readlink(slink
, buf
, sizeof(buf
));
74 if (len
> 0 && len
< (int)sizeof(buf
)) {
76 if (streq(target
, buf
)) {
77 log_debug("preserve already existing symlink '%s' to '%s'", slink
, target
);
78 label_fix(slink
, true, false);
79 utimensat(AT_FDCWD
, slink
, NULL
, AT_SYMLINK_NOFOLLOW
);
85 log_debug("creating symlink '%s' to '%s'", slink
, target
);
87 err
= mkdir_parents_label(slink
, 0755);
88 if (err
!= 0 && err
!= -ENOENT
)
90 mac_selinux_create_file_prepare(slink
, S_IFLNK
);
91 err
= symlink(target
, slink
);
94 mac_selinux_create_file_clear();
95 } while (err
== -ENOENT
);
100 log_debug("atomically replace '%s'", slink
);
101 strscpyl(slink_tmp
, sizeof(slink_tmp
), slink
, ".tmp-", udev_device_get_id_filename(dev
), NULL
);
104 err
= mkdir_parents_label(slink_tmp
, 0755);
105 if (err
!= 0 && err
!= -ENOENT
)
107 mac_selinux_create_file_prepare(slink_tmp
, S_IFLNK
);
108 err
= symlink(target
, slink_tmp
);
111 mac_selinux_create_file_clear();
112 } while (err
== -ENOENT
);
114 log_error_errno(errno
, "symlink '%s' '%s' failed: %m", target
, slink_tmp
);
117 err
= rename(slink_tmp
, slink
);
119 log_error_errno(errno
, "rename '%s' '%s' failed: %m", slink_tmp
, slink
);
126 /* find device node of device with highest priority */
127 static const char *link_find_prioritized(struct udev_device
*dev
, bool add
, const char *stackdir
, char *buf
, size_t bufsize
) {
128 struct udev
*udev
= udev_device_get_udev(dev
);
131 const char *target
= NULL
;
134 priority
= udev_device_get_devlink_priority(dev
);
135 strscpy(buf
, bufsize
, udev_device_get_devnode(dev
));
139 dir
= opendir(stackdir
);
143 struct udev_device
*dev_db
;
147 if (dent
== NULL
|| dent
->d_name
[0] == '\0')
149 if (dent
->d_name
[0] == '.')
152 log_debug("found '%s' claiming '%s'", dent
->d_name
, stackdir
);
154 /* did we find ourself? */
155 if (streq(dent
->d_name
, udev_device_get_id_filename(dev
)))
158 dev_db
= udev_device_new_from_device_id(udev
, dent
->d_name
);
159 if (dev_db
!= NULL
) {
162 devnode
= udev_device_get_devnode(dev_db
);
163 if (devnode
!= NULL
) {
164 if (target
== NULL
|| udev_device_get_devlink_priority(dev_db
) > priority
) {
165 log_debug("'%s' claims priority %i for '%s'",
166 udev_device_get_syspath(dev_db
), udev_device_get_devlink_priority(dev_db
), stackdir
);
167 priority
= udev_device_get_devlink_priority(dev_db
);
168 strscpy(buf
, bufsize
, devnode
);
172 udev_device_unref(dev_db
);
179 /* manage "stack of names" with possibly specified device priorities */
180 static void link_update(struct udev_device
*dev
, const char *slink
, bool add
) {
181 char name_enc
[UTIL_PATH_SIZE
];
182 char filename
[UTIL_PATH_SIZE
* 2];
183 char dirname
[UTIL_PATH_SIZE
];
185 char buf
[UTIL_PATH_SIZE
];
187 util_path_encode(slink
+ strlen("/dev"), name_enc
, sizeof(name_enc
));
188 strscpyl(dirname
, sizeof(dirname
), "/run/udev/links/", name_enc
, NULL
);
189 strscpyl(filename
, sizeof(filename
), dirname
, "/", udev_device_get_id_filename(dev
), NULL
);
191 if (!add
&& unlink(filename
) == 0)
194 target
= link_find_prioritized(dev
, add
, dirname
, buf
, sizeof(buf
));
195 if (target
== NULL
) {
196 log_debug("no reference left, remove '%s'", slink
);
197 if (unlink(slink
) == 0)
198 rmdir_parents(slink
, "/");
200 log_debug("creating link '%s' to '%s'", slink
, target
);
201 node_symlink(dev
, target
, slink
);
210 err
= mkdir_parents(filename
, 0755);
211 if (err
!= 0 && err
!= -ENOENT
)
213 fd
= open(filename
, O_WRONLY
|O_CREAT
|O_CLOEXEC
|O_TRUNC
|O_NOFOLLOW
, 0444);
218 } while (err
== -ENOENT
);
222 void udev_node_update_old_links(struct udev_device
*dev
, struct udev_device
*dev_old
) {
223 struct udev_list_entry
*list_entry
;
225 /* update possible left-over symlinks */
226 udev_list_entry_foreach(list_entry
, udev_device_get_devlinks_list_entry(dev_old
)) {
227 const char *name
= udev_list_entry_get_name(list_entry
);
228 struct udev_list_entry
*list_entry_current
;
231 /* check if old link name still belongs to this device */
233 udev_list_entry_foreach(list_entry_current
, udev_device_get_devlinks_list_entry(dev
)) {
234 const char *name_current
= udev_list_entry_get_name(list_entry_current
);
236 if (streq(name
, name_current
)) {
244 log_debug("update old name, '%s' no longer belonging to '%s'",
245 name
, udev_device_get_devpath(dev
));
246 link_update(dev
, name
, false);
250 static int node_permissions_apply(struct udev_device
*dev
, bool apply
,
251 mode_t mode
, uid_t uid
, gid_t gid
,
252 struct udev_list
*seclabel_list
) {
253 const char *devnode
= udev_device_get_devnode(dev
);
254 dev_t devnum
= udev_device_get_devnum(dev
);
256 struct udev_list_entry
*entry
;
259 if (streq(udev_device_get_subsystem(dev
), "block"))
264 if (lstat(devnode
, &stats
) != 0) {
266 log_debug_errno(errno
, "can not stat() node '%s' (%m)", devnode
);
270 if (((stats
.st_mode
& S_IFMT
) != (mode
& S_IFMT
)) || (stats
.st_rdev
!= devnum
)) {
272 log_debug("found node '%s' with non-matching devnum %s, skip handling",
273 udev_device_get_devnode(dev
), udev_device_get_id_filename(dev
));
278 bool selinux
= false;
281 if ((stats
.st_mode
& 0777) != (mode
& 0777) || stats
.st_uid
!= uid
|| stats
.st_gid
!= gid
) {
282 log_debug("set permissions %s, %#o, uid=%u, gid=%u", devnode
, mode
, uid
, gid
);
283 err
= chmod(devnode
, mode
);
285 log_warning_errno(errno
, "setting mode of %s to %#o failed: %m", devnode
, mode
);
286 err
= chown(devnode
, uid
, gid
);
288 log_warning_errno(errno
, "setting owner of %s to uid=%u, gid=%u failed: %m", devnode
, uid
, gid
);
290 log_debug("preserve permissions %s, %#o, uid=%u, gid=%u", devnode
, mode
, uid
, gid
);
293 /* apply SECLABEL{$module}=$label */
294 udev_list_entry_foreach(entry
, udev_list_get_entry(seclabel_list
)) {
295 const char *name
, *label
;
298 name
= udev_list_entry_get_name(entry
);
299 label
= udev_list_entry_get_value(entry
);
301 if (streq(name
, "selinux")) {
304 r
= mac_selinux_apply(devnode
, label
);
306 log_error_errno(r
, "SECLABEL: failed to set SELinux label '%s': %m", label
);
308 log_debug("SECLABEL: set SELinux label '%s'", label
);
310 } else if (streq(name
, "smack")) {
313 r
= mac_smack_apply(devnode
, SMACK_ATTR_ACCESS
, label
);
315 log_error_errno(r
, "SECLABEL: failed to set SMACK label '%s': %m", label
);
317 log_debug("SECLABEL: set SMACK label '%s'", label
);
320 log_error("SECLABEL: unknown subsystem, ignoring '%s'='%s'", name
, label
);
323 /* set the defaults */
325 mac_selinux_fix(devnode
, true, false);
327 mac_smack_apply(devnode
, SMACK_ATTR_ACCESS
, NULL
);
330 /* always update timestamp when we re-use the node, like on media change events */
331 utimensat(AT_FDCWD
, devnode
, NULL
, 0);
336 void udev_node_add(struct udev_device
*dev
, bool apply
,
337 mode_t mode
, uid_t uid
, gid_t gid
,
338 struct udev_list
*seclabel_list
) {
339 char filename
[UTIL_PATH_SIZE
];
340 struct udev_list_entry
*list_entry
;
342 log_debug("handling device node '%s', devnum=%s, mode=%#o, uid="UID_FMT
", gid="GID_FMT
,
343 udev_device_get_devnode(dev
), udev_device_get_id_filename(dev
), mode
, uid
, gid
);
345 if (node_permissions_apply(dev
, apply
, mode
, uid
, gid
, seclabel_list
) < 0)
348 /* always add /dev/{block,char}/$major:$minor */
349 snprintf(filename
, sizeof(filename
), "/dev/%s/%u:%u",
350 streq(udev_device_get_subsystem(dev
), "block") ? "block" : "char",
351 major(udev_device_get_devnum(dev
)), minor(udev_device_get_devnum(dev
)));
352 node_symlink(dev
, udev_device_get_devnode(dev
), filename
);
354 /* create/update symlinks, add symlinks to name index */
355 udev_list_entry_foreach(list_entry
, udev_device_get_devlinks_list_entry(dev
))
356 link_update(dev
, udev_list_entry_get_name(list_entry
), true);
359 void udev_node_remove(struct udev_device
*dev
) {
360 struct udev_list_entry
*list_entry
;
361 char filename
[UTIL_PATH_SIZE
];
363 /* remove/update symlinks, remove symlinks from name index */
364 udev_list_entry_foreach(list_entry
, udev_device_get_devlinks_list_entry(dev
))
365 link_update(dev
, udev_list_entry_get_name(list_entry
), false);
367 /* remove /dev/{block,char}/$major:$minor */
368 snprintf(filename
, sizeof(filename
), "/dev/%s/%u:%u",
369 streq(udev_device_get_subsystem(dev
), "block") ? "block" : "char",
370 major(udev_device_get_devnum(dev
)), minor(udev_device_get_devnum(dev
)));