2 * Copyright (C) 2003-2010 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/>.
30 #include <sys/types.h>
34 #define TMP_FILE_EXT ".udev-tmp"
36 static int node_symlink(struct udev *udev, const char *node, const char *slink)
39 char target[UTIL_PATH_SIZE];
42 char slink_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)];
47 /* use relative link */
49 while (node[i] && (node[i] == slink[i])) {
56 while (slink[i] != '\0') {
58 l = strpcpy(&s, l, "../");
61 l = strscpy(s, l, &node[tail]);
67 /* preserve link with correct target, do not replace node of other device */
68 if (lstat(slink, &stats) == 0) {
69 if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) {
70 log_error("conflicting device node '%s' found, link to '%s' will not be created\n", slink, node);
72 } else if (S_ISLNK(stats.st_mode)) {
73 char buf[UTIL_PATH_SIZE];
76 len = readlink(slink, buf, sizeof(buf));
77 if (len > 0 && len < (int)sizeof(buf)) {
79 if (strcmp(target, buf) == 0) {
80 log_debug("preserve already existing symlink '%s' to '%s'\n", slink, target);
81 label_fix(slink, true, false);
82 utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW);
88 log_debug("creating symlink '%s' to '%s'\n", slink, target);
90 err = mkdir_parents_label(slink, 0755);
91 if (err != 0 && err != -ENOENT)
93 label_context_set(slink, S_IFLNK);
94 err = symlink(target, slink);
97 label_context_clear();
98 } while (err == -ENOENT);
103 log_debug("atomically replace '%s'\n", slink);
104 strscpyl(slink_tmp, sizeof(slink_tmp), slink, TMP_FILE_EXT, NULL);
107 err = mkdir_parents_label(slink_tmp, 0755);
108 if (err != 0 && err != -ENOENT)
110 label_context_set(slink_tmp, S_IFLNK);
111 err = symlink(target, slink_tmp);
114 label_context_clear();
115 } while (err == -ENOENT);
117 log_error("symlink '%s' '%s' failed: %m\n", target, slink_tmp);
120 err = rename(slink_tmp, slink);
122 log_error("rename '%s' '%s' failed: %m\n", slink_tmp, slink);
129 /* find device node of device with highest priority */
130 static const char *link_find_prioritized(struct udev_device *dev, bool add, const char *stackdir, char *buf, size_t bufsize)
132 struct udev *udev = udev_device_get_udev(dev);
135 const char *target = NULL;
138 priority = udev_device_get_devlink_priority(dev);
139 strscpy(buf, bufsize, udev_device_get_devnode(dev));
143 dir = opendir(stackdir);
147 struct udev_device *dev_db;
151 if (dent == NULL || dent->d_name[0] == '\0')
153 if (dent->d_name[0] == '.')
156 log_debug("found '%s' claiming '%s'\n", dent->d_name, stackdir);
158 /* did we find ourself? */
159 if (strcmp(dent->d_name, udev_device_get_id_filename(dev)) == 0)
162 dev_db = udev_device_new_from_device_id(udev, dent->d_name);
163 if (dev_db != NULL) {
166 devnode = udev_device_get_devnode(dev_db);
167 if (devnode != NULL) {
168 if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) {
169 log_debug("'%s' claims priority %i for '%s'\n",
170 udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir);
171 priority = udev_device_get_devlink_priority(dev_db);
172 strscpy(buf, bufsize, devnode);
176 udev_device_unref(dev_db);
183 /* manage "stack of names" with possibly specified device priorities */
184 static void link_update(struct udev_device *dev, const char *slink, bool add)
186 struct udev *udev = udev_device_get_udev(dev);
187 char name_enc[UTIL_PATH_SIZE];
188 char filename[UTIL_PATH_SIZE * 2];
189 char dirname[UTIL_PATH_SIZE];
191 char buf[UTIL_PATH_SIZE];
193 util_path_encode(slink + strlen("/dev"), name_enc, sizeof(name_enc));
194 strscpyl(dirname, sizeof(dirname), "/run/udev/links/", name_enc, NULL);
195 strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL);
197 if (!add && unlink(filename) == 0)
200 target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf));
201 if (target == NULL) {
202 log_debug("no reference left, remove '%s'\n", slink);
203 if (unlink(slink) == 0)
204 util_delete_path(udev, slink);
206 log_debug("creating link '%s' to '%s'\n", slink, target);
207 node_symlink(udev, target, slink);
216 err = mkdir_parents(filename, 0755);
217 if (err != 0 && err != -ENOENT)
219 fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444);
224 } while (err == -ENOENT);
228 void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old)
230 struct udev_list_entry *list_entry;
232 /* update possible left-over symlinks */
233 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev_old)) {
234 const char *name = udev_list_entry_get_name(list_entry);
235 struct udev_list_entry *list_entry_current;
238 /* check if old link name still belongs to this device */
240 udev_list_entry_foreach(list_entry_current, udev_device_get_devlinks_list_entry(dev)) {
241 const char *name_current = udev_list_entry_get_name(list_entry_current);
243 if (strcmp(name, name_current) == 0) {
251 log_debug("update old name, '%s' no longer belonging to '%s'\n",
252 name, udev_device_get_devpath(dev));
253 link_update(dev, name, false);
257 static int node_fixup(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid)
259 const char *devnode = udev_device_get_devnode(dev);
260 dev_t devnum = udev_device_get_devnum(dev);
264 if (strcmp(udev_device_get_subsystem(dev), "block") == 0)
269 if (lstat(devnode, &stats) != 0) {
271 log_debug("can not stat() node '%s' (%m)\n", devnode);
275 if (((stats.st_mode & S_IFMT) != (mode & S_IFMT)) || (stats.st_rdev != devnum)) {
277 log_debug("found node '%s' with non-matching devnum %s, skip handling\n",
278 udev_device_get_devnode(dev), udev_device_get_id_filename(dev));
283 * Set permissions and selinux file context only on add events. We always
284 * set it on bootup (coldplug) with "trigger --action=add" for all devices
285 * and for any newly added devices (hotplug). We don't want to change it
286 * later, in case something else has applied custom settings in the meantime.
288 if (strcmp(udev_device_get_action(dev), "add") == 0) {
289 if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) {
290 log_debug("set permissions %s, %#o, uid=%u, gid=%u\n", devnode, mode, uid, gid);
291 chmod(devnode, mode);
292 chown(devnode, uid, gid);
294 log_debug("preserve permissions %s, %#o, uid=%u, gid=%u\n", devnode, mode, uid, gid);
297 label_fix(devnode, true, false);
300 /* always update timestamp when we re-use the node, like on media change events */
301 utimensat(AT_FDCWD, devnode, NULL, 0);
306 void udev_node_add(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid)
308 struct udev *udev = udev_device_get_udev(dev);
309 char filename[UTIL_PATH_SIZE];
310 struct udev_list_entry *list_entry;
312 log_debug("handling device node '%s', devnum=%s, mode=%#o, uid=%d, gid=%d\n",
313 udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid);
315 if (node_fixup(dev, mode, uid, gid) < 0)
318 /* always add /dev/{block,char}/$major:$minor */
319 snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
320 strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char",
321 major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
322 node_symlink(udev, udev_device_get_devnode(dev), filename);
324 /* create/update symlinks, add symlinks to name index */
325 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
326 link_update(dev, udev_list_entry_get_name(list_entry), true);
329 void udev_node_remove(struct udev_device *dev)
331 struct udev_list_entry *list_entry;
332 char filename[UTIL_PATH_SIZE];
334 /* remove/update symlinks, remove symlinks from name index */
335 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
336 link_update(dev, udev_list_entry_get_name(list_entry), false);
338 /* remove /dev/{block,char}/$major:$minor */
339 snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
340 strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char",
341 major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));