]> git.ipfire.org Git - thirdparty/systemd.git/blame - src/udev/udev-node.c
Run with a custom SMACK domain (label).
[thirdparty/systemd.git] / src / udev / udev-node.c
CommitLineData
ea733a2f 1/*
22582bb2 2 * Copyright (C) 2003-2013 Kay Sievers <kay@vrfy.org>
ea733a2f 3 *
55e9959b
KS
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.
ea733a2f 8 *
55e9959b
KS
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.
13 *
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/>.
ea733a2f
GKH
16 */
17
18#include <stdlib.h>
19#include <string.h>
20#include <stdio.h>
1aa1e248 21#include <stddef.h>
6c29f2b9 22#include <stdbool.h>
ea733a2f
GKH
23#include <fcntl.h>
24#include <unistd.h>
25#include <errno.h>
67f69ae1 26#include <grp.h>
24f0605c 27#include <dirent.h>
56073914 28#include <sys/time.h>
32ff5bca 29#include <sys/stat.h>
10950dfe 30#include <sys/types.h>
ea733a2f
GKH
31
32#include "udev.h"
9825617b 33
38d70045 34static int node_symlink(struct udev_device *dev, const char *node, const char *slink)
fa33d857 35{
912541b0
KS
36 struct stat stats;
37 char target[UTIL_PATH_SIZE];
38 char *s;
39 size_t l;
38d70045 40 char slink_tmp[UTIL_PATH_SIZE + 32];
912541b0
KS
41 int i = 0;
42 int tail = 0;
43 int err = 0;
44
45 /* use relative link */
46 target[0] = '\0';
47 while (node[i] && (node[i] == slink[i])) {
48 if (node[i] == '/')
49 tail = i+1;
50 i++;
51 }
52 s = target;
53 l = sizeof(target);
54 while (slink[i] != '\0') {
55 if (slink[i] == '/')
d5a89d7d 56 l = strpcpy(&s, l, "../");
912541b0
KS
57 i++;
58 }
d5a89d7d 59 l = strscpy(s, l, &node[tail]);
912541b0
KS
60 if (l == 0) {
61 err = -EINVAL;
62 goto exit;
63 }
64
65 /* preserve link with correct target, do not replace node of other device */
66 if (lstat(slink, &stats) == 0) {
67 if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) {
2be7287b
KS
68 log_error("conflicting device node '%s' found, link to '%s' will not be created\n", slink, node);
69 goto exit;
912541b0
KS
70 } else if (S_ISLNK(stats.st_mode)) {
71 char buf[UTIL_PATH_SIZE];
72 int len;
73
912541b0
KS
74 len = readlink(slink, buf, sizeof(buf));
75 if (len > 0 && len < (int)sizeof(buf)) {
76 buf[len] = '\0';
090be865 77 if (streq(target, buf)) {
baa30fbc 78 log_debug("preserve already existing symlink '%s' to '%s'\n", slink, target);
c9bc0764 79 label_fix(slink, true, false);
912541b0
KS
80 utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW);
81 goto exit;
82 }
83 }
84 }
85 } else {
baa30fbc 86 log_debug("creating symlink '%s' to '%s'\n", slink, target);
912541b0 87 do {
d2e54fae 88 err = mkdir_parents_label(slink, 0755);
912541b0
KS
89 if (err != 0 && err != -ENOENT)
90 break;
e9a5ef7c 91 label_context_set(slink, S_IFLNK);
912541b0
KS
92 err = symlink(target, slink);
93 if (err != 0)
94 err = -errno;
e9a5ef7c 95 label_context_clear();
912541b0
KS
96 } while (err == -ENOENT);
97 if (err == 0)
98 goto exit;
99 }
100
baa30fbc 101 log_debug("atomically replace '%s'\n", slink);
38d70045 102 strscpyl(slink_tmp, sizeof(slink_tmp), slink, ".tmp-", udev_device_get_id_filename(dev), NULL);
912541b0
KS
103 unlink(slink_tmp);
104 do {
d2e54fae 105 err = mkdir_parents_label(slink_tmp, 0755);
912541b0
KS
106 if (err != 0 && err != -ENOENT)
107 break;
e9a5ef7c 108 label_context_set(slink_tmp, S_IFLNK);
912541b0
KS
109 err = symlink(target, slink_tmp);
110 if (err != 0)
111 err = -errno;
e9a5ef7c 112 label_context_clear();
912541b0
KS
113 } while (err == -ENOENT);
114 if (err != 0) {
baa30fbc 115 log_error("symlink '%s' '%s' failed: %m\n", target, slink_tmp);
912541b0
KS
116 goto exit;
117 }
118 err = rename(slink_tmp, slink);
119 if (err != 0) {
baa30fbc 120 log_error("rename '%s' '%s' failed: %m\n", slink_tmp, slink);
912541b0
KS
121 unlink(slink_tmp);
122 }
fa33d857 123exit:
912541b0 124 return err;
fa33d857
KS
125}
126
6c29f2b9
KS
127/* find device node of device with highest priority */
128static const char *link_find_prioritized(struct udev_device *dev, bool add, const char *stackdir, char *buf, size_t bufsize)
24f0605c 129{
912541b0
KS
130 struct udev *udev = udev_device_get_udev(dev);
131 DIR *dir;
132 int priority = 0;
133 const char *target = NULL;
134
135 if (add) {
136 priority = udev_device_get_devlink_priority(dev);
d5a89d7d 137 strscpy(buf, bufsize, udev_device_get_devnode(dev));
912541b0
KS
138 target = buf;
139 }
140
141 dir = opendir(stackdir);
142 if (dir == NULL)
143 return target;
144 for (;;) {
145 struct udev_device *dev_db;
146 struct dirent *dent;
147
148 dent = readdir(dir);
149 if (dent == NULL || dent->d_name[0] == '\0')
150 break;
151 if (dent->d_name[0] == '.')
152 continue;
153
baa30fbc 154 log_debug("found '%s' claiming '%s'\n", dent->d_name, stackdir);
912541b0
KS
155
156 /* did we find ourself? */
090be865 157 if (streq(dent->d_name, udev_device_get_id_filename(dev)))
912541b0
KS
158 continue;
159
dbf61afb 160 dev_db = udev_device_new_from_device_id(udev, dent->d_name);
912541b0
KS
161 if (dev_db != NULL) {
162 const char *devnode;
163
164 devnode = udev_device_get_devnode(dev_db);
165 if (devnode != NULL) {
912541b0 166 if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) {
baa30fbc
KS
167 log_debug("'%s' claims priority %i for '%s'\n",
168 udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir);
912541b0 169 priority = udev_device_get_devlink_priority(dev_db);
d5a89d7d 170 strscpy(buf, bufsize, devnode);
912541b0
KS
171 target = buf;
172 }
173 }
174 udev_device_unref(dev_db);
175 }
176 }
177 closedir(dir);
178 return target;
aa8734ff
KS
179}
180
6c29f2b9
KS
181/* manage "stack of names" with possibly specified device priorities */
182static void link_update(struct udev_device *dev, const char *slink, bool add)
aa8734ff 183{
912541b0
KS
184 struct udev *udev = udev_device_get_udev(dev);
185 char name_enc[UTIL_PATH_SIZE];
186 char filename[UTIL_PATH_SIZE * 2];
187 char dirname[UTIL_PATH_SIZE];
188 const char *target;
189 char buf[UTIL_PATH_SIZE];
190
4cb72937 191 util_path_encode(slink + strlen("/dev"), name_enc, sizeof(name_enc));
d5a89d7d
KS
192 strscpyl(dirname, sizeof(dirname), "/run/udev/links/", name_enc, NULL);
193 strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL);
912541b0 194
baa30fbc
KS
195 if (!add && unlink(filename) == 0)
196 rmdir(dirname);
912541b0
KS
197
198 target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf));
199 if (target == NULL) {
baa30fbc 200 log_debug("no reference left, remove '%s'\n", slink);
912541b0
KS
201 if (unlink(slink) == 0)
202 util_delete_path(udev, slink);
203 } else {
baa30fbc 204 log_debug("creating link '%s' to '%s'\n", slink, target);
38d70045 205 node_symlink(dev, target, slink);
912541b0
KS
206 }
207
208 if (add) {
209 int err;
210
912541b0
KS
211 do {
212 int fd;
213
3cbd5f6b 214 err = mkdir_parents(filename, 0755);
912541b0
KS
215 if (err != 0 && err != -ENOENT)
216 break;
217 fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444);
218 if (fd >= 0)
219 close(fd);
220 else
221 err = -errno;
222 } while (err == -ENOENT);
223 }
24f0605c
KS
224}
225
ec2dd02e 226void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old)
24f0605c 227{
912541b0
KS
228 struct udev_list_entry *list_entry;
229
230 /* update possible left-over symlinks */
231 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev_old)) {
232 const char *name = udev_list_entry_get_name(list_entry);
233 struct udev_list_entry *list_entry_current;
234 int found;
235
236 /* check if old link name still belongs to this device */
237 found = 0;
238 udev_list_entry_foreach(list_entry_current, udev_device_get_devlinks_list_entry(dev)) {
239 const char *name_current = udev_list_entry_get_name(list_entry_current);
240
090be865 241 if (streq(name, name_current)) {
912541b0
KS
242 found = 1;
243 break;
244 }
245 }
246 if (found)
247 continue;
248
baa30fbc 249 log_debug("update old name, '%s' no longer belonging to '%s'\n",
912541b0 250 name, udev_device_get_devpath(dev));
8a173387 251 link_update(dev, name, false);
912541b0 252 }
24f0605c
KS
253}
254
22582bb2 255static int node_permissions_apply(struct udev_device *dev, bool apply, mode_t mode, uid_t uid, gid_t gid)
220893b3 256{
912541b0
KS
257 const char *devnode = udev_device_get_devnode(dev);
258 dev_t devnum = udev_device_get_devnum(dev);
259 struct stat stats;
260 int err = 0;
261
090be865 262 if (streq(udev_device_get_subsystem(dev), "block"))
912541b0
KS
263 mode |= S_IFBLK;
264 else
265 mode |= S_IFCHR;
266
267 if (lstat(devnode, &stats) != 0) {
268 err = -errno;
baa30fbc 269 log_debug("can not stat() node '%s' (%m)\n", devnode);
912541b0
KS
270 goto out;
271 }
272
273 if (((stats.st_mode & S_IFMT) != (mode & S_IFMT)) || (stats.st_rdev != devnum)) {
274 err = -EEXIST;
baa30fbc
KS
275 log_debug("found node '%s' with non-matching devnum %s, skip handling\n",
276 udev_device_get_devnode(dev), udev_device_get_id_filename(dev));
912541b0
KS
277 goto out;
278 }
279
22582bb2 280 if (apply) {
48a849ee
KS
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\n", devnode, mode, uid, gid);
283 chmod(devnode, mode);
284 chown(devnode, uid, gid);
285 } else {
286 log_debug("preserve permissions %s, %#o, uid=%u, gid=%u\n", devnode, mode, uid, gid);
287 }
48a849ee
KS
288 label_fix(devnode, true, false);
289 }
912541b0
KS
290
291 /* always update timestamp when we re-use the node, like on media change events */
292 utimensat(AT_FDCWD, devnode, NULL, 0);
220893b3 293out:
912541b0 294 return err;
220893b3
KS
295}
296
22582bb2 297void udev_node_add(struct udev_device *dev, bool apply, mode_t mode, uid_t uid, gid_t gid)
97853b4f 298{
912541b0
KS
299 char filename[UTIL_PATH_SIZE];
300 struct udev_list_entry *list_entry;
912541b0 301
baa30fbc
KS
302 log_debug("handling device node '%s', devnum=%s, mode=%#o, uid=%d, gid=%d\n",
303 udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid);
912541b0 304
22582bb2 305 if (node_permissions_apply(dev, apply, mode, uid, gid) < 0)
e7f32890 306 return;
912541b0
KS
307
308 /* always add /dev/{block,char}/$major:$minor */
4cb72937 309 snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
090be865 310 streq(udev_device_get_subsystem(dev), "block") ? "block" : "char",
912541b0 311 major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
38d70045 312 node_symlink(dev, udev_device_get_devnode(dev), filename);
912541b0
KS
313
314 /* create/update symlinks, add symlinks to name index */
8a173387
KS
315 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
316 link_update(dev, udev_list_entry_get_name(list_entry), true);
ea733a2f
GKH
317}
318
e7f32890 319void udev_node_remove(struct udev_device *dev)
ff9a488d 320{
912541b0 321 struct udev_list_entry *list_entry;
912541b0 322 char filename[UTIL_PATH_SIZE];
912541b0
KS
323
324 /* remove/update symlinks, remove symlinks from name index */
325 udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
8a173387 326 link_update(dev, udev_list_entry_get_name(list_entry), false);
912541b0
KS
327
328 /* remove /dev/{block,char}/$major:$minor */
4cb72937 329 snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
090be865 330 streq(udev_device_get_subsystem(dev), "block") ? "block" : "char",
912541b0
KS
331 major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
332 unlink(filename);
ea733a2f 333}