blob: f19dc4d900d05a29e4329934fb1bc1692f450196 [file] [log] [blame]
/*
* Copyright (C) 2003-2010 Kay Sievers <kay.sievers@vrfy.org>
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation, either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include <stdlib.h>
#include <string.h>
#include <stdio.h>
#include <stddef.h>
#include <stdbool.h>
#include <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <grp.h>
#include <dirent.h>
#include <sys/time.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "udev.h"
#define TMP_FILE_EXT ".udev-tmp"
int udev_node_mknod(struct udev_device *dev, const char *file, mode_t mode, uid_t uid, gid_t gid)
{
struct udev *udev = udev_device_get_udev(dev);
dev_t devnum = udev_device_get_devnum(dev);
struct stat stats;
int err = 0;
if (strcmp(udev_device_get_subsystem(dev), "block") == 0)
mode |= S_IFBLK;
else
mode |= S_IFCHR;
if (file == NULL)
file = udev_device_get_devnode(dev);
if (lstat(file, &stats) == 0) {
if (((stats.st_mode & S_IFMT) == (mode & S_IFMT)) && (stats.st_rdev == devnum)) {
info(udev, "preserve file '%s', because it has correct dev_t\n", file);
if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) {
/* preserve 'sticky' bit, if already set */
mode |= stats.st_mode & 01000;
info(udev, "set permissions %s, %#o, uid=%u, gid=%u\n", file, mode, uid, gid);
chmod(file, mode);
chown(file, uid, gid);
} else {
info(udev, "preserve permissions %s, %#o, uid=%u, gid=%u\n", file, mode, uid, gid);
}
/*
* Set initial selinux file context only on add events.
* We set the proper context on bootup (triger) or for newly
* added devices, but we don't change it later, in case
* something else has set a custom context in the meantime.
*/
if (strcmp(udev_device_get_action(dev), "add") == 0)
udev_selinux_lsetfilecon(udev, file, mode);
/* always update timestamp when we re-use the node, like on media change events */
utimensat(AT_FDCWD, file, NULL, 0);
} else {
char file_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)];
info(udev, "atomically replace existing file '%s'\n", file);
util_strscpyl(file_tmp, sizeof(file_tmp), file, TMP_FILE_EXT, NULL);
unlink(file_tmp);
udev_selinux_setfscreatecon(udev, file_tmp, mode);
err = mknod(file_tmp, mode, devnum);
udev_selinux_resetfscreatecon(udev);
if (err != 0) {
err(udev, "mknod '%s' %u:%u %#o failed: %m\n",
file_tmp, major(devnum), minor(devnum), mode);
goto exit;
}
err = rename(file_tmp, file);
if (err != 0) {
err(udev, "rename '%s' '%s' failed: %m\n", file_tmp, file);
unlink(file_tmp);
goto exit;
}
info(udev, "set permissions '%s' %#o uid=%u gid=%u\n", file, mode, uid, gid);
chmod(file, mode);
chown(file, uid, gid);
}
} else {
info(udev, "mknod '%s' %u:%u %#o\n", file, major(devnum), minor(devnum), mode);
do {
err = util_create_path_selinux(udev, file);
if (err != 0 && err != -ENOENT)
break;
udev_selinux_setfscreatecon(udev, file, mode);
err = mknod(file, mode, devnum);
if (err != 0)
err = -errno;
udev_selinux_resetfscreatecon(udev);
} while (err == -ENOENT);
if (err != 0 && err != -EEXIST)
err(udev, "mknod '%s' %u:%u %#o' failed: %m\n", file, major(devnum), minor(devnum), mode);
info(udev, "set permissions '%s' %#o uid=%u gid=%u\n", file, mode, uid, gid);
chmod(file, mode);
chown(file, uid, gid);
}
exit:
return err;
}
static int node_symlink(struct udev *udev, const char *node, const char *slink)
{
struct stat stats;
char target[UTIL_PATH_SIZE];
char *s;
size_t l;
char slink_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)];
int i = 0;
int tail = 0;
int err = 0;
/* use relative link */
target[0] = '\0';
while (node[i] && (node[i] == slink[i])) {
if (node[i] == '/')
tail = i+1;
i++;
}
s = target;
l = sizeof(target);
while (slink[i] != '\0') {
if (slink[i] == '/')
l = util_strpcpy(&s, l, "../");
i++;
}
l = util_strscpy(s, l, &node[tail]);
if (l == 0) {
err = -EINVAL;
goto exit;
}
/* preserve link with correct target, do not replace node of other device */
if (lstat(slink, &stats) == 0) {
if (S_ISBLK(stats.st_mode) || S_ISCHR(stats.st_mode)) {
struct stat stats2;
info(udev, "found existing node instead of symlink '%s'\n", slink);
if (lstat(node, &stats2) == 0) {
if ((stats.st_mode & S_IFMT) == (stats2.st_mode & S_IFMT) &&
stats.st_rdev == stats2.st_rdev && stats.st_ino != stats2.st_ino) {
info(udev, "replace device node '%s' with symlink to our node '%s'\n",
slink, node);
} else {
err(udev, "device node '%s' already exists, "
"link to '%s' will not overwrite it\n",
slink, node);
goto exit;
}
}
} else if (S_ISLNK(stats.st_mode)) {
char buf[UTIL_PATH_SIZE];
int len;
dbg(udev, "found existing symlink '%s'\n", slink);
len = readlink(slink, buf, sizeof(buf));
if (len > 0 && len < (int)sizeof(buf)) {
buf[len] = '\0';
if (strcmp(target, buf) == 0) {
info(udev, "preserve already existing symlink '%s' to '%s'\n",
slink, target);
udev_selinux_lsetfilecon(udev, slink, S_IFLNK);
utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW);
goto exit;
}
}
}
} else {
info(udev, "creating symlink '%s' to '%s'\n", slink, target);
do {
err = util_create_path_selinux(udev, slink);
if (err != 0 && err != -ENOENT)
break;
udev_selinux_setfscreatecon(udev, slink, S_IFLNK);
err = symlink(target, slink);
if (err != 0)
err = -errno;
udev_selinux_resetfscreatecon(udev);
} while (err == -ENOENT);
if (err == 0)
goto exit;
}
info(udev, "atomically replace '%s'\n", slink);
util_strscpyl(slink_tmp, sizeof(slink_tmp), slink, TMP_FILE_EXT, NULL);
unlink(slink_tmp);
do {
err = util_create_path_selinux(udev, slink_tmp);
if (err != 0 && err != -ENOENT)
break;
udev_selinux_setfscreatecon(udev, slink_tmp, S_IFLNK);
err = symlink(target, slink_tmp);
if (err != 0)
err = -errno;
udev_selinux_resetfscreatecon(udev);
} while (err == -ENOENT);
if (err != 0) {
err(udev, "symlink '%s' '%s' failed: %m\n", target, slink_tmp);
goto exit;
}
err = rename(slink_tmp, slink);
if (err != 0) {
err(udev, "rename '%s' '%s' failed: %m\n", slink_tmp, slink);
unlink(slink_tmp);
}
exit:
return err;
}
/* find device node of device with highest priority */
static const char *link_find_prioritized(struct udev_device *dev, bool add, const char *stackdir, char *buf, size_t bufsize)
{
struct udev *udev = udev_device_get_udev(dev);
DIR *dir;
int priority = 0;
const char *target = NULL;
if (add) {
priority = udev_device_get_devlink_priority(dev);
util_strscpy(buf, bufsize, udev_device_get_devnode(dev));
target = buf;
}
dir = opendir(stackdir);
if (dir == NULL)
return target;
for (;;) {
struct udev_device *dev_db;
struct dirent *dent;
dent = readdir(dir);
if (dent == NULL || dent->d_name[0] == '\0')
break;
if (dent->d_name[0] == '.')
continue;
info(udev, "found '%s' claiming '%s'\n", dent->d_name, stackdir);
/* did we find ourself? */
if (strcmp(dent->d_name, udev_device_get_id_filename(dev)) == 0)
continue;
dev_db = udev_device_new_from_id_filename(udev, dent->d_name);
if (dev_db != NULL) {
const char *devnode;
devnode = udev_device_get_devnode(dev_db);
if (devnode != NULL) {
dbg(udev, "compare priority of '%s'(%i) > '%s'(%i)\n", target, priority,
udev_device_get_devnode(dev_db), udev_device_get_devlink_priority(dev_db));
if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) {
info(udev, "'%s' claims priority %i for '%s'\n",
udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir);
priority = udev_device_get_devlink_priority(dev_db);
util_strscpy(buf, bufsize, devnode);
target = buf;
}
}
udev_device_unref(dev_db);
}
}
closedir(dir);
return target;
}
/* manage "stack of names" with possibly specified device priorities */
static void link_update(struct udev_device *dev, const char *slink, bool add)
{
struct udev *udev = udev_device_get_udev(dev);
char name_enc[UTIL_PATH_SIZE];
char filename[UTIL_PATH_SIZE * 2];
char dirname[UTIL_PATH_SIZE];
const char *target;
char buf[UTIL_PATH_SIZE];
dbg(udev, "update symlink '%s' of '%s'\n", slink, udev_device_get_syspath(dev));
util_path_encode(&slink[strlen(udev_get_dev_path(udev))+1], name_enc, sizeof(name_enc));
util_strscpyl(dirname, sizeof(dirname), udev_get_run_path(udev), "/links/", name_enc, NULL);
util_strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL);
if (!add) {
dbg(udev, "removing index: '%s'\n", filename);
if (unlink(filename) == 0)
rmdir(dirname);
}
target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf));
if (target == NULL) {
info(udev, "no reference left, remove '%s'\n", slink);
if (unlink(slink) == 0)
util_delete_path(udev, slink);
} else {
info(udev, "creating link '%s' to '%s'\n", slink, target);
node_symlink(udev, target, slink);
}
if (add) {
int err;
dbg(udev, "creating index: '%s'\n", filename);
do {
int fd;
err = util_create_path(udev, filename);
if (err != 0 && err != -ENOENT)
break;
fd = open(filename, O_WRONLY|O_CREAT|O_CLOEXEC|O_TRUNC|O_NOFOLLOW, 0444);
if (fd >= 0)
close(fd);
else
err = -errno;
} while (err == -ENOENT);
}
}
void udev_node_update_old_links(struct udev_device *dev, struct udev_device *dev_old)
{
struct udev *udev = udev_device_get_udev(dev);
struct udev_list_entry *list_entry;
/* update possible left-over symlinks */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev_old)) {
const char *name = udev_list_entry_get_name(list_entry);
struct udev_list_entry *list_entry_current;
int found;
/* check if old link name still belongs to this device */
found = 0;
udev_list_entry_foreach(list_entry_current, udev_device_get_devlinks_list_entry(dev)) {
const char *name_current = udev_list_entry_get_name(list_entry_current);
if (strcmp(name, name_current) == 0) {
found = 1;
break;
}
}
if (found)
continue;
info(udev, "update old name, '%s' no longer belonging to '%s'\n",
name, udev_device_get_devpath(dev));
link_update(dev, name, 0);
}
}
int udev_node_add(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid)
{
struct udev *udev = udev_device_get_udev(dev);
char filename[UTIL_PATH_SIZE];
struct udev_list_entry *list_entry;
int err = 0;
info(udev, "creating device node '%s', devnum=%d:%d, mode=%#o, uid=%d, gid=%d\n",
udev_device_get_devnode(dev),
major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)),
mode, uid, gid);
if (udev_node_mknod(dev, NULL, mode, uid, gid) != 0) {
err = -1;
goto exit;
}
/* always add /dev/{block,char}/$major:$minor */
snprintf(filename, sizeof(filename), "%s/%s/%u:%u",
udev_get_dev_path(udev),
strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char",
major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
node_symlink(udev, udev_device_get_devnode(dev), filename);
/* create/update symlinks, add symlinks to name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) {
if (udev_list_entry_get_num(list_entry))
/* simple unmanaged link name */
node_symlink(udev, udev_device_get_devnode(dev), udev_list_entry_get_name(list_entry));
else
link_update(dev, udev_list_entry_get_name(list_entry), 1);
}
exit:
return err;
}
int udev_node_remove(struct udev_device *dev)
{
struct udev *udev = udev_device_get_udev(dev);
struct udev_list_entry *list_entry;
const char *devnode;
struct stat stats;
struct udev_device *dev_check;
char filename[UTIL_PATH_SIZE];
int err = 0;
/* remove/update symlinks, remove symlinks from name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev))
link_update(dev, udev_list_entry_get_name(list_entry), 0);
devnode = udev_device_get_devnode(dev);
if (devnode == NULL)
goto out;
if (stat(devnode, &stats) != 0) {
info(udev, "device node '%s' not found\n", devnode);
goto out;
}
if (stats.st_rdev != udev_device_get_devnum(dev)) {
info(udev, "device node '%s' points to a different device, skip removal\n", devnode);
err = -1;
goto out;
}
if (stats.st_mode & 01000) {
info(udev, "device node '%s' has sticky bit set, skip removal\n", devnode);
goto out;
}
dev_check = udev_device_new_from_syspath(udev, udev_device_get_syspath(dev));
if (dev_check != NULL) {
/* do not remove device node if the same sys-device is re-created in the meantime */
info(udev, "keeping device node of existing device'%s'\n", devnode);
udev_device_unref(dev_check);
goto out;
}
info(udev, "removing device node '%s'\n", devnode);
err = util_unlink_secure(udev, devnode);
if (err == 0)
util_delete_path(udev, devnode);
/* remove /dev/{block,char}/$major:$minor */
snprintf(filename, sizeof(filename), "%s/%s/%u:%u",
udev_get_dev_path(udev),
strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char",
major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
unlink(filename);
out:
return err;
}