udev-node.c revision cb14f4543a941ff8a22ef2725df86b3b0190a189
/*
* Copyright (C) 2004-2008 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 <fcntl.h>
#include <unistd.h>
#include <errno.h>
#include <grp.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sys/types.h>
#include "udev.h"
#define TMP_FILE_EXT ".udev-tmp"
/* reverse mapping from the device file name to the devpath */
static int name_index(struct udev *udev, const char *devpath, const char *name, int add)
{
char device[UTIL_PATH_SIZE];
char filename[UTIL_PATH_SIZE * 2];
size_t devlen = strlen(udev_get_dev_path(udev))+1;
size_t start;
int fd;
/* directory with device name */
util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename));
start = util_strlcat(filename, "/.udev/names/", sizeof(filename));
util_strlcat(filename, &name[devlen], sizeof(filename));
util_path_encode(&filename[start], sizeof(filename) - start);
/* entry with the devpath */
util_strlcpy(device, devpath, sizeof(device));
util_path_encode(device, sizeof(device));
util_strlcat(filename, "/", sizeof(filename));
util_strlcat(filename, device, sizeof(filename));
if (add) {
dbg(udev, "creating index: '%s'\n", filename);
util_create_path(udev, filename);
fd = open(filename, O_WRONLY|O_TRUNC|O_CREAT, 0644);
if (fd > 0)
close(fd);
} else {
dbg(udev, "removing index: '%s'\n", filename);
unlink(filename);
util_delete_path(udev, filename);
}
return 0;
}
int udev_node_mknod(struct udev_device *dev, const char *file, dev_t devnum, mode_t mode, uid_t uid, gid_t gid)
{
struct udev *udev = udev_device_get_udev(dev);
struct stat stats;
int preserve = 0;
int err = 0;
if (major(devnum) == 0)
devnum = udev_device_get_devnum(dev);
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);
preserve = 1;
udev_selinux_lsetfilecon(udev, file, mode);
} else {
char file_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)];
info(udev, "atomically replace existing file '%s'\n", file);
util_strlcpy(file_tmp, file, sizeof(file_tmp));
util_strlcat(file_tmp, TMP_FILE_EXT, sizeof(file_tmp));
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, %#o, %u, %u) failed: %m\n",
file_tmp, mode, major(devnum), minor(devnum));
goto exit;
}
err = rename(file_tmp, file);
if (err != 0) {
err(udev, "rename(%s, %s) failed: %m\n", file_tmp, file);
unlink(file_tmp);
}
}
} else {
info(udev, "mknod(%s, %#o, (%u,%u))\n", file, mode, major(devnum), minor(devnum));
udev_selinux_setfscreatecon(udev, file, mode);
err = mknod(file, mode, devnum);
udev_selinux_resetfscreatecon(udev);
if (err != 0) {
err(udev, "mknod(%s, %#o, (%u,%u) failed: %m\n", file, mode, major(devnum), minor(devnum));
goto exit;
}
}
if (!preserve || stats.st_mode != mode) {
info(udev, "chmod(%s, %#o)\n", file, mode);
err = chmod(file, mode);
if (err != 0) {
err(udev, "chmod(%s, %#o) failed: %m\n", file, mode);
goto exit;
}
}
if (!preserve || stats.st_uid != uid || stats.st_gid != gid) {
info(udev, "chown(%s, %u, %u)\n", file, uid, gid);
err = chown(file, uid, gid);
if (err != 0) {
err(udev, "chown(%s, %u, %u) failed: %m\n", file, uid, gid);
goto exit;
}
}
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 slink_tmp[UTIL_PATH_SIZE + sizeof(TMP_FILE_EXT)];
int i = 0;
int tail = 0;
int len;
int err = 0;
/* use relative link */
target[0] = '\0';
while (node[i] && (node[i] == slink[i])) {
if (node[i] == '/')
tail = i+1;
i++;
}
while (slink[i] != '\0') {
if (slink[i] == '/')
util_strlcat(target, "../", sizeof(target));
i++;
}
util_strlcat(target, &node[tail], sizeof(target));
/* 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) {
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];
dbg(udev, "found existing symlink '%s'\n", slink);
len = readlink(slink, buf, sizeof(buf));
if (len > 0) {
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);
goto exit;
}
}
}
} else {
info(udev, "creating symlink '%s' to '%s'\n", slink, target);
udev_selinux_setfscreatecon(udev, slink, S_IFLNK);
err = symlink(target, slink);
udev_selinux_resetfscreatecon(udev);
if (err == 0)
goto exit;
}
info(udev, "atomically replace '%s'\n", slink);
util_strlcpy(slink_tmp, slink, sizeof(slink_tmp));
util_strlcat(slink_tmp, TMP_FILE_EXT, sizeof(slink_tmp));
unlink(slink_tmp);
udev_selinux_setfscreatecon(udev, slink, S_IFLNK);
err = symlink(target, slink_tmp);
udev_selinux_resetfscreatecon(udev);
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);
goto exit;
}
exit:
return err;
}
static int name_index_get_devices(struct udev *udev, const char *name, struct udev_list_node *dev_list)
{
char dirname[PATH_MAX];
size_t devlen = strlen(udev_get_dev_path(udev))+1;
size_t start;
DIR *dir;
int count = 0;
util_strlcpy(dirname, udev_get_dev_path(udev), sizeof(dirname));
start = util_strlcat(dirname, "/.udev/names/", sizeof(dirname));
util_strlcat(dirname, &name[devlen], sizeof(dirname));
util_path_encode(&dirname[start], sizeof(dirname) - start);
dir = opendir(dirname);
if (dir == NULL) {
dbg(udev, "no index directory '%s': %m\n", dirname);
count = -1;
goto out;
}
dbg(udev, "found index directory '%s'\n", dirname);
while (1) {
struct dirent *ent;
char device[UTIL_PATH_SIZE];
ent = readdir(dir);
if (ent == NULL || ent->d_name[0] == '\0')
break;
if (ent->d_name[0] == '.')
continue;
util_strlcpy(device, udev_get_sys_path(udev), sizeof(device));
util_strlcat(device, ent->d_name, sizeof(device));
util_path_decode(device);
udev_list_entry_add(udev, dev_list, device, NULL, 1, 0);
count++;
}
closedir(dir);
out:
return count;
}
static int update_link(struct udev_device *dev, const char *slink)
{
struct udev *udev = udev_device_get_udev(dev);
struct udev_list_node dev_list;
struct udev_list_entry *dev_entry;
char target[UTIL_PATH_SIZE];
int count;
int priority = 0;
int rc = 0;
dbg(udev, "update symlink '%s' of '%s'\n", slink, udev_device_get_syspath(dev));
udev_list_init(&dev_list);
count = name_index_get_devices(udev, slink, &dev_list);
if (count > 1)
info(udev, "found %i devices with name '%s'\n", count, slink);
/* if we don't have a reference, delete it */
if (count <= 0) {
info(udev, "no reference left, remove '%s'\n", slink);
unlink(slink);
util_delete_path(udev, slink);
goto out;
}
/* find the device with the highest priority */
target[0] = '\0';
udev_list_entry_foreach(dev_entry, udev_list_get_entry(&dev_list)) {
const char *syspath;
struct udev_device *dev_db;
const char *devnode;
syspath = udev_list_entry_get_name(dev_entry);
dbg(udev, "found '%s' for '%s'\n", syspath, slink);
/* did we find ourself? we win, if we have the same priority */
if (strcmp(udev_device_get_syspath(dev), syspath) == 0) {
dbg(udev, "compare (our own) priority of '%s' %i >= %i\n",
udev_device_get_devpath(dev), udev_device_get_devlink_priority(dev), priority);
if (strcmp(udev_device_get_devnode(dev), slink) == 0) {
info(udev, "'%s' is our device node, database inconsistent, skip link update\n",
udev_device_get_devnode(dev));
} else if (target[0] == '\0' || udev_device_get_devlink_priority(dev) >= priority) {
priority = udev_device_get_devlink_priority(dev);
util_strlcpy(target, udev_device_get_devnode(dev), sizeof(target));
}
continue;
}
/* another device, read priority from database */
dev_db = udev_device_new_from_syspath(udev, syspath);
if (dev_db == NULL)
continue;
devnode = udev_device_get_devnode(dev_db);
if (devnode != NULL) {
if (strcmp(devnode, slink) == 0) {
info(udev, "'%s' is a device node of '%s', skip link update\n",
devnode, syspath);
} else {
dbg(udev, "compare priority of '%s' %i > %i\n",
udev_device_get_devpath(dev_db),
udev_device_get_devlink_priority(dev_db),
priority);
if (target[0] == '\0' || udev_device_get_devlink_priority(dev_db) > priority) {
priority = udev_device_get_devlink_priority(dev_db);
util_strlcpy(target, devnode, sizeof(target));
}
}
}
udev_device_unref(dev_db);
}
udev_list_cleanup_entries(udev, &dev_list);
if (target[0] == '\0') {
info(udev, "no current target for '%s' found\n", slink);
rc = 1;
goto out;
}
/* create symlink to the target with the highest priority */
info(udev, "'%s' with target '%s' has the highest priority %i, create it\n", slink, target, priority);
util_create_path(udev, slink);
node_symlink(udev, target, slink);
out:
return rc;
}
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;
const char *devnode_old;
/* 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 is now our node name */
if (strcmp(name, udev_device_get_devnode(dev)) == 0)
continue;
/* 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));
name_index(udev, udev_device_get_devpath(dev), name, 0);
update_link(dev, name);
}
/*
* if the node name has changed, delete the node,
* and possibly restore a symlink of a different device
*/
devnode_old = udev_device_get_devnode(dev_old);
if (devnode_old != NULL) {
const char *devnode = udev_device_get_devnode(dev);
if (devnode != NULL && strcmp(devnode_old, devnode) != 0) {
info(udev, "node has changed from '%s' to '%s'\n", devnode_old, devnode);
name_index(udev, udev_device_get_devpath(dev), devnode_old, 0);
update_link(dev, devnode_old);
}
}
}
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);
int i;
int num;
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);
util_create_path(udev, udev_device_get_devnode(dev));
if (udev_node_mknod(dev, NULL, makedev(0,0), mode, uid, gid) != 0) {
err = -1;
goto exit;
}
/* create all_partitions if requested */
num = udev_device_get_num_fake_partitions(dev);
if (num > 0) {
info(udev, "creating device partition nodes '%s[1-%i]'\n", udev_device_get_devnode(dev), num);
for (i = 1; i <= num; i++) {
char partitionname[UTIL_PATH_SIZE];
dev_t part_devnum;
snprintf(partitionname, sizeof(partitionname), "%s%d",
udev_device_get_devnode(dev), i);
partitionname[sizeof(partitionname)-1] = '\0';
part_devnum = makedev(major(udev_device_get_devnum(dev)),
minor(udev_device_get_devnum(dev)) + i);
udev_node_mknod(dev, partitionname, part_devnum, mode, uid, gid);
}
}
/* add node to name index */
name_index(udev, udev_device_get_devpath(dev), udev_device_get_devnode(dev), 1);
/* create/update symlinks, add symlinks to name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) {
name_index(udev, udev_device_get_devpath(dev), udev_list_entry_get_name(list_entry), 1);
update_link(dev, udev_list_entry_get_name(list_entry));
}
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;
char partitionname[UTIL_PATH_SIZE];
struct stat stats;
int err = 0;
int num;
/* remove node from name index */
name_index(udev, udev_device_get_devpath(dev), udev_device_get_devnode(dev), 0);
/* remove,update symlinks, remove symlinks from name index */
udev_list_entry_foreach(list_entry, udev_device_get_devlinks_list_entry(dev)) {
name_index(udev, udev_device_get_devpath(dev), udev_list_entry_get_name(list_entry), 0);
update_link(dev, udev_list_entry_get_name(list_entry));
}
devnode = udev_device_get_devnode(dev);
if (devnode == NULL)
return 0;
if (stat(devnode, &stats) != 0) {
info(udev, "device node '%s' not found\n", devnode);
return 0;
}
if (stats.st_rdev != udev_device_get_devnum(dev)) {
info(udev, "device node '%s' points to a different device, skip removal\n", devnode);
return -1;
}
info(udev, "removing device node '%s'\n", devnode);
err = util_unlink_secure(udev, devnode);
if (err)
return err;
num = udev_device_get_num_fake_partitions(dev);
if (num > 0) {
int i;
info(udev, "removing all_partitions '%s[1-%i]'\n", devnode, num);
if (num > 255)
return -1;
for (i = 1; i <= num; i++) {
snprintf(partitionname, sizeof(partitionname), "%s%d", devnode, i);
partitionname[sizeof(partitionname)-1] = '\0';
util_unlink_secure(udev, partitionname);
}
}
util_delete_path(udev, devnode);
return err;
}