udev_node.c revision 44aff4cd6d74d230e4a97f8d59f780472b7cad6e
/*
* Copyright (C) 2003 Greg Kroah-Hartman <greg@kroah.com>
* Copyright (C) 2004-2006 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 version 2 of the License.
*
* 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, write to the Free Software Foundation, Inc.,
* 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*
*/
#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"
#include "udev_rules.h"
#include "udev_selinux.h"
#define TMP_FILE_EXT ".udev-tmp"
int udev_node_mknod(struct udevice *udev, const char *file, dev_t devt, mode_t mode, uid_t uid, gid_t gid)
{
char file_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
struct stat stats;
int preserve = 0;
int err = 0;
if (major(devt) != 0 && strcmp(udev->dev->subsystem, "block") == 0)
mode |= S_IFBLK;
else
mode |= S_IFCHR;
if (lstat(file, &stats) == 0) {
if (((stats.st_mode & S_IFMT) == (mode & S_IFMT)) && (stats.st_rdev == devt)) {
info("preserve file '%s', because it has correct dev_t\n", file);
preserve = 1;
selinux_setfilecon(file, udev->dev->kernel, mode);
} else {
info("atomically replace existing file '%s'\n", file);
strlcpy(file_tmp, file, sizeof(file_tmp));
strlcat(file_tmp, TMP_FILE_EXT, sizeof(file_tmp));
unlink(file_tmp);
selinux_setfscreatecon(file_tmp, udev->dev->kernel, mode);
err = mknod(file_tmp, mode, devt);
selinux_resetfscreatecon();
if (err != 0) {
err("mknod(%s, %#o, %u, %u) failed: %s\n",
file_tmp, mode, major(devt), minor(devt), strerror(errno));
goto exit;
}
err = rename(file_tmp, file);
if (err != 0) {
err("rename(%s, %s) failed: %s\n",
file_tmp, file, strerror(errno));
unlink(file_tmp);
}
}
} else {
info("mknod(%s, %#o, (%u,%u))\n", file, mode, major(devt), minor(devt));
selinux_setfscreatecon(file, udev->dev->kernel, mode);
err = mknod(file, mode, devt);
selinux_resetfscreatecon();
if (err != 0) {
err("mknod(%s, %#o, (%u,%u) failed: %s\n",
file, mode, major(devt), minor(devt), strerror(errno));
goto exit;
}
}
if (!preserve || stats.st_mode != mode) {
info("chmod(%s, %#o)\n", file, mode);
err = chmod(file, mode);
if (err != 0) {
err("chmod(%s, %#o) failed: %s\n", file, mode, strerror(errno));
goto exit;
}
}
if (!preserve || stats.st_uid != uid || stats.st_gid != gid) {
info("chown(%s, %u, %u)\n", file, uid, gid);
err = chown(file, uid, gid);
if (err != 0) {
err("chown(%s, %u, %u) failed: %s\n", file, uid, gid, strerror(errno));
goto exit;
}
}
exit:
return err;
}
static int node_symlink(const char *node, const char *slink)
{
struct stat stats;
char target[PATH_SIZE] = "";
char slink_tmp[PATH_SIZE + sizeof(TMP_FILE_EXT)];
int i = 0;
int tail = 0;
int len;
int retval = 0;
/* use relative link */
while (node[i] && (node[i] == slink[i])) {
if (node[i] == '/')
tail = i+1;
i++;
}
while (slink[i] != '\0') {
if (slink[i] == '/')
strlcat(target, "../", sizeof(target));
i++;
}
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("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("replace device node '%s' with symlink to our node '%s'\n", slink, node);
} else {
err("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[PATH_SIZE];
info("found existing symlink '%s'\n", slink);
len = readlink(slink, buf, sizeof(buf));
if (len > 0) {
buf[len] = '\0';
if (strcmp(target, buf) == 0) {
info("preserve already existing symlink '%s' to '%s'\n", slink, target);
selinux_setfilecon(slink, NULL, S_IFLNK);
goto exit;
}
}
}
} else {
info("creating symlink '%s' to '%s'\n", slink, target);
selinux_setfscreatecon(slink, NULL, S_IFLNK);
retval = symlink(target, slink);
selinux_resetfscreatecon();
if (retval == 0)
goto exit;
}
info("atomically replace '%s'\n", slink);
strlcpy(slink_tmp, slink, sizeof(slink_tmp));
strlcat(slink_tmp, TMP_FILE_EXT, sizeof(slink_tmp));
unlink(slink_tmp);
selinux_setfscreatecon(slink, NULL, S_IFLNK);
retval = symlink(target, slink_tmp);
selinux_resetfscreatecon();
if (retval != 0) {
err("symlink(%s, %s) failed: %s\n", target, slink_tmp, strerror(errno));
goto exit;
}
retval = rename(slink_tmp, slink);
if (retval != 0) {
err("rename(%s, %s) failed: %s\n", slink_tmp, slink, strerror(errno));
unlink(slink_tmp);
goto exit;
}
exit:
return retval;
}
static int update_link(struct udevice *udev, const char *name)
{
LIST_HEAD(name_list);
char slink[PATH_SIZE];
char node[PATH_SIZE];
struct udevice *udev_db;
struct name_entry *device;
char target[PATH_MAX] = "";
int count;
int priority = 0;
int rc = 0;
strlcpy(slink, udev_root, sizeof(slink));
strlcat(slink, "/", sizeof(slink));
strlcat(slink, name, sizeof(slink));
count = udev_db_get_devices_by_name(name, &name_list);
info("found %i devices with name '%s'\n", count, name);
/* if we don't have a reference, delete it */
if (count <= 0) {
info("no reference left, remove '%s'\n", name);
if (!udev->test_run) {
unlink(slink);
delete_path(slink);
}
goto out;
}
/* find the device with the highest priority */
list_for_each_entry(device, &name_list, node) {
info("found '%s' for '%s'\n", device->name, name);
/* did we find ourself? we win, if we have the same priority */
if (strcmp(udev->dev->devpath, device->name) == 0) {
info("compare (our own) priority of '%s' %i >= %i\n",
udev->dev->devpath, udev->link_priority, priority);
if (strcmp(udev->name, name) == 0) {
info("'%s' is our device node, database inconsistent, skip link update\n", udev->name);
} else if (target[0] == '\0' || udev->link_priority >= priority) {
priority = udev->link_priority;
strlcpy(target, udev->name, sizeof(target));
}
continue;
}
/* another device, read priority from database */
udev_db = udev_device_init();
if (udev_db == NULL)
continue;
if (udev_db_get_device(udev_db, device->name) == 0) {
if (strcmp(udev_db->name, name) == 0) {
info("'%s' is a device node of '%s', skip link update\n", udev_db->name, device->name);
} else {
info("compare priority of '%s' %i > %i\n",
udev_db->dev->devpath, udev_db->link_priority, priority);
if (target[0] == '\0' || udev_db->link_priority > priority) {
priority = udev_db->link_priority;
strlcpy(target, udev_db->name, sizeof(target));
}
}
}
udev_device_cleanup(udev_db);
}
name_list_cleanup(&name_list);
if (target[0] == '\0') {
info("no current target for '%s' found\n", name);
rc = 1;
goto out;
}
/* create symlink to the target with the highest priority */
strlcpy(node, udev_root, sizeof(node));
strlcat(node, "/", sizeof(node));
strlcat(node, target, sizeof(node));
info("'%s' with target '%s' has the highest priority %i, create it\n", name, target, priority);
if (!udev->test_run) {
create_path(slink);
node_symlink(node, slink);
}
out:
return rc;
}
void udev_node_update_symlinks(struct udevice *udev, struct udevice *udev_old)
{
struct name_entry *name_loop;
char symlinks[PATH_SIZE] = "";
list_for_each_entry(name_loop, &udev->symlink_list, node) {
info("update symlink '%s' of '%s'\n", name_loop->name, udev->dev->devpath);
update_link(udev, name_loop->name);
strlcat(symlinks, udev_root, sizeof(symlinks));
strlcat(symlinks, "/", sizeof(symlinks));
strlcat(symlinks, name_loop->name, sizeof(symlinks));
strlcat(symlinks, " ", sizeof(symlinks));
}
/* export symlinks to environment */
remove_trailing_chars(symlinks, ' ');
if (symlinks[0] != '\0')
setenv("DEVLINKS", symlinks, 1);
/* update possible left-over symlinks (device metadata changed) */
if (udev_old != NULL) {
struct name_entry *link_loop;
struct name_entry *link_old_loop;
int found;
/* remove current symlinks from old list */
list_for_each_entry(link_old_loop, &udev_old->symlink_list, node) {
found = 0;
list_for_each_entry(link_loop, &udev->symlink_list, node) {
if (strcmp(link_old_loop->name, link_loop->name) == 0) {
found = 1;
break;
}
}
if (!found) {
/* link does no longer belong to this device */
info("update old symlink '%s' no longer belonging to '%s'\n",
link_old_loop->name, udev->dev->devpath);
update_link(udev, link_old_loop->name);
}
}
/*
* if the node name has changed, delete the node,
* or possibly restore a symlink of another device
*/
if (strcmp(udev->name, udev_old->name) != 0)
update_link(udev, udev_old->name);
}
}
int udev_node_add(struct udevice *udev)
{
char filename[PATH_SIZE];
uid_t uid;
gid_t gid;
int i;
int retval = 0;
strlcpy(filename, udev_root, sizeof(filename));
strlcat(filename, "/", sizeof(filename));
strlcat(filename, udev->name, sizeof(filename));
create_path(filename);
if (strcmp(udev->owner, "root") == 0)
uid = 0;
else {
char *endptr;
unsigned long id;
id = strtoul(udev->owner, &endptr, 10);
if (endptr[0] == '\0')
uid = (uid_t) id;
else
uid = lookup_user(udev->owner);
}
if (strcmp(udev->group, "root") == 0)
gid = 0;
else {
char *endptr;
unsigned long id;
id = strtoul(udev->group, &endptr, 10);
if (endptr[0] == '\0')
gid = (gid_t) id;
else
gid = lookup_group(udev->group);
}
info("creating device node '%s', major=%d, minor=%d, mode=%#o, uid=%d, gid=%d\n",
filename, major(udev->devt), minor(udev->devt), udev->mode, uid, gid);
if (!udev->test_run)
if (udev_node_mknod(udev, filename, udev->devt, udev->mode, uid, gid) != 0) {
retval = -1;
goto exit;
}
setenv("DEVNAME", filename, 1);
/* create all_partitions if requested */
if (udev->partitions) {
char partitionname[PATH_SIZE];
char *attr;
int range;
/* take the maximum registered minor range */
attr = sysfs_attr_get_value(udev->dev->devpath, "range");
if (attr != NULL) {
range = atoi(attr);
if (range > 1)
udev->partitions = range-1;
}
info("creating device partition nodes '%s[1-%i]'\n", filename, udev->partitions);
if (!udev->test_run) {
for (i = 1; i <= udev->partitions; i++) {
dev_t part_devt;
snprintf(partitionname, sizeof(partitionname), "%s%d", filename, i);
partitionname[sizeof(partitionname)-1] = '\0';
part_devt = makedev(major(udev->devt), minor(udev->devt) + i);
udev_node_mknod(udev, partitionname, part_devt, udev->mode, uid, gid);
}
}
}
exit:
return retval;
}
int udev_node_remove(struct udevice *udev)
{
char filename[PATH_SIZE];
char partitionname[PATH_SIZE];
struct stat stats;
int retval = 0;
int num;
strlcpy(filename, udev_root, sizeof(filename));
strlcat(filename, "/", sizeof(filename));
strlcat(filename, udev->name, sizeof(filename));
if (stat(filename, &stats) != 0) {
info("device node '%s' not found\n", filename);
return 0;
}
if (udev->devt && stats.st_rdev != udev->devt) {
info("device node '%s' points to a different device, skip removal\n", filename);
return -1;
}
info("removing device node '%s'\n", filename);
if (!udev->test_run)
retval = unlink_secure(filename);
if (retval)
return retval;
setenv("DEVNAME", filename, 1);
num = udev->partitions;
if (num > 0) {
int i;
info("removing all_partitions '%s[1-%i]'\n", filename, num);
if (num > 255)
return -1;
for (i = 1; i <= num; i++) {
snprintf(partitionname, sizeof(partitionname), "%s%d", filename, i);
partitionname[sizeof(partitionname)-1] = '\0';
if (!udev->test_run)
unlink_secure(partitionname);
}
}
delete_path(filename);
return retval;
}