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systemd/udev/udev-watch.c
Alan Jenkins 4b09a2fc43 avoid leaking netlink socket fd to external programs
The netlink socket is now used by udev event processes. We should take
care not to pass it to the programs they execute. This is the same way
the inotify fd was handled.

Signed-off-by: Alan Jenkins <alan-jenkins@tuffmail.co.uk>
2009-04-06 07:23:35 -07:00

185 lines
4.9 KiB
C

/*
* Copyright (C) 2004-2008 Kay Sievers <kay.sievers@vrfy.org>
* Copyright (C) 2009 Canonical Ltd.
* Copyright (C) 2009 Scott James Remnant <scott@netsplit.com>
*
* 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 <sys/types.h>
#include <errno.h>
#include <fcntl.h>
#include <stdio.h>
#include <dirent.h>
#include <stddef.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#ifdef HAVE_INOTIFY
#include <sys/inotify.h>
#endif
#include "udev.h"
int inotify_fd = -1;
/* inotify descriptor, will be shared with rules directory;
* set to cloexec since we need our children to be able to add
* watches for us
*/
void udev_watch_init(struct udev *udev)
{
inotify_fd = inotify_init();
if (inotify_fd >= 0)
util_set_fd_cloexec(inotify_fd);
else if (errno == ENOSYS)
info(udev, "unable to use inotify, udevd will not monitor rule files changes\n");
else
err(udev, "inotify_init failed: %m\n");
}
/* move any old watches directory out of the way, and then restore
* the watches
*/
void udev_watch_restore(struct udev *udev)
{
char filename[UTIL_PATH_SIZE], oldname[UTIL_PATH_SIZE];
if (inotify_fd < 0)
return;
util_strlcpy(oldname, udev_get_dev_path(udev), sizeof(oldname));
util_strlcat(oldname, "/.udev/watch.old", sizeof(oldname));
util_strlcpy(filename, udev_get_dev_path(udev), sizeof(filename));
util_strlcat(filename, "/.udev/watch", sizeof(filename));
if (rename(filename, oldname) == 0) {
DIR *dir;
struct dirent *ent;
dir = opendir(oldname);
if (dir == NULL) {
err(udev, "unable to open old watches dir '%s', old watches will not be restored: %m", oldname);
return;
}
while ((ent = readdir(dir)) != NULL) {
char path[UTIL_PATH_SIZE];
char buf[UTIL_PATH_SIZE];
ssize_t syslen;
ssize_t len;
struct udev_device *dev;
if (ent->d_name[0] < '0' || ent->d_name[0] > '9')
continue;
util_strlcpy(path, oldname, sizeof(path));
util_strlcat(path, "/", sizeof(path));
util_strlcat(path, ent->d_name, sizeof(path));
syslen = util_strlcpy(buf, udev_get_sys_path(udev), sizeof(buf));
len = readlink(path, &buf[syslen], sizeof(buf)-syslen);
if (len <= 0 || len >= (ssize_t)(sizeof(buf)-syslen)) {
unlink(path);
continue;
}
buf[syslen + len] = '\0';
dbg(udev, "old watch to '%s' found\n", buf);
dev = udev_device_new_from_syspath(udev, buf);
if (dev == NULL) {
unlink(path);
continue;
}
info(udev, "restoring old watch on '%s'\n", udev_device_get_devnode(dev));
udev_watch_begin(udev, dev);
udev_device_unref(dev);
unlink(path);
}
closedir(dir);
rmdir(oldname);
} else if (errno != ENOENT) {
err(udev, "unable to move watches dir '%s', old watches will not be restored: %m", filename);
}
}
void udev_watch_begin(struct udev *udev, struct udev_device *dev)
{
char filename[UTIL_PATH_SIZE];
int wd;
if (inotify_fd < 0)
return;
info(udev, "adding watch on '%s'\n", udev_device_get_devnode(dev));
wd = inotify_add_watch(inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
if (wd < 0) {
err(udev, "inotify_add_watch(%d, %s, %o) failed: %m\n",
inotify_fd, udev_device_get_devnode(dev), IN_CLOSE_WRITE);
}
snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
util_create_path(udev, filename);
unlink(filename);
symlink(udev_device_get_devpath(dev), filename);
udev_device_set_watch_handle(dev, wd);
}
void udev_watch_end(struct udev *udev, struct udev_device *dev)
{
int wd;
char filename[UTIL_PATH_SIZE];
if (inotify_fd < 0)
return;
wd = udev_device_get_watch_handle(dev);
if (wd < 0)
return;
info(udev, "removing watch on '%s'\n", udev_device_get_devnode(dev));
inotify_rm_watch(inotify_fd, wd);
snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
unlink(filename);
udev_device_set_watch_handle(dev, -1);
}
struct udev_device *udev_watch_lookup(struct udev *udev, int wd)
{
char filename[UTIL_PATH_SIZE];
char buf[UTIL_PATH_SIZE];
ssize_t syslen;
ssize_t len;
if (inotify_fd < 0 || wd < 0)
return NULL;
snprintf(filename, sizeof(filename), "%s/.udev/watch/%d", udev_get_dev_path(udev), wd);
syslen = util_strlcpy(buf, udev_get_sys_path(udev), sizeof(buf));
len = readlink(filename, &buf[syslen], sizeof(buf)-syslen);
if (len > 0 || len < (ssize_t)(sizeof(buf)-syslen)) {
buf[syslen + len] = '\0';
return udev_device_new_from_syspath(udev, buf);
}
return NULL;
}