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-rw-r--r--src/udev/udev-node.c342
1 files changed, 342 insertions, 0 deletions
diff --git a/src/udev/udev-node.c b/src/udev/udev-node.c
new file mode 100644
index 0000000000..7774303704
--- /dev/null
+++ b/src/udev/udev-node.c
@@ -0,0 +1,342 @@
+/*
+ * Copyright (C) 2003-2010 Kay Sievers <kay@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"
+
+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)) {
+ log_error("conflicting device node '%s' found, link to '%s' will not be created\n", slink, node);
+ goto exit;
+ } else if (S_ISLNK(stats.st_mode)) {
+ char buf[UTIL_PATH_SIZE];
+ int len;
+
+ len = readlink(slink, buf, sizeof(buf));
+ if (len > 0 && len < (int)sizeof(buf)) {
+ buf[len] = '\0';
+ if (strcmp(target, buf) == 0) {
+ log_debug("preserve already existing symlink '%s' to '%s'\n", slink, target);
+ label_fix(slink, true, false);
+ utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW);
+ goto exit;
+ }
+ }
+ }
+ } else {
+ log_debug("creating symlink '%s' to '%s'\n", slink, target);
+ do {
+ err = mkdir_parents_label(slink, 0755);
+ if (err != 0 && err != -ENOENT)
+ break;
+ label_context_set(slink, S_IFLNK);
+ err = symlink(target, slink);
+ if (err != 0)
+ err = -errno;
+ label_context_clear();
+ } while (err == -ENOENT);
+ if (err == 0)
+ goto exit;
+ }
+
+ log_debug("atomically replace '%s'\n", slink);
+ util_strscpyl(slink_tmp, sizeof(slink_tmp), slink, TMP_FILE_EXT, NULL);
+ unlink(slink_tmp);
+ do {
+ err = mkdir_parents_label(slink_tmp, 0755);
+ if (err != 0 && err != -ENOENT)
+ break;
+ label_context_set(slink_tmp, S_IFLNK);
+ err = symlink(target, slink_tmp);
+ if (err != 0)
+ err = -errno;
+ label_context_clear();
+ } while (err == -ENOENT);
+ if (err != 0) {
+ log_error("symlink '%s' '%s' failed: %m\n", target, slink_tmp);
+ goto exit;
+ }
+ err = rename(slink_tmp, slink);
+ if (err != 0) {
+ log_error("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;
+
+ log_debug("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_device_id(udev, dent->d_name);
+ if (dev_db != NULL) {
+ const char *devnode;
+
+ devnode = udev_device_get_devnode(dev_db);
+ if (devnode != NULL) {
+ if (target == NULL || udev_device_get_devlink_priority(dev_db) > priority) {
+ log_debug("'%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];
+
+ util_path_encode(slink + strlen("/dev"), name_enc, sizeof(name_enc));
+ util_strscpyl(dirname, sizeof(dirname), "/run/udev/links/", name_enc, NULL);
+ util_strscpyl(filename, sizeof(filename), dirname, "/", udev_device_get_id_filename(dev), NULL);
+
+ if (!add && unlink(filename) == 0)
+ rmdir(dirname);
+
+ target = link_find_prioritized(dev, add, dirname, buf, sizeof(buf));
+ if (target == NULL) {
+ log_debug("no reference left, remove '%s'\n", slink);
+ if (unlink(slink) == 0)
+ util_delete_path(udev, slink);
+ } else {
+ log_debug("creating link '%s' to '%s'\n", slink, target);
+ node_symlink(udev, target, slink);
+ }
+
+ if (add) {
+ int err;
+
+ do {
+ int fd;
+
+ err = mkdir_parents(filename, 0755);
+ 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_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;
+
+ log_debug("update old name, '%s' no longer belonging to '%s'\n",
+ name, udev_device_get_devpath(dev));
+ link_update(dev, name, false);
+ }
+}
+
+static int node_fixup(struct udev_device *dev, mode_t mode, uid_t uid, gid_t gid)
+{
+ const char *devnode = udev_device_get_devnode(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 (lstat(devnode, &stats) != 0) {
+ err = -errno;
+ log_debug("can not stat() node '%s' (%m)\n", devnode);
+ goto out;
+ }
+
+ if (((stats.st_mode & S_IFMT) != (mode & S_IFMT)) || (stats.st_rdev != devnum)) {
+ err = -EEXIST;
+ log_debug("found node '%s' with non-matching devnum %s, skip handling\n",
+ udev_device_get_devnode(dev), udev_device_get_id_filename(dev));
+ goto out;
+ }
+
+ if ((stats.st_mode & 0777) != (mode & 0777) || stats.st_uid != uid || stats.st_gid != gid) {
+ log_debug("set permissions %s, %#o, uid=%u, gid=%u\n", devnode, mode, uid, gid);
+ chmod(devnode, mode);
+ chown(devnode, uid, gid);
+ } else {
+ log_debug("preserve permissions %s, %#o, uid=%u, gid=%u\n", devnode, 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)
+ label_fix(devnode, true, false);
+
+ /* always update timestamp when we re-use the node, like on media change events */
+ utimensat(AT_FDCWD, devnode, NULL, 0);
+out:
+ return err;
+}
+
+void 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;
+
+ log_debug("handling device node '%s', devnum=%s, mode=%#o, uid=%d, gid=%d\n",
+ udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid);
+
+ if (node_fixup(dev, mode, uid, gid) < 0)
+ return;
+
+ /* always add /dev/{block,char}/$major:$minor */
+ snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
+ 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))
+ link_update(dev, udev_list_entry_get_name(list_entry), true);
+}
+
+void udev_node_remove(struct udev_device *dev)
+{
+ struct udev_list_entry *list_entry;
+ char filename[UTIL_PATH_SIZE];
+
+ /* 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), false);
+
+ /* remove /dev/{block,char}/$major:$minor */
+ snprintf(filename, sizeof(filename), "/dev/%s/%u:%u",
+ strcmp(udev_device_get_subsystem(dev), "block") == 0 ? "block" : "char",
+ major(udev_device_get_devnum(dev)), minor(udev_device_get_devnum(dev)));
+ unlink(filename);
+}