| /* SPDX-License-Identifier: GPL-2.0+ */ |
| /* |
| * |
| */ |
| |
| #include <errno.h> |
| #include <fcntl.h> |
| #include <stdbool.h> |
| #include <stddef.h> |
| #include <stdio.h> |
| #include <string.h> |
| #include <sys/stat.h> |
| #include <unistd.h> |
| |
| #include "device-nodes.h" |
| #include "dirent-util.h" |
| #include "format-util.h" |
| #include "fs-util.h" |
| #include "selinux-util.h" |
| #include "smack-util.h" |
| #include "stdio-util.h" |
| #include "string-util.h" |
| #include "udev.h" |
| |
| static int node_symlink(struct udev_device *dev, 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 + 32]; |
| 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 = strpcpy(&s, l, "../"); |
| i++; |
| } |
| l = 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", 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 (streq(target, buf)) { |
| log_debug("preserve already existing symlink '%s' to '%s'", slink, target); |
| (void) label_fix(slink, LABEL_IGNORE_ENOENT); |
| utimensat(AT_FDCWD, slink, NULL, AT_SYMLINK_NOFOLLOW); |
| goto exit; |
| } |
| } |
| } |
| } else { |
| log_debug("creating symlink '%s' to '%s'", slink, target); |
| do { |
| err = mkdir_parents_label(slink, 0755); |
| if (!IN_SET(err, 0, -ENOENT)) |
| break; |
| mac_selinux_create_file_prepare(slink, S_IFLNK); |
| err = symlink(target, slink); |
| if (err != 0) |
| err = -errno; |
| mac_selinux_create_file_clear(); |
| } while (err == -ENOENT); |
| if (err == 0) |
| goto exit; |
| } |
| |
| log_debug("atomically replace '%s'", slink); |
| strscpyl(slink_tmp, sizeof(slink_tmp), slink, ".tmp-", udev_device_get_id_filename(dev), NULL); |
| unlink(slink_tmp); |
| do { |
| err = mkdir_parents_label(slink_tmp, 0755); |
| if (!IN_SET(err, 0, -ENOENT)) |
| break; |
| mac_selinux_create_file_prepare(slink_tmp, S_IFLNK); |
| err = symlink(target, slink_tmp); |
| if (err != 0) |
| err = -errno; |
| mac_selinux_create_file_clear(); |
| } while (err == -ENOENT); |
| if (err != 0) { |
| log_error_errno(errno, "symlink '%s' '%s' failed: %m", target, slink_tmp); |
| goto exit; |
| } |
| err = rename(slink_tmp, slink); |
| if (err != 0) { |
| log_error_errno(errno, "rename '%s' '%s' failed: %m", 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; |
| struct dirent *dent; |
| int priority = 0; |
| const char *target = NULL; |
| |
| if (add) { |
| priority = udev_device_get_devlink_priority(dev); |
| strscpy(buf, bufsize, udev_device_get_devnode(dev)); |
| target = buf; |
| } |
| |
| dir = opendir(stackdir); |
| if (dir == NULL) |
| return target; |
| FOREACH_DIRENT_ALL(dent, dir, break) { |
| struct udev_device *dev_db; |
| |
| if (dent->d_name[0] == '\0') |
| break; |
| if (dent->d_name[0] == '.') |
| continue; |
| |
| log_debug("found '%s' claiming '%s'", dent->d_name, stackdir); |
| |
| /* did we find ourself? */ |
| if (streq(dent->d_name, udev_device_get_id_filename(dev))) |
| 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'", |
| udev_device_get_syspath(dev_db), udev_device_get_devlink_priority(dev_db), stackdir); |
| priority = udev_device_get_devlink_priority(dev_db); |
| 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) { |
| 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)); |
| strscpyl(dirname, sizeof(dirname), "/run/udev/links/", name_enc, NULL); |
| 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'", slink); |
| if (unlink(slink) == 0) |
| rmdir_parents(slink, "/"); |
| } else { |
| log_debug("creating link '%s' to '%s'", slink, target); |
| node_symlink(dev, target, slink); |
| } |
| |
| if (add) { |
| int err; |
| |
| do { |
| int fd; |
| |
| err = mkdir_parents(filename, 0755); |
| if (!IN_SET(err, 0, -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 (streq(name, name_current)) { |
| found = 1; |
| break; |
| } |
| } |
| if (found) |
| continue; |
| |
| log_debug("update old name, '%s' no longer belonging to '%s'", |
| name, udev_device_get_devpath(dev)); |
| link_update(dev, name, false); |
| } |
| } |
| |
| static int node_permissions_apply(struct udev_device *dev, bool apply, |
| mode_t mode, uid_t uid, gid_t gid, |
| struct udev_list *seclabel_list) { |
| const char *devnode = udev_device_get_devnode(dev); |
| dev_t devnum = udev_device_get_devnum(dev); |
| struct stat stats; |
| struct udev_list_entry *entry; |
| int err = 0; |
| |
| if (streq(udev_device_get_subsystem(dev), "block")) |
| mode |= S_IFBLK; |
| else |
| mode |= S_IFCHR; |
| |
| if (lstat(devnode, &stats) != 0) { |
| err = log_debug_errno(errno, "cannot stat() node '%s' (%m)", 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", |
| udev_device_get_devnode(dev), udev_device_get_id_filename(dev)); |
| goto out; |
| } |
| |
| if (apply) { |
| bool selinux = false; |
| bool smack = false; |
| |
| 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", devnode, mode, uid, gid); |
| err = chmod(devnode, mode); |
| if (err < 0) |
| log_warning_errno(errno, "setting mode of %s to %#o failed: %m", devnode, mode); |
| err = chown(devnode, uid, gid); |
| if (err < 0) |
| log_warning_errno(errno, "setting owner of %s to uid=%u, gid=%u failed: %m", devnode, uid, gid); |
| } else { |
| log_debug("preserve permissions %s, %#o, uid=%u, gid=%u", devnode, mode, uid, gid); |
| } |
| |
| /* apply SECLABEL{$module}=$label */ |
| udev_list_entry_foreach(entry, udev_list_get_entry(seclabel_list)) { |
| const char *name, *label; |
| int r; |
| |
| name = udev_list_entry_get_name(entry); |
| label = udev_list_entry_get_value(entry); |
| |
| if (streq(name, "selinux")) { |
| selinux = true; |
| |
| r = mac_selinux_apply(devnode, label); |
| if (r < 0) |
| log_error_errno(r, "SECLABEL: failed to set SELinux label '%s': %m", label); |
| else |
| log_debug("SECLABEL: set SELinux label '%s'", label); |
| |
| } else if (streq(name, "smack")) { |
| smack = true; |
| |
| r = mac_smack_apply(devnode, SMACK_ATTR_ACCESS, label); |
| if (r < 0) |
| log_error_errno(r, "SECLABEL: failed to set SMACK label '%s': %m", label); |
| else |
| log_debug("SECLABEL: set SMACK label '%s'", label); |
| |
| } else |
| log_error("SECLABEL: unknown subsystem, ignoring '%s'='%s'", name, label); |
| } |
| |
| /* set the defaults */ |
| if (!selinux) |
| (void) mac_selinux_fix(devnode, LABEL_IGNORE_ENOENT); |
| if (!smack) |
| mac_smack_apply(devnode, SMACK_ATTR_ACCESS, NULL); |
| } |
| |
| /* 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, bool apply, |
| mode_t mode, uid_t uid, gid_t gid, |
| struct udev_list *seclabel_list) { |
| char filename[DEV_NUM_PATH_MAX]; |
| struct udev_list_entry *list_entry; |
| |
| log_debug("handling device node '%s', devnum=%s, mode=%#o, uid="UID_FMT", gid="GID_FMT, |
| udev_device_get_devnode(dev), udev_device_get_id_filename(dev), mode, uid, gid); |
| |
| if (node_permissions_apply(dev, apply, mode, uid, gid, seclabel_list) < 0) |
| return; |
| |
| /* always add /dev/{block,char}/$major:$minor */ |
| xsprintf_dev_num_path(filename, |
| streq(udev_device_get_subsystem(dev), "block") ? "block" : "char", |
| udev_device_get_devnum(dev)); |
| node_symlink(dev, 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[DEV_NUM_PATH_MAX]; |
| |
| /* 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 */ |
| xsprintf_dev_num_path(filename, |
| streq(udev_device_get_subsystem(dev), "block") ? "block" : "char", |
| udev_device_get_devnum(dev)); |
| unlink(filename); |
| } |