1 // SPDX-License-Identifier: GPL-2.0-or-later
3 * Copyright 2008 Red Hat, Inc. All rights reserved.
4 * Copyright 2008 Ian Kent <raven@themaw.net>
7 #include <linux/miscdevice.h>
8 #include <linux/compat.h>
9 #include <linux/syscalls.h>
10 #include <linux/magic.h>
15 * This module implements an interface for routing autofs ioctl control
16 * commands via a miscellaneous device file.
18 * The alternate interface is needed because we need to be able open
19 * an ioctl file descriptor on an autofs mount that may be covered by
20 * another mount. This situation arises when starting automount(8)
21 * or other user space daemon which uses direct mounts or offset
22 * mounts (used for autofs lazy mount/umount of nested mount trees),
23 * which have been left busy at service shutdown.
26 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
27 struct autofs_dev_ioctl *);
29 static int check_name(const char *name)
31 if (!strchr(name, '/'))
37 * Check a string doesn't overrun the chunk of
38 * memory we copied from user land.
40 static int invalid_str(char *str, size_t size)
42 if (memchr(str, 0, size))
48 * Check that the user compiled against correct version of autofs
51 * As well as checking the version compatibility this always copies
52 * the kernel interface version out.
54 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
58 if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
59 (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
60 pr_warn("ioctl control interface version mismatch: "
61 "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
62 AUTOFS_DEV_IOCTL_VERSION_MAJOR,
63 AUTOFS_DEV_IOCTL_VERSION_MINOR,
64 param->ver_major, param->ver_minor, cmd);
68 /* Fill in the kernel version. */
69 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
70 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
76 * Copy parameter control struct, including a possible path allocated
77 * at the end of the struct.
79 static struct autofs_dev_ioctl *
80 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
82 struct autofs_dev_ioctl tmp, *res;
84 if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
85 return ERR_PTR(-EFAULT);
87 if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
88 return ERR_PTR(-EINVAL);
90 if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
91 return ERR_PTR(-ENAMETOOLONG);
93 res = memdup_user(in, tmp.size);
100 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
106 * Check sanity of parameter control fields and if a path is present
107 * check that it is terminated and contains at least one "/".
109 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
113 err = check_dev_ioctl_version(cmd, param);
115 pr_warn("invalid device control module version "
116 "supplied for cmd(0x%08x)\n", cmd);
120 if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
121 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
124 "path string terminator missing for cmd(0x%08x)\n",
129 err = check_name(param->path);
131 pr_warn("invalid path supplied for cmd(0x%08x)\n",
136 unsigned int inr = _IOC_NR(cmd);
138 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
139 inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
140 inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
151 /* Return autofs dev ioctl version */
152 static int autofs_dev_ioctl_version(struct file *fp,
153 struct autofs_sb_info *sbi,
154 struct autofs_dev_ioctl *param)
156 /* This should have already been set. */
157 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
158 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
162 /* Return autofs module protocol version */
163 static int autofs_dev_ioctl_protover(struct file *fp,
164 struct autofs_sb_info *sbi,
165 struct autofs_dev_ioctl *param)
167 param->protover.version = sbi->version;
171 /* Return autofs module protocol sub version */
172 static int autofs_dev_ioctl_protosubver(struct file *fp,
173 struct autofs_sb_info *sbi,
174 struct autofs_dev_ioctl *param)
176 param->protosubver.sub_version = sbi->sub_version;
180 /* Find the topmost mount satisfying test() */
181 static int find_autofs_mount(const char *pathname,
183 int test(const struct path *path, void *data),
189 err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
193 while (path.dentry == path.mnt->mnt_root) {
194 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
195 if (test(&path, data)) {
202 if (!follow_up(&path))
209 static int test_by_dev(const struct path *path, void *p)
211 return path->dentry->d_sb->s_dev == *(dev_t *)p;
214 static int test_by_type(const struct path *path, void *p)
216 struct autofs_info *ino = autofs_dentry_ino(path->dentry);
218 return ino && ino->sbi->type & *(unsigned *)p;
222 * Open a file descriptor on the autofs mount point corresponding
223 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
225 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
229 fd = get_unused_fd_flags(O_CLOEXEC);
230 if (likely(fd >= 0)) {
234 err = find_autofs_mount(name, &path, test_by_dev, &devid);
238 filp = dentry_open(&path, O_RDONLY, current_cred());
245 fd_install(fd, filp);
255 /* Open a file descriptor on an autofs mount point */
256 static int autofs_dev_ioctl_openmount(struct file *fp,
257 struct autofs_sb_info *sbi,
258 struct autofs_dev_ioctl *param)
264 /* param->path has been checked in validate_dev_ioctl() */
266 if (!param->openmount.devid)
272 devid = new_decode_dev(param->openmount.devid);
275 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
276 if (unlikely(fd < 0)) {
286 /* Close file descriptor allocated above (user can also use close(2)). */
287 static int autofs_dev_ioctl_closemount(struct file *fp,
288 struct autofs_sb_info *sbi,
289 struct autofs_dev_ioctl *param)
291 return ksys_close(param->ioctlfd);
295 * Send "ready" status for an existing wait (either a mount or an expire
298 static int autofs_dev_ioctl_ready(struct file *fp,
299 struct autofs_sb_info *sbi,
300 struct autofs_dev_ioctl *param)
304 token = (autofs_wqt_t) param->ready.token;
305 return autofs_wait_release(sbi, token, 0);
309 * Send "fail" status for an existing wait (either a mount or an expire
312 static int autofs_dev_ioctl_fail(struct file *fp,
313 struct autofs_sb_info *sbi,
314 struct autofs_dev_ioctl *param)
319 token = (autofs_wqt_t) param->fail.token;
320 status = param->fail.status < 0 ? param->fail.status : -ENOENT;
321 return autofs_wait_release(sbi, token, status);
325 * Set the pipe fd for kernel communication to the daemon.
327 * Normally this is set at mount using an option but if we
328 * are reconnecting to a busy mount then we need to use this
329 * to tell the autofs mount about the new kernel pipe fd. In
330 * order to protect mounts against incorrectly setting the
331 * pipefd we also require that the autofs mount be catatonic.
333 * This also sets the process group id used to identify the
334 * controlling process (eg. the owning automount(8) daemon).
336 static int autofs_dev_ioctl_setpipefd(struct file *fp,
337 struct autofs_sb_info *sbi,
338 struct autofs_dev_ioctl *param)
342 struct pid *new_pid = NULL;
344 if (param->setpipefd.pipefd == -1)
347 pipefd = param->setpipefd.pipefd;
349 mutex_lock(&sbi->wq_mutex);
350 if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
351 mutex_unlock(&sbi->wq_mutex);
356 new_pid = get_task_pid(current, PIDTYPE_PGID);
358 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
359 pr_warn("not allowed to change PID namespace\n");
369 if (autofs_prepare_pipe(pipe) < 0) {
374 swap(sbi->oz_pgrp, new_pid);
375 sbi->pipefd = pipefd;
377 sbi->flags &= ~AUTOFS_SBI_CATATONIC;
381 mutex_unlock(&sbi->wq_mutex);
386 * Make the autofs mount point catatonic, no longer responsive to
387 * mount requests. Also closes the kernel pipe file descriptor.
389 static int autofs_dev_ioctl_catatonic(struct file *fp,
390 struct autofs_sb_info *sbi,
391 struct autofs_dev_ioctl *param)
393 autofs_catatonic_mode(sbi);
397 /* Set the autofs mount timeout */
398 static int autofs_dev_ioctl_timeout(struct file *fp,
399 struct autofs_sb_info *sbi,
400 struct autofs_dev_ioctl *param)
402 unsigned long timeout;
404 timeout = param->timeout.timeout;
405 param->timeout.timeout = sbi->exp_timeout / HZ;
406 sbi->exp_timeout = timeout * HZ;
411 * Return the uid and gid of the last request for the mount
413 * When reconstructing an autofs mount tree with active mounts
414 * we need to re-connect to mounts that may have used the original
415 * process uid and gid (or string variations of them) for mount
416 * lookups within the map entry.
418 static int autofs_dev_ioctl_requester(struct file *fp,
419 struct autofs_sb_info *sbi,
420 struct autofs_dev_ioctl *param)
422 struct autofs_info *ino;
427 /* param->path has been checked in validate_dev_ioctl() */
429 devid = sbi->sb->s_dev;
431 param->requester.uid = param->requester.gid = -1;
433 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
437 ino = autofs_dentry_ino(path.dentry);
440 autofs_expire_wait(&path, 0);
441 spin_lock(&sbi->fs_lock);
442 param->requester.uid =
443 from_kuid_munged(current_user_ns(), ino->uid);
444 param->requester.gid =
445 from_kgid_munged(current_user_ns(), ino->gid);
446 spin_unlock(&sbi->fs_lock);
454 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
455 * more that can be done.
457 static int autofs_dev_ioctl_expire(struct file *fp,
458 struct autofs_sb_info *sbi,
459 struct autofs_dev_ioctl *param)
461 struct vfsmount *mnt;
464 how = param->expire.how;
465 mnt = fp->f_path.mnt;
467 return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
470 /* Check if autofs mount point is in use */
471 static int autofs_dev_ioctl_askumount(struct file *fp,
472 struct autofs_sb_info *sbi,
473 struct autofs_dev_ioctl *param)
475 param->askumount.may_umount = 0;
476 if (may_umount(fp->f_path.mnt))
477 param->askumount.may_umount = 1;
482 * Check if the given path is a mountpoint.
484 * If we are supplied with the file descriptor of an autofs
485 * mount we're looking for a specific mount. In this case
486 * the path is considered a mountpoint if it is itself a
487 * mountpoint or contains a mount, such as a multi-mount
488 * without a root mount. In this case we return 1 if the
489 * path is a mount point and the super magic of the covering
490 * mount if there is one or 0 if it isn't a mountpoint.
492 * If we aren't supplied with a file descriptor then we
493 * lookup the path and check if it is the root of a mount.
494 * If a type is given we are looking for a particular autofs
495 * mount and if we don't find a match we return fail. If the
496 * located path is the root of a mount we return 1 along with
497 * the super magic of the mount or 0 otherwise.
499 * In both cases the device number (as returned by
500 * new_encode_dev()) is also returned.
502 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
503 struct autofs_sb_info *sbi,
504 struct autofs_dev_ioctl *param)
509 unsigned int devid, magic;
512 /* param->path has been checked in validate_dev_ioctl() */
515 type = param->ismountpoint.in.type;
517 param->ismountpoint.out.devid = devid = 0;
518 param->ismountpoint.out.magic = magic = 0;
520 if (!fp || param->ioctlfd == -1) {
521 if (autofs_type_any(type))
522 err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
525 err = find_autofs_mount(name, &path,
526 test_by_type, &type);
529 devid = new_encode_dev(path.dentry->d_sb->s_dev);
531 if (path.mnt->mnt_root == path.dentry) {
533 magic = path.dentry->d_sb->s_magic;
536 dev_t dev = sbi->sb->s_dev;
538 err = find_autofs_mount(name, &path, test_by_dev, &dev);
542 devid = new_encode_dev(dev);
544 err = path_has_submounts(&path);
546 if (follow_down_one(&path))
547 magic = path.dentry->d_sb->s_magic;
550 param->ismountpoint.out.devid = devid;
551 param->ismountpoint.out.magic = magic;
558 * Our range of ioctl numbers isn't 0 based so we need to shift
559 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
562 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
564 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
566 static ioctl_fn _ioctls[] = {
567 autofs_dev_ioctl_version,
568 autofs_dev_ioctl_protover,
569 autofs_dev_ioctl_protosubver,
570 autofs_dev_ioctl_openmount,
571 autofs_dev_ioctl_closemount,
572 autofs_dev_ioctl_ready,
573 autofs_dev_ioctl_fail,
574 autofs_dev_ioctl_setpipefd,
575 autofs_dev_ioctl_catatonic,
576 autofs_dev_ioctl_timeout,
577 autofs_dev_ioctl_requester,
578 autofs_dev_ioctl_expire,
579 autofs_dev_ioctl_askumount,
580 autofs_dev_ioctl_ismountpoint,
582 unsigned int idx = cmd_idx(cmd);
584 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
587 /* ioctl dispatcher */
588 static int _autofs_dev_ioctl(unsigned int command,
589 struct autofs_dev_ioctl __user *user)
591 struct autofs_dev_ioctl *param;
593 struct autofs_sb_info *sbi;
594 unsigned int cmd_first, cmd;
598 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
599 cmd = _IOC_NR(command);
601 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
602 cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
606 /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
607 * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
609 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
610 cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
611 !capable(CAP_SYS_ADMIN))
614 /* Copy the parameters into kernel space. */
615 param = copy_dev_ioctl(user);
617 return PTR_ERR(param);
619 err = validate_dev_ioctl(command, param);
623 fn = lookup_dev_ioctl(cmd);
625 pr_warn("unknown command 0x%08x\n", command);
634 * For obvious reasons the openmount can't have a file
635 * descriptor yet. We don't take a reference to the
636 * file during close to allow for immediate release,
637 * and the same for retrieving ioctl version.
639 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
640 cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
641 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
642 struct super_block *sb;
644 fp = fget(param->ioctlfd);
646 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
652 sb = file_inode(fp)->i_sb;
653 if (sb->s_type != &autofs_fs_type) {
658 sbi = autofs_sbi(sb);
661 * Admin needs to be able to set the mount catatonic in
662 * order to be able to perform the re-open.
664 if (!autofs_oz_mode(sbi) &&
665 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
672 err = fn(fp, sbi, param);
676 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
679 free_dev_ioctl(param);
683 static long autofs_dev_ioctl(struct file *file, unsigned int command,
688 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
693 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
696 return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
699 #define autofs_dev_ioctl_compat NULL
702 static const struct file_operations _dev_ioctl_fops = {
703 .unlocked_ioctl = autofs_dev_ioctl,
704 .compat_ioctl = autofs_dev_ioctl_compat,
705 .owner = THIS_MODULE,
706 .llseek = noop_llseek,
709 static struct miscdevice _autofs_dev_ioctl_misc = {
710 .minor = AUTOFS_MINOR,
711 .name = AUTOFS_DEVICE_NAME,
712 .fops = &_dev_ioctl_fops,
716 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
717 MODULE_ALIAS("devname:autofs");
719 /* Register/deregister misc character device */
720 int __init autofs_dev_ioctl_init(void)
724 r = misc_register(&_autofs_dev_ioctl_misc);
726 pr_err("misc_register failed for control device\n");
733 void autofs_dev_ioctl_exit(void)
735 misc_deregister(&_autofs_dev_ioctl_misc);