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>
11 #include <linux/nospec.h>
16 * This module implements an interface for routing autofs ioctl control
17 * commands via a miscellaneous device file.
19 * The alternate interface is needed because we need to be able open
20 * an ioctl file descriptor on an autofs mount that may be covered by
21 * another mount. This situation arises when starting automount(8)
22 * or other user space daemon which uses direct mounts or offset
23 * mounts (used for autofs lazy mount/umount of nested mount trees),
24 * which have been left busy at service shutdown.
27 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
28 struct autofs_dev_ioctl *);
30 static int check_name(const char *name)
32 if (!strchr(name, '/'))
38 * Check a string doesn't overrun the chunk of
39 * memory we copied from user land.
41 static int invalid_str(char *str, size_t size)
43 if (memchr(str, 0, size))
49 * Check that the user compiled against correct version of autofs
52 * As well as checking the version compatibility this always copies
53 * the kernel interface version out.
55 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
59 if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
60 (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
61 pr_warn("ioctl control interface version mismatch: "
62 "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
63 AUTOFS_DEV_IOCTL_VERSION_MAJOR,
64 AUTOFS_DEV_IOCTL_VERSION_MINOR,
65 param->ver_major, param->ver_minor, cmd);
69 /* Fill in the kernel version. */
70 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
71 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
77 * Copy parameter control struct, including a possible path allocated
78 * at the end of the struct.
80 static struct autofs_dev_ioctl *
81 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
83 struct autofs_dev_ioctl tmp, *res;
85 if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
86 return ERR_PTR(-EFAULT);
88 if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
89 return ERR_PTR(-EINVAL);
91 if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
92 return ERR_PTR(-ENAMETOOLONG);
94 res = memdup_user(in, tmp.size);
101 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
107 * Check sanity of parameter control fields and if a path is present
108 * check that it is terminated and contains at least one "/".
110 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
114 err = check_dev_ioctl_version(cmd, param);
116 pr_warn("invalid device control module version "
117 "supplied for cmd(0x%08x)\n", cmd);
121 if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
122 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
125 "path string terminator missing for cmd(0x%08x)\n",
130 err = check_name(param->path);
132 pr_warn("invalid path supplied for cmd(0x%08x)\n",
137 unsigned int inr = _IOC_NR(cmd);
139 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
140 inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
141 inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
152 /* Return autofs dev ioctl version */
153 static int autofs_dev_ioctl_version(struct file *fp,
154 struct autofs_sb_info *sbi,
155 struct autofs_dev_ioctl *param)
157 /* This should have already been set. */
158 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
159 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
163 /* Return autofs module protocol version */
164 static int autofs_dev_ioctl_protover(struct file *fp,
165 struct autofs_sb_info *sbi,
166 struct autofs_dev_ioctl *param)
168 param->protover.version = sbi->version;
172 /* Return autofs module protocol sub version */
173 static int autofs_dev_ioctl_protosubver(struct file *fp,
174 struct autofs_sb_info *sbi,
175 struct autofs_dev_ioctl *param)
177 param->protosubver.sub_version = sbi->sub_version;
181 /* Find the topmost mount satisfying test() */
182 static int find_autofs_mount(const char *pathname,
184 int test(const struct path *path, void *data),
190 err = kern_path(pathname, LOOKUP_MOUNTPOINT, &path);
194 while (path.dentry == path.mnt->mnt_root) {
195 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
196 if (test(&path, data)) {
203 if (!follow_up(&path))
210 static int test_by_dev(const struct path *path, void *p)
212 return path->dentry->d_sb->s_dev == *(dev_t *)p;
215 static int test_by_type(const struct path *path, void *p)
217 struct autofs_info *ino = autofs_dentry_ino(path->dentry);
219 return ino && ino->sbi->type & *(unsigned *)p;
223 * Open a file descriptor on the autofs mount point corresponding
224 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
226 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
230 fd = get_unused_fd_flags(O_CLOEXEC);
231 if (likely(fd >= 0)) {
235 err = find_autofs_mount(name, &path, test_by_dev, &devid);
239 filp = dentry_open(&path, O_RDONLY, current_cred());
246 fd_install(fd, filp);
256 /* Open a file descriptor on an autofs mount point */
257 static int autofs_dev_ioctl_openmount(struct file *fp,
258 struct autofs_sb_info *sbi,
259 struct autofs_dev_ioctl *param)
265 /* param->path has been checked in validate_dev_ioctl() */
267 if (!param->openmount.devid)
273 devid = new_decode_dev(param->openmount.devid);
276 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
277 if (unlikely(fd < 0)) {
287 /* Close file descriptor allocated above (user can also use close(2)). */
288 static int autofs_dev_ioctl_closemount(struct file *fp,
289 struct autofs_sb_info *sbi,
290 struct autofs_dev_ioctl *param)
292 return ksys_close(param->ioctlfd);
296 * Send "ready" status for an existing wait (either a mount or an expire
299 static int autofs_dev_ioctl_ready(struct file *fp,
300 struct autofs_sb_info *sbi,
301 struct autofs_dev_ioctl *param)
305 token = (autofs_wqt_t) param->ready.token;
306 return autofs_wait_release(sbi, token, 0);
310 * Send "fail" status for an existing wait (either a mount or an expire
313 static int autofs_dev_ioctl_fail(struct file *fp,
314 struct autofs_sb_info *sbi,
315 struct autofs_dev_ioctl *param)
320 token = (autofs_wqt_t) param->fail.token;
321 status = param->fail.status < 0 ? param->fail.status : -ENOENT;
322 return autofs_wait_release(sbi, token, status);
326 * Set the pipe fd for kernel communication to the daemon.
328 * Normally this is set at mount using an option but if we
329 * are reconnecting to a busy mount then we need to use this
330 * to tell the autofs mount about the new kernel pipe fd. In
331 * order to protect mounts against incorrectly setting the
332 * pipefd we also require that the autofs mount be catatonic.
334 * This also sets the process group id used to identify the
335 * controlling process (eg. the owning automount(8) daemon).
337 static int autofs_dev_ioctl_setpipefd(struct file *fp,
338 struct autofs_sb_info *sbi,
339 struct autofs_dev_ioctl *param)
343 struct pid *new_pid = NULL;
345 if (param->setpipefd.pipefd == -1)
348 pipefd = param->setpipefd.pipefd;
350 mutex_lock(&sbi->wq_mutex);
351 if (!(sbi->flags & AUTOFS_SBI_CATATONIC)) {
352 mutex_unlock(&sbi->wq_mutex);
357 new_pid = get_task_pid(current, PIDTYPE_PGID);
359 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
360 pr_warn("not allowed to change PID namespace\n");
370 if (autofs_prepare_pipe(pipe) < 0) {
375 swap(sbi->oz_pgrp, new_pid);
376 sbi->pipefd = pipefd;
378 sbi->flags &= ~AUTOFS_SBI_CATATONIC;
382 mutex_unlock(&sbi->wq_mutex);
387 * Make the autofs mount point catatonic, no longer responsive to
388 * mount requests. Also closes the kernel pipe file descriptor.
390 static int autofs_dev_ioctl_catatonic(struct file *fp,
391 struct autofs_sb_info *sbi,
392 struct autofs_dev_ioctl *param)
394 autofs_catatonic_mode(sbi);
398 /* Set the autofs mount timeout */
399 static int autofs_dev_ioctl_timeout(struct file *fp,
400 struct autofs_sb_info *sbi,
401 struct autofs_dev_ioctl *param)
403 unsigned long timeout;
405 timeout = param->timeout.timeout;
406 param->timeout.timeout = sbi->exp_timeout / HZ;
407 sbi->exp_timeout = timeout * HZ;
412 * Return the uid and gid of the last request for the mount
414 * When reconstructing an autofs mount tree with active mounts
415 * we need to re-connect to mounts that may have used the original
416 * process uid and gid (or string variations of them) for mount
417 * lookups within the map entry.
419 static int autofs_dev_ioctl_requester(struct file *fp,
420 struct autofs_sb_info *sbi,
421 struct autofs_dev_ioctl *param)
423 struct autofs_info *ino;
428 /* param->path has been checked in validate_dev_ioctl() */
430 devid = sbi->sb->s_dev;
432 param->requester.uid = param->requester.gid = -1;
434 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
438 ino = autofs_dentry_ino(path.dentry);
441 autofs_expire_wait(&path, 0);
442 spin_lock(&sbi->fs_lock);
443 param->requester.uid =
444 from_kuid_munged(current_user_ns(), ino->uid);
445 param->requester.gid =
446 from_kgid_munged(current_user_ns(), ino->gid);
447 spin_unlock(&sbi->fs_lock);
455 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
456 * more that can be done.
458 static int autofs_dev_ioctl_expire(struct file *fp,
459 struct autofs_sb_info *sbi,
460 struct autofs_dev_ioctl *param)
462 struct vfsmount *mnt;
465 how = param->expire.how;
466 mnt = fp->f_path.mnt;
468 return autofs_do_expire_multi(sbi->sb, mnt, sbi, how);
471 /* Check if autofs mount point is in use */
472 static int autofs_dev_ioctl_askumount(struct file *fp,
473 struct autofs_sb_info *sbi,
474 struct autofs_dev_ioctl *param)
476 param->askumount.may_umount = 0;
477 if (may_umount(fp->f_path.mnt))
478 param->askumount.may_umount = 1;
483 * Check if the given path is a mountpoint.
485 * If we are supplied with the file descriptor of an autofs
486 * mount we're looking for a specific mount. In this case
487 * the path is considered a mountpoint if it is itself a
488 * mountpoint or contains a mount, such as a multi-mount
489 * without a root mount. In this case we return 1 if the
490 * path is a mount point and the super magic of the covering
491 * mount if there is one or 0 if it isn't a mountpoint.
493 * If we aren't supplied with a file descriptor then we
494 * lookup the path and check if it is the root of a mount.
495 * If a type is given we are looking for a particular autofs
496 * mount and if we don't find a match we return fail. If the
497 * located path is the root of a mount we return 1 along with
498 * the super magic of the mount or 0 otherwise.
500 * In both cases the device number (as returned by
501 * new_encode_dev()) is also returned.
503 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
504 struct autofs_sb_info *sbi,
505 struct autofs_dev_ioctl *param)
510 unsigned int devid, magic;
513 /* param->path has been checked in validate_dev_ioctl() */
516 type = param->ismountpoint.in.type;
518 param->ismountpoint.out.devid = devid = 0;
519 param->ismountpoint.out.magic = magic = 0;
521 if (!fp || param->ioctlfd == -1) {
522 if (autofs_type_any(type))
523 err = kern_path(name, LOOKUP_FOLLOW | LOOKUP_MOUNTPOINT,
526 err = find_autofs_mount(name, &path,
527 test_by_type, &type);
530 devid = new_encode_dev(path.dentry->d_sb->s_dev);
532 if (path.mnt->mnt_root == path.dentry) {
534 magic = path.dentry->d_sb->s_magic;
537 dev_t dev = sbi->sb->s_dev;
539 err = find_autofs_mount(name, &path, test_by_dev, &dev);
543 devid = new_encode_dev(dev);
545 err = path_has_submounts(&path);
547 if (follow_down_one(&path))
548 magic = path.dentry->d_sb->s_magic;
551 param->ismountpoint.out.devid = devid;
552 param->ismountpoint.out.magic = magic;
559 * Our range of ioctl numbers isn't 0 based so we need to shift
560 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
563 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
565 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
567 static const ioctl_fn _ioctls[] = {
568 autofs_dev_ioctl_version,
569 autofs_dev_ioctl_protover,
570 autofs_dev_ioctl_protosubver,
571 autofs_dev_ioctl_openmount,
572 autofs_dev_ioctl_closemount,
573 autofs_dev_ioctl_ready,
574 autofs_dev_ioctl_fail,
575 autofs_dev_ioctl_setpipefd,
576 autofs_dev_ioctl_catatonic,
577 autofs_dev_ioctl_timeout,
578 autofs_dev_ioctl_requester,
579 autofs_dev_ioctl_expire,
580 autofs_dev_ioctl_askumount,
581 autofs_dev_ioctl_ismountpoint,
583 unsigned int idx = cmd_idx(cmd);
585 if (idx >= ARRAY_SIZE(_ioctls))
587 idx = array_index_nospec(idx, ARRAY_SIZE(_ioctls));
591 /* ioctl dispatcher */
592 static int _autofs_dev_ioctl(unsigned int command,
593 struct autofs_dev_ioctl __user *user)
595 struct autofs_dev_ioctl *param;
597 struct autofs_sb_info *sbi;
598 unsigned int cmd_first, cmd;
602 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
603 cmd = _IOC_NR(command);
605 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
606 cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
610 /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
611 * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
613 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
614 cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
615 !capable(CAP_SYS_ADMIN))
618 /* Copy the parameters into kernel space. */
619 param = copy_dev_ioctl(user);
621 return PTR_ERR(param);
623 err = validate_dev_ioctl(command, param);
627 fn = lookup_dev_ioctl(cmd);
629 pr_warn("unknown command 0x%08x\n", command);
638 * For obvious reasons the openmount can't have a file
639 * descriptor yet. We don't take a reference to the
640 * file during close to allow for immediate release,
641 * and the same for retrieving ioctl version.
643 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
644 cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
645 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
646 struct super_block *sb;
648 fp = fget(param->ioctlfd);
650 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
656 sb = file_inode(fp)->i_sb;
657 if (sb->s_type != &autofs_fs_type) {
662 sbi = autofs_sbi(sb);
665 * Admin needs to be able to set the mount catatonic in
666 * order to be able to perform the re-open.
668 if (!autofs_oz_mode(sbi) &&
669 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
676 err = fn(fp, sbi, param);
680 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
683 free_dev_ioctl(param);
687 static long autofs_dev_ioctl(struct file *file, unsigned int command,
692 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
697 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
700 return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
703 #define autofs_dev_ioctl_compat NULL
706 static const struct file_operations _dev_ioctl_fops = {
707 .unlocked_ioctl = autofs_dev_ioctl,
708 .compat_ioctl = autofs_dev_ioctl_compat,
709 .owner = THIS_MODULE,
710 .llseek = noop_llseek,
713 static struct miscdevice _autofs_dev_ioctl_misc = {
714 .minor = AUTOFS_MINOR,
715 .name = AUTOFS_DEVICE_NAME,
716 .fops = &_dev_ioctl_fops,
720 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
721 MODULE_ALIAS("devname:autofs");
723 /* Register/deregister misc character device */
724 int __init autofs_dev_ioctl_init(void)
728 r = misc_register(&_autofs_dev_ioctl_misc);
730 pr_err("misc_register failed for control device\n");
737 void autofs_dev_ioctl_exit(void)
739 misc_deregister(&_autofs_dev_ioctl_misc);