2 * Copyright 2008 Red Hat, Inc. All rights reserved.
3 * Copyright 2008 Ian Kent <raven@themaw.net>
5 * This file is part of the Linux kernel and is made available under
6 * the terms of the GNU General Public License, version 2, or at your
7 * option, any later version, incorporated herein by reference.
10 #include <linux/module.h>
11 #include <linux/vmalloc.h>
12 #include <linux/miscdevice.h>
13 #include <linux/init.h>
14 #include <linux/wait.h>
15 #include <linux/namei.h>
16 #include <linux/fcntl.h>
17 #include <linux/file.h>
18 #include <linux/fdtable.h>
19 #include <linux/sched.h>
20 #include <linux/cred.h>
21 #include <linux/compat.h>
22 #include <linux/syscalls.h>
23 #include <linux/magic.h>
24 #include <linux/dcache.h>
25 #include <linux/uaccess.h>
26 #include <linux/slab.h>
31 * This module implements an interface for routing autofs ioctl control
32 * commands via a miscellaneous device file.
34 * The alternate interface is needed because we need to be able open
35 * an ioctl file descriptor on an autofs mount that may be covered by
36 * another mount. This situation arises when starting automount(8)
37 * or other user space daemon which uses direct mounts or offset
38 * mounts (used for autofs lazy mount/umount of nested mount trees),
39 * which have been left busy at at service shutdown.
42 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
43 struct autofs_dev_ioctl *);
45 static int check_name(const char *name)
47 if (!strchr(name, '/'))
53 * Check a string doesn't overrun the chunk of
54 * memory we copied from user land.
56 static int invalid_str(char *str, size_t size)
58 if (memchr(str, 0, size))
64 * Check that the user compiled against correct version of autofs
67 * As well as checking the version compatibility this always copies
68 * the kernel interface version out.
70 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
74 if ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
75 (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
76 pr_warn("ioctl control interface version mismatch: "
77 "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
78 AUTOFS_DEV_IOCTL_VERSION_MAJOR,
79 AUTOFS_DEV_IOCTL_VERSION_MINOR,
80 param->ver_major, param->ver_minor, cmd);
84 /* Fill in the kernel version. */
85 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
86 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
92 * Copy parameter control struct, including a possible path allocated
93 * at the end of the struct.
95 static struct autofs_dev_ioctl *
96 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
98 struct autofs_dev_ioctl tmp, *res;
100 if (copy_from_user(&tmp, in, AUTOFS_DEV_IOCTL_SIZE))
101 return ERR_PTR(-EFAULT);
103 if (tmp.size < AUTOFS_DEV_IOCTL_SIZE)
104 return ERR_PTR(-EINVAL);
106 if (tmp.size > AUTOFS_DEV_IOCTL_SIZE + PATH_MAX)
107 return ERR_PTR(-ENAMETOOLONG);
109 res = memdup_user(in, tmp.size);
111 res->size = tmp.size;
116 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
122 * Check sanity of parameter control fields and if a path is present
123 * check that it is terminated and contains at least one "/".
125 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
129 err = check_dev_ioctl_version(cmd, param);
131 pr_warn("invalid device control module version "
132 "supplied for cmd(0x%08x)\n", cmd);
136 if (param->size > AUTOFS_DEV_IOCTL_SIZE) {
137 err = invalid_str(param->path, param->size - AUTOFS_DEV_IOCTL_SIZE);
140 "path string terminator missing for cmd(0x%08x)\n",
145 err = check_name(param->path);
147 pr_warn("invalid path supplied for cmd(0x%08x)\n",
152 unsigned int inr = _IOC_NR(cmd);
154 if (inr == AUTOFS_DEV_IOCTL_OPENMOUNT_CMD ||
155 inr == AUTOFS_DEV_IOCTL_REQUESTER_CMD ||
156 inr == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD) {
168 * Get the autofs super block info struct from the file opened on
169 * the autofs mount point.
171 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
173 struct autofs_sb_info *sbi = NULL;
177 inode = file_inode(f);
178 sbi = autofs4_sbi(inode->i_sb);
183 /* Return autofs dev ioctl version */
184 static int autofs_dev_ioctl_version(struct file *fp,
185 struct autofs_sb_info *sbi,
186 struct autofs_dev_ioctl *param)
188 /* This should have already been set. */
189 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
190 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
194 /* Return autofs module protocol version */
195 static int autofs_dev_ioctl_protover(struct file *fp,
196 struct autofs_sb_info *sbi,
197 struct autofs_dev_ioctl *param)
199 param->protover.version = sbi->version;
203 /* Return autofs module protocol sub version */
204 static int autofs_dev_ioctl_protosubver(struct file *fp,
205 struct autofs_sb_info *sbi,
206 struct autofs_dev_ioctl *param)
208 param->protosubver.sub_version = sbi->sub_version;
212 /* Find the topmost mount satisfying test() */
213 static int find_autofs_mount(const char *pathname,
215 int test(const struct path *path, void *data),
221 err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
225 while (path.dentry == path.mnt->mnt_root) {
226 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
227 if (test(&path, data)) {
234 if (!follow_up(&path))
241 static int test_by_dev(const struct path *path, void *p)
243 return path->dentry->d_sb->s_dev == *(dev_t *)p;
246 static int test_by_type(const struct path *path, void *p)
248 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
250 return ino && ino->sbi->type & *(unsigned *)p;
254 * Open a file descriptor on the autofs mount point corresponding
255 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
257 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
261 fd = get_unused_fd_flags(O_CLOEXEC);
262 if (likely(fd >= 0)) {
266 err = find_autofs_mount(name, &path, test_by_dev, &devid);
270 filp = dentry_open(&path, O_RDONLY, current_cred());
277 fd_install(fd, filp);
287 /* Open a file descriptor on an autofs mount point */
288 static int autofs_dev_ioctl_openmount(struct file *fp,
289 struct autofs_sb_info *sbi,
290 struct autofs_dev_ioctl *param)
296 /* param->path has been checked in validate_dev_ioctl() */
298 if (!param->openmount.devid)
304 devid = new_decode_dev(param->openmount.devid);
307 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
308 if (unlikely(fd < 0)) {
318 /* Close file descriptor allocated above (user can also use close(2)). */
319 static int autofs_dev_ioctl_closemount(struct file *fp,
320 struct autofs_sb_info *sbi,
321 struct autofs_dev_ioctl *param)
323 return sys_close(param->ioctlfd);
327 * Send "ready" status for an existing wait (either a mount or an expire
330 static int autofs_dev_ioctl_ready(struct file *fp,
331 struct autofs_sb_info *sbi,
332 struct autofs_dev_ioctl *param)
336 token = (autofs_wqt_t) param->ready.token;
337 return autofs4_wait_release(sbi, token, 0);
341 * Send "fail" status for an existing wait (either a mount or an expire
344 static int autofs_dev_ioctl_fail(struct file *fp,
345 struct autofs_sb_info *sbi,
346 struct autofs_dev_ioctl *param)
351 token = (autofs_wqt_t) param->fail.token;
352 status = param->fail.status < 0 ? param->fail.status : -ENOENT;
353 return autofs4_wait_release(sbi, token, status);
357 * Set the pipe fd for kernel communication to the daemon.
359 * Normally this is set at mount using an option but if we
360 * are reconnecting to a busy mount then we need to use this
361 * to tell the autofs mount about the new kernel pipe fd. In
362 * order to protect mounts against incorrectly setting the
363 * pipefd we also require that the autofs mount be catatonic.
365 * This also sets the process group id used to identify the
366 * controlling process (eg. the owning automount(8) daemon).
368 static int autofs_dev_ioctl_setpipefd(struct file *fp,
369 struct autofs_sb_info *sbi,
370 struct autofs_dev_ioctl *param)
374 struct pid *new_pid = NULL;
376 if (param->setpipefd.pipefd == -1)
379 pipefd = param->setpipefd.pipefd;
381 mutex_lock(&sbi->wq_mutex);
382 if (!sbi->catatonic) {
383 mutex_unlock(&sbi->wq_mutex);
388 new_pid = get_task_pid(current, PIDTYPE_PGID);
390 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
391 pr_warn("not allowed to change PID namespace\n");
401 if (autofs_prepare_pipe(pipe) < 0) {
406 swap(sbi->oz_pgrp, new_pid);
407 sbi->pipefd = pipefd;
413 mutex_unlock(&sbi->wq_mutex);
418 * Make the autofs mount point catatonic, no longer responsive to
419 * mount requests. Also closes the kernel pipe file descriptor.
421 static int autofs_dev_ioctl_catatonic(struct file *fp,
422 struct autofs_sb_info *sbi,
423 struct autofs_dev_ioctl *param)
425 autofs4_catatonic_mode(sbi);
429 /* Set the autofs mount timeout */
430 static int autofs_dev_ioctl_timeout(struct file *fp,
431 struct autofs_sb_info *sbi,
432 struct autofs_dev_ioctl *param)
434 unsigned long timeout;
436 timeout = param->timeout.timeout;
437 param->timeout.timeout = sbi->exp_timeout / HZ;
438 sbi->exp_timeout = timeout * HZ;
443 * Return the uid and gid of the last request for the mount
445 * When reconstructing an autofs mount tree with active mounts
446 * we need to re-connect to mounts that may have used the original
447 * process uid and gid (or string variations of them) for mount
448 * lookups within the map entry.
450 static int autofs_dev_ioctl_requester(struct file *fp,
451 struct autofs_sb_info *sbi,
452 struct autofs_dev_ioctl *param)
454 struct autofs_info *ino;
459 /* param->path has been checked in validate_dev_ioctl() */
461 devid = sbi->sb->s_dev;
463 param->requester.uid = param->requester.gid = -1;
465 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
469 ino = autofs4_dentry_ino(path.dentry);
472 autofs4_expire_wait(&path, 0);
473 spin_lock(&sbi->fs_lock);
474 param->requester.uid =
475 from_kuid_munged(current_user_ns(), ino->uid);
476 param->requester.gid =
477 from_kgid_munged(current_user_ns(), ino->gid);
478 spin_unlock(&sbi->fs_lock);
486 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
487 * more that can be done.
489 static int autofs_dev_ioctl_expire(struct file *fp,
490 struct autofs_sb_info *sbi,
491 struct autofs_dev_ioctl *param)
493 struct vfsmount *mnt;
496 how = param->expire.how;
497 mnt = fp->f_path.mnt;
499 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
502 /* Check if autofs mount point is in use */
503 static int autofs_dev_ioctl_askumount(struct file *fp,
504 struct autofs_sb_info *sbi,
505 struct autofs_dev_ioctl *param)
507 param->askumount.may_umount = 0;
508 if (may_umount(fp->f_path.mnt))
509 param->askumount.may_umount = 1;
514 * Check if the given path is a mountpoint.
516 * If we are supplied with the file descriptor of an autofs
517 * mount we're looking for a specific mount. In this case
518 * the path is considered a mountpoint if it is itself a
519 * mountpoint or contains a mount, such as a multi-mount
520 * without a root mount. In this case we return 1 if the
521 * path is a mount point and the super magic of the covering
522 * mount if there is one or 0 if it isn't a mountpoint.
524 * If we aren't supplied with a file descriptor then we
525 * lookup the path and check if it is the root of a mount.
526 * If a type is given we are looking for a particular autofs
527 * mount and if we don't find a match we return fail. If the
528 * located path is the root of a mount we return 1 along with
529 * the super magic of the mount or 0 otherwise.
531 * In both cases the the device number (as returned by
532 * new_encode_dev()) is also returned.
534 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
535 struct autofs_sb_info *sbi,
536 struct autofs_dev_ioctl *param)
541 unsigned int devid, magic;
544 /* param->path has been checked in validate_dev_ioctl() */
547 type = param->ismountpoint.in.type;
549 param->ismountpoint.out.devid = devid = 0;
550 param->ismountpoint.out.magic = magic = 0;
552 if (!fp || param->ioctlfd == -1) {
553 if (autofs_type_any(type))
554 err = kern_path_mountpoint(AT_FDCWD,
555 name, &path, LOOKUP_FOLLOW);
557 err = find_autofs_mount(name, &path,
558 test_by_type, &type);
561 devid = new_encode_dev(path.dentry->d_sb->s_dev);
563 if (path.mnt->mnt_root == path.dentry) {
565 magic = path.dentry->d_sb->s_magic;
568 dev_t dev = sbi->sb->s_dev;
570 err = find_autofs_mount(name, &path, test_by_dev, &dev);
574 devid = new_encode_dev(dev);
576 err = path_has_submounts(&path);
578 if (follow_down_one(&path))
579 magic = path.dentry->d_sb->s_magic;
582 param->ismountpoint.out.devid = devid;
583 param->ismountpoint.out.magic = magic;
590 * Our range of ioctl numbers isn't 0 based so we need to shift
591 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
594 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
596 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
598 static ioctl_fn _ioctls[] = {
599 autofs_dev_ioctl_version,
600 autofs_dev_ioctl_protover,
601 autofs_dev_ioctl_protosubver,
602 autofs_dev_ioctl_openmount,
603 autofs_dev_ioctl_closemount,
604 autofs_dev_ioctl_ready,
605 autofs_dev_ioctl_fail,
606 autofs_dev_ioctl_setpipefd,
607 autofs_dev_ioctl_catatonic,
608 autofs_dev_ioctl_timeout,
609 autofs_dev_ioctl_requester,
610 autofs_dev_ioctl_expire,
611 autofs_dev_ioctl_askumount,
612 autofs_dev_ioctl_ismountpoint,
614 unsigned int idx = cmd_idx(cmd);
616 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
619 /* ioctl dispatcher */
620 static int _autofs_dev_ioctl(unsigned int command,
621 struct autofs_dev_ioctl __user *user)
623 struct autofs_dev_ioctl *param;
625 struct autofs_sb_info *sbi;
626 unsigned int cmd_first, cmd;
630 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
631 cmd = _IOC_NR(command);
633 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
634 cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
638 /* Only root can use ioctls other than AUTOFS_DEV_IOCTL_VERSION_CMD
639 * and AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD
641 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
642 cmd != AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD &&
643 !capable(CAP_SYS_ADMIN))
646 /* Copy the parameters into kernel space. */
647 param = copy_dev_ioctl(user);
649 return PTR_ERR(param);
651 err = validate_dev_ioctl(command, param);
655 fn = lookup_dev_ioctl(cmd);
657 pr_warn("unknown command 0x%08x\n", command);
666 * For obvious reasons the openmount can't have a file
667 * descriptor yet. We don't take a reference to the
668 * file during close to allow for immediate release,
669 * and the same for retrieving ioctl version.
671 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
672 cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
673 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
674 fp = fget(param->ioctlfd);
676 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
682 sbi = autofs_dev_ioctl_sbi(fp);
683 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
690 * Admin needs to be able to set the mount catatonic in
691 * order to be able to perform the re-open.
693 if (!autofs4_oz_mode(sbi) &&
694 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
701 err = fn(fp, sbi, param);
705 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
708 free_dev_ioctl(param);
712 static long autofs_dev_ioctl(struct file *file, unsigned int command,
717 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
722 static long autofs_dev_ioctl_compat(struct file *file, unsigned int command,
725 return autofs_dev_ioctl(file, command, (unsigned long) compat_ptr(u));
728 #define autofs_dev_ioctl_compat NULL
731 static const struct file_operations _dev_ioctl_fops = {
732 .unlocked_ioctl = autofs_dev_ioctl,
733 .compat_ioctl = autofs_dev_ioctl_compat,
734 .owner = THIS_MODULE,
735 .llseek = noop_llseek,
738 static struct miscdevice _autofs_dev_ioctl_misc = {
739 .minor = AUTOFS_MINOR,
740 .name = AUTOFS_DEVICE_NAME,
741 .fops = &_dev_ioctl_fops,
745 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
746 MODULE_ALIAS("devname:autofs");
748 /* Register/deregister misc character device */
749 int __init autofs_dev_ioctl_init(void)
753 r = misc_register(&_autofs_dev_ioctl_misc);
755 pr_err("misc_register failed for control device\n");
762 void autofs_dev_ioctl_exit(void)
764 misc_deregister(&_autofs_dev_ioctl_misc);