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/compat.h>
21 #include <linux/syscalls.h>
22 #include <linux/smp_lock.h>
23 #include <linux/magic.h>
24 #include <linux/dcache.h>
25 #include <linux/uaccess.h>
30 * This module implements an interface for routing autofs ioctl control
31 * commands via a miscellaneous device file.
33 * The alternate interface is needed because we need to be able open
34 * an ioctl file descriptor on an autofs mount that may be covered by
35 * another mount. This situation arises when starting automount(8)
36 * or other user space daemon which uses direct mounts or offset
37 * mounts (used for autofs lazy mount/umount of nested mount trees),
38 * which have been left busy at at service shutdown.
41 #define AUTOFS_DEV_IOCTL_SIZE sizeof(struct autofs_dev_ioctl)
43 typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
44 struct autofs_dev_ioctl *);
46 static int check_name(const char *name)
48 if (!strchr(name, '/'))
54 * Check a string doesn't overrun the chunk of
55 * memory we copied from user land.
57 static int invalid_str(char *str, void *end)
59 while ((void *) str <= end)
66 * Check that the user compiled against correct version of autofs
69 * As well as checking the version compatibility this always copies
70 * the kernel interface version out.
72 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
76 if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
77 (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
78 AUTOFS_WARN("ioctl control interface version mismatch: "
79 "kernel(%u.%u), user(%u.%u), cmd(%d)",
80 AUTOFS_DEV_IOCTL_VERSION_MAJOR,
81 AUTOFS_DEV_IOCTL_VERSION_MINOR,
82 param->ver_major, param->ver_minor, cmd);
86 /* Fill in the kernel version. */
87 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
88 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
94 * Copy parameter control struct, including a possible path allocated
95 * at the end of the struct.
97 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
99 struct autofs_dev_ioctl tmp, *ads;
101 if (copy_from_user(&tmp, in, sizeof(tmp)))
102 return ERR_PTR(-EFAULT);
104 if (tmp.size < sizeof(tmp))
105 return ERR_PTR(-EINVAL);
107 ads = kmalloc(tmp.size, GFP_KERNEL);
109 return ERR_PTR(-ENOMEM);
111 if (copy_from_user(ads, in, tmp.size)) {
113 return ERR_PTR(-EFAULT);
119 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
126 * Check sanity of parameter control fields and if a path is present
127 * check that it has a "/" and is terminated.
129 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
133 err = check_dev_ioctl_version(cmd, param);
135 AUTOFS_WARN("invalid device control module version "
136 "supplied for cmd(0x%08x)", cmd);
140 if (param->size > sizeof(*param)) {
141 err = check_name(param->path);
143 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
148 err = invalid_str(param->path,
149 (void *) ((size_t) param + param->size));
151 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
163 * Get the autofs super block info struct from the file opened on
164 * the autofs mount point.
166 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
168 struct autofs_sb_info *sbi = NULL;
172 inode = f->f_path.dentry->d_inode;
173 sbi = autofs4_sbi(inode->i_sb);
178 /* Return autofs module protocol version */
179 static int autofs_dev_ioctl_protover(struct file *fp,
180 struct autofs_sb_info *sbi,
181 struct autofs_dev_ioctl *param)
183 param->protover.version = sbi->version;
187 /* Return autofs module protocol sub version */
188 static int autofs_dev_ioctl_protosubver(struct file *fp,
189 struct autofs_sb_info *sbi,
190 struct autofs_dev_ioctl *param)
192 param->protosubver.sub_version = sbi->sub_version;
197 * Walk down the mount stack looking for an autofs mount that
198 * has the requested device number (aka. new_encode_dev(sb->s_dev).
200 static int autofs_dev_ioctl_find_super(struct nameidata *nd, dev_t devno)
202 struct dentry *dentry;
204 struct super_block *sb;
210 /* Lookup the dentry name at the base of our mount point */
211 dentry = d_lookup(nd->path.dentry, &nd->last);
215 dput(nd->path.dentry);
216 nd->path.dentry = dentry;
218 /* And follow the mount stack looking for our autofs mount */
219 while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
220 inode = nd->path.dentry->d_inode;
225 s_dev = new_encode_dev(sb->s_dev);
226 if (devno == s_dev) {
227 if (sb->s_magic == AUTOFS_SUPER_MAGIC) {
238 * Walk down the mount stack looking for an autofs mount that
239 * has the requested mount type (ie. indirect, direct or offset).
241 static int autofs_dev_ioctl_find_sbi_type(struct nameidata *nd, unsigned int type)
243 struct dentry *dentry;
244 struct autofs_info *ino;
249 /* Lookup the dentry name at the base of our mount point */
250 dentry = d_lookup(nd->path.dentry, &nd->last);
254 dput(nd->path.dentry);
255 nd->path.dentry = dentry;
257 /* And follow the mount stack looking for our autofs mount */
258 while (follow_down(&nd->path.mnt, &nd->path.dentry)) {
259 ino = autofs4_dentry_ino(nd->path.dentry);
260 if (ino && ino->sbi->type & type) {
269 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
271 struct files_struct *files = current->files;
274 spin_lock(&files->file_lock);
275 fdt = files_fdtable(files);
276 BUG_ON(fdt->fd[fd] != NULL);
277 rcu_assign_pointer(fdt->fd[fd], file);
278 FD_SET(fd, fdt->close_on_exec);
279 spin_unlock(&files->file_lock);
284 * Open a file descriptor on the autofs mount point corresponding
285 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
287 static int autofs_dev_ioctl_open_mountpoint(const char *path, dev_t devid)
293 fd = get_unused_fd();
294 if (likely(fd >= 0)) {
295 /* Get nameidata of the parent directory */
296 err = path_lookup(path, LOOKUP_PARENT, &nd);
301 * Search down, within the parent, looking for an
302 * autofs super block that has the device number
303 * corresponding to the autofs fs we want to open.
305 err = autofs_dev_ioctl_find_super(&nd, devid);
311 filp = dentry_open(nd.path.dentry, nd.path.mnt, O_RDONLY,
318 autofs_dev_ioctl_fd_install(fd, filp);
328 /* Open a file descriptor on an autofs mount point */
329 static int autofs_dev_ioctl_openmount(struct file *fp,
330 struct autofs_sb_info *sbi,
331 struct autofs_dev_ioctl *param)
337 /* param->path has already been checked */
338 if (!param->openmount.devid)
344 devid = param->openmount.devid;
347 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
348 if (unlikely(fd < 0)) {
358 /* Close file descriptor allocated above (user can also use close(2)). */
359 static int autofs_dev_ioctl_closemount(struct file *fp,
360 struct autofs_sb_info *sbi,
361 struct autofs_dev_ioctl *param)
363 return sys_close(param->ioctlfd);
367 * Send "ready" status for an existing wait (either a mount or an expire
370 static int autofs_dev_ioctl_ready(struct file *fp,
371 struct autofs_sb_info *sbi,
372 struct autofs_dev_ioctl *param)
376 token = (autofs_wqt_t) param->ready.token;
377 return autofs4_wait_release(sbi, token, 0);
381 * Send "fail" status for an existing wait (either a mount or an expire
384 static int autofs_dev_ioctl_fail(struct file *fp,
385 struct autofs_sb_info *sbi,
386 struct autofs_dev_ioctl *param)
391 token = (autofs_wqt_t) param->fail.token;
392 status = param->fail.status ? param->fail.status : -ENOENT;
393 return autofs4_wait_release(sbi, token, status);
397 * Set the pipe fd for kernel communication to the daemon.
399 * Normally this is set at mount using an option but if we
400 * are reconnecting to a busy mount then we need to use this
401 * to tell the autofs mount about the new kernel pipe fd. In
402 * order to protect mounts against incorrectly setting the
403 * pipefd we also require that the autofs mount be catatonic.
405 * This also sets the process group id used to identify the
406 * controlling process (eg. the owning automount(8) daemon).
408 static int autofs_dev_ioctl_setpipefd(struct file *fp,
409 struct autofs_sb_info *sbi,
410 struct autofs_dev_ioctl *param)
415 if (param->setpipefd.pipefd == -1)
418 pipefd = param->setpipefd.pipefd;
420 mutex_lock(&sbi->wq_mutex);
421 if (!sbi->catatonic) {
422 mutex_unlock(&sbi->wq_mutex);
425 struct file *pipe = fget(pipefd);
426 if (!pipe->f_op || !pipe->f_op->write) {
431 sbi->oz_pgrp = task_pgrp_nr(current);
432 sbi->pipefd = pipefd;
437 mutex_unlock(&sbi->wq_mutex);
442 * Make the autofs mount point catatonic, no longer responsive to
443 * mount requests. Also closes the kernel pipe file descriptor.
445 static int autofs_dev_ioctl_catatonic(struct file *fp,
446 struct autofs_sb_info *sbi,
447 struct autofs_dev_ioctl *param)
449 autofs4_catatonic_mode(sbi);
453 /* Set the autofs mount timeout */
454 static int autofs_dev_ioctl_timeout(struct file *fp,
455 struct autofs_sb_info *sbi,
456 struct autofs_dev_ioctl *param)
458 unsigned long timeout;
460 timeout = param->timeout.timeout;
461 param->timeout.timeout = sbi->exp_timeout / HZ;
462 sbi->exp_timeout = timeout * HZ;
467 * Return the uid and gid of the last request for the mount
469 * When reconstructing an autofs mount tree with active mounts
470 * we need to re-connect to mounts that may have used the original
471 * process uid and gid (or string variations of them) for mount
472 * lookups within the map entry.
474 static int autofs_dev_ioctl_requester(struct file *fp,
475 struct autofs_sb_info *sbi,
476 struct autofs_dev_ioctl *param)
478 struct autofs_info *ino;
484 if (param->size <= sizeof(*param)) {
490 devid = sbi->sb->s_dev;
492 param->requester.uid = param->requester.gid = -1;
494 /* Get nameidata of the parent directory */
495 err = path_lookup(path, LOOKUP_PARENT, &nd);
499 err = autofs_dev_ioctl_find_super(&nd, devid);
503 ino = autofs4_dentry_ino(nd.path.dentry);
506 autofs4_expire_wait(nd.path.dentry);
507 spin_lock(&sbi->fs_lock);
508 param->requester.uid = ino->uid;
509 param->requester.gid = ino->gid;
510 spin_unlock(&sbi->fs_lock);
520 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
521 * more that can be done.
523 static int autofs_dev_ioctl_expire(struct file *fp,
524 struct autofs_sb_info *sbi,
525 struct autofs_dev_ioctl *param)
527 struct dentry *dentry;
528 struct vfsmount *mnt;
532 how = param->expire.how;
533 mnt = fp->f_path.mnt;
535 if (autofs_type_trigger(sbi->type))
536 dentry = autofs4_expire_direct(sbi->sb, mnt, sbi, how);
538 dentry = autofs4_expire_indirect(sbi->sb, mnt, sbi, how);
541 struct autofs_info *ino = autofs4_dentry_ino(dentry);
544 * This is synchronous because it makes the daemon a
547 err = autofs4_wait(sbi, dentry, NFY_EXPIRE);
549 spin_lock(&sbi->fs_lock);
550 if (ino->flags & AUTOFS_INF_MOUNTPOINT) {
551 ino->flags &= ~AUTOFS_INF_MOUNTPOINT;
552 sbi->sb->s_root->d_mounted++;
554 ino->flags &= ~AUTOFS_INF_EXPIRING;
555 complete_all(&ino->expire_complete);
556 spin_unlock(&sbi->fs_lock);
563 /* Check if autofs mount point is in use */
564 static int autofs_dev_ioctl_askumount(struct file *fp,
565 struct autofs_sb_info *sbi,
566 struct autofs_dev_ioctl *param)
568 param->askumount.may_umount = 0;
569 if (may_umount(fp->f_path.mnt))
570 param->askumount.may_umount = 1;
575 * Check if the given path is a mountpoint.
577 * If we are supplied with the file descriptor of an autofs
578 * mount we're looking for a specific mount. In this case
579 * the path is considered a mountpoint if it is itself a
580 * mountpoint or contains a mount, such as a multi-mount
581 * without a root mount. In this case we return 1 if the
582 * path is a mount point and the super magic of the covering
583 * mount if there is one or 0 if it isn't a mountpoint.
585 * If we aren't supplied with a file descriptor then we
586 * lookup the nameidata of the path and check if it is the
587 * root of a mount. If a type is given we are looking for
588 * a particular autofs mount and if we don't find a match
589 * we return fail. If the located nameidata path is the
590 * root of a mount we return 1 along with the super magic
591 * of the mount or 0 otherwise.
593 * In both cases the the device number (as returned by
594 * new_encode_dev()) is also returned.
596 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
597 struct autofs_sb_info *sbi,
598 struct autofs_dev_ioctl *param)
603 unsigned int devid, magic;
606 if (param->size <= sizeof(*param)) {
612 type = param->ismountpoint.in.type;
614 param->ismountpoint.out.devid = devid = 0;
615 param->ismountpoint.out.magic = magic = 0;
617 if (!fp || param->ioctlfd == -1) {
618 if (autofs_type_any(type)) {
619 struct super_block *sb;
621 err = path_lookup(path, LOOKUP_FOLLOW, &nd);
625 sb = nd.path.dentry->d_sb;
626 devid = new_encode_dev(sb->s_dev);
628 struct autofs_info *ino;
630 err = path_lookup(path, LOOKUP_PARENT, &nd);
634 err = autofs_dev_ioctl_find_sbi_type(&nd, type);
638 ino = autofs4_dentry_ino(nd.path.dentry);
639 devid = autofs4_get_dev(ino->sbi);
643 if (nd.path.dentry->d_inode &&
644 nd.path.mnt->mnt_root == nd.path.dentry) {
646 magic = nd.path.dentry->d_inode->i_sb->s_magic;
649 dev_t dev = autofs4_get_dev(sbi);
651 err = path_lookup(path, LOOKUP_PARENT, &nd);
655 err = autofs_dev_ioctl_find_super(&nd, dev);
661 err = have_submounts(nd.path.dentry);
663 if (nd.path.mnt->mnt_mountpoint != nd.path.mnt->mnt_root) {
664 if (follow_down(&nd.path.mnt, &nd.path.dentry)) {
665 struct inode *inode = nd.path.dentry->d_inode;
666 magic = inode->i_sb->s_magic;
671 param->ismountpoint.out.devid = devid;
672 param->ismountpoint.out.magic = magic;
681 * Our range of ioctl numbers isn't 0 based so we need to shift
682 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
685 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
687 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
693 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
694 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
695 autofs_dev_ioctl_protover},
696 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
697 autofs_dev_ioctl_protosubver},
698 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
699 autofs_dev_ioctl_openmount},
700 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
701 autofs_dev_ioctl_closemount},
702 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
703 autofs_dev_ioctl_ready},
704 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
705 autofs_dev_ioctl_fail},
706 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
707 autofs_dev_ioctl_setpipefd},
708 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
709 autofs_dev_ioctl_catatonic},
710 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
711 autofs_dev_ioctl_timeout},
712 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
713 autofs_dev_ioctl_requester},
714 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
715 autofs_dev_ioctl_expire},
716 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
717 autofs_dev_ioctl_askumount},
718 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
719 autofs_dev_ioctl_ismountpoint}
721 unsigned int idx = cmd_idx(cmd);
723 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
726 /* ioctl dispatcher */
727 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
729 struct autofs_dev_ioctl *param;
731 struct autofs_sb_info *sbi;
732 unsigned int cmd_first, cmd;
736 /* only root can play with this */
737 if (!capable(CAP_SYS_ADMIN))
740 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
741 cmd = _IOC_NR(command);
743 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
744 cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
748 /* Copy the parameters into kernel space. */
749 param = copy_dev_ioctl(user);
751 return PTR_ERR(param);
753 err = validate_dev_ioctl(command, param);
757 /* The validate routine above always sets the version */
758 if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
761 fn = lookup_dev_ioctl(cmd);
763 AUTOFS_WARN("unknown command 0x%08x", command);
771 * For obvious reasons the openmount can't have a file
772 * descriptor yet. We don't take a reference to the
773 * file during close to allow for immediate release.
775 if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
776 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
777 fp = fget(param->ioctlfd);
779 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
791 sbi = autofs_dev_ioctl_sbi(fp);
792 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
799 * Admin needs to be able to set the mount catatonic in
800 * order to be able to perform the re-open.
802 if (!autofs4_oz_mode(sbi) &&
803 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
810 err = fn(fp, sbi, param);
815 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
818 free_dev_ioctl(param);
822 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
825 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
830 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
832 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
835 #define autofs_dev_ioctl_compat NULL
838 static const struct file_operations _dev_ioctl_fops = {
839 .unlocked_ioctl = autofs_dev_ioctl,
840 .compat_ioctl = autofs_dev_ioctl_compat,
841 .owner = THIS_MODULE,
844 static struct miscdevice _autofs_dev_ioctl_misc = {
845 .minor = MISC_DYNAMIC_MINOR,
846 .name = AUTOFS_DEVICE_NAME,
847 .fops = &_dev_ioctl_fops
850 /* Register/deregister misc character device */
851 int autofs_dev_ioctl_init(void)
855 r = misc_register(&_autofs_dev_ioctl_misc);
857 AUTOFS_ERROR("misc_register failed for control device");
864 void autofs_dev_ioctl_exit(void)
866 misc_deregister(&_autofs_dev_ioctl_misc);