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/magic.h>
23 #include <linux/dcache.h>
24 #include <linux/uaccess.h>
29 * This module implements an interface for routing autofs ioctl control
30 * commands via a miscellaneous device file.
32 * The alternate interface is needed because we need to be able open
33 * an ioctl file descriptor on an autofs mount that may be covered by
34 * another mount. This situation arises when starting automount(8)
35 * or other user space daemon which uses direct mounts or offset
36 * mounts (used for autofs lazy mount/umount of nested mount trees),
37 * which have been left busy at at service shutdown.
40 #define AUTOFS_DEV_IOCTL_SIZE sizeof(struct autofs_dev_ioctl)
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 ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
75 (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
76 AUTOFS_WARN("ioctl control interface version mismatch: "
77 "kernel(%u.%u), user(%u.%u), cmd(%d)",
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 *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
97 struct autofs_dev_ioctl tmp, *ads;
99 if (copy_from_user(&tmp, in, sizeof(tmp)))
100 return ERR_PTR(-EFAULT);
102 if (tmp.size < sizeof(tmp))
103 return ERR_PTR(-EINVAL);
105 ads = kmalloc(tmp.size, GFP_KERNEL);
107 return ERR_PTR(-ENOMEM);
109 if (copy_from_user(ads, in, tmp.size)) {
111 return ERR_PTR(-EFAULT);
117 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
124 * Check sanity of parameter control fields and if a path is present
125 * check that it is terminated and contains at least one "/".
127 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
131 err = check_dev_ioctl_version(cmd, param);
133 AUTOFS_WARN("invalid device control module version "
134 "supplied for cmd(0x%08x)", cmd);
138 if (param->size > sizeof(*param)) {
139 err = invalid_str(param->path, param->size - sizeof(*param));
142 "path string terminator missing for cmd(0x%08x)",
147 err = check_name(param->path);
149 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
161 * Get the autofs super block info struct from the file opened on
162 * the autofs mount point.
164 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
166 struct autofs_sb_info *sbi = NULL;
170 inode = f->f_path.dentry->d_inode;
171 sbi = autofs4_sbi(inode->i_sb);
176 /* Return autofs module protocol version */
177 static int autofs_dev_ioctl_protover(struct file *fp,
178 struct autofs_sb_info *sbi,
179 struct autofs_dev_ioctl *param)
181 param->protover.version = sbi->version;
185 /* Return autofs module protocol sub version */
186 static int autofs_dev_ioctl_protosubver(struct file *fp,
187 struct autofs_sb_info *sbi,
188 struct autofs_dev_ioctl *param)
190 param->protosubver.sub_version = sbi->sub_version;
194 static int find_autofs_mount(const char *pathname,
196 int test(struct path *path, void *data),
200 int err = kern_path(pathname, 0, &path);
204 while (path.dentry == path.mnt->mnt_root) {
205 if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
206 if (test(&path, data)) {
208 if (!err) /* already found some */
214 if (!follow_up(&path))
221 static int test_by_dev(struct path *path, void *p)
223 return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
226 static int test_by_type(struct path *path, void *p)
228 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
229 return ino && ino->sbi->type & *(unsigned *)p;
232 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
234 struct files_struct *files = current->files;
237 spin_lock(&files->file_lock);
238 fdt = files_fdtable(files);
239 BUG_ON(fdt->fd[fd] != NULL);
240 rcu_assign_pointer(fdt->fd[fd], file);
241 FD_SET(fd, fdt->close_on_exec);
242 spin_unlock(&files->file_lock);
247 * Open a file descriptor on the autofs mount point corresponding
248 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
250 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
254 fd = get_unused_fd();
255 if (likely(fd >= 0)) {
259 err = find_autofs_mount(name, &path, test_by_dev, &devid);
264 * Find autofs super block that has the device number
265 * corresponding to the autofs fs we want to open.
268 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
275 autofs_dev_ioctl_fd_install(fd, filp);
285 /* Open a file descriptor on an autofs mount point */
286 static int autofs_dev_ioctl_openmount(struct file *fp,
287 struct autofs_sb_info *sbi,
288 struct autofs_dev_ioctl *param)
294 /* param->path has already been checked */
295 if (!param->openmount.devid)
301 devid = new_decode_dev(param->openmount.devid);
304 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
305 if (unlikely(fd < 0)) {
315 /* Close file descriptor allocated above (user can also use close(2)). */
316 static int autofs_dev_ioctl_closemount(struct file *fp,
317 struct autofs_sb_info *sbi,
318 struct autofs_dev_ioctl *param)
320 return sys_close(param->ioctlfd);
324 * Send "ready" status for an existing wait (either a mount or an expire
327 static int autofs_dev_ioctl_ready(struct file *fp,
328 struct autofs_sb_info *sbi,
329 struct autofs_dev_ioctl *param)
333 token = (autofs_wqt_t) param->ready.token;
334 return autofs4_wait_release(sbi, token, 0);
338 * Send "fail" status for an existing wait (either a mount or an expire
341 static int autofs_dev_ioctl_fail(struct file *fp,
342 struct autofs_sb_info *sbi,
343 struct autofs_dev_ioctl *param)
348 token = (autofs_wqt_t) param->fail.token;
349 status = param->fail.status ? param->fail.status : -ENOENT;
350 return autofs4_wait_release(sbi, token, status);
354 * Set the pipe fd for kernel communication to the daemon.
356 * Normally this is set at mount using an option but if we
357 * are reconnecting to a busy mount then we need to use this
358 * to tell the autofs mount about the new kernel pipe fd. In
359 * order to protect mounts against incorrectly setting the
360 * pipefd we also require that the autofs mount be catatonic.
362 * This also sets the process group id used to identify the
363 * controlling process (eg. the owning automount(8) daemon).
365 static int autofs_dev_ioctl_setpipefd(struct file *fp,
366 struct autofs_sb_info *sbi,
367 struct autofs_dev_ioctl *param)
372 if (param->setpipefd.pipefd == -1)
375 pipefd = param->setpipefd.pipefd;
377 mutex_lock(&sbi->wq_mutex);
378 if (!sbi->catatonic) {
379 mutex_unlock(&sbi->wq_mutex);
382 struct file *pipe = fget(pipefd);
383 if (!pipe->f_op || !pipe->f_op->write) {
388 sbi->oz_pgrp = task_pgrp_nr(current);
389 sbi->pipefd = pipefd;
394 mutex_unlock(&sbi->wq_mutex);
399 * Make the autofs mount point catatonic, no longer responsive to
400 * mount requests. Also closes the kernel pipe file descriptor.
402 static int autofs_dev_ioctl_catatonic(struct file *fp,
403 struct autofs_sb_info *sbi,
404 struct autofs_dev_ioctl *param)
406 autofs4_catatonic_mode(sbi);
410 /* Set the autofs mount timeout */
411 static int autofs_dev_ioctl_timeout(struct file *fp,
412 struct autofs_sb_info *sbi,
413 struct autofs_dev_ioctl *param)
415 unsigned long timeout;
417 timeout = param->timeout.timeout;
418 param->timeout.timeout = sbi->exp_timeout / HZ;
419 sbi->exp_timeout = timeout * HZ;
424 * Return the uid and gid of the last request for the mount
426 * When reconstructing an autofs mount tree with active mounts
427 * we need to re-connect to mounts that may have used the original
428 * process uid and gid (or string variations of them) for mount
429 * lookups within the map entry.
431 static int autofs_dev_ioctl_requester(struct file *fp,
432 struct autofs_sb_info *sbi,
433 struct autofs_dev_ioctl *param)
435 struct autofs_info *ino;
440 if (param->size <= sizeof(*param)) {
445 devid = sbi->sb->s_dev;
447 param->requester.uid = param->requester.gid = -1;
449 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
453 ino = autofs4_dentry_ino(path.dentry);
456 autofs4_expire_wait(path.dentry);
457 spin_lock(&sbi->fs_lock);
458 param->requester.uid = ino->uid;
459 param->requester.gid = ino->gid;
460 spin_unlock(&sbi->fs_lock);
468 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
469 * more that can be done.
471 static int autofs_dev_ioctl_expire(struct file *fp,
472 struct autofs_sb_info *sbi,
473 struct autofs_dev_ioctl *param)
475 struct vfsmount *mnt;
478 how = param->expire.how;
479 mnt = fp->f_path.mnt;
481 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
484 /* Check if autofs mount point is in use */
485 static int autofs_dev_ioctl_askumount(struct file *fp,
486 struct autofs_sb_info *sbi,
487 struct autofs_dev_ioctl *param)
489 param->askumount.may_umount = 0;
490 if (may_umount(fp->f_path.mnt))
491 param->askumount.may_umount = 1;
496 * Check if the given path is a mountpoint.
498 * If we are supplied with the file descriptor of an autofs
499 * mount we're looking for a specific mount. In this case
500 * the path is considered a mountpoint if it is itself a
501 * mountpoint or contains a mount, such as a multi-mount
502 * without a root mount. In this case we return 1 if the
503 * path is a mount point and the super magic of the covering
504 * mount if there is one or 0 if it isn't a mountpoint.
506 * If we aren't supplied with a file descriptor then we
507 * lookup the nameidata of the path and check if it is the
508 * root of a mount. If a type is given we are looking for
509 * a particular autofs mount and if we don't find a match
510 * we return fail. If the located nameidata path is the
511 * root of a mount we return 1 along with the super magic
512 * of the mount or 0 otherwise.
514 * In both cases the the device number (as returned by
515 * new_encode_dev()) is also returned.
517 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
518 struct autofs_sb_info *sbi,
519 struct autofs_dev_ioctl *param)
524 unsigned int devid, magic;
527 if (param->size <= sizeof(*param)) {
533 type = param->ismountpoint.in.type;
535 param->ismountpoint.out.devid = devid = 0;
536 param->ismountpoint.out.magic = magic = 0;
538 if (!fp || param->ioctlfd == -1) {
539 if (autofs_type_any(type))
540 err = kern_path(name, LOOKUP_FOLLOW, &path);
542 err = find_autofs_mount(name, &path, test_by_type, &type);
545 devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
547 if (path.dentry->d_inode &&
548 path.mnt->mnt_root == path.dentry) {
550 magic = path.dentry->d_inode->i_sb->s_magic;
553 dev_t dev = sbi->sb->s_dev;
555 err = find_autofs_mount(name, &path, test_by_dev, &dev);
559 devid = new_encode_dev(dev);
561 err = have_submounts(path.dentry);
563 if (path.mnt->mnt_mountpoint != path.mnt->mnt_root) {
564 if (follow_down(&path))
565 magic = path.mnt->mnt_sb->s_magic;
569 param->ismountpoint.out.devid = devid;
570 param->ismountpoint.out.magic = magic;
577 * Our range of ioctl numbers isn't 0 based so we need to shift
578 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
581 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
583 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
589 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
590 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
591 autofs_dev_ioctl_protover},
592 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
593 autofs_dev_ioctl_protosubver},
594 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
595 autofs_dev_ioctl_openmount},
596 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
597 autofs_dev_ioctl_closemount},
598 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
599 autofs_dev_ioctl_ready},
600 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
601 autofs_dev_ioctl_fail},
602 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
603 autofs_dev_ioctl_setpipefd},
604 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
605 autofs_dev_ioctl_catatonic},
606 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
607 autofs_dev_ioctl_timeout},
608 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
609 autofs_dev_ioctl_requester},
610 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
611 autofs_dev_ioctl_expire},
612 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
613 autofs_dev_ioctl_askumount},
614 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
615 autofs_dev_ioctl_ismountpoint}
617 unsigned int idx = cmd_idx(cmd);
619 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
622 /* ioctl dispatcher */
623 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
625 struct autofs_dev_ioctl *param;
627 struct autofs_sb_info *sbi;
628 unsigned int cmd_first, cmd;
632 /* only root can play with this */
633 if (!capable(CAP_SYS_ADMIN))
636 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
637 cmd = _IOC_NR(command);
639 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
640 cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
644 /* Copy the parameters into kernel space. */
645 param = copy_dev_ioctl(user);
647 return PTR_ERR(param);
649 err = validate_dev_ioctl(command, param);
653 /* The validate routine above always sets the version */
654 if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
657 fn = lookup_dev_ioctl(cmd);
659 AUTOFS_WARN("unknown command 0x%08x", command);
667 * For obvious reasons the openmount can't have a file
668 * descriptor yet. We don't take a reference to the
669 * file during close to allow for immediate release.
671 if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
672 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
673 fp = fget(param->ioctlfd);
675 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
687 sbi = autofs_dev_ioctl_sbi(fp);
688 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
695 * Admin needs to be able to set the mount catatonic in
696 * order to be able to perform the re-open.
698 if (!autofs4_oz_mode(sbi) &&
699 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
706 err = fn(fp, sbi, param);
711 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
714 free_dev_ioctl(param);
718 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
721 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
726 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
728 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
731 #define autofs_dev_ioctl_compat NULL
734 static const struct file_operations _dev_ioctl_fops = {
735 .unlocked_ioctl = autofs_dev_ioctl,
736 .compat_ioctl = autofs_dev_ioctl_compat,
737 .owner = THIS_MODULE,
740 static struct miscdevice _autofs_dev_ioctl_misc = {
741 .minor = MISC_DYNAMIC_MINOR,
742 .name = AUTOFS_DEVICE_NAME,
743 .fops = &_dev_ioctl_fops
746 /* Register/deregister misc character device */
747 int autofs_dev_ioctl_init(void)
751 r = misc_register(&_autofs_dev_ioctl_misc);
753 AUTOFS_ERROR("misc_register failed for control device");
760 void autofs_dev_ioctl_exit(void)
762 misc_deregister(&_autofs_dev_ioctl_misc);