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, size_t size)
59 if (memchr(str, 0, size))
65 * Check that the user compiled against correct version of autofs
68 * As well as checking the version compatibility this always copies
69 * the kernel interface version out.
71 static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
75 if ((AUTOFS_DEV_IOCTL_VERSION_MAJOR != param->ver_major) ||
76 (AUTOFS_DEV_IOCTL_VERSION_MINOR < param->ver_minor)) {
77 AUTOFS_WARN("ioctl control interface version mismatch: "
78 "kernel(%u.%u), user(%u.%u), cmd(%d)",
79 AUTOFS_DEV_IOCTL_VERSION_MAJOR,
80 AUTOFS_DEV_IOCTL_VERSION_MINOR,
81 param->ver_major, param->ver_minor, cmd);
85 /* Fill in the kernel version. */
86 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
87 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
93 * Copy parameter control struct, including a possible path allocated
94 * at the end of the struct.
96 static struct autofs_dev_ioctl *copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
98 struct autofs_dev_ioctl tmp, *ads;
100 if (copy_from_user(&tmp, in, sizeof(tmp)))
101 return ERR_PTR(-EFAULT);
103 if (tmp.size < sizeof(tmp))
104 return ERR_PTR(-EINVAL);
106 ads = kmalloc(tmp.size, GFP_KERNEL);
108 return ERR_PTR(-ENOMEM);
110 if (copy_from_user(ads, in, tmp.size)) {
112 return ERR_PTR(-EFAULT);
118 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
125 * Check sanity of parameter control fields and if a path is present
126 * check that it is terminated and contains at least one "/".
128 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
132 err = check_dev_ioctl_version(cmd, param);
134 AUTOFS_WARN("invalid device control module version "
135 "supplied for cmd(0x%08x)", cmd);
139 if (param->size > sizeof(*param)) {
140 err = invalid_str(param->path, param->size - sizeof(*param));
143 "path string terminator missing for cmd(0x%08x)",
148 err = check_name(param->path);
150 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
162 * Get the autofs super block info struct from the file opened on
163 * the autofs mount point.
165 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
167 struct autofs_sb_info *sbi = NULL;
171 inode = f->f_path.dentry->d_inode;
172 sbi = autofs4_sbi(inode->i_sb);
177 /* Return autofs module protocol version */
178 static int autofs_dev_ioctl_protover(struct file *fp,
179 struct autofs_sb_info *sbi,
180 struct autofs_dev_ioctl *param)
182 param->protover.version = sbi->version;
186 /* Return autofs module protocol sub version */
187 static int autofs_dev_ioctl_protosubver(struct file *fp,
188 struct autofs_sb_info *sbi,
189 struct autofs_dev_ioctl *param)
191 param->protosubver.sub_version = sbi->sub_version;
195 static int find_autofs_mount(const char *pathname,
197 int test(struct path *path, void *data),
201 int err = kern_path(pathname, 0, &path);
205 while (path.dentry == path.mnt->mnt_root) {
206 if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
207 if (test(&path, data)) {
209 if (!err) /* already found some */
215 if (!follow_up(&path))
222 static int test_by_dev(struct path *path, void *p)
224 return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
227 static int test_by_type(struct path *path, void *p)
229 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
230 return ino && ino->sbi->type & *(unsigned *)p;
233 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
235 struct files_struct *files = current->files;
238 spin_lock(&files->file_lock);
239 fdt = files_fdtable(files);
240 BUG_ON(fdt->fd[fd] != NULL);
241 rcu_assign_pointer(fdt->fd[fd], file);
242 FD_SET(fd, fdt->close_on_exec);
243 spin_unlock(&files->file_lock);
248 * Open a file descriptor on the autofs mount point corresponding
249 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
251 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
255 fd = get_unused_fd();
256 if (likely(fd >= 0)) {
260 err = find_autofs_mount(name, &path, test_by_dev, &devid);
265 * Find autofs super block that has the device number
266 * corresponding to the autofs fs we want to open.
269 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
276 autofs_dev_ioctl_fd_install(fd, filp);
286 /* Open a file descriptor on an autofs mount point */
287 static int autofs_dev_ioctl_openmount(struct file *fp,
288 struct autofs_sb_info *sbi,
289 struct autofs_dev_ioctl *param)
295 /* param->path has already been checked */
296 if (!param->openmount.devid)
302 devid = new_decode_dev(param->openmount.devid);
305 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
306 if (unlikely(fd < 0)) {
316 /* Close file descriptor allocated above (user can also use close(2)). */
317 static int autofs_dev_ioctl_closemount(struct file *fp,
318 struct autofs_sb_info *sbi,
319 struct autofs_dev_ioctl *param)
321 return sys_close(param->ioctlfd);
325 * Send "ready" status for an existing wait (either a mount or an expire
328 static int autofs_dev_ioctl_ready(struct file *fp,
329 struct autofs_sb_info *sbi,
330 struct autofs_dev_ioctl *param)
334 token = (autofs_wqt_t) param->ready.token;
335 return autofs4_wait_release(sbi, token, 0);
339 * Send "fail" status for an existing wait (either a mount or an expire
342 static int autofs_dev_ioctl_fail(struct file *fp,
343 struct autofs_sb_info *sbi,
344 struct autofs_dev_ioctl *param)
349 token = (autofs_wqt_t) param->fail.token;
350 status = param->fail.status ? param->fail.status : -ENOENT;
351 return autofs4_wait_release(sbi, token, status);
355 * Set the pipe fd for kernel communication to the daemon.
357 * Normally this is set at mount using an option but if we
358 * are reconnecting to a busy mount then we need to use this
359 * to tell the autofs mount about the new kernel pipe fd. In
360 * order to protect mounts against incorrectly setting the
361 * pipefd we also require that the autofs mount be catatonic.
363 * This also sets the process group id used to identify the
364 * controlling process (eg. the owning automount(8) daemon).
366 static int autofs_dev_ioctl_setpipefd(struct file *fp,
367 struct autofs_sb_info *sbi,
368 struct autofs_dev_ioctl *param)
373 if (param->setpipefd.pipefd == -1)
376 pipefd = param->setpipefd.pipefd;
378 mutex_lock(&sbi->wq_mutex);
379 if (!sbi->catatonic) {
380 mutex_unlock(&sbi->wq_mutex);
383 struct file *pipe = fget(pipefd);
384 if (!pipe->f_op || !pipe->f_op->write) {
389 sbi->oz_pgrp = task_pgrp_nr(current);
390 sbi->pipefd = pipefd;
395 mutex_unlock(&sbi->wq_mutex);
400 * Make the autofs mount point catatonic, no longer responsive to
401 * mount requests. Also closes the kernel pipe file descriptor.
403 static int autofs_dev_ioctl_catatonic(struct file *fp,
404 struct autofs_sb_info *sbi,
405 struct autofs_dev_ioctl *param)
407 autofs4_catatonic_mode(sbi);
411 /* Set the autofs mount timeout */
412 static int autofs_dev_ioctl_timeout(struct file *fp,
413 struct autofs_sb_info *sbi,
414 struct autofs_dev_ioctl *param)
416 unsigned long timeout;
418 timeout = param->timeout.timeout;
419 param->timeout.timeout = sbi->exp_timeout / HZ;
420 sbi->exp_timeout = timeout * HZ;
425 * Return the uid and gid of the last request for the mount
427 * When reconstructing an autofs mount tree with active mounts
428 * we need to re-connect to mounts that may have used the original
429 * process uid and gid (or string variations of them) for mount
430 * lookups within the map entry.
432 static int autofs_dev_ioctl_requester(struct file *fp,
433 struct autofs_sb_info *sbi,
434 struct autofs_dev_ioctl *param)
436 struct autofs_info *ino;
441 if (param->size <= sizeof(*param)) {
446 devid = sbi->sb->s_dev;
448 param->requester.uid = param->requester.gid = -1;
450 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
454 ino = autofs4_dentry_ino(path.dentry);
457 autofs4_expire_wait(path.dentry);
458 spin_lock(&sbi->fs_lock);
459 param->requester.uid = ino->uid;
460 param->requester.gid = ino->gid;
461 spin_unlock(&sbi->fs_lock);
469 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
470 * more that can be done.
472 static int autofs_dev_ioctl_expire(struct file *fp,
473 struct autofs_sb_info *sbi,
474 struct autofs_dev_ioctl *param)
476 struct vfsmount *mnt;
479 how = param->expire.how;
480 mnt = fp->f_path.mnt;
482 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
485 /* Check if autofs mount point is in use */
486 static int autofs_dev_ioctl_askumount(struct file *fp,
487 struct autofs_sb_info *sbi,
488 struct autofs_dev_ioctl *param)
490 param->askumount.may_umount = 0;
491 if (may_umount(fp->f_path.mnt))
492 param->askumount.may_umount = 1;
497 * Check if the given path is a mountpoint.
499 * If we are supplied with the file descriptor of an autofs
500 * mount we're looking for a specific mount. In this case
501 * the path is considered a mountpoint if it is itself a
502 * mountpoint or contains a mount, such as a multi-mount
503 * without a root mount. In this case we return 1 if the
504 * path is a mount point and the super magic of the covering
505 * mount if there is one or 0 if it isn't a mountpoint.
507 * If we aren't supplied with a file descriptor then we
508 * lookup the nameidata of the path and check if it is the
509 * root of a mount. If a type is given we are looking for
510 * a particular autofs mount and if we don't find a match
511 * we return fail. If the located nameidata path is the
512 * root of a mount we return 1 along with the super magic
513 * of the mount or 0 otherwise.
515 * In both cases the the device number (as returned by
516 * new_encode_dev()) is also returned.
518 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
519 struct autofs_sb_info *sbi,
520 struct autofs_dev_ioctl *param)
525 unsigned int devid, magic;
528 if (param->size <= sizeof(*param)) {
534 type = param->ismountpoint.in.type;
536 param->ismountpoint.out.devid = devid = 0;
537 param->ismountpoint.out.magic = magic = 0;
539 if (!fp || param->ioctlfd == -1) {
540 if (autofs_type_any(type))
541 err = kern_path(name, LOOKUP_FOLLOW, &path);
543 err = find_autofs_mount(name, &path, test_by_type, &type);
546 devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
548 if (path.dentry->d_inode &&
549 path.mnt->mnt_root == path.dentry) {
551 magic = path.dentry->d_inode->i_sb->s_magic;
554 dev_t dev = sbi->sb->s_dev;
556 err = find_autofs_mount(name, &path, test_by_dev, &dev);
560 devid = new_encode_dev(dev);
562 err = have_submounts(path.dentry);
564 if (path.mnt->mnt_mountpoint != path.mnt->mnt_root) {
565 if (follow_down(&path))
566 magic = path.mnt->mnt_sb->s_magic;
570 param->ismountpoint.out.devid = devid;
571 param->ismountpoint.out.magic = magic;
578 * Our range of ioctl numbers isn't 0 based so we need to shift
579 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
582 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
584 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
590 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
591 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
592 autofs_dev_ioctl_protover},
593 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
594 autofs_dev_ioctl_protosubver},
595 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
596 autofs_dev_ioctl_openmount},
597 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
598 autofs_dev_ioctl_closemount},
599 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
600 autofs_dev_ioctl_ready},
601 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
602 autofs_dev_ioctl_fail},
603 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
604 autofs_dev_ioctl_setpipefd},
605 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
606 autofs_dev_ioctl_catatonic},
607 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
608 autofs_dev_ioctl_timeout},
609 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
610 autofs_dev_ioctl_requester},
611 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
612 autofs_dev_ioctl_expire},
613 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
614 autofs_dev_ioctl_askumount},
615 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
616 autofs_dev_ioctl_ismountpoint}
618 unsigned int idx = cmd_idx(cmd);
620 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
623 /* ioctl dispatcher */
624 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
626 struct autofs_dev_ioctl *param;
628 struct autofs_sb_info *sbi;
629 unsigned int cmd_first, cmd;
633 /* only root can play with this */
634 if (!capable(CAP_SYS_ADMIN))
637 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
638 cmd = _IOC_NR(command);
640 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
641 cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
645 /* Copy the parameters into kernel space. */
646 param = copy_dev_ioctl(user);
648 return PTR_ERR(param);
650 err = validate_dev_ioctl(command, param);
654 /* The validate routine above always sets the version */
655 if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
658 fn = lookup_dev_ioctl(cmd);
660 AUTOFS_WARN("unknown command 0x%08x", command);
668 * For obvious reasons the openmount can't have a file
669 * descriptor yet. We don't take a reference to the
670 * file during close to allow for immediate release.
672 if (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)
688 sbi = autofs_dev_ioctl_sbi(fp);
689 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
696 * Admin needs to be able to set the mount catatonic in
697 * order to be able to perform the re-open.
699 if (!autofs4_oz_mode(sbi) &&
700 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
707 err = fn(fp, sbi, param);
712 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
715 free_dev_ioctl(param);
719 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
722 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
727 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
729 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
732 #define autofs_dev_ioctl_compat NULL
735 static const struct file_operations _dev_ioctl_fops = {
736 .unlocked_ioctl = autofs_dev_ioctl,
737 .compat_ioctl = autofs_dev_ioctl_compat,
738 .owner = THIS_MODULE,
741 static struct miscdevice _autofs_dev_ioctl_misc = {
742 .minor = MISC_DYNAMIC_MINOR,
743 .name = AUTOFS_DEVICE_NAME,
744 .fops = &_dev_ioctl_fops
747 /* Register/deregister misc character device */
748 int autofs_dev_ioctl_init(void)
752 r = misc_register(&_autofs_dev_ioctl_misc);
754 AUTOFS_ERROR("misc_register failed for control device");
761 void autofs_dev_ioctl_exit(void)
763 misc_deregister(&_autofs_dev_ioctl_misc);