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>
25 #include <linux/slab.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;
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 return memdup_user(in, tmp.size);
109 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
116 * Check sanity of parameter control fields and if a path is present
117 * check that it is terminated and contains at least one "/".
119 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
123 err = check_dev_ioctl_version(cmd, param);
125 AUTOFS_WARN("invalid device control module version "
126 "supplied for cmd(0x%08x)", cmd);
130 if (param->size > sizeof(*param)) {
131 err = invalid_str(param->path, param->size - sizeof(*param));
134 "path string terminator missing for cmd(0x%08x)",
139 err = check_name(param->path);
141 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
153 * Get the autofs super block info struct from the file opened on
154 * the autofs mount point.
156 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
158 struct autofs_sb_info *sbi = NULL;
162 inode = f->f_path.dentry->d_inode;
163 sbi = autofs4_sbi(inode->i_sb);
168 /* Return autofs module protocol version */
169 static int autofs_dev_ioctl_protover(struct file *fp,
170 struct autofs_sb_info *sbi,
171 struct autofs_dev_ioctl *param)
173 param->protover.version = sbi->version;
177 /* Return autofs module protocol sub version */
178 static int autofs_dev_ioctl_protosubver(struct file *fp,
179 struct autofs_sb_info *sbi,
180 struct autofs_dev_ioctl *param)
182 param->protosubver.sub_version = sbi->sub_version;
186 static int find_autofs_mount(const char *pathname,
188 int test(struct path *path, void *data),
192 int err = kern_path(pathname, 0, &path);
196 while (path.dentry == path.mnt->mnt_root) {
197 if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
198 if (test(&path, data)) {
200 if (!err) /* already found some */
206 if (!follow_up(&path))
213 static int test_by_dev(struct path *path, void *p)
215 return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
218 static int test_by_type(struct path *path, void *p)
220 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
221 return ino && ino->sbi->type & *(unsigned *)p;
224 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
226 struct files_struct *files = current->files;
229 spin_lock(&files->file_lock);
230 fdt = files_fdtable(files);
231 BUG_ON(fdt->fd[fd] != NULL);
232 rcu_assign_pointer(fdt->fd[fd], file);
233 FD_SET(fd, fdt->close_on_exec);
234 spin_unlock(&files->file_lock);
239 * Open a file descriptor on the autofs mount point corresponding
240 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
242 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
246 fd = get_unused_fd();
247 if (likely(fd >= 0)) {
251 err = find_autofs_mount(name, &path, test_by_dev, &devid);
256 * Find autofs super block that has the device number
257 * corresponding to the autofs fs we want to open.
260 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
267 autofs_dev_ioctl_fd_install(fd, filp);
277 /* Open a file descriptor on an autofs mount point */
278 static int autofs_dev_ioctl_openmount(struct file *fp,
279 struct autofs_sb_info *sbi,
280 struct autofs_dev_ioctl *param)
286 /* param->path has already been checked */
287 if (!param->openmount.devid)
293 devid = new_decode_dev(param->openmount.devid);
296 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
297 if (unlikely(fd < 0)) {
307 /* Close file descriptor allocated above (user can also use close(2)). */
308 static int autofs_dev_ioctl_closemount(struct file *fp,
309 struct autofs_sb_info *sbi,
310 struct autofs_dev_ioctl *param)
312 return sys_close(param->ioctlfd);
316 * Send "ready" status for an existing wait (either a mount or an expire
319 static int autofs_dev_ioctl_ready(struct file *fp,
320 struct autofs_sb_info *sbi,
321 struct autofs_dev_ioctl *param)
325 token = (autofs_wqt_t) param->ready.token;
326 return autofs4_wait_release(sbi, token, 0);
330 * Send "fail" status for an existing wait (either a mount or an expire
333 static int autofs_dev_ioctl_fail(struct file *fp,
334 struct autofs_sb_info *sbi,
335 struct autofs_dev_ioctl *param)
340 token = (autofs_wqt_t) param->fail.token;
341 status = param->fail.status ? param->fail.status : -ENOENT;
342 return autofs4_wait_release(sbi, token, status);
346 * Set the pipe fd for kernel communication to the daemon.
348 * Normally this is set at mount using an option but if we
349 * are reconnecting to a busy mount then we need to use this
350 * to tell the autofs mount about the new kernel pipe fd. In
351 * order to protect mounts against incorrectly setting the
352 * pipefd we also require that the autofs mount be catatonic.
354 * This also sets the process group id used to identify the
355 * controlling process (eg. the owning automount(8) daemon).
357 static int autofs_dev_ioctl_setpipefd(struct file *fp,
358 struct autofs_sb_info *sbi,
359 struct autofs_dev_ioctl *param)
364 if (param->setpipefd.pipefd == -1)
367 pipefd = param->setpipefd.pipefd;
369 mutex_lock(&sbi->wq_mutex);
370 if (!sbi->catatonic) {
371 mutex_unlock(&sbi->wq_mutex);
374 struct file *pipe = fget(pipefd);
375 if (!pipe->f_op || !pipe->f_op->write) {
380 sbi->oz_pgrp = task_pgrp_nr(current);
381 sbi->pipefd = pipefd;
386 mutex_unlock(&sbi->wq_mutex);
391 * Make the autofs mount point catatonic, no longer responsive to
392 * mount requests. Also closes the kernel pipe file descriptor.
394 static int autofs_dev_ioctl_catatonic(struct file *fp,
395 struct autofs_sb_info *sbi,
396 struct autofs_dev_ioctl *param)
398 autofs4_catatonic_mode(sbi);
402 /* Set the autofs mount timeout */
403 static int autofs_dev_ioctl_timeout(struct file *fp,
404 struct autofs_sb_info *sbi,
405 struct autofs_dev_ioctl *param)
407 unsigned long timeout;
409 timeout = param->timeout.timeout;
410 param->timeout.timeout = sbi->exp_timeout / HZ;
411 sbi->exp_timeout = timeout * HZ;
416 * Return the uid and gid of the last request for the mount
418 * When reconstructing an autofs mount tree with active mounts
419 * we need to re-connect to mounts that may have used the original
420 * process uid and gid (or string variations of them) for mount
421 * lookups within the map entry.
423 static int autofs_dev_ioctl_requester(struct file *fp,
424 struct autofs_sb_info *sbi,
425 struct autofs_dev_ioctl *param)
427 struct autofs_info *ino;
432 if (param->size <= sizeof(*param)) {
437 devid = sbi->sb->s_dev;
439 param->requester.uid = param->requester.gid = -1;
441 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
445 ino = autofs4_dentry_ino(path.dentry);
448 autofs4_expire_wait(path.dentry);
449 spin_lock(&sbi->fs_lock);
450 param->requester.uid = ino->uid;
451 param->requester.gid = ino->gid;
452 spin_unlock(&sbi->fs_lock);
460 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
461 * more that can be done.
463 static int autofs_dev_ioctl_expire(struct file *fp,
464 struct autofs_sb_info *sbi,
465 struct autofs_dev_ioctl *param)
467 struct vfsmount *mnt;
470 how = param->expire.how;
471 mnt = fp->f_path.mnt;
473 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
476 /* Check if autofs mount point is in use */
477 static int autofs_dev_ioctl_askumount(struct file *fp,
478 struct autofs_sb_info *sbi,
479 struct autofs_dev_ioctl *param)
481 param->askumount.may_umount = 0;
482 if (may_umount(fp->f_path.mnt))
483 param->askumount.may_umount = 1;
488 * Check if the given path is a mountpoint.
490 * If we are supplied with the file descriptor of an autofs
491 * mount we're looking for a specific mount. In this case
492 * the path is considered a mountpoint if it is itself a
493 * mountpoint or contains a mount, such as a multi-mount
494 * without a root mount. In this case we return 1 if the
495 * path is a mount point and the super magic of the covering
496 * mount if there is one or 0 if it isn't a mountpoint.
498 * If we aren't supplied with a file descriptor then we
499 * lookup the nameidata of the path and check if it is the
500 * root of a mount. If a type is given we are looking for
501 * a particular autofs mount and if we don't find a match
502 * we return fail. If the located nameidata path is the
503 * root of a mount we return 1 along with the super magic
504 * of the mount or 0 otherwise.
506 * In both cases the the device number (as returned by
507 * new_encode_dev()) is also returned.
509 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
510 struct autofs_sb_info *sbi,
511 struct autofs_dev_ioctl *param)
516 unsigned int devid, magic;
519 if (param->size <= sizeof(*param)) {
525 type = param->ismountpoint.in.type;
527 param->ismountpoint.out.devid = devid = 0;
528 param->ismountpoint.out.magic = magic = 0;
530 if (!fp || param->ioctlfd == -1) {
531 if (autofs_type_any(type))
532 err = kern_path(name, LOOKUP_FOLLOW, &path);
534 err = find_autofs_mount(name, &path, test_by_type, &type);
537 devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
539 if (path.mnt->mnt_root == path.dentry) {
541 magic = path.mnt->mnt_sb->s_magic;
544 dev_t dev = sbi->sb->s_dev;
546 err = find_autofs_mount(name, &path, test_by_dev, &dev);
550 devid = new_encode_dev(dev);
552 err = have_submounts(path.dentry);
554 if (follow_down(&path))
555 magic = path.mnt->mnt_sb->s_magic;
558 param->ismountpoint.out.devid = devid;
559 param->ismountpoint.out.magic = magic;
566 * Our range of ioctl numbers isn't 0 based so we need to shift
567 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
570 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
572 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
578 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
579 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
580 autofs_dev_ioctl_protover},
581 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
582 autofs_dev_ioctl_protosubver},
583 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
584 autofs_dev_ioctl_openmount},
585 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
586 autofs_dev_ioctl_closemount},
587 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
588 autofs_dev_ioctl_ready},
589 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
590 autofs_dev_ioctl_fail},
591 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
592 autofs_dev_ioctl_setpipefd},
593 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
594 autofs_dev_ioctl_catatonic},
595 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
596 autofs_dev_ioctl_timeout},
597 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
598 autofs_dev_ioctl_requester},
599 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
600 autofs_dev_ioctl_expire},
601 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
602 autofs_dev_ioctl_askumount},
603 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
604 autofs_dev_ioctl_ismountpoint}
606 unsigned int idx = cmd_idx(cmd);
608 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
611 /* ioctl dispatcher */
612 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
614 struct autofs_dev_ioctl *param;
616 struct autofs_sb_info *sbi;
617 unsigned int cmd_first, cmd;
621 /* only root can play with this */
622 if (!capable(CAP_SYS_ADMIN))
625 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
626 cmd = _IOC_NR(command);
628 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
629 cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
633 /* Copy the parameters into kernel space. */
634 param = copy_dev_ioctl(user);
636 return PTR_ERR(param);
638 err = validate_dev_ioctl(command, param);
642 /* The validate routine above always sets the version */
643 if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
646 fn = lookup_dev_ioctl(cmd);
648 AUTOFS_WARN("unknown command 0x%08x", command);
656 * For obvious reasons the openmount can't have a file
657 * descriptor yet. We don't take a reference to the
658 * file during close to allow for immediate release.
660 if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
661 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
662 fp = fget(param->ioctlfd);
664 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
676 sbi = autofs_dev_ioctl_sbi(fp);
677 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
684 * Admin needs to be able to set the mount catatonic in
685 * order to be able to perform the re-open.
687 if (!autofs4_oz_mode(sbi) &&
688 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
695 err = fn(fp, sbi, param);
700 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
703 free_dev_ioctl(param);
707 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
710 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
715 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
717 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
720 #define autofs_dev_ioctl_compat NULL
723 static const struct file_operations _dev_ioctl_fops = {
724 .unlocked_ioctl = autofs_dev_ioctl,
725 .compat_ioctl = autofs_dev_ioctl_compat,
726 .owner = THIS_MODULE,
729 static struct miscdevice _autofs_dev_ioctl_misc = {
730 .minor = AUTOFS_MINOR,
731 .name = AUTOFS_DEVICE_NAME,
732 .fops = &_dev_ioctl_fops
735 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
736 MODULE_ALIAS("devname:autofs");
738 /* Register/deregister misc character device */
739 int autofs_dev_ioctl_init(void)
743 r = misc_register(&_autofs_dev_ioctl_misc);
745 AUTOFS_ERROR("misc_register failed for control device");
752 void autofs_dev_ioctl_exit(void)
754 misc_deregister(&_autofs_dev_ioctl_misc);