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 if (tmp.size > (PATH_MAX + sizeof(tmp)))
107 return ERR_PTR(-ENAMETOOLONG);
109 return memdup_user(in, tmp.size);
112 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
119 * Check sanity of parameter control fields and if a path is present
120 * check that it is terminated and contains at least one "/".
122 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
126 err = check_dev_ioctl_version(cmd, param);
128 AUTOFS_WARN("invalid device control module version "
129 "supplied for cmd(0x%08x)", cmd);
133 if (param->size > sizeof(*param)) {
134 err = invalid_str(param->path, param->size - sizeof(*param));
137 "path string terminator missing for cmd(0x%08x)",
142 err = check_name(param->path);
144 AUTOFS_WARN("invalid path supplied for cmd(0x%08x)",
156 * Get the autofs super block info struct from the file opened on
157 * the autofs mount point.
159 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
161 struct autofs_sb_info *sbi = NULL;
165 inode = f->f_path.dentry->d_inode;
166 sbi = autofs4_sbi(inode->i_sb);
171 /* Return autofs module protocol version */
172 static int autofs_dev_ioctl_protover(struct file *fp,
173 struct autofs_sb_info *sbi,
174 struct autofs_dev_ioctl *param)
176 param->protover.version = sbi->version;
180 /* Return autofs module protocol sub version */
181 static int autofs_dev_ioctl_protosubver(struct file *fp,
182 struct autofs_sb_info *sbi,
183 struct autofs_dev_ioctl *param)
185 param->protosubver.sub_version = sbi->sub_version;
189 static int find_autofs_mount(const char *pathname,
191 int test(struct path *path, void *data),
195 int err = kern_path(pathname, 0, &path);
199 while (path.dentry == path.mnt->mnt_root) {
200 if (path.mnt->mnt_sb->s_magic == AUTOFS_SUPER_MAGIC) {
201 if (test(&path, data)) {
203 if (!err) /* already found some */
209 if (!follow_up(&path))
216 static int test_by_dev(struct path *path, void *p)
218 return path->mnt->mnt_sb->s_dev == *(dev_t *)p;
221 static int test_by_type(struct path *path, void *p)
223 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
224 return ino && ino->sbi->type & *(unsigned *)p;
227 static void autofs_dev_ioctl_fd_install(unsigned int fd, struct file *file)
229 struct files_struct *files = current->files;
232 spin_lock(&files->file_lock);
233 fdt = files_fdtable(files);
234 BUG_ON(fdt->fd[fd] != NULL);
235 rcu_assign_pointer(fdt->fd[fd], file);
236 FD_SET(fd, fdt->close_on_exec);
237 spin_unlock(&files->file_lock);
242 * Open a file descriptor on the autofs mount point corresponding
243 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
245 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
249 fd = get_unused_fd();
250 if (likely(fd >= 0)) {
254 err = find_autofs_mount(name, &path, test_by_dev, &devid);
259 * Find autofs super block that has the device number
260 * corresponding to the autofs fs we want to open.
263 filp = dentry_open(path.dentry, path.mnt, O_RDONLY,
270 autofs_dev_ioctl_fd_install(fd, filp);
280 /* Open a file descriptor on an autofs mount point */
281 static int autofs_dev_ioctl_openmount(struct file *fp,
282 struct autofs_sb_info *sbi,
283 struct autofs_dev_ioctl *param)
289 /* param->path has already been checked */
290 if (!param->openmount.devid)
296 devid = new_decode_dev(param->openmount.devid);
299 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
300 if (unlikely(fd < 0)) {
310 /* Close file descriptor allocated above (user can also use close(2)). */
311 static int autofs_dev_ioctl_closemount(struct file *fp,
312 struct autofs_sb_info *sbi,
313 struct autofs_dev_ioctl *param)
315 return sys_close(param->ioctlfd);
319 * Send "ready" status for an existing wait (either a mount or an expire
322 static int autofs_dev_ioctl_ready(struct file *fp,
323 struct autofs_sb_info *sbi,
324 struct autofs_dev_ioctl *param)
328 token = (autofs_wqt_t) param->ready.token;
329 return autofs4_wait_release(sbi, token, 0);
333 * Send "fail" status for an existing wait (either a mount or an expire
336 static int autofs_dev_ioctl_fail(struct file *fp,
337 struct autofs_sb_info *sbi,
338 struct autofs_dev_ioctl *param)
343 token = (autofs_wqt_t) param->fail.token;
344 status = param->fail.status ? param->fail.status : -ENOENT;
345 return autofs4_wait_release(sbi, token, status);
349 * Set the pipe fd for kernel communication to the daemon.
351 * Normally this is set at mount using an option but if we
352 * are reconnecting to a busy mount then we need to use this
353 * to tell the autofs mount about the new kernel pipe fd. In
354 * order to protect mounts against incorrectly setting the
355 * pipefd we also require that the autofs mount be catatonic.
357 * This also sets the process group id used to identify the
358 * controlling process (eg. the owning automount(8) daemon).
360 static int autofs_dev_ioctl_setpipefd(struct file *fp,
361 struct autofs_sb_info *sbi,
362 struct autofs_dev_ioctl *param)
367 if (param->setpipefd.pipefd == -1)
370 pipefd = param->setpipefd.pipefd;
372 mutex_lock(&sbi->wq_mutex);
373 if (!sbi->catatonic) {
374 mutex_unlock(&sbi->wq_mutex);
377 struct file *pipe = fget(pipefd);
382 if (autofs_prepare_pipe(pipe) < 0) {
387 sbi->oz_pgrp = task_pgrp_nr(current);
388 sbi->pipefd = pipefd;
393 mutex_unlock(&sbi->wq_mutex);
398 * Make the autofs mount point catatonic, no longer responsive to
399 * mount requests. Also closes the kernel pipe file descriptor.
401 static int autofs_dev_ioctl_catatonic(struct file *fp,
402 struct autofs_sb_info *sbi,
403 struct autofs_dev_ioctl *param)
405 autofs4_catatonic_mode(sbi);
409 /* Set the autofs mount timeout */
410 static int autofs_dev_ioctl_timeout(struct file *fp,
411 struct autofs_sb_info *sbi,
412 struct autofs_dev_ioctl *param)
414 unsigned long timeout;
416 timeout = param->timeout.timeout;
417 param->timeout.timeout = sbi->exp_timeout / HZ;
418 sbi->exp_timeout = timeout * HZ;
423 * Return the uid and gid of the last request for the mount
425 * When reconstructing an autofs mount tree with active mounts
426 * we need to re-connect to mounts that may have used the original
427 * process uid and gid (or string variations of them) for mount
428 * lookups within the map entry.
430 static int autofs_dev_ioctl_requester(struct file *fp,
431 struct autofs_sb_info *sbi,
432 struct autofs_dev_ioctl *param)
434 struct autofs_info *ino;
439 if (param->size <= sizeof(*param)) {
444 devid = sbi->sb->s_dev;
446 param->requester.uid = param->requester.gid = -1;
448 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
452 ino = autofs4_dentry_ino(path.dentry);
455 autofs4_expire_wait(path.dentry);
456 spin_lock(&sbi->fs_lock);
457 param->requester.uid = ino->uid;
458 param->requester.gid = ino->gid;
459 spin_unlock(&sbi->fs_lock);
467 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
468 * more that can be done.
470 static int autofs_dev_ioctl_expire(struct file *fp,
471 struct autofs_sb_info *sbi,
472 struct autofs_dev_ioctl *param)
474 struct vfsmount *mnt;
477 how = param->expire.how;
478 mnt = fp->f_path.mnt;
480 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
483 /* Check if autofs mount point is in use */
484 static int autofs_dev_ioctl_askumount(struct file *fp,
485 struct autofs_sb_info *sbi,
486 struct autofs_dev_ioctl *param)
488 param->askumount.may_umount = 0;
489 if (may_umount(fp->f_path.mnt))
490 param->askumount.may_umount = 1;
495 * Check if the given path is a mountpoint.
497 * If we are supplied with the file descriptor of an autofs
498 * mount we're looking for a specific mount. In this case
499 * the path is considered a mountpoint if it is itself a
500 * mountpoint or contains a mount, such as a multi-mount
501 * without a root mount. In this case we return 1 if the
502 * path is a mount point and the super magic of the covering
503 * mount if there is one or 0 if it isn't a mountpoint.
505 * If we aren't supplied with a file descriptor then we
506 * lookup the nameidata of the path and check if it is the
507 * root of a mount. If a type is given we are looking for
508 * a particular autofs mount and if we don't find a match
509 * we return fail. If the located nameidata path is the
510 * root of a mount we return 1 along with the super magic
511 * of the mount or 0 otherwise.
513 * In both cases the the device number (as returned by
514 * new_encode_dev()) is also returned.
516 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
517 struct autofs_sb_info *sbi,
518 struct autofs_dev_ioctl *param)
523 unsigned int devid, magic;
526 if (param->size <= sizeof(*param)) {
532 type = param->ismountpoint.in.type;
534 param->ismountpoint.out.devid = devid = 0;
535 param->ismountpoint.out.magic = magic = 0;
537 if (!fp || param->ioctlfd == -1) {
538 if (autofs_type_any(type))
539 err = kern_path(name, LOOKUP_FOLLOW, &path);
541 err = find_autofs_mount(name, &path, test_by_type, &type);
544 devid = new_encode_dev(path.mnt->mnt_sb->s_dev);
546 if (path.mnt->mnt_root == path.dentry) {
548 magic = path.mnt->mnt_sb->s_magic;
551 dev_t dev = sbi->sb->s_dev;
553 err = find_autofs_mount(name, &path, test_by_dev, &dev);
557 devid = new_encode_dev(dev);
559 err = have_submounts(path.dentry);
561 if (follow_down_one(&path))
562 magic = path.mnt->mnt_sb->s_magic;
565 param->ismountpoint.out.devid = devid;
566 param->ismountpoint.out.magic = magic;
573 * Our range of ioctl numbers isn't 0 based so we need to shift
574 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
577 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
579 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
585 {cmd_idx(AUTOFS_DEV_IOCTL_VERSION_CMD), NULL},
586 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOVER_CMD),
587 autofs_dev_ioctl_protover},
588 {cmd_idx(AUTOFS_DEV_IOCTL_PROTOSUBVER_CMD),
589 autofs_dev_ioctl_protosubver},
590 {cmd_idx(AUTOFS_DEV_IOCTL_OPENMOUNT_CMD),
591 autofs_dev_ioctl_openmount},
592 {cmd_idx(AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD),
593 autofs_dev_ioctl_closemount},
594 {cmd_idx(AUTOFS_DEV_IOCTL_READY_CMD),
595 autofs_dev_ioctl_ready},
596 {cmd_idx(AUTOFS_DEV_IOCTL_FAIL_CMD),
597 autofs_dev_ioctl_fail},
598 {cmd_idx(AUTOFS_DEV_IOCTL_SETPIPEFD_CMD),
599 autofs_dev_ioctl_setpipefd},
600 {cmd_idx(AUTOFS_DEV_IOCTL_CATATONIC_CMD),
601 autofs_dev_ioctl_catatonic},
602 {cmd_idx(AUTOFS_DEV_IOCTL_TIMEOUT_CMD),
603 autofs_dev_ioctl_timeout},
604 {cmd_idx(AUTOFS_DEV_IOCTL_REQUESTER_CMD),
605 autofs_dev_ioctl_requester},
606 {cmd_idx(AUTOFS_DEV_IOCTL_EXPIRE_CMD),
607 autofs_dev_ioctl_expire},
608 {cmd_idx(AUTOFS_DEV_IOCTL_ASKUMOUNT_CMD),
609 autofs_dev_ioctl_askumount},
610 {cmd_idx(AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD),
611 autofs_dev_ioctl_ismountpoint}
613 unsigned int idx = cmd_idx(cmd);
615 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx].fn;
618 /* ioctl dispatcher */
619 static int _autofs_dev_ioctl(unsigned int command, struct autofs_dev_ioctl __user *user)
621 struct autofs_dev_ioctl *param;
623 struct autofs_sb_info *sbi;
624 unsigned int cmd_first, cmd;
628 /* only root can play with this */
629 if (!capable(CAP_SYS_ADMIN))
632 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
633 cmd = _IOC_NR(command);
635 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
636 cmd - cmd_first >= AUTOFS_DEV_IOCTL_IOC_COUNT) {
640 /* Copy the parameters into kernel space. */
641 param = copy_dev_ioctl(user);
643 return PTR_ERR(param);
645 err = validate_dev_ioctl(command, param);
649 /* The validate routine above always sets the version */
650 if (cmd == AUTOFS_DEV_IOCTL_VERSION_CMD)
653 fn = lookup_dev_ioctl(cmd);
655 AUTOFS_WARN("unknown command 0x%08x", command);
663 * For obvious reasons the openmount can't have a file
664 * descriptor yet. We don't take a reference to the
665 * file during close to allow for immediate release.
667 if (cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
668 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
669 fp = fget(param->ioctlfd);
671 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
683 sbi = autofs_dev_ioctl_sbi(fp);
684 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
691 * Admin needs to be able to set the mount catatonic in
692 * order to be able to perform the re-open.
694 if (!autofs4_oz_mode(sbi) &&
695 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
702 err = fn(fp, sbi, param);
707 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
710 free_dev_ioctl(param);
714 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
717 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
722 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
724 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
727 #define autofs_dev_ioctl_compat NULL
730 static const struct file_operations _dev_ioctl_fops = {
731 .unlocked_ioctl = autofs_dev_ioctl,
732 .compat_ioctl = autofs_dev_ioctl_compat,
733 .owner = THIS_MODULE,
734 .llseek = noop_llseek,
737 static struct miscdevice _autofs_dev_ioctl_misc = {
738 .minor = AUTOFS_MINOR,
739 .name = AUTOFS_DEVICE_NAME,
740 .fops = &_dev_ioctl_fops
743 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
744 MODULE_ALIAS("devname:autofs");
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);