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 ((param->ver_major != AUTOFS_DEV_IOCTL_VERSION_MAJOR) ||
76 (param->ver_minor > AUTOFS_DEV_IOCTL_VERSION_MINOR)) {
77 pr_warn("ioctl control interface version mismatch: "
78 "kernel(%u.%u), user(%u.%u), cmd(0x%08x)\n",
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 *
97 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
99 struct autofs_dev_ioctl tmp, *res;
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 if (tmp.size > (PATH_MAX + sizeof(tmp)))
108 return ERR_PTR(-ENAMETOOLONG);
110 res = memdup_user(in, tmp.size);
112 res->size = tmp.size;
117 static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
123 * Check sanity of parameter control fields and if a path is present
124 * check that it is terminated and contains at least one "/".
126 static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
130 err = check_dev_ioctl_version(cmd, param);
132 pr_warn("invalid device control module version "
133 "supplied for cmd(0x%08x)\n", cmd);
137 if (param->size > sizeof(*param)) {
138 err = invalid_str(param->path, param->size - sizeof(*param));
141 "path string terminator missing for cmd(0x%08x)\n",
146 err = check_name(param->path);
148 pr_warn("invalid path supplied for cmd(0x%08x)\n",
160 * Get the autofs super block info struct from the file opened on
161 * the autofs mount point.
163 static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
165 struct autofs_sb_info *sbi = NULL;
169 inode = file_inode(f);
170 sbi = autofs4_sbi(inode->i_sb);
175 /* Return autofs dev ioctl version */
176 static int autofs_dev_ioctl_version(struct file *fp,
177 struct autofs_sb_info *sbi,
178 struct autofs_dev_ioctl *param)
180 /* This should have already been set. */
181 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
182 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
186 /* Return autofs module protocol version */
187 static int autofs_dev_ioctl_protover(struct file *fp,
188 struct autofs_sb_info *sbi,
189 struct autofs_dev_ioctl *param)
191 param->protover.version = sbi->version;
195 /* Return autofs module protocol sub version */
196 static int autofs_dev_ioctl_protosubver(struct file *fp,
197 struct autofs_sb_info *sbi,
198 struct autofs_dev_ioctl *param)
200 param->protosubver.sub_version = sbi->sub_version;
204 /* Find the topmost mount satisfying test() */
205 static int find_autofs_mount(const char *pathname,
207 int test(struct path *path, void *data),
213 err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
217 while (path.dentry == path.mnt->mnt_root) {
218 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
219 if (test(&path, data)) {
226 if (!follow_up(&path))
233 static int test_by_dev(struct path *path, void *p)
235 return path->dentry->d_sb->s_dev == *(dev_t *)p;
238 static int test_by_type(struct path *path, void *p)
240 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
242 return ino && ino->sbi->type & *(unsigned *)p;
246 * Open a file descriptor on the autofs mount point corresponding
247 * to the given path and device number (aka. new_encode_dev(sb->s_dev)).
249 static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
253 fd = get_unused_fd_flags(O_CLOEXEC);
254 if (likely(fd >= 0)) {
258 err = find_autofs_mount(name, &path, test_by_dev, &devid);
263 * Find autofs super block that has the device number
264 * corresponding to the autofs fs we want to open.
267 filp = dentry_open(&path, O_RDONLY, current_cred());
274 fd_install(fd, filp);
284 /* Open a file descriptor on an autofs mount point */
285 static int autofs_dev_ioctl_openmount(struct file *fp,
286 struct autofs_sb_info *sbi,
287 struct autofs_dev_ioctl *param)
293 /* param->path has already been checked */
294 if (!param->openmount.devid)
300 devid = new_decode_dev(param->openmount.devid);
303 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
304 if (unlikely(fd < 0)) {
314 /* Close file descriptor allocated above (user can also use close(2)). */
315 static int autofs_dev_ioctl_closemount(struct file *fp,
316 struct autofs_sb_info *sbi,
317 struct autofs_dev_ioctl *param)
319 return sys_close(param->ioctlfd);
323 * Send "ready" status for an existing wait (either a mount or an expire
326 static int autofs_dev_ioctl_ready(struct file *fp,
327 struct autofs_sb_info *sbi,
328 struct autofs_dev_ioctl *param)
332 token = (autofs_wqt_t) param->ready.token;
333 return autofs4_wait_release(sbi, token, 0);
337 * Send "fail" status for an existing wait (either a mount or an expire
340 static int autofs_dev_ioctl_fail(struct file *fp,
341 struct autofs_sb_info *sbi,
342 struct autofs_dev_ioctl *param)
347 token = (autofs_wqt_t) param->fail.token;
348 status = param->fail.status ? param->fail.status : -ENOENT;
349 return autofs4_wait_release(sbi, token, status);
353 * Set the pipe fd for kernel communication to the daemon.
355 * Normally this is set at mount using an option but if we
356 * are reconnecting to a busy mount then we need to use this
357 * to tell the autofs mount about the new kernel pipe fd. In
358 * order to protect mounts against incorrectly setting the
359 * pipefd we also require that the autofs mount be catatonic.
361 * This also sets the process group id used to identify the
362 * controlling process (eg. the owning automount(8) daemon).
364 static int autofs_dev_ioctl_setpipefd(struct file *fp,
365 struct autofs_sb_info *sbi,
366 struct autofs_dev_ioctl *param)
370 struct pid *new_pid = NULL;
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);
384 new_pid = get_task_pid(current, PIDTYPE_PGID);
386 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
387 pr_warn("not allowed to change PID namespace\n");
397 if (autofs_prepare_pipe(pipe) < 0) {
402 swap(sbi->oz_pgrp, new_pid);
403 sbi->pipefd = pipefd;
409 mutex_unlock(&sbi->wq_mutex);
414 * Make the autofs mount point catatonic, no longer responsive to
415 * mount requests. Also closes the kernel pipe file descriptor.
417 static int autofs_dev_ioctl_catatonic(struct file *fp,
418 struct autofs_sb_info *sbi,
419 struct autofs_dev_ioctl *param)
421 autofs4_catatonic_mode(sbi);
425 /* Set the autofs mount timeout */
426 static int autofs_dev_ioctl_timeout(struct file *fp,
427 struct autofs_sb_info *sbi,
428 struct autofs_dev_ioctl *param)
430 unsigned long timeout;
432 timeout = param->timeout.timeout;
433 param->timeout.timeout = sbi->exp_timeout / HZ;
434 sbi->exp_timeout = timeout * HZ;
439 * Return the uid and gid of the last request for the mount
441 * When reconstructing an autofs mount tree with active mounts
442 * we need to re-connect to mounts that may have used the original
443 * process uid and gid (or string variations of them) for mount
444 * lookups within the map entry.
446 static int autofs_dev_ioctl_requester(struct file *fp,
447 struct autofs_sb_info *sbi,
448 struct autofs_dev_ioctl *param)
450 struct autofs_info *ino;
455 if (param->size <= sizeof(*param)) {
460 devid = sbi->sb->s_dev;
462 param->requester.uid = param->requester.gid = -1;
464 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
468 ino = autofs4_dentry_ino(path.dentry);
471 autofs4_expire_wait(path.dentry, 0);
472 spin_lock(&sbi->fs_lock);
473 param->requester.uid =
474 from_kuid_munged(current_user_ns(), ino->uid);
475 param->requester.gid =
476 from_kgid_munged(current_user_ns(), ino->gid);
477 spin_unlock(&sbi->fs_lock);
485 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
486 * more that can be done.
488 static int autofs_dev_ioctl_expire(struct file *fp,
489 struct autofs_sb_info *sbi,
490 struct autofs_dev_ioctl *param)
492 struct vfsmount *mnt;
495 how = param->expire.how;
496 mnt = fp->f_path.mnt;
498 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
501 /* Check if autofs mount point is in use */
502 static int autofs_dev_ioctl_askumount(struct file *fp,
503 struct autofs_sb_info *sbi,
504 struct autofs_dev_ioctl *param)
506 param->askumount.may_umount = 0;
507 if (may_umount(fp->f_path.mnt))
508 param->askumount.may_umount = 1;
513 * Check if the given path is a mountpoint.
515 * If we are supplied with the file descriptor of an autofs
516 * mount we're looking for a specific mount. In this case
517 * the path is considered a mountpoint if it is itself a
518 * mountpoint or contains a mount, such as a multi-mount
519 * without a root mount. In this case we return 1 if the
520 * path is a mount point and the super magic of the covering
521 * mount if there is one or 0 if it isn't a mountpoint.
523 * If we aren't supplied with a file descriptor then we
524 * lookup the path and check if it is the root of a mount.
525 * If a type is given we are looking for a particular autofs
526 * mount and if we don't find a match we return fail. If the
527 * located path is the root of a mount we return 1 along with
528 * the super magic of the mount or 0 otherwise.
530 * In both cases the the device number (as returned by
531 * new_encode_dev()) is also returned.
533 static int autofs_dev_ioctl_ismountpoint(struct file *fp,
534 struct autofs_sb_info *sbi,
535 struct autofs_dev_ioctl *param)
540 unsigned int devid, magic;
543 if (param->size <= sizeof(*param)) {
549 type = param->ismountpoint.in.type;
551 param->ismountpoint.out.devid = devid = 0;
552 param->ismountpoint.out.magic = magic = 0;
554 if (!fp || param->ioctlfd == -1) {
555 if (autofs_type_any(type))
556 err = kern_path_mountpoint(AT_FDCWD,
557 name, &path, LOOKUP_FOLLOW);
559 err = find_autofs_mount(name, &path,
560 test_by_type, &type);
563 devid = new_encode_dev(path.dentry->d_sb->s_dev);
565 if (path.mnt->mnt_root == path.dentry) {
567 magic = path.dentry->d_sb->s_magic;
570 dev_t dev = sbi->sb->s_dev;
572 err = find_autofs_mount(name, &path, test_by_dev, &dev);
576 devid = new_encode_dev(dev);
578 err = have_submounts(path.dentry);
580 if (follow_down_one(&path))
581 magic = path.dentry->d_sb->s_magic;
584 param->ismountpoint.out.devid = devid;
585 param->ismountpoint.out.magic = magic;
592 * Our range of ioctl numbers isn't 0 based so we need to shift
593 * the array index by _IOC_NR(AUTOFS_CTL_IOC_FIRST) for the table
596 #define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
598 static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
600 static ioctl_fn _ioctls[] = {
601 autofs_dev_ioctl_version,
602 autofs_dev_ioctl_protover,
603 autofs_dev_ioctl_protosubver,
604 autofs_dev_ioctl_openmount,
605 autofs_dev_ioctl_closemount,
606 autofs_dev_ioctl_ready,
607 autofs_dev_ioctl_fail,
608 autofs_dev_ioctl_setpipefd,
609 autofs_dev_ioctl_catatonic,
610 autofs_dev_ioctl_timeout,
611 autofs_dev_ioctl_requester,
612 autofs_dev_ioctl_expire,
613 autofs_dev_ioctl_askumount,
614 autofs_dev_ioctl_ismountpoint,
616 unsigned int idx = cmd_idx(cmd);
618 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
621 /* ioctl dispatcher */
622 static int _autofs_dev_ioctl(unsigned int command,
623 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 fn = lookup_dev_ioctl(cmd);
655 pr_warn("unknown command 0x%08x\n", command);
664 * For obvious reasons the openmount can't have a file
665 * descriptor yet. We don't take a reference to the
666 * file during close to allow for immediate release,
667 * and the same for retrieving ioctl version.
669 if (cmd != AUTOFS_DEV_IOCTL_VERSION_CMD &&
670 cmd != AUTOFS_DEV_IOCTL_OPENMOUNT_CMD &&
671 cmd != AUTOFS_DEV_IOCTL_CLOSEMOUNT_CMD) {
672 fp = fget(param->ioctlfd);
674 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
680 sbi = autofs_dev_ioctl_sbi(fp);
681 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
688 * Admin needs to be able to set the mount catatonic in
689 * order to be able to perform the re-open.
691 if (!autofs4_oz_mode(sbi) &&
692 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
699 err = fn(fp, sbi, param);
703 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
706 free_dev_ioctl(param);
710 static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
714 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
719 static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
721 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
724 #define autofs_dev_ioctl_compat NULL
727 static const struct file_operations _dev_ioctl_fops = {
728 .unlocked_ioctl = autofs_dev_ioctl,
729 .compat_ioctl = autofs_dev_ioctl_compat,
730 .owner = THIS_MODULE,
731 .llseek = noop_llseek,
734 static struct miscdevice _autofs_dev_ioctl_misc = {
735 .minor = AUTOFS_MINOR,
736 .name = AUTOFS_DEVICE_NAME,
737 .fops = &_dev_ioctl_fops
740 MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
741 MODULE_ALIAS("devname:autofs");
743 /* Register/deregister misc character device */
744 int __init autofs_dev_ioctl_init(void)
748 r = misc_register(&_autofs_dev_ioctl_misc);
750 pr_err("misc_register failed for control device\n");
757 void autofs_dev_ioctl_exit(void)
759 misc_deregister(&_autofs_dev_ioctl_misc);