Loading...
Note: File does not exist in v6.2.
1/*
2 * Copyright 2008 Red Hat, Inc. All rights reserved.
3 * Copyright 2008 Ian Kent <raven@themaw.net>
4 *
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.
8 */
9
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>
26
27#include "autofs_i.h"
28
29/*
30 * This module implements an interface for routing autofs ioctl control
31 * commands via a miscellaneous device file.
32 *
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.
39 */
40
41#define AUTOFS_DEV_IOCTL_SIZE sizeof(struct autofs_dev_ioctl)
42
43typedef int (*ioctl_fn)(struct file *, struct autofs_sb_info *,
44 struct autofs_dev_ioctl *);
45
46static int check_name(const char *name)
47{
48 if (!strchr(name, '/'))
49 return -EINVAL;
50 return 0;
51}
52
53/*
54 * Check a string doesn't overrun the chunk of
55 * memory we copied from user land.
56 */
57static int invalid_str(char *str, size_t size)
58{
59 if (memchr(str, 0, size))
60 return 0;
61 return -EINVAL;
62}
63
64/*
65 * Check that the user compiled against correct version of autofs
66 * misc device code.
67 *
68 * As well as checking the version compatibility this always copies
69 * the kernel interface version out.
70 */
71static int check_dev_ioctl_version(int cmd, struct autofs_dev_ioctl *param)
72{
73 int err = 0;
74
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);
82 err = -EINVAL;
83 }
84
85 /* Fill in the kernel version. */
86 param->ver_major = AUTOFS_DEV_IOCTL_VERSION_MAJOR;
87 param->ver_minor = AUTOFS_DEV_IOCTL_VERSION_MINOR;
88
89 return err;
90}
91
92/*
93 * Copy parameter control struct, including a possible path allocated
94 * at the end of the struct.
95 */
96static struct autofs_dev_ioctl *
97 copy_dev_ioctl(struct autofs_dev_ioctl __user *in)
98{
99 struct autofs_dev_ioctl tmp, *res;
100
101 if (copy_from_user(&tmp, in, sizeof(tmp)))
102 return ERR_PTR(-EFAULT);
103
104 if (tmp.size < sizeof(tmp))
105 return ERR_PTR(-EINVAL);
106
107 if (tmp.size > (PATH_MAX + sizeof(tmp)))
108 return ERR_PTR(-ENAMETOOLONG);
109
110 res = memdup_user(in, tmp.size);
111 if (!IS_ERR(res))
112 res->size = tmp.size;
113
114 return res;
115}
116
117static inline void free_dev_ioctl(struct autofs_dev_ioctl *param)
118{
119 kfree(param);
120}
121
122/*
123 * Check sanity of parameter control fields and if a path is present
124 * check that it is terminated and contains at least one "/".
125 */
126static int validate_dev_ioctl(int cmd, struct autofs_dev_ioctl *param)
127{
128 int err;
129
130 err = check_dev_ioctl_version(cmd, param);
131 if (err) {
132 pr_warn("invalid device control module version "
133 "supplied for cmd(0x%08x)\n", cmd);
134 goto out;
135 }
136
137 if (param->size > sizeof(*param)) {
138 err = invalid_str(param->path, param->size - sizeof(*param));
139 if (err) {
140 pr_warn(
141 "path string terminator missing for cmd(0x%08x)\n",
142 cmd);
143 goto out;
144 }
145
146 err = check_name(param->path);
147 if (err) {
148 pr_warn("invalid path supplied for cmd(0x%08x)\n",
149 cmd);
150 goto out;
151 }
152 }
153
154 err = 0;
155out:
156 return err;
157}
158
159/*
160 * Get the autofs super block info struct from the file opened on
161 * the autofs mount point.
162 */
163static struct autofs_sb_info *autofs_dev_ioctl_sbi(struct file *f)
164{
165 struct autofs_sb_info *sbi = NULL;
166 struct inode *inode;
167
168 if (f) {
169 inode = file_inode(f);
170 sbi = autofs4_sbi(inode->i_sb);
171 }
172 return sbi;
173}
174
175/* Return autofs dev ioctl version */
176static int autofs_dev_ioctl_version(struct file *fp,
177 struct autofs_sb_info *sbi,
178 struct autofs_dev_ioctl *param)
179{
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;
183 return 0;
184}
185
186/* Return autofs module protocol version */
187static int autofs_dev_ioctl_protover(struct file *fp,
188 struct autofs_sb_info *sbi,
189 struct autofs_dev_ioctl *param)
190{
191 param->protover.version = sbi->version;
192 return 0;
193}
194
195/* Return autofs module protocol sub version */
196static int autofs_dev_ioctl_protosubver(struct file *fp,
197 struct autofs_sb_info *sbi,
198 struct autofs_dev_ioctl *param)
199{
200 param->protosubver.sub_version = sbi->sub_version;
201 return 0;
202}
203
204/* Find the topmost mount satisfying test() */
205static int find_autofs_mount(const char *pathname,
206 struct path *res,
207 int test(const struct path *path, void *data),
208 void *data)
209{
210 struct path path;
211 int err;
212
213 err = kern_path_mountpoint(AT_FDCWD, pathname, &path, 0);
214 if (err)
215 return err;
216 err = -ENOENT;
217 while (path.dentry == path.mnt->mnt_root) {
218 if (path.dentry->d_sb->s_magic == AUTOFS_SUPER_MAGIC) {
219 if (test(&path, data)) {
220 path_get(&path);
221 *res = path;
222 err = 0;
223 break;
224 }
225 }
226 if (!follow_up(&path))
227 break;
228 }
229 path_put(&path);
230 return err;
231}
232
233static int test_by_dev(const struct path *path, void *p)
234{
235 return path->dentry->d_sb->s_dev == *(dev_t *)p;
236}
237
238static int test_by_type(const struct path *path, void *p)
239{
240 struct autofs_info *ino = autofs4_dentry_ino(path->dentry);
241
242 return ino && ino->sbi->type & *(unsigned *)p;
243}
244
245/*
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)).
248 */
249static int autofs_dev_ioctl_open_mountpoint(const char *name, dev_t devid)
250{
251 int err, fd;
252
253 fd = get_unused_fd_flags(O_CLOEXEC);
254 if (likely(fd >= 0)) {
255 struct file *filp;
256 struct path path;
257
258 err = find_autofs_mount(name, &path, test_by_dev, &devid);
259 if (err)
260 goto out;
261
262 /*
263 * Find autofs super block that has the device number
264 * corresponding to the autofs fs we want to open.
265 */
266
267 filp = dentry_open(&path, O_RDONLY, current_cred());
268 path_put(&path);
269 if (IS_ERR(filp)) {
270 err = PTR_ERR(filp);
271 goto out;
272 }
273
274 fd_install(fd, filp);
275 }
276
277 return fd;
278
279out:
280 put_unused_fd(fd);
281 return err;
282}
283
284/* Open a file descriptor on an autofs mount point */
285static int autofs_dev_ioctl_openmount(struct file *fp,
286 struct autofs_sb_info *sbi,
287 struct autofs_dev_ioctl *param)
288{
289 const char *path;
290 dev_t devid;
291 int err, fd;
292
293 /* param->path has already been checked */
294 if (!param->openmount.devid)
295 return -EINVAL;
296
297 param->ioctlfd = -1;
298
299 path = param->path;
300 devid = new_decode_dev(param->openmount.devid);
301
302 err = 0;
303 fd = autofs_dev_ioctl_open_mountpoint(path, devid);
304 if (unlikely(fd < 0)) {
305 err = fd;
306 goto out;
307 }
308
309 param->ioctlfd = fd;
310out:
311 return err;
312}
313
314/* Close file descriptor allocated above (user can also use close(2)). */
315static int autofs_dev_ioctl_closemount(struct file *fp,
316 struct autofs_sb_info *sbi,
317 struct autofs_dev_ioctl *param)
318{
319 return sys_close(param->ioctlfd);
320}
321
322/*
323 * Send "ready" status for an existing wait (either a mount or an expire
324 * request).
325 */
326static int autofs_dev_ioctl_ready(struct file *fp,
327 struct autofs_sb_info *sbi,
328 struct autofs_dev_ioctl *param)
329{
330 autofs_wqt_t token;
331
332 token = (autofs_wqt_t) param->ready.token;
333 return autofs4_wait_release(sbi, token, 0);
334}
335
336/*
337 * Send "fail" status for an existing wait (either a mount or an expire
338 * request).
339 */
340static int autofs_dev_ioctl_fail(struct file *fp,
341 struct autofs_sb_info *sbi,
342 struct autofs_dev_ioctl *param)
343{
344 autofs_wqt_t token;
345 int status;
346
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);
350}
351
352/*
353 * Set the pipe fd for kernel communication to the daemon.
354 *
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.
360 *
361 * This also sets the process group id used to identify the
362 * controlling process (eg. the owning automount(8) daemon).
363 */
364static int autofs_dev_ioctl_setpipefd(struct file *fp,
365 struct autofs_sb_info *sbi,
366 struct autofs_dev_ioctl *param)
367{
368 int pipefd;
369 int err = 0;
370 struct pid *new_pid = NULL;
371
372 if (param->setpipefd.pipefd == -1)
373 return -EINVAL;
374
375 pipefd = param->setpipefd.pipefd;
376
377 mutex_lock(&sbi->wq_mutex);
378 if (!sbi->catatonic) {
379 mutex_unlock(&sbi->wq_mutex);
380 return -EBUSY;
381 } else {
382 struct file *pipe;
383
384 new_pid = get_task_pid(current, PIDTYPE_PGID);
385
386 if (ns_of_pid(new_pid) != ns_of_pid(sbi->oz_pgrp)) {
387 pr_warn("not allowed to change PID namespace\n");
388 err = -EINVAL;
389 goto out;
390 }
391
392 pipe = fget(pipefd);
393 if (!pipe) {
394 err = -EBADF;
395 goto out;
396 }
397 if (autofs_prepare_pipe(pipe) < 0) {
398 err = -EPIPE;
399 fput(pipe);
400 goto out;
401 }
402 swap(sbi->oz_pgrp, new_pid);
403 sbi->pipefd = pipefd;
404 sbi->pipe = pipe;
405 sbi->catatonic = 0;
406 }
407out:
408 put_pid(new_pid);
409 mutex_unlock(&sbi->wq_mutex);
410 return err;
411}
412
413/*
414 * Make the autofs mount point catatonic, no longer responsive to
415 * mount requests. Also closes the kernel pipe file descriptor.
416 */
417static int autofs_dev_ioctl_catatonic(struct file *fp,
418 struct autofs_sb_info *sbi,
419 struct autofs_dev_ioctl *param)
420{
421 autofs4_catatonic_mode(sbi);
422 return 0;
423}
424
425/* Set the autofs mount timeout */
426static int autofs_dev_ioctl_timeout(struct file *fp,
427 struct autofs_sb_info *sbi,
428 struct autofs_dev_ioctl *param)
429{
430 unsigned long timeout;
431
432 timeout = param->timeout.timeout;
433 param->timeout.timeout = sbi->exp_timeout / HZ;
434 sbi->exp_timeout = timeout * HZ;
435 return 0;
436}
437
438/*
439 * Return the uid and gid of the last request for the mount
440 *
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.
445 */
446static int autofs_dev_ioctl_requester(struct file *fp,
447 struct autofs_sb_info *sbi,
448 struct autofs_dev_ioctl *param)
449{
450 struct autofs_info *ino;
451 struct path path;
452 dev_t devid;
453 int err = -ENOENT;
454
455 if (param->size <= sizeof(*param)) {
456 err = -EINVAL;
457 goto out;
458 }
459
460 devid = sbi->sb->s_dev;
461
462 param->requester.uid = param->requester.gid = -1;
463
464 err = find_autofs_mount(param->path, &path, test_by_dev, &devid);
465 if (err)
466 goto out;
467
468 ino = autofs4_dentry_ino(path.dentry);
469 if (ino) {
470 err = 0;
471 autofs4_expire_wait(&path, 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);
478 }
479 path_put(&path);
480out:
481 return err;
482}
483
484/*
485 * Call repeatedly until it returns -EAGAIN, meaning there's nothing
486 * more that can be done.
487 */
488static int autofs_dev_ioctl_expire(struct file *fp,
489 struct autofs_sb_info *sbi,
490 struct autofs_dev_ioctl *param)
491{
492 struct vfsmount *mnt;
493 int how;
494
495 how = param->expire.how;
496 mnt = fp->f_path.mnt;
497
498 return autofs4_do_expire_multi(sbi->sb, mnt, sbi, how);
499}
500
501/* Check if autofs mount point is in use */
502static int autofs_dev_ioctl_askumount(struct file *fp,
503 struct autofs_sb_info *sbi,
504 struct autofs_dev_ioctl *param)
505{
506 param->askumount.may_umount = 0;
507 if (may_umount(fp->f_path.mnt))
508 param->askumount.may_umount = 1;
509 return 0;
510}
511
512/*
513 * Check if the given path is a mountpoint.
514 *
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.
522 *
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.
529 *
530 * In both cases the the device number (as returned by
531 * new_encode_dev()) is also returned.
532 */
533static int autofs_dev_ioctl_ismountpoint(struct file *fp,
534 struct autofs_sb_info *sbi,
535 struct autofs_dev_ioctl *param)
536{
537 struct path path;
538 const char *name;
539 unsigned int type;
540 unsigned int devid, magic;
541 int err = -ENOENT;
542
543 if (param->size <= sizeof(*param)) {
544 err = -EINVAL;
545 goto out;
546 }
547
548 name = param->path;
549 type = param->ismountpoint.in.type;
550
551 param->ismountpoint.out.devid = devid = 0;
552 param->ismountpoint.out.magic = magic = 0;
553
554 if (!fp || param->ioctlfd == -1) {
555 if (autofs_type_any(type))
556 err = kern_path_mountpoint(AT_FDCWD,
557 name, &path, LOOKUP_FOLLOW);
558 else
559 err = find_autofs_mount(name, &path,
560 test_by_type, &type);
561 if (err)
562 goto out;
563 devid = new_encode_dev(path.dentry->d_sb->s_dev);
564 err = 0;
565 if (path.mnt->mnt_root == path.dentry) {
566 err = 1;
567 magic = path.dentry->d_sb->s_magic;
568 }
569 } else {
570 dev_t dev = sbi->sb->s_dev;
571
572 err = find_autofs_mount(name, &path, test_by_dev, &dev);
573 if (err)
574 goto out;
575
576 devid = new_encode_dev(dev);
577
578 err = path_has_submounts(&path);
579
580 if (follow_down_one(&path))
581 magic = path.dentry->d_sb->s_magic;
582 }
583
584 param->ismountpoint.out.devid = devid;
585 param->ismountpoint.out.magic = magic;
586 path_put(&path);
587out:
588 return err;
589}
590
591/*
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
594 * lookup.
595 */
596#define cmd_idx(cmd) (cmd - _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST))
597
598static ioctl_fn lookup_dev_ioctl(unsigned int cmd)
599{
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,
615 };
616 unsigned int idx = cmd_idx(cmd);
617
618 return (idx >= ARRAY_SIZE(_ioctls)) ? NULL : _ioctls[idx];
619}
620
621/* ioctl dispatcher */
622static int _autofs_dev_ioctl(unsigned int command,
623 struct autofs_dev_ioctl __user *user)
624{
625 struct autofs_dev_ioctl *param;
626 struct file *fp;
627 struct autofs_sb_info *sbi;
628 unsigned int cmd_first, cmd;
629 ioctl_fn fn = NULL;
630 int err = 0;
631
632 /* only root can play with this */
633 if (!capable(CAP_SYS_ADMIN))
634 return -EPERM;
635
636 cmd_first = _IOC_NR(AUTOFS_DEV_IOCTL_IOC_FIRST);
637 cmd = _IOC_NR(command);
638
639 if (_IOC_TYPE(command) != _IOC_TYPE(AUTOFS_DEV_IOCTL_IOC_FIRST) ||
640 cmd - cmd_first > AUTOFS_DEV_IOCTL_IOC_COUNT) {
641 return -ENOTTY;
642 }
643
644 /* Copy the parameters into kernel space. */
645 param = copy_dev_ioctl(user);
646 if (IS_ERR(param))
647 return PTR_ERR(param);
648
649 err = validate_dev_ioctl(command, param);
650 if (err)
651 goto out;
652
653 fn = lookup_dev_ioctl(cmd);
654 if (!fn) {
655 pr_warn("unknown command 0x%08x\n", command);
656 err = -ENOTTY;
657 goto out;
658 }
659
660 fp = NULL;
661 sbi = NULL;
662
663 /*
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.
668 */
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);
673 if (!fp) {
674 if (cmd == AUTOFS_DEV_IOCTL_ISMOUNTPOINT_CMD)
675 goto cont;
676 err = -EBADF;
677 goto out;
678 }
679
680 sbi = autofs_dev_ioctl_sbi(fp);
681 if (!sbi || sbi->magic != AUTOFS_SBI_MAGIC) {
682 err = -EINVAL;
683 fput(fp);
684 goto out;
685 }
686
687 /*
688 * Admin needs to be able to set the mount catatonic in
689 * order to be able to perform the re-open.
690 */
691 if (!autofs4_oz_mode(sbi) &&
692 cmd != AUTOFS_DEV_IOCTL_CATATONIC_CMD) {
693 err = -EACCES;
694 fput(fp);
695 goto out;
696 }
697 }
698cont:
699 err = fn(fp, sbi, param);
700
701 if (fp)
702 fput(fp);
703 if (err >= 0 && copy_to_user(user, param, AUTOFS_DEV_IOCTL_SIZE))
704 err = -EFAULT;
705out:
706 free_dev_ioctl(param);
707 return err;
708}
709
710static long autofs_dev_ioctl(struct file *file, uint command, ulong u)
711{
712 int err;
713
714 err = _autofs_dev_ioctl(command, (struct autofs_dev_ioctl __user *) u);
715 return (long) err;
716}
717
718#ifdef CONFIG_COMPAT
719static long autofs_dev_ioctl_compat(struct file *file, uint command, ulong u)
720{
721 return (long) autofs_dev_ioctl(file, command, (ulong) compat_ptr(u));
722}
723#else
724#define autofs_dev_ioctl_compat NULL
725#endif
726
727static 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,
732};
733
734static struct miscdevice _autofs_dev_ioctl_misc = {
735 .minor = AUTOFS_MINOR,
736 .name = AUTOFS_DEVICE_NAME,
737 .fops = &_dev_ioctl_fops
738};
739
740MODULE_ALIAS_MISCDEV(AUTOFS_MINOR);
741MODULE_ALIAS("devname:autofs");
742
743/* Register/deregister misc character device */
744int __init autofs_dev_ioctl_init(void)
745{
746 int r;
747
748 r = misc_register(&_autofs_dev_ioctl_misc);
749 if (r) {
750 pr_err("misc_register failed for control device\n");
751 return r;
752 }
753
754 return 0;
755}
756
757void autofs_dev_ioctl_exit(void)
758{
759 misc_deregister(&_autofs_dev_ioctl_misc);
760}