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1/* SPDX-License-Identifier: GPL-2.0 */
2
3#include <linux/compiler_types.h>
4#include <linux/errno.h>
5#include <linux/fs.h>
6#include <linux/fsnotify.h>
7#include <linux/gfp.h>
8#include <linux/idr.h>
9#include <linux/init.h>
10#include <linux/ipc_namespace.h>
11#include <linux/kdev_t.h>
12#include <linux/kernel.h>
13#include <linux/list.h>
14#include <linux/namei.h>
15#include <linux/magic.h>
16#include <linux/major.h>
17#include <linux/miscdevice.h>
18#include <linux/module.h>
19#include <linux/mutex.h>
20#include <linux/mount.h>
21#include <linux/parser.h>
22#include <linux/radix-tree.h>
23#include <linux/sched.h>
24#include <linux/seq_file.h>
25#include <linux/slab.h>
26#include <linux/spinlock_types.h>
27#include <linux/stddef.h>
28#include <linux/string.h>
29#include <linux/types.h>
30#include <linux/uaccess.h>
31#include <linux/user_namespace.h>
32#include <linux/xarray.h>
33#include <uapi/asm-generic/errno-base.h>
34#include <uapi/linux/android/binder.h>
35#include <uapi/linux/android/binderfs.h>
36
37#include "binder_internal.h"
38
39#define FIRST_INODE 1
40#define SECOND_INODE 2
41#define INODE_OFFSET 3
42#define INTSTRLEN 21
43#define BINDERFS_MAX_MINOR (1U << MINORBITS)
44/* Ensure that the initial ipc namespace always has devices available. */
45#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
46
47static dev_t binderfs_dev;
48static DEFINE_MUTEX(binderfs_minors_mutex);
49static DEFINE_IDA(binderfs_minors);
50
51enum {
52 Opt_max,
53 Opt_stats_mode,
54 Opt_err
55};
56
57enum binderfs_stats_mode {
58 STATS_NONE,
59 STATS_GLOBAL,
60};
61
62static const match_table_t tokens = {
63 { Opt_max, "max=%d" },
64 { Opt_stats_mode, "stats=%s" },
65 { Opt_err, NULL }
66};
67
68static inline struct binderfs_info *BINDERFS_I(const struct inode *inode)
69{
70 return inode->i_sb->s_fs_info;
71}
72
73bool is_binderfs_device(const struct inode *inode)
74{
75 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
76 return true;
77
78 return false;
79}
80
81/**
82 * binderfs_binder_device_create - allocate inode from super block of a
83 * binderfs mount
84 * @ref_inode: inode from wich the super block will be taken
85 * @userp: buffer to copy information about new device for userspace to
86 * @req: struct binderfs_device as copied from userspace
87 *
88 * This function allocates a new binder_device and reserves a new minor
89 * number for it.
90 * Minor numbers are limited and tracked globally in binderfs_minors. The
91 * function will stash a struct binder_device for the specific binder
92 * device in i_private of the inode.
93 * It will go on to allocate a new inode from the super block of the
94 * filesystem mount, stash a struct binder_device in its i_private field
95 * and attach a dentry to that inode.
96 *
97 * Return: 0 on success, negative errno on failure
98 */
99static int binderfs_binder_device_create(struct inode *ref_inode,
100 struct binderfs_device __user *userp,
101 struct binderfs_device *req)
102{
103 int minor, ret;
104 struct dentry *dentry, *root;
105 struct binder_device *device;
106 char *name = NULL;
107 size_t name_len;
108 struct inode *inode = NULL;
109 struct super_block *sb = ref_inode->i_sb;
110 struct binderfs_info *info = sb->s_fs_info;
111#if defined(CONFIG_IPC_NS)
112 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
113#else
114 bool use_reserve = true;
115#endif
116
117 /* Reserve new minor number for the new device. */
118 mutex_lock(&binderfs_minors_mutex);
119 if (++info->device_count <= info->mount_opts.max)
120 minor = ida_alloc_max(&binderfs_minors,
121 use_reserve ? BINDERFS_MAX_MINOR :
122 BINDERFS_MAX_MINOR_CAPPED,
123 GFP_KERNEL);
124 else
125 minor = -ENOSPC;
126 if (minor < 0) {
127 --info->device_count;
128 mutex_unlock(&binderfs_minors_mutex);
129 return minor;
130 }
131 mutex_unlock(&binderfs_minors_mutex);
132
133 ret = -ENOMEM;
134 device = kzalloc(sizeof(*device), GFP_KERNEL);
135 if (!device)
136 goto err;
137
138 inode = new_inode(sb);
139 if (!inode)
140 goto err;
141
142 inode->i_ino = minor + INODE_OFFSET;
143 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
144 init_special_inode(inode, S_IFCHR | 0600,
145 MKDEV(MAJOR(binderfs_dev), minor));
146 inode->i_fop = &binder_fops;
147 inode->i_uid = info->root_uid;
148 inode->i_gid = info->root_gid;
149
150 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
151 name_len = strlen(req->name);
152 /* Make sure to include terminating NUL byte */
153 name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
154 if (!name)
155 goto err;
156
157 device->binderfs_inode = inode;
158 device->context.binder_context_mgr_uid = INVALID_UID;
159 device->context.name = name;
160 device->miscdev.name = name;
161 device->miscdev.minor = minor;
162 mutex_init(&device->context.context_mgr_node_lock);
163
164 req->major = MAJOR(binderfs_dev);
165 req->minor = minor;
166
167 if (userp && copy_to_user(userp, req, sizeof(*req))) {
168 ret = -EFAULT;
169 goto err;
170 }
171
172 root = sb->s_root;
173 inode_lock(d_inode(root));
174
175 /* look it up */
176 dentry = lookup_one_len(name, root, name_len);
177 if (IS_ERR(dentry)) {
178 inode_unlock(d_inode(root));
179 ret = PTR_ERR(dentry);
180 goto err;
181 }
182
183 if (d_really_is_positive(dentry)) {
184 /* already exists */
185 dput(dentry);
186 inode_unlock(d_inode(root));
187 ret = -EEXIST;
188 goto err;
189 }
190
191 inode->i_private = device;
192 d_instantiate(dentry, inode);
193 fsnotify_create(root->d_inode, dentry);
194 inode_unlock(d_inode(root));
195
196 return 0;
197
198err:
199 kfree(name);
200 kfree(device);
201 mutex_lock(&binderfs_minors_mutex);
202 --info->device_count;
203 ida_free(&binderfs_minors, minor);
204 mutex_unlock(&binderfs_minors_mutex);
205 iput(inode);
206
207 return ret;
208}
209
210/**
211 * binderfs_ctl_ioctl - handle binder device node allocation requests
212 *
213 * The request handler for the binder-control device. All requests operate on
214 * the binderfs mount the binder-control device resides in:
215 * - BINDER_CTL_ADD
216 * Allocate a new binder device.
217 *
218 * Return: 0 on success, negative errno on failure
219 */
220static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
221 unsigned long arg)
222{
223 int ret = -EINVAL;
224 struct inode *inode = file_inode(file);
225 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
226 struct binderfs_device device_req;
227
228 switch (cmd) {
229 case BINDER_CTL_ADD:
230 ret = copy_from_user(&device_req, device, sizeof(device_req));
231 if (ret) {
232 ret = -EFAULT;
233 break;
234 }
235
236 ret = binderfs_binder_device_create(inode, device, &device_req);
237 break;
238 default:
239 break;
240 }
241
242 return ret;
243}
244
245static void binderfs_evict_inode(struct inode *inode)
246{
247 struct binder_device *device = inode->i_private;
248 struct binderfs_info *info = BINDERFS_I(inode);
249
250 clear_inode(inode);
251
252 if (!S_ISCHR(inode->i_mode) || !device)
253 return;
254
255 mutex_lock(&binderfs_minors_mutex);
256 --info->device_count;
257 ida_free(&binderfs_minors, device->miscdev.minor);
258 mutex_unlock(&binderfs_minors_mutex);
259
260 kfree(device->context.name);
261 kfree(device);
262}
263
264/**
265 * binderfs_parse_mount_opts - parse binderfs mount options
266 * @data: options to set (can be NULL in which case defaults are used)
267 */
268static int binderfs_parse_mount_opts(char *data,
269 struct binderfs_mount_opts *opts)
270{
271 char *p, *stats;
272 opts->max = BINDERFS_MAX_MINOR;
273 opts->stats_mode = STATS_NONE;
274
275 while ((p = strsep(&data, ",")) != NULL) {
276 substring_t args[MAX_OPT_ARGS];
277 int token;
278 int max_devices;
279
280 if (!*p)
281 continue;
282
283 token = match_token(p, tokens, args);
284 switch (token) {
285 case Opt_max:
286 if (match_int(&args[0], &max_devices) ||
287 (max_devices < 0 ||
288 (max_devices > BINDERFS_MAX_MINOR)))
289 return -EINVAL;
290
291 opts->max = max_devices;
292 break;
293 case Opt_stats_mode:
294 if (!capable(CAP_SYS_ADMIN))
295 return -EINVAL;
296
297 stats = match_strdup(&args[0]);
298 if (!stats)
299 return -ENOMEM;
300
301 if (strcmp(stats, "global") != 0) {
302 kfree(stats);
303 return -EINVAL;
304 }
305
306 opts->stats_mode = STATS_GLOBAL;
307 kfree(stats);
308 break;
309 default:
310 pr_err("Invalid mount options\n");
311 return -EINVAL;
312 }
313 }
314
315 return 0;
316}
317
318static int binderfs_remount(struct super_block *sb, int *flags, char *data)
319{
320 int prev_stats_mode, ret;
321 struct binderfs_info *info = sb->s_fs_info;
322
323 prev_stats_mode = info->mount_opts.stats_mode;
324 ret = binderfs_parse_mount_opts(data, &info->mount_opts);
325 if (ret)
326 return ret;
327
328 if (prev_stats_mode != info->mount_opts.stats_mode) {
329 pr_err("Binderfs stats mode cannot be changed during a remount\n");
330 info->mount_opts.stats_mode = prev_stats_mode;
331 return -EINVAL;
332 }
333
334 return 0;
335}
336
337static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
338{
339 struct binderfs_info *info;
340
341 info = root->d_sb->s_fs_info;
342 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
343 seq_printf(seq, ",max=%d", info->mount_opts.max);
344 if (info->mount_opts.stats_mode == STATS_GLOBAL)
345 seq_printf(seq, ",stats=global");
346
347 return 0;
348}
349
350static const struct super_operations binderfs_super_ops = {
351 .evict_inode = binderfs_evict_inode,
352 .remount_fs = binderfs_remount,
353 .show_options = binderfs_show_mount_opts,
354 .statfs = simple_statfs,
355};
356
357static inline bool is_binderfs_control_device(const struct dentry *dentry)
358{
359 struct binderfs_info *info = dentry->d_sb->s_fs_info;
360 return info->control_dentry == dentry;
361}
362
363static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry,
364 struct inode *new_dir, struct dentry *new_dentry,
365 unsigned int flags)
366{
367 if (is_binderfs_control_device(old_dentry) ||
368 is_binderfs_control_device(new_dentry))
369 return -EPERM;
370
371 return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
372}
373
374static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
375{
376 if (is_binderfs_control_device(dentry))
377 return -EPERM;
378
379 return simple_unlink(dir, dentry);
380}
381
382static const struct file_operations binder_ctl_fops = {
383 .owner = THIS_MODULE,
384 .open = nonseekable_open,
385 .unlocked_ioctl = binder_ctl_ioctl,
386 .compat_ioctl = binder_ctl_ioctl,
387 .llseek = noop_llseek,
388};
389
390/**
391 * binderfs_binder_ctl_create - create a new binder-control device
392 * @sb: super block of the binderfs mount
393 *
394 * This function creates a new binder-control device node in the binderfs mount
395 * referred to by @sb.
396 *
397 * Return: 0 on success, negative errno on failure
398 */
399static int binderfs_binder_ctl_create(struct super_block *sb)
400{
401 int minor, ret;
402 struct dentry *dentry;
403 struct binder_device *device;
404 struct inode *inode = NULL;
405 struct dentry *root = sb->s_root;
406 struct binderfs_info *info = sb->s_fs_info;
407#if defined(CONFIG_IPC_NS)
408 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
409#else
410 bool use_reserve = true;
411#endif
412
413 device = kzalloc(sizeof(*device), GFP_KERNEL);
414 if (!device)
415 return -ENOMEM;
416
417 /* If we have already created a binder-control node, return. */
418 if (info->control_dentry) {
419 ret = 0;
420 goto out;
421 }
422
423 ret = -ENOMEM;
424 inode = new_inode(sb);
425 if (!inode)
426 goto out;
427
428 /* Reserve a new minor number for the new device. */
429 mutex_lock(&binderfs_minors_mutex);
430 minor = ida_alloc_max(&binderfs_minors,
431 use_reserve ? BINDERFS_MAX_MINOR :
432 BINDERFS_MAX_MINOR_CAPPED,
433 GFP_KERNEL);
434 mutex_unlock(&binderfs_minors_mutex);
435 if (minor < 0) {
436 ret = minor;
437 goto out;
438 }
439
440 inode->i_ino = SECOND_INODE;
441 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
442 init_special_inode(inode, S_IFCHR | 0600,
443 MKDEV(MAJOR(binderfs_dev), minor));
444 inode->i_fop = &binder_ctl_fops;
445 inode->i_uid = info->root_uid;
446 inode->i_gid = info->root_gid;
447
448 device->binderfs_inode = inode;
449 device->miscdev.minor = minor;
450
451 dentry = d_alloc_name(root, "binder-control");
452 if (!dentry)
453 goto out;
454
455 inode->i_private = device;
456 info->control_dentry = dentry;
457 d_add(dentry, inode);
458
459 return 0;
460
461out:
462 kfree(device);
463 iput(inode);
464
465 return ret;
466}
467
468static const struct inode_operations binderfs_dir_inode_operations = {
469 .lookup = simple_lookup,
470 .rename = binderfs_rename,
471 .unlink = binderfs_unlink,
472};
473
474static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
475{
476 struct inode *ret;
477
478 ret = new_inode(sb);
479 if (ret) {
480 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
481 ret->i_mode = mode;
482 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
483 }
484 return ret;
485}
486
487static struct dentry *binderfs_create_dentry(struct dentry *parent,
488 const char *name)
489{
490 struct dentry *dentry;
491
492 dentry = lookup_one_len(name, parent, strlen(name));
493 if (IS_ERR(dentry))
494 return dentry;
495
496 /* Return error if the file/dir already exists. */
497 if (d_really_is_positive(dentry)) {
498 dput(dentry);
499 return ERR_PTR(-EEXIST);
500 }
501
502 return dentry;
503}
504
505void binderfs_remove_file(struct dentry *dentry)
506{
507 struct inode *parent_inode;
508
509 parent_inode = d_inode(dentry->d_parent);
510 inode_lock(parent_inode);
511 if (simple_positive(dentry)) {
512 dget(dentry);
513 simple_unlink(parent_inode, dentry);
514 d_delete(dentry);
515 dput(dentry);
516 }
517 inode_unlock(parent_inode);
518}
519
520struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
521 const struct file_operations *fops,
522 void *data)
523{
524 struct dentry *dentry;
525 struct inode *new_inode, *parent_inode;
526 struct super_block *sb;
527
528 parent_inode = d_inode(parent);
529 inode_lock(parent_inode);
530
531 dentry = binderfs_create_dentry(parent, name);
532 if (IS_ERR(dentry))
533 goto out;
534
535 sb = parent_inode->i_sb;
536 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
537 if (!new_inode) {
538 dput(dentry);
539 dentry = ERR_PTR(-ENOMEM);
540 goto out;
541 }
542
543 new_inode->i_fop = fops;
544 new_inode->i_private = data;
545 d_instantiate(dentry, new_inode);
546 fsnotify_create(parent_inode, dentry);
547
548out:
549 inode_unlock(parent_inode);
550 return dentry;
551}
552
553static struct dentry *binderfs_create_dir(struct dentry *parent,
554 const char *name)
555{
556 struct dentry *dentry;
557 struct inode *new_inode, *parent_inode;
558 struct super_block *sb;
559
560 parent_inode = d_inode(parent);
561 inode_lock(parent_inode);
562
563 dentry = binderfs_create_dentry(parent, name);
564 if (IS_ERR(dentry))
565 goto out;
566
567 sb = parent_inode->i_sb;
568 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
569 if (!new_inode) {
570 dput(dentry);
571 dentry = ERR_PTR(-ENOMEM);
572 goto out;
573 }
574
575 new_inode->i_fop = &simple_dir_operations;
576 new_inode->i_op = &simple_dir_inode_operations;
577
578 set_nlink(new_inode, 2);
579 d_instantiate(dentry, new_inode);
580 inc_nlink(parent_inode);
581 fsnotify_mkdir(parent_inode, dentry);
582
583out:
584 inode_unlock(parent_inode);
585 return dentry;
586}
587
588static int init_binder_logs(struct super_block *sb)
589{
590 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
591 struct binderfs_info *info;
592 int ret = 0;
593
594 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
595 "binder_logs");
596 if (IS_ERR(binder_logs_root_dir)) {
597 ret = PTR_ERR(binder_logs_root_dir);
598 goto out;
599 }
600
601 dentry = binderfs_create_file(binder_logs_root_dir, "stats",
602 &binder_stats_fops, NULL);
603 if (IS_ERR(dentry)) {
604 ret = PTR_ERR(dentry);
605 goto out;
606 }
607
608 dentry = binderfs_create_file(binder_logs_root_dir, "state",
609 &binder_state_fops, NULL);
610 if (IS_ERR(dentry)) {
611 ret = PTR_ERR(dentry);
612 goto out;
613 }
614
615 dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
616 &binder_transactions_fops, NULL);
617 if (IS_ERR(dentry)) {
618 ret = PTR_ERR(dentry);
619 goto out;
620 }
621
622 dentry = binderfs_create_file(binder_logs_root_dir,
623 "transaction_log",
624 &binder_transaction_log_fops,
625 &binder_transaction_log);
626 if (IS_ERR(dentry)) {
627 ret = PTR_ERR(dentry);
628 goto out;
629 }
630
631 dentry = binderfs_create_file(binder_logs_root_dir,
632 "failed_transaction_log",
633 &binder_transaction_log_fops,
634 &binder_transaction_log_failed);
635 if (IS_ERR(dentry)) {
636 ret = PTR_ERR(dentry);
637 goto out;
638 }
639
640 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
641 if (IS_ERR(proc_log_dir)) {
642 ret = PTR_ERR(proc_log_dir);
643 goto out;
644 }
645 info = sb->s_fs_info;
646 info->proc_log_dir = proc_log_dir;
647
648out:
649 return ret;
650}
651
652static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
653{
654 int ret;
655 struct binderfs_info *info;
656 struct inode *inode = NULL;
657 struct binderfs_device device_info = { 0 };
658 const char *name;
659 size_t len;
660
661 sb->s_blocksize = PAGE_SIZE;
662 sb->s_blocksize_bits = PAGE_SHIFT;
663
664 /*
665 * The binderfs filesystem can be mounted by userns root in a
666 * non-initial userns. By default such mounts have the SB_I_NODEV flag
667 * set in s_iflags to prevent security issues where userns root can
668 * just create random device nodes via mknod() since it owns the
669 * filesystem mount. But binderfs does not allow to create any files
670 * including devices nodes. The only way to create binder devices nodes
671 * is through the binder-control device which userns root is explicitly
672 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
673 * necessary and safe.
674 */
675 sb->s_iflags &= ~SB_I_NODEV;
676 sb->s_iflags |= SB_I_NOEXEC;
677 sb->s_magic = BINDERFS_SUPER_MAGIC;
678 sb->s_op = &binderfs_super_ops;
679 sb->s_time_gran = 1;
680
681 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
682 if (!sb->s_fs_info)
683 return -ENOMEM;
684 info = sb->s_fs_info;
685
686 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
687
688 ret = binderfs_parse_mount_opts(data, &info->mount_opts);
689 if (ret)
690 return ret;
691
692 info->root_gid = make_kgid(sb->s_user_ns, 0);
693 if (!gid_valid(info->root_gid))
694 info->root_gid = GLOBAL_ROOT_GID;
695 info->root_uid = make_kuid(sb->s_user_ns, 0);
696 if (!uid_valid(info->root_uid))
697 info->root_uid = GLOBAL_ROOT_UID;
698
699 inode = new_inode(sb);
700 if (!inode)
701 return -ENOMEM;
702
703 inode->i_ino = FIRST_INODE;
704 inode->i_fop = &simple_dir_operations;
705 inode->i_mode = S_IFDIR | 0755;
706 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
707 inode->i_op = &binderfs_dir_inode_operations;
708 set_nlink(inode, 2);
709
710 sb->s_root = d_make_root(inode);
711 if (!sb->s_root)
712 return -ENOMEM;
713
714 ret = binderfs_binder_ctl_create(sb);
715 if (ret)
716 return ret;
717
718 name = binder_devices_param;
719 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
720 strscpy(device_info.name, name, len + 1);
721 ret = binderfs_binder_device_create(inode, NULL, &device_info);
722 if (ret)
723 return ret;
724 name += len;
725 if (*name == ',')
726 name++;
727 }
728
729 if (info->mount_opts.stats_mode == STATS_GLOBAL)
730 return init_binder_logs(sb);
731
732 return 0;
733}
734
735static struct dentry *binderfs_mount(struct file_system_type *fs_type,
736 int flags, const char *dev_name,
737 void *data)
738{
739 return mount_nodev(fs_type, flags, data, binderfs_fill_super);
740}
741
742static void binderfs_kill_super(struct super_block *sb)
743{
744 struct binderfs_info *info = sb->s_fs_info;
745
746 kill_litter_super(sb);
747
748 if (info && info->ipc_ns)
749 put_ipc_ns(info->ipc_ns);
750
751 kfree(info);
752}
753
754static struct file_system_type binder_fs_type = {
755 .name = "binder",
756 .mount = binderfs_mount,
757 .kill_sb = binderfs_kill_super,
758 .fs_flags = FS_USERNS_MOUNT,
759};
760
761int __init init_binderfs(void)
762{
763 int ret;
764 const char *name;
765 size_t len;
766
767 /* Verify that the default binderfs device names are valid. */
768 name = binder_devices_param;
769 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
770 if (len > BINDERFS_MAX_NAME)
771 return -E2BIG;
772 name += len;
773 if (*name == ',')
774 name++;
775 }
776
777 /* Allocate new major number for binderfs. */
778 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
779 "binder");
780 if (ret)
781 return ret;
782
783 ret = register_filesystem(&binder_fs_type);
784 if (ret) {
785 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
786 return ret;
787 }
788
789 return ret;
790}