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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/fs_parser.h>
22#include <linux/sched.h>
23#include <linux/seq_file.h>
24#include <linux/slab.h>
25#include <linux/spinlock_types.h>
26#include <linux/stddef.h>
27#include <linux/string.h>
28#include <linux/types.h>
29#include <linux/uaccess.h>
30#include <linux/user_namespace.h>
31#include <linux/xarray.h>
32#include <uapi/linux/android/binder.h>
33#include <uapi/linux/android/binderfs.h>
34
35#include "binder_internal.h"
36
37#define FIRST_INODE 1
38#define SECOND_INODE 2
39#define INODE_OFFSET 3
40#define BINDERFS_MAX_MINOR (1U << MINORBITS)
41/* Ensure that the initial ipc namespace always has devices available. */
42#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
43
44static dev_t binderfs_dev;
45static DEFINE_MUTEX(binderfs_minors_mutex);
46static DEFINE_IDA(binderfs_minors);
47
48enum binderfs_param {
49 Opt_max,
50 Opt_stats_mode,
51};
52
53enum binderfs_stats_mode {
54 binderfs_stats_mode_unset,
55 binderfs_stats_mode_global,
56};
57
58struct binder_features {
59 bool oneway_spam_detection;
60 bool extended_error;
61 bool freeze_notification;
62};
63
64static const struct constant_table binderfs_param_stats[] = {
65 { "global", binderfs_stats_mode_global },
66 {}
67};
68
69static const struct fs_parameter_spec binderfs_fs_parameters[] = {
70 fsparam_u32("max", Opt_max),
71 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats),
72 {}
73};
74
75static struct binder_features binder_features = {
76 .oneway_spam_detection = true,
77 .extended_error = true,
78 .freeze_notification = true,
79};
80
81static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
82{
83 return sb->s_fs_info;
84}
85
86bool is_binderfs_device(const struct inode *inode)
87{
88 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
89 return true;
90
91 return false;
92}
93
94/**
95 * binderfs_binder_device_create - allocate inode from super block of a
96 * binderfs mount
97 * @ref_inode: inode from which the super block will be taken
98 * @userp: buffer to copy information about new device for userspace to
99 * @req: struct binderfs_device as copied from userspace
100 *
101 * This function allocates a new binder_device and reserves a new minor
102 * number for it.
103 * Minor numbers are limited and tracked globally in binderfs_minors. The
104 * function will stash a struct binder_device for the specific binder
105 * device in i_private of the inode.
106 * It will go on to allocate a new inode from the super block of the
107 * filesystem mount, stash a struct binder_device in its i_private field
108 * and attach a dentry to that inode.
109 *
110 * Return: 0 on success, negative errno on failure
111 */
112static int binderfs_binder_device_create(struct inode *ref_inode,
113 struct binderfs_device __user *userp,
114 struct binderfs_device *req)
115{
116 int minor, ret;
117 struct dentry *dentry, *root;
118 struct binder_device *device;
119 char *name = NULL;
120 size_t name_len;
121 struct inode *inode = NULL;
122 struct super_block *sb = ref_inode->i_sb;
123 struct binderfs_info *info = sb->s_fs_info;
124#if defined(CONFIG_IPC_NS)
125 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
126#else
127 bool use_reserve = true;
128#endif
129
130 /* Reserve new minor number for the new device. */
131 mutex_lock(&binderfs_minors_mutex);
132 if (++info->device_count <= info->mount_opts.max)
133 minor = ida_alloc_max(&binderfs_minors,
134 use_reserve ? BINDERFS_MAX_MINOR :
135 BINDERFS_MAX_MINOR_CAPPED,
136 GFP_KERNEL);
137 else
138 minor = -ENOSPC;
139 if (minor < 0) {
140 --info->device_count;
141 mutex_unlock(&binderfs_minors_mutex);
142 return minor;
143 }
144 mutex_unlock(&binderfs_minors_mutex);
145
146 ret = -ENOMEM;
147 device = kzalloc(sizeof(*device), GFP_KERNEL);
148 if (!device)
149 goto err;
150
151 inode = new_inode(sb);
152 if (!inode)
153 goto err;
154
155 inode->i_ino = minor + INODE_OFFSET;
156 simple_inode_init_ts(inode);
157 init_special_inode(inode, S_IFCHR | 0600,
158 MKDEV(MAJOR(binderfs_dev), minor));
159 inode->i_fop = &binder_fops;
160 inode->i_uid = info->root_uid;
161 inode->i_gid = info->root_gid;
162
163 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
164 name_len = strlen(req->name);
165 /* Make sure to include terminating NUL byte */
166 name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
167 if (!name)
168 goto err;
169
170 refcount_set(&device->ref, 1);
171 device->binderfs_inode = inode;
172 device->context.binder_context_mgr_uid = INVALID_UID;
173 device->context.name = name;
174 device->miscdev.name = name;
175 device->miscdev.minor = minor;
176 mutex_init(&device->context.context_mgr_node_lock);
177
178 req->major = MAJOR(binderfs_dev);
179 req->minor = minor;
180
181 if (userp && copy_to_user(userp, req, sizeof(*req))) {
182 ret = -EFAULT;
183 goto err;
184 }
185
186 root = sb->s_root;
187 inode_lock(d_inode(root));
188
189 /* look it up */
190 dentry = lookup_one_len(name, root, name_len);
191 if (IS_ERR(dentry)) {
192 inode_unlock(d_inode(root));
193 ret = PTR_ERR(dentry);
194 goto err;
195 }
196
197 if (d_really_is_positive(dentry)) {
198 /* already exists */
199 dput(dentry);
200 inode_unlock(d_inode(root));
201 ret = -EEXIST;
202 goto err;
203 }
204
205 inode->i_private = device;
206 d_instantiate(dentry, inode);
207 fsnotify_create(root->d_inode, dentry);
208 inode_unlock(d_inode(root));
209
210 return 0;
211
212err:
213 kfree(name);
214 kfree(device);
215 mutex_lock(&binderfs_minors_mutex);
216 --info->device_count;
217 ida_free(&binderfs_minors, minor);
218 mutex_unlock(&binderfs_minors_mutex);
219 iput(inode);
220
221 return ret;
222}
223
224/**
225 * binder_ctl_ioctl - handle binder device node allocation requests
226 *
227 * The request handler for the binder-control device. All requests operate on
228 * the binderfs mount the binder-control device resides in:
229 * - BINDER_CTL_ADD
230 * Allocate a new binder device.
231 *
232 * Return: %0 on success, negative errno on failure.
233 */
234static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
235 unsigned long arg)
236{
237 int ret = -EINVAL;
238 struct inode *inode = file_inode(file);
239 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
240 struct binderfs_device device_req;
241
242 switch (cmd) {
243 case BINDER_CTL_ADD:
244 ret = copy_from_user(&device_req, device, sizeof(device_req));
245 if (ret) {
246 ret = -EFAULT;
247 break;
248 }
249
250 ret = binderfs_binder_device_create(inode, device, &device_req);
251 break;
252 default:
253 break;
254 }
255
256 return ret;
257}
258
259static void binderfs_evict_inode(struct inode *inode)
260{
261 struct binder_device *device = inode->i_private;
262 struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
263
264 clear_inode(inode);
265
266 if (!S_ISCHR(inode->i_mode) || !device)
267 return;
268
269 mutex_lock(&binderfs_minors_mutex);
270 --info->device_count;
271 ida_free(&binderfs_minors, device->miscdev.minor);
272 mutex_unlock(&binderfs_minors_mutex);
273
274 if (refcount_dec_and_test(&device->ref)) {
275 kfree(device->context.name);
276 kfree(device);
277 }
278}
279
280static int binderfs_fs_context_parse_param(struct fs_context *fc,
281 struct fs_parameter *param)
282{
283 int opt;
284 struct binderfs_mount_opts *ctx = fc->fs_private;
285 struct fs_parse_result result;
286
287 opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
288 if (opt < 0)
289 return opt;
290
291 switch (opt) {
292 case Opt_max:
293 if (result.uint_32 > BINDERFS_MAX_MINOR)
294 return invalfc(fc, "Bad value for '%s'", param->key);
295
296 ctx->max = result.uint_32;
297 break;
298 case Opt_stats_mode:
299 if (!capable(CAP_SYS_ADMIN))
300 return -EPERM;
301
302 ctx->stats_mode = result.uint_32;
303 break;
304 default:
305 return invalfc(fc, "Unsupported parameter '%s'", param->key);
306 }
307
308 return 0;
309}
310
311static int binderfs_fs_context_reconfigure(struct fs_context *fc)
312{
313 struct binderfs_mount_opts *ctx = fc->fs_private;
314 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
315
316 if (info->mount_opts.stats_mode != ctx->stats_mode)
317 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
318
319 info->mount_opts.stats_mode = ctx->stats_mode;
320 info->mount_opts.max = ctx->max;
321 return 0;
322}
323
324static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
325{
326 struct binderfs_info *info = BINDERFS_SB(root->d_sb);
327
328 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
329 seq_printf(seq, ",max=%d", info->mount_opts.max);
330
331 switch (info->mount_opts.stats_mode) {
332 case binderfs_stats_mode_unset:
333 break;
334 case binderfs_stats_mode_global:
335 seq_printf(seq, ",stats=global");
336 break;
337 }
338
339 return 0;
340}
341
342static const struct super_operations binderfs_super_ops = {
343 .evict_inode = binderfs_evict_inode,
344 .show_options = binderfs_show_options,
345 .statfs = simple_statfs,
346};
347
348static inline bool is_binderfs_control_device(const struct dentry *dentry)
349{
350 struct binderfs_info *info = dentry->d_sb->s_fs_info;
351
352 return info->control_dentry == dentry;
353}
354
355static int binderfs_rename(struct mnt_idmap *idmap,
356 struct inode *old_dir, struct dentry *old_dentry,
357 struct inode *new_dir, struct dentry *new_dentry,
358 unsigned int flags)
359{
360 if (is_binderfs_control_device(old_dentry) ||
361 is_binderfs_control_device(new_dentry))
362 return -EPERM;
363
364 return simple_rename(idmap, old_dir, old_dentry, new_dir,
365 new_dentry, flags);
366}
367
368static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
369{
370 if (is_binderfs_control_device(dentry))
371 return -EPERM;
372
373 return simple_unlink(dir, dentry);
374}
375
376static const struct file_operations binder_ctl_fops = {
377 .owner = THIS_MODULE,
378 .open = nonseekable_open,
379 .unlocked_ioctl = binder_ctl_ioctl,
380 .compat_ioctl = binder_ctl_ioctl,
381 .llseek = noop_llseek,
382};
383
384/**
385 * binderfs_binder_ctl_create - create a new binder-control device
386 * @sb: super block of the binderfs mount
387 *
388 * This function creates a new binder-control device node in the binderfs mount
389 * referred to by @sb.
390 *
391 * Return: 0 on success, negative errno on failure
392 */
393static int binderfs_binder_ctl_create(struct super_block *sb)
394{
395 int minor, ret;
396 struct dentry *dentry;
397 struct binder_device *device;
398 struct inode *inode = NULL;
399 struct dentry *root = sb->s_root;
400 struct binderfs_info *info = sb->s_fs_info;
401#if defined(CONFIG_IPC_NS)
402 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
403#else
404 bool use_reserve = true;
405#endif
406
407 device = kzalloc(sizeof(*device), GFP_KERNEL);
408 if (!device)
409 return -ENOMEM;
410
411 /* If we have already created a binder-control node, return. */
412 if (info->control_dentry) {
413 ret = 0;
414 goto out;
415 }
416
417 ret = -ENOMEM;
418 inode = new_inode(sb);
419 if (!inode)
420 goto out;
421
422 /* Reserve a new minor number for the new device. */
423 mutex_lock(&binderfs_minors_mutex);
424 minor = ida_alloc_max(&binderfs_minors,
425 use_reserve ? BINDERFS_MAX_MINOR :
426 BINDERFS_MAX_MINOR_CAPPED,
427 GFP_KERNEL);
428 mutex_unlock(&binderfs_minors_mutex);
429 if (minor < 0) {
430 ret = minor;
431 goto out;
432 }
433
434 inode->i_ino = SECOND_INODE;
435 simple_inode_init_ts(inode);
436 init_special_inode(inode, S_IFCHR | 0600,
437 MKDEV(MAJOR(binderfs_dev), minor));
438 inode->i_fop = &binder_ctl_fops;
439 inode->i_uid = info->root_uid;
440 inode->i_gid = info->root_gid;
441
442 refcount_set(&device->ref, 1);
443 device->binderfs_inode = inode;
444 device->miscdev.minor = minor;
445
446 dentry = d_alloc_name(root, "binder-control");
447 if (!dentry)
448 goto out;
449
450 inode->i_private = device;
451 info->control_dentry = dentry;
452 d_add(dentry, inode);
453
454 return 0;
455
456out:
457 kfree(device);
458 iput(inode);
459
460 return ret;
461}
462
463static const struct inode_operations binderfs_dir_inode_operations = {
464 .lookup = simple_lookup,
465 .rename = binderfs_rename,
466 .unlink = binderfs_unlink,
467};
468
469static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
470{
471 struct inode *ret;
472
473 ret = new_inode(sb);
474 if (ret) {
475 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
476 ret->i_mode = mode;
477 simple_inode_init_ts(ret);
478 }
479 return ret;
480}
481
482static struct dentry *binderfs_create_dentry(struct dentry *parent,
483 const char *name)
484{
485 struct dentry *dentry;
486
487 dentry = lookup_one_len(name, parent, strlen(name));
488 if (IS_ERR(dentry))
489 return dentry;
490
491 /* Return error if the file/dir already exists. */
492 if (d_really_is_positive(dentry)) {
493 dput(dentry);
494 return ERR_PTR(-EEXIST);
495 }
496
497 return dentry;
498}
499
500void binderfs_remove_file(struct dentry *dentry)
501{
502 struct inode *parent_inode;
503
504 parent_inode = d_inode(dentry->d_parent);
505 inode_lock(parent_inode);
506 if (simple_positive(dentry)) {
507 dget(dentry);
508 simple_unlink(parent_inode, dentry);
509 d_delete(dentry);
510 dput(dentry);
511 }
512 inode_unlock(parent_inode);
513}
514
515struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
516 const struct file_operations *fops,
517 void *data)
518{
519 struct dentry *dentry;
520 struct inode *new_inode, *parent_inode;
521 struct super_block *sb;
522
523 parent_inode = d_inode(parent);
524 inode_lock(parent_inode);
525
526 dentry = binderfs_create_dentry(parent, name);
527 if (IS_ERR(dentry))
528 goto out;
529
530 sb = parent_inode->i_sb;
531 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
532 if (!new_inode) {
533 dput(dentry);
534 dentry = ERR_PTR(-ENOMEM);
535 goto out;
536 }
537
538 new_inode->i_fop = fops;
539 new_inode->i_private = data;
540 d_instantiate(dentry, new_inode);
541 fsnotify_create(parent_inode, dentry);
542
543out:
544 inode_unlock(parent_inode);
545 return dentry;
546}
547
548static struct dentry *binderfs_create_dir(struct dentry *parent,
549 const char *name)
550{
551 struct dentry *dentry;
552 struct inode *new_inode, *parent_inode;
553 struct super_block *sb;
554
555 parent_inode = d_inode(parent);
556 inode_lock(parent_inode);
557
558 dentry = binderfs_create_dentry(parent, name);
559 if (IS_ERR(dentry))
560 goto out;
561
562 sb = parent_inode->i_sb;
563 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
564 if (!new_inode) {
565 dput(dentry);
566 dentry = ERR_PTR(-ENOMEM);
567 goto out;
568 }
569
570 new_inode->i_fop = &simple_dir_operations;
571 new_inode->i_op = &simple_dir_inode_operations;
572
573 set_nlink(new_inode, 2);
574 d_instantiate(dentry, new_inode);
575 inc_nlink(parent_inode);
576 fsnotify_mkdir(parent_inode, dentry);
577
578out:
579 inode_unlock(parent_inode);
580 return dentry;
581}
582
583static int binder_features_show(struct seq_file *m, void *unused)
584{
585 bool *feature = m->private;
586
587 seq_printf(m, "%d\n", *feature);
588
589 return 0;
590}
591DEFINE_SHOW_ATTRIBUTE(binder_features);
592
593static int init_binder_features(struct super_block *sb)
594{
595 struct dentry *dentry, *dir;
596
597 dir = binderfs_create_dir(sb->s_root, "features");
598 if (IS_ERR(dir))
599 return PTR_ERR(dir);
600
601 dentry = binderfs_create_file(dir, "oneway_spam_detection",
602 &binder_features_fops,
603 &binder_features.oneway_spam_detection);
604 if (IS_ERR(dentry))
605 return PTR_ERR(dentry);
606
607 dentry = binderfs_create_file(dir, "extended_error",
608 &binder_features_fops,
609 &binder_features.extended_error);
610 if (IS_ERR(dentry))
611 return PTR_ERR(dentry);
612
613 dentry = binderfs_create_file(dir, "freeze_notification",
614 &binder_features_fops,
615 &binder_features.freeze_notification);
616 if (IS_ERR(dentry))
617 return PTR_ERR(dentry);
618
619 return 0;
620}
621
622static int init_binder_logs(struct super_block *sb)
623{
624 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
625 const struct binder_debugfs_entry *db_entry;
626 struct binderfs_info *info;
627 int ret = 0;
628
629 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
630 "binder_logs");
631 if (IS_ERR(binder_logs_root_dir)) {
632 ret = PTR_ERR(binder_logs_root_dir);
633 goto out;
634 }
635
636 binder_for_each_debugfs_entry(db_entry) {
637 dentry = binderfs_create_file(binder_logs_root_dir,
638 db_entry->name,
639 db_entry->fops,
640 db_entry->data);
641 if (IS_ERR(dentry)) {
642 ret = PTR_ERR(dentry);
643 goto out;
644 }
645 }
646
647 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
648 if (IS_ERR(proc_log_dir)) {
649 ret = PTR_ERR(proc_log_dir);
650 goto out;
651 }
652 info = sb->s_fs_info;
653 info->proc_log_dir = proc_log_dir;
654
655out:
656 return ret;
657}
658
659static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
660{
661 int ret;
662 struct binderfs_info *info;
663 struct binderfs_mount_opts *ctx = fc->fs_private;
664 struct inode *inode = NULL;
665 struct binderfs_device device_info = {};
666 const char *name;
667 size_t len;
668
669 sb->s_blocksize = PAGE_SIZE;
670 sb->s_blocksize_bits = PAGE_SHIFT;
671
672 /*
673 * The binderfs filesystem can be mounted by userns root in a
674 * non-initial userns. By default such mounts have the SB_I_NODEV flag
675 * set in s_iflags to prevent security issues where userns root can
676 * just create random device nodes via mknod() since it owns the
677 * filesystem mount. But binderfs does not allow to create any files
678 * including devices nodes. The only way to create binder devices nodes
679 * is through the binder-control device which userns root is explicitly
680 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
681 * necessary and safe.
682 */
683 sb->s_iflags &= ~SB_I_NODEV;
684 sb->s_iflags |= SB_I_NOEXEC;
685 sb->s_magic = BINDERFS_SUPER_MAGIC;
686 sb->s_op = &binderfs_super_ops;
687 sb->s_time_gran = 1;
688
689 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
690 if (!sb->s_fs_info)
691 return -ENOMEM;
692 info = sb->s_fs_info;
693
694 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
695
696 info->root_gid = make_kgid(sb->s_user_ns, 0);
697 if (!gid_valid(info->root_gid))
698 info->root_gid = GLOBAL_ROOT_GID;
699 info->root_uid = make_kuid(sb->s_user_ns, 0);
700 if (!uid_valid(info->root_uid))
701 info->root_uid = GLOBAL_ROOT_UID;
702 info->mount_opts.max = ctx->max;
703 info->mount_opts.stats_mode = ctx->stats_mode;
704
705 inode = new_inode(sb);
706 if (!inode)
707 return -ENOMEM;
708
709 inode->i_ino = FIRST_INODE;
710 inode->i_fop = &simple_dir_operations;
711 inode->i_mode = S_IFDIR | 0755;
712 simple_inode_init_ts(inode);
713 inode->i_op = &binderfs_dir_inode_operations;
714 set_nlink(inode, 2);
715
716 sb->s_root = d_make_root(inode);
717 if (!sb->s_root)
718 return -ENOMEM;
719
720 ret = binderfs_binder_ctl_create(sb);
721 if (ret)
722 return ret;
723
724 name = binder_devices_param;
725 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
726 strscpy(device_info.name, name, len + 1);
727 ret = binderfs_binder_device_create(inode, NULL, &device_info);
728 if (ret)
729 return ret;
730 name += len;
731 if (*name == ',')
732 name++;
733 }
734
735 ret = init_binder_features(sb);
736 if (ret)
737 return ret;
738
739 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
740 return init_binder_logs(sb);
741
742 return 0;
743}
744
745static int binderfs_fs_context_get_tree(struct fs_context *fc)
746{
747 return get_tree_nodev(fc, binderfs_fill_super);
748}
749
750static void binderfs_fs_context_free(struct fs_context *fc)
751{
752 struct binderfs_mount_opts *ctx = fc->fs_private;
753
754 kfree(ctx);
755}
756
757static const struct fs_context_operations binderfs_fs_context_ops = {
758 .free = binderfs_fs_context_free,
759 .get_tree = binderfs_fs_context_get_tree,
760 .parse_param = binderfs_fs_context_parse_param,
761 .reconfigure = binderfs_fs_context_reconfigure,
762};
763
764static int binderfs_init_fs_context(struct fs_context *fc)
765{
766 struct binderfs_mount_opts *ctx;
767
768 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
769 if (!ctx)
770 return -ENOMEM;
771
772 ctx->max = BINDERFS_MAX_MINOR;
773 ctx->stats_mode = binderfs_stats_mode_unset;
774
775 fc->fs_private = ctx;
776 fc->ops = &binderfs_fs_context_ops;
777
778 return 0;
779}
780
781static void binderfs_kill_super(struct super_block *sb)
782{
783 struct binderfs_info *info = sb->s_fs_info;
784
785 /*
786 * During inode eviction struct binderfs_info is needed.
787 * So first wipe the super_block then free struct binderfs_info.
788 */
789 kill_litter_super(sb);
790
791 if (info && info->ipc_ns)
792 put_ipc_ns(info->ipc_ns);
793
794 kfree(info);
795}
796
797static struct file_system_type binder_fs_type = {
798 .name = "binder",
799 .init_fs_context = binderfs_init_fs_context,
800 .parameters = binderfs_fs_parameters,
801 .kill_sb = binderfs_kill_super,
802 .fs_flags = FS_USERNS_MOUNT,
803};
804
805int __init init_binderfs(void)
806{
807 int ret;
808 const char *name;
809 size_t len;
810
811 /* Verify that the default binderfs device names are valid. */
812 name = binder_devices_param;
813 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
814 if (len > BINDERFS_MAX_NAME)
815 return -E2BIG;
816 name += len;
817 if (*name == ',')
818 name++;
819 }
820
821 /* Allocate new major number for binderfs. */
822 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
823 "binder");
824 if (ret)
825 return ret;
826
827 ret = register_filesystem(&binder_fs_type);
828 if (ret) {
829 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
830 return ret;
831 }
832
833 return ret;
834}