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}