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/asm-generic/errno-base.h>
33
#include <uapi/linux/android/binder.h>
34
#include <uapi/linux/android/binderfs.h>
35

36
#include "rust_binder.h"
37
#include "rust_binder_internal.h"
38

39
#define FIRST_INODE 1
40
#define SECOND_INODE 2
41
#define INODE_OFFSET 3
42
#define BINDERFS_MAX_MINOR (1U << MINORBITS)
43
/* Ensure that the initial ipc namespace always has devices available. */
44
#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
45

46
DEFINE_SHOW_ATTRIBUTE(rust_binder_stats);
47
DEFINE_SHOW_ATTRIBUTE(rust_binder_state);
48
DEFINE_SHOW_ATTRIBUTE(rust_binder_transactions);
49
DEFINE_SHOW_ATTRIBUTE(rust_binder_proc);
50

51
char *rust_binder_devices_param = CONFIG_ANDROID_BINDER_DEVICES;
52
module_param_named(rust_devices, rust_binder_devices_param, charp, 0444);
53

54
static dev_t binderfs_dev;
55
static DEFINE_MUTEX(binderfs_minors_mutex);
56
static DEFINE_IDA(binderfs_minors);
57

58
enum binderfs_param {
59
	Opt_max,
60
	Opt_stats_mode,
61
};
62

63
enum binderfs_stats_mode {
64
	binderfs_stats_mode_unset,
65
	binderfs_stats_mode_global,
66
};
67

68
struct binder_features {
69
	bool oneway_spam_detection;
70
	bool extended_error;
71
	bool freeze_notification;
72
};
73

74
static const struct constant_table binderfs_param_stats[] = {
75
	{ "global", binderfs_stats_mode_global },
76
	{}
77
};
78

79
static const struct fs_parameter_spec binderfs_fs_parameters[] = {
80
	fsparam_u32("max",	Opt_max),
81
	fsparam_enum("stats",	Opt_stats_mode, binderfs_param_stats),
82
	{}
83
};
84

85
static struct binder_features binder_features = {
86
	.oneway_spam_detection = true,
87
	.extended_error = true,
88
	.freeze_notification = true,
89
};
90

91
static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
92
{
93
	return sb->s_fs_info;
94
}
95

96
/**
97
 * binderfs_binder_device_create - allocate inode from super block of a
98
 *                                 binderfs mount
99
 * @ref_inode: inode from wich the super block will be taken
100
 * @userp:     buffer to copy information about new device for userspace to
101
 * @req:       struct binderfs_device as copied from userspace
102
 *
103
 * This function allocates a new binder_device and reserves a new minor
104
 * number for it.
105
 * Minor numbers are limited and tracked globally in binderfs_minors. The
106
 * function will stash a struct binder_device for the specific binder
107
 * device in i_private of the inode.
108
 * It will go on to allocate a new inode from the super block of the
109
 * filesystem mount, stash a struct binder_device in its i_private field
110
 * and attach a dentry to that inode.
111
 *
112
 * Return: 0 on success, negative errno on failure
113
 */
114
static int binderfs_binder_device_create(struct inode *ref_inode,
115
					 struct binderfs_device __user *userp,
116
					 struct binderfs_device *req)
117
{
118
	int minor, ret;
119
	struct dentry *dentry, *root;
120
	struct binder_device *device = NULL;
121
	rust_binder_context ctx = NULL;
122
	struct inode *inode = NULL;
123
	struct super_block *sb = ref_inode->i_sb;
124
	struct binderfs_info *info = sb->s_fs_info;
125
#if defined(CONFIG_IPC_NS)
126
	bool use_reserve = (info->ipc_ns == &init_ipc_ns);
127
#else
128
	bool use_reserve = true;
129
#endif
130

131
	/* Reserve new minor number for the new device. */
132
	mutex_lock(&binderfs_minors_mutex);
133
	if (++info->device_count <= info->mount_opts.max)
134
		minor = ida_alloc_max(&binderfs_minors,
135
				      use_reserve ? BINDERFS_MAX_MINOR :
136
						    BINDERFS_MAX_MINOR_CAPPED,
137
				      GFP_KERNEL);
138
	else
139
		minor = -ENOSPC;
140
	if (minor < 0) {
141
		--info->device_count;
142
		mutex_unlock(&binderfs_minors_mutex);
143
		return minor;
144
	}
145
	mutex_unlock(&binderfs_minors_mutex);
146

147
	ret = -ENOMEM;
148
	device = kzalloc(sizeof(*device), GFP_KERNEL);
149
	if (!device)
150
		goto err;
151

152
	req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
153

154
	ctx = rust_binder_new_context(req->name);
155
	if (!ctx)
156
		goto err;
157

158
	inode = new_inode(sb);
159
	if (!inode)
160
		goto err;
161

162
	inode->i_ino = minor + INODE_OFFSET;
163
	simple_inode_init_ts(inode);
164
	init_special_inode(inode, S_IFCHR | 0600,
165
			   MKDEV(MAJOR(binderfs_dev), minor));
166
	inode->i_fop = &rust_binder_fops;
167
	inode->i_uid = info->root_uid;
168
	inode->i_gid = info->root_gid;
169

170
	req->major = MAJOR(binderfs_dev);
171
	req->minor = minor;
172
	device->ctx = ctx;
173
	device->minor = minor;
174

175
	if (userp && copy_to_user(userp, req, sizeof(*req))) {
176
		ret = -EFAULT;
177
		goto err;
178
	}
179

180
	root = sb->s_root;
181
	inode_lock(d_inode(root));
182

183
	/* look it up */
184
	dentry = lookup_noperm(&QSTR(req->name), root);
185
	if (IS_ERR(dentry)) {
186
		inode_unlock(d_inode(root));
187
		ret = PTR_ERR(dentry);
188
		goto err;
189
	}
190

191
	if (d_really_is_positive(dentry)) {
192
		/* already exists */
193
		dput(dentry);
194
		inode_unlock(d_inode(root));
195
		ret = -EEXIST;
196
		goto err;
197
	}
198

199
	inode->i_private = device;
200
	d_instantiate(dentry, inode);
201
	fsnotify_create(root->d_inode, dentry);
202
	inode_unlock(d_inode(root));
203

204
	return 0;
205

206
err:
207
	kfree(device);
208
	rust_binder_remove_context(ctx);
209
	mutex_lock(&binderfs_minors_mutex);
210
	--info->device_count;
211
	ida_free(&binderfs_minors, minor);
212
	mutex_unlock(&binderfs_minors_mutex);
213
	iput(inode);
214

215
	return ret;
216
}
217

218
/**
219
 * binder_ctl_ioctl - handle binder device node allocation requests
220
 *
221
 * The request handler for the binder-control device. All requests operate on
222
 * the binderfs mount the binder-control device resides in:
223
 * - BINDER_CTL_ADD
224
 *   Allocate a new binder device.
225
 *
226
 * Return: %0 on success, negative errno on failure.
227
 */
228
static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
229
			     unsigned long arg)
230
{
231
	int ret = -EINVAL;
232
	struct inode *inode = file_inode(file);
233
	struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
234
	struct binderfs_device device_req;
235

236
	switch (cmd) {
237
	case BINDER_CTL_ADD:
238
		ret = copy_from_user(&device_req, device, sizeof(device_req));
239
		if (ret) {
240
			ret = -EFAULT;
241
			break;
242
		}
243

244
		ret = binderfs_binder_device_create(inode, device, &device_req);
245
		break;
246
	default:
247
		break;
248
	}
249

250
	return ret;
251
}
252

253
static void binderfs_evict_inode(struct inode *inode)
254
{
255
	struct binder_device *device = inode->i_private;
256
	struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
257

258
	clear_inode(inode);
259

260
	if (!S_ISCHR(inode->i_mode) || !device)
261
		return;
262

263
	mutex_lock(&binderfs_minors_mutex);
264
	--info->device_count;
265
	ida_free(&binderfs_minors, device->minor);
266
	mutex_unlock(&binderfs_minors_mutex);
267

268
	/* ctx is null for binder-control, but this function ignores null pointers */
269
	rust_binder_remove_context(device->ctx);
270

271
	kfree(device);
272
}
273

274
static int binderfs_fs_context_parse_param(struct fs_context *fc,
275
					   struct fs_parameter *param)
276
{
277
	int opt;
278
	struct binderfs_mount_opts *ctx = fc->fs_private;
279
	struct fs_parse_result result;
280

281
	opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
282
	if (opt < 0)
283
		return opt;
284

285
	switch (opt) {
286
	case Opt_max:
287
		if (result.uint_32 > BINDERFS_MAX_MINOR)
288
			return invalfc(fc, "Bad value for '%s'", param->key);
289

290
		ctx->max = result.uint_32;
291
		break;
292
	case Opt_stats_mode:
293
		if (!capable(CAP_SYS_ADMIN))
294
			return -EPERM;
295

296
		ctx->stats_mode = result.uint_32;
297
		break;
298
	default:
299
		return invalfc(fc, "Unsupported parameter '%s'", param->key);
300
	}
301

302
	return 0;
303
}
304

305
static int binderfs_fs_context_reconfigure(struct fs_context *fc)
306
{
307
	struct binderfs_mount_opts *ctx = fc->fs_private;
308
	struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
309

310
	if (info->mount_opts.stats_mode != ctx->stats_mode)
311
		return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
312

313
	info->mount_opts.stats_mode = ctx->stats_mode;
314
	info->mount_opts.max = ctx->max;
315
	return 0;
316
}
317

318
static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
319
{
320
	struct binderfs_info *info = BINDERFS_SB(root->d_sb);
321

322
	if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
323
		seq_printf(seq, ",max=%d", info->mount_opts.max);
324

325
	switch (info->mount_opts.stats_mode) {
326
	case binderfs_stats_mode_unset:
327
		break;
328
	case binderfs_stats_mode_global:
329
		seq_puts(seq, ",stats=global");
330
		break;
331
	}
332

333
	return 0;
334
}
335

336
static const struct super_operations binderfs_super_ops = {
337
	.evict_inode    = binderfs_evict_inode,
338
	.show_options	= binderfs_show_options,
339
	.statfs         = simple_statfs,
340
};
341

342
static inline bool is_binderfs_control_device(const struct dentry *dentry)
343
{
344
	struct binderfs_info *info = dentry->d_sb->s_fs_info;
345

346
	return info->control_dentry == dentry;
347
}
348

349
static int binderfs_rename(struct mnt_idmap *idmap,
350
			   struct inode *old_dir, struct dentry *old_dentry,
351
			   struct inode *new_dir, struct dentry *new_dentry,
352
			   unsigned int flags)
353
{
354
	if (is_binderfs_control_device(old_dentry) ||
355
	    is_binderfs_control_device(new_dentry))
356
		return -EPERM;
357

358
	return simple_rename(idmap, old_dir, old_dentry, new_dir,
359
			     new_dentry, flags);
360
}
361

362
static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
363
{
364
	if (is_binderfs_control_device(dentry))
365
		return -EPERM;
366

367
	return simple_unlink(dir, dentry);
368
}
369

370
static const struct file_operations binder_ctl_fops = {
371
	.owner		= THIS_MODULE,
372
	.open		= nonseekable_open,
373
	.unlocked_ioctl	= binder_ctl_ioctl,
374
	.compat_ioctl	= binder_ctl_ioctl,
375
	.llseek		= noop_llseek,
376
};
377

378
/**
379
 * binderfs_binder_ctl_create - create a new binder-control device
380
 * @sb: super block of the binderfs mount
381
 *
382
 * This function creates a new binder-control device node in the binderfs mount
383
 * referred to by @sb.
384
 *
385
 * Return: 0 on success, negative errno on failure
386
 */
387
static int binderfs_binder_ctl_create(struct super_block *sb)
388
{
389
	int minor, ret;
390
	struct dentry *dentry;
391
	struct binder_device *device;
392
	struct inode *inode = NULL;
393
	struct dentry *root = sb->s_root;
394
	struct binderfs_info *info = sb->s_fs_info;
395
#if defined(CONFIG_IPC_NS)
396
	bool use_reserve = (info->ipc_ns == &init_ipc_ns);
397
#else
398
	bool use_reserve = true;
399
#endif
400

401
	device = kzalloc(sizeof(*device), GFP_KERNEL);
402
	if (!device)
403
		return -ENOMEM;
404

405
	/* If we have already created a binder-control node, return. */
406
	if (info->control_dentry) {
407
		ret = 0;
408
		goto out;
409
	}
410

411
	ret = -ENOMEM;
412
	inode = new_inode(sb);
413
	if (!inode)
414
		goto out;
415

416
	/* Reserve a new minor number for the new device. */
417
	mutex_lock(&binderfs_minors_mutex);
418
	minor = ida_alloc_max(&binderfs_minors,
419
			      use_reserve ? BINDERFS_MAX_MINOR :
420
					    BINDERFS_MAX_MINOR_CAPPED,
421
			      GFP_KERNEL);
422
	mutex_unlock(&binderfs_minors_mutex);
423
	if (minor < 0) {
424
		ret = minor;
425
		goto out;
426
	}
427

428
	inode->i_ino = SECOND_INODE;
429
	simple_inode_init_ts(inode);
430
	init_special_inode(inode, S_IFCHR | 0600,
431
			   MKDEV(MAJOR(binderfs_dev), minor));
432
	inode->i_fop = &binder_ctl_fops;
433
	inode->i_uid = info->root_uid;
434
	inode->i_gid = info->root_gid;
435

436
	device->minor = minor;
437
	device->ctx = NULL;
438

439
	dentry = d_alloc_name(root, "binder-control");
440
	if (!dentry)
441
		goto out;
442

443
	inode->i_private = device;
444
	info->control_dentry = dentry;
445
	d_add(dentry, inode);
446

447
	return 0;
448

449
out:
450
	kfree(device);
451
	iput(inode);
452

453
	return ret;
454
}
455

456
static const struct inode_operations binderfs_dir_inode_operations = {
457
	.lookup = simple_lookup,
458
	.rename = binderfs_rename,
459
	.unlink = binderfs_unlink,
460
};
461

462
static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
463
{
464
	struct inode *ret;
465

466
	ret = new_inode(sb);
467
	if (ret) {
468
		ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
469
		ret->i_mode = mode;
470
		simple_inode_init_ts(ret);
471
	}
472
	return ret;
473
}
474

475
static struct dentry *binderfs_create_dentry(struct dentry *parent,
476
					     const char *name)
477
{
478
	struct dentry *dentry;
479

480
	dentry = lookup_noperm(&QSTR(name), parent);
481
	if (IS_ERR(dentry))
482
		return dentry;
483

484
	/* Return error if the file/dir already exists. */
485
	if (d_really_is_positive(dentry)) {
486
		dput(dentry);
487
		return ERR_PTR(-EEXIST);
488
	}
489

490
	return dentry;
491
}
492

493
void rust_binderfs_remove_file(struct dentry *dentry)
494
{
495
	struct inode *parent_inode;
496

497
	parent_inode = d_inode(dentry->d_parent);
498
	inode_lock(parent_inode);
499
	if (simple_positive(dentry)) {
500
		dget(dentry);
501
		simple_unlink(parent_inode, dentry);
502
		d_delete(dentry);
503
		dput(dentry);
504
	}
505
	inode_unlock(parent_inode);
506
}
507

508
static struct dentry *rust_binderfs_create_file(struct dentry *parent, const char *name,
509
						const struct file_operations *fops,
510
						void *data)
511
{
512
	struct dentry *dentry;
513
	struct inode *new_inode, *parent_inode;
514
	struct super_block *sb;
515

516
	parent_inode = d_inode(parent);
517
	inode_lock(parent_inode);
518

519
	dentry = binderfs_create_dentry(parent, name);
520
	if (IS_ERR(dentry))
521
		goto out;
522

523
	sb = parent_inode->i_sb;
524
	new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
525
	if (!new_inode) {
526
		dput(dentry);
527
		dentry = ERR_PTR(-ENOMEM);
528
		goto out;
529
	}
530

531
	new_inode->i_fop = fops;
532
	new_inode->i_private = data;
533
	d_instantiate(dentry, new_inode);
534
	fsnotify_create(parent_inode, dentry);
535

536
out:
537
	inode_unlock(parent_inode);
538
	return dentry;
539
}
540

541
struct dentry *rust_binderfs_create_proc_file(struct inode *nodp, int pid)
542
{
543
	struct binderfs_info *info = nodp->i_sb->s_fs_info;
544
	struct dentry *dir = info->proc_log_dir;
545
	char strbuf[20 + 1];
546
	void *data = (void *)(unsigned long) pid;
547

548
	if (!dir)
549
		return NULL;
550

551
	snprintf(strbuf, sizeof(strbuf), "%u", pid);
552
	return rust_binderfs_create_file(dir, strbuf, &rust_binder_proc_fops, data);
553
}
554

555
static struct dentry *binderfs_create_dir(struct dentry *parent,
556
					  const char *name)
557
{
558
	struct dentry *dentry;
559
	struct inode *new_inode, *parent_inode;
560
	struct super_block *sb;
561

562
	parent_inode = d_inode(parent);
563
	inode_lock(parent_inode);
564

565
	dentry = binderfs_create_dentry(parent, name);
566
	if (IS_ERR(dentry))
567
		goto out;
568

569
	sb = parent_inode->i_sb;
570
	new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
571
	if (!new_inode) {
572
		dput(dentry);
573
		dentry = ERR_PTR(-ENOMEM);
574
		goto out;
575
	}
576

577
	new_inode->i_fop = &simple_dir_operations;
578
	new_inode->i_op = &simple_dir_inode_operations;
579

580
	set_nlink(new_inode, 2);
581
	d_instantiate(dentry, new_inode);
582
	inc_nlink(parent_inode);
583
	fsnotify_mkdir(parent_inode, dentry);
584

585
out:
586
	inode_unlock(parent_inode);
587
	return dentry;
588
}
589

590
static int binder_features_show(struct seq_file *m, void *unused)
591
{
592
	bool *feature = m->private;
593

594
	seq_printf(m, "%d\n", *feature);
595

596
	return 0;
597
}
598
DEFINE_SHOW_ATTRIBUTE(binder_features);
599

600
static int init_binder_features(struct super_block *sb)
601
{
602
	struct dentry *dentry, *dir;
603

604
	dir = binderfs_create_dir(sb->s_root, "features");
605
	if (IS_ERR(dir))
606
		return PTR_ERR(dir);
607

608
	dentry = rust_binderfs_create_file(dir, "oneway_spam_detection",
609
				      &binder_features_fops,
610
				      &binder_features.oneway_spam_detection);
611
	if (IS_ERR(dentry))
612
		return PTR_ERR(dentry);
613

614
	dentry = rust_binderfs_create_file(dir, "extended_error",
615
				      &binder_features_fops,
616
				      &binder_features.extended_error);
617
	if (IS_ERR(dentry))
618
		return PTR_ERR(dentry);
619

620
	dentry = rust_binderfs_create_file(dir, "freeze_notification",
621
				      &binder_features_fops,
622
				      &binder_features.freeze_notification);
623
	if (IS_ERR(dentry))
624
		return PTR_ERR(dentry);
625

626
	return 0;
627
}
628

629
static int init_binder_logs(struct super_block *sb)
630
{
631
	struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
632
	struct binderfs_info *info;
633
	int ret = 0;
634

635
	binder_logs_root_dir = binderfs_create_dir(sb->s_root,
636
						   "binder_logs");
637
	if (IS_ERR(binder_logs_root_dir)) {
638
		ret = PTR_ERR(binder_logs_root_dir);
639
		goto out;
640
	}
641

642
	dentry = rust_binderfs_create_file(binder_logs_root_dir, "stats",
643
				      &rust_binder_stats_fops, NULL);
644
	if (IS_ERR(dentry)) {
645
		ret = PTR_ERR(dentry);
646
		goto out;
647
	}
648

649
	dentry = rust_binderfs_create_file(binder_logs_root_dir, "state",
650
				      &rust_binder_state_fops, NULL);
651
	if (IS_ERR(dentry)) {
652
		ret = PTR_ERR(dentry);
653
		goto out;
654
	}
655

656
	dentry = rust_binderfs_create_file(binder_logs_root_dir, "transactions",
657
				      &rust_binder_transactions_fops, NULL);
658
	if (IS_ERR(dentry)) {
659
		ret = PTR_ERR(dentry);
660
		goto out;
661
	}
662

663
	proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
664
	if (IS_ERR(proc_log_dir)) {
665
		ret = PTR_ERR(proc_log_dir);
666
		goto out;
667
	}
668
	info = sb->s_fs_info;
669
	info->proc_log_dir = proc_log_dir;
670

671
out:
672
	return ret;
673
}
674

675
static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
676
{
677
	int ret;
678
	struct binderfs_info *info;
679
	struct binderfs_mount_opts *ctx = fc->fs_private;
680
	struct inode *inode = NULL;
681
	struct binderfs_device device_info = {};
682
	const char *name;
683
	size_t len;
684

685
	sb->s_blocksize = PAGE_SIZE;
686
	sb->s_blocksize_bits = PAGE_SHIFT;
687

688
	/*
689
	 * The binderfs filesystem can be mounted by userns root in a
690
	 * non-initial userns. By default such mounts have the SB_I_NODEV flag
691
	 * set in s_iflags to prevent security issues where userns root can
692
	 * just create random device nodes via mknod() since it owns the
693
	 * filesystem mount. But binderfs does not allow to create any files
694
	 * including devices nodes. The only way to create binder devices nodes
695
	 * is through the binder-control device which userns root is explicitly
696
	 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
697
	 * necessary and safe.
698
	 */
699
	sb->s_iflags &= ~SB_I_NODEV;
700
	sb->s_iflags |= SB_I_NOEXEC;
701
	sb->s_magic = RUST_BINDERFS_SUPER_MAGIC;
702
	sb->s_op = &binderfs_super_ops;
703
	sb->s_time_gran = 1;
704

705
	sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
706
	if (!sb->s_fs_info)
707
		return -ENOMEM;
708
	info = sb->s_fs_info;
709

710
	info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
711

712
	info->root_gid = make_kgid(sb->s_user_ns, 0);
713
	if (!gid_valid(info->root_gid))
714
		info->root_gid = GLOBAL_ROOT_GID;
715
	info->root_uid = make_kuid(sb->s_user_ns, 0);
716
	if (!uid_valid(info->root_uid))
717
		info->root_uid = GLOBAL_ROOT_UID;
718
	info->mount_opts.max = ctx->max;
719
	info->mount_opts.stats_mode = ctx->stats_mode;
720

721
	inode = new_inode(sb);
722
	if (!inode)
723
		return -ENOMEM;
724

725
	inode->i_ino = FIRST_INODE;
726
	inode->i_fop = &simple_dir_operations;
727
	inode->i_mode = S_IFDIR | 0755;
728
	simple_inode_init_ts(inode);
729
	inode->i_op = &binderfs_dir_inode_operations;
730
	set_nlink(inode, 2);
731

732
	sb->s_root = d_make_root(inode);
733
	if (!sb->s_root)
734
		return -ENOMEM;
735

736
	ret = binderfs_binder_ctl_create(sb);
737
	if (ret)
738
		return ret;
739

740
	name = rust_binder_devices_param;
741
	for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
742
		strscpy(device_info.name, name, len + 1);
743
		ret = binderfs_binder_device_create(inode, NULL, &device_info);
744
		if (ret)
745
			return ret;
746
		name += len;
747
		if (*name == ',')
748
			name++;
749
	}
750

751
	ret = init_binder_features(sb);
752
	if (ret)
753
		return ret;
754

755
	if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
756
		return init_binder_logs(sb);
757

758
	return 0;
759
}
760

761
static int binderfs_fs_context_get_tree(struct fs_context *fc)
762
{
763
	return get_tree_nodev(fc, binderfs_fill_super);
764
}
765

766
static void binderfs_fs_context_free(struct fs_context *fc)
767
{
768
	struct binderfs_mount_opts *ctx = fc->fs_private;
769

770
	kfree(ctx);
771
}
772

773
static const struct fs_context_operations binderfs_fs_context_ops = {
774
	.free		= binderfs_fs_context_free,
775
	.get_tree	= binderfs_fs_context_get_tree,
776
	.parse_param	= binderfs_fs_context_parse_param,
777
	.reconfigure	= binderfs_fs_context_reconfigure,
778
};
779

780
static int binderfs_init_fs_context(struct fs_context *fc)
781
{
782
	struct binderfs_mount_opts *ctx;
783

784
	ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
785
	if (!ctx)
786
		return -ENOMEM;
787

788
	ctx->max = BINDERFS_MAX_MINOR;
789
	ctx->stats_mode = binderfs_stats_mode_unset;
790

791
	fc->fs_private = ctx;
792
	fc->ops = &binderfs_fs_context_ops;
793

794
	return 0;
795
}
796

797
static void binderfs_kill_super(struct super_block *sb)
798
{
799
	struct binderfs_info *info = sb->s_fs_info;
800

801
	/*
802
	 * During inode eviction struct binderfs_info is needed.
803
	 * So first wipe the super_block then free struct binderfs_info.
804
	 */
805
	kill_litter_super(sb);
806

807
	if (info && info->ipc_ns)
808
		put_ipc_ns(info->ipc_ns);
809

810
	kfree(info);
811
}
812

813
static struct file_system_type binder_fs_type = {
814
	.name			= "binder",
815
	.init_fs_context	= binderfs_init_fs_context,
816
	.parameters		= binderfs_fs_parameters,
817
	.kill_sb		= binderfs_kill_super,
818
	.fs_flags		= FS_USERNS_MOUNT,
819
};
820

821
int init_rust_binderfs(void)
822
{
823
	int ret;
824
	const char *name;
825
	size_t len;
826

827
	/* Verify that the default binderfs device names are valid. */
828
	name = rust_binder_devices_param;
829
	for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
830
		if (len > BINDERFS_MAX_NAME)
831
			return -E2BIG;
832
		name += len;
833
		if (*name == ',')
834
			name++;
835
	}
836

837
	/* Allocate new major number for binderfs. */
838
	ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
839
				  "rust_binder");
840
	if (ret)
841
		return ret;
842

843
	ret = register_filesystem(&binder_fs_type);
844
	if (ret) {
845
		unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
846
		return ret;
847
	}
848

849
	return ret;
850
}
851

852