xref: /openbmc/linux/drivers/android/binderfs.c (revision a5702920)
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 "binder_internal.h"
37 
38 #define FIRST_INODE 1
39 #define SECOND_INODE 2
40 #define INODE_OFFSET 3
41 #define BINDERFS_MAX_MINOR (1U << MINORBITS)
42 /* Ensure that the initial ipc namespace always has devices available. */
43 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
44 
45 static dev_t binderfs_dev;
46 static DEFINE_MUTEX(binderfs_minors_mutex);
47 static DEFINE_IDA(binderfs_minors);
48 
49 enum binderfs_param {
50 	Opt_max,
51 	Opt_stats_mode,
52 };
53 
54 enum binderfs_stats_mode {
55 	binderfs_stats_mode_unset,
56 	binderfs_stats_mode_global,
57 };
58 
59 struct binder_features {
60 	bool oneway_spam_detection;
61 	bool extended_error;
62 };
63 
64 static const struct constant_table binderfs_param_stats[] = {
65 	{ "global", binderfs_stats_mode_global },
66 	{}
67 };
68 
69 static 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 
75 static struct binder_features binder_features = {
76 	.oneway_spam_detection = true,
77 	.extended_error = true,
78 };
79 
BINDERFS_SB(const struct super_block * sb)80 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
81 {
82 	return sb->s_fs_info;
83 }
84 
is_binderfs_device(const struct inode * inode)85 bool is_binderfs_device(const struct inode *inode)
86 {
87 	if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
88 		return true;
89 
90 	return false;
91 }
92 
93 /**
94  * binderfs_binder_device_create - allocate inode from super block of a
95  *                                 binderfs mount
96  * @ref_inode: inode from wich the super block will be taken
97  * @userp:     buffer to copy information about new device for userspace to
98  * @req:       struct binderfs_device as copied from userspace
99  *
100  * This function allocates a new binder_device and reserves a new minor
101  * number for it.
102  * Minor numbers are limited and tracked globally in binderfs_minors. The
103  * function will stash a struct binder_device for the specific binder
104  * device in i_private of the inode.
105  * It will go on to allocate a new inode from the super block of the
106  * filesystem mount, stash a struct binder_device in its i_private field
107  * and attach a dentry to that inode.
108  *
109  * Return: 0 on success, negative errno on failure
110  */
binderfs_binder_device_create(struct inode * ref_inode,struct binderfs_device __user * userp,struct binderfs_device * req)111 static int binderfs_binder_device_create(struct inode *ref_inode,
112 					 struct binderfs_device __user *userp,
113 					 struct binderfs_device *req)
114 {
115 	int minor, ret;
116 	struct dentry *dentry, *root;
117 	struct binder_device *device;
118 	char *name = NULL;
119 	size_t name_len;
120 	struct inode *inode = NULL;
121 	struct super_block *sb = ref_inode->i_sb;
122 	struct binderfs_info *info = sb->s_fs_info;
123 #if defined(CONFIG_IPC_NS)
124 	bool use_reserve = (info->ipc_ns == &init_ipc_ns);
125 #else
126 	bool use_reserve = true;
127 #endif
128 
129 	/* Reserve new minor number for the new device. */
130 	mutex_lock(&binderfs_minors_mutex);
131 	if (++info->device_count <= info->mount_opts.max)
132 		minor = ida_alloc_max(&binderfs_minors,
133 				      use_reserve ? BINDERFS_MAX_MINOR :
134 						    BINDERFS_MAX_MINOR_CAPPED,
135 				      GFP_KERNEL);
136 	else
137 		minor = -ENOSPC;
138 	if (minor < 0) {
139 		--info->device_count;
140 		mutex_unlock(&binderfs_minors_mutex);
141 		return minor;
142 	}
143 	mutex_unlock(&binderfs_minors_mutex);
144 
145 	ret = -ENOMEM;
146 	device = kzalloc(sizeof(*device), GFP_KERNEL);
147 	if (!device)
148 		goto err;
149 
150 	inode = new_inode(sb);
151 	if (!inode)
152 		goto err;
153 
154 	inode->i_ino = minor + INODE_OFFSET;
155 	inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
156 	init_special_inode(inode, S_IFCHR | 0600,
157 			   MKDEV(MAJOR(binderfs_dev), minor));
158 	inode->i_fop = &binder_fops;
159 	inode->i_uid = info->root_uid;
160 	inode->i_gid = info->root_gid;
161 
162 	req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
163 	name_len = strlen(req->name);
164 	/* Make sure to include terminating NUL byte */
165 	name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
166 	if (!name)
167 		goto err;
168 
169 	refcount_set(&device->ref, 1);
170 	device->binderfs_inode = inode;
171 	device->context.binder_context_mgr_uid = INVALID_UID;
172 	device->context.name = name;
173 	device->miscdev.name = name;
174 	device->miscdev.minor = minor;
175 	mutex_init(&device->context.context_mgr_node_lock);
176 
177 	req->major = MAJOR(binderfs_dev);
178 	req->minor = minor;
179 
180 	if (userp && copy_to_user(userp, req, sizeof(*req))) {
181 		ret = -EFAULT;
182 		goto err;
183 	}
184 
185 	root = sb->s_root;
186 	inode_lock(d_inode(root));
187 
188 	/* look it up */
189 	dentry = lookup_one_len(name, root, name_len);
190 	if (IS_ERR(dentry)) {
191 		inode_unlock(d_inode(root));
192 		ret = PTR_ERR(dentry);
193 		goto err;
194 	}
195 
196 	if (d_really_is_positive(dentry)) {
197 		/* already exists */
198 		dput(dentry);
199 		inode_unlock(d_inode(root));
200 		ret = -EEXIST;
201 		goto err;
202 	}
203 
204 	inode->i_private = device;
205 	d_instantiate(dentry, inode);
206 	fsnotify_create(root->d_inode, dentry);
207 	inode_unlock(d_inode(root));
208 
209 	return 0;
210 
211 err:
212 	kfree(name);
213 	kfree(device);
214 	mutex_lock(&binderfs_minors_mutex);
215 	--info->device_count;
216 	ida_free(&binderfs_minors, minor);
217 	mutex_unlock(&binderfs_minors_mutex);
218 	iput(inode);
219 
220 	return ret;
221 }
222 
223 /**
224  * binder_ctl_ioctl - handle binder device node allocation requests
225  *
226  * The request handler for the binder-control device. All requests operate on
227  * the binderfs mount the binder-control device resides in:
228  * - BINDER_CTL_ADD
229  *   Allocate a new binder device.
230  *
231  * Return: %0 on success, negative errno on failure.
232  */
binder_ctl_ioctl(struct file * file,unsigned int cmd,unsigned long arg)233 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
234 			     unsigned long arg)
235 {
236 	int ret = -EINVAL;
237 	struct inode *inode = file_inode(file);
238 	struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
239 	struct binderfs_device device_req;
240 
241 	switch (cmd) {
242 	case BINDER_CTL_ADD:
243 		ret = copy_from_user(&device_req, device, sizeof(device_req));
244 		if (ret) {
245 			ret = -EFAULT;
246 			break;
247 		}
248 
249 		ret = binderfs_binder_device_create(inode, device, &device_req);
250 		break;
251 	default:
252 		break;
253 	}
254 
255 	return ret;
256 }
257 
binderfs_evict_inode(struct inode * inode)258 static void binderfs_evict_inode(struct inode *inode)
259 {
260 	struct binder_device *device = inode->i_private;
261 	struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
262 
263 	clear_inode(inode);
264 
265 	if (!S_ISCHR(inode->i_mode) || !device)
266 		return;
267 
268 	mutex_lock(&binderfs_minors_mutex);
269 	--info->device_count;
270 	ida_free(&binderfs_minors, device->miscdev.minor);
271 	mutex_unlock(&binderfs_minors_mutex);
272 
273 	if (refcount_dec_and_test(&device->ref)) {
274 		kfree(device->context.name);
275 		kfree(device);
276 	}
277 }
278 
binderfs_fs_context_parse_param(struct fs_context * fc,struct fs_parameter * param)279 static int binderfs_fs_context_parse_param(struct fs_context *fc,
280 					   struct fs_parameter *param)
281 {
282 	int opt;
283 	struct binderfs_mount_opts *ctx = fc->fs_private;
284 	struct fs_parse_result result;
285 
286 	opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
287 	if (opt < 0)
288 		return opt;
289 
290 	switch (opt) {
291 	case Opt_max:
292 		if (result.uint_32 > BINDERFS_MAX_MINOR)
293 			return invalfc(fc, "Bad value for '%s'", param->key);
294 
295 		ctx->max = result.uint_32;
296 		break;
297 	case Opt_stats_mode:
298 		if (!capable(CAP_SYS_ADMIN))
299 			return -EPERM;
300 
301 		ctx->stats_mode = result.uint_32;
302 		break;
303 	default:
304 		return invalfc(fc, "Unsupported parameter '%s'", param->key);
305 	}
306 
307 	return 0;
308 }
309 
binderfs_fs_context_reconfigure(struct fs_context * fc)310 static int binderfs_fs_context_reconfigure(struct fs_context *fc)
311 {
312 	struct binderfs_mount_opts *ctx = fc->fs_private;
313 	struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
314 
315 	if (info->mount_opts.stats_mode != ctx->stats_mode)
316 		return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
317 
318 	info->mount_opts.stats_mode = ctx->stats_mode;
319 	info->mount_opts.max = ctx->max;
320 	return 0;
321 }
322 
binderfs_show_options(struct seq_file * seq,struct dentry * root)323 static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
324 {
325 	struct binderfs_info *info = BINDERFS_SB(root->d_sb);
326 
327 	if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
328 		seq_printf(seq, ",max=%d", info->mount_opts.max);
329 
330 	switch (info->mount_opts.stats_mode) {
331 	case binderfs_stats_mode_unset:
332 		break;
333 	case binderfs_stats_mode_global:
334 		seq_printf(seq, ",stats=global");
335 		break;
336 	}
337 
338 	return 0;
339 }
340 
341 static const struct super_operations binderfs_super_ops = {
342 	.evict_inode    = binderfs_evict_inode,
343 	.show_options	= binderfs_show_options,
344 	.statfs         = simple_statfs,
345 };
346 
is_binderfs_control_device(const struct dentry * dentry)347 static inline bool is_binderfs_control_device(const struct dentry *dentry)
348 {
349 	struct binderfs_info *info = dentry->d_sb->s_fs_info;
350 
351 	return info->control_dentry == dentry;
352 }
353 
binderfs_rename(struct mnt_idmap * idmap,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)354 static int binderfs_rename(struct mnt_idmap *idmap,
355 			   struct inode *old_dir, struct dentry *old_dentry,
356 			   struct inode *new_dir, struct dentry *new_dentry,
357 			   unsigned int flags)
358 {
359 	if (is_binderfs_control_device(old_dentry) ||
360 	    is_binderfs_control_device(new_dentry))
361 		return -EPERM;
362 
363 	return simple_rename(idmap, old_dir, old_dentry, new_dir,
364 			     new_dentry, flags);
365 }
366 
binderfs_unlink(struct inode * dir,struct dentry * dentry)367 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
368 {
369 	if (is_binderfs_control_device(dentry))
370 		return -EPERM;
371 
372 	return simple_unlink(dir, dentry);
373 }
374 
375 static const struct file_operations binder_ctl_fops = {
376 	.owner		= THIS_MODULE,
377 	.open		= nonseekable_open,
378 	.unlocked_ioctl	= binder_ctl_ioctl,
379 	.compat_ioctl	= binder_ctl_ioctl,
380 	.llseek		= noop_llseek,
381 };
382 
383 /**
384  * binderfs_binder_ctl_create - create a new binder-control device
385  * @sb: super block of the binderfs mount
386  *
387  * This function creates a new binder-control device node in the binderfs mount
388  * referred to by @sb.
389  *
390  * Return: 0 on success, negative errno on failure
391  */
binderfs_binder_ctl_create(struct super_block * sb)392 static int binderfs_binder_ctl_create(struct super_block *sb)
393 {
394 	int minor, ret;
395 	struct dentry *dentry;
396 	struct binder_device *device;
397 	struct inode *inode = NULL;
398 	struct dentry *root = sb->s_root;
399 	struct binderfs_info *info = sb->s_fs_info;
400 #if defined(CONFIG_IPC_NS)
401 	bool use_reserve = (info->ipc_ns == &init_ipc_ns);
402 #else
403 	bool use_reserve = true;
404 #endif
405 
406 	device = kzalloc(sizeof(*device), GFP_KERNEL);
407 	if (!device)
408 		return -ENOMEM;
409 
410 	/* If we have already created a binder-control node, return. */
411 	if (info->control_dentry) {
412 		ret = 0;
413 		goto out;
414 	}
415 
416 	ret = -ENOMEM;
417 	inode = new_inode(sb);
418 	if (!inode)
419 		goto out;
420 
421 	/* Reserve a new minor number for the new device. */
422 	mutex_lock(&binderfs_minors_mutex);
423 	minor = ida_alloc_max(&binderfs_minors,
424 			      use_reserve ? BINDERFS_MAX_MINOR :
425 					    BINDERFS_MAX_MINOR_CAPPED,
426 			      GFP_KERNEL);
427 	mutex_unlock(&binderfs_minors_mutex);
428 	if (minor < 0) {
429 		ret = minor;
430 		goto out;
431 	}
432 
433 	inode->i_ino = SECOND_INODE;
434 	inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
435 	init_special_inode(inode, S_IFCHR | 0600,
436 			   MKDEV(MAJOR(binderfs_dev), minor));
437 	inode->i_fop = &binder_ctl_fops;
438 	inode->i_uid = info->root_uid;
439 	inode->i_gid = info->root_gid;
440 
441 	refcount_set(&device->ref, 1);
442 	device->binderfs_inode = inode;
443 	device->miscdev.minor = minor;
444 
445 	dentry = d_alloc_name(root, "binder-control");
446 	if (!dentry)
447 		goto out;
448 
449 	inode->i_private = device;
450 	info->control_dentry = dentry;
451 	d_add(dentry, inode);
452 
453 	return 0;
454 
455 out:
456 	kfree(device);
457 	iput(inode);
458 
459 	return ret;
460 }
461 
462 static const struct inode_operations binderfs_dir_inode_operations = {
463 	.lookup = simple_lookup,
464 	.rename = binderfs_rename,
465 	.unlink = binderfs_unlink,
466 };
467 
binderfs_make_inode(struct super_block * sb,int mode)468 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
469 {
470 	struct inode *ret;
471 
472 	ret = new_inode(sb);
473 	if (ret) {
474 		ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
475 		ret->i_mode = mode;
476 		ret->i_atime = ret->i_mtime = inode_set_ctime_current(ret);
477 	}
478 	return ret;
479 }
480 
binderfs_create_dentry(struct dentry * parent,const char * name)481 static struct dentry *binderfs_create_dentry(struct dentry *parent,
482 					     const char *name)
483 {
484 	struct dentry *dentry;
485 
486 	dentry = lookup_one_len(name, parent, strlen(name));
487 	if (IS_ERR(dentry))
488 		return dentry;
489 
490 	/* Return error if the file/dir already exists. */
491 	if (d_really_is_positive(dentry)) {
492 		dput(dentry);
493 		return ERR_PTR(-EEXIST);
494 	}
495 
496 	return dentry;
497 }
498 
binderfs_remove_file(struct dentry * dentry)499 void binderfs_remove_file(struct dentry *dentry)
500 {
501 	struct inode *parent_inode;
502 
503 	parent_inode = d_inode(dentry->d_parent);
504 	inode_lock(parent_inode);
505 	if (simple_positive(dentry)) {
506 		dget(dentry);
507 		simple_unlink(parent_inode, dentry);
508 		d_delete(dentry);
509 		dput(dentry);
510 	}
511 	inode_unlock(parent_inode);
512 }
513 
binderfs_create_file(struct dentry * parent,const char * name,const struct file_operations * fops,void * data)514 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
515 				    const struct file_operations *fops,
516 				    void *data)
517 {
518 	struct dentry *dentry;
519 	struct inode *new_inode, *parent_inode;
520 	struct super_block *sb;
521 
522 	parent_inode = d_inode(parent);
523 	inode_lock(parent_inode);
524 
525 	dentry = binderfs_create_dentry(parent, name);
526 	if (IS_ERR(dentry))
527 		goto out;
528 
529 	sb = parent_inode->i_sb;
530 	new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
531 	if (!new_inode) {
532 		dput(dentry);
533 		dentry = ERR_PTR(-ENOMEM);
534 		goto out;
535 	}
536 
537 	new_inode->i_fop = fops;
538 	new_inode->i_private = data;
539 	d_instantiate(dentry, new_inode);
540 	fsnotify_create(parent_inode, dentry);
541 
542 out:
543 	inode_unlock(parent_inode);
544 	return dentry;
545 }
546 
binderfs_create_dir(struct dentry * parent,const char * name)547 static struct dentry *binderfs_create_dir(struct dentry *parent,
548 					  const char *name)
549 {
550 	struct dentry *dentry;
551 	struct inode *new_inode, *parent_inode;
552 	struct super_block *sb;
553 
554 	parent_inode = d_inode(parent);
555 	inode_lock(parent_inode);
556 
557 	dentry = binderfs_create_dentry(parent, name);
558 	if (IS_ERR(dentry))
559 		goto out;
560 
561 	sb = parent_inode->i_sb;
562 	new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
563 	if (!new_inode) {
564 		dput(dentry);
565 		dentry = ERR_PTR(-ENOMEM);
566 		goto out;
567 	}
568 
569 	new_inode->i_fop = &simple_dir_operations;
570 	new_inode->i_op = &simple_dir_inode_operations;
571 
572 	set_nlink(new_inode, 2);
573 	d_instantiate(dentry, new_inode);
574 	inc_nlink(parent_inode);
575 	fsnotify_mkdir(parent_inode, dentry);
576 
577 out:
578 	inode_unlock(parent_inode);
579 	return dentry;
580 }
581 
binder_features_show(struct seq_file * m,void * unused)582 static int binder_features_show(struct seq_file *m, void *unused)
583 {
584 	bool *feature = m->private;
585 
586 	seq_printf(m, "%d\n", *feature);
587 
588 	return 0;
589 }
590 DEFINE_SHOW_ATTRIBUTE(binder_features);
591 
init_binder_features(struct super_block * sb)592 static int init_binder_features(struct super_block *sb)
593 {
594 	struct dentry *dentry, *dir;
595 
596 	dir = binderfs_create_dir(sb->s_root, "features");
597 	if (IS_ERR(dir))
598 		return PTR_ERR(dir);
599 
600 	dentry = binderfs_create_file(dir, "oneway_spam_detection",
601 				      &binder_features_fops,
602 				      &binder_features.oneway_spam_detection);
603 	if (IS_ERR(dentry))
604 		return PTR_ERR(dentry);
605 
606 	dentry = binderfs_create_file(dir, "extended_error",
607 				      &binder_features_fops,
608 				      &binder_features.extended_error);
609 	if (IS_ERR(dentry))
610 		return PTR_ERR(dentry);
611 
612 	return 0;
613 }
614 
init_binder_logs(struct super_block * sb)615 static int init_binder_logs(struct super_block *sb)
616 {
617 	struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
618 	const struct binder_debugfs_entry *db_entry;
619 	struct binderfs_info *info;
620 	int ret = 0;
621 
622 	binder_logs_root_dir = binderfs_create_dir(sb->s_root,
623 						   "binder_logs");
624 	if (IS_ERR(binder_logs_root_dir)) {
625 		ret = PTR_ERR(binder_logs_root_dir);
626 		goto out;
627 	}
628 
629 	binder_for_each_debugfs_entry(db_entry) {
630 		dentry = binderfs_create_file(binder_logs_root_dir,
631 					      db_entry->name,
632 					      db_entry->fops,
633 					      db_entry->data);
634 		if (IS_ERR(dentry)) {
635 			ret = PTR_ERR(dentry);
636 			goto out;
637 		}
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 
648 out:
649 	return ret;
650 }
651 
binderfs_fill_super(struct super_block * sb,struct fs_context * fc)652 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
653 {
654 	int ret;
655 	struct binderfs_info *info;
656 	struct binderfs_mount_opts *ctx = fc->fs_private;
657 	struct inode *inode = NULL;
658 	struct binderfs_device device_info = {};
659 	const char *name;
660 	size_t len;
661 
662 	sb->s_blocksize = PAGE_SIZE;
663 	sb->s_blocksize_bits = PAGE_SHIFT;
664 
665 	/*
666 	 * The binderfs filesystem can be mounted by userns root in a
667 	 * non-initial userns. By default such mounts have the SB_I_NODEV flag
668 	 * set in s_iflags to prevent security issues where userns root can
669 	 * just create random device nodes via mknod() since it owns the
670 	 * filesystem mount. But binderfs does not allow to create any files
671 	 * including devices nodes. The only way to create binder devices nodes
672 	 * is through the binder-control device which userns root is explicitly
673 	 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
674 	 * necessary and safe.
675 	 */
676 	sb->s_iflags &= ~SB_I_NODEV;
677 	sb->s_iflags |= SB_I_NOEXEC;
678 	sb->s_magic = BINDERFS_SUPER_MAGIC;
679 	sb->s_op = &binderfs_super_ops;
680 	sb->s_time_gran = 1;
681 
682 	sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
683 	if (!sb->s_fs_info)
684 		return -ENOMEM;
685 	info = sb->s_fs_info;
686 
687 	info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
688 
689 	info->root_gid = make_kgid(sb->s_user_ns, 0);
690 	if (!gid_valid(info->root_gid))
691 		info->root_gid = GLOBAL_ROOT_GID;
692 	info->root_uid = make_kuid(sb->s_user_ns, 0);
693 	if (!uid_valid(info->root_uid))
694 		info->root_uid = GLOBAL_ROOT_UID;
695 	info->mount_opts.max = ctx->max;
696 	info->mount_opts.stats_mode = ctx->stats_mode;
697 
698 	inode = new_inode(sb);
699 	if (!inode)
700 		return -ENOMEM;
701 
702 	inode->i_ino = FIRST_INODE;
703 	inode->i_fop = &simple_dir_operations;
704 	inode->i_mode = S_IFDIR | 0755;
705 	inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
706 	inode->i_op = &binderfs_dir_inode_operations;
707 	set_nlink(inode, 2);
708 
709 	sb->s_root = d_make_root(inode);
710 	if (!sb->s_root)
711 		return -ENOMEM;
712 
713 	ret = binderfs_binder_ctl_create(sb);
714 	if (ret)
715 		return ret;
716 
717 	name = binder_devices_param;
718 	for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
719 		strscpy(device_info.name, name, len + 1);
720 		ret = binderfs_binder_device_create(inode, NULL, &device_info);
721 		if (ret)
722 			return ret;
723 		name += len;
724 		if (*name == ',')
725 			name++;
726 	}
727 
728 	ret = init_binder_features(sb);
729 	if (ret)
730 		return ret;
731 
732 	if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
733 		return init_binder_logs(sb);
734 
735 	return 0;
736 }
737 
binderfs_fs_context_get_tree(struct fs_context * fc)738 static int binderfs_fs_context_get_tree(struct fs_context *fc)
739 {
740 	return get_tree_nodev(fc, binderfs_fill_super);
741 }
742 
binderfs_fs_context_free(struct fs_context * fc)743 static void binderfs_fs_context_free(struct fs_context *fc)
744 {
745 	struct binderfs_mount_opts *ctx = fc->fs_private;
746 
747 	kfree(ctx);
748 }
749 
750 static const struct fs_context_operations binderfs_fs_context_ops = {
751 	.free		= binderfs_fs_context_free,
752 	.get_tree	= binderfs_fs_context_get_tree,
753 	.parse_param	= binderfs_fs_context_parse_param,
754 	.reconfigure	= binderfs_fs_context_reconfigure,
755 };
756 
binderfs_init_fs_context(struct fs_context * fc)757 static int binderfs_init_fs_context(struct fs_context *fc)
758 {
759 	struct binderfs_mount_opts *ctx;
760 
761 	ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
762 	if (!ctx)
763 		return -ENOMEM;
764 
765 	ctx->max = BINDERFS_MAX_MINOR;
766 	ctx->stats_mode = binderfs_stats_mode_unset;
767 
768 	fc->fs_private = ctx;
769 	fc->ops = &binderfs_fs_context_ops;
770 
771 	return 0;
772 }
773 
binderfs_kill_super(struct super_block * sb)774 static void binderfs_kill_super(struct super_block *sb)
775 {
776 	struct binderfs_info *info = sb->s_fs_info;
777 
778 	/*
779 	 * During inode eviction struct binderfs_info is needed.
780 	 * So first wipe the super_block then free struct binderfs_info.
781 	 */
782 	kill_litter_super(sb);
783 
784 	if (info && info->ipc_ns)
785 		put_ipc_ns(info->ipc_ns);
786 
787 	kfree(info);
788 }
789 
790 static struct file_system_type binder_fs_type = {
791 	.name			= "binder",
792 	.init_fs_context	= binderfs_init_fs_context,
793 	.parameters		= binderfs_fs_parameters,
794 	.kill_sb		= binderfs_kill_super,
795 	.fs_flags		= FS_USERNS_MOUNT,
796 };
797 
init_binderfs(void)798 int __init init_binderfs(void)
799 {
800 	int ret;
801 	const char *name;
802 	size_t len;
803 
804 	/* Verify that the default binderfs device names are valid. */
805 	name = binder_devices_param;
806 	for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
807 		if (len > BINDERFS_MAX_NAME)
808 			return -E2BIG;
809 		name += len;
810 		if (*name == ',')
811 			name++;
812 	}
813 
814 	/* Allocate new major number for binderfs. */
815 	ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
816 				  "binder");
817 	if (ret)
818 		return ret;
819 
820 	ret = register_filesystem(&binder_fs_type);
821 	if (ret) {
822 		unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
823 		return ret;
824 	}
825 
826 	return ret;
827 }
828