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(ida: &binderfs_minors,
134 max: 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(lock: &binderfs_minors_mutex);
142 return minor;
143 }
144 mutex_unlock(lock: &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(r: &device->ref, n: 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(to: userp, from: req, n: sizeof(*req))) {
182 ret = -EFAULT;
183 goto err;
184 }
185
186 root = sb->s_root;
187 inode_lock(inode: d_inode(dentry: root));
188
189 /* look it up */
190 dentry = lookup_noperm(&QSTR(name), root);
191 if (IS_ERR(ptr: dentry)) {
192 inode_unlock(inode: d_inode(dentry: root));
193 ret = PTR_ERR(ptr: dentry);
194 goto err;
195 }
196
197 if (d_really_is_positive(dentry)) {
198 /* already exists */
199 dput(dentry);
200 inode_unlock(inode: d_inode(dentry: root));
201 ret = -EEXIST;
202 goto err;
203 }
204
205 inode->i_private = device;
206 d_instantiate(dentry, inode);
207 fsnotify_create(dir: root->d_inode, dentry);
208 inode_unlock(inode: d_inode(dentry: root));
209
210 binder_add_device(device);
211
212 return 0;
213
214err:
215 kfree(objp: name);
216 kfree(objp: device);
217 mutex_lock(&binderfs_minors_mutex);
218 --info->device_count;
219 ida_free(&binderfs_minors, id: minor);
220 mutex_unlock(lock: &binderfs_minors_mutex);
221 iput(inode);
222
223 return ret;
224}
225
226/**
227 * binder_ctl_ioctl - handle binder device node allocation requests
228 *
229 * The request handler for the binder-control device. All requests operate on
230 * the binderfs mount the binder-control device resides in:
231 * - BINDER_CTL_ADD
232 * Allocate a new binder device.
233 *
234 * Return: %0 on success, negative errno on failure.
235 */
236static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
237 unsigned long arg)
238{
239 int ret = -EINVAL;
240 struct inode *inode = file_inode(f: file);
241 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
242 struct binderfs_device device_req;
243
244 switch (cmd) {
245 case BINDER_CTL_ADD:
246 ret = copy_from_user(to: &device_req, from: device, n: sizeof(device_req));
247 if (ret) {
248 ret = -EFAULT;
249 break;
250 }
251
252 ret = binderfs_binder_device_create(ref_inode: inode, userp: device, req: &device_req);
253 break;
254 default:
255 break;
256 }
257
258 return ret;
259}
260
261static void binderfs_evict_inode(struct inode *inode)
262{
263 struct binder_device *device = inode->i_private;
264 struct binderfs_info *info = BINDERFS_SB(sb: inode->i_sb);
265
266 clear_inode(inode);
267
268 if (!S_ISCHR(inode->i_mode) || !device)
269 return;
270
271 mutex_lock(&binderfs_minors_mutex);
272 --info->device_count;
273 ida_free(&binderfs_minors, id: device->miscdev.minor);
274 mutex_unlock(lock: &binderfs_minors_mutex);
275
276 if (refcount_dec_and_test(r: &device->ref)) {
277 binder_remove_device(device);
278 kfree(objp: device->context.name);
279 kfree(objp: device);
280 }
281}
282
283static int binderfs_fs_context_parse_param(struct fs_context *fc,
284 struct fs_parameter *param)
285{
286 int opt;
287 struct binderfs_mount_opts *ctx = fc->fs_private;
288 struct fs_parse_result result;
289
290 opt = fs_parse(fc, desc: binderfs_fs_parameters, param, result: &result);
291 if (opt < 0)
292 return opt;
293
294 switch (opt) {
295 case Opt_max:
296 if (result.uint_32 > BINDERFS_MAX_MINOR)
297 return invalfc(fc, "Bad value for '%s'", param->key);
298
299 ctx->max = result.uint_32;
300 break;
301 case Opt_stats_mode:
302 if (!capable(CAP_SYS_ADMIN))
303 return -EPERM;
304
305 ctx->stats_mode = result.uint_32;
306 break;
307 default:
308 return invalfc(fc, "Unsupported parameter '%s'", param->key);
309 }
310
311 return 0;
312}
313
314static int binderfs_fs_context_reconfigure(struct fs_context *fc)
315{
316 struct binderfs_mount_opts *ctx = fc->fs_private;
317 struct binderfs_info *info = BINDERFS_SB(sb: fc->root->d_sb);
318
319 if (info->mount_opts.stats_mode != ctx->stats_mode)
320 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
321
322 info->mount_opts.stats_mode = ctx->stats_mode;
323 info->mount_opts.max = ctx->max;
324 return 0;
325}
326
327static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
328{
329 struct binderfs_info *info = BINDERFS_SB(sb: root->d_sb);
330
331 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
332 seq_printf(m: seq, fmt: ",max=%d", info->mount_opts.max);
333
334 switch (info->mount_opts.stats_mode) {
335 case binderfs_stats_mode_unset:
336 break;
337 case binderfs_stats_mode_global:
338 seq_printf(m: seq, fmt: ",stats=global");
339 break;
340 }
341
342 return 0;
343}
344
345static const struct super_operations binderfs_super_ops = {
346 .evict_inode = binderfs_evict_inode,
347 .show_options = binderfs_show_options,
348 .statfs = simple_statfs,
349};
350
351static inline bool is_binderfs_control_device(const struct dentry *dentry)
352{
353 struct binderfs_info *info = dentry->d_sb->s_fs_info;
354
355 return info->control_dentry == dentry;
356}
357
358static int binderfs_rename(struct mnt_idmap *idmap,
359 struct inode *old_dir, struct dentry *old_dentry,
360 struct inode *new_dir, struct dentry *new_dentry,
361 unsigned int flags)
362{
363 if (is_binderfs_control_device(dentry: old_dentry) ||
364 is_binderfs_control_device(dentry: new_dentry))
365 return -EPERM;
366
367 return simple_rename(idmap, old_dir, old_dentry, new_dir,
368 new_dentry, flags);
369}
370
371static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
372{
373 if (is_binderfs_control_device(dentry))
374 return -EPERM;
375
376 return simple_unlink(dir, dentry);
377}
378
379static const struct file_operations binder_ctl_fops = {
380 .owner = THIS_MODULE,
381 .open = nonseekable_open,
382 .unlocked_ioctl = binder_ctl_ioctl,
383 .compat_ioctl = binder_ctl_ioctl,
384 .llseek = noop_llseek,
385};
386
387/**
388 * binderfs_binder_ctl_create - create a new binder-control device
389 * @sb: super block of the binderfs mount
390 *
391 * This function creates a new binder-control device node in the binderfs mount
392 * referred to by @sb.
393 *
394 * Return: 0 on success, negative errno on failure
395 */
396static int binderfs_binder_ctl_create(struct super_block *sb)
397{
398 int minor, ret;
399 struct dentry *dentry;
400 struct binder_device *device;
401 struct inode *inode = NULL;
402 struct dentry *root = sb->s_root;
403 struct binderfs_info *info = sb->s_fs_info;
404#if defined(CONFIG_IPC_NS)
405 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
406#else
407 bool use_reserve = true;
408#endif
409
410 device = kzalloc(sizeof(*device), GFP_KERNEL);
411 if (!device)
412 return -ENOMEM;
413
414 /* If we have already created a binder-control node, return. */
415 if (info->control_dentry) {
416 ret = 0;
417 goto out;
418 }
419
420 ret = -ENOMEM;
421 inode = new_inode(sb);
422 if (!inode)
423 goto out;
424
425 /* Reserve a new minor number for the new device. */
426 mutex_lock(&binderfs_minors_mutex);
427 minor = ida_alloc_max(ida: &binderfs_minors,
428 max: use_reserve ? BINDERFS_MAX_MINOR :
429 BINDERFS_MAX_MINOR_CAPPED,
430 GFP_KERNEL);
431 mutex_unlock(lock: &binderfs_minors_mutex);
432 if (minor < 0) {
433 ret = minor;
434 goto out;
435 }
436
437 inode->i_ino = SECOND_INODE;
438 simple_inode_init_ts(inode);
439 init_special_inode(inode, S_IFCHR | 0600,
440 MKDEV(MAJOR(binderfs_dev), minor));
441 inode->i_fop = &binder_ctl_fops;
442 inode->i_uid = info->root_uid;
443 inode->i_gid = info->root_gid;
444
445 refcount_set(r: &device->ref, n: 1);
446 device->binderfs_inode = inode;
447 device->miscdev.minor = minor;
448
449 dentry = d_alloc_name(root, "binder-control");
450 if (!dentry)
451 goto out;
452
453 inode->i_private = device;
454 info->control_dentry = dentry;
455 d_add(dentry, inode);
456
457 return 0;
458
459out:
460 kfree(objp: device);
461 iput(inode);
462
463 return ret;
464}
465
466static const struct inode_operations binderfs_dir_inode_operations = {
467 .lookup = simple_lookup,
468 .rename = binderfs_rename,
469 .unlink = binderfs_unlink,
470};
471
472static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
473{
474 struct inode *ret;
475
476 ret = new_inode(sb);
477 if (ret) {
478 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
479 ret->i_mode = mode;
480 simple_inode_init_ts(inode: ret);
481 }
482 return ret;
483}
484
485static struct dentry *binderfs_create_dentry(struct dentry *parent,
486 const char *name)
487{
488 struct dentry *dentry;
489
490 dentry = lookup_noperm(&QSTR(name), parent);
491 if (IS_ERR(ptr: dentry))
492 return dentry;
493
494 /* Return error if the file/dir already exists. */
495 if (d_really_is_positive(dentry)) {
496 dput(dentry);
497 return ERR_PTR(error: -EEXIST);
498 }
499
500 return dentry;
501}
502
503void binderfs_remove_file(struct dentry *dentry)
504{
505 struct inode *parent_inode;
506
507 parent_inode = d_inode(dentry: dentry->d_parent);
508 inode_lock(inode: parent_inode);
509 if (simple_positive(dentry)) {
510 dget(dentry);
511 simple_unlink(parent_inode, dentry);
512 d_delete(dentry);
513 dput(dentry);
514 }
515 inode_unlock(inode: parent_inode);
516}
517
518struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
519 const struct file_operations *fops,
520 void *data)
521{
522 struct dentry *dentry;
523 struct inode *new_inode, *parent_inode;
524 struct super_block *sb;
525
526 parent_inode = d_inode(dentry: parent);
527 inode_lock(inode: parent_inode);
528
529 dentry = binderfs_create_dentry(parent, name);
530 if (IS_ERR(ptr: dentry))
531 goto out;
532
533 sb = parent_inode->i_sb;
534 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
535 if (!new_inode) {
536 dput(dentry);
537 dentry = ERR_PTR(error: -ENOMEM);
538 goto out;
539 }
540
541 new_inode->i_fop = fops;
542 new_inode->i_private = data;
543 d_instantiate(dentry, new_inode);
544 fsnotify_create(dir: parent_inode, dentry);
545
546out:
547 inode_unlock(inode: parent_inode);
548 return dentry;
549}
550
551static struct dentry *binderfs_create_dir(struct dentry *parent,
552 const char *name)
553{
554 struct dentry *dentry;
555 struct inode *new_inode, *parent_inode;
556 struct super_block *sb;
557
558 parent_inode = d_inode(dentry: parent);
559 inode_lock(inode: parent_inode);
560
561 dentry = binderfs_create_dentry(parent, name);
562 if (IS_ERR(ptr: dentry))
563 goto out;
564
565 sb = parent_inode->i_sb;
566 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
567 if (!new_inode) {
568 dput(dentry);
569 dentry = ERR_PTR(error: -ENOMEM);
570 goto out;
571 }
572
573 new_inode->i_fop = &simple_dir_operations;
574 new_inode->i_op = &simple_dir_inode_operations;
575
576 set_nlink(inode: new_inode, nlink: 2);
577 d_instantiate(dentry, new_inode);
578 inc_nlink(inode: parent_inode);
579 fsnotify_mkdir(dir: parent_inode, dentry);
580
581out:
582 inode_unlock(inode: parent_inode);
583 return dentry;
584}
585
586static int binder_features_show(struct seq_file *m, void *unused)
587{
588 bool *feature = m->private;
589
590 seq_printf(m, fmt: "%d\n", *feature);
591
592 return 0;
593}
594DEFINE_SHOW_ATTRIBUTE(binder_features);
595
596static int init_binder_features(struct super_block *sb)
597{
598 struct dentry *dentry, *dir;
599
600 dir = binderfs_create_dir(parent: sb->s_root, name: "features");
601 if (IS_ERR(ptr: dir))
602 return PTR_ERR(ptr: dir);
603
604 dentry = binderfs_create_file(parent: dir, name: "oneway_spam_detection",
605 fops: &binder_features_fops,
606 data: &binder_features.oneway_spam_detection);
607 if (IS_ERR(ptr: dentry))
608 return PTR_ERR(ptr: dentry);
609
610 dentry = binderfs_create_file(parent: dir, name: "extended_error",
611 fops: &binder_features_fops,
612 data: &binder_features.extended_error);
613 if (IS_ERR(ptr: dentry))
614 return PTR_ERR(ptr: dentry);
615
616 dentry = binderfs_create_file(parent: dir, name: "freeze_notification",
617 fops: &binder_features_fops,
618 data: &binder_features.freeze_notification);
619 if (IS_ERR(ptr: dentry))
620 return PTR_ERR(ptr: dentry);
621
622 return 0;
623}
624
625static int init_binder_logs(struct super_block *sb)
626{
627 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
628 const struct binder_debugfs_entry *db_entry;
629 struct binderfs_info *info;
630 int ret = 0;
631
632 binder_logs_root_dir = binderfs_create_dir(parent: sb->s_root,
633 name: "binder_logs");
634 if (IS_ERR(ptr: binder_logs_root_dir)) {
635 ret = PTR_ERR(ptr: binder_logs_root_dir);
636 goto out;
637 }
638
639 binder_for_each_debugfs_entry(db_entry) {
640 dentry = binderfs_create_file(parent: binder_logs_root_dir,
641 name: db_entry->name,
642 fops: db_entry->fops,
643 data: db_entry->data);
644 if (IS_ERR(ptr: dentry)) {
645 ret = PTR_ERR(ptr: dentry);
646 goto out;
647 }
648 }
649
650 proc_log_dir = binderfs_create_dir(parent: binder_logs_root_dir, name: "proc");
651 if (IS_ERR(ptr: proc_log_dir)) {
652 ret = PTR_ERR(ptr: proc_log_dir);
653 goto out;
654 }
655 info = sb->s_fs_info;
656 info->proc_log_dir = proc_log_dir;
657
658out:
659 return ret;
660}
661
662static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
663{
664 int ret;
665 struct binderfs_info *info;
666 struct binderfs_mount_opts *ctx = fc->fs_private;
667 struct inode *inode = NULL;
668 struct binderfs_device device_info = {};
669 const char *name;
670 size_t len;
671
672 sb->s_blocksize = PAGE_SIZE;
673 sb->s_blocksize_bits = PAGE_SHIFT;
674
675 /*
676 * The binderfs filesystem can be mounted by userns root in a
677 * non-initial userns. By default such mounts have the SB_I_NODEV flag
678 * set in s_iflags to prevent security issues where userns root can
679 * just create random device nodes via mknod() since it owns the
680 * filesystem mount. But binderfs does not allow to create any files
681 * including devices nodes. The only way to create binder devices nodes
682 * is through the binder-control device which userns root is explicitly
683 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
684 * necessary and safe.
685 */
686 sb->s_iflags &= ~SB_I_NODEV;
687 sb->s_iflags |= SB_I_NOEXEC;
688 sb->s_magic = BINDERFS_SUPER_MAGIC;
689 sb->s_op = &binderfs_super_ops;
690 sb->s_time_gran = 1;
691
692 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
693 if (!sb->s_fs_info)
694 return -ENOMEM;
695 info = sb->s_fs_info;
696
697 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
698
699 info->root_gid = make_kgid(from: sb->s_user_ns, gid: 0);
700 if (!gid_valid(gid: info->root_gid))
701 info->root_gid = GLOBAL_ROOT_GID;
702 info->root_uid = make_kuid(sb->s_user_ns, 0);
703 if (!uid_valid(info->root_uid))
704 info->root_uid = GLOBAL_ROOT_UID;
705 info->mount_opts.max = ctx->max;
706 info->mount_opts.stats_mode = ctx->stats_mode;
707
708 inode = new_inode(sb);
709 if (!inode)
710 return -ENOMEM;
711
712 inode->i_ino = FIRST_INODE;
713 inode->i_fop = &simple_dir_operations;
714 inode->i_mode = S_IFDIR | 0755;
715 simple_inode_init_ts(inode);
716 inode->i_op = &binderfs_dir_inode_operations;
717 set_nlink(inode, 2);
718
719 sb->s_root = d_make_root(inode);
720 if (!sb->s_root)
721 return -ENOMEM;
722
723 ret = binderfs_binder_ctl_create(sb);
724 if (ret)
725 return ret;
726
727 name = binder_devices_param;
728 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
729 strscpy(device_info.name, name, len + 1);
730 ret = binderfs_binder_device_create(inode, NULL, &device_info);
731 if (ret)
732 return ret;
733 name += len;
734 if (*name == ',')
735 name++;
736 }
737
738 ret = init_binder_features(sb);
739 if (ret)
740 return ret;
741
742 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
743 return init_binder_logs(sb);
744
745 return 0;
746}
747
748static int binderfs_fs_context_get_tree(struct fs_context *fc)
749{
750 return get_tree_nodev(fc, fill_super: binderfs_fill_super);
751}
752
753static void binderfs_fs_context_free(struct fs_context *fc)
754{
755 struct binderfs_mount_opts *ctx = fc->fs_private;
756
757 kfree(objp: ctx);
758}
759
760static const struct fs_context_operations binderfs_fs_context_ops = {
761 .free = binderfs_fs_context_free,
762 .get_tree = binderfs_fs_context_get_tree,
763 .parse_param = binderfs_fs_context_parse_param,
764 .reconfigure = binderfs_fs_context_reconfigure,
765};
766
767static int binderfs_init_fs_context(struct fs_context *fc)
768{
769 struct binderfs_mount_opts *ctx;
770
771 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
772 if (!ctx)
773 return -ENOMEM;
774
775 ctx->max = BINDERFS_MAX_MINOR;
776 ctx->stats_mode = binderfs_stats_mode_unset;
777
778 fc->fs_private = ctx;
779 fc->ops = &binderfs_fs_context_ops;
780
781 return 0;
782}
783
784static void binderfs_kill_super(struct super_block *sb)
785{
786 struct binderfs_info *info = sb->s_fs_info;
787
788 /*
789 * During inode eviction struct binderfs_info is needed.
790 * So first wipe the super_block then free struct binderfs_info.
791 */
792 kill_litter_super(sb);
793
794 if (info && info->ipc_ns)
795 put_ipc_ns(ns: info->ipc_ns);
796
797 kfree(objp: info);
798}
799
800static struct file_system_type binder_fs_type = {
801 .name = "binder",
802 .init_fs_context = binderfs_init_fs_context,
803 .parameters = binderfs_fs_parameters,
804 .kill_sb = binderfs_kill_super,
805 .fs_flags = FS_USERNS_MOUNT,
806};
807
808int __init init_binderfs(void)
809{
810 int ret;
811 const char *name;
812 size_t len;
813
814 /* Verify that the default binderfs device names are valid. */
815 name = binder_devices_param;
816 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
817 if (len > BINDERFS_MAX_NAME)
818 return -E2BIG;
819 name += len;
820 if (*name == ',')
821 name++;
822 }
823
824 /* Allocate new major number for binderfs. */
825 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
826 "binder");
827 if (ret)
828 return ret;
829
830 ret = register_filesystem(&binder_fs_type);
831 if (ret) {
832 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
833 return ret;
834 }
835
836 return ret;
837}
838

source code of linux/drivers/android/binderfs.c

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