Loading...
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/radix-tree.h>
23#include <linux/sched.h>
24#include <linux/seq_file.h>
25#include <linux/slab.h>
26#include <linux/spinlock_types.h>
27#include <linux/stddef.h>
28#include <linux/string.h>
29#include <linux/types.h>
30#include <linux/uaccess.h>
31#include <linux/user_namespace.h>
32#include <linux/xarray.h>
33#include <uapi/asm-generic/errno-base.h>
34#include <uapi/linux/android/binder.h>
35#include <uapi/linux/android/binderfs.h>
36
37#include "binder_internal.h"
38
39#define FIRST_INODE 1
40#define SECOND_INODE 2
41#define INODE_OFFSET 3
42#define INTSTRLEN 21
43#define BINDERFS_MAX_MINOR (1U << MINORBITS)
44/* Ensure that the initial ipc namespace always has devices available. */
45#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
46
47static dev_t binderfs_dev;
48static DEFINE_MUTEX(binderfs_minors_mutex);
49static DEFINE_IDA(binderfs_minors);
50
51enum binderfs_param {
52 Opt_max,
53 Opt_stats_mode,
54};
55
56enum binderfs_stats_mode {
57 binderfs_stats_mode_unset,
58 binderfs_stats_mode_global,
59};
60
61static const struct constant_table binderfs_param_stats[] = {
62 { "global", binderfs_stats_mode_global },
63 {}
64};
65
66const struct fs_parameter_spec binderfs_fs_parameters[] = {
67 fsparam_u32("max", Opt_max),
68 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats),
69 {}
70};
71
72static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
73{
74 return sb->s_fs_info;
75}
76
77bool is_binderfs_device(const struct inode *inode)
78{
79 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
80 return true;
81
82 return false;
83}
84
85/**
86 * binderfs_binder_device_create - allocate inode from super block of a
87 * binderfs mount
88 * @ref_inode: inode from wich the super block will be taken
89 * @userp: buffer to copy information about new device for userspace to
90 * @req: struct binderfs_device as copied from userspace
91 *
92 * This function allocates a new binder_device and reserves a new minor
93 * number for it.
94 * Minor numbers are limited and tracked globally in binderfs_minors. The
95 * function will stash a struct binder_device for the specific binder
96 * device in i_private of the inode.
97 * It will go on to allocate a new inode from the super block of the
98 * filesystem mount, stash a struct binder_device in its i_private field
99 * and attach a dentry to that inode.
100 *
101 * Return: 0 on success, negative errno on failure
102 */
103static int binderfs_binder_device_create(struct inode *ref_inode,
104 struct binderfs_device __user *userp,
105 struct binderfs_device *req)
106{
107 int minor, ret;
108 struct dentry *dentry, *root;
109 struct binder_device *device;
110 char *name = NULL;
111 size_t name_len;
112 struct inode *inode = NULL;
113 struct super_block *sb = ref_inode->i_sb;
114 struct binderfs_info *info = sb->s_fs_info;
115#if defined(CONFIG_IPC_NS)
116 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
117#else
118 bool use_reserve = true;
119#endif
120
121 /* Reserve new minor number for the new device. */
122 mutex_lock(&binderfs_minors_mutex);
123 if (++info->device_count <= info->mount_opts.max)
124 minor = ida_alloc_max(&binderfs_minors,
125 use_reserve ? BINDERFS_MAX_MINOR :
126 BINDERFS_MAX_MINOR_CAPPED,
127 GFP_KERNEL);
128 else
129 minor = -ENOSPC;
130 if (minor < 0) {
131 --info->device_count;
132 mutex_unlock(&binderfs_minors_mutex);
133 return minor;
134 }
135 mutex_unlock(&binderfs_minors_mutex);
136
137 ret = -ENOMEM;
138 device = kzalloc(sizeof(*device), GFP_KERNEL);
139 if (!device)
140 goto err;
141
142 inode = new_inode(sb);
143 if (!inode)
144 goto err;
145
146 inode->i_ino = minor + INODE_OFFSET;
147 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
148 init_special_inode(inode, S_IFCHR | 0600,
149 MKDEV(MAJOR(binderfs_dev), minor));
150 inode->i_fop = &binder_fops;
151 inode->i_uid = info->root_uid;
152 inode->i_gid = info->root_gid;
153
154 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
155 name_len = strlen(req->name);
156 /* Make sure to include terminating NUL byte */
157 name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
158 if (!name)
159 goto err;
160
161 refcount_set(&device->ref, 1);
162 device->binderfs_inode = inode;
163 device->context.binder_context_mgr_uid = INVALID_UID;
164 device->context.name = name;
165 device->miscdev.name = name;
166 device->miscdev.minor = minor;
167 mutex_init(&device->context.context_mgr_node_lock);
168
169 req->major = MAJOR(binderfs_dev);
170 req->minor = minor;
171
172 if (userp && copy_to_user(userp, req, sizeof(*req))) {
173 ret = -EFAULT;
174 goto err;
175 }
176
177 root = sb->s_root;
178 inode_lock(d_inode(root));
179
180 /* look it up */
181 dentry = lookup_one_len(name, root, name_len);
182 if (IS_ERR(dentry)) {
183 inode_unlock(d_inode(root));
184 ret = PTR_ERR(dentry);
185 goto err;
186 }
187
188 if (d_really_is_positive(dentry)) {
189 /* already exists */
190 dput(dentry);
191 inode_unlock(d_inode(root));
192 ret = -EEXIST;
193 goto err;
194 }
195
196 inode->i_private = device;
197 d_instantiate(dentry, inode);
198 fsnotify_create(root->d_inode, dentry);
199 inode_unlock(d_inode(root));
200
201 return 0;
202
203err:
204 kfree(name);
205 kfree(device);
206 mutex_lock(&binderfs_minors_mutex);
207 --info->device_count;
208 ida_free(&binderfs_minors, minor);
209 mutex_unlock(&binderfs_minors_mutex);
210 iput(inode);
211
212 return ret;
213}
214
215/**
216 * binderfs_ctl_ioctl - handle binder device node allocation requests
217 *
218 * The request handler for the binder-control device. All requests operate on
219 * the binderfs mount the binder-control device resides in:
220 * - BINDER_CTL_ADD
221 * Allocate a new binder device.
222 *
223 * Return: 0 on success, negative errno on failure
224 */
225static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
226 unsigned long arg)
227{
228 int ret = -EINVAL;
229 struct inode *inode = file_inode(file);
230 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
231 struct binderfs_device device_req;
232
233 switch (cmd) {
234 case BINDER_CTL_ADD:
235 ret = copy_from_user(&device_req, device, sizeof(device_req));
236 if (ret) {
237 ret = -EFAULT;
238 break;
239 }
240
241 ret = binderfs_binder_device_create(inode, device, &device_req);
242 break;
243 default:
244 break;
245 }
246
247 return ret;
248}
249
250static void binderfs_evict_inode(struct inode *inode)
251{
252 struct binder_device *device = inode->i_private;
253 struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
254
255 clear_inode(inode);
256
257 if (!S_ISCHR(inode->i_mode) || !device)
258 return;
259
260 mutex_lock(&binderfs_minors_mutex);
261 --info->device_count;
262 ida_free(&binderfs_minors, device->miscdev.minor);
263 mutex_unlock(&binderfs_minors_mutex);
264
265 if (refcount_dec_and_test(&device->ref)) {
266 kfree(device->context.name);
267 kfree(device);
268 }
269}
270
271static int binderfs_fs_context_parse_param(struct fs_context *fc,
272 struct fs_parameter *param)
273{
274 int opt;
275 struct binderfs_mount_opts *ctx = fc->fs_private;
276 struct fs_parse_result result;
277
278 opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
279 if (opt < 0)
280 return opt;
281
282 switch (opt) {
283 case Opt_max:
284 if (result.uint_32 > BINDERFS_MAX_MINOR)
285 return invalfc(fc, "Bad value for '%s'", param->key);
286
287 ctx->max = result.uint_32;
288 break;
289 case Opt_stats_mode:
290 if (!capable(CAP_SYS_ADMIN))
291 return -EPERM;
292
293 ctx->stats_mode = result.uint_32;
294 break;
295 default:
296 return invalfc(fc, "Unsupported parameter '%s'", param->key);
297 }
298
299 return 0;
300}
301
302static int binderfs_fs_context_reconfigure(struct fs_context *fc)
303{
304 struct binderfs_mount_opts *ctx = fc->fs_private;
305 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
306
307 if (info->mount_opts.stats_mode != ctx->stats_mode)
308 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
309
310 info->mount_opts.stats_mode = ctx->stats_mode;
311 info->mount_opts.max = ctx->max;
312 return 0;
313}
314
315static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
316{
317 struct binderfs_info *info = BINDERFS_SB(root->d_sb);
318
319 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
320 seq_printf(seq, ",max=%d", info->mount_opts.max);
321
322 switch (info->mount_opts.stats_mode) {
323 case binderfs_stats_mode_unset:
324 break;
325 case binderfs_stats_mode_global:
326 seq_printf(seq, ",stats=global");
327 break;
328 }
329
330 return 0;
331}
332
333static void binderfs_put_super(struct super_block *sb)
334{
335 struct binderfs_info *info = sb->s_fs_info;
336
337 if (info && info->ipc_ns)
338 put_ipc_ns(info->ipc_ns);
339
340 kfree(info);
341 sb->s_fs_info = NULL;
342}
343
344static const struct super_operations binderfs_super_ops = {
345 .evict_inode = binderfs_evict_inode,
346 .show_options = binderfs_show_options,
347 .statfs = simple_statfs,
348 .put_super = binderfs_put_super,
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 inode *old_dir, struct dentry *old_dentry,
359 struct inode *new_dir, struct dentry *new_dentry,
360 unsigned int flags)
361{
362 if (is_binderfs_control_device(old_dentry) ||
363 is_binderfs_control_device(new_dentry))
364 return -EPERM;
365
366 return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
367}
368
369static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
370{
371 if (is_binderfs_control_device(dentry))
372 return -EPERM;
373
374 return simple_unlink(dir, dentry);
375}
376
377static const struct file_operations binder_ctl_fops = {
378 .owner = THIS_MODULE,
379 .open = nonseekable_open,
380 .unlocked_ioctl = binder_ctl_ioctl,
381 .compat_ioctl = binder_ctl_ioctl,
382 .llseek = noop_llseek,
383};
384
385/**
386 * binderfs_binder_ctl_create - create a new binder-control device
387 * @sb: super block of the binderfs mount
388 *
389 * This function creates a new binder-control device node in the binderfs mount
390 * referred to by @sb.
391 *
392 * Return: 0 on success, negative errno on failure
393 */
394static int binderfs_binder_ctl_create(struct super_block *sb)
395{
396 int minor, ret;
397 struct dentry *dentry;
398 struct binder_device *device;
399 struct inode *inode = NULL;
400 struct dentry *root = sb->s_root;
401 struct binderfs_info *info = sb->s_fs_info;
402#if defined(CONFIG_IPC_NS)
403 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
404#else
405 bool use_reserve = true;
406#endif
407
408 device = kzalloc(sizeof(*device), GFP_KERNEL);
409 if (!device)
410 return -ENOMEM;
411
412 /* If we have already created a binder-control node, return. */
413 if (info->control_dentry) {
414 ret = 0;
415 goto out;
416 }
417
418 ret = -ENOMEM;
419 inode = new_inode(sb);
420 if (!inode)
421 goto out;
422
423 /* Reserve a new minor number for the new device. */
424 mutex_lock(&binderfs_minors_mutex);
425 minor = ida_alloc_max(&binderfs_minors,
426 use_reserve ? BINDERFS_MAX_MINOR :
427 BINDERFS_MAX_MINOR_CAPPED,
428 GFP_KERNEL);
429 mutex_unlock(&binderfs_minors_mutex);
430 if (minor < 0) {
431 ret = minor;
432 goto out;
433 }
434
435 inode->i_ino = SECOND_INODE;
436 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
437 init_special_inode(inode, S_IFCHR | 0600,
438 MKDEV(MAJOR(binderfs_dev), minor));
439 inode->i_fop = &binder_ctl_fops;
440 inode->i_uid = info->root_uid;
441 inode->i_gid = info->root_gid;
442
443 refcount_set(&device->ref, 1);
444 device->binderfs_inode = inode;
445 device->miscdev.minor = minor;
446
447 dentry = d_alloc_name(root, "binder-control");
448 if (!dentry)
449 goto out;
450
451 inode->i_private = device;
452 info->control_dentry = dentry;
453 d_add(dentry, inode);
454
455 return 0;
456
457out:
458 kfree(device);
459 iput(inode);
460
461 return ret;
462}
463
464static const struct inode_operations binderfs_dir_inode_operations = {
465 .lookup = simple_lookup,
466 .rename = binderfs_rename,
467 .unlink = binderfs_unlink,
468};
469
470static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
471{
472 struct inode *ret;
473
474 ret = new_inode(sb);
475 if (ret) {
476 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
477 ret->i_mode = mode;
478 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
479 }
480 return ret;
481}
482
483static struct dentry *binderfs_create_dentry(struct dentry *parent,
484 const char *name)
485{
486 struct dentry *dentry;
487
488 dentry = lookup_one_len(name, parent, strlen(name));
489 if (IS_ERR(dentry))
490 return dentry;
491
492 /* Return error if the file/dir already exists. */
493 if (d_really_is_positive(dentry)) {
494 dput(dentry);
495 return ERR_PTR(-EEXIST);
496 }
497
498 return dentry;
499}
500
501void binderfs_remove_file(struct dentry *dentry)
502{
503 struct inode *parent_inode;
504
505 parent_inode = d_inode(dentry->d_parent);
506 inode_lock(parent_inode);
507 if (simple_positive(dentry)) {
508 dget(dentry);
509 simple_unlink(parent_inode, dentry);
510 d_delete(dentry);
511 dput(dentry);
512 }
513 inode_unlock(parent_inode);
514}
515
516struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
517 const struct file_operations *fops,
518 void *data)
519{
520 struct dentry *dentry;
521 struct inode *new_inode, *parent_inode;
522 struct super_block *sb;
523
524 parent_inode = d_inode(parent);
525 inode_lock(parent_inode);
526
527 dentry = binderfs_create_dentry(parent, name);
528 if (IS_ERR(dentry))
529 goto out;
530
531 sb = parent_inode->i_sb;
532 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
533 if (!new_inode) {
534 dput(dentry);
535 dentry = ERR_PTR(-ENOMEM);
536 goto out;
537 }
538
539 new_inode->i_fop = fops;
540 new_inode->i_private = data;
541 d_instantiate(dentry, new_inode);
542 fsnotify_create(parent_inode, dentry);
543
544out:
545 inode_unlock(parent_inode);
546 return dentry;
547}
548
549static struct dentry *binderfs_create_dir(struct dentry *parent,
550 const char *name)
551{
552 struct dentry *dentry;
553 struct inode *new_inode, *parent_inode;
554 struct super_block *sb;
555
556 parent_inode = d_inode(parent);
557 inode_lock(parent_inode);
558
559 dentry = binderfs_create_dentry(parent, name);
560 if (IS_ERR(dentry))
561 goto out;
562
563 sb = parent_inode->i_sb;
564 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
565 if (!new_inode) {
566 dput(dentry);
567 dentry = ERR_PTR(-ENOMEM);
568 goto out;
569 }
570
571 new_inode->i_fop = &simple_dir_operations;
572 new_inode->i_op = &simple_dir_inode_operations;
573
574 set_nlink(new_inode, 2);
575 d_instantiate(dentry, new_inode);
576 inc_nlink(parent_inode);
577 fsnotify_mkdir(parent_inode, dentry);
578
579out:
580 inode_unlock(parent_inode);
581 return dentry;
582}
583
584static int init_binder_logs(struct super_block *sb)
585{
586 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
587 struct binderfs_info *info;
588 int ret = 0;
589
590 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
591 "binder_logs");
592 if (IS_ERR(binder_logs_root_dir)) {
593 ret = PTR_ERR(binder_logs_root_dir);
594 goto out;
595 }
596
597 dentry = binderfs_create_file(binder_logs_root_dir, "stats",
598 &binder_stats_fops, NULL);
599 if (IS_ERR(dentry)) {
600 ret = PTR_ERR(dentry);
601 goto out;
602 }
603
604 dentry = binderfs_create_file(binder_logs_root_dir, "state",
605 &binder_state_fops, NULL);
606 if (IS_ERR(dentry)) {
607 ret = PTR_ERR(dentry);
608 goto out;
609 }
610
611 dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
612 &binder_transactions_fops, NULL);
613 if (IS_ERR(dentry)) {
614 ret = PTR_ERR(dentry);
615 goto out;
616 }
617
618 dentry = binderfs_create_file(binder_logs_root_dir,
619 "transaction_log",
620 &binder_transaction_log_fops,
621 &binder_transaction_log);
622 if (IS_ERR(dentry)) {
623 ret = PTR_ERR(dentry);
624 goto out;
625 }
626
627 dentry = binderfs_create_file(binder_logs_root_dir,
628 "failed_transaction_log",
629 &binder_transaction_log_fops,
630 &binder_transaction_log_failed);
631 if (IS_ERR(dentry)) {
632 ret = PTR_ERR(dentry);
633 goto out;
634 }
635
636 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
637 if (IS_ERR(proc_log_dir)) {
638 ret = PTR_ERR(proc_log_dir);
639 goto out;
640 }
641 info = sb->s_fs_info;
642 info->proc_log_dir = proc_log_dir;
643
644out:
645 return ret;
646}
647
648static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
649{
650 int ret;
651 struct binderfs_info *info;
652 struct binderfs_mount_opts *ctx = fc->fs_private;
653 struct inode *inode = NULL;
654 struct binderfs_device device_info = {};
655 const char *name;
656 size_t len;
657
658 sb->s_blocksize = PAGE_SIZE;
659 sb->s_blocksize_bits = PAGE_SHIFT;
660
661 /*
662 * The binderfs filesystem can be mounted by userns root in a
663 * non-initial userns. By default such mounts have the SB_I_NODEV flag
664 * set in s_iflags to prevent security issues where userns root can
665 * just create random device nodes via mknod() since it owns the
666 * filesystem mount. But binderfs does not allow to create any files
667 * including devices nodes. The only way to create binder devices nodes
668 * is through the binder-control device which userns root is explicitly
669 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
670 * necessary and safe.
671 */
672 sb->s_iflags &= ~SB_I_NODEV;
673 sb->s_iflags |= SB_I_NOEXEC;
674 sb->s_magic = BINDERFS_SUPER_MAGIC;
675 sb->s_op = &binderfs_super_ops;
676 sb->s_time_gran = 1;
677
678 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
679 if (!sb->s_fs_info)
680 return -ENOMEM;
681 info = sb->s_fs_info;
682
683 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
684
685 info->root_gid = make_kgid(sb->s_user_ns, 0);
686 if (!gid_valid(info->root_gid))
687 info->root_gid = GLOBAL_ROOT_GID;
688 info->root_uid = make_kuid(sb->s_user_ns, 0);
689 if (!uid_valid(info->root_uid))
690 info->root_uid = GLOBAL_ROOT_UID;
691 info->mount_opts.max = ctx->max;
692 info->mount_opts.stats_mode = ctx->stats_mode;
693
694 inode = new_inode(sb);
695 if (!inode)
696 return -ENOMEM;
697
698 inode->i_ino = FIRST_INODE;
699 inode->i_fop = &simple_dir_operations;
700 inode->i_mode = S_IFDIR | 0755;
701 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
702 inode->i_op = &binderfs_dir_inode_operations;
703 set_nlink(inode, 2);
704
705 sb->s_root = d_make_root(inode);
706 if (!sb->s_root)
707 return -ENOMEM;
708
709 ret = binderfs_binder_ctl_create(sb);
710 if (ret)
711 return ret;
712
713 name = binder_devices_param;
714 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
715 strscpy(device_info.name, name, len + 1);
716 ret = binderfs_binder_device_create(inode, NULL, &device_info);
717 if (ret)
718 return ret;
719 name += len;
720 if (*name == ',')
721 name++;
722 }
723
724 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
725 return init_binder_logs(sb);
726
727 return 0;
728}
729
730static int binderfs_fs_context_get_tree(struct fs_context *fc)
731{
732 return get_tree_nodev(fc, binderfs_fill_super);
733}
734
735static void binderfs_fs_context_free(struct fs_context *fc)
736{
737 struct binderfs_mount_opts *ctx = fc->fs_private;
738
739 kfree(ctx);
740}
741
742static const struct fs_context_operations binderfs_fs_context_ops = {
743 .free = binderfs_fs_context_free,
744 .get_tree = binderfs_fs_context_get_tree,
745 .parse_param = binderfs_fs_context_parse_param,
746 .reconfigure = binderfs_fs_context_reconfigure,
747};
748
749static int binderfs_init_fs_context(struct fs_context *fc)
750{
751 struct binderfs_mount_opts *ctx;
752
753 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
754 if (!ctx)
755 return -ENOMEM;
756
757 ctx->max = BINDERFS_MAX_MINOR;
758 ctx->stats_mode = binderfs_stats_mode_unset;
759
760 fc->fs_private = ctx;
761 fc->ops = &binderfs_fs_context_ops;
762
763 return 0;
764}
765
766static struct file_system_type binder_fs_type = {
767 .name = "binder",
768 .init_fs_context = binderfs_init_fs_context,
769 .parameters = binderfs_fs_parameters,
770 .kill_sb = kill_litter_super,
771 .fs_flags = FS_USERNS_MOUNT,
772};
773
774int __init init_binderfs(void)
775{
776 int ret;
777 const char *name;
778 size_t len;
779
780 /* Verify that the default binderfs device names are valid. */
781 name = binder_devices_param;
782 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
783 if (len > BINDERFS_MAX_NAME)
784 return -E2BIG;
785 name += len;
786 if (*name == ',')
787 name++;
788 }
789
790 /* Allocate new major number for binderfs. */
791 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
792 "binder");
793 if (ret)
794 return ret;
795
796 ret = register_filesystem(&binder_fs_type);
797 if (ret) {
798 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
799 return ret;
800 }
801
802 return ret;
803}
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/parser.h>
22#include <linux/radix-tree.h>
23#include <linux/sched.h>
24#include <linux/seq_file.h>
25#include <linux/slab.h>
26#include <linux/spinlock_types.h>
27#include <linux/stddef.h>
28#include <linux/string.h>
29#include <linux/types.h>
30#include <linux/uaccess.h>
31#include <linux/user_namespace.h>
32#include <linux/xarray.h>
33#include <uapi/asm-generic/errno-base.h>
34#include <uapi/linux/android/binder.h>
35#include <uapi/linux/android/binderfs.h>
36
37#include "binder_internal.h"
38
39#define FIRST_INODE 1
40#define SECOND_INODE 2
41#define INODE_OFFSET 3
42#define INTSTRLEN 21
43#define BINDERFS_MAX_MINOR (1U << MINORBITS)
44/* Ensure that the initial ipc namespace always has devices available. */
45#define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
46
47static dev_t binderfs_dev;
48static DEFINE_MUTEX(binderfs_minors_mutex);
49static DEFINE_IDA(binderfs_minors);
50
51enum {
52 Opt_max,
53 Opt_stats_mode,
54 Opt_err
55};
56
57enum binderfs_stats_mode {
58 STATS_NONE,
59 STATS_GLOBAL,
60};
61
62static const match_table_t tokens = {
63 { Opt_max, "max=%d" },
64 { Opt_stats_mode, "stats=%s" },
65 { Opt_err, NULL }
66};
67
68static inline struct binderfs_info *BINDERFS_I(const struct inode *inode)
69{
70 return inode->i_sb->s_fs_info;
71}
72
73bool is_binderfs_device(const struct inode *inode)
74{
75 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
76 return true;
77
78 return false;
79}
80
81/**
82 * binderfs_binder_device_create - allocate inode from super block of a
83 * binderfs mount
84 * @ref_inode: inode from wich the super block will be taken
85 * @userp: buffer to copy information about new device for userspace to
86 * @req: struct binderfs_device as copied from userspace
87 *
88 * This function allocates a new binder_device and reserves a new minor
89 * number for it.
90 * Minor numbers are limited and tracked globally in binderfs_minors. The
91 * function will stash a struct binder_device for the specific binder
92 * device in i_private of the inode.
93 * It will go on to allocate a new inode from the super block of the
94 * filesystem mount, stash a struct binder_device in its i_private field
95 * and attach a dentry to that inode.
96 *
97 * Return: 0 on success, negative errno on failure
98 */
99static int binderfs_binder_device_create(struct inode *ref_inode,
100 struct binderfs_device __user *userp,
101 struct binderfs_device *req)
102{
103 int minor, ret;
104 struct dentry *dentry, *root;
105 struct binder_device *device;
106 char *name = NULL;
107 size_t name_len;
108 struct inode *inode = NULL;
109 struct super_block *sb = ref_inode->i_sb;
110 struct binderfs_info *info = sb->s_fs_info;
111#if defined(CONFIG_IPC_NS)
112 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
113#else
114 bool use_reserve = true;
115#endif
116
117 /* Reserve new minor number for the new device. */
118 mutex_lock(&binderfs_minors_mutex);
119 if (++info->device_count <= info->mount_opts.max)
120 minor = ida_alloc_max(&binderfs_minors,
121 use_reserve ? BINDERFS_MAX_MINOR :
122 BINDERFS_MAX_MINOR_CAPPED,
123 GFP_KERNEL);
124 else
125 minor = -ENOSPC;
126 if (minor < 0) {
127 --info->device_count;
128 mutex_unlock(&binderfs_minors_mutex);
129 return minor;
130 }
131 mutex_unlock(&binderfs_minors_mutex);
132
133 ret = -ENOMEM;
134 device = kzalloc(sizeof(*device), GFP_KERNEL);
135 if (!device)
136 goto err;
137
138 inode = new_inode(sb);
139 if (!inode)
140 goto err;
141
142 inode->i_ino = minor + INODE_OFFSET;
143 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
144 init_special_inode(inode, S_IFCHR | 0600,
145 MKDEV(MAJOR(binderfs_dev), minor));
146 inode->i_fop = &binder_fops;
147 inode->i_uid = info->root_uid;
148 inode->i_gid = info->root_gid;
149
150 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
151 name_len = strlen(req->name);
152 /* Make sure to include terminating NUL byte */
153 name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
154 if (!name)
155 goto err;
156
157 device->binderfs_inode = inode;
158 device->context.binder_context_mgr_uid = INVALID_UID;
159 device->context.name = name;
160 device->miscdev.name = name;
161 device->miscdev.minor = minor;
162 mutex_init(&device->context.context_mgr_node_lock);
163
164 req->major = MAJOR(binderfs_dev);
165 req->minor = minor;
166
167 if (userp && copy_to_user(userp, req, sizeof(*req))) {
168 ret = -EFAULT;
169 goto err;
170 }
171
172 root = sb->s_root;
173 inode_lock(d_inode(root));
174
175 /* look it up */
176 dentry = lookup_one_len(name, root, name_len);
177 if (IS_ERR(dentry)) {
178 inode_unlock(d_inode(root));
179 ret = PTR_ERR(dentry);
180 goto err;
181 }
182
183 if (d_really_is_positive(dentry)) {
184 /* already exists */
185 dput(dentry);
186 inode_unlock(d_inode(root));
187 ret = -EEXIST;
188 goto err;
189 }
190
191 inode->i_private = device;
192 d_instantiate(dentry, inode);
193 fsnotify_create(root->d_inode, dentry);
194 inode_unlock(d_inode(root));
195
196 return 0;
197
198err:
199 kfree(name);
200 kfree(device);
201 mutex_lock(&binderfs_minors_mutex);
202 --info->device_count;
203 ida_free(&binderfs_minors, minor);
204 mutex_unlock(&binderfs_minors_mutex);
205 iput(inode);
206
207 return ret;
208}
209
210/**
211 * binderfs_ctl_ioctl - handle binder device node allocation requests
212 *
213 * The request handler for the binder-control device. All requests operate on
214 * the binderfs mount the binder-control device resides in:
215 * - BINDER_CTL_ADD
216 * Allocate a new binder device.
217 *
218 * Return: 0 on success, negative errno on failure
219 */
220static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
221 unsigned long arg)
222{
223 int ret = -EINVAL;
224 struct inode *inode = file_inode(file);
225 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
226 struct binderfs_device device_req;
227
228 switch (cmd) {
229 case BINDER_CTL_ADD:
230 ret = copy_from_user(&device_req, device, sizeof(device_req));
231 if (ret) {
232 ret = -EFAULT;
233 break;
234 }
235
236 ret = binderfs_binder_device_create(inode, device, &device_req);
237 break;
238 default:
239 break;
240 }
241
242 return ret;
243}
244
245static void binderfs_evict_inode(struct inode *inode)
246{
247 struct binder_device *device = inode->i_private;
248 struct binderfs_info *info = BINDERFS_I(inode);
249
250 clear_inode(inode);
251
252 if (!S_ISCHR(inode->i_mode) || !device)
253 return;
254
255 mutex_lock(&binderfs_minors_mutex);
256 --info->device_count;
257 ida_free(&binderfs_minors, device->miscdev.minor);
258 mutex_unlock(&binderfs_minors_mutex);
259
260 kfree(device->context.name);
261 kfree(device);
262}
263
264/**
265 * binderfs_parse_mount_opts - parse binderfs mount options
266 * @data: options to set (can be NULL in which case defaults are used)
267 */
268static int binderfs_parse_mount_opts(char *data,
269 struct binderfs_mount_opts *opts)
270{
271 char *p, *stats;
272 opts->max = BINDERFS_MAX_MINOR;
273 opts->stats_mode = STATS_NONE;
274
275 while ((p = strsep(&data, ",")) != NULL) {
276 substring_t args[MAX_OPT_ARGS];
277 int token;
278 int max_devices;
279
280 if (!*p)
281 continue;
282
283 token = match_token(p, tokens, args);
284 switch (token) {
285 case Opt_max:
286 if (match_int(&args[0], &max_devices) ||
287 (max_devices < 0 ||
288 (max_devices > BINDERFS_MAX_MINOR)))
289 return -EINVAL;
290
291 opts->max = max_devices;
292 break;
293 case Opt_stats_mode:
294 if (!capable(CAP_SYS_ADMIN))
295 return -EINVAL;
296
297 stats = match_strdup(&args[0]);
298 if (!stats)
299 return -ENOMEM;
300
301 if (strcmp(stats, "global") != 0) {
302 kfree(stats);
303 return -EINVAL;
304 }
305
306 opts->stats_mode = STATS_GLOBAL;
307 kfree(stats);
308 break;
309 default:
310 pr_err("Invalid mount options\n");
311 return -EINVAL;
312 }
313 }
314
315 return 0;
316}
317
318static int binderfs_remount(struct super_block *sb, int *flags, char *data)
319{
320 int prev_stats_mode, ret;
321 struct binderfs_info *info = sb->s_fs_info;
322
323 prev_stats_mode = info->mount_opts.stats_mode;
324 ret = binderfs_parse_mount_opts(data, &info->mount_opts);
325 if (ret)
326 return ret;
327
328 if (prev_stats_mode != info->mount_opts.stats_mode) {
329 pr_err("Binderfs stats mode cannot be changed during a remount\n");
330 info->mount_opts.stats_mode = prev_stats_mode;
331 return -EINVAL;
332 }
333
334 return 0;
335}
336
337static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
338{
339 struct binderfs_info *info;
340
341 info = root->d_sb->s_fs_info;
342 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
343 seq_printf(seq, ",max=%d", info->mount_opts.max);
344 if (info->mount_opts.stats_mode == STATS_GLOBAL)
345 seq_printf(seq, ",stats=global");
346
347 return 0;
348}
349
350static const struct super_operations binderfs_super_ops = {
351 .evict_inode = binderfs_evict_inode,
352 .remount_fs = binderfs_remount,
353 .show_options = binderfs_show_mount_opts,
354 .statfs = simple_statfs,
355};
356
357static inline bool is_binderfs_control_device(const struct dentry *dentry)
358{
359 struct binderfs_info *info = dentry->d_sb->s_fs_info;
360 return info->control_dentry == dentry;
361}
362
363static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry,
364 struct inode *new_dir, struct dentry *new_dentry,
365 unsigned int flags)
366{
367 if (is_binderfs_control_device(old_dentry) ||
368 is_binderfs_control_device(new_dentry))
369 return -EPERM;
370
371 return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
372}
373
374static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
375{
376 if (is_binderfs_control_device(dentry))
377 return -EPERM;
378
379 return simple_unlink(dir, dentry);
380}
381
382static const struct file_operations binder_ctl_fops = {
383 .owner = THIS_MODULE,
384 .open = nonseekable_open,
385 .unlocked_ioctl = binder_ctl_ioctl,
386 .compat_ioctl = binder_ctl_ioctl,
387 .llseek = noop_llseek,
388};
389
390/**
391 * binderfs_binder_ctl_create - create a new binder-control device
392 * @sb: super block of the binderfs mount
393 *
394 * This function creates a new binder-control device node in the binderfs mount
395 * referred to by @sb.
396 *
397 * Return: 0 on success, negative errno on failure
398 */
399static int binderfs_binder_ctl_create(struct super_block *sb)
400{
401 int minor, ret;
402 struct dentry *dentry;
403 struct binder_device *device;
404 struct inode *inode = NULL;
405 struct dentry *root = sb->s_root;
406 struct binderfs_info *info = sb->s_fs_info;
407#if defined(CONFIG_IPC_NS)
408 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
409#else
410 bool use_reserve = true;
411#endif
412
413 device = kzalloc(sizeof(*device), GFP_KERNEL);
414 if (!device)
415 return -ENOMEM;
416
417 /* If we have already created a binder-control node, return. */
418 if (info->control_dentry) {
419 ret = 0;
420 goto out;
421 }
422
423 ret = -ENOMEM;
424 inode = new_inode(sb);
425 if (!inode)
426 goto out;
427
428 /* Reserve a new minor number for the new device. */
429 mutex_lock(&binderfs_minors_mutex);
430 minor = ida_alloc_max(&binderfs_minors,
431 use_reserve ? BINDERFS_MAX_MINOR :
432 BINDERFS_MAX_MINOR_CAPPED,
433 GFP_KERNEL);
434 mutex_unlock(&binderfs_minors_mutex);
435 if (minor < 0) {
436 ret = minor;
437 goto out;
438 }
439
440 inode->i_ino = SECOND_INODE;
441 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
442 init_special_inode(inode, S_IFCHR | 0600,
443 MKDEV(MAJOR(binderfs_dev), minor));
444 inode->i_fop = &binder_ctl_fops;
445 inode->i_uid = info->root_uid;
446 inode->i_gid = info->root_gid;
447
448 device->binderfs_inode = inode;
449 device->miscdev.minor = minor;
450
451 dentry = d_alloc_name(root, "binder-control");
452 if (!dentry)
453 goto out;
454
455 inode->i_private = device;
456 info->control_dentry = dentry;
457 d_add(dentry, inode);
458
459 return 0;
460
461out:
462 kfree(device);
463 iput(inode);
464
465 return ret;
466}
467
468static const struct inode_operations binderfs_dir_inode_operations = {
469 .lookup = simple_lookup,
470 .rename = binderfs_rename,
471 .unlink = binderfs_unlink,
472};
473
474static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
475{
476 struct inode *ret;
477
478 ret = new_inode(sb);
479 if (ret) {
480 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
481 ret->i_mode = mode;
482 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
483 }
484 return ret;
485}
486
487static struct dentry *binderfs_create_dentry(struct dentry *parent,
488 const char *name)
489{
490 struct dentry *dentry;
491
492 dentry = lookup_one_len(name, parent, strlen(name));
493 if (IS_ERR(dentry))
494 return dentry;
495
496 /* Return error if the file/dir already exists. */
497 if (d_really_is_positive(dentry)) {
498 dput(dentry);
499 return ERR_PTR(-EEXIST);
500 }
501
502 return dentry;
503}
504
505void binderfs_remove_file(struct dentry *dentry)
506{
507 struct inode *parent_inode;
508
509 parent_inode = d_inode(dentry->d_parent);
510 inode_lock(parent_inode);
511 if (simple_positive(dentry)) {
512 dget(dentry);
513 simple_unlink(parent_inode, dentry);
514 d_delete(dentry);
515 dput(dentry);
516 }
517 inode_unlock(parent_inode);
518}
519
520struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
521 const struct file_operations *fops,
522 void *data)
523{
524 struct dentry *dentry;
525 struct inode *new_inode, *parent_inode;
526 struct super_block *sb;
527
528 parent_inode = d_inode(parent);
529 inode_lock(parent_inode);
530
531 dentry = binderfs_create_dentry(parent, name);
532 if (IS_ERR(dentry))
533 goto out;
534
535 sb = parent_inode->i_sb;
536 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
537 if (!new_inode) {
538 dput(dentry);
539 dentry = ERR_PTR(-ENOMEM);
540 goto out;
541 }
542
543 new_inode->i_fop = fops;
544 new_inode->i_private = data;
545 d_instantiate(dentry, new_inode);
546 fsnotify_create(parent_inode, dentry);
547
548out:
549 inode_unlock(parent_inode);
550 return dentry;
551}
552
553static struct dentry *binderfs_create_dir(struct dentry *parent,
554 const char *name)
555{
556 struct dentry *dentry;
557 struct inode *new_inode, *parent_inode;
558 struct super_block *sb;
559
560 parent_inode = d_inode(parent);
561 inode_lock(parent_inode);
562
563 dentry = binderfs_create_dentry(parent, name);
564 if (IS_ERR(dentry))
565 goto out;
566
567 sb = parent_inode->i_sb;
568 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
569 if (!new_inode) {
570 dput(dentry);
571 dentry = ERR_PTR(-ENOMEM);
572 goto out;
573 }
574
575 new_inode->i_fop = &simple_dir_operations;
576 new_inode->i_op = &simple_dir_inode_operations;
577
578 set_nlink(new_inode, 2);
579 d_instantiate(dentry, new_inode);
580 inc_nlink(parent_inode);
581 fsnotify_mkdir(parent_inode, dentry);
582
583out:
584 inode_unlock(parent_inode);
585 return dentry;
586}
587
588static int init_binder_logs(struct super_block *sb)
589{
590 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
591 struct binderfs_info *info;
592 int ret = 0;
593
594 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
595 "binder_logs");
596 if (IS_ERR(binder_logs_root_dir)) {
597 ret = PTR_ERR(binder_logs_root_dir);
598 goto out;
599 }
600
601 dentry = binderfs_create_file(binder_logs_root_dir, "stats",
602 &binder_stats_fops, NULL);
603 if (IS_ERR(dentry)) {
604 ret = PTR_ERR(dentry);
605 goto out;
606 }
607
608 dentry = binderfs_create_file(binder_logs_root_dir, "state",
609 &binder_state_fops, NULL);
610 if (IS_ERR(dentry)) {
611 ret = PTR_ERR(dentry);
612 goto out;
613 }
614
615 dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
616 &binder_transactions_fops, NULL);
617 if (IS_ERR(dentry)) {
618 ret = PTR_ERR(dentry);
619 goto out;
620 }
621
622 dentry = binderfs_create_file(binder_logs_root_dir,
623 "transaction_log",
624 &binder_transaction_log_fops,
625 &binder_transaction_log);
626 if (IS_ERR(dentry)) {
627 ret = PTR_ERR(dentry);
628 goto out;
629 }
630
631 dentry = binderfs_create_file(binder_logs_root_dir,
632 "failed_transaction_log",
633 &binder_transaction_log_fops,
634 &binder_transaction_log_failed);
635 if (IS_ERR(dentry)) {
636 ret = PTR_ERR(dentry);
637 goto out;
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
648out:
649 return ret;
650}
651
652static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
653{
654 int ret;
655 struct binderfs_info *info;
656 struct inode *inode = NULL;
657 struct binderfs_device device_info = { 0 };
658 const char *name;
659 size_t len;
660
661 sb->s_blocksize = PAGE_SIZE;
662 sb->s_blocksize_bits = PAGE_SHIFT;
663
664 /*
665 * The binderfs filesystem can be mounted by userns root in a
666 * non-initial userns. By default such mounts have the SB_I_NODEV flag
667 * set in s_iflags to prevent security issues where userns root can
668 * just create random device nodes via mknod() since it owns the
669 * filesystem mount. But binderfs does not allow to create any files
670 * including devices nodes. The only way to create binder devices nodes
671 * is through the binder-control device which userns root is explicitly
672 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
673 * necessary and safe.
674 */
675 sb->s_iflags &= ~SB_I_NODEV;
676 sb->s_iflags |= SB_I_NOEXEC;
677 sb->s_magic = BINDERFS_SUPER_MAGIC;
678 sb->s_op = &binderfs_super_ops;
679 sb->s_time_gran = 1;
680
681 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
682 if (!sb->s_fs_info)
683 return -ENOMEM;
684 info = sb->s_fs_info;
685
686 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
687
688 ret = binderfs_parse_mount_opts(data, &info->mount_opts);
689 if (ret)
690 return ret;
691
692 info->root_gid = make_kgid(sb->s_user_ns, 0);
693 if (!gid_valid(info->root_gid))
694 info->root_gid = GLOBAL_ROOT_GID;
695 info->root_uid = make_kuid(sb->s_user_ns, 0);
696 if (!uid_valid(info->root_uid))
697 info->root_uid = GLOBAL_ROOT_UID;
698
699 inode = new_inode(sb);
700 if (!inode)
701 return -ENOMEM;
702
703 inode->i_ino = FIRST_INODE;
704 inode->i_fop = &simple_dir_operations;
705 inode->i_mode = S_IFDIR | 0755;
706 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
707 inode->i_op = &binderfs_dir_inode_operations;
708 set_nlink(inode, 2);
709
710 sb->s_root = d_make_root(inode);
711 if (!sb->s_root)
712 return -ENOMEM;
713
714 ret = binderfs_binder_ctl_create(sb);
715 if (ret)
716 return ret;
717
718 name = binder_devices_param;
719 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
720 strscpy(device_info.name, name, len + 1);
721 ret = binderfs_binder_device_create(inode, NULL, &device_info);
722 if (ret)
723 return ret;
724 name += len;
725 if (*name == ',')
726 name++;
727 }
728
729 if (info->mount_opts.stats_mode == STATS_GLOBAL)
730 return init_binder_logs(sb);
731
732 return 0;
733}
734
735static struct dentry *binderfs_mount(struct file_system_type *fs_type,
736 int flags, const char *dev_name,
737 void *data)
738{
739 return mount_nodev(fs_type, flags, data, binderfs_fill_super);
740}
741
742static void binderfs_kill_super(struct super_block *sb)
743{
744 struct binderfs_info *info = sb->s_fs_info;
745
746 kill_litter_super(sb);
747
748 if (info && info->ipc_ns)
749 put_ipc_ns(info->ipc_ns);
750
751 kfree(info);
752}
753
754static struct file_system_type binder_fs_type = {
755 .name = "binder",
756 .mount = binderfs_mount,
757 .kill_sb = binderfs_kill_super,
758 .fs_flags = FS_USERNS_MOUNT,
759};
760
761int __init init_binderfs(void)
762{
763 int ret;
764 const char *name;
765 size_t len;
766
767 /* Verify that the default binderfs device names are valid. */
768 name = binder_devices_param;
769 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
770 if (len > BINDERFS_MAX_NAME)
771 return -E2BIG;
772 name += len;
773 if (*name == ',')
774 name++;
775 }
776
777 /* Allocate new major number for binderfs. */
778 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
779 "binder");
780 if (ret)
781 return ret;
782
783 ret = register_filesystem(&binder_fs_type);
784 if (ret) {
785 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
786 return ret;
787 }
788
789 return ret;
790}