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
44 static dev_t binderfs_dev;
45 static DEFINE_MUTEX(binderfs_minors_mutex);
46 static DEFINE_IDA(binderfs_minors);
47
48 enum binderfs_param {
49 Opt_max,
50 Opt_stats_mode,
51 };
52
53 enum binderfs_stats_mode {
54 binderfs_stats_mode_unset,
55 binderfs_stats_mode_global,
56 };
57
58 struct binder_features {
59 bool oneway_spam_detection;
60 bool extended_error;
61 bool freeze_notification;
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 .freeze_notification = true,
79 };
80
BINDERFS_SB(const struct super_block * sb)81 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
82 {
83 return sb->s_fs_info;
84 }
85
is_binderfs_device(const struct inode * inode)86 bool 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 */
binderfs_binder_device_create(struct inode * ref_inode,struct binderfs_device __user * userp,struct binderfs_device * req)112 static 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 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 simple_inode_init_ts(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 = kstrdup(req->name, GFP_KERNEL);
164 if (!name)
165 goto err;
166
167 refcount_set(&device->ref, 1);
168 device->binderfs_inode = inode;
169 device->context.binder_context_mgr_uid = INVALID_UID;
170 device->context.name = name;
171 device->miscdev.name = name;
172 device->miscdev.minor = minor;
173 mutex_init(&device->context.context_mgr_node_lock);
174
175 req->major = MAJOR(binderfs_dev);
176 req->minor = minor;
177
178 if (userp && copy_to_user(userp, req, sizeof(*req))) {
179 ret = -EFAULT;
180 goto err;
181 }
182
183 root = sb->s_root;
184 inode_lock(d_inode(root));
185
186 /* look it up */
187 dentry = lookup_noperm(&QSTR(name), root);
188 if (IS_ERR(dentry)) {
189 inode_unlock(d_inode(root));
190 ret = PTR_ERR(dentry);
191 goto err;
192 }
193
194 if (d_really_is_positive(dentry)) {
195 /* already exists */
196 dput(dentry);
197 inode_unlock(d_inode(root));
198 ret = -EEXIST;
199 goto err;
200 }
201
202 inode->i_private = device;
203 d_instantiate(dentry, inode);
204 fsnotify_create(root->d_inode, dentry);
205 inode_unlock(d_inode(root));
206
207 binder_add_device(device);
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 binder_remove_device(device);
275 kfree(device->context.name);
276 kfree(device);
277 }
278 }
279
binderfs_fs_context_parse_param(struct fs_context * fc,struct fs_parameter * param)280 static int binderfs_fs_context_parse_param(struct fs_context *fc,
281 struct fs_parameter *param)
282 {
283 int opt;
284 struct binderfs_mount_opts *ctx = fc->fs_private;
285 struct fs_parse_result result;
286
287 opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
288 if (opt < 0)
289 return opt;
290
291 switch (opt) {
292 case Opt_max:
293 if (result.uint_32 > BINDERFS_MAX_MINOR)
294 return invalfc(fc, "Bad value for '%s'", param->key);
295
296 ctx->max = result.uint_32;
297 break;
298 case Opt_stats_mode:
299 if (!capable(CAP_SYS_ADMIN))
300 return -EPERM;
301
302 ctx->stats_mode = result.uint_32;
303 break;
304 default:
305 return invalfc(fc, "Unsupported parameter '%s'", param->key);
306 }
307
308 return 0;
309 }
310
binderfs_fs_context_reconfigure(struct fs_context * fc)311 static int binderfs_fs_context_reconfigure(struct fs_context *fc)
312 {
313 struct binderfs_mount_opts *ctx = fc->fs_private;
314 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
315
316 if (info->mount_opts.stats_mode != ctx->stats_mode)
317 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
318
319 info->mount_opts.stats_mode = ctx->stats_mode;
320 info->mount_opts.max = ctx->max;
321 return 0;
322 }
323
binderfs_show_options(struct seq_file * seq,struct dentry * root)324 static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
325 {
326 struct binderfs_info *info = BINDERFS_SB(root->d_sb);
327
328 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
329 seq_printf(seq, ",max=%d", info->mount_opts.max);
330
331 switch (info->mount_opts.stats_mode) {
332 case binderfs_stats_mode_unset:
333 break;
334 case binderfs_stats_mode_global:
335 seq_printf(seq, ",stats=global");
336 break;
337 }
338
339 return 0;
340 }
341
342 static const struct super_operations binderfs_super_ops = {
343 .evict_inode = binderfs_evict_inode,
344 .show_options = binderfs_show_options,
345 .statfs = simple_statfs,
346 };
347
is_binderfs_control_device(const struct dentry * dentry)348 static inline bool is_binderfs_control_device(const struct dentry *dentry)
349 {
350 struct binderfs_info *info = dentry->d_sb->s_fs_info;
351
352 return info->control_dentry == dentry;
353 }
354
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)355 static int binderfs_rename(struct mnt_idmap *idmap,
356 struct inode *old_dir, struct dentry *old_dentry,
357 struct inode *new_dir, struct dentry *new_dentry,
358 unsigned int flags)
359 {
360 if (is_binderfs_control_device(old_dentry) ||
361 is_binderfs_control_device(new_dentry))
362 return -EPERM;
363
364 return simple_rename(idmap, old_dir, old_dentry, new_dir,
365 new_dentry, flags);
366 }
367
binderfs_unlink(struct inode * dir,struct dentry * dentry)368 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
369 {
370 if (is_binderfs_control_device(dentry))
371 return -EPERM;
372
373 return simple_unlink(dir, dentry);
374 }
375
376 static const struct file_operations binder_ctl_fops = {
377 .owner = THIS_MODULE,
378 .open = nonseekable_open,
379 .unlocked_ioctl = binder_ctl_ioctl,
380 .compat_ioctl = binder_ctl_ioctl,
381 .llseek = noop_llseek,
382 };
383
384 /**
385 * binderfs_binder_ctl_create - create a new binder-control device
386 * @sb: super block of the binderfs mount
387 *
388 * This function creates a new binder-control device node in the binderfs mount
389 * referred to by @sb.
390 *
391 * Return: 0 on success, negative errno on failure
392 */
binderfs_binder_ctl_create(struct super_block * sb)393 static int binderfs_binder_ctl_create(struct super_block *sb)
394 {
395 int minor, ret;
396 struct dentry *dentry;
397 struct binder_device *device;
398 struct inode *inode = NULL;
399 struct dentry *root = sb->s_root;
400 struct binderfs_info *info = sb->s_fs_info;
401 #if defined(CONFIG_IPC_NS)
402 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
403 #else
404 bool use_reserve = true;
405 #endif
406
407 device = kzalloc(sizeof(*device), GFP_KERNEL);
408 if (!device)
409 return -ENOMEM;
410
411 /* If we have already created a binder-control node, return. */
412 if (info->control_dentry) {
413 ret = 0;
414 goto out;
415 }
416
417 ret = -ENOMEM;
418 inode = new_inode(sb);
419 if (!inode)
420 goto out;
421
422 /* Reserve a new minor number for the new device. */
423 mutex_lock(&binderfs_minors_mutex);
424 minor = ida_alloc_max(&binderfs_minors,
425 use_reserve ? BINDERFS_MAX_MINOR :
426 BINDERFS_MAX_MINOR_CAPPED,
427 GFP_KERNEL);
428 mutex_unlock(&binderfs_minors_mutex);
429 if (minor < 0) {
430 ret = minor;
431 goto out;
432 }
433
434 inode->i_ino = SECOND_INODE;
435 simple_inode_init_ts(inode);
436 init_special_inode(inode, S_IFCHR | 0600,
437 MKDEV(MAJOR(binderfs_dev), minor));
438 inode->i_fop = &binder_ctl_fops;
439 inode->i_uid = info->root_uid;
440 inode->i_gid = info->root_gid;
441
442 refcount_set(&device->ref, 1);
443 device->binderfs_inode = inode;
444 device->miscdev.minor = minor;
445
446 dentry = d_alloc_name(root, "binder-control");
447 if (!dentry)
448 goto out;
449
450 inode->i_private = device;
451 info->control_dentry = dentry;
452 d_add(dentry, inode);
453
454 return 0;
455
456 out:
457 kfree(device);
458 iput(inode);
459
460 return ret;
461 }
462
463 static const struct inode_operations binderfs_dir_inode_operations = {
464 .lookup = simple_lookup,
465 .rename = binderfs_rename,
466 .unlink = binderfs_unlink,
467 };
468
binderfs_make_inode(struct super_block * sb,int mode)469 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
470 {
471 struct inode *ret;
472
473 ret = new_inode(sb);
474 if (ret) {
475 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
476 ret->i_mode = mode;
477 simple_inode_init_ts(ret);
478 }
479 return ret;
480 }
481
binderfs_create_dentry(struct dentry * parent,const char * name)482 static struct dentry *binderfs_create_dentry(struct dentry *parent,
483 const char *name)
484 {
485 struct dentry *dentry;
486
487 dentry = lookup_noperm(&QSTR(name), parent);
488 if (IS_ERR(dentry))
489 return dentry;
490
491 /* Return error if the file/dir already exists. */
492 if (d_really_is_positive(dentry)) {
493 dput(dentry);
494 return ERR_PTR(-EEXIST);
495 }
496
497 return dentry;
498 }
499
binderfs_create_file(struct dentry * parent,const char * name,const struct file_operations * fops,void * data)500 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
501 const struct file_operations *fops,
502 void *data)
503 {
504 struct dentry *dentry;
505 struct inode *new_inode, *parent_inode;
506 struct super_block *sb;
507
508 parent_inode = d_inode(parent);
509 inode_lock(parent_inode);
510
511 dentry = binderfs_create_dentry(parent, name);
512 if (IS_ERR(dentry))
513 goto out;
514
515 sb = parent_inode->i_sb;
516 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
517 if (!new_inode) {
518 dput(dentry);
519 dentry = ERR_PTR(-ENOMEM);
520 goto out;
521 }
522
523 new_inode->i_fop = fops;
524 new_inode->i_private = data;
525 d_instantiate(dentry, new_inode);
526 fsnotify_create(parent_inode, dentry);
527
528 out:
529 inode_unlock(parent_inode);
530 return dentry;
531 }
532
binderfs_create_dir(struct dentry * parent,const char * name)533 static struct dentry *binderfs_create_dir(struct dentry *parent,
534 const char *name)
535 {
536 struct dentry *dentry;
537 struct inode *new_inode, *parent_inode;
538 struct super_block *sb;
539
540 parent_inode = d_inode(parent);
541 inode_lock(parent_inode);
542
543 dentry = binderfs_create_dentry(parent, name);
544 if (IS_ERR(dentry))
545 goto out;
546
547 sb = parent_inode->i_sb;
548 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
549 if (!new_inode) {
550 dput(dentry);
551 dentry = ERR_PTR(-ENOMEM);
552 goto out;
553 }
554
555 new_inode->i_fop = &simple_dir_operations;
556 new_inode->i_op = &simple_dir_inode_operations;
557
558 set_nlink(new_inode, 2);
559 d_instantiate(dentry, new_inode);
560 inc_nlink(parent_inode);
561 fsnotify_mkdir(parent_inode, dentry);
562
563 out:
564 inode_unlock(parent_inode);
565 return dentry;
566 }
567
binder_features_show(struct seq_file * m,void * unused)568 static int binder_features_show(struct seq_file *m, void *unused)
569 {
570 bool *feature = m->private;
571
572 seq_printf(m, "%d\n", *feature);
573
574 return 0;
575 }
576 DEFINE_SHOW_ATTRIBUTE(binder_features);
577
init_binder_features(struct super_block * sb)578 static int init_binder_features(struct super_block *sb)
579 {
580 struct dentry *dentry, *dir;
581
582 dir = binderfs_create_dir(sb->s_root, "features");
583 if (IS_ERR(dir))
584 return PTR_ERR(dir);
585
586 dentry = binderfs_create_file(dir, "oneway_spam_detection",
587 &binder_features_fops,
588 &binder_features.oneway_spam_detection);
589 if (IS_ERR(dentry))
590 return PTR_ERR(dentry);
591
592 dentry = binderfs_create_file(dir, "extended_error",
593 &binder_features_fops,
594 &binder_features.extended_error);
595 if (IS_ERR(dentry))
596 return PTR_ERR(dentry);
597
598 dentry = binderfs_create_file(dir, "freeze_notification",
599 &binder_features_fops,
600 &binder_features.freeze_notification);
601 if (IS_ERR(dentry))
602 return PTR_ERR(dentry);
603
604 return 0;
605 }
606
init_binder_logs(struct super_block * sb)607 static int init_binder_logs(struct super_block *sb)
608 {
609 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
610 const struct binder_debugfs_entry *db_entry;
611 struct binderfs_info *info;
612 int ret = 0;
613
614 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
615 "binder_logs");
616 if (IS_ERR(binder_logs_root_dir)) {
617 ret = PTR_ERR(binder_logs_root_dir);
618 goto out;
619 }
620
621 binder_for_each_debugfs_entry(db_entry) {
622 dentry = binderfs_create_file(binder_logs_root_dir,
623 db_entry->name,
624 db_entry->fops,
625 db_entry->data);
626 if (IS_ERR(dentry)) {
627 ret = PTR_ERR(dentry);
628 goto out;
629 }
630 }
631
632 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
633 if (IS_ERR(proc_log_dir)) {
634 ret = PTR_ERR(proc_log_dir);
635 goto out;
636 }
637 info = sb->s_fs_info;
638 info->proc_log_dir = proc_log_dir;
639
640 out:
641 return ret;
642 }
643
binderfs_fill_super(struct super_block * sb,struct fs_context * fc)644 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
645 {
646 int ret;
647 struct binderfs_info *info;
648 struct binderfs_mount_opts *ctx = fc->fs_private;
649 struct inode *inode = NULL;
650 struct binderfs_device device_info = {};
651 const char *name;
652 size_t len;
653
654 sb->s_blocksize = PAGE_SIZE;
655 sb->s_blocksize_bits = PAGE_SHIFT;
656
657 /*
658 * The binderfs filesystem can be mounted by userns root in a
659 * non-initial userns. By default such mounts have the SB_I_NODEV flag
660 * set in s_iflags to prevent security issues where userns root can
661 * just create random device nodes via mknod() since it owns the
662 * filesystem mount. But binderfs does not allow to create any files
663 * including devices nodes. The only way to create binder devices nodes
664 * is through the binder-control device which userns root is explicitly
665 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
666 * necessary and safe.
667 */
668 sb->s_iflags &= ~SB_I_NODEV;
669 sb->s_iflags |= SB_I_NOEXEC;
670 sb->s_magic = BINDERFS_SUPER_MAGIC;
671 sb->s_op = &binderfs_super_ops;
672 sb->s_time_gran = 1;
673
674 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
675 if (!sb->s_fs_info)
676 return -ENOMEM;
677 info = sb->s_fs_info;
678
679 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
680
681 info->root_gid = make_kgid(sb->s_user_ns, 0);
682 if (!gid_valid(info->root_gid))
683 info->root_gid = GLOBAL_ROOT_GID;
684 info->root_uid = make_kuid(sb->s_user_ns, 0);
685 if (!uid_valid(info->root_uid))
686 info->root_uid = GLOBAL_ROOT_UID;
687 info->mount_opts.max = ctx->max;
688 info->mount_opts.stats_mode = ctx->stats_mode;
689
690 inode = new_inode(sb);
691 if (!inode)
692 return -ENOMEM;
693
694 inode->i_ino = FIRST_INODE;
695 inode->i_fop = &simple_dir_operations;
696 inode->i_mode = S_IFDIR | 0755;
697 simple_inode_init_ts(inode);
698 inode->i_op = &binderfs_dir_inode_operations;
699 set_nlink(inode, 2);
700
701 sb->s_root = d_make_root(inode);
702 if (!sb->s_root)
703 return -ENOMEM;
704
705 ret = binderfs_binder_ctl_create(sb);
706 if (ret)
707 return ret;
708
709 name = binder_devices_param;
710 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
711 strscpy(device_info.name, name, len + 1);
712 ret = binderfs_binder_device_create(inode, NULL, &device_info);
713 if (ret)
714 return ret;
715 name += len;
716 if (*name == ',')
717 name++;
718 }
719
720 ret = init_binder_features(sb);
721 if (ret)
722 return ret;
723
724 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
725 return init_binder_logs(sb);
726
727 return 0;
728 }
729
binderfs_fs_context_get_tree(struct fs_context * fc)730 static int binderfs_fs_context_get_tree(struct fs_context *fc)
731 {
732 return get_tree_nodev(fc, binderfs_fill_super);
733 }
734
binderfs_fs_context_free(struct fs_context * fc)735 static 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
742 static 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
binderfs_init_fs_context(struct fs_context * fc)749 static 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
binderfs_kill_super(struct super_block * sb)766 static void binderfs_kill_super(struct super_block *sb)
767 {
768 struct binderfs_info *info = sb->s_fs_info;
769
770 /*
771 * During inode eviction struct binderfs_info is needed.
772 * So first wipe the super_block then free struct binderfs_info.
773 */
774 kill_litter_super(sb);
775
776 if (info && info->ipc_ns)
777 put_ipc_ns(info->ipc_ns);
778
779 kfree(info);
780 }
781
782 static struct file_system_type binder_fs_type = {
783 .name = "binder",
784 .init_fs_context = binderfs_init_fs_context,
785 .parameters = binderfs_fs_parameters,
786 .kill_sb = binderfs_kill_super,
787 .fs_flags = FS_USERNS_MOUNT,
788 };
789
init_binderfs(void)790 int __init init_binderfs(void)
791 {
792 int ret;
793 const char *name;
794 size_t len;
795
796 /* Verify that the default binderfs device names are valid. */
797 name = binder_devices_param;
798 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
799 if (len > BINDERFS_MAX_NAME)
800 return -E2BIG;
801 name += len;
802 if (*name == ',')
803 name++;
804 }
805
806 /* Allocate new major number for binderfs. */
807 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
808 "binder");
809 if (ret)
810 return ret;
811
812 ret = register_filesystem(&binder_fs_type);
813 if (ret) {
814 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
815 return ret;
816 }
817
818 return ret;
819 }
820