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 bool transaction_report;
63 };
64
65 static const struct constant_table binderfs_param_stats[] = {
66 { "global", binderfs_stats_mode_global },
67 {}
68 };
69
70 static const struct fs_parameter_spec binderfs_fs_parameters[] = {
71 fsparam_u32("max", Opt_max),
72 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats),
73 {}
74 };
75
76 static struct binder_features binder_features = {
77 .oneway_spam_detection = true,
78 .extended_error = true,
79 .freeze_notification = true,
80 .transaction_report = true,
81 };
82
BINDERFS_SB(const struct super_block * sb)83 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
84 {
85 return sb->s_fs_info;
86 }
87
is_binderfs_device(const struct inode * inode)88 bool is_binderfs_device(const struct inode *inode)
89 {
90 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
91 return true;
92
93 return false;
94 }
95
96 /**
97 * binderfs_binder_device_create - allocate inode from super block of a
98 * binderfs mount
99 * @ref_inode: inode from which the super block will be taken
100 * @userp: buffer to copy information about new device for userspace to
101 * @req: struct binderfs_device as copied from userspace
102 *
103 * This function allocates a new binder_device and reserves a new minor
104 * number for it.
105 * Minor numbers are limited and tracked globally in binderfs_minors. The
106 * function will stash a struct binder_device for the specific binder
107 * device in i_private of the inode.
108 * It will go on to allocate a new inode from the super block of the
109 * filesystem mount, stash a struct binder_device in its i_private field
110 * and attach a dentry to that inode.
111 *
112 * Return: 0 on success, negative errno on failure
113 */
binderfs_binder_device_create(struct inode * ref_inode,struct binderfs_device __user * userp,struct binderfs_device * req)114 static int binderfs_binder_device_create(struct inode *ref_inode,
115 struct binderfs_device __user *userp,
116 struct binderfs_device *req)
117 {
118 int minor, ret;
119 struct dentry *dentry, *root;
120 struct binder_device *device;
121 char *name = NULL;
122 struct inode *inode = NULL;
123 struct super_block *sb = ref_inode->i_sb;
124 struct binderfs_info *info = sb->s_fs_info;
125 #if defined(CONFIG_IPC_NS)
126 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
127 #else
128 bool use_reserve = true;
129 #endif
130
131 /* Reserve new minor number for the new device. */
132 mutex_lock(&binderfs_minors_mutex);
133 if (++info->device_count <= info->mount_opts.max)
134 minor = ida_alloc_max(&binderfs_minors,
135 use_reserve ? BINDERFS_MAX_MINOR - 1 :
136 BINDERFS_MAX_MINOR_CAPPED - 1,
137 GFP_KERNEL);
138 else
139 minor = -ENOSPC;
140 if (minor < 0) {
141 --info->device_count;
142 mutex_unlock(&binderfs_minors_mutex);
143 return minor;
144 }
145 mutex_unlock(&binderfs_minors_mutex);
146
147 ret = -ENOMEM;
148 device = kzalloc_obj(*device);
149 if (!device)
150 goto err;
151
152 inode = new_inode(sb);
153 if (!inode)
154 goto err;
155
156 inode->i_ino = minor + INODE_OFFSET;
157 simple_inode_init_ts(inode);
158 init_special_inode(inode, S_IFCHR | 0600,
159 MKDEV(MAJOR(binderfs_dev), minor));
160 inode->i_fop = &binder_fops;
161 inode->i_uid = info->root_uid;
162 inode->i_gid = info->root_gid;
163
164 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
165 name = kstrdup(req->name, 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 dentry = simple_start_creating(root, name);
187 if (IS_ERR(dentry)) {
188 ret = PTR_ERR(dentry);
189 goto err;
190 }
191 inode->i_private = device;
192 binder_add_device(device);
193 d_make_persistent(dentry, inode);
194 fsnotify_create(root->d_inode, dentry);
195 simple_done_creating(dentry);
196
197 return 0;
198
199 err:
200 kfree(name);
201 kfree(device);
202 mutex_lock(&binderfs_minors_mutex);
203 --info->device_count;
204 ida_free(&binderfs_minors, minor);
205 mutex_unlock(&binderfs_minors_mutex);
206 iput(inode);
207
208 return ret;
209 }
210
211 /**
212 * binder_ctl_ioctl - handle binder device node allocation requests
213 * @file: The file pointer for the binder-control device node.
214 * @cmd: The ioctl command.
215 * @arg: The ioctl argument.
216 *
217 * The request handler for the binder-control device. All requests operate on
218 * the binderfs mount the binder-control device resides in:
219 * - BINDER_CTL_ADD
220 * Allocate a new binder device.
221 *
222 * Return: %0 on success, negative errno on failure.
223 */
binder_ctl_ioctl(struct file * file,unsigned int cmd,unsigned long arg)224 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
225 unsigned long arg)
226 {
227 int ret = -EINVAL;
228 struct inode *inode = file_inode(file);
229 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
230 struct binderfs_device device_req;
231
232 switch (cmd) {
233 case BINDER_CTL_ADD:
234 ret = copy_from_user(&device_req, device, sizeof(device_req));
235 if (ret) {
236 ret = -EFAULT;
237 break;
238 }
239
240 ret = binderfs_binder_device_create(inode, device, &device_req);
241 break;
242 default:
243 break;
244 }
245
246 return ret;
247 }
248
binderfs_evict_inode(struct inode * inode)249 static void binderfs_evict_inode(struct inode *inode)
250 {
251 struct binder_device *device = inode->i_private;
252 struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
253
254 clear_inode(inode);
255
256 if (!S_ISCHR(inode->i_mode) || !device)
257 return;
258
259 mutex_lock(&binderfs_minors_mutex);
260 --info->device_count;
261 ida_free(&binderfs_minors, device->miscdev.minor);
262 mutex_unlock(&binderfs_minors_mutex);
263
264 if (refcount_dec_and_test(&device->ref)) {
265 binder_remove_device(device);
266 kfree(device->context.name);
267 kfree(device);
268 }
269 }
270
binderfs_fs_context_parse_param(struct fs_context * fc,struct fs_parameter * param)271 static 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
binderfs_fs_context_reconfigure(struct fs_context * fc)302 static 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
binderfs_show_options(struct seq_file * seq,struct dentry * root)315 static 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
333 static const struct super_operations binderfs_super_ops = {
334 .evict_inode = binderfs_evict_inode,
335 .show_options = binderfs_show_options,
336 .statfs = simple_statfs,
337 };
338
is_binderfs_control_device(const struct dentry * dentry)339 static inline bool is_binderfs_control_device(const struct dentry *dentry)
340 {
341 struct binderfs_info *info = dentry->d_sb->s_fs_info;
342
343 return info->control_dentry == dentry;
344 }
345
binderfs_rename(const struct mnt_idmap * idmap,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)346 static int binderfs_rename(const struct mnt_idmap *idmap,
347 struct inode *old_dir, struct dentry *old_dentry,
348 struct inode *new_dir, struct dentry *new_dentry,
349 unsigned int flags)
350 {
351 if (is_binderfs_control_device(old_dentry) ||
352 is_binderfs_control_device(new_dentry))
353 return -EPERM;
354
355 return simple_rename(idmap, old_dir, old_dentry, new_dir,
356 new_dentry, flags);
357 }
358
binderfs_unlink(struct inode * dir,struct dentry * dentry)359 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
360 {
361 if (is_binderfs_control_device(dentry))
362 return -EPERM;
363
364 return simple_unlink(dir, dentry);
365 }
366
367 static const struct file_operations binder_ctl_fops = {
368 .owner = THIS_MODULE,
369 .open = nonseekable_open,
370 .unlocked_ioctl = binder_ctl_ioctl,
371 .compat_ioctl = binder_ctl_ioctl,
372 .llseek = noop_llseek,
373 };
374
375 /**
376 * binderfs_binder_ctl_create - create a new binder-control device
377 * @sb: super block of the binderfs mount
378 *
379 * This function creates a new binder-control device node in the binderfs mount
380 * referred to by @sb.
381 *
382 * Return: 0 on success, negative errno on failure
383 */
binderfs_binder_ctl_create(struct super_block * sb)384 static int binderfs_binder_ctl_create(struct super_block *sb)
385 {
386 int minor, ret;
387 struct dentry *dentry;
388 struct binder_device *device;
389 struct inode *inode = NULL;
390 struct dentry *root = sb->s_root;
391 struct binderfs_info *info = sb->s_fs_info;
392 #if defined(CONFIG_IPC_NS)
393 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
394 #else
395 bool use_reserve = true;
396 #endif
397
398 device = kzalloc_obj(*device);
399 if (!device)
400 return -ENOMEM;
401
402 ret = -ENOMEM;
403 inode = new_inode(sb);
404 if (!inode)
405 goto out;
406
407 /* Reserve a new minor number for the new device. */
408 mutex_lock(&binderfs_minors_mutex);
409 minor = ida_alloc_max(&binderfs_minors,
410 use_reserve ? BINDERFS_MAX_MINOR - 1 :
411 BINDERFS_MAX_MINOR_CAPPED - 1,
412 GFP_KERNEL);
413 mutex_unlock(&binderfs_minors_mutex);
414 if (minor < 0) {
415 ret = minor;
416 goto out;
417 }
418
419 inode->i_ino = SECOND_INODE;
420 simple_inode_init_ts(inode);
421 init_special_inode(inode, S_IFCHR | 0600,
422 MKDEV(MAJOR(binderfs_dev), minor));
423 inode->i_fop = &binder_ctl_fops;
424 inode->i_uid = info->root_uid;
425 inode->i_gid = info->root_gid;
426
427 refcount_set(&device->ref, 1);
428 device->binderfs_inode = inode;
429 device->miscdev.minor = minor;
430
431 dentry = d_alloc_name(root, "binder-control");
432 if (!dentry)
433 goto out;
434
435 inode->i_private = device;
436 info->control_dentry = dentry;
437 d_make_persistent(dentry, inode);
438 dput(dentry);
439
440 return 0;
441
442 out:
443 kfree(device);
444 iput(inode);
445
446 return ret;
447 }
448
449 static const struct inode_operations binderfs_dir_inode_operations = {
450 .lookup = simple_lookup,
451 .rename = binderfs_rename,
452 .unlink = binderfs_unlink,
453 };
454
binderfs_make_inode(struct super_block * sb,int mode)455 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
456 {
457 struct inode *ret;
458
459 ret = new_inode(sb);
460 if (ret) {
461 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
462 ret->i_mode = mode;
463 simple_inode_init_ts(ret);
464 }
465 return ret;
466 }
467
binderfs_create_file(struct dentry * parent,const char * name,const struct file_operations * fops,void * data)468 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
469 const struct file_operations *fops,
470 void *data)
471 {
472 struct dentry *dentry;
473 struct inode *new_inode, *parent_inode;
474 struct super_block *sb;
475
476 parent_inode = d_inode(parent);
477
478 dentry = simple_start_creating(parent, name);
479 if (IS_ERR(dentry))
480 return dentry;
481
482 sb = parent_inode->i_sb;
483 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
484 if (!new_inode) {
485 simple_done_creating(dentry);
486 return ERR_PTR(-ENOMEM);
487 }
488
489 new_inode->i_fop = fops;
490 new_inode->i_private = data;
491 d_make_persistent(dentry, new_inode);
492 fsnotify_create(parent_inode, dentry);
493 simple_done_creating(dentry);
494 return dentry; // borrowed
495 }
496
binderfs_create_dir(struct dentry * parent,const char * name)497 static struct dentry *binderfs_create_dir(struct dentry *parent,
498 const char *name)
499 {
500 struct dentry *dentry;
501 struct inode *new_inode, *parent_inode;
502 struct super_block *sb;
503
504 parent_inode = d_inode(parent);
505
506 dentry = simple_start_creating(parent, name);
507 if (IS_ERR(dentry))
508 return dentry;
509
510 sb = parent_inode->i_sb;
511 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
512 if (!new_inode) {
513 simple_done_creating(dentry);
514 return ERR_PTR(-ENOMEM);
515 }
516
517 new_inode->i_fop = &simple_dir_operations;
518 new_inode->i_op = &simple_dir_inode_operations;
519
520 set_nlink(new_inode, 2);
521 d_make_persistent(dentry, new_inode);
522 inc_nlink(parent_inode);
523 fsnotify_mkdir(parent_inode, dentry);
524 simple_done_creating(dentry);
525 return dentry;
526 }
527
binder_features_show(struct seq_file * m,void * unused)528 static int binder_features_show(struct seq_file *m, void *unused)
529 {
530 bool *feature = m->private;
531
532 seq_printf(m, "%d\n", *feature);
533
534 return 0;
535 }
536 DEFINE_SHOW_ATTRIBUTE(binder_features);
537
init_binder_features(struct super_block * sb)538 static int init_binder_features(struct super_block *sb)
539 {
540 struct dentry *dentry, *dir;
541
542 dir = binderfs_create_dir(sb->s_root, "features");
543 if (IS_ERR(dir))
544 return PTR_ERR(dir);
545
546 dentry = binderfs_create_file(dir, "oneway_spam_detection",
547 &binder_features_fops,
548 &binder_features.oneway_spam_detection);
549 if (IS_ERR(dentry))
550 return PTR_ERR(dentry);
551
552 dentry = binderfs_create_file(dir, "extended_error",
553 &binder_features_fops,
554 &binder_features.extended_error);
555 if (IS_ERR(dentry))
556 return PTR_ERR(dentry);
557
558 dentry = binderfs_create_file(dir, "freeze_notification",
559 &binder_features_fops,
560 &binder_features.freeze_notification);
561 if (IS_ERR(dentry))
562 return PTR_ERR(dentry);
563
564 dentry = binderfs_create_file(dir, "transaction_report",
565 &binder_features_fops,
566 &binder_features.transaction_report);
567 if (IS_ERR(dentry))
568 return PTR_ERR(dentry);
569
570 return 0;
571 }
572
init_binder_logs(struct super_block * sb)573 static int init_binder_logs(struct super_block *sb)
574 {
575 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
576 const struct binder_debugfs_entry *db_entry;
577 struct binderfs_info *info;
578 int ret = 0;
579
580 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
581 "binder_logs");
582 if (IS_ERR(binder_logs_root_dir)) {
583 ret = PTR_ERR(binder_logs_root_dir);
584 goto out;
585 }
586
587 binder_for_each_debugfs_entry(db_entry) {
588 dentry = binderfs_create_file(binder_logs_root_dir,
589 db_entry->name,
590 db_entry->fops,
591 db_entry->data);
592 if (IS_ERR(dentry)) {
593 ret = PTR_ERR(dentry);
594 goto out;
595 }
596 }
597
598 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
599 if (IS_ERR(proc_log_dir)) {
600 ret = PTR_ERR(proc_log_dir);
601 goto out;
602 }
603 info = sb->s_fs_info;
604 info->proc_log_dir = proc_log_dir;
605
606 out:
607 return ret;
608 }
609
binderfs_fill_super(struct super_block * sb,struct fs_context * fc)610 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
611 {
612 int ret;
613 struct binderfs_info *info;
614 struct binderfs_mount_opts *ctx = fc->fs_private;
615 struct inode *inode = NULL;
616 struct binderfs_device device_info = {};
617 const char *name;
618 size_t len;
619
620 sb->s_blocksize = PAGE_SIZE;
621 sb->s_blocksize_bits = PAGE_SHIFT;
622
623 /*
624 * The binderfs filesystem can be mounted by userns root in a
625 * non-initial userns. By default such mounts have the SB_I_NODEV flag
626 * set in s_iflags to prevent security issues where userns root can
627 * just create random device nodes via mknod() since it owns the
628 * filesystem mount. But binderfs does not allow to create any files
629 * including devices nodes. The only way to create binder devices nodes
630 * is through the binder-control device which userns root is explicitly
631 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
632 * necessary and safe.
633 */
634 sb->s_iflags &= ~SB_I_NODEV;
635 sb->s_iflags |= SB_I_NOEXEC;
636 sb->s_magic = BINDERFS_SUPER_MAGIC;
637 sb->s_op = &binderfs_super_ops;
638 sb->s_time_gran = 1;
639
640 sb->s_fs_info = kzalloc_obj(struct binderfs_info);
641 if (!sb->s_fs_info)
642 return -ENOMEM;
643 info = sb->s_fs_info;
644
645 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
646
647 info->root_gid = make_kgid(sb->s_user_ns, 0);
648 if (!gid_valid(info->root_gid))
649 info->root_gid = GLOBAL_ROOT_GID;
650 info->root_uid = make_kuid(sb->s_user_ns, 0);
651 if (!uid_valid(info->root_uid))
652 info->root_uid = GLOBAL_ROOT_UID;
653 info->mount_opts.max = ctx->max;
654 info->mount_opts.stats_mode = ctx->stats_mode;
655
656 inode = new_inode(sb);
657 if (!inode)
658 return -ENOMEM;
659
660 inode->i_ino = FIRST_INODE;
661 inode->i_fop = &simple_dir_operations;
662 inode->i_mode = S_IFDIR | 0755;
663 simple_inode_init_ts(inode);
664 inode->i_op = &binderfs_dir_inode_operations;
665 set_nlink(inode, 2);
666
667 sb->s_root = d_make_root(inode);
668 if (!sb->s_root)
669 return -ENOMEM;
670
671 ret = binderfs_binder_ctl_create(sb);
672 if (ret)
673 return ret;
674
675 name = binder_devices_param;
676 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
677 strscpy(device_info.name, name, len + 1);
678 ret = binderfs_binder_device_create(inode, NULL, &device_info);
679 if (ret)
680 return ret;
681 name += len;
682 if (*name == ',')
683 name++;
684 }
685
686 ret = init_binder_features(sb);
687 if (ret)
688 return ret;
689
690 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
691 return init_binder_logs(sb);
692
693 return 0;
694 }
695
binderfs_fs_context_get_tree(struct fs_context * fc)696 static int binderfs_fs_context_get_tree(struct fs_context *fc)
697 {
698 return get_tree_nodev(fc, binderfs_fill_super);
699 }
700
binderfs_fs_context_free(struct fs_context * fc)701 static void binderfs_fs_context_free(struct fs_context *fc)
702 {
703 struct binderfs_mount_opts *ctx = fc->fs_private;
704
705 kfree(ctx);
706 }
707
708 static const struct fs_context_operations binderfs_fs_context_ops = {
709 .free = binderfs_fs_context_free,
710 .get_tree = binderfs_fs_context_get_tree,
711 .parse_param = binderfs_fs_context_parse_param,
712 .reconfigure = binderfs_fs_context_reconfigure,
713 };
714
binderfs_init_fs_context(struct fs_context * fc)715 static int binderfs_init_fs_context(struct fs_context *fc)
716 {
717 struct binderfs_mount_opts *ctx;
718
719 ctx = kzalloc_obj(struct binderfs_mount_opts);
720 if (!ctx)
721 return -ENOMEM;
722
723 ctx->max = BINDERFS_MAX_MINOR;
724 ctx->stats_mode = binderfs_stats_mode_unset;
725
726 fc->fs_private = ctx;
727 fc->ops = &binderfs_fs_context_ops;
728
729 return 0;
730 }
731
binderfs_kill_super(struct super_block * sb)732 static void binderfs_kill_super(struct super_block *sb)
733 {
734 struct binderfs_info *info = sb->s_fs_info;
735
736 /*
737 * During inode eviction struct binderfs_info is needed.
738 * So first wipe the super_block then free struct binderfs_info.
739 */
740 kill_anon_super(sb);
741
742 if (info && info->ipc_ns)
743 put_ipc_ns(info->ipc_ns);
744
745 kfree(info);
746 }
747
748 static struct file_system_type binder_fs_type = {
749 .name = "binder",
750 .init_fs_context = binderfs_init_fs_context,
751 .parameters = binderfs_fs_parameters,
752 .kill_sb = binderfs_kill_super,
753 .fs_flags = FS_USERNS_MOUNT,
754 };
755
init_binderfs(void)756 int __init init_binderfs(void)
757 {
758 int ret;
759 const char *name;
760 size_t len;
761
762 /* Verify that the default binderfs device names are valid. */
763 name = binder_devices_param;
764 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
765 if (len > BINDERFS_MAX_NAME)
766 return -E2BIG;
767 name += len;
768 if (*name == ',')
769 name++;
770 }
771
772 /* Allocate new major number for binderfs. */
773 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
774 "binder");
775 if (ret)
776 return ret;
777
778 ret = register_filesystem(&binder_fs_type);
779 if (ret) {
780 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
781 return ret;
782 }
783
784 return ret;
785 }
786