1 // SPDX-License-Identifier: GPL-2.0
2
3 #include <linux/compiler_types.h>
4 #include <linux/errno.h>
5 #include <linux/fs.h>
6 #include <linux/fsnotify.h>
7 #include <linux/gfp.h>
8 #include <linux/idr.h>
9 #include <linux/init.h>
10 #include <linux/ipc_namespace.h>
11 #include <linux/kdev_t.h>
12 #include <linux/kernel.h>
13 #include <linux/list.h>
14 #include <linux/namei.h>
15 #include <linux/magic.h>
16 #include <linux/major.h>
17 #include <linux/miscdevice.h>
18 #include <linux/module.h>
19 #include <linux/mutex.h>
20 #include <linux/mount.h>
21 #include <linux/fs_parser.h>
22 #include <linux/sched.h>
23 #include <linux/seq_file.h>
24 #include <linux/slab.h>
25 #include <linux/spinlock_types.h>
26 #include <linux/stddef.h>
27 #include <linux/string.h>
28 #include <linux/types.h>
29 #include <linux/uaccess.h>
30 #include <linux/user_namespace.h>
31 #include <linux/xarray.h>
32 #include <uapi/asm-generic/errno-base.h>
33 #include <uapi/linux/android/binder.h>
34 #include <uapi/linux/android/binderfs.h>
35
36 #include "binder_internal.h"
37
38 #define FIRST_INODE 1
39 #define SECOND_INODE 2
40 #define INODE_OFFSET 3
41 #define BINDERFS_MAX_MINOR (1U << MINORBITS)
42 /* Ensure that the initial ipc namespace always has devices available. */
43 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
44
45 static dev_t binderfs_dev;
46 static DEFINE_MUTEX(binderfs_minors_mutex);
47 static DEFINE_IDA(binderfs_minors);
48
49 enum binderfs_param {
50 Opt_max,
51 Opt_stats_mode,
52 };
53
54 enum binderfs_stats_mode {
55 binderfs_stats_mode_unset,
56 binderfs_stats_mode_global,
57 };
58
59 struct binder_features {
60 bool oneway_spam_detection;
61 bool extended_error;
62 };
63
64 static const struct constant_table binderfs_param_stats[] = {
65 { "global", binderfs_stats_mode_global },
66 {}
67 };
68
69 static const struct fs_parameter_spec binderfs_fs_parameters[] = {
70 fsparam_u32("max", Opt_max),
71 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats),
72 {}
73 };
74
75 static struct binder_features binder_features = {
76 .oneway_spam_detection = true,
77 .extended_error = true,
78 };
79
BINDERFS_SB(const struct super_block * sb)80 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
81 {
82 return sb->s_fs_info;
83 }
84
is_binderfs_device(const struct inode * inode)85 bool is_binderfs_device(const struct inode *inode)
86 {
87 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
88 return true;
89
90 return false;
91 }
92
93 /**
94 * binderfs_binder_device_create - allocate inode from super block of a
95 * binderfs mount
96 * @ref_inode: inode from wich the super block will be taken
97 * @userp: buffer to copy information about new device for userspace to
98 * @req: struct binderfs_device as copied from userspace
99 *
100 * This function allocates a new binder_device and reserves a new minor
101 * number for it.
102 * Minor numbers are limited and tracked globally in binderfs_minors. The
103 * function will stash a struct binder_device for the specific binder
104 * device in i_private of the inode.
105 * It will go on to allocate a new inode from the super block of the
106 * filesystem mount, stash a struct binder_device in its i_private field
107 * and attach a dentry to that inode.
108 *
109 * Return: 0 on success, negative errno on failure
110 */
binderfs_binder_device_create(struct inode * ref_inode,struct binderfs_device __user * userp,struct binderfs_device * req)111 static int binderfs_binder_device_create(struct inode *ref_inode,
112 struct binderfs_device __user *userp,
113 struct binderfs_device *req)
114 {
115 int minor, ret;
116 struct dentry *dentry, *root;
117 struct binder_device *device;
118 char *name = NULL;
119 size_t name_len;
120 struct inode *inode = NULL;
121 struct super_block *sb = ref_inode->i_sb;
122 struct binderfs_info *info = sb->s_fs_info;
123 #if defined(CONFIG_IPC_NS)
124 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
125 #else
126 bool use_reserve = true;
127 #endif
128
129 /* Reserve new minor number for the new device. */
130 mutex_lock(&binderfs_minors_mutex);
131 if (++info->device_count <= info->mount_opts.max)
132 minor = ida_alloc_max(&binderfs_minors,
133 use_reserve ? BINDERFS_MAX_MINOR :
134 BINDERFS_MAX_MINOR_CAPPED,
135 GFP_KERNEL);
136 else
137 minor = -ENOSPC;
138 if (minor < 0) {
139 --info->device_count;
140 mutex_unlock(&binderfs_minors_mutex);
141 return minor;
142 }
143 mutex_unlock(&binderfs_minors_mutex);
144
145 ret = -ENOMEM;
146 device = kzalloc(sizeof(*device), GFP_KERNEL);
147 if (!device)
148 goto err;
149
150 inode = new_inode(sb);
151 if (!inode)
152 goto err;
153
154 inode->i_ino = minor + INODE_OFFSET;
155 inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
156 init_special_inode(inode, S_IFCHR | 0600,
157 MKDEV(MAJOR(binderfs_dev), minor));
158 inode->i_fop = &binder_fops;
159 inode->i_uid = info->root_uid;
160 inode->i_gid = info->root_gid;
161
162 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
163 name_len = strlen(req->name);
164 /* Make sure to include terminating NUL byte */
165 name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
166 if (!name)
167 goto err;
168
169 refcount_set(&device->ref, 1);
170 device->binderfs_inode = inode;
171 device->context.binder_context_mgr_uid = INVALID_UID;
172 device->context.name = name;
173 device->miscdev.name = name;
174 device->miscdev.minor = minor;
175 mutex_init(&device->context.context_mgr_node_lock);
176
177 req->major = MAJOR(binderfs_dev);
178 req->minor = minor;
179
180 if (userp && copy_to_user(userp, req, sizeof(*req))) {
181 ret = -EFAULT;
182 goto err;
183 }
184
185 root = sb->s_root;
186 inode_lock(d_inode(root));
187
188 /* look it up */
189 dentry = lookup_one_len(name, root, name_len);
190 if (IS_ERR(dentry)) {
191 inode_unlock(d_inode(root));
192 ret = PTR_ERR(dentry);
193 goto err;
194 }
195
196 if (d_really_is_positive(dentry)) {
197 /* already exists */
198 dput(dentry);
199 inode_unlock(d_inode(root));
200 ret = -EEXIST;
201 goto err;
202 }
203
204 inode->i_private = device;
205 d_instantiate(dentry, inode);
206 fsnotify_create(root->d_inode, dentry);
207 inode_unlock(d_inode(root));
208
209 return 0;
210
211 err:
212 kfree(name);
213 kfree(device);
214 mutex_lock(&binderfs_minors_mutex);
215 --info->device_count;
216 ida_free(&binderfs_minors, minor);
217 mutex_unlock(&binderfs_minors_mutex);
218 iput(inode);
219
220 return ret;
221 }
222
223 /**
224 * binder_ctl_ioctl - handle binder device node allocation requests
225 *
226 * The request handler for the binder-control device. All requests operate on
227 * the binderfs mount the binder-control device resides in:
228 * - BINDER_CTL_ADD
229 * Allocate a new binder device.
230 *
231 * Return: %0 on success, negative errno on failure.
232 */
binder_ctl_ioctl(struct file * file,unsigned int cmd,unsigned long arg)233 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
234 unsigned long arg)
235 {
236 int ret = -EINVAL;
237 struct inode *inode = file_inode(file);
238 struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
239 struct binderfs_device device_req;
240
241 switch (cmd) {
242 case BINDER_CTL_ADD:
243 ret = copy_from_user(&device_req, device, sizeof(device_req));
244 if (ret) {
245 ret = -EFAULT;
246 break;
247 }
248
249 ret = binderfs_binder_device_create(inode, device, &device_req);
250 break;
251 default:
252 break;
253 }
254
255 return ret;
256 }
257
binderfs_evict_inode(struct inode * inode)258 static void binderfs_evict_inode(struct inode *inode)
259 {
260 struct binder_device *device = inode->i_private;
261 struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
262
263 clear_inode(inode);
264
265 if (!S_ISCHR(inode->i_mode) || !device)
266 return;
267
268 mutex_lock(&binderfs_minors_mutex);
269 --info->device_count;
270 ida_free(&binderfs_minors, device->miscdev.minor);
271 mutex_unlock(&binderfs_minors_mutex);
272
273 if (refcount_dec_and_test(&device->ref)) {
274 kfree(device->context.name);
275 kfree(device);
276 }
277 }
278
binderfs_fs_context_parse_param(struct fs_context * fc,struct fs_parameter * param)279 static int binderfs_fs_context_parse_param(struct fs_context *fc,
280 struct fs_parameter *param)
281 {
282 int opt;
283 struct binderfs_mount_opts *ctx = fc->fs_private;
284 struct fs_parse_result result;
285
286 opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
287 if (opt < 0)
288 return opt;
289
290 switch (opt) {
291 case Opt_max:
292 if (result.uint_32 > BINDERFS_MAX_MINOR)
293 return invalfc(fc, "Bad value for '%s'", param->key);
294
295 ctx->max = result.uint_32;
296 break;
297 case Opt_stats_mode:
298 if (!capable(CAP_SYS_ADMIN))
299 return -EPERM;
300
301 ctx->stats_mode = result.uint_32;
302 break;
303 default:
304 return invalfc(fc, "Unsupported parameter '%s'", param->key);
305 }
306
307 return 0;
308 }
309
binderfs_fs_context_reconfigure(struct fs_context * fc)310 static int binderfs_fs_context_reconfigure(struct fs_context *fc)
311 {
312 struct binderfs_mount_opts *ctx = fc->fs_private;
313 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
314
315 if (info->mount_opts.stats_mode != ctx->stats_mode)
316 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
317
318 info->mount_opts.stats_mode = ctx->stats_mode;
319 info->mount_opts.max = ctx->max;
320 return 0;
321 }
322
binderfs_show_options(struct seq_file * seq,struct dentry * root)323 static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
324 {
325 struct binderfs_info *info = BINDERFS_SB(root->d_sb);
326
327 if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
328 seq_printf(seq, ",max=%d", info->mount_opts.max);
329
330 switch (info->mount_opts.stats_mode) {
331 case binderfs_stats_mode_unset:
332 break;
333 case binderfs_stats_mode_global:
334 seq_printf(seq, ",stats=global");
335 break;
336 }
337
338 return 0;
339 }
340
341 static const struct super_operations binderfs_super_ops = {
342 .evict_inode = binderfs_evict_inode,
343 .show_options = binderfs_show_options,
344 .statfs = simple_statfs,
345 };
346
is_binderfs_control_device(const struct dentry * dentry)347 static inline bool is_binderfs_control_device(const struct dentry *dentry)
348 {
349 struct binderfs_info *info = dentry->d_sb->s_fs_info;
350
351 return info->control_dentry == dentry;
352 }
353
binderfs_rename(struct mnt_idmap * idmap,struct inode * old_dir,struct dentry * old_dentry,struct inode * new_dir,struct dentry * new_dentry,unsigned int flags)354 static int binderfs_rename(struct mnt_idmap *idmap,
355 struct inode *old_dir, struct dentry *old_dentry,
356 struct inode *new_dir, struct dentry *new_dentry,
357 unsigned int flags)
358 {
359 if (is_binderfs_control_device(old_dentry) ||
360 is_binderfs_control_device(new_dentry))
361 return -EPERM;
362
363 return simple_rename(idmap, old_dir, old_dentry, new_dir,
364 new_dentry, flags);
365 }
366
binderfs_unlink(struct inode * dir,struct dentry * dentry)367 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
368 {
369 if (is_binderfs_control_device(dentry))
370 return -EPERM;
371
372 return simple_unlink(dir, dentry);
373 }
374
375 static const struct file_operations binder_ctl_fops = {
376 .owner = THIS_MODULE,
377 .open = nonseekable_open,
378 .unlocked_ioctl = binder_ctl_ioctl,
379 .compat_ioctl = binder_ctl_ioctl,
380 .llseek = noop_llseek,
381 };
382
383 /**
384 * binderfs_binder_ctl_create - create a new binder-control device
385 * @sb: super block of the binderfs mount
386 *
387 * This function creates a new binder-control device node in the binderfs mount
388 * referred to by @sb.
389 *
390 * Return: 0 on success, negative errno on failure
391 */
binderfs_binder_ctl_create(struct super_block * sb)392 static int binderfs_binder_ctl_create(struct super_block *sb)
393 {
394 int minor, ret;
395 struct dentry *dentry;
396 struct binder_device *device;
397 struct inode *inode = NULL;
398 struct dentry *root = sb->s_root;
399 struct binderfs_info *info = sb->s_fs_info;
400 #if defined(CONFIG_IPC_NS)
401 bool use_reserve = (info->ipc_ns == &init_ipc_ns);
402 #else
403 bool use_reserve = true;
404 #endif
405
406 device = kzalloc(sizeof(*device), GFP_KERNEL);
407 if (!device)
408 return -ENOMEM;
409
410 /* If we have already created a binder-control node, return. */
411 if (info->control_dentry) {
412 ret = 0;
413 goto out;
414 }
415
416 ret = -ENOMEM;
417 inode = new_inode(sb);
418 if (!inode)
419 goto out;
420
421 /* Reserve a new minor number for the new device. */
422 mutex_lock(&binderfs_minors_mutex);
423 minor = ida_alloc_max(&binderfs_minors,
424 use_reserve ? BINDERFS_MAX_MINOR :
425 BINDERFS_MAX_MINOR_CAPPED,
426 GFP_KERNEL);
427 mutex_unlock(&binderfs_minors_mutex);
428 if (minor < 0) {
429 ret = minor;
430 goto out;
431 }
432
433 inode->i_ino = SECOND_INODE;
434 inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
435 init_special_inode(inode, S_IFCHR | 0600,
436 MKDEV(MAJOR(binderfs_dev), minor));
437 inode->i_fop = &binder_ctl_fops;
438 inode->i_uid = info->root_uid;
439 inode->i_gid = info->root_gid;
440
441 refcount_set(&device->ref, 1);
442 device->binderfs_inode = inode;
443 device->miscdev.minor = minor;
444
445 dentry = d_alloc_name(root, "binder-control");
446 if (!dentry)
447 goto out;
448
449 inode->i_private = device;
450 info->control_dentry = dentry;
451 d_add(dentry, inode);
452
453 return 0;
454
455 out:
456 kfree(device);
457 iput(inode);
458
459 return ret;
460 }
461
462 static const struct inode_operations binderfs_dir_inode_operations = {
463 .lookup = simple_lookup,
464 .rename = binderfs_rename,
465 .unlink = binderfs_unlink,
466 };
467
binderfs_make_inode(struct super_block * sb,int mode)468 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
469 {
470 struct inode *ret;
471
472 ret = new_inode(sb);
473 if (ret) {
474 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
475 ret->i_mode = mode;
476 ret->i_atime = ret->i_mtime = inode_set_ctime_current(ret);
477 }
478 return ret;
479 }
480
binderfs_create_dentry(struct dentry * parent,const char * name)481 static struct dentry *binderfs_create_dentry(struct dentry *parent,
482 const char *name)
483 {
484 struct dentry *dentry;
485
486 dentry = lookup_one_len(name, parent, strlen(name));
487 if (IS_ERR(dentry))
488 return dentry;
489
490 /* Return error if the file/dir already exists. */
491 if (d_really_is_positive(dentry)) {
492 dput(dentry);
493 return ERR_PTR(-EEXIST);
494 }
495
496 return dentry;
497 }
498
binderfs_remove_file(struct dentry * dentry)499 void binderfs_remove_file(struct dentry *dentry)
500 {
501 struct inode *parent_inode;
502
503 parent_inode = d_inode(dentry->d_parent);
504 inode_lock(parent_inode);
505 if (simple_positive(dentry)) {
506 dget(dentry);
507 simple_unlink(parent_inode, dentry);
508 d_delete(dentry);
509 dput(dentry);
510 }
511 inode_unlock(parent_inode);
512 }
513
binderfs_create_file(struct dentry * parent,const char * name,const struct file_operations * fops,void * data)514 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
515 const struct file_operations *fops,
516 void *data)
517 {
518 struct dentry *dentry;
519 struct inode *new_inode, *parent_inode;
520 struct super_block *sb;
521
522 parent_inode = d_inode(parent);
523 inode_lock(parent_inode);
524
525 dentry = binderfs_create_dentry(parent, name);
526 if (IS_ERR(dentry))
527 goto out;
528
529 sb = parent_inode->i_sb;
530 new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
531 if (!new_inode) {
532 dput(dentry);
533 dentry = ERR_PTR(-ENOMEM);
534 goto out;
535 }
536
537 new_inode->i_fop = fops;
538 new_inode->i_private = data;
539 d_instantiate(dentry, new_inode);
540 fsnotify_create(parent_inode, dentry);
541
542 out:
543 inode_unlock(parent_inode);
544 return dentry;
545 }
546
binderfs_create_dir(struct dentry * parent,const char * name)547 static struct dentry *binderfs_create_dir(struct dentry *parent,
548 const char *name)
549 {
550 struct dentry *dentry;
551 struct inode *new_inode, *parent_inode;
552 struct super_block *sb;
553
554 parent_inode = d_inode(parent);
555 inode_lock(parent_inode);
556
557 dentry = binderfs_create_dentry(parent, name);
558 if (IS_ERR(dentry))
559 goto out;
560
561 sb = parent_inode->i_sb;
562 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
563 if (!new_inode) {
564 dput(dentry);
565 dentry = ERR_PTR(-ENOMEM);
566 goto out;
567 }
568
569 new_inode->i_fop = &simple_dir_operations;
570 new_inode->i_op = &simple_dir_inode_operations;
571
572 set_nlink(new_inode, 2);
573 d_instantiate(dentry, new_inode);
574 inc_nlink(parent_inode);
575 fsnotify_mkdir(parent_inode, dentry);
576
577 out:
578 inode_unlock(parent_inode);
579 return dentry;
580 }
581
binder_features_show(struct seq_file * m,void * unused)582 static int binder_features_show(struct seq_file *m, void *unused)
583 {
584 bool *feature = m->private;
585
586 seq_printf(m, "%d\n", *feature);
587
588 return 0;
589 }
590 DEFINE_SHOW_ATTRIBUTE(binder_features);
591
init_binder_features(struct super_block * sb)592 static int init_binder_features(struct super_block *sb)
593 {
594 struct dentry *dentry, *dir;
595
596 dir = binderfs_create_dir(sb->s_root, "features");
597 if (IS_ERR(dir))
598 return PTR_ERR(dir);
599
600 dentry = binderfs_create_file(dir, "oneway_spam_detection",
601 &binder_features_fops,
602 &binder_features.oneway_spam_detection);
603 if (IS_ERR(dentry))
604 return PTR_ERR(dentry);
605
606 dentry = binderfs_create_file(dir, "extended_error",
607 &binder_features_fops,
608 &binder_features.extended_error);
609 if (IS_ERR(dentry))
610 return PTR_ERR(dentry);
611
612 return 0;
613 }
614
init_binder_logs(struct super_block * sb)615 static int init_binder_logs(struct super_block *sb)
616 {
617 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
618 const struct binder_debugfs_entry *db_entry;
619 struct binderfs_info *info;
620 int ret = 0;
621
622 binder_logs_root_dir = binderfs_create_dir(sb->s_root,
623 "binder_logs");
624 if (IS_ERR(binder_logs_root_dir)) {
625 ret = PTR_ERR(binder_logs_root_dir);
626 goto out;
627 }
628
629 binder_for_each_debugfs_entry(db_entry) {
630 dentry = binderfs_create_file(binder_logs_root_dir,
631 db_entry->name,
632 db_entry->fops,
633 db_entry->data);
634 if (IS_ERR(dentry)) {
635 ret = PTR_ERR(dentry);
636 goto out;
637 }
638 }
639
640 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
641 if (IS_ERR(proc_log_dir)) {
642 ret = PTR_ERR(proc_log_dir);
643 goto out;
644 }
645 info = sb->s_fs_info;
646 info->proc_log_dir = proc_log_dir;
647
648 out:
649 return ret;
650 }
651
binderfs_fill_super(struct super_block * sb,struct fs_context * fc)652 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
653 {
654 int ret;
655 struct binderfs_info *info;
656 struct binderfs_mount_opts *ctx = fc->fs_private;
657 struct inode *inode = NULL;
658 struct binderfs_device device_info = {};
659 const char *name;
660 size_t len;
661
662 sb->s_blocksize = PAGE_SIZE;
663 sb->s_blocksize_bits = PAGE_SHIFT;
664
665 /*
666 * The binderfs filesystem can be mounted by userns root in a
667 * non-initial userns. By default such mounts have the SB_I_NODEV flag
668 * set in s_iflags to prevent security issues where userns root can
669 * just create random device nodes via mknod() since it owns the
670 * filesystem mount. But binderfs does not allow to create any files
671 * including devices nodes. The only way to create binder devices nodes
672 * is through the binder-control device which userns root is explicitly
673 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
674 * necessary and safe.
675 */
676 sb->s_iflags &= ~SB_I_NODEV;
677 sb->s_iflags |= SB_I_NOEXEC;
678 sb->s_magic = BINDERFS_SUPER_MAGIC;
679 sb->s_op = &binderfs_super_ops;
680 sb->s_time_gran = 1;
681
682 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
683 if (!sb->s_fs_info)
684 return -ENOMEM;
685 info = sb->s_fs_info;
686
687 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
688
689 info->root_gid = make_kgid(sb->s_user_ns, 0);
690 if (!gid_valid(info->root_gid))
691 info->root_gid = GLOBAL_ROOT_GID;
692 info->root_uid = make_kuid(sb->s_user_ns, 0);
693 if (!uid_valid(info->root_uid))
694 info->root_uid = GLOBAL_ROOT_UID;
695 info->mount_opts.max = ctx->max;
696 info->mount_opts.stats_mode = ctx->stats_mode;
697
698 inode = new_inode(sb);
699 if (!inode)
700 return -ENOMEM;
701
702 inode->i_ino = FIRST_INODE;
703 inode->i_fop = &simple_dir_operations;
704 inode->i_mode = S_IFDIR | 0755;
705 inode->i_mtime = inode->i_atime = inode_set_ctime_current(inode);
706 inode->i_op = &binderfs_dir_inode_operations;
707 set_nlink(inode, 2);
708
709 sb->s_root = d_make_root(inode);
710 if (!sb->s_root)
711 return -ENOMEM;
712
713 ret = binderfs_binder_ctl_create(sb);
714 if (ret)
715 return ret;
716
717 name = binder_devices_param;
718 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
719 strscpy(device_info.name, name, len + 1);
720 ret = binderfs_binder_device_create(inode, NULL, &device_info);
721 if (ret)
722 return ret;
723 name += len;
724 if (*name == ',')
725 name++;
726 }
727
728 ret = init_binder_features(sb);
729 if (ret)
730 return ret;
731
732 if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
733 return init_binder_logs(sb);
734
735 return 0;
736 }
737
binderfs_fs_context_get_tree(struct fs_context * fc)738 static int binderfs_fs_context_get_tree(struct fs_context *fc)
739 {
740 return get_tree_nodev(fc, binderfs_fill_super);
741 }
742
binderfs_fs_context_free(struct fs_context * fc)743 static void binderfs_fs_context_free(struct fs_context *fc)
744 {
745 struct binderfs_mount_opts *ctx = fc->fs_private;
746
747 kfree(ctx);
748 }
749
750 static const struct fs_context_operations binderfs_fs_context_ops = {
751 .free = binderfs_fs_context_free,
752 .get_tree = binderfs_fs_context_get_tree,
753 .parse_param = binderfs_fs_context_parse_param,
754 .reconfigure = binderfs_fs_context_reconfigure,
755 };
756
binderfs_init_fs_context(struct fs_context * fc)757 static int binderfs_init_fs_context(struct fs_context *fc)
758 {
759 struct binderfs_mount_opts *ctx;
760
761 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
762 if (!ctx)
763 return -ENOMEM;
764
765 ctx->max = BINDERFS_MAX_MINOR;
766 ctx->stats_mode = binderfs_stats_mode_unset;
767
768 fc->fs_private = ctx;
769 fc->ops = &binderfs_fs_context_ops;
770
771 return 0;
772 }
773
binderfs_kill_super(struct super_block * sb)774 static void binderfs_kill_super(struct super_block *sb)
775 {
776 struct binderfs_info *info = sb->s_fs_info;
777
778 /*
779 * During inode eviction struct binderfs_info is needed.
780 * So first wipe the super_block then free struct binderfs_info.
781 */
782 kill_litter_super(sb);
783
784 if (info && info->ipc_ns)
785 put_ipc_ns(info->ipc_ns);
786
787 kfree(info);
788 }
789
790 static struct file_system_type binder_fs_type = {
791 .name = "binder",
792 .init_fs_context = binderfs_init_fs_context,
793 .parameters = binderfs_fs_parameters,
794 .kill_sb = binderfs_kill_super,
795 .fs_flags = FS_USERNS_MOUNT,
796 };
797
init_binderfs(void)798 int __init init_binderfs(void)
799 {
800 int ret;
801 const char *name;
802 size_t len;
803
804 /* Verify that the default binderfs device names are valid. */
805 name = binder_devices_param;
806 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
807 if (len > BINDERFS_MAX_NAME)
808 return -E2BIG;
809 name += len;
810 if (*name == ',')
811 name++;
812 }
813
814 /* Allocate new major number for binderfs. */
815 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
816 "binder");
817 if (ret)
818 return ret;
819
820 ret = register_filesystem(&binder_fs_type);
821 if (ret) {
822 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
823 return ret;
824 }
825
826 return ret;
827 }
828