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