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 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; 197 198 err: 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 */ 220 static 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 } 244 245 static 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 */ 268 static 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 } 317 318 static 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 } 336 337 static 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 } 349 350 static 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 }; 356 357 static 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 } 362 363 static 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 } 373 374 static 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 } 381 382 static 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 */ 399 static 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; 460 461 out: 462 kfree(device); 463 iput(inode); 464 465 return ret; 466 } 467 468 static const struct inode_operations binderfs_dir_inode_operations = { 469 .lookup = simple_lookup, 470 .rename = binderfs_rename, 471 .unlink = binderfs_unlink, 472 }; 473 474 static 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 } 486 487 static 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 } 504 505 void 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 } 519 520 struct 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); 547 548 out: 549 inode_unlock(parent_inode); 550 return dentry; 551 } 552 553 static 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); 582 583 out: 584 inode_unlock(parent_inode); 585 return dentry; 586 } 587 588 static 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; 647 648 out: 649 return ret; 650 } 651 652 static 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 } 734 735 static 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 } 741 742 static 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 } 753 754 static 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 }; 760 761 int __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 } 791