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/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 binderfs_param { 52 Opt_max, 53 Opt_stats_mode, 54 }; 55 56 enum binderfs_stats_mode { 57 binderfs_stats_mode_unset, 58 binderfs_stats_mode_global, 59 }; 60 61 static const struct constant_table binderfs_param_stats[] = { 62 { "global", binderfs_stats_mode_global }, 63 {} 64 }; 65 66 static const struct fs_parameter_spec binderfs_fs_parameters[] = { 67 fsparam_u32("max", Opt_max), 68 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats), 69 {} 70 }; 71 72 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb) 73 { 74 return sb->s_fs_info; 75 } 76 77 bool is_binderfs_device(const struct inode *inode) 78 { 79 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC) 80 return true; 81 82 return false; 83 } 84 85 /** 86 * binderfs_binder_device_create - allocate inode from super block of a 87 * binderfs mount 88 * @ref_inode: inode from wich the super block will be taken 89 * @userp: buffer to copy information about new device for userspace to 90 * @req: struct binderfs_device as copied from userspace 91 * 92 * This function allocates a new binder_device and reserves a new minor 93 * number for it. 94 * Minor numbers are limited and tracked globally in binderfs_minors. The 95 * function will stash a struct binder_device for the specific binder 96 * device in i_private of the inode. 97 * It will go on to allocate a new inode from the super block of the 98 * filesystem mount, stash a struct binder_device in its i_private field 99 * and attach a dentry to that inode. 100 * 101 * Return: 0 on success, negative errno on failure 102 */ 103 static int binderfs_binder_device_create(struct inode *ref_inode, 104 struct binderfs_device __user *userp, 105 struct binderfs_device *req) 106 { 107 int minor, ret; 108 struct dentry *dentry, *root; 109 struct binder_device *device; 110 char *name = NULL; 111 size_t name_len; 112 struct inode *inode = NULL; 113 struct super_block *sb = ref_inode->i_sb; 114 struct binderfs_info *info = sb->s_fs_info; 115 #if defined(CONFIG_IPC_NS) 116 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 117 #else 118 bool use_reserve = true; 119 #endif 120 121 /* Reserve new minor number for the new device. */ 122 mutex_lock(&binderfs_minors_mutex); 123 if (++info->device_count <= info->mount_opts.max) 124 minor = ida_alloc_max(&binderfs_minors, 125 use_reserve ? BINDERFS_MAX_MINOR : 126 BINDERFS_MAX_MINOR_CAPPED, 127 GFP_KERNEL); 128 else 129 minor = -ENOSPC; 130 if (minor < 0) { 131 --info->device_count; 132 mutex_unlock(&binderfs_minors_mutex); 133 return minor; 134 } 135 mutex_unlock(&binderfs_minors_mutex); 136 137 ret = -ENOMEM; 138 device = kzalloc(sizeof(*device), GFP_KERNEL); 139 if (!device) 140 goto err; 141 142 inode = new_inode(sb); 143 if (!inode) 144 goto err; 145 146 inode->i_ino = minor + INODE_OFFSET; 147 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 148 init_special_inode(inode, S_IFCHR | 0600, 149 MKDEV(MAJOR(binderfs_dev), minor)); 150 inode->i_fop = &binder_fops; 151 inode->i_uid = info->root_uid; 152 inode->i_gid = info->root_gid; 153 154 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */ 155 name_len = strlen(req->name); 156 /* Make sure to include terminating NUL byte */ 157 name = kmemdup(req->name, name_len + 1, GFP_KERNEL); 158 if (!name) 159 goto err; 160 161 refcount_set(&device->ref, 1); 162 device->binderfs_inode = inode; 163 device->context.binder_context_mgr_uid = INVALID_UID; 164 device->context.name = name; 165 device->miscdev.name = name; 166 device->miscdev.minor = minor; 167 mutex_init(&device->context.context_mgr_node_lock); 168 169 req->major = MAJOR(binderfs_dev); 170 req->minor = minor; 171 172 if (userp && copy_to_user(userp, req, sizeof(*req))) { 173 ret = -EFAULT; 174 goto err; 175 } 176 177 root = sb->s_root; 178 inode_lock(d_inode(root)); 179 180 /* look it up */ 181 dentry = lookup_one_len(name, root, name_len); 182 if (IS_ERR(dentry)) { 183 inode_unlock(d_inode(root)); 184 ret = PTR_ERR(dentry); 185 goto err; 186 } 187 188 if (d_really_is_positive(dentry)) { 189 /* already exists */ 190 dput(dentry); 191 inode_unlock(d_inode(root)); 192 ret = -EEXIST; 193 goto err; 194 } 195 196 inode->i_private = device; 197 d_instantiate(dentry, inode); 198 fsnotify_create(root->d_inode, dentry); 199 inode_unlock(d_inode(root)); 200 201 return 0; 202 203 err: 204 kfree(name); 205 kfree(device); 206 mutex_lock(&binderfs_minors_mutex); 207 --info->device_count; 208 ida_free(&binderfs_minors, minor); 209 mutex_unlock(&binderfs_minors_mutex); 210 iput(inode); 211 212 return ret; 213 } 214 215 /** 216 * binderfs_ctl_ioctl - handle binder device node allocation requests 217 * 218 * The request handler for the binder-control device. All requests operate on 219 * the binderfs mount the binder-control device resides in: 220 * - BINDER_CTL_ADD 221 * Allocate a new binder device. 222 * 223 * Return: 0 on success, negative errno on failure 224 */ 225 static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 226 unsigned long arg) 227 { 228 int ret = -EINVAL; 229 struct inode *inode = file_inode(file); 230 struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 231 struct binderfs_device device_req; 232 233 switch (cmd) { 234 case BINDER_CTL_ADD: 235 ret = copy_from_user(&device_req, device, sizeof(device_req)); 236 if (ret) { 237 ret = -EFAULT; 238 break; 239 } 240 241 ret = binderfs_binder_device_create(inode, device, &device_req); 242 break; 243 default: 244 break; 245 } 246 247 return ret; 248 } 249 250 static void binderfs_evict_inode(struct inode *inode) 251 { 252 struct binder_device *device = inode->i_private; 253 struct binderfs_info *info = BINDERFS_SB(inode->i_sb); 254 255 clear_inode(inode); 256 257 if (!S_ISCHR(inode->i_mode) || !device) 258 return; 259 260 mutex_lock(&binderfs_minors_mutex); 261 --info->device_count; 262 ida_free(&binderfs_minors, device->miscdev.minor); 263 mutex_unlock(&binderfs_minors_mutex); 264 265 if (refcount_dec_and_test(&device->ref)) { 266 kfree(device->context.name); 267 kfree(device); 268 } 269 } 270 271 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 } 301 302 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 } 314 315 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 void binderfs_put_super(struct super_block *sb) 334 { 335 struct binderfs_info *info = sb->s_fs_info; 336 337 if (info && info->ipc_ns) 338 put_ipc_ns(info->ipc_ns); 339 340 kfree(info); 341 sb->s_fs_info = NULL; 342 } 343 344 static const struct super_operations binderfs_super_ops = { 345 .evict_inode = binderfs_evict_inode, 346 .show_options = binderfs_show_options, 347 .statfs = simple_statfs, 348 .put_super = binderfs_put_super, 349 }; 350 351 static inline bool is_binderfs_control_device(const struct dentry *dentry) 352 { 353 struct binderfs_info *info = dentry->d_sb->s_fs_info; 354 355 return info->control_dentry == dentry; 356 } 357 358 static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry, 359 struct inode *new_dir, struct dentry *new_dentry, 360 unsigned int flags) 361 { 362 if (is_binderfs_control_device(old_dentry) || 363 is_binderfs_control_device(new_dentry)) 364 return -EPERM; 365 366 return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags); 367 } 368 369 static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 370 { 371 if (is_binderfs_control_device(dentry)) 372 return -EPERM; 373 374 return simple_unlink(dir, dentry); 375 } 376 377 static const struct file_operations binder_ctl_fops = { 378 .owner = THIS_MODULE, 379 .open = nonseekable_open, 380 .unlocked_ioctl = binder_ctl_ioctl, 381 .compat_ioctl = binder_ctl_ioctl, 382 .llseek = noop_llseek, 383 }; 384 385 /** 386 * binderfs_binder_ctl_create - create a new binder-control device 387 * @sb: super block of the binderfs mount 388 * 389 * This function creates a new binder-control device node in the binderfs mount 390 * referred to by @sb. 391 * 392 * Return: 0 on success, negative errno on failure 393 */ 394 static int binderfs_binder_ctl_create(struct super_block *sb) 395 { 396 int minor, ret; 397 struct dentry *dentry; 398 struct binder_device *device; 399 struct inode *inode = NULL; 400 struct dentry *root = sb->s_root; 401 struct binderfs_info *info = sb->s_fs_info; 402 #if defined(CONFIG_IPC_NS) 403 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 404 #else 405 bool use_reserve = true; 406 #endif 407 408 device = kzalloc(sizeof(*device), GFP_KERNEL); 409 if (!device) 410 return -ENOMEM; 411 412 /* If we have already created a binder-control node, return. */ 413 if (info->control_dentry) { 414 ret = 0; 415 goto out; 416 } 417 418 ret = -ENOMEM; 419 inode = new_inode(sb); 420 if (!inode) 421 goto out; 422 423 /* Reserve a new minor number for the new device. */ 424 mutex_lock(&binderfs_minors_mutex); 425 minor = ida_alloc_max(&binderfs_minors, 426 use_reserve ? BINDERFS_MAX_MINOR : 427 BINDERFS_MAX_MINOR_CAPPED, 428 GFP_KERNEL); 429 mutex_unlock(&binderfs_minors_mutex); 430 if (minor < 0) { 431 ret = minor; 432 goto out; 433 } 434 435 inode->i_ino = SECOND_INODE; 436 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 437 init_special_inode(inode, S_IFCHR | 0600, 438 MKDEV(MAJOR(binderfs_dev), minor)); 439 inode->i_fop = &binder_ctl_fops; 440 inode->i_uid = info->root_uid; 441 inode->i_gid = info->root_gid; 442 443 refcount_set(&device->ref, 1); 444 device->binderfs_inode = inode; 445 device->miscdev.minor = minor; 446 447 dentry = d_alloc_name(root, "binder-control"); 448 if (!dentry) 449 goto out; 450 451 inode->i_private = device; 452 info->control_dentry = dentry; 453 d_add(dentry, inode); 454 455 return 0; 456 457 out: 458 kfree(device); 459 iput(inode); 460 461 return ret; 462 } 463 464 static const struct inode_operations binderfs_dir_inode_operations = { 465 .lookup = simple_lookup, 466 .rename = binderfs_rename, 467 .unlink = binderfs_unlink, 468 }; 469 470 static struct inode *binderfs_make_inode(struct super_block *sb, int mode) 471 { 472 struct inode *ret; 473 474 ret = new_inode(sb); 475 if (ret) { 476 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET); 477 ret->i_mode = mode; 478 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret); 479 } 480 return ret; 481 } 482 483 static struct dentry *binderfs_create_dentry(struct dentry *parent, 484 const char *name) 485 { 486 struct dentry *dentry; 487 488 dentry = lookup_one_len(name, parent, strlen(name)); 489 if (IS_ERR(dentry)) 490 return dentry; 491 492 /* Return error if the file/dir already exists. */ 493 if (d_really_is_positive(dentry)) { 494 dput(dentry); 495 return ERR_PTR(-EEXIST); 496 } 497 498 return dentry; 499 } 500 501 void binderfs_remove_file(struct dentry *dentry) 502 { 503 struct inode *parent_inode; 504 505 parent_inode = d_inode(dentry->d_parent); 506 inode_lock(parent_inode); 507 if (simple_positive(dentry)) { 508 dget(dentry); 509 simple_unlink(parent_inode, dentry); 510 d_delete(dentry); 511 dput(dentry); 512 } 513 inode_unlock(parent_inode); 514 } 515 516 struct dentry *binderfs_create_file(struct dentry *parent, const char *name, 517 const struct file_operations *fops, 518 void *data) 519 { 520 struct dentry *dentry; 521 struct inode *new_inode, *parent_inode; 522 struct super_block *sb; 523 524 parent_inode = d_inode(parent); 525 inode_lock(parent_inode); 526 527 dentry = binderfs_create_dentry(parent, name); 528 if (IS_ERR(dentry)) 529 goto out; 530 531 sb = parent_inode->i_sb; 532 new_inode = binderfs_make_inode(sb, S_IFREG | 0444); 533 if (!new_inode) { 534 dput(dentry); 535 dentry = ERR_PTR(-ENOMEM); 536 goto out; 537 } 538 539 new_inode->i_fop = fops; 540 new_inode->i_private = data; 541 d_instantiate(dentry, new_inode); 542 fsnotify_create(parent_inode, dentry); 543 544 out: 545 inode_unlock(parent_inode); 546 return dentry; 547 } 548 549 static struct dentry *binderfs_create_dir(struct dentry *parent, 550 const char *name) 551 { 552 struct dentry *dentry; 553 struct inode *new_inode, *parent_inode; 554 struct super_block *sb; 555 556 parent_inode = d_inode(parent); 557 inode_lock(parent_inode); 558 559 dentry = binderfs_create_dentry(parent, name); 560 if (IS_ERR(dentry)) 561 goto out; 562 563 sb = parent_inode->i_sb; 564 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755); 565 if (!new_inode) { 566 dput(dentry); 567 dentry = ERR_PTR(-ENOMEM); 568 goto out; 569 } 570 571 new_inode->i_fop = &simple_dir_operations; 572 new_inode->i_op = &simple_dir_inode_operations; 573 574 set_nlink(new_inode, 2); 575 d_instantiate(dentry, new_inode); 576 inc_nlink(parent_inode); 577 fsnotify_mkdir(parent_inode, dentry); 578 579 out: 580 inode_unlock(parent_inode); 581 return dentry; 582 } 583 584 static int init_binder_logs(struct super_block *sb) 585 { 586 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 587 struct binderfs_info *info; 588 int ret = 0; 589 590 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 591 "binder_logs"); 592 if (IS_ERR(binder_logs_root_dir)) { 593 ret = PTR_ERR(binder_logs_root_dir); 594 goto out; 595 } 596 597 dentry = binderfs_create_file(binder_logs_root_dir, "stats", 598 &binder_stats_fops, NULL); 599 if (IS_ERR(dentry)) { 600 ret = PTR_ERR(dentry); 601 goto out; 602 } 603 604 dentry = binderfs_create_file(binder_logs_root_dir, "state", 605 &binder_state_fops, NULL); 606 if (IS_ERR(dentry)) { 607 ret = PTR_ERR(dentry); 608 goto out; 609 } 610 611 dentry = binderfs_create_file(binder_logs_root_dir, "transactions", 612 &binder_transactions_fops, NULL); 613 if (IS_ERR(dentry)) { 614 ret = PTR_ERR(dentry); 615 goto out; 616 } 617 618 dentry = binderfs_create_file(binder_logs_root_dir, 619 "transaction_log", 620 &binder_transaction_log_fops, 621 &binder_transaction_log); 622 if (IS_ERR(dentry)) { 623 ret = PTR_ERR(dentry); 624 goto out; 625 } 626 627 dentry = binderfs_create_file(binder_logs_root_dir, 628 "failed_transaction_log", 629 &binder_transaction_log_fops, 630 &binder_transaction_log_failed); 631 if (IS_ERR(dentry)) { 632 ret = PTR_ERR(dentry); 633 goto out; 634 } 635 636 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 637 if (IS_ERR(proc_log_dir)) { 638 ret = PTR_ERR(proc_log_dir); 639 goto out; 640 } 641 info = sb->s_fs_info; 642 info->proc_log_dir = proc_log_dir; 643 644 out: 645 return ret; 646 } 647 648 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 649 { 650 int ret; 651 struct binderfs_info *info; 652 struct binderfs_mount_opts *ctx = fc->fs_private; 653 struct inode *inode = NULL; 654 struct binderfs_device device_info = {}; 655 const char *name; 656 size_t len; 657 658 sb->s_blocksize = PAGE_SIZE; 659 sb->s_blocksize_bits = PAGE_SHIFT; 660 661 /* 662 * The binderfs filesystem can be mounted by userns root in a 663 * non-initial userns. By default such mounts have the SB_I_NODEV flag 664 * set in s_iflags to prevent security issues where userns root can 665 * just create random device nodes via mknod() since it owns the 666 * filesystem mount. But binderfs does not allow to create any files 667 * including devices nodes. The only way to create binder devices nodes 668 * is through the binder-control device which userns root is explicitly 669 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 670 * necessary and safe. 671 */ 672 sb->s_iflags &= ~SB_I_NODEV; 673 sb->s_iflags |= SB_I_NOEXEC; 674 sb->s_magic = BINDERFS_SUPER_MAGIC; 675 sb->s_op = &binderfs_super_ops; 676 sb->s_time_gran = 1; 677 678 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 679 if (!sb->s_fs_info) 680 return -ENOMEM; 681 info = sb->s_fs_info; 682 683 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 684 685 info->root_gid = make_kgid(sb->s_user_ns, 0); 686 if (!gid_valid(info->root_gid)) 687 info->root_gid = GLOBAL_ROOT_GID; 688 info->root_uid = make_kuid(sb->s_user_ns, 0); 689 if (!uid_valid(info->root_uid)) 690 info->root_uid = GLOBAL_ROOT_UID; 691 info->mount_opts.max = ctx->max; 692 info->mount_opts.stats_mode = ctx->stats_mode; 693 694 inode = new_inode(sb); 695 if (!inode) 696 return -ENOMEM; 697 698 inode->i_ino = FIRST_INODE; 699 inode->i_fop = &simple_dir_operations; 700 inode->i_mode = S_IFDIR | 0755; 701 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 702 inode->i_op = &binderfs_dir_inode_operations; 703 set_nlink(inode, 2); 704 705 sb->s_root = d_make_root(inode); 706 if (!sb->s_root) 707 return -ENOMEM; 708 709 ret = binderfs_binder_ctl_create(sb); 710 if (ret) 711 return ret; 712 713 name = binder_devices_param; 714 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 715 strscpy(device_info.name, name, len + 1); 716 ret = binderfs_binder_device_create(inode, NULL, &device_info); 717 if (ret) 718 return ret; 719 name += len; 720 if (*name == ',') 721 name++; 722 } 723 724 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 725 return init_binder_logs(sb); 726 727 return 0; 728 } 729 730 static int binderfs_fs_context_get_tree(struct fs_context *fc) 731 { 732 return get_tree_nodev(fc, binderfs_fill_super); 733 } 734 735 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 }; 748 749 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 } 765 766 static struct file_system_type binder_fs_type = { 767 .name = "binder", 768 .init_fs_context = binderfs_init_fs_context, 769 .parameters = binderfs_fs_parameters, 770 .kill_sb = kill_litter_super, 771 .fs_flags = FS_USERNS_MOUNT, 772 }; 773 774 int __init init_binderfs(void) 775 { 776 int ret; 777 const char *name; 778 size_t len; 779 780 /* Verify that the default binderfs device names are valid. */ 781 name = binder_devices_param; 782 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 783 if (len > BINDERFS_MAX_NAME) 784 return -E2BIG; 785 name += len; 786 if (*name == ',') 787 name++; 788 } 789 790 /* Allocate new major number for binderfs. */ 791 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 792 "binder"); 793 if (ret) 794 return ret; 795 796 ret = register_filesystem(&binder_fs_type); 797 if (ret) { 798 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 799 return ret; 800 } 801 802 return ret; 803 } 804