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