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 bool transaction_report; 63 }; 64 65 static const struct constant_table binderfs_param_stats[] = { 66 { "global", binderfs_stats_mode_global }, 67 {} 68 }; 69 70 static const struct fs_parameter_spec binderfs_fs_parameters[] = { 71 fsparam_u32("max", Opt_max), 72 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats), 73 {} 74 }; 75 76 static struct binder_features binder_features = { 77 .oneway_spam_detection = true, 78 .extended_error = true, 79 .freeze_notification = true, 80 .transaction_report = true, 81 }; 82 83 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb) 84 { 85 return sb->s_fs_info; 86 } 87 88 bool is_binderfs_device(const struct inode *inode) 89 { 90 if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC) 91 return true; 92 93 return false; 94 } 95 96 /** 97 * binderfs_binder_device_create - allocate inode from super block of a 98 * binderfs mount 99 * @ref_inode: inode from which the super block will be taken 100 * @userp: buffer to copy information about new device for userspace to 101 * @req: struct binderfs_device as copied from userspace 102 * 103 * This function allocates a new binder_device and reserves a new minor 104 * number for it. 105 * Minor numbers are limited and tracked globally in binderfs_minors. The 106 * function will stash a struct binder_device for the specific binder 107 * device in i_private of the inode. 108 * It will go on to allocate a new inode from the super block of the 109 * filesystem mount, stash a struct binder_device in its i_private field 110 * and attach a dentry to that inode. 111 * 112 * Return: 0 on success, negative errno on failure 113 */ 114 static int binderfs_binder_device_create(struct inode *ref_inode, 115 struct binderfs_device __user *userp, 116 struct binderfs_device *req) 117 { 118 int minor, ret; 119 struct dentry *dentry, *root; 120 struct binder_device *device; 121 char *name = NULL; 122 struct inode *inode = NULL; 123 struct super_block *sb = ref_inode->i_sb; 124 struct binderfs_info *info = sb->s_fs_info; 125 #if defined(CONFIG_IPC_NS) 126 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 127 #else 128 bool use_reserve = true; 129 #endif 130 131 /* Reserve new minor number for the new device. */ 132 mutex_lock(&binderfs_minors_mutex); 133 if (++info->device_count <= info->mount_opts.max) 134 minor = ida_alloc_max(&binderfs_minors, 135 use_reserve ? BINDERFS_MAX_MINOR : 136 BINDERFS_MAX_MINOR_CAPPED, 137 GFP_KERNEL); 138 else 139 minor = -ENOSPC; 140 if (minor < 0) { 141 --info->device_count; 142 mutex_unlock(&binderfs_minors_mutex); 143 return minor; 144 } 145 mutex_unlock(&binderfs_minors_mutex); 146 147 ret = -ENOMEM; 148 device = kzalloc(sizeof(*device), GFP_KERNEL); 149 if (!device) 150 goto err; 151 152 inode = new_inode(sb); 153 if (!inode) 154 goto err; 155 156 inode->i_ino = minor + INODE_OFFSET; 157 simple_inode_init_ts(inode); 158 init_special_inode(inode, S_IFCHR | 0600, 159 MKDEV(MAJOR(binderfs_dev), minor)); 160 inode->i_fop = &binder_fops; 161 inode->i_uid = info->root_uid; 162 inode->i_gid = info->root_gid; 163 164 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */ 165 name = kstrdup(req->name, 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_noperm(&QSTR(name), root); 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 binder_add_device(device); 210 211 return 0; 212 213 err: 214 kfree(name); 215 kfree(device); 216 mutex_lock(&binderfs_minors_mutex); 217 --info->device_count; 218 ida_free(&binderfs_minors, minor); 219 mutex_unlock(&binderfs_minors_mutex); 220 iput(inode); 221 222 return ret; 223 } 224 225 /** 226 * binder_ctl_ioctl - handle binder device node allocation requests 227 * @file: The file pointer for the binder-control device node. 228 * @cmd: The ioctl command. 229 * @arg: The ioctl argument. 230 * 231 * The request handler for the binder-control device. All requests operate on 232 * the binderfs mount the binder-control device resides in: 233 * - BINDER_CTL_ADD 234 * Allocate a new binder device. 235 * 236 * Return: %0 on success, negative errno on failure. 237 */ 238 static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 239 unsigned long arg) 240 { 241 int ret = -EINVAL; 242 struct inode *inode = file_inode(file); 243 struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 244 struct binderfs_device device_req; 245 246 switch (cmd) { 247 case BINDER_CTL_ADD: 248 ret = copy_from_user(&device_req, device, sizeof(device_req)); 249 if (ret) { 250 ret = -EFAULT; 251 break; 252 } 253 254 ret = binderfs_binder_device_create(inode, device, &device_req); 255 break; 256 default: 257 break; 258 } 259 260 return ret; 261 } 262 263 static void binderfs_evict_inode(struct inode *inode) 264 { 265 struct binder_device *device = inode->i_private; 266 struct binderfs_info *info = BINDERFS_SB(inode->i_sb); 267 268 clear_inode(inode); 269 270 if (!S_ISCHR(inode->i_mode) || !device) 271 return; 272 273 mutex_lock(&binderfs_minors_mutex); 274 --info->device_count; 275 ida_free(&binderfs_minors, device->miscdev.minor); 276 mutex_unlock(&binderfs_minors_mutex); 277 278 if (refcount_dec_and_test(&device->ref)) { 279 binder_remove_device(device); 280 kfree(device->context.name); 281 kfree(device); 282 } 283 } 284 285 static int binderfs_fs_context_parse_param(struct fs_context *fc, 286 struct fs_parameter *param) 287 { 288 int opt; 289 struct binderfs_mount_opts *ctx = fc->fs_private; 290 struct fs_parse_result result; 291 292 opt = fs_parse(fc, binderfs_fs_parameters, param, &result); 293 if (opt < 0) 294 return opt; 295 296 switch (opt) { 297 case Opt_max: 298 if (result.uint_32 > BINDERFS_MAX_MINOR) 299 return invalfc(fc, "Bad value for '%s'", param->key); 300 301 ctx->max = result.uint_32; 302 break; 303 case Opt_stats_mode: 304 if (!capable(CAP_SYS_ADMIN)) 305 return -EPERM; 306 307 ctx->stats_mode = result.uint_32; 308 break; 309 default: 310 return invalfc(fc, "Unsupported parameter '%s'", param->key); 311 } 312 313 return 0; 314 } 315 316 static int binderfs_fs_context_reconfigure(struct fs_context *fc) 317 { 318 struct binderfs_mount_opts *ctx = fc->fs_private; 319 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb); 320 321 if (info->mount_opts.stats_mode != ctx->stats_mode) 322 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount"); 323 324 info->mount_opts.stats_mode = ctx->stats_mode; 325 info->mount_opts.max = ctx->max; 326 return 0; 327 } 328 329 static int binderfs_show_options(struct seq_file *seq, struct dentry *root) 330 { 331 struct binderfs_info *info = BINDERFS_SB(root->d_sb); 332 333 if (info->mount_opts.max <= BINDERFS_MAX_MINOR) 334 seq_printf(seq, ",max=%d", info->mount_opts.max); 335 336 switch (info->mount_opts.stats_mode) { 337 case binderfs_stats_mode_unset: 338 break; 339 case binderfs_stats_mode_global: 340 seq_printf(seq, ",stats=global"); 341 break; 342 } 343 344 return 0; 345 } 346 347 static const struct super_operations binderfs_super_ops = { 348 .evict_inode = binderfs_evict_inode, 349 .show_options = binderfs_show_options, 350 .statfs = simple_statfs, 351 }; 352 353 static inline bool is_binderfs_control_device(const struct dentry *dentry) 354 { 355 struct binderfs_info *info = dentry->d_sb->s_fs_info; 356 357 return info->control_dentry == dentry; 358 } 359 360 static int binderfs_rename(struct mnt_idmap *idmap, 361 struct inode *old_dir, struct dentry *old_dentry, 362 struct inode *new_dir, struct dentry *new_dentry, 363 unsigned int flags) 364 { 365 if (is_binderfs_control_device(old_dentry) || 366 is_binderfs_control_device(new_dentry)) 367 return -EPERM; 368 369 return simple_rename(idmap, old_dir, old_dentry, new_dir, 370 new_dentry, flags); 371 } 372 373 static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 374 { 375 if (is_binderfs_control_device(dentry)) 376 return -EPERM; 377 378 return simple_unlink(dir, dentry); 379 } 380 381 static const struct file_operations binder_ctl_fops = { 382 .owner = THIS_MODULE, 383 .open = nonseekable_open, 384 .unlocked_ioctl = binder_ctl_ioctl, 385 .compat_ioctl = binder_ctl_ioctl, 386 .llseek = noop_llseek, 387 }; 388 389 /** 390 * binderfs_binder_ctl_create - create a new binder-control device 391 * @sb: super block of the binderfs mount 392 * 393 * This function creates a new binder-control device node in the binderfs mount 394 * referred to by @sb. 395 * 396 * Return: 0 on success, negative errno on failure 397 */ 398 static int binderfs_binder_ctl_create(struct super_block *sb) 399 { 400 int minor, ret; 401 struct dentry *dentry; 402 struct binder_device *device; 403 struct inode *inode = NULL; 404 struct dentry *root = sb->s_root; 405 struct binderfs_info *info = sb->s_fs_info; 406 #if defined(CONFIG_IPC_NS) 407 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 408 #else 409 bool use_reserve = true; 410 #endif 411 412 device = kzalloc(sizeof(*device), GFP_KERNEL); 413 if (!device) 414 return -ENOMEM; 415 416 /* If we have already created a binder-control node, return. */ 417 if (info->control_dentry) { 418 ret = 0; 419 goto out; 420 } 421 422 ret = -ENOMEM; 423 inode = new_inode(sb); 424 if (!inode) 425 goto out; 426 427 /* Reserve a new minor number for the new device. */ 428 mutex_lock(&binderfs_minors_mutex); 429 minor = ida_alloc_max(&binderfs_minors, 430 use_reserve ? BINDERFS_MAX_MINOR : 431 BINDERFS_MAX_MINOR_CAPPED, 432 GFP_KERNEL); 433 mutex_unlock(&binderfs_minors_mutex); 434 if (minor < 0) { 435 ret = minor; 436 goto out; 437 } 438 439 inode->i_ino = SECOND_INODE; 440 simple_inode_init_ts(inode); 441 init_special_inode(inode, S_IFCHR | 0600, 442 MKDEV(MAJOR(binderfs_dev), minor)); 443 inode->i_fop = &binder_ctl_fops; 444 inode->i_uid = info->root_uid; 445 inode->i_gid = info->root_gid; 446 447 refcount_set(&device->ref, 1); 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 simple_inode_init_ts(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_noperm(&QSTR(name), parent); 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 struct dentry *binderfs_create_file(struct dentry *parent, const char *name, 506 const struct file_operations *fops, 507 void *data) 508 { 509 struct dentry *dentry; 510 struct inode *new_inode, *parent_inode; 511 struct super_block *sb; 512 513 parent_inode = d_inode(parent); 514 inode_lock(parent_inode); 515 516 dentry = binderfs_create_dentry(parent, name); 517 if (IS_ERR(dentry)) 518 goto out; 519 520 sb = parent_inode->i_sb; 521 new_inode = binderfs_make_inode(sb, S_IFREG | 0444); 522 if (!new_inode) { 523 dput(dentry); 524 dentry = ERR_PTR(-ENOMEM); 525 goto out; 526 } 527 528 new_inode->i_fop = fops; 529 new_inode->i_private = data; 530 d_instantiate(dentry, new_inode); 531 fsnotify_create(parent_inode, dentry); 532 533 out: 534 inode_unlock(parent_inode); 535 return dentry; 536 } 537 538 static struct dentry *binderfs_create_dir(struct dentry *parent, 539 const char *name) 540 { 541 struct dentry *dentry; 542 struct inode *new_inode, *parent_inode; 543 struct super_block *sb; 544 545 parent_inode = d_inode(parent); 546 inode_lock(parent_inode); 547 548 dentry = binderfs_create_dentry(parent, name); 549 if (IS_ERR(dentry)) 550 goto out; 551 552 sb = parent_inode->i_sb; 553 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755); 554 if (!new_inode) { 555 dput(dentry); 556 dentry = ERR_PTR(-ENOMEM); 557 goto out; 558 } 559 560 new_inode->i_fop = &simple_dir_operations; 561 new_inode->i_op = &simple_dir_inode_operations; 562 563 set_nlink(new_inode, 2); 564 d_instantiate(dentry, new_inode); 565 inc_nlink(parent_inode); 566 fsnotify_mkdir(parent_inode, dentry); 567 568 out: 569 inode_unlock(parent_inode); 570 return dentry; 571 } 572 573 static int binder_features_show(struct seq_file *m, void *unused) 574 { 575 bool *feature = m->private; 576 577 seq_printf(m, "%d\n", *feature); 578 579 return 0; 580 } 581 DEFINE_SHOW_ATTRIBUTE(binder_features); 582 583 static int init_binder_features(struct super_block *sb) 584 { 585 struct dentry *dentry, *dir; 586 587 dir = binderfs_create_dir(sb->s_root, "features"); 588 if (IS_ERR(dir)) 589 return PTR_ERR(dir); 590 591 dentry = binderfs_create_file(dir, "oneway_spam_detection", 592 &binder_features_fops, 593 &binder_features.oneway_spam_detection); 594 if (IS_ERR(dentry)) 595 return PTR_ERR(dentry); 596 597 dentry = binderfs_create_file(dir, "extended_error", 598 &binder_features_fops, 599 &binder_features.extended_error); 600 if (IS_ERR(dentry)) 601 return PTR_ERR(dentry); 602 603 dentry = binderfs_create_file(dir, "freeze_notification", 604 &binder_features_fops, 605 &binder_features.freeze_notification); 606 if (IS_ERR(dentry)) 607 return PTR_ERR(dentry); 608 609 dentry = binderfs_create_file(dir, "transaction_report", 610 &binder_features_fops, 611 &binder_features.transaction_report); 612 if (IS_ERR(dentry)) 613 return PTR_ERR(dentry); 614 615 return 0; 616 } 617 618 static int init_binder_logs(struct super_block *sb) 619 { 620 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 621 const struct binder_debugfs_entry *db_entry; 622 struct binderfs_info *info; 623 int ret = 0; 624 625 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 626 "binder_logs"); 627 if (IS_ERR(binder_logs_root_dir)) { 628 ret = PTR_ERR(binder_logs_root_dir); 629 goto out; 630 } 631 632 binder_for_each_debugfs_entry(db_entry) { 633 dentry = binderfs_create_file(binder_logs_root_dir, 634 db_entry->name, 635 db_entry->fops, 636 db_entry->data); 637 if (IS_ERR(dentry)) { 638 ret = PTR_ERR(dentry); 639 goto out; 640 } 641 } 642 643 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 644 if (IS_ERR(proc_log_dir)) { 645 ret = PTR_ERR(proc_log_dir); 646 goto out; 647 } 648 info = sb->s_fs_info; 649 info->proc_log_dir = proc_log_dir; 650 651 out: 652 return ret; 653 } 654 655 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 656 { 657 int ret; 658 struct binderfs_info *info; 659 struct binderfs_mount_opts *ctx = fc->fs_private; 660 struct inode *inode = NULL; 661 struct binderfs_device device_info = {}; 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 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 info->mount_opts.max = ctx->max; 699 info->mount_opts.stats_mode = ctx->stats_mode; 700 701 inode = new_inode(sb); 702 if (!inode) 703 return -ENOMEM; 704 705 inode->i_ino = FIRST_INODE; 706 inode->i_fop = &simple_dir_operations; 707 inode->i_mode = S_IFDIR | 0755; 708 simple_inode_init_ts(inode); 709 inode->i_op = &binderfs_dir_inode_operations; 710 set_nlink(inode, 2); 711 712 sb->s_root = d_make_root(inode); 713 if (!sb->s_root) 714 return -ENOMEM; 715 716 ret = binderfs_binder_ctl_create(sb); 717 if (ret) 718 return ret; 719 720 name = binder_devices_param; 721 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 722 strscpy(device_info.name, name, len + 1); 723 ret = binderfs_binder_device_create(inode, NULL, &device_info); 724 if (ret) 725 return ret; 726 name += len; 727 if (*name == ',') 728 name++; 729 } 730 731 ret = init_binder_features(sb); 732 if (ret) 733 return ret; 734 735 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 736 return init_binder_logs(sb); 737 738 return 0; 739 } 740 741 static int binderfs_fs_context_get_tree(struct fs_context *fc) 742 { 743 return get_tree_nodev(fc, binderfs_fill_super); 744 } 745 746 static void binderfs_fs_context_free(struct fs_context *fc) 747 { 748 struct binderfs_mount_opts *ctx = fc->fs_private; 749 750 kfree(ctx); 751 } 752 753 static const struct fs_context_operations binderfs_fs_context_ops = { 754 .free = binderfs_fs_context_free, 755 .get_tree = binderfs_fs_context_get_tree, 756 .parse_param = binderfs_fs_context_parse_param, 757 .reconfigure = binderfs_fs_context_reconfigure, 758 }; 759 760 static int binderfs_init_fs_context(struct fs_context *fc) 761 { 762 struct binderfs_mount_opts *ctx; 763 764 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL); 765 if (!ctx) 766 return -ENOMEM; 767 768 ctx->max = BINDERFS_MAX_MINOR; 769 ctx->stats_mode = binderfs_stats_mode_unset; 770 771 fc->fs_private = ctx; 772 fc->ops = &binderfs_fs_context_ops; 773 774 return 0; 775 } 776 777 static void binderfs_kill_super(struct super_block *sb) 778 { 779 struct binderfs_info *info = sb->s_fs_info; 780 781 /* 782 * During inode eviction struct binderfs_info is needed. 783 * So first wipe the super_block then free struct binderfs_info. 784 */ 785 kill_litter_super(sb); 786 787 if (info && info->ipc_ns) 788 put_ipc_ns(info->ipc_ns); 789 790 kfree(info); 791 } 792 793 static struct file_system_type binder_fs_type = { 794 .name = "binder", 795 .init_fs_context = binderfs_init_fs_context, 796 .parameters = binderfs_fs_parameters, 797 .kill_sb = binderfs_kill_super, 798 .fs_flags = FS_USERNS_MOUNT, 799 }; 800 801 int __init init_binderfs(void) 802 { 803 int ret; 804 const char *name; 805 size_t len; 806 807 /* Verify that the default binderfs device names are valid. */ 808 name = binder_devices_param; 809 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 810 if (len > BINDERFS_MAX_NAME) 811 return -E2BIG; 812 name += len; 813 if (*name == ',') 814 name++; 815 } 816 817 /* Allocate new major number for binderfs. */ 818 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 819 "binder"); 820 if (ret) 821 return ret; 822 823 ret = register_filesystem(&binder_fs_type); 824 if (ret) { 825 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 826 return ret; 827 } 828 829 return ret; 830 } 831