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 BINDERFS_MAX_MINOR (1U << MINORBITS) 43 /* Ensure that the initial ipc namespace always has devices available. */ 44 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4) 45 46 static dev_t binderfs_dev; 47 static DEFINE_MUTEX(binderfs_minors_mutex); 48 static DEFINE_IDA(binderfs_minors); 49 50 enum binderfs_param { 51 Opt_max, 52 Opt_stats_mode, 53 }; 54 55 enum binderfs_stats_mode { 56 binderfs_stats_mode_unset, 57 binderfs_stats_mode_global, 58 }; 59 60 struct binder_features { 61 bool oneway_spam_detection; 62 bool extended_error; 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 }; 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 wich 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 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(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_one_len(name, root, name_len); 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 return 0; 211 212 err: 213 kfree(name); 214 kfree(device); 215 mutex_lock(&binderfs_minors_mutex); 216 --info->device_count; 217 ida_free(&binderfs_minors, minor); 218 mutex_unlock(&binderfs_minors_mutex); 219 iput(inode); 220 221 return ret; 222 } 223 224 /** 225 * binderfs_ctl_ioctl - handle binder device node allocation requests 226 * 227 * The request handler for the binder-control device. All requests operate on 228 * the binderfs mount the binder-control device resides in: 229 * - BINDER_CTL_ADD 230 * Allocate a new binder device. 231 * 232 * Return: 0 on success, negative errno on failure 233 */ 234 static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 235 unsigned long arg) 236 { 237 int ret = -EINVAL; 238 struct inode *inode = file_inode(file); 239 struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 240 struct binderfs_device device_req; 241 242 switch (cmd) { 243 case BINDER_CTL_ADD: 244 ret = copy_from_user(&device_req, device, sizeof(device_req)); 245 if (ret) { 246 ret = -EFAULT; 247 break; 248 } 249 250 ret = binderfs_binder_device_create(inode, device, &device_req); 251 break; 252 default: 253 break; 254 } 255 256 return ret; 257 } 258 259 static void binderfs_evict_inode(struct inode *inode) 260 { 261 struct binder_device *device = inode->i_private; 262 struct binderfs_info *info = BINDERFS_SB(inode->i_sb); 263 264 clear_inode(inode); 265 266 if (!S_ISCHR(inode->i_mode) || !device) 267 return; 268 269 mutex_lock(&binderfs_minors_mutex); 270 --info->device_count; 271 ida_free(&binderfs_minors, device->miscdev.minor); 272 mutex_unlock(&binderfs_minors_mutex); 273 274 if (refcount_dec_and_test(&device->ref)) { 275 kfree(device->context.name); 276 kfree(device); 277 } 278 } 279 280 static int binderfs_fs_context_parse_param(struct fs_context *fc, 281 struct fs_parameter *param) 282 { 283 int opt; 284 struct binderfs_mount_opts *ctx = fc->fs_private; 285 struct fs_parse_result result; 286 287 opt = fs_parse(fc, binderfs_fs_parameters, param, &result); 288 if (opt < 0) 289 return opt; 290 291 switch (opt) { 292 case Opt_max: 293 if (result.uint_32 > BINDERFS_MAX_MINOR) 294 return invalfc(fc, "Bad value for '%s'", param->key); 295 296 ctx->max = result.uint_32; 297 break; 298 case Opt_stats_mode: 299 if (!capable(CAP_SYS_ADMIN)) 300 return -EPERM; 301 302 ctx->stats_mode = result.uint_32; 303 break; 304 default: 305 return invalfc(fc, "Unsupported parameter '%s'", param->key); 306 } 307 308 return 0; 309 } 310 311 static int binderfs_fs_context_reconfigure(struct fs_context *fc) 312 { 313 struct binderfs_mount_opts *ctx = fc->fs_private; 314 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb); 315 316 if (info->mount_opts.stats_mode != ctx->stats_mode) 317 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount"); 318 319 info->mount_opts.stats_mode = ctx->stats_mode; 320 info->mount_opts.max = ctx->max; 321 return 0; 322 } 323 324 static int binderfs_show_options(struct seq_file *seq, struct dentry *root) 325 { 326 struct binderfs_info *info = BINDERFS_SB(root->d_sb); 327 328 if (info->mount_opts.max <= BINDERFS_MAX_MINOR) 329 seq_printf(seq, ",max=%d", info->mount_opts.max); 330 331 switch (info->mount_opts.stats_mode) { 332 case binderfs_stats_mode_unset: 333 break; 334 case binderfs_stats_mode_global: 335 seq_printf(seq, ",stats=global"); 336 break; 337 } 338 339 return 0; 340 } 341 342 static void binderfs_put_super(struct super_block *sb) 343 { 344 struct binderfs_info *info = sb->s_fs_info; 345 346 if (info && info->ipc_ns) 347 put_ipc_ns(info->ipc_ns); 348 349 kfree(info); 350 sb->s_fs_info = NULL; 351 } 352 353 static const struct super_operations binderfs_super_ops = { 354 .evict_inode = binderfs_evict_inode, 355 .show_options = binderfs_show_options, 356 .statfs = simple_statfs, 357 .put_super = binderfs_put_super, 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; 363 364 return info->control_dentry == dentry; 365 } 366 367 static int binderfs_rename(struct user_namespace *mnt_userns, 368 struct inode *old_dir, struct dentry *old_dentry, 369 struct inode *new_dir, struct dentry *new_dentry, 370 unsigned int flags) 371 { 372 if (is_binderfs_control_device(old_dentry) || 373 is_binderfs_control_device(new_dentry)) 374 return -EPERM; 375 376 return simple_rename(&init_user_ns, old_dir, old_dentry, new_dir, 377 new_dentry, flags); 378 } 379 380 static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 381 { 382 if (is_binderfs_control_device(dentry)) 383 return -EPERM; 384 385 return simple_unlink(dir, dentry); 386 } 387 388 static const struct file_operations binder_ctl_fops = { 389 .owner = THIS_MODULE, 390 .open = nonseekable_open, 391 .unlocked_ioctl = binder_ctl_ioctl, 392 .compat_ioctl = binder_ctl_ioctl, 393 .llseek = noop_llseek, 394 }; 395 396 /** 397 * binderfs_binder_ctl_create - create a new binder-control device 398 * @sb: super block of the binderfs mount 399 * 400 * This function creates a new binder-control device node in the binderfs mount 401 * referred to by @sb. 402 * 403 * Return: 0 on success, negative errno on failure 404 */ 405 static int binderfs_binder_ctl_create(struct super_block *sb) 406 { 407 int minor, ret; 408 struct dentry *dentry; 409 struct binder_device *device; 410 struct inode *inode = NULL; 411 struct dentry *root = sb->s_root; 412 struct binderfs_info *info = sb->s_fs_info; 413 #if defined(CONFIG_IPC_NS) 414 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 415 #else 416 bool use_reserve = true; 417 #endif 418 419 device = kzalloc(sizeof(*device), GFP_KERNEL); 420 if (!device) 421 return -ENOMEM; 422 423 /* If we have already created a binder-control node, return. */ 424 if (info->control_dentry) { 425 ret = 0; 426 goto out; 427 } 428 429 ret = -ENOMEM; 430 inode = new_inode(sb); 431 if (!inode) 432 goto out; 433 434 /* Reserve a new minor number for the new device. */ 435 mutex_lock(&binderfs_minors_mutex); 436 minor = ida_alloc_max(&binderfs_minors, 437 use_reserve ? BINDERFS_MAX_MINOR : 438 BINDERFS_MAX_MINOR_CAPPED, 439 GFP_KERNEL); 440 mutex_unlock(&binderfs_minors_mutex); 441 if (minor < 0) { 442 ret = minor; 443 goto out; 444 } 445 446 inode->i_ino = SECOND_INODE; 447 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 448 init_special_inode(inode, S_IFCHR | 0600, 449 MKDEV(MAJOR(binderfs_dev), minor)); 450 inode->i_fop = &binder_ctl_fops; 451 inode->i_uid = info->root_uid; 452 inode->i_gid = info->root_gid; 453 454 refcount_set(&device->ref, 1); 455 device->binderfs_inode = inode; 456 device->miscdev.minor = minor; 457 458 dentry = d_alloc_name(root, "binder-control"); 459 if (!dentry) 460 goto out; 461 462 inode->i_private = device; 463 info->control_dentry = dentry; 464 d_add(dentry, inode); 465 466 return 0; 467 468 out: 469 kfree(device); 470 iput(inode); 471 472 return ret; 473 } 474 475 static const struct inode_operations binderfs_dir_inode_operations = { 476 .lookup = simple_lookup, 477 .rename = binderfs_rename, 478 .unlink = binderfs_unlink, 479 }; 480 481 static struct inode *binderfs_make_inode(struct super_block *sb, int mode) 482 { 483 struct inode *ret; 484 485 ret = new_inode(sb); 486 if (ret) { 487 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET); 488 ret->i_mode = mode; 489 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret); 490 } 491 return ret; 492 } 493 494 static struct dentry *binderfs_create_dentry(struct dentry *parent, 495 const char *name) 496 { 497 struct dentry *dentry; 498 499 dentry = lookup_one_len(name, parent, strlen(name)); 500 if (IS_ERR(dentry)) 501 return dentry; 502 503 /* Return error if the file/dir already exists. */ 504 if (d_really_is_positive(dentry)) { 505 dput(dentry); 506 return ERR_PTR(-EEXIST); 507 } 508 509 return dentry; 510 } 511 512 void binderfs_remove_file(struct dentry *dentry) 513 { 514 struct inode *parent_inode; 515 516 parent_inode = d_inode(dentry->d_parent); 517 inode_lock(parent_inode); 518 if (simple_positive(dentry)) { 519 dget(dentry); 520 simple_unlink(parent_inode, dentry); 521 d_delete(dentry); 522 dput(dentry); 523 } 524 inode_unlock(parent_inode); 525 } 526 527 struct dentry *binderfs_create_file(struct dentry *parent, const char *name, 528 const struct file_operations *fops, 529 void *data) 530 { 531 struct dentry *dentry; 532 struct inode *new_inode, *parent_inode; 533 struct super_block *sb; 534 535 parent_inode = d_inode(parent); 536 inode_lock(parent_inode); 537 538 dentry = binderfs_create_dentry(parent, name); 539 if (IS_ERR(dentry)) 540 goto out; 541 542 sb = parent_inode->i_sb; 543 new_inode = binderfs_make_inode(sb, S_IFREG | 0444); 544 if (!new_inode) { 545 dput(dentry); 546 dentry = ERR_PTR(-ENOMEM); 547 goto out; 548 } 549 550 new_inode->i_fop = fops; 551 new_inode->i_private = data; 552 d_instantiate(dentry, new_inode); 553 fsnotify_create(parent_inode, dentry); 554 555 out: 556 inode_unlock(parent_inode); 557 return dentry; 558 } 559 560 static struct dentry *binderfs_create_dir(struct dentry *parent, 561 const char *name) 562 { 563 struct dentry *dentry; 564 struct inode *new_inode, *parent_inode; 565 struct super_block *sb; 566 567 parent_inode = d_inode(parent); 568 inode_lock(parent_inode); 569 570 dentry = binderfs_create_dentry(parent, name); 571 if (IS_ERR(dentry)) 572 goto out; 573 574 sb = parent_inode->i_sb; 575 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755); 576 if (!new_inode) { 577 dput(dentry); 578 dentry = ERR_PTR(-ENOMEM); 579 goto out; 580 } 581 582 new_inode->i_fop = &simple_dir_operations; 583 new_inode->i_op = &simple_dir_inode_operations; 584 585 set_nlink(new_inode, 2); 586 d_instantiate(dentry, new_inode); 587 inc_nlink(parent_inode); 588 fsnotify_mkdir(parent_inode, dentry); 589 590 out: 591 inode_unlock(parent_inode); 592 return dentry; 593 } 594 595 static int binder_features_show(struct seq_file *m, void *unused) 596 { 597 bool *feature = m->private; 598 599 seq_printf(m, "%d\n", *feature); 600 601 return 0; 602 } 603 DEFINE_SHOW_ATTRIBUTE(binder_features); 604 605 static int init_binder_features(struct super_block *sb) 606 { 607 struct dentry *dentry, *dir; 608 609 dir = binderfs_create_dir(sb->s_root, "features"); 610 if (IS_ERR(dir)) 611 return PTR_ERR(dir); 612 613 dentry = binderfs_create_file(dir, "oneway_spam_detection", 614 &binder_features_fops, 615 &binder_features.oneway_spam_detection); 616 if (IS_ERR(dentry)) 617 return PTR_ERR(dentry); 618 619 dentry = binderfs_create_file(dir, "extended_error", 620 &binder_features_fops, 621 &binder_features.extended_error); 622 if (IS_ERR(dentry)) 623 return PTR_ERR(dentry); 624 625 return 0; 626 } 627 628 static int init_binder_logs(struct super_block *sb) 629 { 630 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 631 const struct binder_debugfs_entry *db_entry; 632 struct binderfs_info *info; 633 int ret = 0; 634 635 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 636 "binder_logs"); 637 if (IS_ERR(binder_logs_root_dir)) { 638 ret = PTR_ERR(binder_logs_root_dir); 639 goto out; 640 } 641 642 binder_for_each_debugfs_entry(db_entry) { 643 dentry = binderfs_create_file(binder_logs_root_dir, 644 db_entry->name, 645 db_entry->fops, 646 db_entry->data); 647 if (IS_ERR(dentry)) { 648 ret = PTR_ERR(dentry); 649 goto out; 650 } 651 } 652 653 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 654 if (IS_ERR(proc_log_dir)) { 655 ret = PTR_ERR(proc_log_dir); 656 goto out; 657 } 658 info = sb->s_fs_info; 659 info->proc_log_dir = proc_log_dir; 660 661 out: 662 return ret; 663 } 664 665 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 666 { 667 int ret; 668 struct binderfs_info *info; 669 struct binderfs_mount_opts *ctx = fc->fs_private; 670 struct inode *inode = NULL; 671 struct binderfs_device device_info = {}; 672 const char *name; 673 size_t len; 674 675 sb->s_blocksize = PAGE_SIZE; 676 sb->s_blocksize_bits = PAGE_SHIFT; 677 678 /* 679 * The binderfs filesystem can be mounted by userns root in a 680 * non-initial userns. By default such mounts have the SB_I_NODEV flag 681 * set in s_iflags to prevent security issues where userns root can 682 * just create random device nodes via mknod() since it owns the 683 * filesystem mount. But binderfs does not allow to create any files 684 * including devices nodes. The only way to create binder devices nodes 685 * is through the binder-control device which userns root is explicitly 686 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 687 * necessary and safe. 688 */ 689 sb->s_iflags &= ~SB_I_NODEV; 690 sb->s_iflags |= SB_I_NOEXEC; 691 sb->s_magic = BINDERFS_SUPER_MAGIC; 692 sb->s_op = &binderfs_super_ops; 693 sb->s_time_gran = 1; 694 695 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 696 if (!sb->s_fs_info) 697 return -ENOMEM; 698 info = sb->s_fs_info; 699 700 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 701 702 info->root_gid = make_kgid(sb->s_user_ns, 0); 703 if (!gid_valid(info->root_gid)) 704 info->root_gid = GLOBAL_ROOT_GID; 705 info->root_uid = make_kuid(sb->s_user_ns, 0); 706 if (!uid_valid(info->root_uid)) 707 info->root_uid = GLOBAL_ROOT_UID; 708 info->mount_opts.max = ctx->max; 709 info->mount_opts.stats_mode = ctx->stats_mode; 710 711 inode = new_inode(sb); 712 if (!inode) 713 return -ENOMEM; 714 715 inode->i_ino = FIRST_INODE; 716 inode->i_fop = &simple_dir_operations; 717 inode->i_mode = S_IFDIR | 0755; 718 inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode); 719 inode->i_op = &binderfs_dir_inode_operations; 720 set_nlink(inode, 2); 721 722 sb->s_root = d_make_root(inode); 723 if (!sb->s_root) 724 return -ENOMEM; 725 726 ret = binderfs_binder_ctl_create(sb); 727 if (ret) 728 return ret; 729 730 name = binder_devices_param; 731 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 732 strscpy(device_info.name, name, len + 1); 733 ret = binderfs_binder_device_create(inode, NULL, &device_info); 734 if (ret) 735 return ret; 736 name += len; 737 if (*name == ',') 738 name++; 739 } 740 741 ret = init_binder_features(sb); 742 if (ret) 743 return ret; 744 745 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 746 return init_binder_logs(sb); 747 748 return 0; 749 } 750 751 static int binderfs_fs_context_get_tree(struct fs_context *fc) 752 { 753 return get_tree_nodev(fc, binderfs_fill_super); 754 } 755 756 static void binderfs_fs_context_free(struct fs_context *fc) 757 { 758 struct binderfs_mount_opts *ctx = fc->fs_private; 759 760 kfree(ctx); 761 } 762 763 static const struct fs_context_operations binderfs_fs_context_ops = { 764 .free = binderfs_fs_context_free, 765 .get_tree = binderfs_fs_context_get_tree, 766 .parse_param = binderfs_fs_context_parse_param, 767 .reconfigure = binderfs_fs_context_reconfigure, 768 }; 769 770 static int binderfs_init_fs_context(struct fs_context *fc) 771 { 772 struct binderfs_mount_opts *ctx; 773 774 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL); 775 if (!ctx) 776 return -ENOMEM; 777 778 ctx->max = BINDERFS_MAX_MINOR; 779 ctx->stats_mode = binderfs_stats_mode_unset; 780 781 fc->fs_private = ctx; 782 fc->ops = &binderfs_fs_context_ops; 783 784 return 0; 785 } 786 787 static struct file_system_type binder_fs_type = { 788 .name = "binder", 789 .init_fs_context = binderfs_init_fs_context, 790 .parameters = binderfs_fs_parameters, 791 .kill_sb = kill_litter_super, 792 .fs_flags = FS_USERNS_MOUNT, 793 }; 794 795 int __init init_binderfs(void) 796 { 797 int ret; 798 const char *name; 799 size_t len; 800 801 /* Verify that the default binderfs device names are valid. */ 802 name = binder_devices_param; 803 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 804 if (len > BINDERFS_MAX_NAME) 805 return -E2BIG; 806 name += len; 807 if (*name == ',') 808 name++; 809 } 810 811 /* Allocate new major number for binderfs. */ 812 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 813 "binder"); 814 if (ret) 815 return ret; 816 817 ret = register_filesystem(&binder_fs_type); 818 if (ret) { 819 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 820 return ret; 821 } 822 823 return ret; 824 } 825