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 void binderfs_remove_file(struct dentry *dentry) 504 { 505 struct inode *parent_inode; 506 507 parent_inode = d_inode(dentry->d_parent); 508 inode_lock(parent_inode); 509 if (simple_positive(dentry)) { 510 dget(dentry); 511 simple_unlink(parent_inode, dentry); 512 d_delete(dentry); 513 dput(dentry); 514 } 515 inode_unlock(parent_inode); 516 } 517 518 struct dentry *binderfs_create_file(struct dentry *parent, const char *name, 519 const struct file_operations *fops, 520 void *data) 521 { 522 struct dentry *dentry; 523 struct inode *new_inode, *parent_inode; 524 struct super_block *sb; 525 526 parent_inode = d_inode(parent); 527 inode_lock(parent_inode); 528 529 dentry = binderfs_create_dentry(parent, name); 530 if (IS_ERR(dentry)) 531 goto out; 532 533 sb = parent_inode->i_sb; 534 new_inode = binderfs_make_inode(sb, S_IFREG | 0444); 535 if (!new_inode) { 536 dput(dentry); 537 dentry = ERR_PTR(-ENOMEM); 538 goto out; 539 } 540 541 new_inode->i_fop = fops; 542 new_inode->i_private = data; 543 d_instantiate(dentry, new_inode); 544 fsnotify_create(parent_inode, dentry); 545 546 out: 547 inode_unlock(parent_inode); 548 return dentry; 549 } 550 551 static struct dentry *binderfs_create_dir(struct dentry *parent, 552 const char *name) 553 { 554 struct dentry *dentry; 555 struct inode *new_inode, *parent_inode; 556 struct super_block *sb; 557 558 parent_inode = d_inode(parent); 559 inode_lock(parent_inode); 560 561 dentry = binderfs_create_dentry(parent, name); 562 if (IS_ERR(dentry)) 563 goto out; 564 565 sb = parent_inode->i_sb; 566 new_inode = binderfs_make_inode(sb, S_IFDIR | 0755); 567 if (!new_inode) { 568 dput(dentry); 569 dentry = ERR_PTR(-ENOMEM); 570 goto out; 571 } 572 573 new_inode->i_fop = &simple_dir_operations; 574 new_inode->i_op = &simple_dir_inode_operations; 575 576 set_nlink(new_inode, 2); 577 d_instantiate(dentry, new_inode); 578 inc_nlink(parent_inode); 579 fsnotify_mkdir(parent_inode, dentry); 580 581 out: 582 inode_unlock(parent_inode); 583 return dentry; 584 } 585 586 static int binder_features_show(struct seq_file *m, void *unused) 587 { 588 bool *feature = m->private; 589 590 seq_printf(m, "%d\n", *feature); 591 592 return 0; 593 } 594 DEFINE_SHOW_ATTRIBUTE(binder_features); 595 596 static int init_binder_features(struct super_block *sb) 597 { 598 struct dentry *dentry, *dir; 599 600 dir = binderfs_create_dir(sb->s_root, "features"); 601 if (IS_ERR(dir)) 602 return PTR_ERR(dir); 603 604 dentry = binderfs_create_file(dir, "oneway_spam_detection", 605 &binder_features_fops, 606 &binder_features.oneway_spam_detection); 607 if (IS_ERR(dentry)) 608 return PTR_ERR(dentry); 609 610 dentry = binderfs_create_file(dir, "extended_error", 611 &binder_features_fops, 612 &binder_features.extended_error); 613 if (IS_ERR(dentry)) 614 return PTR_ERR(dentry); 615 616 dentry = binderfs_create_file(dir, "freeze_notification", 617 &binder_features_fops, 618 &binder_features.freeze_notification); 619 if (IS_ERR(dentry)) 620 return PTR_ERR(dentry); 621 622 return 0; 623 } 624 625 static int init_binder_logs(struct super_block *sb) 626 { 627 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 628 const struct binder_debugfs_entry *db_entry; 629 struct binderfs_info *info; 630 int ret = 0; 631 632 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 633 "binder_logs"); 634 if (IS_ERR(binder_logs_root_dir)) { 635 ret = PTR_ERR(binder_logs_root_dir); 636 goto out; 637 } 638 639 binder_for_each_debugfs_entry(db_entry) { 640 dentry = binderfs_create_file(binder_logs_root_dir, 641 db_entry->name, 642 db_entry->fops, 643 db_entry->data); 644 if (IS_ERR(dentry)) { 645 ret = PTR_ERR(dentry); 646 goto out; 647 } 648 } 649 650 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 651 if (IS_ERR(proc_log_dir)) { 652 ret = PTR_ERR(proc_log_dir); 653 goto out; 654 } 655 info = sb->s_fs_info; 656 info->proc_log_dir = proc_log_dir; 657 658 out: 659 return ret; 660 } 661 662 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 663 { 664 int ret; 665 struct binderfs_info *info; 666 struct binderfs_mount_opts *ctx = fc->fs_private; 667 struct inode *inode = NULL; 668 struct binderfs_device device_info = {}; 669 const char *name; 670 size_t len; 671 672 sb->s_blocksize = PAGE_SIZE; 673 sb->s_blocksize_bits = PAGE_SHIFT; 674 675 /* 676 * The binderfs filesystem can be mounted by userns root in a 677 * non-initial userns. By default such mounts have the SB_I_NODEV flag 678 * set in s_iflags to prevent security issues where userns root can 679 * just create random device nodes via mknod() since it owns the 680 * filesystem mount. But binderfs does not allow to create any files 681 * including devices nodes. The only way to create binder devices nodes 682 * is through the binder-control device which userns root is explicitly 683 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 684 * necessary and safe. 685 */ 686 sb->s_iflags &= ~SB_I_NODEV; 687 sb->s_iflags |= SB_I_NOEXEC; 688 sb->s_magic = BINDERFS_SUPER_MAGIC; 689 sb->s_op = &binderfs_super_ops; 690 sb->s_time_gran = 1; 691 692 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 693 if (!sb->s_fs_info) 694 return -ENOMEM; 695 info = sb->s_fs_info; 696 697 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 698 699 info->root_gid = make_kgid(sb->s_user_ns, 0); 700 if (!gid_valid(info->root_gid)) 701 info->root_gid = GLOBAL_ROOT_GID; 702 info->root_uid = make_kuid(sb->s_user_ns, 0); 703 if (!uid_valid(info->root_uid)) 704 info->root_uid = GLOBAL_ROOT_UID; 705 info->mount_opts.max = ctx->max; 706 info->mount_opts.stats_mode = ctx->stats_mode; 707 708 inode = new_inode(sb); 709 if (!inode) 710 return -ENOMEM; 711 712 inode->i_ino = FIRST_INODE; 713 inode->i_fop = &simple_dir_operations; 714 inode->i_mode = S_IFDIR | 0755; 715 simple_inode_init_ts(inode); 716 inode->i_op = &binderfs_dir_inode_operations; 717 set_nlink(inode, 2); 718 719 sb->s_root = d_make_root(inode); 720 if (!sb->s_root) 721 return -ENOMEM; 722 723 ret = binderfs_binder_ctl_create(sb); 724 if (ret) 725 return ret; 726 727 name = binder_devices_param; 728 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 729 strscpy(device_info.name, name, len + 1); 730 ret = binderfs_binder_device_create(inode, NULL, &device_info); 731 if (ret) 732 return ret; 733 name += len; 734 if (*name == ',') 735 name++; 736 } 737 738 ret = init_binder_features(sb); 739 if (ret) 740 return ret; 741 742 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 743 return init_binder_logs(sb); 744 745 return 0; 746 } 747 748 static int binderfs_fs_context_get_tree(struct fs_context *fc) 749 { 750 return get_tree_nodev(fc, binderfs_fill_super); 751 } 752 753 static void binderfs_fs_context_free(struct fs_context *fc) 754 { 755 struct binderfs_mount_opts *ctx = fc->fs_private; 756 757 kfree(ctx); 758 } 759 760 static const struct fs_context_operations binderfs_fs_context_ops = { 761 .free = binderfs_fs_context_free, 762 .get_tree = binderfs_fs_context_get_tree, 763 .parse_param = binderfs_fs_context_parse_param, 764 .reconfigure = binderfs_fs_context_reconfigure, 765 }; 766 767 static int binderfs_init_fs_context(struct fs_context *fc) 768 { 769 struct binderfs_mount_opts *ctx; 770 771 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL); 772 if (!ctx) 773 return -ENOMEM; 774 775 ctx->max = BINDERFS_MAX_MINOR; 776 ctx->stats_mode = binderfs_stats_mode_unset; 777 778 fc->fs_private = ctx; 779 fc->ops = &binderfs_fs_context_ops; 780 781 return 0; 782 } 783 784 static void binderfs_kill_super(struct super_block *sb) 785 { 786 struct binderfs_info *info = sb->s_fs_info; 787 788 /* 789 * During inode eviction struct binderfs_info is needed. 790 * So first wipe the super_block then free struct binderfs_info. 791 */ 792 kill_litter_super(sb); 793 794 if (info && info->ipc_ns) 795 put_ipc_ns(info->ipc_ns); 796 797 kfree(info); 798 } 799 800 static struct file_system_type binder_fs_type = { 801 .name = "binder", 802 .init_fs_context = binderfs_init_fs_context, 803 .parameters = binderfs_fs_parameters, 804 .kill_sb = binderfs_kill_super, 805 .fs_flags = FS_USERNS_MOUNT, 806 }; 807 808 int __init init_binderfs(void) 809 { 810 int ret; 811 const char *name; 812 size_t len; 813 814 /* Verify that the default binderfs device names are valid. */ 815 name = binder_devices_param; 816 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 817 if (len > BINDERFS_MAX_NAME) 818 return -E2BIG; 819 name += len; 820 if (*name == ',') 821 name++; 822 } 823 824 /* Allocate new major number for binderfs. */ 825 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 826 "binder"); 827 if (ret) 828 return ret; 829 830 ret = register_filesystem(&binder_fs_type); 831 if (ret) { 832 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 833 return ret; 834 } 835 836 return ret; 837 } 838