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/asm-generic/errno-base.h> 33 #include <uapi/linux/android/binder.h> 34 #include <uapi/linux/android/binderfs.h> 35 36 #include "rust_binder.h" 37 #include "rust_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 DEFINE_SHOW_ATTRIBUTE(rust_binder_stats); 47 DEFINE_SHOW_ATTRIBUTE(rust_binder_state); 48 DEFINE_SHOW_ATTRIBUTE(rust_binder_transactions); 49 DEFINE_SHOW_ATTRIBUTE(rust_binder_proc); 50 51 char *rust_binder_devices_param = CONFIG_ANDROID_BINDER_DEVICES; 52 module_param_named(rust_devices, rust_binder_devices_param, charp, 0444); 53 54 static dev_t binderfs_dev; 55 static DEFINE_MUTEX(binderfs_minors_mutex); 56 static DEFINE_IDA(binderfs_minors); 57 58 enum binderfs_param { 59 Opt_max, 60 Opt_stats_mode, 61 }; 62 63 enum binderfs_stats_mode { 64 binderfs_stats_mode_unset, 65 binderfs_stats_mode_global, 66 }; 67 68 struct binder_features { 69 bool oneway_spam_detection; 70 bool extended_error; 71 bool freeze_notification; 72 }; 73 74 static const struct constant_table binderfs_param_stats[] = { 75 { "global", binderfs_stats_mode_global }, 76 {} 77 }; 78 79 static const struct fs_parameter_spec binderfs_fs_parameters[] = { 80 fsparam_u32("max", Opt_max), 81 fsparam_enum("stats", Opt_stats_mode, binderfs_param_stats), 82 {} 83 }; 84 85 static struct binder_features binder_features = { 86 .oneway_spam_detection = true, 87 .extended_error = true, 88 .freeze_notification = true, 89 }; 90 91 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb) 92 { 93 return sb->s_fs_info; 94 } 95 96 /** 97 * binderfs_binder_device_create - allocate inode from super block of a 98 * binderfs mount 99 * @ref_inode: inode from wich 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 = NULL; 121 rust_binder_context ctx = 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 req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */ 153 154 ctx = rust_binder_new_context(req->name); 155 if (!ctx) 156 goto err; 157 158 inode = new_inode(sb); 159 if (!inode) 160 goto err; 161 162 inode->i_ino = minor + INODE_OFFSET; 163 simple_inode_init_ts(inode); 164 init_special_inode(inode, S_IFCHR | 0600, 165 MKDEV(MAJOR(binderfs_dev), minor)); 166 inode->i_fop = &rust_binder_fops; 167 inode->i_uid = info->root_uid; 168 inode->i_gid = info->root_gid; 169 170 req->major = MAJOR(binderfs_dev); 171 req->minor = minor; 172 device->ctx = ctx; 173 device->minor = minor; 174 175 if (userp && copy_to_user(userp, req, sizeof(*req))) { 176 ret = -EFAULT; 177 goto err; 178 } 179 180 root = sb->s_root; 181 dentry = simple_start_creating(root, req->name); 182 if (IS_ERR(dentry)) { 183 ret = PTR_ERR(dentry); 184 goto err; 185 } 186 187 inode->i_private = device; 188 d_make_persistent(dentry, inode); 189 190 fsnotify_create(root->d_inode, dentry); 191 simple_done_creating(dentry); 192 193 return 0; 194 195 err: 196 kfree(device); 197 rust_binder_remove_context(ctx); 198 mutex_lock(&binderfs_minors_mutex); 199 --info->device_count; 200 ida_free(&binderfs_minors, minor); 201 mutex_unlock(&binderfs_minors_mutex); 202 iput(inode); 203 204 return ret; 205 } 206 207 /** 208 * binder_ctl_ioctl - handle binder device node allocation requests 209 * 210 * The request handler for the binder-control device. All requests operate on 211 * the binderfs mount the binder-control device resides in: 212 * - BINDER_CTL_ADD 213 * Allocate a new binder device. 214 * 215 * Return: %0 on success, negative errno on failure. 216 */ 217 static long binder_ctl_ioctl(struct file *file, unsigned int cmd, 218 unsigned long arg) 219 { 220 int ret = -EINVAL; 221 struct inode *inode = file_inode(file); 222 struct binderfs_device __user *device = (struct binderfs_device __user *)arg; 223 struct binderfs_device device_req; 224 225 switch (cmd) { 226 case BINDER_CTL_ADD: 227 ret = copy_from_user(&device_req, device, sizeof(device_req)); 228 if (ret) { 229 ret = -EFAULT; 230 break; 231 } 232 233 ret = binderfs_binder_device_create(inode, device, &device_req); 234 break; 235 default: 236 break; 237 } 238 239 return ret; 240 } 241 242 static void binderfs_evict_inode(struct inode *inode) 243 { 244 struct binder_device *device = inode->i_private; 245 struct binderfs_info *info = BINDERFS_SB(inode->i_sb); 246 247 clear_inode(inode); 248 249 if (!S_ISCHR(inode->i_mode) || !device) 250 return; 251 252 mutex_lock(&binderfs_minors_mutex); 253 --info->device_count; 254 ida_free(&binderfs_minors, device->minor); 255 mutex_unlock(&binderfs_minors_mutex); 256 257 /* ctx is null for binder-control, but this function ignores null pointers */ 258 rust_binder_remove_context(device->ctx); 259 260 kfree(device); 261 } 262 263 static int binderfs_fs_context_parse_param(struct fs_context *fc, 264 struct fs_parameter *param) 265 { 266 int opt; 267 struct binderfs_mount_opts *ctx = fc->fs_private; 268 struct fs_parse_result result; 269 270 opt = fs_parse(fc, binderfs_fs_parameters, param, &result); 271 if (opt < 0) 272 return opt; 273 274 switch (opt) { 275 case Opt_max: 276 if (result.uint_32 > BINDERFS_MAX_MINOR) 277 return invalfc(fc, "Bad value for '%s'", param->key); 278 279 ctx->max = result.uint_32; 280 break; 281 case Opt_stats_mode: 282 if (!capable(CAP_SYS_ADMIN)) 283 return -EPERM; 284 285 ctx->stats_mode = result.uint_32; 286 break; 287 default: 288 return invalfc(fc, "Unsupported parameter '%s'", param->key); 289 } 290 291 return 0; 292 } 293 294 static int binderfs_fs_context_reconfigure(struct fs_context *fc) 295 { 296 struct binderfs_mount_opts *ctx = fc->fs_private; 297 struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb); 298 299 if (info->mount_opts.stats_mode != ctx->stats_mode) 300 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount"); 301 302 info->mount_opts.stats_mode = ctx->stats_mode; 303 info->mount_opts.max = ctx->max; 304 return 0; 305 } 306 307 static int binderfs_show_options(struct seq_file *seq, struct dentry *root) 308 { 309 struct binderfs_info *info = BINDERFS_SB(root->d_sb); 310 311 if (info->mount_opts.max <= BINDERFS_MAX_MINOR) 312 seq_printf(seq, ",max=%d", info->mount_opts.max); 313 314 switch (info->mount_opts.stats_mode) { 315 case binderfs_stats_mode_unset: 316 break; 317 case binderfs_stats_mode_global: 318 seq_puts(seq, ",stats=global"); 319 break; 320 } 321 322 return 0; 323 } 324 325 static const struct super_operations binderfs_super_ops = { 326 .evict_inode = binderfs_evict_inode, 327 .show_options = binderfs_show_options, 328 .statfs = simple_statfs, 329 }; 330 331 static inline bool is_binderfs_control_device(const struct dentry *dentry) 332 { 333 struct binderfs_info *info = dentry->d_sb->s_fs_info; 334 335 return info->control_dentry == dentry; 336 } 337 338 static int binderfs_rename(struct mnt_idmap *idmap, 339 struct inode *old_dir, struct dentry *old_dentry, 340 struct inode *new_dir, struct dentry *new_dentry, 341 unsigned int flags) 342 { 343 if (is_binderfs_control_device(old_dentry) || 344 is_binderfs_control_device(new_dentry)) 345 return -EPERM; 346 347 return simple_rename(idmap, old_dir, old_dentry, new_dir, 348 new_dentry, flags); 349 } 350 351 static int binderfs_unlink(struct inode *dir, struct dentry *dentry) 352 { 353 if (is_binderfs_control_device(dentry)) 354 return -EPERM; 355 356 return simple_unlink(dir, dentry); 357 } 358 359 static const struct file_operations binder_ctl_fops = { 360 .owner = THIS_MODULE, 361 .open = nonseekable_open, 362 .unlocked_ioctl = binder_ctl_ioctl, 363 .compat_ioctl = binder_ctl_ioctl, 364 .llseek = noop_llseek, 365 }; 366 367 /** 368 * binderfs_binder_ctl_create - create a new binder-control device 369 * @sb: super block of the binderfs mount 370 * 371 * This function creates a new binder-control device node in the binderfs mount 372 * referred to by @sb. 373 * 374 * Return: 0 on success, negative errno on failure 375 */ 376 static int binderfs_binder_ctl_create(struct super_block *sb) 377 { 378 int minor, ret; 379 struct dentry *dentry; 380 struct binder_device *device; 381 struct inode *inode = NULL; 382 struct dentry *root = sb->s_root; 383 struct binderfs_info *info = sb->s_fs_info; 384 #if defined(CONFIG_IPC_NS) 385 bool use_reserve = (info->ipc_ns == &init_ipc_ns); 386 #else 387 bool use_reserve = true; 388 #endif 389 390 device = kzalloc(sizeof(*device), GFP_KERNEL); 391 if (!device) 392 return -ENOMEM; 393 394 /* If we have already created a binder-control node, return. */ 395 if (info->control_dentry) { 396 ret = 0; 397 goto out; 398 } 399 400 ret = -ENOMEM; 401 inode = new_inode(sb); 402 if (!inode) 403 goto out; 404 405 /* Reserve a new minor number for the new device. */ 406 mutex_lock(&binderfs_minors_mutex); 407 minor = ida_alloc_max(&binderfs_minors, 408 use_reserve ? BINDERFS_MAX_MINOR : 409 BINDERFS_MAX_MINOR_CAPPED, 410 GFP_KERNEL); 411 mutex_unlock(&binderfs_minors_mutex); 412 if (minor < 0) { 413 ret = minor; 414 goto out; 415 } 416 417 inode->i_ino = SECOND_INODE; 418 simple_inode_init_ts(inode); 419 init_special_inode(inode, S_IFCHR | 0600, 420 MKDEV(MAJOR(binderfs_dev), minor)); 421 inode->i_fop = &binder_ctl_fops; 422 inode->i_uid = info->root_uid; 423 inode->i_gid = info->root_gid; 424 425 device->minor = minor; 426 device->ctx = NULL; 427 428 dentry = d_alloc_name(root, "binder-control"); 429 if (!dentry) 430 goto out; 431 432 inode->i_private = device; 433 info->control_dentry = dentry; 434 d_add(dentry, inode); 435 436 return 0; 437 438 out: 439 kfree(device); 440 iput(inode); 441 442 return ret; 443 } 444 445 static const struct inode_operations binderfs_dir_inode_operations = { 446 .lookup = simple_lookup, 447 .rename = binderfs_rename, 448 .unlink = binderfs_unlink, 449 }; 450 451 static struct inode *binderfs_make_inode(struct super_block *sb, int mode) 452 { 453 struct inode *ret; 454 455 ret = new_inode(sb); 456 if (ret) { 457 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET); 458 ret->i_mode = mode; 459 simple_inode_init_ts(ret); 460 } 461 return ret; 462 } 463 464 void rust_binderfs_remove_file(struct dentry *dentry) 465 { 466 simple_recursive_removal(dentry, NULL); 467 } 468 469 static struct dentry *rust_binderfs_create_file(struct dentry *parent, const char *name, 470 const struct file_operations *fops, 471 void *data) 472 { 473 struct dentry *dentry; 474 struct inode *new_inode; 475 476 new_inode = binderfs_make_inode(parent->d_sb, S_IFREG | 0444); 477 if (!new_inode) 478 return ERR_PTR(-ENOMEM); 479 new_inode->i_fop = fops; 480 new_inode->i_private = data; 481 482 dentry = simple_start_creating(parent, name); 483 if (IS_ERR(dentry)) { 484 iput(new_inode); 485 return dentry; 486 } 487 488 d_make_persistent(dentry, new_inode); 489 fsnotify_create(parent->d_inode, dentry); 490 simple_done_creating(dentry); 491 return dentry; 492 } 493 494 struct dentry *rust_binderfs_create_proc_file(struct inode *nodp, int pid) 495 { 496 struct binderfs_info *info = nodp->i_sb->s_fs_info; 497 struct dentry *dir = info->proc_log_dir; 498 char strbuf[20 + 1]; 499 void *data = (void *)(unsigned long) pid; 500 501 if (!dir) 502 return NULL; 503 504 snprintf(strbuf, sizeof(strbuf), "%u", pid); 505 return rust_binderfs_create_file(dir, strbuf, &rust_binder_proc_fops, data); 506 } 507 508 static struct dentry *binderfs_create_dir(struct dentry *parent, 509 const char *name) 510 { 511 struct dentry *dentry; 512 struct inode *new_inode; 513 514 new_inode = binderfs_make_inode(parent->d_sb, S_IFDIR | 0755); 515 if (!new_inode) 516 return ERR_PTR(-ENOMEM); 517 518 new_inode->i_fop = &simple_dir_operations; 519 new_inode->i_op = &simple_dir_inode_operations; 520 521 dentry = simple_start_creating(parent, name); 522 if (IS_ERR(dentry)) { 523 iput(new_inode); 524 return dentry; 525 } 526 527 inc_nlink(parent->d_inode); 528 set_nlink(new_inode, 2); 529 d_make_persistent(dentry, new_inode); 530 fsnotify_mkdir(parent->d_inode, dentry); 531 simple_done_creating(dentry); 532 return dentry; 533 } 534 535 static int binder_features_show(struct seq_file *m, void *unused) 536 { 537 bool *feature = m->private; 538 539 seq_printf(m, "%d\n", *feature); 540 541 return 0; 542 } 543 DEFINE_SHOW_ATTRIBUTE(binder_features); 544 545 static int init_binder_features(struct super_block *sb) 546 { 547 struct dentry *dentry, *dir; 548 549 dir = binderfs_create_dir(sb->s_root, "features"); 550 if (IS_ERR(dir)) 551 return PTR_ERR(dir); 552 553 dentry = rust_binderfs_create_file(dir, "oneway_spam_detection", 554 &binder_features_fops, 555 &binder_features.oneway_spam_detection); 556 if (IS_ERR(dentry)) 557 return PTR_ERR(dentry); 558 559 dentry = rust_binderfs_create_file(dir, "extended_error", 560 &binder_features_fops, 561 &binder_features.extended_error); 562 if (IS_ERR(dentry)) 563 return PTR_ERR(dentry); 564 565 dentry = rust_binderfs_create_file(dir, "freeze_notification", 566 &binder_features_fops, 567 &binder_features.freeze_notification); 568 if (IS_ERR(dentry)) 569 return PTR_ERR(dentry); 570 571 return 0; 572 } 573 574 static int init_binder_logs(struct super_block *sb) 575 { 576 struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir; 577 struct binderfs_info *info; 578 int ret = 0; 579 580 binder_logs_root_dir = binderfs_create_dir(sb->s_root, 581 "binder_logs"); 582 if (IS_ERR(binder_logs_root_dir)) { 583 ret = PTR_ERR(binder_logs_root_dir); 584 goto out; 585 } 586 587 dentry = rust_binderfs_create_file(binder_logs_root_dir, "stats", 588 &rust_binder_stats_fops, NULL); 589 if (IS_ERR(dentry)) { 590 ret = PTR_ERR(dentry); 591 goto out; 592 } 593 594 dentry = rust_binderfs_create_file(binder_logs_root_dir, "state", 595 &rust_binder_state_fops, NULL); 596 if (IS_ERR(dentry)) { 597 ret = PTR_ERR(dentry); 598 goto out; 599 } 600 601 dentry = rust_binderfs_create_file(binder_logs_root_dir, "transactions", 602 &rust_binder_transactions_fops, NULL); 603 if (IS_ERR(dentry)) { 604 ret = PTR_ERR(dentry); 605 goto out; 606 } 607 608 proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc"); 609 if (IS_ERR(proc_log_dir)) { 610 ret = PTR_ERR(proc_log_dir); 611 goto out; 612 } 613 info = sb->s_fs_info; 614 info->proc_log_dir = proc_log_dir; 615 616 out: 617 return ret; 618 } 619 620 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc) 621 { 622 int ret; 623 struct binderfs_info *info; 624 struct binderfs_mount_opts *ctx = fc->fs_private; 625 struct inode *inode = NULL; 626 struct binderfs_device device_info = {}; 627 const char *name; 628 size_t len; 629 630 sb->s_blocksize = PAGE_SIZE; 631 sb->s_blocksize_bits = PAGE_SHIFT; 632 633 /* 634 * The binderfs filesystem can be mounted by userns root in a 635 * non-initial userns. By default such mounts have the SB_I_NODEV flag 636 * set in s_iflags to prevent security issues where userns root can 637 * just create random device nodes via mknod() since it owns the 638 * filesystem mount. But binderfs does not allow to create any files 639 * including devices nodes. The only way to create binder devices nodes 640 * is through the binder-control device which userns root is explicitly 641 * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both 642 * necessary and safe. 643 */ 644 sb->s_iflags &= ~SB_I_NODEV; 645 sb->s_iflags |= SB_I_NOEXEC; 646 sb->s_magic = RUST_BINDERFS_SUPER_MAGIC; 647 sb->s_op = &binderfs_super_ops; 648 sb->s_time_gran = 1; 649 650 sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL); 651 if (!sb->s_fs_info) 652 return -ENOMEM; 653 info = sb->s_fs_info; 654 655 info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns); 656 657 info->root_gid = make_kgid(sb->s_user_ns, 0); 658 if (!gid_valid(info->root_gid)) 659 info->root_gid = GLOBAL_ROOT_GID; 660 info->root_uid = make_kuid(sb->s_user_ns, 0); 661 if (!uid_valid(info->root_uid)) 662 info->root_uid = GLOBAL_ROOT_UID; 663 info->mount_opts.max = ctx->max; 664 info->mount_opts.stats_mode = ctx->stats_mode; 665 666 inode = new_inode(sb); 667 if (!inode) 668 return -ENOMEM; 669 670 inode->i_ino = FIRST_INODE; 671 inode->i_fop = &simple_dir_operations; 672 inode->i_mode = S_IFDIR | 0755; 673 simple_inode_init_ts(inode); 674 inode->i_op = &binderfs_dir_inode_operations; 675 set_nlink(inode, 2); 676 677 sb->s_root = d_make_root(inode); 678 if (!sb->s_root) 679 return -ENOMEM; 680 681 ret = binderfs_binder_ctl_create(sb); 682 if (ret) 683 return ret; 684 685 name = rust_binder_devices_param; 686 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 687 strscpy(device_info.name, name, len + 1); 688 ret = binderfs_binder_device_create(inode, NULL, &device_info); 689 if (ret) 690 return ret; 691 name += len; 692 if (*name == ',') 693 name++; 694 } 695 696 ret = init_binder_features(sb); 697 if (ret) 698 return ret; 699 700 if (info->mount_opts.stats_mode == binderfs_stats_mode_global) 701 return init_binder_logs(sb); 702 703 return 0; 704 } 705 706 static int binderfs_fs_context_get_tree(struct fs_context *fc) 707 { 708 return get_tree_nodev(fc, binderfs_fill_super); 709 } 710 711 static void binderfs_fs_context_free(struct fs_context *fc) 712 { 713 struct binderfs_mount_opts *ctx = fc->fs_private; 714 715 kfree(ctx); 716 } 717 718 static const struct fs_context_operations binderfs_fs_context_ops = { 719 .free = binderfs_fs_context_free, 720 .get_tree = binderfs_fs_context_get_tree, 721 .parse_param = binderfs_fs_context_parse_param, 722 .reconfigure = binderfs_fs_context_reconfigure, 723 }; 724 725 static int binderfs_init_fs_context(struct fs_context *fc) 726 { 727 struct binderfs_mount_opts *ctx; 728 729 ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL); 730 if (!ctx) 731 return -ENOMEM; 732 733 ctx->max = BINDERFS_MAX_MINOR; 734 ctx->stats_mode = binderfs_stats_mode_unset; 735 736 fc->fs_private = ctx; 737 fc->ops = &binderfs_fs_context_ops; 738 739 return 0; 740 } 741 742 static void binderfs_kill_super(struct super_block *sb) 743 { 744 struct binderfs_info *info = sb->s_fs_info; 745 746 /* 747 * During inode eviction struct binderfs_info is needed. 748 * So first wipe the super_block then free struct binderfs_info. 749 */ 750 kill_anon_super(sb); 751 752 if (info && info->ipc_ns) 753 put_ipc_ns(info->ipc_ns); 754 755 kfree(info); 756 } 757 758 static struct file_system_type binder_fs_type = { 759 .name = "binder", 760 .init_fs_context = binderfs_init_fs_context, 761 .parameters = binderfs_fs_parameters, 762 .kill_sb = binderfs_kill_super, 763 .fs_flags = FS_USERNS_MOUNT, 764 }; 765 766 int init_rust_binderfs(void) 767 { 768 int ret; 769 const char *name; 770 size_t len; 771 772 /* Verify that the default binderfs device names are valid. */ 773 name = rust_binder_devices_param; 774 for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) { 775 if (len > BINDERFS_MAX_NAME) 776 return -E2BIG; 777 name += len; 778 if (*name == ',') 779 name++; 780 } 781 782 /* Allocate new major number for binderfs. */ 783 ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR, 784 "rust_binder"); 785 if (ret) 786 return ret; 787 788 ret = register_filesystem(&binder_fs_type); 789 if (ret) { 790 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR); 791 return ret; 792 } 793 794 return ret; 795 } 796