drivers/android/binderfs.c

   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/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 INTSTRLEN 21
  43 #define BINDERFS_MAX_MINOR (1U << MINORBITS)
  44 /* Ensure that the initial ipc namespace always has devices available. */
  45 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
  46
  47 static dev_t binderfs_dev;
  48 static DEFINE_MUTEX(binderfs_minors_mutex);
  49 static DEFINE_IDA(binderfs_minors);
  50
  51 enum {
  52         Opt_max,
  53         Opt_stats_mode,
  54         Opt_err
  55 };
  56
  57 enum binderfs_stats_mode {
  58         STATS_NONE,
  59         STATS_GLOBAL,
  60 };
  61
  62 static const match_table_t tokens = {
  63         { Opt_max, "max=%d" },
  64         { Opt_stats_mode, "stats=%s" },
  65         { Opt_err, NULL     }
  66 };
  67
  68 static inline struct binderfs_info *BINDERFS_I(const struct inode *inode)
  69 {
  70         return inode->i_sb->s_fs_info;
  71 }
  72
  73 bool is_binderfs_device(const struct inode *inode)
  74 {
  75         if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
  76                 return true;
  77
  78         return false;
  79 }
  80
  81 /**
  82  * binderfs_binder_device_create - allocate inode from super block of a
  83  *                                 binderfs mount
  84  * @ref_inode: inode from wich the super block will be taken
  85  * @userp:     buffer to copy information about new device for userspace to
  86  * @req:       struct binderfs_device as copied from userspace
  87  *
  88  * This function allocates a new binder_device and reserves a new minor
  89  * number for it.
  90  * Minor numbers are limited and tracked globally in binderfs_minors. The
  91  * function will stash a struct binder_device for the specific binder
  92  * device in i_private of the inode.
  93  * It will go on to allocate a new inode from the super block of the
  94  * filesystem mount, stash a struct binder_device in its i_private field
  95  * and attach a dentry to that inode.
  96  *
  97  * Return: 0 on success, negative errno on failure
  98  */
  99 static int binderfs_binder_device_create(struct inode *ref_inode,
 100                                          struct binderfs_device __user *userp,
 101                                          struct binderfs_device *req)
 102 {
 103         int minor, ret;
 104         struct dentry *dentry, *root;
 105         struct binder_device *device;
 106         char *name = NULL;
 107         size_t name_len;
 108         struct inode *inode = NULL;
 109         struct super_block *sb = ref_inode->i_sb;
 110         struct binderfs_info *info = sb->s_fs_info;
 111 #if defined(CONFIG_IPC_NS)
 112         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 113 #else
 114         bool use_reserve = true;
 115 #endif
 116
 117         /* Reserve new minor number for the new device. */
 118         mutex_lock(&binderfs_minors_mutex);
 119         if (++info->device_count <= info->mount_opts.max)
 120                 minor = ida_alloc_max(&binderfs_minors,
 121                                       use_reserve ? BINDERFS_MAX_MINOR :
 122                                                     BINDERFS_MAX_MINOR_CAPPED,
 123                                       GFP_KERNEL);
 124         else
 125                 minor = -ENOSPC;
 126         if (minor < 0) {
 127                 --info->device_count;
 128                 mutex_unlock(&binderfs_minors_mutex);
 129                 return minor;
 130         }
 131         mutex_unlock(&binderfs_minors_mutex);
 132
 133         ret = -ENOMEM;
 134         device = kzalloc(sizeof(*device), GFP_KERNEL);
 135         if (!device)
 136                 goto err;
 137
 138         inode = new_inode(sb);
 139         if (!inode)
 140                 goto err;
 141
 142         inode->i_ino = minor + INODE_OFFSET;
 143         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 144         init_special_inode(inode, S_IFCHR | 0600,
 145                            MKDEV(MAJOR(binderfs_dev), minor));
 146         inode->i_fop = &binder_fops;
 147         inode->i_uid = info->root_uid;
 148         inode->i_gid = info->root_gid;
 149
 150         req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
 151         name_len = strlen(req->name);
 152         /* Make sure to include terminating NUL byte */
 153         name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
 154         if (!name)
 155                 goto err;
 156
 157         device->binderfs_inode = inode;
 158         device->context.binder_context_mgr_uid = INVALID_UID;
 159         device->context.name = name;
 160         device->miscdev.name = name;
 161         device->miscdev.minor = minor;
 162         mutex_init(&device->context.context_mgr_node_lock);
 163
 164         req->major = MAJOR(binderfs_dev);
 165         req->minor = minor;
 166
 167         if (userp && copy_to_user(userp, req, sizeof(*req))) {
 168                 ret = -EFAULT;
 169                 goto err;
 170         }
 171
 172         root = sb->s_root;
 173         inode_lock(d_inode(root));
 174
 175         /* look it up */
 176         dentry = lookup_one_len(name, root, name_len);
 177         if (IS_ERR(dentry)) {
 178                 inode_unlock(d_inode(root));
 179                 ret = PTR_ERR(dentry);
 180                 goto err;
 181         }
 182
 183         if (d_really_is_positive(dentry)) {
 184                 /* already exists */
 185                 dput(dentry);
 186                 inode_unlock(d_inode(root));
 187                 ret = -EEXIST;
 188                 goto err;
 189         }
 190
 191         inode->i_private = device;
 192         d_instantiate(dentry, inode);
 193         fsnotify_create(root->d_inode, dentry);
 194         inode_unlock(d_inode(root));
 195
 196         return 0;
 197
 198 err:
 199         kfree(name);
 200         kfree(device);
 201         mutex_lock(&binderfs_minors_mutex);
 202         --info->device_count;
 203         ida_free(&binderfs_minors, minor);
 204         mutex_unlock(&binderfs_minors_mutex);
 205         iput(inode);
 206
 207         return ret;
 208 }
 209
 210 /**
 211  * binderfs_ctl_ioctl - handle binder device node allocation requests
 212  *
 213  * The request handler for the binder-control device. All requests operate on
 214  * the binderfs mount the binder-control device resides in:
 215  * - BINDER_CTL_ADD
 216  *   Allocate a new binder device.
 217  *
 218  * Return: 0 on success, negative errno on failure
 219  */
 220 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
 221                              unsigned long arg)
 222 {
 223         int ret = -EINVAL;
 224         struct inode *inode = file_inode(file);
 225         struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
 226         struct binderfs_device device_req;
 227
 228         switch (cmd) {
 229         case BINDER_CTL_ADD:
 230                 ret = copy_from_user(&device_req, device, sizeof(device_req));
 231                 if (ret) {
 232                         ret = -EFAULT;
 233                         break;
 234                 }
 235
 236                 ret = binderfs_binder_device_create(inode, device, &device_req);
 237                 break;
 238         default:
 239                 break;
 240         }
 241
 242         return ret;
 243 }
 244
 245 static void binderfs_evict_inode(struct inode *inode)
 246 {
 247         struct binder_device *device = inode->i_private;
 248         struct binderfs_info *info = BINDERFS_I(inode);
 249
 250         clear_inode(inode);
 251
 252         if (!S_ISCHR(inode->i_mode) || !device)
 253                 return;
 254
 255         mutex_lock(&binderfs_minors_mutex);
 256         --info->device_count;
 257         ida_free(&binderfs_minors, device->miscdev.minor);
 258         mutex_unlock(&binderfs_minors_mutex);
 259
 260         kfree(device->context.name);
 261         kfree(device);
 262 }
 263
 264 /**
 265  * binderfs_parse_mount_opts - parse binderfs mount options
 266  * @data: options to set (can be NULL in which case defaults are used)
 267  */
 268 static int binderfs_parse_mount_opts(char *data,
 269                                      struct binderfs_mount_opts *opts)
 270 {
 271         char *p, *stats;
 272         opts->max = BINDERFS_MAX_MINOR;
 273         opts->stats_mode = STATS_NONE;
 274
 275         while ((p = strsep(&data, ",")) != NULL) {
 276                 substring_t args[MAX_OPT_ARGS];
 277                 int token;
 278                 int max_devices;
 279
 280                 if (!*p)
 281                         continue;
 282
 283                 token = match_token(p, tokens, args);
 284                 switch (token) {
 285                 case Opt_max:
 286                         if (match_int(&args[0], &max_devices) ||
 287                             (max_devices < 0 ||
 288                              (max_devices > BINDERFS_MAX_MINOR)))
 289                                 return -EINVAL;
 290
 291                         opts->max = max_devices;
 292                         break;
 293                 case Opt_stats_mode:
 294                         if (!capable(CAP_SYS_ADMIN))
 295                                 return -EINVAL;
 296
 297                         stats = match_strdup(&args[0]);
 298                         if (!stats)
 299                                 return -ENOMEM;
 300
 301                         if (strcmp(stats, "global") != 0) {
 302                                 kfree(stats);
 303                                 return -EINVAL;
 304                         }
 305
 306                         opts->stats_mode = STATS_GLOBAL;
 307                         kfree(stats);
 308                         break;
 309                 default:
 310                         pr_err("Invalid mount options\n");
 311                         return -EINVAL;
 312                 }
 313         }
 314
 315         return 0;
 316 }
 317
 318 static int binderfs_remount(struct super_block *sb, int *flags, char *data)
 319 {
 320         int prev_stats_mode, ret;
 321         struct binderfs_info *info = sb->s_fs_info;
 322
 323         prev_stats_mode = info->mount_opts.stats_mode;
 324         ret = binderfs_parse_mount_opts(data, &info->mount_opts);
 325         if (ret)
 326                 return ret;
 327
 328         if (prev_stats_mode != info->mount_opts.stats_mode) {
 329                 pr_err("Binderfs stats mode cannot be changed during a remount\n");
 330                 info->mount_opts.stats_mode = prev_stats_mode;
 331                 return -EINVAL;
 332         }
 333
 334         return 0;
 335 }
 336
 337 static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
 338 {
 339         struct binderfs_info *info;
 340
 341         info = root->d_sb->s_fs_info;
 342         if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
 343                 seq_printf(seq, ",max=%d", info->mount_opts.max);
 344         if (info->mount_opts.stats_mode == STATS_GLOBAL)
 345                 seq_printf(seq, ",stats=global");
 346
 347         return 0;
 348 }
 349
 350 static const struct super_operations binderfs_super_ops = {
 351         .evict_inode    = binderfs_evict_inode,
 352         .remount_fs     = binderfs_remount,
 353         .show_options   = binderfs_show_mount_opts,
 354         .statfs         = simple_statfs,
 355 };
 356
 357 static inline bool is_binderfs_control_device(const struct dentry *dentry)
 358 {
 359         struct binderfs_info *info = dentry->d_sb->s_fs_info;
 360         return info->control_dentry == dentry;
 361 }
 362
 363 static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 364                            struct inode *new_dir, struct dentry *new_dentry,
 365                            unsigned int flags)
 366 {
 367         if (is_binderfs_control_device(old_dentry) ||
 368             is_binderfs_control_device(new_dentry))
 369                 return -EPERM;
 370
 371         return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
 372 }
 373
 374 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
 375 {
 376         if (is_binderfs_control_device(dentry))
 377                 return -EPERM;
 378
 379         return simple_unlink(dir, dentry);
 380 }
 381
 382 static const struct file_operations binder_ctl_fops = {
 383         .owner          = THIS_MODULE,
 384         .open           = nonseekable_open,
 385         .unlocked_ioctl = binder_ctl_ioctl,
 386         .compat_ioctl   = binder_ctl_ioctl,
 387         .llseek         = noop_llseek,
 388 };
 389
 390 /**
 391  * binderfs_binder_ctl_create - create a new binder-control device
 392  * @sb: super block of the binderfs mount
 393  *
 394  * This function creates a new binder-control device node in the binderfs mount
 395  * referred to by @sb.
 396  *
 397  * Return: 0 on success, negative errno on failure
 398  */
 399 static int binderfs_binder_ctl_create(struct super_block *sb)
 400 {
 401         int minor, ret;
 402         struct dentry *dentry;
 403         struct binder_device *device;
 404         struct inode *inode = NULL;
 405         struct dentry *root = sb->s_root;
 406         struct binderfs_info *info = sb->s_fs_info;
 407 #if defined(CONFIG_IPC_NS)
 408         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 409 #else
 410         bool use_reserve = true;
 411 #endif
 412
 413         device = kzalloc(sizeof(*device), GFP_KERNEL);
 414         if (!device)
 415                 return -ENOMEM;
 416
 417         /* If we have already created a binder-control node, return. */
 418         if (info->control_dentry) {
 419                 ret = 0;
 420                 goto out;
 421         }
 422
 423         ret = -ENOMEM;
 424         inode = new_inode(sb);
 425         if (!inode)
 426                 goto out;
 427
 428         /* Reserve a new minor number for the new device. */
 429         mutex_lock(&binderfs_minors_mutex);
 430         minor = ida_alloc_max(&binderfs_minors,
 431                               use_reserve ? BINDERFS_MAX_MINOR :
 432                                             BINDERFS_MAX_MINOR_CAPPED,
 433                               GFP_KERNEL);
 434         mutex_unlock(&binderfs_minors_mutex);
 435         if (minor < 0) {
 436                 ret = minor;
 437                 goto out;
 438         }
 439
 440         inode->i_ino = SECOND_INODE;
 441         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 442         init_special_inode(inode, S_IFCHR | 0600,
 443                            MKDEV(MAJOR(binderfs_dev), minor));
 444         inode->i_fop = &binder_ctl_fops;
 445         inode->i_uid = info->root_uid;
 446         inode->i_gid = info->root_gid;
 447
 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                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(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_one_len(name, parent, strlen(name));
 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 void binderfs_remove_file(struct dentry *dentry)
 506 {
 507         struct inode *parent_inode;
 508
 509         parent_inode = d_inode(dentry->d_parent);
 510         inode_lock(parent_inode);
 511         if (simple_positive(dentry)) {
 512                 dget(dentry);
 513                 simple_unlink(parent_inode, dentry);
 514                 d_delete(dentry);
 515                 dput(dentry);
 516         }
 517         inode_unlock(parent_inode);
 518 }
 519
 520 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
 521                                     const struct file_operations *fops,
 522                                     void *data)
 523 {
 524         struct dentry *dentry;
 525         struct inode *new_inode, *parent_inode;
 526         struct super_block *sb;
 527
 528         parent_inode = d_inode(parent);
 529         inode_lock(parent_inode);
 530
 531         dentry = binderfs_create_dentry(parent, name);
 532         if (IS_ERR(dentry))
 533                 goto out;
 534
 535         sb = parent_inode->i_sb;
 536         new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
 537         if (!new_inode) {
 538                 dput(dentry);
 539                 dentry = ERR_PTR(-ENOMEM);
 540                 goto out;
 541         }
 542
 543         new_inode->i_fop = fops;
 544         new_inode->i_private = data;
 545         d_instantiate(dentry, new_inode);
 546         fsnotify_create(parent_inode, dentry);
 547
 548 out:
 549         inode_unlock(parent_inode);
 550         return dentry;
 551 }
 552
 553 static struct dentry *binderfs_create_dir(struct dentry *parent,
 554                                           const char *name)
 555 {
 556         struct dentry *dentry;
 557         struct inode *new_inode, *parent_inode;
 558         struct super_block *sb;
 559
 560         parent_inode = d_inode(parent);
 561         inode_lock(parent_inode);
 562
 563         dentry = binderfs_create_dentry(parent, name);
 564         if (IS_ERR(dentry))
 565                 goto out;
 566
 567         sb = parent_inode->i_sb;
 568         new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
 569         if (!new_inode) {
 570                 dput(dentry);
 571                 dentry = ERR_PTR(-ENOMEM);
 572                 goto out;
 573         }
 574
 575         new_inode->i_fop = &simple_dir_operations;
 576         new_inode->i_op = &simple_dir_inode_operations;
 577
 578         set_nlink(new_inode, 2);
 579         d_instantiate(dentry, new_inode);
 580         inc_nlink(parent_inode);
 581         fsnotify_mkdir(parent_inode, dentry);
 582
 583 out:
 584         inode_unlock(parent_inode);
 585         return dentry;
 586 }
 587
 588 static int init_binder_logs(struct super_block *sb)
 589 {
 590         struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
 591         struct binderfs_info *info;
 592         int ret = 0;
 593
 594         binder_logs_root_dir = binderfs_create_dir(sb->s_root,
 595                                                    "binder_logs");
 596         if (IS_ERR(binder_logs_root_dir)) {
 597                 ret = PTR_ERR(binder_logs_root_dir);
 598                 goto out;
 599         }
 600
 601         dentry = binderfs_create_file(binder_logs_root_dir, "stats",
 602                                       &binder_stats_fops, NULL);
 603         if (IS_ERR(dentry)) {
 604                 ret = PTR_ERR(dentry);
 605                 goto out;
 606         }
 607
 608         dentry = binderfs_create_file(binder_logs_root_dir, "state",
 609                                       &binder_state_fops, NULL);
 610         if (IS_ERR(dentry)) {
 611                 ret = PTR_ERR(dentry);
 612                 goto out;
 613         }
 614
 615         dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
 616                                       &binder_transactions_fops, NULL);
 617         if (IS_ERR(dentry)) {
 618                 ret = PTR_ERR(dentry);
 619                 goto out;
 620         }
 621
 622         dentry = binderfs_create_file(binder_logs_root_dir,
 623                                       "transaction_log",
 624                                       &binder_transaction_log_fops,
 625                                       &binder_transaction_log);
 626         if (IS_ERR(dentry)) {
 627                 ret = PTR_ERR(dentry);
 628                 goto out;
 629         }
 630
 631         dentry = binderfs_create_file(binder_logs_root_dir,
 632                                       "failed_transaction_log",
 633                                       &binder_transaction_log_fops,
 634                                       &binder_transaction_log_failed);
 635         if (IS_ERR(dentry)) {
 636                 ret = PTR_ERR(dentry);
 637                 goto out;
 638         }
 639
 640         proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
 641         if (IS_ERR(proc_log_dir)) {
 642                 ret = PTR_ERR(proc_log_dir);
 643                 goto out;
 644         }
 645         info = sb->s_fs_info;
 646         info->proc_log_dir = proc_log_dir;
 647
 648 out:
 649         return ret;
 650 }
 651
 652 static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
 653 {
 654         int ret;
 655         struct binderfs_info *info;
 656         struct inode *inode = NULL;
 657         struct binderfs_device device_info = { 0 };
 658         const char *name;
 659         size_t len;
 660
 661         sb->s_blocksize = PAGE_SIZE;
 662         sb->s_blocksize_bits = PAGE_SHIFT;
 663
 664         /*
 665          * The binderfs filesystem can be mounted by userns root in a
 666          * non-initial userns. By default such mounts have the SB_I_NODEV flag
 667          * set in s_iflags to prevent security issues where userns root can
 668          * just create random device nodes via mknod() since it owns the
 669          * filesystem mount. But binderfs does not allow to create any files
 670          * including devices nodes. The only way to create binder devices nodes
 671          * is through the binder-control device which userns root is explicitly
 672          * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
 673          * necessary and safe.
 674          */
 675         sb->s_iflags &= ~SB_I_NODEV;
 676         sb->s_iflags |= SB_I_NOEXEC;
 677         sb->s_magic = BINDERFS_SUPER_MAGIC;
 678         sb->s_op = &binderfs_super_ops;
 679         sb->s_time_gran = 1;
 680
 681         sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
 682         if (!sb->s_fs_info)
 683                 return -ENOMEM;
 684         info = sb->s_fs_info;
 685
 686         info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
 687
 688         ret = binderfs_parse_mount_opts(data, &info->mount_opts);
 689         if (ret)
 690                 return ret;
 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
 699         inode = new_inode(sb);
 700         if (!inode)
 701                 return -ENOMEM;
 702
 703         inode->i_ino = FIRST_INODE;
 704         inode->i_fop = &simple_dir_operations;
 705         inode->i_mode = S_IFDIR | 0755;
 706         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 707         inode->i_op = &binderfs_dir_inode_operations;
 708         set_nlink(inode, 2);
 709
 710         sb->s_root = d_make_root(inode);
 711         if (!sb->s_root)
 712                 return -ENOMEM;
 713
 714         ret = binderfs_binder_ctl_create(sb);
 715         if (ret)
 716                 return ret;
 717
 718         name = binder_devices_param;
 719         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 720                 strscpy(device_info.name, name, len + 1);
 721                 ret = binderfs_binder_device_create(inode, NULL, &device_info);
 722                 if (ret)
 723                         return ret;
 724                 name += len;
 725                 if (*name == ',')
 726                         name++;
 727         }
 728
 729         if (info->mount_opts.stats_mode == STATS_GLOBAL)
 730                 return init_binder_logs(sb);
 731
 732         return 0;
 733 }
 734
 735 static struct dentry *binderfs_mount(struct file_system_type *fs_type,
 736                                      int flags, const char *dev_name,
 737                                      void *data)
 738 {
 739         return mount_nodev(fs_type, flags, data, binderfs_fill_super);
 740 }
 741
 742 static void binderfs_kill_super(struct super_block *sb)
 743 {
 744         struct binderfs_info *info = sb->s_fs_info;
 745
 746         kill_litter_super(sb);
 747
 748         if (info && info->ipc_ns)
 749                 put_ipc_ns(info->ipc_ns);
 750
 751         kfree(info);
 752 }
 753
 754 static struct file_system_type binder_fs_type = {
 755         .name           = "binder",
 756         .mount          = binderfs_mount,
 757         .kill_sb        = binderfs_kill_super,
 758         .fs_flags       = FS_USERNS_MOUNT,
 759 };
 760
 761 int __init init_binderfs(void)
 762 {
 763         int ret;
 764         const char *name;
 765         size_t len;
 766
 767         /* Verify that the default binderfs device names are valid. */
 768         name = binder_devices_param;
 769         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 770                 if (len > BINDERFS_MAX_NAME)
 771                         return -E2BIG;
 772                 name += len;
 773                 if (*name == ',')
 774                         name++;
 775         }
 776
 777         /* Allocate new major number for binderfs. */
 778         ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
 779                                   "binder");
 780         if (ret)
 781                 return ret;
 782
 783         ret = register_filesystem(&binder_fs_type);
 784         if (ret) {
 785                 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
 786                 return ret;
 787         }
 788
 789         return ret;
 790 }