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         refcount_set(&device->ref, 1);
 158         device->binderfs_inode = inode;
 159         device->context.binder_context_mgr_uid = INVALID_UID;
 160         device->context.name = name;
 161         device->miscdev.name = name;
 162         device->miscdev.minor = minor;
 163         mutex_init(&device->context.context_mgr_node_lock);
 164
 165         req->major = MAJOR(binderfs_dev);
 166         req->minor = minor;
 167
 168         if (userp && copy_to_user(userp, req, sizeof(*req))) {
 169                 ret = -EFAULT;
 170                 goto err;
 171         }
 172
 173         root = sb->s_root;
 174         inode_lock(d_inode(root));
 175
 176         /* look it up */
 177         dentry = lookup_one_len(name, root, name_len);
 178         if (IS_ERR(dentry)) {
 179                 inode_unlock(d_inode(root));
 180                 ret = PTR_ERR(dentry);
 181                 goto err;
 182         }
 183
 184         if (d_really_is_positive(dentry)) {
 185                 /* already exists */
 186                 dput(dentry);
 187                 inode_unlock(d_inode(root));
 188                 ret = -EEXIST;
 189                 goto err;
 190         }
 191
 192         inode->i_private = device;
 193         d_instantiate(dentry, inode);
 194         fsnotify_create(root->d_inode, dentry);
 195         inode_unlock(d_inode(root));
 196
 197         return 0;
 198
 199 err:
 200         kfree(name);
 201         kfree(device);
 202         mutex_lock(&binderfs_minors_mutex);
 203         --info->device_count;
 204         ida_free(&binderfs_minors, minor);
 205         mutex_unlock(&binderfs_minors_mutex);
 206         iput(inode);
 207
 208         return ret;
 209 }
 210
 211 /**
 212  * binderfs_ctl_ioctl - handle binder device node allocation requests
 213  *
 214  * The request handler for the binder-control device. All requests operate on
 215  * the binderfs mount the binder-control device resides in:
 216  * - BINDER_CTL_ADD
 217  *   Allocate a new binder device.
 218  *
 219  * Return: 0 on success, negative errno on failure
 220  */
 221 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
 222                              unsigned long arg)
 223 {
 224         int ret = -EINVAL;
 225         struct inode *inode = file_inode(file);
 226         struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
 227         struct binderfs_device device_req;
 228
 229         switch (cmd) {
 230         case BINDER_CTL_ADD:
 231                 ret = copy_from_user(&device_req, device, sizeof(device_req));
 232                 if (ret) {
 233                         ret = -EFAULT;
 234                         break;
 235                 }
 236
 237                 ret = binderfs_binder_device_create(inode, device, &device_req);
 238                 break;
 239         default:
 240                 break;
 241         }
 242
 243         return ret;
 244 }
 245
 246 static void binderfs_evict_inode(struct inode *inode)
 247 {
 248         struct binder_device *device = inode->i_private;
 249         struct binderfs_info *info = BINDERFS_I(inode);
 250
 251         clear_inode(inode);
 252
 253         if (!S_ISCHR(inode->i_mode) || !device)
 254                 return;
 255
 256         mutex_lock(&binderfs_minors_mutex);
 257         --info->device_count;
 258         ida_free(&binderfs_minors, device->miscdev.minor);
 259         mutex_unlock(&binderfs_minors_mutex);
 260
 261         if (refcount_dec_and_test(&device->ref)) {
 262                 kfree(device->context.name);
 263                 kfree(device);
 264         }
 265 }
 266
 267 /**
 268  * binderfs_parse_mount_opts - parse binderfs mount options
 269  * @data: options to set (can be NULL in which case defaults are used)
 270  */
 271 static int binderfs_parse_mount_opts(char *data,
 272                                      struct binderfs_mount_opts *opts)
 273 {
 274         char *p, *stats;
 275         opts->max = BINDERFS_MAX_MINOR;
 276         opts->stats_mode = STATS_NONE;
 277
 278         while ((p = strsep(&data, ",")) != NULL) {
 279                 substring_t args[MAX_OPT_ARGS];
 280                 int token;
 281                 int max_devices;
 282
 283                 if (!*p)
 284                         continue;
 285
 286                 token = match_token(p, tokens, args);
 287                 switch (token) {
 288                 case Opt_max:
 289                         if (match_int(&args[0], &max_devices) ||
 290                             (max_devices < 0 ||
 291                              (max_devices > BINDERFS_MAX_MINOR)))
 292                                 return -EINVAL;
 293
 294                         opts->max = max_devices;
 295                         break;
 296                 case Opt_stats_mode:
 297                         if (!capable(CAP_SYS_ADMIN))
 298                                 return -EINVAL;
 299
 300                         stats = match_strdup(&args[0]);
 301                         if (!stats)
 302                                 return -ENOMEM;
 303
 304                         if (strcmp(stats, "global") != 0) {
 305                                 kfree(stats);
 306                                 return -EINVAL;
 307                         }
 308
 309                         opts->stats_mode = STATS_GLOBAL;
 310                         kfree(stats);
 311                         break;
 312                 default:
 313                         pr_err("Invalid mount options\n");
 314                         return -EINVAL;
 315                 }
 316         }
 317
 318         return 0;
 319 }
 320
 321 static int binderfs_remount(struct super_block *sb, int *flags, char *data)
 322 {
 323         int prev_stats_mode, ret;
 324         struct binderfs_info *info = sb->s_fs_info;
 325
 326         prev_stats_mode = info->mount_opts.stats_mode;
 327         ret = binderfs_parse_mount_opts(data, &info->mount_opts);
 328         if (ret)
 329                 return ret;
 330
 331         if (prev_stats_mode != info->mount_opts.stats_mode) {
 332                 pr_err("Binderfs stats mode cannot be changed during a remount\n");
 333                 info->mount_opts.stats_mode = prev_stats_mode;
 334                 return -EINVAL;
 335         }
 336
 337         return 0;
 338 }
 339
 340 static int binderfs_show_mount_opts(struct seq_file *seq, struct dentry *root)
 341 {
 342         struct binderfs_info *info;
 343
 344         info = root->d_sb->s_fs_info;
 345         if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
 346                 seq_printf(seq, ",max=%d", info->mount_opts.max);
 347         if (info->mount_opts.stats_mode == STATS_GLOBAL)
 348                 seq_printf(seq, ",stats=global");
 349
 350         return 0;
 351 }
 352
 353 static const struct super_operations binderfs_super_ops = {
 354         .evict_inode    = binderfs_evict_inode,
 355         .remount_fs     = binderfs_remount,
 356         .show_options   = binderfs_show_mount_opts,
 357         .statfs         = simple_statfs,
 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         return info->control_dentry == dentry;
 364 }
 365
 366 static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 367                            struct inode *new_dir, struct dentry *new_dentry,
 368                            unsigned int flags)
 369 {
 370         if (is_binderfs_control_device(old_dentry) ||
 371             is_binderfs_control_device(new_dentry))
 372                 return -EPERM;
 373
 374         return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
 375 }
 376
 377 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
 378 {
 379         if (is_binderfs_control_device(dentry))
 380                 return -EPERM;
 381
 382         return simple_unlink(dir, dentry);
 383 }
 384
 385 static const struct file_operations binder_ctl_fops = {
 386         .owner          = THIS_MODULE,
 387         .open           = nonseekable_open,
 388         .unlocked_ioctl = binder_ctl_ioctl,
 389         .compat_ioctl   = binder_ctl_ioctl,
 390         .llseek         = noop_llseek,
 391 };
 392
 393 /**
 394  * binderfs_binder_ctl_create - create a new binder-control device
 395  * @sb: super block of the binderfs mount
 396  *
 397  * This function creates a new binder-control device node in the binderfs mount
 398  * referred to by @sb.
 399  *
 400  * Return: 0 on success, negative errno on failure
 401  */
 402 static int binderfs_binder_ctl_create(struct super_block *sb)
 403 {
 404         int minor, ret;
 405         struct dentry *dentry;
 406         struct binder_device *device;
 407         struct inode *inode = NULL;
 408         struct dentry *root = sb->s_root;
 409         struct binderfs_info *info = sb->s_fs_info;
 410 #if defined(CONFIG_IPC_NS)
 411         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 412 #else
 413         bool use_reserve = true;
 414 #endif
 415
 416         device = kzalloc(sizeof(*device), GFP_KERNEL);
 417         if (!device)
 418                 return -ENOMEM;
 419
 420         /* If we have already created a binder-control node, return. */
 421         if (info->control_dentry) {
 422                 ret = 0;
 423                 goto out;
 424         }
 425
 426         ret = -ENOMEM;
 427         inode = new_inode(sb);
 428         if (!inode)
 429                 goto out;
 430
 431         /* Reserve a new minor number for the new device. */
 432         mutex_lock(&binderfs_minors_mutex);
 433         minor = ida_alloc_max(&binderfs_minors,
 434                               use_reserve ? BINDERFS_MAX_MINOR :
 435                                             BINDERFS_MAX_MINOR_CAPPED,
 436                               GFP_KERNEL);
 437         mutex_unlock(&binderfs_minors_mutex);
 438         if (minor < 0) {
 439                 ret = minor;
 440                 goto out;
 441         }
 442
 443         inode->i_ino = SECOND_INODE;
 444         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 445         init_special_inode(inode, S_IFCHR | 0600,
 446                            MKDEV(MAJOR(binderfs_dev), minor));
 447         inode->i_fop = &binder_ctl_fops;
 448         inode->i_uid = info->root_uid;
 449         inode->i_gid = info->root_gid;
 450
 451         device->binderfs_inode = inode;
 452         device->miscdev.minor = minor;
 453
 454         dentry = d_alloc_name(root, "binder-control");
 455         if (!dentry)
 456                 goto out;
 457
 458         inode->i_private = device;
 459         info->control_dentry = dentry;
 460         d_add(dentry, inode);
 461
 462         return 0;
 463
 464 out:
 465         kfree(device);
 466         iput(inode);
 467
 468         return ret;
 469 }
 470
 471 static const struct inode_operations binderfs_dir_inode_operations = {
 472         .lookup = simple_lookup,
 473         .rename = binderfs_rename,
 474         .unlink = binderfs_unlink,
 475 };
 476
 477 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
 478 {
 479         struct inode *ret;
 480
 481         ret = new_inode(sb);
 482         if (ret) {
 483                 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
 484                 ret->i_mode = mode;
 485                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 486         }
 487         return ret;
 488 }
 489
 490 static struct dentry *binderfs_create_dentry(struct dentry *parent,
 491                                              const char *name)
 492 {
 493         struct dentry *dentry;
 494
 495         dentry = lookup_one_len(name, parent, strlen(name));
 496         if (IS_ERR(dentry))
 497                 return dentry;
 498
 499         /* Return error if the file/dir already exists. */
 500         if (d_really_is_positive(dentry)) {
 501                 dput(dentry);
 502                 return ERR_PTR(-EEXIST);
 503         }
 504
 505         return dentry;
 506 }
 507
 508 void binderfs_remove_file(struct dentry *dentry)
 509 {
 510         struct inode *parent_inode;
 511
 512         parent_inode = d_inode(dentry->d_parent);
 513         inode_lock(parent_inode);
 514         if (simple_positive(dentry)) {
 515                 dget(dentry);
 516                 simple_unlink(parent_inode, dentry);
 517                 d_delete(dentry);
 518                 dput(dentry);
 519         }
 520         inode_unlock(parent_inode);
 521 }
 522
 523 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
 524                                     const struct file_operations *fops,
 525                                     void *data)
 526 {
 527         struct dentry *dentry;
 528         struct inode *new_inode, *parent_inode;
 529         struct super_block *sb;
 530
 531         parent_inode = d_inode(parent);
 532         inode_lock(parent_inode);
 533
 534         dentry = binderfs_create_dentry(parent, name);
 535         if (IS_ERR(dentry))
 536                 goto out;
 537
 538         sb = parent_inode->i_sb;
 539         new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
 540         if (!new_inode) {
 541                 dput(dentry);
 542                 dentry = ERR_PTR(-ENOMEM);
 543                 goto out;
 544         }
 545
 546         new_inode->i_fop = fops;
 547         new_inode->i_private = data;
 548         d_instantiate(dentry, new_inode);
 549         fsnotify_create(parent_inode, dentry);
 550
 551 out:
 552         inode_unlock(parent_inode);
 553         return dentry;
 554 }
 555
 556 static struct dentry *binderfs_create_dir(struct dentry *parent,
 557                                           const char *name)
 558 {
 559         struct dentry *dentry;
 560         struct inode *new_inode, *parent_inode;
 561         struct super_block *sb;
 562
 563         parent_inode = d_inode(parent);
 564         inode_lock(parent_inode);
 565
 566         dentry = binderfs_create_dentry(parent, name);
 567         if (IS_ERR(dentry))
 568                 goto out;
 569
 570         sb = parent_inode->i_sb;
 571         new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
 572         if (!new_inode) {
 573                 dput(dentry);
 574                 dentry = ERR_PTR(-ENOMEM);
 575                 goto out;
 576         }
 577
 578         new_inode->i_fop = &simple_dir_operations;
 579         new_inode->i_op = &simple_dir_inode_operations;
 580
 581         set_nlink(new_inode, 2);
 582         d_instantiate(dentry, new_inode);
 583         inc_nlink(parent_inode);
 584         fsnotify_mkdir(parent_inode, dentry);
 585
 586 out:
 587         inode_unlock(parent_inode);
 588         return dentry;
 589 }
 590
 591 static int init_binder_logs(struct super_block *sb)
 592 {
 593         struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
 594         struct binderfs_info *info;
 595         int ret = 0;
 596
 597         binder_logs_root_dir = binderfs_create_dir(sb->s_root,
 598                                                    "binder_logs");
 599         if (IS_ERR(binder_logs_root_dir)) {
 600                 ret = PTR_ERR(binder_logs_root_dir);
 601                 goto out;
 602         }
 603
 604         dentry = binderfs_create_file(binder_logs_root_dir, "stats",
 605                                       &binder_stats_fops, NULL);
 606         if (IS_ERR(dentry)) {
 607                 ret = PTR_ERR(dentry);
 608                 goto out;
 609         }
 610
 611         dentry = binderfs_create_file(binder_logs_root_dir, "state",
 612                                       &binder_state_fops, NULL);
 613         if (IS_ERR(dentry)) {
 614                 ret = PTR_ERR(dentry);
 615                 goto out;
 616         }
 617
 618         dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
 619                                       &binder_transactions_fops, NULL);
 620         if (IS_ERR(dentry)) {
 621                 ret = PTR_ERR(dentry);
 622                 goto out;
 623         }
 624
 625         dentry = binderfs_create_file(binder_logs_root_dir,
 626                                       "transaction_log",
 627                                       &binder_transaction_log_fops,
 628                                       &binder_transaction_log);
 629         if (IS_ERR(dentry)) {
 630                 ret = PTR_ERR(dentry);
 631                 goto out;
 632         }
 633
 634         dentry = binderfs_create_file(binder_logs_root_dir,
 635                                       "failed_transaction_log",
 636                                       &binder_transaction_log_fops,
 637                                       &binder_transaction_log_failed);
 638         if (IS_ERR(dentry)) {
 639                 ret = PTR_ERR(dentry);
 640                 goto out;
 641         }
 642
 643         proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
 644         if (IS_ERR(proc_log_dir)) {
 645                 ret = PTR_ERR(proc_log_dir);
 646                 goto out;
 647         }
 648         info = sb->s_fs_info;
 649         info->proc_log_dir = proc_log_dir;
 650
 651 out:
 652         return ret;
 653 }
 654
 655 static int binderfs_fill_super(struct super_block *sb, void *data, int silent)
 656 {
 657         int ret;
 658         struct binderfs_info *info;
 659         struct inode *inode = NULL;
 660         struct binderfs_device device_info = { 0 };
 661         const char *name;
 662         size_t len;
 663
 664         sb->s_blocksize = PAGE_SIZE;
 665         sb->s_blocksize_bits = PAGE_SHIFT;
 666
 667         /*
 668          * The binderfs filesystem can be mounted by userns root in a
 669          * non-initial userns. By default such mounts have the SB_I_NODEV flag
 670          * set in s_iflags to prevent security issues where userns root can
 671          * just create random device nodes via mknod() since it owns the
 672          * filesystem mount. But binderfs does not allow to create any files
 673          * including devices nodes. The only way to create binder devices nodes
 674          * is through the binder-control device which userns root is explicitly
 675          * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
 676          * necessary and safe.
 677          */
 678         sb->s_iflags &= ~SB_I_NODEV;
 679         sb->s_iflags |= SB_I_NOEXEC;
 680         sb->s_magic = BINDERFS_SUPER_MAGIC;
 681         sb->s_op = &binderfs_super_ops;
 682         sb->s_time_gran = 1;
 683
 684         sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
 685         if (!sb->s_fs_info)
 686                 return -ENOMEM;
 687         info = sb->s_fs_info;
 688
 689         info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
 690
 691         ret = binderfs_parse_mount_opts(data, &info->mount_opts);
 692         if (ret)
 693                 return ret;
 694
 695         info->root_gid = make_kgid(sb->s_user_ns, 0);
 696         if (!gid_valid(info->root_gid))
 697                 info->root_gid = GLOBAL_ROOT_GID;
 698         info->root_uid = make_kuid(sb->s_user_ns, 0);
 699         if (!uid_valid(info->root_uid))
 700                 info->root_uid = GLOBAL_ROOT_UID;
 701
 702         inode = new_inode(sb);
 703         if (!inode)
 704                 return -ENOMEM;
 705
 706         inode->i_ino = FIRST_INODE;
 707         inode->i_fop = &simple_dir_operations;
 708         inode->i_mode = S_IFDIR | 0755;
 709         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 710         inode->i_op = &binderfs_dir_inode_operations;
 711         set_nlink(inode, 2);
 712
 713         sb->s_root = d_make_root(inode);
 714         if (!sb->s_root)
 715                 return -ENOMEM;
 716
 717         ret = binderfs_binder_ctl_create(sb);
 718         if (ret)
 719                 return ret;
 720
 721         name = binder_devices_param;
 722         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 723                 strscpy(device_info.name, name, len + 1);
 724                 ret = binderfs_binder_device_create(inode, NULL, &device_info);
 725                 if (ret)
 726                         return ret;
 727                 name += len;
 728                 if (*name == ',')
 729                         name++;
 730         }
 731
 732         if (info->mount_opts.stats_mode == STATS_GLOBAL)
 733                 return init_binder_logs(sb);
 734
 735         return 0;
 736 }
 737
 738 static struct dentry *binderfs_mount(struct file_system_type *fs_type,
 739                                      int flags, const char *dev_name,
 740                                      void *data)
 741 {
 742         return mount_nodev(fs_type, flags, data, binderfs_fill_super);
 743 }
 744
 745 static void binderfs_kill_super(struct super_block *sb)
 746 {
 747         struct binderfs_info *info = sb->s_fs_info;
 748
 749         kill_litter_super(sb);
 750
 751         if (info && info->ipc_ns)
 752                 put_ipc_ns(info->ipc_ns);
 753
 754         kfree(info);
 755 }
 756
 757 static struct file_system_type binder_fs_type = {
 758         .name           = "binder",
 759         .mount          = binderfs_mount,
 760         .kill_sb        = binderfs_kill_super,
 761         .fs_flags       = FS_USERNS_MOUNT,
 762 };
 763
 764 int __init init_binderfs(void)
 765 {
 766         int ret;
 767         const char *name;
 768         size_t len;
 769
 770         /* Verify that the default binderfs device names are valid. */
 771         name = binder_devices_param;
 772         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 773                 if (len > BINDERFS_MAX_NAME)
 774                         return -E2BIG;
 775                 name += len;
 776                 if (*name == ',')
 777                         name++;
 778         }
 779
 780         /* Allocate new major number for binderfs. */
 781         ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
 782                                   "binder");
 783         if (ret)
 784                 return ret;
 785
 786         ret = register_filesystem(&binder_fs_type);
 787         if (ret) {
 788                 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
 789                 return ret;
 790         }
 791
 792         return ret;
 793 }