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/fs_parser.h>
  22 #include <linux/radix-tree.h>
  23 #include <linux/sched.h>
  24 #include <linux/seq_file.h>
  25 #include <linux/slab.h>
  26 #include <linux/spinlock_types.h>
  27 #include <linux/stddef.h>
  28 #include <linux/string.h>
  29 #include <linux/types.h>
  30 #include <linux/uaccess.h>
  31 #include <linux/user_namespace.h>
  32 #include <linux/xarray.h>
  33 #include <uapi/asm-generic/errno-base.h>
  34 #include <uapi/linux/android/binder.h>
  35 #include <uapi/linux/android/binderfs.h>
  36
  37 #include "binder_internal.h"
  38
  39 #define FIRST_INODE 1
  40 #define SECOND_INODE 2
  41 #define INODE_OFFSET 3
  42 #define 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 binderfs_param {
  52         Opt_max,
  53         Opt_stats_mode,
  54 };
  55
  56 enum binderfs_stats_mode {
  57         binderfs_stats_mode_unset,
  58         binderfs_stats_mode_global,
  59 };
  60
  61 static const struct constant_table binderfs_param_stats[] = {
  62         { "global", binderfs_stats_mode_global },
  63         {}
  64 };
  65
  66 const struct fs_parameter_spec binderfs_fs_parameters[] = {
  67         fsparam_u32("max",      Opt_max),
  68         fsparam_enum("stats",   Opt_stats_mode, binderfs_param_stats),
  69         {}
  70 };
  71
  72 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
  73 {
  74         return sb->s_fs_info;
  75 }
  76
  77 bool is_binderfs_device(const struct inode *inode)
  78 {
  79         if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
  80                 return true;
  81
  82         return false;
  83 }
  84
  85 /**
  86  * binderfs_binder_device_create - allocate inode from super block of a
  87  *                                 binderfs mount
  88  * @ref_inode: inode from wich the super block will be taken
  89  * @userp:     buffer to copy information about new device for userspace to
  90  * @req:       struct binderfs_device as copied from userspace
  91  *
  92  * This function allocates a new binder_device and reserves a new minor
  93  * number for it.
  94  * Minor numbers are limited and tracked globally in binderfs_minors. The
  95  * function will stash a struct binder_device for the specific binder
  96  * device in i_private of the inode.
  97  * It will go on to allocate a new inode from the super block of the
  98  * filesystem mount, stash a struct binder_device in its i_private field
  99  * and attach a dentry to that inode.
 100  *
 101  * Return: 0 on success, negative errno on failure
 102  */
 103 static int binderfs_binder_device_create(struct inode *ref_inode,
 104                                          struct binderfs_device __user *userp,
 105                                          struct binderfs_device *req)
 106 {
 107         int minor, ret;
 108         struct dentry *dentry, *root;
 109         struct binder_device *device;
 110         char *name = NULL;
 111         size_t name_len;
 112         struct inode *inode = NULL;
 113         struct super_block *sb = ref_inode->i_sb;
 114         struct binderfs_info *info = sb->s_fs_info;
 115 #if defined(CONFIG_IPC_NS)
 116         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 117 #else
 118         bool use_reserve = true;
 119 #endif
 120
 121         /* Reserve new minor number for the new device. */
 122         mutex_lock(&binderfs_minors_mutex);
 123         if (++info->device_count <= info->mount_opts.max)
 124                 minor = ida_alloc_max(&binderfs_minors,
 125                                       use_reserve ? BINDERFS_MAX_MINOR :
 126                                                     BINDERFS_MAX_MINOR_CAPPED,
 127                                       GFP_KERNEL);
 128         else
 129                 minor = -ENOSPC;
 130         if (minor < 0) {
 131                 --info->device_count;
 132                 mutex_unlock(&binderfs_minors_mutex);
 133                 return minor;
 134         }
 135         mutex_unlock(&binderfs_minors_mutex);
 136
 137         ret = -ENOMEM;
 138         device = kzalloc(sizeof(*device), GFP_KERNEL);
 139         if (!device)
 140                 goto err;
 141
 142         inode = new_inode(sb);
 143         if (!inode)
 144                 goto err;
 145
 146         inode->i_ino = minor + INODE_OFFSET;
 147         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 148         init_special_inode(inode, S_IFCHR | 0600,
 149                            MKDEV(MAJOR(binderfs_dev), minor));
 150         inode->i_fop = &binder_fops;
 151         inode->i_uid = info->root_uid;
 152         inode->i_gid = info->root_gid;
 153
 154         req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
 155         name_len = strlen(req->name);
 156         /* Make sure to include terminating NUL byte */
 157         name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
 158         if (!name)
 159                 goto err;
 160
 161         refcount_set(&device->ref, 1);
 162         device->binderfs_inode = inode;
 163         device->context.binder_context_mgr_uid = INVALID_UID;
 164         device->context.name = name;
 165         device->miscdev.name = name;
 166         device->miscdev.minor = minor;
 167         mutex_init(&device->context.context_mgr_node_lock);
 168
 169         req->major = MAJOR(binderfs_dev);
 170         req->minor = minor;
 171
 172         if (userp && copy_to_user(userp, req, sizeof(*req))) {
 173                 ret = -EFAULT;
 174                 goto err;
 175         }
 176
 177         root = sb->s_root;
 178         inode_lock(d_inode(root));
 179
 180         /* look it up */
 181         dentry = lookup_one_len(name, root, name_len);
 182         if (IS_ERR(dentry)) {
 183                 inode_unlock(d_inode(root));
 184                 ret = PTR_ERR(dentry);
 185                 goto err;
 186         }
 187
 188         if (d_really_is_positive(dentry)) {
 189                 /* already exists */
 190                 dput(dentry);
 191                 inode_unlock(d_inode(root));
 192                 ret = -EEXIST;
 193                 goto err;
 194         }
 195
 196         inode->i_private = device;
 197         d_instantiate(dentry, inode);
 198         fsnotify_create(root->d_inode, dentry);
 199         inode_unlock(d_inode(root));
 200
 201         return 0;
 202
 203 err:
 204         kfree(name);
 205         kfree(device);
 206         mutex_lock(&binderfs_minors_mutex);
 207         --info->device_count;
 208         ida_free(&binderfs_minors, minor);
 209         mutex_unlock(&binderfs_minors_mutex);
 210         iput(inode);
 211
 212         return ret;
 213 }
 214
 215 /**
 216  * binderfs_ctl_ioctl - handle binder device node allocation requests
 217  *
 218  * The request handler for the binder-control device. All requests operate on
 219  * the binderfs mount the binder-control device resides in:
 220  * - BINDER_CTL_ADD
 221  *   Allocate a new binder device.
 222  *
 223  * Return: 0 on success, negative errno on failure
 224  */
 225 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
 226                              unsigned long arg)
 227 {
 228         int ret = -EINVAL;
 229         struct inode *inode = file_inode(file);
 230         struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
 231         struct binderfs_device device_req;
 232
 233         switch (cmd) {
 234         case BINDER_CTL_ADD:
 235                 ret = copy_from_user(&device_req, device, sizeof(device_req));
 236                 if (ret) {
 237                         ret = -EFAULT;
 238                         break;
 239                 }
 240
 241                 ret = binderfs_binder_device_create(inode, device, &device_req);
 242                 break;
 243         default:
 244                 break;
 245         }
 246
 247         return ret;
 248 }
 249
 250 static void binderfs_evict_inode(struct inode *inode)
 251 {
 252         struct binder_device *device = inode->i_private;
 253         struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
 254
 255         clear_inode(inode);
 256
 257         if (!S_ISCHR(inode->i_mode) || !device)
 258                 return;
 259
 260         mutex_lock(&binderfs_minors_mutex);
 261         --info->device_count;
 262         ida_free(&binderfs_minors, device->miscdev.minor);
 263         mutex_unlock(&binderfs_minors_mutex);
 264
 265         if (refcount_dec_and_test(&device->ref)) {
 266                 kfree(device->context.name);
 267                 kfree(device);
 268         }
 269 }
 270
 271 static int binderfs_fs_context_parse_param(struct fs_context *fc,
 272                                            struct fs_parameter *param)
 273 {
 274         int opt;
 275         struct binderfs_mount_opts *ctx = fc->fs_private;
 276         struct fs_parse_result result;
 277
 278         opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
 279         if (opt < 0)
 280                 return opt;
 281
 282         switch (opt) {
 283         case Opt_max:
 284                 if (result.uint_32 > BINDERFS_MAX_MINOR)
 285                         return invalfc(fc, "Bad value for '%s'", param->key);
 286
 287                 ctx->max = result.uint_32;
 288                 break;
 289         case Opt_stats_mode:
 290                 if (!capable(CAP_SYS_ADMIN))
 291                         return -EPERM;
 292
 293                 ctx->stats_mode = result.uint_32;
 294                 break;
 295         default:
 296                 return invalfc(fc, "Unsupported parameter '%s'", param->key);
 297         }
 298
 299         return 0;
 300 }
 301
 302 static int binderfs_fs_context_reconfigure(struct fs_context *fc)
 303 {
 304         struct binderfs_mount_opts *ctx = fc->fs_private;
 305         struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
 306
 307         if (info->mount_opts.stats_mode != ctx->stats_mode)
 308                 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
 309
 310         info->mount_opts.stats_mode = ctx->stats_mode;
 311         info->mount_opts.max = ctx->max;
 312         return 0;
 313 }
 314
 315 static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
 316 {
 317         struct binderfs_info *info = BINDERFS_SB(root->d_sb);
 318
 319         if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
 320                 seq_printf(seq, ",max=%d", info->mount_opts.max);
 321
 322         switch (info->mount_opts.stats_mode) {
 323         case binderfs_stats_mode_unset:
 324                 break;
 325         case binderfs_stats_mode_global:
 326                 seq_printf(seq, ",stats=global");
 327                 break;
 328         }
 329
 330         return 0;
 331 }
 332
 333 static void binderfs_put_super(struct super_block *sb)
 334 {
 335         struct binderfs_info *info = sb->s_fs_info;
 336
 337         if (info && info->ipc_ns)
 338                 put_ipc_ns(info->ipc_ns);
 339
 340         kfree(info);
 341         sb->s_fs_info = NULL;
 342 }
 343
 344 static const struct super_operations binderfs_super_ops = {
 345         .evict_inode    = binderfs_evict_inode,
 346         .show_options   = binderfs_show_options,
 347         .statfs         = simple_statfs,
 348         .put_super      = binderfs_put_super,
 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         return info->control_dentry == dentry;
 355 }
 356
 357 static int binderfs_rename(struct inode *old_dir, struct dentry *old_dentry,
 358                            struct inode *new_dir, struct dentry *new_dentry,
 359                            unsigned int flags)
 360 {
 361         if (is_binderfs_control_device(old_dentry) ||
 362             is_binderfs_control_device(new_dentry))
 363                 return -EPERM;
 364
 365         return simple_rename(old_dir, old_dentry, new_dir, new_dentry, flags);
 366 }
 367
 368 static int binderfs_unlink(struct inode *dir, struct dentry *dentry)
 369 {
 370         if (is_binderfs_control_device(dentry))
 371                 return -EPERM;
 372
 373         return simple_unlink(dir, dentry);
 374 }
 375
 376 static const struct file_operations binder_ctl_fops = {
 377         .owner          = THIS_MODULE,
 378         .open           = nonseekable_open,
 379         .unlocked_ioctl = binder_ctl_ioctl,
 380         .compat_ioctl   = binder_ctl_ioctl,
 381         .llseek         = noop_llseek,
 382 };
 383
 384 /**
 385  * binderfs_binder_ctl_create - create a new binder-control device
 386  * @sb: super block of the binderfs mount
 387  *
 388  * This function creates a new binder-control device node in the binderfs mount
 389  * referred to by @sb.
 390  *
 391  * Return: 0 on success, negative errno on failure
 392  */
 393 static int binderfs_binder_ctl_create(struct super_block *sb)
 394 {
 395         int minor, ret;
 396         struct dentry *dentry;
 397         struct binder_device *device;
 398         struct inode *inode = NULL;
 399         struct dentry *root = sb->s_root;
 400         struct binderfs_info *info = sb->s_fs_info;
 401 #if defined(CONFIG_IPC_NS)
 402         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 403 #else
 404         bool use_reserve = true;
 405 #endif
 406
 407         device = kzalloc(sizeof(*device), GFP_KERNEL);
 408         if (!device)
 409                 return -ENOMEM;
 410
 411         /* If we have already created a binder-control node, return. */
 412         if (info->control_dentry) {
 413                 ret = 0;
 414                 goto out;
 415         }
 416
 417         ret = -ENOMEM;
 418         inode = new_inode(sb);
 419         if (!inode)
 420                 goto out;
 421
 422         /* Reserve a new minor number for the new device. */
 423         mutex_lock(&binderfs_minors_mutex);
 424         minor = ida_alloc_max(&binderfs_minors,
 425                               use_reserve ? BINDERFS_MAX_MINOR :
 426                                             BINDERFS_MAX_MINOR_CAPPED,
 427                               GFP_KERNEL);
 428         mutex_unlock(&binderfs_minors_mutex);
 429         if (minor < 0) {
 430                 ret = minor;
 431                 goto out;
 432         }
 433
 434         inode->i_ino = SECOND_INODE;
 435         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 436         init_special_inode(inode, S_IFCHR | 0600,
 437                            MKDEV(MAJOR(binderfs_dev), minor));
 438         inode->i_fop = &binder_ctl_fops;
 439         inode->i_uid = info->root_uid;
 440         inode->i_gid = info->root_gid;
 441
 442         refcount_set(&device->ref, 1);
 443         device->binderfs_inode = inode;
 444         device->miscdev.minor = minor;
 445
 446         dentry = d_alloc_name(root, "binder-control");
 447         if (!dentry)
 448                 goto out;
 449
 450         inode->i_private = device;
 451         info->control_dentry = dentry;
 452         d_add(dentry, inode);
 453
 454         return 0;
 455
 456 out:
 457         kfree(device);
 458         iput(inode);
 459
 460         return ret;
 461 }
 462
 463 static const struct inode_operations binderfs_dir_inode_operations = {
 464         .lookup = simple_lookup,
 465         .rename = binderfs_rename,
 466         .unlink = binderfs_unlink,
 467 };
 468
 469 static struct inode *binderfs_make_inode(struct super_block *sb, int mode)
 470 {
 471         struct inode *ret;
 472
 473         ret = new_inode(sb);
 474         if (ret) {
 475                 ret->i_ino = iunique(sb, BINDERFS_MAX_MINOR + INODE_OFFSET);
 476                 ret->i_mode = mode;
 477                 ret->i_atime = ret->i_mtime = ret->i_ctime = current_time(ret);
 478         }
 479         return ret;
 480 }
 481
 482 static struct dentry *binderfs_create_dentry(struct dentry *parent,
 483                                              const char *name)
 484 {
 485         struct dentry *dentry;
 486
 487         dentry = lookup_one_len(name, parent, strlen(name));
 488         if (IS_ERR(dentry))
 489                 return dentry;
 490
 491         /* Return error if the file/dir already exists. */
 492         if (d_really_is_positive(dentry)) {
 493                 dput(dentry);
 494                 return ERR_PTR(-EEXIST);
 495         }
 496
 497         return dentry;
 498 }
 499
 500 void binderfs_remove_file(struct dentry *dentry)
 501 {
 502         struct inode *parent_inode;
 503
 504         parent_inode = d_inode(dentry->d_parent);
 505         inode_lock(parent_inode);
 506         if (simple_positive(dentry)) {
 507                 dget(dentry);
 508                 simple_unlink(parent_inode, dentry);
 509                 d_delete(dentry);
 510                 dput(dentry);
 511         }
 512         inode_unlock(parent_inode);
 513 }
 514
 515 struct dentry *binderfs_create_file(struct dentry *parent, const char *name,
 516                                     const struct file_operations *fops,
 517                                     void *data)
 518 {
 519         struct dentry *dentry;
 520         struct inode *new_inode, *parent_inode;
 521         struct super_block *sb;
 522
 523         parent_inode = d_inode(parent);
 524         inode_lock(parent_inode);
 525
 526         dentry = binderfs_create_dentry(parent, name);
 527         if (IS_ERR(dentry))
 528                 goto out;
 529
 530         sb = parent_inode->i_sb;
 531         new_inode = binderfs_make_inode(sb, S_IFREG | 0444);
 532         if (!new_inode) {
 533                 dput(dentry);
 534                 dentry = ERR_PTR(-ENOMEM);
 535                 goto out;
 536         }
 537
 538         new_inode->i_fop = fops;
 539         new_inode->i_private = data;
 540         d_instantiate(dentry, new_inode);
 541         fsnotify_create(parent_inode, dentry);
 542
 543 out:
 544         inode_unlock(parent_inode);
 545         return dentry;
 546 }
 547
 548 static struct dentry *binderfs_create_dir(struct dentry *parent,
 549                                           const char *name)
 550 {
 551         struct dentry *dentry;
 552         struct inode *new_inode, *parent_inode;
 553         struct super_block *sb;
 554
 555         parent_inode = d_inode(parent);
 556         inode_lock(parent_inode);
 557
 558         dentry = binderfs_create_dentry(parent, name);
 559         if (IS_ERR(dentry))
 560                 goto out;
 561
 562         sb = parent_inode->i_sb;
 563         new_inode = binderfs_make_inode(sb, S_IFDIR | 0755);
 564         if (!new_inode) {
 565                 dput(dentry);
 566                 dentry = ERR_PTR(-ENOMEM);
 567                 goto out;
 568         }
 569
 570         new_inode->i_fop = &simple_dir_operations;
 571         new_inode->i_op = &simple_dir_inode_operations;
 572
 573         set_nlink(new_inode, 2);
 574         d_instantiate(dentry, new_inode);
 575         inc_nlink(parent_inode);
 576         fsnotify_mkdir(parent_inode, dentry);
 577
 578 out:
 579         inode_unlock(parent_inode);
 580         return dentry;
 581 }
 582
 583 static int init_binder_logs(struct super_block *sb)
 584 {
 585         struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
 586         struct binderfs_info *info;
 587         int ret = 0;
 588
 589         binder_logs_root_dir = binderfs_create_dir(sb->s_root,
 590                                                    "binder_logs");
 591         if (IS_ERR(binder_logs_root_dir)) {
 592                 ret = PTR_ERR(binder_logs_root_dir);
 593                 goto out;
 594         }
 595
 596         dentry = binderfs_create_file(binder_logs_root_dir, "stats",
 597                                       &binder_stats_fops, NULL);
 598         if (IS_ERR(dentry)) {
 599                 ret = PTR_ERR(dentry);
 600                 goto out;
 601         }
 602
 603         dentry = binderfs_create_file(binder_logs_root_dir, "state",
 604                                       &binder_state_fops, NULL);
 605         if (IS_ERR(dentry)) {
 606                 ret = PTR_ERR(dentry);
 607                 goto out;
 608         }
 609
 610         dentry = binderfs_create_file(binder_logs_root_dir, "transactions",
 611                                       &binder_transactions_fops, NULL);
 612         if (IS_ERR(dentry)) {
 613                 ret = PTR_ERR(dentry);
 614                 goto out;
 615         }
 616
 617         dentry = binderfs_create_file(binder_logs_root_dir,
 618                                       "transaction_log",
 619                                       &binder_transaction_log_fops,
 620                                       &binder_transaction_log);
 621         if (IS_ERR(dentry)) {
 622                 ret = PTR_ERR(dentry);
 623                 goto out;
 624         }
 625
 626         dentry = binderfs_create_file(binder_logs_root_dir,
 627                                       "failed_transaction_log",
 628                                       &binder_transaction_log_fops,
 629                                       &binder_transaction_log_failed);
 630         if (IS_ERR(dentry)) {
 631                 ret = PTR_ERR(dentry);
 632                 goto out;
 633         }
 634
 635         proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
 636         if (IS_ERR(proc_log_dir)) {
 637                 ret = PTR_ERR(proc_log_dir);
 638                 goto out;
 639         }
 640         info = sb->s_fs_info;
 641         info->proc_log_dir = proc_log_dir;
 642
 643 out:
 644         return ret;
 645 }
 646
 647 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
 648 {
 649         int ret;
 650         struct binderfs_info *info;
 651         struct binderfs_mount_opts *ctx = fc->fs_private;
 652         struct inode *inode = NULL;
 653         struct binderfs_device device_info = { 0 };
 654         const char *name;
 655         size_t len;
 656
 657         sb->s_blocksize = PAGE_SIZE;
 658         sb->s_blocksize_bits = PAGE_SHIFT;
 659
 660         /*
 661          * The binderfs filesystem can be mounted by userns root in a
 662          * non-initial userns. By default such mounts have the SB_I_NODEV flag
 663          * set in s_iflags to prevent security issues where userns root can
 664          * just create random device nodes via mknod() since it owns the
 665          * filesystem mount. But binderfs does not allow to create any files
 666          * including devices nodes. The only way to create binder devices nodes
 667          * is through the binder-control device which userns root is explicitly
 668          * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
 669          * necessary and safe.
 670          */
 671         sb->s_iflags &= ~SB_I_NODEV;
 672         sb->s_iflags |= SB_I_NOEXEC;
 673         sb->s_magic = BINDERFS_SUPER_MAGIC;
 674         sb->s_op = &binderfs_super_ops;
 675         sb->s_time_gran = 1;
 676
 677         sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
 678         if (!sb->s_fs_info)
 679                 return -ENOMEM;
 680         info = sb->s_fs_info;
 681
 682         info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
 683
 684         info->root_gid = make_kgid(sb->s_user_ns, 0);
 685         if (!gid_valid(info->root_gid))
 686                 info->root_gid = GLOBAL_ROOT_GID;
 687         info->root_uid = make_kuid(sb->s_user_ns, 0);
 688         if (!uid_valid(info->root_uid))
 689                 info->root_uid = GLOBAL_ROOT_UID;
 690         info->mount_opts.max = ctx->max;
 691         info->mount_opts.stats_mode = ctx->stats_mode;
 692
 693         inode = new_inode(sb);
 694         if (!inode)
 695                 return -ENOMEM;
 696
 697         inode->i_ino = FIRST_INODE;
 698         inode->i_fop = &simple_dir_operations;
 699         inode->i_mode = S_IFDIR | 0755;
 700         inode->i_mtime = inode->i_atime = inode->i_ctime = current_time(inode);
 701         inode->i_op = &binderfs_dir_inode_operations;
 702         set_nlink(inode, 2);
 703
 704         sb->s_root = d_make_root(inode);
 705         if (!sb->s_root)
 706                 return -ENOMEM;
 707
 708         ret = binderfs_binder_ctl_create(sb);
 709         if (ret)
 710                 return ret;
 711
 712         name = binder_devices_param;
 713         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 714                 strscpy(device_info.name, name, len + 1);
 715                 ret = binderfs_binder_device_create(inode, NULL, &device_info);
 716                 if (ret)
 717                         return ret;
 718                 name += len;
 719                 if (*name == ',')
 720                         name++;
 721         }
 722
 723         if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
 724                 return init_binder_logs(sb);
 725
 726         return 0;
 727 }
 728
 729 static int binderfs_fs_context_get_tree(struct fs_context *fc)
 730 {
 731         return get_tree_nodev(fc, binderfs_fill_super);
 732 }
 733
 734 static void binderfs_fs_context_free(struct fs_context *fc)
 735 {
 736         struct binderfs_mount_opts *ctx = fc->fs_private;
 737
 738         kfree(ctx);
 739 }
 740
 741 static const struct fs_context_operations binderfs_fs_context_ops = {
 742         .free           = binderfs_fs_context_free,
 743         .get_tree       = binderfs_fs_context_get_tree,
 744         .parse_param    = binderfs_fs_context_parse_param,
 745         .reconfigure    = binderfs_fs_context_reconfigure,
 746 };
 747
 748 static int binderfs_init_fs_context(struct fs_context *fc)
 749 {
 750         struct binderfs_mount_opts *ctx = fc->fs_private;
 751
 752         ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
 753         if (!ctx)
 754                 return -ENOMEM;
 755
 756         ctx->max = BINDERFS_MAX_MINOR;
 757         ctx->stats_mode = binderfs_stats_mode_unset;
 758
 759         fc->fs_private = ctx;
 760         fc->ops = &binderfs_fs_context_ops;
 761
 762         return 0;
 763 }
 764
 765 static struct file_system_type binder_fs_type = {
 766         .name                   = "binder",
 767         .init_fs_context        = binderfs_init_fs_context,
 768         .parameters             = binderfs_fs_parameters,
 769         .kill_sb                = kill_litter_super,
 770         .fs_flags               = FS_USERNS_MOUNT,
 771 };
 772
 773 int __init init_binderfs(void)
 774 {
 775         int ret;
 776         const char *name;
 777         size_t len;
 778
 779         /* Verify that the default binderfs device names are valid. */
 780         name = binder_devices_param;
 781         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 782                 if (len > BINDERFS_MAX_NAME)
 783                         return -E2BIG;
 784                 name += len;
 785                 if (*name == ',')
 786                         name++;
 787         }
 788
 789         /* Allocate new major number for binderfs. */
 790         ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
 791                                   "binder");
 792         if (ret)
 793                 return ret;
 794
 795         ret = register_filesystem(&binder_fs_type);
 796         if (ret) {
 797                 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
 798                 return ret;
 799         }
 800
 801         return ret;
 802 }