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/sched.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/slab.h>
  25 #include <linux/spinlock_types.h>
  26 #include <linux/stddef.h>
  27 #include <linux/string.h>
  28 #include <linux/types.h>
  29 #include <linux/uaccess.h>
  30 #include <linux/user_namespace.h>
  31 #include <linux/xarray.h>
  32 #include <uapi/linux/android/binder.h>
  33 #include <uapi/linux/android/binderfs.h>
  34
  35 #include "binder_internal.h"
  36
  37 #define FIRST_INODE 1
  38 #define SECOND_INODE 2
  39 #define INODE_OFFSET 3
  40 #define BINDERFS_MAX_MINOR (1U << MINORBITS)
  41 /* Ensure that the initial ipc namespace always has devices available. */
  42 #define BINDERFS_MAX_MINOR_CAPPED (BINDERFS_MAX_MINOR - 4)
  43
  44 static dev_t binderfs_dev;
  45 static DEFINE_MUTEX(binderfs_minors_mutex);
  46 static DEFINE_IDA(binderfs_minors);
  47
  48 enum binderfs_param {
  49         Opt_max,
  50         Opt_stats_mode,
  51 };
  52
  53 enum binderfs_stats_mode {
  54         binderfs_stats_mode_unset,
  55         binderfs_stats_mode_global,
  56 };
  57
  58 struct binder_features {
  59         bool oneway_spam_detection;
  60         bool extended_error;
  61         bool freeze_notification;
  62 };
  63
  64 static const struct constant_table binderfs_param_stats[] = {
  65         { "global", binderfs_stats_mode_global },
  66         {}
  67 };
  68
  69 static const struct fs_parameter_spec binderfs_fs_parameters[] = {
  70         fsparam_u32("max",      Opt_max),
  71         fsparam_enum("stats",   Opt_stats_mode, binderfs_param_stats),
  72         {}
  73 };
  74
  75 static struct binder_features binder_features = {
  76         .oneway_spam_detection = true,
  77         .extended_error = true,
  78         .freeze_notification = true,
  79 };
  80
  81 static inline struct binderfs_info *BINDERFS_SB(const struct super_block *sb)
  82 {
  83         return sb->s_fs_info;
  84 }
  85
  86 bool is_binderfs_device(const struct inode *inode)
  87 {
  88         if (inode->i_sb->s_magic == BINDERFS_SUPER_MAGIC)
  89                 return true;
  90
  91         return false;
  92 }
  93
  94 /**
  95  * binderfs_binder_device_create - allocate inode from super block of a
  96  *                                 binderfs mount
  97  * @ref_inode: inode from which the super block will be taken
  98  * @userp:     buffer to copy information about new device for userspace to
  99  * @req:       struct binderfs_device as copied from userspace
 100  *
 101  * This function allocates a new binder_device and reserves a new minor
 102  * number for it.
 103  * Minor numbers are limited and tracked globally in binderfs_minors. The
 104  * function will stash a struct binder_device for the specific binder
 105  * device in i_private of the inode.
 106  * It will go on to allocate a new inode from the super block of the
 107  * filesystem mount, stash a struct binder_device in its i_private field
 108  * and attach a dentry to that inode.
 109  *
 110  * Return: 0 on success, negative errno on failure
 111  */
 112 static int binderfs_binder_device_create(struct inode *ref_inode,
 113                                          struct binderfs_device __user *userp,
 114                                          struct binderfs_device *req)
 115 {
 116         int minor, ret;
 117         struct dentry *dentry, *root;
 118         struct binder_device *device;
 119         char *name = NULL;
 120         size_t name_len;
 121         struct inode *inode = NULL;
 122         struct super_block *sb = ref_inode->i_sb;
 123         struct binderfs_info *info = sb->s_fs_info;
 124 #if defined(CONFIG_IPC_NS)
 125         bool use_reserve = (info->ipc_ns == &init_ipc_ns);
 126 #else
 127         bool use_reserve = true;
 128 #endif
 129
 130         /* Reserve new minor number for the new device. */
 131         mutex_lock(&binderfs_minors_mutex);
 132         if (++info->device_count <= info->mount_opts.max)
 133                 minor = ida_alloc_max(&binderfs_minors,
 134                                       use_reserve ? BINDERFS_MAX_MINOR :
 135                                                     BINDERFS_MAX_MINOR_CAPPED,
 136                                       GFP_KERNEL);
 137         else
 138                 minor = -ENOSPC;
 139         if (minor < 0) {
 140                 --info->device_count;
 141                 mutex_unlock(&binderfs_minors_mutex);
 142                 return minor;
 143         }
 144         mutex_unlock(&binderfs_minors_mutex);
 145
 146         ret = -ENOMEM;
 147         device = kzalloc(sizeof(*device), GFP_KERNEL);
 148         if (!device)
 149                 goto err;
 150
 151         inode = new_inode(sb);
 152         if (!inode)
 153                 goto err;
 154
 155         inode->i_ino = minor + INODE_OFFSET;
 156         simple_inode_init_ts(inode);
 157         init_special_inode(inode, S_IFCHR | 0600,
 158                            MKDEV(MAJOR(binderfs_dev), minor));
 159         inode->i_fop = &binder_fops;
 160         inode->i_uid = info->root_uid;
 161         inode->i_gid = info->root_gid;
 162
 163         req->name[BINDERFS_MAX_NAME] = '\0'; /* NUL-terminate */
 164         name_len = strlen(req->name);
 165         /* Make sure to include terminating NUL byte */
 166         name = kmemdup(req->name, name_len + 1, GFP_KERNEL);
 167         if (!name)
 168                 goto err;
 169
 170         refcount_set(&device->ref, 1);
 171         device->binderfs_inode = inode;
 172         device->context.binder_context_mgr_uid = INVALID_UID;
 173         device->context.name = name;
 174         device->miscdev.name = name;
 175         device->miscdev.minor = minor;
 176         mutex_init(&device->context.context_mgr_node_lock);
 177
 178         req->major = MAJOR(binderfs_dev);
 179         req->minor = minor;
 180
 181         if (userp && copy_to_user(userp, req, sizeof(*req))) {
 182                 ret = -EFAULT;
 183                 goto err;
 184         }
 185
 186         root = sb->s_root;
 187         inode_lock(d_inode(root));
 188
 189         /* look it up */
 190         dentry = lookup_one_len(name, root, name_len);
 191         if (IS_ERR(dentry)) {
 192                 inode_unlock(d_inode(root));
 193                 ret = PTR_ERR(dentry);
 194                 goto err;
 195         }
 196
 197         if (d_really_is_positive(dentry)) {
 198                 /* already exists */
 199                 dput(dentry);
 200                 inode_unlock(d_inode(root));
 201                 ret = -EEXIST;
 202                 goto err;
 203         }
 204
 205         inode->i_private = device;
 206         d_instantiate(dentry, inode);
 207         fsnotify_create(root->d_inode, dentry);
 208         inode_unlock(d_inode(root));
 209
 210         return 0;
 211
 212 err:
 213         kfree(name);
 214         kfree(device);
 215         mutex_lock(&binderfs_minors_mutex);
 216         --info->device_count;
 217         ida_free(&binderfs_minors, minor);
 218         mutex_unlock(&binderfs_minors_mutex);
 219         iput(inode);
 220
 221         return ret;
 222 }
 223
 224 /**
 225  * binder_ctl_ioctl - handle binder device node allocation requests
 226  *
 227  * The request handler for the binder-control device. All requests operate on
 228  * the binderfs mount the binder-control device resides in:
 229  * - BINDER_CTL_ADD
 230  *   Allocate a new binder device.
 231  *
 232  * Return: %0 on success, negative errno on failure.
 233  */
 234 static long binder_ctl_ioctl(struct file *file, unsigned int cmd,
 235                              unsigned long arg)
 236 {
 237         int ret = -EINVAL;
 238         struct inode *inode = file_inode(file);
 239         struct binderfs_device __user *device = (struct binderfs_device __user *)arg;
 240         struct binderfs_device device_req;
 241
 242         switch (cmd) {
 243         case BINDER_CTL_ADD:
 244                 ret = copy_from_user(&device_req, device, sizeof(device_req));
 245                 if (ret) {
 246                         ret = -EFAULT;
 247                         break;
 248                 }
 249
 250                 ret = binderfs_binder_device_create(inode, device, &device_req);
 251                 break;
 252         default:
 253                 break;
 254         }
 255
 256         return ret;
 257 }
 258
 259 static void binderfs_evict_inode(struct inode *inode)
 260 {
 261         struct binder_device *device = inode->i_private;
 262         struct binderfs_info *info = BINDERFS_SB(inode->i_sb);
 263
 264         clear_inode(inode);
 265
 266         if (!S_ISCHR(inode->i_mode) || !device)
 267                 return;
 268
 269         mutex_lock(&binderfs_minors_mutex);
 270         --info->device_count;
 271         ida_free(&binderfs_minors, device->miscdev.minor);
 272         mutex_unlock(&binderfs_minors_mutex);
 273
 274         if (refcount_dec_and_test(&device->ref)) {
 275                 kfree(device->context.name);
 276                 kfree(device);
 277         }
 278 }
 279
 280 static int binderfs_fs_context_parse_param(struct fs_context *fc,
 281                                            struct fs_parameter *param)
 282 {
 283         int opt;
 284         struct binderfs_mount_opts *ctx = fc->fs_private;
 285         struct fs_parse_result result;
 286
 287         opt = fs_parse(fc, binderfs_fs_parameters, param, &result);
 288         if (opt < 0)
 289                 return opt;
 290
 291         switch (opt) {
 292         case Opt_max:
 293                 if (result.uint_32 > BINDERFS_MAX_MINOR)
 294                         return invalfc(fc, "Bad value for '%s'", param->key);
 295
 296                 ctx->max = result.uint_32;
 297                 break;
 298         case Opt_stats_mode:
 299                 if (!capable(CAP_SYS_ADMIN))
 300                         return -EPERM;
 301
 302                 ctx->stats_mode = result.uint_32;
 303                 break;
 304         default:
 305                 return invalfc(fc, "Unsupported parameter '%s'", param->key);
 306         }
 307
 308         return 0;
 309 }
 310
 311 static int binderfs_fs_context_reconfigure(struct fs_context *fc)
 312 {
 313         struct binderfs_mount_opts *ctx = fc->fs_private;
 314         struct binderfs_info *info = BINDERFS_SB(fc->root->d_sb);
 315
 316         if (info->mount_opts.stats_mode != ctx->stats_mode)
 317                 return invalfc(fc, "Binderfs stats mode cannot be changed during a remount");
 318
 319         info->mount_opts.stats_mode = ctx->stats_mode;
 320         info->mount_opts.max = ctx->max;
 321         return 0;
 322 }
 323
 324 static int binderfs_show_options(struct seq_file *seq, struct dentry *root)
 325 {
 326         struct binderfs_info *info = BINDERFS_SB(root->d_sb);
 327
 328         if (info->mount_opts.max <= BINDERFS_MAX_MINOR)
 329                 seq_printf(seq, ",max=%d", info->mount_opts.max);
 330
 331         switch (info->mount_opts.stats_mode) {
 332         case binderfs_stats_mode_unset:
 333                 break;
 334         case binderfs_stats_mode_global:
 335                 seq_printf(seq, ",stats=global");
 336                 break;
 337         }
 338
 339         return 0;
 340 }
 341
 342 static const struct super_operations binderfs_super_ops = {
 343         .evict_inode    = binderfs_evict_inode,
 344         .show_options   = binderfs_show_options,
 345         .statfs         = simple_statfs,
 346 };
 347
 348 static inline bool is_binderfs_control_device(const struct dentry *dentry)
 349 {
 350         struct binderfs_info *info = dentry->d_sb->s_fs_info;
 351
 352         return info->control_dentry == dentry;
 353 }
 354
 355 static int binderfs_rename(struct mnt_idmap *idmap,
 356                            struct inode *old_dir, struct dentry *old_dentry,
 357                            struct inode *new_dir, struct dentry *new_dentry,
 358                            unsigned int flags)
 359 {
 360         if (is_binderfs_control_device(old_dentry) ||
 361             is_binderfs_control_device(new_dentry))
 362                 return -EPERM;
 363
 364         return simple_rename(idmap, old_dir, old_dentry, new_dir,
 365                              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         simple_inode_init_ts(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                 simple_inode_init_ts(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 binder_features_show(struct seq_file *m, void *unused)
 584 {
 585         bool *feature = m->private;
 586
 587         seq_printf(m, "%d\n", *feature);
 588
 589         return 0;
 590 }
 591 DEFINE_SHOW_ATTRIBUTE(binder_features);
 592
 593 static int init_binder_features(struct super_block *sb)
 594 {
 595         struct dentry *dentry, *dir;
 596
 597         dir = binderfs_create_dir(sb->s_root, "features");
 598         if (IS_ERR(dir))
 599                 return PTR_ERR(dir);
 600
 601         dentry = binderfs_create_file(dir, "oneway_spam_detection",
 602                                       &binder_features_fops,
 603                                       &binder_features.oneway_spam_detection);
 604         if (IS_ERR(dentry))
 605                 return PTR_ERR(dentry);
 606
 607         dentry = binderfs_create_file(dir, "extended_error",
 608                                       &binder_features_fops,
 609                                       &binder_features.extended_error);
 610         if (IS_ERR(dentry))
 611                 return PTR_ERR(dentry);
 612
 613         dentry = binderfs_create_file(dir, "freeze_notification",
 614                                       &binder_features_fops,
 615                                       &binder_features.freeze_notification);
 616         if (IS_ERR(dentry))
 617                 return PTR_ERR(dentry);
 618
 619         return 0;
 620 }
 621
 622 static int init_binder_logs(struct super_block *sb)
 623 {
 624         struct dentry *binder_logs_root_dir, *dentry, *proc_log_dir;
 625         const struct binder_debugfs_entry *db_entry;
 626         struct binderfs_info *info;
 627         int ret = 0;
 628
 629         binder_logs_root_dir = binderfs_create_dir(sb->s_root,
 630                                                    "binder_logs");
 631         if (IS_ERR(binder_logs_root_dir)) {
 632                 ret = PTR_ERR(binder_logs_root_dir);
 633                 goto out;
 634         }
 635
 636         binder_for_each_debugfs_entry(db_entry) {
 637                 dentry = binderfs_create_file(binder_logs_root_dir,
 638                                               db_entry->name,
 639                                               db_entry->fops,
 640                                               db_entry->data);
 641                 if (IS_ERR(dentry)) {
 642                         ret = PTR_ERR(dentry);
 643                         goto out;
 644                 }
 645         }
 646
 647         proc_log_dir = binderfs_create_dir(binder_logs_root_dir, "proc");
 648         if (IS_ERR(proc_log_dir)) {
 649                 ret = PTR_ERR(proc_log_dir);
 650                 goto out;
 651         }
 652         info = sb->s_fs_info;
 653         info->proc_log_dir = proc_log_dir;
 654
 655 out:
 656         return ret;
 657 }
 658
 659 static int binderfs_fill_super(struct super_block *sb, struct fs_context *fc)
 660 {
 661         int ret;
 662         struct binderfs_info *info;
 663         struct binderfs_mount_opts *ctx = fc->fs_private;
 664         struct inode *inode = NULL;
 665         struct binderfs_device device_info = {};
 666         const char *name;
 667         size_t len;
 668
 669         sb->s_blocksize = PAGE_SIZE;
 670         sb->s_blocksize_bits = PAGE_SHIFT;
 671
 672         /*
 673          * The binderfs filesystem can be mounted by userns root in a
 674          * non-initial userns. By default such mounts have the SB_I_NODEV flag
 675          * set in s_iflags to prevent security issues where userns root can
 676          * just create random device nodes via mknod() since it owns the
 677          * filesystem mount. But binderfs does not allow to create any files
 678          * including devices nodes. The only way to create binder devices nodes
 679          * is through the binder-control device which userns root is explicitly
 680          * allowed to do. So removing the SB_I_NODEV flag from s_iflags is both
 681          * necessary and safe.
 682          */
 683         sb->s_iflags &= ~SB_I_NODEV;
 684         sb->s_iflags |= SB_I_NOEXEC;
 685         sb->s_magic = BINDERFS_SUPER_MAGIC;
 686         sb->s_op = &binderfs_super_ops;
 687         sb->s_time_gran = 1;
 688
 689         sb->s_fs_info = kzalloc(sizeof(struct binderfs_info), GFP_KERNEL);
 690         if (!sb->s_fs_info)
 691                 return -ENOMEM;
 692         info = sb->s_fs_info;
 693
 694         info->ipc_ns = get_ipc_ns(current->nsproxy->ipc_ns);
 695
 696         info->root_gid = make_kgid(sb->s_user_ns, 0);
 697         if (!gid_valid(info->root_gid))
 698                 info->root_gid = GLOBAL_ROOT_GID;
 699         info->root_uid = make_kuid(sb->s_user_ns, 0);
 700         if (!uid_valid(info->root_uid))
 701                 info->root_uid = GLOBAL_ROOT_UID;
 702         info->mount_opts.max = ctx->max;
 703         info->mount_opts.stats_mode = ctx->stats_mode;
 704
 705         inode = new_inode(sb);
 706         if (!inode)
 707                 return -ENOMEM;
 708
 709         inode->i_ino = FIRST_INODE;
 710         inode->i_fop = &simple_dir_operations;
 711         inode->i_mode = S_IFDIR | 0755;
 712         simple_inode_init_ts(inode);
 713         inode->i_op = &binderfs_dir_inode_operations;
 714         set_nlink(inode, 2);
 715
 716         sb->s_root = d_make_root(inode);
 717         if (!sb->s_root)
 718                 return -ENOMEM;
 719
 720         ret = binderfs_binder_ctl_create(sb);
 721         if (ret)
 722                 return ret;
 723
 724         name = binder_devices_param;
 725         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 726                 strscpy(device_info.name, name, len + 1);
 727                 ret = binderfs_binder_device_create(inode, NULL, &device_info);
 728                 if (ret)
 729                         return ret;
 730                 name += len;
 731                 if (*name == ',')
 732                         name++;
 733         }
 734
 735         ret = init_binder_features(sb);
 736         if (ret)
 737                 return ret;
 738
 739         if (info->mount_opts.stats_mode == binderfs_stats_mode_global)
 740                 return init_binder_logs(sb);
 741
 742         return 0;
 743 }
 744
 745 static int binderfs_fs_context_get_tree(struct fs_context *fc)
 746 {
 747         return get_tree_nodev(fc, binderfs_fill_super);
 748 }
 749
 750 static void binderfs_fs_context_free(struct fs_context *fc)
 751 {
 752         struct binderfs_mount_opts *ctx = fc->fs_private;
 753
 754         kfree(ctx);
 755 }
 756
 757 static const struct fs_context_operations binderfs_fs_context_ops = {
 758         .free           = binderfs_fs_context_free,
 759         .get_tree       = binderfs_fs_context_get_tree,
 760         .parse_param    = binderfs_fs_context_parse_param,
 761         .reconfigure    = binderfs_fs_context_reconfigure,
 762 };
 763
 764 static int binderfs_init_fs_context(struct fs_context *fc)
 765 {
 766         struct binderfs_mount_opts *ctx;
 767
 768         ctx = kzalloc(sizeof(struct binderfs_mount_opts), GFP_KERNEL);
 769         if (!ctx)
 770                 return -ENOMEM;
 771
 772         ctx->max = BINDERFS_MAX_MINOR;
 773         ctx->stats_mode = binderfs_stats_mode_unset;
 774
 775         fc->fs_private = ctx;
 776         fc->ops = &binderfs_fs_context_ops;
 777
 778         return 0;
 779 }
 780
 781 static void binderfs_kill_super(struct super_block *sb)
 782 {
 783         struct binderfs_info *info = sb->s_fs_info;
 784
 785         /*
 786          * During inode eviction struct binderfs_info is needed.
 787          * So first wipe the super_block then free struct binderfs_info.
 788          */
 789         kill_litter_super(sb);
 790
 791         if (info && info->ipc_ns)
 792                 put_ipc_ns(info->ipc_ns);
 793
 794         kfree(info);
 795 }
 796
 797 static struct file_system_type binder_fs_type = {
 798         .name                   = "binder",
 799         .init_fs_context        = binderfs_init_fs_context,
 800         .parameters             = binderfs_fs_parameters,
 801         .kill_sb                = binderfs_kill_super,
 802         .fs_flags               = FS_USERNS_MOUNT,
 803 };
 804
 805 int __init init_binderfs(void)
 806 {
 807         int ret;
 808         const char *name;
 809         size_t len;
 810
 811         /* Verify that the default binderfs device names are valid. */
 812         name = binder_devices_param;
 813         for (len = strcspn(name, ","); len > 0; len = strcspn(name, ",")) {
 814                 if (len > BINDERFS_MAX_NAME)
 815                         return -E2BIG;
 816                 name += len;
 817                 if (*name == ',')
 818                         name++;
 819         }
 820
 821         /* Allocate new major number for binderfs. */
 822         ret = alloc_chrdev_region(&binderfs_dev, 0, BINDERFS_MAX_MINOR,
 823                                   "binder");
 824         if (ret)
 825                 return ret;
 826
 827         ret = register_filesystem(&binder_fs_type);
 828         if (ret) {
 829                 unregister_chrdev_region(binderfs_dev, BINDERFS_MAX_MINOR);
 830                 return ret;
 831         }
 832
 833         return ret;
 834 }