fs/vboxsf/super.c

   1 // SPDX-License-Identifier: MIT
   2 /*
   3  * VirtualBox Guest Shared Folders support: Virtual File System.
   4  *
   5  * Module initialization/finalization
   6  * File system registration/deregistration
   7  * Superblock reading
   8  * Few utility functions
   9  *
  10  * Copyright (C) 2006-2018 Oracle Corporation
  11  */
  12
  13 #include <linux/idr.h>
  14 #include <linux/fs_parser.h>
  15 #include <linux/magic.h>
  16 #include <linux/module.h>
  17 #include <linux/nls.h>
  18 #include <linux/statfs.h>
  19 #include <linux/vbox_utils.h>
  20 #include "vfsmod.h"
  21
  22 #define VBOXSF_SUPER_MAGIC 0x786f4256 /* 'VBox' little endian */
  23
  24 #define VBSF_MOUNT_SIGNATURE_BYTE_0 ('\000')
  25 #define VBSF_MOUNT_SIGNATURE_BYTE_1 ('\377')
  26 #define VBSF_MOUNT_SIGNATURE_BYTE_2 ('\376')
  27 #define VBSF_MOUNT_SIGNATURE_BYTE_3 ('\375')
  28
  29 static int follow_symlinks;
  30 module_param(follow_symlinks, int, 0444);
  31 MODULE_PARM_DESC(follow_symlinks,
  32                  "Let host resolve symlinks rather than showing them");
  33
  34 static DEFINE_IDA(vboxsf_bdi_ida);
  35 static DEFINE_MUTEX(vboxsf_setup_mutex);
  36 static bool vboxsf_setup_done;
  37 static struct super_operations vboxsf_super_ops; /* forward declaration */
  38 static struct kmem_cache *vboxsf_inode_cachep;
  39
  40 static char * const vboxsf_default_nls = CONFIG_NLS_DEFAULT;
  41
  42 enum  { opt_nls, opt_uid, opt_gid, opt_ttl, opt_dmode, opt_fmode,
  43         opt_dmask, opt_fmask };
  44
  45 static const struct fs_parameter_spec vboxsf_fs_parameters[] = {
  46         fsparam_string  ("nls",         opt_nls),
  47         fsparam_u32     ("uid",         opt_uid),
  48         fsparam_u32     ("gid",         opt_gid),
  49         fsparam_u32     ("ttl",         opt_ttl),
  50         fsparam_u32oct  ("dmode",       opt_dmode),
  51         fsparam_u32oct  ("fmode",       opt_fmode),
  52         fsparam_u32oct  ("dmask",       opt_dmask),
  53         fsparam_u32oct  ("fmask",       opt_fmask),
  54         {}
  55 };
  56
  57 static int vboxsf_parse_param(struct fs_context *fc, struct fs_parameter *param)
  58 {
  59         struct vboxsf_fs_context *ctx = fc->fs_private;
  60         struct fs_parse_result result;
  61         kuid_t uid;
  62         kgid_t gid;
  63         int opt;
  64
  65         opt = fs_parse(fc, vboxsf_fs_parameters, param, &result);
  66         if (opt < 0)
  67                 return opt;
  68
  69         switch (opt) {
  70         case opt_nls:
  71                 if (ctx->nls_name || fc->purpose != FS_CONTEXT_FOR_MOUNT) {
  72                         vbg_err("vboxsf: Cannot reconfigure nls option\n");
  73                         return -EINVAL;
  74                 }
  75                 ctx->nls_name = param->string;
  76                 param->string = NULL;
  77                 break;
  78         case opt_uid:
  79                 uid = make_kuid(current_user_ns(), result.uint_32);
  80                 if (!uid_valid(uid))
  81                         return -EINVAL;
  82                 ctx->o.uid = uid;
  83                 break;
  84         case opt_gid:
  85                 gid = make_kgid(current_user_ns(), result.uint_32);
  86                 if (!gid_valid(gid))
  87                         return -EINVAL;
  88                 ctx->o.gid = gid;
  89                 break;
  90         case opt_ttl:
  91                 ctx->o.ttl = msecs_to_jiffies(result.uint_32);
  92                 break;
  93         case opt_dmode:
  94                 if (result.uint_32 & ~0777)
  95                         return -EINVAL;
  96                 ctx->o.dmode = result.uint_32;
  97                 ctx->o.dmode_set = true;
  98                 break;
  99         case opt_fmode:
 100                 if (result.uint_32 & ~0777)
 101                         return -EINVAL;
 102                 ctx->o.fmode = result.uint_32;
 103                 ctx->o.fmode_set = true;
 104                 break;
 105         case opt_dmask:
 106                 if (result.uint_32 & ~07777)
 107                         return -EINVAL;
 108                 ctx->o.dmask = result.uint_32;
 109                 break;
 110         case opt_fmask:
 111                 if (result.uint_32 & ~07777)
 112                         return -EINVAL;
 113                 ctx->o.fmask = result.uint_32;
 114                 break;
 115         default:
 116                 return -EINVAL;
 117         }
 118
 119         return 0;
 120 }
 121
 122 static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc)
 123 {
 124         struct vboxsf_fs_context *ctx = fc->fs_private;
 125         struct shfl_string *folder_name, root_path;
 126         struct vboxsf_sbi *sbi;
 127         struct dentry *droot;
 128         struct inode *iroot;
 129         char *nls_name;
 130         size_t size;
 131         int err;
 132
 133         if (!fc->source)
 134                 return -EINVAL;
 135
 136         sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
 137         if (!sbi)
 138                 return -ENOMEM;
 139
 140         sbi->o = ctx->o;
 141         idr_init(&sbi->ino_idr);
 142         spin_lock_init(&sbi->ino_idr_lock);
 143         sbi->next_generation = 1;
 144         sbi->bdi_id = -1;
 145
 146         /* Load nls if not utf8 */
 147         nls_name = ctx->nls_name ? ctx->nls_name : vboxsf_default_nls;
 148         if (strcmp(nls_name, "utf8") != 0) {
 149                 if (nls_name == vboxsf_default_nls)
 150                         sbi->nls = load_nls_default();
 151                 else
 152                         sbi->nls = load_nls(nls_name);
 153
 154                 if (!sbi->nls) {
 155                         vbg_err("vboxsf: Count not load '%s' nls\n", nls_name);
 156                         err = -EINVAL;
 157                         goto fail_free;
 158                 }
 159         }
 160
 161         sbi->bdi_id = ida_simple_get(&vboxsf_bdi_ida, 0, 0, GFP_KERNEL);
 162         if (sbi->bdi_id < 0) {
 163                 err = sbi->bdi_id;
 164                 goto fail_free;
 165         }
 166
 167         err = super_setup_bdi_name(sb, "vboxsf-%d", sbi->bdi_id);
 168         if (err)
 169                 goto fail_free;
 170         sb->s_bdi->ra_pages = 0;
 171         sb->s_bdi->io_pages = 0;
 172
 173         /* Turn source into a shfl_string and map the folder */
 174         size = strlen(fc->source) + 1;
 175         folder_name = kmalloc(SHFLSTRING_HEADER_SIZE + size, GFP_KERNEL);
 176         if (!folder_name) {
 177                 err = -ENOMEM;
 178                 goto fail_free;
 179         }
 180         folder_name->size = size;
 181         folder_name->length = size - 1;
 182         strlcpy(folder_name->string.utf8, fc->source, size);
 183         err = vboxsf_map_folder(folder_name, &sbi->root);
 184         kfree(folder_name);
 185         if (err) {
 186                 vbg_err("vboxsf: Host rejected mount of '%s' with error %d\n",
 187                         fc->source, err);
 188                 goto fail_free;
 189         }
 190
 191         root_path.length = 1;
 192         root_path.size = 2;
 193         root_path.string.utf8[0] = '/';
 194         root_path.string.utf8[1] = 0;
 195         err = vboxsf_stat(sbi, &root_path, &sbi->root_info);
 196         if (err)
 197                 goto fail_unmap;
 198
 199         sb->s_magic = VBOXSF_SUPER_MAGIC;
 200         sb->s_blocksize = 1024;
 201         sb->s_maxbytes = MAX_LFS_FILESIZE;
 202         sb->s_op = &vboxsf_super_ops;
 203         sb->s_d_op = &vboxsf_dentry_ops;
 204
 205         iroot = iget_locked(sb, 0);
 206         if (!iroot) {
 207                 err = -ENOMEM;
 208                 goto fail_unmap;
 209         }
 210         vboxsf_init_inode(sbi, iroot, &sbi->root_info);
 211         unlock_new_inode(iroot);
 212
 213         droot = d_make_root(iroot);
 214         if (!droot) {
 215                 err = -ENOMEM;
 216                 goto fail_unmap;
 217         }
 218
 219         sb->s_root = droot;
 220         sb->s_fs_info = sbi;
 221         return 0;
 222
 223 fail_unmap:
 224         vboxsf_unmap_folder(sbi->root);
 225 fail_free:
 226         if (sbi->bdi_id >= 0)
 227                 ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
 228         if (sbi->nls)
 229                 unload_nls(sbi->nls);
 230         idr_destroy(&sbi->ino_idr);
 231         kfree(sbi);
 232         return err;
 233 }
 234
 235 static void vboxsf_inode_init_once(void *data)
 236 {
 237         struct vboxsf_inode *sf_i = data;
 238
 239         mutex_init(&sf_i->handle_list_mutex);
 240         inode_init_once(&sf_i->vfs_inode);
 241 }
 242
 243 static struct inode *vboxsf_alloc_inode(struct super_block *sb)
 244 {
 245         struct vboxsf_inode *sf_i;
 246
 247         sf_i = kmem_cache_alloc(vboxsf_inode_cachep, GFP_NOFS);
 248         if (!sf_i)
 249                 return NULL;
 250
 251         sf_i->force_restat = 0;
 252         INIT_LIST_HEAD(&sf_i->handle_list);
 253
 254         return &sf_i->vfs_inode;
 255 }
 256
 257 static void vboxsf_free_inode(struct inode *inode)
 258 {
 259         struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
 260         unsigned long flags;
 261
 262         spin_lock_irqsave(&sbi->ino_idr_lock, flags);
 263         idr_remove(&sbi->ino_idr, inode->i_ino);
 264         spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
 265         kmem_cache_free(vboxsf_inode_cachep, VBOXSF_I(inode));
 266 }
 267
 268 static void vboxsf_put_super(struct super_block *sb)
 269 {
 270         struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
 271
 272         vboxsf_unmap_folder(sbi->root);
 273         if (sbi->bdi_id >= 0)
 274                 ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
 275         if (sbi->nls)
 276                 unload_nls(sbi->nls);
 277
 278         /*
 279          * vboxsf_free_inode uses the idr, make sure all delayed rcu free
 280          * inodes are flushed.
 281          */
 282         rcu_barrier();
 283         idr_destroy(&sbi->ino_idr);
 284         kfree(sbi);
 285 }
 286
 287 static int vboxsf_statfs(struct dentry *dentry, struct kstatfs *stat)
 288 {
 289         struct super_block *sb = dentry->d_sb;
 290         struct shfl_volinfo shfl_volinfo;
 291         struct vboxsf_sbi *sbi;
 292         u32 buf_len;
 293         int err;
 294
 295         sbi = VBOXSF_SBI(sb);
 296         buf_len = sizeof(shfl_volinfo);
 297         err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
 298                             &buf_len, &shfl_volinfo);
 299         if (err)
 300                 return err;
 301
 302         stat->f_type = VBOXSF_SUPER_MAGIC;
 303         stat->f_bsize = shfl_volinfo.bytes_per_allocation_unit;
 304
 305         do_div(shfl_volinfo.total_allocation_bytes,
 306                shfl_volinfo.bytes_per_allocation_unit);
 307         stat->f_blocks = shfl_volinfo.total_allocation_bytes;
 308
 309         do_div(shfl_volinfo.available_allocation_bytes,
 310                shfl_volinfo.bytes_per_allocation_unit);
 311         stat->f_bfree  = shfl_volinfo.available_allocation_bytes;
 312         stat->f_bavail = shfl_volinfo.available_allocation_bytes;
 313
 314         stat->f_files = 1000;
 315         /*
 316          * Don't return 0 here since the guest may then think that it is not
 317          * possible to create any more files.
 318          */
 319         stat->f_ffree = 1000000;
 320         stat->f_fsid.val[0] = 0;
 321         stat->f_fsid.val[1] = 0;
 322         stat->f_namelen = 255;
 323         return 0;
 324 }
 325
 326 static struct super_operations vboxsf_super_ops = {
 327         .alloc_inode    = vboxsf_alloc_inode,
 328         .free_inode     = vboxsf_free_inode,
 329         .put_super      = vboxsf_put_super,
 330         .statfs         = vboxsf_statfs,
 331 };
 332
 333 static int vboxsf_setup(void)
 334 {
 335         int err;
 336
 337         mutex_lock(&vboxsf_setup_mutex);
 338
 339         if (vboxsf_setup_done)
 340                 goto success;
 341
 342         vboxsf_inode_cachep =
 343                 kmem_cache_create("vboxsf_inode_cache",
 344                                   sizeof(struct vboxsf_inode), 0,
 345                                   (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
 346                                    SLAB_ACCOUNT),
 347                                   vboxsf_inode_init_once);
 348         if (!vboxsf_inode_cachep) {
 349                 err = -ENOMEM;
 350                 goto fail_nomem;
 351         }
 352
 353         err = vboxsf_connect();
 354         if (err) {
 355                 vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err);
 356                 vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n");
 357                 vbg_err("vboxsf: and check dmesg for vboxguest errors\n");
 358                 goto fail_free_cache;
 359         }
 360
 361         err = vboxsf_set_utf8();
 362         if (err) {
 363                 vbg_err("vboxsf_setutf8 error %d\n", err);
 364                 goto fail_disconnect;
 365         }
 366
 367         if (!follow_symlinks) {
 368                 err = vboxsf_set_symlinks();
 369                 if (err)
 370                         vbg_warn("vboxsf: Unable to show symlinks: %d\n", err);
 371         }
 372
 373         vboxsf_setup_done = true;
 374 success:
 375         mutex_unlock(&vboxsf_setup_mutex);
 376         return 0;
 377
 378 fail_disconnect:
 379         vboxsf_disconnect();
 380 fail_free_cache:
 381         kmem_cache_destroy(vboxsf_inode_cachep);
 382 fail_nomem:
 383         mutex_unlock(&vboxsf_setup_mutex);
 384         return err;
 385 }
 386
 387 static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
 388 {
 389         unsigned char *options = data;
 390
 391         if (options && options[0] == VBSF_MOUNT_SIGNATURE_BYTE_0 &&
 392                        options[1] == VBSF_MOUNT_SIGNATURE_BYTE_1 &&
 393                        options[2] == VBSF_MOUNT_SIGNATURE_BYTE_2 &&
 394                        options[3] == VBSF_MOUNT_SIGNATURE_BYTE_3) {
 395                 vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n");
 396                 return -EINVAL;
 397         }
 398
 399         return generic_parse_monolithic(fc, data);
 400 }
 401
 402 static int vboxsf_get_tree(struct fs_context *fc)
 403 {
 404         int err;
 405
 406         err = vboxsf_setup();
 407         if (err)
 408                 return err;
 409
 410         return get_tree_nodev(fc, vboxsf_fill_super);
 411 }
 412
 413 static int vboxsf_reconfigure(struct fs_context *fc)
 414 {
 415         struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
 416         struct vboxsf_fs_context *ctx = fc->fs_private;
 417         struct inode *iroot = fc->root->d_sb->s_root->d_inode;
 418
 419         /* Apply changed options to the root inode */
 420         sbi->o = ctx->o;
 421         vboxsf_init_inode(sbi, iroot, &sbi->root_info);
 422
 423         return 0;
 424 }
 425
 426 static void vboxsf_free_fc(struct fs_context *fc)
 427 {
 428         struct vboxsf_fs_context *ctx = fc->fs_private;
 429
 430         kfree(ctx->nls_name);
 431         kfree(ctx);
 432 }
 433
 434 static const struct fs_context_operations vboxsf_context_ops = {
 435         .free                   = vboxsf_free_fc,
 436         .parse_param            = vboxsf_parse_param,
 437         .parse_monolithic       = vboxsf_parse_monolithic,
 438         .get_tree               = vboxsf_get_tree,
 439         .reconfigure            = vboxsf_reconfigure,
 440 };
 441
 442 static int vboxsf_init_fs_context(struct fs_context *fc)
 443 {
 444         struct vboxsf_fs_context *ctx;
 445
 446         ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 447         if (!ctx)
 448                 return -ENOMEM;
 449
 450         current_uid_gid(&ctx->o.uid, &ctx->o.gid);
 451
 452         fc->fs_private = ctx;
 453         fc->ops = &vboxsf_context_ops;
 454         return 0;
 455 }
 456
 457 static struct file_system_type vboxsf_fs_type = {
 458         .owner                  = THIS_MODULE,
 459         .name                   = "vboxsf",
 460         .init_fs_context        = vboxsf_init_fs_context,
 461         .kill_sb                = kill_anon_super
 462 };
 463
 464 /* Module initialization/finalization handlers */
 465 static int __init vboxsf_init(void)
 466 {
 467         return register_filesystem(&vboxsf_fs_type);
 468 }
 469
 470 static void __exit vboxsf_fini(void)
 471 {
 472         unregister_filesystem(&vboxsf_fs_type);
 473
 474         mutex_lock(&vboxsf_setup_mutex);
 475         if (vboxsf_setup_done) {
 476                 vboxsf_disconnect();
 477                 /*
 478                  * Make sure all delayed rcu free inodes are flushed
 479                  * before we destroy the cache.
 480                  */
 481                 rcu_barrier();
 482                 kmem_cache_destroy(vboxsf_inode_cachep);
 483         }
 484         mutex_unlock(&vboxsf_setup_mutex);
 485 }
 486
 487 module_init(vboxsf_init);
 488 module_exit(vboxsf_fini);
 489
 490 MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
 491 MODULE_AUTHOR("Oracle Corporation");
 492 MODULE_LICENSE("GPL v2");
 493 MODULE_ALIAS_FS("vboxsf");