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
 171         /* Turn source into a shfl_string and map the folder */
 172         size = strlen(fc->source) + 1;
 173         folder_name = kmalloc(SHFLSTRING_HEADER_SIZE + size, GFP_KERNEL);
 174         if (!folder_name) {
 175                 err = -ENOMEM;
 176                 goto fail_free;
 177         }
 178         folder_name->size = size;
 179         folder_name->length = size - 1;
 180         strlcpy(folder_name->string.utf8, fc->source, size);
 181         err = vboxsf_map_folder(folder_name, &sbi->root);
 182         kfree(folder_name);
 183         if (err) {
 184                 vbg_err("vboxsf: Host rejected mount of '%s' with error %d\n",
 185                         fc->source, err);
 186                 goto fail_free;
 187         }
 188
 189         root_path.length = 1;
 190         root_path.size = 2;
 191         root_path.string.utf8[0] = '/';
 192         root_path.string.utf8[1] = 0;
 193         err = vboxsf_stat(sbi, &root_path, &sbi->root_info);
 194         if (err)
 195                 goto fail_unmap;
 196
 197         sb->s_magic = VBOXSF_SUPER_MAGIC;
 198         sb->s_blocksize = 1024;
 199         sb->s_maxbytes = MAX_LFS_FILESIZE;
 200         sb->s_op = &vboxsf_super_ops;
 201         sb->s_d_op = &vboxsf_dentry_ops;
 202
 203         iroot = iget_locked(sb, 0);
 204         if (!iroot) {
 205                 err = -ENOMEM;
 206                 goto fail_unmap;
 207         }
 208         vboxsf_init_inode(sbi, iroot, &sbi->root_info);
 209         unlock_new_inode(iroot);
 210
 211         droot = d_make_root(iroot);
 212         if (!droot) {
 213                 err = -ENOMEM;
 214                 goto fail_unmap;
 215         }
 216
 217         sb->s_root = droot;
 218         sb->s_fs_info = sbi;
 219         return 0;
 220
 221 fail_unmap:
 222         vboxsf_unmap_folder(sbi->root);
 223 fail_free:
 224         if (sbi->bdi_id >= 0)
 225                 ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
 226         if (sbi->nls)
 227                 unload_nls(sbi->nls);
 228         idr_destroy(&sbi->ino_idr);
 229         kfree(sbi);
 230         return err;
 231 }
 232
 233 static void vboxsf_inode_init_once(void *data)
 234 {
 235         struct vboxsf_inode *sf_i = data;
 236
 237         mutex_init(&sf_i->handle_list_mutex);
 238         inode_init_once(&sf_i->vfs_inode);
 239 }
 240
 241 static struct inode *vboxsf_alloc_inode(struct super_block *sb)
 242 {
 243         struct vboxsf_inode *sf_i;
 244
 245         sf_i = kmem_cache_alloc(vboxsf_inode_cachep, GFP_NOFS);
 246         if (!sf_i)
 247                 return NULL;
 248
 249         sf_i->force_restat = 0;
 250         INIT_LIST_HEAD(&sf_i->handle_list);
 251
 252         return &sf_i->vfs_inode;
 253 }
 254
 255 static void vboxsf_free_inode(struct inode *inode)
 256 {
 257         struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
 258         unsigned long flags;
 259
 260         spin_lock_irqsave(&sbi->ino_idr_lock, flags);
 261         idr_remove(&sbi->ino_idr, inode->i_ino);
 262         spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
 263         kmem_cache_free(vboxsf_inode_cachep, VBOXSF_I(inode));
 264 }
 265
 266 static void vboxsf_put_super(struct super_block *sb)
 267 {
 268         struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
 269
 270         vboxsf_unmap_folder(sbi->root);
 271         if (sbi->bdi_id >= 0)
 272                 ida_simple_remove(&vboxsf_bdi_ida, sbi->bdi_id);
 273         if (sbi->nls)
 274                 unload_nls(sbi->nls);
 275
 276         /*
 277          * vboxsf_free_inode uses the idr, make sure all delayed rcu free
 278          * inodes are flushed.
 279          */
 280         rcu_barrier();
 281         idr_destroy(&sbi->ino_idr);
 282         kfree(sbi);
 283 }
 284
 285 static int vboxsf_statfs(struct dentry *dentry, struct kstatfs *stat)
 286 {
 287         struct super_block *sb = dentry->d_sb;
 288         struct shfl_volinfo shfl_volinfo;
 289         struct vboxsf_sbi *sbi;
 290         u32 buf_len;
 291         int err;
 292
 293         sbi = VBOXSF_SBI(sb);
 294         buf_len = sizeof(shfl_volinfo);
 295         err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
 296                             &buf_len, &shfl_volinfo);
 297         if (err)
 298                 return err;
 299
 300         stat->f_type = VBOXSF_SUPER_MAGIC;
 301         stat->f_bsize = shfl_volinfo.bytes_per_allocation_unit;
 302
 303         do_div(shfl_volinfo.total_allocation_bytes,
 304                shfl_volinfo.bytes_per_allocation_unit);
 305         stat->f_blocks = shfl_volinfo.total_allocation_bytes;
 306
 307         do_div(shfl_volinfo.available_allocation_bytes,
 308                shfl_volinfo.bytes_per_allocation_unit);
 309         stat->f_bfree  = shfl_volinfo.available_allocation_bytes;
 310         stat->f_bavail = shfl_volinfo.available_allocation_bytes;
 311
 312         stat->f_files = 1000;
 313         /*
 314          * Don't return 0 here since the guest may then think that it is not
 315          * possible to create any more files.
 316          */
 317         stat->f_ffree = 1000000;
 318         stat->f_fsid.val[0] = 0;
 319         stat->f_fsid.val[1] = 0;
 320         stat->f_namelen = 255;
 321         return 0;
 322 }
 323
 324 static struct super_operations vboxsf_super_ops = {
 325         .alloc_inode    = vboxsf_alloc_inode,
 326         .free_inode     = vboxsf_free_inode,
 327         .put_super      = vboxsf_put_super,
 328         .statfs         = vboxsf_statfs,
 329 };
 330
 331 static int vboxsf_setup(void)
 332 {
 333         int err;
 334
 335         mutex_lock(&vboxsf_setup_mutex);
 336
 337         if (vboxsf_setup_done)
 338                 goto success;
 339
 340         vboxsf_inode_cachep =
 341                 kmem_cache_create("vboxsf_inode_cache",
 342                                   sizeof(struct vboxsf_inode), 0,
 343                                   (SLAB_RECLAIM_ACCOUNT | SLAB_MEM_SPREAD |
 344                                    SLAB_ACCOUNT),
 345                                   vboxsf_inode_init_once);
 346         if (!vboxsf_inode_cachep) {
 347                 err = -ENOMEM;
 348                 goto fail_nomem;
 349         }
 350
 351         err = vboxsf_connect();
 352         if (err) {
 353                 vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err);
 354                 vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n");
 355                 vbg_err("vboxsf: and check dmesg for vboxguest errors\n");
 356                 goto fail_free_cache;
 357         }
 358
 359         err = vboxsf_set_utf8();
 360         if (err) {
 361                 vbg_err("vboxsf_setutf8 error %d\n", err);
 362                 goto fail_disconnect;
 363         }
 364
 365         if (!follow_symlinks) {
 366                 err = vboxsf_set_symlinks();
 367                 if (err)
 368                         vbg_warn("vboxsf: Unable to show symlinks: %d\n", err);
 369         }
 370
 371         vboxsf_setup_done = true;
 372 success:
 373         mutex_unlock(&vboxsf_setup_mutex);
 374         return 0;
 375
 376 fail_disconnect:
 377         vboxsf_disconnect();
 378 fail_free_cache:
 379         kmem_cache_destroy(vboxsf_inode_cachep);
 380 fail_nomem:
 381         mutex_unlock(&vboxsf_setup_mutex);
 382         return err;
 383 }
 384
 385 static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
 386 {
 387         char *options = data;
 388
 389         if (options && options[0] == VBSF_MOUNT_SIGNATURE_BYTE_0 &&
 390                        options[1] == VBSF_MOUNT_SIGNATURE_BYTE_1 &&
 391                        options[2] == VBSF_MOUNT_SIGNATURE_BYTE_2 &&
 392                        options[3] == VBSF_MOUNT_SIGNATURE_BYTE_3) {
 393                 vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n");
 394                 return -EINVAL;
 395         }
 396
 397         return generic_parse_monolithic(fc, data);
 398 }
 399
 400 static int vboxsf_get_tree(struct fs_context *fc)
 401 {
 402         int err;
 403
 404         err = vboxsf_setup();
 405         if (err)
 406                 return err;
 407
 408         return get_tree_nodev(fc, vboxsf_fill_super);
 409 }
 410
 411 static int vboxsf_reconfigure(struct fs_context *fc)
 412 {
 413         struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
 414         struct vboxsf_fs_context *ctx = fc->fs_private;
 415         struct inode *iroot = fc->root->d_sb->s_root->d_inode;
 416
 417         /* Apply changed options to the root inode */
 418         sbi->o = ctx->o;
 419         vboxsf_init_inode(sbi, iroot, &sbi->root_info);
 420
 421         return 0;
 422 }
 423
 424 static void vboxsf_free_fc(struct fs_context *fc)
 425 {
 426         struct vboxsf_fs_context *ctx = fc->fs_private;
 427
 428         kfree(ctx->nls_name);
 429         kfree(ctx);
 430 }
 431
 432 static const struct fs_context_operations vboxsf_context_ops = {
 433         .free                   = vboxsf_free_fc,
 434         .parse_param            = vboxsf_parse_param,
 435         .parse_monolithic       = vboxsf_parse_monolithic,
 436         .get_tree               = vboxsf_get_tree,
 437         .reconfigure            = vboxsf_reconfigure,
 438 };
 439
 440 static int vboxsf_init_fs_context(struct fs_context *fc)
 441 {
 442         struct vboxsf_fs_context *ctx;
 443
 444         ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
 445         if (!ctx)
 446                 return -ENOMEM;
 447
 448         current_uid_gid(&ctx->o.uid, &ctx->o.gid);
 449
 450         fc->fs_private = ctx;
 451         fc->ops = &vboxsf_context_ops;
 452         return 0;
 453 }
 454
 455 static struct file_system_type vboxsf_fs_type = {
 456         .owner                  = THIS_MODULE,
 457         .name                   = "vboxsf",
 458         .init_fs_context        = vboxsf_init_fs_context,
 459         .kill_sb                = kill_anon_super
 460 };
 461
 462 /* Module initialization/finalization handlers */
 463 static int __init vboxsf_init(void)
 464 {
 465         return register_filesystem(&vboxsf_fs_type);
 466 }
 467
 468 static void __exit vboxsf_fini(void)
 469 {
 470         unregister_filesystem(&vboxsf_fs_type);
 471
 472         mutex_lock(&vboxsf_setup_mutex);
 473         if (vboxsf_setup_done) {
 474                 vboxsf_disconnect();
 475                 /*
 476                  * Make sure all delayed rcu free inodes are flushed
 477                  * before we destroy the cache.
 478                  */
 479                 rcu_barrier();
 480                 kmem_cache_destroy(vboxsf_inode_cachep);
 481         }
 482         mutex_unlock(&vboxsf_setup_mutex);
 483 }
 484
 485 module_init(vboxsf_init);
 486 module_exit(vboxsf_fini);
 487
 488 MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
 489 MODULE_AUTHOR("Oracle Corporation");
 490 MODULE_LICENSE("GPL v2");
 491 MODULE_ALIAS_FS("vboxsf");