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