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] __nonstring = "\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_uid ("uid", opt_uid), 45 fsparam_gid ("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 int opt; 59 60 opt = fs_parse(fc, vboxsf_fs_parameters, param, &result); 61 if (opt < 0) 62 return opt; 63 64 switch (opt) { 65 case opt_nls: 66 if (ctx->nls_name || fc->purpose != FS_CONTEXT_FOR_MOUNT) { 67 vbg_err("vboxsf: Cannot reconfigure nls option\n"); 68 return -EINVAL; 69 } 70 ctx->nls_name = param->string; 71 param->string = NULL; 72 break; 73 case opt_uid: 74 ctx->o.uid = result.uid; 75 break; 76 case opt_gid: 77 ctx->o.gid = result.gid; 78 break; 79 case opt_ttl: 80 ctx->o.ttl = msecs_to_jiffies(result.uint_32); 81 break; 82 case opt_dmode: 83 if (result.uint_32 & ~0777) 84 return -EINVAL; 85 ctx->o.dmode = result.uint_32; 86 ctx->o.dmode_set = true; 87 break; 88 case opt_fmode: 89 if (result.uint_32 & ~0777) 90 return -EINVAL; 91 ctx->o.fmode = result.uint_32; 92 ctx->o.fmode_set = true; 93 break; 94 case opt_dmask: 95 if (result.uint_32 & ~07777) 96 return -EINVAL; 97 ctx->o.dmask = result.uint_32; 98 break; 99 case opt_fmask: 100 if (result.uint_32 & ~07777) 101 return -EINVAL; 102 ctx->o.fmask = result.uint_32; 103 break; 104 default: 105 return -EINVAL; 106 } 107 108 return 0; 109 } 110 111 static int vboxsf_fill_super(struct super_block *sb, struct fs_context *fc) 112 { 113 struct vboxsf_fs_context *ctx = fc->fs_private; 114 struct shfl_string *folder_name, root_path; 115 struct vboxsf_sbi *sbi; 116 struct dentry *droot; 117 struct inode *iroot; 118 char *nls_name; 119 size_t size; 120 int err; 121 122 if (!fc->source) 123 return -EINVAL; 124 125 sbi = kzalloc_obj(*sbi); 126 if (!sbi) 127 return -ENOMEM; 128 129 sbi->o = ctx->o; 130 idr_init(&sbi->ino_idr); 131 spin_lock_init(&sbi->ino_idr_lock); 132 sbi->next_generation = 1; 133 sbi->bdi_id = -1; 134 135 /* Load nls if not utf8 */ 136 nls_name = ctx->nls_name ? ctx->nls_name : vboxsf_default_nls; 137 if (strcmp(nls_name, "utf8") != 0) { 138 if (nls_name == vboxsf_default_nls) 139 sbi->nls = load_nls_default(); 140 else 141 sbi->nls = load_nls(nls_name); 142 143 if (!sbi->nls) { 144 vbg_err("vboxsf: Count not load '%s' nls\n", nls_name); 145 err = -EINVAL; 146 goto fail_destroy_idr; 147 } 148 } 149 150 sbi->bdi_id = ida_alloc(&vboxsf_bdi_ida, GFP_KERNEL); 151 if (sbi->bdi_id < 0) { 152 err = sbi->bdi_id; 153 goto fail_free; 154 } 155 156 err = super_setup_bdi_name(sb, "vboxsf-%d", sbi->bdi_id); 157 if (err) 158 goto fail_free; 159 sb->s_bdi->ra_pages = 0; 160 sb->s_bdi->io_pages = 0; 161 162 /* Turn source into a shfl_string and map the folder */ 163 size = strlen(fc->source) + 1; 164 folder_name = kmalloc(SHFLSTRING_HEADER_SIZE + size, GFP_KERNEL); 165 if (!folder_name) { 166 err = -ENOMEM; 167 goto fail_free; 168 } 169 folder_name->size = size; 170 folder_name->length = size - 1; 171 strscpy(folder_name->string.utf8, fc->source, size); 172 err = vboxsf_map_folder(folder_name, &sbi->root); 173 kfree(folder_name); 174 if (err) { 175 vbg_err("vboxsf: Host rejected mount of '%s' with error %d\n", 176 fc->source, err); 177 goto fail_free; 178 } 179 180 root_path.length = 1; 181 root_path.size = 2; 182 root_path.string.utf8[0] = '/'; 183 root_path.string.utf8[1] = 0; 184 err = vboxsf_stat(sbi, &root_path, &sbi->root_info); 185 if (err) 186 goto fail_unmap; 187 188 /* 189 * A failed query leaves sbi->case_insensitive false, so the 190 * mount defaults to reporting case-sensitive behavior. Do not 191 * fail the mount over an advisory attribute. 192 */ 193 vboxsf_query_case_sensitive(sbi); 194 195 sb->s_magic = VBOXSF_SUPER_MAGIC; 196 sb->s_blocksize = 1024; 197 sb->s_maxbytes = MAX_LFS_FILESIZE; 198 sb->s_op = &vboxsf_super_ops; 199 set_default_d_op(sb, &vboxsf_dentry_ops); 200 201 iroot = iget_locked(sb, 0); 202 if (!iroot) { 203 err = -ENOMEM; 204 goto fail_unmap; 205 } 206 vboxsf_init_inode(sbi, iroot, &sbi->root_info, false); 207 unlock_new_inode(iroot); 208 209 droot = d_make_root(iroot); 210 if (!droot) { 211 err = -ENOMEM; 212 goto fail_unmap; 213 } 214 215 sb->s_root = droot; 216 sb->s_fs_info = sbi; 217 return 0; 218 219 fail_unmap: 220 vboxsf_unmap_folder(sbi->root); 221 fail_free: 222 if (sbi->bdi_id >= 0) 223 ida_free(&vboxsf_bdi_ida, sbi->bdi_id); 224 if (sbi->nls) 225 unload_nls(sbi->nls); 226 fail_destroy_idr: 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_free(&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_obj(*ctx); 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