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"); 492