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
vboxsf_parse_param(struct fs_context * fc,struct fs_parameter * param)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
vboxsf_fill_super(struct super_block * sb,struct fs_context * fc)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_destroy_idr;
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 fail_destroy_idr:
228 idr_destroy(&sbi->ino_idr);
229 kfree(sbi);
230 return err;
231 }
232
vboxsf_inode_init_once(void * data)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
vboxsf_alloc_inode(struct super_block * sb)241 static struct inode *vboxsf_alloc_inode(struct super_block *sb)
242 {
243 struct vboxsf_inode *sf_i;
244
245 sf_i = alloc_inode_sb(sb, 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
vboxsf_free_inode(struct inode * inode)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
vboxsf_put_super(struct super_block * sb)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
vboxsf_statfs(struct dentry * dentry,struct kstatfs * stat)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
vboxsf_setup(void)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
vboxsf_parse_monolithic(struct fs_context * fc,void * data)385 static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
386 {
387 if (data && !memcmp(data, VBSF_MOUNT_SIGNATURE, 4)) {
388 vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n");
389 return -EINVAL;
390 }
391
392 return generic_parse_monolithic(fc, data);
393 }
394
vboxsf_get_tree(struct fs_context * fc)395 static int vboxsf_get_tree(struct fs_context *fc)
396 {
397 int err;
398
399 err = vboxsf_setup();
400 if (err)
401 return err;
402
403 return get_tree_nodev(fc, vboxsf_fill_super);
404 }
405
vboxsf_reconfigure(struct fs_context * fc)406 static int vboxsf_reconfigure(struct fs_context *fc)
407 {
408 struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
409 struct vboxsf_fs_context *ctx = fc->fs_private;
410 struct inode *iroot = fc->root->d_sb->s_root->d_inode;
411
412 /* Apply changed options to the root inode */
413 sbi->o = ctx->o;
414 vboxsf_init_inode(sbi, iroot, &sbi->root_info, true);
415
416 return 0;
417 }
418
vboxsf_free_fc(struct fs_context * fc)419 static void vboxsf_free_fc(struct fs_context *fc)
420 {
421 struct vboxsf_fs_context *ctx = fc->fs_private;
422
423 kfree(ctx->nls_name);
424 kfree(ctx);
425 }
426
427 static const struct fs_context_operations vboxsf_context_ops = {
428 .free = vboxsf_free_fc,
429 .parse_param = vboxsf_parse_param,
430 .parse_monolithic = vboxsf_parse_monolithic,
431 .get_tree = vboxsf_get_tree,
432 .reconfigure = vboxsf_reconfigure,
433 };
434
vboxsf_init_fs_context(struct fs_context * fc)435 static int vboxsf_init_fs_context(struct fs_context *fc)
436 {
437 struct vboxsf_fs_context *ctx;
438
439 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
440 if (!ctx)
441 return -ENOMEM;
442
443 current_uid_gid(&ctx->o.uid, &ctx->o.gid);
444
445 fc->fs_private = ctx;
446 fc->ops = &vboxsf_context_ops;
447 return 0;
448 }
449
450 static struct file_system_type vboxsf_fs_type = {
451 .owner = THIS_MODULE,
452 .name = "vboxsf",
453 .init_fs_context = vboxsf_init_fs_context,
454 .kill_sb = kill_anon_super
455 };
456
457 /* Module initialization/finalization handlers */
vboxsf_init(void)458 static int __init vboxsf_init(void)
459 {
460 return register_filesystem(&vboxsf_fs_type);
461 }
462
vboxsf_fini(void)463 static void __exit vboxsf_fini(void)
464 {
465 unregister_filesystem(&vboxsf_fs_type);
466
467 mutex_lock(&vboxsf_setup_mutex);
468 if (vboxsf_setup_done) {
469 vboxsf_disconnect();
470 /*
471 * Make sure all delayed rcu free inodes are flushed
472 * before we destroy the cache.
473 */
474 rcu_barrier();
475 kmem_cache_destroy(vboxsf_inode_cachep);
476 }
477 mutex_unlock(&vboxsf_setup_mutex);
478 }
479
480 module_init(vboxsf_init);
481 module_exit(vboxsf_fini);
482
483 MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
484 MODULE_AUTHOR("Oracle Corporation");
485 MODULE_LICENSE("GPL v2");
486 MODULE_ALIAS_FS("vboxsf");
487