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
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 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
vboxsf_fill_super(struct super_block * sb,struct fs_context * fc)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(sizeof(*sbi), GFP_KERNEL);
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 sb->s_magic = VBOXSF_SUPER_MAGIC;
189 sb->s_blocksize = 1024;
190 sb->s_maxbytes = MAX_LFS_FILESIZE;
191 sb->s_op = &vboxsf_super_ops;
192 set_default_d_op(sb, &vboxsf_dentry_ops);
193
194 iroot = iget_locked(sb, 0);
195 if (!iroot) {
196 err = -ENOMEM;
197 goto fail_unmap;
198 }
199 vboxsf_init_inode(sbi, iroot, &sbi->root_info, false);
200 unlock_new_inode(iroot);
201
202 droot = d_make_root(iroot);
203 if (!droot) {
204 err = -ENOMEM;
205 goto fail_unmap;
206 }
207
208 sb->s_root = droot;
209 sb->s_fs_info = sbi;
210 return 0;
211
212 fail_unmap:
213 vboxsf_unmap_folder(sbi->root);
214 fail_free:
215 if (sbi->bdi_id >= 0)
216 ida_free(&vboxsf_bdi_ida, sbi->bdi_id);
217 if (sbi->nls)
218 unload_nls(sbi->nls);
219 fail_destroy_idr:
220 idr_destroy(&sbi->ino_idr);
221 kfree(sbi);
222 return err;
223 }
224
vboxsf_inode_init_once(void * data)225 static void vboxsf_inode_init_once(void *data)
226 {
227 struct vboxsf_inode *sf_i = data;
228
229 mutex_init(&sf_i->handle_list_mutex);
230 inode_init_once(&sf_i->vfs_inode);
231 }
232
vboxsf_alloc_inode(struct super_block * sb)233 static struct inode *vboxsf_alloc_inode(struct super_block *sb)
234 {
235 struct vboxsf_inode *sf_i;
236
237 sf_i = alloc_inode_sb(sb, vboxsf_inode_cachep, GFP_NOFS);
238 if (!sf_i)
239 return NULL;
240
241 sf_i->force_restat = 0;
242 INIT_LIST_HEAD(&sf_i->handle_list);
243
244 return &sf_i->vfs_inode;
245 }
246
vboxsf_free_inode(struct inode * inode)247 static void vboxsf_free_inode(struct inode *inode)
248 {
249 struct vboxsf_sbi *sbi = VBOXSF_SBI(inode->i_sb);
250 unsigned long flags;
251
252 spin_lock_irqsave(&sbi->ino_idr_lock, flags);
253 idr_remove(&sbi->ino_idr, inode->i_ino);
254 spin_unlock_irqrestore(&sbi->ino_idr_lock, flags);
255 kmem_cache_free(vboxsf_inode_cachep, VBOXSF_I(inode));
256 }
257
vboxsf_put_super(struct super_block * sb)258 static void vboxsf_put_super(struct super_block *sb)
259 {
260 struct vboxsf_sbi *sbi = VBOXSF_SBI(sb);
261
262 vboxsf_unmap_folder(sbi->root);
263 if (sbi->bdi_id >= 0)
264 ida_free(&vboxsf_bdi_ida, sbi->bdi_id);
265 if (sbi->nls)
266 unload_nls(sbi->nls);
267
268 /*
269 * vboxsf_free_inode uses the idr, make sure all delayed rcu free
270 * inodes are flushed.
271 */
272 rcu_barrier();
273 idr_destroy(&sbi->ino_idr);
274 kfree(sbi);
275 }
276
vboxsf_statfs(struct dentry * dentry,struct kstatfs * stat)277 static int vboxsf_statfs(struct dentry *dentry, struct kstatfs *stat)
278 {
279 struct super_block *sb = dentry->d_sb;
280 struct shfl_volinfo shfl_volinfo;
281 struct vboxsf_sbi *sbi;
282 u32 buf_len;
283 int err;
284
285 sbi = VBOXSF_SBI(sb);
286 buf_len = sizeof(shfl_volinfo);
287 err = vboxsf_fsinfo(sbi->root, 0, SHFL_INFO_GET | SHFL_INFO_VOLUME,
288 &buf_len, &shfl_volinfo);
289 if (err)
290 return err;
291
292 stat->f_type = VBOXSF_SUPER_MAGIC;
293 stat->f_bsize = shfl_volinfo.bytes_per_allocation_unit;
294
295 do_div(shfl_volinfo.total_allocation_bytes,
296 shfl_volinfo.bytes_per_allocation_unit);
297 stat->f_blocks = shfl_volinfo.total_allocation_bytes;
298
299 do_div(shfl_volinfo.available_allocation_bytes,
300 shfl_volinfo.bytes_per_allocation_unit);
301 stat->f_bfree = shfl_volinfo.available_allocation_bytes;
302 stat->f_bavail = shfl_volinfo.available_allocation_bytes;
303
304 stat->f_files = 1000;
305 /*
306 * Don't return 0 here since the guest may then think that it is not
307 * possible to create any more files.
308 */
309 stat->f_ffree = 1000000;
310 stat->f_fsid.val[0] = 0;
311 stat->f_fsid.val[1] = 0;
312 stat->f_namelen = 255;
313 return 0;
314 }
315
316 static struct super_operations vboxsf_super_ops = {
317 .alloc_inode = vboxsf_alloc_inode,
318 .free_inode = vboxsf_free_inode,
319 .put_super = vboxsf_put_super,
320 .statfs = vboxsf_statfs,
321 };
322
vboxsf_setup(void)323 static int vboxsf_setup(void)
324 {
325 int err;
326
327 mutex_lock(&vboxsf_setup_mutex);
328
329 if (vboxsf_setup_done)
330 goto success;
331
332 vboxsf_inode_cachep =
333 kmem_cache_create("vboxsf_inode_cache",
334 sizeof(struct vboxsf_inode), 0,
335 SLAB_RECLAIM_ACCOUNT | SLAB_ACCOUNT,
336 vboxsf_inode_init_once);
337 if (!vboxsf_inode_cachep) {
338 err = -ENOMEM;
339 goto fail_nomem;
340 }
341
342 err = vboxsf_connect();
343 if (err) {
344 vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err);
345 vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n");
346 vbg_err("vboxsf: and check dmesg for vboxguest errors\n");
347 goto fail_free_cache;
348 }
349
350 err = vboxsf_set_utf8();
351 if (err) {
352 vbg_err("vboxsf_setutf8 error %d\n", err);
353 goto fail_disconnect;
354 }
355
356 if (!follow_symlinks) {
357 err = vboxsf_set_symlinks();
358 if (err)
359 vbg_warn("vboxsf: Unable to show symlinks: %d\n", err);
360 }
361
362 vboxsf_setup_done = true;
363 success:
364 mutex_unlock(&vboxsf_setup_mutex);
365 return 0;
366
367 fail_disconnect:
368 vboxsf_disconnect();
369 fail_free_cache:
370 kmem_cache_destroy(vboxsf_inode_cachep);
371 fail_nomem:
372 mutex_unlock(&vboxsf_setup_mutex);
373 return err;
374 }
375
vboxsf_parse_monolithic(struct fs_context * fc,void * data)376 static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
377 {
378 if (data && !memcmp(data, VBSF_MOUNT_SIGNATURE, 4)) {
379 vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n");
380 return -EINVAL;
381 }
382
383 return generic_parse_monolithic(fc, data);
384 }
385
vboxsf_get_tree(struct fs_context * fc)386 static int vboxsf_get_tree(struct fs_context *fc)
387 {
388 int err;
389
390 err = vboxsf_setup();
391 if (err)
392 return err;
393
394 return get_tree_nodev(fc, vboxsf_fill_super);
395 }
396
vboxsf_reconfigure(struct fs_context * fc)397 static int vboxsf_reconfigure(struct fs_context *fc)
398 {
399 struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
400 struct vboxsf_fs_context *ctx = fc->fs_private;
401 struct inode *iroot = fc->root->d_sb->s_root->d_inode;
402
403 /* Apply changed options to the root inode */
404 sbi->o = ctx->o;
405 vboxsf_init_inode(sbi, iroot, &sbi->root_info, true);
406
407 return 0;
408 }
409
vboxsf_free_fc(struct fs_context * fc)410 static void vboxsf_free_fc(struct fs_context *fc)
411 {
412 struct vboxsf_fs_context *ctx = fc->fs_private;
413
414 kfree(ctx->nls_name);
415 kfree(ctx);
416 }
417
418 static const struct fs_context_operations vboxsf_context_ops = {
419 .free = vboxsf_free_fc,
420 .parse_param = vboxsf_parse_param,
421 .parse_monolithic = vboxsf_parse_monolithic,
422 .get_tree = vboxsf_get_tree,
423 .reconfigure = vboxsf_reconfigure,
424 };
425
vboxsf_init_fs_context(struct fs_context * fc)426 static int vboxsf_init_fs_context(struct fs_context *fc)
427 {
428 struct vboxsf_fs_context *ctx;
429
430 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
431 if (!ctx)
432 return -ENOMEM;
433
434 current_uid_gid(&ctx->o.uid, &ctx->o.gid);
435
436 fc->fs_private = ctx;
437 fc->ops = &vboxsf_context_ops;
438 return 0;
439 }
440
441 static struct file_system_type vboxsf_fs_type = {
442 .owner = THIS_MODULE,
443 .name = "vboxsf",
444 .init_fs_context = vboxsf_init_fs_context,
445 .kill_sb = kill_anon_super
446 };
447
448 /* Module initialization/finalization handlers */
vboxsf_init(void)449 static int __init vboxsf_init(void)
450 {
451 return register_filesystem(&vboxsf_fs_type);
452 }
453
vboxsf_fini(void)454 static void __exit vboxsf_fini(void)
455 {
456 unregister_filesystem(&vboxsf_fs_type);
457
458 mutex_lock(&vboxsf_setup_mutex);
459 if (vboxsf_setup_done) {
460 vboxsf_disconnect();
461 /*
462 * Make sure all delayed rcu free inodes are flushed
463 * before we destroy the cache.
464 */
465 rcu_barrier();
466 kmem_cache_destroy(vboxsf_inode_cachep);
467 }
468 mutex_unlock(&vboxsf_setup_mutex);
469 }
470
471 module_init(vboxsf_init);
472 module_exit(vboxsf_fini);
473
474 MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
475 MODULE_AUTHOR("Oracle Corporation");
476 MODULE_LICENSE("GPL v2");
477 MODULE_ALIAS_FS("vboxsf");
478