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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
29static int follow_symlinks;
30module_param(follow_symlinks, int, 0444);
31MODULE_PARM_DESC(follow_symlinks,
32 "Let host resolve symlinks rather than showing them");
33
34static DEFINE_IDA(vboxsf_bdi_ida);
35static DEFINE_MUTEX(vboxsf_setup_mutex);
36static bool vboxsf_setup_done;
37static struct super_operations vboxsf_super_ops; /* forward declaration */
38static struct kmem_cache *vboxsf_inode_cachep;
39
40static char * const vboxsf_default_nls = CONFIG_NLS_DEFAULT;
41
42enum { opt_nls, opt_uid, opt_gid, opt_ttl, opt_dmode, opt_fmode,
43 opt_dmask, opt_fmask };
44
45static 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
57static 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
122static 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
221fail_unmap:
222 vboxsf_unmap_folder(sbi->root);
223fail_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
233static 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
241static 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
255static 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
266static 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
285static 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
324static 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
331static 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;
372success:
373 mutex_unlock(&vboxsf_setup_mutex);
374 return 0;
375
376fail_disconnect:
377 vboxsf_disconnect();
378fail_free_cache:
379 kmem_cache_destroy(vboxsf_inode_cachep);
380fail_nomem:
381 mutex_unlock(&vboxsf_setup_mutex);
382 return err;
383}
384
385static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
386{
387 unsigned 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
400static 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
411static 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
424static 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
432static 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
440static 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
455static 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 */
463static int __init vboxsf_init(void)
464{
465 return register_filesystem(&vboxsf_fs_type);
466}
467
468static 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
485module_init(vboxsf_init);
486module_exit(vboxsf_fini);
487
488MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
489MODULE_AUTHOR("Oracle Corporation");
490MODULE_LICENSE("GPL v2");
491MODULE_ALIAS_FS("vboxsf");