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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
24static const unsigned char VBSF_MOUNT_SIGNATURE[4] = "\000\377\376\375";
25
26static int follow_symlinks;
27module_param(follow_symlinks, int, 0444);
28MODULE_PARM_DESC(follow_symlinks,
29 "Let host resolve symlinks rather than showing them");
30
31static DEFINE_IDA(vboxsf_bdi_ida);
32static DEFINE_MUTEX(vboxsf_setup_mutex);
33static bool vboxsf_setup_done;
34static struct super_operations vboxsf_super_ops; /* forward declaration */
35static struct kmem_cache *vboxsf_inode_cachep;
36
37static char * const vboxsf_default_nls = CONFIG_NLS_DEFAULT;
38
39enum { opt_nls, opt_uid, opt_gid, opt_ttl, opt_dmode, opt_fmode,
40 opt_dmask, opt_fmask };
41
42static 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
54static 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
119static 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_free;
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 strlcpy(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
220fail_unmap:
221 vboxsf_unmap_folder(sbi->root);
222fail_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 idr_destroy(&sbi->ino_idr);
228 kfree(sbi);
229 return err;
230}
231
232static 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
240static 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
254static 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
265static 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_simple_remove(&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
284static 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
323static 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
330static 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_MEM_SPREAD |
343 SLAB_ACCOUNT),
344 vboxsf_inode_init_once);
345 if (!vboxsf_inode_cachep) {
346 err = -ENOMEM;
347 goto fail_nomem;
348 }
349
350 err = vboxsf_connect();
351 if (err) {
352 vbg_err("vboxsf: err %d connecting to guest PCI-device\n", err);
353 vbg_err("vboxsf: make sure you are inside a VirtualBox VM\n");
354 vbg_err("vboxsf: and check dmesg for vboxguest errors\n");
355 goto fail_free_cache;
356 }
357
358 err = vboxsf_set_utf8();
359 if (err) {
360 vbg_err("vboxsf_setutf8 error %d\n", err);
361 goto fail_disconnect;
362 }
363
364 if (!follow_symlinks) {
365 err = vboxsf_set_symlinks();
366 if (err)
367 vbg_warn("vboxsf: Unable to show symlinks: %d\n", err);
368 }
369
370 vboxsf_setup_done = true;
371success:
372 mutex_unlock(&vboxsf_setup_mutex);
373 return 0;
374
375fail_disconnect:
376 vboxsf_disconnect();
377fail_free_cache:
378 kmem_cache_destroy(vboxsf_inode_cachep);
379fail_nomem:
380 mutex_unlock(&vboxsf_setup_mutex);
381 return err;
382}
383
384static int vboxsf_parse_monolithic(struct fs_context *fc, void *data)
385{
386 if (data && !memcmp(data, VBSF_MOUNT_SIGNATURE, 4)) {
387 vbg_err("vboxsf: Old binary mount data not supported, remove obsolete mount.vboxsf and/or update your VBoxService.\n");
388 return -EINVAL;
389 }
390
391 return generic_parse_monolithic(fc, data);
392}
393
394static int vboxsf_get_tree(struct fs_context *fc)
395{
396 int err;
397
398 err = vboxsf_setup();
399 if (err)
400 return err;
401
402 return get_tree_nodev(fc, vboxsf_fill_super);
403}
404
405static int vboxsf_reconfigure(struct fs_context *fc)
406{
407 struct vboxsf_sbi *sbi = VBOXSF_SBI(fc->root->d_sb);
408 struct vboxsf_fs_context *ctx = fc->fs_private;
409 struct inode *iroot = fc->root->d_sb->s_root->d_inode;
410
411 /* Apply changed options to the root inode */
412 sbi->o = ctx->o;
413 vboxsf_init_inode(sbi, iroot, &sbi->root_info, true);
414
415 return 0;
416}
417
418static void vboxsf_free_fc(struct fs_context *fc)
419{
420 struct vboxsf_fs_context *ctx = fc->fs_private;
421
422 kfree(ctx->nls_name);
423 kfree(ctx);
424}
425
426static const struct fs_context_operations vboxsf_context_ops = {
427 .free = vboxsf_free_fc,
428 .parse_param = vboxsf_parse_param,
429 .parse_monolithic = vboxsf_parse_monolithic,
430 .get_tree = vboxsf_get_tree,
431 .reconfigure = vboxsf_reconfigure,
432};
433
434static int vboxsf_init_fs_context(struct fs_context *fc)
435{
436 struct vboxsf_fs_context *ctx;
437
438 ctx = kzalloc(sizeof(*ctx), GFP_KERNEL);
439 if (!ctx)
440 return -ENOMEM;
441
442 current_uid_gid(&ctx->o.uid, &ctx->o.gid);
443
444 fc->fs_private = ctx;
445 fc->ops = &vboxsf_context_ops;
446 return 0;
447}
448
449static struct file_system_type vboxsf_fs_type = {
450 .owner = THIS_MODULE,
451 .name = "vboxsf",
452 .init_fs_context = vboxsf_init_fs_context,
453 .kill_sb = kill_anon_super
454};
455
456/* Module initialization/finalization handlers */
457static int __init vboxsf_init(void)
458{
459 return register_filesystem(&vboxsf_fs_type);
460}
461
462static void __exit vboxsf_fini(void)
463{
464 unregister_filesystem(&vboxsf_fs_type);
465
466 mutex_lock(&vboxsf_setup_mutex);
467 if (vboxsf_setup_done) {
468 vboxsf_disconnect();
469 /*
470 * Make sure all delayed rcu free inodes are flushed
471 * before we destroy the cache.
472 */
473 rcu_barrier();
474 kmem_cache_destroy(vboxsf_inode_cachep);
475 }
476 mutex_unlock(&vboxsf_setup_mutex);
477}
478
479module_init(vboxsf_init);
480module_exit(vboxsf_fini);
481
482MODULE_DESCRIPTION("Oracle VM VirtualBox Module for Host File System Access");
483MODULE_AUTHOR("Oracle Corporation");
484MODULE_LICENSE("GPL v2");
485MODULE_ALIAS_FS("vboxsf");