1 /*
2 * fs/sdcardfs/main.c
3 *
4 * Copyright (c) 2013 Samsung Electronics Co. Ltd
5 * Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
6 * Sunghwan Yun, Sungjong Seo
7 *
8 * This program has been developed as a stackable file system based on
9 * the WrapFS which written by
10 *
11 * Copyright (c) 1998-2011 Erez Zadok
12 * Copyright (c) 2009 Shrikar Archak
13 * Copyright (c) 2003-2011 Stony Brook University
14 * Copyright (c) 2003-2011 The Research Foundation of SUNY
15 *
16 * This file is dual licensed. It may be redistributed and/or modified
17 * under the terms of the Apache 2.0 License OR version 2 of the GNU
18 * General Public License.
19 */
20
21 #include "sdcardfs.h"
22 #include <linux/module.h>
23 #include <linux/types.h>
24 #include <linux/parser.h>
25
26 enum {
27 Opt_fsuid,
28 Opt_fsgid,
29 Opt_gid,
30 Opt_debug,
31 Opt_mask,
32 Opt_multiuser,
33 Opt_userid,
34 Opt_reserved_mb,
35 Opt_gid_derivation,
36 Opt_default_normal,
37 Opt_err,
38 };
39
40 static const match_table_t sdcardfs_tokens = {
41 {Opt_fsuid, "fsuid=%u"},
42 {Opt_fsgid, "fsgid=%u"},
43 {Opt_gid, "gid=%u"},
44 {Opt_debug, "debug"},
45 {Opt_mask, "mask=%u"},
46 {Opt_userid, "userid=%d"},
47 {Opt_multiuser, "multiuser"},
48 {Opt_gid_derivation, "derive_gid"},
49 {Opt_default_normal, "default_normal"},
50 {Opt_reserved_mb, "reserved_mb=%u"},
51 {Opt_err, NULL}
52 };
53
parse_options(struct super_block * sb,char * options,int silent,int * debug,struct sdcardfs_vfsmount_options * vfsopts,struct sdcardfs_mount_options * opts)54 static int parse_options(struct super_block *sb, char *options, int silent,
55 int *debug, struct sdcardfs_vfsmount_options *vfsopts,
56 struct sdcardfs_mount_options *opts)
57 {
58 char *p;
59 substring_t args[MAX_OPT_ARGS];
60 int option;
61
62 /* by default, we use AID_MEDIA_RW as uid, gid */
63 opts->fs_low_uid = AID_MEDIA_RW;
64 opts->fs_low_gid = AID_MEDIA_RW;
65 vfsopts->mask = 0;
66 opts->multiuser = false;
67 opts->fs_user_id = 0;
68 vfsopts->gid = 0;
69 /* by default, 0MB is reserved */
70 opts->reserved_mb = 0;
71 /* by default, gid derivation is off */
72 opts->gid_derivation = false;
73 opts->default_normal = false;
74
75 *debug = 0;
76
77 if (!options)
78 return 0;
79
80 while ((p = strsep(&options, ",")) != NULL) {
81 int token;
82
83 if (!*p)
84 continue;
85
86 token = match_token(p, sdcardfs_tokens, args);
87
88 switch (token) {
89 case Opt_debug:
90 *debug = 1;
91 break;
92 case Opt_fsuid:
93 if (match_int(&args[0], &option))
94 return 0;
95 opts->fs_low_uid = option;
96 break;
97 case Opt_fsgid:
98 if (match_int(&args[0], &option))
99 return 0;
100 opts->fs_low_gid = option;
101 break;
102 case Opt_gid:
103 if (match_int(&args[0], &option))
104 return 0;
105 vfsopts->gid = option;
106 break;
107 case Opt_userid:
108 if (match_int(&args[0], &option))
109 return 0;
110 opts->fs_user_id = option;
111 break;
112 case Opt_mask:
113 if (match_int(&args[0], &option))
114 return 0;
115 vfsopts->mask = option;
116 break;
117 case Opt_multiuser:
118 opts->multiuser = true;
119 break;
120 case Opt_reserved_mb:
121 if (match_int(&args[0], &option))
122 return 0;
123 opts->reserved_mb = option;
124 break;
125 case Opt_gid_derivation:
126 opts->gid_derivation = true;
127 break;
128 case Opt_default_normal:
129 opts->default_normal = true;
130 break;
131 /* unknown option */
132 default:
133 if (!silent)
134 pr_err("Unrecognized mount option \"%s\" or missing value", p);
135 return -EINVAL;
136 }
137 }
138
139 if (*debug) {
140 pr_info("sdcardfs : options - debug:%d\n", *debug);
141 pr_info("sdcardfs : options - uid:%d\n",
142 opts->fs_low_uid);
143 pr_info("sdcardfs : options - gid:%d\n",
144 opts->fs_low_gid);
145 }
146
147 return 0;
148 }
149
parse_options_remount(struct super_block * sb,char * options,int silent,struct sdcardfs_vfsmount_options * vfsopts)150 int parse_options_remount(struct super_block *sb, char *options, int silent,
151 struct sdcardfs_vfsmount_options *vfsopts)
152 {
153 char *p;
154 substring_t args[MAX_OPT_ARGS];
155 int option;
156 int debug;
157
158 if (!options)
159 return 0;
160
161 while ((p = strsep(&options, ",")) != NULL) {
162 int token;
163
164 if (!*p)
165 continue;
166
167 token = match_token(p, sdcardfs_tokens, args);
168
169 switch (token) {
170 case Opt_debug:
171 debug = 1;
172 break;
173 case Opt_gid:
174 if (match_int(&args[0], &option))
175 return 0;
176 vfsopts->gid = option;
177
178 break;
179 case Opt_mask:
180 if (match_int(&args[0], &option))
181 return 0;
182 vfsopts->mask = option;
183 break;
184 case Opt_default_normal:
185 case Opt_multiuser:
186 case Opt_userid:
187 case Opt_fsuid:
188 case Opt_fsgid:
189 case Opt_reserved_mb:
190 pr_warn("Option \"%s\" can't be changed during remount\n", p);
191 break;
192 /* unknown option */
193 default:
194 if (!silent)
195 pr_err("Unrecognized mount option \"%s\" or missing value", p);
196 return -EINVAL;
197 }
198 }
199
200 if (debug) {
201 pr_info("sdcardfs : options - debug:%d\n", debug);
202 pr_info("sdcardfs : options - gid:%d\n", vfsopts->gid);
203 pr_info("sdcardfs : options - mask:%d\n", vfsopts->mask);
204 }
205
206 return 0;
207 }
208
209 #if 0
210 /*
211 * our custom d_alloc_root work-alike
212 *
213 * we can't use d_alloc_root if we want to use our own interpose function
214 * unchanged, so we simply call our own "fake" d_alloc_root
215 */
216 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
217 {
218 struct dentry *ret = NULL;
219
220 if (sb) {
221 static const struct qstr name = {
222 .name = "/",
223 .len = 1
224 };
225
226 ret = d_alloc(NULL, &name);
227 if (ret) {
228 d_set_d_op(ret, &sdcardfs_ci_dops);
229 ret->d_sb = sb;
230 ret->d_parent = ret;
231 }
232 }
233 return ret;
234 }
235 #endif
236
237 DEFINE_MUTEX(sdcardfs_super_list_lock);
238 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
239 LIST_HEAD(sdcardfs_super_list);
240 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
241
242 /*
243 * There is no need to lock the sdcardfs_super_info's rwsem as there is no
244 * way anyone can have a reference to the superblock at this point in time.
245 */
sdcardfs_read_super(struct vfsmount * mnt,struct super_block * sb,const char * dev_name,void * raw_data,int silent)246 static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
247 const char *dev_name, void *raw_data, int silent)
248 {
249 int err = 0;
250 int debug;
251 struct super_block *lower_sb;
252 struct path lower_path;
253 struct sdcardfs_sb_info *sb_info;
254 struct sdcardfs_vfsmount_options *mnt_opt = mnt->data;
255 struct inode *inode;
256
257 pr_info("sdcardfs version 2.0\n");
258
259 if (!dev_name) {
260 pr_err("sdcardfs: read_super: missing dev_name argument\n");
261 err = -EINVAL;
262 goto out;
263 }
264
265 pr_info("sdcardfs: dev_name -> %s\n", dev_name);
266 pr_info("sdcardfs: options -> %s\n", (char *)raw_data);
267 pr_info("sdcardfs: mnt -> %p\n", mnt);
268
269 /* parse lower path */
270 err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
271 &lower_path);
272 if (err) {
273 pr_err("sdcardfs: error accessing lower directory '%s'\n", dev_name);
274 goto out;
275 }
276
277 /* allocate superblock private data */
278 sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
279 if (!SDCARDFS_SB(sb)) {
280 pr_crit("sdcardfs: read_super: out of memory\n");
281 err = -ENOMEM;
282 goto out_free;
283 }
284
285 sb_info = sb->s_fs_info;
286 /* parse options */
287 err = parse_options(sb, raw_data, silent, &debug, mnt_opt, &sb_info->options);
288 if (err) {
289 pr_err("sdcardfs: invalid options\n");
290 goto out_freesbi;
291 }
292
293 /* set the lower superblock field of upper superblock */
294 lower_sb = lower_path.dentry->d_sb;
295 atomic_inc(&lower_sb->s_active);
296 sdcardfs_set_lower_super(sb, lower_sb);
297
298 /* inherit maxbytes from lower file system */
299 sb->s_maxbytes = lower_sb->s_maxbytes;
300
301 /*
302 * Our c/m/atime granularity is 1 ns because we may stack on file
303 * systems whose granularity is as good.
304 */
305 sb->s_time_gran = 1;
306
307 sb->s_magic = SDCARDFS_SUPER_MAGIC;
308 sb->s_op = &sdcardfs_sops;
309
310 /* get a new inode and allocate our root dentry */
311 inode = sdcardfs_iget(sb, d_inode(lower_path.dentry), 0);
312 if (IS_ERR(inode)) {
313 err = PTR_ERR(inode);
314 goto out_sput;
315 }
316 sb->s_root = d_make_root(inode);
317 if (!sb->s_root) {
318 err = -ENOMEM;
319 goto out_sput;
320 }
321 d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
322
323 /* link the upper and lower dentries */
324 sb->s_root->d_fsdata = NULL;
325 err = new_dentry_private_data(sb->s_root);
326 if (err)
327 goto out_freeroot;
328
329 /* set the lower dentries for s_root */
330 sdcardfs_set_lower_path(sb->s_root, &lower_path);
331
332 /*
333 * No need to call interpose because we already have a positive
334 * dentry, which was instantiated by d_make_root. Just need to
335 * d_rehash it.
336 */
337 d_rehash(sb->s_root);
338
339 /* setup permission policy */
340 sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
341 mutex_lock(&sdcardfs_super_list_lock);
342 if (sb_info->options.multiuser) {
343 setup_derived_state(d_inode(sb->s_root), PERM_PRE_ROOT,
344 sb_info->options.fs_user_id, AID_ROOT);
345 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
346 } else {
347 setup_derived_state(d_inode(sb->s_root), PERM_ROOT,
348 sb_info->options.fs_user_id, AID_ROOT);
349 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
350 }
351 fixup_tmp_permissions(d_inode(sb->s_root));
352 sb_info->sb = sb;
353 list_add(&sb_info->list, &sdcardfs_super_list);
354 mutex_unlock(&sdcardfs_super_list_lock);
355
356 if (!silent)
357 pr_info("sdcardfs: mounted on top of %s type %s\n",
358 dev_name, lower_sb->s_type->name);
359 goto out; /* all is well */
360
361 /* no longer needed: free_dentry_private_data(sb->s_root); */
362 out_freeroot:
363 dput(sb->s_root);
364 sb->s_root = NULL;
365 out_sput:
366 /* drop refs we took earlier */
367 atomic_dec(&lower_sb->s_active);
368 out_freesbi:
369 kfree(SDCARDFS_SB(sb));
370 sb->s_fs_info = NULL;
371 out_free:
372 path_put(&lower_path);
373
374 out:
375 return err;
376 }
377
378 struct sdcardfs_mount_private {
379 struct vfsmount *mnt;
380 const char *dev_name;
381 void *raw_data;
382 };
383
__sdcardfs_fill_super(struct super_block * sb,void * _priv,int silent)384 static int __sdcardfs_fill_super(
385 struct super_block *sb,
386 void *_priv, int silent)
387 {
388 struct sdcardfs_mount_private *priv = _priv;
389
390 return sdcardfs_read_super(priv->mnt,
391 sb, priv->dev_name, priv->raw_data, silent);
392 }
393
sdcardfs_mount(struct vfsmount * mnt,struct file_system_type * fs_type,int flags,const char * dev_name,void * raw_data)394 static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
395 struct file_system_type *fs_type, int flags,
396 const char *dev_name, void *raw_data)
397 {
398 struct sdcardfs_mount_private priv = {
399 .mnt = mnt,
400 .dev_name = dev_name,
401 .raw_data = raw_data
402 };
403
404 return mount_nodev(fs_type, flags,
405 &priv, __sdcardfs_fill_super);
406 }
407
sdcardfs_mount_wrn(struct file_system_type * fs_type,int flags,const char * dev_name,void * raw_data)408 static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type,
409 int flags, const char *dev_name, void *raw_data)
410 {
411 WARN(1, "sdcardfs does not support mount. Use mount2.\n");
412 return ERR_PTR(-EINVAL);
413 }
414
sdcardfs_alloc_mnt_data(void)415 void *sdcardfs_alloc_mnt_data(void)
416 {
417 return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
418 }
419
sdcardfs_kill_sb(struct super_block * sb)420 void sdcardfs_kill_sb(struct super_block *sb)
421 {
422 struct sdcardfs_sb_info *sbi;
423
424 if (sb->s_magic == SDCARDFS_SUPER_MAGIC && sb->s_fs_info) {
425 sbi = SDCARDFS_SB(sb);
426 mutex_lock(&sdcardfs_super_list_lock);
427 list_del(&sbi->list);
428 mutex_unlock(&sdcardfs_super_list_lock);
429 }
430 kill_anon_super(sb);
431 }
432
433 static struct file_system_type sdcardfs_fs_type = {
434 .owner = THIS_MODULE,
435 .name = SDCARDFS_NAME,
436 .mount = sdcardfs_mount_wrn,
437 .mount2 = sdcardfs_mount,
438 .alloc_mnt_data = sdcardfs_alloc_mnt_data,
439 .kill_sb = sdcardfs_kill_sb,
440 .fs_flags = 0,
441 };
442 MODULE_ALIAS_FS(SDCARDFS_NAME);
443
init_sdcardfs_fs(void)444 static int __init init_sdcardfs_fs(void)
445 {
446 int err;
447
448 pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
449
450 err = sdcardfs_init_inode_cache();
451 if (err)
452 goto out;
453 err = sdcardfs_init_dentry_cache();
454 if (err)
455 goto out;
456 err = packagelist_init();
457 if (err)
458 goto out;
459 err = register_filesystem(&sdcardfs_fs_type);
460 out:
461 if (err) {
462 sdcardfs_destroy_inode_cache();
463 sdcardfs_destroy_dentry_cache();
464 packagelist_exit();
465 }
466 return err;
467 }
468
exit_sdcardfs_fs(void)469 static void __exit exit_sdcardfs_fs(void)
470 {
471 sdcardfs_destroy_inode_cache();
472 sdcardfs_destroy_dentry_cache();
473 packagelist_exit();
474 unregister_filesystem(&sdcardfs_fs_type);
475 pr_info("Completed sdcardfs module unload\n");
476 }
477
478 /* Original wrapfs authors */
479 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University (http://www.fsl.cs.sunysb.edu/)");
480
481 /* Original sdcardfs authors */
482 MODULE_AUTHOR("Woojoong Lee, Daeho Jeong, Kitae Lee, Yeongjin Gil System Memory Lab., Samsung Electronics");
483
484 /* Current maintainer */
485 MODULE_AUTHOR("Daniel Rosenberg, Google");
486 MODULE_DESCRIPTION("Sdcardfs " SDCARDFS_VERSION);
487 MODULE_LICENSE("GPL");
488
489 module_init(init_sdcardfs_fs);
490 module_exit(exit_sdcardfs_fs);
491