fs/sdcardfs/main.c

   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_lower_fs,
  32         Opt_mask,
  33         Opt_multiuser, // May need?
  34         Opt_userid,
  35         Opt_reserved_mb,
  36         Opt_err,
  37 };
  38
  39 static const match_table_t sdcardfs_tokens = {
  40         {Opt_fsuid, "fsuid=%u"},
  41         {Opt_fsgid, "fsgid=%u"},
  42         {Opt_gid, "gid=%u"},
  43         {Opt_debug, "debug"},
  44         {Opt_mask, "mask=%u"},
  45         {Opt_userid, "userid=%d"},
  46         {Opt_multiuser, "multiuser"},
  47         {Opt_reserved_mb, "reserved_mb=%u"},
  48         {Opt_err, NULL}
  49 };
  50
  51 static int parse_options(struct super_block *sb, char *options, int silent,
  52                                 int *debug, struct sdcardfs_vfsmount_options *vfsopts,
  53                                 struct sdcardfs_mount_options *opts)
  54 {
  55         char *p;
  56         substring_t args[MAX_OPT_ARGS];
  57         int option;
  58
  59         /* by default, we use AID_MEDIA_RW as uid, gid */
  60         opts->fs_low_uid = AID_MEDIA_RW;
  61         opts->fs_low_gid = AID_MEDIA_RW;
  62         vfsopts->mask = 0;
  63         opts->mask = 0;
  64         opts->multiuser = false;
  65         opts->fs_user_id = 0;
  66         vfsopts->gid = 0;
  67         opts->gid = 0;
  68         /* by default, 0MB is reserved */
  69         opts->reserved_mb = 0;
  70
  71         *debug = 0;
  72
  73         if (!options)
  74                 return 0;
  75
  76         while ((p = strsep(&options, ",")) != NULL) {
  77                 int token;
  78                 if (!*p)
  79                         continue;
  80
  81                 token = match_token(p, sdcardfs_tokens, args);
  82
  83                 switch (token) {
  84                 case Opt_debug:
  85                         *debug = 1;
  86                         break;
  87                 case Opt_fsuid:
  88                         if (match_int(&args[0], &option))
  89                                 return 0;
  90                         opts->fs_low_uid = option;
  91                         break;
  92                 case Opt_fsgid:
  93                         if (match_int(&args[0], &option))
  94                                 return 0;
  95                         opts->fs_low_gid = option;
  96                         break;
  97                 case Opt_gid:
  98                         if (match_int(&args[0], &option))
  99                                 return 0;
 100                         opts->gid = option;
 101                         vfsopts->gid = option;
 102                         break;
 103                 case Opt_userid:
 104                         if (match_int(&args[0], &option))
 105                                 return 0;
 106                         opts->fs_user_id = option;
 107                         break;
 108                 case Opt_mask:
 109                         if (match_int(&args[0], &option))
 110                                 return 0;
 111                         opts->mask = option;
 112                         vfsopts->mask = option;
 113                         break;
 114                 case Opt_multiuser:
 115                         opts->multiuser = true;
 116                         break;
 117                 case Opt_reserved_mb:
 118                         if (match_int(&args[0], &option))
 119                                 return 0;
 120                         opts->reserved_mb = option;
 121                         break;
 122                 /* unknown option */
 123                 default:
 124                         if (!silent) {
 125                                 printk( KERN_ERR "Unrecognized mount option \"%s\" "
 126                                                 "or missing value", p);
 127                         }
 128                         return -EINVAL;
 129                 }
 130         }
 131
 132         if (*debug) {
 133                 printk( KERN_INFO "sdcardfs : options - debug:%d\n", *debug);
 134                 printk( KERN_INFO "sdcardfs : options - uid:%d\n",
 135                                                         opts->fs_low_uid);
 136                 printk( KERN_INFO "sdcardfs : options - gid:%d\n",
 137                                                         opts->fs_low_gid);
 138         }
 139
 140         return 0;
 141 }
 142
 143 int parse_options_remount(struct super_block *sb, char *options, int silent,
 144                                 struct sdcardfs_vfsmount_options *vfsopts)
 145 {
 146         char *p;
 147         substring_t args[MAX_OPT_ARGS];
 148         int option;
 149         int debug;
 150
 151         if (!options)
 152                 return 0;
 153
 154         while ((p = strsep(&options, ",")) != NULL) {
 155                 int token;
 156                 if (!*p)
 157                         continue;
 158
 159                 token = match_token(p, sdcardfs_tokens, args);
 160
 161                 switch (token) {
 162                 case Opt_debug:
 163                         debug = 1;
 164                         break;
 165                 case Opt_gid:
 166                         if (match_int(&args[0], &option))
 167                                 return 0;
 168                         vfsopts->gid = option;
 169
 170                         break;
 171                 case Opt_mask:
 172                         if (match_int(&args[0], &option))
 173                                 return 0;
 174                         vfsopts->mask = option;
 175                         break;
 176                 case Opt_multiuser:
 177                 case Opt_userid:
 178                 case Opt_fsuid:
 179                 case Opt_fsgid:
 180                 case Opt_reserved_mb:
 181                         printk( KERN_WARNING "Option \"%s\" can't be changed during remount\n", p);
 182                         break;
 183                 /* unknown option */
 184                 default:
 185                         if (!silent) {
 186                                 printk( KERN_ERR "Unrecognized mount option \"%s\" "
 187                                                 "or missing value", p);
 188                         }
 189                         return -EINVAL;
 190                 }
 191         }
 192
 193         if (debug) {
 194                 printk( KERN_INFO "sdcardfs : options - debug:%d\n", debug);
 195                 printk( KERN_INFO "sdcardfs : options - gid:%d\n", vfsopts->gid);
 196                 printk( KERN_INFO "sdcardfs : options - mask:%d\n", vfsopts->mask);
 197         }
 198
 199         return 0;
 200 }
 201
 202 #if 0
 203 /*
 204  * our custom d_alloc_root work-alike
 205  *
 206  * we can't use d_alloc_root if we want to use our own interpose function
 207  * unchanged, so we simply call our own "fake" d_alloc_root
 208  */
 209 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
 210 {
 211         struct dentry *ret = NULL;
 212
 213         if (sb) {
 214                 static const struct qstr name = {
 215                         .name = "/",
 216                         .len = 1
 217                 };
 218
 219                 ret = d_alloc(NULL, &name);
 220                 if (ret) {
 221                         d_set_d_op(ret, &sdcardfs_ci_dops);
 222                         ret->d_sb = sb;
 223                         ret->d_parent = ret;
 224                 }
 225         }
 226         return ret;
 227 }
 228 #endif
 229
 230 DEFINE_MUTEX(sdcardfs_super_list_lock);
 231 LIST_HEAD(sdcardfs_super_list);
 232 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
 233 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
 234
 235 /*
 236  * There is no need to lock the sdcardfs_super_info's rwsem as there is no
 237  * way anyone can have a reference to the superblock at this point in time.
 238  */
 239 static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
 240                 const char *dev_name, void *raw_data, int silent)
 241 {
 242         int err = 0;
 243         int debug;
 244         struct super_block *lower_sb;
 245         struct path lower_path;
 246         struct sdcardfs_sb_info *sb_info;
 247         struct sdcardfs_vfsmount_options *mnt_opt = mnt->data;
 248         struct inode *inode;
 249
 250         printk(KERN_INFO "sdcardfs version 2.0\n");
 251
 252         if (!dev_name) {
 253                 printk(KERN_ERR
 254                        "sdcardfs: read_super: missing dev_name argument\n");
 255                 err = -EINVAL;
 256                 goto out;
 257         }
 258
 259         printk(KERN_INFO "sdcardfs: dev_name -> %s\n", dev_name);
 260         printk(KERN_INFO "sdcardfs: options -> %s\n", (char *)raw_data);
 261
 262         /* parse lower path */
 263         err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
 264                         &lower_path);
 265         if (err) {
 266                 printk(KERN_ERR "sdcardfs: error accessing lower directory '%s'\n", dev_name);
 267                 goto out;
 268         }
 269
 270         /* allocate superblock private data */
 271         sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
 272         if (!SDCARDFS_SB(sb)) {
 273                 printk(KERN_CRIT "sdcardfs: read_super: out of memory\n");
 274                 err = -ENOMEM;
 275                 goto out_free;
 276         }
 277
 278         sb_info = sb->s_fs_info;
 279         /* parse options */
 280         err = parse_options(sb, raw_data, silent, &debug, mnt_opt, &sb_info->options);
 281         if (err) {
 282                 printk(KERN_ERR "sdcardfs: invalid options\n");
 283                 goto out_freesbi;
 284         }
 285
 286         /* set the lower superblock field of upper superblock */
 287         lower_sb = lower_path.dentry->d_sb;
 288         atomic_inc(&lower_sb->s_active);
 289         sdcardfs_set_lower_super(sb, lower_sb);
 290
 291         /* inherit maxbytes from lower file system */
 292         sb->s_maxbytes = lower_sb->s_maxbytes;
 293
 294         /*
 295          * Our c/m/atime granularity is 1 ns because we may stack on file
 296          * systems whose granularity is as good.
 297          */
 298         sb->s_time_gran = 1;
 299
 300         sb->s_magic = SDCARDFS_SUPER_MAGIC;
 301         sb->s_op = &sdcardfs_sops;
 302
 303         /* get a new inode and allocate our root dentry */
 304         inode = sdcardfs_iget(sb, lower_path.dentry->d_inode, 0);
 305         if (IS_ERR(inode)) {
 306                 err = PTR_ERR(inode);
 307                 goto out_sput;
 308         }
 309         sb->s_root = d_make_root(inode);
 310         if (!sb->s_root) {
 311                 err = -ENOMEM;
 312                 goto out_iput;
 313         }
 314         d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
 315
 316         /* link the upper and lower dentries */
 317         sb->s_root->d_fsdata = NULL;
 318         err = new_dentry_private_data(sb->s_root);
 319         if (err)
 320                 goto out_freeroot;
 321
 322         /* set the lower dentries for s_root */
 323         sdcardfs_set_lower_path(sb->s_root, &lower_path);
 324
 325         /*
 326          * No need to call interpose because we already have a positive
 327          * dentry, which was instantiated by d_make_root.  Just need to
 328          * d_rehash it.
 329          */
 330         d_rehash(sb->s_root);
 331
 332         /* setup permission policy */
 333         sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
 334         mutex_lock(&sdcardfs_super_list_lock);
 335         if(sb_info->options.multiuser) {
 336                 setup_derived_state(d_inode(sb->s_root), PERM_PRE_ROOT, sb_info->options.fs_user_id, AID_ROOT, false, d_inode(sb->s_root));
 337                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
 338                 /*err =  prepare_dir(sb_info->obbpath_s,
 339                                         sb_info->options.fs_low_uid,
 340                                         sb_info->options.fs_low_gid, 00755);*/
 341         } else {
 342                 setup_derived_state(d_inode(sb->s_root), PERM_ROOT, sb_info->options.fs_user_id, AID_ROOT, false, d_inode(sb->s_root));
 343                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
 344         }
 345         fix_derived_permission(sb->s_root->d_inode);
 346         sb_info->sb = sb;
 347         list_add(&sb_info->list, &sdcardfs_super_list);
 348         mutex_unlock(&sdcardfs_super_list_lock);
 349
 350         if (!silent)
 351                 printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
 352                                 dev_name, lower_sb->s_type->name);
 353         goto out; /* all is well */
 354
 355         /* no longer needed: free_dentry_private_data(sb->s_root); */
 356 out_freeroot:
 357         dput(sb->s_root);
 358 out_iput:
 359         iput(inode);
 360 out_sput:
 361         /* drop refs we took earlier */
 362         atomic_dec(&lower_sb->s_active);
 363 out_freesbi:
 364         kfree(SDCARDFS_SB(sb));
 365         sb->s_fs_info = NULL;
 366 out_free:
 367         path_put(&lower_path);
 368
 369 out:
 370         return err;
 371 }
 372
 373 /* A feature which supports mount_nodev() with options */
 374 static struct dentry *mount_nodev_with_options(struct vfsmount *mnt,
 375         struct file_system_type *fs_type, int flags, const char *dev_name, void *data,
 376         int (*fill_super)(struct vfsmount *, struct super_block *, const char *, void *, int))
 377
 378 {
 379         int error;
 380         struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL);
 381
 382         if (IS_ERR(s))
 383                 return ERR_CAST(s);
 384
 385         s->s_flags = flags;
 386
 387         error = fill_super(mnt, s, dev_name, data, flags & MS_SILENT ? 1 : 0);
 388         if (error) {
 389                 deactivate_locked_super(s);
 390                 return ERR_PTR(error);
 391         }
 392         s->s_flags |= MS_ACTIVE;
 393         return dget(s->s_root);
 394 }
 395
 396 static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
 397                 struct file_system_type *fs_type, int flags,
 398                             const char *dev_name, void *raw_data)
 399 {
 400         /*
 401          * dev_name is a lower_path_name,
 402          * raw_data is a option string.
 403          */
 404         return mount_nodev_with_options(mnt, fs_type, flags, dev_name,
 405                                                 raw_data, sdcardfs_read_super);
 406 }
 407
 408 static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type, int flags,
 409                     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
 415 void *sdcardfs_alloc_mnt_data(void) {
 416         return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
 417 }
 418
 419 void sdcardfs_kill_sb(struct super_block *sb) {
 420         struct sdcardfs_sb_info *sbi;
 421         if (sb->s_magic == SDCARDFS_SUPER_MAGIC) {
 422                 sbi = SDCARDFS_SB(sb);
 423                 mutex_lock(&sdcardfs_super_list_lock);
 424                 list_del(&sbi->list);
 425                 mutex_unlock(&sdcardfs_super_list_lock);
 426         }
 427         generic_shutdown_super(sb);
 428 }
 429
 430 static struct file_system_type sdcardfs_fs_type = {
 431         .owner          = THIS_MODULE,
 432         .name           = SDCARDFS_NAME,
 433         .mount          = sdcardfs_mount_wrn,
 434         .mount2         = sdcardfs_mount,
 435         .alloc_mnt_data = sdcardfs_alloc_mnt_data,
 436         .kill_sb        = sdcardfs_kill_sb,
 437         .fs_flags       = 0,
 438 };
 439
 440 static int __init init_sdcardfs_fs(void)
 441 {
 442         int err;
 443
 444         pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
 445
 446         err = sdcardfs_init_inode_cache();
 447         if (err)
 448                 goto out;
 449         err = sdcardfs_init_dentry_cache();
 450         if (err)
 451                 goto out;
 452         err = packagelist_init();
 453         if (err)
 454                 goto out;
 455         err = register_filesystem(&sdcardfs_fs_type);
 456 out:
 457         if (err) {
 458                 sdcardfs_destroy_inode_cache();
 459                 sdcardfs_destroy_dentry_cache();
 460                 packagelist_exit();
 461         }
 462         return err;
 463 }
 464
 465 static void __exit exit_sdcardfs_fs(void)
 466 {
 467         sdcardfs_destroy_inode_cache();
 468         sdcardfs_destroy_dentry_cache();
 469         packagelist_exit();
 470         unregister_filesystem(&sdcardfs_fs_type);
 471         pr_info("Completed sdcardfs module unload\n");
 472 }
 473
 474 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
 475               " (http://www.fsl.cs.sunysb.edu/)");
 476 MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
 477                    " (http://wrapfs.filesystems.org/)");
 478 MODULE_LICENSE("GPL");
 479
 480 module_init(init_sdcardfs_fs);
 481 module_exit(exit_sdcardfs_fs);