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_mask,
  32         Opt_multiuser, // May need?
  33         Opt_userid,
  34         Opt_reserved_mb,
  35         Opt_err,
  36 };
  37
  38 static const match_table_t sdcardfs_tokens = {
  39         {Opt_fsuid, "fsuid=%u"},
  40         {Opt_fsgid, "fsgid=%u"},
  41         {Opt_gid, "gid=%u"},
  42         {Opt_debug, "debug"},
  43         {Opt_mask, "mask=%u"},
  44         {Opt_userid, "userid=%d"},
  45         {Opt_multiuser, "multiuser"},
  46         {Opt_reserved_mb, "reserved_mb=%u"},
  47         {Opt_err, NULL}
  48 };
  49
  50 static int parse_options(struct super_block *sb, char *options, int silent,
  51                                 int *debug, struct sdcardfs_vfsmount_options *vfsopts,
  52                                 struct sdcardfs_mount_options *opts)
  53 {
  54         char *p;
  55         substring_t args[MAX_OPT_ARGS];
  56         int option;
  57
  58         /* by default, we use AID_MEDIA_RW as uid, gid */
  59         opts->fs_low_uid = AID_MEDIA_RW;
  60         opts->fs_low_gid = AID_MEDIA_RW;
  61         vfsopts->mask = 0;
  62         opts->multiuser = false;
  63         opts->fs_user_id = 0;
  64         vfsopts->gid = 0;
  65         /* by default, 0MB is reserved */
  66         opts->reserved_mb = 0;
  67
  68         *debug = 0;
  69
  70         if (!options)
  71                 return 0;
  72
  73         while ((p = strsep(&options, ",")) != NULL) {
  74                 int token;
  75                 if (!*p)
  76                         continue;
  77
  78                 token = match_token(p, sdcardfs_tokens, args);
  79
  80                 switch (token) {
  81                 case Opt_debug:
  82                         *debug = 1;
  83                         break;
  84                 case Opt_fsuid:
  85                         if (match_int(&args[0], &option))
  86                                 return 0;
  87                         opts->fs_low_uid = option;
  88                         break;
  89                 case Opt_fsgid:
  90                         if (match_int(&args[0], &option))
  91                                 return 0;
  92                         opts->fs_low_gid = option;
  93                         break;
  94                 case Opt_gid:
  95                         if (match_int(&args[0], &option))
  96                                 return 0;
  97                         vfsopts->gid = option;
  98                         break;
  99                 case Opt_userid:
 100                         if (match_int(&args[0], &option))
 101                                 return 0;
 102                         opts->fs_user_id = option;
 103                         break;
 104                 case Opt_mask:
 105                         if (match_int(&args[0], &option))
 106                                 return 0;
 107                         vfsopts->mask = option;
 108                         break;
 109                 case Opt_multiuser:
 110                         opts->multiuser = true;
 111                         break;
 112                 case Opt_reserved_mb:
 113                         if (match_int(&args[0], &option))
 114                                 return 0;
 115                         opts->reserved_mb = option;
 116                         break;
 117                 /* unknown option */
 118                 default:
 119                         if (!silent) {
 120                                 printk( KERN_ERR "Unrecognized mount option \"%s\" "
 121                                                 "or missing value", p);
 122                         }
 123                         return -EINVAL;
 124                 }
 125         }
 126
 127         if (*debug) {
 128                 printk( KERN_INFO "sdcardfs : options - debug:%d\n", *debug);
 129                 printk( KERN_INFO "sdcardfs : options - uid:%d\n",
 130                                                         opts->fs_low_uid);
 131                 printk( KERN_INFO "sdcardfs : options - gid:%d\n",
 132                                                         opts->fs_low_gid);
 133         }
 134
 135         return 0;
 136 }
 137
 138 int parse_options_remount(struct super_block *sb, char *options, int silent,
 139                                 struct sdcardfs_vfsmount_options *vfsopts)
 140 {
 141         char *p;
 142         substring_t args[MAX_OPT_ARGS];
 143         int option;
 144         int debug;
 145
 146         if (!options)
 147                 return 0;
 148
 149         while ((p = strsep(&options, ",")) != NULL) {
 150                 int token;
 151                 if (!*p)
 152                         continue;
 153
 154                 token = match_token(p, sdcardfs_tokens, args);
 155
 156                 switch (token) {
 157                 case Opt_debug:
 158                         debug = 1;
 159                         break;
 160                 case Opt_gid:
 161                         if (match_int(&args[0], &option))
 162                                 return 0;
 163                         vfsopts->gid = option;
 164
 165                         break;
 166                 case Opt_mask:
 167                         if (match_int(&args[0], &option))
 168                                 return 0;
 169                         vfsopts->mask = option;
 170                         break;
 171                 case Opt_multiuser:
 172                 case Opt_userid:
 173                 case Opt_fsuid:
 174                 case Opt_fsgid:
 175                 case Opt_reserved_mb:
 176                         printk( KERN_WARNING "Option \"%s\" can't be changed during remount\n", p);
 177                         break;
 178                 /* unknown option */
 179                 default:
 180                         if (!silent) {
 181                                 printk( KERN_ERR "Unrecognized mount option \"%s\" "
 182                                                 "or missing value", p);
 183                         }
 184                         return -EINVAL;
 185                 }
 186         }
 187
 188         if (debug) {
 189                 printk( KERN_INFO "sdcardfs : options - debug:%d\n", debug);
 190                 printk( KERN_INFO "sdcardfs : options - gid:%d\n", vfsopts->gid);
 191                 printk( KERN_INFO "sdcardfs : options - mask:%d\n", vfsopts->mask);
 192         }
 193
 194         return 0;
 195 }
 196
 197 #if 0
 198 /*
 199  * our custom d_alloc_root work-alike
 200  *
 201  * we can't use d_alloc_root if we want to use our own interpose function
 202  * unchanged, so we simply call our own "fake" d_alloc_root
 203  */
 204 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
 205 {
 206         struct dentry *ret = NULL;
 207
 208         if (sb) {
 209                 static const struct qstr name = {
 210                         .name = "/",
 211                         .len = 1
 212                 };
 213
 214                 ret = d_alloc(NULL, &name);
 215                 if (ret) {
 216                         d_set_d_op(ret, &sdcardfs_ci_dops);
 217                         ret->d_sb = sb;
 218                         ret->d_parent = ret;
 219                 }
 220         }
 221         return ret;
 222 }
 223 #endif
 224
 225 DEFINE_MUTEX(sdcardfs_super_list_lock);
 226 LIST_HEAD(sdcardfs_super_list);
 227 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
 228 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
 229
 230 /*
 231  * There is no need to lock the sdcardfs_super_info's rwsem as there is no
 232  * way anyone can have a reference to the superblock at this point in time.
 233  */
 234 static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
 235                 const char *dev_name, void *raw_data, int silent)
 236 {
 237         int err = 0;
 238         int debug;
 239         struct super_block *lower_sb;
 240         struct path lower_path;
 241         struct sdcardfs_sb_info *sb_info;
 242         struct sdcardfs_vfsmount_options *mnt_opt = mnt->data;
 243         struct inode *inode;
 244
 245         printk(KERN_INFO "sdcardfs version 2.0\n");
 246
 247         if (!dev_name) {
 248                 printk(KERN_ERR
 249                        "sdcardfs: read_super: missing dev_name argument\n");
 250                 err = -EINVAL;
 251                 goto out;
 252         }
 253
 254         printk(KERN_INFO "sdcardfs: dev_name -> %s\n", dev_name);
 255         printk(KERN_INFO "sdcardfs: options -> %s\n", (char *)raw_data);
 256         printk(KERN_INFO "sdcardfs: mnt -> %p\n", mnt);
 257
 258         /* parse lower path */
 259         err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
 260                         &lower_path);
 261         if (err) {
 262                 printk(KERN_ERR "sdcardfs: error accessing lower directory '%s'\n", dev_name);
 263                 goto out;
 264         }
 265
 266         /* allocate superblock private data */
 267         sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
 268         if (!SDCARDFS_SB(sb)) {
 269                 printk(KERN_CRIT "sdcardfs: read_super: out of memory\n");
 270                 err = -ENOMEM;
 271                 goto out_free;
 272         }
 273
 274         sb_info = sb->s_fs_info;
 275         /* parse options */
 276         err = parse_options(sb, raw_data, silent, &debug, mnt_opt, &sb_info->options);
 277         if (err) {
 278                 printk(KERN_ERR "sdcardfs: invalid options\n");
 279                 goto out_freesbi;
 280         }
 281
 282         /* set the lower superblock field of upper superblock */
 283         lower_sb = lower_path.dentry->d_sb;
 284         atomic_inc(&lower_sb->s_active);
 285         sdcardfs_set_lower_super(sb, lower_sb);
 286
 287         /* inherit maxbytes from lower file system */
 288         sb->s_maxbytes = lower_sb->s_maxbytes;
 289
 290         /*
 291          * Our c/m/atime granularity is 1 ns because we may stack on file
 292          * systems whose granularity is as good.
 293          */
 294         sb->s_time_gran = 1;
 295
 296         sb->s_magic = SDCARDFS_SUPER_MAGIC;
 297         sb->s_op = &sdcardfs_sops;
 298
 299         /* get a new inode and allocate our root dentry */
 300         inode = sdcardfs_iget(sb, d_inode(lower_path.dentry), 0);
 301         if (IS_ERR(inode)) {
 302                 err = PTR_ERR(inode);
 303                 goto out_sput;
 304         }
 305         sb->s_root = d_make_root(inode);
 306         if (!sb->s_root) {
 307                 err = -ENOMEM;
 308                 goto out_iput;
 309         }
 310         d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
 311
 312         /* link the upper and lower dentries */
 313         sb->s_root->d_fsdata = NULL;
 314         err = new_dentry_private_data(sb->s_root);
 315         if (err)
 316                 goto out_freeroot;
 317
 318         /* set the lower dentries for s_root */
 319         sdcardfs_set_lower_path(sb->s_root, &lower_path);
 320
 321         /*
 322          * No need to call interpose because we already have a positive
 323          * dentry, which was instantiated by d_make_root.  Just need to
 324          * d_rehash it.
 325          */
 326         d_rehash(sb->s_root);
 327
 328         /* setup permission policy */
 329         sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
 330         mutex_lock(&sdcardfs_super_list_lock);
 331         if(sb_info->options.multiuser) {
 332                 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));
 333                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
 334                 /*err =  prepare_dir(sb_info->obbpath_s,
 335                                         sb_info->options.fs_low_uid,
 336                                         sb_info->options.fs_low_gid, 00755);*/
 337         } else {
 338                 setup_derived_state(d_inode(sb->s_root), PERM_ROOT, sb_info->options.fs_user_id, AID_ROOT, false, d_inode(sb->s_root));
 339                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
 340         }
 341         fixup_tmp_permissions(d_inode(sb->s_root));
 342         sb_info->sb = sb;
 343         list_add(&sb_info->list, &sdcardfs_super_list);
 344         mutex_unlock(&sdcardfs_super_list_lock);
 345
 346         if (!silent)
 347                 printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
 348                                 dev_name, lower_sb->s_type->name);
 349         goto out; /* all is well */
 350
 351         /* no longer needed: free_dentry_private_data(sb->s_root); */
 352 out_freeroot:
 353         dput(sb->s_root);
 354 out_iput:
 355         iput(inode);
 356 out_sput:
 357         /* drop refs we took earlier */
 358         atomic_dec(&lower_sb->s_active);
 359 out_freesbi:
 360         kfree(SDCARDFS_SB(sb));
 361         sb->s_fs_info = NULL;
 362 out_free:
 363         path_put(&lower_path);
 364
 365 out:
 366         return err;
 367 }
 368
 369 /* A feature which supports mount_nodev() with options */
 370 static struct dentry *mount_nodev_with_options(struct vfsmount *mnt,
 371         struct file_system_type *fs_type, int flags, const char *dev_name, void *data,
 372         int (*fill_super)(struct vfsmount *, struct super_block *, const char *, void *, int))
 373
 374 {
 375         int error;
 376         struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL);
 377
 378         if (IS_ERR(s))
 379                 return ERR_CAST(s);
 380
 381         s->s_flags = flags;
 382
 383         error = fill_super(mnt, s, dev_name, data, flags & MS_SILENT ? 1 : 0);
 384         if (error) {
 385                 deactivate_locked_super(s);
 386                 return ERR_PTR(error);
 387         }
 388         s->s_flags |= MS_ACTIVE;
 389         return dget(s->s_root);
 390 }
 391
 392 static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
 393                 struct file_system_type *fs_type, int flags,
 394                             const char *dev_name, void *raw_data)
 395 {
 396         /*
 397          * dev_name is a lower_path_name,
 398          * raw_data is a option string.
 399          */
 400         return mount_nodev_with_options(mnt, fs_type, flags, dev_name,
 401                                                 raw_data, sdcardfs_read_super);
 402 }
 403
 404 static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type, int flags,
 405                     const char *dev_name, void *raw_data)
 406 {
 407         WARN(1, "sdcardfs does not support mount. Use mount2.\n");
 408         return ERR_PTR(-EINVAL);
 409 }
 410
 411 void *sdcardfs_alloc_mnt_data(void) {
 412         return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
 413 }
 414
 415 void sdcardfs_kill_sb(struct super_block *sb) {
 416         struct sdcardfs_sb_info *sbi;
 417         if (sb->s_magic == SDCARDFS_SUPER_MAGIC) {
 418                 sbi = SDCARDFS_SB(sb);
 419                 mutex_lock(&sdcardfs_super_list_lock);
 420                 list_del(&sbi->list);
 421                 mutex_unlock(&sdcardfs_super_list_lock);
 422         }
 423         generic_shutdown_super(sb);
 424 }
 425
 426 static struct file_system_type sdcardfs_fs_type = {
 427         .owner          = THIS_MODULE,
 428         .name           = SDCARDFS_NAME,
 429         .mount          = sdcardfs_mount_wrn,
 430         .mount2         = sdcardfs_mount,
 431         .alloc_mnt_data = sdcardfs_alloc_mnt_data,
 432         .kill_sb        = sdcardfs_kill_sb,
 433         .fs_flags       = 0,
 434 };
 435
 436 static int __init init_sdcardfs_fs(void)
 437 {
 438         int err;
 439
 440         pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
 441
 442         err = sdcardfs_init_inode_cache();
 443         if (err)
 444                 goto out;
 445         err = sdcardfs_init_dentry_cache();
 446         if (err)
 447                 goto out;
 448         err = packagelist_init();
 449         if (err)
 450                 goto out;
 451         err = register_filesystem(&sdcardfs_fs_type);
 452 out:
 453         if (err) {
 454                 sdcardfs_destroy_inode_cache();
 455                 sdcardfs_destroy_dentry_cache();
 456                 packagelist_exit();
 457         }
 458         return err;
 459 }
 460
 461 static void __exit exit_sdcardfs_fs(void)
 462 {
 463         sdcardfs_destroy_inode_cache();
 464         sdcardfs_destroy_dentry_cache();
 465         packagelist_exit();
 466         unregister_filesystem(&sdcardfs_fs_type);
 467         pr_info("Completed sdcardfs module unload\n");
 468 }
 469
 470 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
 471               " (http://www.fsl.cs.sunysb.edu/)");
 472 MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
 473                    " (http://wrapfs.filesystems.org/)");
 474 MODULE_LICENSE("GPL");
 475
 476 module_init(init_sdcardfs_fs);
 477 module_exit(exit_sdcardfs_fs);