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         sb->s_stack_depth = lower_sb->s_stack_depth + 1;
 288         if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
 289                 pr_err("sdcardfs: maximum fs stacking depth exceeded\n");
 290                 err = -EINVAL;
 291                 goto out_sput;
 292         }
 293
 294         /* inherit maxbytes from lower file system */
 295         sb->s_maxbytes = lower_sb->s_maxbytes;
 296
 297         /*
 298          * Our c/m/atime granularity is 1 ns because we may stack on file
 299          * systems whose granularity is as good.
 300          */
 301         sb->s_time_gran = 1;
 302
 303         sb->s_magic = SDCARDFS_SUPER_MAGIC;
 304         sb->s_op = &sdcardfs_sops;
 305
 306         /* get a new inode and allocate our root dentry */
 307         inode = sdcardfs_iget(sb, lower_path.dentry->d_inode, 0);
 308         if (IS_ERR(inode)) {
 309                 err = PTR_ERR(inode);
 310                 goto out_sput;
 311         }
 312         sb->s_root = d_make_root(inode);
 313         if (!sb->s_root) {
 314                 err = -ENOMEM;
 315                 goto out_iput;
 316         }
 317         d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
 318
 319         /* link the upper and lower dentries */
 320         sb->s_root->d_fsdata = NULL;
 321         err = new_dentry_private_data(sb->s_root);
 322         if (err)
 323                 goto out_freeroot;
 324
 325         /* set the lower dentries for s_root */
 326         sdcardfs_set_lower_path(sb->s_root, &lower_path);
 327
 328         /*
 329          * No need to call interpose because we already have a positive
 330          * dentry, which was instantiated by d_make_root.  Just need to
 331          * d_rehash it.
 332          */
 333         d_rehash(sb->s_root);
 334
 335         /* setup permission policy */
 336         sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
 337         mutex_lock(&sdcardfs_super_list_lock);
 338         if(sb_info->options.multiuser) {
 339                 setup_derived_state(sb->s_root->d_inode, PERM_PRE_ROOT, sb_info->options.fs_user_id, AID_ROOT, false, sb->s_root->d_inode);
 340                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
 341                 /*err =  prepare_dir(sb_info->obbpath_s,
 342                                         sb_info->options.fs_low_uid,
 343                                         sb_info->options.fs_low_gid, 00755);*/
 344         } else {
 345                 setup_derived_state(sb->s_root->d_inode, PERM_ROOT, sb_info->options.fs_user_id, AID_ROOT, false, sb->s_root->d_inode);
 346                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
 347         }
 348         fixup_tmp_permissions(sb->s_root->d_inode);
 349         sb_info->sb = sb;
 350         list_add(&sb_info->list, &sdcardfs_super_list);
 351         mutex_unlock(&sdcardfs_super_list_lock);
 352
 353         if (!silent)
 354                 printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
 355                                 dev_name, lower_sb->s_type->name);
 356         goto out; /* all is well */
 357
 358         /* no longer needed: free_dentry_private_data(sb->s_root); */
 359 out_freeroot:
 360         dput(sb->s_root);
 361 out_iput:
 362         iput(inode);
 363 out_sput:
 364         /* drop refs we took earlier */
 365         atomic_dec(&lower_sb->s_active);
 366 out_freesbi:
 367         kfree(SDCARDFS_SB(sb));
 368         sb->s_fs_info = NULL;
 369 out_free:
 370         path_put(&lower_path);
 371
 372 out:
 373         return err;
 374 }
 375
 376 /* A feature which supports mount_nodev() with options */
 377 static struct dentry *mount_nodev_with_options(struct vfsmount *mnt,
 378         struct file_system_type *fs_type, int flags, const char *dev_name, void *data,
 379         int (*fill_super)(struct vfsmount *, struct super_block *, const char *, void *, int))
 380
 381 {
 382         int error;
 383         struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL);
 384
 385         if (IS_ERR(s))
 386                 return ERR_CAST(s);
 387
 388         s->s_flags = flags;
 389
 390         error = fill_super(mnt, s, dev_name, data, flags & MS_SILENT ? 1 : 0);
 391         if (error) {
 392                 deactivate_locked_super(s);
 393                 return ERR_PTR(error);
 394         }
 395         s->s_flags |= MS_ACTIVE;
 396         return dget(s->s_root);
 397 }
 398
 399 static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
 400                 struct file_system_type *fs_type, int flags,
 401                             const char *dev_name, void *raw_data)
 402 {
 403         /*
 404          * dev_name is a lower_path_name,
 405          * raw_data is a option string.
 406          */
 407         return mount_nodev_with_options(mnt, fs_type, flags, dev_name,
 408                                                 raw_data, sdcardfs_read_super);
 409 }
 410
 411 static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type, int flags,
 412                     const char *dev_name, void *raw_data)
 413 {
 414         WARN(1, "sdcardfs does not support mount. Use mount2.\n");
 415         return ERR_PTR(-EINVAL);
 416 }
 417
 418 void *sdcardfs_alloc_mnt_data(void) {
 419         return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
 420 }
 421
 422 void sdcardfs_kill_sb(struct super_block *sb) {
 423         struct sdcardfs_sb_info *sbi;
 424         if (sb->s_magic == SDCARDFS_SUPER_MAGIC) {
 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         generic_shutdown_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
 443 static int __init init_sdcardfs_fs(void)
 444 {
 445         int err;
 446
 447         pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
 448
 449         err = sdcardfs_init_inode_cache();
 450         if (err)
 451                 goto out;
 452         err = sdcardfs_init_dentry_cache();
 453         if (err)
 454                 goto out;
 455         err = packagelist_init();
 456         if (err)
 457                 goto out;
 458         err = register_filesystem(&sdcardfs_fs_type);
 459 out:
 460         if (err) {
 461                 sdcardfs_destroy_inode_cache();
 462                 sdcardfs_destroy_dentry_cache();
 463                 packagelist_exit();
 464         }
 465         return err;
 466 }
 467
 468 static void __exit exit_sdcardfs_fs(void)
 469 {
 470         sdcardfs_destroy_inode_cache();
 471         sdcardfs_destroy_dentry_cache();
 472         packagelist_exit();
 473         unregister_filesystem(&sdcardfs_fs_type);
 474         pr_info("Completed sdcardfs module unload\n");
 475 }
 476
 477 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
 478               " (http://www.fsl.cs.sunysb.edu/)");
 479 MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
 480                    " (http://wrapfs.filesystems.org/)");
 481 MODULE_LICENSE("GPL");
 482
 483 module_init(init_sdcardfs_fs);
 484 module_exit(exit_sdcardfs_fs);