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,
  33         Opt_userid,
  34         Opt_reserved_mb,
  35         Opt_gid_derivation,
  36         Opt_default_normal,
  37         Opt_nocache,
  38         Opt_err,
  39 };
  40
  41 static const match_table_t sdcardfs_tokens = {
  42         {Opt_fsuid, "fsuid=%u"},
  43         {Opt_fsgid, "fsgid=%u"},
  44         {Opt_gid, "gid=%u"},
  45         {Opt_debug, "debug"},
  46         {Opt_mask, "mask=%u"},
  47         {Opt_userid, "userid=%d"},
  48         {Opt_multiuser, "multiuser"},
  49         {Opt_gid_derivation, "derive_gid"},
  50         {Opt_default_normal, "default_normal"},
  51         {Opt_reserved_mb, "reserved_mb=%u"},
  52         {Opt_nocache, "nocache"},
  53         {Opt_err, NULL}
  54 };
  55
  56 static int parse_options(struct super_block *sb, char *options, int silent,
  57                                 int *debug, struct sdcardfs_vfsmount_options *vfsopts,
  58                                 struct sdcardfs_mount_options *opts)
  59 {
  60         char *p;
  61         substring_t args[MAX_OPT_ARGS];
  62         int option;
  63
  64         /* by default, we use AID_MEDIA_RW as uid, gid */
  65         opts->fs_low_uid = AID_MEDIA_RW;
  66         opts->fs_low_gid = AID_MEDIA_RW;
  67         vfsopts->mask = 0;
  68         opts->multiuser = false;
  69         opts->fs_user_id = 0;
  70         vfsopts->gid = 0;
  71         /* by default, 0MB is reserved */
  72         opts->reserved_mb = 0;
  73         /* by default, gid derivation is off */
  74         opts->gid_derivation = false;
  75         opts->default_normal = false;
  76         opts->nocache = false;
  77
  78         *debug = 0;
  79
  80         if (!options)
  81                 return 0;
  82
  83         while ((p = strsep(&options, ",")) != NULL) {
  84                 int token;
  85
  86                 if (!*p)
  87                         continue;
  88
  89                 token = match_token(p, sdcardfs_tokens, args);
  90
  91                 switch (token) {
  92                 case Opt_debug:
  93                         *debug = 1;
  94                         break;
  95                 case Opt_fsuid:
  96                         if (match_int(&args[0], &option))
  97                                 return 0;
  98                         opts->fs_low_uid = option;
  99                         break;
 100                 case Opt_fsgid:
 101                         if (match_int(&args[0], &option))
 102                                 return 0;
 103                         opts->fs_low_gid = option;
 104                         break;
 105                 case Opt_gid:
 106                         if (match_int(&args[0], &option))
 107                                 return 0;
 108                         vfsopts->gid = option;
 109                         break;
 110                 case Opt_userid:
 111                         if (match_int(&args[0], &option))
 112                                 return 0;
 113                         opts->fs_user_id = option;
 114                         break;
 115                 case Opt_mask:
 116                         if (match_int(&args[0], &option))
 117                                 return 0;
 118                         vfsopts->mask = option;
 119                         break;
 120                 case Opt_multiuser:
 121                         opts->multiuser = true;
 122                         break;
 123                 case Opt_reserved_mb:
 124                         if (match_int(&args[0], &option))
 125                                 return 0;
 126                         opts->reserved_mb = option;
 127                         break;
 128                 case Opt_gid_derivation:
 129                         opts->gid_derivation = true;
 130                         break;
 131                 case Opt_default_normal:
 132                         opts->default_normal = true;
 133                         break;
 134                 case Opt_nocache:
 135                         opts->nocache = true;
 136                         break;
 137                 /* unknown option */
 138                 default:
 139                         if (!silent)
 140                                 pr_err("Unrecognized mount option \"%s\" or missing value", p);
 141                         return -EINVAL;
 142                 }
 143         }
 144
 145         if (*debug) {
 146                 pr_info("sdcardfs : options - debug:%d\n", *debug);
 147                 pr_info("sdcardfs : options - uid:%d\n",
 148                                                         opts->fs_low_uid);
 149                 pr_info("sdcardfs : options - gid:%d\n",
 150                                                         opts->fs_low_gid);
 151         }
 152
 153         return 0;
 154 }
 155
 156 int parse_options_remount(struct super_block *sb, char *options, int silent,
 157                                 struct sdcardfs_vfsmount_options *vfsopts)
 158 {
 159         char *p;
 160         substring_t args[MAX_OPT_ARGS];
 161         int option;
 162         int debug;
 163
 164         if (!options)
 165                 return 0;
 166
 167         while ((p = strsep(&options, ",")) != NULL) {
 168                 int token;
 169
 170                 if (!*p)
 171                         continue;
 172
 173                 token = match_token(p, sdcardfs_tokens, args);
 174
 175                 switch (token) {
 176                 case Opt_debug:
 177                         debug = 1;
 178                         break;
 179                 case Opt_gid:
 180                         if (match_int(&args[0], &option))
 181                                 return 0;
 182                         vfsopts->gid = option;
 183
 184                         break;
 185                 case Opt_mask:
 186                         if (match_int(&args[0], &option))
 187                                 return 0;
 188                         vfsopts->mask = option;
 189                         break;
 190                 case Opt_default_normal:
 191                 case Opt_multiuser:
 192                 case Opt_userid:
 193                 case Opt_fsuid:
 194                 case Opt_fsgid:
 195                 case Opt_reserved_mb:
 196                         pr_warn("Option \"%s\" can't be changed during remount\n", p);
 197                         break;
 198                 /* unknown option */
 199                 default:
 200                         if (!silent)
 201                                 pr_err("Unrecognized mount option \"%s\" or missing value", p);
 202                         return -EINVAL;
 203                 }
 204         }
 205
 206         if (debug) {
 207                 pr_info("sdcardfs : options - debug:%d\n", debug);
 208                 pr_info("sdcardfs : options - gid:%d\n", vfsopts->gid);
 209                 pr_info("sdcardfs : options - mask:%d\n", vfsopts->mask);
 210         }
 211
 212         return 0;
 213 }
 214
 215 #if 0
 216 /*
 217  * our custom d_alloc_root work-alike
 218  *
 219  * we can't use d_alloc_root if we want to use our own interpose function
 220  * unchanged, so we simply call our own "fake" d_alloc_root
 221  */
 222 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
 223 {
 224         struct dentry *ret = NULL;
 225
 226         if (sb) {
 227                 static const struct qstr name = {
 228                         .name = "/",
 229                         .len = 1
 230                 };
 231
 232                 ret = d_alloc(NULL, &name);
 233                 if (ret) {
 234                         d_set_d_op(ret, &sdcardfs_ci_dops);
 235                         ret->d_sb = sb;
 236                         ret->d_parent = ret;
 237                 }
 238         }
 239         return ret;
 240 }
 241 #endif
 242
 243 DEFINE_MUTEX(sdcardfs_super_list_lock);
 244 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
 245 LIST_HEAD(sdcardfs_super_list);
 246 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
 247
 248 /*
 249  * There is no need to lock the sdcardfs_super_info's rwsem as there is no
 250  * way anyone can have a reference to the superblock at this point in time.
 251  */
 252 static int sdcardfs_read_super(struct vfsmount *mnt, struct super_block *sb,
 253                 const char *dev_name, void *raw_data, int silent)
 254 {
 255         int err = 0;
 256         int debug;
 257         struct super_block *lower_sb;
 258         struct path lower_path;
 259         struct sdcardfs_sb_info *sb_info;
 260         struct sdcardfs_vfsmount_options *mnt_opt = mnt->data;
 261         struct inode *inode;
 262
 263         pr_info("sdcardfs version 2.0\n");
 264
 265         if (!dev_name) {
 266                 pr_err("sdcardfs: read_super: missing dev_name argument\n");
 267                 err = -EINVAL;
 268                 goto out;
 269         }
 270
 271         pr_info("sdcardfs: dev_name -> %s\n", dev_name);
 272         pr_info("sdcardfs: options -> %s\n", (char *)raw_data);
 273         pr_info("sdcardfs: mnt -> %p\n", mnt);
 274
 275         /* parse lower path */
 276         err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
 277                         &lower_path);
 278         if (err) {
 279                 pr_err("sdcardfs: error accessing lower directory '%s'\n", dev_name);
 280                 goto out;
 281         }
 282
 283         /* allocate superblock private data */
 284         sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
 285         if (!SDCARDFS_SB(sb)) {
 286                 pr_crit("sdcardfs: read_super: out of memory\n");
 287                 err = -ENOMEM;
 288                 goto out_free;
 289         }
 290
 291         sb_info = sb->s_fs_info;
 292         /* parse options */
 293         err = parse_options(sb, raw_data, silent, &debug, mnt_opt, &sb_info->options);
 294         if (err) {
 295                 pr_err("sdcardfs: invalid options\n");
 296                 goto out_freesbi;
 297         }
 298
 299         /* set the lower superblock field of upper superblock */
 300         lower_sb = lower_path.dentry->d_sb;
 301         atomic_inc(&lower_sb->s_active);
 302         sdcardfs_set_lower_super(sb, lower_sb);
 303
 304         sb->s_stack_depth = lower_sb->s_stack_depth + 1;
 305         if (sb->s_stack_depth > FILESYSTEM_MAX_STACK_DEPTH) {
 306                 pr_err("sdcardfs: maximum fs stacking depth exceeded\n");
 307                 err = -EINVAL;
 308                 goto out_sput;
 309         }
 310
 311         /* inherit maxbytes from lower file system */
 312         sb->s_maxbytes = lower_sb->s_maxbytes;
 313
 314         /*
 315          * Our c/m/atime granularity is 1 ns because we may stack on file
 316          * systems whose granularity is as good.
 317          */
 318         sb->s_time_gran = 1;
 319
 320         sb->s_magic = SDCARDFS_SUPER_MAGIC;
 321         sb->s_op = &sdcardfs_sops;
 322
 323         /* get a new inode and allocate our root dentry */
 324         inode = sdcardfs_iget(sb, d_inode(lower_path.dentry), 0);
 325         if (IS_ERR(inode)) {
 326                 err = PTR_ERR(inode);
 327                 goto out_sput;
 328         }
 329         sb->s_root = d_make_root(inode);
 330         if (!sb->s_root) {
 331                 err = -ENOMEM;
 332                 goto out_sput;
 333         }
 334         d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
 335
 336         /* link the upper and lower dentries */
 337         sb->s_root->d_fsdata = NULL;
 338         err = new_dentry_private_data(sb->s_root);
 339         if (err)
 340                 goto out_freeroot;
 341
 342         /* set the lower dentries for s_root */
 343         sdcardfs_set_lower_path(sb->s_root, &lower_path);
 344
 345         /*
 346          * No need to call interpose because we already have a positive
 347          * dentry, which was instantiated by d_make_root.  Just need to
 348          * d_rehash it.
 349          */
 350         d_rehash(sb->s_root);
 351
 352         /* setup permission policy */
 353         sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
 354         mutex_lock(&sdcardfs_super_list_lock);
 355         if (sb_info->options.multiuser) {
 356                 setup_derived_state(d_inode(sb->s_root), PERM_PRE_ROOT,
 357                                 sb_info->options.fs_user_id, AID_ROOT);
 358                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
 359         } else {
 360                 setup_derived_state(d_inode(sb->s_root), PERM_ROOT,
 361                                 sb_info->options.fs_user_id, AID_ROOT);
 362                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
 363         }
 364         fixup_tmp_permissions(d_inode(sb->s_root));
 365         sb_info->sb = sb;
 366         list_add(&sb_info->list, &sdcardfs_super_list);
 367         mutex_unlock(&sdcardfs_super_list_lock);
 368
 369         if (!silent)
 370                 pr_info("sdcardfs: mounted on top of %s type %s\n",
 371                                 dev_name, lower_sb->s_type->name);
 372         goto out; /* all is well */
 373
 374         /* no longer needed: free_dentry_private_data(sb->s_root); */
 375 out_freeroot:
 376         dput(sb->s_root);
 377         sb->s_root = NULL;
 378 out_sput:
 379         /* drop refs we took earlier */
 380         atomic_dec(&lower_sb->s_active);
 381 out_freesbi:
 382         kfree(SDCARDFS_SB(sb));
 383         sb->s_fs_info = NULL;
 384 out_free:
 385         path_put(&lower_path);
 386
 387 out:
 388         return err;
 389 }
 390
 391 struct sdcardfs_mount_private {
 392         struct vfsmount *mnt;
 393         const char *dev_name;
 394         void *raw_data;
 395 };
 396
 397 static int __sdcardfs_fill_super(
 398         struct super_block *sb,
 399         void *_priv, int silent)
 400 {
 401         struct sdcardfs_mount_private *priv = _priv;
 402
 403         return sdcardfs_read_super(priv->mnt,
 404                 sb, priv->dev_name, priv->raw_data, silent);
 405 }
 406
 407 static struct dentry *sdcardfs_mount(struct vfsmount *mnt,
 408                 struct file_system_type *fs_type, int flags,
 409                             const char *dev_name, void *raw_data)
 410 {
 411         struct sdcardfs_mount_private priv = {
 412                 .mnt = mnt,
 413                 .dev_name = dev_name,
 414                 .raw_data = raw_data
 415         };
 416
 417         return mount_nodev(fs_type, flags,
 418                 &priv, __sdcardfs_fill_super);
 419 }
 420
 421 static struct dentry *sdcardfs_mount_wrn(struct file_system_type *fs_type,
 422                     int flags, const char *dev_name, void *raw_data)
 423 {
 424         WARN(1, "sdcardfs does not support mount. Use mount2.\n");
 425         return ERR_PTR(-EINVAL);
 426 }
 427
 428 void *sdcardfs_alloc_mnt_data(void)
 429 {
 430         return kmalloc(sizeof(struct sdcardfs_vfsmount_options), GFP_KERNEL);
 431 }
 432
 433 void sdcardfs_kill_sb(struct super_block *sb)
 434 {
 435         struct sdcardfs_sb_info *sbi;
 436
 437         if (sb->s_magic == SDCARDFS_SUPER_MAGIC && sb->s_fs_info) {
 438                 sbi = SDCARDFS_SB(sb);
 439                 mutex_lock(&sdcardfs_super_list_lock);
 440                 list_del(&sbi->list);
 441                 mutex_unlock(&sdcardfs_super_list_lock);
 442         }
 443         kill_anon_super(sb);
 444 }
 445
 446 static struct file_system_type sdcardfs_fs_type = {
 447         .owner          = THIS_MODULE,
 448         .name           = SDCARDFS_NAME,
 449         .mount          = sdcardfs_mount_wrn,
 450         .mount2         = sdcardfs_mount,
 451         .alloc_mnt_data = sdcardfs_alloc_mnt_data,
 452         .kill_sb        = sdcardfs_kill_sb,
 453         .fs_flags       = 0,
 454 };
 455 MODULE_ALIAS_FS(SDCARDFS_NAME);
 456
 457 static int __init init_sdcardfs_fs(void)
 458 {
 459         int err;
 460
 461         pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
 462
 463         err = sdcardfs_init_inode_cache();
 464         if (err)
 465                 goto out;
 466         err = sdcardfs_init_dentry_cache();
 467         if (err)
 468                 goto out;
 469         err = packagelist_init();
 470         if (err)
 471                 goto out;
 472         err = register_filesystem(&sdcardfs_fs_type);
 473 out:
 474         if (err) {
 475                 sdcardfs_destroy_inode_cache();
 476                 sdcardfs_destroy_dentry_cache();
 477                 packagelist_exit();
 478         }
 479         return err;
 480 }
 481
 482 static void __exit exit_sdcardfs_fs(void)
 483 {
 484         sdcardfs_destroy_inode_cache();
 485         sdcardfs_destroy_dentry_cache();
 486         packagelist_exit();
 487         unregister_filesystem(&sdcardfs_fs_type);
 488         pr_info("Completed sdcardfs module unload\n");
 489 }
 490
 491 /* Original wrapfs authors */
 492 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University (http://www.fsl.cs.sunysb.edu/)");
 493
 494 /* Original sdcardfs authors */
 495 MODULE_AUTHOR("Woojoong Lee, Daeho Jeong, Kitae Lee, Yeongjin Gil System Memory Lab., Samsung Electronics");
 496
 497 /* Current maintainer */
 498 MODULE_AUTHOR("Daniel Rosenberg, Google");
 499 MODULE_DESCRIPTION("Sdcardfs " SDCARDFS_VERSION);
 500 MODULE_LICENSE("GPL");
 501
 502 module_init(init_sdcardfs_fs);
 503 module_exit(exit_sdcardfs_fs);