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_lower_fs, "lower_fs=%s"},
  45         {Opt_mask, "mask=%u"},
  46         {Opt_userid, "userid=%d"},
  47         {Opt_multiuser, "multiuser"},
  48         {Opt_reserved_mb, "reserved_mb=%u"},
  49         {Opt_err, NULL}
  50 };
  51
  52 static int parse_options(struct super_block *sb, char *options, int silent,
  53                                 int *debug, struct sdcardfs_mount_options *opts)
  54 {
  55         char *p;
  56         substring_t args[MAX_OPT_ARGS];
  57         int option;
  58         char *string_option;
  59
  60         /* by default, we use AID_MEDIA_RW as uid, gid */
  61         opts->fs_low_uid = AID_MEDIA_RW;
  62         opts->fs_low_gid = AID_MEDIA_RW;
  63         opts->mask = 0;
  64         opts->multiuser = false;
  65         opts->fs_user_id = 0;
  66         opts->gid = 0;
  67         /* by default, we use LOWER_FS_EXT4 as lower fs type */
  68         opts->lower_fs = LOWER_FS_EXT4;
  69         /* by default, 0MB is reserved */
  70         opts->reserved_mb = 0;
  71
  72         *debug = 0;
  73
  74         if (!options)
  75                 return 0;
  76
  77         while ((p = strsep(&options, ",")) != NULL) {
  78                 int token;
  79                 if (!*p)
  80                         continue;
  81
  82                 token = match_token(p, sdcardfs_tokens, args);
  83
  84                 switch (token) {
  85                 case Opt_debug:
  86                         *debug = 1;
  87                         break;
  88                 case Opt_fsuid:
  89                         if (match_int(&args[0], &option))
  90                                 return 0;
  91                         opts->fs_low_uid = option;
  92                         break;
  93                 case Opt_fsgid:
  94                         if (match_int(&args[0], &option))
  95                                 return 0;
  96                         opts->fs_low_gid = option;
  97                         break;
  98                 case Opt_gid:
  99                         if (match_int(&args[0], &option))
 100                                 return 0;
 101                         opts->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                         break;
 113                 case Opt_multiuser:
 114                         opts->multiuser = true;
 115                         break;
 116                 case Opt_lower_fs:
 117                         string_option = match_strdup(&args[0]);
 118                         if (!strcmp("ext4", string_option)) {
 119                                 opts->lower_fs = LOWER_FS_EXT4;
 120                         } else if (!strcmp("fat", string_option)) {
 121                                 opts->lower_fs = LOWER_FS_FAT;
 122                         } else {
 123                                 kfree(string_option);
 124                                 goto invalid_option;
 125                         }
 126                         kfree(string_option);
 127                         break;
 128                 case Opt_reserved_mb:
 129                         if (match_int(&args[0], &option))
 130                                 return 0;
 131                         opts->reserved_mb = option;
 132                         break;
 133                 /* unknown option */
 134                 default:
 135 invalid_option:
 136                         if (!silent) {
 137                                 printk( KERN_ERR "Unrecognized mount option \"%s\" "
 138                                                 "or missing value", p);
 139                         }
 140                         return -EINVAL;
 141                 }
 142         }
 143
 144         if (*debug) {
 145                 printk( KERN_INFO "sdcardfs : options - debug:%d\n", *debug);
 146                 printk( KERN_INFO "sdcardfs : options - uid:%d\n",
 147                                                         opts->fs_low_uid);
 148                 printk( KERN_INFO "sdcardfs : options - gid:%d\n",
 149                                                         opts->fs_low_gid);
 150         }
 151
 152         return 0;
 153 }
 154
 155 #if 0
 156 /*
 157  * our custom d_alloc_root work-alike
 158  *
 159  * we can't use d_alloc_root if we want to use our own interpose function
 160  * unchanged, so we simply call our own "fake" d_alloc_root
 161  */
 162 static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
 163 {
 164         struct dentry *ret = NULL;
 165
 166         if (sb) {
 167                 static const struct qstr name = {
 168                         .name = "/",
 169                         .len = 1
 170                 };
 171
 172                 ret = d_alloc(NULL, &name);
 173                 if (ret) {
 174                         d_set_d_op(ret, &sdcardfs_ci_dops);
 175                         ret->d_sb = sb;
 176                         ret->d_parent = ret;
 177                 }
 178         }
 179         return ret;
 180 }
 181 #endif
 182
 183 DEFINE_MUTEX(sdcardfs_super_list_lock);
 184 LIST_HEAD(sdcardfs_super_list);
 185 EXPORT_SYMBOL_GPL(sdcardfs_super_list_lock);
 186 EXPORT_SYMBOL_GPL(sdcardfs_super_list);
 187
 188 /*
 189  * There is no need to lock the sdcardfs_super_info's rwsem as there is no
 190  * way anyone can have a reference to the superblock at this point in time.
 191  */
 192 static int sdcardfs_read_super(struct super_block *sb, const char *dev_name,
 193                                                 void *raw_data, int silent)
 194 {
 195         int err = 0;
 196         int debug;
 197         struct super_block *lower_sb;
 198         struct path lower_path;
 199         struct sdcardfs_sb_info *sb_info;
 200         struct inode *inode;
 201
 202         printk(KERN_INFO "sdcardfs version 2.0\n");
 203
 204         if (!dev_name) {
 205                 printk(KERN_ERR
 206                        "sdcardfs: read_super: missing dev_name argument\n");
 207                 err = -EINVAL;
 208                 goto out;
 209         }
 210
 211         printk(KERN_INFO "sdcardfs: dev_name -> %s\n", dev_name);
 212         printk(KERN_INFO "sdcardfs: options -> %s\n", (char *)raw_data);
 213
 214         /* parse lower path */
 215         err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
 216                         &lower_path);
 217         if (err) {
 218                 printk(KERN_ERR "sdcardfs: error accessing lower directory '%s'\n", dev_name);
 219                 goto out;
 220         }
 221
 222         /* allocate superblock private data */
 223         sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
 224         if (!SDCARDFS_SB(sb)) {
 225                 printk(KERN_CRIT "sdcardfs: read_super: out of memory\n");
 226                 err = -ENOMEM;
 227                 goto out_free;
 228         }
 229
 230         sb_info = sb->s_fs_info;
 231         /* parse options */
 232         err = parse_options(sb, raw_data, silent, &debug, &sb_info->options);
 233         if (err) {
 234                 printk(KERN_ERR "sdcardfs: invalid options\n");
 235                 goto out_freesbi;
 236         }
 237
 238         /* set the lower superblock field of upper superblock */
 239         lower_sb = lower_path.dentry->d_sb;
 240         atomic_inc(&lower_sb->s_active);
 241         sdcardfs_set_lower_super(sb, lower_sb);
 242
 243         /* inherit maxbytes from lower file system */
 244         sb->s_maxbytes = lower_sb->s_maxbytes;
 245
 246         /*
 247          * Our c/m/atime granularity is 1 ns because we may stack on file
 248          * systems whose granularity is as good.
 249          */
 250         sb->s_time_gran = 1;
 251
 252         sb->s_magic = SDCARDFS_SUPER_MAGIC;
 253         sb->s_op = &sdcardfs_sops;
 254
 255         /* get a new inode and allocate our root dentry */
 256         inode = sdcardfs_iget(sb, lower_path.dentry->d_inode, 0);
 257         if (IS_ERR(inode)) {
 258                 err = PTR_ERR(inode);
 259                 goto out_sput;
 260         }
 261         sb->s_root = d_make_root(inode);
 262         if (!sb->s_root) {
 263                 err = -ENOMEM;
 264                 goto out_iput;
 265         }
 266         d_set_d_op(sb->s_root, &sdcardfs_ci_dops);
 267
 268         /* link the upper and lower dentries */
 269         sb->s_root->d_fsdata = NULL;
 270         err = new_dentry_private_data(sb->s_root);
 271         if (err)
 272                 goto out_freeroot;
 273
 274         /* set the lower dentries for s_root */
 275         sdcardfs_set_lower_path(sb->s_root, &lower_path);
 276
 277         /*
 278          * No need to call interpose because we already have a positive
 279          * dentry, which was instantiated by d_make_root.  Just need to
 280          * d_rehash it.
 281          */
 282         d_rehash(sb->s_root);
 283
 284         /* setup permission policy */
 285         sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
 286         mutex_lock(&sdcardfs_super_list_lock);
 287         if(sb_info->options.multiuser) {
 288                 setup_derived_state(sb->s_root->d_inode, PERM_PRE_ROOT, sb_info->options.fs_user_id, AID_ROOT, false);
 289                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
 290                 /*err =  prepare_dir(sb_info->obbpath_s,
 291                                         sb_info->options.fs_low_uid,
 292                                         sb_info->options.fs_low_gid, 00755);*/
 293         } else {
 294                 setup_derived_state(sb->s_root->d_inode, PERM_ROOT, sb_info->options.fs_low_uid, AID_ROOT, false);
 295                 snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
 296         }
 297         fix_derived_permission(sb->s_root->d_inode);
 298         sb_info->sb = sb;
 299         list_add(&sb_info->list, &sdcardfs_super_list);
 300         mutex_unlock(&sdcardfs_super_list_lock);
 301
 302         if (!silent)
 303                 printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
 304                                 dev_name, lower_sb->s_type->name);
 305         goto out; /* all is well */
 306
 307         /* no longer needed: free_dentry_private_data(sb->s_root); */
 308 out_freeroot:
 309         dput(sb->s_root);
 310 out_iput:
 311         iput(inode);
 312 out_sput:
 313         /* drop refs we took earlier */
 314         atomic_dec(&lower_sb->s_active);
 315 out_freesbi:
 316         kfree(SDCARDFS_SB(sb));
 317         sb->s_fs_info = NULL;
 318 out_free:
 319         path_put(&lower_path);
 320
 321 out:
 322         return err;
 323 }
 324
 325 /* A feature which supports mount_nodev() with options */
 326 static struct dentry *mount_nodev_with_options(struct file_system_type *fs_type,
 327         int flags, const char *dev_name, void *data,
 328         int (*fill_super)(struct super_block *, const char *, void *, int))
 329
 330 {
 331         int error;
 332         struct super_block *s = sget(fs_type, NULL, set_anon_super, flags, NULL);
 333
 334         if (IS_ERR(s))
 335                 return ERR_CAST(s);
 336
 337         s->s_flags = flags;
 338
 339         error = fill_super(s, dev_name, data, flags & MS_SILENT ? 1 : 0);
 340         if (error) {
 341                 deactivate_locked_super(s);
 342                 return ERR_PTR(error);
 343         }
 344         s->s_flags |= MS_ACTIVE;
 345         return dget(s->s_root);
 346 }
 347
 348 struct dentry *sdcardfs_mount(struct file_system_type *fs_type, int flags,
 349                             const char *dev_name, void *raw_data)
 350 {
 351         /*
 352          * dev_name is a lower_path_name,
 353          * raw_data is a option string.
 354          */
 355         return mount_nodev_with_options(fs_type, flags, dev_name,
 356                                         raw_data, sdcardfs_read_super);
 357 }
 358
 359 void sdcardfs_kill_sb(struct super_block *sb) {
 360         struct sdcardfs_sb_info *sbi;
 361         if (sb->s_magic == SDCARDFS_SUPER_MAGIC) {
 362                 sbi = SDCARDFS_SB(sb);
 363                 mutex_lock(&sdcardfs_super_list_lock);
 364                 list_del(&sbi->list);
 365                 mutex_unlock(&sdcardfs_super_list_lock);
 366         }
 367         generic_shutdown_super(sb);
 368 }
 369
 370 static struct file_system_type sdcardfs_fs_type = {
 371         .owner          = THIS_MODULE,
 372         .name           = SDCARDFS_NAME,
 373         .mount          = sdcardfs_mount,
 374         .kill_sb        = sdcardfs_kill_sb,
 375         .fs_flags       = 0,
 376 };
 377
 378 static int __init init_sdcardfs_fs(void)
 379 {
 380         int err;
 381
 382         pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
 383
 384         err = sdcardfs_init_inode_cache();
 385         if (err)
 386                 goto out;
 387         err = sdcardfs_init_dentry_cache();
 388         if (err)
 389                 goto out;
 390         err = packagelist_init();
 391         if (err)
 392                 goto out;
 393         err = register_filesystem(&sdcardfs_fs_type);
 394 out:
 395         if (err) {
 396                 sdcardfs_destroy_inode_cache();
 397                 sdcardfs_destroy_dentry_cache();
 398                 packagelist_exit();
 399         }
 400         return err;
 401 }
 402
 403 static void __exit exit_sdcardfs_fs(void)
 404 {
 405         sdcardfs_destroy_inode_cache();
 406         sdcardfs_destroy_dentry_cache();
 407         packagelist_exit();
 408         unregister_filesystem(&sdcardfs_fs_type);
 409         pr_info("Completed sdcardfs module unload\n");
 410 }
 411
 412 MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
 413               " (http://www.fsl.cs.sunysb.edu/)");
 414 MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
 415                    " (http://wrapfs.filesystems.org/)");
 416 MODULE_LICENSE("GPL");
 417
 418 module_init(init_sdcardfs_fs);
 419 module_exit(exit_sdcardfs_fs);