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