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