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main.c
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main.c
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/*
* fs/sdcardfs/main.c
*
* Copyright (c) 2013 Samsung Electronics Co. Ltd
* Authors: Daeho Jeong, Woojoong Lee, Seunghwan Hyun,
* Sunghwan Yun, Sungjong Seo
*
* This program has been developed as a stackable file system based on
* the WrapFS which written by
*
* Copyright (c) 1998-2011 Erez Zadok
* Copyright (c) 2009 Shrikar Archak
* Copyright (c) 2003-2011 Stony Brook University
* Copyright (c) 2003-2011 The Research Foundation of SUNY
*
* This file is dual licensed. It may be redistributed and/or modified
* under the terms of the Apache 2.0 License OR version 2 of the GNU
* General Public License.
*/
#include "sdcardfs.h"
#include <linux/module.h>
#include <linux/types.h>
#include <linux/parser.h>
#include <linux/syscalls.h>
#include "../internal.h"
enum {
Opt_uid,
Opt_gid,
Opt_wgid,
Opt_debug,
Opt_split,
Opt_derive,
Opt_lower_fs,
Opt_reserved_mb,
Opt_err,
};
static const match_table_t sdcardfs_tokens = {
{Opt_uid, "uid=%u"},
{Opt_gid, "gid=%u"},
{Opt_wgid, "wgid=%u"},
{Opt_debug, "debug"},
{Opt_split, "split"},
{Opt_derive, "derive=%s"},
{Opt_lower_fs, "lower_fs=%s"},
{Opt_reserved_mb, "reserved_mb=%u"},
{Opt_err, NULL}
};
static int parse_options(struct super_block *sb, char *options, int silent,
int *debug, struct sdcardfs_mount_options *opts)
{
char *p;
substring_t args[MAX_OPT_ARGS];
int option;
char *string_option;
/* by default, we use AID_MEDIA_RW as uid, gid */
opts->fs_low_uid = AID_MEDIA_RW;
opts->fs_low_gid = AID_MEDIA_RW;
/* by default, we use AID_SDCARD_RW as write_gid */
opts->write_gid = AID_SDCARD_RW;
/* default permission policy
* (DERIVE_NONE | DERIVE_LEGACY | DERIVE_UNIFIED) */
opts->derive = DERIVE_NONE;
opts->split_perms = 0;
/* by default, we use LOWER_FS_EXT4 as lower fs type */
opts->lower_fs = LOWER_FS_EXT4;
/* by default, 0MB is reserved */
opts->reserved_mb = 0;
*debug = 0;
if (!options)
return 0;
while ((p = strsep(&options, ",")) != NULL) {
int token;
if (!*p)
continue;
token = match_token(p, sdcardfs_tokens, args);
switch (token) {
case Opt_debug:
*debug = 1;
break;
case Opt_uid:
if (match_int(&args[0], &option))
return 0;
opts->fs_low_uid = option;
break;
case Opt_gid:
if (match_int(&args[0], &option))
return 0;
opts->fs_low_gid = option;
break;
case Opt_wgid:
if (match_int(&args[0], &option))
return 0;
opts->write_gid = option;
break;
case Opt_split:
opts->split_perms=1;
break;
case Opt_derive:
string_option = match_strdup(&args[0]);
if (!strcmp("none", string_option)) {
opts->derive = DERIVE_NONE;
} else if (!strcmp("legacy", string_option)) {
opts->derive = DERIVE_LEGACY;
} else if (!strcmp("unified", string_option)) {
opts->derive = DERIVE_UNIFIED;
} else {
kfree(string_option);
goto invalid_option;
}
kfree(string_option);
break;
case Opt_lower_fs:
string_option = match_strdup(&args[0]);
if (!strcmp("ext4", string_option)) {
opts->lower_fs = LOWER_FS_EXT4;
} else if (!strcmp("fat", string_option)) {
opts->lower_fs = LOWER_FS_FAT;
} else {
kfree(string_option);
goto invalid_option;
}
kfree(string_option);
break;
case Opt_reserved_mb:
if (match_int(&args[0], &option))
return 0;
opts->reserved_mb = option;
break;
/* unknown option */
default:
invalid_option:
if (!silent) {
printk( KERN_ERR "Unrecognized mount option \"%s\" "
"or missing value", p);
}
return -EINVAL;
}
}
if (*debug) {
printk( KERN_INFO "sdcardfs : options - debug:%d\n", *debug);
printk( KERN_INFO "sdcardfs : options - uid:%d\n",
opts->fs_low_uid);
printk( KERN_INFO "sdcardfs : options - gid:%d\n",
opts->fs_low_gid);
}
return 0;
}
/*
* our custom d_alloc_root work-alike
*
* we can't use d_alloc_root if we want to use our own interpose function
* unchanged, so we simply call our own "fake" d_alloc_root
*/
static struct dentry *sdcardfs_d_alloc_root(struct super_block *sb)
{
struct dentry *ret = NULL;
//struct sdcardfs_sb_info *sbi = SDCARDFS_SB(sb);
struct dentry *(*__d_alloc_new)(struct super_block *, const struct qstr *) = (void *)kallsyms_lookup_name("__d_alloc");
if (sb) {
static const struct qstr name = {
.name = "/",
.len = 1
};
ret = __d_alloc_new(sb, &name);
if (ret) {
d_set_d_op(ret, &sdcardfs_ci_dops);
ret->d_parent = ret;
}
}
return ret;
}
/*
* There is no need to lock the sdcardfs_super_info's rwsem as there is no
* way anyone can have a reference to the superblock at this point in time.
*/
static int sdcardfs_read_super(struct super_block *sb, const char *dev_name,
void *raw_data, int silent)
{
int err = 0;
int debug;
struct super_block *lower_sb;
struct path lower_path;
struct sdcardfs_sb_info *sb_info;
void *pkgl_id;
printk(KERN_INFO "sdcardfs version 2.0\n");
if (!dev_name) {
printk(KERN_ERR
"sdcardfs: read_super: missing dev_name argument\n");
err = -EINVAL;
goto out;
}
printk(KERN_INFO "sdcardfs: dev_name -> %s\n", dev_name);
printk(KERN_INFO "sdcardfs: options -> %s\n", (char *)raw_data);
/* parse lower path */
err = kern_path(dev_name, LOOKUP_FOLLOW | LOOKUP_DIRECTORY,
&lower_path);
if (err) {
printk(KERN_ERR "sdcardfs: error accessing "
"lower directory '%s'\n", dev_name);
goto out;
}
/* allocate superblock private data */
sb->s_fs_info = kzalloc(sizeof(struct sdcardfs_sb_info), GFP_KERNEL);
if (!SDCARDFS_SB(sb)) {
printk(KERN_CRIT "sdcardfs: read_super: out of memory\n");
err = -ENOMEM;
goto out_free;
}
sb_info = sb->s_fs_info;
/* parse options */
err = parse_options(sb, raw_data, silent, &debug, &sb_info->options);
if (err) {
printk(KERN_ERR "sdcardfs: invalid options\n");
goto out_freesbi;
}
if (sb_info->options.derive != DERIVE_NONE) {
pkgl_id = packagelist_create(sb_info->options.write_gid);
if(IS_ERR(pkgl_id))
goto out_freesbi;
else
sb_info->pkgl_id = pkgl_id;
}
/* set the lower superblock field of upper superblock */
lower_sb = lower_path.dentry->d_sb;
atomic_inc(&lower_sb->s_active);
sdcardfs_set_lower_super(sb, lower_sb);
/* inherit maxbytes from lower file system */
sb->s_maxbytes = lower_sb->s_maxbytes;
/*
* Our c/m/atime granularity is 1 ns because we may stack on file
* systems whose granularity is as good.
*/
sb->s_time_gran = 1;
sb->s_magic = SDCARDFS_SUPER_MAGIC;
sb->s_op = &sdcardfs_sops;
/* see comment next to the definition of sdcardfs_d_alloc_root */
sb->s_root = sdcardfs_d_alloc_root(sb);
if (!sb->s_root) {
err = -ENOMEM;
goto out_sput;
}
/* link the upper and lower dentries */
sb->s_root->d_fsdata = NULL;
err = new_dentry_private_data(sb->s_root);
if (err)
goto out_freeroot;
/* set the lower dentries for s_root */
sdcardfs_set_lower_path(sb->s_root, &lower_path);
/* call interpose to create the upper level inode */
err = sdcardfs_interpose(sb->s_root, sb, &lower_path);
if (!err) {
/* setup permission policy */
switch(sb_info->options.derive) {
case DERIVE_NONE:
setup_derived_state(sb->s_root->d_inode,
PERM_ROOT, 0, AID_ROOT, AID_SDCARD_RW, 00775);
sb_info->obbpath_s = NULL;
break;
case DERIVE_LEGACY:
/* Legacy behavior used to support internal multiuser layout which
* places user_id at the top directory level, with the actual roots
* just below that. Shared OBB path is also at top level. */
setup_derived_state(sb->s_root->d_inode,
PERM_LEGACY_PRE_ROOT, 0, AID_ROOT, AID_SDCARD_R, 00771);
/* initialize the obbpath string and lookup the path
* sb_info->obb_path will be deactivated by path_put
* on sdcardfs_put_super */
sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
snprintf(sb_info->obbpath_s, PATH_MAX, "%s/obb", dev_name);
err = prepare_dir(sb_info->obbpath_s,
sb_info->options.fs_low_uid,
sb_info->options.fs_low_gid, 00755);
if(err)
printk(KERN_ERR "sdcardfs: %s: %d, error on creating %s\n",
__func__,__LINE__, sb_info->obbpath_s);
break;
case DERIVE_UNIFIED:
/* Unified multiuser layout which places secondary user_id under
* /Android/user and shared OBB path under /Android/obb. */
setup_derived_state(sb->s_root->d_inode,
PERM_ROOT, 0, AID_ROOT, AID_SDCARD_R, 00771);
sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
break;
}
fix_derived_permission(sb->s_root->d_inode);
if (!silent)
printk(KERN_INFO "sdcardfs: mounted on top of %s type %s\n",
dev_name, lower_sb->s_type->name);
goto out;
}
/* else error: fall through */
free_dentry_private_data(sb->s_root);
out_freeroot:
dput(sb->s_root);
out_sput:
/* drop refs we took earlier */
atomic_dec(&lower_sb->s_active);
packagelist_destroy(sb_info->pkgl_id);
out_freesbi:
kfree(SDCARDFS_SB(sb));
sb->s_fs_info = NULL;
out_free:
path_put(&lower_path);
out:
return err;
}
/* A feature which supports mount_nodev() with options */
static struct dentry *mount_nodev_with_options(struct file_system_type *fs_type,
int flags, const char *dev_name, void *data,
int (*fill_super)(struct super_block *, const char *, void *, int))
{
int error;
struct super_block *s = sget(fs_type, NULL, set_anon_super, NULL);
if (IS_ERR(s))
return ERR_CAST(s);
s->s_flags = flags;
error = fill_super(s, dev_name, data, flags & MS_SILENT ? 1 : 0);
if (error) {
deactivate_locked_super(s);
return ERR_PTR(error);
}
s->s_flags |= MS_ACTIVE;
return dget(s->s_root);
}
struct dentry *sdcardfs_mount(struct file_system_type *fs_type, int flags,
const char *dev_name, void *raw_data)
{
/*
* dev_name is a lower_path_name,
* raw_data is a option string.
*/
return mount_nodev_with_options(fs_type, flags, dev_name,
raw_data, sdcardfs_read_super);
}
static struct file_system_type sdcardfs_fs_type = {
.owner = THIS_MODULE,
.name = SDCARDFS_NAME,
.mount = sdcardfs_mount,
.kill_sb = generic_shutdown_super,
.fs_flags = FS_REVAL_DOT,
};
static int __init init_sdcardfs_fs(void)
{
int err;
pr_info("Registering sdcardfs " SDCARDFS_VERSION "\n");
err = sdcardfs_init_inode_cache();
if (err)
goto out;
err = sdcardfs_init_dentry_cache();
if (err)
goto out;
err = packagelist_init();
if (err)
goto out;
err = register_filesystem(&sdcardfs_fs_type);
out:
if (err) {
sdcardfs_destroy_inode_cache();
sdcardfs_destroy_dentry_cache();
packagelist_exit();
}
return err;
}
static void __exit exit_sdcardfs_fs(void)
{
sdcardfs_destroy_inode_cache();
sdcardfs_destroy_dentry_cache();
packagelist_exit();
unregister_filesystem(&sdcardfs_fs_type);
pr_info("Completed sdcardfs module unload\n");
}
MODULE_AUTHOR("Erez Zadok, Filesystems and Storage Lab, Stony Brook University"
" (http://www.fsl.cs.sunysb.edu/)");
MODULE_DESCRIPTION("Wrapfs " SDCARDFS_VERSION
" (http://wrapfs.filesystems.org/)");
MODULE_LICENSE("GPL");
module_init(init_sdcardfs_fs);
module_exit(exit_sdcardfs_fs);