Fixed MTP to work with TWRP

fs/sdcardfs/main.c

@@ -0,0 +1,440 @@
+/*
+ * 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 "version.h"
+#include <linux/module.h>
+#include <linux/types.h>
+#include <linux/parser.h>
+#include "../internal.h"
+
+enum {
+	Opt_low_uid,
+	Opt_low_gid,
+	Opt_gid,
+	Opt_userid,
+	Opt_debug,
+	Opt_lower_fs,
+	Opt_reserved_mb,
+	Opt_mask,
+	Opt_multi_user,
+	Opt_label,
+	Opt_type,
+	Opt_err,
+};
+
+static const match_table_t sdcardfs_tokens = {
+	{Opt_low_uid, "low_uid=%u"},
+	{Opt_low_gid, "low_gid=%u"},
+	{Opt_gid, "gid=%u"},
+	{Opt_userid, "userid=%u"},
+	{Opt_debug, "debug"},
+	{Opt_lower_fs, "lower_fs=%s"},
+	{Opt_reserved_mb, "reserved_mb=%u"},
+	{Opt_mask, "mask=%o"},
+	{Opt_multi_user, "multi_user"},
+	{Opt_label, "label=%s"},
+	{Opt_type, "type=%s"},
+	{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;
+	char *label;
+
+	/* by default, we use AID_MEDIA_RW as low_uid, low_gid */
+	opts->fs_low_uid = AID_MEDIA_RW;
+	opts->fs_low_gid = AID_MEDIA_RW;
+	/* by default, userid is 0, gid is AID_EVERYBODY */
+	opts->gid = AID_EVERYBODY;
+	opts->userid = 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;
+	/* by default, mask is 0 */
+	opts->mask = 0;
+	/* by default, multi_user is false */
+	opts->multi_user = false;
+	opts->label = NULL;
+	opts->type = TYPE_NONE;
+
+	*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_low_uid:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->fs_low_uid = option;
+			break;
+		case Opt_low_gid:
+			if (match_int(&args[0], &option))
+				return 0;
+			opts->fs_low_gid = option;
+			break;
+		case Opt_gid:
+			if (match_int(&args[0], &option))
+				goto invalid_option;
+			opts->gid = option;
+			break;
+		case Opt_userid:
+			if (match_int(&args[0], &option))
+				goto invalid_option;
+			opts->userid = option;
+			break;
+		case Opt_lower_fs:
+			string_option = match_strdup(&args[0]);
+			if (!string_option)
+				return -ENOMEM;
+			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;
+		case Opt_mask:
+			if (match_octal(&args[0], &option))
+				goto invalid_option;
+			opts->mask = option;
+			break;
+		case Opt_multi_user:
+			opts->multi_user = true;
+			break;
+		case Opt_label:
+			label = match_strdup(&args[0]);
+			if (!label)
+				return -ENOMEM;
+			opts->label = label;
+			break;
+		case Opt_type:
+			string_option = match_strdup(&args[0]);
+			if (!string_option)
+				return -ENOMEM;
+			if (!strcmp("default", string_option)) {
+				opts->type = TYPE_DEFAULT;
+			} else if (!strcmp("read", string_option)) {
+				opts->type = TYPE_READ;
+			} else if (!strcmp("write", string_option)) {
+				opts->type = TYPE_WRITE;
+			} else {
+				kfree(string_option);
+				goto invalid_option;
+			}
+			kfree(string_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;
+
+	if (sb) {
+		static const struct qstr name = {
+			.name = "/",
+			.len = 1
+		};
+
+		ret = __d_alloc(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 %s\n", SDCARDFS_VERSION);
+
+	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 or out of memory\n");
+		goto out_freesbi;
+	}
+
+	pkgl_id = packagelist_create();
+	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;
+	if (sb_info->options.type != TYPE_NONE)
+		sb->s_op = &sdcardfs_multimount_sops;
+	else
+		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 */
+		if(sb_info->options.multi_user){
+			setup_derived_state(sb->s_root->d_inode, 
+				PERM_PRE_ROOT, sb_info->options.userid, AID_ROOT, sb_info->options.gid, false);
+			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, 00775);
+		} else {
+			setup_derived_state(sb->s_root->d_inode,
+				PERM_ROOT, sb_info->options.userid, AID_ROOT, sb_info->options.gid, false);
+			sb_info->obbpath_s = kzalloc(PATH_MAX, GFP_KERNEL);
+			snprintf(sb_info->obbpath_s, PATH_MAX, "%s/Android/obb", dev_name);
+		}
+		fix_derived_permission(sb->s_root->d_inode);
+
+		sb_info->devpath = kzalloc(PATH_MAX, GFP_KERNEL);
+		if(sb_info->devpath && dev_name)
+			strncpy(sb_info->devpath, dev_name, strlen(dev_name));
+		
+		if (!silent && !err)
+			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, flags, 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	= 0,
+};
+
+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("Woojoong Lee, Daeho Jeong, Kitae Lee, Yeongjin Gil"
+        " System Memory Lab., Samsung Electronics");
+MODULE_DESCRIPTION("Sdcardfs " SDCARDFS_VERSION);
+MODULE_LICENSE("GPL");
+
+module_init(init_sdcardfs_fs);
+module_exit(exit_sdcardfs_fs);