ccs-patch/fs/syaoran_2.6.c

/*
 * fs/syaoran_2.6.c
 *
 * Implementation of the Tamper-Proof Device Filesystem.
 *
 * Portions Copyright (C) 2005-2008  NTT DATA CORPORATION
 *
 * Version: 1.6.6-pre   2008/12/01
 *
 * This file is applicable to 2.6.11 and later.
 * See README.ccs for ChangeLog.
 * This filesystem is developed using the ramfs implementation.
 *
 */
/*
 * Resizable simple ram filesystem for Linux.
 *
 * Copyright (C) 2000 Linus Torvalds.
 *               2000 Transmeta Corp.
 *
 * Usage limits added by David Gibson, Linuxcare Australia.
 * This file is released under the GPL.
 */

/*
 * NOTE! This filesystem is probably most useful
 * not as a real filesystem, but as an example of
 * how virtual filesystems can be written.
 *
 * It doesn't get much simpler than this. Consider
 * that this file implements the full semantics of
 * a POSIX-compliant read-write filesystem.
 *
 * Note in particular how the filesystem does not
 * need to implement any data structures of its own
 * to keep track of the virtual data: using the VFS
 * caches is sufficient.
 */

#include <linux/module.h>
#include <linux/fs.h>
#include <linux/pagemap.h>
#include <linux/highmem.h>
#include <linux/init.h>
#include <linux/string.h>
#include <linux/smp_lock.h>
#include <linux/backing-dev.h>

#include <asm/uaccess.h>

#include <linux/namei.h>
#include <linux/version.h>
#include <linux/sched.h>
#include <linux/mm.h>

static struct super_operations syaoran_ops;
static struct address_space_operations syaoran_aops;
static struct inode_operations syaoran_file_inode_operations;
static struct inode_operations syaoran_dir_inode_operations;
static struct inode_operations syaoran_symlink_inode_operations;
static struct file_operations syaoran_file_operations;

static struct backing_dev_info syaoran_backing_dev_info = {
        .ra_pages      = 0,    /* No readahead */
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 12)
        .memory_backed = 1,    /* Does not contribute to dirty memory */
#else
        .capabilities  = BDI_CAP_NO_ACCT_DIRTY | BDI_CAP_NO_WRITEBACK |
        BDI_CAP_MAP_DIRECT | BDI_CAP_MAP_COPY |
        BDI_CAP_READ_MAP | BDI_CAP_WRITE_MAP |
        BDI_CAP_EXEC_MAP,
#endif
};

#include <linux/syaoran.h>

static struct inode *syaoran_get_inode(struct super_block *sb, int mode,
                                       dev_t dev)
{
        struct inode *inode = new_inode(sb);

        if (inode) {
                inode->i_mode = mode;
                inode->i_uid = current->fsuid;
                inode->i_gid = current->fsgid;
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
#ifndef HAVE_NO_I_BLKSIZE_IN_INODE
                inode->i_blksize = PAGE_CACHE_SIZE;
#endif
#endif
                inode->i_blocks = 0;
                inode->i_mapping->a_ops = &syaoran_aops;
                inode->i_mapping->backing_dev_info = &syaoran_backing_dev_info;
                inode->i_ctime = CURRENT_TIME;
                inode->i_mtime = inode->i_ctime;
                inode->i_atime = inode->i_mtime;
                switch (mode & S_IFMT) {
                default:
                        init_special_inode(inode, mode, dev);
                        if (S_ISBLK(mode))
                                inode->i_fop = &wrapped_def_blk_fops;
                        else if (S_ISCHR(mode))
                                inode->i_fop = &wrapped_def_chr_fops;
                        inode->i_op = &syaoran_file_inode_operations;
                        break;
                case S_IFREG:
                        inode->i_op = &syaoran_file_inode_operations;
                        inode->i_fop = &syaoran_file_operations;
                        break;
                case S_IFDIR:
                        inode->i_op = &syaoran_dir_inode_operations;
                        inode->i_fop = &simple_dir_operations;
                        /*
                         * directory inodes start off with i_nlink == 2
                         * (for "." entry)
                         */
                        inode->i_nlink++;
                        break;
                case S_IFLNK:
                        inode->i_op = &syaoran_symlink_inode_operations;
                        break;
                }
        }
        return inode;
}

/*
 * File creation. Allocate an inode, and we're done..
 */
/* SMP-safe */
static int syaoran_mknod(struct inode *dir, struct dentry *dentry, int mode,
                         dev_t dev)
{
        struct inode *inode;
        int error = -ENOSPC;
        if (syaoran_may_create_node(dentry, mode, dev) < 0)
                return -EPERM;
        inode = syaoran_get_inode(dir->i_sb, mode, dev);
        if (inode) {
                if (dir->i_mode & S_ISGID) {
                        inode->i_gid = dir->i_gid;
                        if (S_ISDIR(mode))
                                inode->i_mode |= S_ISGID;
                }
                d_instantiate(dentry, inode);
                dget(dentry); /* Extra count - pin the dentry in core */
                error = 0;
        }
        return error;
}

static int syaoran_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
        int retval = syaoran_mknod(dir, dentry, mode | S_IFDIR, 0);
        if (!retval)
                dir->i_nlink++;
        return retval;
}

static int syaoran_create(struct inode *dir, struct dentry *dentry, int mode,
                          struct nameidata *nd)
{
        return syaoran_mknod(dir, dentry, mode | S_IFREG, 0);
}

static int syaoran_symlink(struct inode *dir, struct dentry *dentry,
                           const char *symname)
{
        struct inode *inode;
        int error = -ENOSPC;
        if (syaoran_may_create_node(dentry, S_IFLNK, 0) < 0)
                return -EPERM;
        inode = syaoran_get_inode(dir->i_sb, S_IFLNK|S_IRWXUGO, 0);
        if (inode) {
                int l = strlen(symname)+1;
                error = page_symlink(inode, symname, l);
                if (!error) {
                        if (dir->i_mode & S_ISGID)
                                inode->i_gid = dir->i_gid;
                        d_instantiate(dentry, inode);
                        dget(dentry);
                } else
                        iput(inode);
        }
        return error;
}

static int syaoran_link(struct dentry *old_dentry, struct inode *dir,
                        struct dentry *dentry)
{
        struct inode *inode = old_dentry->d_inode;
        if (!inode || syaoran_may_create_node(dentry, inode->i_mode,
                                              inode->i_rdev) < 0)
                return -EPERM;
        return simple_link(old_dentry, dir, dentry);
}

static int syaoran_unlink(struct inode *dir, struct dentry *dentry)
{
        if (syaoran_may_modify_node(dentry, MAY_DELETE) < 0)
                return -EPERM;
        return simple_unlink(dir, dentry);
}

static int syaoran_rename(struct inode *old_dir, struct dentry *old_dentry,
                          struct inode *new_dir, struct dentry *new_dentry)
{
        struct inode *inode = old_dentry->d_inode;
        if (!inode || syaoran_may_modify_node(old_dentry, MAY_DELETE) < 0 ||
            syaoran_may_create_node(new_dentry, inode->i_mode,
                                    inode->i_rdev) < 0)
                return -EPERM;
        return simple_rename(old_dir, old_dentry, new_dir, new_dentry);
}

static int syaoran_rmdir(struct inode *dir, struct dentry *dentry)
{
        if (syaoran_may_modify_node(dentry, MAY_DELETE) < 0)
                return -EPERM;
        return simple_rmdir(dir, dentry);
}

static int syaoran_setattr(struct dentry *dentry, struct iattr *attr)
{
        struct inode *inode = dentry->d_inode;
        int error = inode_change_ok(inode, attr);
        if (!error) {
                unsigned int ia_valid = attr->ia_valid;
                unsigned int flags = 0;
                if (ia_valid & (ATTR_UID | ATTR_GID))
                        flags |= MAY_CHOWN;
                if (ia_valid & ATTR_MODE)
                        flags |= MAY_CHMOD;
                if (syaoran_may_modify_node(dentry, flags) < 0)
                        return -EPERM;
                if (!error)
                        error = inode_setattr(inode, attr);
        }
        return error;
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 24)
static struct address_space_operations syaoran_aops = {
        .readpage       = simple_readpage,
        .prepare_write  = simple_prepare_write,
        .commit_write   = simple_commit_write
};
#else
static int syaoran_set_page_dirty_no_writeback(struct page *page)
{
        if (!PageDirty(page))
                SetPageDirty(page);
        return 0;
}
static struct address_space_operations syaoran_aops = {
        .readpage       = simple_readpage,
        .write_begin    = simple_write_begin,
        .write_end      = simple_write_end,
        .set_page_dirty = syaoran_set_page_dirty_no_writeback,
};
#endif

static struct file_operations syaoran_file_operations = {
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 19)
        .read        = generic_file_read,
        .write       = generic_file_write,
#else
        .aio_read    = generic_file_aio_read,
        .read        = do_sync_read,
        .aio_write   = generic_file_aio_write,
        .write       = do_sync_write,
#endif
        .mmap        = generic_file_mmap,
        .fsync       = simple_sync_file,
#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 23)
        .sendfile    = generic_file_sendfile,
#else
        .splice_read = generic_file_splice_read,
#endif
        .llseek      = generic_file_llseek,
};

static struct inode_operations syaoran_file_inode_operations = {
        .getattr    = simple_getattr,
        .setattr    = syaoran_setattr,
};

static struct inode_operations syaoran_dir_inode_operations = {
        .create     = syaoran_create,
        .lookup     = simple_lookup,
        .link       = syaoran_link,
        .unlink     = syaoran_unlink,
        .symlink    = syaoran_symlink,
        .mkdir      = syaoran_mkdir,
        .rmdir      = syaoran_rmdir,
        .mknod      = syaoran_mknod,
        .rename     = syaoran_rename,
        .setattr    = syaoran_setattr,
};

static struct inode_operations syaoran_symlink_inode_operations = {
        .readlink       = generic_readlink,
        .follow_link    = page_follow_link_light,
        .put_link       = page_put_link,
        .setattr        = syaoran_setattr,
};

static struct super_operations syaoran_ops = {
        .statfs     = simple_statfs,
        .drop_inode = generic_delete_inode,
        .put_super  = syaoran_put_super,
};

static int syaoran_fill_super(struct super_block *sb, void *data, int silent)
{
        struct inode *inode;
        struct dentry *root;

        sb->s_maxbytes = MAX_LFS_FILESIZE;
        sb->s_blocksize = PAGE_CACHE_SIZE;
        sb->s_blocksize_bits = PAGE_CACHE_SHIFT;
        sb->s_magic = SYAORAN_MAGIC;
        sb->s_op = &syaoran_ops;
#if LINUX_VERSION_CODE >= KERNEL_VERSION(2, 6, 9)
        sb->s_time_gran = 1;
#endif
        {
                int error = syaoran_initialize(sb, data);
                if (error < 0)
                        return error;
        }
        inode = syaoran_get_inode(sb, S_IFDIR | 0755, 0);
        if (!inode)
                return -ENOMEM;

        root = d_alloc_root(inode);
        if (!root) {
                iput(inode);
                return -ENOMEM;
        }
        sb->s_root = root;
        syaoran_make_initial_nodes(sb);
        return 0;
}

#if LINUX_VERSION_CODE < KERNEL_VERSION(2, 6, 18)
static struct super_block *syaoran_get_sb(struct file_system_type *fs_type,
                                          int flags, const char *dev_name,
                                          void *data)
{
        return get_sb_nodev(fs_type, flags, data, syaoran_fill_super);
}
#else
static int syaoran_get_sb(struct file_system_type *fs_type,
                          int flags, const char *dev_name, void *data,
                          struct vfsmount *mnt)
{
        return get_sb_nodev(fs_type, flags, data, syaoran_fill_super, mnt);
}
#endif

static struct file_system_type syaoran_fs_type = {
        .owner      = THIS_MODULE,
        .name       = "syaoran",
        .get_sb     = syaoran_get_sb,
        .kill_sb    = kill_litter_super,
};

static int __init init_syaoran_fs(void)
{
        return register_filesystem(&syaoran_fs_type);
}

static void __exit exit_syaoran_fs(void)
{
        unregister_filesystem(&syaoran_fs_type);
}

module_init(init_syaoran_fs);
module_exit(exit_syaoran_fs);

MODULE_LICENSE("GPL");