// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2017 Red Hat, Inc.
*/
#include <linux/cred.h>
#include <linux/file.h>
#include <linux/mount.h>
#include <linux/xattr.h>
#include <linux/uio.h>
#include <linux/uaccess.h>
#include <linux/splice.h>
#include <linux/security.h>
#include <linux/mm.h>
#include <linux/fs.h>
#include "overlayfs.h"
struct ovl_aio_req {
struct kiocb iocb;
struct kiocb *orig_iocb;
struct fd fd;
};
static struct kmem_cache *ovl_aio_request_cachep;
static char ovl_whatisit(struct inode *inode, struct inode *realinode)
{
if (realinode != ovl_inode_upper(inode))
return 'l';
if (ovl_has_upperdata(inode))
return 'u';
else
return 'm';
}
/* No atime modificaton nor notify on underlying */
#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
static struct file *ovl_open_realfile(const struct file *file,
struct inode *realinode)
{
struct inode *inode = file_inode(file);
struct file *realfile;
const struct cred *old_cred;
int flags = file->f_flags | OVL_OPEN_FLAGS;
int acc_mode = ACC_MODE(flags);
int err;
if (flags & O_APPEND)
acc_mode |= MAY_APPEND;
old_cred = ovl_override_creds(inode->i_sb);
err = inode_permission(realinode, MAY_OPEN | acc_mode);
if (err) {
realfile = ERR_PTR(err);
} else if (!inode_owner_or_capable(realinode)) {
realfile = ERR_PTR(-EPERM);
} else {
realfile = open_with_fake_path(&file->f_path, flags, realinode,
current_cred());
}
revert_creds(old_cred);
pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
file, file, ovl_whatisit(inode, realinode), file->f_flags,
realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
return realfile;
}
#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
static int ovl_change_flags(struct file *file, unsigned int flags)
{
struct inode *inode = file_inode(file);
int err;
flags |= OVL_OPEN_FLAGS;
/* If some flag changed that cannot be changed then something's amiss */
if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
return -EIO;
flags &= OVL_SETFL_MASK;
if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
return -EPERM;
if (flags & O_DIRECT) {
if (!file->f_mapping->a_ops ||
!file->f_mapping->a_ops->direct_IO)
return -EINVAL;
}
if (file->f_op->check_flags) {
err = file->f_op->check_flags(flags);
if (err)
return err;
}
spin_lock(&file->f_lock);
file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
spin_unlock(&file->f_lock);
return 0;
}
static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
bool allow_meta)
{
struct inode *inode = file_inode(file);
struct inode *realinode;
real->flags = 0;
real->file = file->private_data;
if (allow_meta)
realinode = ovl_inode_real(inode);
else
realinode = ovl_inode_realdata(inode);
/* Has it been copied up since we'd opened it? */
if (unlikely(file_inode(real->file) != realinode)) {
real->flags = FDPUT_FPUT;
real->file = ovl_open_realfile(file, realinode);
return PTR_ERR_OR_ZERO(real->file);
}
/* Did the flags change since open? */
if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
return ovl_change_flags(real->file, file->f_flags);
return 0;
}
static int ovl_real_fdget(const struct file *file, struct fd *real)
{
if (d_is_dir(file_dentry(file))) {
real->flags = 0;
real->file = ovl_dir_real_file(file, false);
return PTR_ERR_OR_ZERO(real->file);
}
return ovl_real_fdget_meta(file, real, false);
}
static int ovl_open(struct inode *inode, struct file *file)
{
struct file *realfile;
int err;
err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
if (err)
return err;
/* No longer need these flags, so don't pass them on to underlying fs */
file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
if (IS_ERR(realfile))
return PTR_ERR(realfile);
file->private_data = realfile;
return 0;
}
static int ovl_release(struct inode *inode, struct file *file)
{