654 lines
14 KiB
C
654 lines
14 KiB
C
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/*
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* Copyright (C) 2017 Red Hat, Inc.
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*
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* This program is free software; you can redistribute it and/or modify it
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* under the terms of the GNU General Public License version 2 as published by
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* the Free Software Foundation.
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*/
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#include <linux/cred.h>
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#include <linux/file.h>
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#include <linux/mount.h>
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#include <linux/xattr.h>
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#include <linux/uio.h>
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#include <linux/uaccess.h>
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#include "overlayfs.h"
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static char ovl_whatisit(struct inode *inode, struct inode *realinode)
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{
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if (realinode != ovl_inode_upper(inode))
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return 'l';
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if (ovl_has_upperdata(inode))
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return 'u';
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else
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return 'm';
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}
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/* No atime modificaton nor notify on underlying */
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#define OVL_OPEN_FLAGS (O_NOATIME | FMODE_NONOTIFY)
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static struct file *ovl_open_realfile(const struct file *file,
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struct inode *realinode)
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{
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struct inode *inode = file_inode(file);
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struct file *realfile;
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const struct cred *old_cred;
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int flags = file->f_flags | OVL_OPEN_FLAGS;
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old_cred = ovl_override_creds(inode->i_sb);
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realfile = open_with_fake_path(&file->f_path, flags, realinode,
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current_cred());
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ovl_revert_creds(old_cred);
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pr_debug("open(%p[%pD2/%c], 0%o) -> (%p, 0%o)\n",
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file, file, ovl_whatisit(inode, realinode), file->f_flags,
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realfile, IS_ERR(realfile) ? 0 : realfile->f_flags);
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return realfile;
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}
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#define OVL_SETFL_MASK (O_APPEND | O_NONBLOCK | O_NDELAY | O_DIRECT)
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static int ovl_change_flags(struct file *file, unsigned int flags)
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{
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struct inode *inode = file_inode(file);
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int err;
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flags |= OVL_OPEN_FLAGS;
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/* If some flag changed that cannot be changed then something's amiss */
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if (WARN_ON((file->f_flags ^ flags) & ~OVL_SETFL_MASK))
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return -EIO;
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flags &= OVL_SETFL_MASK;
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if (((flags ^ file->f_flags) & O_APPEND) && IS_APPEND(inode))
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return -EPERM;
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if (flags & O_DIRECT) {
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if (!file->f_mapping->a_ops ||
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!file->f_mapping->a_ops->direct_IO)
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return -EINVAL;
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}
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if (file->f_op->check_flags) {
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err = file->f_op->check_flags(flags);
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if (err)
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return err;
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}
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spin_lock(&file->f_lock);
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file->f_flags = (file->f_flags & ~OVL_SETFL_MASK) | flags;
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spin_unlock(&file->f_lock);
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return 0;
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}
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static int ovl_real_fdget_meta(const struct file *file, struct fd *real,
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bool allow_meta)
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{
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struct inode *inode = file_inode(file);
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struct inode *realinode;
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real->flags = 0;
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real->file = file->private_data;
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if (allow_meta)
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realinode = ovl_inode_real(inode);
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else
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realinode = ovl_inode_realdata(inode);
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/* Has it been copied up since we'd opened it? */
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if (unlikely(file_inode(real->file) != realinode)) {
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real->flags = FDPUT_FPUT;
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real->file = ovl_open_realfile(file, realinode);
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return PTR_ERR_OR_ZERO(real->file);
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}
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/* Did the flags change since open? */
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if (unlikely((file->f_flags ^ real->file->f_flags) & ~OVL_OPEN_FLAGS))
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return ovl_change_flags(real->file, file->f_flags);
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return 0;
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}
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static int ovl_real_fdget(const struct file *file, struct fd *real)
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{
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return ovl_real_fdget_meta(file, real, false);
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}
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static int ovl_open(struct inode *inode, struct file *file)
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{
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struct file *realfile;
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int err;
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err = ovl_maybe_copy_up(file_dentry(file), file->f_flags);
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if (err)
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return err;
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/* No longer need these flags, so don't pass them on to underlying fs */
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file->f_flags &= ~(O_CREAT | O_EXCL | O_NOCTTY | O_TRUNC);
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realfile = ovl_open_realfile(file, ovl_inode_realdata(inode));
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if (IS_ERR(realfile))
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return PTR_ERR(realfile);
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file->private_data = realfile;
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return 0;
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}
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static int ovl_release(struct inode *inode, struct file *file)
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{
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fput(file->private_data);
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return 0;
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}
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static loff_t ovl_llseek(struct file *file, loff_t offset, int whence)
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{
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struct inode *inode = file_inode(file);
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struct fd real;
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const struct cred *old_cred;
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loff_t ret;
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/*
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* The two special cases below do not need to involve real fs,
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* so we can optimizing concurrent callers.
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*/
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if (offset == 0) {
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if (whence == SEEK_CUR)
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return file->f_pos;
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if (whence == SEEK_SET)
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return vfs_setpos(file, 0, 0);
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}
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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/*
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* Overlay file f_pos is the master copy that is preserved
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* through copy up and modified on read/write, but only real
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* fs knows how to SEEK_HOLE/SEEK_DATA and real fs may impose
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* limitations that are more strict than ->s_maxbytes for specific
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* files, so we use the real file to perform seeks.
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*/
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inode_lock(inode);
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real.file->f_pos = file->f_pos;
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old_cred = ovl_override_creds(inode->i_sb);
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ret = vfs_llseek(real.file, offset, whence);
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ovl_revert_creds(old_cred);
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file->f_pos = real.file->f_pos;
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inode_unlock(inode);
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fdput(real);
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return ret;
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}
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static void ovl_file_accessed(struct file *file)
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{
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struct inode *inode, *upperinode;
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if (file->f_flags & O_NOATIME)
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return;
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inode = file_inode(file);
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upperinode = ovl_inode_upper(inode);
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if (!upperinode)
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return;
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if ((!timespec64_equal(&inode->i_mtime, &upperinode->i_mtime) ||
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!timespec64_equal(&inode->i_ctime, &upperinode->i_ctime))) {
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inode->i_mtime = upperinode->i_mtime;
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inode->i_ctime = upperinode->i_ctime;
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}
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touch_atime(&file->f_path);
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}
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static rwf_t ovl_iocb_to_rwf(struct kiocb *iocb)
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{
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int ifl = iocb->ki_flags;
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rwf_t flags = 0;
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if (ifl & IOCB_NOWAIT)
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flags |= RWF_NOWAIT;
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if (ifl & IOCB_HIPRI)
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flags |= RWF_HIPRI;
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if (ifl & IOCB_DSYNC)
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flags |= RWF_DSYNC;
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if (ifl & IOCB_SYNC)
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flags |= RWF_SYNC;
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return flags;
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}
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static ssize_t ovl_read_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct file *file = iocb->ki_filp;
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struct fd real;
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const struct cred *old_cred;
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ssize_t ret;
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if (!iov_iter_count(iter))
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return 0;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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ret = vfs_iter_read(real.file, iter, &iocb->ki_pos,
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ovl_iocb_to_rwf(iocb));
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ovl_revert_creds(old_cred);
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ovl_file_accessed(file);
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fdput(real);
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return ret;
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}
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static ssize_t ovl_write_iter(struct kiocb *iocb, struct iov_iter *iter)
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{
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struct file *file = iocb->ki_filp;
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struct inode *inode = file_inode(file);
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struct fd real;
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const struct cred *old_cred;
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ssize_t ret;
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if (!iov_iter_count(iter))
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return 0;
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inode_lock(inode);
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/* Update mode */
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ovl_copyattr(ovl_inode_real(inode), inode);
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ret = file_remove_privs(file);
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if (ret)
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goto out_unlock;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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goto out_unlock;
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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file_start_write(real.file);
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ret = vfs_iter_write(real.file, iter, &iocb->ki_pos,
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ovl_iocb_to_rwf(iocb));
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file_end_write(real.file);
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ovl_revert_creds(old_cred);
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/* Update size */
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ovl_copyattr(ovl_inode_real(inode), inode);
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fdput(real);
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out_unlock:
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inode_unlock(inode);
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return ret;
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}
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static int ovl_fsync(struct file *file, loff_t start, loff_t end, int datasync)
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{
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struct fd real;
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const struct cred *old_cred;
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int ret;
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ret = ovl_real_fdget_meta(file, &real, !datasync);
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if (ret)
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return ret;
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/* Don't sync lower file for fear of receiving EROFS error */
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if (file_inode(real.file) == ovl_inode_upper(file_inode(file))) {
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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ret = vfs_fsync_range(real.file, start, end, datasync);
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ovl_revert_creds(old_cred);
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}
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fdput(real);
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return ret;
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}
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static int ovl_mmap(struct file *file, struct vm_area_struct *vma)
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{
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struct file *realfile = file->private_data;
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const struct cred *old_cred;
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int ret;
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if (!realfile->f_op->mmap)
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return -ENODEV;
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if (WARN_ON(file != vma->vm_file))
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return -EIO;
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vma->vm_file = get_file(realfile);
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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ret = call_mmap(vma->vm_file, vma);
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ovl_revert_creds(old_cred);
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if (ret) {
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/* Drop reference count from new vm_file value */
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fput(realfile);
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} else {
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/* Drop reference count from previous vm_file value */
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fput(file);
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}
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ovl_file_accessed(file);
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return ret;
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}
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static long ovl_fallocate(struct file *file, int mode, loff_t offset, loff_t len)
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{
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struct inode *inode = file_inode(file);
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struct fd real;
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const struct cred *old_cred;
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int ret;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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ret = vfs_fallocate(real.file, mode, offset, len);
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ovl_revert_creds(old_cred);
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/* Update size */
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ovl_copyattr(ovl_inode_real(inode), inode);
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fdput(real);
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return ret;
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}
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static int ovl_fadvise(struct file *file, loff_t offset, loff_t len, int advice)
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{
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struct fd real;
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const struct cred *old_cred;
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int ret;
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ret = ovl_real_fdget(file, &real);
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if (ret)
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return ret;
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old_cred = ovl_override_creds(file_inode(file)->i_sb);
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ret = vfs_fadvise(real.file, offset, len, advice);
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|
ovl_revert_creds(old_cred);
|
||
|
|
|
||
|
|
fdput(real);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_real_ioctl(struct file *file, unsigned int cmd,
|
||
|
|
unsigned long arg)
|
||
|
|
{
|
||
|
|
struct fd real;
|
||
|
|
const struct cred *old_cred;
|
||
|
|
long ret;
|
||
|
|
|
||
|
|
ret = ovl_real_fdget(file, &real);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
old_cred = ovl_override_creds(file_inode(file)->i_sb);
|
||
|
|
ret = vfs_ioctl(real.file, cmd, arg);
|
||
|
|
ovl_revert_creds(old_cred);
|
||
|
|
|
||
|
|
fdput(real);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_ioctl_set_flags(struct file *file, unsigned int cmd,
|
||
|
|
unsigned long arg, unsigned int iflags)
|
||
|
|
{
|
||
|
|
long ret;
|
||
|
|
struct inode *inode = file_inode(file);
|
||
|
|
unsigned int old_iflags;
|
||
|
|
|
||
|
|
if (!inode_owner_or_capable(inode))
|
||
|
|
return -EACCES;
|
||
|
|
|
||
|
|
ret = mnt_want_write_file(file);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
inode_lock(inode);
|
||
|
|
|
||
|
|
/* Check the capability before cred override */
|
||
|
|
ret = -EPERM;
|
||
|
|
old_iflags = READ_ONCE(inode->i_flags);
|
||
|
|
if (((iflags ^ old_iflags) & (S_APPEND | S_IMMUTABLE)) &&
|
||
|
|
!capable(CAP_LINUX_IMMUTABLE))
|
||
|
|
goto unlock;
|
||
|
|
|
||
|
|
ret = ovl_maybe_copy_up(file_dentry(file), O_WRONLY);
|
||
|
|
if (ret)
|
||
|
|
goto unlock;
|
||
|
|
|
||
|
|
ret = ovl_real_ioctl(file, cmd, arg);
|
||
|
|
|
||
|
|
ovl_copyflags(ovl_inode_real(inode), inode);
|
||
|
|
unlock:
|
||
|
|
inode_unlock(inode);
|
||
|
|
|
||
|
|
mnt_drop_write_file(file);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
}
|
||
|
|
|
||
|
|
static unsigned int ovl_fsflags_to_iflags(unsigned int flags)
|
||
|
|
{
|
||
|
|
unsigned int iflags = 0;
|
||
|
|
|
||
|
|
if (flags & FS_SYNC_FL)
|
||
|
|
iflags |= S_SYNC;
|
||
|
|
if (flags & FS_APPEND_FL)
|
||
|
|
iflags |= S_APPEND;
|
||
|
|
if (flags & FS_IMMUTABLE_FL)
|
||
|
|
iflags |= S_IMMUTABLE;
|
||
|
|
if (flags & FS_NOATIME_FL)
|
||
|
|
iflags |= S_NOATIME;
|
||
|
|
|
||
|
|
return iflags;
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_ioctl_set_fsflags(struct file *file, unsigned int cmd,
|
||
|
|
unsigned long arg)
|
||
|
|
{
|
||
|
|
unsigned int flags;
|
||
|
|
|
||
|
|
if (get_user(flags, (int __user *) arg))
|
||
|
|
return -EFAULT;
|
||
|
|
|
||
|
|
return ovl_ioctl_set_flags(file, cmd, arg,
|
||
|
|
ovl_fsflags_to_iflags(flags));
|
||
|
|
}
|
||
|
|
|
||
|
|
static unsigned int ovl_fsxflags_to_iflags(unsigned int xflags)
|
||
|
|
{
|
||
|
|
unsigned int iflags = 0;
|
||
|
|
|
||
|
|
if (xflags & FS_XFLAG_SYNC)
|
||
|
|
iflags |= S_SYNC;
|
||
|
|
if (xflags & FS_XFLAG_APPEND)
|
||
|
|
iflags |= S_APPEND;
|
||
|
|
if (xflags & FS_XFLAG_IMMUTABLE)
|
||
|
|
iflags |= S_IMMUTABLE;
|
||
|
|
if (xflags & FS_XFLAG_NOATIME)
|
||
|
|
iflags |= S_NOATIME;
|
||
|
|
|
||
|
|
return iflags;
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_ioctl_set_fsxflags(struct file *file, unsigned int cmd,
|
||
|
|
unsigned long arg)
|
||
|
|
{
|
||
|
|
struct fsxattr fa;
|
||
|
|
|
||
|
|
memset(&fa, 0, sizeof(fa));
|
||
|
|
if (copy_from_user(&fa, (void __user *) arg, sizeof(fa)))
|
||
|
|
return -EFAULT;
|
||
|
|
|
||
|
|
return ovl_ioctl_set_flags(file, cmd, arg,
|
||
|
|
ovl_fsxflags_to_iflags(fa.fsx_xflags));
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
|
||
|
|
{
|
||
|
|
long ret;
|
||
|
|
|
||
|
|
switch (cmd) {
|
||
|
|
case FS_IOC_GETFLAGS:
|
||
|
|
case FS_IOC_FSGETXATTR:
|
||
|
|
ret = ovl_real_ioctl(file, cmd, arg);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case FS_IOC_SETFLAGS:
|
||
|
|
ret = ovl_ioctl_set_fsflags(file, cmd, arg);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case FS_IOC_FSSETXATTR:
|
||
|
|
ret = ovl_ioctl_set_fsxflags(file, cmd, arg);
|
||
|
|
break;
|
||
|
|
|
||
|
|
default:
|
||
|
|
ret = -ENOTTY;
|
||
|
|
}
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static long ovl_compat_ioctl(struct file *file, unsigned int cmd,
|
||
|
|
unsigned long arg)
|
||
|
|
{
|
||
|
|
switch (cmd) {
|
||
|
|
case FS_IOC32_GETFLAGS:
|
||
|
|
cmd = FS_IOC_GETFLAGS;
|
||
|
|
break;
|
||
|
|
|
||
|
|
case FS_IOC32_SETFLAGS:
|
||
|
|
cmd = FS_IOC_SETFLAGS;
|
||
|
|
break;
|
||
|
|
|
||
|
|
default:
|
||
|
|
return -ENOIOCTLCMD;
|
||
|
|
}
|
||
|
|
|
||
|
|
return ovl_ioctl(file, cmd, arg);
|
||
|
|
}
|
||
|
|
|
||
|
|
enum ovl_copyop {
|
||
|
|
OVL_COPY,
|
||
|
|
OVL_CLONE,
|
||
|
|
OVL_DEDUPE,
|
||
|
|
};
|
||
|
|
|
||
|
|
static ssize_t ovl_copyfile(struct file *file_in, loff_t pos_in,
|
||
|
|
struct file *file_out, loff_t pos_out,
|
||
|
|
u64 len, unsigned int flags, enum ovl_copyop op)
|
||
|
|
{
|
||
|
|
struct inode *inode_out = file_inode(file_out);
|
||
|
|
struct fd real_in, real_out;
|
||
|
|
const struct cred *old_cred;
|
||
|
|
ssize_t ret;
|
||
|
|
|
||
|
|
ret = ovl_real_fdget(file_out, &real_out);
|
||
|
|
if (ret)
|
||
|
|
return ret;
|
||
|
|
|
||
|
|
ret = ovl_real_fdget(file_in, &real_in);
|
||
|
|
if (ret) {
|
||
|
|
fdput(real_out);
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
old_cred = ovl_override_creds(file_inode(file_out)->i_sb);
|
||
|
|
switch (op) {
|
||
|
|
case OVL_COPY:
|
||
|
|
ret = vfs_copy_file_range(real_in.file, pos_in,
|
||
|
|
real_out.file, pos_out, len, flags);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case OVL_CLONE:
|
||
|
|
ret = vfs_clone_file_range(real_in.file, pos_in,
|
||
|
|
real_out.file, pos_out, len);
|
||
|
|
break;
|
||
|
|
|
||
|
|
case OVL_DEDUPE:
|
||
|
|
ret = vfs_dedupe_file_range_one(real_in.file, pos_in,
|
||
|
|
real_out.file, pos_out, len);
|
||
|
|
break;
|
||
|
|
}
|
||
|
|
ovl_revert_creds(old_cred);
|
||
|
|
|
||
|
|
/* Update size */
|
||
|
|
ovl_copyattr(ovl_inode_real(inode_out), inode_out);
|
||
|
|
|
||
|
|
fdput(real_in);
|
||
|
|
fdput(real_out);
|
||
|
|
|
||
|
|
return ret;
|
||
|
|
}
|
||
|
|
|
||
|
|
static ssize_t ovl_copy_file_range(struct file *file_in, loff_t pos_in,
|
||
|
|
struct file *file_out, loff_t pos_out,
|
||
|
|
size_t len, unsigned int flags)
|
||
|
|
{
|
||
|
|
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, flags,
|
||
|
|
OVL_COPY);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int ovl_clone_file_range(struct file *file_in, loff_t pos_in,
|
||
|
|
struct file *file_out, loff_t pos_out, u64 len)
|
||
|
|
{
|
||
|
|
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
|
||
|
|
OVL_CLONE);
|
||
|
|
}
|
||
|
|
|
||
|
|
static int ovl_dedupe_file_range(struct file *file_in, loff_t pos_in,
|
||
|
|
struct file *file_out, loff_t pos_out, u64 len)
|
||
|
|
{
|
||
|
|
/*
|
||
|
|
* Don't copy up because of a dedupe request, this wouldn't make sense
|
||
|
|
* most of the time (data would be duplicated instead of deduplicated).
|
||
|
|
*/
|
||
|
|
if (!ovl_inode_upper(file_inode(file_in)) ||
|
||
|
|
!ovl_inode_upper(file_inode(file_out)))
|
||
|
|
return -EPERM;
|
||
|
|
|
||
|
|
return ovl_copyfile(file_in, pos_in, file_out, pos_out, len, 0,
|
||
|
|
OVL_DEDUPE);
|
||
|
|
}
|
||
|
|
|
||
|
|
const struct file_operations ovl_file_operations = {
|
||
|
|
.open = ovl_open,
|
||
|
|
.release = ovl_release,
|
||
|
|
.llseek = ovl_llseek,
|
||
|
|
.read_iter = ovl_read_iter,
|
||
|
|
.write_iter = ovl_write_iter,
|
||
|
|
.fsync = ovl_fsync,
|
||
|
|
.mmap = ovl_mmap,
|
||
|
|
.fallocate = ovl_fallocate,
|
||
|
|
.fadvise = ovl_fadvise,
|
||
|
|
.unlocked_ioctl = ovl_ioctl,
|
||
|
|
.compat_ioctl = ovl_compat_ioctl,
|
||
|
|
|
||
|
|
.copy_file_range = ovl_copy_file_range,
|
||
|
|
.clone_file_range = ovl_clone_file_range,
|
||
|
|
.dedupe_file_range = ovl_dedupe_file_range,
|
||
|
|
};
|