77 lines
1.9 KiB
C
77 lines
1.9 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/xattr.h>
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#include "overlayfs.h"
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static struct file *ovl_open_realfile(const struct file *file)
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{
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struct inode *inode = file_inode(file);
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struct inode *upperinode = ovl_inode_upper(inode);
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struct inode *realinode = upperinode ?: ovl_inode_lower(inode);
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struct file *realfile;
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const struct cred *old_cred;
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old_cred = ovl_override_creds(inode->i_sb);
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realfile = open_with_fake_path(&file->f_path, file->f_flags | O_NOATIME,
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realinode, current_cred());
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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, upperinode ? 'u' : 'l', 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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static int ovl_open(struct inode *inode, struct file *file)
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{
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struct dentry *dentry = file_dentry(file);
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struct file *realfile;
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int err;
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err = ovl_open_maybe_copy_up(dentry, 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);
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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 *realinode = ovl_inode_real(file_inode(file));
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return generic_file_llseek_size(file, offset, whence,
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realinode->i_sb->s_maxbytes,
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i_size_read(realinode));
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}
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const struct file_operations ovl_file_operations = {
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.open = ovl_open,
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.release = ovl_release,
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.llseek = ovl_llseek,
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};
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