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440 lines
13 KiB
440 lines
13 KiB
/**
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* eCryptfs: Linux filesystem encryption layer
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*
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* Copyright (C) 1997-2004 Erez Zadok
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* Copyright (C) 2001-2004 Stony Brook University
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* Copyright (C) 2004-2006 International Business Machines Corp.
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* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
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* Michael C. Thompson <mcthomps@us.ibm.com>
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License as
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* published by the Free Software Foundation; either version 2 of the
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* License, or (at your option) any later version.
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*
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* This program is distributed in the hope that it will be useful, but
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* WITHOUT ANY WARRANTY; without even the implied warranty of
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* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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* General Public License for more details.
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*
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* You should have received a copy of the GNU General Public License
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* along with this program; if not, write to the Free Software
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* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
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* 02111-1307, USA.
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*/
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#include <linux/file.h>
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#include <linux/poll.h>
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#include <linux/mount.h>
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#include <linux/pagemap.h>
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#include <linux/security.h>
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#include <linux/smp_lock.h>
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#include <linux/compat.h>
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#include "ecryptfs_kernel.h"
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/**
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* ecryptfs_llseek
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* @file: File we are seeking in
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* @offset: The offset to seek to
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* @origin: 2 - offset from i_size; 1 - offset from f_pos
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*
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* Returns the position we have seeked to, or negative on error
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*/
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static loff_t ecryptfs_llseek(struct file *file, loff_t offset, int origin)
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{
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loff_t rv;
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loff_t new_end_pos;
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int rc;
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int expanding_file = 0;
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struct inode *inode = file->f_mapping->host;
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/* If our offset is past the end of our file, we're going to
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* need to grow it so we have a valid length of 0's */
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new_end_pos = offset;
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switch (origin) {
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case 2:
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new_end_pos += i_size_read(inode);
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expanding_file = 1;
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break;
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case 1:
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new_end_pos += file->f_pos;
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if (new_end_pos > i_size_read(inode)) {
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ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
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"> i_size_read(inode)(=[0x%.16x])\n",
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new_end_pos, i_size_read(inode));
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expanding_file = 1;
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}
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break;
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default:
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if (new_end_pos > i_size_read(inode)) {
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ecryptfs_printk(KERN_DEBUG, "new_end_pos(=[0x%.16x]) "
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"> i_size_read(inode)(=[0x%.16x])\n",
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new_end_pos, i_size_read(inode));
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expanding_file = 1;
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}
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}
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ecryptfs_printk(KERN_DEBUG, "new_end_pos = [0x%.16x]\n", new_end_pos);
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if (expanding_file) {
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rc = ecryptfs_truncate(file->f_dentry, new_end_pos);
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if (rc) {
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rv = rc;
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ecryptfs_printk(KERN_ERR, "Error on attempt to "
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"truncate to (higher) offset [0x%.16x];"
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" rc = [%d]\n", new_end_pos, rc);
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goto out;
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}
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}
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rv = generic_file_llseek(file, offset, origin);
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out:
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return rv;
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}
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/**
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* ecryptfs_read_update_atime
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*
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* generic_file_read updates the atime of upper layer inode. But, it
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* doesn't give us a chance to update the atime of the lower layer
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* inode. This function is a wrapper to generic_file_read. It
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* updates the atime of the lower level inode if generic_file_read
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* returns without any errors. This is to be used only for file reads.
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* The function to be used for directory reads is ecryptfs_read.
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*/
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static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
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const struct iovec *iov,
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unsigned long nr_segs, loff_t pos)
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{
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int rc;
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struct dentry *lower_dentry;
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struct vfsmount *lower_vfsmount;
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struct file *file = iocb->ki_filp;
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rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
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/*
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* Even though this is a async interface, we need to wait
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* for IO to finish to update atime
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*/
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if (-EIOCBQUEUED == rc)
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rc = wait_on_sync_kiocb(iocb);
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if (rc >= 0) {
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lower_dentry = ecryptfs_dentry_to_lower(file->f_dentry);
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lower_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_dentry);
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touch_atime(lower_vfsmount, lower_dentry);
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}
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return rc;
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}
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struct ecryptfs_getdents_callback {
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void *dirent;
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struct dentry *dentry;
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filldir_t filldir;
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int err;
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int filldir_called;
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int entries_written;
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};
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/* Inspired by generic filldir in fs/readir.c */
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static int
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ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
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u64 ino, unsigned int d_type)
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{
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struct ecryptfs_crypt_stat *crypt_stat;
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struct ecryptfs_getdents_callback *buf =
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(struct ecryptfs_getdents_callback *)dirent;
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int rc;
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int decoded_length;
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char *decoded_name;
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crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
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buf->filldir_called++;
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decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
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&decoded_name);
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if (decoded_length < 0) {
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rc = decoded_length;
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goto out;
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}
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rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
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ino, d_type);
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kfree(decoded_name);
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if (rc >= 0)
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buf->entries_written++;
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out:
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return rc;
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}
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/**
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* ecryptfs_readdir
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* @file: The ecryptfs file struct
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* @dirent: Directory entry
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* @filldir: The filldir callback function
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*/
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static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
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{
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int rc;
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struct file *lower_file;
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struct inode *inode;
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struct ecryptfs_getdents_callback buf;
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lower_file = ecryptfs_file_to_lower(file);
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lower_file->f_pos = file->f_pos;
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inode = file->f_dentry->d_inode;
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memset(&buf, 0, sizeof(buf));
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buf.dirent = dirent;
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buf.dentry = file->f_dentry;
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buf.filldir = filldir;
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retry:
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buf.filldir_called = 0;
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buf.entries_written = 0;
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buf.err = 0;
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rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
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if (buf.err)
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rc = buf.err;
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if (buf.filldir_called && !buf.entries_written)
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goto retry;
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file->f_pos = lower_file->f_pos;
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if (rc >= 0)
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ecryptfs_copy_attr_atime(inode, lower_file->f_dentry->d_inode);
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return rc;
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}
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struct kmem_cache *ecryptfs_file_info_cache;
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/**
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* ecryptfs_open
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* @inode: inode speciying file to open
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* @file: Structure to return filled in
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*
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* Opens the file specified by inode.
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*
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* Returns zero on success; non-zero otherwise
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*/
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static int ecryptfs_open(struct inode *inode, struct file *file)
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{
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int rc = 0;
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struct ecryptfs_crypt_stat *crypt_stat = NULL;
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struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
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struct dentry *ecryptfs_dentry = file->f_dentry;
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/* Private value of ecryptfs_dentry allocated in
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* ecryptfs_lookup() */
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struct dentry *lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
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struct inode *lower_inode = NULL;
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struct file *lower_file = NULL;
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struct vfsmount *lower_mnt;
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struct ecryptfs_file_info *file_info;
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int lower_flags;
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/* Released in ecryptfs_release or end of function if failure */
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file_info = kmem_cache_alloc(ecryptfs_file_info_cache, SLAB_KERNEL);
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ecryptfs_set_file_private(file, file_info);
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if (!file_info) {
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ecryptfs_printk(KERN_ERR,
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"Error attempting to allocate memory\n");
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rc = -ENOMEM;
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goto out;
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}
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memset(file_info, 0, sizeof(*file_info));
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lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
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crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
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mount_crypt_stat = &ecryptfs_superblock_to_private(
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ecryptfs_dentry->d_sb)->mount_crypt_stat;
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mutex_lock(&crypt_stat->cs_mutex);
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if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED)) {
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ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
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/* Policy code enabled in future release */
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ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_POLICY_APPLIED);
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ECRYPTFS_SET_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
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}
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mutex_unlock(&crypt_stat->cs_mutex);
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/* This mntget & dget is undone via fput when the file is released */
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dget(lower_dentry);
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lower_flags = file->f_flags;
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if ((lower_flags & O_ACCMODE) == O_WRONLY)
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lower_flags = (lower_flags & O_ACCMODE) | O_RDWR;
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if (file->f_flags & O_APPEND)
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lower_flags &= ~O_APPEND;
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lower_mnt = ecryptfs_dentry_to_lower_mnt(ecryptfs_dentry);
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mntget(lower_mnt);
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/* Corresponding fput() in ecryptfs_release() */
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lower_file = dentry_open(lower_dentry, lower_mnt, lower_flags);
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if (IS_ERR(lower_file)) {
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rc = PTR_ERR(lower_file);
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ecryptfs_printk(KERN_ERR, "Error opening lower file\n");
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goto out_puts;
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}
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ecryptfs_set_file_lower(file, lower_file);
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/* Isn't this check the same as the one in lookup? */
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lower_inode = lower_dentry->d_inode;
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if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
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ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
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ECRYPTFS_CLEAR_FLAG(crypt_stat->flags, ECRYPTFS_ENCRYPTED);
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rc = 0;
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goto out;
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}
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mutex_lock(&crypt_stat->cs_mutex);
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if (i_size_read(lower_inode) < ECRYPTFS_MINIMUM_HEADER_EXTENT_SIZE) {
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if (!(mount_crypt_stat->flags
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& ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
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rc = -EIO;
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printk(KERN_WARNING "Attempt to read file that is "
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"not in a valid eCryptfs format, and plaintext "
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"passthrough mode is not enabled; returning "
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"-EIO\n");
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mutex_unlock(&crypt_stat->cs_mutex);
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goto out_puts;
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}
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crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
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rc = 0;
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mutex_unlock(&crypt_stat->cs_mutex);
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goto out;
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} else if (!ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
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ECRYPTFS_POLICY_APPLIED)
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|| !ECRYPTFS_CHECK_FLAG(crypt_stat->flags,
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ECRYPTFS_KEY_VALID)) {
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rc = ecryptfs_read_headers(ecryptfs_dentry, lower_file);
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if (rc) {
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ecryptfs_printk(KERN_DEBUG,
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"Valid headers not found\n");
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if (!(mount_crypt_stat->flags
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& ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
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rc = -EIO;
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printk(KERN_WARNING "Attempt to read file that "
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"is not in a valid eCryptfs format, "
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"and plaintext passthrough mode is not "
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"enabled; returning -EIO\n");
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mutex_unlock(&crypt_stat->cs_mutex);
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goto out_puts;
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}
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ECRYPTFS_CLEAR_FLAG(crypt_stat->flags,
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ECRYPTFS_ENCRYPTED);
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rc = 0;
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mutex_unlock(&crypt_stat->cs_mutex);
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goto out;
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}
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}
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mutex_unlock(&crypt_stat->cs_mutex);
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ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = [0x%.16x] "
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"size: [0x%.16x]\n", inode, inode->i_ino,
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i_size_read(inode));
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ecryptfs_set_file_lower(file, lower_file);
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goto out;
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out_puts:
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mntput(lower_mnt);
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dput(lower_dentry);
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kmem_cache_free(ecryptfs_file_info_cache,
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ecryptfs_file_to_private(file));
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out:
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return rc;
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}
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static int ecryptfs_flush(struct file *file, fl_owner_t td)
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{
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int rc = 0;
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struct file *lower_file = NULL;
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lower_file = ecryptfs_file_to_lower(file);
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if (lower_file->f_op && lower_file->f_op->flush)
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rc = lower_file->f_op->flush(lower_file, td);
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return rc;
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}
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static int ecryptfs_release(struct inode *inode, struct file *file)
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{
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struct file *lower_file = ecryptfs_file_to_lower(file);
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struct ecryptfs_file_info *file_info = ecryptfs_file_to_private(file);
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struct inode *lower_inode = ecryptfs_inode_to_lower(inode);
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fput(lower_file);
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inode->i_blocks = lower_inode->i_blocks;
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kmem_cache_free(ecryptfs_file_info_cache, file_info);
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return 0;
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}
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static int
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ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
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{
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struct file *lower_file = ecryptfs_file_to_lower(file);
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struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
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struct inode *lower_inode = lower_dentry->d_inode;
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int rc = -EINVAL;
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if (lower_inode->i_fop->fsync) {
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mutex_lock(&lower_inode->i_mutex);
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rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
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datasync);
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mutex_unlock(&lower_inode->i_mutex);
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}
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return rc;
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}
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static int ecryptfs_fasync(int fd, struct file *file, int flag)
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{
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int rc = 0;
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struct file *lower_file = NULL;
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lower_file = ecryptfs_file_to_lower(file);
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if (lower_file->f_op && lower_file->f_op->fasync)
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rc = lower_file->f_op->fasync(fd, lower_file, flag);
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return rc;
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}
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static ssize_t ecryptfs_sendfile(struct file *file, loff_t * ppos,
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size_t count, read_actor_t actor, void *target)
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{
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struct file *lower_file = NULL;
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int rc = -EINVAL;
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lower_file = ecryptfs_file_to_lower(file);
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if (lower_file->f_op && lower_file->f_op->sendfile)
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rc = lower_file->f_op->sendfile(lower_file, ppos, count,
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actor, target);
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return rc;
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}
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static int ecryptfs_ioctl(struct inode *inode, struct file *file,
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unsigned int cmd, unsigned long arg);
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const struct file_operations ecryptfs_dir_fops = {
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.readdir = ecryptfs_readdir,
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.ioctl = ecryptfs_ioctl,
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.mmap = generic_file_mmap,
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.open = ecryptfs_open,
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.flush = ecryptfs_flush,
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.release = ecryptfs_release,
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.fsync = ecryptfs_fsync,
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.fasync = ecryptfs_fasync,
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.sendfile = ecryptfs_sendfile,
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};
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const struct file_operations ecryptfs_main_fops = {
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.llseek = ecryptfs_llseek,
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.read = do_sync_read,
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.aio_read = ecryptfs_read_update_atime,
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.write = do_sync_write,
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.aio_write = generic_file_aio_write,
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.readdir = ecryptfs_readdir,
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.ioctl = ecryptfs_ioctl,
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.mmap = generic_file_mmap,
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.open = ecryptfs_open,
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.flush = ecryptfs_flush,
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.release = ecryptfs_release,
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.fsync = ecryptfs_fsync,
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.fasync = ecryptfs_fasync,
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.sendfile = ecryptfs_sendfile,
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};
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static int
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ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
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unsigned long arg)
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{
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int rc = 0;
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struct file *lower_file = NULL;
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if (ecryptfs_file_to_private(file))
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lower_file = ecryptfs_file_to_lower(file);
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if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
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rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
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lower_file, cmd, arg);
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else
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rc = -ENOTTY;
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return rc;
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}
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