/**
* eCryptfs: Linux filesystem encryption layer
*
* Copyright (C) 1997-2004 Erez Zadok
* Copyright (C) 2001-2004 Stony Brook University
* Copyright (C) 2004-2007 International Business Machines Corp.
* Author(s): Michael A. Halcrow <mhalcrow@us.ibm.com>
* Michael C. Thompson <mcthomps@us.ibm.com>
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License as
* published by the Free Software Foundation; either version 2 of the
* License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful, but
* WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
* General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
* 02111-1307, USA.
*/
#include <linux/file.h>
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/mount.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/compat.h>
#include <linux/fs_stack.h>
#include "ecryptfs_kernel.h"
/**
* ecryptfs_read_update_atime
*
* generic_file_read updates the atime of upper layer inode. But, it
* doesn't give us a chance to update the atime of the lower layer
* inode. This function is a wrapper to generic_file_read. It
* updates the atime of the lower level inode if generic_file_read
* returns without any errors. This is to be used only for file reads.
* The function to be used for directory reads is ecryptfs_read.
*/
static ssize_t ecryptfs_read_update_atime(struct kiocb *iocb,
const struct iovec *iov,
unsigned long nr_segs, loff_t pos)
{
ssize_t rc;
struct path lower;
struct file *file = iocb->ki_filp;
rc = generic_file_aio_read(iocb, iov, nr_segs, pos);
/*
* Even though this is a async interface, we need to wait
* for IO to finish to update atime
*/
if (-EIOCBQUEUED == rc)
rc = wait_on_sync_kiocb(iocb);
if (rc >= 0) {
lower.dentry = ecryptfs_dentry_to_lower(file->f_path.dentry);
lower.mnt = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
touch_atime(&lower);
}
return rc;
}
struct ecryptfs_getdents_callback {
void *dirent;
struct dentry *dentry;
filldir_t filldir;
int filldir_called;
int entries_written;
};
/* Inspired by generic filldir in fs/readdir.c */
static int
ecryptfs_filldir(void *dirent, const char *lower_name, int lower_namelen,
loff_t offset, u64 ino, unsigned int d_type)
{
struct ecryptfs_getdents_callback *buf =
(struct ecryptfs_getdents_callback *)dirent;
size_t name_size;
char *name;
int rc;
buf->filldir_called++;
rc = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
buf->dentry, lower_name,
lower_namelen);
if (rc) {
printk(KERN_ERR "%s: Error attempting to decode and decrypt "
"filename [%s]; rc = [%d]\n", __func__, lower_name,
rc);
goto out;
}
rc = buf->filldir(buf->dirent, name, name_size, offset, ino, d_type);
kfree(name);
if (rc >= 0)
buf->entries_written++;
out:
return rc;
}
/**
* ecryptfs_readdir
* @file: The eCryptfs directory file
* @dirent: Directory entry handle
* @filldir: The filldir callback function
*/
static int ecryptfs_readdir(struct file *file, void *dirent, filldir_t filldir)
{
int rc;
struct file *lower_file;
struct inode *inode;
struct ecryptfs_getdents_callback buf;
lower_file = ecryptfs_file_to_lower(file);
lower_file->f_pos = file->f_pos;
inode = file->f_path.dentry->d_inode;
memset(&buf, 0, sizeof(buf));
buf.dirent = dirent;
buf.dentry = file->f_path.dentry;
buf.filldir = filldir;
buf.filldir_called = 0;
buf.entries_written = 0;
rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
file->f_pos = lower_file->f_pos;
if (rc < 0)
goto out;
if (buf.filldir_called && !buf.entries_written)
goto out;
if (rc >= 0)
fsstack_copy_attr_atime(inode,
lower_file->f_path.dentry->d_inode);
out:
return rc;
}
static void ecryptfs_vma_close(struct vm_area_struct *vma)
{
filemap_write_and_wait(vma->vm_file->f_mapping);
}
static const struct vm_operations_struct ecryptfs_file_vm_ops = {
.close = ecryptfs_vma_close,
.fault = filemap_fault,
};
static int ecryptfs_file_mmap(struct file *file, struct vm_area_struct *vma)
{
int rc;
rc = generic_file_mmap(file, vma);
if (!rc)
vma->vm_ops = &ecryptfs_file_vm_ops;
return rc;
}
struct kmem_cache *ecryptfs_file_info_cache;
/**
* ecryptfs_open
* @inode: inode speciying file to open
* @file: Structure to return filled in
*
* Opens the file specified by inode.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_open(struct inode *inode, struct file *file)
{
int rc = 0;
struct ecryptfs_crypt_stat *crypt_stat = NULL;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct dentry *lower_dentry;
struct ecryptfs_file_info *file_info;
mount_crypt_stat = &ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
if ((mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED)
&& ((file->f_flags & O_WRONLY) || (file->f_flags & O_RDWR)
|| (file->f_flags & O_CREAT) || (file->f_flags & O_TRUNC)
|| (file->f_flags & O_APPEND))) {
printk(KERN_WARNING "Mount has encrypted view enabled; "
"files may only be read\n");
rc = -EPERM;
goto out;
}
/* Released in ecryptfs_release or end of function if failure */
file_info = kmem_cache_zalloc(ecryptfs_file_info_cache, GFP_KERNEL);
ecryptfs_set_file_private(file, file_info);
if (!file_info) {
ecryptfs_printk(KERN_ERR,
"Error attempting to allocate memory\n");
rc = -ENOMEM;
goto out;
}
lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
mutex_lock(&crypt_stat->cs_mutex);
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)) {
ecryptfs_printk(KERN_DEBUG, "Setting flags for stat...\n");
/* Policy code enabled in future release */
crypt_stat->flags |= (ECRYPTFS_POLICY_APPLIED
| ECRYPTFS_ENCRYPTED);
}
mutex_unlock(&crypt_stat->cs_mutex);
rc = ecryptfs_get_lower_file(ecryptfs_dentry, inode);
if (rc) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%s]; rc = [%d]\n", __func__,
ecryptfs_dentry->d_name.name, rc);
goto out_free;
}
if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_ACCMODE)
== O_RDONLY && (file->f_flags & O_ACCMODE) != O_RDONLY) {
rc = -EPERM;
printk(KERN_WARNING "%s: Lower file is RO; eCryptfs "
"file must hence be opened RO\n", __func__);
goto out_put;
}
ecryptfs_set_file_lower(
file, ecryptfs_inode_to_private(inode)->lower_file);
if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
mutex_lock(&crypt_stat->cs_mutex);
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
mutex_unlock(&crypt_stat->cs_mutex);
rc = 0;
goto out;
}
mutex_lock(&crypt_stat->cs_mutex);
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
|| !(crypt_stat->flags & ECRYPTFS_KEY_VALID)) {
rc = ecryptfs_read_metadata(ecryptfs_dentry);
if (rc) {
ecryptfs_printk(KERN_DEBUG,
"Valid headers not found\n");
if (!(mount_crypt_stat->flags
& ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED)) {
rc = -EIO;
printk(KERN_WARNING "Either the lower file "
"is not in a valid eCryptfs format, "
"or the key could not be retrieved. "
"Plaintext passthrough mode is not "
"enabled; returning -EIO\n");
mutex_unlock(&crypt_stat->cs_mutex);
goto out_put;
}
rc = 0;
crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
| ECRYPTFS_ENCRYPTED);
mutex_unlock(&crypt_stat->cs_mutex);
goto out;
}
}
mutex_unlock(&crypt_stat->cs_mutex);
ecryptfs_printk(KERN_DEBUG, "inode w/ addr = [0x%p], i_ino = "
"[0x%.16lx] size: [0x%.16llx]\n", inode, inode->i_ino,
(unsigned long long)i_size_read(inode));
goto out;
out_put:
ecryptfs_put_lower_file(inode);
out_free:
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
out:
return rc;
}
static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
return file->f_mode & FMODE_WRITE
? filemap_write_and_wait(file->f_mapping) : 0;
}
static int ecryptfs_release(struct inode *inode, struct file *file)
{
ecryptfs_put_lower_file(inode);
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static int
ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
int rc = 0;
rc = generic_file_fsync(file, start, end, datasync);
if (rc)
goto out;
rc = vfs_fsync_range(ecryptfs_file_to_lower(file), start, end,
datasync);
out:
return rc;
}
static int ecryptfs_fasync(int fd, struct file *file, int flag)
{
int rc = 0;
struct file *lower_file = NULL;
lower_file = ecryptfs_file_to_lower(file);
if (lower_file->f_op && lower_file->f_op->fasync)
rc = lower_file->f_op->fasync(fd, lower_file, flag);
return rc;
}
static long
ecryptfs_unlocked_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file = NULL;
long rc = -ENOTTY;
if (ecryptfs_file_to_private(file))
lower_file = ecryptfs_file_to_lower(file);
if (lower_file && lower_file->f_op && lower_file->f_op->unlocked_ioctl)
rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
return rc;
}
#ifdef CONFIG_COMPAT
static long
ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file = NULL;
long rc = -ENOIOCTLCMD;
if (ecryptfs_file_to_private(file))
lower_file = ecryptfs_file_to_lower(file);
if (lower_file && lower_file->f_op && lower_file->f_op->compat_ioctl)
rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
return rc;
}
#endif
const struct file_operations ecryptfs_dir_fops = {
.readdir = ecryptfs_readdir,
.read = generic_read_dir,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
.llseek = default_llseek,
};
const struct file_operations ecryptfs_main_fops = {
.llseek = generic_file_llseek,
.read = do_sync_read,
.aio_read = ecryptfs_read_update_atime,
.write = do_sync_write,
.aio_write = generic_file_aio_write,
.readdir = ecryptfs_readdir,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.mmap = ecryptfs_file_mmap,
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
};
