kernel-ark/fs/ecryptfs/file.c
Michael Halcrow 391b52f98c eCryptfs: Make all persistent file opens delayed
There is no good reason to immediately open the lower file, and that can
cause problems with files that the user does not intend to immediately
open, such as device nodes.

This patch removes the persistent file open from the interpose step and
pushes that to the locations where eCryptfs really does need the lower
persistent file, such as just before reading or writing the metadata
stored in the lower file header.

Two functions are jumping to out_dput when they should just be jumping to
out on error paths.  This patch also fixes these.

Signed-off-by: Michael Halcrow <mhalcrow@us.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-07-24 10:47:31 -07:00

354 lines
10 KiB
C

/**
* 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/mount.h>
#include <linux/pagemap.h>
#include <linux/security.h>
#include <linux/compat.h>
#include <linux/fs_stack.h>
#include <linux/smp_lock.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)
{
int rc;
struct dentry *lower_dentry;
struct vfsmount *lower_vfsmount;
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_vfsmount = ecryptfs_dentry_to_lower_mnt(file->f_path.dentry);
touch_atime(lower_vfsmount, lower_dentry);
}
return rc;
}
struct ecryptfs_getdents_callback {
void *dirent;
struct dentry *dentry;
filldir_t filldir;
int err;
int filldir_called;
int entries_written;
};
/* Inspired by generic filldir in fs/readir.c */
static int
ecryptfs_filldir(void *dirent, const char *name, int namelen, loff_t offset,
u64 ino, unsigned int d_type)
{
struct ecryptfs_crypt_stat *crypt_stat;
struct ecryptfs_getdents_callback *buf =
(struct ecryptfs_getdents_callback *)dirent;
int rc;
int decoded_length;
char *decoded_name;
crypt_stat = ecryptfs_dentry_to_private(buf->dentry)->crypt_stat;
buf->filldir_called++;
decoded_length = ecryptfs_decode_filename(crypt_stat, name, namelen,
&decoded_name);
if (decoded_length < 0) {
rc = decoded_length;
goto out;
}
rc = buf->filldir(buf->dirent, decoded_name, decoded_length, offset,
ino, d_type);
kfree(decoded_name);
if (rc >= 0)
buf->entries_written++;
out:
return rc;
}
/**
* ecryptfs_readdir
* @file: The ecryptfs file struct
* @dirent: Directory entry
* @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;
retry:
buf.filldir_called = 0;
buf.entries_written = 0;
buf.err = 0;
rc = vfs_readdir(lower_file, ecryptfs_filldir, (void *)&buf);
if (buf.err)
rc = buf.err;
if (buf.filldir_called && !buf.entries_written)
goto retry;
file->f_pos = lower_file->f_pos;
if (rc >= 0)
fsstack_copy_attr_atime(inode, lower_file->f_path.dentry->d_inode);
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 = ecryptfs_dentry_to_lower(ecryptfs_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);
if ((ecryptfs_inode_to_private(inode)->lower_file->f_flags & O_RDONLY)
&& !(file->f_flags & O_RDONLY)) {
rc = -EPERM;
printk(KERN_WARNING "%s: Lower persistent file is RO; eCryptfs "
"file must hence be opened RO\n", __func__);
goto out;
}
if (!ecryptfs_inode_to_private(inode)->lower_file) {
rc = ecryptfs_init_persistent_file(ecryptfs_dentry);
if (rc) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the persistent file for the dentry with name "
"[%s]; rc = [%d]\n", __func__,
ecryptfs_dentry->d_name.name, rc);
goto out;
}
}
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_free;
}
rc = 0;
crypt_stat->flags &= ~(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%.16x] "
"size: [0x%.16x]\n", inode, inode->i_ino,
i_size_read(inode));
goto out;
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)
{
int rc = 0;
struct file *lower_file = NULL;
lower_file = ecryptfs_file_to_lower(file);
if (lower_file->f_op && lower_file->f_op->flush)
rc = lower_file->f_op->flush(lower_file, td);
return rc;
}
static int ecryptfs_release(struct inode *inode, struct file *file)
{
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static int
ecryptfs_fsync(struct file *file, struct dentry *dentry, int datasync)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
struct inode *lower_inode = lower_dentry->d_inode;
int rc = -EINVAL;
if (lower_inode->i_fop->fsync) {
mutex_lock(&lower_inode->i_mutex);
rc = lower_inode->i_fop->fsync(lower_file, lower_dentry,
datasync);
mutex_unlock(&lower_inode->i_mutex);
}
return rc;
}
static int ecryptfs_fasync(int fd, struct file *file, int flag)
{
int rc = 0;
struct file *lower_file = NULL;
lock_kernel();
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);
unlock_kernel();
return rc;
}
static int ecryptfs_ioctl(struct inode *inode, struct file *file,
unsigned int cmd, unsigned long arg);
const struct file_operations ecryptfs_dir_fops = {
.readdir = ecryptfs_readdir,
.ioctl = ecryptfs_ioctl,
.mmap = generic_file_mmap,
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
};
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,
.ioctl = ecryptfs_ioctl,
.mmap = generic_file_mmap,
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = generic_file_splice_read,
};
static int
ecryptfs_ioctl(struct inode *inode, struct file *file, unsigned int cmd,
unsigned long arg)
{
int rc = 0;
struct file *lower_file = NULL;
if (ecryptfs_file_to_private(file))
lower_file = ecryptfs_file_to_lower(file);
if (lower_file && lower_file->f_op && lower_file->f_op->ioctl)
rc = lower_file->f_op->ioctl(ecryptfs_inode_to_lower(inode),
lower_file, cmd, arg);
else
rc = -ENOTTY;
return rc;
}