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linux/fs/ecryptfs/inode.c

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/**
* 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 <mahalcro@us.ibm.com>
* Michael C. Thompsion <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/vmalloc.h>
#include <linux/pagemap.h>
#include <linux/dcache.h>
#include <linux/namei.h>
#include <linux/mount.h>
#include <linux/crypto.h>
#include <linux/fs_stack.h>
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"
static struct dentry *lock_parent(struct dentry *dentry)
{
struct dentry *dir;
dir = dget_parent(dentry);
mutex_lock_nested(&(dir->d_inode->i_mutex), I_MUTEX_PARENT);
return dir;
}
static void unlock_dir(struct dentry *dir)
{
mutex_unlock(&dir->d_inode->i_mutex);
dput(dir);
}
/**
* ecryptfs_create_underlying_file
* @lower_dir_inode: inode of the parent in the lower fs of the new file
* @dentry: New file's dentry
* @mode: The mode of the new file
* @nd: nameidata of ecryptfs' parent's dentry & vfsmount
*
* Creates the file in the lower file system.
*
* Returns zero on success; non-zero on error condition
*/
static int
ecryptfs_create_underlying_file(struct inode *lower_dir_inode,
struct dentry *dentry, int mode,
struct nameidata *nd)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
struct vfsmount *lower_mnt = ecryptfs_dentry_to_lower_mnt(dentry);
struct dentry *dentry_save;
struct vfsmount *vfsmount_save;
int rc;
dentry_save = nd->path.dentry;
vfsmount_save = nd->path.mnt;
nd->path.dentry = lower_dentry;
nd->path.mnt = lower_mnt;
rc = vfs_create(lower_dir_inode, lower_dentry, mode, nd);
nd->path.dentry = dentry_save;
nd->path.mnt = vfsmount_save;
return rc;
}
/**
* ecryptfs_do_create
* @directory_inode: inode of the new file's dentry's parent in ecryptfs
* @ecryptfs_dentry: New file's dentry in ecryptfs
* @mode: The mode of the new file
* @nd: nameidata of ecryptfs' parent's dentry & vfsmount
*
* Creates the underlying file and the eCryptfs inode which will link to
* it. It will also update the eCryptfs directory inode to mimic the
* stat of the lower directory inode.
*
* Returns zero on success; non-zero on error condition
*/
static int
ecryptfs_do_create(struct inode *directory_inode,
struct dentry *ecryptfs_dentry, int mode,
struct nameidata *nd)
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
lower_dir_dentry = lock_parent(lower_dentry);
if (IS_ERR(lower_dir_dentry)) {
ecryptfs_printk(KERN_ERR, "Error locking directory of "
"dentry\n");
rc = PTR_ERR(lower_dir_dentry);
goto out;
}
rc = ecryptfs_create_underlying_file(lower_dir_dentry->d_inode,
ecryptfs_dentry, mode, nd);
if (rc) {
printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
"rc = [%d]\n", __func__, rc);
goto out_lock;
}
rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
directory_inode->i_sb, 0);
if (rc) {
ecryptfs_printk(KERN_ERR, "Failure in ecryptfs_interpose\n");
goto out_lock;
}
fsstack_copy_attr_times(directory_inode, lower_dir_dentry->d_inode);
fsstack_copy_inode_size(directory_inode, lower_dir_dentry->d_inode);
out_lock:
unlock_dir(lower_dir_dentry);
out:
return rc;
}
/**
* grow_file
* @ecryptfs_dentry: the eCryptfs dentry
*
* This is the code which will grow the file to its correct size.
*/
static int grow_file(struct dentry *ecryptfs_dentry)
{
struct inode *ecryptfs_inode = ecryptfs_dentry->d_inode;
struct file fake_file;
struct ecryptfs_file_info tmp_file_info;
char zero_virt[] = { 0x00 };
int rc = 0;
memset(&fake_file, 0, sizeof(fake_file));
fake_file.f_path.dentry = ecryptfs_dentry;
memset(&tmp_file_info, 0, sizeof(tmp_file_info));
ecryptfs_set_file_private(&fake_file, &tmp_file_info);
ecryptfs_set_file_lower(
&fake_file,
ecryptfs_inode_to_private(ecryptfs_inode)->lower_file);
rc = ecryptfs_write(&fake_file, zero_virt, 0, 1);
i_size_write(ecryptfs_inode, 0);
rc = ecryptfs_write_inode_size_to_metadata(ecryptfs_inode);
ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat.flags |=
ECRYPTFS_NEW_FILE;
return rc;
}
/**
* ecryptfs_initialize_file
*
* Cause the file to be changed from a basic empty file to an ecryptfs
* file with a header and first data page.
*
* Returns zero on success
*/
static int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(ecryptfs_dentry->d_inode)->crypt_stat;
int rc = 0;
if (S_ISDIR(ecryptfs_dentry->d_inode->i_mode)) {
ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
goto out;
}
crypt_stat->flags |= ECRYPTFS_NEW_FILE;
ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
rc = ecryptfs_new_file_context(ecryptfs_dentry);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error creating new file "
"context; rc = [%d]\n", rc);
goto out;
}
if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_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;
}
}
rc = ecryptfs_write_metadata(ecryptfs_dentry);
if (rc) {
printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
goto out;
}
rc = grow_file(ecryptfs_dentry);
if (rc)
printk(KERN_ERR "Error growing file; rc = [%d]\n", rc);
out:
return rc;
}
/**
* ecryptfs_create
* @dir: The inode of the directory in which to create the file.
* @dentry: The eCryptfs dentry
* @mode: The mode of the new file.
* @nd: nameidata
*
* Creates a new file.
*
* Returns zero on success; non-zero on error condition
*/
static int
ecryptfs_create(struct inode *directory_inode, struct dentry *ecryptfs_dentry,
int mode, struct nameidata *nd)
{
int rc;
/* ecryptfs_do_create() calls ecryptfs_interpose() */
rc = ecryptfs_do_create(directory_inode, ecryptfs_dentry, mode, nd);
if (unlikely(rc)) {
ecryptfs_printk(KERN_WARNING, "Failed to create file in"
"lower filesystem\n");
goto out;
}
/* At this point, a file exists on "disk"; we need to make sure
* that this on disk file is prepared to be an ecryptfs file */
rc = ecryptfs_initialize_file(ecryptfs_dentry);
out:
return rc;
}
/**
* ecryptfs_lookup_and_interpose_lower - Perform a lookup
*/
int ecryptfs_lookup_and_interpose_lower(struct dentry *ecryptfs_dentry,
struct dentry *lower_dentry,
struct inode *ecryptfs_dir_inode,
struct nameidata *ecryptfs_nd)
{
struct dentry *lower_dir_dentry;
struct vfsmount *lower_mnt;
struct inode *lower_inode;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct ecryptfs_crypt_stat *crypt_stat;
char *page_virt = NULL;
u64 file_size;
int rc = 0;
lower_dir_dentry = lower_dentry->d_parent;
lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(
ecryptfs_dentry->d_parent));
lower_inode = lower_dentry->d_inode;
fsstack_copy_attr_atime(ecryptfs_dir_inode, lower_dir_dentry->d_inode);
BUG_ON(!atomic_read(&lower_dentry->d_count));
ecryptfs_set_dentry_private(ecryptfs_dentry,
kmem_cache_alloc(ecryptfs_dentry_info_cache,
GFP_KERNEL));
if (!ecryptfs_dentry_to_private(ecryptfs_dentry)) {
rc = -ENOMEM;
printk(KERN_ERR "%s: Out of memory whilst attempting "
"to allocate ecryptfs_dentry_info struct\n",
__func__);
goto out_dput;
}
ecryptfs_set_dentry_lower(ecryptfs_dentry, lower_dentry);
ecryptfs_set_dentry_lower_mnt(ecryptfs_dentry, lower_mnt);
if (!lower_dentry->d_inode) {
/* We want to add because we couldn't find in lower */
d_add(ecryptfs_dentry, NULL);
goto out;
}
rc = ecryptfs_interpose(lower_dentry, ecryptfs_dentry,
ecryptfs_dir_inode->i_sb, 1);
if (rc) {
printk(KERN_ERR "%s: Error interposing; rc = [%d]\n",
__func__, rc);
goto out;
}
if (S_ISDIR(lower_inode->i_mode))
goto out;
if (S_ISLNK(lower_inode->i_mode))
goto out;
if (special_file(lower_inode->i_mode))
goto out;
if (!ecryptfs_nd)
goto out;
/* Released in this function */
page_virt = kmem_cache_zalloc(ecryptfs_header_cache_2, GFP_USER);
if (!page_virt) {
printk(KERN_ERR "%s: Cannot kmem_cache_zalloc() a page\n",
__func__);
rc = -ENOMEM;
goto out;
}
if (!ecryptfs_inode_to_private(ecryptfs_dentry->d_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_free_kmem;
}
}
crypt_stat = &ecryptfs_inode_to_private(
ecryptfs_dentry->d_inode)->crypt_stat;
/* TODO: lock for crypt_stat comparison */
if (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED))
ecryptfs_set_default_sizes(crypt_stat);
rc = ecryptfs_read_and_validate_header_region(page_virt,
ecryptfs_dentry->d_inode);
if (rc) {
rc = ecryptfs_read_and_validate_xattr_region(page_virt,
ecryptfs_dentry);
if (rc) {
rc = 0;
goto out_free_kmem;
}
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
}
mount_crypt_stat = &ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
if (mount_crypt_stat->flags & ECRYPTFS_ENCRYPTED_VIEW_ENABLED) {
if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
file_size = (crypt_stat->num_header_bytes_at_front
+ i_size_read(lower_dentry->d_inode));
else
file_size = i_size_read(lower_dentry->d_inode);
} else {
file_size = get_unaligned_be64(page_virt);
}
i_size_write(ecryptfs_dentry->d_inode, (loff_t)file_size);
out_free_kmem:
kmem_cache_free(ecryptfs_header_cache_2, page_virt);
goto out;
out_dput:
dput(lower_dentry);
d_drop(ecryptfs_dentry);
out:
return rc;
}
/**
* ecryptfs_lookup
* @ecryptfs_dir_inode: The eCryptfs directory inode
* @ecryptfs_dentry: The eCryptfs dentry that we are looking up
* @ecryptfs_nd: nameidata; may be NULL
*
* Find a file on disk. If the file does not exist, then we'll add it to the
* dentry cache and continue on to read it from the disk.
*/
static struct dentry *ecryptfs_lookup(struct inode *ecryptfs_dir_inode,
struct dentry *ecryptfs_dentry,
struct nameidata *ecryptfs_nd)
{
char *encrypted_and_encoded_name = NULL;
size_t encrypted_and_encoded_name_size;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
struct dentry *lower_dir_dentry, *lower_dentry;
int rc = 0;
ecryptfs_dentry->d_op = &ecryptfs_dops;
if ((ecryptfs_dentry->d_name.len == 1
&& !strcmp(ecryptfs_dentry->d_name.name, "."))
|| (ecryptfs_dentry->d_name.len == 2
&& !strcmp(ecryptfs_dentry->d_name.name, ".."))) {
goto out_d_drop;
}
lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
lower_dentry = lookup_one_len(ecryptfs_dentry->d_name.name,
lower_dir_dentry,
ecryptfs_dentry->d_name.len);
mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
if (IS_ERR(lower_dentry)) {
rc = PTR_ERR(lower_dentry);
printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
"lower_dentry = [%s]\n", __func__, rc,
ecryptfs_dentry->d_name.name);
goto out_d_drop;
}
if (lower_dentry->d_inode)
goto lookup_and_interpose;
mount_crypt_stat = &ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
if (!(mount_crypt_stat
&& (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)))
goto lookup_and_interpose;
dput(lower_dentry);
rc = ecryptfs_encrypt_and_encode_filename(
&encrypted_and_encoded_name, &encrypted_and_encoded_name_size,
NULL, mount_crypt_stat, ecryptfs_dentry->d_name.name,
ecryptfs_dentry->d_name.len);
if (rc) {
printk(KERN_ERR "%s: Error attempting to encrypt and encode "
"filename; rc = [%d]\n", __func__, rc);
goto out_d_drop;
}
mutex_lock(&lower_dir_dentry->d_inode->i_mutex);
lower_dentry = lookup_one_len(encrypted_and_encoded_name,
lower_dir_dentry,
encrypted_and_encoded_name_size - 1);
mutex_unlock(&lower_dir_dentry->d_inode->i_mutex);
if (IS_ERR(lower_dentry)) {
rc = PTR_ERR(lower_dentry);
printk(KERN_ERR "%s: lookup_one_len() returned [%d] on "
"lower_dentry = [%s]\n", __func__, rc,
encrypted_and_encoded_name);
goto out_d_drop;
}
lookup_and_interpose:
rc = ecryptfs_lookup_and_interpose_lower(ecryptfs_dentry, lower_dentry,
ecryptfs_dir_inode,
ecryptfs_nd);
goto out;
out_d_drop:
d_drop(ecryptfs_dentry);
out:
kfree(encrypted_and_encoded_name);
return ERR_PTR(rc);
}
static int ecryptfs_link(struct dentry *old_dentry, struct inode *dir,
struct dentry *new_dentry)
{
struct dentry *lower_old_dentry;
struct dentry *lower_new_dentry;
struct dentry *lower_dir_dentry;
u64 file_size_save;
int rc;
file_size_save = i_size_read(old_dentry->d_inode);
lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
dget(lower_old_dentry);
dget(lower_new_dentry);
lower_dir_dentry = lock_parent(lower_new_dentry);
rc = vfs_link(lower_old_dentry, lower_dir_dentry->d_inode,
lower_new_dentry);
if (rc || !lower_new_dentry->d_inode)
goto out_lock;
rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb, 0);
if (rc)
goto out_lock;
fsstack_copy_attr_times(dir, lower_new_dentry->d_inode);
fsstack_copy_inode_size(dir, lower_new_dentry->d_inode);
old_dentry->d_inode->i_nlink =
ecryptfs_inode_to_lower(old_dentry->d_inode)->i_nlink;
i_size_write(new_dentry->d_inode, file_size_save);
out_lock:
unlock_dir(lower_dir_dentry);
dput(lower_new_dentry);
dput(lower_old_dentry);
d_drop(lower_old_dentry);
d_drop(new_dentry);
d_drop(old_dentry);
return rc;
}
static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
{
int rc = 0;
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
struct inode *lower_dir_inode = ecryptfs_inode_to_lower(dir);
struct dentry *lower_dir_dentry;
dget(lower_dentry);
lower_dir_dentry = lock_parent(lower_dentry);
rc = vfs_unlink(lower_dir_inode, lower_dentry);
if (rc) {
printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
goto out_unlock;
}
fsstack_copy_attr_times(dir, lower_dir_inode);
dentry->d_inode->i_nlink =
ecryptfs_inode_to_lower(dentry->d_inode)->i_nlink;
dentry->d_inode->i_ctime = dir->i_ctime;
d_drop(dentry);
out_unlock:
unlock_dir(lower_dir_dentry);
dput(lower_dentry);
return rc;
}
static int ecryptfs_symlink(struct inode *dir, struct dentry *dentry,
const char *symname)
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
char *encoded_symname;
size_t encoded_symlen;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat = NULL;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
dget(lower_dentry);
lower_dir_dentry = lock_parent(lower_dentry);
mount_crypt_stat = &ecryptfs_superblock_to_private(
dir->i_sb)->mount_crypt_stat;
rc = ecryptfs_encrypt_and_encode_filename(&encoded_symname,
&encoded_symlen,
NULL,
mount_crypt_stat, symname,
strlen(symname));
if (rc)
goto out_lock;
rc = vfs_symlink(lower_dir_dentry->d_inode, lower_dentry,
encoded_symname);
kfree(encoded_symname);
if (rc || !lower_dentry->d_inode)
goto out_lock;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
if (rc)
goto out_lock;
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
out_lock:
unlock_dir(lower_dir_dentry);
dput(lower_dentry);
if (!dentry->d_inode)
d_drop(dentry);
return rc;
}
static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, int mode)
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
lower_dir_dentry = lock_parent(lower_dentry);
rc = vfs_mkdir(lower_dir_dentry->d_inode, lower_dentry, mode);
if (rc || !lower_dentry->d_inode)
goto out;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
if (rc)
goto out;
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
out:
unlock_dir(lower_dir_dentry);
if (!dentry->d_inode)
d_drop(dentry);
return rc;
}
static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
{
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
int rc;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
dget(dentry);
lower_dir_dentry = lock_parent(lower_dentry);
dget(lower_dentry);
rc = vfs_rmdir(lower_dir_dentry->d_inode, lower_dentry);
dput(lower_dentry);
if (!rc)
d_delete(lower_dentry);
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
dir->i_nlink = lower_dir_dentry->d_inode->i_nlink;
unlock_dir(lower_dir_dentry);
if (!rc)
d_drop(dentry);
dput(dentry);
return rc;
}
static int
ecryptfs_mknod(struct inode *dir, struct dentry *dentry, int mode, dev_t dev)
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
lower_dir_dentry = lock_parent(lower_dentry);
rc = vfs_mknod(lower_dir_dentry->d_inode, lower_dentry, mode, dev);
if (rc || !lower_dentry->d_inode)
goto out;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb, 0);
if (rc)
goto out;
fsstack_copy_attr_times(dir, lower_dir_dentry->d_inode);
fsstack_copy_inode_size(dir, lower_dir_dentry->d_inode);
out:
unlock_dir(lower_dir_dentry);
if (!dentry->d_inode)
d_drop(dentry);
return rc;
}
static int
ecryptfs_rename(struct inode *old_dir, struct dentry *old_dentry,
struct inode *new_dir, struct dentry *new_dentry)
{
int rc;
struct dentry *lower_old_dentry;
struct dentry *lower_new_dentry;
struct dentry *lower_old_dir_dentry;
struct dentry *lower_new_dir_dentry;
lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
dget(lower_old_dentry);
dget(lower_new_dentry);
lower_old_dir_dentry = dget_parent(lower_old_dentry);
lower_new_dir_dentry = dget_parent(lower_new_dentry);
lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
rc = vfs_rename(lower_old_dir_dentry->d_inode, lower_old_dentry,
lower_new_dir_dentry->d_inode, lower_new_dentry);
if (rc)
goto out_lock;
fsstack_copy_attr_all(new_dir, lower_new_dir_dentry->d_inode, NULL);
if (new_dir != old_dir)
fsstack_copy_attr_all(old_dir, lower_old_dir_dentry->d_inode, NULL);
out_lock:
unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
dput(lower_new_dentry->d_parent);
dput(lower_old_dentry->d_parent);
dput(lower_new_dentry);
dput(lower_old_dentry);
return rc;
}
static int
ecryptfs_readlink(struct dentry *dentry, char __user *buf, int bufsiz)
{
char *lower_buf;
size_t lower_bufsiz;
struct dentry *lower_dentry;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
char *plaintext_name;
size_t plaintext_name_size;
mm_segment_t old_fs;
int rc;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
if (!lower_dentry->d_inode->i_op->readlink) {
rc = -EINVAL;
goto out;
}
mount_crypt_stat = &ecryptfs_superblock_to_private(
dentry->d_sb)->mount_crypt_stat;
/*
* If the lower filename is encrypted, it will result in a significantly
* longer name. If needed, truncate the name after decode and decrypt.
*/
if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES)
lower_bufsiz = PATH_MAX;
else
lower_bufsiz = bufsiz;
/* Released in this function */
lower_buf = kmalloc(lower_bufsiz, GFP_KERNEL);
if (lower_buf == NULL) {
printk(KERN_ERR "%s: Out of memory whilst attempting to "
"kmalloc [%zd] bytes\n", __func__, lower_bufsiz);
rc = -ENOMEM;
goto out;
}
old_fs = get_fs();
set_fs(get_ds());
rc = lower_dentry->d_inode->i_op->readlink(lower_dentry,
(char __user *)lower_buf,
lower_bufsiz);
set_fs(old_fs);
if (rc >= 0) {
rc = ecryptfs_decode_and_decrypt_filename(&plaintext_name,
&plaintext_name_size,
dentry, lower_buf,
rc);
if (rc) {
printk(KERN_ERR "%s: Error attempting to decode and "
"decrypt filename; rc = [%d]\n", __func__,
rc);
goto out_free_lower_buf;
}
/* Check for bufsiz <= 0 done in sys_readlinkat() */
rc = copy_to_user(buf, plaintext_name,
min((size_t) bufsiz, plaintext_name_size));
if (rc)
rc = -EFAULT;
else
rc = plaintext_name_size;
kfree(plaintext_name);
fsstack_copy_attr_atime(dentry->d_inode, lower_dentry->d_inode);
}
out_free_lower_buf:
kfree(lower_buf);
out:
return rc;
}
static void *ecryptfs_follow_link(struct dentry *dentry, struct nameidata *nd)
{
char *buf;
int len = PAGE_SIZE, rc;
mm_segment_t old_fs;
/* Released in ecryptfs_put_link(); only release here on error */
buf = kmalloc(len, GFP_KERNEL);
if (!buf) {
rc = -ENOMEM;
goto out;
}
old_fs = get_fs();
set_fs(get_ds());
rc = dentry->d_inode->i_op->readlink(dentry, (char __user *)buf, len);
set_fs(old_fs);
if (rc < 0)
goto out_free;
else
buf[rc] = '\0';
rc = 0;
nd_set_link(nd, buf);
goto out;
out_free:
kfree(buf);
out:
return ERR_PTR(rc);
}
static void
ecryptfs_put_link(struct dentry *dentry, struct nameidata *nd, void *ptr)
{
/* Free the char* */
kfree(nd_get_link(nd));
}
/**
* upper_size_to_lower_size
* @crypt_stat: Crypt_stat associated with file
* @upper_size: Size of the upper file
*
* Calculate the required size of the lower file based on the
* specified size of the upper file. This calculation is based on the
* number of headers in the underlying file and the extent size.
*
* Returns Calculated size of the lower file.
*/
static loff_t
upper_size_to_lower_size(struct ecryptfs_crypt_stat *crypt_stat,
loff_t upper_size)
{
loff_t lower_size;
lower_size = crypt_stat->num_header_bytes_at_front;
if (upper_size != 0) {
loff_t num_extents;
num_extents = upper_size >> crypt_stat->extent_shift;
if (upper_size & ~crypt_stat->extent_mask)
num_extents++;
lower_size += (num_extents * crypt_stat->extent_size);
}
return lower_size;
}
/**
* ecryptfs_truncate
* @dentry: The ecryptfs layer dentry
* @new_length: The length to expand the file to
*
* Function to handle truncations modifying the size of the file. Note
* that the file sizes are interpolated. When expanding, we are simply
* writing strings of 0's out. When truncating, we need to modify the
* underlying file size according to the page index interpolations.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
{
int rc = 0;
struct inode *inode = dentry->d_inode;
struct dentry *lower_dentry;
struct file fake_ecryptfs_file;
struct ecryptfs_crypt_stat *crypt_stat;
loff_t i_size = i_size_read(inode);
loff_t lower_size_before_truncate;
loff_t lower_size_after_truncate;
if (unlikely((new_length == i_size)))
goto out;
crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
/* Set up a fake ecryptfs file, this is used to interface with
* the file in the underlying filesystem so that the
* truncation has an effect there as well. */
memset(&fake_ecryptfs_file, 0, sizeof(fake_ecryptfs_file));
fake_ecryptfs_file.f_path.dentry = dentry;
/* Released at out_free: label */
ecryptfs_set_file_private(&fake_ecryptfs_file,
kmem_cache_alloc(ecryptfs_file_info_cache,
GFP_KERNEL));
if (unlikely(!ecryptfs_file_to_private(&fake_ecryptfs_file))) {
rc = -ENOMEM;
goto out;
}
lower_dentry = ecryptfs_dentry_to_lower(dentry);
ecryptfs_set_file_lower(
&fake_ecryptfs_file,
ecryptfs_inode_to_private(dentry->d_inode)->lower_file);
/* Switch on growing or shrinking file */
if (new_length > i_size) {
char zero[] = { 0x00 };
/* Write a single 0 at the last position of the file;
* this triggers code that will fill in 0's throughout
* the intermediate portion of the previous end of the
* file and the new and of the file */
rc = ecryptfs_write(&fake_ecryptfs_file, zero,
(new_length - 1), 1);
} else { /* new_length < i_size_read(inode) */
/* We're chopping off all the pages down do the page
* in which new_length is located. Fill in the end of
* that page from (new_length & ~PAGE_CACHE_MASK) to
* PAGE_CACHE_SIZE with zeros. */
size_t num_zeros = (PAGE_CACHE_SIZE
- (new_length & ~PAGE_CACHE_MASK));
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
rc = vmtruncate(inode, new_length);
if (rc)
goto out_free;
rc = vmtruncate(lower_dentry->d_inode, new_length);
goto out_free;
}
if (num_zeros) {
char *zeros_virt;
zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
if (!zeros_virt) {
rc = -ENOMEM;
goto out_free;
}
rc = ecryptfs_write(&fake_ecryptfs_file, zeros_virt,
new_length, num_zeros);
kfree(zeros_virt);
if (rc) {
printk(KERN_ERR "Error attempting to zero out "
"the remainder of the end page on "
"reducing truncate; rc = [%d]\n", rc);
goto out_free;
}
}
vmtruncate(inode, new_length);
rc = ecryptfs_write_inode_size_to_metadata(inode);
if (rc) {
printk(KERN_ERR "Problem with "
"ecryptfs_write_inode_size_to_metadata; "
"rc = [%d]\n", rc);
goto out_free;
}
/* We are reducing the size of the ecryptfs file, and need to
* know if we need to reduce the size of the lower file. */
lower_size_before_truncate =
upper_size_to_lower_size(crypt_stat, i_size);
lower_size_after_truncate =
upper_size_to_lower_size(crypt_stat, new_length);
if (lower_size_after_truncate < lower_size_before_truncate)
vmtruncate(lower_dentry->d_inode,
lower_size_after_truncate);
}
out_free:
if (ecryptfs_file_to_private(&fake_ecryptfs_file))
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(&fake_ecryptfs_file));
out:
return rc;
}
static int
ecryptfs_permission(struct inode *inode, int mask)
{
return inode_permission(ecryptfs_inode_to_lower(inode), mask);
}
/**
* ecryptfs_setattr
* @dentry: dentry handle to the inode to modify
* @ia: Structure with flags of what to change and values
*
* Updates the metadata of an inode. If the update is to the size
* i.e. truncation, then ecryptfs_truncate will handle the size modification
* of both the ecryptfs inode and the lower inode.
*
* All other metadata changes will be passed right to the lower filesystem,
* and we will just update our inode to look like the lower.
*/
static int ecryptfs_setattr(struct dentry *dentry, struct iattr *ia)
{
int rc = 0;
struct dentry *lower_dentry;
struct inode *inode;
struct inode *lower_inode;
struct ecryptfs_crypt_stat *crypt_stat;
crypt_stat = &ecryptfs_inode_to_private(dentry->d_inode)->crypt_stat;
if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED))
ecryptfs_init_crypt_stat(crypt_stat);
inode = dentry->d_inode;
lower_inode = ecryptfs_inode_to_lower(inode);
lower_dentry = ecryptfs_dentry_to_lower(dentry);
mutex_lock(&crypt_stat->cs_mutex);
if (S_ISDIR(dentry->d_inode->i_mode))
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
else if (S_ISREG(dentry->d_inode->i_mode)
&& (!(crypt_stat->flags & ECRYPTFS_POLICY_APPLIED)
|| !(crypt_stat->flags & ECRYPTFS_KEY_VALID))) {
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
mount_crypt_stat = &ecryptfs_superblock_to_private(
dentry->d_sb)->mount_crypt_stat;
rc = ecryptfs_read_metadata(dentry);
if (rc) {
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;
}
rc = 0;
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
}
}
mutex_unlock(&crypt_stat->cs_mutex);
if (ia->ia_valid & ATTR_SIZE) {
ecryptfs_printk(KERN_DEBUG,
"ia->ia_valid = [0x%x] ATTR_SIZE" " = [0x%x]\n",
ia->ia_valid, ATTR_SIZE);
rc = ecryptfs_truncate(dentry, ia->ia_size);
/* ecryptfs_truncate handles resizing of the lower file */
ia->ia_valid &= ~ATTR_SIZE;
ecryptfs_printk(KERN_DEBUG, "ia->ia_valid = [%x]\n",
ia->ia_valid);
if (rc < 0)
goto out;
}
/*
* mode change is for clearing setuid/setgid bits. Allow lower fs
* to interpret this in its own way.
*/
if (ia->ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
ia->ia_valid &= ~ATTR_MODE;
mutex_lock(&lower_dentry->d_inode->i_mutex);
rc = notify_change(lower_dentry, ia);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
fsstack_copy_attr_all(inode, lower_inode, NULL);
return rc;
}
int
ecryptfs_setxattr(struct dentry *dentry, const char *name, const void *value,
size_t size, int flags)
{
int rc = 0;
struct dentry *lower_dentry;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
if (!lower_dentry->d_inode->i_op->setxattr) {
rc = -ENOSYS;
goto out;
}
mutex_lock(&lower_dentry->d_inode->i_mutex);
rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry, name, value,
size, flags);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
return rc;
}
ssize_t
ecryptfs_getxattr_lower(struct dentry *lower_dentry, const char *name,
void *value, size_t size)
{
int rc = 0;
if (!lower_dentry->d_inode->i_op->getxattr) {
rc = -ENOSYS;
goto out;
}
mutex_lock(&lower_dentry->d_inode->i_mutex);
rc = lower_dentry->d_inode->i_op->getxattr(lower_dentry, name, value,
size);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
return rc;
}
static ssize_t
ecryptfs_getxattr(struct dentry *dentry, const char *name, void *value,
size_t size)
{
return ecryptfs_getxattr_lower(ecryptfs_dentry_to_lower(dentry), name,
value, size);
}
static ssize_t
ecryptfs_listxattr(struct dentry *dentry, char *list, size_t size)
{
int rc = 0;
struct dentry *lower_dentry;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
if (!lower_dentry->d_inode->i_op->listxattr) {
rc = -ENOSYS;
goto out;
}
mutex_lock(&lower_dentry->d_inode->i_mutex);
rc = lower_dentry->d_inode->i_op->listxattr(lower_dentry, list, size);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
return rc;
}
static int ecryptfs_removexattr(struct dentry *dentry, const char *name)
{
int rc = 0;
struct dentry *lower_dentry;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
if (!lower_dentry->d_inode->i_op->removexattr) {
rc = -ENOSYS;
goto out;
}
mutex_lock(&lower_dentry->d_inode->i_mutex);
rc = lower_dentry->d_inode->i_op->removexattr(lower_dentry, name);
mutex_unlock(&lower_dentry->d_inode->i_mutex);
out:
return rc;
}
int ecryptfs_inode_test(struct inode *inode, void *candidate_lower_inode)
{
if ((ecryptfs_inode_to_lower(inode)
== (struct inode *)candidate_lower_inode))
return 1;
else
return 0;
}
int ecryptfs_inode_set(struct inode *inode, void *lower_inode)
{
ecryptfs_init_inode(inode, (struct inode *)lower_inode);
return 0;
}
const struct inode_operations ecryptfs_symlink_iops = {
.readlink = ecryptfs_readlink,
.follow_link = ecryptfs_follow_link,
.put_link = ecryptfs_put_link,
.permission = ecryptfs_permission,
.setattr = ecryptfs_setattr,
.setxattr = ecryptfs_setxattr,
.getxattr = ecryptfs_getxattr,
.listxattr = ecryptfs_listxattr,
.removexattr = ecryptfs_removexattr
};
const struct inode_operations ecryptfs_dir_iops = {
.create = ecryptfs_create,
.lookup = ecryptfs_lookup,
.link = ecryptfs_link,
.unlink = ecryptfs_unlink,
.symlink = ecryptfs_symlink,
.mkdir = ecryptfs_mkdir,
.rmdir = ecryptfs_rmdir,
.mknod = ecryptfs_mknod,
.rename = ecryptfs_rename,
.permission = ecryptfs_permission,
.setattr = ecryptfs_setattr,
.setxattr = ecryptfs_setxattr,
.getxattr = ecryptfs_getxattr,
.listxattr = ecryptfs_listxattr,
.removexattr = ecryptfs_removexattr
};
const struct inode_operations ecryptfs_main_iops = {
.permission = ecryptfs_permission,
.setattr = ecryptfs_setattr,
.setxattr = ecryptfs_setxattr,
.getxattr = ecryptfs_getxattr,
.listxattr = ecryptfs_listxattr,
.removexattr = ecryptfs_removexattr
};
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