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inode.c
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inode.c
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// SPDX-License-Identifier: GPL-2.0-or-later
/**
* 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 <[email protected]>
* Michael C. Thompsion <[email protected]>
*/
#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/fs_stack.h>
#include <linux/slab.h>
#include <linux/xattr.h>
#include <asm/unaligned.h>
#include "ecryptfs_kernel.h"
static struct dentry *lock_parent(struct dentry *dentry)
{
struct dentry *dir;
dir = dget_parent(dentry);
inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
return dir;
}
static void unlock_dir(struct dentry *dir)
{
inode_unlock(d_inode(dir));
dput(dir);
}
static int ecryptfs_inode_test(struct inode *inode, void *lower_inode)
{
return ecryptfs_inode_to_lower(inode) == lower_inode;
}
static int ecryptfs_inode_set(struct inode *inode, void *opaque)
{
struct inode *lower_inode = opaque;
ecryptfs_set_inode_lower(inode, lower_inode);
fsstack_copy_attr_all(inode, lower_inode);
/* i_size will be overwritten for encrypted regular files */
fsstack_copy_inode_size(inode, lower_inode);
inode->i_ino = lower_inode->i_ino;
inode->i_mapping->a_ops = &ecryptfs_aops;
if (S_ISLNK(inode->i_mode))
inode->i_op = &ecryptfs_symlink_iops;
else if (S_ISDIR(inode->i_mode))
inode->i_op = &ecryptfs_dir_iops;
else
inode->i_op = &ecryptfs_main_iops;
if (S_ISDIR(inode->i_mode))
inode->i_fop = &ecryptfs_dir_fops;
else if (special_file(inode->i_mode))
init_special_inode(inode, inode->i_mode, inode->i_rdev);
else
inode->i_fop = &ecryptfs_main_fops;
return 0;
}
static struct inode *__ecryptfs_get_inode(struct inode *lower_inode,
struct super_block *sb)
{
struct inode *inode;
if (lower_inode->i_sb != ecryptfs_superblock_to_lower(sb))
return ERR_PTR(-EXDEV);
if (!igrab(lower_inode))
return ERR_PTR(-ESTALE);
inode = iget5_locked(sb, (unsigned long)lower_inode,
ecryptfs_inode_test, ecryptfs_inode_set,
lower_inode);
if (!inode) {
iput(lower_inode);
return ERR_PTR(-EACCES);
}
if (!(inode->i_state & I_NEW))
iput(lower_inode);
return inode;
}
struct inode *ecryptfs_get_inode(struct inode *lower_inode,
struct super_block *sb)
{
struct inode *inode = __ecryptfs_get_inode(lower_inode, sb);
if (!IS_ERR(inode) && (inode->i_state & I_NEW))
unlock_new_inode(inode);
return inode;
}
/**
* ecryptfs_interpose
* @lower_dentry: Existing dentry in the lower filesystem
* @dentry: ecryptfs' dentry
* @sb: ecryptfs's super_block
*
* Interposes upper and lower dentries.
*
* Returns zero on success; non-zero otherwise
*/
static int ecryptfs_interpose(struct dentry *lower_dentry,
struct dentry *dentry, struct super_block *sb)
{
struct inode *inode = ecryptfs_get_inode(d_inode(lower_dentry), sb);
if (IS_ERR(inode))
return PTR_ERR(inode);
d_instantiate(dentry, inode);
return 0;
}
static int ecryptfs_do_unlink(struct inode *dir, struct dentry *dentry,
struct inode *inode)
{
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
struct dentry *lower_dir_dentry;
struct inode *lower_dir_inode;
int rc;
lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
lower_dir_inode = d_inode(lower_dir_dentry);
inode_lock_nested(lower_dir_inode, I_MUTEX_PARENT);
dget(lower_dentry); // don't even try to make the lower negative
if (lower_dentry->d_parent != lower_dir_dentry)
rc = -EINVAL;
else if (d_unhashed(lower_dentry))
rc = -EINVAL;
else
rc = vfs_unlink(lower_dir_inode, lower_dentry, NULL);
if (rc) {
printk(KERN_ERR "Error in vfs_unlink; rc = [%d]\n", rc);
goto out_unlock;
}
fsstack_copy_attr_times(dir, lower_dir_inode);
set_nlink(inode, ecryptfs_inode_to_lower(inode)->i_nlink);
inode->i_ctime = dir->i_ctime;
out_unlock:
dput(lower_dentry);
inode_unlock(lower_dir_inode);
if (!rc)
d_drop(dentry);
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
*
* 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 the new eCryptfs inode on success; an ERR_PTR on error condition
*/
static struct inode *
ecryptfs_do_create(struct inode *directory_inode,
struct dentry *ecryptfs_dentry, umode_t mode)
{
int rc;
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
struct inode *inode;
lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
lower_dir_dentry = lock_parent(lower_dentry);
rc = vfs_create(d_inode(lower_dir_dentry), lower_dentry, mode, true);
if (rc) {
printk(KERN_ERR "%s: Failure to create dentry in lower fs; "
"rc = [%d]\n", __func__, rc);
inode = ERR_PTR(rc);
goto out_lock;
}
inode = __ecryptfs_get_inode(d_inode(lower_dentry),
directory_inode->i_sb);
if (IS_ERR(inode)) {
vfs_unlink(d_inode(lower_dir_dentry), lower_dentry, NULL);
goto out_lock;
}
fsstack_copy_attr_times(directory_inode, d_inode(lower_dir_dentry));
fsstack_copy_inode_size(directory_inode, d_inode(lower_dir_dentry));
out_lock:
unlock_dir(lower_dir_dentry);
return inode;
}
/**
* 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
*/
int ecryptfs_initialize_file(struct dentry *ecryptfs_dentry,
struct inode *ecryptfs_inode)
{
struct ecryptfs_crypt_stat *crypt_stat =
&ecryptfs_inode_to_private(ecryptfs_inode)->crypt_stat;
int rc = 0;
if (S_ISDIR(ecryptfs_inode->i_mode)) {
ecryptfs_printk(KERN_DEBUG, "This is a directory\n");
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
goto out;
}
ecryptfs_printk(KERN_DEBUG, "Initializing crypto context\n");
rc = ecryptfs_new_file_context(ecryptfs_inode);
if (rc) {
ecryptfs_printk(KERN_ERR, "Error creating new file "
"context; rc = [%d]\n", rc);
goto out;
}
rc = ecryptfs_get_lower_file(ecryptfs_dentry, ecryptfs_inode);
if (rc) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%d]\n", __func__,
ecryptfs_dentry, rc);
goto out;
}
rc = ecryptfs_write_metadata(ecryptfs_dentry, ecryptfs_inode);
if (rc)
printk(KERN_ERR "Error writing headers; rc = [%d]\n", rc);
ecryptfs_put_lower_file(ecryptfs_inode);
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.
*
* 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,
umode_t mode, bool excl)
{
struct inode *ecryptfs_inode;
int rc;
ecryptfs_inode = ecryptfs_do_create(directory_inode, ecryptfs_dentry,
mode);
if (IS_ERR(ecryptfs_inode)) {
ecryptfs_printk(KERN_WARNING, "Failed to create file in"
"lower filesystem\n");
rc = PTR_ERR(ecryptfs_inode);
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, ecryptfs_inode);
if (rc) {
ecryptfs_do_unlink(directory_inode, ecryptfs_dentry,
ecryptfs_inode);
iget_failed(ecryptfs_inode);
goto out;
}
d_instantiate_new(ecryptfs_dentry, ecryptfs_inode);
out:
return rc;
}
static int ecryptfs_i_size_read(struct dentry *dentry, struct inode *inode)
{
struct ecryptfs_crypt_stat *crypt_stat;
int rc;
rc = ecryptfs_get_lower_file(dentry, inode);
if (rc) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%d]\n", __func__,
dentry, rc);
return rc;
}
crypt_stat = &ecryptfs_inode_to_private(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(inode);
ecryptfs_put_lower_file(inode);
if (rc) {
rc = ecryptfs_read_and_validate_xattr_region(dentry, inode);
if (!rc)
crypt_stat->flags |= ECRYPTFS_METADATA_IN_XATTR;
}
/* Must return 0 to allow non-eCryptfs files to be looked up, too */
return 0;
}
/**
* ecryptfs_lookup_interpose - Dentry interposition for a lookup
*/
static struct dentry *ecryptfs_lookup_interpose(struct dentry *dentry,
struct dentry *lower_dentry)
{
struct inode *inode, *lower_inode;
struct ecryptfs_dentry_info *dentry_info;
struct vfsmount *lower_mnt;
int rc = 0;
dentry_info = kmem_cache_alloc(ecryptfs_dentry_info_cache, GFP_KERNEL);
if (!dentry_info) {
dput(lower_dentry);
return ERR_PTR(-ENOMEM);
}
lower_mnt = mntget(ecryptfs_dentry_to_lower_mnt(dentry->d_parent));
fsstack_copy_attr_atime(d_inode(dentry->d_parent),
d_inode(lower_dentry->d_parent));
BUG_ON(!d_count(lower_dentry));
ecryptfs_set_dentry_private(dentry, dentry_info);
dentry_info->lower_path.mnt = lower_mnt;
dentry_info->lower_path.dentry = lower_dentry;
/*
* negative dentry can go positive under us here - its parent is not
* locked. That's OK and that could happen just as we return from
* ecryptfs_lookup() anyway. Just need to be careful and fetch
* ->d_inode only once - it's not stable here.
*/
lower_inode = READ_ONCE(lower_dentry->d_inode);
if (!lower_inode) {
/* We want to add because we couldn't find in lower */
d_add(dentry, NULL);
return NULL;
}
inode = __ecryptfs_get_inode(lower_inode, dentry->d_sb);
if (IS_ERR(inode)) {
printk(KERN_ERR "%s: Error interposing; rc = [%ld]\n",
__func__, PTR_ERR(inode));
return ERR_CAST(inode);
}
if (S_ISREG(inode->i_mode)) {
rc = ecryptfs_i_size_read(dentry, inode);
if (rc) {
make_bad_inode(inode);
return ERR_PTR(rc);
}
}
if (inode->i_state & I_NEW)
unlock_new_inode(inode);
return d_splice_alias(inode, dentry);
}
/**
* ecryptfs_lookup
* @ecryptfs_dir_inode: The eCryptfs directory inode
* @ecryptfs_dentry: The eCryptfs dentry that we are looking up
* @flags: lookup flags
*
* 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,
unsigned int flags)
{
char *encrypted_and_encoded_name = NULL;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct dentry *lower_dir_dentry, *lower_dentry;
const char *name = ecryptfs_dentry->d_name.name;
size_t len = ecryptfs_dentry->d_name.len;
struct dentry *res;
int rc = 0;
lower_dir_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry->d_parent);
mount_crypt_stat = &ecryptfs_superblock_to_private(
ecryptfs_dentry->d_sb)->mount_crypt_stat;
if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
rc = ecryptfs_encrypt_and_encode_filename(
&encrypted_and_encoded_name, &len,
mount_crypt_stat, name, len);
if (rc) {
printk(KERN_ERR "%s: Error attempting to encrypt and encode "
"filename; rc = [%d]\n", __func__, rc);
return ERR_PTR(rc);
}
name = encrypted_and_encoded_name;
}
lower_dentry = lookup_one_len_unlocked(name, lower_dir_dentry, len);
if (IS_ERR(lower_dentry)) {
ecryptfs_printk(KERN_DEBUG, "%s: lookup_one_len() returned "
"[%ld] on lower_dentry = [%s]\n", __func__,
PTR_ERR(lower_dentry),
name);
res = ERR_CAST(lower_dentry);
} else {
res = ecryptfs_lookup_interpose(ecryptfs_dentry, lower_dentry);
}
kfree(encrypted_and_encoded_name);
return res;
}
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(d_inode(old_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_dir_dentry = lock_parent(lower_new_dentry);
rc = vfs_link(lower_old_dentry, d_inode(lower_dir_dentry),
lower_new_dentry, NULL);
if (rc || d_really_is_negative(lower_new_dentry))
goto out_lock;
rc = ecryptfs_interpose(lower_new_dentry, new_dentry, dir->i_sb);
if (rc)
goto out_lock;
fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
set_nlink(d_inode(old_dentry),
ecryptfs_inode_to_lower(d_inode(old_dentry))->i_nlink);
i_size_write(d_inode(new_dentry), file_size_save);
out_lock:
unlock_dir(lower_dir_dentry);
dput(lower_new_dentry);
dput(lower_old_dentry);
return rc;
}
static int ecryptfs_unlink(struct inode *dir, struct dentry *dentry)
{
return ecryptfs_do_unlink(dir, dentry, d_inode(dentry));
}
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,
mount_crypt_stat, symname,
strlen(symname));
if (rc)
goto out_lock;
rc = vfs_symlink(d_inode(lower_dir_dentry), lower_dentry,
encoded_symname);
kfree(encoded_symname);
if (rc || d_really_is_negative(lower_dentry))
goto out_lock;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
if (rc)
goto out_lock;
fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
out_lock:
unlock_dir(lower_dir_dentry);
dput(lower_dentry);
if (d_really_is_negative(dentry))
d_drop(dentry);
return rc;
}
static int ecryptfs_mkdir(struct inode *dir, struct dentry *dentry, umode_t 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(d_inode(lower_dir_dentry), lower_dentry, mode);
if (rc || d_really_is_negative(lower_dentry))
goto out;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
if (rc)
goto out;
fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
set_nlink(dir, d_inode(lower_dir_dentry)->i_nlink);
out:
unlock_dir(lower_dir_dentry);
if (d_really_is_negative(dentry))
d_drop(dentry);
return rc;
}
static int ecryptfs_rmdir(struct inode *dir, struct dentry *dentry)
{
struct dentry *lower_dentry;
struct dentry *lower_dir_dentry;
struct inode *lower_dir_inode;
int rc;
lower_dentry = ecryptfs_dentry_to_lower(dentry);
lower_dir_dentry = ecryptfs_dentry_to_lower(dentry->d_parent);
lower_dir_inode = d_inode(lower_dir_dentry);
inode_lock_nested(lower_dir_inode, I_MUTEX_PARENT);
dget(lower_dentry); // don't even try to make the lower negative
if (lower_dentry->d_parent != lower_dir_dentry)
rc = -EINVAL;
else if (d_unhashed(lower_dentry))
rc = -EINVAL;
else
rc = vfs_rmdir(lower_dir_inode, lower_dentry);
if (!rc) {
clear_nlink(d_inode(dentry));
fsstack_copy_attr_times(dir, lower_dir_inode);
set_nlink(dir, lower_dir_inode->i_nlink);
}
dput(lower_dentry);
inode_unlock(lower_dir_inode);
if (!rc)
d_drop(dentry);
return rc;
}
static int
ecryptfs_mknod(struct inode *dir, struct dentry *dentry, umode_t 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(d_inode(lower_dir_dentry), lower_dentry, mode, dev);
if (rc || d_really_is_negative(lower_dentry))
goto out;
rc = ecryptfs_interpose(lower_dentry, dentry, dir->i_sb);
if (rc)
goto out;
fsstack_copy_attr_times(dir, d_inode(lower_dir_dentry));
fsstack_copy_inode_size(dir, d_inode(lower_dir_dentry));
out:
unlock_dir(lower_dir_dentry);
if (d_really_is_negative(dentry))
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,
unsigned int flags)
{
int rc;
struct dentry *lower_old_dentry;
struct dentry *lower_new_dentry;
struct dentry *lower_old_dir_dentry;
struct dentry *lower_new_dir_dentry;
struct dentry *trap;
struct inode *target_inode;
if (flags)
return -EINVAL;
lower_old_dir_dentry = ecryptfs_dentry_to_lower(old_dentry->d_parent);
lower_new_dir_dentry = ecryptfs_dentry_to_lower(new_dentry->d_parent);
lower_old_dentry = ecryptfs_dentry_to_lower(old_dentry);
lower_new_dentry = ecryptfs_dentry_to_lower(new_dentry);
target_inode = d_inode(new_dentry);
trap = lock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
dget(lower_new_dentry);
rc = -EINVAL;
if (lower_old_dentry->d_parent != lower_old_dir_dentry)
goto out_lock;
if (lower_new_dentry->d_parent != lower_new_dir_dentry)
goto out_lock;
if (d_unhashed(lower_old_dentry) || d_unhashed(lower_new_dentry))
goto out_lock;
/* source should not be ancestor of target */
if (trap == lower_old_dentry)
goto out_lock;
/* target should not be ancestor of source */
if (trap == lower_new_dentry) {
rc = -ENOTEMPTY;
goto out_lock;
}
rc = vfs_rename(d_inode(lower_old_dir_dentry), lower_old_dentry,
d_inode(lower_new_dir_dentry), lower_new_dentry,
NULL, 0);
if (rc)
goto out_lock;
if (target_inode)
fsstack_copy_attr_all(target_inode,
ecryptfs_inode_to_lower(target_inode));
fsstack_copy_attr_all(new_dir, d_inode(lower_new_dir_dentry));
if (new_dir != old_dir)
fsstack_copy_attr_all(old_dir, d_inode(lower_old_dir_dentry));
out_lock:
dput(lower_new_dentry);
unlock_rename(lower_old_dir_dentry, lower_new_dir_dentry);
return rc;
}
static char *ecryptfs_readlink_lower(struct dentry *dentry, size_t *bufsiz)
{
DEFINE_DELAYED_CALL(done);
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
const char *link;
char *buf;
int rc;
link = vfs_get_link(lower_dentry, &done);
if (IS_ERR(link))
return ERR_CAST(link);
rc = ecryptfs_decode_and_decrypt_filename(&buf, bufsiz, dentry->d_sb,
link, strlen(link));
do_delayed_call(&done);
if (rc)
return ERR_PTR(rc);
return buf;
}
static const char *ecryptfs_get_link(struct dentry *dentry,
struct inode *inode,
struct delayed_call *done)
{
size_t len;
char *buf;
if (!dentry)
return ERR_PTR(-ECHILD);
buf = ecryptfs_readlink_lower(dentry, &len);
if (IS_ERR(buf))
return buf;
fsstack_copy_attr_atime(d_inode(dentry),
d_inode(ecryptfs_dentry_to_lower(dentry)));
buf[len] = '\0';
set_delayed_call(done, kfree_link, buf);
return buf;
}
/**
* 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 = ecryptfs_lower_header_size(crypt_stat);
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;
}
/**
* truncate_upper
* @dentry: The ecryptfs layer dentry
* @ia: Address of the ecryptfs inode's attributes
* @lower_ia: Address of the lower inode's attributes
*
* 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 truncate the upper
* inode and update the lower_ia according to the page index
* interpolations. If ATTR_SIZE is set in lower_ia->ia_valid upon return,
* the caller must use lower_ia in a call to notify_change() to perform
* the truncation of the lower inode.
*
* Returns zero on success; non-zero otherwise
*/
static int truncate_upper(struct dentry *dentry, struct iattr *ia,
struct iattr *lower_ia)
{
int rc = 0;
struct inode *inode = d_inode(dentry);
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((ia->ia_size == i_size))) {
lower_ia->ia_valid &= ~ATTR_SIZE;
return 0;
}
rc = ecryptfs_get_lower_file(dentry, inode);
if (rc)
return rc;
crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
/* Switch on growing or shrinking file */
if (ia->ia_size > i_size) {
char zero[] = { 0x00 };
lower_ia->ia_valid &= ~ATTR_SIZE;
/* 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(inode, zero,
(ia->ia_size - 1), 1);
} else { /* ia->ia_size < i_size_read(inode) */
/* We're chopping off all the pages down to the page
* in which ia->ia_size is located. Fill in the end of
* that page from (ia->ia_size & ~PAGE_MASK) to
* PAGE_SIZE with zeros. */
size_t num_zeros = (PAGE_SIZE
- (ia->ia_size & ~PAGE_MASK));
if (!(crypt_stat->flags & ECRYPTFS_ENCRYPTED)) {
truncate_setsize(inode, ia->ia_size);
lower_ia->ia_size = ia->ia_size;
lower_ia->ia_valid |= ATTR_SIZE;
goto out;
}
if (num_zeros) {
char *zeros_virt;
zeros_virt = kzalloc(num_zeros, GFP_KERNEL);
if (!zeros_virt) {
rc = -ENOMEM;
goto out;
}
rc = ecryptfs_write(inode, zeros_virt,
ia->ia_size, 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;
}
}
truncate_setsize(inode, ia->ia_size);
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;
}
/* 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, ia->ia_size);
if (lower_size_after_truncate < lower_size_before_truncate) {
lower_ia->ia_size = lower_size_after_truncate;
lower_ia->ia_valid |= ATTR_SIZE;
} else
lower_ia->ia_valid &= ~ATTR_SIZE;
}
out:
ecryptfs_put_lower_file(inode);
return rc;
}
static int ecryptfs_inode_newsize_ok(struct inode *inode, loff_t offset)
{
struct ecryptfs_crypt_stat *crypt_stat;
loff_t lower_oldsize, lower_newsize;
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
lower_oldsize = upper_size_to_lower_size(crypt_stat,
i_size_read(inode));
lower_newsize = upper_size_to_lower_size(crypt_stat, offset);
if (lower_newsize > lower_oldsize) {
/*
* The eCryptfs inode and the new *lower* size are mixed here
* because we may not have the lower i_mutex held and/or it may
* not be appropriate to call inode_newsize_ok() with inodes
* from other filesystems.
*/
return inode_newsize_ok(inode, lower_newsize);
}
return 0;
}
/**
* ecryptfs_truncate
* @dentry: The ecryptfs layer dentry
* @new_length: The length to expand the file to
*
* Simple function that handles the truncation of an eCryptfs inode and
* its corresponding lower inode.
*
* Returns zero on success; non-zero otherwise
*/
int ecryptfs_truncate(struct dentry *dentry, loff_t new_length)
{
struct iattr ia = { .ia_valid = ATTR_SIZE, .ia_size = new_length };
struct iattr lower_ia = { .ia_valid = 0 };
int rc;
rc = ecryptfs_inode_newsize_ok(d_inode(dentry), new_length);
if (rc)
return rc;
rc = truncate_upper(dentry, &ia, &lower_ia);
if (!rc && lower_ia.ia_valid & ATTR_SIZE) {
struct dentry *lower_dentry = ecryptfs_dentry_to_lower(dentry);
inode_lock(d_inode(lower_dentry));
rc = notify_change(lower_dentry, &lower_ia, NULL);
inode_unlock(d_inode(lower_dentry));
}
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 iattr lower_ia;
struct inode *inode;
struct inode *lower_inode;
struct ecryptfs_crypt_stat *crypt_stat;
crypt_stat = &ecryptfs_inode_to_private(d_inode(dentry))->crypt_stat;
if (!(crypt_stat->flags & ECRYPTFS_STRUCT_INITIALIZED)) {
rc = ecryptfs_init_crypt_stat(crypt_stat);
if (rc)
return rc;
}
inode = d_inode(dentry);
lower_inode = ecryptfs_inode_to_lower(inode);
lower_dentry = ecryptfs_dentry_to_lower(dentry);
mutex_lock(&crypt_stat->cs_mutex);
if (d_is_dir(dentry))
crypt_stat->flags &= ~(ECRYPTFS_ENCRYPTED);
else if (d_is_reg(dentry)
&& (!(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_get_lower_file(dentry, inode);
if (rc) {
mutex_unlock(&crypt_stat->cs_mutex);
goto out;
}
rc = ecryptfs_read_metadata(dentry);
ecryptfs_put_lower_file(inode);
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_I_SIZE_INITIALIZED
| ECRYPTFS_ENCRYPTED);
}
}
mutex_unlock(&crypt_stat->cs_mutex);
rc = setattr_prepare(dentry, ia);
if (rc)
goto out;
if (ia->ia_valid & ATTR_SIZE) {
rc = ecryptfs_inode_newsize_ok(inode, ia->ia_size);
if (rc)
goto out;
}
memcpy(&lower_ia, ia, sizeof(lower_ia));
if (ia->ia_valid & ATTR_FILE)
lower_ia.ia_file = ecryptfs_file_to_lower(ia->ia_file);
if (ia->ia_valid & ATTR_SIZE) {
rc = truncate_upper(dentry, ia, &lower_ia);
if (rc < 0)
goto out;
}
/*
* mode change is for clearing setuid/setgid bits. Allow lower fs
* to interpret this in its own way.
*/
if (lower_ia.ia_valid & (ATTR_KILL_SUID | ATTR_KILL_SGID))
lower_ia.ia_valid &= ~ATTR_MODE;
inode_lock(d_inode(lower_dentry));
rc = notify_change(lower_dentry, &lower_ia, NULL);
inode_unlock(d_inode(lower_dentry));
out:
fsstack_copy_attr_all(inode, lower_inode);
return rc;
}
static int ecryptfs_getattr_link(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
int rc = 0;
mount_crypt_stat = &ecryptfs_superblock_to_private(
dentry->d_sb)->mount_crypt_stat;
generic_fillattr(d_inode(dentry), stat);
if (mount_crypt_stat->flags & ECRYPTFS_GLOBAL_ENCRYPT_FILENAMES) {
char *target;
size_t targetsiz;
target = ecryptfs_readlink_lower(dentry, &targetsiz);
if (!IS_ERR(target)) {
kfree(target);
stat->size = targetsiz;
} else {
rc = PTR_ERR(target);
}
}
return rc;
}
static int ecryptfs_getattr(const struct path *path, struct kstat *stat,
u32 request_mask, unsigned int flags)
{
struct dentry *dentry = path->dentry;
struct kstat lower_stat;
int rc;