// 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. Thompson <[email protected]>
*/
#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,
struct iov_iter *to)
{
ssize_t rc;
const struct path *path;
struct file *file = iocb->ki_filp;
rc = generic_file_read_iter(iocb, to);
if (rc >= 0) {
path = ecryptfs_dentry_to_lower_path(file->f_path.dentry);
touch_atime(path);
}
return rc;
}
/*
* ecryptfs_splice_read_update_atime
*
* filemap_splice_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_splice_read_update_atime(struct file *in, loff_t *ppos,
struct pipe_inode_info *pipe,
size_t len, unsigned int flags)
{
ssize_t rc;
const struct path *path;
rc = filemap_splice_read(in, ppos, pipe, len, flags);
if (rc >= 0) {
path = ecryptfs_dentry_to_lower_path(in->f_path.dentry);
touch_atime(path);
}
return rc;
}
struct ecryptfs_getdents_callback {
struct dir_context ctx;
struct dir_context *caller;
struct super_block *sb;
int filldir_called;
int entries_written;
};
/* Inspired by generic filldir in fs/readdir.c */
static bool
ecryptfs_filldir(struct dir_context *ctx, const char *lower_name,
int lower_namelen, loff_t offset, u64 ino, unsigned int d_type)
{
struct ecryptfs_getdents_callback *buf =
container_of(ctx, struct ecryptfs_getdents_callback, ctx);
size_t name_size;
char *name;
int err;
bool res;
buf->filldir_called++;
err = ecryptfs_decode_and_decrypt_filename(&name, &name_size,
buf->sb, lower_name,
lower_namelen);
if (err) {
if (err != -EINVAL) {
ecryptfs_printk(KERN_DEBUG,
"%s: Error attempting to decode and decrypt filename [%s]; rc = [%d]\n",
__func__, lower_name, err);
return false;
}
/* Mask -EINVAL errors as these are most likely due a plaintext
* filename present in the lower filesystem despite filename
* encryption being enabled. One unavoidable example would be
* the "lost+found" dentry in the root directory of an Ext4
* filesystem.
*/
return true;
}
buf->caller->pos = buf->ctx.pos;
res = dir_emit(buf->caller, name, name_size, ino, d_type);
kfree(name);
if (res)
buf->entries_written++;
return res;
}
/**
* ecryptfs_readdir
* @file: The eCryptfs directory file
* @ctx: The actor to feed the entries to
*/
static int ecryptfs_readdir(struct file *file, struct dir_context *ctx)
{
int rc;
struct file *lower_file;
struct inode *inode = file_inode(file);
struct ecryptfs_getdents_callback buf = {
.ctx.actor = ecryptfs_filldir,
.caller = ctx,
.sb = inode->i_sb,
};
lower_file = ecryptfs_file_to_lower(file);
rc = iterate_dir(lower_file, &buf.ctx);
ctx->pos = buf.ctx.pos;
if (rc >= 0 && (buf.entries_written || !buf.filldir_called))
fsstack_copy_attr_atime(inode, file_inode(lower_file));
return rc;
}
struct kmem_cache *ecryptfs_file_info_cache;
static int read_or_initialize_metadata(struct dentry *dentry)
{
struct inode *inode = d_inode(dentry);
struct ecryptfs_mount_crypt_stat *mount_crypt_stat;
struct ecryptfs_crypt_stat *crypt_stat;
int rc;
crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
mount_crypt_stat = &ecryptfs_superblock_to_private(
inode->i_sb)->mount_crypt_stat;
mutex_lock(&crypt_stat->cs_mutex);
if (crypt_stat->flags & ECRYPTFS_POLICY_APPLIED &&
crypt_stat->flags & ECRYPTFS_KEY_VALID) {
rc = 0;
goto out;
}
rc = ecryptfs_read_metadata(dentry);
if (!rc)
goto out;
if (mount_crypt_stat->flags & ECRYPTFS_PLAINTEXT_PASSTHROUGH_ENABLED) {
crypt_stat->flags &= ~(ECRYPTFS_I_SIZE_INITIALIZED
| ECRYPTFS_ENCRYPTED);
rc = 0;
goto out;
}
if (!(mount_crypt_stat->flags & ECRYPTFS_XATTR_METADATA_ENABLED) &&
!i_size_read(ecryptfs_inode_to_lower(inode))) {
rc = ecryptfs_initialize_file(dentry, inode);
if (!rc)
goto out;
}
rc = -EIO;
out:
mutex_unlock(&crypt_stat->cs_mutex);
return rc;
}
static int ecryptfs_mmap(struct file *file, struct vm_area_struct *vma)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
/*
* Don't allow mmap on top of file systems that don't support it
* natively. If FILESYSTEM_MAX_STACK_DEPTH > 2 or ecryptfs
* allows recursive mounting, this will need to be extended.
*/
if (!lower_file->f_op->mmap)
return -ENODEV;
return generic_file_mmap(file, vma);
}
/**
* ecryptfs_open
* @inode: inode specifying 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 dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct ecryptfs_file_info *file_info;
/* 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;
}
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 "
"[%pd]; rc = [%d]\n", __func__,
ecryptfs_dentry, 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);
rc = read_or_initialize_metadata(ecryptfs_dentry);
if (rc)
goto out_put;
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;
}
/**
* ecryptfs_dir_open
* @inode: inode specifying 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_dir_open(struct inode *inode, struct file *file)
{
struct dentry *ecryptfs_dentry = file->f_path.dentry;
/* Private value of ecryptfs_dentry allocated in
* ecryptfs_lookup() */
struct ecryptfs_file_info *file_info;
struct file *lower_file;
/* 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 (unlikely(!file_info)) {
ecryptfs_printk(KERN_ERR,
"Error attempting to allocate memory\n");
return -ENOMEM;
}
lower_file = dentry_open(ecryptfs_dentry_to_lower_path(ecryptfs_dentry),
file->f_flags, current_cred());
if (IS_ERR(lower_file)) {
printk(KERN_ERR "%s: Error attempting to initialize "
"the lower file for the dentry with name "
"[%pd]; rc = [%ld]\n", __func__,
ecryptfs_dentry, PTR_ERR(lower_file));
kmem_cache_free(ecryptfs_file_info_cache, file_info);
return PTR_ERR(lower_file);
}
ecryptfs_set_file_lower(file, lower_file);
return 0;
}
static int ecryptfs_flush(struct file *file, fl_owner_t td)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
if (lower_file->f_op->flush) {
filemap_write_and_wait(file->f_mapping);
return lower_file->f_op->flush(lower_file, td);
}
return 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_dir_release(struct inode *inode, struct file *file)
{
fput(ecryptfs_file_to_lower(file));
kmem_cache_free(ecryptfs_file_info_cache,
ecryptfs_file_to_private(file));
return 0;
}
static loff_t ecryptfs_dir_llseek(struct file *file, loff_t offset, int whence)
{
return vfs_llseek(ecryptfs_file_to_lower(file), offset, whence);
}
static int
ecryptfs_fsync(struct file *file, loff_t start, loff_t end, int datasync)
{
int rc;
rc = file_write_and_wait(file);
if (rc)
return rc;
return vfs_fsync(ecryptfs_file_to_lower(file), datasync);
}
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->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 = ecryptfs_file_to_lower(file);
long rc = -ENOTTY;
if (!lower_file->f_op->unlocked_ioctl)
return rc;
switch (cmd) {
case FITRIM:
case FS_IOC_GETFLAGS:
case FS_IOC_SETFLAGS:
case FS_IOC_GETVERSION:
case FS_IOC_SETVERSION:
rc = lower_file->f_op->unlocked_ioctl(lower_file, cmd, arg);
fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
return rc;
default:
return rc;
}
}
#ifdef CONFIG_COMPAT
static long
ecryptfs_compat_ioctl(struct file *file, unsigned int cmd, unsigned long arg)
{
struct file *lower_file = ecryptfs_file_to_lower(file);
long rc = -ENOIOCTLCMD;
if (!lower_file->f_op->compat_ioctl)
return rc;
switch (cmd) {
case FITRIM:
case FS_IOC32_GETFLAGS:
case FS_IOC32_SETFLAGS:
case FS_IOC32_GETVERSION:
case FS_IOC32_SETVERSION:
rc = lower_file->f_op->compat_ioctl(lower_file, cmd, arg);
fsstack_copy_attr_all(file_inode(file), file_inode(lower_file));
return rc;
default:
return rc;
}
}
#endif
const struct file_operations ecryptfs_dir_fops = {
.iterate_shared = ecryptfs_readdir,
.read = generic_read_dir,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.open = ecryptfs_dir_open,
.release = ecryptfs_dir_release,
.fsync = ecryptfs_fsync,
.llseek = ecryptfs_dir_llseek,
};
const struct file_operations ecryptfs_main_fops = {
.llseek = generic_file_llseek,
.read_iter = ecryptfs_read_update_atime,
.write_iter = generic_file_write_iter,
.unlocked_ioctl = ecryptfs_unlocked_ioctl,
#ifdef CONFIG_COMPAT
.compat_ioctl = ecryptfs_compat_ioctl,
#endif
.mmap = ecryptfs_mmap,
.open = ecryptfs_open,
.flush = ecryptfs_flush,
.release = ecryptfs_release,
.fsync = ecryptfs_fsync,
.fasync = ecryptfs_fasync,
.splice_read = ecryptfs_splice_read_update_atime,
};
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