// SPDX-License-Identifier: GPL-2.0-only
/*
* Copyright (C) 2004 IBM Corporation
* Authors:
* Leendert van Doorn <[email protected]>
* Dave Safford <[email protected]>
* Reiner Sailer <[email protected]>
* Kylene Hall <[email protected]>
*
* Copyright (C) 2013 Obsidian Research Corp
* Jason Gunthorpe <[email protected]>
*
* Device file system interface to the TPM
*/
#include <linux/poll.h>
#include <linux/slab.h>
#include <linux/uaccess.h>
#include <linux/workqueue.h>
#include "tpm.h"
#include "tpm-dev.h"
static struct workqueue_struct *tpm_dev_wq;
static ssize_t tpm_dev_transmit(struct tpm_chip *chip, struct tpm_space *space,
u8 *buf, size_t bufsiz)
{
struct tpm_header *header = (void *)buf;
ssize_t ret, len;
ret = tpm2_prepare_space(chip, space, buf, bufsiz);
/* If the command is not implemented by the TPM, synthesize a
* response with a TPM2_RC_COMMAND_CODE return for user-space.
*/
if (ret == -EOPNOTSUPP) {
header->length = cpu_to_be32(sizeof(*header));
header->tag = cpu_to_be16(TPM2_ST_NO_SESSIONS);
header->return_code = cpu_to_be32(TPM2_RC_COMMAND_CODE |
TSS2_RESMGR_TPM_RC_LAYER);
ret = sizeof(*header);
}
if (ret)
goto out_rc;
len = tpm_transmit(chip, buf, bufsiz);
if (len < 0)
ret = len;
if (!ret)
ret = tpm2_commit_space(chip, space, buf, &len);
else
tpm2_flush_space(chip);
out_rc:
return ret ? ret : len;
}
static void tpm_dev_async_work(struct work_struct *work)
{
struct file_priv *priv =
container_of(work, struct file_priv, async_work);
ssize_t ret;
mutex_lock(&priv->buffer_mutex);
priv->command_enqueued = false;
ret = tpm_try_get_ops(priv->chip);
if (ret) {
priv->response_length = ret;
goto out;
}
ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
sizeof(priv->data_buffer));
tpm_put_ops(priv->chip);
/*
* If ret is > 0 then tpm_dev_transmit returned the size of the
* response. If ret is < 0 then tpm_dev_transmit failed and
* returned an error code.
*/
if (ret != 0) {
priv->response_length = ret;
mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
}
out:
mutex_unlock(&priv->buffer_mutex);
wake_up_interruptible(&priv->async_wait);
}
static void user_reader_timeout(struct timer_list *t)
{
struct file_priv *priv = from_timer(priv, t, user_read_timer);
pr_warn("TPM user space timeout is deprecated (pid=%d)\n",
task_tgid_nr(current));
schedule_work(&priv->timeout_work);
}
static void tpm_timeout_work(struct work_struct *work)
{
struct file_priv *priv = container_of(work, struct file_priv,
timeout_work);
mutex_lock(&priv->buffer_mutex);
priv->response_read = true;
priv->response_length = 0;
memset(priv->data_buffer, 0, sizeof(priv->data_buffer));
mutex_unlock(&priv->buffer_mutex);
wake_up_interruptible(&priv->async_wait);
}
void tpm_common_open(struct file *file, struct tpm_chip *chip,
struct file_priv *priv, struct tpm_space *space)
{
priv->chip = chip;
priv->space = space;
priv->response_read = true;
mutex_init(&priv->buffer_mutex);
timer_setup(&priv->user_read_timer, user_reader_timeout, 0);
INIT_WORK(&priv->timeout_work, tpm_timeout_work);
INIT_WORK(&priv->async_work, tpm_dev_async_work);
init_waitqueue_head(&priv->async_wait);
file->private_data = priv;
}
ssize_t tpm_common_read(struct file *file, char __user *buf,
size_t size, loff_t *off)
{
struct file_priv *priv = file->private_data;
ssize_t ret_size = 0;
int rc;
mutex_lock(&priv->buffer_mutex);
if (priv->response_length) {
priv->response_read = true;
ret_size = min_t(ssize_t, size, priv->response_length);
if (ret_size <= 0) {
priv->response_length = 0;
goto out;
}
rc = copy_to_user(buf, priv->data_buffer + *off, ret_size);
if (rc) {
memset(priv->data_buffer, 0, TPM_BUFSIZE);
priv->response_length = 0;
ret_size = -EFAULT;
} else {
memset(priv->data_buffer + *off, 0, ret_size);
priv->response_length -= ret_size;
*off += ret_size;
}
}
out:
if (!priv->response_length) {
*off = 0;
del_timer_sync(&priv->user_read_timer);
flush_work(&priv->timeout_work);
}
mutex_unlock(&priv->buffer_mutex);
return ret_size;
}
ssize_t tpm_common_write(struct file *file, const char __user *buf,
size_t size, loff_t *off)
{
struct file_priv *priv = file->private_data;
int ret = 0;
if (size > TPM_BUFSIZE)
return -E2BIG;
mutex_lock(&priv->buffer_mutex);
/* Cannot perform a write until the read has cleared either via
* tpm_read or a user_read_timer timeout. This also prevents split
* buffered writes from blocking here.
*/
if ((!priv->response_read && priv->response_length) ||
priv->command_enqueued) {
ret = -EBUSY;
goto out;
}
if (copy_from_user(priv->data_buffer, buf, size)) {
ret = -EFAULT;
goto out;
}
if (size < 6 ||
size < be32_to_cpu(*((__be32 *)(priv->data_buffer + 2)))) {
ret = -EINVAL;
goto out;
}
priv->response_length = 0;
priv->response_read = false;
*off = 0;
/*
* If in nonblocking mode schedule an async job to send
* the command return the size.
* In case of error the err code will be returned in
* the subsequent read call.
*/
if (file->f_flags & O_NONBLOCK) {
priv->command_enqueued = true;
queue_work(tpm_dev_wq, &priv->async_work);
mutex_unlock(&priv->buffer_mutex);
return size;
}
/* atomic tpm command send and result receive. We only hold the ops
* lock during this period so that the tpm can be unregistered even if
* the char dev is held open.
*/
if (tpm_try_get_ops(priv->chip)) {
ret = -EPIPE;
goto out;
}
ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
sizeof(priv->data_buffer));
tpm_put_ops(priv->chip);
if (ret > 0) {
priv->response_length = ret;
mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
ret = size;
}
out:
mutex_unlock(&priv->buffer_mutex);
return ret;
}
__poll_t tpm_common_poll(struct file *file, poll_table *wait)
{
struct file_priv *priv = file->private_data;
__poll_t mask = 0;
poll_wait(file, &priv->async_wait, wait);
mutex_lock(&priv->buffer_mutex);
/*
* The response_length indicates if there is still response
* (or part of it) to be consumed. Partial reads decrease it
* by the number of bytes read, and write resets it the zero.
*/
if (priv->response_length)
mask = EPOLLIN | EPOLLRDNORM;
else
mask = EPOLLOUT | EPOLLWRNORM;
mutex_unlock(&priv->buffer_mutex);
return mask;
}
/*
* Called on file close
*/
void tpm_common_release(struct file *file, struct file_priv *priv)
{
flush_work(&priv->async_work);
del_timer_sync(&priv->user_read_timer);
flush_work(&priv->timeout_work);
file->private_data = NULL;
priv->response_length = 0;
}
int __init tpm_dev_common_init(void)
{
tpm_dev_wq = alloc_workqueue("tpm_dev_wq", WQ_MEM_RECLAIM, 0);
return !tpm_dev_wq ? -ENOMEM : 0;
}
void __exit tpm_dev_common_exit(void)
{
if (tpm_dev_wq) {
destroy_workqueue(tpm_dev_wq);
tpm_dev_wq = NULL;
}
}
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