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