1 files changed, 285 insertions, 0 deletions
diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
new file mode 100644
index 000000000..b99e1941c
--- /dev/null
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -0,0 +1,285 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright (C) 2004 IBM Corporation
+ * Authors:
+ * Leendert van Doorn <leendert@watson.ibm.com>
+ * Dave Safford <safford@watson.ibm.com>
+ * Reiner Sailer <sailer@watson.ibm.com>
+ * Kylene Hall <kjhall@us.ibm.com>
+ *
+ * Copyright (C) 2013 Obsidian Research Corp
+ * Jason Gunthorpe <jgunthorpe@obsidianresearch.com>
+ *
+ * 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 DEFINE_MUTEX(tpm_dev_wq_lock);
+
+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);
+
+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_singleshot_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_singleshot_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;
+	}
+}