Re: [v9,3/4] tpm: Initialize TPM and get durations and timeouts

From: Jarkko Sakkinen
Date: Thu Mar 31 2016 - 04:25:50 EST

On Tue, Mar 29, 2016 at 02:19:13PM -0400, Stefan Berger wrote:
> Add the retrieval of TPM 1.2 durations and timeouts. Since this requires
> the startup of the TPM, do this for TPM 1.2 and TPM 2.
>
> Signed-off-by: Stefan Berger <stefanb@xxxxxxxxxxxxxxxxxx>
> CC: linux-kernel@xxxxxxxxxxxxxxx
> CC: linux-doc@xxxxxxxxxxxxxxx
> CC: linux-api@xxxxxxxxxxxxxxx
>
> ---
> drivers/char/tpm/tpm_vtpm_proxy.c | 96 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 86 insertions(+), 10 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
> index 81abc4b..8936bf3 100644
> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
> @@ -45,11 +45,15 @@ struct proxy_dev {
> size_t req_len; /* length of queued TPM request */
> size_t resp_len; /* length of queued TPM response */
> u8 buffer[TPM_BUFSIZE]; /* request/response buffer */
> +
> + struct work_struct work; /* task that retrieves TPM timeouts */
> };
>
> /* all supported flags */
> #define VTPM_PROXY_FLAGS_ALL (VTPM_PROXY_FLAG_TPM2)
>
> +static struct workqueue_struct *workqueue;
> +
> static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev);
>
> /*
> @@ -69,12 +73,19 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
> size_t len;
> int sig, rc;
>
> - sig = wait_event_interruptible(proxy_dev->wq, proxy_dev->req_len != 0);
> + sig = wait_event_interruptible(proxy_dev->wq,
> + proxy_dev->req_len != 0 ||
> + !(proxy_dev->state & STATE_OPENED_FLAG));
> if (sig)
> return -EINTR;
>
> mutex_lock(&proxy_dev->buf_lock);
>
> + if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
> + mutex_unlock(&proxy_dev->buf_lock);
> + return -EPIPE;
> + }
> +
> len = proxy_dev->req_len;
>
> if (count < len) {
> @@ -112,6 +123,11 @@ static ssize_t vtpm_proxy_fops_write(struct file *filp, const char __user *buf,
>
> mutex_lock(&proxy_dev->buf_lock);
>
> + if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
> + mutex_unlock(&proxy_dev->buf_lock);
> + return -EPIPE;
> + }
> +
> if (count > sizeof(proxy_dev->buffer) ||
> !(proxy_dev->state & STATE_WAIT_RESPONSE_FLAG)) {
> mutex_unlock(&proxy_dev->buf_lock);
> @@ -156,6 +172,9 @@ static unsigned int vtpm_proxy_fops_poll(struct file *filp, poll_table *wait)
> if (proxy_dev->req_len)
> ret |= POLLIN | POLLRDNORM;
>
> + if (!(proxy_dev->state & STATE_OPENED_FLAG))
> + ret |= POLLHUP;
> +
> mutex_unlock(&proxy_dev->buf_lock);
>
> return ret;
> @@ -343,6 +362,55 @@ static const struct tpm_class_ops vtpm_proxy_tpm_ops = {
> };
>
> /*
> + * Code related to the startup of the TPM 2 and startup of TPM 1.2 +
> + * retrieval of timeouts and durations.
> + */
> +
> +static void vtpm_proxy_work(struct work_struct *work)
> +{
> + struct proxy_dev *proxy_dev = container_of(work, struct proxy_dev,
> + work);
> + int rc;
> +
> + if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
> + rc = tpm2_startup(proxy_dev->chip, TPM2_SU_CLEAR);
> + else
> + rc = tpm_get_timeouts(proxy_dev->chip);
> +
> + if (rc)
> + goto err;
> +
> + rc = tpm_chip_register(proxy_dev->chip);
> + if (rc)
> + goto err;
> +
> + return;
> +
> +err:
> + vtpm_proxy_fops_undo_open(proxy_dev);
> +}
> +
> +/*
> + * vtpm_proxy_work_stop: make sure the work has finished
> + *
> + * This function is useful when user space closed the fd
> + * while the driver still determines timeouts.
> + */
> +static void vtpm_proxy_work_stop(struct proxy_dev *proxy_dev)
> +{
> + vtpm_proxy_fops_undo_open(proxy_dev);
> + flush_work(&proxy_dev->work);

The main proxy driver patch should implement cancel() callback and then
these could be swapped. This whole use of OPENED callback looks like a
hack that is done because cancel is not implemented.

A new flag CANCELED could be added and functions would return -ECANCEL
if it is set. This should be part of original vTPM proxy driver
functionally.

The current solution is unclean and hard to follow. It looks like "it
could work" but the OPENED flag has too many hats that it wears IMHO.

/Jarkko

> +}
> +
> +/*
> + * vtpm_proxy_work_start: Schedule the work for TPM 1.2 & 2 initialization
> + */
> +static inline void vtpm_proxy_work_start(struct proxy_dev *proxy_dev)
> +{
> + queue_work(workqueue, &proxy_dev->work);
> +}
> +
> +/*
> * Code related to creation and deletion of device pairs
> */
> static struct proxy_dev *vtpm_proxy_create_proxy_dev(void)
> @@ -357,6 +425,7 @@ static struct proxy_dev *vtpm_proxy_create_proxy_dev(void)
>
> init_waitqueue_head(&proxy_dev->wq);
> mutex_init(&proxy_dev->buf_lock);
> + INIT_WORK(&proxy_dev->work, vtpm_proxy_work);
>
> chip = tpm_chip_alloc(NULL, &vtpm_proxy_tpm_ops);
> if (IS_ERR(chip)) {
> @@ -427,9 +496,7 @@ static struct file *vtpm_proxy_create_device(
> if (proxy_dev->flags & VTPM_PROXY_FLAG_TPM2)
> proxy_dev->chip->flags |= TPM_CHIP_FLAG_TPM2;
>
> - rc = tpm_chip_register(proxy_dev->chip);
> - if (rc)
> - goto err_vtpm_fput;
> + vtpm_proxy_work_start(proxy_dev);
>
> vtpm_new_dev->fd = fd;
> vtpm_new_dev->major = MAJOR(proxy_dev->chip->dev.devt);
> @@ -438,12 +505,6 @@ static struct file *vtpm_proxy_create_device(
>
> return file;
>
> -err_vtpm_fput:
> - put_unused_fd(fd);
> - fput(file);
> -
> - return ERR_PTR(rc);
> -
> err_put_unused_fd:
> put_unused_fd(fd);
>
> @@ -458,6 +519,8 @@ err_delete_proxy_dev:
> */
> static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev)
> {
> + vtpm_proxy_work_stop(proxy_dev);
> +
> /*
> * A client may hold the 'ops' lock, so let it know that the server
> * side shuts down before we try to grab the 'ops' lock when
> @@ -557,11 +620,24 @@ static int __init vtpm_module_init(void)
> return rc;
> }
>
> + workqueue = create_workqueue("tpm-vtpm");
> + if (!workqueue) {
> + pr_err("couldn't create workqueue\n");
> + rc = -ENOMEM;
> + goto err_vtpmx_cleanup;
> + }
> +
> return 0;
> +
> +err_vtpmx_cleanup:
> + vtpmx_cleanup();
> +
> + return rc;
> }
>
> static void __exit vtpm_module_exit(void)
> {
> + destroy_workqueue(workqueue);
> vtpmx_cleanup();
> }
>