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Date: Tue, 22 Mar 2016 08:34:59 +0200
From: Jarkko Sakkinen <jarkko.sakkinen@...ux.intel.com>
To: Stefan Berger <stefanb@...ux.vnet.ibm.com>
Cc: tpmdd-devel@...ts.sourceforge.net, linux-doc@...r.kernel.org,
linux-api@...r.kernel.org, linux-kernel@...r.kernel.org,
linux-security-module@...r.kernel.org
Subject: Re: [v8,09/10] tpm: Initialize TPM and get durations and timeouts
On Sun, Mar 13, 2016 at 06:54:39PM -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@...ux.vnet.ibm.com>
> CC: linux-kernel@...r.kernel.org
> CC: linux-doc@...r.kernel.org
> CC: linux-api@...r.kernel.org
>
> ---
> drivers/char/tpm/tpm_vtpm_proxy.c | 95 +++++++++++++++++++++++++++++++++++----
> 1 file changed, 86 insertions(+), 9 deletions(-)
>
> diff --git a/drivers/char/tpm/tpm_vtpm_proxy.c b/drivers/char/tpm/tpm_vtpm_proxy.c
> index 2bb2c8c..7fd686b 100644
> --- a/drivers/char/tpm/tpm_vtpm_proxy.c
> +++ b/drivers/char/tpm/tpm_vtpm_proxy.c
> @@ -45,8 +45,11 @@ 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 */
> };
>
> +static struct workqueue_struct *workqueue;
>
> static void vtpm_proxy_delete_device(struct proxy_dev *proxy_dev);
>
> @@ -67,6 +70,15 @@ static ssize_t vtpm_proxy_fops_read(struct file *filp, char __user *buf,
> size_t len;
> int sig, rc;
>
> + mutex_lock(&proxy_dev->buf_lock);
> +
> + if (!(proxy_dev->state & STATE_OPENED_FLAG)) {
> + mutex_unlock(&proxy_dev->buf_lock);
> + return -EPIPE;
> + }
> +
> + mutex_unlock(&proxy_dev->buf_lock);
> +
> sig = wait_event_interruptible(proxy_dev->wq, proxy_dev->req_len != 0);
> if (sig)
> return -EINTR;
What if STATE_OPENED_FLAG is set after mutex_unlock()?
Is there some scenario where STATE_OPENED_FLAG would evaluate false
at this point?
Actually I couldn't find a scenario where this check would be needed
because:
* In vtpm_proxy_work() vtpm_proxy_fops_undo_open() is called after
sending TPM commands.
* vtpm_proxy_delete_device() calls vtpm_proxy_work_stop() as its
first statement.
Am I ignoring something?
/Jarkko
> @@ -110,6 +122,11 @@ 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);
> @@ -154,6 +171,9 @@ 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;
> @@ -341,6 +361,55 @@ 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);
> +}
> +
> +/*
> + * 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)
> @@ -355,6 +424,7 @@ 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)) {
> @@ -425,9 +495,7 @@ 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);
> @@ -436,12 +504,6 @@ 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);
>
> @@ -456,6 +518,8 @@ 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
> @@ -555,11 +619,24 @@ 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();
> }
>
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