diff mbox series

[v3,1/2] tpm: Fix error handling in async work

Message ID 20220111055228.1830-1-tstruk@gmail.com (mailing list archive)
State New
Headers show
Series [v3,1/2] tpm: Fix error handling in async work | expand

Commit Message

Tadeusz Struk Jan. 11, 2022, 5:52 a.m. UTC
When an invalid (non existing) handle is used in a TPM command,
that uses the resource manager interface (/dev/tpmrm0) the resource
manager tries to load it from its internal cache, but fails and
the tpm_dev_transmit returns an -EINVAL error to the caller.
The existing async handler doesn't handle these error cases
currently and the condition in the poll handler never returns
mask with EPOLLIN set.
The result is that the poll call blocks and the application gets stuck
until the user_read_timer wakes it up after 120 sec.
Change the tpm_dev_async_work function to handle error conditions
returned from tpm_dev_transmit they are also reflected in the poll mask
and a correct error code could passed back to the caller.

Cc: Jarkko Sakkinen <jarkko@kernel.org>
Cc: Jason Gunthorpe <jgg@ziepe.ca>
Cc: <linux-integrity@vger.kernel.org>
Cc: <stable@vger.kernel.org>
Cc: <linux-kernel@vger.kernel.org>
Fixes: 9e1b74a63f77 ("tpm: add support for nonblocking operation")
Signed-off-by: Tadeusz Struk <tstruk@gmail.com>
---
Changed in v2:
- Updated commit message with better problem description
- Fixed typeos.
Changed in v3:
- Added a comment to tpm_dev_async_work.
- Updated commit message.
---
 drivers/char/tpm/tpm-dev-common.c | 8 +++++++-
 1 file changed, 7 insertions(+), 1 deletion(-)

Comments

Jarkko Sakkinen Jan. 12, 2022, 6:35 p.m. UTC | #1
On Mon, Jan 10, 2022 at 09:52:27PM -0800, Tadeusz Struk wrote:
> When an invalid (non existing) handle is used in a TPM command,
> that uses the resource manager interface (/dev/tpmrm0) the resource
> manager tries to load it from its internal cache, but fails and
> the tpm_dev_transmit returns an -EINVAL error to the caller.
> The existing async handler doesn't handle these error cases
> currently and the condition in the poll handler never returns
> mask with EPOLLIN set.
> The result is that the poll call blocks and the application gets stuck
> until the user_read_timer wakes it up after 120 sec.
> Change the tpm_dev_async_work function to handle error conditions
> returned from tpm_dev_transmit they are also reflected in the poll mask
> and a correct error code could passed back to the caller.
> 
> Cc: Jarkko Sakkinen <jarkko@kernel.org>
> Cc: Jason Gunthorpe <jgg@ziepe.ca>
> Cc: <linux-integrity@vger.kernel.org>
> Cc: <stable@vger.kernel.org>
> Cc: <linux-kernel@vger.kernel.org>
> Fixes: 9e1b74a63f77 ("tpm: add support for nonblocking operation")
> Signed-off-by: Tadeusz Struk <tstruk@gmail.com>
> ---
> Changed in v2:
> - Updated commit message with better problem description
> - Fixed typeos.
> Changed in v3:
> - Added a comment to tpm_dev_async_work.
> - Updated commit message.
> ---
>  drivers/char/tpm/tpm-dev-common.c | 8 +++++++-
>  1 file changed, 7 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
> index c08cbb306636..50df8f09ff79 100644
> --- a/drivers/char/tpm/tpm-dev-common.c
> +++ b/drivers/char/tpm/tpm-dev-common.c
> @@ -69,7 +69,13 @@ static void tpm_dev_async_work(struct work_struct *work)
>  	ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
>  			       sizeof(priv->data_buffer));
>  	tpm_put_ops(priv->chip);
> -	if (ret > 0) {
> +
> +	/*
> +	 * 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 a return code.
> +	 */
> +	if (ret != 0) {
>  		priv->response_length = ret;
>  		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
>  	}
> -- 
> 2.30.2
> 

These look good to me! Thank you. I'm in process of compiling a test
kernel.

/Jarkko
Tadeusz Struk Jan. 12, 2022, 6:47 p.m. UTC | #2
On 1/12/22 10:35, Jarkko Sakkinen wrote:
> These look good to me! Thank you. I'm in process of compiling a test
> kernel.

Thanks Jarkko,
You can run the new test before and after applying the change and see
how it behaves. Also just noticed a mistake in the comment, sorry but
it was quite late when I sent it.

+	/*
+	 * 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 a return code.
+	 */

In the above could you please replace:

s/returned a return code/returned an error code/

before applying the patch. I would appreciate that.
Jarkko Sakkinen Jan. 14, 2022, 9:07 p.m. UTC | #3
On Wed, Jan 12, 2022 at 10:47:29AM -0800, Tadeusz Struk wrote:
> On 1/12/22 10:35, Jarkko Sakkinen wrote:
> > These look good to me! Thank you. I'm in process of compiling a test
> > kernel.
> 
> Thanks Jarkko,
> You can run the new test before and after applying the change and see
> how it behaves. Also just noticed a mistake in the comment, sorry but
> it was quite late when I sent it.
> 
> +	/*
> +	 * 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 a return code.
> +	 */
> 
> In the above could you please replace:
> 
> s/returned a return code/returned an error code/
> 
> before applying the patch. I would appreciate that.

Please send new versions, there's also this:

def test_flush_invlid_context()

I'd figure "invlid" should be  "invalid"

You can add, as these changes do not change the semantics of the
patches:

Tested-by: Jarkko Sakkinen <jarkko@kernel.org>

It's always best if you author the final version, as then a clear
reference on what was accepted exist at lore.kernel.org.

BR, Jarkko
Jarkko Sakkinen Jan. 14, 2022, 9:12 p.m. UTC | #4
On Fri, Jan 14, 2022 at 11:07:22PM +0200, Jarkko Sakkinen wrote:
> On Wed, Jan 12, 2022 at 10:47:29AM -0800, Tadeusz Struk wrote:
> > On 1/12/22 10:35, Jarkko Sakkinen wrote:
> > > These look good to me! Thank you. I'm in process of compiling a test
> > > kernel.
> > 
> > Thanks Jarkko,
> > You can run the new test before and after applying the change and see
> > how it behaves. Also just noticed a mistake in the comment, sorry but
> > it was quite late when I sent it.
> > 
> > +	/*
> > +	 * 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 a return code.
> > +	 */
> > 
> > In the above could you please replace:
> > 
> > s/returned a return code/returned an error code/
> > 
> > before applying the patch. I would appreciate that.
> 
> Please send new versions, there's also this:
> 
> def test_flush_invlid_context()
> 
> I'd figure "invlid" should be  "invalid"
> 
> You can add, as these changes do not change the semantics of the
> patches:
> 
> Tested-by: Jarkko Sakkinen <jarkko@kernel.org>
> 
> It's always best if you author the final version, as then a clear
> reference on what was accepted exist at lore.kernel.org.

Maybe it is good to mention that the test environment was libvirt hosted
QEMU using swtpm, which I tried for the first time, instead of real hadware
(libvirt has a nice property that it handles the startup/shutdown of
swtpm). I managed to run all tests so I guess swtpm is working properly.

/Jarkko
Tadeusz Struk Jan. 16, 2022, 1:22 a.m. UTC | #5
On 1/14/22 13:12, Jarkko Sakkinen wrote:
>> Please send new versions, there's also this:
>>
>> def test_flush_invlid_context()
>>
>> I'd figure "invlid" should be  "invalid"
>>
>> You can add, as these changes do not change the semantics of the
>> patches:
>>
>> Tested-by: Jarkko Sakkinen<jarkko@kernel.org>
>>
>> It's always best if you author the final version, as then a clear
>> reference on what was accepted exist at lore.kernel.org.
> Maybe it is good to mention that the test environment was libvirt hosted
> QEMU using swtpm, which I tried for the first time, instead of real hadware
> (libvirt has a nice property that it handles the startup/shutdown of
> swtpm). I managed to run all tests so I guess swtpm is working properly.

Yes, I have been using it all the time for testing since the support was
added to qemu. New versions on their way.

Thanks,
Tadeusz
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm-dev-common.c b/drivers/char/tpm/tpm-dev-common.c
index c08cbb306636..50df8f09ff79 100644
--- a/drivers/char/tpm/tpm-dev-common.c
+++ b/drivers/char/tpm/tpm-dev-common.c
@@ -69,7 +69,13 @@  static void tpm_dev_async_work(struct work_struct *work)
 	ret = tpm_dev_transmit(priv->chip, priv->space, priv->data_buffer,
 			       sizeof(priv->data_buffer));
 	tpm_put_ops(priv->chip);
-	if (ret > 0) {
+
+	/*
+	 * 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 a return code.
+	 */
+	if (ret != 0) {
 		priv->response_length = ret;
 		mod_timer(&priv->user_read_timer, jiffies + (120 * HZ));
 	}