diff mbox series

tpm: ibmvtpm: Avoid error message when process gets signal while waiting

Message ID 20210712162505.205943-1-stefanb@linux.vnet.ibm.com (mailing list archive)
State New, archived
Headers show
Series tpm: ibmvtpm: Avoid error message when process gets signal while waiting | expand

Commit Message

Stefan Berger July 12, 2021, 4:25 p.m. UTC 
From: Stefan Berger <stefanb@linux.ibm.com>

When rngd is run as root then lots of these types of message will appear
in the kernel log if the TPM has been configure to provide random bytes:

[ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4

The issue is caused by the following call that is interrupted while
waiting for the TPM's response.

sig = wait_event_interruptible(ibmvtpm->wq,
                               !ibmvtpm->tpm_processing_cmd);

The solution is to use wait_event() instead.

To recreat the issue start rngd like this:

sudo rngd -r /dev/hwrng -t

Link: https://bugzilla.redhat.com/show_bug.cgi?id=1981473
Fixes: 6674ff145eef ("tpm_ibmvtpm: properly handle interrupted packet receptions")
Cc: Nayna Jain <nayna@linux.ibm.com>
Cc: George Wilson <gcwilson@linux.ibm.com>
Reported-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>
---
 drivers/char/tpm/tpm_ibmvtpm.c | 13 ++++---------
 1 file changed, 4 insertions(+), 9 deletions(-)

Comments

R Nageswara Sastry July 13, 2021, 5:03 a.m. UTC | #1 
On 12/07/21 9:55 pm, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.ibm.com>
> 
> When rngd is run as root then lots of these types of message will appear
> in the kernel log if the TPM has been configure to provide random bytes:
> 
> [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
> 
> The issue is caused by the following call that is interrupted while
> waiting for the TPM's response.
> 
> sig = wait_event_interruptible(ibmvtpm->wq,
>                                 !ibmvtpm->tpm_processing_cmd);
> 
> The solution is to use wait_event() instead.
> 
> To recreat the issue start rngd like this:
> 
> sudo rngd -r /dev/hwrng -t
> 
> Link: https://bugzilla.redhat.com/show_bug.cgi?id=1981473
> Fixes: 6674ff145eef ("tpm_ibmvtpm: properly handle interrupted packet receptions")
> Cc: Nayna Jain <nayna@linux.ibm.com>
> Cc: George Wilson <gcwilson@linux.ibm.com>
> Reported-by: Nageswara R Sastry <rnsastry@linux.ibm.com>
> Signed-off-by: Stefan Berger <stefanb@linux.ibm.com>

Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>

> ---
>   drivers/char/tpm/tpm_ibmvtpm.c | 13 ++++---------
>   1 file changed, 4 insertions(+), 9 deletions(-)
> 
> diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
> index 903604769de9..99b0442a5fdf 100644
> --- a/drivers/char/tpm/tpm_ibmvtpm.c
> +++ b/drivers/char/tpm/tpm_ibmvtpm.c
> @@ -106,16 +106,13 @@ static int tpm_ibmvtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
>   {
>   	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
>   	u16 len;
> -	int sig;
>   
>   	if (!ibmvtpm->rtce_buf) {
>   		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
>   		return 0;
>   	}
>   
> -	sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
> -	if (sig)
> -		return -EINTR;
> +	wait_event(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
>   
>   	len = ibmvtpm->res_len;
>   
> @@ -206,7 +203,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
>   {
>   	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
>   	bool retry = true;
> -	int rc, sig;
> +	int rc;
>   
>   	if (!ibmvtpm->rtce_buf) {
>   		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
> @@ -224,9 +221,7 @@ static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
>   		dev_info(ibmvtpm->dev,
>   		         "Need to wait for TPM to finish\n");
>   		/* wait for previous command to finish */
> -		sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
> -		if (sig)
> -			return -EINTR;
> +		wait_event(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
>   	}
>   
>   	spin_lock(&ibmvtpm->rtce_lock);
> @@ -551,7 +546,7 @@ static void ibmvtpm_crq_process(struct ibmvtpm_crq *crq,
>   			/* len of the data in rtce buffer */
>   			ibmvtpm->res_len = be16_to_cpu(crq->len);
>   			ibmvtpm->tpm_processing_cmd = false;
> -			wake_up_interruptible(&ibmvtpm->wq);
> +			wake_up(&ibmvtpm->wq);
>   			return;
>   		default:
>   			return;
>
Jarkko Sakkinen July 27, 2021, 2:42 a.m. UTC | #2 
On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
> From: Stefan Berger <stefanb@linux.ibm.com>
> 
> When rngd is run as root then lots of these types of message will appear
> in the kernel log if the TPM has been configure to provide random bytes:
> 
> [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
> 
> The issue is caused by the following call that is interrupted while
> waiting for the TPM's response.
> 
> sig = wait_event_interruptible(ibmvtpm->wq,
>                                !ibmvtpm->tpm_processing_cmd);
> 
> The solution is to use wait_event() instead.

Why?

/Jarkko
Stefan Berger July 27, 2021, 3 a.m. UTC | #3 
On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
> On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
>> From: Stefan Berger <stefanb@linux.ibm.com>
>>
>> When rngd is run as root then lots of these types of message will appear
>> in the kernel log if the TPM has been configure to provide random bytes:
>>
>> [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
>>
>> The issue is caused by the following call that is interrupted while
>> waiting for the TPM's response.
>>
>> sig = wait_event_interruptible(ibmvtpm->wq,
>>                                 !ibmvtpm->tpm_processing_cmd);
>>
>> The solution is to use wait_event() instead.
> Why?

So it becomes uninterruptible and these error messages go away.

     Stefan

>
> /Jarkko
Jarkko Sakkinen July 28, 2021, 9:50 p.m. UTC | #4 
On Mon, Jul 26, 2021 at 11:00:51PM -0400, Stefan Berger wrote:
> 
> On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
> > On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
> > > From: Stefan Berger <stefanb@linux.ibm.com>
> > > 
> > > When rngd is run as root then lots of these types of message will appear
> > > in the kernel log if the TPM has been configure to provide random bytes:
> > > 
> > > [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
> > > 
> > > The issue is caused by the following call that is interrupted while
> > > waiting for the TPM's response.
> > > 
> > > sig = wait_event_interruptible(ibmvtpm->wq,
> > >                                 !ibmvtpm->tpm_processing_cmd);
> > > 
> > > The solution is to use wait_event() instead.
> > Why?
> 
> So it becomes uninterruptible and these error messages go away.

We do not want to make a process uninterruptible. That would prevent
killing it.

/Jarkko
Stefan Berger July 29, 2021, 1:39 p.m. UTC | #5 
On 7/28/21 5:50 PM, Jarkko Sakkinen wrote:
> On Mon, Jul 26, 2021 at 11:00:51PM -0400, Stefan Berger wrote:
>> On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
>>> On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
>>>> From: Stefan Berger <stefanb@linux.ibm.com>
>>>>
>>>> When rngd is run as root then lots of these types of message will appear
>>>> in the kernel log if the TPM has been configure to provide random bytes:
>>>>
>>>> [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
>>>>
>>>> The issue is caused by the following call that is interrupted while
>>>> waiting for the TPM's response.
>>>>
>>>> sig = wait_event_interruptible(ibmvtpm->wq,
>>>>                                  !ibmvtpm->tpm_processing_cmd);
>>>>
>>>> The solution is to use wait_event() instead.
>>> Why?
>> So it becomes uninterruptible and these error messages go away.
> We do not want to make a process uninterruptible. That would prevent
> killing it.

I guess we'll have to go back to this one then: 
https://www.spinics.net/lists/linux-integrity/msg16741.html

    Stefan


>
> /Jarkko
Jarkko Sakkinen July 30, 2021, 12:57 a.m. UTC | #6 
On Thu, Jul 29, 2021 at 09:39:18AM -0400, Stefan Berger wrote:
> 
> On 7/28/21 5:50 PM, Jarkko Sakkinen wrote:
> > On Mon, Jul 26, 2021 at 11:00:51PM -0400, Stefan Berger wrote:
> > > On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
> > > > On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
> > > > > From: Stefan Berger <stefanb@linux.ibm.com>
> > > > > 
> > > > > When rngd is run as root then lots of these types of message will appear
> > > > > in the kernel log if the TPM has been configure to provide random bytes:
> > > > > 
> > > > > [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
> > > > > 
> > > > > The issue is caused by the following call that is interrupted while
> > > > > waiting for the TPM's response.
> > > > > 
> > > > > sig = wait_event_interruptible(ibmvtpm->wq,
> > > > >                                  !ibmvtpm->tpm_processing_cmd);
> > > > > 
> > > > > The solution is to use wait_event() instead.
> > > > Why?
> > > So it becomes uninterruptible and these error messages go away.
> > We do not want to make a process uninterruptible. That would prevent
> > killing it.
> 
> I guess we'll have to go back to this one then:
> https://www.spinics.net/lists/linux-integrity/msg16741.html

Makes a heck lot more sense.

There's a typo in the commit message: PM_STATUS_BUSY 

Also the commit message lacks explanation of this change completely:

@@ -690,8 +688,15 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
 		goto init_irq_cleanup;
 	}
 
-	if (!strcmp(id->compat, "IBM,vtpm20")) {
+
+	if (!strcmp(id->compat, "IBM,vtpm20"))
 		chip->flags |= TPM_CHIP_FLAG_TPM2;
+
+	rc = tpm_get_timeouts(chip);
+	if (rc)
+		goto init_irq_cleanup;
+
+	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
 		rc = tpm2_get_cc_attrs_tbl(chip);

The last paragraph should be rewritten in imperative form.

Finally, you could simplify the fix by simply changing the type of
tpm_processing_cmd to u8, and just set it to 'true' and 'false',
which will set the first bit.

/Jarkko
Stefan Berger July 30, 2021, 11:45 a.m. UTC | #7 
On 7/29/21 8:57 PM, Jarkko Sakkinen wrote:
> On Thu, Jul 29, 2021 at 09:39:18AM -0400, Stefan Berger wrote:
>> On 7/28/21 5:50 PM, Jarkko Sakkinen wrote:
>>> On Mon, Jul 26, 2021 at 11:00:51PM -0400, Stefan Berger wrote:
>>>> On 7/26/21 10:42 PM, Jarkko Sakkinen wrote:
>>>>> On Mon, Jul 12, 2021 at 12:25:05PM -0400, Stefan Berger wrote:
>>>>>> From: Stefan Berger <stefanb@linux.ibm.com>
>>>>>>
>>>>>> When rngd is run as root then lots of these types of message will appear
>>>>>> in the kernel log if the TPM has been configure to provide random bytes:
>>>>>>
>>>>>> [ 7406.275163] tpm tpm0: tpm_transmit: tpm_recv: error -4
>>>>>>
>>>>>> The issue is caused by the following call that is interrupted while
>>>>>> waiting for the TPM's response.
>>>>>>
>>>>>> sig = wait_event_interruptible(ibmvtpm->wq,
>>>>>>                                   !ibmvtpm->tpm_processing_cmd);
>>>>>>
>>>>>> The solution is to use wait_event() instead.
>>>>> Why?
>>>> So it becomes uninterruptible and these error messages go away.
>>> We do not want to make a process uninterruptible. That would prevent
>>> killing it.
>> I guess we'll have to go back to this one then:
>> https://www.spinics.net/lists/linux-integrity/msg16741.html
> Makes a heck lot more sense.
>
> There's a typo in the commit message: PM_STATUS_BUSY
>
> Also the commit message lacks explanation of this change completely:
>
> @@ -690,8 +688,15 @@ static int tpm_ibmvtpm_probe(struct vio_dev *vio_dev,
>   		goto init_irq_cleanup;
>   	}
>   
> -	if (!strcmp(id->compat, "IBM,vtpm20")) {
> +
> +	if (!strcmp(id->compat, "IBM,vtpm20"))
>   		chip->flags |= TPM_CHIP_FLAG_TPM2;
> +
> +	rc = tpm_get_timeouts(chip);
> +	if (rc)
> +		goto init_irq_cleanup;
> +
> +	if (chip->flags & TPM_CHIP_FLAG_TPM2) {
>   		rc = tpm2_get_cc_attrs_tbl(chip);
>
> The last paragraph should be rewritten in imperative form.


will fix.

>
> Finally, you could simplify the fix by simply changing the type of
> tpm_processing_cmd to u8, and just set it to 'true' and 'false',
> which will set the first bit.

Are you sure? It's a bit mask we are using this with. Using 'true' for 
these type of operations doesn't sound right.

         u8 status = chip->ops->status(chip);
         if ((status & chip->ops->req_complete_mask) ==
             chip->ops->req_complete_val)

             goto out_recv;

https://elixir.bootlin.com/linux/latest/source/drivers/char/tpm/tpm-interface.c#L108

@@ -457,7 +455,7 @@ static const struct tpm_class_ops tpm_ibmvtpm = {
  	.send = tpm_ibmvtpm_send,
  	.cancel = tpm_ibmvtpm_cancel,
  	.status = tpm_ibmvtpm_status,
-	.req_complete_mask = 0,
+	.req_complete_mask = TPM_STATUS_BUSY,
  	.req_complete_val = 0,
  	.req_canceled = tpm_ibmvtpm_req_canceled,
  };


    Stefan

>
> /Jarkko
diff mbox series

Patch

diff --git a/drivers/char/tpm/tpm_ibmvtpm.c b/drivers/char/tpm/tpm_ibmvtpm.c
index 903604769de9..99b0442a5fdf 100644
--- a/drivers/char/tpm/tpm_ibmvtpm.c
+++ b/drivers/char/tpm/tpm_ibmvtpm.c
@@ -106,16 +106,13 @@  static int tpm_ibmvtpm_recv(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
 	u16 len;
-	int sig;
 
 	if (!ibmvtpm->rtce_buf) {
 		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
 		return 0;
 	}
 
-	sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
-	if (sig)
-		return -EINTR;
+	wait_event(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
 
 	len = ibmvtpm->res_len;
 
@@ -206,7 +203,7 @@  static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
 {
 	struct ibmvtpm_dev *ibmvtpm = dev_get_drvdata(&chip->dev);
 	bool retry = true;
-	int rc, sig;
+	int rc;
 
 	if (!ibmvtpm->rtce_buf) {
 		dev_err(ibmvtpm->dev, "ibmvtpm device is not ready\n");
@@ -224,9 +221,7 @@  static int tpm_ibmvtpm_send(struct tpm_chip *chip, u8 *buf, size_t count)
 		dev_info(ibmvtpm->dev,
 		         "Need to wait for TPM to finish\n");
 		/* wait for previous command to finish */
-		sig = wait_event_interruptible(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
-		if (sig)
-			return -EINTR;
+		wait_event(ibmvtpm->wq, !ibmvtpm->tpm_processing_cmd);
 	}
 
 	spin_lock(&ibmvtpm->rtce_lock);
@@ -551,7 +546,7 @@  static void ibmvtpm_crq_process(struct ibmvtpm_crq *crq,
 			/* len of the data in rtce buffer */
 			ibmvtpm->res_len = be16_to_cpu(crq->len);
 			ibmvtpm->tpm_processing_cmd = false;
-			wake_up_interruptible(&ibmvtpm->wq);
+			wake_up(&ibmvtpm->wq);
 			return;
 		default:
 			return;