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Subject: Re: [PATCH] tpm_tis: verify locality released before returning from
 release_locality
To:     linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
        Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>,
        Peter Huewe <peterhuewe@gmx.de>, Jason Gunthorpe <jgg@ziepe.ca>
References: <20180505195453.10431-1-jsnitsel@redhat.com>
 <20180505200315.x7jt33j7psizmfyi@cantor>
From:   Laurent Bigonville <bigon@debian.org>
Message-ID: <bcac4481-108a-4598-6524-041879be7c06@debian.org>
Date:   Fri, 11 May 2018 21:02:16 +0200
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Le 05/05/18 à 22:03, Jerry Snitselaar a écrit :
> On Sat May 05 18, Jerry Snitselaar wrote:
>> For certain tpm chips releasing locality can take long enough that a
>> subsequent call to request_locality will see the locality as being
>> active when the access register is read in check_locality. So check
>> that the locality has been released before returning from
>> release_locality.
>>
>> Cc: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
>> Cc: Peter Huewe <peterhuewe@gmx.de>
>> Cc: Jason Gunthorpe <jgg@ziepe.ca>
>> Reported-by: Laurent Bigonville <bigon@debian.org>
>> Signed-off-by: Jerry Snitselaar <jsnitsel@redhat.com>
Tested-by: Laurent Bigonville <bigon@debian.org>
>> ---
>> drivers/char/tpm/tpm_tis_core.c | 47 
>> ++++++++++++++++++++++++++++++++++++++++-
>> 1 file changed, 46 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/char/tpm/tpm_tis_core.c 
>> b/drivers/char/tpm/tpm_tis_core.c
>> index 5a1f47b43947..d547cd309dbd 100644
>> --- a/drivers/char/tpm/tpm_tis_core.c
>> +++ b/drivers/char/tpm/tpm_tis_core.c
>> @@ -143,13 +143,58 @@ static bool check_locality(struct tpm_chip 
>> *chip, int l)
>>     return false;
>> }
>>
>> +static bool locality_inactive(struct tpm_chip *chip, int l)
>> +{
>> +    struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>> +    int rc;
>> +    u8 access;
>> +
>> +    rc = tpm_tis_read8(priv, TPM_ACCESS(l), &access);
>> +    if (rc < 0)
>> +        return false;
>> +
>> +    if ((access & (TPM_ACCESS_VALID | TPM_ACCESS_ACTIVE_LOCALITY))
>> +        == TPM_ACCESS_VALID)
>> +        return true;
>> +
>> +    return false;
>> +}
>> +
>> static int release_locality(struct tpm_chip *chip, int l)
>> {
>>     struct tpm_tis_data *priv = dev_get_drvdata(&chip->dev);
>> +    unsigned long stop, timeout;
>> +    long rc;
>>
>>     tpm_tis_write8(priv, TPM_ACCESS(l), TPM_ACCESS_ACTIVE_LOCALITY);
>>
>> -    return 0;
>> +    stop = jiffies + chip->timeout_a;
>> +
>> +    if (chip->flags & TPM_CHIP_FLAG_IRQ) {
>> +again:
>> +        timeout = stop - jiffies;
>> +        if ((long)timeout <= 0)
>> +            return -1;
>> +
>> +        rc = wait_event_interruptible_timeout(priv->int_queue,
>> +                              (locality_inactive(chip, l)),
>> +                              timeout);
>> +
>> +        if (rc > 0)
>> +            return 0;
>> +
>> +        if (rc == -ERESTARTSYS && freezing(current)) {
>> +            clear_thread_flag(TIF_SIGPENDING);
>> +            goto again;
>> +        }
>> +    } else {
>> +        do {
>> +            if (locality_inactive(chip, l))
>> +                return 0;
>> +            tpm_msleep(TPM_TIMEOUT);
>> +        } while (time_before(jiffies, stop));
>> +    }
>> +    return -1;
>> }
>>
>> static int request_locality(struct tpm_chip *chip, int l)
>> -- 
>> 2.15.0
>>
>
> Laurent,
>
> Can you try this patch with your system since it is the one
> that has exhibited the problem so far. I've tested on a
> tpm2.0 and tpm1.2 system here.
>
> Regards,
> Jerry