From: Jerry Snitselaar <jsnitsel@redhat.com>
To: Mimi Zohar <zohar@linux.ibm.com>
Cc: "Jarkko Sakkinen" <jarkko.sakkinen@linux.intel.com>,
"Petr Vorel" <pvorel@suse.cz>, Nayna <nayna@linux.vnet.ibm.com>,
linux-integrity <linux-integrity@vger.kernel.org>,
ltp@lists.linux.it, "Piotr Król" <piotr.krol@3mdeb.com>,
"Peter Huewe" <peterhuewe@gmx.de>,
"Jason Gunthorpe" <jgg@ziepe.ca>
Subject: Re: [LTP] [PATCH] ima: skip verifying TPM 2.0 PCR values
Date: Thu, 24 Oct 2019 19:11:59 -0700 [thread overview]
Message-ID: <20191025021159.dt7ifgnebnke6ca7@cantor> (raw)
In-Reply-To: <1571964420.5173.12.camel@linux.ibm.com>
On Thu Oct 24 19, Mimi Zohar wrote:
>On Thu, 2019-10-24 at 14:38 -0700, Jerry Snitselaar wrote:
>> On Thu Oct 24 19, Jarkko Sakkinen wrote:
>> >On Thu, Oct 24, 2019 at 02:18:48PM +0200, Petr Vorel wrote:
>> >> Hi all,
>> >>
>> >> I wonder what to do with this patch "ima: skip verifying TPM 2.0 PCR values" [1].
>> >> Is it a correct way to differentiate between TPM 1.2 and TPM 2.0?
>> >> Or something else should be applied?
>> >>
>> >> How is the work on TPM 2.0 Linux sysfs interface?
>> >> But even it's done in near future, we'd still need some way for older kernels.
>> >>
>> >> Kind regards,
>> >> Petr
>> >>
>> >> [1] https://patchwork.ozlabs.org/patch/1100733/
>> >
>> >version_major sysfs file would be acceptable if someone wants to proceed
>> >and send such patch.
>> >
>> >Also replicants for durations and timeouts files would make sense for
>> >TPM 2.0.
>> >
>> >/Jarkko
>>
>> Is it as simple as doing this?
>>
>> diff --git a/drivers/char/tpm/tpm-sysfs.c b/drivers/char/tpm/tpm-sysfs.c
>> index edfa89160010..fd8eb8d8945c 100644
>> --- a/drivers/char/tpm/tpm-sysfs.c
>> +++ b/drivers/char/tpm/tpm-sysfs.c
>> @@ -309,7 +309,17 @@ static ssize_t timeouts_show(struct device *dev, struct device_attribute *attr,
>> }
>> static DEVICE_ATTR_RO(timeouts);
>>
>> -static struct attribute *tpm_dev_attrs[] = {
>> +static ssize_t version_major_show(struct device *dev,
>> + struct device_attribute *attr, char *buf)
>> +{
>> + struct tpm_chip *chip = to_tpm_chip(dev);
>> +
>> + return sprintf(buf, "TPM%s\n", chip->flags & TPM_CHIP_FLAG_TPM2
>> + ? "2.0" : "1.2");
>> +}
>> +static DEVICE_ATTR_RO(version_major);
>> +
>> +static struct attribute *tpm12_dev_attrs[] = {
>> &dev_attr_pubek.attr,
>> &dev_attr_pcrs.attr,
>> &dev_attr_enabled.attr,
>> @@ -320,18 +330,28 @@ static struct attribute *tpm_dev_attrs[] = {
>> &dev_attr_cancel.attr,
>> &dev_attr_durations.attr,
>> &dev_attr_timeouts.attr,
>> + &dev_attr_version_major.attr,
>> NULL,
>> };
>>
>
>The TPM version seems to be included in "dev_attr_caps.attr".
>
>> -static const struct attribute_group tpm_dev_group = {
>> - .attrs = tpm_dev_attrs,
>> +static struct attribute *tpm20_dev_attrs[] = {
>> + &dev_attr_version_major.attr,
>> + NULL
>> +};
>
>This should work, but wouldn't exporting this information under
>security/tpmX, like the binary_bios_measurements, be a lot easier to
>find and use?
>
>Mimi
>
/sys/kernel/security/tpmX/major_version (on fedora and rhel at least, is it elsewhere on other distros?)
versus
/sys/class/tpm/tpmX/major_version
I don't know that it is any easier to find.
>> +
>> +static const struct attribute_group tpm12_dev_group = {
>> + .attrs = tpm12_dev_attrs,
>> +};
>> +
>> +static const struct attribute_group tpm20_dev_group = {
>> + .attrs = tpm20_dev_attrs,
>> };
>>
>> void tpm_sysfs_add_device(struct tpm_chip *chip)
>> {
>> - if (chip->flags & TPM_CHIP_FLAG_TPM2)
>> - return;
>> -
>> WARN_ON(chip->groups_cnt != 0);
>> - chip->groups[chip->groups_cnt++] = &tpm_dev_group;
>> + if (chip->flags & TPM_CHIP_FLAG_TPM2)
>> + chip->groups[chip->groups_cnt++] = &tpm20_dev_group;
>> + else
>> + chip->groups[chip->groups_cnt++] = &tpm12_dev_group;
>> }
>>
>>
>> Did a quick test on 2 systems here.
>
next prev parent reply other threads:[~2019-10-25 2:12 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-16 21:12 [PATCH] ima: skip verifying TPM 2.0 PCR values Mimi Zohar
2019-05-17 6:51 ` Petr Vorel
2019-05-17 11:19 ` Mimi Zohar
2019-05-17 11:28 ` Petr Vorel
2019-05-17 13:50 ` Nayna
2019-05-17 15:04 ` Petr Vorel
2019-10-24 12:18 ` [LTP] " Petr Vorel
2019-10-24 17:20 ` Jarkko Sakkinen
2019-10-24 18:20 ` Jason Gunthorpe
2019-10-24 19:14 ` Jarkko Sakkinen
2019-10-24 23:36 ` Jason Gunthorpe
2019-10-28 20:51 ` Jarkko Sakkinen
2019-10-24 21:38 ` Jerry Snitselaar
2019-10-24 23:26 ` Jason Gunthorpe
2019-10-25 0:47 ` Mimi Zohar
2019-10-25 2:11 ` Jerry Snitselaar [this message]
2019-10-25 8:56 ` Petr Vorel
2019-10-25 12:52 ` Serge E. Hallyn
2019-10-25 13:22 ` Mimi Zohar
2019-10-25 13:25 ` Petr Vorel
2019-10-25 14:13 ` Jerry Snitselaar
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