Documentation/ABI/stable/sysfs-class-tpm
What: /sys/class/tpm/tpmX/device/
Date: April 2005
KernelVersion: 2.6.12
Contact: linux-integrity@vger.kernel.org
Description: The device/ directory under a specific TPM instance exposes
the properties of that TPM chip
What: /sys/class/tpm/tpmX/device/active
Date: April 2006
KernelVersion: 2.6.17
Contact: linux-integrity@vger.kernel.org
Description: The "active" property prints a '1' if the TPM chip is accepting
commands. An inactive TPM chip still contains all the state of
an active chip (Storage Root Key, NVRAM, etc), and can be
visible to the OS, but will only accept a restricted set of
commands. See the TPM Main Specification part 2, Structures,
section 17 for more information on which commands are
available.
What: /sys/class/tpm/tpmX/device/cancel
Date: June 2005
KernelVersion: 2.6.13
Contact: linux-integrity@vger.kernel.org
Description: The "cancel" property allows you to cancel the currently
pending TPM command. Writing any value to cancel will call the
TPM vendor specific cancel operation.
What: /sys/class/tpm/tpmX/device/caps
Date: April 2005
KernelVersion: 2.6.12
Contact: linux-integrity@vger.kernel.org
Description: The "caps" property contains TPM manufacturer and version info.
Example output::
Manufacturer: 0x53544d20
TCG version: 1.2
Firmware version: 8.16
Manufacturer is a hex dump of the 4 byte manufacturer info
space in a TPM. TCG version shows the TCG TPM spec level that
the chip supports. Firmware version is that of the chip and
is manufacturer specific.
What: /sys/class/tpm/tpmX/device/durations
Date: March 2011
KernelVersion: 3.1
Contact: linux-integrity@vger.kernel.org
Description: The "durations" property shows the 3 vendor-specific values
used to wait for a short, medium and long TPM command. All
TPM commands are categorized as short, medium or long in
execution time, so that the driver doesn't have to wait
any longer than necessary before starting to poll for a
result.
Example output::
3015000 4508000 180995000 [original]
Here the short, medium and long durations are displayed in
usecs. "[original]" indicates that the values are displayed
unmodified from when they were queried from the chip.
Durations can be modified in the case where a buggy chip
reports them in msec instead of usec and they need to be
scaled to be displayed in usecs. In this case "[adjusted]"
will be displayed in place of "[original]".
What: /sys/class/tpm/tpmX/device/enabled
Date: April 2006
KernelVersion: 2.6.17
Contact: linux-integrity@vger.kernel.org
Description: The "enabled" property prints a '1' if the TPM chip is enabled,
meaning that it should be visible to the OS. This property
may be visible but produce a '0' after some operation that
disables the TPM.
What: /sys/class/tpm/tpmX/device/owned
Date: April 2006
KernelVersion: 2.6.17
Contact: linux-integrity@vger.kernel.org
Description: The "owned" property produces a '1' if the TPM_TakeOwnership
ordinal has been executed successfully in the chip. A '0'
indicates that ownership hasn't been taken.
What: /sys/class/tpm/tpmX/device/pcrs
Date: April 2005
KernelVersion: 2.6.12
Contact: linux-integrity@vger.kernel.org
Description: The "pcrs" property will dump the current value of all Platform
Configuration Registers in the TPM. Note that since these
values may be constantly changing, the output is only valid
for a snapshot in time.
Example output::
PCR-00: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
PCR-01: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
PCR-02: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
PCR-03: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
PCR-04: 3A 3F 78 0F 11 A4 B4 99 69 FC AA 80 CD 6E 39 57 C3 3B 22 75
...
The number of PCRs and hex bytes needed to represent a PCR
value will vary depending on TPM chip version. For TPM 1.1 and
1.2 chips, PCRs represent SHA-1 hashes, which are 20 bytes
long. Use the "caps" property to determine TPM version.
What: /sys/class/tpm/tpmX/device/pubek
Date: April 2005
KernelVersion: 2.6.12
Contact: linux-integrity@vger.kernel.org
Description: The "pubek" property will return the TPM's public endorsement
key if possible. If the TPM has had ownership established and
is version 1.2, the pubek will not be available without the
owner's authorization. Since the TPM driver doesn't store any
secrets, it can't authorize its own request for the pubek,
making it unaccessible. The public endorsement key is gener-
ated at TPM manufacture time and exists for the life of the
chip.
Example output::
Algorithm: 00 00 00 01
Encscheme: 00 03
Sigscheme: 00 01
Parameters: 00 00 08 00 00 00 00 02 00 00 00 00
Modulus length: 256
Modulus:
B4 76 41 82 C9 20 2C 10 18 40 BC 8B E5 44 4C 6C
3A B2 92 0C A4 9B 2A 83 EB 5C 12 85 04 48 A0 B6
1E E4 81 84 CE B2 F2 45 1C F0 85 99 61 02 4D EB
86 C4 F7 F3 29 60 52 93 6B B2 E5 AB 8B A9 09 E3
D7 0E 7D CA 41 BF 43 07 65 86 3C 8C 13 7A D0 8B
82 5E 96 0B F8 1F 5F 34 06 DA A2 52 C1 A9 D5 26
0F F4 04 4B D9 3F 2D F2 AC 2F 74 64 1F 8B CD 3E
1E 30 38 6C 70 63 69 AB E2 50 DF 49 05 2E E1 8D
6F 78 44 DA 57 43 69 EE 76 6C 38 8A E9 8E A3 F0
A7 1F 3C A8 D0 12 15 3E CA 0E BD FA 24 CD 33 C6
47 AE A4 18 83 8E 22 39 75 93 86 E6 FD 66 48 B6
10 AD 94 14 65 F9 6A 17 78 BD 16 53 84 30 BF 70
E0 DC 65 FD 3C C6 B0 1E BF B9 C1 B5 6C EF B1 3A
F8 28 05 83 62 26 11 DC B4 6B 5A 97 FF 32 26 B6
F7 02 71 CF 15 AE 16 DD D1 C1 8E A8 CF 9B 50 7B
C3 91 FF 44 1E CF 7C 39 FE 17 77 21 20 BD CE 9B
Possible values::
Algorithm: TPM_ALG_RSA (1)
Encscheme: TPM_ES_RSAESPKCSv15 (2)
TPM_ES_RSAESOAEP_SHA1_MGF1 (3)
Sigscheme: TPM_SS_NONE (1)
Parameters, a byte string of 3 u32 values:
Key Length (bits): 00 00 08 00 (2048)
Num primes: 00 00 00 02 (2)
Exponent Size: 00 00 00 00 (0 means the
default exp)
Modulus Length: 256 (bytes)
Modulus: The 256 byte Endorsement Key modulus
What: /sys/class/tpm/tpmX/device/temp_deactivated
Date: April 2006
KernelVersion: 2.6.17
Contact: linux-integrity@vger.kernel.org
Description: The "temp_deactivated" property returns a '1' if the chip has
been temporarily deactivated, usually until the next power
cycle. Whether a warm boot (reboot) will clear a TPM chip
from a temp_deactivated state is platform specific.
What: /sys/class/tpm/tpmX/device/timeouts
Date: March 2011
KernelVersion: 3.1
Contact: linux-integrity@vger.kernel.org
Description: The "timeouts" property shows the 4 vendor-specific values
for the TPM's interface spec timeouts. The use of these
timeouts is defined by the TPM interface spec that the chip
conforms to.
Example output::
750000 750000 750000 750000 [original]
The four timeout values are shown in usecs, with a trailing
"[original]" or "[adjusted]" depending on whether the values
were scaled by the driver to be reported in usec from msecs.
What: /sys/class/tpm/tpmX/tpm_version_major
Date: October 2019
KernelVersion: 5.5
Contact: linux-integrity@vger.kernel.org
Description: The "tpm_version_major" property shows the TCG spec major version
implemented by the TPM device.
Example output::
2
What: /sys/class/tpm/tpmX/pcr-<H>/<N>
Date: March 2021
KernelVersion: 5.12
Contact: linux-integrity@vger.kernel.org
Description: produces output in compact hex representation for PCR
number N from hash bank H. N is the numeric value of
the PCR number and H is the crypto string
representation of the hash
Example output::
cat /sys/class/tpm/tpm0/pcr-sha256/7
2ED93F199692DC6788EFA6A1FE74514AB9760B2A6CEEAEF6C808C13E4ABB0D42