linux-kernel - Re: [PATCH] docs: Extend trusted keys documentation for TPM 2.0

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Date:   Fri, 19 Oct 2018 16:07:42 -0700
From:   Randy Dunlap <rdunlap@...radead.org>
To:     Stefan Berger <stefanb@...ux.ibm.com>, keyrings@...r.kernel.org,
        linux-integrity@...r.kernel.org
Cc:     zohar@...ux.ibm.com, jejb@...ux.ibm.com,
        Alexander.Levin@...rosoft.com, jsnitsel@...hat.com,
        jmorris@...ei.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] docs: Extend trusted keys documentation for TPM 2.0

Hi,
Feel free to ignore my comments.  I don't know anything about TPM.

On 10/19/18 3:17 AM, Stefan Berger wrote:
> Extend the documentation for trusted keys with documentation for how to
> set up a key for a TPM 2.0 so it can be used with a TPM 2.0 as well.
> 
> Signed-off-by: Stefan Berger <stefanb@...ux.ibm.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
>  .../security/keys/trusted-encrypted.rst       | 31 ++++++++++++++++++-
>  1 file changed, 30 insertions(+), 1 deletion(-)
> 
> diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
> index 3bb24e09a332..6ec6bb2ac497 100644
> --- a/Documentation/security/keys/trusted-encrypted.rst
> +++ b/Documentation/security/keys/trusted-encrypted.rst
> @@ -18,10 +18,33 @@ integrity verifications match.  A loaded Trusted Key can be updated with new
>  when the kernel and initramfs are updated.  The same key can have many saved
>  blobs under different PCR values, so multiple boots are easily supported.
>  
> +TPM 1.2
> +-------
> +
>  By default, trusted keys are sealed under the SRK, which has the default
>  authorization value (20 zeros).  This can be set at takeownership time with the
>  trouser's utility: "tpm_takeownership -u -z".

It appears to be TrouSerS or maybe just trousers (no ').

BTW, is this still the current location for it or has it moved elsewhere?
http://trousers.sourceforge.net/


>  
> +TPM 2.0
> +-------
> +
> +The user must first create a storage key and make it persistent, so the key is
> +available after reboot. This can be done using the following commands.
> +
> +With the IBM TSS 2 stack::
> +
> +  #> tsscreateprimary -hi o -st
> +  Handle 80000000
> +  #> tssevictcontrol -hi o -ho 80000000 -hp 81000001
> +
> +Or with the Intel TSS 2 stack::
> +
> +  #> tpm2_createprimary --hierarchy o -G rsa2048 -o key.ctxt
> +  [...]
> +  handle: 0x800000FF

Is that handle value important?  It doesn't seem to be used later...

> +  #> tpm2_evictcontrol -c key.ctxt -p 0x81000001
> +  persistentHandle: 0x81000001
> +
>  Usage::
>  
>      keyctl add trusted name "new keylen [options]" ring
> @@ -30,7 +53,9 @@ Usage::
>      keyctl print keyid
>  
>      options:
> -       keyhandle=    ascii hex value of sealing key default 0x40000000 (SRK)
> +       keyhandle=    ascii hex value of sealing key

s/ascii/ASCII/g

> +                       TPM 1.2: default 0x40000000 (SRK)
> +                       TPM 2.0: no default; must be passed every time
>         keyauth=	     ascii hex auth for sealing key default 0x00...i
>                       (40 ascii zeros)
>         blobauth=     ascii hex auth for sealed data default 0x00...
> @@ -84,6 +109,10 @@ Examples of trusted and encrypted key usage:
>  
>  Create and save a trusted key named "kmk" of length 32 bytes::
>  
> +Note: When using a TPM 2.0 with a persistent key with handle 0x81000001,
> +append 'keyhandle=0x81000001' to statements between quotes, such as
> +"new 32 keyhandle=0x81000001".
> +
>      $ keyctl add trusted kmk "new 32" @u
>      440502848
>  
> 

ta.
-- 
~Randy