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

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Date:   Tue, 06 Nov 2018 16:14:58 +0000
From:   Joshua Lock <joshua.g.lock@...ux.intel.com>
To:     Jerry Snitselaar <jsnitsel@...hat.com>,
        Stefan Berger <stefanb@...ux.ibm.com>,
        keyrings@...r.kernel.org, linux-integrity@...r.kernel.org,
        zohar@...ux.ibm.com, jejb@...ux.ibm.com,
        Alexander.Levin@...rosoft.com, jmorris@...ei.org,
        linux-kernel@...r.kernel.org
Cc:     William Roberts <william.c.roberts@...el.com>
Subject: Re: [PATCH] docs: Extend trusted keys documentation for TPM 2.0

On Tue, 2018-11-06 at 09:00 -0700, Jerry Snitselaar wrote:
> On Mon Nov 05 18, Jerry Snitselaar wrote:
> > On Fri Oct 19 18, 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".
> > > 
> > > +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
> > > +  #> tpm2_evictcontrol -c key.ctxt -p 0x81000001
> > > +  persistentHandle: 0x81000001
> > > +
> > 
> > Is that the correct option for tpm2_evictcontrol? What I'm seeing
> > in the versions I have is -S or -persistent= for specifying the
> > persistent handle.
> > 
> > Other than that looks good to me.
> 
> William, is the above correct?

We're changing some of the options in master ahead of our next major
release, the -p/--persistent option is correct for that branch and the
eventual 4.X series.

Regards,
Joshua

> > 
> > > 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
> > > +                       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
> > > 
> > > -- 
> > > 2.17.2
> > >