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

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Message-ID: <20181105204215.hw6vme5epxcc3nch@cantor>
Date:   Mon, 5 Nov 2018 13:42:15 -0700
From:   Jerry Snitselaar <jsnitsel@...hat.com>
To:     Stefan Berger <stefanb@...ux.ibm.com>
Cc:     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
Subject: Re: [PATCH] docs: Extend trusted keys documentation for TPM 2.0

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.

> 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
>