On Sat, Sep 12, 2020 at 10:26:41AM -0700, James Bottomley wrote:
> In TPM 1.2 an authorization was a 20 byte number. The spec actually
> recommended you to hash variable length passwords and use the sha1
> hash as the authorization. Because the spec doesn't require this
> hashing, the current authorization for trusted keys is a 40 digit hex
> number. For TPM 2.0 the spec allows the passing in of variable length
> passwords and passphrases directly, so we should allow that in trusted
> keys for ease of use. Update the 'blobauth' parameter to take this
> into account, so we can now use plain text passwords for the keys.
>
> so before
>
> keyctl add trusted kmk "new 32 blobauth=f572d396fae9206628714fb2ce00f72e94f2258f"
>
> after we will accept both the old hex sha1 form as well as a new
> directly supplied password:
>
> keyctl add trusted kmk "new 32 blobauth=hello keyhandle=81000001"
>
> Since a sha1 hex code must be exactly 40 bytes long and a direct
> password must be 20 or less, we use the length as the discriminator
> for which form is input.
>
> Note this is both and enhancement and a potential bug fix. The TPM
> 2.0 spec requires us to strip leading zeros, meaning empyty
> authorization is a zero length HMAC whereas we're currently passing in
> 20 bytes of zeros. A lot of TPMs simply accept this as OK, but the
> Microsoft TPM emulator rejects it with TPM_RC_BAD_AUTH, so this patch
> makes the Microsoft TPM emulator work with trusted keys.
>
> Fixes: 0fe5480303a1 ("keys, trusted: seal/unseal with TPM 2.0 chips")
> Signed-off-by: James Bottomley <James.Bottomley@xxxxxxxxxxxxxxxxxxxxx>
> Reviewed-by: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
I created a key:
$ sudo ./tpm2-root-key
0x80000000
$ sudo ./tpm2-list-handles
0x80000000
$ keyctl add trusted kmk "new 32 blobauth=hello keyhandle=0x80000000"
<keyctl usage>
$ lsmod
Module Size Used by
sha1_generic 16384 2
trusted 32768 0
asn1_encoder 16384 1 trusted
x86_pkg_temp_thermal 20480 0
iwlmvm 356352 0
iwlwifi 315392 1 iwlmvm
tpm_crb 16384 0
tpm_tis 16384 0
tpm_tis_core 24576 1 tpm_tis
tpm 61440 4 tpm_tis,trusted,tpm_crb,tpm_tis_core
efivarfs 16384 1
What could be wrong? Have the full seris applied on a test kernel.
The root key creation is contained in create_root_key():
https://github.com/jsakkine-intel/tpm2-scripts/blob/master/tpm2.py
/Jarkko
