On Tue, 2020-02-25 at 18:48 +0200, Jarkko Sakkinen wrote:
> On Thu, Jan 30, 2020 at 11:18:09AM +0100, 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.
> >
> > Signed-off-by: James Bottomley <James.Bottomley@HansenPartnership.c
> > om>
>
> Should have a fixes tag.
I made all the other changes, but I'm not sure what to identify in the
fixes tag. The problem is the code I updated was simply carried over
unaltered from TPM 1.2
You could certainly argue that commit
commit 0fe5480303a1657b328a0a389f8d99249d9961f5
Author: Jarkko Sakkinen <jarkko.sakkinen@xxxxxxxxxxxxxxx>
Date: Fri Jun 26 22:28:26 2015 +0300
keys, trusted: seal/unseal with TPM 2.0 chips
Should have updated the blobauth handling ... is that the one you'd
like fixes: to identify?
James
