From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: James Bottomley <James.Bottomley@HansenPartnership.com>
Cc: linux-integrity@vger.kernel.org, Mimi Zohar <zohar@linux.ibm.com>,
David Woodhouse <dwmw2@infradead.org>,
keyrings@vger.kernel.org
Subject: Re: [PATCH v5 3/6] security: keys: trusted fix tpm2 authorizations
Date: Thu, 27 Feb 2020 18:19:49 +0200 [thread overview]
Message-ID: <20200227161949.GD5140@linux.intel.com> (raw)
In-Reply-To: <1582765091.4245.33.camel@HansenPartnership.com>
On Wed, Feb 26, 2020 at 04:58:11PM -0800, James Bottomley wrote:
> 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@linux.intel.com>
> 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?
What I'm thinking is to have fixes tag w/o cc to stable. I'm not
sure at this point whether we want to backport this but it still
makes sense to tag it.
/Jarkko
next prev parent reply other threads:[~2020-02-27 16:19 UTC|newest]
Thread overview: 27+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-01-30 10:18 [PATCH v5 0/6] TPM 2.0 trusted keys with attached policy James Bottomley
2020-01-30 10:18 ` [PATCH v5 1/6] lib: add ASN.1 encoder James Bottomley
2020-01-30 10:18 ` [PATCH v5 2/6] oid_registry: Add TCG defined OIDS for TPM keys James Bottomley
2020-01-30 10:18 ` [PATCH v5 3/6] security: keys: trusted fix tpm2 authorizations James Bottomley
2020-02-25 16:48 ` Jarkko Sakkinen
2020-02-26 15:15 ` Jarkko Sakkinen
2020-02-27 0:58 ` James Bottomley
2020-02-27 16:19 ` Jarkko Sakkinen [this message]
2020-02-27 16:21 ` James Bottomley
2020-02-27 17:49 ` James Bottomley
2020-03-02 11:08 ` Jarkko Sakkinen
2020-01-30 10:18 ` [PATCH v5 4/6] security: keys: trusted: use ASN.1 TPM2 key format for the blobs James Bottomley
2020-02-03 16:54 ` James Prestwood
2020-02-27 0:02 ` James Bottomley
2020-02-27 0:20 ` James Prestwood
2020-02-27 0:54 ` James Bottomley
2020-02-27 17:19 ` James Prestwood
2020-02-27 20:19 ` James Bottomley
2020-02-27 20:26 ` James Bottomley
2020-02-27 20:44 ` James Prestwood
2020-02-27 20:57 ` James Prestwood
2020-07-12 21:38 ` Ken Goldman
2020-07-12 21:54 ` James Bottomley
2020-03-02 19:00 ` James Prestwood
2020-01-30 10:18 ` [PATCH v5 5/6] security: keys: trusted: add ability to specify arbitrary policy James Bottomley
2020-01-30 10:18 ` [PATCH v5 6/6] security: keys: trusted: implement counter/timer policy James Bottomley
2020-02-20 20:17 ` [PATCH v5 0/6] TPM 2.0 trusted keys with attached policy Jarkko Sakkinen
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