From: Jarkko Sakkinen <jarkko.sakkinen@linux.intel.com>
To: "Safford, David (GE Global Research, US)" <david.safford@ge.com>
Cc: Mimi Zohar <zohar@linux.ibm.com>,
"Wiseman, Monty (GE Global Research, US)" <monty.wiseman@ge.com>,
"linux-integrity@vger.kernel.org"
<linux-integrity@vger.kernel.org>,
"stable@vger.kernel.org" <stable@vger.kernel.org>,
David Howells <dhowells@redhat.com>,
Herbert Xu <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
"open list:ASYMMETRIC KEYS" <keyrings@vger.kernel.org>,
"open list:CRYPTO API" <linux-crypto@vger.kernel.org>,
open list <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes()
Date: Fri, 4 Oct 2019 21:27:11 +0300 [thread overview]
Message-ID: <20191004182711.GC6945@linux.intel.com> (raw)
In-Reply-To: <BCA04D5D9A3B764C9B7405BBA4D4A3C035F2A22E@ALPMBAPA12.e2k.ad.ge.com>
On Fri, Oct 04, 2019 at 01:26:58PM +0000, Safford, David (GE Global Research, US) wrote:
> As the original author of trusted keys, let me make a few comments.
> First, trusted keys were specifically implemented and *documented* to
> use the TPM to both generate and seal keys. Its kernel documentation
> specifically states this as a promise to user space. If you want to have
> a different key system that uses the random pool to generate the keys,
> fine, but don't change trusted keys, as that changes the existing promise
> to user space.
TPM generating keys (i.e. the random number) would make sense if the key
would never leave from TPM (that kind of trusted keys would not be a
bad idea at all).
> There are many good reasons for wanting the keys to be based on the
> TPM generator. As the source for the kernel random number generator
> itself says, some systems lack good randomness at startup, and systems
> should preserve and reload the pool across shutdown and startup.
> There are use cases for trusted keys which need to generate keys
> before such scripts have run. Also, in some use cases, we need to show
> that trusted keys are FIPS compliant, which is possible with TPM
> generated keys.
If you are able to call tpm_get_random(), the driver has already
registered TPN as hwrng. With this solution you fail to follow the
principle of defense in depth. If the TPM random number generator
is compromissed (has a bug) using the entropy pool will decrease
the collateral damage.
> Second, the TPM is hardly a "proprietary random number generator".
> It is an open standard with multiple implementations, many of which are
> FIPS certified.
>
> Third, as Mimi states, using a TPM is not a "regression". It would be a
> regression to change trusted keys _not_ to use the TPM, because that
> is what trusted keys are documented to provide to user space.
For asym-tpm.c it is without a question a regression because of the
evolution that has happened after trusted keys. For trusted keys
using kernel rng would be improvement.
/Jarkko
next prev parent reply other threads:[~2019-10-04 18:27 UTC|newest]
Thread overview: 58+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-26 17:16 [PATCH] KEYS: asym_tpm: Switch to get_random_bytes() Jarkko Sakkinen
2019-09-28 18:05 ` Jerry Snitselaar
2019-10-01 20:54 ` Jarkko Sakkinen
2019-10-02 14:00 ` Mimi Zohar
2019-10-03 11:41 ` Jarkko Sakkinen
2019-10-03 11:43 ` Jarkko Sakkinen
2019-10-03 13:02 ` Mimi Zohar
2019-10-03 17:58 ` Jarkko Sakkinen
2019-10-03 18:53 ` Mimi Zohar
2019-10-03 21:51 ` Jarkko Sakkinen
2019-10-03 21:57 ` Jarkko Sakkinen
2019-10-03 22:08 ` Mimi Zohar
2019-10-03 23:59 ` James Bottomley
2019-10-04 18:22 ` Jarkko Sakkinen
2019-10-04 18:24 ` James Bottomley
2019-10-04 18:33 ` Jerry Snitselaar
2019-10-04 18:42 ` James Bottomley
2019-10-04 20:07 ` Jerry Snitselaar
2019-10-04 20:11 ` Jerry Snitselaar
2019-10-04 22:11 ` James Bottomley
2019-10-06 0:38 ` Mimi Zohar
2019-10-06 23:52 ` Jarkko Sakkinen
2019-10-07 18:08 ` Mimi Zohar
2019-10-04 18:20 ` Jarkko Sakkinen
2019-10-03 22:10 ` Jarkko Sakkinen
2019-10-04 13:26 ` Safford, David (GE Global Research, US)
2019-10-04 18:27 ` Jarkko Sakkinen [this message]
2019-10-04 18:30 ` Jarkko Sakkinen
2019-10-04 19:56 ` Safford, David (GE Global Research, US)
2019-10-07 0:05 ` Jarkko Sakkinen
2019-10-07 22:13 ` Ken Goldman
2019-10-08 23:49 ` Jarkko Sakkinen
2019-10-08 23:53 ` Jarkko Sakkinen
2019-10-09 7:10 ` Pascal Van Leeuwen
2019-10-09 7:33 ` Jarkko Sakkinen
2019-10-09 7:41 ` Jarkko Sakkinen
2019-10-09 8:09 ` Pascal Van Leeuwen
2019-10-14 19:11 ` Jarkko Sakkinen
2019-10-09 8:02 ` Pascal Van Leeuwen
2019-10-09 12:11 ` Safford, David (GE Global Research, US)
2019-10-14 19:00 ` Jarkko Sakkinen
2019-10-14 19:29 ` Jarkko Sakkinen
2019-10-14 19:29 ` James Bottomley
2019-10-16 11:00 ` Jarkko Sakkinen
2019-10-16 12:34 ` James Bottomley
2019-10-16 16:25 ` Jarkko Sakkinen
2019-10-16 19:10 ` James Bottomley
2019-10-17 12:52 ` Sumit Garg
2019-10-17 12:58 ` James Bottomley
2019-10-17 18:04 ` Jarkko Sakkinen
2019-10-21 11:39 ` Jarkko Sakkinen
2019-10-29 8:42 ` Jarkko Sakkinen
2019-10-29 14:58 ` James Bottomley
2019-10-31 21:03 ` Jarkko Sakkinen
2019-10-18 7:32 ` Janne Karhunen
2019-10-03 18:02 ` Jarkko Sakkinen
2019-10-03 18:15 ` Jarkko Sakkinen
2019-10-07 10:33 ` Janne Karhunen
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