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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: Mon, 7 Oct 2019 03:05:20 +0300	[thread overview]
Message-ID: <20191007000520.GA17116@linux.intel.com> (raw)
In-Reply-To: <BCA04D5D9A3B764C9B7405BBA4D4A3C035F2A38B@ALPMBAPA12.e2k.ad.ge.com>

On Fri, Oct 04, 2019 at 07:56:01PM +0000, Safford, David (GE Global Research, US) wrote:
> 
> > From: linux-integrity-owner@vger.kernel.org <linux-integrity-
> > owner@vger.kernel.org> On Behalf Of Jarkko Sakkinen
> > Sent: Friday, October 4, 2019 2:27 PM
> > Subject: EXT: Re: [PATCH] KEYS: asym_tpm: Switch to get_random_bytes()
> > 
> > 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.
> 
> And if the entropy pool has a bug or is misconfigured, you lose everything.
> That does not sound like defense in depth to me. In the real world
> I am not aware of a single instance of RNG vulnerability on a TPM.
> I am directly aware of several published vulnerabilities in embedded systems 
> due to a badly ported version of the kernel random pool. In addition, 
> the random generator in a TPM is hardware isolated, and less likely to be
> vulnerable to side channel or memory manipulation errors. The TPM
> RNG is typically FIPS certified.  The use of the TPM RNG was a deliberate
> design choice in trusted keys.

Hmm... so is RDRAND opcode FIPS certified.

Kernel has the random number generator for two reasons:

1. To protect against bugs in hwrng's.
2. To protect against deliberate backdoors in hwrng's.

How TPM RNG is guaranteed to protect against both 1 and 2?

If I would agree what you say, that'd be argument against using kernel
random number generator *anywhere* in the kernel. Even with the entropy
issues it is least worst thing to use for key generations for better
or worse.

/Jarkko

  reply	other threads:[~2019-10-07  0:05 UTC|newest]

Thread overview: 58+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-09-26 17:16 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
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 [this message]
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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