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Subject: Re: [PATCH v6 3/6] KEYS: trusted: Introduce NXP DCP-backed trusted
 keys
From: David Gstir <david@sigma-star.at>
In-Reply-To: <CZNRMR5YZPQO.1QBLW62A6S840@kernel.org>
Date: Fri, 8 Mar 2024 08:17:35 +0100
Cc: Mimi Zohar <zohar@linux.ibm.com>,
 James Bottomley <jejb@linux.ibm.com>,
 Herbert Xu <herbert@gondor.apana.org.au>,
 "David S. Miller" <davem@davemloft.net>,
 Shawn Guo <shawnguo@kernel.org>,
 Jonathan Corbet <corbet@lwn.net>,
 Sascha Hauer <s.hauer@pengutronix.de>,
 "kernel@pengutronix.de" <kernel@pengutronix.de>,
 Fabio Estevam <festevam@gmail.com>,
 NXP Linux Team <linux-imx@nxp.com>,
 Ahmad Fatoum <a.fatoum@pengutronix.de>,
 sigma star Kernel Team <upstream+dcp@sigma-star.at>,
 David Howells <dhowells@redhat.com>,
 Li Yang <leoyang.li@nxp.com>,
 Paul Moore <paul@paul-moore.com>,
 James Morris <jmorris@namei.org>,
 "Serge E. Hallyn" <serge@hallyn.com>,
 "Paul E. McKenney" <paulmck@kernel.org>,
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 Catalin Marinas <catalin.marinas@arm.com>,
 "Rafael J. Wysocki" <rafael.j.wysocki@intel.com>,
 Tejun Heo <tj@kernel.org>,
 "Steven Rostedt (Google)" <rostedt@goodmis.org>,
 linux-doc@vger.kernel.org,
 "linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
 "linux-integrity@vger.kernel.org" <linux-integrity@vger.kernel.org>,
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 "linux-security-module@vger.kernel.org" <linux-security-module@vger.kernel.org>,
 Richard Weinberger <richard@nod.at>,
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References: <20240307153842.80033-1-david@sigma-star.at>
 <20240307153842.80033-4-david@sigma-star.at>
 <CZNRMR5YZPQO.1QBLW62A6S840@kernel.org>
To: Jarkko Sakkinen <jarkko@kernel.org>

Hi Jarkko,

> On 07.03.2024, at 20:30, Jarkko Sakkinen <jarkko@kernel.org> wrote:

[...]

>> +
>> +static int trusted_dcp_init(void)
>> +{
>> + int ret;
>> +
>> + if (use_otp_key)
>> + pr_info("Using DCP OTP key\n");
>> +
>> + ret =3D test_for_zero_key();
>> + if (ret) {
>> + pr_err("Test for zero'ed keys failed: %i\n", ret);
>=20
> I'm not sure whether this should err or warn.
>=20
> What sort of situations can cause the test the fail (e.g.
> adversary/interposer, bad configuration etc.).

This occurs when the hardware is not in "secure mode". I.e. it=E2=80=99s =
a bad configuration issue.
Once the board is properly configured, this will never trigger again.
Do you think a warning is better for this then?

Thanks,
- David