From: Jarkko Sakkinen <jarkko@kernel.org>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: "Sumit Garg" <sumit.garg@linaro.org>,
"James Bottomley" <jejb@linux.ibm.com>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"David Howells" <dhowells@redhat.com>,
kernel <kernel@pengutronix.de>,
"James Morris" <jmorris@namei.org>,
"Serge E. Hallyn" <serge@hallyn.com>,
"Horia Geantă" <horia.geanta@nxp.com>,
"Aymen Sghaier" <aymen.sghaier@nxp.com>,
"Herbert Xu" <herbert@gondor.apana.org.au>,
"David S. Miller" <davem@davemloft.net>,
"Udit Agarwal" <udit.agarwal@nxp.com>,
"Eric Biggers" <ebiggers@kernel.org>,
"Jan Luebbe" <j.luebbe@pengutronix.de>,
"David Gstir" <david@sigma-star.at>,
"Richard Weinberger" <richard@nod.at>,
"Franck LENORMAND" <franck.lenormand@nxp.com>,
"open list:ASYMMETRIC KEYS" <keyrings@vger.kernel.org>,
"open list:HARDWARE RANDOM NUMBER GENERATOR CORE"
<linux-crypto@vger.kernel.org>,
linux-integrity <linux-integrity@vger.kernel.org>,
"Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>,
"open list:SECURITY SUBSYSTEM"
<linux-security-module@vger.kernel.org>
Subject: Re: [PATCH 2/4] KEYS: trusted: allow trust sources to use kernel RNG for key material
Date: Mon, 9 Aug 2021 12:56:47 +0300 [thread overview]
Message-ID: <20210809095647.7xcxjeot5gyvmlpj@kernel.org> (raw)
In-Reply-To: <7537c853-3641-a6d3-91d8-70fea9f01a89@pengutronix.de>
On Mon, Aug 09, 2021 at 09:52:20AM +0200, Ahmad Fatoum wrote:
> Hello Sumit,
>
> On 22.07.21 08:31, Sumit Garg wrote:
> > On Wed, 21 Jul 2021 at 22:19, Ahmad Fatoum <a.fatoum@pengutronix.de> wrote:
> >>
> >> The two existing trusted key sources don't make use of the kernel RNG,
> >> but instead let the hardware that does the sealing/unsealing also
> >> generate the random key material. While a previous change offers users
> >> the choice to use the kernel RNG instead for both, new trust sources
> >> may want to unconditionally use the kernel RNG for generating key
> >> material, like it's done elsewhere in the kernel.
> >>
> >> This is especially prudent for hardware that has proven-in-production
> >> HWRNG drivers implemented, as otherwise code would have to be duplicated
> >> only to arrive at a possibly worse result.
> >>
> >> Make this possible by turning struct trusted_key_ops::get_random
> >> into an optional member. If a driver leaves it NULL, kernel RNG
> >> will be used instead.
> >>
> >> Signed-off-by: Ahmad Fatoum <a.fatoum@pengutronix.de>
> >> ---
> >> To: James Bottomley <jejb@linux.ibm.com>
> >> To: Jarkko Sakkinen <jarkko@kernel.org>
> >> To: Mimi Zohar <zohar@linux.ibm.com>
> >> To: David Howells <dhowells@redhat.com>
> >> Cc: James Morris <jmorris@namei.org>
> >> Cc: "Serge E. Hallyn" <serge@hallyn.com>
> >> Cc: "Horia Geantă" <horia.geanta@nxp.com>
> >> Cc: Aymen Sghaier <aymen.sghaier@nxp.com>
> >> Cc: Herbert Xu <herbert@gondor.apana.org.au>
> >> Cc: "David S. Miller" <davem@davemloft.net>
> >> Cc: Udit Agarwal <udit.agarwal@nxp.com>
> >> Cc: Eric Biggers <ebiggers@kernel.org>
> >> Cc: Jan Luebbe <j.luebbe@pengutronix.de>
> >> Cc: David Gstir <david@sigma-star.at>
> >> Cc: Richard Weinberger <richard@nod.at>
> >> Cc: Franck LENORMAND <franck.lenormand@nxp.com>
> >> Cc: Sumit Garg <sumit.garg@linaro.org>
> >> Cc: keyrings@vger.kernel.org
> >> Cc: linux-crypto@vger.kernel.org
> >> Cc: linux-integrity@vger.kernel.org
> >> Cc: linux-kernel@vger.kernel.org
> >> Cc: linux-security-module@vger.kernel.org
> >> ---
> >> include/keys/trusted-type.h | 2 +-
> >> security/keys/trusted-keys/trusted_core.c | 2 +-
> >> 2 files changed, 2 insertions(+), 2 deletions(-)
> >>
> >> diff --git a/include/keys/trusted-type.h b/include/keys/trusted-type.h
> >> index d89fa2579ac0..4eb64548a74f 100644
> >> --- a/include/keys/trusted-type.h
> >> +++ b/include/keys/trusted-type.h
> >> @@ -64,7 +64,7 @@ struct trusted_key_ops {
> >> /* Unseal a key. */
> >> int (*unseal)(struct trusted_key_payload *p, char *datablob);
> >>
> >> - /* Get a randomized key. */
> >> + /* Optional: Get a randomized key. */
> >> int (*get_random)(unsigned char *key, size_t key_len);
> >>
> >> /* Exit key interface. */
> >> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> >> index 569af9af8df0..d2b7626cde8b 100644
> >> --- a/security/keys/trusted-keys/trusted_core.c
> >> +++ b/security/keys/trusted-keys/trusted_core.c
> >> @@ -334,7 +334,7 @@ static int __init init_trusted(void)
> >> continue;
> >>
> >> get_random = trusted_key_sources[i].ops->get_random;
> >> - if (trusted_kernel_rng)
> >> + if (trusted_kernel_rng || !get_random)
> >> get_random = kernel_get_random;
> >>
> >
> > For ease of understanding, I would prefer to write it as:
> >
> > get_random = trusted_key_sources[i].ops->get_random ?:
> > kernel_get_random;
> > if (trusted_kernel_rng)
> > get_random = kernel_get_random;
> >
> > With that:
> >
> > Acked-by: Sumit Garg <sumit.garg@linaro.org>
>
> I don't think it improves readability to split up the conditional.
> At least I need to take a second pass over the code to understand
> the second conditional.
Ternary operators are pain to read, unless a super trivial case.
I'd stick to what you did.
/Jarkko
next prev parent reply other threads:[~2021-08-09 9:56 UTC|newest]
Thread overview: 28+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-07-21 16:48 [PATCH 0/4] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-07-21 16:48 ` [PATCH 1/4] KEYS: trusted: allow users to use kernel RNG for key material Ahmad Fatoum
2021-07-22 6:17 ` Sumit Garg
2021-07-21 16:48 ` [PATCH 2/4] KEYS: trusted: allow trust sources " Ahmad Fatoum
2021-07-22 6:31 ` Sumit Garg
2021-08-09 7:52 ` Ahmad Fatoum
2021-08-09 9:56 ` Jarkko Sakkinen [this message]
2021-08-10 5:24 ` Sumit Garg
2021-07-21 16:48 ` [PATCH 3/4] crypto: caam - add in-kernel interface for blob generator Ahmad Fatoum
2021-08-10 11:29 ` David Gstir
2021-08-11 10:22 ` Ahmad Fatoum
2021-08-11 10:43 ` David Gstir
2021-07-21 16:48 ` [PATCH 4/4] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-08-06 15:12 ` [PATCH 0/4] " Ahmad Fatoum
2021-08-09 9:35 ` Jarkko Sakkinen
2021-08-09 10:16 ` Ahmad Fatoum
2021-08-10 11:28 ` David Gstir
2021-08-20 16:25 ` Ahmad Fatoum
2021-08-20 15:39 ` Tim Harvey
2021-08-20 16:19 ` Ahmad Fatoum
2021-08-20 20:20 ` Tim Harvey
2021-08-20 20:36 ` Ahmad Fatoum
2021-08-20 21:19 ` Tim Harvey
2021-08-23 13:29 ` Ahmad Fatoum
2021-08-23 17:50 ` Tim Harvey
2021-08-24 7:33 ` Ahmad Fatoum
2021-08-24 15:23 ` Tim Harvey
2021-08-25 9:34 ` Ahmad Fatoum
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