From: Jarkko Sakkinen <jarkko@kernel.org>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: "James Bottomley" <jejb@linux.ibm.com>,
"Mimi Zohar" <zohar@linux.ibm.com>,
"David Howells" <dhowells@redhat.com>,
kernel@pengutronix.de, "Sumit Garg" <sumit.garg@linaro.org>,
"David Gstir" <david@sigma-star.at>,
"Tim Harvey" <tharvey@gateworks.com>,
"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>,
"Jan Luebbe" <j.luebbe@pengutronix.de>,
"Eric Biggers" <ebiggers@kernel.org>,
"Richard Weinberger" <richard@nod.at>,
"Franck LENORMAND" <franck.lenormand@nxp.com>,
keyrings@vger.kernel.org, linux-crypto@vger.kernel.org,
linux-integrity@vger.kernel.org, linux-kernel@vger.kernel.org,
linux-security-module@vger.kernel.org
Subject: Re: [PATCH v4 2/5] KEYS: trusted: allow users to use kernel RNG for key material
Date: Sun, 5 Dec 2021 02:16:49 +0200 [thread overview]
Message-ID: <YawE8cQ2SZjxqWUo@iki.fi> (raw)
In-Reply-To: <9bd8c969d5c656825a35aab6fb0725282a8a62cc.1633946449.git-series.a.fatoum@pengutronix.de>
On Mon, Oct 11, 2021 at 12:02:35PM +0200, Ahmad Fatoum wrote:
> The two existing trusted key sources don't make use of the kernel RNG,
> but instead let the hardware doing the sealing/unsealing also
> generate the random key material. However, Users may want to place
"Users" -> "users"
> less trust into the quality of the trust source's random number
> generator and instead use the kernel entropy pool, which can be
> seeded from multiple entropy sources.
>
> Make this possible by adding a new trusted.kernel_rng parameter,
> that will force use of the kernel RNG. In its absence, it's up
> to the trust source to decide, which random numbers to use,
> maintaining the existing behavior.
>
> Suggested-by: Jarkko Sakkinen <jarkko@kernel.org>
> Acked-by: Sumit Garg <sumit.garg@linaro.org>
> Reviewed-by: David Gstir <david@sigma-star.at>
> Tested-By: Tim Harvey <tharvey@gateworks.com>
> 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: Jan Luebbe <j.luebbe@pengutronix.de>
> Cc: Eric Biggers <ebiggers@kernel.org>
> 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
> ---
> Documentation/admin-guide/kernel-parameters.txt | 7 ++++++-
> Documentation/security/keys/trusted-encrypted.rst | 20 +++++++++-------
> security/keys/trusted-keys/trusted_core.c | 17 +++++++++++++-
> 3 files changed, 35 insertions(+), 9 deletions(-)
>
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index 43dc35fe5bc0..d5969452f063 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5772,6 +5772,13 @@
> first trust source as a backend which is initialized
> successfully during iteration.
>
> + trusted.kernel_rng = [KEYS]
> + Format: <bool>
> + When set to true (1), the kernel random number pool
> + is used to generate key material for trusted keys.
> + The default is to leave the RNG's choice to each
> + individual trust source.
> +
> tsc= Disable clocksource stability checks for TSC.
> Format: <string>
> [x86] reliable: mark tsc clocksource as reliable, this
> diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Documentation/security/keys/trusted-encrypted.rst
> index 80d5a5af62a1..1d4b4b8f12f0 100644
> --- a/Documentation/security/keys/trusted-encrypted.rst
> +++ b/Documentation/security/keys/trusted-encrypted.rst
> @@ -87,22 +87,26 @@ Key Generation
> Trusted Keys
> ------------
>
> -New keys are created from random numbers generated in the trust source. They
> -are encrypted/decrypted using a child key in the storage key hierarchy.
> -Encryption and decryption of the child key must be protected by a strong
> -access control policy within the trust source.
> +New keys are created from random numbers. They are encrypted/decrypted using
> +a child key in the storage key hierarchy. Encryption and decryption of the
> +child key must be protected by a strong access control policy within the
> +trust source. The random number generator in use differs according to the
> +selected trust source:
>
> - * TPM (hardware device) based RNG
> + * TPM: hardware device based RNG
>
> - Strength of random numbers may vary from one device manufacturer to
> - another.
> + Keys are generated within the TPM. Strength of random numbers may vary
> + from one device manufacturer to another.
>
> - * TEE (OP-TEE based on Arm TrustZone) based RNG
> + * TEE: OP-TEE based on Arm TrustZone based RNG
>
> RNG is customizable as per platform needs. It can either be direct output
> from platform specific hardware RNG or a software based Fortuna CSPRNG
> which can be seeded via multiple entropy sources.
>
> +Optionally, users may specify ``trusted.kernel_rng=1`` on the kernel
> +command-line to override the used RNG with the kernel's random number pool.
> +
> Encrypted Keys
> --------------
>
> diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/trusted-keys/trusted_core.c
> index 8cab69e5d0da..569af9af8df0 100644
> --- a/security/keys/trusted-keys/trusted_core.c
> +++ b/security/keys/trusted-keys/trusted_core.c
> @@ -16,12 +16,17 @@
> #include <linux/key-type.h>
> #include <linux/module.h>
> #include <linux/parser.h>
> +#include <linux/random.h>
> #include <linux/rcupdate.h>
> #include <linux/slab.h>
> #include <linux/static_call.h>
> #include <linux/string.h>
> #include <linux/uaccess.h>
>
> +static bool trusted_kernel_rng;
> +module_param_named(kernel_rng, trusted_kernel_rng, bool, 0);
> +MODULE_PARM_DESC(kernel_rng, "Generate key material from kernel RNG");
It's not then always kernel RNG, i.e. that is a very misleading name.
I'd prefer trusted_rng with string values "kernel", "tee". That makes
it explicit what you are using.
/Jarkko
next prev parent reply other threads:[~2021-12-05 0:16 UTC|newest]
Thread overview: 21+ messages / expand[flat|nested] mbox.gz Atom feed top
2021-10-11 10:02 [PATCH v4 0/5] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-10-11 10:02 ` [PATCH v4 1/5] KEYS: trusted: allow use of TEE as backend without TCG_TPM support Ahmad Fatoum
2021-12-05 0:12 ` Jarkko Sakkinen
2021-10-11 10:02 ` [PATCH v4 2/5] KEYS: trusted: allow users to use kernel RNG for key material Ahmad Fatoum
2021-12-05 0:16 ` Jarkko Sakkinen [this message]
2021-12-13 10:29 ` Ahmad Fatoum
2021-12-23 7:25 ` [EXT] " Pankaj Gupta
2021-10-11 10:02 ` [PATCH v4 3/5] KEYS: trusted: allow trust sources " Ahmad Fatoum
2021-10-11 10:02 ` [PATCH v4 4/5] crypto: caam - add in-kernel interface for blob generator Ahmad Fatoum
2021-11-01 8:00 ` Ahmad Fatoum
2021-11-24 7:48 ` Ahmad Fatoum
2021-12-05 0:18 ` Jarkko Sakkinen
2021-12-13 10:34 ` Ahmad Fatoum
2021-12-23 7:20 ` [EXT] " Pankaj Gupta (OSS)
2021-10-11 10:02 ` [PATCH v4 5/5] KEYS: trusted: Introduce support for NXP CAAM-based trusted keys Ahmad Fatoum
2021-11-24 7:53 ` Ahmad Fatoum
2021-12-13 11:00 ` Matthias Schiffer
2021-12-13 11:36 ` Ahmad Fatoum
2021-12-13 13:40 ` Matthias Schiffer
2022-02-22 4:30 ` [EXT] " Pankaj Gupta
2022-02-22 11:24 ` Ahmad Fatoum
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