linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Sumit Garg <sumit.garg@linaro.org>
To: Ahmad Fatoum <a.fatoum@pengutronix.de>
Cc: "James Bottomley" <jejb@linux.ibm.com>,
	"Jarkko Sakkinen" <jarkko@kernel.org>,
	"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>,
	"Jan Luebbe" <j.luebbe@pengutronix.de>,
	"Eric Biggers" <ebiggers@kernel.org>,
	"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 1/4] KEYS: trusted: allow users to use kernel RNG for key material
Date: Thu, 22 Jul 2021 11:47:40 +0530	[thread overview]
Message-ID: <CAFA6WYOjXtFtVgviZtdGhf_MpTP6AQrtaPfju0AwEAYMDL=5hQ@mail.gmail.com> (raw)
In-Reply-To: <3b93fda0155af1a8776e9cc9984ecdb39ce827e4.1626885907.git-series.a.fatoum@pengutronix.de>

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 doing the sealing/unsealing also
> generate the random key material. However, Users may want to place
> 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>
> 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(-)
>

Sounds like a reasonable approach to me.

Acked-by: Sumit Garg <sumit.garg@linaro.org>

-Sumit

> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index bdb22006f713..0267ead88902 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -5734,6 +5734,13 @@
>                         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");
> +
>  static char *trusted_key_source;
>  module_param_named(source, trusted_key_source, charp, 0);
>  MODULE_PARM_DESC(source, "Select trusted keys source (tpm or tee)");
> @@ -312,8 +317,14 @@ struct key_type key_type_trusted = {
>  };
>  EXPORT_SYMBOL_GPL(key_type_trusted);
>
> +static int kernel_get_random(unsigned char *key, size_t key_len)
> +{
> +       return get_random_bytes_wait(key, key_len) ?: key_len;
> +}
> +
>  static int __init init_trusted(void)
>  {
> +       int (*get_random)(unsigned char *key, size_t key_len);
>         int i, ret = 0;
>
>         for (i = 0; i < ARRAY_SIZE(trusted_key_sources); i++) {
> @@ -322,6 +333,10 @@ static int __init init_trusted(void)
>                             strlen(trusted_key_sources[i].name)))
>                         continue;
>
> +               get_random = trusted_key_sources[i].ops->get_random;
> +               if (trusted_kernel_rng)
> +                       get_random = kernel_get_random;
> +
>                 static_call_update(trusted_key_init,
>                                    trusted_key_sources[i].ops->init);
>                 static_call_update(trusted_key_seal,
> @@ -329,7 +344,7 @@ static int __init init_trusted(void)
>                 static_call_update(trusted_key_unseal,
>                                    trusted_key_sources[i].ops->unseal);
>                 static_call_update(trusted_key_get_random,
> -                                  trusted_key_sources[i].ops->get_random);
> +                                  get_random);
>                 static_call_update(trusted_key_exit,
>                                    trusted_key_sources[i].ops->exit);
>                 migratable = trusted_key_sources[i].ops->migratable;
> --
> git-series 0.9.1

  reply	other threads:[~2021-07-22  6:18 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 [this message]
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
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

Reply instructions:

You may reply publicly to this message via plain-text email
using any one of the following methods:

* Save the following mbox file, import it into your mail client,
  and reply-to-all from there: mbox

  Avoid top-posting and favor interleaved quoting:
  https://en.wikipedia.org/wiki/Posting_style#Interleaved_style

* Reply using the --to, --cc, and --in-reply-to
  switches of git-send-email(1):

  git send-email \
    --in-reply-to='CAFA6WYOjXtFtVgviZtdGhf_MpTP6AQrtaPfju0AwEAYMDL=5hQ@mail.gmail.com' \
    --to=sumit.garg@linaro.org \
    --cc=a.fatoum@pengutronix.de \
    --cc=aymen.sghaier@nxp.com \
    --cc=davem@davemloft.net \
    --cc=david@sigma-star.at \
    --cc=dhowells@redhat.com \
    --cc=ebiggers@kernel.org \
    --cc=franck.lenormand@nxp.com \
    --cc=herbert@gondor.apana.org.au \
    --cc=horia.geanta@nxp.com \
    --cc=j.luebbe@pengutronix.de \
    --cc=jarkko@kernel.org \
    --cc=jejb@linux.ibm.com \
    --cc=jmorris@namei.org \
    --cc=kernel@pengutronix.de \
    --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 \
    --cc=richard@nod.at \
    --cc=serge@hallyn.com \
    --cc=udit.agarwal@nxp.com \
    --cc=zohar@linux.ibm.com \
    --subject='Re: [PATCH 1/4] KEYS: trusted: allow users to use kernel RNG for key material' \
    /path/to/YOUR_REPLY

  https://kernel.org/pub/software/scm/git/docs/git-send-email.html

* If your mail client supports setting the In-Reply-To header
  via mailto: links, try the mailto: link

This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).