From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=unavailable autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66BCBC63799 for ; Thu, 22 Jul 2021 06:18:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3950761283 for ; Thu, 22 Jul 2021 06:18:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231169AbhGVFhU (ORCPT ); Thu, 22 Jul 2021 01:37:20 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45988 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230500AbhGVFhT (ORCPT ); Thu, 22 Jul 2021 01:37:19 -0400 Received: from mail-lf1-x12d.google.com (mail-lf1-x12d.google.com [IPv6:2a00:1450:4864:20::12d]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id C3AD1C061575 for ; Wed, 21 Jul 2021 23:17:53 -0700 (PDT) Received: by mail-lf1-x12d.google.com with SMTP id s13so6770094lfi.12 for ; Wed, 21 Jul 2021 23:17:53 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linaro.org; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc:content-transfer-encoding; bh=WORoTGHF102QmcPLJnYL0wl9JDz1GesGd0P0NJ/o4VY=; b=IHTNNSIGRh52lvqCaFt1jBoEW1/opFfVCgkb3Ln7p1RrwsNMrPogYpKHKMMe9ZTH+C Uqjx6nU7X5lHZNtAN8gMsvTGS201uow8OyfcWgp3zzsVPXuTzeQpm/UUdNedfMCXntId ISSOQCRoPSssGaJBTa/LKtraNnxMiWYjk1SRg0Ft+x4aBgzji4CD9BwNRrQfp8pKGSLO WdWy5q3j5ewpdwNwB52IwOcvRn3Zx1KZPg6I/AEg7XnE8o4p8/Mkjd9UR493w0QTtIa4 kFIPi3a4t4xPHnCcYC3hZhRtGpszwAFy+MWqjWqxpfsP7PHayUf1qyhDTjG3I54knlkp WyRw== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc:content-transfer-encoding; bh=WORoTGHF102QmcPLJnYL0wl9JDz1GesGd0P0NJ/o4VY=; b=OfaHTSsPttsIOwi6MvgAvywubOoV6/+9d237wtXcuyhVYTkw9FXhp5G3pCOr2CYwTx kRoeHOFpxCe3mofMx21Yn8crV1JemdomviHcTo0M+2RdrYoTrooIYMvQvK0/y5QTLq3I 0sWluCpe/bj1Y+0LDDlSQoV62beo9cXzPSbtYW0OilNJwNEpj+cIxGGSZrdEnINMB9La QY25FoGN69vwbZZdnAXC3HPsheqdm72fEhId0lK3/Aikcl+dGNpwsX2Sj5BBYE3mXVEI IwJRSQ8HUfrj+PknujjdzRR7E5ZJvdpZHMhQct4C5mxEN+fMo63JjnBstsM+zmnOiw4O YCRQ== X-Gm-Message-State: AOAM531qY/Q5oc/TeVLx5MYw3c37mwQFldLe+Y71RhfMNbllToAf61+5 e7T/9BYt2OsiHMX4ZsMJg3ZKBQAzFG5Bbx1FVJfdxQ== X-Google-Smtp-Source: ABdhPJxwqkYYSDj6ayPNqBy3Xzy0MH1wQFA8Q/nRMaU5NRIQDMZn4xDFUsJiqwUgCaiyv5WVxn3f5GLhYq4kN7GFzj4= X-Received: by 2002:a19:6e0d:: with SMTP id j13mr27727553lfc.108.1626934672014; Wed, 21 Jul 2021 23:17:52 -0700 (PDT) MIME-Version: 1.0 References: <3b93fda0155af1a8776e9cc9984ecdb39ce827e4.1626885907.git-series.a.fatoum@pengutronix.de> In-Reply-To: <3b93fda0155af1a8776e9cc9984ecdb39ce827e4.1626885907.git-series.a.fatoum@pengutronix.de> From: Sumit Garg Date: Thu, 22 Jul 2021 11:47:40 +0530 Message-ID: Subject: Re: [PATCH 1/4] KEYS: trusted: allow users to use kernel RNG for key material To: Ahmad Fatoum Cc: James Bottomley , Jarkko Sakkinen , Mimi Zohar , David Howells , kernel , James Morris , "Serge E. Hallyn" , =?UTF-8?Q?Horia_Geant=C4=83?= , Aymen Sghaier , Herbert Xu , "David S. Miller" , Udit Agarwal , Jan Luebbe , Eric Biggers , David Gstir , Richard Weinberger , Franck LENORMAND , "open list:ASYMMETRIC KEYS" , "open list:HARDWARE RANDOM NUMBER GENERATOR CORE" , linux-integrity , Linux Kernel Mailing List , "open list:SECURITY SUBSYSTEM" Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: quoted-printable Precedence: bulk List-ID: X-Mailing-List: keyrings@vger.kernel.org On Wed, 21 Jul 2021 at 22:19, 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 > 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 > Signed-off-by: Ahmad Fatoum > --- > To: James Bottomley > To: Jarkko Sakkinen > To: Mimi Zohar > To: David Howells > Cc: James Morris > Cc: "Serge E. Hallyn" > Cc: "Horia Geant=C4=83" > Cc: Aymen Sghaier > Cc: Herbert Xu > Cc: "David S. Miller" > Cc: Udit Agarwal > Cc: Jan Luebbe > Cc: Eric Biggers > Cc: David Gstir > Cc: Richard Weinberger > Cc: Franck LENORMAND > Cc: Sumit Garg > 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 > diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentat= ion/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 initiali= zed > successfully during iteration. > > + trusted.kernel_rng =3D [KEYS] > + Format: > + When set to true (1), the kernel random number po= ol > + is used to generate key material for trusted keys= . > + The default is to leave the RNG's choice to each > + individual trust source. > + > tsc=3D Disable clocksource stability checks for TSC. > Format: > [x86] reliable: mark tsc clocksource as reliable,= this > diff --git a/Documentation/security/keys/trusted-encrypted.rst b/Document= ation/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 u= sing > +a child key in the storage key hierarchy. Encryption and decryption of t= he > +child key must be protected by a strong access control policy within the > +trust source. The random number generator in use differs according to th= e > +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 v= ary > + 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 CSP= RNG > which can be seeded via multiple entropy sources. > > +Optionally, users may specify ``trusted.kernel_rng=3D1`` on the kernel > +command-line to override the used RNG with the kernel's random number po= ol. > + > Encrypted Keys > -------------- > > diff --git a/security/keys/trusted-keys/trusted_core.c b/security/keys/tr= usted-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 > #include > #include > +#include > #include > #include > #include > #include > #include > > +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 =3D { > }; > 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 =3D 0; > > for (i =3D 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 =3D trusted_key_sources[i].ops->get_random; > + if (trusted_kernel_rng) > + get_random =3D 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 =3D trusted_key_sources[i].ops->migratable; > -- > git-series 0.9.1