linux-kernel - Re: [PATCH v3 01/14] integrity: Introduce a Linux keyring for the Machine Owner Key (MOK)

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Date:   Thu, 12 Aug 2021 21:58:53 +0300
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     keyrings@...r.kernel.org, linux-integrity@...r.kernel.org,
        zohar@...ux.ibm.com, dhowells@...hat.com, dwmw2@...radead.org,
        herbert@...dor.apana.org.au, davem@...emloft.net,
        jmorris@...ei.org, serge@...lyn.com, keescook@...omium.org,
        gregkh@...uxfoundation.org, torvalds@...ux-foundation.org,
        scott.branden@...adcom.com, weiyongjun1@...wei.com,
        nayna@...ux.ibm.com, ebiggers@...gle.com, ardb@...nel.org,
        nramas@...ux.microsoft.com, lszubowi@...hat.com,
        linux-kernel@...r.kernel.org, linux-crypto@...r.kernel.org,
        linux-security-module@...r.kernel.org,
        James.Bottomley@...senpartnership.com, pjones@...hat.com,
        glin@...e.com, konrad.wilk@...cle.com
Subject: Re: [PATCH v3 01/14] integrity: Introduce a Linux keyring for the
 Machine Owner Key (MOK)

On Wed, Aug 11, 2021 at 10:18:42PM -0400, Eric Snowberg wrote:
> Many UEFI Linux distributions boot using shim.  The UEFI shim provides
> what is called Machine Owner Keys (MOK). Shim uses both the UEFI Secure
> Boot DB and MOK keys to validate the next step in the boot chain.  The
> MOK facility can be used to import user generated keys.  These keys can
> be used to sign an end-users development kernel build.  When Linux
> boots, both UEFI Secure Boot DB and MOK keys get loaded in the Linux
> .platform keyring.
> 
> Add a new Linux keyring called .mok.  This keyring shall contain just

I would consider ".machine" instead. It holds MOK keys but is not a
MOK key.

> MOK keys and not the remaining keys in the platform keyring. This new
> .mok keyring will be used in follow on patches.  Unlike keys in the
> platform keyring, keys contained in the .mok keyring will be trusted
> within the kernel if the end-user has chosen to do so.
> 
> Signed-off-by: Eric Snowberg <eric.snowberg@...cle.com>
> ---
> v1: Initial version
> v2: Removed destory keyring code
> v3: Unmodified from v2
> ---
>  security/integrity/Makefile                   |  3 ++-
>  security/integrity/digsig.c                   |  1 +
>  security/integrity/integrity.h                |  3 ++-
>  .../integrity/platform_certs/mok_keyring.c    | 21 +++++++++++++++++++
>  4 files changed, 26 insertions(+), 2 deletions(-)
>  create mode 100644 security/integrity/platform_certs/mok_keyring.c
> 
> diff --git a/security/integrity/Makefile b/security/integrity/Makefile
> index 7ee39d66cf16..8e2e98cba1f6 100644
> --- a/security/integrity/Makefile
> +++ b/security/integrity/Makefile
> @@ -9,7 +9,8 @@ integrity-y := iint.o
>  integrity-$(CONFIG_INTEGRITY_AUDIT) += integrity_audit.o
>  integrity-$(CONFIG_INTEGRITY_SIGNATURE) += digsig.o
>  integrity-$(CONFIG_INTEGRITY_ASYMMETRIC_KEYS) += digsig_asymmetric.o
> -integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o
> +integrity-$(CONFIG_INTEGRITY_PLATFORM_KEYRING) += platform_certs/platform_keyring.o \
> +						  platform_certs/mok_keyring.o
>  integrity-$(CONFIG_LOAD_UEFI_KEYS) += platform_certs/efi_parser.o \
>  				      platform_certs/load_uefi.o \
>  				      platform_certs/keyring_handler.o
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index 3b06a01bd0fd..e07334504ef1 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -30,6 +30,7 @@ static const char * const keyring_name[INTEGRITY_KEYRING_MAX] = {
>  	".ima",
>  #endif
>  	".platform",
> +	".mok",
>  };
>  
>  #ifdef CONFIG_IMA_KEYRINGS_PERMIT_SIGNED_BY_BUILTIN_OR_SECONDARY
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index 547425c20e11..e0e17ccba2e6 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -151,7 +151,8 @@ int integrity_kernel_read(struct file *file, loff_t offset,
>  #define INTEGRITY_KEYRING_EVM		0
>  #define INTEGRITY_KEYRING_IMA		1
>  #define INTEGRITY_KEYRING_PLATFORM	2
> -#define INTEGRITY_KEYRING_MAX		3
> +#define INTEGRITY_KEYRING_MOK		3
> +#define INTEGRITY_KEYRING_MAX		4
>  
>  extern struct dentry *integrity_dir;
>  
> diff --git a/security/integrity/platform_certs/mok_keyring.c b/security/integrity/platform_certs/mok_keyring.c
> new file mode 100644
> index 000000000000..b1ee45b77731
> --- /dev/null
> +++ b/security/integrity/platform_certs/mok_keyring.c
> @@ -0,0 +1,21 @@
> +// SPDX-License-Identifier: GPL-2.0
> +/*
> + * MOK keyring routines.
> + *
> + * Copyright (c) 2021, Oracle and/or its affiliates.
> + */
> +
> +#include "../integrity.h"
> +
> +static __init int mok_keyring_init(void)
> +{
> +	int rc;
> +
> +	rc = integrity_init_keyring(INTEGRITY_KEYRING_MOK);
> +	if (rc)
> +		return rc;
> +
> +	pr_notice("MOK Keyring initialized\n");
> +	return 0;
> +}
> +device_initcall(mok_keyring_init);
> -- 
> 2.18.4
> 
> 

/Jarkko