linux-kernel - Re: [PATCH v9 3/8] integrity: add new keyring handler for mok keys

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Date:   Sun, 9 Jan 2022 00:21:31 +0200
From:   Jarkko Sakkinen <jarkko@...nel.org>
To:     Eric Snowberg <eric.snowberg@...cle.com>
Cc:     dhowells@...hat.com, dwmw2@...radead.org, ardb@...nel.org,
        jmorris@...ei.org, serge@...lyn.com, nayna@...ux.ibm.com,
        zohar@...ux.ibm.com, keescook@...omium.org,
        torvalds@...ux-foundation.org, weiyongjun1@...wei.com,
        keyrings@...r.kernel.org, linux-kernel@...r.kernel.org,
        linux-efi@...r.kernel.org, linux-security-module@...r.kernel.org,
        James.Bottomley@...senpartnership.com, pjones@...hat.com,
        konrad.wilk@...cle.com
Subject: Re: [PATCH v9 3/8] integrity: add new keyring handler for mok keys

On Wed, Jan 05, 2022 at 06:50:07PM -0500, Eric Snowberg wrote:
> Currently both Secure Boot DB and Machine Owner Keys (MOK) go through
> the same keyring handler (get_handler_for_db). With the addition of the
> new machine keyring, the end-user may choose to trust MOK keys.
> 
> Introduce a new keyring handler specific for MOK keys.  If MOK keys are
> trusted by the end-user, use the new keyring handler instead.
> 
> Signed-off-by: Eric Snowberg <eric.snowberg@...cle.com>
> Reviewed-by: Mimi Zohar <zohar@...ux.ibm.com>
> ---
> v1: Initial version
> v3: Only change the keyring handler if the secondary is enabled
> v4: Removed trust_moklist check
> v5: Rename to machine keyring
> v7: Unmodified from v5
> v8: Code unmodified from v7 added Mimi's Reviewed-by
> v9: Unmodified from v8
> ---
>  .../integrity/platform_certs/keyring_handler.c  | 17 ++++++++++++++++-
>  .../integrity/platform_certs/keyring_handler.h  |  5 +++++
>  security/integrity/platform_certs/load_uefi.c   |  4 ++--
>  3 files changed, 23 insertions(+), 3 deletions(-)
> 
> diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c
> index e9791be98fd9..4872850d081f 100644
> --- a/security/integrity/platform_certs/keyring_handler.c
> +++ b/security/integrity/platform_certs/keyring_handler.c
> @@ -67,7 +67,7 @@ static __init void uefi_revocation_list_x509(const char *source,
>  
>  /*
>   * Return the appropriate handler for particular signature list types found in
> - * the UEFI db and MokListRT tables.
> + * the UEFI db tables.
>   */
>  __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
>  {
> @@ -76,6 +76,21 @@ __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
>  	return 0;
>  }
>  
> +/*
> + * Return the appropriate handler for particular signature list types found in
> + * the MokListRT tables.
> + */
> +__init efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type)
> +{
> +	if (efi_guidcmp(*sig_type, efi_cert_x509_guid) == 0) {
> +		if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING))
> +			return add_to_machine_keyring;
> +		else
> +			return add_to_platform_keyring;
> +	}
> +	return 0;
> +}
> +
>  /*
>   * Return the appropriate handler for particular signature list types found in
>   * the UEFI dbx and MokListXRT tables.
> diff --git a/security/integrity/platform_certs/keyring_handler.h b/security/integrity/platform_certs/keyring_handler.h
> index 2462bfa08fe3..284558f30411 100644
> --- a/security/integrity/platform_certs/keyring_handler.h
> +++ b/security/integrity/platform_certs/keyring_handler.h
> @@ -24,6 +24,11 @@ void blacklist_binary(const char *source, const void *data, size_t len);
>   */
>  efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type);
>  
> +/*
> + * Return the handler for particular signature list types found in the mok.
> + */
> +efi_element_handler_t get_handler_for_mok(const efi_guid_t *sig_type);
> +
>  /*
>   * Return the handler for particular signature list types found in the dbx.
>   */
> diff --git a/security/integrity/platform_certs/load_uefi.c b/security/integrity/platform_certs/load_uefi.c
> index f290f78c3f30..c1bfd1cd7cc3 100644
> --- a/security/integrity/platform_certs/load_uefi.c
> +++ b/security/integrity/platform_certs/load_uefi.c
> @@ -94,7 +94,7 @@ static int __init load_moklist_certs(void)
>  		rc = parse_efi_signature_list("UEFI:MokListRT (MOKvar table)",
>  					      mokvar_entry->data,
>  					      mokvar_entry->data_size,
> -					      get_handler_for_db);
> +					      get_handler_for_mok);
>  		/* All done if that worked. */
>  		if (!rc)
>  			return rc;
> @@ -109,7 +109,7 @@ static int __init load_moklist_certs(void)
>  	mok = get_cert_list(L"MokListRT", &mok_var, &moksize, &status);
>  	if (mok) {
>  		rc = parse_efi_signature_list("UEFI:MokListRT",
> -					      mok, moksize, get_handler_for_db);
> +					      mok, moksize, get_handler_for_mok);
>  		kfree(mok);
>  		if (rc)
>  			pr_err("Couldn't parse MokListRT signatures: %d\n", rc);
> -- 
> 2.18.4
> 

Reviewed-by: Jarkko Sakkinen <jarkko@...nel.org>

/Jarkko