Re: [PATCH v4 4/6] integrity: check whether imputed trust is enabled

[R Nageswara Sastry <rnsastry@linux.ibm.com>]

On 15/08/23 4:57 pm, Nayna Jain wrote:
> trust_moklist() is specific to UEFI enabled systems. Other platforms
> rely only on the Kconfig.
> 
> Define a generic wrapper named imputed_trust_enabled().
> 
> Signed-off-by: Nayna Jain <nayna@linux.ibm.com>
> Reviewed-off-by: Mimi Zohar <zohar@linux.ibm.com>

Tested with trustedcadb, moduledb scenarios
Tested-by: Nageswara R Sastry <rnsastry@linux.ibm.com>

> ---
>   security/integrity/digsig.c                    |  2 +-
>   security/integrity/integrity.h                 |  5 +++--
>   .../integrity/platform_certs/keyring_handler.c |  3 ++-
>   .../integrity/platform_certs/machine_keyring.c | 18 ++++++++++++++++--
>   4 files changed, 22 insertions(+), 6 deletions(-)
> 
> diff --git a/security/integrity/digsig.c b/security/integrity/digsig.c
> index d0704b1597d4..df387de29bfa 100644
> --- a/security/integrity/digsig.c
> +++ b/security/integrity/digsig.c
> @@ -113,7 +113,7 @@ static int __init __integrity_init_keyring(const unsigned int id,
>   	} else {
>   		if (id == INTEGRITY_KEYRING_PLATFORM)
>   			set_platform_trusted_keys(keyring[id]);
> -		if (id == INTEGRITY_KEYRING_MACHINE && trust_moklist())
> +		if (id == INTEGRITY_KEYRING_MACHINE && imputed_trust_enabled())
>   			set_machine_trusted_keys(keyring[id]);
>   		if (id == INTEGRITY_KEYRING_IMA)
>   			load_module_cert(keyring[id]);
> diff --git a/security/integrity/integrity.h b/security/integrity/integrity.h
> index 7167a6e99bdc..d7553c93f5c0 100644
> --- a/security/integrity/integrity.h
> +++ b/security/integrity/integrity.h
> @@ -320,13 +320,14 @@ static inline void __init add_to_platform_keyring(const char *source,
>   
>   #ifdef CONFIG_INTEGRITY_MACHINE_KEYRING
>   void __init add_to_machine_keyring(const char *source, const void *data, size_t len);
> -bool __init trust_moklist(void);
> +bool __init imputed_trust_enabled(void);
>   #else
>   static inline void __init add_to_machine_keyring(const char *source,
>   						  const void *data, size_t len)
>   {
>   }
> -static inline bool __init trust_moklist(void)
> +
> +static inline bool __init imputed_trust_enabled(void)
>   {
>   	return false;
>   }
> diff --git a/security/integrity/platform_certs/keyring_handler.c b/security/integrity/platform_certs/keyring_handler.c
> index 1649d047e3b8..586027b9a3f5 100644
> --- a/security/integrity/platform_certs/keyring_handler.c
> +++ b/security/integrity/platform_certs/keyring_handler.c
> @@ -61,7 +61,8 @@ __init efi_element_handler_t get_handler_for_db(const efi_guid_t *sig_type)
>   __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) && trust_moklist())
> +		if (IS_ENABLED(CONFIG_INTEGRITY_MACHINE_KEYRING) &&
> +		    imputed_trust_enabled())
>   			return add_to_machine_keyring;
>   		else
>   			return add_to_platform_keyring;
> diff --git a/security/integrity/platform_certs/machine_keyring.c b/security/integrity/platform_certs/machine_keyring.c
> index 9482e16cb2ca..a401640a63cd 100644
> --- a/security/integrity/platform_certs/machine_keyring.c
> +++ b/security/integrity/platform_certs/machine_keyring.c
> @@ -34,7 +34,8 @@ void __init add_to_machine_keyring(const char *source, const void *data, size_t
>   	 * If the restriction check does not pass and the platform keyring
>   	 * is configured, try to add it into that keyring instead.
>   	 */
> -	if (rc && efi_enabled(EFI_BOOT) && IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING))
> +	if (rc && efi_enabled(EFI_BOOT) &&
> +	    IS_ENABLED(CONFIG_INTEGRITY_PLATFORM_KEYRING))
>   		rc = integrity_load_cert(INTEGRITY_KEYRING_PLATFORM, source,
>   					 data, len, perm);
>   
> @@ -60,7 +61,7 @@ static __init bool uefi_check_trust_mok_keys(void)
>   	return false;
>   }
>   
> -bool __init trust_moklist(void)
> +static bool __init trust_moklist(void)
>   {
>   	static bool initialized;
>   	static bool trust_mok;
> @@ -75,3 +76,16 @@ bool __init trust_moklist(void)
>   
>   	return trust_mok;
>   }
> +
> +/*
> + * Provides platform specific check for trusting imputed keys before loading
> + * on .machine keyring. UEFI systems enable this trust based on a variable,
> + * and for other platforms, it is always enabled.
> + */
> +bool __init imputed_trust_enabled(void)
> +{
> +	if (efi_enabled(EFI_BOOT))
> +		return trust_moklist();
> +
> +	return true;
> +}

-- 
Thanks and Regards
R.Nageswara Sastry