[PATCH 04/14] Implement CAP_TRUST capability.

[Serge Hallyn (shallyn)]

On Fri, Feb 03, 2023 at 11:09:44PM -0600, Dr. Greg wrote:
> TSEM was designed to support a Trust Orchestration System (TOS)
> security architecture.  A TOS based system uses the concept of a
> minimum Trusted Computing Base of utilities, referred to as trust
> orchestrators, that maintain workloads in a trusted execution
> state.  The trust orchestrators are thus, from a security
> perspective, the most privileged assets on the platform.
> 
> Introduce the CAP_TRUST capability that is defined as a
> capability that allows a process to alter the trust status of the

This sounds like CAP_MAC_ADMIN.  Any reason not to re-use that?

> platform.  In a fully trust orchestrated system only the
> orchestrators carry this capability bit.
> 
> In TSEM the CAP_TRUST capability allows the holder to access the
> control plane of the LSM.  This ability allows subordinate
> modeling domains to be created and managed.  Most principally the
> CAP_TRUST capability allows the holder to designate whether or
> not a process should be trusted or untrusted.
> 
> The proposed Integrity Measurement Architecture namespaces would
> also be a candidate to use the CAP_TRUST capability.
> 
> Signed-off-by: Greg Wettstein <greg at enjellic.com>
> ---
>  include/uapi/linux/capability.h     | 6 +++++-
>  security/selinux/include/classmap.h | 2 +-
>  2 files changed, 6 insertions(+), 2 deletions(-)
> 
> diff --git a/include/uapi/linux/capability.h b/include/uapi/linux/capability.h
> index 3d61a0ae055d..af677b534949 100644
> --- a/include/uapi/linux/capability.h
> +++ b/include/uapi/linux/capability.h
> @@ -417,7 +417,11 @@ struct vfs_ns_cap_data {
>  
>  #define CAP_CHECKPOINT_RESTORE	40
>  
> -#define CAP_LAST_CAP         CAP_CHECKPOINT_RESTORE
> +/* Allow modifications to the trust status of the system */
> +
> +#define CAP_TRUST	41
> +
> +#define CAP_LAST_CAP         CAP_TRUST
>  
>  #define cap_valid(x) ((x) >= 0 && (x) <= CAP_LAST_CAP)
>  
> diff --git a/security/selinux/include/classmap.h b/security/selinux/include/classmap.h
> index a3c380775d41..e8c497c16271 100644
> --- a/security/selinux/include/classmap.h
> +++ b/security/selinux/include/classmap.h
> @@ -30,7 +30,7 @@
>  		"wake_alarm", "block_suspend", "audit_read", "perfmon", "bpf", \
>  		"checkpoint_restore"
>  
> -#if CAP_LAST_CAP > CAP_CHECKPOINT_RESTORE
> +#if CAP_LAST_CAP > CAP_TRUST
>  #error New capability defined, please update COMMON_CAP2_PERMS.
>  #endif
>  
> -- 
> 2.39.1
>