[PATCH V3 09/10] capabilities: fix logic for effective root or real root

[Serge E. Hallyn]

Quoting Richard Guy Briggs (rgb at redhat.com):
> Now that the logic is inverted, it is much easier to see that both real root
> and effective root conditions had to be met to avoid printing the BPRM_FCAPS
> record with audit syscalls.  This meant that any setuid root applications would
> print a full BPRM_FCAPS record when it wasn't necessary, cluttering the event
> output, since the SYSCALL and PATH records indicated the presence of the setuid
> bit and effective root user id.
> 
> Require only one of effective root or real root to avoid printing the
> unnecessary record.
> 
> Ref: 3fc689e96c0c (Add audit_log_bprm_fcaps/AUDIT_BPRM_FCAPS)
> See: https://github.com/linux-audit/audit-kernel/issues/16
> 
> Signed-off-by: Richard Guy Briggs <rgb at redhat.com>

Reviewed-by: Serge Hallyn <serge at hallyn.com>

I wonder whether,

> ---
>  security/commoncap.c |    6 +++---
>  1 files changed, 3 insertions(+), 3 deletions(-)
> 
> diff --git a/security/commoncap.c b/security/commoncap.c
> index eb2da69..49cce06 100644
> --- a/security/commoncap.c
> +++ b/security/commoncap.c
> @@ -540,7 +540,7 @@ static inline bool is_setgid(struct cred *new, const struct cred *old)
>   *
>   * We do not bother to audit if 3 things are true:
>   *   1) cap_effective has all caps
> - *   2) we are root
> + *   2) we became root *OR* are root

For clarity, what do you think about adding "(because fcaps were not used)"?

>   *   3) root is supposed to have all caps (SECURE_NOROOT)
>   * Since this is just a normal root execing a process.
>   *
> @@ -553,8 +553,8 @@ static inline bool nonroot_raised_pE(struct cred *cred, kuid_t root)
>  
>  	if (cap_grew(effective, ambient, cred) &&
>  	    !(cap_full(effective, cred) &&
> -	      is_eff(root, cred) &&
> -	      is_real(root, cred) &&
> +	      (is_eff(root, cred) ||
> +	       is_real(root, cred)) &&
>  	      root_privileged()))
>  		ret = true;
>  	return ret;
> -- 
> 1.7.1
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