Re: [PATCH] selinux: Streamline type determination in security_compute_sid

[Paul Moore <paul@paul-moore.com>]

On Jun 29, 2024 Canfeng Guo <guocanfeng@uniontech.com> wrote:
> 
> Simplifies the logic for determining the security context type in
> security_compute_sid, enhancing readability and efficiency.
> 
> Consolidates default type assignment logic next to type transition
> checks, removing redundancy and improving code flow.
> 
> Signed-off-by: Canfeng Guo <guocanfeng@uniontech.com>
> ---
>  security/selinux/ss/services.c | 32 ++++++++++++++++----------------
>  1 file changed, 16 insertions(+), 16 deletions(-)
> 
> diff --git a/security/selinux/ss/services.c b/security/selinux/ss/services.c
> index e33e55384b75..0c07ebf0b1e7 100644
> --- a/security/selinux/ss/services.c
> +++ b/security/selinux/ss/services.c
> @@ -1804,21 +1804,7 @@ static int security_compute_sid(u32 ssid,
>  			newcontext.role = OBJECT_R_VAL;
>  	}
>  
> -	/* Set the type to default values. */
> -	if (cladatum && cladatum->default_type == DEFAULT_SOURCE) {
> -		newcontext.type = scontext->type;
> -	} else if (cladatum && cladatum->default_type == DEFAULT_TARGET) {
> -		newcontext.type = tcontext->type;
> -	} else {
> -		if ((tclass == policydb->process_class) || sock) {
> -			/* Use the type of process. */
> -			newcontext.type = scontext->type;
> -		} else {
> -			/* Use the type of the related object. */
> -			newcontext.type = tcontext->type;
> -		}
> -	}
> -
> +	/* Set the type. */
>  	/* Look for a type transition/member/change rule. */
>  	avkey.source_type = scontext->type;
>  	avkey.target_type = tcontext->type;
> @@ -1837,9 +1823,23 @@ static int security_compute_sid(u32 ssid,
>  		}
>  	}
>  
> +	/* If a permanent rule is found, use the type from */
> +	/* the type transition/member/change rule. Otherwise, */
> +	/* set the type to its default values. */

In general this patch looks fine with the exception of the comment
block above, you can either follow the multi-line comment used elsewhere
in this source file, example:

 /* line one
    line two
    line three */

... or you can follow the generally accepted style for multi-line
comments in the Linux kernel:

 /* line one
  * line two
  * line three
  */

See the link below for more information:

* https://docs.kernel.org/process/coding-style.html#commenting

>  	if (avnode) {
> -		/* Use the type from the type transition/member/change rule. */
>  		newcontext.type = avnode->datum.u.data;
> +	} else if (cladatum && cladatum->default_type == DEFAULT_SOURCE) {
> +		newcontext.type = scontext->type;
> +	} else if (cladatum && cladatum->default_type == DEFAULT_TARGET) {
> +		newcontext.type = tcontext->type;
> +	} else {
> +		if ((tclass == policydb->process_class) || sock) {
> +			/* Use the type of process. */
> +			newcontext.type = scontext->type;
> +		} else {
> +			/* Use the type of the related object. */
> +			newcontext.type = tcontext->type;
> +		}
>  	}
>  
>  	/* if we have a objname this is a file trans check so check those rules */
> -- 
> 2.20.1

--
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