[PATCH v1 2/4] landlock: Use scoped guards for ruleset in landlock_add_rule()

[Günther Noack]

On Mon, Jan 13, 2025 at 05:11:10PM +0100, Mickaël Salaün wrote:
> Simplify error handling by replacing goto statements with automatic
> calls to landlock_put_ruleset() when going out of scope.
> 
> This change depends on the TCP support.
> 
> Cc: Günther Noack <gnoack at google.com>
> Cc: Konstantin Meskhidze <konstantin.meskhidze at huawei.com>
> Cc: Mikhail Ivanov <ivanov.mikhail1 at huawei-partners.com>
> Signed-off-by: Mickaël Salaün <mic at digikod.net>
> Link: https://lore.kernel.org/r/20250113161112.452505-3-mic@digikod.net
> ---
>  security/landlock/syscalls.c | 14 ++++----------
>  1 file changed, 4 insertions(+), 10 deletions(-)
> 
> diff --git a/security/landlock/syscalls.c b/security/landlock/syscalls.c
> index 5a7f1f77292e..a9760d252fc2 100644
> --- a/security/landlock/syscalls.c
> +++ b/security/landlock/syscalls.c
> @@ -399,8 +399,7 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
>  		const enum landlock_rule_type, rule_type,
>  		const void __user *const, rule_attr, const __u32, flags)
>  {
> -	struct landlock_ruleset *ruleset;
> -	int err;
> +	struct landlock_ruleset *ruleset __free(landlock_put_ruleset) = NULL;
>  
>  	if (!is_initialized())
>  		return -EOPNOTSUPP;
> @@ -416,17 +415,12 @@ SYSCALL_DEFINE4(landlock_add_rule, const int, ruleset_fd,
>  
>  	switch (rule_type) {
>  	case LANDLOCK_RULE_PATH_BENEATH:
> -		err = add_rule_path_beneath(ruleset, rule_attr);
> -		break;
> +		return add_rule_path_beneath(ruleset, rule_attr);
>  	case LANDLOCK_RULE_NET_PORT:
> -		err = add_rule_net_port(ruleset, rule_attr);
> -		break;
> +		return add_rule_net_port(ruleset, rule_attr);
>  	default:
> -		err = -EINVAL;
> -		break;
> +		return -EINVAL;
>  	}
> -	landlock_put_ruleset(ruleset);
> -	return err;
>  }
>  
>  /* Enforcement */
> -- 
> 2.47.1
> 

Reviewed-by: Günther Noack <gnoack at google.com>