[PATCH] smack: Guard smack_ipv6_lock definition within a SMACK_IPV6_PORT_LABELING block

[Casey Schaufler]

On 9/10/2021 2:45 AM, Sebastian Andrzej Siewior wrote:
> The mutex smack_ipv6_lock is only used with the SMACK_IPV6_PORT_LABELING
> block but its definition is outside of the block. This leads to a
> defined-but-not-used warning on PREEMPT_RT.
>
> Moving smack_ipv6_lock down to the block where it is used where it used
> raises the question why is smk_ipv6_port_list read if nothing is added
> to it.
> Turns out, only smk_ipv6_port_check() is using it outside of an ifdef
> SMACK_IPV6_PORT_LABELING block. However two of three caller invoke
> smk_ipv6_port_check() from a ifdef block and only one is using
> __is_defined() macro which requires the function and smk_ipv6_port_list
> to be around.
>
> Put the lock and list inside an ifdef SMACK_IPV6_PORT_LABELING block to
> avoid the warning regarding unused mutex. Extend the ifdef-block to also
> cover smk_ipv6_port_check(). Make smack_socket_connect() use ifdef
> instead of __is_defined() to avoid complains about missing function.
>
> Cc: Casey Schaufler <casey at schaufler-ca.com>

This is the Smack maintainer, to whom you should send the next revision.

> Cc: James Morris <jmorris at namei.org>
> Cc: "Serge E. Hallyn" <serge at hallyn.com>
> Signed-off-by: Sebastian Andrzej Siewior <bigeasy at linutronix.de>
> ---
>  security/smack/smack_lsm.c | 7 +++++--
>  1 file changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index cacbe75185194..fd9e6b54907ee 100644
> --- a/security/smack/smack_lsm.c
> +++ b/security/smack/smack_lsm.c
> @@ -51,8 +51,10 @@
>  #define SMK_RECEIVING	1
>  #define SMK_SENDING	2
>  
> +#ifdef SMACK_IPV6_PORT_LABELING
>  static DEFINE_MUTEX(smack_ipv6_lock);
>  static LIST_HEAD(smk_ipv6_port_list);
> +#endif
>  struct kmem_cache *smack_rule_cache;
>  int smack_enabled __initdata;
>  
> @@ -2603,7 +2605,6 @@ static void smk_ipv6_port_label(struct socket *sock, struct sockaddr *address)
>  	mutex_unlock(&smack_ipv6_lock);
>  	return;
>  }
> -#endif
>  
>  /**
>   * smk_ipv6_port_check - check Smack port access
> @@ -2666,6 +2667,7 @@ static int smk_ipv6_port_check(struct sock *sk, struct sockaddr_in6 *address,
>  
>  	return smk_ipv6_check(skp, object, address, act);
>  }
> +#endif
>  
>  /**
>   * smack_inode_setsecurity - set smack xattrs
> @@ -2852,8 +2854,9 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
>  			rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
>  					    SMK_CONNECTING);
>  		}
> -		if (__is_defined(SMACK_IPV6_PORT_LABELING))
> +#ifdef SMACK_IPV6_PORT_LABELING
>  			rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
> +#endif

Fix the indentation.

Also, the patch came through with some html artifacts. Please fix the
indentation and resubmit. Thank you.

>  
>  		return rc;
>  	}