Subject: [PATCH] smack: Guard smack_ipv6_lock definition within a SMACK_IPV6_PORT_LABELING block
From: Sebastian Andrzej Siewior <[email-masked]>
Date: Thu, 9 Sep 2021 12:18:29 +0200

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 <[email-masked]>
Cc: James Morris <[email-masked]>
Cc: "Serge E. Hallyn" <[email-masked]>
Signed-off-by: Sebastian Andrzej Siewior <[email-masked]>
---
 security/smack/smack_lsm.c |    9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

--- 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 s
 	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 so
 
 	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 s
 			rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
 					    SMK_CONNECTING);
 		}
-		if (__is_defined(SMACK_IPV6_PORT_LABELING))
-			rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
+#ifdef SMACK_IPV6_PORT_LABELING
+		rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
+#endif
 
 		return rc;
 	}