smack: avoid unused 'sip' variable warning

The mix of IS_ENABLED() and #ifdef checks has left a combination
that causes a warning about an unused variable:

security/smack/smack_lsm.c: In function 'smack_socket_connect':
security/smack/smack_lsm.c:2838:24: error: unused variable 'sip' [-Werror=unused-variable]
 2838 |   struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;

Change the code to use C-style checks consistently so the compiler
can handle it correctly.

Fixes: 87fbfff ("broken ping to ipv6 linklocal addresses on debian buster")
Signed-off-by: Arnd Bergmann <arnd@arndb.de>
Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

Author: arndb

security/smack/smack.h

@@ -148,7 +148,6 @@ struct smk_net4addr {
 	struct smack_known	*smk_label;	/* label */
 };
 
-#if IS_ENABLED(CONFIG_IPV6)
 /*
  * An entry in the table identifying IPv6 hosts.
  */
@@ -159,9 +158,7 @@ struct smk_net6addr {
 	int			smk_masks;	/* mask size */
 	struct smack_known	*smk_label;	/* label */
 };
-#endif /* CONFIG_IPV6 */
 
-#ifdef SMACK_IPV6_PORT_LABELING
 /*
  * An entry in the table identifying ports.
  */
@@ -174,7 +171,6 @@ struct smk_port_label {
 	short			smk_sock_type;	/* Socket type */
 	short			smk_can_reuse;
 };
-#endif /* SMACK_IPV6_PORT_LABELING */
 
 struct smack_known_list_elem {
 	struct list_head	list;
@@ -335,9 +331,7 @@ extern struct smack_known smack_known_web;
 extern struct mutex	smack_known_lock;
 extern struct list_head smack_known_list;
 extern struct list_head smk_net4addr_list;
-#if IS_ENABLED(CONFIG_IPV6)
 extern struct list_head smk_net6addr_list;
-#endif /* CONFIG_IPV6 */
 
 extern struct mutex     smack_onlycap_lock;
 extern struct list_head smack_onlycap_list;

security/smack/smack_lsm.c

@@ -50,10 +50,8 @@
 #define SMK_RECEIVING	1
 #define SMK_SENDING	2
 
-#ifdef SMACK_IPV6_PORT_LABELING
-DEFINE_MUTEX(smack_ipv6_lock);
+static DEFINE_MUTEX(smack_ipv6_lock);
 static LIST_HEAD(smk_ipv6_port_list);
-#endif
 static struct kmem_cache *smack_inode_cache;
 struct kmem_cache *smack_rule_cache;
 int smack_enabled;
@@ -2320,7 +2318,6 @@ static struct smack_known *smack_ipv4host_label(struct sockaddr_in *sip)
 	return NULL;
 }
 
-#if IS_ENABLED(CONFIG_IPV6)
 /*
  * smk_ipv6_localhost - Check for local ipv6 host address
  * @sip: the address
@@ -2388,7 +2385,6 @@ static struct smack_known *smack_ipv6host_label(struct sockaddr_in6 *sip)
 
 	return NULL;
 }
-#endif /* CONFIG_IPV6 */
 
 /**
  * smack_netlabel - Set the secattr on a socket
@@ -2477,7 +2473,6 @@ static int smack_netlabel_send(struct sock *sk, struct sockaddr_in *sap)
 	return smack_netlabel(sk, sk_lbl);
 }
 
-#if IS_ENABLED(CONFIG_IPV6)
 /**
  * smk_ipv6_check - check Smack access
  * @subject: subject Smack label
@@ -2510,7 +2505,6 @@ static int smk_ipv6_check(struct smack_known *subject,
 	rc = smk_bu_note("IPv6 check", subject, object, MAY_WRITE, rc);
 	return rc;
 }
-#endif /* CONFIG_IPV6 */
 
 #ifdef SMACK_IPV6_PORT_LABELING
 /**
@@ -2599,6 +2593,7 @@ 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
@@ -2661,7 +2656,6 @@ static int smk_ipv6_port_check(struct sock *sk, struct sockaddr_in6 *address,
 
 	return smk_ipv6_check(skp, object, address, act);
 }
-#endif /* SMACK_IPV6_PORT_LABELING */
 
 /**
  * smack_inode_setsecurity - set smack xattrs
@@ -2836,24 +2830,21 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
 		return 0;
 	if (IS_ENABLED(CONFIG_IPV6) && sap->sa_family == AF_INET6) {
 		struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;
-#ifdef SMACK_IPV6_SECMARK_LABELING
-		struct smack_known *rsp;
-#endif
+		struct smack_known *rsp = NULL;
 
 		if (addrlen < SIN6_LEN_RFC2133)
 			return 0;
-#ifdef SMACK_IPV6_SECMARK_LABELING
-		rsp = smack_ipv6host_label(sip);
+		if (__is_defined(SMACK_IPV6_SECMARK_LABELING))
+			rsp = smack_ipv6host_label(sip);
 		if (rsp != NULL) {
 			struct socket_smack *ssp = sock->sk->sk_security;
 
 			rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
 					    SMK_CONNECTING);
 		}
-#endif
-#ifdef SMACK_IPV6_PORT_LABELING
-		rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
-#endif
+		if (__is_defined(SMACK_IPV6_PORT_LABELING))
+			rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
+
 		return rc;
 	}
 	if (sap->sa_family != AF_INET || addrlen < sizeof(struct sockaddr_in))