Re: [PATCH] smack: avoid unused 'sip' variable warning

[Casey Schaufler]

On 4/8/2020 12:04 PM, Arnd Bergmann wrote:
> 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: 87fbfffcc89b ("broken ping to ipv6 linklocal addresses on debian buster")
> Signed-off-by: Arnd Bergmann <arnd@xxxxxxxx>


Thanks. I will take this, assuming it passes testing.

> ---
> There are lots of ways of addressing this, if you prefer a different
> way, please just treat this patch as a bug report and apply the
> replacement patch directly.
> ---
>  security/smack/smack.h     |  6 ------
>  security/smack/smack_lsm.c | 25 ++++++++-----------------
>  2 files changed, 8 insertions(+), 23 deletions(-)
>
> diff --git a/security/smack/smack.h b/security/smack/smack.h
> index 62529f382942..335d2411abe4 100644
> --- a/security/smack/smack.h
> +++ b/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;
> diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
> index 8c61d175e195..e193b0db0271 100644
> --- a/security/smack/smack_lsm.c
> +++ b/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))