[PATCH 69/97] Smack: Consolidate secmark conversions

[Casey Schaufler <casey@schaufler-ca.com>]

Add a helper function smack_from_skb() that does all the checks
required and maps a valid secmark to a smack_known structure.
Replace the direct use of the secmark in surrounding code.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>
---
 security/smack/smack_lsm.c | 39 ++++++++++++++++++++++++++------------
 1 file changed, 27 insertions(+), 12 deletions(-)

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d3ec5f49ef44..7b8ad16c09e0 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -3734,6 +3734,20 @@ static int smk_skb_to_addr_ipv6(struct sk_buff *skb, struct sockaddr_in6 *sip)
 }
 #endif /* CONFIG_IPV6 */
 
+/**
+ * smack_from_skb - Smack data from the secmark in an skb
+ * @skb: packet
+ *
+ * Returns smack_known of the secmark or NULL if that won't work.
+ */
+static struct smack_known *smack_from_skb(struct sk_buff *skb)
+{
+	if (skb == NULL || skb->secmark == 0)
+		return NULL;
+
+	return smack_from_secid(skb->secmark);
+}
+
 /**
  * smack_socket_sock_rcv_skb - Smack packet delivery access check
  * @sk: socket
@@ -3768,10 +3782,9 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		 * If there is no secmark fall back to CIPSO.
 		 * The secmark is assumed to reflect policy better.
 		 */
-		if (skb && skb->secmark != 0) {
-			skp = smack_from_secid(skb->secmark);
+		skp = smack_from_skb(skb);
+		if (skp)
 			goto access_check;
-		}
 #endif /* CONFIG_SECURITY_SMACK_NETFILTER */
 		/*
 		 * Translate what netlabel gave us.
@@ -3814,9 +3827,8 @@ static int smack_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 		    proto != IPPROTO_TCP && proto != IPPROTO_DCCP)
 			break;
 #ifdef SMACK_IPV6_SECMARK_LABELING
-		if (skb && skb->secmark != 0)
-			skp = smack_from_secid(skb->secmark);
-		else
+		skp = smack_from_skb(skb);
+		if (skp == NULL)
 			skp = smack_ipv6host_label(&sadd);
 		if (skp == NULL)
 			skp = smack_net_ambient;
@@ -3917,9 +3929,11 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
 		break;
 	case PF_INET:
 #ifdef CONFIG_SECURITY_SMACK_NETFILTER
-		s = skb->secmark;
-		if (s != 0)
+		skp = smack_from_skb(skb);
+		if (skp) {
+			s = skp->smk_secid;
 			break;
+		}
 #endif
 		/*
 		 * Translate what netlabel gave us.
@@ -3936,7 +3950,9 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
 		break;
 	case PF_INET6:
 #ifdef SMACK_IPV6_SECMARK_LABELING
-		s = skb->secmark;
+		skp = smack_from_skb(skb);
+		if (skp)
+			s = skp->smk_secid;
 #endif
 		break;
 	}
@@ -4014,10 +4030,9 @@ static int smack_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	 * If there is no secmark fall back to CIPSO.
 	 * The secmark is assumed to reflect policy better.
 	 */
-	if (skb && skb->secmark != 0) {
-		skp = smack_from_secid(skb->secmark);
+	skp = smack_from_skb(skb);
+	if (skp)
 		goto access_check;
-	}
 #endif /* CONFIG_SECURITY_SMACK_NETFILTER */
 
 	netlbl_secattr_init(&secattr);
-- 
2.17.0