[PATCH] selinux: Add node controls

From: James Morris <jmorris@redhat.com>

This patch adds 'node' access controls for SELinux, which allows network
traffic to be controlled on the basis of remote address.

Like the previous patch, similar functionality was present in earlier
SELinux implementations; this is a rework within the constraints of the LSM
hooks present in the mainline kernel.

security/selinux/hooks.c

@@ -2668,10 +2668,11 @@ static int selinux_socket_unix_may_send(struct socket *sock,
 static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
 	int err = 0;
-	u32 netif_perm;
+	u32 netif_perm, node_perm, node_sid;
 	struct socket *sock;
 	struct inode *inode;
 	struct net_device *dev;
+	struct iphdr *iph;
 	struct sel_netif *netif;
 	struct netif_security_struct *nsec;
 	struct inode_security_struct *isec;
@@ -2707,14 +2708,17 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	switch (isec->sclass) {
 	case SECCLASS_UDP_SOCKET:
 		netif_perm = NETIF__UDP_RECV;
+		node_perm = NODE__UDP_RECV;
 		break;
 	
 	case SECCLASS_TCP_SOCKET:
 		netif_perm = NETIF__TCP_RECV;
+		node_perm = NODE__TCP_RECV;
 		break;
 	
 	default:
 		netif_perm = NETIF__RAWIP_RECV;
+		node_perm = NODE__RAWIP_RECV;
 		break;
 	}
 
@@ -2724,8 +2728,18 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 
 	err = avc_has_perm(isec->sid, nsec->if_sid, SECCLASS_NETIF,
 	                   netif_perm, &nsec->avcr, &ad);
-
 	sel_netif_put(netif);
+	if (err)
+		goto out;
+	
+	/* Fixme: this lookup is inefficient */
+	iph = skb->nh.iph;
+	err = security_node_sid(PF_INET, &iph->saddr, sizeof(iph->saddr), &node_sid);
+	if (err)
+		goto out;
+	
+	err = avc_has_perm(isec->sid, node_sid, SECCLASS_NODE, node_perm, NULL, &ad);
+
 out:	
 	return err;
 }
@@ -2738,9 +2752,10 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
                                               int (*okfn)(struct sk_buff *))
 {
 	int err = NF_ACCEPT;
-	u32 netif_perm;
+	u32 netif_perm, node_perm, node_sid;
 	struct socket *sock;
 	struct inode *inode;
+	struct iphdr *iph;
 	struct sel_netif *netif;
 	struct sk_buff *skb = *pskb;
 	struct netif_security_struct *nsec;
@@ -2771,14 +2786,17 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
 	switch (isec->sclass) {
 	case SECCLASS_UDP_SOCKET:
 		netif_perm = NETIF__UDP_SEND;
+		node_perm = NODE__UDP_SEND;
 		break;
 	
 	case SECCLASS_TCP_SOCKET:
 		netif_perm = NETIF__TCP_SEND;
+		node_perm = NODE__TCP_SEND;
 		break;
 	
 	default:
 		netif_perm = NETIF__RAWIP_SEND;
+		node_perm = NODE__RAWIP_SEND;
 		break;
 	}
 
@@ -2788,8 +2806,18 @@ static unsigned int selinux_ip_postroute_last(unsigned int hooknum,
 
 	err = avc_has_perm(isec->sid, nsec->if_sid, SECCLASS_NETIF,
 	                   netif_perm, &nsec->avcr, &ad) ? NF_DROP : NF_ACCEPT;
-
 	sel_netif_put(netif);
+	if (err != NF_ACCEPT)
+		goto out;
+		
+	/* Fixme: this lookup is inefficient */
+	iph = skb->nh.iph;
+	err = security_node_sid(PF_INET, &iph->daddr, sizeof(iph->daddr), &node_sid);
+	if (err)
+		goto out;
+	
+	err = avc_has_perm(isec->sid, node_sid, SECCLASS_NODE,
+	                   node_perm, NULL, &ad) ? NF_DROP : NF_ACCEPT;
 out:
 	return err;
 }