Smack: IPv6 host labeling

IPv6 appears to be (finally) coming of age with the
influx of autonomous devices. In support of this, add
the ability to associate a Smack label with IPv6 addresses.

This patch also cleans up some of the conditional
compilation associated with the introduction of
secmark processing. It's now more obvious which bit
of code goes with which feature.

Signed-off-by: Casey Schaufler <casey@schaufler-ca.com>

1 files changed, 187 insertions, 75 deletions

diff --git a/security/smack/smack_lsm.c b/security/smack/smack_lsm.c
index d962f887d3f4..cc390bccecd7 100644
--- a/security/smack/smack_lsm.c
+++ b/security/smack/smack_lsm.c
@@ -51,9 +51,9 @@
 #define SMK_RECEIVING	1
 #define SMK_SENDING	2
 
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
+#ifdef SMACK_IPV6_PORT_LABELING
 LIST_HEAD(smk_ipv6_port_list);
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
 static struct kmem_cache *smack_inode_cache;
 int smack_enabled;
 
@@ -2272,7 +2272,7 @@ static void smack_sk_free_security(struct sock *sk)
 }
 
 /**
-* smack_host_label - check host based restrictions
+* smack_ipv4host_label - check host based restrictions
 * @sip: the object end
 *
 * looks for host based access restrictions
@@ -2283,30 +2283,96 @@ static void smack_sk_free_security(struct sock *sk)
 *
 * Returns the label of the far end or NULL if it's not special.
 */
-static struct smack_known *smack_host_label(struct sockaddr_in *sip)
+static struct smack_known *smack_ipv4host_label(struct sockaddr_in *sip)
 {
-	struct smk_netlbladdr *snp;
+	struct smk_net4addr *snp;
 	struct in_addr *siap = &sip->sin_addr;
 
 	if (siap->s_addr == 0)
 		return NULL;
 
-	list_for_each_entry_rcu(snp, &smk_netlbladdr_list, list)
+	list_for_each_entry_rcu(snp, &smk_net4addr_list, list)
+		/*
+		 * we break after finding the first match because
+		 * the list is sorted from longest to shortest mask
+		 * so we have found the most specific match
+		 */
+		if (snp->smk_host.s_addr ==
+		    (siap->s_addr & snp->smk_mask.s_addr))
+			return snp->smk_label;
+
+	return NULL;
+}
+
+#if IS_ENABLED(CONFIG_IPV6)
+/*
+ * smk_ipv6_localhost - Check for local ipv6 host address
+ * @sip: the address
+ *
+ * Returns boolean true if this is the localhost address
+ */
+static bool smk_ipv6_localhost(struct sockaddr_in6 *sip)
+{
+	__be16 *be16p = (__be16 *)&sip->sin6_addr;
+	__be32 *be32p = (__be32 *)&sip->sin6_addr;
+
+	if (be32p[0] == 0 && be32p[1] == 0 && be32p[2] == 0 && be16p[6] == 0 &&
+	    ntohs(be16p[7]) == 1)
+		return true;
+	return false;
+}
+
+/**
+* smack_ipv6host_label - check host based restrictions
+* @sip: the object end
+*
+* looks for host based access restrictions
+*
+* This version will only be appropriate for really small sets of single label
+* hosts.  The caller is responsible for ensuring that the RCU read lock is
+* taken before calling this function.
+*
+* Returns the label of the far end or NULL if it's not special.
+*/
+static struct smack_known *smack_ipv6host_label(struct sockaddr_in6 *sip)
+{
+	struct smk_net6addr *snp;
+	struct in6_addr *sap = &sip->sin6_addr;
+	int i;
+	int found = 0;
+
+	/*
+	 * It's local. Don't look for a host label.
+	 */
+	if (smk_ipv6_localhost(sip))
+		return NULL;
+
+	list_for_each_entry_rcu(snp, &smk_net6addr_list, list) {
 		/*
 		* we break after finding the first match because
 		* the list is sorted from longest to shortest mask
 		* so we have found the most specific match
 		*/
-		if ((&snp->smk_host.sin_addr)->s_addr ==
-		    (siap->s_addr & (&snp->smk_mask)->s_addr)) {
-			/* we have found the special CIPSO option */
-			if (snp->smk_label == &smack_cipso_option)
-				return NULL;
-			return snp->smk_label;
+		for (found = 1, i = 0; i < 8; i++) {
+			/*
+			 * If the label is NULL the entry has
+			 * been renounced. Ignore it.
+			 */
+			if (snp->smk_label == NULL)
+				continue;
+			if ((sap->s6_addr16[i] & snp->smk_mask.s6_addr16[i]) !=
+			    snp->smk_host.s6_addr16[i]) {
+				found = 0;
+				break;
+			}
 		}
+		if (found)
+			return snp->smk_label;
+	}
 
 	return NULL;
 }
+#endif /* CONFIG_IPV6 */
 
 /**
  * smack_netlabel - Set the secattr on a socket
@@ -2370,7 +2436,7 @@ static int smack_netlabel_send(struct sock *sk, struct sockaddr_in *sap)
 	struct smk_audit_info ad;
 
 	rcu_read_lock();
-	hkp = smack_host_label(sap);
+	hkp = smack_ipv4host_label(sap);
 	if (hkp != NULL) {
 #ifdef CONFIG_AUDIT
 		struct lsm_network_audit net;
@@ -2395,7 +2461,42 @@ static int smack_netlabel_send(struct sock *sk, struct sockaddr_in *sap)
 	return smack_netlabel(sk, sk_lbl);
 }
 
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
+#if IS_ENABLED(CONFIG_IPV6)
+/**
+ * smk_ipv6_check - check Smack access
+ * @subject: subject Smack label
+ * @object: object Smack label
+ * @address: address
+ * @act: the action being taken
+ *
+ * Check an IPv6 access
+ */
+static int smk_ipv6_check(struct smack_known *subject,
+				struct smack_known *object,
+				struct sockaddr_in6 *address, int act)
+{
+#ifdef CONFIG_AUDIT
+	struct lsm_network_audit net;
+#endif
+	struct smk_audit_info ad;
+	int rc;
+
+#ifdef CONFIG_AUDIT
+	smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
+	ad.a.u.net->family = PF_INET6;
+	ad.a.u.net->dport = ntohs(address->sin6_port);
+	if (act == SMK_RECEIVING)
+		ad.a.u.net->v6info.saddr = address->sin6_addr;
+	else
+		ad.a.u.net->v6info.daddr = address->sin6_addr;
+#endif
+	rc = smk_access(subject, object, MAY_WRITE, &ad);
+	rc = smk_bu_note("IPv6 check", subject, object, MAY_WRITE, rc);
+	return rc;
+}
+#endif /* CONFIG_IPV6 */
+
+#ifdef SMACK_IPV6_PORT_LABELING
 /**
  * smk_ipv6_port_label - Smack port access table management
  * @sock: socket
@@ -2479,48 +2580,43 @@ static void smk_ipv6_port_label(struct socket *sock, struct sockaddr *address)
 static int smk_ipv6_port_check(struct sock *sk, struct sockaddr_in6 *address,
 				int act)
 {
-	__be16 *bep;
-	__be32 *be32p;
 	struct smk_port_label *spp;
 	struct socket_smack *ssp = sk->sk_security;
-	struct smack_known *skp;
-	unsigned short port = 0;
+	struct smack_known *skp = NULL;
+	unsigned short port;
 	struct smack_known *object;
-	struct smk_audit_info ad;
-	int rc;
-#ifdef CONFIG_AUDIT
-	struct lsm_network_audit net;
-#endif
 
 	if (act == SMK_RECEIVING) {
-		skp = smack_net_ambient;
+		skp = smack_ipv6host_label(address);
 		object = ssp->smk_in;
 	} else {
 		skp = ssp->smk_out;
-		object = smack_net_ambient;
+		object = smack_ipv6host_label(address);
 	}
 
 	/*
-	 * Get the IP address and port from the address.
+	 * The other end is a single label host.
 	 */
-	port = ntohs(address->sin6_port);
-	bep = (__be16 *)(&address->sin6_addr);
-	be32p = (__be32 *)(&address->sin6_addr);
+	if (skp != NULL && object != NULL)
+		return smk_ipv6_check(skp, object, address, act);
+	if (skp == NULL)
+		skp = smack_net_ambient;
+	if (object == NULL)
+		object = smack_net_ambient;
 
 	/*
 	 * It's remote, so port lookup does no good.
 	 */
-	if (be32p[0] || be32p[1] || be32p[2] || bep[6] || ntohs(bep[7]) != 1)
-		goto auditout;
+	if (!smk_ipv6_localhost(address))
+		return smk_ipv6_check(skp, object, address, act);
 
 	/*
 	 * It's local so the send check has to have passed.
 	 */
-	if (act == SMK_RECEIVING) {
-		skp = &smack_known_web;
-		goto auditout;
-	}
+	if (act == SMK_RECEIVING)
+		return 0;
 
+	port = ntohs(address->sin6_port);
 	list_for_each_entry(spp, &smk_ipv6_port_list, list) {
 		if (spp->smk_port != port)
 			continue;
@@ -2530,22 +2626,9 @@ static int smk_ipv6_port_check(struct sock *sk, struct sockaddr_in6 *address,
 		break;
 	}
 
-auditout:
-
-#ifdef CONFIG_AUDIT
-	smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
-	ad.a.u.net->family = sk->sk_family;
-	ad.a.u.net->dport = port;
-	if (act == SMK_RECEIVING)
-		ad.a.u.net->v6info.saddr = address->sin6_addr;
-	else
-		ad.a.u.net->v6info.daddr = address->sin6_addr;
-#endif
-	rc = smk_access(skp, object, MAY_WRITE, &ad);
-	rc = smk_bu_note("IPv6 port check", skp, object, MAY_WRITE, rc);
-	return rc;
+	return smk_ipv6_check(skp, object, address, act);
 }
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif /* SMACK_IPV6_PORT_LABELING */
 
 /**
  * smack_inode_setsecurity - set smack xattrs
@@ -2606,10 +2689,10 @@ static int smack_inode_setsecurity(struct inode *inode, const char *name,
 	} else
 		return -EOPNOTSUPP;
 
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
+#ifdef SMACK_IPV6_PORT_LABELING
 	if (sock->sk->sk_family == PF_INET6)
 		smk_ipv6_port_label(sock, NULL);
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
 
 	return 0;
 }
@@ -2651,7 +2734,7 @@ static int smack_socket_post_create(struct socket *sock, int family,
 	return smack_netlabel(sock->sk, SMACK_CIPSO_SOCKET);
 }
 
-#ifndef CONFIG_SECURITY_SMACK_NETFILTER
+#ifdef SMACK_IPV6_PORT_LABELING
 /**
  * smack_socket_bind - record port binding information.
  * @sock: the socket
@@ -2665,14 +2748,11 @@ static int smack_socket_post_create(struct socket *sock, int family,
 static int smack_socket_bind(struct socket *sock, struct sockaddr *address,
 				int addrlen)
 {
-#if IS_ENABLED(CONFIG_IPV6)
 	if (sock->sk != NULL && sock->sk->sk_family == PF_INET6)
 		smk_ipv6_port_label(sock, address);
-#endif
-
 	return 0;
 }
-#endif /* !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif /* SMACK_IPV6_PORT_LABELING */
 
 /**
  * smack_socket_connect - connect access check
@@ -2688,6 +2768,13 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
 				int addrlen)
 {
 	int rc = 0;
+#if IS_ENABLED(CONFIG_IPV6)
+	struct sockaddr_in6 *sip = (struct sockaddr_in6 *)sap;
+#endif
+#ifdef SMACK_IPV6_SECMARK_LABELING
+	struct smack_known *rsp;
+	struct socket_smack *ssp = sock->sk->sk_security;
+#endif
 
 	if (sock->sk == NULL)
 		return 0;
@@ -2701,10 +2788,15 @@ static int smack_socket_connect(struct socket *sock, struct sockaddr *sap,
 	case PF_INET6:
 		if (addrlen < sizeof(struct sockaddr_in6))
 			return -EINVAL;
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
-		rc = smk_ipv6_port_check(sock->sk, (struct sockaddr_in6 *)sap,
+#ifdef SMACK_IPV6_SECMARK_LABELING
+		rsp = smack_ipv6host_label(sip);
+		if (rsp != NULL)
+			rc = smk_ipv6_check(ssp->smk_out, rsp, sip,
 						SMK_CONNECTING);
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
+#ifdef SMACK_IPV6_PORT_LABELING
+		rc = smk_ipv6_port_check(sock->sk, sip, SMK_CONNECTING);
+#endif
 		break;
 	}
 	return rc;
@@ -3590,9 +3682,13 @@ static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
 				int size)
 {
 	struct sockaddr_in *sip = (struct sockaddr_in *) msg->msg_name;
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
+#if IS_ENABLED(CONFIG_IPV6)
 	struct sockaddr_in6 *sap = (struct sockaddr_in6 *) msg->msg_name;
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
+#ifdef SMACK_IPV6_SECMARK_LABELING
+	struct socket_smack *ssp = sock->sk->sk_security;
+	struct smack_known *rsp;
+#endif
 	int rc = 0;
 
 	/*
@@ -3606,9 +3702,15 @@ static int smack_socket_sendmsg(struct socket *sock, struct msghdr *msg,
 		rc = smack_netlabel_send(sock->sk, sip);
 		break;
 	case AF_INET6:
-#if IS_ENABLED(CONFIG_IPV6) && !defined(CONFIG_SECURITY_SMACK_NETFILTER)
+#ifdef SMACK_IPV6_SECMARK_LABELING
+		rsp = smack_ipv6host_label(sap);
+		if (rsp != NULL)
+			rc = smk_ipv6_check(ssp->smk_out, rsp, sap,
+						SMK_CONNECTING);
+#endif
+#ifdef SMACK_IPV6_PORT_LABELING
 		rc = smk_ipv6_port_check(sock->sk, sap, SMK_SENDING);
-#endif /* CONFIG_IPV6 && !CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
 		break;
 	}
 	return rc;
@@ -3822,10 +3924,12 @@ access_check:
 		proto = smk_skb_to_addr_ipv6(skb, &sadd);
 		if (proto != IPPROTO_UDP && proto != IPPROTO_TCP)
 			break;
-#ifdef CONFIG_SECURITY_SMACK_NETFILTER
+#ifdef SMACK_IPV6_SECMARK_LABELING
 		if (skb && skb->secmark != 0)
 			skp = smack_from_secid(skb->secmark);
 		else
+			skp = smack_ipv6host_label(&sadd);
+		if (skp == NULL)
 			skp = smack_net_ambient;
 #ifdef CONFIG_AUDIT
 		smk_ad_init_net(&ad, __func__, LSM_AUDIT_DATA_NET, &net);
@@ -3836,9 +3940,10 @@ access_check:
 		rc = smk_access(skp, ssp->smk_in, MAY_WRITE, &ad);
 		rc = smk_bu_note("IPv6 delivery", skp, ssp->smk_in,
 					MAY_WRITE, rc);
-#else /* CONFIG_SECURITY_SMACK_NETFILTER */
+#endif /* SMACK_IPV6_SECMARK_LABELING */
+#ifdef SMACK_IPV6_PORT_LABELING
 		rc = smk_ipv6_port_check(sk, &sadd, SMK_RECEIVING);
-#endif /* CONFIG_SECURITY_SMACK_NETFILTER */
+#endif /* SMACK_IPV6_PORT_LABELING */
 		break;
 #endif /* CONFIG_IPV6 */
 	}
@@ -3936,13 +4041,11 @@ static int smack_socket_getpeersec_dgram(struct socket *sock,
 		}
 		netlbl_secattr_destroy(&secattr);
 		break;
-#if IS_ENABLED(CONFIG_IPV6)
 	case PF_INET6:
-#ifdef CONFIG_SECURITY_SMACK_NETFILTER
+#ifdef SMACK_IPV6_SECMARK_LABELING
 		s = skb->secmark;
-#endif /* CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
 		break;
-#endif /* CONFIG_IPV6 */
 	}
 	*secid = s;
 	if (s == 0)
@@ -4065,7 +4168,7 @@ access_check:
 	hdr = ip_hdr(skb);
 	addr.sin_addr.s_addr = hdr->saddr;
 	rcu_read_lock();
-	hskp = smack_host_label(&addr);
+	hskp = smack_ipv4host_label(&addr);
 	rcu_read_unlock();
 
 	if (hskp == NULL)
@@ -4517,9 +4620,9 @@ struct security_hook_list smack_hooks[] = {
 	LSM_HOOK_INIT(unix_may_send, smack_unix_may_send),
 
 	LSM_HOOK_INIT(socket_post_create, smack_socket_post_create),
-#ifndef CONFIG_SECURITY_SMACK_NETFILTER
+#ifdef SMACK_IPV6_PORT_LABELING
 	LSM_HOOK_INIT(socket_bind, smack_socket_bind),
-#endif /* CONFIG_SECURITY_SMACK_NETFILTER */
+#endif
 	LSM_HOOK_INIT(socket_connect, smack_socket_connect),
 	LSM_HOOK_INIT(socket_sendmsg, smack_socket_sendmsg),
 	LSM_HOOK_INIT(socket_sock_rcv_skb, smack_socket_sock_rcv_skb),
@@ -4614,7 +4717,16 @@ static __init int smack_init(void)
 		return -ENOMEM;
 	}
 
-	printk(KERN_INFO "Smack:  Initializing.\n");
+	pr_info("Smack:  Initializing.\n");
+#ifdef CONFIG_SECURITY_SMACK_NETFILTER
+	pr_info("Smack:  Netfilter enabled.\n");
+#endif
+#ifdef SMACK_IPV6_PORT_LABELING
+	pr_info("Smack:  IPv6 port labeling enabled.\n");
+#endif
+#ifdef SMACK_IPV6_SECMARK_LABELING
+	pr_info("Smack:  IPv6 Netfilter enabled.\n");
+#endif
 
 	/*
 	 * Set the security state for the initial task.