SELinux: Better integration between peer labeling subsystems

Rework the handling of network peer labels so that the different peer labeling
subsystems work better together.  This includes moving both subsystems to a
single "peer" object class which involves not only changes to the permission
checks but an improved method of consolidating multiple packet peer labels.
As part of this work the inbound packet permission check code has been heavily
modified to handle both the old and new behavior in as sane a fashion as
possible.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: James Morris <jmorris@namei.org>

security/selinux/hooks.c

@@ -50,6 +50,7 @@
 #include <net/icmp.h>
 #include <net/ip.h>		/* for local_port_range[] */
 #include <net/tcp.h>		/* struct or_callable used in sock_rcv_skb */
+#include <net/net_namespace.h>
 #include <asm/uaccess.h>
 #include <asm/ioctls.h>
 #include <linux/bitops.h>
@@ -3426,36 +3427,39 @@ static int selinux_parse_skb(struct sk_buff *skb, struct avc_audit_data *ad,
 }
 
 /**
- * selinux_skb_extlbl_sid - Determine the external label of a packet
+ * selinux_skb_peerlbl_sid - Determine the peer label of a packet
  * @skb: the packet
  * @family: protocol family
- * @sid: the packet's SID
+ * @sid: the packet's peer label SID
  *
  * Description:
- * Check the various different forms of external packet labeling and determine
- * the external SID for the packet.  If only one form of external labeling is
- * present then it is used, if both labeled IPsec and NetLabel labels are
- * present then the SELinux type information is taken from the labeled IPsec
- * SA and the MLS sensitivity label information is taken from the NetLabel
- * security attributes.  This bit of "magic" is done in the call to
- * selinux_netlbl_skbuff_getsid().
+ * Check the various different forms of network peer labeling and determine
+ * the peer label/SID for the packet; most of the magic actually occurs in
+ * the security server function security_net_peersid_cmp().  The function
+ * returns zero if the value in @sid is valid (although it may be SECSID_NULL)
+ * or -EACCES if @sid is invalid due to inconsistencies with the different
+ * peer labels.
  *
  */
-static void selinux_skb_extlbl_sid(struct sk_buff *skb,
-				   u16 family,
-				   u32 *sid)
+static int selinux_skb_peerlbl_sid(struct sk_buff *skb, u16 family, u32 *sid)
 {
 	u32 xfrm_sid;
 	u32 nlbl_sid;
+	u32 nlbl_type;
 
 	selinux_skb_xfrm_sid(skb, &xfrm_sid);
-	if (selinux_netlbl_skbuff_getsid(skb,
-					 family,
-					 (xfrm_sid == SECSID_NULL ?
-					  SECINITSID_NETMSG : xfrm_sid),
-					 &nlbl_sid) != 0)
-		nlbl_sid = SECSID_NULL;
-	*sid = (nlbl_sid == SECSID_NULL ? xfrm_sid : nlbl_sid);
+	selinux_netlbl_skbuff_getsid(skb,
+				     family,
+				     SECINITSID_NETMSG,
+				     &nlbl_type,
+				     &nlbl_sid);
+
+	if (security_net_peersid_resolve(nlbl_sid, nlbl_type,
+					 xfrm_sid,
+					 sid) != 0)
+		return -EACCES;
+
+	return 0;
 }
 
 /* socket security operations */
@@ -3521,6 +3525,7 @@ static int selinux_socket_post_create(struct socket *sock, int family,
 	if (sock->sk) {
 		sksec = sock->sk->sk_security;
 		sksec->sid = isec->sid;
+		sksec->sclass = isec->sclass;
 		err = selinux_netlbl_socket_post_create(sock);
 	}
 
@@ -3824,104 +3829,114 @@ static int selinux_socket_unix_may_send(struct socket *sock,
 	return 0;
 }
 
-static int selinux_sock_rcv_skb_compat(struct sock *sk, struct sk_buff *skb,
-				       struct avc_audit_data *ad,
-				       u16 family, char *addrp)
+static int selinux_sock_rcv_skb_iptables_compat(struct sock *sk,
+						struct sk_buff *skb,
+						struct avc_audit_data *ad,
+						u16 family,
+						char *addrp)
 {
-	int err = 0;
-	u32 netif_perm, node_perm, node_sid, if_sid, recv_perm = 0;
-	struct socket *sock;
-	u16 sock_class = 0;
-	u32 sock_sid = 0;
-
- 	read_lock_bh(&sk->sk_callback_lock);
- 	sock = sk->sk_socket;
- 	if (sock) {
- 		struct inode *inode;
- 		inode = SOCK_INODE(sock);
- 		if (inode) {
- 			struct inode_security_struct *isec;
- 			isec = inode->i_security;
- 			sock_sid = isec->sid;
- 			sock_class = isec->sclass;
- 		}
- 	}
- 	read_unlock_bh(&sk->sk_callback_lock);
- 	if (!sock_sid)
-  		goto out;
-
-	if (!skb->dev)
-		goto out;
+	int err;
+	struct sk_security_struct *sksec = sk->sk_security;
+	u16 sk_class;
+	u32 netif_perm, node_perm, recv_perm;
+	u32 port_sid, node_sid, if_sid, sk_sid;
 
-	err = sel_netif_sid(skb->iif, &if_sid);
-	if (err)
-		goto out;
+	sk_sid = sksec->sid;
+	sk_class = sksec->sclass;
 
-	switch (sock_class) {
+	switch (sk_class) {
 	case SECCLASS_UDP_SOCKET:
 		netif_perm = NETIF__UDP_RECV;
 		node_perm = NODE__UDP_RECV;
 		recv_perm = UDP_SOCKET__RECV_MSG;
 		break;
-
 	case SECCLASS_TCP_SOCKET:
 		netif_perm = NETIF__TCP_RECV;
 		node_perm = NODE__TCP_RECV;
 		recv_perm = TCP_SOCKET__RECV_MSG;
 		break;
-
 	case SECCLASS_DCCP_SOCKET:
 		netif_perm = NETIF__DCCP_RECV;
 		node_perm = NODE__DCCP_RECV;
 		recv_perm = DCCP_SOCKET__RECV_MSG;
 		break;
-
 	default:
 		netif_perm = NETIF__RAWIP_RECV;
 		node_perm = NODE__RAWIP_RECV;
+		recv_perm = 0;
 		break;
 	}
 
-	err = avc_has_perm(sock_sid, if_sid, SECCLASS_NETIF, netif_perm, ad);
+	err = sel_netif_sid(skb->iif, &if_sid);
 	if (err)
-		goto out;
+		return err;
+	err = avc_has_perm(sk_sid, if_sid, SECCLASS_NETIF, netif_perm, ad);
+	if (err)
+		return err;
 
 	err = sel_netnode_sid(addrp, family, &node_sid);
 	if (err)
-		goto out;
-
-	err = avc_has_perm(sock_sid, node_sid, SECCLASS_NODE, node_perm, ad);
+		return err;
+	err = avc_has_perm(sk_sid, node_sid, SECCLASS_NODE, node_perm, ad);
 	if (err)
-		goto out;
+		return err;
 
-	if (recv_perm) {
-		u32 port_sid;
+	if (!recv_perm)
+		return 0;
+	err = security_port_sid(sk->sk_family, sk->sk_type,
+				sk->sk_protocol, ntohs(ad->u.net.sport),
+				&port_sid);
+	if (err)
+		return err;
+	return avc_has_perm(sk_sid, port_sid, sk_class, recv_perm, ad);
+}
 
-		err = security_port_sid(sk->sk_family, sk->sk_type,
-		                        sk->sk_protocol, ntohs(ad->u.net.sport),
-		                        &port_sid);
-		if (err)
-			goto out;
+static int selinux_sock_rcv_skb_compat(struct sock *sk, struct sk_buff *skb,
+				       struct avc_audit_data *ad,
+				       u16 family, char *addrp)
+{
+	int err;
+	struct sk_security_struct *sksec = sk->sk_security;
+	u32 peer_sid;
+	u32 sk_sid = sksec->sid;
+
+	if (selinux_compat_net)
+		err = selinux_sock_rcv_skb_iptables_compat(sk, skb, ad,
+							   family, addrp);
+	else
+		err = avc_has_perm(sk_sid, skb->secmark, SECCLASS_PACKET,
+				   PACKET__RECV, ad);
+	if (err)
+		return err;
 
-		err = avc_has_perm(sock_sid, port_sid,
-				   sock_class, recv_perm, ad);
+	if (selinux_policycap_netpeer) {
+		err = selinux_skb_peerlbl_sid(skb, family, &peer_sid);
+		if (err)
+			return err;
+		err = avc_has_perm(sk_sid, peer_sid,
+				   SECCLASS_PEER, PEER__RECV, ad);
+	} else {
+		err = selinux_netlbl_sock_rcv_skb(sksec, skb, family, ad);
+		if (err)
+			return err;
+		err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, ad);
 	}
 
-out:
 	return err;
 }
 
 static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 {
-	u16 family;
-	char *addrp;
-	int err = 0;
-	struct avc_audit_data ad;
+	int err;
 	struct sk_security_struct *sksec = sk->sk_security;
+	u16 family = sk->sk_family;
+	u32 sk_sid = sksec->sid;
+	u32 peer_sid;
+	struct avc_audit_data ad;
+	char *addrp;
 
-	family = sk->sk_family;
 	if (family != PF_INET && family != PF_INET6)
-		goto out;
+		return 0;
 
 	/* Handle mapped IPv4 packets arriving via IPv6 sockets */
 	if (family == PF_INET6 && skb->protocol == htons(ETH_P_IP))
@@ -3930,26 +3945,27 @@ static int selinux_socket_sock_rcv_skb(struct sock *sk, struct sk_buff *skb)
 	AVC_AUDIT_DATA_INIT(&ad, NET);
 	ad.u.net.netif = skb->iif;
 	ad.u.net.family = family;
-
 	err = selinux_parse_skb(skb, &ad, &addrp, 1, NULL);
 	if (err)
-		goto out;
+		return err;
 
-	if (selinux_compat_net)
-		err = selinux_sock_rcv_skb_compat(sk, skb, &ad, family, addrp);
-	else
-		err = avc_has_perm(sksec->sid, skb->secmark, SECCLASS_PACKET,
-				   PACKET__RECV, &ad);
-	if (err)
-		goto out;
+	/* If any sort of compatibility mode is enabled then handoff processing
+	 * to the selinux_sock_rcv_skb_compat() function to deal with the
+	 * special handling.  We do this in an attempt to keep this function
+	 * as fast and as clean as possible. */
+	if (selinux_compat_net || !selinux_policycap_netpeer)
+		return selinux_sock_rcv_skb_compat(sk, skb, &ad,
+						   family, addrp);
 
-	err = selinux_netlbl_sock_rcv_skb(sksec, skb, family, &ad);
+	err = avc_has_perm(sk_sid, skb->secmark, SECCLASS_PACKET,
+			   PACKET__RECV, &ad);
 	if (err)
-		goto out;
+		return err;
 
-	err = selinux_xfrm_sock_rcv_skb(sksec->sid, skb, &ad);
-out:	
-	return err;
+	err = selinux_skb_peerlbl_sid(skb, family, &peer_sid);
+	if (err)
+		return err;
+	return avc_has_perm(sk_sid, peer_sid, SECCLASS_PEER, PEER__RECV, &ad);
 }
 
 static int selinux_socket_getpeersec_stream(struct socket *sock, char __user *optval,
@@ -4011,7 +4027,7 @@ static int selinux_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *
 	if (sock && family == PF_UNIX)
 		selinux_get_inode_sid(SOCK_INODE(sock), &peer_secid);
 	else if (skb)
-		selinux_skb_extlbl_sid(skb, family, &peer_secid);
+		selinux_skb_peerlbl_sid(skb, family, &peer_secid);
 
 out:
 	*secid = peer_secid;
@@ -4037,6 +4053,7 @@ static void selinux_sk_clone_security(const struct sock *sk, struct sock *newsk)
 
 	newssec->sid = ssec->sid;
 	newssec->peer_sid = ssec->peer_sid;
+	newssec->sclass = ssec->sclass;
 
 	selinux_netlbl_sk_security_clone(ssec, newssec);
 }
@@ -4060,6 +4077,7 @@ static void selinux_sock_graft(struct sock* sk, struct socket *parent)
 	if (sk->sk_family == PF_INET || sk->sk_family == PF_INET6 ||
 	    sk->sk_family == PF_UNIX)
 		isec->sid = sksec->sid;
+	sksec->sclass = isec->sclass;
 
 	selinux_netlbl_sock_graft(sk, parent);
 }
@@ -4072,7 +4090,9 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	u32 newsid;
 	u32 peersid;
 
-	selinux_skb_extlbl_sid(skb, sk->sk_family, &peersid);
+	err = selinux_skb_peerlbl_sid(skb, sk->sk_family, &peersid);
+	if (err)
+		return err;
 	if (peersid == SECSID_NULL) {
 		req->secid = sksec->sid;
 		req->peer_secid = SECSID_NULL;
@@ -4110,7 +4130,7 @@ static void selinux_inet_conn_established(struct sock *sk,
 {
 	struct sk_security_struct *sksec = sk->sk_security;
 
-	selinux_skb_extlbl_sid(skb, sk->sk_family, &sksec->peer_sid);
+	selinux_skb_peerlbl_sid(skb, sk->sk_family, &sksec->peer_sid);
 }
 
 static void selinux_req_classify_flow(const struct request_sock *req,

security/selinux/include/netlabel.h

@@ -49,6 +49,7 @@ void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 				 u16 family,
 				 u32 base_sid,
+				 u32 *type,
 				 u32 *sid);
 
 void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock);
@@ -89,8 +90,10 @@ static inline void selinux_netlbl_sk_security_clone(
 static inline int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 					       u16 family,
 					       u32 base_sid,
+					       u32 *type,
 					       u32 *sid)
 {
+	*type = NETLBL_NLTYPE_NONE;
 	*sid = SECSID_NULL;
 	return 0;
 }

security/selinux/include/objsec.h

@@ -113,8 +113,8 @@ struct sk_security_struct {
 	struct sock *sk;		/* back pointer to sk object */
 	u32 sid;			/* SID of this object */
 	u32 peer_sid;			/* SID of peer */
-#ifdef CONFIG_NETLABEL
 	u16 sclass;			/* sock security class */
+#ifdef CONFIG_NETLABEL
 	enum {				/* NetLabel state */
 		NLBL_UNSET = 0,
 		NLBL_REQUIRE,

security/selinux/include/security.h

@@ -99,6 +99,10 @@ int security_validate_transition(u32 oldsid, u32 newsid, u32 tasksid,
 
 int security_sid_mls_copy(u32 sid, u32 mls_sid, u32 *new_sid);
 
+int security_net_peersid_resolve(u32 nlbl_sid, u32 nlbl_type,
+				 u32 xfrm_sid,
+				 u32 *peer_sid);
+
 int security_get_classes(char ***classes, int *nclasses);
 int security_get_permissions(char *class, char ***perms, int *nperms);
 int security_get_reject_unknown(void);