Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security

Pull SELinux fixes from James Morris.

* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security:
  selinux: process labeled IPsec TCP SYN-ACK packets properly in selinux_ip_postroute()
  selinux: look for IPsec labels on both inbound and outbound packets
  selinux: handle TCP SYN-ACK packets correctly in selinux_ip_postroute()
  selinux: handle TCP SYN-ACK packets correctly in selinux_ip_output()
  selinux: fix possible memory leak

security/selinux/hooks.c

@@ -53,6 +53,7 @@
 #include <net/ip.h>		/* for local_port_range[] */
 #include <net/sock.h>
 #include <net/tcp.h>		/* struct or_callable used in sock_rcv_skb */
+#include <net/inet_connection_sock.h>
 #include <net/net_namespace.h>
 #include <net/netlabel.h>
 #include <linux/uaccess.h>
@@ -3824,7 +3825,7 @@ static int selinux_skb_peerlbl_sid(struct sk_buff *skb, u16 family, u32 *sid)
 	u32 nlbl_sid;
 	u32 nlbl_type;
 
-	err = selinux_skb_xfrm_sid(skb, &xfrm_sid);
+	err = selinux_xfrm_skb_sid(skb, &xfrm_sid);
 	if (unlikely(err))
 		return -EACCES;
 	err = selinux_netlbl_skbuff_getsid(skb, family, &nlbl_type, &nlbl_sid);
@@ -3842,6 +3843,30 @@ static int selinux_skb_peerlbl_sid(struct sk_buff *skb, u16 family, u32 *sid)
 	return 0;
 }
 
+/**
+ * selinux_conn_sid - Determine the child socket label for a connection
+ * @sk_sid: the parent socket's SID
+ * @skb_sid: the packet's SID
+ * @conn_sid: the resulting connection SID
+ *
+ * If @skb_sid is valid then the user:role:type information from @sk_sid is
+ * combined with the MLS information from @skb_sid in order to create
+ * @conn_sid.  If @skb_sid is not valid then then @conn_sid is simply a copy
+ * of @sk_sid.  Returns zero on success, negative values on failure.
+ *
+ */
+static int selinux_conn_sid(u32 sk_sid, u32 skb_sid, u32 *conn_sid)
+{
+	int err = 0;
+
+	if (skb_sid != SECSID_NULL)
+		err = security_sid_mls_copy(sk_sid, skb_sid, conn_sid);
+	else
+		*conn_sid = sk_sid;
+
+	return err;
+}
+
 /* socket security operations */
 
 static int socket_sockcreate_sid(const struct task_security_struct *tsec,
@@ -4448,7 +4473,7 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	struct sk_security_struct *sksec = sk->sk_security;
 	int err;
 	u16 family = sk->sk_family;
-	u32 newsid;
+	u32 connsid;
 	u32 peersid;
 
 	/* handle mapped IPv4 packets arriving via IPv6 sockets */
@@ -4458,16 +4483,11 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	err = selinux_skb_peerlbl_sid(skb, family, &peersid);
 	if (err)
 		return err;
-	if (peersid == SECSID_NULL) {
-		req->secid = sksec->sid;
-		req->peer_secid = SECSID_NULL;
-	} else {
-		err = security_sid_mls_copy(sksec->sid, peersid, &newsid);
+	err = selinux_conn_sid(sksec->sid, peersid, &connsid);
 	if (err)
 		return err;
-		req->secid = newsid;
+	req->secid = connsid;
 	req->peer_secid = peersid;
-	}
 
 	return selinux_netlbl_inet_conn_request(req, family);
 }
@@ -4727,6 +4747,7 @@ static unsigned int selinux_ipv6_forward(const struct nf_hook_ops *ops,
 static unsigned int selinux_ip_output(struct sk_buff *skb,
 				      u16 family)
 {
+	struct sock *sk;
 	u32 sid;
 
 	if (!netlbl_enabled())
@@ -4735,8 +4756,27 @@ static unsigned int selinux_ip_output(struct sk_buff *skb,
 	/* we do this in the LOCAL_OUT path and not the POST_ROUTING path
 	 * because we want to make sure we apply the necessary labeling
 	 * before IPsec is applied so we can leverage AH protection */
-	if (skb->sk) {
-		struct sk_security_struct *sksec = skb->sk->sk_security;
+	sk = skb->sk;
+	if (sk) {
+		struct sk_security_struct *sksec;
+
+		if (sk->sk_state == TCP_LISTEN)
+			/* if the socket is the listening state then this
+			 * packet is a SYN-ACK packet which means it needs to
+			 * be labeled based on the connection/request_sock and
+			 * not the parent socket.  unfortunately, we can't
+			 * lookup the request_sock yet as it isn't queued on
+			 * the parent socket until after the SYN-ACK is sent.
+			 * the "solution" is to simply pass the packet as-is
+			 * as any IP option based labeling should be copied
+			 * from the initial connection request (in the IP
+			 * layer).  it is far from ideal, but until we get a
+			 * security label in the packet itself this is the
+			 * best we can do. */
+			return NF_ACCEPT;
+
+		/* standard practice, label using the parent socket */
+		sksec = sk->sk_security;
 		sid = sksec->sid;
 	} else
 		sid = SECINITSID_KERNEL;
@@ -4806,27 +4846,36 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
 	 * as fast and as clean as possible. */
 	if (!selinux_policycap_netpeer)
 		return selinux_ip_postroute_compat(skb, ifindex, family);
+
+	secmark_active = selinux_secmark_enabled();
+	peerlbl_active = selinux_peerlbl_enabled();
+	if (!secmark_active && !peerlbl_active)
+		return NF_ACCEPT;
+
+	sk = skb->sk;
+
 #ifdef CONFIG_XFRM
 	/* If skb->dst->xfrm is non-NULL then the packet is undergoing an IPsec
 	 * packet transformation so allow the packet to pass without any checks
 	 * since we'll have another chance to perform access control checks
 	 * when the packet is on it's final way out.
 	 * NOTE: there appear to be some IPv6 multicast cases where skb->dst
-	 *       is NULL, in this case go ahead and apply access control. */
-	if (skb_dst(skb) != NULL && skb_dst(skb)->xfrm != NULL)
+	 *       is NULL, in this case go ahead and apply access control.
+	 * NOTE: if this is a local socket (skb->sk != NULL) that is in the
+	 *       TCP listening state we cannot wait until the XFRM processing
+	 *       is done as we will miss out on the SA label if we do;
+	 *       unfortunately, this means more work, but it is only once per
+	 *       connection. */
+	if (skb_dst(skb) != NULL && skb_dst(skb)->xfrm != NULL &&
+	    !(sk != NULL && sk->sk_state == TCP_LISTEN))
 		return NF_ACCEPT;
 #endif
-	secmark_active = selinux_secmark_enabled();
-	peerlbl_active = selinux_peerlbl_enabled();
-	if (!secmark_active && !peerlbl_active)
-		return NF_ACCEPT;
 
-	/* if the packet is being forwarded then get the peer label from the
-	 * packet itself; otherwise check to see if it is from a local
-	 * application or the kernel, if from an application get the peer label
-	 * from the sending socket, otherwise use the kernel's sid */
-	sk = skb->sk;
 	if (sk == NULL) {
+		/* Without an associated socket the packet is either coming
+		 * from the kernel or it is being forwarded; check the packet
+		 * to determine which and if the packet is being forwarded
+		 * query the packet directly to determine the security label. */
 		if (skb->skb_iif) {
 			secmark_perm = PACKET__FORWARD_OUT;
 			if (selinux_skb_peerlbl_sid(skb, family, &peer_sid))
@@ -4835,7 +4884,45 @@ static unsigned int selinux_ip_postroute(struct sk_buff *skb, int ifindex,
 			secmark_perm = PACKET__SEND;
 			peer_sid = SECINITSID_KERNEL;
 		}
+	} else if (sk->sk_state == TCP_LISTEN) {
+		/* Locally generated packet but the associated socket is in the
+		 * listening state which means this is a SYN-ACK packet.  In
+		 * this particular case the correct security label is assigned
+		 * to the connection/request_sock but unfortunately we can't
+		 * query the request_sock as it isn't queued on the parent
+		 * socket until after the SYN-ACK packet is sent; the only
+		 * viable choice is to regenerate the label like we do in
+		 * selinux_inet_conn_request().  See also selinux_ip_output()
+		 * for similar problems. */
+		u32 skb_sid;
+		struct sk_security_struct *sksec = sk->sk_security;
+		if (selinux_skb_peerlbl_sid(skb, family, &skb_sid))
+			return NF_DROP;
+		/* At this point, if the returned skb peerlbl is SECSID_NULL
+		 * and the packet has been through at least one XFRM
+		 * transformation then we must be dealing with the "final"
+		 * form of labeled IPsec packet; since we've already applied
+		 * all of our access controls on this packet we can safely
+		 * pass the packet. */
+		if (skb_sid == SECSID_NULL) {
+			switch (family) {
+			case PF_INET:
+				if (IPCB(skb)->flags & IPSKB_XFRM_TRANSFORMED)
+					return NF_ACCEPT;
+				break;
+			case PF_INET6:
+				if (IP6CB(skb)->flags & IP6SKB_XFRM_TRANSFORMED)
+					return NF_ACCEPT;
+			default:
+				return NF_DROP_ERR(-ECONNREFUSED);
+			}
+		}
+		if (selinux_conn_sid(sksec->sid, skb_sid, &peer_sid))
+			return NF_DROP;
+		secmark_perm = PACKET__SEND;
 	} else {
+		/* Locally generated packet, fetch the security label from the
+		 * associated socket. */
 		struct sk_security_struct *sksec = sk->sk_security;
 		peer_sid = sksec->sid;
 		secmark_perm = PACKET__SEND;

security/selinux/include/xfrm.h

@@ -39,6 +39,7 @@ int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
 int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
 				struct common_audit_data *ad, u8 proto);
 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall);
+int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid);
 
 static inline void selinux_xfrm_notify_policyload(void)
 {
@@ -79,11 +80,12 @@ static inline int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid,
 static inline void selinux_xfrm_notify_policyload(void)
 {
 }
-#endif
 
-static inline int selinux_skb_xfrm_sid(struct sk_buff *skb, u32 *sid)
+static inline int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
 {
-	return selinux_xfrm_decode_session(skb, sid, 0);
+	*sid = SECSID_NULL;
+	return 0;
 }
+#endif
 
 #endif /* _SELINUX_XFRM_H_ */

security/selinux/xfrm.c

@@ -209,19 +209,26 @@ int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
 			    NULL) ? 0 : 1);
 }
 
-/*
- * LSM hook implementation that checks and/or returns the xfrm sid for the
- * incoming packet.
- */
-int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
+static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
 {
-	u32 sid_session = SECSID_NULL;
-	struct sec_path *sp;
+	struct dst_entry *dst = skb_dst(skb);
+	struct xfrm_state *x;
 
-	if (skb == NULL)
-		goto out;
+	if (dst == NULL)
+		return SECSID_NULL;
+	x = dst->xfrm;
+	if (x == NULL || !selinux_authorizable_xfrm(x))
+		return SECSID_NULL;
+
+	return x->security->ctx_sid;
+}
+
+static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
+					u32 *sid, int ckall)
+{
+	u32 sid_session = SECSID_NULL;
+	struct sec_path *sp = skb->sp;
 
-	sp = skb->sp;
 	if (sp) {
 		int i;
 
@@ -247,6 +254,30 @@ int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
 	return 0;
 }
 
+/*
+ * LSM hook implementation that checks and/or returns the xfrm sid for the
+ * incoming packet.
+ */
+int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
+{
+	if (skb == NULL) {
+		*sid = SECSID_NULL;
+		return 0;
+	}
+	return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
+}
+
+int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
+{
+	int rc;
+
+	rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
+	if (rc == 0 && *sid == SECSID_NULL)
+		*sid = selinux_xfrm_skb_sid_egress(skb);
+
+	return rc;
+}
+
 /*
  * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
  */
@@ -327,19 +358,22 @@ int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
 		return rc;
 
 	ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
-	if (!ctx)
-		return -ENOMEM;
+	if (!ctx) {
+		rc = -ENOMEM;
+		goto out;
+	}
 
 	ctx->ctx_doi = XFRM_SC_DOI_LSM;
 	ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
 	ctx->ctx_sid = secid;
 	ctx->ctx_len = str_len;
 	memcpy(ctx->ctx_str, ctx_str, str_len);
-	kfree(ctx_str);
 
 	x->security = ctx;
 	atomic_inc(&selinux_xfrm_refcount);
-	return 0;
+out:
+	kfree(ctx_str);
+	return rc;
 }
 
 /*