[PATCH 2/2] SELinux: use SECINITSID_NETMSG instead of SECINITSID_UNLABELEDfor NetLabel

[James Morris]

From: Paul Moore <paul.moore@xxxxxx>

These changes will make NetLabel behave like labeled IPsec where there is 
an access check for both labeled and unlabeled packets as well as 
providing the ability to restrict domains to receiving only labeled 
packets when NetLabel is in use.  The changes to the policy are straight 
forward with the following necessary to receive labeled traffic (with 
SECINITSID_NETMSG defined as "netlabel_peer_t"):

 allow mydom_t netlabel_peer_t:{ tcp_socket udp_socket rawip_socket } recvfrom;

The policy for unlabeled traffic would be:

 allow mydom_t unlabeled_t:{ tcp_socket udp_socket rawip_socket } recvfrom;

These policy changes, as well as more general NetLabel support, are 
included in the latest SELinux Reference Policy release 20070629 or later.  
Users who make use of NetLabel are strongly encouraged to upgrade their 
policy to avoid network problems.

Signed-off-by: Paul Moore <paul.moore@xxxxxx>
Signed-off-by: James Morris <jmorris@xxxxxxxxx>
---
 security/selinux/hooks.c    |   21 +++++++++++----------
 security/selinux/netlabel.c |   41 ++++++++++++++++++++---------------------
 2 files changed, 31 insertions(+), 31 deletions(-)

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index 78c3f98..aff8f46 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3129,17 +3129,19 @@ 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
  * @skb: the packet
- * @base_sid: the SELinux SID to use as a context for MLS only external labels
  * @sid: the packet's SID
  *
  * Description:
  * Check the various different forms of external packet labeling and determine
- * the external SID for the packet.
+ * 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().
  *
  */
-static void selinux_skb_extlbl_sid(struct sk_buff *skb,
-				   u32 base_sid,
-				   u32 *sid)
+static void selinux_skb_extlbl_sid(struct sk_buff *skb, u32 *sid)
 {
 	u32 xfrm_sid;
 	u32 nlbl_sid;
@@ -3147,10 +3149,9 @@ static void selinux_skb_extlbl_sid(struct sk_buff *skb,
 	selinux_skb_xfrm_sid(skb, &xfrm_sid);
 	if (selinux_netlbl_skbuff_getsid(skb,
 					 (xfrm_sid == SECSID_NULL ?
-					  base_sid : xfrm_sid),
+					  SECINITSID_NETMSG : xfrm_sid),
 					 &nlbl_sid) != 0)
 		nlbl_sid = SECSID_NULL;
-
 	*sid = (nlbl_sid == SECSID_NULL ? xfrm_sid : nlbl_sid);
 }
 
@@ -3695,7 +3696,7 @@ static int selinux_socket_getpeersec_dgram(struct socket *sock, struct sk_buff *
 	if (sock && sock->sk->sk_family == PF_UNIX)
 		selinux_get_inode_sid(SOCK_INODE(sock), &peer_secid);
 	else if (skb)
-		selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &peer_secid);
+		selinux_skb_extlbl_sid(skb, &peer_secid);
 
 	if (peer_secid == SECSID_NULL)
 		err = -EINVAL;
@@ -3756,7 +3757,7 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
 	u32 newsid;
 	u32 peersid;
 
-	selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &peersid);
+	selinux_skb_extlbl_sid(skb, &peersid);
 	if (peersid == SECSID_NULL) {
 		req->secid = sksec->sid;
 		req->peer_secid = SECSID_NULL;
@@ -3794,7 +3795,7 @@ static void selinux_inet_conn_established(struct sock *sk,
 {
 	struct sk_security_struct *sksec = sk->sk_security;
 
-	selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &sksec->peer_sid);
+	selinux_skb_extlbl_sid(skb, &sksec->peer_sid);
 }
 
 static void selinux_req_classify_flow(const struct request_sock *req,
diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c
index ed9155b..051b14c 100644
--- a/security/selinux/netlabel.c
+++ b/security/selinux/netlabel.c
@@ -163,9 +163,7 @@ int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u32 base_sid, u32 *sid)
 	netlbl_secattr_init(&secattr);
 	rc = netlbl_skbuff_getattr(skb, &secattr);
 	if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
-		rc = security_netlbl_secattr_to_sid(&secattr,
-						    base_sid,
-						    sid);
+		rc = security_netlbl_secattr_to_sid(&secattr, base_sid, sid);
 	else
 		*sid = SECSID_NULL;
 	netlbl_secattr_destroy(&secattr);
@@ -203,7 +201,7 @@ void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
 	if (netlbl_sock_getattr(sk, &secattr) == 0 &&
 	    secattr.flags != NETLBL_SECATTR_NONE &&
 	    security_netlbl_secattr_to_sid(&secattr,
-					   SECINITSID_UNLABELED,
+					   SECINITSID_NETMSG,
 					   &nlbl_peer_sid) == 0)
 		sksec->peer_sid = nlbl_peer_sid;
 	netlbl_secattr_destroy(&secattr);
@@ -300,41 +298,42 @@ int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 				struct avc_audit_data *ad)
 {
 	int rc;
-	u32 netlbl_sid;
-	u32 recv_perm;
+	u32 nlbl_sid;
+	u32 perm;
+	struct netlbl_lsm_secattr secattr;
 
 	if (!netlbl_enabled())
 		return 0;
 
-	rc = selinux_netlbl_skbuff_getsid(skb,
-					  SECINITSID_UNLABELED,
-					  &netlbl_sid);
+	netlbl_secattr_init(&secattr);
+	rc = netlbl_skbuff_getattr(skb, &secattr);
+	if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
+		rc = security_netlbl_secattr_to_sid(&secattr,
+						    SECINITSID_NETMSG,
+						    &nlbl_sid);
+	else
+		nlbl_sid = SECINITSID_UNLABELED;
+	netlbl_secattr_destroy(&secattr);
 	if (rc != 0)
 		return rc;
 
-	if (netlbl_sid == SECSID_NULL)
-		return 0;
-
 	switch (sksec->sclass) {
 	case SECCLASS_UDP_SOCKET:
-		recv_perm = UDP_SOCKET__RECVFROM;
+		perm = UDP_SOCKET__RECVFROM;
 		break;
 	case SECCLASS_TCP_SOCKET:
-		recv_perm = TCP_SOCKET__RECVFROM;
+		perm = TCP_SOCKET__RECVFROM;
 		break;
 	default:
-		recv_perm = RAWIP_SOCKET__RECVFROM;
+		perm = RAWIP_SOCKET__RECVFROM;
 	}
 
-	rc = avc_has_perm(sksec->sid,
-			  netlbl_sid,
-			  sksec->sclass,
-			  recv_perm,
-			  ad);
+	rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 	if (rc == 0)
 		return 0;
 
-	netlbl_skbuff_err(skb, rc);
+	if (nlbl_sid != SECINITSID_UNLABELED)
+		netlbl_skbuff_err(skb, rc);
 	return rc;
 }
 
-- 
1.5.0.6

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