Revert "SELinux: use SECINITSID_NETMSG instead of SECINITSID_UNLABELED for NetLabel"

This reverts commit 9faf65fb6ee2b4e08325ba2d69e5ccf0c46453d0.

It bit people like Michal Piotrowski:

  "My system is too secure, I can not login :)"

because it changed how CONFIG_NETLABEL worked, and broke older SElinux
policies.

As a result, quoth James Morris:

  "Can you please revert this patch?

   We thought it only affected people running MLS, but it will affect others.

   Sorry for the hassle."

Cc: James Morris <jmorris@namei.org>
Cc: Stephen Smalley <sds@tycho.nsa.gov>
Cc: Michal Piotrowski <michal.k.k.piotrowski@gmail.com>
Cc: Paul Moore <paul.moore@hp.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

2 files changed, 31 insertions, 24 deletions

diff --git a/security/selinux/hooks.c b/security/selinux/hooks.c
index aff8f46c2aa2..78c3f98fcdcf 100644
--- a/security/selinux/hooks.c
+++ b/security/selinux/hooks.c
@@ -3129,19 +3129,17 @@ 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.  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().
+ * the external SID for the packet.
  *
  */
-static void selinux_skb_extlbl_sid(struct sk_buff *skb, u32 *sid)
+static void selinux_skb_extlbl_sid(struct sk_buff *skb,
+                                   u32 base_sid,
+                                   u32 *sid)
 {
         u32 xfrm_sid;
         u32 nlbl_sid;
@@ -3149,9 +3147,10 @@ static void selinux_skb_extlbl_sid(struct sk_buff *skb, u32 *sid)
         selinux_skb_xfrm_sid(skb, &xfrm_sid);
         if (selinux_netlbl_skbuff_getsid(skb,
                                          (xfrm_sid == SECSID_NULL ?
-                                          SECINITSID_NETMSG : xfrm_sid),
+                                          base_sid : xfrm_sid),
                                          &nlbl_sid) != 0)
                 nlbl_sid = SECSID_NULL;
+
         *sid = (nlbl_sid == SECSID_NULL ? xfrm_sid : nlbl_sid);
 }
 
@@ -3696,7 +3695,7 @@ 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, &peer_secid);
+                selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &peer_secid);
 
         if (peer_secid == SECSID_NULL)
                 err = -EINVAL;
@@ -3757,7 +3756,7 @@ static int selinux_inet_conn_request(struct sock *sk, struct sk_buff *skb,
         u32 newsid;
         u32 peersid;
 
-        selinux_skb_extlbl_sid(skb, &peersid);
+        selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &peersid);
         if (peersid == SECSID_NULL) {
                 req->secid = sksec->sid;
                 req->peer_secid = SECSID_NULL;
@@ -3795,7 +3794,7 @@ static void selinux_inet_conn_established(struct sock *sk,
 {
         struct sk_security_struct *sksec = sk->sk_security;
 
-        selinux_skb_extlbl_sid(skb, &sksec->peer_sid);
+        selinux_skb_extlbl_sid(skb, SECINITSID_UNLABELED, &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 8192e8bc9f5a..e64eca246f1a 100644
--- a/security/selinux/netlabel.c
+++ b/security/selinux/netlabel.c
@@ -158,7 +158,9 @@ 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);
@@ -196,7 +198,7 @@ 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_NETMSG,
+                                           SECINITSID_UNLABELED,
                                            &nlbl_peer_sid) == 0)
                 sksec->peer_sid = nlbl_peer_sid;
         netlbl_secattr_destroy(&secattr);
@@ -293,32 +295,38 @@ int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
                                 struct avc_audit_data *ad)
 {
         int rc;
-        u32 nlbl_sid;
-        u32 perm;
+        u32 netlbl_sid;
+        u32 recv_perm;
 
-        rc = selinux_netlbl_skbuff_getsid(skb, SECINITSID_NETMSG, &nlbl_sid);
+        rc = selinux_netlbl_skbuff_getsid(skb,
+                                          SECINITSID_UNLABELED,
+                                          &netlbl_sid);
         if (rc != 0)
                 return rc;
-        if (nlbl_sid == SECSID_NULL)
-                nlbl_sid = SECINITSID_UNLABELED;
+
+        if (netlbl_sid == SECSID_NULL)
+                return 0;
 
         switch (sksec->sclass) {
         case SECCLASS_UDP_SOCKET:
-                perm = UDP_SOCKET__RECVFROM;
+                recv_perm = UDP_SOCKET__RECVFROM;
                 break;
         case SECCLASS_TCP_SOCKET:
-                perm = TCP_SOCKET__RECVFROM;
+                recv_perm = TCP_SOCKET__RECVFROM;
                 break;
         default:
-                perm = RAWIP_SOCKET__RECVFROM;
+                recv_perm = RAWIP_SOCKET__RECVFROM;
         }
 
-        rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
+        rc = avc_has_perm(sksec->sid,
+                          netlbl_sid,
+                          sksec->sclass,
+                          recv_perm,
+                          ad);
         if (rc == 0)
                 return 0;
 
-        if (nlbl_sid != SECINITSID_UNLABELED)
-                netlbl_skbuff_err(skb, rc);
+        netlbl_skbuff_err(skb, rc);
         return rc;
 }