[NetLabel]: SELinux support

Add NetLabel support to the SELinux LSM and modify the
socket_post_create() LSM hook to return an error code.  The most
significant part of this patch is the addition of NetLabel hooks into
the following SELinux LSM hooks:

 * selinux_file_permission()
 * selinux_socket_sendmsg()
 * selinux_socket_post_create()
 * selinux_socket_sock_rcv_skb()
 * selinux_socket_getpeersec_stream()
 * selinux_socket_getpeersec_dgram()
 * selinux_sock_graft()
 * selinux_inet_conn_request()

The basic reasoning behind this patch is that outgoing packets are
"NetLabel'd" by labeling their socket and the NetLabel security
attributes are checked via the additional hook in
selinux_socket_sock_rcv_skb().  NetLabel itself is only a labeling
mechanism, similar to filesystem extended attributes, it is up to the
SELinux enforcement mechanism to perform the actual access checks.

In addition to the changes outlined above this patch also includes
some changes to the extended bitmap (ebitmap) and multi-level security
(mls) code to import and export SELinux TE/MLS attributes into and out
of NetLabel.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: David S. Miller <davem@davemloft.net>

2 files changed, 133 insertions, 0 deletions

diff --git a/security/selinux/include/objsec.h b/security/selinux/include/objsec.h
index 79b9e0af19a0..0a39bfd1319f 100644
--- a/security/selinux/include/objsec.h
+++ b/security/selinux/include/objsec.h
@@ -101,6 +101,14 @@ 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 */
+        enum {                          /* NetLabel state */
+                NLBL_UNSET = 0,
+                NLBL_REQUIRE,
+                NLBL_LABELED,
+        } nlbl_state;
+#endif
 };
 
 struct key_security_struct {
diff --git a/security/selinux/include/selinux_netlabel.h b/security/selinux/include/selinux_netlabel.h
new file mode 100644
index 000000000000..88c463eef1e1
--- /dev/null
+++ b/security/selinux/include/selinux_netlabel.h
@@ -0,0 +1,125 @@
+/*
+ * SELinux interface to the NetLabel subsystem
+ *
+ * Author : Paul Moore <paul.moore@hp.com>
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
+ *
+ * This program is free software;  you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY;  without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
+ * the GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program;  if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+ *
+ */
+
+#ifndef _SELINUX_NETLABEL_H_
+#define _SELINUX_NETLABEL_H_
+
+#ifdef CONFIG_NETLABEL
+void selinux_netlbl_cache_invalidate(void);
+int selinux_netlbl_socket_post_create(struct socket *sock,
+                                      int sock_family,
+                                      u32 sid);
+void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock);
+u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb, u32 sock_sid);
+int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
+                                struct sk_buff *skb,
+                                struct avc_audit_data *ad);
+u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock);
+u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb);
+
+int __selinux_netlbl_inode_permission(struct inode *inode, int mask);
+/**
+ * selinux_netlbl_inode_permission - Verify the socket is NetLabel labeled
+ * @inode: the file descriptor's inode
+ * @mask: the permission mask
+ *
+ * Description:
+ * Looks at a file's inode and if it is marked as a socket protected by
+ * NetLabel then verify that the socket has been labeled, if not try to label
+ * the socket now with the inode's SID.  Returns zero on success, negative
+ * values on failure.
+ *
+ */
+static inline int selinux_netlbl_inode_permission(struct inode *inode,
+                                                  int mask)
+{
+        int rc = 0;
+        struct inode_security_struct *isec;
+        struct sk_security_struct *sksec;
+
+        if (!S_ISSOCK(inode->i_mode))
+                return 0;
+
+        isec = inode->i_security;
+        sksec = SOCKET_I(inode)->sk->sk_security;
+        down(&isec->sem);
+        if (unlikely(sksec->nlbl_state == NLBL_REQUIRE &&
+                     (mask & (MAY_WRITE | MAY_APPEND))))
+                rc = __selinux_netlbl_inode_permission(inode, mask);
+        up(&isec->sem);
+
+        return rc;
+}
+#else
+static inline void selinux_netlbl_cache_invalidate(void)
+{
+        return;
+}
+
+static inline int selinux_netlbl_socket_post_create(struct socket *sock,
+                                                    int sock_family,
+                                                    u32 sid)
+{
+        return 0;
+}
+
+static inline void selinux_netlbl_sock_graft(struct sock *sk,
+                                             struct socket *sock)
+{
+        return;
+}
+
+static inline u32 selinux_netlbl_inet_conn_request(struct sk_buff *skb,
+                                                   u32 sock_sid)
+{
+        return SECSID_NULL;
+}
+
+static inline int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
+                                              struct sk_buff *skb,
+                                              struct avc_audit_data *ad)
+{
+        return 0;
+}
+
+static inline u32 selinux_netlbl_socket_getpeersec_stream(struct socket *sock)
+{
+        return SECSID_NULL;
+}
+
+static inline u32 selinux_netlbl_socket_getpeersec_dgram(struct sk_buff *skb)
+{
+        return SECSID_NULL;
+}
+
+static inline int selinux_netlbl_inode_permission(struct inode *inode,
+                                                  int mask)
+{
+        return 0;
+}
+#endif /* CONFIG_NETLABEL */
+
+#endif