SELinux: extract the NetLabel SELinux support from the security server

Up until this patch the functions which have provided NetLabel support to
SELinux have been integrated into the SELinux security server, which for
various reasons is not really ideal.  This patch makes an effort to extract as
much of the NetLabel support from the security server as possibile and move it
into it's own file within the SELinux directory structure.

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

1 files changed, 363 insertions, 0 deletions

diff --git a/security/selinux/netlabel.c b/security/selinux/netlabel.c
new file mode 100644
index 000000000000..bf8750791dd1
--- /dev/null
+++ b/security/selinux/netlabel.c
@@ -0,0 +1,363 @@
+/*
+ * SELinux NetLabel Support
+ *
+ * This file provides the necessary glue to tie NetLabel into the SELinux
+ * subsystem.
+ *
+ * Author: Paul Moore <paul.moore@hp.com>
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
+ *
+ * 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
+ *
+ */
+
+#include <linux/spinlock.h>
+#include <linux/rcupdate.h>
+#include <net/sock.h>
+#include <net/netlabel.h>
+
+#include "objsec.h"
+#include "security.h"
+
+/**
+ * selinux_netlbl_socket_setsid - Label a socket using the NetLabel mechanism
+ * @sock: the socket to label
+ * @sid: the SID to use
+ *
+ * Description:
+ * Attempt to label a socket using the NetLabel mechanism using the given
+ * SID.  Returns zero values on success, negative values on failure.  The
+ * caller is responsibile for calling rcu_read_lock() before calling this
+ * this function and rcu_read_unlock() after this function returns.
+ *
+ */
+static int selinux_netlbl_socket_setsid(struct socket *sock, u32 sid)
+{
+	int rc;
+	struct sk_security_struct *sksec = sock->sk->sk_security;
+	struct netlbl_lsm_secattr secattr;
+
+	rc = security_netlbl_sid_to_secattr(sid, &secattr);
+	if (rc != 0)
+		return rc;
+
+	rc = netlbl_socket_setattr(sock, &secattr);
+	if (rc == 0) {
+		spin_lock_bh(&sksec->nlbl_lock);
+		sksec->nlbl_state = NLBL_LABELED;
+		spin_unlock_bh(&sksec->nlbl_lock);
+	}
+
+	return rc;
+}
+
+/**
+ * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
+ *
+ * Description:
+ * Invalidate the NetLabel security attribute mapping cache.
+ *
+ */
+void selinux_netlbl_cache_invalidate(void)
+{
+	netlbl_cache_invalidate();
+}
+
+/**
+ * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
+ * @ssec: the sk_security_struct
+ * @family: the socket family
+ *
+ * Description:
+ * Called when the NetLabel state of a sk_security_struct needs to be reset.
+ * The caller is responsibile for all the NetLabel sk_security_struct locking.
+ *
+ */
+void selinux_netlbl_sk_security_reset(struct sk_security_struct *ssec,
+				      int family)
+{
+        if (family == PF_INET)
+		ssec->nlbl_state = NLBL_REQUIRE;
+	else
+		ssec->nlbl_state = NLBL_UNSET;
+}
+
+/**
+ * selinux_netlbl_sk_security_init - Setup the NetLabel fields
+ * @ssec: the sk_security_struct
+ * @family: the socket family
+ *
+ * Description:
+ * Called when a new sk_security_struct is allocated to initialize the NetLabel
+ * fields.
+ *
+ */
+void selinux_netlbl_sk_security_init(struct sk_security_struct *ssec,
+				     int family)
+{
+	/* No locking needed, we are the only one who has access to ssec */
+	selinux_netlbl_sk_security_reset(ssec, family);
+	spin_lock_init(&ssec->nlbl_lock);
+}
+
+/**
+ * selinux_netlbl_sk_security_clone - Copy the NetLabel fields
+ * @ssec: the original sk_security_struct
+ * @newssec: the cloned sk_security_struct
+ *
+ * Description:
+ * Clone the NetLabel specific sk_security_struct fields from @ssec to
+ * @newssec.
+ *
+ */
+void selinux_netlbl_sk_security_clone(struct sk_security_struct *ssec,
+				      struct sk_security_struct *newssec)
+{
+	/* We don't need to take newssec->nlbl_lock because we are the only
+	 * thread with access to newssec, but we do need to take the RCU read
+	 * lock as other threads could have access to ssec */
+	rcu_read_lock();
+	selinux_netlbl_sk_security_reset(newssec, ssec->sk->sk_family);
+	newssec->sclass = ssec->sclass;
+	rcu_read_unlock();
+}
+
+/**
+ * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
+ * @skb: the packet
+ * @base_sid: the SELinux SID to use as a context for MLS only attributes
+ * @sid: the SID
+ *
+ * Description:
+ * Call the NetLabel mechanism to get the security attributes of the given
+ * packet and use those attributes to determine the correct context/SID to
+ * assign to the packet.  Returns zero on success, negative values on failure.
+ *
+ */
+int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, u32 base_sid, u32 *sid)
+{
+	int rc;
+	struct netlbl_lsm_secattr secattr;
+
+	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);
+	else
+		*sid = SECSID_NULL;
+	netlbl_secattr_destroy(&secattr);
+
+	return rc;
+}
+
+/**
+ * selinux_netlbl_sock_graft - Netlabel the new socket
+ * @sk: the new connection
+ * @sock: the new socket
+ *
+ * Description:
+ * The connection represented by @sk is being grafted onto @sock so set the
+ * socket's NetLabel to match the SID of @sk.
+ *
+ */
+void selinux_netlbl_sock_graft(struct sock *sk, struct socket *sock)
+{
+	struct inode_security_struct *isec = SOCK_INODE(sock)->i_security;
+	struct sk_security_struct *sksec = sk->sk_security;
+	struct netlbl_lsm_secattr secattr;
+	u32 nlbl_peer_sid;
+
+	sksec->sclass = isec->sclass;
+
+	rcu_read_lock();
+
+	if (sksec->nlbl_state != NLBL_REQUIRE) {
+		rcu_read_unlock();
+		return;
+	}
+
+	netlbl_secattr_init(&secattr);
+	if (netlbl_sock_getattr(sk, &secattr) == 0 &&
+	    secattr.flags != NETLBL_SECATTR_NONE &&
+	    security_netlbl_secattr_to_sid(&secattr,
+					   SECINITSID_UNLABELED,
+					   &nlbl_peer_sid) == 0)
+		sksec->peer_sid = nlbl_peer_sid;
+	netlbl_secattr_destroy(&secattr);
+
+	/* Try to set the NetLabel on the socket to save time later, if we fail
+	 * here we will pick up the pieces in later calls to
+	 * selinux_netlbl_inode_permission(). */
+	selinux_netlbl_socket_setsid(sock, sksec->sid);
+
+	rcu_read_unlock();
+}
+
+/**
+ * selinux_netlbl_socket_post_create - Label a socket using NetLabel
+ * @sock: the socket to label
+ *
+ * Description:
+ * Attempt to label a socket using the NetLabel mechanism using the given
+ * SID.  Returns zero values on success, negative values on failure.
+ *
+ */
+int selinux_netlbl_socket_post_create(struct socket *sock)
+{
+	int rc = 0;
+	struct inode_security_struct *isec = SOCK_INODE(sock)->i_security;
+	struct sk_security_struct *sksec = sock->sk->sk_security;
+
+	sksec->sclass = isec->sclass;
+
+	rcu_read_lock();
+	if (sksec->nlbl_state == NLBL_REQUIRE)
+		rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
+	rcu_read_unlock();
+
+	return rc;
+}
+
+/**
+ * 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.
+ *
+ */
+int selinux_netlbl_inode_permission(struct inode *inode, int mask)
+{
+	int rc;
+	struct sk_security_struct *sksec;
+	struct socket *sock;
+
+	if (!S_ISSOCK(inode->i_mode) ||
+	    ((mask & (MAY_WRITE | MAY_APPEND)) == 0))
+		return 0;
+	sock = SOCKET_I(inode);
+	sksec = sock->sk->sk_security;
+
+	rcu_read_lock();
+	if (sksec->nlbl_state != NLBL_REQUIRE) {
+		rcu_read_unlock();
+		return 0;
+	}
+	local_bh_disable();
+	bh_lock_sock_nested(sock->sk);
+	rc = selinux_netlbl_socket_setsid(sock, sksec->sid);
+	bh_unlock_sock(sock->sk);
+	local_bh_enable();
+	rcu_read_unlock();
+
+	return rc;
+}
+
+/**
+ * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
+ * @sksec: the sock's sk_security_struct
+ * @skb: the packet
+ * @ad: the audit data
+ *
+ * Description:
+ * Fetch the NetLabel security attributes from @skb and perform an access check
+ * against the receiving socket.  Returns zero on success, negative values on
+ * error.
+ *
+ */
+int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
+				struct sk_buff *skb,
+				struct avc_audit_data *ad)
+{
+	int rc;
+	u32 netlbl_sid;
+	u32 recv_perm;
+
+	rc = selinux_netlbl_skbuff_getsid(skb,
+					  SECINITSID_UNLABELED,
+					  &netlbl_sid);
+	if (rc != 0)
+		return rc;
+
+	if (netlbl_sid == SECSID_NULL)
+		return 0;
+
+	switch (sksec->sclass) {
+	case SECCLASS_UDP_SOCKET:
+		recv_perm = UDP_SOCKET__RECVFROM;
+		break;
+	case SECCLASS_TCP_SOCKET:
+		recv_perm = TCP_SOCKET__RECVFROM;
+		break;
+	default:
+		recv_perm = RAWIP_SOCKET__RECVFROM;
+	}
+
+	rc = avc_has_perm(sksec->sid,
+			  netlbl_sid,
+			  sksec->sclass,
+			  recv_perm,
+			  ad);
+	if (rc == 0)
+		return 0;
+
+	netlbl_skbuff_err(skb, rc);
+	return rc;
+}
+
+/**
+ * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
+ * @sock: the socket
+ * @level: the socket level or protocol
+ * @optname: the socket option name
+ *
+ * Description:
+ * Check the setsockopt() call and if the user is trying to replace the IP
+ * options on a socket and a NetLabel is in place for the socket deny the
+ * access; otherwise allow the access.  Returns zero when the access is
+ * allowed, -EACCES when denied, and other negative values on error.
+ *
+ */
+int selinux_netlbl_socket_setsockopt(struct socket *sock,
+				     int level,
+				     int optname)
+{
+	int rc = 0;
+	struct sk_security_struct *sksec = sock->sk->sk_security;
+	struct netlbl_lsm_secattr secattr;
+
+	rcu_read_lock();
+	if (level == IPPROTO_IP && optname == IP_OPTIONS &&
+	    sksec->nlbl_state == NLBL_LABELED) {
+		netlbl_secattr_init(&secattr);
+		rc = netlbl_socket_getattr(sock, &secattr);
+		if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
+			rc = -EACCES;
+		netlbl_secattr_destroy(&secattr);
+	}
+	rcu_read_unlock();
+
+	return rc;
+}