SELinux: add netport.[ch]

Thank you, git.

Signed-off-by: James Morris <[e-mail]>

security/selinux/include/netport.h

···
+/*
+ * Network port table
+ *
+ * SELinux must keep a mapping of network ports to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead.
+ *
+ * Author: Paul Moore <[e-mail]>
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ */
+
+#ifndef _SELINUX_NETPORT_H
+#define _SELINUX_NETPORT_H
+
+int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid);
+
+#endif

security/selinux/netport.c

···
+/*
+ * Network port table
+ *
+ * SELinux must keep a mapping of network ports to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead.
+ *
+ * Author: Paul Moore <[e-mail]>
+ *
+ * This code is heavily based on the "netif" concept originally developed by
+ * James Morris <[e-mail]>
+ *   (see security/selinux/netif.c for more information)
+ *
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
+ *
+ * This program is free software: you can redistribute it and/or modify
+ * it under the terms of version 2 of the GNU General Public License as
+ * published by the Free Software Foundation.
+ *
+ * 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.
+ *
+ */
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/spinlock.h>
+#include <linux/in.h>
+#include <linux/in6.h>
+#include <linux/ip.h>
+#include <linux/ipv6.h>
+#include <net/ip.h>
+#include <net/ipv6.h>
+#include <asm/bug.h>
+
+#include "netport.h"
+#include "objsec.h"
+
+#define SEL_NETPORT_HASH_SIZE       256
+#define SEL_NETPORT_HASH_BKT_LIMIT   16
+
+struct sel_netport_bkt {
+	int size;
+	struct list_head list;
+};
+
+struct sel_netport {
+	struct netport_security_struct psec;
+
+	struct list_head list;
+	struct rcu_head rcu;
+};
+
+/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
+ * for this is that I suspect most users will not make heavy use of both
+ * address families at the same time so one table will usually end up wasted,
+ * if this becomes a problem we can always add a hash table for each address
+ * family later */
+
+static LIST_HEAD(sel_netport_list);
+static DEFINE_SPINLOCK(sel_netport_lock);
+static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
+
+/**
+ * sel_netport_free - Frees a port entry
+ * @p: the entry's RCU field
+ *
+ * Description:
+ * This function is designed to be used as a callback to the call_rcu()
+ * function so that memory allocated to a hash table port entry can be
+ * released safely.
+ *
+ */
+static void sel_netport_free(struct rcu_head *p)
+{
+	struct sel_netport *port = container_of(p, struct sel_netport, rcu);
+	kfree(port);
+}
+
+/**
+ * sel_netport_hashfn - Hashing function for the port table
+ * @pnum: port number
+ *
+ * Description:
+ * This is the hashing function for the port table, it returns the bucket
+ * number for the given port.
+ *
+ */
+static unsigned int sel_netport_hashfn(u16 pnum)
+{
+	return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
+}
+
+/**
+ * sel_netport_find - Search for a port record
+ * @protocol: protocol
+ * @port: pnum
+ *
+ * Description:
+ * Search the network port table and return the matching record.  If an entry
+ * can not be found in the table return NULL.
+ *
+ */
+static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
+{
+	unsigned int idx;
+	struct sel_netport *port;
+
+	idx = sel_netport_hashfn(pnum);
+	list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
+		if (port->psec.port == pnum &&
+		    port->psec.protocol == protocol)
+			return port;
+
+	return NULL;
+}
+
+/**
+ * sel_netport_insert - Insert a new port into the table
+ * @port: the new port record
+ *
+ * Description:
+ * Add a new port record to the network address hash table.  Returns zero on
+ * success, negative values on failure.
+ *
+ */
+static int sel_netport_insert(struct sel_netport *port)
+{
+	unsigned int idx;
+
+	/* we need to impose a limit on the growth of the hash table so check
+	 * this bucket to make sure it is within the specified bounds */
+	idx = sel_netport_hashfn(port->psec.port);
+	list_add_rcu(&port->list, &sel_netport_hash[idx].list);
+	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
+		struct sel_netport *tail;
+		tail = list_entry(port->list.prev, struct sel_netport, list);
+		list_del_rcu(port->list.prev);
+		call_rcu(&tail->rcu, sel_netport_free);
+	} else
+		sel_netport_hash[idx].size++;
+
+	return 0;
+}
+
+/**
+ * sel_netport_sid_slow - Lookup the SID of a network address using the policy
+ * @protocol: protocol
+ * @pnum: port
+ * @sid: port SID
+ *
+ * Description:
+ * This function determines the SID of a network port by quering the security
+ * policy.  The result is added to the network port table to speedup future
+ * queries.  Returns zero on success, negative values on failure.
+ *
+ */
+static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
+{
+	int ret;
+	struct sel_netport *port;
+	struct sel_netport *new = NULL;
+
+	spin_lock_bh(&sel_netport_lock);
+	port = sel_netport_find(protocol, pnum);
+	if (port != NULL) {
+		*sid = port->psec.sid;
+		ret = 0;
+		goto out;
+	}
+	new = kzalloc(sizeof(*new), GFP_ATOMIC);
+	if (new == NULL) {
+		ret = -ENOMEM;
+		goto out;
+	}
+	ret = security_port_sid(protocol, pnum, &new->psec.sid);
+	if (ret != 0)
+		goto out;
+	new->psec.port = pnum;
+	new->psec.protocol = protocol;
+	ret = sel_netport_insert(new);
+	if (ret != 0)
+		goto out;
+	*sid = new->psec.sid;
+
+out:
+	spin_unlock_bh(&sel_netport_lock);
+	if (unlikely(ret)) {
+		printk(KERN_WARNING
+		       "SELinux: failure in sel_netport_sid_slow(),"
+		       " unable to determine network port label\n");
+		kfree(new);
+	}
+	return ret;
+}
+
+/**
+ * sel_netport_sid - Lookup the SID of a network port
+ * @protocol: protocol
+ * @pnum: port
+ * @sid: port SID
+ *
+ * Description:
+ * This function determines the SID of a network port using the fastest method
+ * possible.  First the port table is queried, but if an entry can't be found
+ * then the policy is queried and the result is added to the table to speedup
+ * future queries.  Returns zero on success, negative values on failure.
+ *
+ */
+int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
+{
+	struct sel_netport *port;
+
+	rcu_read_lock();
+	port = sel_netport_find(protocol, pnum);
+	if (port != NULL) {
+		*sid = port->psec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_netport_sid_slow(protocol, pnum, sid);
+}
+
+/**
+ * sel_netport_flush - Flush the entire network port table
+ *
+ * Description:
+ * Remove all entries from the network address table.
+ *
+ */
+static void sel_netport_flush(void)
+{
+	unsigned int idx;
+	struct sel_netport *port;
+
+	spin_lock_bh(&sel_netport_lock);
+	for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
+		list_for_each_entry(port, &sel_netport_hash[idx].list, list) {
+			list_del_rcu(&port->list);
+			call_rcu(&port->rcu, sel_netport_free);
+		}
+		sel_netport_hash[idx].size = 0;
+	}
+	spin_unlock_bh(&sel_netport_lock);
+}
+
+static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
+				    u16 class, u32 perms, u32 *retained)
+{
+	if (event == AVC_CALLBACK_RESET) {
+		sel_netport_flush();
+		synchronize_net();
+	}
+	return 0;
+}
+
+static __init int sel_netport_init(void)
+{
+	int iter;
+	int ret;
+
+	if (!selinux_enabled)
+		return 0;
+
+	for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
+		INIT_LIST_HEAD(&sel_netport_hash[iter].list);
+		sel_netport_hash[iter].size = 0;
+	}
+
+	ret = avc_add_callback(sel_netport_avc_callback, AVC_CALLBACK_RESET,
+	                       SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
+	if (ret != 0)
+		panic("avc_add_callback() failed, error %d\n", ret);
+
+	return ret;
+}
+
+__initcall(sel_netport_init);