1 files changed, 281 insertions, 0 deletions
diff --git a/security/selinux/netif.c b/security/selinux/netif.c
new file mode 100644
index 000000000..86813b46f
--- /dev/null
+++ b/security/selinux/netif.c
@@ -0,0 +1,281 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Network interface table.
+ *
+ * Network interfaces (devices) do not have a security field, so we
+ * maintain a table associating each interface with a SID.
+ *
+ * Author: James Morris <jmorris@redhat.com>
+ *
+ * Copyright (C) 2003 Red Hat, Inc., James Morris <jmorris@redhat.com>
+ * Copyright (C) 2007 Hewlett-Packard Development Company, L.P.
+ *		      Paul Moore <paul@paul-moore.com>
+ */
+#include <linux/init.h>
+#include <linux/types.h>
+#include <linux/slab.h>
+#include <linux/stddef.h>
+#include <linux/kernel.h>
+#include <linux/list.h>
+#include <linux/notifier.h>
+#include <linux/netdevice.h>
+#include <linux/rcupdate.h>
+#include <net/net_namespace.h>
+
+#include "security.h"
+#include "objsec.h"
+#include "netif.h"
+
+#define SEL_NETIF_HASH_SIZE	64
+#define SEL_NETIF_HASH_MAX	1024
+
+struct sel_netif {
+	struct list_head list;
+	struct netif_security_struct nsec;
+	struct rcu_head rcu_head;
+};
+
+static u32 sel_netif_total;
+static LIST_HEAD(sel_netif_list);
+static DEFINE_SPINLOCK(sel_netif_lock);
+static struct list_head sel_netif_hash[SEL_NETIF_HASH_SIZE];
+
+/**
+ * sel_netif_hashfn - Hashing function for the interface table
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * This is the hashing function for the network interface table, it returns the
+ * bucket number for the given interface.
+ *
+ */
+static inline u32 sel_netif_hashfn(const struct net *ns, int ifindex)
+{
+	return (((uintptr_t)ns + ifindex) & (SEL_NETIF_HASH_SIZE - 1));
+}
+
+/**
+ * sel_netif_find - Search for an interface record
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * Search the network interface table and return the record matching @ifindex.
+ * If an entry can not be found in the table return NULL.
+ *
+ */
+static inline struct sel_netif *sel_netif_find(const struct net *ns,
+					       int ifindex)
+{
+	int idx = sel_netif_hashfn(ns, ifindex);
+	struct sel_netif *netif;
+
+	list_for_each_entry_rcu(netif, &sel_netif_hash[idx], list)
+		if (net_eq(netif->nsec.ns, ns) &&
+		    netif->nsec.ifindex == ifindex)
+			return netif;
+
+	return NULL;
+}
+
+/**
+ * sel_netif_insert - Insert a new interface into the table
+ * @netif: the new interface record
+ *
+ * Description:
+ * Add a new interface record to the network interface hash table.  Returns
+ * zero on success, negative values on failure.
+ *
+ */
+static int sel_netif_insert(struct sel_netif *netif)
+{
+	int idx;
+
+	if (sel_netif_total >= SEL_NETIF_HASH_MAX)
+		return -ENOSPC;
+
+	idx = sel_netif_hashfn(netif->nsec.ns, netif->nsec.ifindex);
+	list_add_rcu(&netif->list, &sel_netif_hash[idx]);
+	sel_netif_total++;
+
+	return 0;
+}
+
+/**
+ * sel_netif_destroy - Remove an interface record from the table
+ * @netif: the existing interface record
+ *
+ * Description:
+ * Remove an existing interface record from the network interface table.
+ *
+ */
+static void sel_netif_destroy(struct sel_netif *netif)
+{
+	list_del_rcu(&netif->list);
+	sel_netif_total--;
+	kfree_rcu(netif, rcu_head);
+}
+
+/**
+ * sel_netif_sid_slow - Lookup the SID of a network interface using the policy
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ * @sid: interface SID
+ *
+ * Description:
+ * This function determines the SID of a network interface by querying the
+ * security policy.  The result is added to the network interface table to
+ * speedup future queries.  Returns zero on success, negative values on
+ * failure.
+ *
+ */
+static int sel_netif_sid_slow(struct net *ns, int ifindex, u32 *sid)
+{
+	int ret = 0;
+	struct sel_netif *netif;
+	struct sel_netif *new;
+	struct net_device *dev;
+
+	/* NOTE: we always use init's network namespace since we don't
+	 * currently support containers */
+
+	dev = dev_get_by_index(ns, ifindex);
+	if (unlikely(dev == NULL)) {
+		pr_warn("SELinux: failure in %s(), invalid network interface (%d)\n",
+			__func__, ifindex);
+		return -ENOENT;
+	}
+
+	spin_lock_bh(&sel_netif_lock);
+	netif = sel_netif_find(ns, ifindex);
+	if (netif != NULL) {
+		*sid = netif->nsec.sid;
+		goto out;
+	}
+
+	ret = security_netif_sid(&selinux_state, dev->name, sid);
+	if (ret != 0)
+		goto out;
+	new = kzalloc(sizeof(*new), GFP_ATOMIC);
+	if (new) {
+		new->nsec.ns = ns;
+		new->nsec.ifindex = ifindex;
+		new->nsec.sid = *sid;
+		if (sel_netif_insert(new))
+			kfree(new);
+	}
+
+out:
+	spin_unlock_bh(&sel_netif_lock);
+	dev_put(dev);
+	if (unlikely(ret))
+		pr_warn("SELinux: failure in %s(), unable to determine network interface label (%d)\n",
+			__func__, ifindex);
+	return ret;
+}
+
+/**
+ * sel_netif_sid - Lookup the SID of a network interface
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ * @sid: interface SID
+ *
+ * Description:
+ * This function determines the SID of a network interface using the fastest
+ * method possible.  First the interface 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_netif_sid(struct net *ns, int ifindex, u32 *sid)
+{
+	struct sel_netif *netif;
+
+	rcu_read_lock();
+	netif = sel_netif_find(ns, ifindex);
+	if (likely(netif != NULL)) {
+		*sid = netif->nsec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_netif_sid_slow(ns, ifindex, sid);
+}
+
+/**
+ * sel_netif_kill - Remove an entry from the network interface table
+ * @ns: the network namespace
+ * @ifindex: the network interface
+ *
+ * Description:
+ * This function removes the entry matching @ifindex from the network interface
+ * table if it exists.
+ *
+ */
+static void sel_netif_kill(const struct net *ns, int ifindex)
+{
+	struct sel_netif *netif;
+
+	rcu_read_lock();
+	spin_lock_bh(&sel_netif_lock);
+	netif = sel_netif_find(ns, ifindex);
+	if (netif)
+		sel_netif_destroy(netif);
+	spin_unlock_bh(&sel_netif_lock);
+	rcu_read_unlock();
+}
+
+/**
+ * sel_netif_flush - Flush the entire network interface table
+ *
+ * Description:
+ * Remove all entries from the network interface table.
+ *
+ */
+void sel_netif_flush(void)
+{
+	int idx;
+	struct sel_netif *netif;
+
+	spin_lock_bh(&sel_netif_lock);
+	for (idx = 0; idx < SEL_NETIF_HASH_SIZE; idx++)
+		list_for_each_entry(netif, &sel_netif_hash[idx], list)
+			sel_netif_destroy(netif);
+	spin_unlock_bh(&sel_netif_lock);
+}
+
+static int sel_netif_netdev_notifier_handler(struct notifier_block *this,
+					     unsigned long event, void *ptr)
+{
+	struct net_device *dev = netdev_notifier_info_to_dev(ptr);
+
+	if (event == NETDEV_DOWN)
+		sel_netif_kill(dev_net(dev), dev->ifindex);
+
+	return NOTIFY_DONE;
+}
+
+static struct notifier_block sel_netif_netdev_notifier = {
+	.notifier_call = sel_netif_netdev_notifier_handler,
+};
+
+static __init int sel_netif_init(void)
+{
+	int i;
+
+	if (!selinux_enabled_boot)
+		return 0;
+
+	for (i = 0; i < SEL_NETIF_HASH_SIZE; i++)
+		INIT_LIST_HEAD(&sel_netif_hash[i]);
+
+	register_netdevice_notifier(&sel_netif_netdev_notifier);
+
+	return 0;
+}
+
+__initcall(sel_netif_init);
+