1 files changed, 305 insertions, 0 deletions
diff --git a/security/selinux/netnode.c b/security/selinux/netnode.c
new file mode 100644
index 000000000..5c8c77e50
--- /dev/null
+++ b/security/selinux/netnode.c
@@ -0,0 +1,305 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Network node table
+ *
+ * SELinux must keep a mapping of network nodes to labels/SIDs.  This
+ * mapping is maintained as part of the normal policy but a fast cache is
+ * needed to reduce the lookup overhead since most of these queries happen on
+ * a per-packet basis.
+ *
+ * Author: Paul Moore <paul@paul-moore.com>
+ *
+ * This code is heavily based on the "netif" concept originally developed by
+ * James Morris <jmorris@redhat.com>
+ *   (see security/selinux/netif.c for more information)
+ */
+
+/*
+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
+ */
+
+#include <linux/types.h>
+#include <linux/rcupdate.h>
+#include <linux/list.h>
+#include <linux/slab.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 "netnode.h"
+#include "objsec.h"
+
+#define SEL_NETNODE_HASH_SIZE       256
+#define SEL_NETNODE_HASH_BKT_LIMIT   16
+
+struct sel_netnode_bkt {
+	unsigned int size;
+	struct list_head list;
+};
+
+struct sel_netnode {
+	struct netnode_security_struct nsec;
+
+	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 DEFINE_SPINLOCK(sel_netnode_lock);
+static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
+
+/**
+ * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
+ * @addr: IPv4 address
+ *
+ * Description:
+ * This is the IPv4 hashing function for the node interface table, it returns
+ * the bucket number for the given IP address.
+ *
+ */
+static unsigned int sel_netnode_hashfn_ipv4(__be32 addr)
+{
+	/* at some point we should determine if the mismatch in byte order
+	 * affects the hash function dramatically */
+	return (addr & (SEL_NETNODE_HASH_SIZE - 1));
+}
+
+/**
+ * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
+ * @addr: IPv6 address
+ *
+ * Description:
+ * This is the IPv6 hashing function for the node interface table, it returns
+ * the bucket number for the given IP address.
+ *
+ */
+static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
+{
+	/* just hash the least significant 32 bits to keep things fast (they
+	 * are the most likely to be different anyway), we can revisit this
+	 * later if needed */
+	return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
+}
+
+/**
+ * sel_netnode_find - Search for a node record
+ * @addr: IP address
+ * @family: address family
+ *
+ * Description:
+ * Search the network node table and return the record matching @addr.  If an
+ * entry can not be found in the table return NULL.
+ *
+ */
+static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
+{
+	unsigned int idx;
+	struct sel_netnode *node;
+
+	switch (family) {
+	case PF_INET:
+		idx = sel_netnode_hashfn_ipv4(*(const __be32 *)addr);
+		break;
+	case PF_INET6:
+		idx = sel_netnode_hashfn_ipv6(addr);
+		break;
+	default:
+		BUG();
+		return NULL;
+	}
+
+	list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list)
+		if (node->nsec.family == family)
+			switch (family) {
+			case PF_INET:
+				if (node->nsec.addr.ipv4 == *(const __be32 *)addr)
+					return node;
+				break;
+			case PF_INET6:
+				if (ipv6_addr_equal(&node->nsec.addr.ipv6,
+						    addr))
+					return node;
+				break;
+			}
+
+	return NULL;
+}
+
+/**
+ * sel_netnode_insert - Insert a new node into the table
+ * @node: the new node record
+ *
+ * Description:
+ * Add a new node record to the network address hash table.
+ *
+ */
+static void sel_netnode_insert(struct sel_netnode *node)
+{
+	unsigned int idx;
+
+	switch (node->nsec.family) {
+	case PF_INET:
+		idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
+		break;
+	case PF_INET6:
+		idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
+		break;
+	default:
+		BUG();
+		return;
+	}
+
+	/* 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 */
+	list_add_rcu(&node->list, &sel_netnode_hash[idx].list);
+	if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) {
+		struct sel_netnode *tail;
+		tail = list_entry(
+			rcu_dereference_protected(
+				list_tail_rcu(&sel_netnode_hash[idx].list),
+				lockdep_is_held(&sel_netnode_lock)),
+			struct sel_netnode, list);
+		list_del_rcu(&tail->list);
+		kfree_rcu(tail, rcu);
+	} else
+		sel_netnode_hash[idx].size++;
+}
+
+/**
+ * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
+ * @addr: the IP address
+ * @family: the address family
+ * @sid: node SID
+ *
+ * Description:
+ * This function determines the SID of a network address by querying the
+ * security policy.  The result is added to the network address table to
+ * speedup future queries.  Returns zero on success, negative values on
+ * failure.
+ *
+ */
+static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
+{
+	int ret;
+	struct sel_netnode *node;
+	struct sel_netnode *new;
+
+	spin_lock_bh(&sel_netnode_lock);
+	node = sel_netnode_find(addr, family);
+	if (node != NULL) {
+		*sid = node->nsec.sid;
+		spin_unlock_bh(&sel_netnode_lock);
+		return 0;
+	}
+
+	new = kzalloc(sizeof(*new), GFP_ATOMIC);
+	switch (family) {
+	case PF_INET:
+		ret = security_node_sid(PF_INET,
+					addr, sizeof(struct in_addr), sid);
+		if (new)
+			new->nsec.addr.ipv4 = *(__be32 *)addr;
+		break;
+	case PF_INET6:
+		ret = security_node_sid(PF_INET6,
+					addr, sizeof(struct in6_addr), sid);
+		if (new)
+			new->nsec.addr.ipv6 = *(struct in6_addr *)addr;
+		break;
+	default:
+		BUG();
+		ret = -EINVAL;
+	}
+	if (ret == 0 && new) {
+		new->nsec.family = family;
+		new->nsec.sid = *sid;
+		sel_netnode_insert(new);
+	} else
+		kfree(new);
+
+	spin_unlock_bh(&sel_netnode_lock);
+	if (unlikely(ret))
+		pr_warn("SELinux: failure in %s(), unable to determine network node label\n",
+			__func__);
+	return ret;
+}
+
+/**
+ * sel_netnode_sid - Lookup the SID of a network address
+ * @addr: the IP address
+ * @family: the address family
+ * @sid: node SID
+ *
+ * Description:
+ * This function determines the SID of a network address using the fastest
+ * method possible.  First the address 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_netnode_sid(void *addr, u16 family, u32 *sid)
+{
+	struct sel_netnode *node;
+
+	rcu_read_lock();
+	node = sel_netnode_find(addr, family);
+	if (node != NULL) {
+		*sid = node->nsec.sid;
+		rcu_read_unlock();
+		return 0;
+	}
+	rcu_read_unlock();
+
+	return sel_netnode_sid_slow(addr, family, sid);
+}
+
+/**
+ * sel_netnode_flush - Flush the entire network address table
+ *
+ * Description:
+ * Remove all entries from the network address table.
+ *
+ */
+void sel_netnode_flush(void)
+{
+	unsigned int idx;
+	struct sel_netnode *node, *node_tmp;
+
+	spin_lock_bh(&sel_netnode_lock);
+	for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) {
+		list_for_each_entry_safe(node, node_tmp,
+					 &sel_netnode_hash[idx].list, list) {
+				list_del_rcu(&node->list);
+				kfree_rcu(node, rcu);
+		}
+		sel_netnode_hash[idx].size = 0;
+	}
+	spin_unlock_bh(&sel_netnode_lock);
+}
+
+static __init int sel_netnode_init(void)
+{
+	int iter;
+
+	if (!selinux_enabled_boot)
+		return 0;
+
+	for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) {
+		INIT_LIST_HEAD(&sel_netnode_hash[iter].list);
+		sel_netnode_hash[iter].size = 0;
+	}
+
+	return 0;
+}
+
+__initcall(sel_netnode_init);