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@@ -0,0 +1,350 @@
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+/*
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+ * Network node table
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+ *
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+ * SELinux must keep a mapping of network nodes to labels/SIDs. This
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+ * mapping is maintained as part of the normal policy but a fast cache is
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+ * needed to reduce the lookup overhead since most of these queries happen on
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+ * a per-packet basis.
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+ *
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+ * Author: Paul Moore <paul.moore@hp.com>
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+ *
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+ * This code is heavily based on the "netif" concept originally developed by
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+ * James Morris <jmorris@redhat.com>
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+ * (see security/selinux/netif.c for more information)
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+ *
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+ */
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+
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+/*
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+ * (c) Copyright Hewlett-Packard Development Company, L.P., 2007
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+ *
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+ * This program is free software: you can redistribute it and/or modify
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+ * it under the terms of version 2 of the GNU General Public License as
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+ * published by the Free Software Foundation.
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+ *
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+ * This program is distributed in the hope that it will be useful,
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+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
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+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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+ * GNU General Public License for more details.
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+ *
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+ */
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+
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+#include <linux/types.h>
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+#include <linux/rcupdate.h>
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+#include <linux/list.h>
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+#include <linux/spinlock.h>
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+#include <linux/in.h>
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+#include <linux/in6.h>
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+#include <linux/ip.h>
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+#include <linux/ipv6.h>
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+#include <net/ip.h>
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+#include <net/ipv6.h>
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+#include <asm/bug.h>
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+
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+#include "objsec.h"
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+
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+#define SEL_NETNODE_HASH_SIZE 256
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+#define SEL_NETNODE_HASH_BKT_LIMIT 16
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+
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+struct sel_netnode {
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+ struct netnode_security_struct nsec;
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+
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+ struct list_head list;
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+ struct rcu_head rcu;
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+};
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+
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+/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
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+ * for this is that I suspect most users will not make heavy use of both
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+ * address families at the same time so one table will usually end up wasted,
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+ * if this becomes a problem we can always add a hash table for each address
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+ * family later */
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+
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+static LIST_HEAD(sel_netnode_list);
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+static DEFINE_SPINLOCK(sel_netnode_lock);
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+static struct list_head sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
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+
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+/**
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+ * sel_netnode_free - Frees a node entry
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+ * @p: the entry's RCU field
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+ *
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+ * Description:
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+ * This function is designed to be used as a callback to the call_rcu()
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+ * function so that memory allocated to a hash table node entry can be
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+ * released safely.
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+ *
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+ */
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+static void sel_netnode_free(struct rcu_head *p)
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+{
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+ struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
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+ kfree(node);
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+}
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+
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+/**
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+ * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table
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+ * @addr: IPv4 address
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+ *
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+ * Description:
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+ * This is the IPv4 hashing function for the node interface table, it returns
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+ * the bucket number for the given IP address.
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+ *
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+ */
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+static u32 sel_netnode_hashfn_ipv4(__be32 addr)
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+{
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+ /* at some point we should determine if the mismatch in byte order
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+ * affects the hash function dramatically */
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+ return (addr & (SEL_NETNODE_HASH_SIZE - 1));
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+}
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+
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+/**
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+ * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table
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+ * @addr: IPv6 address
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+ *
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+ * Description:
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+ * This is the IPv6 hashing function for the node interface table, it returns
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+ * the bucket number for the given IP address.
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+ *
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+ */
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+static u32 sel_netnode_hashfn_ipv6(const struct in6_addr *addr)
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+{
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+ /* just hash the least significant 32 bits to keep things fast (they
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+ * are the most likely to be different anyway), we can revisit this
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+ * later if needed */
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+ return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1));
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+}
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+
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+/**
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+ * sel_netnode_find - Search for a node record
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+ * @addr: IP address
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+ * @family: address family
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+ *
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+ * Description:
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+ * Search the network node table and return the record matching @addr. If an
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+ * entry can not be found in the table return NULL.
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+ *
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+ */
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+static struct sel_netnode *sel_netnode_find(const void *addr, u16 family)
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+{
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+ u32 idx;
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+ struct sel_netnode *node;
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+
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+ switch (family) {
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+ case PF_INET:
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+ idx = sel_netnode_hashfn_ipv4(*(__be32 *)addr);
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+ break;
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+ case PF_INET6:
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+ idx = sel_netnode_hashfn_ipv6(addr);
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+ break;
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+ default:
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+ BUG();
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+ }
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+
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+ list_for_each_entry_rcu(node, &sel_netnode_hash[idx], list)
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+ if (node->nsec.family == family)
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+ switch (family) {
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+ case PF_INET:
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+ if (node->nsec.addr.ipv4 == *(__be32 *)addr)
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+ return node;
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+ break;
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+ case PF_INET6:
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+ if (ipv6_addr_equal(&node->nsec.addr.ipv6,
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+ addr))
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+ return node;
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+ break;
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+ }
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+
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+ return NULL;
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+}
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+
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+/**
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+ * sel_netnode_insert - Insert a new node into the table
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+ * @node: the new node record
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+ *
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+ * Description:
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+ * Add a new node record to the network address hash table. Returns zero on
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+ * success, negative values on failure.
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+ *
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+ */
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+static int sel_netnode_insert(struct sel_netnode *node)
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+{
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+ u32 idx;
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+ u32 count = 0;
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+ struct sel_netnode *iter;
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+
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+ switch (node->nsec.family) {
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+ case PF_INET:
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+ idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4);
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+ break;
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+ case PF_INET6:
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+ idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6);
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+ break;
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+ default:
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+ BUG();
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+ }
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+ list_add_rcu(&node->list, &sel_netnode_hash[idx]);
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+
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+ /* we need to impose a limit on the growth of the hash table so check
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+ * this bucket to make sure it is within the specified bounds */
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+ list_for_each_entry(iter, &sel_netnode_hash[idx], list)
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+ if (++count > SEL_NETNODE_HASH_BKT_LIMIT) {
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+ list_del_rcu(&iter->list);
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+ call_rcu(&iter->rcu, sel_netnode_free);
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+ break;
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+ }
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+
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+ return 0;
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+}
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+
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+/**
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+ * sel_netnode_destroy - Remove a node record from the table
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+ * @node: the existing node record
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+ *
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+ * Description:
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+ * Remove an existing node record from the network address table.
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+ *
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+ */
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+static void sel_netnode_destroy(struct sel_netnode *node)
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+{
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+ list_del_rcu(&node->list);
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+ call_rcu(&node->rcu, sel_netnode_free);
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+}
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+
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+/**
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+ * sel_netnode_sid_slow - Lookup the SID of a network address using the policy
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+ * @addr: the IP address
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+ * @family: the address family
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+ * @sid: node SID
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+ *
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+ * Description:
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+ * This function determines the SID of a network address by quering the
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+ * security policy. The result is added to the network address table to
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+ * speedup future queries. Returns zero on success, negative values on
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+ * failure.
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+ *
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+ */
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+static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid)
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+{
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+ int ret;
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+ struct sel_netnode *node;
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+ struct sel_netnode *new = NULL;
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+
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+ spin_lock_bh(&sel_netnode_lock);
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+ node = sel_netnode_find(addr, family);
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+ if (node != NULL) {
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+ *sid = node->nsec.sid;
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+ ret = 0;
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+ goto out;
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+ }
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+ new = kzalloc(sizeof(*new), GFP_ATOMIC);
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+ if (new == NULL) {
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+ ret = -ENOMEM;
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+ goto out;
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+ }
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+ switch (family) {
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+ case PF_INET:
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+ ret = security_node_sid(PF_INET,
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+ addr, sizeof(struct in_addr),
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+ &new->nsec.sid);
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+ new->nsec.addr.ipv4 = *(__be32 *)addr;
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+ break;
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+ case PF_INET6:
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+ ret = security_node_sid(PF_INET6,
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+ addr, sizeof(struct in6_addr),
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+ &new->nsec.sid);
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+ ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
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+ break;
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+ default:
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+ BUG();
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+ }
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+ if (ret != 0)
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+ goto out;
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+ new->nsec.family = family;
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+ ret = sel_netnode_insert(new);
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+ if (ret != 0)
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+ goto out;
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+ *sid = new->nsec.sid;
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+
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+out:
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+ spin_unlock_bh(&sel_netnode_lock);
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+ if (ret != 0)
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+ kfree(new);
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+ return ret;
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+}
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+
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+/**
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+ * sel_netnode_sid - Lookup the SID of a network address
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+ * @addr: the IP address
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+ * @family: the address family
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+ * @sid: node SID
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+ *
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+ * Description:
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+ * This function determines the SID of a network address using the fastest
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+ * method possible. First the address table is queried, but if an entry
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+ * can't be found then the policy is queried and the result is added to the
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+ * table to speedup future queries. Returns zero on success, negative values
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+ * on failure.
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+ *
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+ */
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+int sel_netnode_sid(void *addr, u16 family, u32 *sid)
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+{
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+ struct sel_netnode *node;
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+
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+ rcu_read_lock();
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+ node = sel_netnode_find(addr, family);
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+ if (node != NULL) {
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+ *sid = node->nsec.sid;
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+ rcu_read_unlock();
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+ return 0;
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+ }
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+ rcu_read_unlock();
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+
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+ return sel_netnode_sid_slow(addr, family, sid);
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+}
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+
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+/**
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+ * sel_netnode_flush - Flush the entire network address table
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+ *
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+ * Description:
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+ * Remove all entries from the network address table.
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+ *
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+ */
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+static void sel_netnode_flush(void)
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+{
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+ u32 idx;
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+ struct sel_netnode *node;
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+
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+ spin_lock_bh(&sel_netnode_lock);
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+ for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++)
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+ list_for_each_entry(node, &sel_netnode_hash[idx], list)
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+ sel_netnode_destroy(node);
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+ spin_unlock_bh(&sel_netnode_lock);
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+}
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+
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+static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
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+ u16 class, u32 perms, u32 *retained)
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+{
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+ if (event == AVC_CALLBACK_RESET) {
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+ sel_netnode_flush();
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+ synchronize_net();
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+ }
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+ return 0;
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+}
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+
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+static __init int sel_netnode_init(void)
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+{
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+ int iter;
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+ int ret;
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+
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+ if (!selinux_enabled)
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+ return 0;
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+
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+ for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++)
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+ INIT_LIST_HEAD(&sel_netnode_hash[iter]);
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+
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+ ret = avc_add_callback(sel_netnode_avc_callback, AVC_CALLBACK_RESET,
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+ SECSID_NULL, SECSID_NULL, SECCLASS_NULL, 0);
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+ if (ret != 0)
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+ panic("avc_add_callback() failed, error %d\n", ret);
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+
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+ return ret;
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+}
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+
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+__initcall(sel_netnode_init);
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Paul Moore