linux/security/selinux/netnode.c

// 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 <[email protected]>
 *
 * This code is heavily based on the "netif" concept originally developed by
 * James Morris <[email protected]>
 *   (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 …
#define SEL_NETNODE_HASH_BKT_LIMIT …

struct sel_netnode_bkt { … };

struct sel_netnode { … };

/* 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * 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)
{ … }

/**
 * sel_netnode_flush - Flush the entire network address table
 *
 * Description:
 * Remove all entries from the network address table.
 *
 */
void sel_netnode_flush(void)
{ … }

static __init int sel_netnode_init(void)
{ … }

__initcall(sel_netnode_init);