/*
* 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.moore@hp.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
*
* 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/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 LIST_HEAD(sel_netnode_list);
static DEFINE_SPINLOCK(sel_netnode_lock);
static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE];
/**
* sel_netnode_free - Frees a node 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 node entry can be
* released safely.
*
*/
static void sel_netnode_free(struct rcu_head *p)
{
struct sel_netnode *node = container_of(p, struct sel_netnode, rcu);
kfree(node);
}
/**
* 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(*(__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 == *(__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();
}
/* 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(sel_netnode_hash[idx].list.prev),
struct sel_netnode, list);
list_del_rcu(&tail->list);
call_rcu(&tail->rcu, sel_netnode_free);
} 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 quering 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 = -ENOMEM;
struct sel_netnode *node;
struct sel_netnode *new = NULL;
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);
if (new == NULL)
goto out;
switch (family) {
case PF_INET:
ret = security_node_sid(PF_INET,
addr, sizeof(struct in_addr), sid);
new->nsec.addr.ipv4 = *(__be32 *)addr;
break;
case PF_INET6:
ret = security_node_sid(PF_INET6,
addr, sizeof(struct in6_addr), sid);
ipv6_addr_copy(&new->nsec.addr.ipv6, addr);
break;
default:
BUG();
}
if (ret != 0)
goto out;
new->nsec.family = family;
new->nsec.sid = *sid;
sel_netnode_insert(new);
out:
spin_unlock_bh(&sel_netnode_lock);
if (unlikely(ret)) {
printk(KERN_WARNING
"SELinux: failure in sel_netnode_sid_slow(),"
" unable to determine network node label\n");
kfree(new);
}
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.
*
*/
static 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);
call_rcu(&node->rcu, sel_netnode_free);
}
sel_netnode_hash[idx].size = 0;
}
spin_unlock_bh(&sel_netnode_lock);
}
static int sel_netnode_avc_callback(u32 event, u32 ssid, u32 tsid,
u16 class, u32 perms, u32 *retained)
{
if (event == AVC_CALLBACK_RESET) {
sel_netnode_flush();
synchronize_net();
}
return 0;
}
static __init int sel_netnode_init(void)
{
int iter;
int ret;
if (!selinux_enabled)
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;
}
ret = avc_add_callback(sel_netnode_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_netnode_init);
