/*
* Network port table
*
* SELinux must keep a mapping of network ports to labels/SIDs. This
* mapping is maintained as part of the normal policy but a fast cache is
* needed to reduce the lookup overhead.
*
* 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., 2008
*
* 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/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 <asm/bug.h>
#include "netport.h"
#include "objsec.h"
#define SEL_NETPORT_HASH_SIZE 256
#define SEL_NETPORT_HASH_BKT_LIMIT 16
struct sel_netport_bkt {
int size;
struct list_head list;
};
struct sel_netport {
struct netport_security_struct psec;
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_netport_list);
static DEFINE_SPINLOCK(sel_netport_lock);
static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
/**
* sel_netport_free - Frees a port 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 port entry can be
* released safely.
*
*/
static void sel_netport_free(struct rcu_head *p)
{
struct sel_netport *port = container_of(p, struct sel_netport, rcu);
kfree(port);
}
/**
* sel_netport_hashfn - Hashing function for the port table
* @pnum: port number
*
* Description:
* This is the hashing function for the port table, it returns the bucket
* number for the given port.
*
*/
static unsigned int sel_netport_hashfn(u16 pnum)
{
return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
}
/**
* sel_netport_find - Search for a port record
* @protocol: protocol
* @port: pnum
*
* Description:
* Search the network port table and return the matching record. If an entry
* can not be found in the table return NULL.
*
*/
static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
{
unsigned int idx;
struct sel_netport *port;
idx = sel_netport_hashfn(pnum);
list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
if (port->psec.port == pnum && port->psec.protocol == protocol)
return port;
return NULL;
}
/**
* sel_netport_insert - Insert a new port into the table
* @port: the new port record
*
* Description:
* Add a new port record to the network address hash table.
*
*/
static void sel_netport_insert(struct sel_netport *port)
{
unsigned int idx;
/* 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 */
idx = sel_netport_hashfn(port->psec.port);
list_add_rcu(&port->list, &sel_netport_hash[idx].list);
if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
struct sel_netport *tail;
tail = list_entry(
rcu_dereference(sel_netport_hash[idx].list.prev),
struct sel_netport, list);
list_del_rcu(&tail->list);
call_rcu(&tail->rcu, sel_netport_free);
} else
sel_netport_hash[idx].size++;
}
/**
* sel_netport_sid_slow - Lookup the SID of a network address using the policy
* @protocol: protocol
* @pnum: port
* @sid: port SID
*
* Description:
* This function determines the SID of a network port by quering the security
* policy. The result is added to the network port table to speedup future
* queries. Returns zero on success, negative values on failure.
*
*/
static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
{
int ret = -ENOMEM;
struct sel_netport *port;
struct sel_netport *new = NULL;
spin_lock_bh(&sel_netport_lock);
port = sel_netport_find(protocol, pnum);
if (port != NULL) {
*sid = port->psec.sid;
spin_unlock_bh(&sel_netport_lock);
return 0;
}
new = kzalloc(sizeof(*new), GFP_ATOMIC);
if (new == NULL)
goto out;
ret = security_port_sid(protocol, pnum, sid);
if (ret != 0)
goto out;
new->psec.port = pnum;
new->psec.protocol = protocol;
new->psec.sid = *sid;
sel_netport_insert(new);
out:
spin_unlock_bh(&sel_netport_lock);
if (unlikely(ret)) {
printk(KERN_WARNING
"SELinux: failure in sel_netport_sid_slow(),"
" unable to determine network port label\n");
kfree(new);
}
return ret;
}
/**
* sel_netport_sid - Lookup the SID of a network port
* @protocol: protocol
* @pnum: port
* @sid: port SID
*
* Description:
* This function determines the SID of a network port using the fastest method
* possible. First the port 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_netport_sid(u8 protocol, u16 pnum, u32 *sid)
{
struct sel_netport *port;
rcu_read_lock();
port = sel_netport_find(protocol, pnum);
if (port != NULL) {
*sid = port->psec.sid;
rcu_read_unlock();
return 0;
}
rcu_read_unlock();
return sel_netport_sid_slow(protocol, pnum, sid);
}
/**
* sel_netport_flush - Flush the entire network port table
*
* Description:
* Remove all entries from the network address table.
*
*/
static void sel_netport_flush(void)
{
unsigned int idx;
struct sel_netport *port, *port_tmp;
spin_lock_bh(&sel_netport_lock);
for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
list_for_each_entry_safe(port, port_tmp,
&sel_netport_hash[idx].list, list) {
list_del_rcu(&port->list);
call_rcu(&port->rcu, sel_netport_free);
}
sel_netport_hash[idx].size = 0;
}
spin_unlock_bh(&sel_netport_lock);
}
static int sel_netport_avc_callback(u32 event, u32 ssid, u32 tsid,
u16 class, u32 perms, u32 *retained)
{
if (event == AVC_CALLBACK_RESET) {
sel_netport_flush();
synchronize_net();
}
return 0;
}
static __init int sel_netport_init(void)
{
int iter;
int ret;
if (!selinux_enabled)
return 0;
for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
INIT_LIST_HEAD(&sel_netport_hash[iter].list);
sel_netport_hash[iter].size = 0;
}
ret = avc_add_callback(sel_netport_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_netport_init);
