linux/security/selinux/netport.c
Paul Moore 82c21bfab4 doc: Update the email address for Paul Moore in various source files
My @hp.com will no longer be valid starting August 5, 2011 so an update is
necessary.  My new email address is employer independent so we don't have
to worry about doing this again any time soon.

Signed-off-by: Paul Moore <paul.moore@hp.com>
Signed-off-by: Paul Moore <paul@paul-moore.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
2011-08-01 17:58:33 -07:00

267 lines
6.7 KiB
C

/*
* 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@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., 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/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 "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_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);
kfree_rcu(tail, rcu);
} 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);
kfree_rcu(port, rcu);
}
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);