282 lines
7.1 KiB
C
282 lines
7.1 KiB
C
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/*
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* Network port table
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*
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* SELinux must keep a mapping of network ports 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.
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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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* (c) Copyright Hewlett-Packard Development Company, L.P., 2008
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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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#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 "netport.h"
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#include "objsec.h"
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#define SEL_NETPORT_HASH_SIZE 256
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#define SEL_NETPORT_HASH_BKT_LIMIT 16
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struct sel_netport_bkt {
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int size;
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struct list_head list;
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};
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struct sel_netport {
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struct netport_security_struct psec;
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struct list_head list;
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struct rcu_head rcu;
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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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static LIST_HEAD(sel_netport_list);
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static DEFINE_SPINLOCK(sel_netport_lock);
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static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
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/**
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* sel_netport_free - Frees a port 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 port entry can be
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* released safely.
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*
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*/
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static void sel_netport_free(struct rcu_head *p)
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{
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struct sel_netport *port = container_of(p, struct sel_netport, rcu);
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kfree(port);
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}
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/**
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* sel_netport_hashfn - Hashing function for the port table
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* @pnum: port number
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*
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* Description:
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* This is the hashing function for the port table, it returns the bucket
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* number for the given port.
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*
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*/
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static unsigned int sel_netport_hashfn(u16 pnum)
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{
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return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
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}
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/**
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* sel_netport_find - Search for a port record
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* @protocol: protocol
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* @port: pnum
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*
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* Description:
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* Search the network port table and return the matching record. If an entry
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* can not be found in the table return NULL.
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*
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*/
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static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
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{
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unsigned int idx;
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struct sel_netport *port;
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idx = sel_netport_hashfn(pnum);
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list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
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if (port->psec.port == pnum && port->psec.protocol == protocol)
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return port;
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return NULL;
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}
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/**
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* sel_netport_insert - Insert a new port into the table
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* @port: the new port record
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*
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* Description:
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* Add a new port record to the network address hash table.
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*
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*/
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static void sel_netport_insert(struct sel_netport *port)
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{
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unsigned int idx;
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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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idx = sel_netport_hashfn(port->psec.port);
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list_add_rcu(&port->list, &sel_netport_hash[idx].list);
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if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
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struct sel_netport *tail;
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tail = list_entry(
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rcu_dereference(sel_netport_hash[idx].list.prev),
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struct sel_netport, list);
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list_del_rcu(&tail->list);
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call_rcu(&tail->rcu, sel_netport_free);
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} else
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sel_netport_hash[idx].size++;
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}
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/**
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* sel_netport_sid_slow - Lookup the SID of a network address using the policy
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* @protocol: protocol
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* @pnum: port
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* @sid: port SID
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*
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* Description:
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* This function determines the SID of a network port by quering the security
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* policy. The result is added to the network port table to speedup future
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* queries. Returns zero on success, negative values on failure.
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*
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*/
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static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
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{
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int ret = -ENOMEM;
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struct sel_netport *port;
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struct sel_netport *new = NULL;
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spin_lock_bh(&sel_netport_lock);
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port = sel_netport_find(protocol, pnum);
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if (port != NULL) {
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*sid = port->psec.sid;
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spin_unlock_bh(&sel_netport_lock);
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return 0;
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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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goto out;
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ret = security_port_sid(protocol, pnum, sid);
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if (ret != 0)
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goto out;
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new->psec.port = pnum;
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new->psec.protocol = protocol;
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new->psec.sid = *sid;
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sel_netport_insert(new);
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out:
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spin_unlock_bh(&sel_netport_lock);
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if (unlikely(ret)) {
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printk(KERN_WARNING
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"SELinux: failure in sel_netport_sid_slow(),"
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" unable to determine network port label\n");
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kfree(new);
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}
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return ret;
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}
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/**
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* sel_netport_sid - Lookup the SID of a network port
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* @protocol: protocol
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* @pnum: port
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* @sid: port SID
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*
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* Description:
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* This function determines the SID of a network port using the fastest method
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* possible. First the port table is queried, but if an entry can't be found
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* then the policy is queried and the result is added to the table to speedup
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* future queries. Returns zero on success, negative values on failure.
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*
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*/
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int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
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{
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struct sel_netport *port;
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rcu_read_lock();
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port = sel_netport_find(protocol, pnum);
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if (port != NULL) {
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*sid = port->psec.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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return sel_netport_sid_slow(protocol, pnum, sid);
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}
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/**
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* sel_netport_flush - Flush the entire network port 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_netport_flush(void)
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{
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unsigned int idx;
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struct sel_netport *port, *port_tmp;
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spin_lock_bh(&sel_netport_lock);
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for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
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list_for_each_entry_safe(port, port_tmp,
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&sel_netport_hash[idx].list, list) {
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list_del_rcu(&port->list);
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call_rcu(&port->rcu, sel_netport_free);
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}
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sel_netport_hash[idx].size = 0;
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}
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spin_unlock_bh(&sel_netport_lock);
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}
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static int sel_netport_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_netport_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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static __init int sel_netport_init(void)
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{
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int iter;
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int ret;
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if (!selinux_enabled)
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return 0;
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for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
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INIT_LIST_HEAD(&sel_netport_hash[iter].list);
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sel_netport_hash[iter].size = 0;
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}
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ret = avc_add_callback(sel_netport_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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return ret;
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}
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__initcall(sel_netport_init);
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