cachepc-linux

Fork of AMDESE/linux with modifications for CachePC side-channel attack
git clone https://git.sinitax.com/sinitax/cachepc-linux
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netport.c (5968B)


      1// SPDX-License-Identifier: GPL-2.0-only
      2/*
      3 * Network port table
      4 *
      5 * SELinux must keep a mapping of network ports to labels/SIDs.  This
      6 * mapping is maintained as part of the normal policy but a fast cache is
      7 * needed to reduce the lookup overhead.
      8 *
      9 * Author: Paul Moore <paul@paul-moore.com>
     10 *
     11 * This code is heavily based on the "netif" concept originally developed by
     12 * James Morris <jmorris@redhat.com>
     13 *   (see security/selinux/netif.c for more information)
     14 */
     15
     16/*
     17 * (c) Copyright Hewlett-Packard Development Company, L.P., 2008
     18 */
     19
     20#include <linux/types.h>
     21#include <linux/rcupdate.h>
     22#include <linux/list.h>
     23#include <linux/slab.h>
     24#include <linux/spinlock.h>
     25#include <linux/in.h>
     26#include <linux/in6.h>
     27#include <linux/ip.h>
     28#include <linux/ipv6.h>
     29#include <net/ip.h>
     30#include <net/ipv6.h>
     31
     32#include "netport.h"
     33#include "objsec.h"
     34
     35#define SEL_NETPORT_HASH_SIZE       256
     36#define SEL_NETPORT_HASH_BKT_LIMIT   16
     37
     38struct sel_netport_bkt {
     39	int size;
     40	struct list_head list;
     41};
     42
     43struct sel_netport {
     44	struct netport_security_struct psec;
     45
     46	struct list_head list;
     47	struct rcu_head rcu;
     48};
     49
     50/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason
     51 * for this is that I suspect most users will not make heavy use of both
     52 * address families at the same time so one table will usually end up wasted,
     53 * if this becomes a problem we can always add a hash table for each address
     54 * family later */
     55
     56static DEFINE_SPINLOCK(sel_netport_lock);
     57static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE];
     58
     59/**
     60 * sel_netport_hashfn - Hashing function for the port table
     61 * @pnum: port number
     62 *
     63 * Description:
     64 * This is the hashing function for the port table, it returns the bucket
     65 * number for the given port.
     66 *
     67 */
     68static unsigned int sel_netport_hashfn(u16 pnum)
     69{
     70	return (pnum & (SEL_NETPORT_HASH_SIZE - 1));
     71}
     72
     73/**
     74 * sel_netport_find - Search for a port record
     75 * @protocol: protocol
     76 * @pnum: port
     77 *
     78 * Description:
     79 * Search the network port table and return the matching record.  If an entry
     80 * can not be found in the table return NULL.
     81 *
     82 */
     83static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum)
     84{
     85	unsigned int idx;
     86	struct sel_netport *port;
     87
     88	idx = sel_netport_hashfn(pnum);
     89	list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list)
     90		if (port->psec.port == pnum && port->psec.protocol == protocol)
     91			return port;
     92
     93	return NULL;
     94}
     95
     96/**
     97 * sel_netport_insert - Insert a new port into the table
     98 * @port: the new port record
     99 *
    100 * Description:
    101 * Add a new port record to the network address hash table.
    102 *
    103 */
    104static void sel_netport_insert(struct sel_netport *port)
    105{
    106	unsigned int idx;
    107
    108	/* we need to impose a limit on the growth of the hash table so check
    109	 * this bucket to make sure it is within the specified bounds */
    110	idx = sel_netport_hashfn(port->psec.port);
    111	list_add_rcu(&port->list, &sel_netport_hash[idx].list);
    112	if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) {
    113		struct sel_netport *tail;
    114		tail = list_entry(
    115			rcu_dereference_protected(
    116				list_tail_rcu(&sel_netport_hash[idx].list),
    117				lockdep_is_held(&sel_netport_lock)),
    118			struct sel_netport, list);
    119		list_del_rcu(&tail->list);
    120		kfree_rcu(tail, rcu);
    121	} else
    122		sel_netport_hash[idx].size++;
    123}
    124
    125/**
    126 * sel_netport_sid_slow - Lookup the SID of a network address using the policy
    127 * @protocol: protocol
    128 * @pnum: port
    129 * @sid: port SID
    130 *
    131 * Description:
    132 * This function determines the SID of a network port by querying the security
    133 * policy.  The result is added to the network port table to speedup future
    134 * queries.  Returns zero on success, negative values on failure.
    135 *
    136 */
    137static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid)
    138{
    139	int ret;
    140	struct sel_netport *port;
    141	struct sel_netport *new;
    142
    143	spin_lock_bh(&sel_netport_lock);
    144	port = sel_netport_find(protocol, pnum);
    145	if (port != NULL) {
    146		*sid = port->psec.sid;
    147		spin_unlock_bh(&sel_netport_lock);
    148		return 0;
    149	}
    150
    151	ret = security_port_sid(&selinux_state, protocol, pnum, sid);
    152	if (ret != 0)
    153		goto out;
    154	new = kzalloc(sizeof(*new), GFP_ATOMIC);
    155	if (new) {
    156		new->psec.port = pnum;
    157		new->psec.protocol = protocol;
    158		new->psec.sid = *sid;
    159		sel_netport_insert(new);
    160	}
    161
    162out:
    163	spin_unlock_bh(&sel_netport_lock);
    164	if (unlikely(ret))
    165		pr_warn("SELinux: failure in %s(), unable to determine network port label\n",
    166			__func__);
    167	return ret;
    168}
    169
    170/**
    171 * sel_netport_sid - Lookup the SID of a network port
    172 * @protocol: protocol
    173 * @pnum: port
    174 * @sid: port SID
    175 *
    176 * Description:
    177 * This function determines the SID of a network port using the fastest method
    178 * possible.  First the port table is queried, but if an entry can't be found
    179 * then the policy is queried and the result is added to the table to speedup
    180 * future queries.  Returns zero on success, negative values on failure.
    181 *
    182 */
    183int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid)
    184{
    185	struct sel_netport *port;
    186
    187	rcu_read_lock();
    188	port = sel_netport_find(protocol, pnum);
    189	if (port != NULL) {
    190		*sid = port->psec.sid;
    191		rcu_read_unlock();
    192		return 0;
    193	}
    194	rcu_read_unlock();
    195
    196	return sel_netport_sid_slow(protocol, pnum, sid);
    197}
    198
    199/**
    200 * sel_netport_flush - Flush the entire network port table
    201 *
    202 * Description:
    203 * Remove all entries from the network address table.
    204 *
    205 */
    206void sel_netport_flush(void)
    207{
    208	unsigned int idx;
    209	struct sel_netport *port, *port_tmp;
    210
    211	spin_lock_bh(&sel_netport_lock);
    212	for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) {
    213		list_for_each_entry_safe(port, port_tmp,
    214					 &sel_netport_hash[idx].list, list) {
    215			list_del_rcu(&port->list);
    216			kfree_rcu(port, rcu);
    217		}
    218		sel_netport_hash[idx].size = 0;
    219	}
    220	spin_unlock_bh(&sel_netport_lock);
    221}
    222
    223static __init int sel_netport_init(void)
    224{
    225	int iter;
    226
    227	if (!selinux_enabled_boot)
    228		return 0;
    229
    230	for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) {
    231		INIT_LIST_HEAD(&sel_netport_hash[iter].list);
    232		sel_netport_hash[iter].size = 0;
    233	}
    234
    235	return 0;
    236}
    237
    238__initcall(sel_netport_init);