1/* 2 * Network port table 3 * 4 * SELinux must keep a mapping of network ports to labels/SIDs. This 5 * mapping is maintained as part of the normal policy but a fast cache is 6 * needed to reduce the lookup overhead. 7 * 8 * Author: Paul Moore <paul@paul-moore.com> 9 * 10 * This code is heavily based on the "netif" concept originally developed by 11 * James Morris <jmorris@redhat.com> 12 * (see security/selinux/netif.c for more information) 13 * 14 */ 15 16/* 17 * (c) Copyright Hewlett-Packard Development Company, L.P., 2008 18 * 19 * This program is free software: you can redistribute it and/or modify 20 * it under the terms of version 2 of the GNU General Public License as 21 * published by the Free Software Foundation. 22 * 23 * This program is distributed in the hope that it will be useful, 24 * but WITHOUT ANY WARRANTY; without even the implied warranty of 25 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the 26 * GNU General Public License for more details. 27 * 28 */ 29 30#include <linux/types.h> 31#include <linux/rcupdate.h> 32#include <linux/list.h> 33#include <linux/slab.h> 34#include <linux/spinlock.h> 35#include <linux/in.h> 36#include <linux/in6.h> 37#include <linux/ip.h> 38#include <linux/ipv6.h> 39#include <net/ip.h> 40#include <net/ipv6.h> 41 42#include "netport.h" 43#include "objsec.h" 44 45#define SEL_NETPORT_HASH_SIZE 256 46#define SEL_NETPORT_HASH_BKT_LIMIT 16 47 48struct sel_netport_bkt { 49 int size; 50 struct list_head list; 51}; 52 53struct sel_netport { 54 struct netport_security_struct psec; 55 56 struct list_head list; 57 struct rcu_head rcu; 58}; 59 60/* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason 61 * for this is that I suspect most users will not make heavy use of both 62 * address families at the same time so one table will usually end up wasted, 63 * if this becomes a problem we can always add a hash table for each address 64 * family later */ 65 66static LIST_HEAD(sel_netport_list); 67static DEFINE_SPINLOCK(sel_netport_lock); 68static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE]; 69 70/** 71 * sel_netport_hashfn - Hashing function for the port table 72 * @pnum: port number 73 * 74 * Description: 75 * This is the hashing function for the port table, it returns the bucket 76 * number for the given port. 77 * 78 */ 79static unsigned int sel_netport_hashfn(u16 pnum) 80{ 81 return (pnum & (SEL_NETPORT_HASH_SIZE - 1)); 82} 83 84/** 85 * sel_netport_find - Search for a port record 86 * @protocol: protocol 87 * @port: pnum 88 * 89 * Description: 90 * Search the network port table and return the matching record. If an entry 91 * can not be found in the table return NULL. 92 * 93 */ 94static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum) 95{ 96 unsigned int idx; 97 struct sel_netport *port; 98 99 idx = sel_netport_hashfn(pnum); 100 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list) 101 if (port->psec.port == pnum && port->psec.protocol == protocol) 102 return port; 103 104 return NULL; 105} 106 107/** 108 * sel_netport_insert - Insert a new port into the table 109 * @port: the new port record 110 * 111 * Description: 112 * Add a new port record to the network address hash table. 113 * 114 */ 115static void sel_netport_insert(struct sel_netport *port) 116{ 117 unsigned int idx; 118 119 /* we need to impose a limit on the growth of the hash table so check 120 * this bucket to make sure it is within the specified bounds */ 121 idx = sel_netport_hashfn(port->psec.port); 122 list_add_rcu(&port->list, &sel_netport_hash[idx].list); 123 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) { 124 struct sel_netport *tail; 125 tail = list_entry( 126 rcu_dereference_protected( 127 sel_netport_hash[idx].list.prev, 128 lockdep_is_held(&sel_netport_lock)), 129 struct sel_netport, list); 130 list_del_rcu(&tail->list); 131 kfree_rcu(tail, rcu); 132 } else 133 sel_netport_hash[idx].size++; 134} 135 136/** 137 * sel_netport_sid_slow - Lookup the SID of a network address using the policy 138 * @protocol: protocol 139 * @pnum: port 140 * @sid: port SID 141 * 142 * Description: 143 * This function determines the SID of a network port by quering the security 144 * policy. The result is added to the network port table to speedup future 145 * queries. Returns zero on success, negative values on failure. 146 * 147 */ 148static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) 149{ 150 int ret = -ENOMEM; 151 struct sel_netport *port; 152 struct sel_netport *new = NULL; 153 154 spin_lock_bh(&sel_netport_lock); 155 port = sel_netport_find(protocol, pnum); 156 if (port != NULL) { 157 *sid = port->psec.sid; 158 spin_unlock_bh(&sel_netport_lock); 159 return 0; 160 } 161 new = kzalloc(sizeof(*new), GFP_ATOMIC); 162 if (new == NULL) 163 goto out; 164 ret = security_port_sid(protocol, pnum, sid); 165 if (ret != 0) 166 goto out; 167 168 new->psec.port = pnum; 169 new->psec.protocol = protocol; 170 new->psec.sid = *sid; 171 sel_netport_insert(new); 172 173out: 174 spin_unlock_bh(&sel_netport_lock); 175 if (unlikely(ret)) { 176 printk(KERN_WARNING 177 "SELinux: failure in sel_netport_sid_slow()," 178 " unable to determine network port label\n"); 179 kfree(new); 180 } 181 return ret; 182} 183 184/** 185 * sel_netport_sid - Lookup the SID of a network port 186 * @protocol: protocol 187 * @pnum: port 188 * @sid: port SID 189 * 190 * Description: 191 * This function determines the SID of a network port using the fastest method 192 * possible. First the port table is queried, but if an entry can't be found 193 * then the policy is queried and the result is added to the table to speedup 194 * future queries. Returns zero on success, negative values on failure. 195 * 196 */ 197int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid) 198{ 199 struct sel_netport *port; 200 201 rcu_read_lock(); 202 port = sel_netport_find(protocol, pnum); 203 if (port != NULL) { 204 *sid = port->psec.sid; 205 rcu_read_unlock(); 206 return 0; 207 } 208 rcu_read_unlock(); 209 210 return sel_netport_sid_slow(protocol, pnum, sid); 211} 212 213/** 214 * sel_netport_flush - Flush the entire network port table 215 * 216 * Description: 217 * Remove all entries from the network address table. 218 * 219 */ 220void sel_netport_flush(void) 221{ 222 unsigned int idx; 223 struct sel_netport *port, *port_tmp; 224 225 spin_lock_bh(&sel_netport_lock); 226 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { 227 list_for_each_entry_safe(port, port_tmp, 228 &sel_netport_hash[idx].list, list) { 229 list_del_rcu(&port->list); 230 kfree_rcu(port, rcu); 231 } 232 sel_netport_hash[idx].size = 0; 233 } 234 spin_unlock_bh(&sel_netport_lock); 235} 236 237static __init int sel_netport_init(void) 238{ 239 int iter; 240 241 if (!selinux_enabled) 242 return 0; 243 244 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) { 245 INIT_LIST_HEAD(&sel_netport_hash[iter].list); 246 sel_netport_hash[iter].size = 0; 247 } 248 249 return 0; 250} 251 252__initcall(sel_netport_init); 253