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 38 struct sel_netport_bkt { 39 int size; 40 struct list_head list; 41 }; 42 43 struct 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 56 static DEFINE_SPINLOCK(sel_netport_lock); 57 static 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 */ 68 static 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 */ 83 static 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 */ 104 static 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 sel_netport_hash[idx].list.prev, 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 */ 137 static 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 } 161 162 out: 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 */ 183 int 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 */ 206 void 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 } 222 223 static __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); 239