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 LIST_HEAD(sel_netport_list); 57 static DEFINE_SPINLOCK(sel_netport_lock); 58 static struct sel_netport_bkt sel_netport_hash[SEL_NETPORT_HASH_SIZE]; 59 60 /** 61 * sel_netport_hashfn - Hashing function for the port table 62 * @pnum: port number 63 * 64 * Description: 65 * This is the hashing function for the port table, it returns the bucket 66 * number for the given port. 67 * 68 */ 69 static unsigned int sel_netport_hashfn(u16 pnum) 70 { 71 return (pnum & (SEL_NETPORT_HASH_SIZE - 1)); 72 } 73 74 /** 75 * sel_netport_find - Search for a port record 76 * @protocol: protocol 77 * @port: pnum 78 * 79 * Description: 80 * Search the network port table and return the matching record. If an entry 81 * can not be found in the table return NULL. 82 * 83 */ 84 static struct sel_netport *sel_netport_find(u8 protocol, u16 pnum) 85 { 86 unsigned int idx; 87 struct sel_netport *port; 88 89 idx = sel_netport_hashfn(pnum); 90 list_for_each_entry_rcu(port, &sel_netport_hash[idx].list, list) 91 if (port->psec.port == pnum && port->psec.protocol == protocol) 92 return port; 93 94 return NULL; 95 } 96 97 /** 98 * sel_netport_insert - Insert a new port into the table 99 * @port: the new port record 100 * 101 * Description: 102 * Add a new port record to the network address hash table. 103 * 104 */ 105 static void sel_netport_insert(struct sel_netport *port) 106 { 107 unsigned int idx; 108 109 /* we need to impose a limit on the growth of the hash table so check 110 * this bucket to make sure it is within the specified bounds */ 111 idx = sel_netport_hashfn(port->psec.port); 112 list_add_rcu(&port->list, &sel_netport_hash[idx].list); 113 if (sel_netport_hash[idx].size == SEL_NETPORT_HASH_BKT_LIMIT) { 114 struct sel_netport *tail; 115 tail = list_entry( 116 rcu_dereference_protected( 117 sel_netport_hash[idx].list.prev, 118 lockdep_is_held(&sel_netport_lock)), 119 struct sel_netport, list); 120 list_del_rcu(&tail->list); 121 kfree_rcu(tail, rcu); 122 } else 123 sel_netport_hash[idx].size++; 124 } 125 126 /** 127 * sel_netport_sid_slow - Lookup the SID of a network address using the policy 128 * @protocol: protocol 129 * @pnum: port 130 * @sid: port SID 131 * 132 * Description: 133 * This function determines the SID of a network port by quering the security 134 * policy. The result is added to the network port table to speedup future 135 * queries. Returns zero on success, negative values on failure. 136 * 137 */ 138 static int sel_netport_sid_slow(u8 protocol, u16 pnum, u32 *sid) 139 { 140 int ret; 141 struct sel_netport *port; 142 struct sel_netport *new; 143 144 spin_lock_bh(&sel_netport_lock); 145 port = sel_netport_find(protocol, pnum); 146 if (port != NULL) { 147 *sid = port->psec.sid; 148 spin_unlock_bh(&sel_netport_lock); 149 return 0; 150 } 151 152 ret = security_port_sid(&selinux_state, protocol, pnum, sid); 153 if (ret != 0) 154 goto out; 155 new = kzalloc(sizeof(*new), GFP_ATOMIC); 156 if (new) { 157 new->psec.port = pnum; 158 new->psec.protocol = protocol; 159 new->psec.sid = *sid; 160 sel_netport_insert(new); 161 } 162 163 out: 164 spin_unlock_bh(&sel_netport_lock); 165 if (unlikely(ret)) 166 pr_warn("SELinux: failure in %s(), unable to determine network port label\n", 167 __func__); 168 return ret; 169 } 170 171 /** 172 * sel_netport_sid - Lookup the SID of a network port 173 * @protocol: protocol 174 * @pnum: port 175 * @sid: port SID 176 * 177 * Description: 178 * This function determines the SID of a network port using the fastest method 179 * possible. First the port table is queried, but if an entry can't be found 180 * then the policy is queried and the result is added to the table to speedup 181 * future queries. Returns zero on success, negative values on failure. 182 * 183 */ 184 int sel_netport_sid(u8 protocol, u16 pnum, u32 *sid) 185 { 186 struct sel_netport *port; 187 188 rcu_read_lock(); 189 port = sel_netport_find(protocol, pnum); 190 if (port != NULL) { 191 *sid = port->psec.sid; 192 rcu_read_unlock(); 193 return 0; 194 } 195 rcu_read_unlock(); 196 197 return sel_netport_sid_slow(protocol, pnum, sid); 198 } 199 200 /** 201 * sel_netport_flush - Flush the entire network port table 202 * 203 * Description: 204 * Remove all entries from the network address table. 205 * 206 */ 207 void sel_netport_flush(void) 208 { 209 unsigned int idx; 210 struct sel_netport *port, *port_tmp; 211 212 spin_lock_bh(&sel_netport_lock); 213 for (idx = 0; idx < SEL_NETPORT_HASH_SIZE; idx++) { 214 list_for_each_entry_safe(port, port_tmp, 215 &sel_netport_hash[idx].list, list) { 216 list_del_rcu(&port->list); 217 kfree_rcu(port, rcu); 218 } 219 sel_netport_hash[idx].size = 0; 220 } 221 spin_unlock_bh(&sel_netport_lock); 222 } 223 224 static __init int sel_netport_init(void) 225 { 226 int iter; 227 228 if (!selinux_enabled) 229 return 0; 230 231 for (iter = 0; iter < SEL_NETPORT_HASH_SIZE; iter++) { 232 INIT_LIST_HEAD(&sel_netport_hash[iter].list); 233 sel_netport_hash[iter].size = 0; 234 } 235 236 return 0; 237 } 238 239 __initcall(sel_netport_init); 240