1 // SPDX-License-Identifier: GPL-2.0-only 2 /* 3 * Network node table 4 * 5 * SELinux must keep a mapping of network nodes 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 since most of these queries happen on 8 * a per-packet basis. 9 * 10 * Author: Paul Moore <paul@paul-moore.com> 11 * 12 * This code is heavily based on the "netif" concept originally developed by 13 * James Morris <jmorris@redhat.com> 14 * (see security/selinux/netif.c for more information) 15 */ 16 17 /* 18 * (c) Copyright Hewlett-Packard Development Company, L.P., 2007 19 */ 20 21 #include <linux/types.h> 22 #include <linux/rcupdate.h> 23 #include <linux/list.h> 24 #include <linux/slab.h> 25 #include <linux/spinlock.h> 26 #include <linux/in.h> 27 #include <linux/in6.h> 28 #include <linux/ip.h> 29 #include <linux/ipv6.h> 30 #include <net/ip.h> 31 #include <net/ipv6.h> 32 33 #include "netnode.h" 34 #include "objsec.h" 35 36 #define SEL_NETNODE_HASH_SIZE 256 37 #define SEL_NETNODE_HASH_BKT_LIMIT 16 38 39 struct sel_netnode_bkt { 40 unsigned int size; 41 struct list_head list; 42 }; 43 44 struct sel_netnode { 45 struct netnode_security_struct nsec; 46 47 struct list_head list; 48 struct rcu_head rcu; 49 }; 50 51 /* NOTE: we are using a combined hash table for both IPv4 and IPv6, the reason 52 * for this is that I suspect most users will not make heavy use of both 53 * address families at the same time so one table will usually end up wasted, 54 * if this becomes a problem we can always add a hash table for each address 55 * family later */ 56 57 static DEFINE_SPINLOCK(sel_netnode_lock); 58 static struct sel_netnode_bkt sel_netnode_hash[SEL_NETNODE_HASH_SIZE]; 59 60 /** 61 * sel_netnode_hashfn_ipv4 - IPv4 hashing function for the node table 62 * @addr: IPv4 address 63 * 64 * Description: 65 * This is the IPv4 hashing function for the node interface table, it returns 66 * the bucket number for the given IP address. 67 * 68 */ sel_netnode_hashfn_ipv4(__be32 addr)69 static unsigned int sel_netnode_hashfn_ipv4(__be32 addr) 70 { 71 /* at some point we should determine if the mismatch in byte order 72 * affects the hash function dramatically */ 73 return (addr & (SEL_NETNODE_HASH_SIZE - 1)); 74 } 75 76 /** 77 * sel_netnode_hashfn_ipv6 - IPv6 hashing function for the node table 78 * @addr: IPv6 address 79 * 80 * Description: 81 * This is the IPv6 hashing function for the node interface table, it returns 82 * the bucket number for the given IP address. 83 * 84 */ sel_netnode_hashfn_ipv6(const struct in6_addr * addr)85 static unsigned int sel_netnode_hashfn_ipv6(const struct in6_addr *addr) 86 { 87 /* just hash the least significant 32 bits to keep things fast (they 88 * are the most likely to be different anyway), we can revisit this 89 * later if needed */ 90 return (addr->s6_addr32[3] & (SEL_NETNODE_HASH_SIZE - 1)); 91 } 92 93 /** 94 * sel_netnode_find - Search for a node record 95 * @addr: IP address 96 * @family: address family 97 * 98 * Description: 99 * Search the network node table and return the record matching @addr. If an 100 * entry can not be found in the table return NULL. 101 * 102 */ sel_netnode_find(const void * addr,u16 family)103 static struct sel_netnode *sel_netnode_find(const void *addr, u16 family) 104 { 105 unsigned int idx; 106 struct sel_netnode *node; 107 108 switch (family) { 109 case PF_INET: 110 idx = sel_netnode_hashfn_ipv4(*(const __be32 *)addr); 111 break; 112 case PF_INET6: 113 idx = sel_netnode_hashfn_ipv6(addr); 114 break; 115 default: 116 BUG(); 117 return NULL; 118 } 119 120 list_for_each_entry_rcu(node, &sel_netnode_hash[idx].list, list) 121 if (node->nsec.family == family) 122 switch (family) { 123 case PF_INET: 124 if (node->nsec.addr.ipv4 == *(const __be32 *)addr) 125 return node; 126 break; 127 case PF_INET6: 128 if (ipv6_addr_equal(&node->nsec.addr.ipv6, 129 addr)) 130 return node; 131 break; 132 } 133 134 return NULL; 135 } 136 137 /** 138 * sel_netnode_insert - Insert a new node into the table 139 * @node: the new node record 140 * 141 * Description: 142 * Add a new node record to the network address hash table. 143 * 144 */ sel_netnode_insert(struct sel_netnode * node)145 static void sel_netnode_insert(struct sel_netnode *node) 146 { 147 unsigned int idx; 148 149 switch (node->nsec.family) { 150 case PF_INET: 151 idx = sel_netnode_hashfn_ipv4(node->nsec.addr.ipv4); 152 break; 153 case PF_INET6: 154 idx = sel_netnode_hashfn_ipv6(&node->nsec.addr.ipv6); 155 break; 156 default: 157 BUG(); 158 return; 159 } 160 161 /* we need to impose a limit on the growth of the hash table so check 162 * this bucket to make sure it is within the specified bounds */ 163 list_add_rcu(&node->list, &sel_netnode_hash[idx].list); 164 if (sel_netnode_hash[idx].size == SEL_NETNODE_HASH_BKT_LIMIT) { 165 struct sel_netnode *tail; 166 tail = list_entry( 167 rcu_dereference_protected( 168 list_tail_rcu(&sel_netnode_hash[idx].list), 169 lockdep_is_held(&sel_netnode_lock)), 170 struct sel_netnode, list); 171 list_del_rcu(&tail->list); 172 kfree_rcu(tail, rcu); 173 } else 174 sel_netnode_hash[idx].size++; 175 } 176 177 /** 178 * sel_netnode_sid_slow - Lookup the SID of a network address using the policy 179 * @addr: the IP address 180 * @family: the address family 181 * @sid: node SID 182 * 183 * Description: 184 * This function determines the SID of a network address by querying the 185 * security policy. The result is added to the network address table to 186 * speedup future queries. Returns zero on success, negative values on 187 * failure. 188 * 189 */ sel_netnode_sid_slow(void * addr,u16 family,u32 * sid)190 static int sel_netnode_sid_slow(void *addr, u16 family, u32 *sid) 191 { 192 int ret; 193 struct sel_netnode *node; 194 struct sel_netnode *new; 195 196 spin_lock_bh(&sel_netnode_lock); 197 node = sel_netnode_find(addr, family); 198 if (node != NULL) { 199 *sid = node->nsec.sid; 200 spin_unlock_bh(&sel_netnode_lock); 201 return 0; 202 } 203 204 new = kzalloc(sizeof(*new), GFP_ATOMIC); 205 switch (family) { 206 case PF_INET: 207 ret = security_node_sid(PF_INET, 208 addr, sizeof(struct in_addr), sid); 209 if (new) 210 new->nsec.addr.ipv4 = *(__be32 *)addr; 211 break; 212 case PF_INET6: 213 ret = security_node_sid(PF_INET6, 214 addr, sizeof(struct in6_addr), sid); 215 if (new) 216 new->nsec.addr.ipv6 = *(struct in6_addr *)addr; 217 break; 218 default: 219 BUG(); 220 ret = -EINVAL; 221 } 222 if (ret == 0 && new) { 223 new->nsec.family = family; 224 new->nsec.sid = *sid; 225 sel_netnode_insert(new); 226 } else 227 kfree(new); 228 229 spin_unlock_bh(&sel_netnode_lock); 230 if (unlikely(ret)) 231 pr_warn("SELinux: failure in %s(), unable to determine network node label\n", 232 __func__); 233 return ret; 234 } 235 236 /** 237 * sel_netnode_sid - Lookup the SID of a network address 238 * @addr: the IP address 239 * @family: the address family 240 * @sid: node SID 241 * 242 * Description: 243 * This function determines the SID of a network address using the fastest 244 * method possible. First the address table is queried, but if an entry 245 * can't be found then the policy is queried and the result is added to the 246 * table to speedup future queries. Returns zero on success, negative values 247 * on failure. 248 * 249 */ sel_netnode_sid(void * addr,u16 family,u32 * sid)250 int sel_netnode_sid(void *addr, u16 family, u32 *sid) 251 { 252 struct sel_netnode *node; 253 254 rcu_read_lock(); 255 node = sel_netnode_find(addr, family); 256 if (node != NULL) { 257 *sid = node->nsec.sid; 258 rcu_read_unlock(); 259 return 0; 260 } 261 rcu_read_unlock(); 262 263 return sel_netnode_sid_slow(addr, family, sid); 264 } 265 266 /** 267 * sel_netnode_flush - Flush the entire network address table 268 * 269 * Description: 270 * Remove all entries from the network address table. 271 * 272 */ sel_netnode_flush(void)273 void sel_netnode_flush(void) 274 { 275 unsigned int idx; 276 struct sel_netnode *node, *node_tmp; 277 278 spin_lock_bh(&sel_netnode_lock); 279 for (idx = 0; idx < SEL_NETNODE_HASH_SIZE; idx++) { 280 list_for_each_entry_safe(node, node_tmp, 281 &sel_netnode_hash[idx].list, list) { 282 list_del_rcu(&node->list); 283 kfree_rcu(node, rcu); 284 } 285 sel_netnode_hash[idx].size = 0; 286 } 287 spin_unlock_bh(&sel_netnode_lock); 288 } 289 sel_netnode_init(void)290 static __init int sel_netnode_init(void) 291 { 292 int iter; 293 294 if (!selinux_enabled_boot) 295 return 0; 296 297 for (iter = 0; iter < SEL_NETNODE_HASH_SIZE; iter++) { 298 INIT_LIST_HEAD(&sel_netnode_hash[iter].list); 299 sel_netnode_hash[iter].size = 0; 300 } 301 302 return 0; 303 } 304 305 __initcall(sel_netnode_init); 306