1 /* 2 * NetLabel Domain Hash Table 3 * 4 * This file manages the domain hash table that NetLabel uses to determine 5 * which network labeling protocol to use for a given domain. The NetLabel 6 * system manages static and dynamic label mappings for network protocols such 7 * as CIPSO and RIPSO. 8 * 9 * Author: Paul Moore <paul.moore@hp.com> 10 * 11 */ 12 13 /* 14 * (c) Copyright Hewlett-Packard Development Company, L.P., 2006 15 * 16 * This program is free software; you can redistribute it and/or modify 17 * it under the terms of the GNU General Public License as published by 18 * the Free Software Foundation; either version 2 of the License, or 19 * (at your option) any later version. 20 * 21 * This program is distributed in the hope that it will be useful, 22 * but WITHOUT ANY WARRANTY; without even the implied warranty of 23 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See 24 * the GNU General Public License for more details. 25 * 26 * You should have received a copy of the GNU General Public License 27 * along with this program; if not, write to the Free Software 28 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA 29 * 30 */ 31 32 #include <linux/types.h> 33 #include <linux/rcupdate.h> 34 #include <linux/list.h> 35 #include <linux/skbuff.h> 36 #include <linux/spinlock.h> 37 #include <linux/string.h> 38 #include <linux/audit.h> 39 #include <net/netlabel.h> 40 #include <net/cipso_ipv4.h> 41 #include <asm/bug.h> 42 43 #include "netlabel_mgmt.h" 44 #include "netlabel_domainhash.h" 45 #include "netlabel_user.h" 46 47 struct netlbl_domhsh_tbl { 48 struct list_head *tbl; 49 u32 size; 50 }; 51 52 /* Domain hash table */ 53 /* XXX - updates should be so rare that having one spinlock for the entire 54 * hash table should be okay */ 55 static DEFINE_SPINLOCK(netlbl_domhsh_lock); 56 static struct netlbl_domhsh_tbl *netlbl_domhsh = NULL; 57 static struct netlbl_dom_map *netlbl_domhsh_def = NULL; 58 59 /* 60 * Domain Hash Table Helper Functions 61 */ 62 63 /** 64 * netlbl_domhsh_free_entry - Frees a domain hash table entry 65 * @entry: the entry's RCU field 66 * 67 * Description: 68 * This function is designed to be used as a callback to the call_rcu() 69 * function so that the memory allocated to a hash table entry can be released 70 * safely. 71 * 72 */ 73 static void netlbl_domhsh_free_entry(struct rcu_head *entry) 74 { 75 struct netlbl_dom_map *ptr; 76 77 ptr = container_of(entry, struct netlbl_dom_map, rcu); 78 kfree(ptr->domain); 79 kfree(ptr); 80 } 81 82 /** 83 * netlbl_domhsh_hash - Hashing function for the domain hash table 84 * @domain: the domain name to hash 85 * 86 * Description: 87 * This is the hashing function for the domain hash table, it returns the 88 * correct bucket number for the domain. The caller is responsibile for 89 * calling the rcu_read_[un]lock() functions. 90 * 91 */ 92 static u32 netlbl_domhsh_hash(const char *key) 93 { 94 u32 iter; 95 u32 val; 96 u32 len; 97 98 /* This is taken (with slight modification) from 99 * security/selinux/ss/symtab.c:symhash() */ 100 101 for (iter = 0, val = 0, len = strlen(key); iter < len; iter++) 102 val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter]; 103 return val & (rcu_dereference(netlbl_domhsh)->size - 1); 104 } 105 106 /** 107 * netlbl_domhsh_search - Search for a domain entry 108 * @domain: the domain 109 * 110 * Description: 111 * Searches the domain hash table and returns a pointer to the hash table 112 * entry if found, otherwise NULL is returned. The caller is responsibile for 113 * the rcu hash table locks (i.e. the caller much call rcu_read_[un]lock()). 114 * 115 */ 116 static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain) 117 { 118 u32 bkt; 119 struct netlbl_dom_map *iter; 120 121 if (domain != NULL) { 122 bkt = netlbl_domhsh_hash(domain); 123 list_for_each_entry_rcu(iter, 124 &rcu_dereference(netlbl_domhsh)->tbl[bkt], 125 list) 126 if (iter->valid && strcmp(iter->domain, domain) == 0) 127 return iter; 128 } 129 130 return NULL; 131 } 132 133 /** 134 * netlbl_domhsh_search_def - Search for a domain entry 135 * @domain: the domain 136 * @def: return default if no match is found 137 * 138 * Description: 139 * Searches the domain hash table and returns a pointer to the hash table 140 * entry if an exact match is found, if an exact match is not present in the 141 * hash table then the default entry is returned if valid otherwise NULL is 142 * returned. The caller is responsibile for the rcu hash table locks 143 * (i.e. the caller much call rcu_read_[un]lock()). 144 * 145 */ 146 static struct netlbl_dom_map *netlbl_domhsh_search_def(const char *domain) 147 { 148 struct netlbl_dom_map *entry; 149 150 entry = netlbl_domhsh_search(domain); 151 if (entry == NULL) { 152 entry = rcu_dereference(netlbl_domhsh_def); 153 if (entry != NULL && !entry->valid) 154 entry = NULL; 155 } 156 157 return entry; 158 } 159 160 /* 161 * Domain Hash Table Functions 162 */ 163 164 /** 165 * netlbl_domhsh_init - Init for the domain hash 166 * @size: the number of bits to use for the hash buckets 167 * 168 * Description: 169 * Initializes the domain hash table, should be called only by 170 * netlbl_user_init() during initialization. Returns zero on success, non-zero 171 * values on error. 172 * 173 */ 174 int __init netlbl_domhsh_init(u32 size) 175 { 176 u32 iter; 177 struct netlbl_domhsh_tbl *hsh_tbl; 178 179 if (size == 0) 180 return -EINVAL; 181 182 hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL); 183 if (hsh_tbl == NULL) 184 return -ENOMEM; 185 hsh_tbl->size = 1 << size; 186 hsh_tbl->tbl = kcalloc(hsh_tbl->size, 187 sizeof(struct list_head), 188 GFP_KERNEL); 189 if (hsh_tbl->tbl == NULL) { 190 kfree(hsh_tbl); 191 return -ENOMEM; 192 } 193 for (iter = 0; iter < hsh_tbl->size; iter++) 194 INIT_LIST_HEAD(&hsh_tbl->tbl[iter]); 195 196 spin_lock(&netlbl_domhsh_lock); 197 rcu_assign_pointer(netlbl_domhsh, hsh_tbl); 198 spin_unlock(&netlbl_domhsh_lock); 199 200 return 0; 201 } 202 203 /** 204 * netlbl_domhsh_add - Adds a entry to the domain hash table 205 * @entry: the entry to add 206 * @audit_info: NetLabel audit information 207 * 208 * Description: 209 * Adds a new entry to the domain hash table and handles any updates to the 210 * lower level protocol handler (i.e. CIPSO). Returns zero on success, 211 * negative on failure. 212 * 213 */ 214 int netlbl_domhsh_add(struct netlbl_dom_map *entry, 215 struct netlbl_audit *audit_info) 216 { 217 int ret_val; 218 u32 bkt; 219 struct audit_buffer *audit_buf; 220 221 switch (entry->type) { 222 case NETLBL_NLTYPE_UNLABELED: 223 ret_val = 0; 224 break; 225 case NETLBL_NLTYPE_CIPSOV4: 226 ret_val = cipso_v4_doi_domhsh_add(entry->type_def.cipsov4, 227 entry->domain); 228 break; 229 default: 230 return -EINVAL; 231 } 232 if (ret_val != 0) 233 return ret_val; 234 235 entry->valid = 1; 236 INIT_RCU_HEAD(&entry->rcu); 237 238 rcu_read_lock(); 239 spin_lock(&netlbl_domhsh_lock); 240 if (entry->domain != NULL) { 241 bkt = netlbl_domhsh_hash(entry->domain); 242 if (netlbl_domhsh_search(entry->domain) == NULL) 243 list_add_tail_rcu(&entry->list, 244 &rcu_dereference(netlbl_domhsh)->tbl[bkt]); 245 else 246 ret_val = -EEXIST; 247 } else { 248 INIT_LIST_HEAD(&entry->list); 249 if (rcu_dereference(netlbl_domhsh_def) == NULL) 250 rcu_assign_pointer(netlbl_domhsh_def, entry); 251 else 252 ret_val = -EEXIST; 253 } 254 spin_unlock(&netlbl_domhsh_lock); 255 audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD, audit_info); 256 if (audit_buf != NULL) { 257 audit_log_format(audit_buf, 258 " nlbl_domain=%s", 259 entry->domain ? entry->domain : "(default)"); 260 switch (entry->type) { 261 case NETLBL_NLTYPE_UNLABELED: 262 audit_log_format(audit_buf, " nlbl_protocol=unlbl"); 263 break; 264 case NETLBL_NLTYPE_CIPSOV4: 265 audit_log_format(audit_buf, 266 " nlbl_protocol=cipsov4 cipso_doi=%u", 267 entry->type_def.cipsov4->doi); 268 break; 269 } 270 audit_log_format(audit_buf, " res=%u", ret_val == 0 ? 1 : 0); 271 audit_log_end(audit_buf); 272 } 273 rcu_read_unlock(); 274 275 if (ret_val != 0) { 276 switch (entry->type) { 277 case NETLBL_NLTYPE_CIPSOV4: 278 if (cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4, 279 entry->domain) != 0) 280 BUG(); 281 break; 282 } 283 } 284 285 return ret_val; 286 } 287 288 /** 289 * netlbl_domhsh_add_default - Adds the default entry to the domain hash table 290 * @entry: the entry to add 291 * @audit_info: NetLabel audit information 292 * 293 * Description: 294 * Adds a new default entry to the domain hash table and handles any updates 295 * to the lower level protocol handler (i.e. CIPSO). Returns zero on success, 296 * negative on failure. 297 * 298 */ 299 int netlbl_domhsh_add_default(struct netlbl_dom_map *entry, 300 struct netlbl_audit *audit_info) 301 { 302 return netlbl_domhsh_add(entry, audit_info); 303 } 304 305 /** 306 * netlbl_domhsh_remove - Removes an entry from the domain hash table 307 * @domain: the domain to remove 308 * @audit_info: NetLabel audit information 309 * 310 * Description: 311 * Removes an entry from the domain hash table and handles any updates to the 312 * lower level protocol handler (i.e. CIPSO). Returns zero on success, 313 * negative on failure. 314 * 315 */ 316 int netlbl_domhsh_remove(const char *domain, struct netlbl_audit *audit_info) 317 { 318 int ret_val = -ENOENT; 319 struct netlbl_dom_map *entry; 320 struct audit_buffer *audit_buf; 321 322 rcu_read_lock(); 323 if (domain) 324 entry = netlbl_domhsh_search(domain); 325 else 326 entry = netlbl_domhsh_search_def(domain); 327 if (entry == NULL) 328 goto remove_return; 329 switch (entry->type) { 330 case NETLBL_NLTYPE_CIPSOV4: 331 cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4, 332 entry->domain); 333 break; 334 } 335 spin_lock(&netlbl_domhsh_lock); 336 if (entry->valid) { 337 entry->valid = 0; 338 if (entry != rcu_dereference(netlbl_domhsh_def)) 339 list_del_rcu(&entry->list); 340 else 341 rcu_assign_pointer(netlbl_domhsh_def, NULL); 342 ret_val = 0; 343 } 344 spin_unlock(&netlbl_domhsh_lock); 345 346 audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL, audit_info); 347 if (audit_buf != NULL) { 348 audit_log_format(audit_buf, 349 " nlbl_domain=%s res=%u", 350 entry->domain ? entry->domain : "(default)", 351 ret_val == 0 ? 1 : 0); 352 audit_log_end(audit_buf); 353 } 354 355 remove_return: 356 rcu_read_unlock(); 357 if (ret_val == 0) 358 call_rcu(&entry->rcu, netlbl_domhsh_free_entry); 359 return ret_val; 360 } 361 362 /** 363 * netlbl_domhsh_remove_default - Removes the default entry from the table 364 * @audit_info: NetLabel audit information 365 * 366 * Description: 367 * Removes/resets the default entry for the domain hash table and handles any 368 * updates to the lower level protocol handler (i.e. CIPSO). Returns zero on 369 * success, non-zero on failure. 370 * 371 */ 372 int netlbl_domhsh_remove_default(struct netlbl_audit *audit_info) 373 { 374 return netlbl_domhsh_remove(NULL, audit_info); 375 } 376 377 /** 378 * netlbl_domhsh_getentry - Get an entry from the domain hash table 379 * @domain: the domain name to search for 380 * 381 * Description: 382 * Look through the domain hash table searching for an entry to match @domain, 383 * return a pointer to a copy of the entry or NULL. The caller is responsibile 384 * for ensuring that rcu_read_[un]lock() is called. 385 * 386 */ 387 struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain) 388 { 389 return netlbl_domhsh_search_def(domain); 390 } 391 392 /** 393 * netlbl_domhsh_walk - Iterate through the domain mapping hash table 394 * @skip_bkt: the number of buckets to skip at the start 395 * @skip_chain: the number of entries to skip in the first iterated bucket 396 * @callback: callback for each entry 397 * @cb_arg: argument for the callback function 398 * 399 * Description: 400 * Interate over the domain mapping hash table, skipping the first @skip_bkt 401 * buckets and @skip_chain entries. For each entry in the table call 402 * @callback, if @callback returns a negative value stop 'walking' through the 403 * table and return. Updates the values in @skip_bkt and @skip_chain on 404 * return. Returns zero on succcess, negative values on failure. 405 * 406 */ 407 int netlbl_domhsh_walk(u32 *skip_bkt, 408 u32 *skip_chain, 409 int (*callback) (struct netlbl_dom_map *entry, void *arg), 410 void *cb_arg) 411 { 412 int ret_val = -ENOENT; 413 u32 iter_bkt; 414 struct netlbl_dom_map *iter_entry; 415 u32 chain_cnt = 0; 416 417 rcu_read_lock(); 418 for (iter_bkt = *skip_bkt; 419 iter_bkt < rcu_dereference(netlbl_domhsh)->size; 420 iter_bkt++, chain_cnt = 0) { 421 list_for_each_entry_rcu(iter_entry, 422 &rcu_dereference(netlbl_domhsh)->tbl[iter_bkt], 423 list) 424 if (iter_entry->valid) { 425 if (chain_cnt++ < *skip_chain) 426 continue; 427 ret_val = callback(iter_entry, cb_arg); 428 if (ret_val < 0) { 429 chain_cnt--; 430 goto walk_return; 431 } 432 } 433 } 434 435 walk_return: 436 rcu_read_unlock(); 437 *skip_bkt = iter_bkt; 438 *skip_chain = chain_cnt; 439 return ret_val; 440 } 441