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