net/netlabel/netlabel_domainhash.c

   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 }