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
  58 /* Default domain mapping */
  59 static DEFINE_SPINLOCK(netlbl_domhsh_def_lock);
  60 static struct netlbl_dom_map *netlbl_domhsh_def = NULL;
  61
  62 /*
  63  * Domain Hash Table Helper Functions
  64  */
  65
  66 /**
  67  * netlbl_domhsh_free_entry - Frees a domain hash table entry
  68  * @entry: the entry's RCU field
  69  *
  70  * Description:
  71  * This function is designed to be used as a callback to the call_rcu()
  72  * function so that the memory allocated to a hash table entry can be released
  73  * safely.
  74  *
  75  */
  76 static void netlbl_domhsh_free_entry(struct rcu_head *entry)
  77 {
  78         struct netlbl_dom_map *ptr;
  79
  80         ptr = container_of(entry, struct netlbl_dom_map, rcu);
  81         kfree(ptr->domain);
  82         kfree(ptr);
  83 }
  84
  85 /**
  86  * netlbl_domhsh_hash - Hashing function for the domain hash table
  87  * @domain: the domain name to hash
  88  *
  89  * Description:
  90  * This is the hashing function for the domain hash table, it returns the
  91  * correct bucket number for the domain.  The caller is responsibile for
  92  * calling the rcu_read_[un]lock() functions.
  93  *
  94  */
  95 static u32 netlbl_domhsh_hash(const char *key)
  96 {
  97         u32 iter;
  98         u32 val;
  99         u32 len;
 100
 101         /* This is taken (with slight modification) from
 102          * security/selinux/ss/symtab.c:symhash() */
 103
 104         for (iter = 0, val = 0, len = strlen(key); iter < len; iter++)
 105                 val = (val << 4 | (val >> (8 * sizeof(u32) - 4))) ^ key[iter];
 106         return val & (rcu_dereference(netlbl_domhsh)->size - 1);
 107 }
 108
 109 /**
 110  * netlbl_domhsh_search - Search for a domain entry
 111  * @domain: the domain
 112  * @def: return default if no match is found
 113  *
 114  * Description:
 115  * Searches the domain hash table and returns a pointer to the hash table
 116  * entry if found, otherwise NULL is returned.  If @def is non-zero and a
 117  * match is not found in the domain hash table the default mapping is returned
 118  * if it exists.  The caller is responsibile for the rcu hash table locks
 119  * (i.e. the caller much call rcu_read_[un]lock()).
 120  *
 121  */
 122 static struct netlbl_dom_map *netlbl_domhsh_search(const char *domain, u32 def)
 123 {
 124         u32 bkt;
 125         struct netlbl_dom_map *iter;
 126
 127         if (domain != NULL) {
 128                 bkt = netlbl_domhsh_hash(domain);
 129                 list_for_each_entry_rcu(iter, &netlbl_domhsh->tbl[bkt], list)
 130                         if (iter->valid && strcmp(iter->domain, domain) == 0)
 131                                 return iter;
 132         }
 133
 134         if (def != 0) {
 135                 iter = rcu_dereference(netlbl_domhsh_def);
 136                 if (iter != NULL && iter->valid)
 137                         return iter;
 138         }
 139
 140         return NULL;
 141 }
 142
 143 /*
 144  * Domain Hash Table Functions
 145  */
 146
 147 /**
 148  * netlbl_domhsh_init - Init for the domain hash
 149  * @size: the number of bits to use for the hash buckets
 150  *
 151  * Description:
 152  * Initializes the domain hash table, should be called only by
 153  * netlbl_user_init() during initialization.  Returns zero on success, non-zero
 154  * values on error.
 155  *
 156  */
 157 int netlbl_domhsh_init(u32 size)
 158 {
 159         u32 iter;
 160         struct netlbl_domhsh_tbl *hsh_tbl;
 161
 162         if (size == 0)
 163                 return -EINVAL;
 164
 165         hsh_tbl = kmalloc(sizeof(*hsh_tbl), GFP_KERNEL);
 166         if (hsh_tbl == NULL)
 167                 return -ENOMEM;
 168         hsh_tbl->size = 1 << size;
 169         hsh_tbl->tbl = kcalloc(hsh_tbl->size,
 170                                sizeof(struct list_head),
 171                                GFP_KERNEL);
 172         if (hsh_tbl->tbl == NULL) {
 173                 kfree(hsh_tbl);
 174                 return -ENOMEM;
 175         }
 176         for (iter = 0; iter < hsh_tbl->size; iter++)
 177                 INIT_LIST_HEAD(&hsh_tbl->tbl[iter]);
 178
 179         rcu_read_lock();
 180         spin_lock(&netlbl_domhsh_lock);
 181         rcu_assign_pointer(netlbl_domhsh, hsh_tbl);
 182         spin_unlock(&netlbl_domhsh_lock);
 183         rcu_read_unlock();
 184
 185         return 0;
 186 }
 187
 188 /**
 189  * netlbl_domhsh_add - Adds a entry to the domain hash table
 190  * @entry: the entry to add
 191  * @audit_secid: the LSM secid to use in the audit message
 192  *
 193  * Description:
 194  * Adds a new entry to the domain hash table and handles any updates to the
 195  * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 196  * negative on failure.
 197  *
 198  */
 199 int netlbl_domhsh_add(struct netlbl_dom_map *entry, u32 audit_secid)
 200 {
 201         int ret_val;
 202         u32 bkt;
 203         struct audit_buffer *audit_buf;
 204         char *audit_domain;
 205
 206         switch (entry->type) {
 207         case NETLBL_NLTYPE_UNLABELED:
 208                 ret_val = 0;
 209                 break;
 210         case NETLBL_NLTYPE_CIPSOV4:
 211                 ret_val = cipso_v4_doi_domhsh_add(entry->type_def.cipsov4,
 212                                                   entry->domain);
 213                 break;
 214         default:
 215                 return -EINVAL;
 216         }
 217         if (ret_val != 0)
 218                 return ret_val;
 219
 220         entry->valid = 1;
 221         INIT_RCU_HEAD(&entry->rcu);
 222
 223         ret_val = 0;
 224         rcu_read_lock();
 225         if (entry->domain != NULL) {
 226                 bkt = netlbl_domhsh_hash(entry->domain);
 227                 spin_lock(&netlbl_domhsh_lock);
 228                 if (netlbl_domhsh_search(entry->domain, 0) == NULL)
 229                         list_add_tail_rcu(&entry->list,
 230                                           &netlbl_domhsh->tbl[bkt]);
 231                 else
 232                         ret_val = -EEXIST;
 233                 spin_unlock(&netlbl_domhsh_lock);
 234         } else if (entry->domain == NULL) {
 235                 INIT_LIST_HEAD(&entry->list);
 236                 spin_lock(&netlbl_domhsh_def_lock);
 237                 if (rcu_dereference(netlbl_domhsh_def) == NULL)
 238                         rcu_assign_pointer(netlbl_domhsh_def, entry);
 239                 else
 240                         ret_val = -EEXIST;
 241                 spin_unlock(&netlbl_domhsh_def_lock);
 242         } else
 243                 ret_val = -EINVAL;
 244         if (ret_val == 0) {
 245                 if (entry->domain != NULL)
 246                         audit_domain = entry->domain;
 247                 else
 248                         audit_domain = "(default)";
 249                 audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_ADD,
 250                                                       audit_secid);
 251                 audit_log_format(audit_buf, " domain=%s", audit_domain);
 252                 switch (entry->type) {
 253                 case NETLBL_NLTYPE_UNLABELED:
 254                         audit_log_format(audit_buf, " protocol=unlbl");
 255                         break;
 256                 case NETLBL_NLTYPE_CIPSOV4:
 257                         audit_log_format(audit_buf,
 258                                          " protocol=cipsov4 doi=%u",
 259                                          entry->type_def.cipsov4->doi);
 260                         break;
 261                 }
 262                 audit_log_end(audit_buf);
 263         }
 264         rcu_read_unlock();
 265
 266         if (ret_val != 0) {
 267                 switch (entry->type) {
 268                 case NETLBL_NLTYPE_CIPSOV4:
 269                         if (cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
 270                                                        entry->domain) != 0)
 271                                 BUG();
 272                         break;
 273                 }
 274         }
 275
 276         return ret_val;
 277 }
 278
 279 /**
 280  * netlbl_domhsh_add_default - Adds the default entry to the domain hash table
 281  * @entry: the entry to add
 282  * @audit_secid: the LSM secid to use in the audit message
 283  *
 284  * Description:
 285  * Adds a new default entry to the domain hash table and handles any updates
 286  * to the lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 287  * negative on failure.
 288  *
 289  */
 290 int netlbl_domhsh_add_default(struct netlbl_dom_map *entry, u32 audit_secid)
 291 {
 292         return netlbl_domhsh_add(entry, audit_secid);
 293 }
 294
 295 /**
 296  * netlbl_domhsh_remove - Removes an entry from the domain hash table
 297  * @domain: the domain to remove
 298  * @audit_secid: the LSM secid to use in the audit message
 299  *
 300  * Description:
 301  * Removes an entry from the domain hash table and handles any updates to the
 302  * lower level protocol handler (i.e. CIPSO).  Returns zero on success,
 303  * negative on failure.
 304  *
 305  */
 306 int netlbl_domhsh_remove(const char *domain, u32 audit_secid)
 307 {
 308         int ret_val = -ENOENT;
 309         struct netlbl_dom_map *entry;
 310         struct audit_buffer *audit_buf;
 311         char *audit_domain;
 312
 313         rcu_read_lock();
 314         if (domain != NULL)
 315                 entry = netlbl_domhsh_search(domain, 0);
 316         else
 317                 entry = netlbl_domhsh_search(domain, 1);
 318         if (entry == NULL)
 319                 goto remove_return;
 320         switch (entry->type) {
 321         case NETLBL_NLTYPE_UNLABELED:
 322                 break;
 323         case NETLBL_NLTYPE_CIPSOV4:
 324                 ret_val = cipso_v4_doi_domhsh_remove(entry->type_def.cipsov4,
 325                                                      entry->domain);
 326                 if (ret_val != 0)
 327                         goto remove_return;
 328                 break;
 329         }
 330         ret_val = 0;
 331         if (entry != rcu_dereference(netlbl_domhsh_def)) {
 332                 spin_lock(&netlbl_domhsh_lock);
 333                 if (entry->valid) {
 334                         entry->valid = 0;
 335                         list_del_rcu(&entry->list);
 336                 } else
 337                         ret_val = -ENOENT;
 338                 spin_unlock(&netlbl_domhsh_lock);
 339         } else {
 340                 spin_lock(&netlbl_domhsh_def_lock);
 341                 if (entry->valid) {
 342                         entry->valid = 0;
 343                         rcu_assign_pointer(netlbl_domhsh_def, NULL);
 344                 } else
 345                         ret_val = -ENOENT;
 346                 spin_unlock(&netlbl_domhsh_def_lock);
 347         }
 348         if (ret_val == 0) {
 349                 if (entry->domain != NULL)
 350                         audit_domain = entry->domain;
 351                 else
 352                         audit_domain = "(default)";
 353                 audit_buf = netlbl_audit_start_common(AUDIT_MAC_MAP_DEL,
 354                                                       audit_secid);
 355                 audit_log_format(audit_buf, " domain=%s", audit_domain);
 356                 audit_log_end(audit_buf);
 357
 358                 call_rcu(&entry->rcu, netlbl_domhsh_free_entry);
 359         }
 360
 361 remove_return:
 362         rcu_read_unlock();
 363         return ret_val;
 364 }
 365
 366 /**
 367  * netlbl_domhsh_remove_default - Removes the default entry from the table
 368  * @audit_secid: the LSM secid to use in the audit message
 369  *
 370  * Description:
 371  * Removes/resets the default entry for the domain hash table and handles any
 372  * updates to the lower level protocol handler (i.e. CIPSO).  Returns zero on
 373  * success, non-zero on failure.
 374  *
 375  */
 376 int netlbl_domhsh_remove_default(u32 audit_secid)
 377 {
 378         return netlbl_domhsh_remove(NULL, audit_secid);
 379 }
 380
 381 /**
 382  * netlbl_domhsh_getentry - Get an entry from the domain hash table
 383  * @domain: the domain name to search for
 384  *
 385  * Description:
 386  * Look through the domain hash table searching for an entry to match @domain,
 387  * return a pointer to a copy of the entry or NULL.  The caller is responsibile
 388  * for ensuring that rcu_read_[un]lock() is called.
 389  *
 390  */
 391 struct netlbl_dom_map *netlbl_domhsh_getentry(const char *domain)
 392 {
 393         return netlbl_domhsh_search(domain, 1);
 394 }
 395
 396 /**
 397  * netlbl_domhsh_walk - Iterate through the domain mapping hash table
 398  * @skip_bkt: the number of buckets to skip at the start
 399  * @skip_chain: the number of entries to skip in the first iterated bucket
 400  * @callback: callback for each entry
 401  * @cb_arg: argument for the callback function
 402  *
 403  * Description:
 404  * Interate over the domain mapping hash table, skipping the first @skip_bkt
 405  * buckets and @skip_chain entries.  For each entry in the table call
 406  * @callback, if @callback returns a negative value stop 'walking' through the
 407  * table and return.  Updates the values in @skip_bkt and @skip_chain on
 408  * return.  Returns zero on succcess, negative values on failure.
 409  *
 410  */
 411 int netlbl_domhsh_walk(u32 *skip_bkt,
 412                      u32 *skip_chain,
 413                      int (*callback) (struct netlbl_dom_map *entry, void *arg),
 414                      void *cb_arg)
 415 {
 416         int ret_val = -ENOENT;
 417         u32 iter_bkt;
 418         struct netlbl_dom_map *iter_entry;
 419         u32 chain_cnt = 0;
 420
 421         rcu_read_lock();
 422         for (iter_bkt = *skip_bkt;
 423              iter_bkt < rcu_dereference(netlbl_domhsh)->size;
 424              iter_bkt++, chain_cnt = 0) {
 425                 list_for_each_entry_rcu(iter_entry,
 426                                         &netlbl_domhsh->tbl[iter_bkt],
 427                                         list)
 428                         if (iter_entry->valid) {
 429                                 if (chain_cnt++ < *skip_chain)
 430                                         continue;
 431                                 ret_val = callback(iter_entry, cb_arg);
 432                                 if (ret_val < 0) {
 433                                         chain_cnt--;
 434                                         goto walk_return;
 435                                 }
 436                         }
 437         }
 438
 439 walk_return:
 440         rcu_read_unlock();
 441         *skip_bkt = iter_bkt;
 442         *skip_chain = chain_cnt;
 443         return ret_val;
 444 }