net/netlabel/netlabel_kapi.c

   1 /*
   2  * NetLabel Kernel API
   3  *
   4  * This file defines the kernel API for the NetLabel system.  The NetLabel
   5  * system manages static and dynamic label mappings for network protocols such
   6  * as CIPSO and RIPSO.
   7  *
   8  * Author: Paul Moore <paul.moore@hp.com>
   9  *
  10  */
  11
  12 /*
  13  * (c) Copyright Hewlett-Packard Development Company, L.P., 2006
  14  *
  15  * This program is free software;  you can redistribute it and/or modify
  16  * it under the terms of the GNU General Public License as published by
  17  * the Free Software Foundation; either version 2 of the License, or
  18  * (at your option) any later version.
  19  *
  20  * This program is distributed in the hope that it will be useful,
  21  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
  22  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  23  * the GNU General Public License for more details.
  24  *
  25  * You should have received a copy of the GNU General Public License
  26  * along with this program;  if not, write to the Free Software
  27  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  28  *
  29  */
  30
  31 #include <linux/init.h>
  32 #include <linux/types.h>
  33 #include <net/ip.h>
  34 #include <net/netlabel.h>
  35 #include <net/cipso_ipv4.h>
  36 #include <asm/bug.h>
  37
  38 #include "netlabel_domainhash.h"
  39 #include "netlabel_unlabeled.h"
  40 #include "netlabel_user.h"
  41 #include "netlabel_mgmt.h"
  42
  43 /*
  44  * Security Attribute Functions
  45  */
  46
  47 /**
  48  * netlbl_secattr_catmap_walk - Walk a LSM secattr catmap looking for a bit
  49  * @catmap: the category bitmap
  50  * @offset: the offset to start searching at, in bits
  51  *
  52  * Description:
  53  * This function walks a LSM secattr category bitmap starting at @offset and
  54  * returns the spot of the first set bit or -ENOENT if no bits are set.
  55  *
  56  */
  57 int netlbl_secattr_catmap_walk(struct netlbl_lsm_secattr_catmap *catmap,
  58                                u32 offset)
  59 {
  60         struct netlbl_lsm_secattr_catmap *iter = catmap;
  61         u32 node_idx;
  62         u32 node_bit;
  63         NETLBL_CATMAP_MAPTYPE bitmap;
  64
  65         if (offset > iter->startbit) {
  66                 while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
  67                         iter = iter->next;
  68                         if (iter == NULL)
  69                                 return -ENOENT;
  70                 }
  71                 node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
  72                 node_bit = offset - iter->startbit -
  73                            (NETLBL_CATMAP_MAPSIZE * node_idx);
  74         } else {
  75                 node_idx = 0;
  76                 node_bit = 0;
  77         }
  78         bitmap = iter->bitmap[node_idx] >> node_bit;
  79
  80         for (;;) {
  81                 if (bitmap != 0) {
  82                         while ((bitmap & NETLBL_CATMAP_BIT) == 0) {
  83                                 bitmap >>= 1;
  84                                 node_bit++;
  85                         }
  86                         return iter->startbit +
  87                                 (NETLBL_CATMAP_MAPSIZE * node_idx) + node_bit;
  88                 }
  89                 if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
  90                         if (iter->next != NULL) {
  91                                 iter = iter->next;
  92                                 node_idx = 0;
  93                         } else
  94                                 return -ENOENT;
  95                 }
  96                 bitmap = iter->bitmap[node_idx];
  97                 node_bit = 0;
  98         }
  99
 100         return -ENOENT;
 101 }
 102
 103 /**
 104  * netlbl_secattr_catmap_walk_rng - Find the end of a string of set bits
 105  * @catmap: the category bitmap
 106  * @offset: the offset to start searching at, in bits
 107  *
 108  * Description:
 109  * This function walks a LSM secattr category bitmap starting at @offset and
 110  * returns the spot of the first cleared bit or -ENOENT if the offset is past
 111  * the end of the bitmap.
 112  *
 113  */
 114 int netlbl_secattr_catmap_walk_rng(struct netlbl_lsm_secattr_catmap *catmap,
 115                                    u32 offset)
 116 {
 117         struct netlbl_lsm_secattr_catmap *iter = catmap;
 118         u32 node_idx;
 119         u32 node_bit;
 120         NETLBL_CATMAP_MAPTYPE bitmask;
 121         NETLBL_CATMAP_MAPTYPE bitmap;
 122
 123         if (offset > iter->startbit) {
 124                 while (offset >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
 125                         iter = iter->next;
 126                         if (iter == NULL)
 127                                 return -ENOENT;
 128                 }
 129                 node_idx = (offset - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
 130                 node_bit = offset - iter->startbit -
 131                            (NETLBL_CATMAP_MAPSIZE * node_idx);
 132         } else {
 133                 node_idx = 0;
 134                 node_bit = 0;
 135         }
 136         bitmask = NETLBL_CATMAP_BIT << node_bit;
 137
 138         for (;;) {
 139                 bitmap = iter->bitmap[node_idx];
 140                 while (bitmask != 0 && (bitmap & bitmask) != 0) {
 141                         bitmask <<= 1;
 142                         node_bit++;
 143                 }
 144
 145                 if (bitmask != 0)
 146                         return iter->startbit +
 147                                 (NETLBL_CATMAP_MAPSIZE * node_idx) +
 148                                 node_bit - 1;
 149                 else if (++node_idx >= NETLBL_CATMAP_MAPCNT) {
 150                         if (iter->next == NULL)
 151                                 return iter->startbit + NETLBL_CATMAP_SIZE - 1;
 152                         iter = iter->next;
 153                         node_idx = 0;
 154                 }
 155                 bitmask = NETLBL_CATMAP_BIT;
 156                 node_bit = 0;
 157         }
 158
 159         return -ENOENT;
 160 }
 161
 162 /**
 163  * netlbl_secattr_catmap_setbit - Set a bit in a LSM secattr catmap
 164  * @catmap: the category bitmap
 165  * @bit: the bit to set
 166  * @flags: memory allocation flags
 167  *
 168  * Description:
 169  * Set the bit specified by @bit in @catmap.  Returns zero on success,
 170  * negative values on failure.
 171  *
 172  */
 173 int netlbl_secattr_catmap_setbit(struct netlbl_lsm_secattr_catmap *catmap,
 174                                  u32 bit,
 175                                  gfp_t flags)
 176 {
 177         struct netlbl_lsm_secattr_catmap *iter = catmap;
 178         u32 node_bit;
 179         u32 node_idx;
 180
 181         while (iter->next != NULL &&
 182                bit >= (iter->startbit + NETLBL_CATMAP_SIZE))
 183                 iter = iter->next;
 184         if (bit >= (iter->startbit + NETLBL_CATMAP_SIZE)) {
 185                 iter->next = netlbl_secattr_catmap_alloc(flags);
 186                 if (iter->next == NULL)
 187                         return -ENOMEM;
 188                 iter = iter->next;
 189                 iter->startbit = bit & ~(NETLBL_CATMAP_SIZE - 1);
 190         }
 191
 192         /* gcc always rounds to zero when doing integer division */
 193         node_idx = (bit - iter->startbit) / NETLBL_CATMAP_MAPSIZE;
 194         node_bit = bit - iter->startbit - (NETLBL_CATMAP_MAPSIZE * node_idx);
 195         iter->bitmap[node_idx] |= NETLBL_CATMAP_BIT << node_bit;
 196
 197         return 0;
 198 }
 199
 200 /**
 201  * netlbl_secattr_catmap_setrng - Set a range of bits in a LSM secattr catmap
 202  * @catmap: the category bitmap
 203  * @start: the starting bit
 204  * @end: the last bit in the string
 205  * @flags: memory allocation flags
 206  *
 207  * Description:
 208  * Set a range of bits, starting at @start and ending with @end.  Returns zero
 209  * on success, negative values on failure.
 210  *
 211  */
 212 int netlbl_secattr_catmap_setrng(struct netlbl_lsm_secattr_catmap *catmap,
 213                                  u32 start,
 214                                  u32 end,
 215                                  gfp_t flags)
 216 {
 217         int ret_val = 0;
 218         struct netlbl_lsm_secattr_catmap *iter = catmap;
 219         u32 iter_max_spot;
 220         u32 spot;
 221
 222         /* XXX - This could probably be made a bit faster by combining writes
 223          * to the catmap instead of setting a single bit each time, but for
 224          * right now skipping to the start of the range in the catmap should
 225          * be a nice improvement over calling the individual setbit function
 226          * repeatedly from a loop. */
 227
 228         while (iter->next != NULL &&
 229                start >= (iter->startbit + NETLBL_CATMAP_SIZE))
 230                 iter = iter->next;
 231         iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
 232
 233         for (spot = start; spot <= end && ret_val == 0; spot++) {
 234                 if (spot >= iter_max_spot && iter->next != NULL) {
 235                         iter = iter->next;
 236                         iter_max_spot = iter->startbit + NETLBL_CATMAP_SIZE;
 237                 }
 238                 ret_val = netlbl_secattr_catmap_setbit(iter, spot, GFP_ATOMIC);
 239         }
 240
 241         return ret_val;
 242 }
 243
 244 /*
 245  * LSM Functions
 246  */
 247
 248 /**
 249  * netlbl_enabled - Determine if the NetLabel subsystem is enabled
 250  *
 251  * Description:
 252  * The LSM can use this function to determine if it should use NetLabel
 253  * security attributes in it's enforcement mechanism.  Currently, NetLabel is
 254  * considered to be enabled when it's configuration contains a valid setup for
 255  * at least one labeled protocol (i.e. NetLabel can understand incoming
 256  * labeled packets of at least one type); otherwise NetLabel is considered to
 257  * be disabled.
 258  *
 259  */
 260 int netlbl_enabled(void)
 261 {
 262         /* At some point we probably want to expose this mechanism to the user
 263          * as well so that admins can toggle NetLabel regardless of the
 264          * configuration */
 265         return (netlbl_mgmt_protocount_value() > 0 ? 1 : 0);
 266 }
 267
 268 /**
 269  * netlbl_socket_setattr - Label a socket using the correct protocol
 270  * @sk: the socket to label
 271  * @secattr: the security attributes
 272  *
 273  * Description:
 274  * Attach the correct label to the given socket using the security attributes
 275  * specified in @secattr.  This function requires exclusive access to @sk,
 276  * which means it either needs to be in the process of being created or locked.
 277  * Returns zero on success, negative values on failure.
 278  *
 279  */
 280 int netlbl_sock_setattr(struct sock *sk,
 281                         const struct netlbl_lsm_secattr *secattr)
 282 {
 283         int ret_val = -ENOENT;
 284         struct netlbl_dom_map *dom_entry;
 285
 286         rcu_read_lock();
 287         dom_entry = netlbl_domhsh_getentry(secattr->domain);
 288         if (dom_entry == NULL)
 289                 goto socket_setattr_return;
 290         switch (dom_entry->type) {
 291         case NETLBL_NLTYPE_CIPSOV4:
 292                 ret_val = cipso_v4_sock_setattr(sk,
 293                                                 dom_entry->type_def.cipsov4,
 294                                                 secattr);
 295                 break;
 296         case NETLBL_NLTYPE_UNLABELED:
 297                 ret_val = 0;
 298                 break;
 299         default:
 300                 ret_val = -ENOENT;
 301         }
 302
 303 socket_setattr_return:
 304         rcu_read_unlock();
 305         return ret_val;
 306 }
 307
 308 /**
 309  * netlbl_sock_getattr - Determine the security attributes of a sock
 310  * @sk: the sock
 311  * @secattr: the security attributes
 312  *
 313  * Description:
 314  * Examines the given sock to see any NetLabel style labeling has been
 315  * applied to the sock, if so it parses the socket label and returns the
 316  * security attributes in @secattr.  Returns zero on success, negative values
 317  * on failure.
 318  *
 319  */
 320 int netlbl_sock_getattr(struct sock *sk, struct netlbl_lsm_secattr *secattr)
 321 {
 322         int ret_val;
 323
 324         ret_val = cipso_v4_sock_getattr(sk, secattr);
 325         if (ret_val == 0)
 326                 return 0;
 327
 328         return netlbl_unlabel_getattr(secattr);
 329 }
 330
 331 /**
 332  * netlbl_skbuff_getattr - Determine the security attributes of a packet
 333  * @skb: the packet
 334  * @secattr: the security attributes
 335  *
 336  * Description:
 337  * Examines the given packet to see if a recognized form of packet labeling
 338  * is present, if so it parses the packet label and returns the security
 339  * attributes in @secattr.  Returns zero on success, negative values on
 340  * failure.
 341  *
 342  */
 343 int netlbl_skbuff_getattr(const struct sk_buff *skb,
 344                           struct netlbl_lsm_secattr *secattr)
 345 {
 346         if (CIPSO_V4_OPTEXIST(skb) &&
 347             cipso_v4_skbuff_getattr(skb, secattr) == 0)
 348                 return 0;
 349
 350         return netlbl_unlabel_getattr(secattr);
 351 }
 352
 353 /**
 354  * netlbl_skbuff_err - Handle a LSM error on a sk_buff
 355  * @skb: the packet
 356  * @error: the error code
 357  *
 358  * Description:
 359  * Deal with a LSM problem when handling the packet in @skb, typically this is
 360  * a permission denied problem (-EACCES).  The correct action is determined
 361  * according to the packet's labeling protocol.
 362  *
 363  */
 364 void netlbl_skbuff_err(struct sk_buff *skb, int error)
 365 {
 366         if (CIPSO_V4_OPTEXIST(skb))
 367                 cipso_v4_error(skb, error, 0);
 368 }
 369
 370 /**
 371  * netlbl_cache_invalidate - Invalidate all of the NetLabel protocol caches
 372  *
 373  * Description:
 374  * For all of the NetLabel protocols that support some form of label mapping
 375  * cache, invalidate the cache.  Returns zero on success, negative values on
 376  * error.
 377  *
 378  */
 379 void netlbl_cache_invalidate(void)
 380 {
 381         cipso_v4_cache_invalidate();
 382 }
 383
 384 /**
 385  * netlbl_cache_add - Add an entry to a NetLabel protocol cache
 386  * @skb: the packet
 387  * @secattr: the packet's security attributes
 388  *
 389  * Description:
 390  * Add the LSM security attributes for the given packet to the underlying
 391  * NetLabel protocol's label mapping cache.  Returns zero on success, negative
 392  * values on error.
 393  *
 394  */
 395 int netlbl_cache_add(const struct sk_buff *skb,
 396                      const struct netlbl_lsm_secattr *secattr)
 397 {
 398         if ((secattr->flags & NETLBL_SECATTR_CACHE) == 0)
 399                 return -ENOMSG;
 400
 401         if (CIPSO_V4_OPTEXIST(skb))
 402                 return cipso_v4_cache_add(skb, secattr);
 403
 404         return -ENOMSG;
 405 }
 406
 407 /*
 408  * Setup Functions
 409  */
 410
 411 /**
 412  * netlbl_init - Initialize NetLabel
 413  *
 414  * Description:
 415  * Perform the required NetLabel initialization before first use.
 416  *
 417  */
 418 static int __init netlbl_init(void)
 419 {
 420         int ret_val;
 421
 422         printk(KERN_INFO "NetLabel: Initializing\n");
 423         printk(KERN_INFO "NetLabel:  domain hash size = %u\n",
 424                (1 << NETLBL_DOMHSH_BITSIZE));
 425         printk(KERN_INFO "NetLabel:  protocols ="
 426                " UNLABELED"
 427                " CIPSOv4"
 428                "\n");
 429
 430         ret_val = netlbl_domhsh_init(NETLBL_DOMHSH_BITSIZE);
 431         if (ret_val != 0)
 432                 goto init_failure;
 433
 434         ret_val = netlbl_netlink_init();
 435         if (ret_val != 0)
 436                 goto init_failure;
 437
 438         ret_val = netlbl_unlabel_defconf();
 439         if (ret_val != 0)
 440                 goto init_failure;
 441         printk(KERN_INFO "NetLabel:  unlabeled traffic allowed by default\n");
 442
 443         return 0;
 444
 445 init_failure:
 446         panic("NetLabel: failed to initialize properly (%d)\n", ret_val);
 447 }
 448
 449 subsys_initcall(netlbl_init);