security/selinux/netlabel.c

   1 /*
   2  * SELinux NetLabel Support
   3  *
   4  * This file provides the necessary glue to tie NetLabel into the SELinux
   5  * subsystem.
   6  *
   7  * Author: Paul Moore <paul@paul-moore.com>
   8  *
   9  */
  10
  11 /*
  12  * (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
  13  *
  14  * This program is free software;  you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * This program is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY;  without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See
  22  * the GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with this program;  if not, write to the Free Software
  26  * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
  27  *
  28  */
  29
  30 #include <linux/spinlock.h>
  31 #include <linux/rcupdate.h>
  32 #include <linux/gfp.h>
  33 #include <linux/ip.h>
  34 #include <linux/ipv6.h>
  35 #include <net/sock.h>
  36 #include <net/netlabel.h>
  37 #include <net/ip.h>
  38 #include <net/ipv6.h>
  39
  40 #include "objsec.h"
  41 #include "security.h"
  42 #include "netlabel.h"
  43
  44 /**
  45  * selinux_netlbl_sidlookup_cached - Cache a SID lookup
  46  * @skb: the packet
  47  * @secattr: the NetLabel security attributes
  48  * @sid: the SID
  49  *
  50  * Description:
  51  * Query the SELinux security server to lookup the correct SID for the given
  52  * security attributes.  If the query is successful, cache the result to speed
  53  * up future lookups.  Returns zero on success, negative values on failure.
  54  *
  55  */
  56 static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
  57                                            struct netlbl_lsm_secattr *secattr,
  58                                            u32 *sid)
  59 {
  60         int rc;
  61
  62         rc = security_netlbl_secattr_to_sid(secattr, sid);
  63         if (rc == 0 &&
  64             (secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
  65             (secattr->flags & NETLBL_SECATTR_CACHE))
  66                 netlbl_cache_add(skb, secattr);
  67
  68         return rc;
  69 }
  70
  71 /**
  72  * selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
  73  * @sk: the socket
  74  *
  75  * Description:
  76  * Generate the NetLabel security attributes for a socket, making full use of
  77  * the socket's attribute cache.  Returns a pointer to the security attributes
  78  * on success, NULL on failure.
  79  *
  80  */
  81 static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
  82 {
  83         int rc;
  84         struct sk_security_struct *sksec = sk->sk_security;
  85         struct netlbl_lsm_secattr *secattr;
  86
  87         if (sksec->nlbl_secattr != NULL)
  88                 return sksec->nlbl_secattr;
  89
  90         secattr = netlbl_secattr_alloc(GFP_ATOMIC);
  91         if (secattr == NULL)
  92                 return NULL;
  93         rc = security_netlbl_sid_to_secattr(sksec->sid, secattr);
  94         if (rc != 0) {
  95                 netlbl_secattr_free(secattr);
  96                 return NULL;
  97         }
  98         sksec->nlbl_secattr = secattr;
  99
 100         return secattr;
 101 }
 102
 103 /**
 104  * selinux_netlbl_sock_getattr - Get the cached NetLabel secattr
 105  * @sk: the socket
 106  * @sid: the SID
 107  *
 108  * Query the socket's cached secattr and if the SID matches the cached value
 109  * return the cache, otherwise return NULL.
 110  *
 111  */
 112 static struct netlbl_lsm_secattr *selinux_netlbl_sock_getattr(
 113                                                         const struct sock *sk,
 114                                                         u32 sid)
 115 {
 116         struct sk_security_struct *sksec = sk->sk_security;
 117         struct netlbl_lsm_secattr *secattr = sksec->nlbl_secattr;
 118
 119         if (secattr == NULL)
 120                 return NULL;
 121
 122         if ((secattr->flags & NETLBL_SECATTR_SECID) &&
 123             (secattr->attr.secid == sid))
 124                 return secattr;
 125
 126         return NULL;
 127 }
 128
 129 /**
 130  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
 131  *
 132  * Description:
 133  * Invalidate the NetLabel security attribute mapping cache.
 134  *
 135  */
 136 void selinux_netlbl_cache_invalidate(void)
 137 {
 138         netlbl_cache_invalidate();
 139 }
 140
 141 /**
 142  * selinux_netlbl_err - Handle a NetLabel packet error
 143  * @skb: the packet
 144  * @error: the error code
 145  * @gateway: true if host is acting as a gateway, false otherwise
 146  *
 147  * Description:
 148  * When a packet is dropped due to a call to avc_has_perm() pass the error
 149  * code to the NetLabel subsystem so any protocol specific processing can be
 150  * done.  This is safe to call even if you are unsure if NetLabel labeling is
 151  * present on the packet, NetLabel is smart enough to only act when it should.
 152  *
 153  */
 154 void selinux_netlbl_err(struct sk_buff *skb, int error, int gateway)
 155 {
 156         netlbl_skbuff_err(skb, error, gateway);
 157 }
 158
 159 /**
 160  * selinux_netlbl_sk_security_free - Free the NetLabel fields
 161  * @sksec: the sk_security_struct
 162  *
 163  * Description:
 164  * Free all of the memory in the NetLabel fields of a sk_security_struct.
 165  *
 166  */
 167 void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
 168 {
 169         if (sksec->nlbl_secattr != NULL)
 170                 netlbl_secattr_free(sksec->nlbl_secattr);
 171 }
 172
 173 /**
 174  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 175  * @sksec: the sk_security_struct
 176  * @family: the socket family
 177  *
 178  * Description:
 179  * Called when the NetLabel state of a sk_security_struct needs to be reset.
 180  * The caller is responsible for all the NetLabel sk_security_struct locking.
 181  *
 182  */
 183 void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
 184 {
 185         sksec->nlbl_state = NLBL_UNSET;
 186 }
 187
 188 /**
 189  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 190  * @skb: the packet
 191  * @family: protocol family
 192  * @type: NetLabel labeling protocol type
 193  * @sid: the SID
 194  *
 195  * Description:
 196  * Call the NetLabel mechanism to get the security attributes of the given
 197  * packet and use those attributes to determine the correct context/SID to
 198  * assign to the packet.  Returns zero on success, negative values on failure.
 199  *
 200  */
 201 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 202                                  u16 family,
 203                                  u32 *type,
 204                                  u32 *sid)
 205 {
 206         int rc;
 207         struct netlbl_lsm_secattr secattr;
 208
 209         if (!netlbl_enabled()) {
 210                 *sid = SECSID_NULL;
 211                 return 0;
 212         }
 213
 214         netlbl_secattr_init(&secattr);
 215         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 216         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 217                 rc = selinux_netlbl_sidlookup_cached(skb, &secattr, sid);
 218         else
 219                 *sid = SECSID_NULL;
 220         *type = secattr.type;
 221         netlbl_secattr_destroy(&secattr);
 222
 223         return rc;
 224 }
 225
 226 /**
 227  * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
 228  * @skb: the packet
 229  * @family: protocol family
 230  * @sid: the SID
 231  *
 232  * Description
 233  * Call the NetLabel mechanism to set the label of a packet using @sid.
 234  * Returns zero on success, negative values on failure.
 235  *
 236  */
 237 int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
 238                                  u16 family,
 239                                  u32 sid)
 240 {
 241         int rc;
 242         struct netlbl_lsm_secattr secattr_storage;
 243         struct netlbl_lsm_secattr *secattr = NULL;
 244         struct sock *sk;
 245
 246         /* if this is a locally generated packet check to see if it is already
 247          * being labeled by it's parent socket, if it is just exit */
 248         sk = skb->sk;
 249         if (sk != NULL) {
 250                 struct sk_security_struct *sksec = sk->sk_security;
 251                 if (sksec->nlbl_state != NLBL_REQSKB)
 252                         return 0;
 253                 secattr = selinux_netlbl_sock_getattr(sk, sid);
 254         }
 255         if (secattr == NULL) {
 256                 secattr = &secattr_storage;
 257                 netlbl_secattr_init(secattr);
 258                 rc = security_netlbl_sid_to_secattr(sid, secattr);
 259                 if (rc != 0)
 260                         goto skbuff_setsid_return;
 261         }
 262
 263         rc = netlbl_skbuff_setattr(skb, family, secattr);
 264
 265 skbuff_setsid_return:
 266         if (secattr == &secattr_storage)
 267                 netlbl_secattr_destroy(secattr);
 268         return rc;
 269 }
 270
 271 /**
 272  * selinux_netlbl_inet_conn_request - Label an incoming stream connection
 273  * @req: incoming connection request socket
 274  *
 275  * Description:
 276  * A new incoming connection request is represented by @req, we need to label
 277  * the new request_sock here and the stack will ensure the on-the-wire label
 278  * will get preserved when a full sock is created once the connection handshake
 279  * is complete.  Returns zero on success, negative values on failure.
 280  *
 281  */
 282 int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
 283 {
 284         int rc;
 285         struct netlbl_lsm_secattr secattr;
 286
 287         if (family != PF_INET)
 288                 return 0;
 289
 290         netlbl_secattr_init(&secattr);
 291         rc = security_netlbl_sid_to_secattr(req->secid, &secattr);
 292         if (rc != 0)
 293                 goto inet_conn_request_return;
 294         rc = netlbl_req_setattr(req, &secattr);
 295 inet_conn_request_return:
 296         netlbl_secattr_destroy(&secattr);
 297         return rc;
 298 }
 299
 300 /**
 301  * selinux_netlbl_inet_csk_clone - Initialize the newly created sock
 302  * @sk: the new sock
 303  *
 304  * Description:
 305  * A new connection has been established using @sk, we've already labeled the
 306  * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
 307  * we need to set the NetLabel state here since we now have a sock structure.
 308  *
 309  */
 310 void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
 311 {
 312         struct sk_security_struct *sksec = sk->sk_security;
 313
 314         if (family == PF_INET)
 315                 sksec->nlbl_state = NLBL_LABELED;
 316         else
 317                 sksec->nlbl_state = NLBL_UNSET;
 318 }
 319
 320 /**
 321  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 322  * @sock: the socket to label
 323  * @family: protocol family
 324  *
 325  * Description:
 326  * Attempt to label a socket using the NetLabel mechanism using the given
 327  * SID.  Returns zero values on success, negative values on failure.
 328  *
 329  */
 330 int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
 331 {
 332         int rc;
 333         struct sk_security_struct *sksec = sk->sk_security;
 334         struct netlbl_lsm_secattr *secattr;
 335
 336         if (family != PF_INET)
 337                 return 0;
 338
 339         secattr = selinux_netlbl_sock_genattr(sk);
 340         if (secattr == NULL)
 341                 return -ENOMEM;
 342         rc = netlbl_sock_setattr(sk, family, secattr);
 343         switch (rc) {
 344         case 0:
 345                 sksec->nlbl_state = NLBL_LABELED;
 346                 break;
 347         case -EDESTADDRREQ:
 348                 sksec->nlbl_state = NLBL_REQSKB;
 349                 rc = 0;
 350                 break;
 351         }
 352
 353         return rc;
 354 }
 355
 356 /**
 357  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 358  * @sksec: the sock's sk_security_struct
 359  * @skb: the packet
 360  * @family: protocol family
 361  * @ad: the audit data
 362  *
 363  * Description:
 364  * Fetch the NetLabel security attributes from @skb and perform an access check
 365  * against the receiving socket.  Returns zero on success, negative values on
 366  * error.
 367  *
 368  */
 369 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 370                                 struct sk_buff *skb,
 371                                 u16 family,
 372                                 struct common_audit_data *ad)
 373 {
 374         int rc;
 375         u32 nlbl_sid;
 376         u32 perm;
 377         struct netlbl_lsm_secattr secattr;
 378
 379         if (!netlbl_enabled())
 380                 return 0;
 381
 382         netlbl_secattr_init(&secattr);
 383         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 384         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 385                 rc = selinux_netlbl_sidlookup_cached(skb, &secattr, &nlbl_sid);
 386         else
 387                 nlbl_sid = SECINITSID_UNLABELED;
 388         netlbl_secattr_destroy(&secattr);
 389         if (rc != 0)
 390                 return rc;
 391
 392         switch (sksec->sclass) {
 393         case SECCLASS_UDP_SOCKET:
 394                 perm = UDP_SOCKET__RECVFROM;
 395                 break;
 396         case SECCLASS_TCP_SOCKET:
 397                 perm = TCP_SOCKET__RECVFROM;
 398                 break;
 399         default:
 400                 perm = RAWIP_SOCKET__RECVFROM;
 401         }
 402
 403         rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 404         if (rc == 0)
 405                 return 0;
 406
 407         if (nlbl_sid != SECINITSID_UNLABELED)
 408                 netlbl_skbuff_err(skb, rc, 0);
 409         return rc;
 410 }
 411
 412 /**
 413  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 414  * @sock: the socket
 415  * @level: the socket level or protocol
 416  * @optname: the socket option name
 417  *
 418  * Description:
 419  * Check the setsockopt() call and if the user is trying to replace the IP
 420  * options on a socket and a NetLabel is in place for the socket deny the
 421  * access; otherwise allow the access.  Returns zero when the access is
 422  * allowed, -EACCES when denied, and other negative values on error.
 423  *
 424  */
 425 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 426                                      int level,
 427                                      int optname)
 428 {
 429         int rc = 0;
 430         struct sock *sk = sock->sk;
 431         struct sk_security_struct *sksec = sk->sk_security;
 432         struct netlbl_lsm_secattr secattr;
 433
 434         if (level == IPPROTO_IP && optname == IP_OPTIONS &&
 435             (sksec->nlbl_state == NLBL_LABELED ||
 436              sksec->nlbl_state == NLBL_CONNLABELED)) {
 437                 netlbl_secattr_init(&secattr);
 438                 lock_sock(sk);
 439                 /* call the netlabel function directly as we want to see the
 440                  * on-the-wire label that is assigned via the socket's options
 441                  * and not the cached netlabel/lsm attributes */
 442                 rc = netlbl_sock_getattr(sk, &secattr);
 443                 release_sock(sk);
 444                 if (rc == 0)
 445                         rc = -EACCES;
 446                 else if (rc == -ENOMSG)
 447                         rc = 0;
 448                 netlbl_secattr_destroy(&secattr);
 449         }
 450
 451         return rc;
 452 }
 453
 454 /**
 455  * selinux_netlbl_socket_connect - Label a client-side socket on connect
 456  * @sk: the socket to label
 457  * @addr: the destination address
 458  *
 459  * Description:
 460  * Attempt to label a connected socket with NetLabel using the given address.
 461  * Returns zero values on success, negative values on failure.
 462  *
 463  */
 464 int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
 465 {
 466         int rc;
 467         struct sk_security_struct *sksec = sk->sk_security;
 468         struct netlbl_lsm_secattr *secattr;
 469
 470         if (sksec->nlbl_state != NLBL_REQSKB &&
 471             sksec->nlbl_state != NLBL_CONNLABELED)
 472                 return 0;
 473
 474         lock_sock(sk);
 475
 476         /* connected sockets are allowed to disconnect when the address family
 477          * is set to AF_UNSPEC, if that is what is happening we want to reset
 478          * the socket */
 479         if (addr->sa_family == AF_UNSPEC) {
 480                 netlbl_sock_delattr(sk);
 481                 sksec->nlbl_state = NLBL_REQSKB;
 482                 rc = 0;
 483                 goto socket_connect_return;
 484         }
 485         secattr = selinux_netlbl_sock_genattr(sk);
 486         if (secattr == NULL) {
 487                 rc = -ENOMEM;
 488                 goto socket_connect_return;
 489         }
 490         rc = netlbl_conn_setattr(sk, addr, secattr);
 491         if (rc == 0)
 492                 sksec->nlbl_state = NLBL_CONNLABELED;
 493
 494 socket_connect_return:
 495         release_sock(sk);
 496         return rc;
 497 }