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                                            u16 family,
  58                                            struct netlbl_lsm_secattr *secattr,
  59                                            u32 *sid)
  60 {
  61         int rc;
  62
  63         rc = security_netlbl_secattr_to_sid(secattr, sid);
  64         if (rc == 0 &&
  65             (secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
  66             (secattr->flags & NETLBL_SECATTR_CACHE))
  67                 netlbl_cache_add(skb, family, secattr);
  68
  69         return rc;
  70 }
  71
  72 /**
  73  * selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
  74  * @sk: the socket
  75  *
  76  * Description:
  77  * Generate the NetLabel security attributes for a socket, making full use of
  78  * the socket's attribute cache.  Returns a pointer to the security attributes
  79  * on success, NULL on failure.
  80  *
  81  */
  82 static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
  83 {
  84         int rc;
  85         struct sk_security_struct *sksec = sk->sk_security;
  86         struct netlbl_lsm_secattr *secattr;
  87
  88         if (sksec->nlbl_secattr != NULL)
  89                 return sksec->nlbl_secattr;
  90
  91         secattr = netlbl_secattr_alloc(GFP_ATOMIC);
  92         if (secattr == NULL)
  93                 return NULL;
  94         rc = security_netlbl_sid_to_secattr(sksec->sid, secattr);
  95         if (rc != 0) {
  96                 netlbl_secattr_free(secattr);
  97                 return NULL;
  98         }
  99         sksec->nlbl_secattr = secattr;
 100
 101         return secattr;
 102 }
 103
 104 /**
 105  * selinux_netlbl_sock_getattr - Get the cached NetLabel secattr
 106  * @sk: the socket
 107  * @sid: the SID
 108  *
 109  * Query the socket's cached secattr and if the SID matches the cached value
 110  * return the cache, otherwise return NULL.
 111  *
 112  */
 113 static struct netlbl_lsm_secattr *selinux_netlbl_sock_getattr(
 114                                                         const struct sock *sk,
 115                                                         u32 sid)
 116 {
 117         struct sk_security_struct *sksec = sk->sk_security;
 118         struct netlbl_lsm_secattr *secattr = sksec->nlbl_secattr;
 119
 120         if (secattr == NULL)
 121                 return NULL;
 122
 123         if ((secattr->flags & NETLBL_SECATTR_SECID) &&
 124             (secattr->attr.secid == sid))
 125                 return secattr;
 126
 127         return NULL;
 128 }
 129
 130 /**
 131  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
 132  *
 133  * Description:
 134  * Invalidate the NetLabel security attribute mapping cache.
 135  *
 136  */
 137 void selinux_netlbl_cache_invalidate(void)
 138 {
 139         netlbl_cache_invalidate();
 140 }
 141
 142 /**
 143  * selinux_netlbl_err - Handle a NetLabel packet error
 144  * @skb: the packet
 145  * @error: the error code
 146  * @gateway: true if host is acting as a gateway, false otherwise
 147  *
 148  * Description:
 149  * When a packet is dropped due to a call to avc_has_perm() pass the error
 150  * code to the NetLabel subsystem so any protocol specific processing can be
 151  * done.  This is safe to call even if you are unsure if NetLabel labeling is
 152  * present on the packet, NetLabel is smart enough to only act when it should.
 153  *
 154  */
 155 void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error, int gateway)
 156 {
 157         netlbl_skbuff_err(skb, family, error, gateway);
 158 }
 159
 160 /**
 161  * selinux_netlbl_sk_security_free - Free the NetLabel fields
 162  * @sksec: the sk_security_struct
 163  *
 164  * Description:
 165  * Free all of the memory in the NetLabel fields of a sk_security_struct.
 166  *
 167  */
 168 void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
 169 {
 170         if (sksec->nlbl_secattr != NULL)
 171                 netlbl_secattr_free(sksec->nlbl_secattr);
 172 }
 173
 174 /**
 175  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 176  * @sksec: the sk_security_struct
 177  * @family: the socket family
 178  *
 179  * Description:
 180  * Called when the NetLabel state of a sk_security_struct needs to be reset.
 181  * The caller is responsible for all the NetLabel sk_security_struct locking.
 182  *
 183  */
 184 void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
 185 {
 186         sksec->nlbl_state = NLBL_UNSET;
 187 }
 188
 189 /**
 190  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 191  * @skb: the packet
 192  * @family: protocol family
 193  * @type: NetLabel labeling protocol type
 194  * @sid: the SID
 195  *
 196  * Description:
 197  * Call the NetLabel mechanism to get the security attributes of the given
 198  * packet and use those attributes to determine the correct context/SID to
 199  * assign to the packet.  Returns zero on success, negative values on failure.
 200  *
 201  */
 202 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 203                                  u16 family,
 204                                  u32 *type,
 205                                  u32 *sid)
 206 {
 207         int rc;
 208         struct netlbl_lsm_secattr secattr;
 209
 210         if (!netlbl_enabled()) {
 211                 *sid = SECSID_NULL;
 212                 return 0;
 213         }
 214
 215         netlbl_secattr_init(&secattr);
 216         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 217         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 218                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 219                                                      &secattr, sid);
 220         else
 221                 *sid = SECSID_NULL;
 222         *type = secattr.type;
 223         netlbl_secattr_destroy(&secattr);
 224
 225         return rc;
 226 }
 227
 228 /**
 229  * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
 230  * @skb: the packet
 231  * @family: protocol family
 232  * @sid: the SID
 233  *
 234  * Description
 235  * Call the NetLabel mechanism to set the label of a packet using @sid.
 236  * Returns zero on success, negative values on failure.
 237  *
 238  */
 239 int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
 240                                  u16 family,
 241                                  u32 sid)
 242 {
 243         int rc;
 244         struct netlbl_lsm_secattr secattr_storage;
 245         struct netlbl_lsm_secattr *secattr = NULL;
 246         struct sock *sk;
 247
 248         /* if this is a locally generated packet check to see if it is already
 249          * being labeled by it's parent socket, if it is just exit */
 250         sk = skb_to_full_sk(skb);
 251         if (sk != NULL) {
 252                 struct sk_security_struct *sksec = sk->sk_security;
 253                 if (sksec->nlbl_state != NLBL_REQSKB)
 254                         return 0;
 255                 secattr = selinux_netlbl_sock_getattr(sk, sid);
 256         }
 257         if (secattr == NULL) {
 258                 secattr = &secattr_storage;
 259                 netlbl_secattr_init(secattr);
 260                 rc = security_netlbl_sid_to_secattr(sid, secattr);
 261                 if (rc != 0)
 262                         goto skbuff_setsid_return;
 263         }
 264
 265         rc = netlbl_skbuff_setattr(skb, family, secattr);
 266
 267 skbuff_setsid_return:
 268         if (secattr == &secattr_storage)
 269                 netlbl_secattr_destroy(secattr);
 270         return rc;
 271 }
 272
 273 /**
 274  * selinux_netlbl_inet_conn_request - Label an incoming stream connection
 275  * @req: incoming connection request socket
 276  *
 277  * Description:
 278  * A new incoming connection request is represented by @req, we need to label
 279  * the new request_sock here and the stack will ensure the on-the-wire label
 280  * will get preserved when a full sock is created once the connection handshake
 281  * is complete.  Returns zero on success, negative values on failure.
 282  *
 283  */
 284 int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
 285 {
 286         int rc;
 287         struct netlbl_lsm_secattr secattr;
 288
 289         if (family != PF_INET && family != PF_INET6)
 290                 return 0;
 291
 292         netlbl_secattr_init(&secattr);
 293         rc = security_netlbl_sid_to_secattr(req->secid, &secattr);
 294         if (rc != 0)
 295                 goto inet_conn_request_return;
 296         rc = netlbl_req_setattr(req, &secattr);
 297 inet_conn_request_return:
 298         netlbl_secattr_destroy(&secattr);
 299         return rc;
 300 }
 301
 302 /**
 303  * selinux_netlbl_inet_csk_clone - Initialize the newly created sock
 304  * @sk: the new sock
 305  *
 306  * Description:
 307  * A new connection has been established using @sk, we've already labeled the
 308  * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
 309  * we need to set the NetLabel state here since we now have a sock structure.
 310  *
 311  */
 312 void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
 313 {
 314         struct sk_security_struct *sksec = sk->sk_security;
 315
 316         if (family == PF_INET)
 317                 sksec->nlbl_state = NLBL_LABELED;
 318         else
 319                 sksec->nlbl_state = NLBL_UNSET;
 320 }
 321
 322 /**
 323  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 324  * @sock: the socket to label
 325  * @family: protocol family
 326  *
 327  * Description:
 328  * Attempt to label a socket using the NetLabel mechanism using the given
 329  * SID.  Returns zero values on success, negative values on failure.
 330  *
 331  */
 332 int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
 333 {
 334         int rc;
 335         struct sk_security_struct *sksec = sk->sk_security;
 336         struct netlbl_lsm_secattr *secattr;
 337
 338         if (family != PF_INET && family != PF_INET6)
 339                 return 0;
 340
 341         secattr = selinux_netlbl_sock_genattr(sk);
 342         if (secattr == NULL)
 343                 return -ENOMEM;
 344         rc = netlbl_sock_setattr(sk, family, secattr);
 345         switch (rc) {
 346         case 0:
 347                 sksec->nlbl_state = NLBL_LABELED;
 348                 break;
 349         case -EDESTADDRREQ:
 350                 sksec->nlbl_state = NLBL_REQSKB;
 351                 rc = 0;
 352                 break;
 353         }
 354
 355         return rc;
 356 }
 357
 358 /**
 359  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 360  * @sksec: the sock's sk_security_struct
 361  * @skb: the packet
 362  * @family: protocol family
 363  * @ad: the audit data
 364  *
 365  * Description:
 366  * Fetch the NetLabel security attributes from @skb and perform an access check
 367  * against the receiving socket.  Returns zero on success, negative values on
 368  * error.
 369  *
 370  */
 371 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 372                                 struct sk_buff *skb,
 373                                 u16 family,
 374                                 struct common_audit_data *ad)
 375 {
 376         int rc;
 377         u32 nlbl_sid;
 378         u32 perm;
 379         struct netlbl_lsm_secattr secattr;
 380
 381         if (!netlbl_enabled())
 382                 return 0;
 383
 384         netlbl_secattr_init(&secattr);
 385         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 386         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 387                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 388                                                      &secattr, &nlbl_sid);
 389         else
 390                 nlbl_sid = SECINITSID_UNLABELED;
 391         netlbl_secattr_destroy(&secattr);
 392         if (rc != 0)
 393                 return rc;
 394
 395         switch (sksec->sclass) {
 396         case SECCLASS_UDP_SOCKET:
 397                 perm = UDP_SOCKET__RECVFROM;
 398                 break;
 399         case SECCLASS_TCP_SOCKET:
 400                 perm = TCP_SOCKET__RECVFROM;
 401                 break;
 402         default:
 403                 perm = RAWIP_SOCKET__RECVFROM;
 404         }
 405
 406         rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 407         if (rc == 0)
 408                 return 0;
 409
 410         if (nlbl_sid != SECINITSID_UNLABELED)
 411                 netlbl_skbuff_err(skb, family, rc, 0);
 412         return rc;
 413 }
 414
 415 /**
 416  * selinux_netlbl_option - Is this a NetLabel option
 417  * @level: the socket level or protocol
 418  * @optname: the socket option name
 419  *
 420  * Description:
 421  * Returns true if @level and @optname refer to a NetLabel option.
 422  * Helper for selinux_netlbl_socket_setsockopt().
 423  */
 424 static inline int selinux_netlbl_option(int level, int optname)
 425 {
 426         return (level == IPPROTO_IP && optname == IP_OPTIONS) ||
 427                 (level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS);
 428 }
 429
 430 /**
 431  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 432  * @sock: the socket
 433  * @level: the socket level or protocol
 434  * @optname: the socket option name
 435  *
 436  * Description:
 437  * Check the setsockopt() call and if the user is trying to replace the IP
 438  * options on a socket and a NetLabel is in place for the socket deny the
 439  * access; otherwise allow the access.  Returns zero when the access is
 440  * allowed, -EACCES when denied, and other negative values on error.
 441  *
 442  */
 443 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 444                                      int level,
 445                                      int optname)
 446 {
 447         int rc = 0;
 448         struct sock *sk = sock->sk;
 449         struct sk_security_struct *sksec = sk->sk_security;
 450         struct netlbl_lsm_secattr secattr;
 451
 452         if (selinux_netlbl_option(level, optname) &&
 453             (sksec->nlbl_state == NLBL_LABELED ||
 454              sksec->nlbl_state == NLBL_CONNLABELED)) {
 455                 netlbl_secattr_init(&secattr);
 456                 lock_sock(sk);
 457                 /* call the netlabel function directly as we want to see the
 458                  * on-the-wire label that is assigned via the socket's options
 459                  * and not the cached netlabel/lsm attributes */
 460                 rc = netlbl_sock_getattr(sk, &secattr);
 461                 release_sock(sk);
 462                 if (rc == 0)
 463                         rc = -EACCES;
 464                 else if (rc == -ENOMSG)
 465                         rc = 0;
 466                 netlbl_secattr_destroy(&secattr);
 467         }
 468
 469         return rc;
 470 }
 471
 472 /**
 473  * selinux_netlbl_socket_connect - Label a client-side socket on connect
 474  * @sk: the socket to label
 475  * @addr: the destination address
 476  *
 477  * Description:
 478  * Attempt to label a connected socket with NetLabel using the given address.
 479  * Returns zero values on success, negative values on failure.
 480  *
 481  */
 482 int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
 483 {
 484         int rc;
 485         struct sk_security_struct *sksec = sk->sk_security;
 486         struct netlbl_lsm_secattr *secattr;
 487
 488         if (sksec->nlbl_state != NLBL_REQSKB &&
 489             sksec->nlbl_state != NLBL_CONNLABELED)
 490                 return 0;
 491
 492         lock_sock(sk);
 493
 494         /* connected sockets are allowed to disconnect when the address family
 495          * is set to AF_UNSPEC, if that is what is happening we want to reset
 496          * the socket */
 497         if (addr->sa_family == AF_UNSPEC) {
 498                 netlbl_sock_delattr(sk);
 499                 sksec->nlbl_state = NLBL_REQSKB;
 500                 rc = 0;
 501                 goto socket_connect_return;
 502         }
 503         secattr = selinux_netlbl_sock_genattr(sk);
 504         if (secattr == NULL) {
 505                 rc = -ENOMEM;
 506                 goto socket_connect_return;
 507         }
 508         rc = netlbl_conn_setattr(sk, addr, secattr);
 509         if (rc == 0)
 510                 sksec->nlbl_state = NLBL_CONNLABELED;
 511
 512 socket_connect_return:
 513         release_sock(sk);
 514         return rc;
 515 }