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, see <http://www.gnu.org/licenses/>.
  26  *
  27  */
  28
  29 #include <linux/spinlock.h>
  30 #include <linux/rcupdate.h>
  31 #include <linux/gfp.h>
  32 #include <linux/ip.h>
  33 #include <linux/ipv6.h>
  34 #include <net/sock.h>
  35 #include <net/netlabel.h>
  36 #include <net/ip.h>
  37 #include <net/ipv6.h>
  38
  39 #include "objsec.h"
  40 #include "security.h"
  41 #include "netlabel.h"
  42
  43 /**
  44  * selinux_netlbl_sidlookup_cached - Cache a SID lookup
  45  * @skb: the packet
  46  * @secattr: the NetLabel security attributes
  47  * @sid: the SID
  48  *
  49  * Description:
  50  * Query the SELinux security server to lookup the correct SID for the given
  51  * security attributes.  If the query is successful, cache the result to speed
  52  * up future lookups.  Returns zero on success, negative values on failure.
  53  *
  54  */
  55 static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
  56                                            u16 family,
  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, family, 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, u16 family, int error, int gateway)
 155 {
 156         netlbl_skbuff_err(skb, family, 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, family,
 218                                                      &secattr, sid);
 219         else
 220                 *sid = SECSID_NULL;
 221         *type = secattr.type;
 222         netlbl_secattr_destroy(&secattr);
 223
 224         return rc;
 225 }
 226
 227 /**
 228  * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
 229  * @skb: the packet
 230  * @family: protocol family
 231  * @sid: the SID
 232  *
 233  * Description
 234  * Call the NetLabel mechanism to set the label of a packet using @sid.
 235  * Returns zero on success, negative values on failure.
 236  *
 237  */
 238 int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
 239                                  u16 family,
 240                                  u32 sid)
 241 {
 242         int rc;
 243         struct netlbl_lsm_secattr secattr_storage;
 244         struct netlbl_lsm_secattr *secattr = NULL;
 245         struct sock *sk;
 246
 247         /* if this is a locally generated packet check to see if it is already
 248          * being labeled by it's parent socket, if it is just exit */
 249         sk = skb_to_full_sk(skb);
 250         if (sk != NULL) {
 251                 struct sk_security_struct *sksec = sk->sk_security;
 252                 if (sksec->nlbl_state != NLBL_REQSKB)
 253                         return 0;
 254                 secattr = selinux_netlbl_sock_getattr(sk, sid);
 255         }
 256         if (secattr == NULL) {
 257                 secattr = &secattr_storage;
 258                 netlbl_secattr_init(secattr);
 259                 rc = security_netlbl_sid_to_secattr(sid, secattr);
 260                 if (rc != 0)
 261                         goto skbuff_setsid_return;
 262         }
 263
 264         rc = netlbl_skbuff_setattr(skb, family, secattr);
 265
 266 skbuff_setsid_return:
 267         if (secattr == &secattr_storage)
 268                 netlbl_secattr_destroy(secattr);
 269         return rc;
 270 }
 271
 272 /**
 273  * selinux_netlbl_inet_conn_request - Label an incoming stream connection
 274  * @req: incoming connection request socket
 275  *
 276  * Description:
 277  * A new incoming connection request is represented by @req, we need to label
 278  * the new request_sock here and the stack will ensure the on-the-wire label
 279  * will get preserved when a full sock is created once the connection handshake
 280  * is complete.  Returns zero on success, negative values on failure.
 281  *
 282  */
 283 int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
 284 {
 285         int rc;
 286         struct netlbl_lsm_secattr secattr;
 287
 288         if (family != PF_INET && family != PF_INET6)
 289                 return 0;
 290
 291         netlbl_secattr_init(&secattr);
 292         rc = security_netlbl_sid_to_secattr(req->secid, &secattr);
 293         if (rc != 0)
 294                 goto inet_conn_request_return;
 295         rc = netlbl_req_setattr(req, &secattr);
 296 inet_conn_request_return:
 297         netlbl_secattr_destroy(&secattr);
 298         return rc;
 299 }
 300
 301 /**
 302  * selinux_netlbl_inet_csk_clone - Initialize the newly created sock
 303  * @sk: the new sock
 304  *
 305  * Description:
 306  * A new connection has been established using @sk, we've already labeled the
 307  * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
 308  * we need to set the NetLabel state here since we now have a sock structure.
 309  *
 310  */
 311 void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
 312 {
 313         struct sk_security_struct *sksec = sk->sk_security;
 314
 315         if (family == PF_INET)
 316                 sksec->nlbl_state = NLBL_LABELED;
 317         else
 318                 sksec->nlbl_state = NLBL_UNSET;
 319 }
 320
 321 /**
 322  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 323  * @sock: the socket to label
 324  * @family: protocol family
 325  *
 326  * Description:
 327  * Attempt to label a socket using the NetLabel mechanism using the given
 328  * SID.  Returns zero values on success, negative values on failure.
 329  *
 330  */
 331 int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
 332 {
 333         int rc;
 334         struct sk_security_struct *sksec = sk->sk_security;
 335         struct netlbl_lsm_secattr *secattr;
 336
 337         if (family != PF_INET && family != PF_INET6)
 338                 return 0;
 339
 340         secattr = selinux_netlbl_sock_genattr(sk);
 341         if (secattr == NULL)
 342                 return -ENOMEM;
 343         rc = netlbl_sock_setattr(sk, family, secattr);
 344         switch (rc) {
 345         case 0:
 346                 sksec->nlbl_state = NLBL_LABELED;
 347                 break;
 348         case -EDESTADDRREQ:
 349                 sksec->nlbl_state = NLBL_REQSKB;
 350                 rc = 0;
 351                 break;
 352         }
 353
 354         return rc;
 355 }
 356
 357 /**
 358  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 359  * @sksec: the sock's sk_security_struct
 360  * @skb: the packet
 361  * @family: protocol family
 362  * @ad: the audit data
 363  *
 364  * Description:
 365  * Fetch the NetLabel security attributes from @skb and perform an access check
 366  * against the receiving socket.  Returns zero on success, negative values on
 367  * error.
 368  *
 369  */
 370 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 371                                 struct sk_buff *skb,
 372                                 u16 family,
 373                                 struct common_audit_data *ad)
 374 {
 375         int rc;
 376         u32 nlbl_sid;
 377         u32 perm;
 378         struct netlbl_lsm_secattr secattr;
 379
 380         if (!netlbl_enabled())
 381                 return 0;
 382
 383         netlbl_secattr_init(&secattr);
 384         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 385         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 386                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 387                                                      &secattr, &nlbl_sid);
 388         else
 389                 nlbl_sid = SECINITSID_UNLABELED;
 390         netlbl_secattr_destroy(&secattr);
 391         if (rc != 0)
 392                 return rc;
 393
 394         switch (sksec->sclass) {
 395         case SECCLASS_UDP_SOCKET:
 396                 perm = UDP_SOCKET__RECVFROM;
 397                 break;
 398         case SECCLASS_TCP_SOCKET:
 399                 perm = TCP_SOCKET__RECVFROM;
 400                 break;
 401         default:
 402                 perm = RAWIP_SOCKET__RECVFROM;
 403         }
 404
 405         rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 406         if (rc == 0)
 407                 return 0;
 408
 409         if (nlbl_sid != SECINITSID_UNLABELED)
 410                 netlbl_skbuff_err(skb, family, rc, 0);
 411         return rc;
 412 }
 413
 414 /**
 415  * selinux_netlbl_option - Is this a NetLabel option
 416  * @level: the socket level or protocol
 417  * @optname: the socket option name
 418  *
 419  * Description:
 420  * Returns true if @level and @optname refer to a NetLabel option.
 421  * Helper for selinux_netlbl_socket_setsockopt().
 422  */
 423 static inline int selinux_netlbl_option(int level, int optname)
 424 {
 425         return (level == IPPROTO_IP && optname == IP_OPTIONS) ||
 426                 (level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS);
 427 }
 428
 429 /**
 430  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 431  * @sock: the socket
 432  * @level: the socket level or protocol
 433  * @optname: the socket option name
 434  *
 435  * Description:
 436  * Check the setsockopt() call and if the user is trying to replace the IP
 437  * options on a socket and a NetLabel is in place for the socket deny the
 438  * access; otherwise allow the access.  Returns zero when the access is
 439  * allowed, -EACCES when denied, and other negative values on error.
 440  *
 441  */
 442 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 443                                      int level,
 444                                      int optname)
 445 {
 446         int rc = 0;
 447         struct sock *sk = sock->sk;
 448         struct sk_security_struct *sksec = sk->sk_security;
 449         struct netlbl_lsm_secattr secattr;
 450
 451         if (selinux_netlbl_option(level, optname) &&
 452             (sksec->nlbl_state == NLBL_LABELED ||
 453              sksec->nlbl_state == NLBL_CONNLABELED)) {
 454                 netlbl_secattr_init(&secattr);
 455                 lock_sock(sk);
 456                 /* call the netlabel function directly as we want to see the
 457                  * on-the-wire label that is assigned via the socket's options
 458                  * and not the cached netlabel/lsm attributes */
 459                 rc = netlbl_sock_getattr(sk, &secattr);
 460                 release_sock(sk);
 461                 if (rc == 0)
 462                         rc = -EACCES;
 463                 else if (rc == -ENOMSG)
 464                         rc = 0;
 465                 netlbl_secattr_destroy(&secattr);
 466         }
 467
 468         return rc;
 469 }
 470
 471 /**
 472  * selinux_netlbl_socket_connect - Label a client-side socket on connect
 473  * @sk: the socket to label
 474  * @addr: the destination address
 475  *
 476  * Description:
 477  * Attempt to label a connected socket with NetLabel using the given address.
 478  * Returns zero values on success, negative values on failure.
 479  *
 480  */
 481 int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
 482 {
 483         int rc;
 484         struct sk_security_struct *sksec = sk->sk_security;
 485         struct netlbl_lsm_secattr *secattr;
 486
 487         if (sksec->nlbl_state != NLBL_REQSKB &&
 488             sksec->nlbl_state != NLBL_CONNLABELED)
 489                 return 0;
 490
 491         lock_sock(sk);
 492
 493         /* connected sockets are allowed to disconnect when the address family
 494          * is set to AF_UNSPEC, if that is what is happening we want to reset
 495          * the socket */
 496         if (addr->sa_family == AF_UNSPEC) {
 497                 netlbl_sock_delattr(sk);
 498                 sksec->nlbl_state = NLBL_REQSKB;
 499                 rc = 0;
 500                 goto socket_connect_return;
 501         }
 502         secattr = selinux_netlbl_sock_genattr(sk);
 503         if (secattr == NULL) {
 504                 rc = -ENOMEM;
 505                 goto socket_connect_return;
 506         }
 507         rc = netlbl_conn_setattr(sk, addr, secattr);
 508         if (rc == 0)
 509                 sksec->nlbl_state = NLBL_CONNLABELED;
 510
 511 socket_connect_return:
 512         release_sock(sk);
 513         return rc;
 514 }