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