linux/security/selinux/netlabel.c
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   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 */
  56static 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 */
  81static 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 */
 110void 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 */
 128void 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 */
 141void 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 */
 157void 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 */
 175int 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 */
 211int 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
 239skbuff_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 */
 256int 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);
 269inet_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 */
 284void 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 */
 304int 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 */
 343int 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 */
 399int 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 */
 435int 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        local_bh_disable();
 446        bh_lock_sock_nested(sk);
 447
 448        /* connected sockets are allowed to disconnect when the address family
 449         * is set to AF_UNSPEC, if that is what is happening we want to reset
 450         * the socket */
 451        if (addr->sa_family == AF_UNSPEC) {
 452                netlbl_sock_delattr(sk);
 453                sksec->nlbl_state = NLBL_REQSKB;
 454                rc = 0;
 455                goto socket_connect_return;
 456        }
 457        secattr = selinux_netlbl_sock_genattr(sk);
 458        if (secattr == NULL) {
 459                rc = -ENOMEM;
 460                goto socket_connect_return;
 461        }
 462        rc = netlbl_conn_setattr(sk, addr, secattr);
 463        if (rc == 0)
 464                sksec->nlbl_state = NLBL_CONNLABELED;
 465
 466socket_connect_return:
 467        bh_unlock_sock(sk);
 468        local_bh_enable();
 469        return rc;
 470}
 471
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