security/selinux/netlabel.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /*
   3  * SELinux NetLabel Support
   4  *
   5  * This file provides the necessary glue to tie NetLabel into the SELinux
   6  * subsystem.
   7  *
   8  * Author: Paul Moore <paul@paul-moore.com>
   9  */
  10
  11 /*
  12  * (c) Copyright Hewlett-Packard Development Company, L.P., 2007, 2008
  13  */
  14
  15 #include <linux/spinlock.h>
  16 #include <linux/rcupdate.h>
  17 #include <linux/gfp.h>
  18 #include <linux/ip.h>
  19 #include <linux/ipv6.h>
  20 #include <net/sock.h>
  21 #include <net/netlabel.h>
  22 #include <net/ip.h>
  23 #include <net/ipv6.h>
  24
  25 #include "objsec.h"
  26 #include "security.h"
  27 #include "netlabel.h"
  28
  29 /**
  30  * selinux_netlbl_sidlookup_cached - Cache a SID lookup
  31  * @skb: the packet
  32  * @secattr: the NetLabel security attributes
  33  * @sid: the SID
  34  *
  35  * Description:
  36  * Query the SELinux security server to lookup the correct SID for the given
  37  * security attributes.  If the query is successful, cache the result to speed
  38  * up future lookups.  Returns zero on success, negative values on failure.
  39  *
  40  */
  41 static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb,
  42                                            u16 family,
  43                                            struct netlbl_lsm_secattr *secattr,
  44                                            u32 *sid)
  45 {
  46         int rc;
  47
  48         rc = security_netlbl_secattr_to_sid(&selinux_state, secattr, sid);
  49         if (rc == 0 &&
  50             (secattr->flags & NETLBL_SECATTR_CACHEABLE) &&
  51             (secattr->flags & NETLBL_SECATTR_CACHE))
  52                 netlbl_cache_add(skb, family, secattr);
  53
  54         return rc;
  55 }
  56
  57 /**
  58  * selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr
  59  * @sk: the socket
  60  *
  61  * Description:
  62  * Generate the NetLabel security attributes for a socket, making full use of
  63  * the socket's attribute cache.  Returns a pointer to the security attributes
  64  * on success, NULL on failure.
  65  *
  66  */
  67 static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk)
  68 {
  69         int rc;
  70         struct sk_security_struct *sksec = sk->sk_security;
  71         struct netlbl_lsm_secattr *secattr;
  72
  73         if (sksec->nlbl_secattr != NULL)
  74                 return sksec->nlbl_secattr;
  75
  76         secattr = netlbl_secattr_alloc(GFP_ATOMIC);
  77         if (secattr == NULL)
  78                 return NULL;
  79         rc = security_netlbl_sid_to_secattr(&selinux_state, sksec->sid,
  80                                             secattr);
  81         if (rc != 0) {
  82                 netlbl_secattr_free(secattr);
  83                 return NULL;
  84         }
  85         sksec->nlbl_secattr = secattr;
  86
  87         return secattr;
  88 }
  89
  90 /**
  91  * selinux_netlbl_sock_getattr - Get the cached NetLabel secattr
  92  * @sk: the socket
  93  * @sid: the SID
  94  *
  95  * Query the socket's cached secattr and if the SID matches the cached value
  96  * return the cache, otherwise return NULL.
  97  *
  98  */
  99 static struct netlbl_lsm_secattr *selinux_netlbl_sock_getattr(
 100                                                         const struct sock *sk,
 101                                                         u32 sid)
 102 {
 103         struct sk_security_struct *sksec = sk->sk_security;
 104         struct netlbl_lsm_secattr *secattr = sksec->nlbl_secattr;
 105
 106         if (secattr == NULL)
 107                 return NULL;
 108
 109         if ((secattr->flags & NETLBL_SECATTR_SECID) &&
 110             (secattr->attr.secid == sid))
 111                 return secattr;
 112
 113         return NULL;
 114 }
 115
 116 /**
 117  * selinux_netlbl_cache_invalidate - Invalidate the NetLabel cache
 118  *
 119  * Description:
 120  * Invalidate the NetLabel security attribute mapping cache.
 121  *
 122  */
 123 void selinux_netlbl_cache_invalidate(void)
 124 {
 125         netlbl_cache_invalidate();
 126 }
 127
 128 /**
 129  * selinux_netlbl_err - Handle a NetLabel packet error
 130  * @skb: the packet
 131  * @error: the error code
 132  * @gateway: true if host is acting as a gateway, false otherwise
 133  *
 134  * Description:
 135  * When a packet is dropped due to a call to avc_has_perm() pass the error
 136  * code to the NetLabel subsystem so any protocol specific processing can be
 137  * done.  This is safe to call even if you are unsure if NetLabel labeling is
 138  * present on the packet, NetLabel is smart enough to only act when it should.
 139  *
 140  */
 141 void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error, int gateway)
 142 {
 143         netlbl_skbuff_err(skb, family, error, gateway);
 144 }
 145
 146 /**
 147  * selinux_netlbl_sk_security_free - Free the NetLabel fields
 148  * @sksec: the sk_security_struct
 149  *
 150  * Description:
 151  * Free all of the memory in the NetLabel fields of a sk_security_struct.
 152  *
 153  */
 154 void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec)
 155 {
 156         if (sksec->nlbl_secattr != NULL)
 157                 netlbl_secattr_free(sksec->nlbl_secattr);
 158 }
 159
 160 /**
 161  * selinux_netlbl_sk_security_reset - Reset the NetLabel fields
 162  * @sksec: the sk_security_struct
 163  * @family: the socket family
 164  *
 165  * Description:
 166  * Called when the NetLabel state of a sk_security_struct needs to be reset.
 167  * The caller is responsible for all the NetLabel sk_security_struct locking.
 168  *
 169  */
 170 void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec)
 171 {
 172         sksec->nlbl_state = NLBL_UNSET;
 173 }
 174
 175 /**
 176  * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel
 177  * @skb: the packet
 178  * @family: protocol family
 179  * @type: NetLabel labeling protocol type
 180  * @sid: the SID
 181  *
 182  * Description:
 183  * Call the NetLabel mechanism to get the security attributes of the given
 184  * packet and use those attributes to determine the correct context/SID to
 185  * assign to the packet.  Returns zero on success, negative values on failure.
 186  *
 187  */
 188 int selinux_netlbl_skbuff_getsid(struct sk_buff *skb,
 189                                  u16 family,
 190                                  u32 *type,
 191                                  u32 *sid)
 192 {
 193         int rc;
 194         struct netlbl_lsm_secattr secattr;
 195
 196         if (!netlbl_enabled()) {
 197                 *sid = SECSID_NULL;
 198                 return 0;
 199         }
 200
 201         netlbl_secattr_init(&secattr);
 202         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 203         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 204                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 205                                                      &secattr, sid);
 206         else
 207                 *sid = SECSID_NULL;
 208         *type = secattr.type;
 209         netlbl_secattr_destroy(&secattr);
 210
 211         return rc;
 212 }
 213
 214 /**
 215  * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid
 216  * @skb: the packet
 217  * @family: protocol family
 218  * @sid: the SID
 219  *
 220  * Description
 221  * Call the NetLabel mechanism to set the label of a packet using @sid.
 222  * Returns zero on success, negative values on failure.
 223  *
 224  */
 225 int selinux_netlbl_skbuff_setsid(struct sk_buff *skb,
 226                                  u16 family,
 227                                  u32 sid)
 228 {
 229         int rc;
 230         struct netlbl_lsm_secattr secattr_storage;
 231         struct netlbl_lsm_secattr *secattr = NULL;
 232         struct sock *sk;
 233
 234         /* if this is a locally generated packet check to see if it is already
 235          * being labeled by it's parent socket, if it is just exit */
 236         sk = skb_to_full_sk(skb);
 237         if (sk != NULL) {
 238                 struct sk_security_struct *sksec = sk->sk_security;
 239
 240                 if (sksec->nlbl_state != NLBL_REQSKB)
 241                         return 0;
 242                 secattr = selinux_netlbl_sock_getattr(sk, sid);
 243         }
 244         if (secattr == NULL) {
 245                 secattr = &secattr_storage;
 246                 netlbl_secattr_init(secattr);
 247                 rc = security_netlbl_sid_to_secattr(&selinux_state, sid,
 248                                                     secattr);
 249                 if (rc != 0)
 250                         goto skbuff_setsid_return;
 251         }
 252
 253         rc = netlbl_skbuff_setattr(skb, family, secattr);
 254
 255 skbuff_setsid_return:
 256         if (secattr == &secattr_storage)
 257                 netlbl_secattr_destroy(secattr);
 258         return rc;
 259 }
 260
 261 /**
 262  * selinux_netlbl_sctp_assoc_request - Label an incoming sctp association.
 263  * @ep: incoming association endpoint.
 264  * @skb: the packet.
 265  *
 266  * Description:
 267  * A new incoming connection is represented by @ep, ......
 268  * Returns zero on success, negative values on failure.
 269  *
 270  */
 271 int selinux_netlbl_sctp_assoc_request(struct sctp_endpoint *ep,
 272                                      struct sk_buff *skb)
 273 {
 274         int rc;
 275         struct netlbl_lsm_secattr secattr;
 276         struct sk_security_struct *sksec = ep->base.sk->sk_security;
 277         struct sockaddr_in addr4;
 278         struct sockaddr_in6 addr6;
 279
 280         if (ep->base.sk->sk_family != PF_INET &&
 281                                 ep->base.sk->sk_family != PF_INET6)
 282                 return 0;
 283
 284         netlbl_secattr_init(&secattr);
 285         rc = security_netlbl_sid_to_secattr(&selinux_state,
 286                                             ep->secid, &secattr);
 287         if (rc != 0)
 288                 goto assoc_request_return;
 289
 290         /* Move skb hdr address info to a struct sockaddr and then call
 291          * netlbl_conn_setattr().
 292          */
 293         if (ip_hdr(skb)->version == 4) {
 294                 addr4.sin_family = AF_INET;
 295                 addr4.sin_addr.s_addr = ip_hdr(skb)->saddr;
 296                 rc = netlbl_conn_setattr(ep->base.sk, (void *)&addr4, &secattr);
 297         } else if (IS_ENABLED(CONFIG_IPV6) && ip_hdr(skb)->version == 6) {
 298                 addr6.sin6_family = AF_INET6;
 299                 addr6.sin6_addr = ipv6_hdr(skb)->saddr;
 300                 rc = netlbl_conn_setattr(ep->base.sk, (void *)&addr6, &secattr);
 301         } else {
 302                 rc = -EAFNOSUPPORT;
 303         }
 304
 305         if (rc == 0)
 306                 sksec->nlbl_state = NLBL_LABELED;
 307
 308 assoc_request_return:
 309         netlbl_secattr_destroy(&secattr);
 310         return rc;
 311 }
 312
 313 /**
 314  * selinux_netlbl_inet_conn_request - Label an incoming stream connection
 315  * @req: incoming connection request socket
 316  *
 317  * Description:
 318  * A new incoming connection request is represented by @req, we need to label
 319  * the new request_sock here and the stack will ensure the on-the-wire label
 320  * will get preserved when a full sock is created once the connection handshake
 321  * is complete.  Returns zero on success, negative values on failure.
 322  *
 323  */
 324 int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family)
 325 {
 326         int rc;
 327         struct netlbl_lsm_secattr secattr;
 328
 329         if (family != PF_INET && family != PF_INET6)
 330                 return 0;
 331
 332         netlbl_secattr_init(&secattr);
 333         rc = security_netlbl_sid_to_secattr(&selinux_state, req->secid,
 334                                             &secattr);
 335         if (rc != 0)
 336                 goto inet_conn_request_return;
 337         rc = netlbl_req_setattr(req, &secattr);
 338 inet_conn_request_return:
 339         netlbl_secattr_destroy(&secattr);
 340         return rc;
 341 }
 342
 343 /**
 344  * selinux_netlbl_inet_csk_clone - Initialize the newly created sock
 345  * @sk: the new sock
 346  *
 347  * Description:
 348  * A new connection has been established using @sk, we've already labeled the
 349  * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but
 350  * we need to set the NetLabel state here since we now have a sock structure.
 351  *
 352  */
 353 void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family)
 354 {
 355         struct sk_security_struct *sksec = sk->sk_security;
 356
 357         if (family == PF_INET)
 358                 sksec->nlbl_state = NLBL_LABELED;
 359         else
 360                 sksec->nlbl_state = NLBL_UNSET;
 361 }
 362
 363 /**
 364  * selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock
 365  * @sk: current sock
 366  * @newsk: the new sock
 367  *
 368  * Description:
 369  * Called whenever a new socket is created by accept(2) or sctp_peeloff(3).
 370  */
 371 void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk)
 372 {
 373         struct sk_security_struct *sksec = sk->sk_security;
 374         struct sk_security_struct *newsksec = newsk->sk_security;
 375
 376         newsksec->nlbl_state = sksec->nlbl_state;
 377 }
 378
 379 /**
 380  * selinux_netlbl_socket_post_create - Label a socket using NetLabel
 381  * @sock: the socket to label
 382  * @family: protocol family
 383  *
 384  * Description:
 385  * Attempt to label a socket using the NetLabel mechanism using the given
 386  * SID.  Returns zero values on success, negative values on failure.
 387  *
 388  */
 389 int selinux_netlbl_socket_post_create(struct sock *sk, u16 family)
 390 {
 391         int rc;
 392         struct sk_security_struct *sksec = sk->sk_security;
 393         struct netlbl_lsm_secattr *secattr;
 394
 395         if (family != PF_INET && family != PF_INET6)
 396                 return 0;
 397
 398         secattr = selinux_netlbl_sock_genattr(sk);
 399         if (secattr == NULL)
 400                 return -ENOMEM;
 401         rc = netlbl_sock_setattr(sk, family, secattr);
 402         switch (rc) {
 403         case 0:
 404                 sksec->nlbl_state = NLBL_LABELED;
 405                 break;
 406         case -EDESTADDRREQ:
 407                 sksec->nlbl_state = NLBL_REQSKB;
 408                 rc = 0;
 409                 break;
 410         }
 411
 412         return rc;
 413 }
 414
 415 /**
 416  * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel
 417  * @sksec: the sock's sk_security_struct
 418  * @skb: the packet
 419  * @family: protocol family
 420  * @ad: the audit data
 421  *
 422  * Description:
 423  * Fetch the NetLabel security attributes from @skb and perform an access check
 424  * against the receiving socket.  Returns zero on success, negative values on
 425  * error.
 426  *
 427  */
 428 int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec,
 429                                 struct sk_buff *skb,
 430                                 u16 family,
 431                                 struct common_audit_data *ad)
 432 {
 433         int rc;
 434         u32 nlbl_sid;
 435         u32 perm;
 436         struct netlbl_lsm_secattr secattr;
 437
 438         if (!netlbl_enabled())
 439                 return 0;
 440
 441         netlbl_secattr_init(&secattr);
 442         rc = netlbl_skbuff_getattr(skb, family, &secattr);
 443         if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE)
 444                 rc = selinux_netlbl_sidlookup_cached(skb, family,
 445                                                      &secattr, &nlbl_sid);
 446         else
 447                 nlbl_sid = SECINITSID_UNLABELED;
 448         netlbl_secattr_destroy(&secattr);
 449         if (rc != 0)
 450                 return rc;
 451
 452         switch (sksec->sclass) {
 453         case SECCLASS_UDP_SOCKET:
 454                 perm = UDP_SOCKET__RECVFROM;
 455                 break;
 456         case SECCLASS_TCP_SOCKET:
 457                 perm = TCP_SOCKET__RECVFROM;
 458                 break;
 459         default:
 460                 perm = RAWIP_SOCKET__RECVFROM;
 461         }
 462
 463         rc = avc_has_perm(&selinux_state,
 464                           sksec->sid, nlbl_sid, sksec->sclass, perm, ad);
 465         if (rc == 0)
 466                 return 0;
 467
 468         if (nlbl_sid != SECINITSID_UNLABELED)
 469                 netlbl_skbuff_err(skb, family, rc, 0);
 470         return rc;
 471 }
 472
 473 /**
 474  * selinux_netlbl_option - Is this a NetLabel option
 475  * @level: the socket level or protocol
 476  * @optname: the socket option name
 477  *
 478  * Description:
 479  * Returns true if @level and @optname refer to a NetLabel option.
 480  * Helper for selinux_netlbl_socket_setsockopt().
 481  */
 482 static inline int selinux_netlbl_option(int level, int optname)
 483 {
 484         return (level == IPPROTO_IP && optname == IP_OPTIONS) ||
 485                 (level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS);
 486 }
 487
 488 /**
 489  * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel
 490  * @sock: the socket
 491  * @level: the socket level or protocol
 492  * @optname: the socket option name
 493  *
 494  * Description:
 495  * Check the setsockopt() call and if the user is trying to replace the IP
 496  * options on a socket and a NetLabel is in place for the socket deny the
 497  * access; otherwise allow the access.  Returns zero when the access is
 498  * allowed, -EACCES when denied, and other negative values on error.
 499  *
 500  */
 501 int selinux_netlbl_socket_setsockopt(struct socket *sock,
 502                                      int level,
 503                                      int optname)
 504 {
 505         int rc = 0;
 506         struct sock *sk = sock->sk;
 507         struct sk_security_struct *sksec = sk->sk_security;
 508         struct netlbl_lsm_secattr secattr;
 509
 510         if (selinux_netlbl_option(level, optname) &&
 511             (sksec->nlbl_state == NLBL_LABELED ||
 512              sksec->nlbl_state == NLBL_CONNLABELED)) {
 513                 netlbl_secattr_init(&secattr);
 514                 lock_sock(sk);
 515                 /* call the netlabel function directly as we want to see the
 516                  * on-the-wire label that is assigned via the socket's options
 517                  * and not the cached netlabel/lsm attributes */
 518                 rc = netlbl_sock_getattr(sk, &secattr);
 519                 release_sock(sk);
 520                 if (rc == 0)
 521                         rc = -EACCES;
 522                 else if (rc == -ENOMSG)
 523                         rc = 0;
 524                 netlbl_secattr_destroy(&secattr);
 525         }
 526
 527         return rc;
 528 }
 529
 530 /**
 531  * selinux_netlbl_socket_connect_helper - Help label a client-side socket on
 532  * connect
 533  * @sk: the socket to label
 534  * @addr: the destination address
 535  *
 536  * Description:
 537  * Attempt to label a connected socket with NetLabel using the given address.
 538  * Returns zero values on success, negative values on failure.
 539  *
 540  */
 541 static int selinux_netlbl_socket_connect_helper(struct sock *sk,
 542                                                 struct sockaddr *addr)
 543 {
 544         int rc;
 545         struct sk_security_struct *sksec = sk->sk_security;
 546         struct netlbl_lsm_secattr *secattr;
 547
 548         /* connected sockets are allowed to disconnect when the address family
 549          * is set to AF_UNSPEC, if that is what is happening we want to reset
 550          * the socket */
 551         if (addr->sa_family == AF_UNSPEC) {
 552                 netlbl_sock_delattr(sk);
 553                 sksec->nlbl_state = NLBL_REQSKB;
 554                 rc = 0;
 555                 return rc;
 556         }
 557         secattr = selinux_netlbl_sock_genattr(sk);
 558         if (secattr == NULL) {
 559                 rc = -ENOMEM;
 560                 return rc;
 561         }
 562         rc = netlbl_conn_setattr(sk, addr, secattr);
 563         if (rc == 0)
 564                 sksec->nlbl_state = NLBL_CONNLABELED;
 565
 566         return rc;
 567 }
 568
 569 /**
 570  * selinux_netlbl_socket_connect_locked - Label a client-side socket on
 571  * connect
 572  * @sk: the socket to label
 573  * @addr: the destination address
 574  *
 575  * Description:
 576  * Attempt to label a connected socket that already has the socket locked
 577  * with NetLabel using the given address.
 578  * Returns zero values on success, negative values on failure.
 579  *
 580  */
 581 int selinux_netlbl_socket_connect_locked(struct sock *sk,
 582                                          struct sockaddr *addr)
 583 {
 584         struct sk_security_struct *sksec = sk->sk_security;
 585
 586         if (sksec->nlbl_state != NLBL_REQSKB &&
 587             sksec->nlbl_state != NLBL_CONNLABELED)
 588                 return 0;
 589
 590         return selinux_netlbl_socket_connect_helper(sk, addr);
 591 }
 592
 593 /**
 594  * selinux_netlbl_socket_connect - Label a client-side socket on connect
 595  * @sk: the socket to label
 596  * @addr: the destination address
 597  *
 598  * Description:
 599  * Attempt to label a connected socket with NetLabel using the given address.
 600  * Returns zero values on success, negative values on failure.
 601  *
 602  */
 603 int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr)
 604 {
 605         int rc;
 606
 607         lock_sock(sk);
 608         rc = selinux_netlbl_socket_connect_locked(sk, addr);
 609         release_sock(sk);
 610
 611         return rc;
 612 }