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TOMOYO Linux Cross Reference
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  */
 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 }
516 

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