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

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