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 */
selinux_netlbl_sidlookup_cached(struct sk_buff * skb,struct netlbl_lsm_secattr * secattr,u32 * sid)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 */
selinux_netlbl_sock_genattr(struct sock * sk)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 */
selinux_netlbl_sock_getattr(const struct sock * sk,u32 sid)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 */
selinux_netlbl_cache_invalidate(void)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 */
selinux_netlbl_err(struct sk_buff * skb,int error,int gateway)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 */
selinux_netlbl_sk_security_free(struct sk_security_struct * sksec)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 */
selinux_netlbl_sk_security_reset(struct sk_security_struct * sksec)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 */
selinux_netlbl_skbuff_getsid(struct sk_buff * skb,u16 family,u32 * type,u32 * sid)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 */
selinux_netlbl_skbuff_setsid(struct sk_buff * skb,u16 family,u32 sid)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 */
selinux_netlbl_inet_conn_request(struct request_sock * req,u16 family)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 */
selinux_netlbl_inet_csk_clone(struct sock * sk,u16 family)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 */
selinux_netlbl_socket_post_create(struct sock * sk,u16 family)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 */
selinux_netlbl_sock_rcv_skb(struct sk_security_struct * sksec,struct sk_buff * skb,u16 family,struct common_audit_data * ad)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 */
selinux_netlbl_socket_setsockopt(struct socket * sock,int level,int optname)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 */
selinux_netlbl_socket_connect(struct sock * sk,struct sockaddr * addr)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