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_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 */
112static 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 */
136void 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 */
154void 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 */
167void 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 */
183void 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 */
201int 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 */
237int 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->sk;
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
265skbuff_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 */
282int 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);
295inet_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 */
310void 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 */
330int 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 */
369int 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 */
425int 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 */
464int 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
494socket_connect_return:
495	release_sock(sk);
496	return rc;
497}
498