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 | * @family: the packet's address family |
33 | * @secattr: the NetLabel security attributes |
34 | * @sid: the SID |
35 | * |
36 | * Description: |
37 | * Query the SELinux security server to lookup the correct SID for the given |
38 | * security attributes. If the query is successful, cache the result to speed |
39 | * up future lookups. Returns zero on success, negative values on failure. |
40 | * |
41 | */ |
42 | static int selinux_netlbl_sidlookup_cached(struct sk_buff *skb, |
43 | u16 family, |
44 | struct netlbl_lsm_secattr *secattr, |
45 | u32 *sid) |
46 | { |
47 | int rc; |
48 | |
49 | rc = security_netlbl_secattr_to_sid(secattr, sid); |
50 | if (rc == 0 && |
51 | (secattr->flags & NETLBL_SECATTR_CACHEABLE) && |
52 | (secattr->flags & NETLBL_SECATTR_CACHE)) |
53 | netlbl_cache_add(skb, family, secattr); |
54 | |
55 | return rc; |
56 | } |
57 | |
58 | /** |
59 | * selinux_netlbl_sock_genattr - Generate the NetLabel socket secattr |
60 | * @sk: the socket |
61 | * |
62 | * Description: |
63 | * Generate the NetLabel security attributes for a socket, making full use of |
64 | * the socket's attribute cache. Returns a pointer to the security attributes |
65 | * on success, NULL on failure. |
66 | * |
67 | */ |
68 | static struct netlbl_lsm_secattr *selinux_netlbl_sock_genattr(struct sock *sk) |
69 | { |
70 | int rc; |
71 | struct sk_security_struct *sksec = sk->sk_security; |
72 | struct netlbl_lsm_secattr *secattr; |
73 | |
74 | if (sksec->nlbl_secattr != NULL) |
75 | return sksec->nlbl_secattr; |
76 | |
77 | secattr = netlbl_secattr_alloc(GFP_ATOMIC); |
78 | if (secattr == NULL) |
79 | return NULL; |
80 | rc = security_netlbl_sid_to_secattr(sksec->sid, 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 | * @family: the packet's address family |
132 | * @error: the error code |
133 | * @gateway: true if host is acting as a gateway, false otherwise |
134 | * |
135 | * Description: |
136 | * When a packet is dropped due to a call to avc_has_perm() pass the error |
137 | * code to the NetLabel subsystem so any protocol specific processing can be |
138 | * done. This is safe to call even if you are unsure if NetLabel labeling is |
139 | * present on the packet, NetLabel is smart enough to only act when it should. |
140 | * |
141 | */ |
142 | void selinux_netlbl_err(struct sk_buff *skb, u16 family, int error, int gateway) |
143 | { |
144 | netlbl_skbuff_err(skb, family, error, gateway); |
145 | } |
146 | |
147 | /** |
148 | * selinux_netlbl_sk_security_free - Free the NetLabel fields |
149 | * @sksec: the sk_security_struct |
150 | * |
151 | * Description: |
152 | * Free all of the memory in the NetLabel fields of a sk_security_struct. |
153 | * |
154 | */ |
155 | void selinux_netlbl_sk_security_free(struct sk_security_struct *sksec) |
156 | { |
157 | if (!sksec->nlbl_secattr) |
158 | return; |
159 | |
160 | netlbl_secattr_free(secattr: sksec->nlbl_secattr); |
161 | sksec->nlbl_secattr = NULL; |
162 | sksec->nlbl_state = NLBL_UNSET; |
163 | } |
164 | |
165 | /** |
166 | * selinux_netlbl_sk_security_reset - Reset the NetLabel fields |
167 | * @sksec: the sk_security_struct |
168 | * |
169 | * Description: |
170 | * Called when the NetLabel state of a sk_security_struct needs to be reset. |
171 | * The caller is responsible for all the NetLabel sk_security_struct locking. |
172 | * |
173 | */ |
174 | void selinux_netlbl_sk_security_reset(struct sk_security_struct *sksec) |
175 | { |
176 | sksec->nlbl_state = NLBL_UNSET; |
177 | } |
178 | |
179 | /** |
180 | * selinux_netlbl_skbuff_getsid - Get the sid of a packet using NetLabel |
181 | * @skb: the packet |
182 | * @family: protocol family |
183 | * @type: NetLabel labeling protocol type |
184 | * @sid: the SID |
185 | * |
186 | * Description: |
187 | * Call the NetLabel mechanism to get the security attributes of the given |
188 | * packet and use those attributes to determine the correct context/SID to |
189 | * assign to the packet. Returns zero on success, negative values on failure. |
190 | * |
191 | */ |
192 | int selinux_netlbl_skbuff_getsid(struct sk_buff *skb, |
193 | u16 family, |
194 | u32 *type, |
195 | u32 *sid) |
196 | { |
197 | int rc; |
198 | struct netlbl_lsm_secattr secattr; |
199 | |
200 | if (!netlbl_enabled()) { |
201 | *type = NETLBL_NLTYPE_NONE; |
202 | *sid = SECSID_NULL; |
203 | return 0; |
204 | } |
205 | |
206 | netlbl_secattr_init(secattr: &secattr); |
207 | rc = netlbl_skbuff_getattr(skb, family, secattr: &secattr); |
208 | if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE) |
209 | rc = selinux_netlbl_sidlookup_cached(skb, family, |
210 | secattr: &secattr, sid); |
211 | else |
212 | *sid = SECSID_NULL; |
213 | *type = secattr.type; |
214 | netlbl_secattr_destroy(secattr: &secattr); |
215 | |
216 | return rc; |
217 | } |
218 | |
219 | /** |
220 | * selinux_netlbl_skbuff_setsid - Set the NetLabel on a packet given a sid |
221 | * @skb: the packet |
222 | * @family: protocol family |
223 | * @sid: the SID |
224 | * |
225 | * Description |
226 | * Call the NetLabel mechanism to set the label of a packet using @sid. |
227 | * Returns zero on success, negative values on failure. |
228 | * |
229 | */ |
230 | int selinux_netlbl_skbuff_setsid(struct sk_buff *skb, |
231 | u16 family, |
232 | u32 sid) |
233 | { |
234 | int rc; |
235 | struct netlbl_lsm_secattr secattr_storage; |
236 | struct netlbl_lsm_secattr *secattr = NULL; |
237 | struct sock *sk; |
238 | |
239 | /* if this is a locally generated packet check to see if it is already |
240 | * being labeled by it's parent socket, if it is just exit */ |
241 | sk = skb_to_full_sk(skb); |
242 | if (sk != NULL) { |
243 | struct sk_security_struct *sksec = sk->sk_security; |
244 | |
245 | if (sksec->nlbl_state != NLBL_REQSKB) |
246 | return 0; |
247 | secattr = selinux_netlbl_sock_getattr(sk, sid); |
248 | } |
249 | if (secattr == NULL) { |
250 | secattr = &secattr_storage; |
251 | netlbl_secattr_init(secattr); |
252 | rc = security_netlbl_sid_to_secattr(sid, secattr); |
253 | if (rc != 0) |
254 | goto skbuff_setsid_return; |
255 | } |
256 | |
257 | rc = netlbl_skbuff_setattr(skb, family, secattr); |
258 | |
259 | skbuff_setsid_return: |
260 | if (secattr == &secattr_storage) |
261 | netlbl_secattr_destroy(secattr); |
262 | return rc; |
263 | } |
264 | |
265 | /** |
266 | * selinux_netlbl_sctp_assoc_request - Label an incoming sctp association. |
267 | * @asoc: incoming association. |
268 | * @skb: the packet. |
269 | * |
270 | * Description: |
271 | * A new incoming connection is represented by @asoc, ...... |
272 | * Returns zero on success, negative values on failure. |
273 | * |
274 | */ |
275 | int selinux_netlbl_sctp_assoc_request(struct sctp_association *asoc, |
276 | struct sk_buff *skb) |
277 | { |
278 | int rc; |
279 | struct netlbl_lsm_secattr secattr; |
280 | struct sk_security_struct *sksec = asoc->base.sk->sk_security; |
281 | struct sockaddr_in addr4; |
282 | struct sockaddr_in6 addr6; |
283 | |
284 | if (asoc->base.sk->sk_family != PF_INET && |
285 | asoc->base.sk->sk_family != PF_INET6) |
286 | return 0; |
287 | |
288 | netlbl_secattr_init(secattr: &secattr); |
289 | rc = security_netlbl_sid_to_secattr(asoc->secid, &secattr); |
290 | if (rc != 0) |
291 | goto assoc_request_return; |
292 | |
293 | /* Move skb hdr address info to a struct sockaddr and then call |
294 | * netlbl_conn_setattr(). |
295 | */ |
296 | if (ip_hdr(skb)->version == 4) { |
297 | addr4.sin_family = AF_INET; |
298 | addr4.sin_addr.s_addr = ip_hdr(skb)->saddr; |
299 | rc = netlbl_conn_setattr(sk: asoc->base.sk, addr: (void *)&addr4, secattr: &secattr); |
300 | } else if (IS_ENABLED(CONFIG_IPV6) && ip_hdr(skb)->version == 6) { |
301 | addr6.sin6_family = AF_INET6; |
302 | addr6.sin6_addr = ipv6_hdr(skb)->saddr; |
303 | rc = netlbl_conn_setattr(sk: asoc->base.sk, addr: (void *)&addr6, secattr: &secattr); |
304 | } else { |
305 | rc = -EAFNOSUPPORT; |
306 | } |
307 | |
308 | if (rc == 0) |
309 | sksec->nlbl_state = NLBL_LABELED; |
310 | |
311 | assoc_request_return: |
312 | netlbl_secattr_destroy(secattr: &secattr); |
313 | return rc; |
314 | } |
315 | |
316 | /** |
317 | * selinux_netlbl_inet_conn_request - Label an incoming stream connection |
318 | * @req: incoming connection request socket |
319 | * @family: the request socket's address family |
320 | * |
321 | * Description: |
322 | * A new incoming connection request is represented by @req, we need to label |
323 | * the new request_sock here and the stack will ensure the on-the-wire label |
324 | * will get preserved when a full sock is created once the connection handshake |
325 | * is complete. Returns zero on success, negative values on failure. |
326 | * |
327 | */ |
328 | int selinux_netlbl_inet_conn_request(struct request_sock *req, u16 family) |
329 | { |
330 | int rc; |
331 | struct netlbl_lsm_secattr secattr; |
332 | |
333 | if (family != PF_INET && family != PF_INET6) |
334 | return 0; |
335 | |
336 | netlbl_secattr_init(secattr: &secattr); |
337 | rc = security_netlbl_sid_to_secattr(req->secid, &secattr); |
338 | if (rc != 0) |
339 | goto inet_conn_request_return; |
340 | rc = netlbl_req_setattr(req, secattr: &secattr); |
341 | inet_conn_request_return: |
342 | netlbl_secattr_destroy(secattr: &secattr); |
343 | return rc; |
344 | } |
345 | |
346 | /** |
347 | * selinux_netlbl_inet_csk_clone - Initialize the newly created sock |
348 | * @sk: the new sock |
349 | * @family: the sock's address family |
350 | * |
351 | * Description: |
352 | * A new connection has been established using @sk, we've already labeled the |
353 | * socket via the request_sock struct in selinux_netlbl_inet_conn_request() but |
354 | * we need to set the NetLabel state here since we now have a sock structure. |
355 | * |
356 | */ |
357 | void selinux_netlbl_inet_csk_clone(struct sock *sk, u16 family) |
358 | { |
359 | struct sk_security_struct *sksec = sk->sk_security; |
360 | |
361 | if (family == PF_INET) |
362 | sksec->nlbl_state = NLBL_LABELED; |
363 | else |
364 | sksec->nlbl_state = NLBL_UNSET; |
365 | } |
366 | |
367 | /** |
368 | * selinux_netlbl_sctp_sk_clone - Copy state to the newly created sock |
369 | * @sk: current sock |
370 | * @newsk: the new sock |
371 | * |
372 | * Description: |
373 | * Called whenever a new socket is created by accept(2) or sctp_peeloff(3). |
374 | */ |
375 | void selinux_netlbl_sctp_sk_clone(struct sock *sk, struct sock *newsk) |
376 | { |
377 | struct sk_security_struct *sksec = sk->sk_security; |
378 | struct sk_security_struct *newsksec = newsk->sk_security; |
379 | |
380 | newsksec->nlbl_state = sksec->nlbl_state; |
381 | } |
382 | |
383 | /** |
384 | * selinux_netlbl_socket_post_create - Label a socket using NetLabel |
385 | * @sk: the sock to label |
386 | * @family: protocol family |
387 | * |
388 | * Description: |
389 | * Attempt to label a socket using the NetLabel mechanism using the given |
390 | * SID. Returns zero values on success, negative values on failure. |
391 | * |
392 | */ |
393 | int selinux_netlbl_socket_post_create(struct sock *sk, u16 family) |
394 | { |
395 | int rc; |
396 | struct sk_security_struct *sksec = sk->sk_security; |
397 | struct netlbl_lsm_secattr *secattr; |
398 | |
399 | if (family != PF_INET && family != PF_INET6) |
400 | return 0; |
401 | |
402 | secattr = selinux_netlbl_sock_genattr(sk); |
403 | if (secattr == NULL) |
404 | return -ENOMEM; |
405 | rc = netlbl_sock_setattr(sk, family, secattr); |
406 | switch (rc) { |
407 | case 0: |
408 | sksec->nlbl_state = NLBL_LABELED; |
409 | break; |
410 | case -EDESTADDRREQ: |
411 | sksec->nlbl_state = NLBL_REQSKB; |
412 | rc = 0; |
413 | break; |
414 | } |
415 | |
416 | return rc; |
417 | } |
418 | |
419 | /** |
420 | * selinux_netlbl_sock_rcv_skb - Do an inbound access check using NetLabel |
421 | * @sksec: the sock's sk_security_struct |
422 | * @skb: the packet |
423 | * @family: protocol family |
424 | * @ad: the audit data |
425 | * |
426 | * Description: |
427 | * Fetch the NetLabel security attributes from @skb and perform an access check |
428 | * against the receiving socket. Returns zero on success, negative values on |
429 | * error. |
430 | * |
431 | */ |
432 | int selinux_netlbl_sock_rcv_skb(struct sk_security_struct *sksec, |
433 | struct sk_buff *skb, |
434 | u16 family, |
435 | struct common_audit_data *ad) |
436 | { |
437 | int rc; |
438 | u32 nlbl_sid; |
439 | u32 perm; |
440 | struct netlbl_lsm_secattr secattr; |
441 | |
442 | if (!netlbl_enabled()) |
443 | return 0; |
444 | |
445 | netlbl_secattr_init(secattr: &secattr); |
446 | rc = netlbl_skbuff_getattr(skb, family, secattr: &secattr); |
447 | if (rc == 0 && secattr.flags != NETLBL_SECATTR_NONE) |
448 | rc = selinux_netlbl_sidlookup_cached(skb, family, |
449 | secattr: &secattr, sid: &nlbl_sid); |
450 | else |
451 | nlbl_sid = SECINITSID_UNLABELED; |
452 | netlbl_secattr_destroy(secattr: &secattr); |
453 | if (rc != 0) |
454 | return rc; |
455 | |
456 | switch (sksec->sclass) { |
457 | case SECCLASS_UDP_SOCKET: |
458 | perm = UDP_SOCKET__RECVFROM; |
459 | break; |
460 | case SECCLASS_TCP_SOCKET: |
461 | perm = TCP_SOCKET__RECVFROM; |
462 | break; |
463 | default: |
464 | perm = RAWIP_SOCKET__RECVFROM; |
465 | } |
466 | |
467 | rc = avc_has_perm(sksec->sid, nlbl_sid, sksec->sclass, perm, ad); |
468 | if (rc == 0) |
469 | return 0; |
470 | |
471 | if (nlbl_sid != SECINITSID_UNLABELED) |
472 | netlbl_skbuff_err(skb, family, error: rc, gateway: 0); |
473 | return rc; |
474 | } |
475 | |
476 | /** |
477 | * selinux_netlbl_option - Is this a NetLabel option |
478 | * @level: the socket level or protocol |
479 | * @optname: the socket option name |
480 | * |
481 | * Description: |
482 | * Returns true if @level and @optname refer to a NetLabel option. |
483 | * Helper for selinux_netlbl_socket_setsockopt(). |
484 | */ |
485 | static inline int selinux_netlbl_option(int level, int optname) |
486 | { |
487 | return (level == IPPROTO_IP && optname == IP_OPTIONS) || |
488 | (level == IPPROTO_IPV6 && optname == IPV6_HOPOPTS); |
489 | } |
490 | |
491 | /** |
492 | * selinux_netlbl_socket_setsockopt - Do not allow users to remove a NetLabel |
493 | * @sock: the socket |
494 | * @level: the socket level or protocol |
495 | * @optname: the socket option name |
496 | * |
497 | * Description: |
498 | * Check the setsockopt() call and if the user is trying to replace the IP |
499 | * options on a socket and a NetLabel is in place for the socket deny the |
500 | * access; otherwise allow the access. Returns zero when the access is |
501 | * allowed, -EACCES when denied, and other negative values on error. |
502 | * |
503 | */ |
504 | int selinux_netlbl_socket_setsockopt(struct socket *sock, |
505 | int level, |
506 | int optname) |
507 | { |
508 | int rc = 0; |
509 | struct sock *sk = sock->sk; |
510 | struct sk_security_struct *sksec = sk->sk_security; |
511 | struct netlbl_lsm_secattr secattr; |
512 | |
513 | if (selinux_netlbl_option(level, optname) && |
514 | (sksec->nlbl_state == NLBL_LABELED || |
515 | sksec->nlbl_state == NLBL_CONNLABELED)) { |
516 | netlbl_secattr_init(secattr: &secattr); |
517 | lock_sock(sk); |
518 | /* call the netlabel function directly as we want to see the |
519 | * on-the-wire label that is assigned via the socket's options |
520 | * and not the cached netlabel/lsm attributes */ |
521 | rc = netlbl_sock_getattr(sk, secattr: &secattr); |
522 | release_sock(sk); |
523 | if (rc == 0) |
524 | rc = -EACCES; |
525 | else if (rc == -ENOMSG) |
526 | rc = 0; |
527 | netlbl_secattr_destroy(secattr: &secattr); |
528 | } |
529 | |
530 | return rc; |
531 | } |
532 | |
533 | /** |
534 | * selinux_netlbl_socket_connect_helper - Help label a client-side socket on |
535 | * connect |
536 | * @sk: the socket to label |
537 | * @addr: the destination address |
538 | * |
539 | * Description: |
540 | * Attempt to label a connected socket with NetLabel using the given address. |
541 | * Returns zero values on success, negative values on failure. |
542 | * |
543 | */ |
544 | static int selinux_netlbl_socket_connect_helper(struct sock *sk, |
545 | struct sockaddr *addr) |
546 | { |
547 | int rc; |
548 | struct sk_security_struct *sksec = sk->sk_security; |
549 | struct netlbl_lsm_secattr *secattr; |
550 | |
551 | /* connected sockets are allowed to disconnect when the address family |
552 | * is set to AF_UNSPEC, if that is what is happening we want to reset |
553 | * the socket */ |
554 | if (addr->sa_family == AF_UNSPEC) { |
555 | netlbl_sock_delattr(sk); |
556 | sksec->nlbl_state = NLBL_REQSKB; |
557 | rc = 0; |
558 | return rc; |
559 | } |
560 | secattr = selinux_netlbl_sock_genattr(sk); |
561 | if (secattr == NULL) { |
562 | rc = -ENOMEM; |
563 | return rc; |
564 | } |
565 | rc = netlbl_conn_setattr(sk, addr, secattr); |
566 | if (rc == 0) |
567 | sksec->nlbl_state = NLBL_CONNLABELED; |
568 | |
569 | return rc; |
570 | } |
571 | |
572 | /** |
573 | * selinux_netlbl_socket_connect_locked - Label a client-side socket on |
574 | * connect |
575 | * @sk: the socket to label |
576 | * @addr: the destination address |
577 | * |
578 | * Description: |
579 | * Attempt to label a connected socket that already has the socket locked |
580 | * with NetLabel using the given address. |
581 | * Returns zero values on success, negative values on failure. |
582 | * |
583 | */ |
584 | int selinux_netlbl_socket_connect_locked(struct sock *sk, |
585 | struct sockaddr *addr) |
586 | { |
587 | struct sk_security_struct *sksec = sk->sk_security; |
588 | |
589 | if (sksec->nlbl_state != NLBL_REQSKB && |
590 | sksec->nlbl_state != NLBL_CONNLABELED) |
591 | return 0; |
592 | |
593 | return selinux_netlbl_socket_connect_helper(sk, addr); |
594 | } |
595 | |
596 | /** |
597 | * selinux_netlbl_socket_connect - Label a client-side socket on connect |
598 | * @sk: the socket to label |
599 | * @addr: the destination address |
600 | * |
601 | * Description: |
602 | * Attempt to label a connected socket with NetLabel using the given address. |
603 | * Returns zero values on success, negative values on failure. |
604 | * |
605 | */ |
606 | int selinux_netlbl_socket_connect(struct sock *sk, struct sockaddr *addr) |
607 | { |
608 | int rc; |
609 | |
610 | lock_sock(sk); |
611 | rc = selinux_netlbl_socket_connect_locked(sk, addr); |
612 | release_sock(sk); |
613 | |
614 | return rc; |
615 | } |
616 | |