Commit | Line | Data |
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d28d1e08 TJ |
1 | /* |
2 | * NSA Security-Enhanced Linux (SELinux) security module | |
3 | * | |
4 | * This file contains the SELinux XFRM hook function implementations. | |
5 | * | |
6 | * Authors: Serge Hallyn <sergeh@us.ibm.com> | |
7 | * Trent Jaeger <jaegert@us.ibm.com> | |
8 | * | |
e0d1caa7 VY |
9 | * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com> |
10 | * | |
11 | * Granular IPSec Associations for use in MLS environments. | |
12 | * | |
d28d1e08 | 13 | * Copyright (C) 2005 International Business Machines Corporation |
e0d1caa7 | 14 | * Copyright (C) 2006 Trusted Computer Solutions, Inc. |
d28d1e08 TJ |
15 | * |
16 | * This program is free software; you can redistribute it and/or modify | |
17 | * it under the terms of the GNU General Public License version 2, | |
18 | * as published by the Free Software Foundation. | |
19 | */ | |
20 | ||
21 | /* | |
22 | * USAGE: | |
23 | * NOTES: | |
24 | * 1. Make sure to enable the following options in your kernel config: | |
25 | * CONFIG_SECURITY=y | |
26 | * CONFIG_SECURITY_NETWORK=y | |
27 | * CONFIG_SECURITY_NETWORK_XFRM=y | |
28 | * CONFIG_SECURITY_SELINUX=m/y | |
29 | * ISSUES: | |
30 | * 1. Caching packets, so they are not dropped during negotiation | |
31 | * 2. Emulating a reasonable SO_PEERSEC across machines | |
32 | * 3. Testing addition of sk_policy's with security context via setsockopt | |
33 | */ | |
d28d1e08 TJ |
34 | #include <linux/module.h> |
35 | #include <linux/kernel.h> | |
36 | #include <linux/init.h> | |
37 | #include <linux/security.h> | |
38 | #include <linux/types.h> | |
39 | #include <linux/netfilter.h> | |
40 | #include <linux/netfilter_ipv4.h> | |
41 | #include <linux/netfilter_ipv6.h> | |
42 | #include <linux/ip.h> | |
43 | #include <linux/tcp.h> | |
44 | #include <linux/skbuff.h> | |
45 | #include <linux/xfrm.h> | |
46 | #include <net/xfrm.h> | |
47 | #include <net/checksum.h> | |
48 | #include <net/udp.h> | |
49 | #include <asm/semaphore.h> | |
50 | ||
51 | #include "avc.h" | |
52 | #include "objsec.h" | |
53 | #include "xfrm.h" | |
54 | ||
55 | ||
56 | /* | |
57 | * Returns true if an LSM/SELinux context | |
58 | */ | |
59 | static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx) | |
60 | { | |
61 | return (ctx && | |
62 | (ctx->ctx_doi == XFRM_SC_DOI_LSM) && | |
63 | (ctx->ctx_alg == XFRM_SC_ALG_SELINUX)); | |
64 | } | |
65 | ||
66 | /* | |
67 | * Returns true if the xfrm contains a security blob for SELinux | |
68 | */ | |
69 | static inline int selinux_authorizable_xfrm(struct xfrm_state *x) | |
70 | { | |
71 | return selinux_authorizable_ctx(x->security); | |
72 | } | |
73 | ||
74 | /* | |
e0d1caa7 VY |
75 | * LSM hook implementation that authorizes that a flow can use |
76 | * a xfrm policy rule. | |
d28d1e08 | 77 | */ |
e0d1caa7 | 78 | int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir) |
d28d1e08 | 79 | { |
5b368e61 VY |
80 | int rc; |
81 | u32 sel_sid; | |
d28d1e08 TJ |
82 | struct xfrm_sec_ctx *ctx; |
83 | ||
84 | /* Context sid is either set to label or ANY_ASSOC */ | |
85 | if ((ctx = xp->security)) { | |
86 | if (!selinux_authorizable_ctx(ctx)) | |
87 | return -EINVAL; | |
88 | ||
89 | sel_sid = ctx->ctx_sid; | |
90 | } | |
5b368e61 VY |
91 | else |
92 | /* | |
93 | * All flows should be treated as polmatch'ing an | |
94 | * otherwise applicable "non-labeled" policy. This | |
95 | * would prevent inadvertent "leaks". | |
96 | */ | |
97 | return 0; | |
d28d1e08 | 98 | |
e0d1caa7 VY |
99 | rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, |
100 | ASSOCIATION__POLMATCH, | |
d28d1e08 TJ |
101 | NULL); |
102 | ||
5b368e61 VY |
103 | if (rc == -EACCES) |
104 | rc = -ESRCH; | |
105 | ||
d28d1e08 TJ |
106 | return rc; |
107 | } | |
108 | ||
e0d1caa7 VY |
109 | /* |
110 | * LSM hook implementation that authorizes that a state matches | |
111 | * the given policy, flow combo. | |
112 | */ | |
113 | ||
114 | int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp, | |
115 | struct flowi *fl) | |
116 | { | |
117 | u32 state_sid; | |
118 | u32 pol_sid; | |
119 | int err; | |
120 | ||
5b368e61 VY |
121 | if (xp->security) { |
122 | if (!x->security) | |
123 | /* unlabeled SA and labeled policy can't match */ | |
124 | return 0; | |
125 | else | |
126 | state_sid = x->security->ctx_sid; | |
e0d1caa7 | 127 | pol_sid = xp->security->ctx_sid; |
5b368e61 VY |
128 | } else |
129 | if (x->security) | |
130 | /* unlabeled policy and labeled SA can't match */ | |
131 | return 0; | |
132 | else | |
133 | /* unlabeled policy and unlabeled SA match all flows */ | |
134 | return 1; | |
e0d1caa7 VY |
135 | |
136 | err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION, | |
137 | ASSOCIATION__POLMATCH, | |
138 | NULL); | |
139 | ||
140 | if (err) | |
141 | return 0; | |
142 | ||
5b368e61 VY |
143 | err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION, |
144 | ASSOCIATION__SENDTO, | |
145 | NULL)? 0:1; | |
146 | ||
147 | return err; | |
e0d1caa7 VY |
148 | } |
149 | ||
150 | /* | |
151 | * LSM hook implementation that authorizes that a particular outgoing flow | |
152 | * can use a given security association. | |
153 | */ | |
154 | ||
5b368e61 VY |
155 | int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm, |
156 | struct xfrm_policy *xp) | |
e0d1caa7 VY |
157 | { |
158 | int rc = 0; | |
159 | u32 sel_sid = SECINITSID_UNLABELED; | |
160 | struct xfrm_sec_ctx *ctx; | |
161 | ||
5b368e61 VY |
162 | if (!xp->security) |
163 | if (!xfrm->security) | |
164 | return 1; | |
165 | else | |
166 | return 0; | |
167 | else | |
168 | if (!xfrm->security) | |
169 | return 0; | |
170 | ||
e0d1caa7 VY |
171 | /* Context sid is either set to label or ANY_ASSOC */ |
172 | if ((ctx = xfrm->security)) { | |
173 | if (!selinux_authorizable_ctx(ctx)) | |
174 | return 0; | |
175 | ||
176 | sel_sid = ctx->ctx_sid; | |
177 | } | |
178 | ||
179 | rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION, | |
180 | ASSOCIATION__SENDTO, | |
181 | NULL)? 0:1; | |
182 | ||
183 | return rc; | |
184 | } | |
185 | ||
186 | /* | |
187 | * LSM hook implementation that determines the sid for the session. | |
188 | */ | |
189 | ||
beb8d13b | 190 | int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) |
e0d1caa7 VY |
191 | { |
192 | struct sec_path *sp; | |
193 | ||
beb8d13b | 194 | *sid = SECSID_NULL; |
e0d1caa7 VY |
195 | |
196 | if (skb == NULL) | |
197 | return 0; | |
198 | ||
199 | sp = skb->sp; | |
200 | if (sp) { | |
201 | int i, sid_set = 0; | |
202 | ||
203 | for (i = sp->len-1; i >= 0; i--) { | |
204 | struct xfrm_state *x = sp->xvec[i]; | |
205 | if (selinux_authorizable_xfrm(x)) { | |
206 | struct xfrm_sec_ctx *ctx = x->security; | |
207 | ||
208 | if (!sid_set) { | |
beb8d13b | 209 | *sid = ctx->ctx_sid; |
e0d1caa7 | 210 | sid_set = 1; |
beb8d13b VY |
211 | |
212 | if (!ckall) | |
213 | break; | |
e0d1caa7 | 214 | } |
beb8d13b | 215 | else if (*sid != ctx->ctx_sid) |
e0d1caa7 VY |
216 | return -EINVAL; |
217 | } | |
218 | } | |
219 | } | |
220 | ||
221 | return 0; | |
222 | } | |
223 | ||
d28d1e08 TJ |
224 | /* |
225 | * Security blob allocation for xfrm_policy and xfrm_state | |
226 | * CTX does not have a meaningful value on input | |
227 | */ | |
e0d1caa7 | 228 | static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, |
c1a856c9 | 229 | struct xfrm_user_sec_ctx *uctx, u32 sid) |
d28d1e08 TJ |
230 | { |
231 | int rc = 0; | |
232 | struct task_security_struct *tsec = current->security; | |
e0d1caa7 VY |
233 | struct xfrm_sec_ctx *ctx = NULL; |
234 | char *ctx_str = NULL; | |
235 | u32 str_len; | |
e0d1caa7 | 236 | |
c1a856c9 | 237 | BUG_ON(uctx && sid); |
e0d1caa7 | 238 | |
cb969f07 VY |
239 | if (!uctx) |
240 | goto not_from_user; | |
e0d1caa7 VY |
241 | |
242 | if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) | |
243 | return -EINVAL; | |
d28d1e08 TJ |
244 | |
245 | if (uctx->ctx_len >= PAGE_SIZE) | |
246 | return -ENOMEM; | |
247 | ||
248 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
249 | uctx->ctx_len, | |
250 | GFP_KERNEL); | |
251 | ||
252 | if (!ctx) | |
253 | return -ENOMEM; | |
254 | ||
255 | ctx->ctx_doi = uctx->ctx_doi; | |
256 | ctx->ctx_len = uctx->ctx_len; | |
257 | ctx->ctx_alg = uctx->ctx_alg; | |
258 | ||
259 | memcpy(ctx->ctx_str, | |
260 | uctx+1, | |
261 | ctx->ctx_len); | |
262 | rc = security_context_to_sid(ctx->ctx_str, | |
263 | ctx->ctx_len, | |
264 | &ctx->ctx_sid); | |
265 | ||
266 | if (rc) | |
267 | goto out; | |
268 | ||
269 | /* | |
c8c05a8e | 270 | * Does the subject have permission to set security context? |
d28d1e08 | 271 | */ |
d28d1e08 TJ |
272 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
273 | SECCLASS_ASSOCIATION, | |
5f8ac64b | 274 | ASSOCIATION__SETCONTEXT, NULL); |
d28d1e08 TJ |
275 | if (rc) |
276 | goto out; | |
277 | ||
278 | return rc; | |
279 | ||
cb969f07 | 280 | not_from_user: |
c1a856c9 | 281 | rc = security_sid_to_context(sid, &ctx_str, &str_len); |
e0d1caa7 VY |
282 | if (rc) |
283 | goto out; | |
284 | ||
285 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
286 | str_len, | |
287 | GFP_ATOMIC); | |
288 | ||
289 | if (!ctx) { | |
290 | rc = -ENOMEM; | |
291 | goto out; | |
292 | } | |
293 | ||
e0d1caa7 VY |
294 | ctx->ctx_doi = XFRM_SC_DOI_LSM; |
295 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
c1a856c9 | 296 | ctx->ctx_sid = sid; |
e0d1caa7 VY |
297 | ctx->ctx_len = str_len; |
298 | memcpy(ctx->ctx_str, | |
299 | ctx_str, | |
300 | str_len); | |
301 | ||
302 | goto out2; | |
303 | ||
d28d1e08 | 304 | out: |
ee2e6841 | 305 | *ctxp = NULL; |
d28d1e08 | 306 | kfree(ctx); |
e0d1caa7 VY |
307 | out2: |
308 | kfree(ctx_str); | |
d28d1e08 TJ |
309 | return rc; |
310 | } | |
311 | ||
312 | /* | |
313 | * LSM hook implementation that allocs and transfers uctx spec to | |
314 | * xfrm_policy. | |
315 | */ | |
cb969f07 | 316 | int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, |
c1a856c9 | 317 | struct xfrm_user_sec_ctx *uctx) |
d28d1e08 TJ |
318 | { |
319 | int err; | |
320 | ||
321 | BUG_ON(!xp); | |
c1a856c9 | 322 | BUG_ON(!uctx); |
d28d1e08 | 323 | |
c1a856c9 | 324 | err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0); |
d28d1e08 TJ |
325 | return err; |
326 | } | |
327 | ||
328 | ||
329 | /* | |
330 | * LSM hook implementation that copies security data structure from old to | |
331 | * new for policy cloning. | |
332 | */ | |
333 | int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new) | |
334 | { | |
335 | struct xfrm_sec_ctx *old_ctx, *new_ctx; | |
336 | ||
337 | old_ctx = old->security; | |
338 | ||
339 | if (old_ctx) { | |
340 | new_ctx = new->security = kmalloc(sizeof(*new_ctx) + | |
341 | old_ctx->ctx_len, | |
342 | GFP_KERNEL); | |
343 | ||
344 | if (!new_ctx) | |
345 | return -ENOMEM; | |
346 | ||
347 | memcpy(new_ctx, old_ctx, sizeof(*new_ctx)); | |
348 | memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len); | |
349 | } | |
350 | return 0; | |
351 | } | |
352 | ||
353 | /* | |
354 | * LSM hook implementation that frees xfrm_policy security information. | |
355 | */ | |
356 | void selinux_xfrm_policy_free(struct xfrm_policy *xp) | |
357 | { | |
358 | struct xfrm_sec_ctx *ctx = xp->security; | |
359 | if (ctx) | |
360 | kfree(ctx); | |
361 | } | |
362 | ||
c8c05a8e CZ |
363 | /* |
364 | * LSM hook implementation that authorizes deletion of labeled policies. | |
365 | */ | |
366 | int selinux_xfrm_policy_delete(struct xfrm_policy *xp) | |
367 | { | |
368 | struct task_security_struct *tsec = current->security; | |
369 | struct xfrm_sec_ctx *ctx = xp->security; | |
370 | int rc = 0; | |
371 | ||
372 | if (ctx) | |
373 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
374 | SECCLASS_ASSOCIATION, | |
375 | ASSOCIATION__SETCONTEXT, NULL); | |
376 | ||
377 | return rc; | |
378 | } | |
379 | ||
d28d1e08 TJ |
380 | /* |
381 | * LSM hook implementation that allocs and transfers sec_ctx spec to | |
382 | * xfrm_state. | |
383 | */ | |
e0d1caa7 | 384 | int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx, |
c1a856c9 | 385 | u32 secid) |
d28d1e08 TJ |
386 | { |
387 | int err; | |
388 | ||
389 | BUG_ON(!x); | |
390 | ||
c1a856c9 | 391 | err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid); |
d28d1e08 TJ |
392 | return err; |
393 | } | |
394 | ||
395 | /* | |
396 | * LSM hook implementation that frees xfrm_state security information. | |
397 | */ | |
398 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
399 | { | |
400 | struct xfrm_sec_ctx *ctx = x->security; | |
401 | if (ctx) | |
402 | kfree(ctx); | |
403 | } | |
404 | ||
2c7946a7 CZ |
405 | /* |
406 | * SELinux internal function to retrieve the context of a connected | |
407 | * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security | |
408 | * association used to connect to the remote socket. | |
409 | * | |
410 | * Retrieve via getsockopt SO_PEERSEC. | |
411 | */ | |
412 | u32 selinux_socket_getpeer_stream(struct sock *sk) | |
413 | { | |
414 | struct dst_entry *dst, *dst_test; | |
415 | u32 peer_sid = SECSID_NULL; | |
416 | ||
417 | if (sk->sk_state != TCP_ESTABLISHED) | |
418 | goto out; | |
419 | ||
420 | dst = sk_dst_get(sk); | |
421 | if (!dst) | |
422 | goto out; | |
423 | ||
424 | for (dst_test = dst; dst_test != 0; | |
425 | dst_test = dst_test->child) { | |
426 | struct xfrm_state *x = dst_test->xfrm; | |
427 | ||
428 | if (x && selinux_authorizable_xfrm(x)) { | |
429 | struct xfrm_sec_ctx *ctx = x->security; | |
430 | peer_sid = ctx->ctx_sid; | |
431 | break; | |
432 | } | |
433 | } | |
434 | dst_release(dst); | |
435 | ||
436 | out: | |
437 | return peer_sid; | |
438 | } | |
439 | ||
440 | /* | |
441 | * SELinux internal function to retrieve the context of a UDP packet | |
442 | * based on its security association used to connect to the remote socket. | |
443 | * | |
444 | * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message | |
445 | * type SCM_SECURITY. | |
446 | */ | |
447 | u32 selinux_socket_getpeer_dgram(struct sk_buff *skb) | |
448 | { | |
449 | struct sec_path *sp; | |
450 | ||
451 | if (skb == NULL) | |
452 | return SECSID_NULL; | |
453 | ||
454 | if (skb->sk->sk_protocol != IPPROTO_UDP) | |
455 | return SECSID_NULL; | |
456 | ||
457 | sp = skb->sp; | |
458 | if (sp) { | |
459 | int i; | |
460 | ||
461 | for (i = sp->len-1; i >= 0; i--) { | |
67644726 | 462 | struct xfrm_state *x = sp->xvec[i]; |
2c7946a7 CZ |
463 | if (selinux_authorizable_xfrm(x)) { |
464 | struct xfrm_sec_ctx *ctx = x->security; | |
465 | return ctx->ctx_sid; | |
466 | } | |
467 | } | |
468 | } | |
469 | ||
470 | return SECSID_NULL; | |
471 | } | |
472 | ||
c8c05a8e CZ |
473 | /* |
474 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
475 | */ | |
476 | int selinux_xfrm_state_delete(struct xfrm_state *x) | |
477 | { | |
478 | struct task_security_struct *tsec = current->security; | |
479 | struct xfrm_sec_ctx *ctx = x->security; | |
480 | int rc = 0; | |
481 | ||
482 | if (ctx) | |
483 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
484 | SECCLASS_ASSOCIATION, | |
485 | ASSOCIATION__SETCONTEXT, NULL); | |
486 | ||
487 | return rc; | |
488 | } | |
489 | ||
d28d1e08 TJ |
490 | /* |
491 | * LSM hook that controls access to unlabelled packets. If | |
492 | * a xfrm_state is authorizable (defined by macro) then it was | |
493 | * already authorized by the IPSec process. If not, then | |
494 | * we need to check for unlabelled access since this may not have | |
495 | * gone thru the IPSec process. | |
496 | */ | |
e0d1caa7 VY |
497 | int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, |
498 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
499 | { |
500 | int i, rc = 0; | |
501 | struct sec_path *sp; | |
e0d1caa7 | 502 | u32 sel_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
503 | |
504 | sp = skb->sp; | |
505 | ||
506 | if (sp) { | |
d28d1e08 | 507 | for (i = 0; i < sp->len; i++) { |
67644726 | 508 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 509 | |
e0d1caa7 VY |
510 | if (x && selinux_authorizable_xfrm(x)) { |
511 | struct xfrm_sec_ctx *ctx = x->security; | |
512 | sel_sid = ctx->ctx_sid; | |
513 | break; | |
514 | } | |
d28d1e08 TJ |
515 | } |
516 | } | |
517 | ||
e0d1caa7 VY |
518 | rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, |
519 | ASSOCIATION__RECVFROM, ad); | |
d28d1e08 | 520 | |
d28d1e08 TJ |
521 | return rc; |
522 | } | |
523 | ||
524 | /* | |
525 | * POSTROUTE_LAST hook's XFRM processing: | |
526 | * If we have no security association, then we need to determine | |
527 | * whether the socket is allowed to send to an unlabelled destination. | |
528 | * If we do have a authorizable security association, then it has already been | |
529 | * checked in xfrm_policy_lookup hook. | |
530 | */ | |
e0d1caa7 VY |
531 | int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, |
532 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
533 | { |
534 | struct dst_entry *dst; | |
535 | int rc = 0; | |
536 | ||
537 | dst = skb->dst; | |
538 | ||
539 | if (dst) { | |
540 | struct dst_entry *dst_test; | |
541 | ||
542 | for (dst_test = dst; dst_test != 0; | |
543 | dst_test = dst_test->child) { | |
544 | struct xfrm_state *x = dst_test->xfrm; | |
545 | ||
546 | if (x && selinux_authorizable_xfrm(x)) | |
4e5ab4cb | 547 | goto out; |
d28d1e08 TJ |
548 | } |
549 | } | |
550 | ||
551 | rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, | |
e0d1caa7 | 552 | ASSOCIATION__SENDTO, ad); |
4e5ab4cb JM |
553 | out: |
554 | return rc; | |
d28d1e08 | 555 | } |