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 VY |
228 | static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, |
229 | struct xfrm_user_sec_ctx *uctx, struct xfrm_sec_ctx *pol, 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; | |
236 | u32 ctx_sid; | |
237 | ||
238 | BUG_ON(uctx && pol); | |
239 | ||
cb969f07 VY |
240 | if (!uctx) |
241 | goto not_from_user; | |
e0d1caa7 VY |
242 | |
243 | if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) | |
244 | return -EINVAL; | |
d28d1e08 TJ |
245 | |
246 | if (uctx->ctx_len >= PAGE_SIZE) | |
247 | return -ENOMEM; | |
248 | ||
249 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
250 | uctx->ctx_len, | |
251 | GFP_KERNEL); | |
252 | ||
253 | if (!ctx) | |
254 | return -ENOMEM; | |
255 | ||
256 | ctx->ctx_doi = uctx->ctx_doi; | |
257 | ctx->ctx_len = uctx->ctx_len; | |
258 | ctx->ctx_alg = uctx->ctx_alg; | |
259 | ||
260 | memcpy(ctx->ctx_str, | |
261 | uctx+1, | |
262 | ctx->ctx_len); | |
263 | rc = security_context_to_sid(ctx->ctx_str, | |
264 | ctx->ctx_len, | |
265 | &ctx->ctx_sid); | |
266 | ||
267 | if (rc) | |
268 | goto out; | |
269 | ||
270 | /* | |
c8c05a8e | 271 | * Does the subject have permission to set security context? |
d28d1e08 | 272 | */ |
d28d1e08 TJ |
273 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
274 | SECCLASS_ASSOCIATION, | |
5f8ac64b | 275 | ASSOCIATION__SETCONTEXT, NULL); |
d28d1e08 TJ |
276 | if (rc) |
277 | goto out; | |
278 | ||
279 | return rc; | |
280 | ||
cb969f07 VY |
281 | not_from_user: |
282 | if (pol) { | |
283 | rc = security_sid_mls_copy(pol->ctx_sid, sid, &ctx_sid); | |
284 | if (rc) | |
285 | goto out; | |
286 | } | |
287 | else | |
288 | ctx_sid = sid; | |
e0d1caa7 VY |
289 | |
290 | rc = security_sid_to_context(ctx_sid, &ctx_str, &str_len); | |
291 | if (rc) | |
292 | goto out; | |
293 | ||
294 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
295 | str_len, | |
296 | GFP_ATOMIC); | |
297 | ||
298 | if (!ctx) { | |
299 | rc = -ENOMEM; | |
300 | goto out; | |
301 | } | |
302 | ||
e0d1caa7 VY |
303 | ctx->ctx_doi = XFRM_SC_DOI_LSM; |
304 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
305 | ctx->ctx_sid = ctx_sid; | |
306 | ctx->ctx_len = str_len; | |
307 | memcpy(ctx->ctx_str, | |
308 | ctx_str, | |
309 | str_len); | |
310 | ||
311 | goto out2; | |
312 | ||
d28d1e08 | 313 | out: |
ee2e6841 | 314 | *ctxp = NULL; |
d28d1e08 | 315 | kfree(ctx); |
e0d1caa7 VY |
316 | out2: |
317 | kfree(ctx_str); | |
d28d1e08 TJ |
318 | return rc; |
319 | } | |
320 | ||
321 | /* | |
322 | * LSM hook implementation that allocs and transfers uctx spec to | |
323 | * xfrm_policy. | |
324 | */ | |
cb969f07 VY |
325 | int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, |
326 | struct xfrm_user_sec_ctx *uctx, struct sock *sk) | |
d28d1e08 TJ |
327 | { |
328 | int err; | |
cb969f07 | 329 | u32 sid; |
d28d1e08 TJ |
330 | |
331 | BUG_ON(!xp); | |
cb969f07 VY |
332 | BUG_ON(uctx && sk); |
333 | ||
334 | if (sk) { | |
335 | struct sk_security_struct *ssec = sk->sk_security; | |
336 | sid = ssec->sid; | |
337 | } | |
338 | else | |
339 | sid = SECSID_NULL; | |
d28d1e08 | 340 | |
cb969f07 | 341 | err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, NULL, sid); |
d28d1e08 TJ |
342 | return err; |
343 | } | |
344 | ||
345 | ||
346 | /* | |
347 | * LSM hook implementation that copies security data structure from old to | |
348 | * new for policy cloning. | |
349 | */ | |
350 | int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new) | |
351 | { | |
352 | struct xfrm_sec_ctx *old_ctx, *new_ctx; | |
353 | ||
354 | old_ctx = old->security; | |
355 | ||
356 | if (old_ctx) { | |
357 | new_ctx = new->security = kmalloc(sizeof(*new_ctx) + | |
358 | old_ctx->ctx_len, | |
359 | GFP_KERNEL); | |
360 | ||
361 | if (!new_ctx) | |
362 | return -ENOMEM; | |
363 | ||
364 | memcpy(new_ctx, old_ctx, sizeof(*new_ctx)); | |
365 | memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len); | |
366 | } | |
367 | return 0; | |
368 | } | |
369 | ||
370 | /* | |
371 | * LSM hook implementation that frees xfrm_policy security information. | |
372 | */ | |
373 | void selinux_xfrm_policy_free(struct xfrm_policy *xp) | |
374 | { | |
375 | struct xfrm_sec_ctx *ctx = xp->security; | |
376 | if (ctx) | |
377 | kfree(ctx); | |
378 | } | |
379 | ||
c8c05a8e CZ |
380 | /* |
381 | * LSM hook implementation that authorizes deletion of labeled policies. | |
382 | */ | |
383 | int selinux_xfrm_policy_delete(struct xfrm_policy *xp) | |
384 | { | |
385 | struct task_security_struct *tsec = current->security; | |
386 | struct xfrm_sec_ctx *ctx = xp->security; | |
387 | int rc = 0; | |
388 | ||
389 | if (ctx) | |
390 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
391 | SECCLASS_ASSOCIATION, | |
392 | ASSOCIATION__SETCONTEXT, NULL); | |
393 | ||
394 | return rc; | |
395 | } | |
396 | ||
d28d1e08 TJ |
397 | /* |
398 | * LSM hook implementation that allocs and transfers sec_ctx spec to | |
399 | * xfrm_state. | |
400 | */ | |
e0d1caa7 VY |
401 | int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx, |
402 | struct xfrm_sec_ctx *pol, u32 secid) | |
d28d1e08 TJ |
403 | { |
404 | int err; | |
405 | ||
406 | BUG_ON(!x); | |
407 | ||
e0d1caa7 | 408 | err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, pol, secid); |
d28d1e08 TJ |
409 | return err; |
410 | } | |
411 | ||
412 | /* | |
413 | * LSM hook implementation that frees xfrm_state security information. | |
414 | */ | |
415 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
416 | { | |
417 | struct xfrm_sec_ctx *ctx = x->security; | |
418 | if (ctx) | |
419 | kfree(ctx); | |
420 | } | |
421 | ||
2c7946a7 CZ |
422 | /* |
423 | * SELinux internal function to retrieve the context of a connected | |
424 | * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security | |
425 | * association used to connect to the remote socket. | |
426 | * | |
427 | * Retrieve via getsockopt SO_PEERSEC. | |
428 | */ | |
429 | u32 selinux_socket_getpeer_stream(struct sock *sk) | |
430 | { | |
431 | struct dst_entry *dst, *dst_test; | |
432 | u32 peer_sid = SECSID_NULL; | |
433 | ||
434 | if (sk->sk_state != TCP_ESTABLISHED) | |
435 | goto out; | |
436 | ||
437 | dst = sk_dst_get(sk); | |
438 | if (!dst) | |
439 | goto out; | |
440 | ||
441 | for (dst_test = dst; dst_test != 0; | |
442 | dst_test = dst_test->child) { | |
443 | struct xfrm_state *x = dst_test->xfrm; | |
444 | ||
445 | if (x && selinux_authorizable_xfrm(x)) { | |
446 | struct xfrm_sec_ctx *ctx = x->security; | |
447 | peer_sid = ctx->ctx_sid; | |
448 | break; | |
449 | } | |
450 | } | |
451 | dst_release(dst); | |
452 | ||
453 | out: | |
454 | return peer_sid; | |
455 | } | |
456 | ||
457 | /* | |
458 | * SELinux internal function to retrieve the context of a UDP packet | |
459 | * based on its security association used to connect to the remote socket. | |
460 | * | |
461 | * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message | |
462 | * type SCM_SECURITY. | |
463 | */ | |
464 | u32 selinux_socket_getpeer_dgram(struct sk_buff *skb) | |
465 | { | |
466 | struct sec_path *sp; | |
467 | ||
468 | if (skb == NULL) | |
469 | return SECSID_NULL; | |
470 | ||
471 | if (skb->sk->sk_protocol != IPPROTO_UDP) | |
472 | return SECSID_NULL; | |
473 | ||
474 | sp = skb->sp; | |
475 | if (sp) { | |
476 | int i; | |
477 | ||
478 | for (i = sp->len-1; i >= 0; i--) { | |
67644726 | 479 | struct xfrm_state *x = sp->xvec[i]; |
2c7946a7 CZ |
480 | if (selinux_authorizable_xfrm(x)) { |
481 | struct xfrm_sec_ctx *ctx = x->security; | |
482 | return ctx->ctx_sid; | |
483 | } | |
484 | } | |
485 | } | |
486 | ||
487 | return SECSID_NULL; | |
488 | } | |
489 | ||
c8c05a8e CZ |
490 | /* |
491 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
492 | */ | |
493 | int selinux_xfrm_state_delete(struct xfrm_state *x) | |
494 | { | |
495 | struct task_security_struct *tsec = current->security; | |
496 | struct xfrm_sec_ctx *ctx = x->security; | |
497 | int rc = 0; | |
498 | ||
499 | if (ctx) | |
500 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
501 | SECCLASS_ASSOCIATION, | |
502 | ASSOCIATION__SETCONTEXT, NULL); | |
503 | ||
504 | return rc; | |
505 | } | |
506 | ||
d28d1e08 TJ |
507 | /* |
508 | * LSM hook that controls access to unlabelled packets. If | |
509 | * a xfrm_state is authorizable (defined by macro) then it was | |
510 | * already authorized by the IPSec process. If not, then | |
511 | * we need to check for unlabelled access since this may not have | |
512 | * gone thru the IPSec process. | |
513 | */ | |
e0d1caa7 VY |
514 | int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, |
515 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
516 | { |
517 | int i, rc = 0; | |
518 | struct sec_path *sp; | |
e0d1caa7 | 519 | u32 sel_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
520 | |
521 | sp = skb->sp; | |
522 | ||
523 | if (sp) { | |
d28d1e08 | 524 | for (i = 0; i < sp->len; i++) { |
67644726 | 525 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 526 | |
e0d1caa7 VY |
527 | if (x && selinux_authorizable_xfrm(x)) { |
528 | struct xfrm_sec_ctx *ctx = x->security; | |
529 | sel_sid = ctx->ctx_sid; | |
530 | break; | |
531 | } | |
d28d1e08 TJ |
532 | } |
533 | } | |
534 | ||
e0d1caa7 VY |
535 | rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, |
536 | ASSOCIATION__RECVFROM, ad); | |
d28d1e08 | 537 | |
d28d1e08 TJ |
538 | return rc; |
539 | } | |
540 | ||
541 | /* | |
542 | * POSTROUTE_LAST hook's XFRM processing: | |
543 | * If we have no security association, then we need to determine | |
544 | * whether the socket is allowed to send to an unlabelled destination. | |
545 | * If we do have a authorizable security association, then it has already been | |
546 | * checked in xfrm_policy_lookup hook. | |
547 | */ | |
e0d1caa7 VY |
548 | int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, |
549 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
550 | { |
551 | struct dst_entry *dst; | |
552 | int rc = 0; | |
553 | ||
554 | dst = skb->dst; | |
555 | ||
556 | if (dst) { | |
557 | struct dst_entry *dst_test; | |
558 | ||
559 | for (dst_test = dst; dst_test != 0; | |
560 | dst_test = dst_test->child) { | |
561 | struct xfrm_state *x = dst_test->xfrm; | |
562 | ||
563 | if (x && selinux_authorizable_xfrm(x)) | |
4e5ab4cb | 564 | goto out; |
d28d1e08 TJ |
565 | } |
566 | } | |
567 | ||
568 | rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, | |
e0d1caa7 | 569 | ASSOCIATION__SENDTO, ad); |
4e5ab4cb JM |
570 | out: |
571 | return rc; | |
d28d1e08 | 572 | } |