]>
Commit | Line | Data |
---|---|---|
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 | /* | |
6b877699 VY |
187 | * LSM hook implementation that checks and/or returns the xfrm sid for the |
188 | * incoming packet. | |
e0d1caa7 VY |
189 | */ |
190 | ||
beb8d13b | 191 | int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) |
e0d1caa7 VY |
192 | { |
193 | struct sec_path *sp; | |
194 | ||
beb8d13b | 195 | *sid = SECSID_NULL; |
e0d1caa7 VY |
196 | |
197 | if (skb == NULL) | |
198 | return 0; | |
199 | ||
200 | sp = skb->sp; | |
201 | if (sp) { | |
202 | int i, sid_set = 0; | |
203 | ||
204 | for (i = sp->len-1; i >= 0; i--) { | |
205 | struct xfrm_state *x = sp->xvec[i]; | |
206 | if (selinux_authorizable_xfrm(x)) { | |
207 | struct xfrm_sec_ctx *ctx = x->security; | |
208 | ||
209 | if (!sid_set) { | |
beb8d13b | 210 | *sid = ctx->ctx_sid; |
e0d1caa7 | 211 | sid_set = 1; |
beb8d13b VY |
212 | |
213 | if (!ckall) | |
214 | break; | |
e0d1caa7 | 215 | } |
beb8d13b | 216 | else if (*sid != ctx->ctx_sid) |
e0d1caa7 VY |
217 | return -EINVAL; |
218 | } | |
219 | } | |
220 | } | |
221 | ||
222 | return 0; | |
223 | } | |
224 | ||
d28d1e08 TJ |
225 | /* |
226 | * Security blob allocation for xfrm_policy and xfrm_state | |
227 | * CTX does not have a meaningful value on input | |
228 | */ | |
e0d1caa7 | 229 | static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, |
c1a856c9 | 230 | struct xfrm_user_sec_ctx *uctx, u32 sid) |
d28d1e08 TJ |
231 | { |
232 | int rc = 0; | |
233 | struct task_security_struct *tsec = current->security; | |
e0d1caa7 VY |
234 | struct xfrm_sec_ctx *ctx = NULL; |
235 | char *ctx_str = NULL; | |
236 | u32 str_len; | |
e0d1caa7 | 237 | |
c1a856c9 | 238 | BUG_ON(uctx && sid); |
e0d1caa7 | 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 | 281 | not_from_user: |
c1a856c9 | 282 | rc = security_sid_to_context(sid, &ctx_str, &str_len); |
e0d1caa7 VY |
283 | if (rc) |
284 | goto out; | |
285 | ||
286 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
287 | str_len, | |
288 | GFP_ATOMIC); | |
289 | ||
290 | if (!ctx) { | |
291 | rc = -ENOMEM; | |
292 | goto out; | |
293 | } | |
294 | ||
e0d1caa7 VY |
295 | ctx->ctx_doi = XFRM_SC_DOI_LSM; |
296 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
c1a856c9 | 297 | ctx->ctx_sid = sid; |
e0d1caa7 VY |
298 | ctx->ctx_len = str_len; |
299 | memcpy(ctx->ctx_str, | |
300 | ctx_str, | |
301 | str_len); | |
302 | ||
303 | goto out2; | |
304 | ||
d28d1e08 | 305 | out: |
ee2e6841 | 306 | *ctxp = NULL; |
d28d1e08 | 307 | kfree(ctx); |
e0d1caa7 VY |
308 | out2: |
309 | kfree(ctx_str); | |
d28d1e08 TJ |
310 | return rc; |
311 | } | |
312 | ||
313 | /* | |
314 | * LSM hook implementation that allocs and transfers uctx spec to | |
315 | * xfrm_policy. | |
316 | */ | |
cb969f07 | 317 | int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, |
c1a856c9 | 318 | struct xfrm_user_sec_ctx *uctx) |
d28d1e08 TJ |
319 | { |
320 | int err; | |
321 | ||
322 | BUG_ON(!xp); | |
c1a856c9 | 323 | BUG_ON(!uctx); |
d28d1e08 | 324 | |
c1a856c9 | 325 | err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0); |
d28d1e08 TJ |
326 | return err; |
327 | } | |
328 | ||
329 | ||
330 | /* | |
331 | * LSM hook implementation that copies security data structure from old to | |
332 | * new for policy cloning. | |
333 | */ | |
334 | int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new) | |
335 | { | |
336 | struct xfrm_sec_ctx *old_ctx, *new_ctx; | |
337 | ||
338 | old_ctx = old->security; | |
339 | ||
340 | if (old_ctx) { | |
341 | new_ctx = new->security = kmalloc(sizeof(*new_ctx) + | |
342 | old_ctx->ctx_len, | |
343 | GFP_KERNEL); | |
344 | ||
345 | if (!new_ctx) | |
346 | return -ENOMEM; | |
347 | ||
348 | memcpy(new_ctx, old_ctx, sizeof(*new_ctx)); | |
349 | memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len); | |
350 | } | |
351 | return 0; | |
352 | } | |
353 | ||
354 | /* | |
355 | * LSM hook implementation that frees xfrm_policy security information. | |
356 | */ | |
357 | void selinux_xfrm_policy_free(struct xfrm_policy *xp) | |
358 | { | |
359 | struct xfrm_sec_ctx *ctx = xp->security; | |
360 | if (ctx) | |
361 | kfree(ctx); | |
362 | } | |
363 | ||
c8c05a8e CZ |
364 | /* |
365 | * LSM hook implementation that authorizes deletion of labeled policies. | |
366 | */ | |
367 | int selinux_xfrm_policy_delete(struct xfrm_policy *xp) | |
368 | { | |
369 | struct task_security_struct *tsec = current->security; | |
370 | struct xfrm_sec_ctx *ctx = xp->security; | |
371 | int rc = 0; | |
372 | ||
373 | if (ctx) | |
374 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
375 | SECCLASS_ASSOCIATION, | |
376 | ASSOCIATION__SETCONTEXT, NULL); | |
377 | ||
378 | return rc; | |
379 | } | |
380 | ||
d28d1e08 TJ |
381 | /* |
382 | * LSM hook implementation that allocs and transfers sec_ctx spec to | |
383 | * xfrm_state. | |
384 | */ | |
e0d1caa7 | 385 | int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx, |
c1a856c9 | 386 | u32 secid) |
d28d1e08 TJ |
387 | { |
388 | int err; | |
389 | ||
390 | BUG_ON(!x); | |
391 | ||
c1a856c9 | 392 | err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid); |
d28d1e08 TJ |
393 | return err; |
394 | } | |
395 | ||
396 | /* | |
397 | * LSM hook implementation that frees xfrm_state security information. | |
398 | */ | |
399 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
400 | { | |
401 | struct xfrm_sec_ctx *ctx = x->security; | |
402 | if (ctx) | |
403 | kfree(ctx); | |
404 | } | |
405 | ||
2c7946a7 CZ |
406 | /* |
407 | * SELinux internal function to retrieve the context of a UDP packet | |
6b877699 | 408 | * based on its security association. |
2c7946a7 CZ |
409 | * |
410 | * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message | |
411 | * type SCM_SECURITY. | |
412 | */ | |
413 | u32 selinux_socket_getpeer_dgram(struct sk_buff *skb) | |
414 | { | |
415 | struct sec_path *sp; | |
416 | ||
417 | if (skb == NULL) | |
418 | return SECSID_NULL; | |
419 | ||
420 | if (skb->sk->sk_protocol != IPPROTO_UDP) | |
421 | return SECSID_NULL; | |
422 | ||
423 | sp = skb->sp; | |
424 | if (sp) { | |
425 | int i; | |
426 | ||
427 | for (i = sp->len-1; i >= 0; i--) { | |
67644726 | 428 | struct xfrm_state *x = sp->xvec[i]; |
2c7946a7 CZ |
429 | if (selinux_authorizable_xfrm(x)) { |
430 | struct xfrm_sec_ctx *ctx = x->security; | |
431 | return ctx->ctx_sid; | |
432 | } | |
433 | } | |
434 | } | |
435 | ||
436 | return SECSID_NULL; | |
437 | } | |
438 | ||
c8c05a8e CZ |
439 | /* |
440 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
441 | */ | |
442 | int selinux_xfrm_state_delete(struct xfrm_state *x) | |
443 | { | |
444 | struct task_security_struct *tsec = current->security; | |
445 | struct xfrm_sec_ctx *ctx = x->security; | |
446 | int rc = 0; | |
447 | ||
448 | if (ctx) | |
449 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, | |
450 | SECCLASS_ASSOCIATION, | |
451 | ASSOCIATION__SETCONTEXT, NULL); | |
452 | ||
453 | return rc; | |
454 | } | |
455 | ||
d28d1e08 TJ |
456 | /* |
457 | * LSM hook that controls access to unlabelled packets. If | |
458 | * a xfrm_state is authorizable (defined by macro) then it was | |
459 | * already authorized by the IPSec process. If not, then | |
460 | * we need to check for unlabelled access since this may not have | |
461 | * gone thru the IPSec process. | |
462 | */ | |
e0d1caa7 VY |
463 | int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, |
464 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
465 | { |
466 | int i, rc = 0; | |
467 | struct sec_path *sp; | |
e0d1caa7 | 468 | u32 sel_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
469 | |
470 | sp = skb->sp; | |
471 | ||
472 | if (sp) { | |
d28d1e08 | 473 | for (i = 0; i < sp->len; i++) { |
67644726 | 474 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 475 | |
e0d1caa7 VY |
476 | if (x && selinux_authorizable_xfrm(x)) { |
477 | struct xfrm_sec_ctx *ctx = x->security; | |
478 | sel_sid = ctx->ctx_sid; | |
479 | break; | |
480 | } | |
d28d1e08 TJ |
481 | } |
482 | } | |
483 | ||
e0d1caa7 VY |
484 | rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, |
485 | ASSOCIATION__RECVFROM, ad); | |
d28d1e08 | 486 | |
d28d1e08 TJ |
487 | return rc; |
488 | } | |
489 | ||
490 | /* | |
491 | * POSTROUTE_LAST hook's XFRM processing: | |
492 | * If we have no security association, then we need to determine | |
493 | * whether the socket is allowed to send to an unlabelled destination. | |
494 | * If we do have a authorizable security association, then it has already been | |
495 | * checked in xfrm_policy_lookup hook. | |
496 | */ | |
e0d1caa7 VY |
497 | int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, |
498 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
499 | { |
500 | struct dst_entry *dst; | |
501 | int rc = 0; | |
502 | ||
503 | dst = skb->dst; | |
504 | ||
505 | if (dst) { | |
506 | struct dst_entry *dst_test; | |
507 | ||
508 | for (dst_test = dst; dst_test != 0; | |
509 | dst_test = dst_test->child) { | |
510 | struct xfrm_state *x = dst_test->xfrm; | |
511 | ||
512 | if (x && selinux_authorizable_xfrm(x)) | |
4e5ab4cb | 513 | goto out; |
d28d1e08 TJ |
514 | } |
515 | } | |
516 | ||
517 | rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, | |
e0d1caa7 | 518 | ASSOCIATION__SENDTO, ad); |
4e5ab4cb JM |
519 | out: |
520 | return rc; | |
d28d1e08 | 521 | } |