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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/kernel.h> |
35 | #include <linux/init.h> | |
36 | #include <linux/security.h> | |
37 | #include <linux/types.h> | |
38 | #include <linux/netfilter.h> | |
39 | #include <linux/netfilter_ipv4.h> | |
40 | #include <linux/netfilter_ipv6.h> | |
41 | #include <linux/ip.h> | |
42 | #include <linux/tcp.h> | |
43 | #include <linux/skbuff.h> | |
44 | #include <linux/xfrm.h> | |
45 | #include <net/xfrm.h> | |
46 | #include <net/checksum.h> | |
47 | #include <net/udp.h> | |
48 | #include <asm/semaphore.h> | |
d621d35e | 49 | #include <asm/atomic.h> |
d28d1e08 TJ |
50 | |
51 | #include "avc.h" | |
52 | #include "objsec.h" | |
53 | #include "xfrm.h" | |
54 | ||
d621d35e PM |
55 | /* Labeled XFRM instance counter */ |
56 | atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0); | |
d28d1e08 TJ |
57 | |
58 | /* | |
59 | * Returns true if an LSM/SELinux context | |
60 | */ | |
61 | static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx) | |
62 | { | |
63 | return (ctx && | |
64 | (ctx->ctx_doi == XFRM_SC_DOI_LSM) && | |
65 | (ctx->ctx_alg == XFRM_SC_ALG_SELINUX)); | |
66 | } | |
67 | ||
68 | /* | |
69 | * Returns true if the xfrm contains a security blob for SELinux | |
70 | */ | |
71 | static inline int selinux_authorizable_xfrm(struct xfrm_state *x) | |
72 | { | |
73 | return selinux_authorizable_ctx(x->security); | |
74 | } | |
75 | ||
76 | /* | |
e0d1caa7 VY |
77 | * LSM hook implementation that authorizes that a flow can use |
78 | * a xfrm policy rule. | |
d28d1e08 | 79 | */ |
e0d1caa7 | 80 | int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir) |
d28d1e08 | 81 | { |
5b368e61 VY |
82 | int rc; |
83 | u32 sel_sid; | |
d28d1e08 TJ |
84 | struct xfrm_sec_ctx *ctx; |
85 | ||
86 | /* Context sid is either set to label or ANY_ASSOC */ | |
87 | if ((ctx = xp->security)) { | |
88 | if (!selinux_authorizable_ctx(ctx)) | |
89 | return -EINVAL; | |
90 | ||
91 | sel_sid = ctx->ctx_sid; | |
92 | } | |
5b368e61 VY |
93 | else |
94 | /* | |
95 | * All flows should be treated as polmatch'ing an | |
96 | * otherwise applicable "non-labeled" policy. This | |
97 | * would prevent inadvertent "leaks". | |
98 | */ | |
99 | return 0; | |
d28d1e08 | 100 | |
e0d1caa7 VY |
101 | rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, |
102 | ASSOCIATION__POLMATCH, | |
d28d1e08 TJ |
103 | NULL); |
104 | ||
5b368e61 VY |
105 | if (rc == -EACCES) |
106 | rc = -ESRCH; | |
107 | ||
d28d1e08 TJ |
108 | return rc; |
109 | } | |
110 | ||
e0d1caa7 VY |
111 | /* |
112 | * LSM hook implementation that authorizes that a state matches | |
113 | * the given policy, flow combo. | |
114 | */ | |
115 | ||
116 | int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp, | |
117 | struct flowi *fl) | |
118 | { | |
119 | u32 state_sid; | |
67f83cbf | 120 | int rc; |
e0d1caa7 | 121 | |
67f83cbf | 122 | if (!xp->security) |
5b368e61 VY |
123 | if (x->security) |
124 | /* unlabeled policy and labeled SA can't match */ | |
125 | return 0; | |
126 | else | |
127 | /* unlabeled policy and unlabeled SA match all flows */ | |
128 | return 1; | |
5b368e61 | 129 | else |
67f83cbf VY |
130 | if (!x->security) |
131 | /* unlabeled SA and labeled policy can't match */ | |
5b368e61 | 132 | return 0; |
67f83cbf VY |
133 | else |
134 | if (!selinux_authorizable_xfrm(x)) | |
135 | /* Not a SELinux-labeled SA */ | |
136 | return 0; | |
5b368e61 | 137 | |
67f83cbf | 138 | state_sid = x->security->ctx_sid; |
e0d1caa7 | 139 | |
67f83cbf VY |
140 | if (fl->secid != state_sid) |
141 | return 0; | |
e0d1caa7 | 142 | |
67f83cbf | 143 | rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION, |
e0d1caa7 VY |
144 | ASSOCIATION__SENDTO, |
145 | NULL)? 0:1; | |
146 | ||
67f83cbf VY |
147 | /* |
148 | * We don't need a separate SA Vs. policy polmatch check | |
149 | * since the SA is now of the same label as the flow and | |
150 | * a flow Vs. policy polmatch check had already happened | |
151 | * in selinux_xfrm_policy_lookup() above. | |
152 | */ | |
153 | ||
e0d1caa7 VY |
154 | return rc; |
155 | } | |
156 | ||
157 | /* | |
6b877699 VY |
158 | * LSM hook implementation that checks and/or returns the xfrm sid for the |
159 | * incoming packet. | |
e0d1caa7 VY |
160 | */ |
161 | ||
beb8d13b | 162 | int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) |
e0d1caa7 VY |
163 | { |
164 | struct sec_path *sp; | |
165 | ||
beb8d13b | 166 | *sid = SECSID_NULL; |
e0d1caa7 VY |
167 | |
168 | if (skb == NULL) | |
169 | return 0; | |
170 | ||
171 | sp = skb->sp; | |
172 | if (sp) { | |
173 | int i, sid_set = 0; | |
174 | ||
175 | for (i = sp->len-1; i >= 0; i--) { | |
176 | struct xfrm_state *x = sp->xvec[i]; | |
177 | if (selinux_authorizable_xfrm(x)) { | |
178 | struct xfrm_sec_ctx *ctx = x->security; | |
179 | ||
180 | if (!sid_set) { | |
beb8d13b | 181 | *sid = ctx->ctx_sid; |
e0d1caa7 | 182 | sid_set = 1; |
beb8d13b VY |
183 | |
184 | if (!ckall) | |
185 | break; | |
e0d1caa7 | 186 | } |
beb8d13b | 187 | else if (*sid != ctx->ctx_sid) |
e0d1caa7 VY |
188 | return -EINVAL; |
189 | } | |
190 | } | |
191 | } | |
192 | ||
193 | return 0; | |
194 | } | |
195 | ||
d28d1e08 TJ |
196 | /* |
197 | * Security blob allocation for xfrm_policy and xfrm_state | |
198 | * CTX does not have a meaningful value on input | |
199 | */ | |
e0d1caa7 | 200 | static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, |
c1a856c9 | 201 | struct xfrm_user_sec_ctx *uctx, u32 sid) |
d28d1e08 TJ |
202 | { |
203 | int rc = 0; | |
204 | struct task_security_struct *tsec = current->security; | |
e0d1caa7 VY |
205 | struct xfrm_sec_ctx *ctx = NULL; |
206 | char *ctx_str = NULL; | |
207 | u32 str_len; | |
e0d1caa7 | 208 | |
c1a856c9 | 209 | BUG_ON(uctx && sid); |
e0d1caa7 | 210 | |
cb969f07 VY |
211 | if (!uctx) |
212 | goto not_from_user; | |
e0d1caa7 VY |
213 | |
214 | if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) | |
215 | return -EINVAL; | |
d28d1e08 | 216 | |
57002bfb SR |
217 | str_len = uctx->ctx_len; |
218 | if (str_len >= PAGE_SIZE) | |
d28d1e08 TJ |
219 | return -ENOMEM; |
220 | ||
221 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
57002bfb | 222 | str_len + 1, |
d28d1e08 TJ |
223 | GFP_KERNEL); |
224 | ||
225 | if (!ctx) | |
226 | return -ENOMEM; | |
227 | ||
228 | ctx->ctx_doi = uctx->ctx_doi; | |
57002bfb | 229 | ctx->ctx_len = str_len; |
d28d1e08 TJ |
230 | ctx->ctx_alg = uctx->ctx_alg; |
231 | ||
232 | memcpy(ctx->ctx_str, | |
233 | uctx+1, | |
57002bfb SR |
234 | str_len); |
235 | ctx->ctx_str[str_len] = 0; | |
d28d1e08 | 236 | rc = security_context_to_sid(ctx->ctx_str, |
57002bfb | 237 | str_len, |
d28d1e08 TJ |
238 | &ctx->ctx_sid); |
239 | ||
240 | if (rc) | |
241 | goto out; | |
242 | ||
243 | /* | |
c8c05a8e | 244 | * Does the subject have permission to set security context? |
d28d1e08 | 245 | */ |
d28d1e08 TJ |
246 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
247 | SECCLASS_ASSOCIATION, | |
5f8ac64b | 248 | ASSOCIATION__SETCONTEXT, NULL); |
d28d1e08 TJ |
249 | if (rc) |
250 | goto out; | |
251 | ||
252 | return rc; | |
253 | ||
cb969f07 | 254 | not_from_user: |
c1a856c9 | 255 | rc = security_sid_to_context(sid, &ctx_str, &str_len); |
e0d1caa7 VY |
256 | if (rc) |
257 | goto out; | |
258 | ||
259 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
260 | str_len, | |
261 | GFP_ATOMIC); | |
262 | ||
263 | if (!ctx) { | |
264 | rc = -ENOMEM; | |
265 | goto out; | |
266 | } | |
267 | ||
e0d1caa7 VY |
268 | ctx->ctx_doi = XFRM_SC_DOI_LSM; |
269 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
c1a856c9 | 270 | ctx->ctx_sid = sid; |
e0d1caa7 VY |
271 | ctx->ctx_len = str_len; |
272 | memcpy(ctx->ctx_str, | |
273 | ctx_str, | |
274 | str_len); | |
275 | ||
276 | goto out2; | |
277 | ||
d28d1e08 | 278 | out: |
ee2e6841 | 279 | *ctxp = NULL; |
d28d1e08 | 280 | kfree(ctx); |
e0d1caa7 VY |
281 | out2: |
282 | kfree(ctx_str); | |
d28d1e08 TJ |
283 | return rc; |
284 | } | |
285 | ||
286 | /* | |
287 | * LSM hook implementation that allocs and transfers uctx spec to | |
288 | * xfrm_policy. | |
289 | */ | |
cb969f07 | 290 | int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, |
c1a856c9 | 291 | struct xfrm_user_sec_ctx *uctx) |
d28d1e08 TJ |
292 | { |
293 | int err; | |
294 | ||
295 | BUG_ON(!xp); | |
c1a856c9 | 296 | BUG_ON(!uctx); |
d28d1e08 | 297 | |
c1a856c9 | 298 | err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0); |
d621d35e PM |
299 | if (err == 0) |
300 | atomic_inc(&selinux_xfrm_refcount); | |
301 | ||
d28d1e08 TJ |
302 | return err; |
303 | } | |
304 | ||
305 | ||
306 | /* | |
307 | * LSM hook implementation that copies security data structure from old to | |
308 | * new for policy cloning. | |
309 | */ | |
310 | int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new) | |
311 | { | |
312 | struct xfrm_sec_ctx *old_ctx, *new_ctx; | |
313 | ||
314 | old_ctx = old->security; | |
315 | ||
316 | if (old_ctx) { | |
317 | new_ctx = new->security = kmalloc(sizeof(*new_ctx) + | |
318 | old_ctx->ctx_len, | |
319 | GFP_KERNEL); | |
320 | ||
321 | if (!new_ctx) | |
322 | return -ENOMEM; | |
323 | ||
324 | memcpy(new_ctx, old_ctx, sizeof(*new_ctx)); | |
325 | memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len); | |
326 | } | |
327 | return 0; | |
328 | } | |
329 | ||
330 | /* | |
331 | * LSM hook implementation that frees xfrm_policy security information. | |
332 | */ | |
333 | void selinux_xfrm_policy_free(struct xfrm_policy *xp) | |
334 | { | |
335 | struct xfrm_sec_ctx *ctx = xp->security; | |
336 | if (ctx) | |
337 | kfree(ctx); | |
338 | } | |
339 | ||
c8c05a8e CZ |
340 | /* |
341 | * LSM hook implementation that authorizes deletion of labeled policies. | |
342 | */ | |
343 | int selinux_xfrm_policy_delete(struct xfrm_policy *xp) | |
344 | { | |
345 | struct task_security_struct *tsec = current->security; | |
346 | struct xfrm_sec_ctx *ctx = xp->security; | |
347 | int rc = 0; | |
348 | ||
d621d35e | 349 | if (ctx) { |
c8c05a8e CZ |
350 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
351 | SECCLASS_ASSOCIATION, | |
352 | ASSOCIATION__SETCONTEXT, NULL); | |
d621d35e PM |
353 | if (rc == 0) |
354 | atomic_dec(&selinux_xfrm_refcount); | |
355 | } | |
c8c05a8e CZ |
356 | |
357 | return rc; | |
358 | } | |
359 | ||
d28d1e08 TJ |
360 | /* |
361 | * LSM hook implementation that allocs and transfers sec_ctx spec to | |
362 | * xfrm_state. | |
363 | */ | |
e0d1caa7 | 364 | int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx, |
c1a856c9 | 365 | u32 secid) |
d28d1e08 TJ |
366 | { |
367 | int err; | |
368 | ||
369 | BUG_ON(!x); | |
370 | ||
c1a856c9 | 371 | err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid); |
d621d35e PM |
372 | if (err == 0) |
373 | atomic_inc(&selinux_xfrm_refcount); | |
d28d1e08 TJ |
374 | return err; |
375 | } | |
376 | ||
377 | /* | |
378 | * LSM hook implementation that frees xfrm_state security information. | |
379 | */ | |
380 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
381 | { | |
382 | struct xfrm_sec_ctx *ctx = x->security; | |
383 | if (ctx) | |
384 | kfree(ctx); | |
385 | } | |
386 | ||
c8c05a8e CZ |
387 | /* |
388 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
389 | */ | |
390 | int selinux_xfrm_state_delete(struct xfrm_state *x) | |
391 | { | |
392 | struct task_security_struct *tsec = current->security; | |
393 | struct xfrm_sec_ctx *ctx = x->security; | |
394 | int rc = 0; | |
395 | ||
d621d35e | 396 | if (ctx) { |
c8c05a8e CZ |
397 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
398 | SECCLASS_ASSOCIATION, | |
399 | ASSOCIATION__SETCONTEXT, NULL); | |
d621d35e PM |
400 | if (rc == 0) |
401 | atomic_dec(&selinux_xfrm_refcount); | |
402 | } | |
c8c05a8e CZ |
403 | |
404 | return rc; | |
405 | } | |
406 | ||
d28d1e08 TJ |
407 | /* |
408 | * LSM hook that controls access to unlabelled packets. If | |
409 | * a xfrm_state is authorizable (defined by macro) then it was | |
410 | * already authorized by the IPSec process. If not, then | |
411 | * we need to check for unlabelled access since this may not have | |
412 | * gone thru the IPSec process. | |
413 | */ | |
e0d1caa7 VY |
414 | int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, |
415 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
416 | { |
417 | int i, rc = 0; | |
418 | struct sec_path *sp; | |
e0d1caa7 | 419 | u32 sel_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
420 | |
421 | sp = skb->sp; | |
422 | ||
423 | if (sp) { | |
d28d1e08 | 424 | for (i = 0; i < sp->len; i++) { |
67644726 | 425 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 426 | |
e0d1caa7 VY |
427 | if (x && selinux_authorizable_xfrm(x)) { |
428 | struct xfrm_sec_ctx *ctx = x->security; | |
429 | sel_sid = ctx->ctx_sid; | |
430 | break; | |
431 | } | |
d28d1e08 TJ |
432 | } |
433 | } | |
434 | ||
67f83cbf VY |
435 | /* |
436 | * This check even when there's no association involved is | |
437 | * intended, according to Trent Jaeger, to make sure a | |
438 | * process can't engage in non-ipsec communication unless | |
439 | * explicitly allowed by policy. | |
440 | */ | |
441 | ||
e0d1caa7 VY |
442 | rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, |
443 | ASSOCIATION__RECVFROM, ad); | |
d28d1e08 | 444 | |
d28d1e08 TJ |
445 | return rc; |
446 | } | |
447 | ||
448 | /* | |
449 | * POSTROUTE_LAST hook's XFRM processing: | |
450 | * If we have no security association, then we need to determine | |
451 | * whether the socket is allowed to send to an unlabelled destination. | |
452 | * If we do have a authorizable security association, then it has already been | |
67f83cbf | 453 | * checked in the selinux_xfrm_state_pol_flow_match hook above. |
d28d1e08 | 454 | */ |
e0d1caa7 | 455 | int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, |
67f83cbf | 456 | struct avc_audit_data *ad, u8 proto) |
d28d1e08 TJ |
457 | { |
458 | struct dst_entry *dst; | |
459 | int rc = 0; | |
460 | ||
461 | dst = skb->dst; | |
462 | ||
463 | if (dst) { | |
464 | struct dst_entry *dst_test; | |
465 | ||
c80544dc | 466 | for (dst_test = dst; dst_test != NULL; |
d28d1e08 TJ |
467 | dst_test = dst_test->child) { |
468 | struct xfrm_state *x = dst_test->xfrm; | |
469 | ||
470 | if (x && selinux_authorizable_xfrm(x)) | |
4e5ab4cb | 471 | goto out; |
d28d1e08 TJ |
472 | } |
473 | } | |
474 | ||
67f83cbf VY |
475 | switch (proto) { |
476 | case IPPROTO_AH: | |
477 | case IPPROTO_ESP: | |
478 | case IPPROTO_COMP: | |
479 | /* | |
480 | * We should have already seen this packet once before | |
481 | * it underwent xfrm(s). No need to subject it to the | |
482 | * unlabeled check. | |
483 | */ | |
484 | goto out; | |
485 | default: | |
486 | break; | |
487 | } | |
488 | ||
489 | /* | |
490 | * This check even when there's no association involved is | |
491 | * intended, according to Trent Jaeger, to make sure a | |
492 | * process can't engage in non-ipsec communication unless | |
493 | * explicitly allowed by policy. | |
494 | */ | |
495 | ||
d28d1e08 | 496 | rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, |
e0d1caa7 | 497 | ASSOCIATION__SENDTO, ad); |
4e5ab4cb JM |
498 | out: |
499 | return rc; | |
d28d1e08 | 500 | } |