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