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/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> | |
d621d35e | 48 | #include <asm/atomic.h> |
d28d1e08 TJ |
49 | |
50 | #include "avc.h" | |
51 | #include "objsec.h" | |
52 | #include "xfrm.h" | |
53 | ||
d621d35e PM |
54 | /* Labeled XFRM instance counter */ |
55 | atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0); | |
d28d1e08 TJ |
56 | |
57 | /* | |
58 | * Returns true if an LSM/SELinux context | |
59 | */ | |
60 | static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx) | |
61 | { | |
62 | return (ctx && | |
63 | (ctx->ctx_doi == XFRM_SC_DOI_LSM) && | |
64 | (ctx->ctx_alg == XFRM_SC_ALG_SELINUX)); | |
65 | } | |
66 | ||
67 | /* | |
68 | * Returns true if the xfrm contains a security blob for SELinux | |
69 | */ | |
70 | static inline int selinux_authorizable_xfrm(struct xfrm_state *x) | |
71 | { | |
72 | return selinux_authorizable_ctx(x->security); | |
73 | } | |
74 | ||
75 | /* | |
e0d1caa7 VY |
76 | * LSM hook implementation that authorizes that a flow can use |
77 | * a xfrm policy rule. | |
d28d1e08 | 78 | */ |
03e1ad7b | 79 | int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir) |
d28d1e08 | 80 | { |
5b368e61 VY |
81 | int rc; |
82 | u32 sel_sid; | |
d28d1e08 TJ |
83 | |
84 | /* Context sid is either set to label or ANY_ASSOC */ | |
03e1ad7b | 85 | if (ctx) { |
d28d1e08 TJ |
86 | if (!selinux_authorizable_ctx(ctx)) |
87 | return -EINVAL; | |
88 | ||
89 | sel_sid = ctx->ctx_sid; | |
03e1ad7b | 90 | } else |
5b368e61 VY |
91 | /* |
92 | * All flows should be treated as polmatch'ing an | |
93 | * otherwise applicable "non-labeled" policy. This | |
94 | * would prevent inadvertent "leaks". | |
95 | */ | |
96 | return 0; | |
d28d1e08 | 97 | |
e0d1caa7 VY |
98 | rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION, |
99 | ASSOCIATION__POLMATCH, | |
d28d1e08 TJ |
100 | NULL); |
101 | ||
5b368e61 | 102 | if (rc == -EACCES) |
03e1ad7b | 103 | return -ESRCH; |
5b368e61 | 104 | |
d28d1e08 TJ |
105 | return rc; |
106 | } | |
107 | ||
e0d1caa7 VY |
108 | /* |
109 | * LSM hook implementation that authorizes that a state matches | |
110 | * the given policy, flow combo. | |
111 | */ | |
112 | ||
113 | int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp, | |
114 | struct flowi *fl) | |
115 | { | |
116 | u32 state_sid; | |
67f83cbf | 117 | int rc; |
e0d1caa7 | 118 | |
67f83cbf | 119 | if (!xp->security) |
5b368e61 VY |
120 | if (x->security) |
121 | /* unlabeled policy and labeled SA can't match */ | |
122 | return 0; | |
123 | else | |
124 | /* unlabeled policy and unlabeled SA match all flows */ | |
125 | return 1; | |
5b368e61 | 126 | else |
67f83cbf VY |
127 | if (!x->security) |
128 | /* unlabeled SA and labeled policy can't match */ | |
5b368e61 | 129 | return 0; |
67f83cbf VY |
130 | else |
131 | if (!selinux_authorizable_xfrm(x)) | |
132 | /* Not a SELinux-labeled SA */ | |
133 | return 0; | |
5b368e61 | 134 | |
67f83cbf | 135 | state_sid = x->security->ctx_sid; |
e0d1caa7 | 136 | |
67f83cbf VY |
137 | if (fl->secid != state_sid) |
138 | return 0; | |
e0d1caa7 | 139 | |
67f83cbf | 140 | rc = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION, |
e0d1caa7 VY |
141 | ASSOCIATION__SENDTO, |
142 | NULL)? 0:1; | |
143 | ||
67f83cbf VY |
144 | /* |
145 | * We don't need a separate SA Vs. policy polmatch check | |
146 | * since the SA is now of the same label as the flow and | |
147 | * a flow Vs. policy polmatch check had already happened | |
148 | * in selinux_xfrm_policy_lookup() above. | |
149 | */ | |
150 | ||
e0d1caa7 VY |
151 | return rc; |
152 | } | |
153 | ||
154 | /* | |
6b877699 VY |
155 | * LSM hook implementation that checks and/or returns the xfrm sid for the |
156 | * incoming packet. | |
e0d1caa7 VY |
157 | */ |
158 | ||
beb8d13b | 159 | int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) |
e0d1caa7 VY |
160 | { |
161 | struct sec_path *sp; | |
162 | ||
beb8d13b | 163 | *sid = SECSID_NULL; |
e0d1caa7 VY |
164 | |
165 | if (skb == NULL) | |
166 | return 0; | |
167 | ||
168 | sp = skb->sp; | |
169 | if (sp) { | |
170 | int i, sid_set = 0; | |
171 | ||
172 | for (i = sp->len-1; i >= 0; i--) { | |
173 | struct xfrm_state *x = sp->xvec[i]; | |
174 | if (selinux_authorizable_xfrm(x)) { | |
175 | struct xfrm_sec_ctx *ctx = x->security; | |
176 | ||
177 | if (!sid_set) { | |
beb8d13b | 178 | *sid = ctx->ctx_sid; |
e0d1caa7 | 179 | sid_set = 1; |
beb8d13b VY |
180 | |
181 | if (!ckall) | |
182 | break; | |
3c1c88ab | 183 | } else if (*sid != ctx->ctx_sid) |
e0d1caa7 VY |
184 | return -EINVAL; |
185 | } | |
186 | } | |
187 | } | |
188 | ||
189 | return 0; | |
190 | } | |
191 | ||
d28d1e08 TJ |
192 | /* |
193 | * Security blob allocation for xfrm_policy and xfrm_state | |
194 | * CTX does not have a meaningful value on input | |
195 | */ | |
e0d1caa7 | 196 | static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp, |
c1a856c9 | 197 | struct xfrm_user_sec_ctx *uctx, u32 sid) |
d28d1e08 TJ |
198 | { |
199 | int rc = 0; | |
200 | struct task_security_struct *tsec = current->security; | |
e0d1caa7 VY |
201 | struct xfrm_sec_ctx *ctx = NULL; |
202 | char *ctx_str = NULL; | |
203 | u32 str_len; | |
e0d1caa7 | 204 | |
c1a856c9 | 205 | BUG_ON(uctx && sid); |
e0d1caa7 | 206 | |
cb969f07 VY |
207 | if (!uctx) |
208 | goto not_from_user; | |
e0d1caa7 VY |
209 | |
210 | if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX) | |
211 | return -EINVAL; | |
d28d1e08 | 212 | |
57002bfb SR |
213 | str_len = uctx->ctx_len; |
214 | if (str_len >= PAGE_SIZE) | |
d28d1e08 TJ |
215 | return -ENOMEM; |
216 | ||
217 | *ctxp = ctx = kmalloc(sizeof(*ctx) + | |
57002bfb | 218 | str_len + 1, |
d28d1e08 TJ |
219 | GFP_KERNEL); |
220 | ||
221 | if (!ctx) | |
222 | return -ENOMEM; | |
223 | ||
224 | ctx->ctx_doi = uctx->ctx_doi; | |
57002bfb | 225 | ctx->ctx_len = str_len; |
d28d1e08 TJ |
226 | ctx->ctx_alg = uctx->ctx_alg; |
227 | ||
228 | memcpy(ctx->ctx_str, | |
229 | uctx+1, | |
57002bfb SR |
230 | str_len); |
231 | ctx->ctx_str[str_len] = 0; | |
d28d1e08 | 232 | rc = security_context_to_sid(ctx->ctx_str, |
57002bfb | 233 | str_len, |
d28d1e08 TJ |
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 | */ | |
03e1ad7b PM |
286 | int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, |
287 | struct xfrm_user_sec_ctx *uctx) | |
d28d1e08 TJ |
288 | { |
289 | int err; | |
290 | ||
c1a856c9 | 291 | BUG_ON(!uctx); |
d28d1e08 | 292 | |
03e1ad7b | 293 | err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0); |
d621d35e PM |
294 | if (err == 0) |
295 | atomic_inc(&selinux_xfrm_refcount); | |
296 | ||
d28d1e08 TJ |
297 | return err; |
298 | } | |
299 | ||
300 | ||
301 | /* | |
302 | * LSM hook implementation that copies security data structure from old to | |
303 | * new for policy cloning. | |
304 | */ | |
03e1ad7b PM |
305 | int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx, |
306 | struct xfrm_sec_ctx **new_ctxp) | |
d28d1e08 | 307 | { |
03e1ad7b | 308 | struct xfrm_sec_ctx *new_ctx; |
d28d1e08 TJ |
309 | |
310 | if (old_ctx) { | |
03e1ad7b PM |
311 | new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len, |
312 | GFP_KERNEL); | |
d28d1e08 TJ |
313 | if (!new_ctx) |
314 | return -ENOMEM; | |
315 | ||
316 | memcpy(new_ctx, old_ctx, sizeof(*new_ctx)); | |
317 | memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len); | |
03e1ad7b | 318 | *new_ctxp = new_ctx; |
d28d1e08 TJ |
319 | } |
320 | return 0; | |
321 | } | |
322 | ||
323 | /* | |
03e1ad7b | 324 | * LSM hook implementation that frees xfrm_sec_ctx security information. |
d28d1e08 | 325 | */ |
03e1ad7b | 326 | void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx) |
d28d1e08 | 327 | { |
3c1c88ab | 328 | kfree(ctx); |
d28d1e08 TJ |
329 | } |
330 | ||
c8c05a8e CZ |
331 | /* |
332 | * LSM hook implementation that authorizes deletion of labeled policies. | |
333 | */ | |
03e1ad7b | 334 | int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx) |
c8c05a8e CZ |
335 | { |
336 | struct task_security_struct *tsec = current->security; | |
c8c05a8e CZ |
337 | int rc = 0; |
338 | ||
d621d35e | 339 | if (ctx) { |
c8c05a8e CZ |
340 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
341 | SECCLASS_ASSOCIATION, | |
342 | ASSOCIATION__SETCONTEXT, NULL); | |
d621d35e PM |
343 | if (rc == 0) |
344 | atomic_dec(&selinux_xfrm_refcount); | |
345 | } | |
c8c05a8e CZ |
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); |
d621d35e PM |
362 | if (err == 0) |
363 | atomic_inc(&selinux_xfrm_refcount); | |
d28d1e08 TJ |
364 | return err; |
365 | } | |
366 | ||
367 | /* | |
368 | * LSM hook implementation that frees xfrm_state security information. | |
369 | */ | |
370 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
371 | { | |
372 | struct xfrm_sec_ctx *ctx = x->security; | |
3c1c88ab | 373 | kfree(ctx); |
d28d1e08 TJ |
374 | } |
375 | ||
c8c05a8e CZ |
376 | /* |
377 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
378 | */ | |
379 | int selinux_xfrm_state_delete(struct xfrm_state *x) | |
380 | { | |
381 | struct task_security_struct *tsec = current->security; | |
382 | struct xfrm_sec_ctx *ctx = x->security; | |
383 | int rc = 0; | |
384 | ||
d621d35e | 385 | if (ctx) { |
c8c05a8e CZ |
386 | rc = avc_has_perm(tsec->sid, ctx->ctx_sid, |
387 | SECCLASS_ASSOCIATION, | |
388 | ASSOCIATION__SETCONTEXT, NULL); | |
d621d35e PM |
389 | if (rc == 0) |
390 | atomic_dec(&selinux_xfrm_refcount); | |
391 | } | |
c8c05a8e CZ |
392 | |
393 | return rc; | |
394 | } | |
395 | ||
d28d1e08 TJ |
396 | /* |
397 | * LSM hook that controls access to unlabelled packets. If | |
398 | * a xfrm_state is authorizable (defined by macro) then it was | |
399 | * already authorized by the IPSec process. If not, then | |
400 | * we need to check for unlabelled access since this may not have | |
401 | * gone thru the IPSec process. | |
402 | */ | |
e0d1caa7 VY |
403 | int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb, |
404 | struct avc_audit_data *ad) | |
d28d1e08 TJ |
405 | { |
406 | int i, rc = 0; | |
407 | struct sec_path *sp; | |
e0d1caa7 | 408 | u32 sel_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
409 | |
410 | sp = skb->sp; | |
411 | ||
412 | if (sp) { | |
d28d1e08 | 413 | for (i = 0; i < sp->len; i++) { |
67644726 | 414 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 415 | |
e0d1caa7 VY |
416 | if (x && selinux_authorizable_xfrm(x)) { |
417 | struct xfrm_sec_ctx *ctx = x->security; | |
418 | sel_sid = ctx->ctx_sid; | |
419 | break; | |
420 | } | |
d28d1e08 TJ |
421 | } |
422 | } | |
423 | ||
67f83cbf VY |
424 | /* |
425 | * This check even when there's no association involved is | |
426 | * intended, according to Trent Jaeger, to make sure a | |
427 | * process can't engage in non-ipsec communication unless | |
428 | * explicitly allowed by policy. | |
429 | */ | |
430 | ||
e0d1caa7 VY |
431 | rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION, |
432 | ASSOCIATION__RECVFROM, ad); | |
d28d1e08 | 433 | |
d28d1e08 TJ |
434 | return rc; |
435 | } | |
436 | ||
437 | /* | |
438 | * POSTROUTE_LAST hook's XFRM processing: | |
439 | * If we have no security association, then we need to determine | |
440 | * whether the socket is allowed to send to an unlabelled destination. | |
441 | * If we do have a authorizable security association, then it has already been | |
67f83cbf | 442 | * checked in the selinux_xfrm_state_pol_flow_match hook above. |
d28d1e08 | 443 | */ |
e0d1caa7 | 444 | int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb, |
67f83cbf | 445 | struct avc_audit_data *ad, u8 proto) |
d28d1e08 TJ |
446 | { |
447 | struct dst_entry *dst; | |
448 | int rc = 0; | |
449 | ||
450 | dst = skb->dst; | |
451 | ||
452 | if (dst) { | |
453 | struct dst_entry *dst_test; | |
454 | ||
c80544dc | 455 | for (dst_test = dst; dst_test != NULL; |
d28d1e08 TJ |
456 | dst_test = dst_test->child) { |
457 | struct xfrm_state *x = dst_test->xfrm; | |
458 | ||
459 | if (x && selinux_authorizable_xfrm(x)) | |
4e5ab4cb | 460 | goto out; |
d28d1e08 TJ |
461 | } |
462 | } | |
463 | ||
67f83cbf VY |
464 | switch (proto) { |
465 | case IPPROTO_AH: | |
466 | case IPPROTO_ESP: | |
467 | case IPPROTO_COMP: | |
468 | /* | |
469 | * We should have already seen this packet once before | |
470 | * it underwent xfrm(s). No need to subject it to the | |
471 | * unlabeled check. | |
472 | */ | |
473 | goto out; | |
474 | default: | |
475 | break; | |
476 | } | |
477 | ||
478 | /* | |
479 | * This check even when there's no association involved is | |
480 | * intended, according to Trent Jaeger, to make sure a | |
481 | * process can't engage in non-ipsec communication unless | |
482 | * explicitly allowed by policy. | |
483 | */ | |
484 | ||
d28d1e08 | 485 | rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION, |
e0d1caa7 | 486 | ASSOCIATION__SENDTO, ad); |
4e5ab4cb JM |
487 | out: |
488 | return rc; | |
d28d1e08 | 489 | } |