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> | |
5a0e3ad6 | 38 | #include <linux/slab.h> |
d28d1e08 TJ |
39 | #include <linux/ip.h> |
40 | #include <linux/tcp.h> | |
41 | #include <linux/skbuff.h> | |
42 | #include <linux/xfrm.h> | |
43 | #include <net/xfrm.h> | |
44 | #include <net/checksum.h> | |
45 | #include <net/udp.h> | |
60063497 | 46 | #include <linux/atomic.h> |
d28d1e08 TJ |
47 | |
48 | #include "avc.h" | |
49 | #include "objsec.h" | |
50 | #include "xfrm.h" | |
51 | ||
d621d35e PM |
52 | /* Labeled XFRM instance counter */ |
53 | atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0); | |
d28d1e08 TJ |
54 | |
55 | /* | |
4baabeec | 56 | * Returns true if the context is an LSM/SELinux context. |
d28d1e08 TJ |
57 | */ |
58 | static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx) | |
59 | { | |
60 | return (ctx && | |
61 | (ctx->ctx_doi == XFRM_SC_DOI_LSM) && | |
62 | (ctx->ctx_alg == XFRM_SC_ALG_SELINUX)); | |
63 | } | |
64 | ||
65 | /* | |
4baabeec | 66 | * Returns true if the xfrm contains a security blob for SELinux. |
d28d1e08 TJ |
67 | */ |
68 | static inline int selinux_authorizable_xfrm(struct xfrm_state *x) | |
69 | { | |
70 | return selinux_authorizable_ctx(x->security); | |
71 | } | |
72 | ||
2e5aa866 PM |
73 | /* |
74 | * Allocates a xfrm_sec_state and populates it using the supplied security | |
75 | * xfrm_user_sec_ctx context. | |
76 | */ | |
77 | static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp, | |
52a4c640 NA |
78 | struct xfrm_user_sec_ctx *uctx, |
79 | gfp_t gfp) | |
2e5aa866 PM |
80 | { |
81 | int rc; | |
0c6cfa62 | 82 | const struct task_security_struct *tsec = selinux_cred(current_cred()); |
2e5aa866 PM |
83 | struct xfrm_sec_ctx *ctx = NULL; |
84 | u32 str_len; | |
85 | ||
86 | if (ctxp == NULL || uctx == NULL || | |
87 | uctx->ctx_doi != XFRM_SC_DOI_LSM || | |
88 | uctx->ctx_alg != XFRM_SC_ALG_SELINUX) | |
89 | return -EINVAL; | |
90 | ||
91 | str_len = uctx->ctx_len; | |
92 | if (str_len >= PAGE_SIZE) | |
93 | return -ENOMEM; | |
94 | ||
52a4c640 | 95 | ctx = kmalloc(sizeof(*ctx) + str_len + 1, gfp); |
2e5aa866 PM |
96 | if (!ctx) |
97 | return -ENOMEM; | |
98 | ||
99 | ctx->ctx_doi = XFRM_SC_DOI_LSM; | |
100 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
101 | ctx->ctx_len = str_len; | |
102 | memcpy(ctx->ctx_str, &uctx[1], str_len); | |
103 | ctx->ctx_str[str_len] = '\0'; | |
aa8e712c SS |
104 | rc = security_context_to_sid(&selinux_state, ctx->ctx_str, str_len, |
105 | &ctx->ctx_sid, gfp); | |
2e5aa866 PM |
106 | if (rc) |
107 | goto err; | |
108 | ||
6b6bc620 SS |
109 | rc = avc_has_perm(&selinux_state, |
110 | tsec->sid, ctx->ctx_sid, | |
2e5aa866 PM |
111 | SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL); |
112 | if (rc) | |
113 | goto err; | |
114 | ||
115 | *ctxp = ctx; | |
116 | atomic_inc(&selinux_xfrm_refcount); | |
117 | return 0; | |
118 | ||
119 | err: | |
120 | kfree(ctx); | |
121 | return rc; | |
122 | } | |
123 | ||
ccf17cc4 PM |
124 | /* |
125 | * Free the xfrm_sec_ctx structure. | |
126 | */ | |
127 | static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx) | |
128 | { | |
129 | if (!ctx) | |
130 | return; | |
131 | ||
132 | atomic_dec(&selinux_xfrm_refcount); | |
133 | kfree(ctx); | |
134 | } | |
135 | ||
136 | /* | |
137 | * Authorize the deletion of a labeled SA or policy rule. | |
138 | */ | |
139 | static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx) | |
140 | { | |
0c6cfa62 | 141 | const struct task_security_struct *tsec = selinux_cred(current_cred()); |
ccf17cc4 PM |
142 | |
143 | if (!ctx) | |
144 | return 0; | |
145 | ||
6b6bc620 SS |
146 | return avc_has_perm(&selinux_state, |
147 | tsec->sid, ctx->ctx_sid, | |
ccf17cc4 PM |
148 | SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, |
149 | NULL); | |
150 | } | |
151 | ||
d28d1e08 | 152 | /* |
4baabeec PM |
153 | * LSM hook implementation that authorizes that a flow can use a xfrm policy |
154 | * rule. | |
d28d1e08 | 155 | */ |
03e1ad7b | 156 | int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir) |
d28d1e08 | 157 | { |
5b368e61 | 158 | int rc; |
d28d1e08 | 159 | |
96484348 PM |
160 | /* All flows should be treated as polmatch'ing an otherwise applicable |
161 | * "non-labeled" policy. This would prevent inadvertent "leaks". */ | |
162 | if (!ctx) | |
5b368e61 | 163 | return 0; |
d28d1e08 | 164 | |
96484348 PM |
165 | /* Context sid is either set to label or ANY_ASSOC */ |
166 | if (!selinux_authorizable_ctx(ctx)) | |
167 | return -EINVAL; | |
5b368e61 | 168 | |
6b6bc620 SS |
169 | rc = avc_has_perm(&selinux_state, |
170 | fl_secid, ctx->ctx_sid, | |
96484348 PM |
171 | SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL); |
172 | return (rc == -EACCES ? -ESRCH : rc); | |
d28d1e08 TJ |
173 | } |
174 | ||
e0d1caa7 VY |
175 | /* |
176 | * LSM hook implementation that authorizes that a state matches | |
177 | * the given policy, flow combo. | |
178 | */ | |
96484348 PM |
179 | int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, |
180 | struct xfrm_policy *xp, | |
181 | const struct flowi *fl) | |
e0d1caa7 VY |
182 | { |
183 | u32 state_sid; | |
e0d1caa7 | 184 | |
67f83cbf | 185 | if (!xp->security) |
5b368e61 VY |
186 | if (x->security) |
187 | /* unlabeled policy and labeled SA can't match */ | |
188 | return 0; | |
189 | else | |
190 | /* unlabeled policy and unlabeled SA match all flows */ | |
191 | return 1; | |
5b368e61 | 192 | else |
67f83cbf VY |
193 | if (!x->security) |
194 | /* unlabeled SA and labeled policy can't match */ | |
5b368e61 | 195 | return 0; |
67f83cbf VY |
196 | else |
197 | if (!selinux_authorizable_xfrm(x)) | |
198 | /* Not a SELinux-labeled SA */ | |
199 | return 0; | |
5b368e61 | 200 | |
67f83cbf | 201 | state_sid = x->security->ctx_sid; |
e0d1caa7 | 202 | |
1d28f42c | 203 | if (fl->flowi_secid != state_sid) |
67f83cbf | 204 | return 0; |
e0d1caa7 | 205 | |
96484348 PM |
206 | /* We don't need a separate SA Vs. policy polmatch check since the SA |
207 | * is now of the same label as the flow and a flow Vs. policy polmatch | |
208 | * check had already happened in selinux_xfrm_policy_lookup() above. */ | |
6b6bc620 SS |
209 | return (avc_has_perm(&selinux_state, |
210 | fl->flowi_secid, state_sid, | |
96484348 PM |
211 | SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, |
212 | NULL) ? 0 : 1); | |
e0d1caa7 VY |
213 | } |
214 | ||
817eff71 | 215 | static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb) |
e0d1caa7 | 216 | { |
817eff71 PM |
217 | struct dst_entry *dst = skb_dst(skb); |
218 | struct xfrm_state *x; | |
219 | ||
220 | if (dst == NULL) | |
221 | return SECSID_NULL; | |
222 | x = dst->xfrm; | |
223 | if (x == NULL || !selinux_authorizable_xfrm(x)) | |
224 | return SECSID_NULL; | |
e0d1caa7 | 225 | |
817eff71 PM |
226 | return x->security->ctx_sid; |
227 | } | |
228 | ||
229 | static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb, | |
230 | u32 *sid, int ckall) | |
231 | { | |
232 | u32 sid_session = SECSID_NULL; | |
2294be0f | 233 | struct sec_path *sp = skb_sec_path(skb); |
e0d1caa7 | 234 | |
e0d1caa7 | 235 | if (sp) { |
e2193695 | 236 | int i; |
e0d1caa7 | 237 | |
e2193695 | 238 | for (i = sp->len - 1; i >= 0; i--) { |
e0d1caa7 VY |
239 | struct xfrm_state *x = sp->xvec[i]; |
240 | if (selinux_authorizable_xfrm(x)) { | |
241 | struct xfrm_sec_ctx *ctx = x->security; | |
242 | ||
e2193695 PM |
243 | if (sid_session == SECSID_NULL) { |
244 | sid_session = ctx->ctx_sid; | |
beb8d13b | 245 | if (!ckall) |
e2193695 PM |
246 | goto out; |
247 | } else if (sid_session != ctx->ctx_sid) { | |
248 | *sid = SECSID_NULL; | |
e0d1caa7 | 249 | return -EINVAL; |
e2193695 | 250 | } |
e0d1caa7 VY |
251 | } |
252 | } | |
253 | } | |
254 | ||
e2193695 PM |
255 | out: |
256 | *sid = sid_session; | |
e0d1caa7 VY |
257 | return 0; |
258 | } | |
259 | ||
817eff71 PM |
260 | /* |
261 | * LSM hook implementation that checks and/or returns the xfrm sid for the | |
262 | * incoming packet. | |
263 | */ | |
264 | int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall) | |
265 | { | |
266 | if (skb == NULL) { | |
267 | *sid = SECSID_NULL; | |
268 | return 0; | |
269 | } | |
270 | return selinux_xfrm_skb_sid_ingress(skb, sid, ckall); | |
271 | } | |
272 | ||
273 | int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid) | |
274 | { | |
275 | int rc; | |
276 | ||
277 | rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0); | |
278 | if (rc == 0 && *sid == SECSID_NULL) | |
279 | *sid = selinux_xfrm_skb_sid_egress(skb); | |
280 | ||
281 | return rc; | |
282 | } | |
283 | ||
d28d1e08 | 284 | /* |
4baabeec | 285 | * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy. |
d28d1e08 | 286 | */ |
03e1ad7b | 287 | int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp, |
52a4c640 NA |
288 | struct xfrm_user_sec_ctx *uctx, |
289 | gfp_t gfp) | |
d28d1e08 | 290 | { |
52a4c640 | 291 | return selinux_xfrm_alloc_user(ctxp, uctx, gfp); |
d28d1e08 TJ |
292 | } |
293 | ||
d28d1e08 | 294 | /* |
4baabeec PM |
295 | * LSM hook implementation that copies security data structure from old to new |
296 | * for policy cloning. | |
d28d1e08 | 297 | */ |
03e1ad7b PM |
298 | int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx, |
299 | struct xfrm_sec_ctx **new_ctxp) | |
d28d1e08 | 300 | { |
03e1ad7b | 301 | struct xfrm_sec_ctx *new_ctx; |
d28d1e08 | 302 | |
ccf17cc4 PM |
303 | if (!old_ctx) |
304 | return 0; | |
305 | ||
7d1db4b2 DJ |
306 | new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len, |
307 | GFP_ATOMIC); | |
ccf17cc4 PM |
308 | if (!new_ctx) |
309 | return -ENOMEM; | |
ccf17cc4 PM |
310 | atomic_inc(&selinux_xfrm_refcount); |
311 | *new_ctxp = new_ctx; | |
d28d1e08 | 312 | |
d28d1e08 TJ |
313 | return 0; |
314 | } | |
315 | ||
316 | /* | |
03e1ad7b | 317 | * LSM hook implementation that frees xfrm_sec_ctx security information. |
d28d1e08 | 318 | */ |
03e1ad7b | 319 | void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx) |
d28d1e08 | 320 | { |
ccf17cc4 | 321 | selinux_xfrm_free(ctx); |
d28d1e08 TJ |
322 | } |
323 | ||
c8c05a8e CZ |
324 | /* |
325 | * LSM hook implementation that authorizes deletion of labeled policies. | |
326 | */ | |
03e1ad7b | 327 | int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx) |
c8c05a8e | 328 | { |
ccf17cc4 | 329 | return selinux_xfrm_delete(ctx); |
c8c05a8e CZ |
330 | } |
331 | ||
d28d1e08 | 332 | /* |
2e5aa866 PM |
333 | * LSM hook implementation that allocates a xfrm_sec_state, populates it using |
334 | * the supplied security context, and assigns it to the xfrm_state. | |
d28d1e08 | 335 | */ |
2e5aa866 PM |
336 | int selinux_xfrm_state_alloc(struct xfrm_state *x, |
337 | struct xfrm_user_sec_ctx *uctx) | |
d28d1e08 | 338 | { |
52a4c640 | 339 | return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL); |
2e5aa866 | 340 | } |
d28d1e08 | 341 | |
2e5aa866 PM |
342 | /* |
343 | * LSM hook implementation that allocates a xfrm_sec_state and populates based | |
344 | * on a secid. | |
345 | */ | |
346 | int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x, | |
347 | struct xfrm_sec_ctx *polsec, u32 secid) | |
348 | { | |
349 | int rc; | |
350 | struct xfrm_sec_ctx *ctx; | |
351 | char *ctx_str = NULL; | |
352 | int str_len; | |
d28d1e08 | 353 | |
2e5aa866 PM |
354 | if (!polsec) |
355 | return 0; | |
356 | ||
357 | if (secid == 0) | |
358 | return -EINVAL; | |
359 | ||
aa8e712c SS |
360 | rc = security_sid_to_context(&selinux_state, secid, &ctx_str, |
361 | &str_len); | |
2e5aa866 PM |
362 | if (rc) |
363 | return rc; | |
364 | ||
365 | ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC); | |
0af90164 GB |
366 | if (!ctx) { |
367 | rc = -ENOMEM; | |
368 | goto out; | |
369 | } | |
2e5aa866 PM |
370 | |
371 | ctx->ctx_doi = XFRM_SC_DOI_LSM; | |
372 | ctx->ctx_alg = XFRM_SC_ALG_SELINUX; | |
373 | ctx->ctx_sid = secid; | |
374 | ctx->ctx_len = str_len; | |
375 | memcpy(ctx->ctx_str, ctx_str, str_len); | |
2e5aa866 PM |
376 | |
377 | x->security = ctx; | |
378 | atomic_inc(&selinux_xfrm_refcount); | |
0af90164 GB |
379 | out: |
380 | kfree(ctx_str); | |
381 | return rc; | |
d28d1e08 TJ |
382 | } |
383 | ||
384 | /* | |
385 | * LSM hook implementation that frees xfrm_state security information. | |
386 | */ | |
387 | void selinux_xfrm_state_free(struct xfrm_state *x) | |
388 | { | |
ccf17cc4 | 389 | selinux_xfrm_free(x->security); |
d28d1e08 TJ |
390 | } |
391 | ||
4baabeec PM |
392 | /* |
393 | * LSM hook implementation that authorizes deletion of labeled SAs. | |
394 | */ | |
c8c05a8e CZ |
395 | int selinux_xfrm_state_delete(struct xfrm_state *x) |
396 | { | |
ccf17cc4 | 397 | return selinux_xfrm_delete(x->security); |
c8c05a8e CZ |
398 | } |
399 | ||
d28d1e08 TJ |
400 | /* |
401 | * LSM hook that controls access to unlabelled packets. If | |
402 | * a xfrm_state is authorizable (defined by macro) then it was | |
403 | * already authorized by the IPSec process. If not, then | |
404 | * we need to check for unlabelled access since this may not have | |
405 | * gone thru the IPSec process. | |
406 | */ | |
eef9b416 PM |
407 | int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb, |
408 | struct common_audit_data *ad) | |
d28d1e08 | 409 | { |
eef9b416 | 410 | int i; |
2294be0f | 411 | struct sec_path *sp = skb_sec_path(skb); |
eef9b416 | 412 | u32 peer_sid = SECINITSID_UNLABELED; |
d28d1e08 TJ |
413 | |
414 | if (sp) { | |
d28d1e08 | 415 | for (i = 0; i < sp->len; i++) { |
67644726 | 416 | struct xfrm_state *x = sp->xvec[i]; |
d28d1e08 | 417 | |
e0d1caa7 VY |
418 | if (x && selinux_authorizable_xfrm(x)) { |
419 | struct xfrm_sec_ctx *ctx = x->security; | |
eef9b416 | 420 | peer_sid = ctx->ctx_sid; |
e0d1caa7 VY |
421 | break; |
422 | } | |
d28d1e08 TJ |
423 | } |
424 | } | |
425 | ||
eef9b416 PM |
426 | /* This check even when there's no association involved is intended, |
427 | * according to Trent Jaeger, to make sure a process can't engage in | |
428 | * non-IPsec communication unless explicitly allowed by policy. */ | |
6b6bc620 SS |
429 | return avc_has_perm(&selinux_state, |
430 | sk_sid, peer_sid, | |
eef9b416 | 431 | SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad); |
d28d1e08 TJ |
432 | } |
433 | ||
434 | /* | |
435 | * POSTROUTE_LAST hook's XFRM processing: | |
436 | * If we have no security association, then we need to determine | |
437 | * whether the socket is allowed to send to an unlabelled destination. | |
438 | * If we do have a authorizable security association, then it has already been | |
67f83cbf | 439 | * checked in the selinux_xfrm_state_pol_flow_match hook above. |
d28d1e08 | 440 | */ |
eef9b416 PM |
441 | int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb, |
442 | struct common_audit_data *ad, u8 proto) | |
d28d1e08 TJ |
443 | { |
444 | struct dst_entry *dst; | |
d28d1e08 | 445 | |
67f83cbf VY |
446 | switch (proto) { |
447 | case IPPROTO_AH: | |
448 | case IPPROTO_ESP: | |
449 | case IPPROTO_COMP: | |
eef9b416 PM |
450 | /* We should have already seen this packet once before it |
451 | * underwent xfrm(s). No need to subject it to the unlabeled | |
452 | * check. */ | |
453 | return 0; | |
67f83cbf VY |
454 | default: |
455 | break; | |
456 | } | |
457 | ||
eef9b416 PM |
458 | dst = skb_dst(skb); |
459 | if (dst) { | |
460 | struct dst_entry *iter; | |
67f83cbf | 461 | |
b92cf4aa | 462 | for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) { |
eef9b416 PM |
463 | struct xfrm_state *x = iter->xfrm; |
464 | ||
465 | if (x && selinux_authorizable_xfrm(x)) | |
466 | return 0; | |
467 | } | |
468 | } | |
469 | ||
470 | /* This check even when there's no association involved is intended, | |
471 | * according to Trent Jaeger, to make sure a process can't engage in | |
472 | * non-IPsec communication unless explicitly allowed by policy. */ | |
6b6bc620 | 473 | return avc_has_perm(&selinux_state, sk_sid, SECINITSID_UNLABELED, |
eef9b416 | 474 | SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad); |
d28d1e08 | 475 | } |