Merge branch 'linus' into core/locking
[linux-2.6-block.git] / security / selinux / xfrm.c
CommitLineData
d28d1e08
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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
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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
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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
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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>
5a0e3ad6 41#include <linux/slab.h>
d28d1e08
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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>
60063497 49#include <linux/atomic.h>
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50
51#include "avc.h"
52#include "objsec.h"
53#include "xfrm.h"
54
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55/* Labeled XFRM instance counter */
56atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
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57
58/*
4baabeec 59 * Returns true if the context is an LSM/SELinux context.
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60 */
61static 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/*
4baabeec 69 * Returns true if the xfrm contains a security blob for SELinux.
d28d1e08
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70 */
71static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
72{
73 return selinux_authorizable_ctx(x->security);
74}
75
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76/*
77 * Allocates a xfrm_sec_state and populates it using the supplied security
78 * xfrm_user_sec_ctx context.
79 */
80static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
81 struct xfrm_user_sec_ctx *uctx)
82{
83 int rc;
84 const struct task_security_struct *tsec = current_security();
85 struct xfrm_sec_ctx *ctx = NULL;
86 u32 str_len;
87
88 if (ctxp == NULL || uctx == NULL ||
89 uctx->ctx_doi != XFRM_SC_DOI_LSM ||
90 uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
91 return -EINVAL;
92
93 str_len = uctx->ctx_len;
94 if (str_len >= PAGE_SIZE)
95 return -ENOMEM;
96
97 ctx = kmalloc(sizeof(*ctx) + str_len + 1, GFP_KERNEL);
98 if (!ctx)
99 return -ENOMEM;
100
101 ctx->ctx_doi = XFRM_SC_DOI_LSM;
102 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
103 ctx->ctx_len = str_len;
104 memcpy(ctx->ctx_str, &uctx[1], str_len);
105 ctx->ctx_str[str_len] = '\0';
106 rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid);
107 if (rc)
108 goto err;
109
110 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
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
119err:
120 kfree(ctx);
121 return rc;
122}
123
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124/*
125 * Free the xfrm_sec_ctx structure.
126 */
127static 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 */
139static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
140{
141 const struct task_security_struct *tsec = current_security();
142
143 if (!ctx)
144 return 0;
145
146 return avc_has_perm(tsec->sid, ctx->ctx_sid,
147 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
148 NULL);
149}
150
d28d1e08 151/*
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152 * LSM hook implementation that authorizes that a flow can use a xfrm policy
153 * rule.
d28d1e08 154 */
03e1ad7b 155int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
d28d1e08 156{
5b368e61 157 int rc;
d28d1e08 158
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159 /* All flows should be treated as polmatch'ing an otherwise applicable
160 * "non-labeled" policy. This would prevent inadvertent "leaks". */
161 if (!ctx)
5b368e61 162 return 0;
d28d1e08 163
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164 /* Context sid is either set to label or ANY_ASSOC */
165 if (!selinux_authorizable_ctx(ctx))
166 return -EINVAL;
5b368e61 167
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168 rc = avc_has_perm(fl_secid, ctx->ctx_sid,
169 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
170 return (rc == -EACCES ? -ESRCH : rc);
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171}
172
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173/*
174 * LSM hook implementation that authorizes that a state matches
175 * the given policy, flow combo.
176 */
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177int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
178 struct xfrm_policy *xp,
179 const struct flowi *fl)
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180{
181 u32 state_sid;
e0d1caa7 182
67f83cbf 183 if (!xp->security)
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184 if (x->security)
185 /* unlabeled policy and labeled SA can't match */
186 return 0;
187 else
188 /* unlabeled policy and unlabeled SA match all flows */
189 return 1;
5b368e61 190 else
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191 if (!x->security)
192 /* unlabeled SA and labeled policy can't match */
5b368e61 193 return 0;
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194 else
195 if (!selinux_authorizable_xfrm(x))
196 /* Not a SELinux-labeled SA */
197 return 0;
5b368e61 198
67f83cbf 199 state_sid = x->security->ctx_sid;
e0d1caa7 200
1d28f42c 201 if (fl->flowi_secid != state_sid)
67f83cbf 202 return 0;
e0d1caa7 203
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204 /* We don't need a separate SA Vs. policy polmatch check since the SA
205 * is now of the same label as the flow and a flow Vs. policy polmatch
206 * check had already happened in selinux_xfrm_policy_lookup() above. */
207 return (avc_has_perm(fl->flowi_secid, state_sid,
208 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
209 NULL) ? 0 : 1);
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210}
211
817eff71 212static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
e0d1caa7 213{
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214 struct dst_entry *dst = skb_dst(skb);
215 struct xfrm_state *x;
216
217 if (dst == NULL)
218 return SECSID_NULL;
219 x = dst->xfrm;
220 if (x == NULL || !selinux_authorizable_xfrm(x))
221 return SECSID_NULL;
e0d1caa7 222
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223 return x->security->ctx_sid;
224}
225
226static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
227 u32 *sid, int ckall)
228{
229 u32 sid_session = SECSID_NULL;
230 struct sec_path *sp = skb->sp;
e0d1caa7 231
e0d1caa7 232 if (sp) {
e2193695 233 int i;
e0d1caa7 234
e2193695 235 for (i = sp->len - 1; i >= 0; i--) {
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236 struct xfrm_state *x = sp->xvec[i];
237 if (selinux_authorizable_xfrm(x)) {
238 struct xfrm_sec_ctx *ctx = x->security;
239
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240 if (sid_session == SECSID_NULL) {
241 sid_session = ctx->ctx_sid;
beb8d13b 242 if (!ckall)
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243 goto out;
244 } else if (sid_session != ctx->ctx_sid) {
245 *sid = SECSID_NULL;
e0d1caa7 246 return -EINVAL;
e2193695 247 }
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248 }
249 }
250 }
251
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252out:
253 *sid = sid_session;
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254 return 0;
255}
256
817eff71
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257/*
258 * LSM hook implementation that checks and/or returns the xfrm sid for the
259 * incoming packet.
260 */
261int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
262{
263 if (skb == NULL) {
264 *sid = SECSID_NULL;
265 return 0;
266 }
267 return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
268}
269
270int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
271{
272 int rc;
273
274 rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
275 if (rc == 0 && *sid == SECSID_NULL)
276 *sid = selinux_xfrm_skb_sid_egress(skb);
277
278 return rc;
279}
280
d28d1e08 281/*
4baabeec 282 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
d28d1e08 283 */
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284int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
285 struct xfrm_user_sec_ctx *uctx)
d28d1e08 286{
2e5aa866 287 return selinux_xfrm_alloc_user(ctxp, uctx);
d28d1e08
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288}
289
d28d1e08 290/*
4baabeec
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291 * LSM hook implementation that copies security data structure from old to new
292 * for policy cloning.
d28d1e08 293 */
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294int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
295 struct xfrm_sec_ctx **new_ctxp)
d28d1e08 296{
03e1ad7b 297 struct xfrm_sec_ctx *new_ctx;
d28d1e08 298
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299 if (!old_ctx)
300 return 0;
301
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302 new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
303 GFP_ATOMIC);
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304 if (!new_ctx)
305 return -ENOMEM;
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306 atomic_inc(&selinux_xfrm_refcount);
307 *new_ctxp = new_ctx;
d28d1e08 308
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309 return 0;
310}
311
312/*
03e1ad7b 313 * LSM hook implementation that frees xfrm_sec_ctx security information.
d28d1e08 314 */
03e1ad7b 315void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
d28d1e08 316{
ccf17cc4 317 selinux_xfrm_free(ctx);
d28d1e08
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318}
319
c8c05a8e
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320/*
321 * LSM hook implementation that authorizes deletion of labeled policies.
322 */
03e1ad7b 323int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
c8c05a8e 324{
ccf17cc4 325 return selinux_xfrm_delete(ctx);
c8c05a8e
CZ
326}
327
d28d1e08 328/*
2e5aa866
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329 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
330 * the supplied security context, and assigns it to the xfrm_state.
d28d1e08 331 */
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332int selinux_xfrm_state_alloc(struct xfrm_state *x,
333 struct xfrm_user_sec_ctx *uctx)
d28d1e08 334{
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335 return selinux_xfrm_alloc_user(&x->security, uctx);
336}
d28d1e08 337
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338/*
339 * LSM hook implementation that allocates a xfrm_sec_state and populates based
340 * on a secid.
341 */
342int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
343 struct xfrm_sec_ctx *polsec, u32 secid)
344{
345 int rc;
346 struct xfrm_sec_ctx *ctx;
347 char *ctx_str = NULL;
348 int str_len;
d28d1e08 349
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350 if (!polsec)
351 return 0;
352
353 if (secid == 0)
354 return -EINVAL;
355
356 rc = security_sid_to_context(secid, &ctx_str, &str_len);
357 if (rc)
358 return rc;
359
360 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
0af90164
GB
361 if (!ctx) {
362 rc = -ENOMEM;
363 goto out;
364 }
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365
366 ctx->ctx_doi = XFRM_SC_DOI_LSM;
367 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
368 ctx->ctx_sid = secid;
369 ctx->ctx_len = str_len;
370 memcpy(ctx->ctx_str, ctx_str, str_len);
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371
372 x->security = ctx;
373 atomic_inc(&selinux_xfrm_refcount);
0af90164
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374out:
375 kfree(ctx_str);
376 return rc;
d28d1e08
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377}
378
379/*
380 * LSM hook implementation that frees xfrm_state security information.
381 */
382void selinux_xfrm_state_free(struct xfrm_state *x)
383{
ccf17cc4 384 selinux_xfrm_free(x->security);
d28d1e08
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385}
386
4baabeec
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387/*
388 * LSM hook implementation that authorizes deletion of labeled SAs.
389 */
c8c05a8e
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390int selinux_xfrm_state_delete(struct xfrm_state *x)
391{
ccf17cc4 392 return selinux_xfrm_delete(x->security);
c8c05a8e
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393}
394
d28d1e08
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395/*
396 * LSM hook that controls access to unlabelled packets. If
397 * a xfrm_state is authorizable (defined by macro) then it was
398 * already authorized by the IPSec process. If not, then
399 * we need to check for unlabelled access since this may not have
400 * gone thru the IPSec process.
401 */
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402int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
403 struct common_audit_data *ad)
d28d1e08 404{
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405 int i;
406 struct sec_path *sp = skb->sp;
407 u32 peer_sid = SECINITSID_UNLABELED;
d28d1e08
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408
409 if (sp) {
d28d1e08 410 for (i = 0; i < sp->len; i++) {
67644726 411 struct xfrm_state *x = sp->xvec[i];
d28d1e08 412
e0d1caa7
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413 if (x && selinux_authorizable_xfrm(x)) {
414 struct xfrm_sec_ctx *ctx = x->security;
eef9b416 415 peer_sid = ctx->ctx_sid;
e0d1caa7
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416 break;
417 }
d28d1e08
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418 }
419 }
420
eef9b416
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421 /* This check even when there's no association involved is intended,
422 * according to Trent Jaeger, to make sure a process can't engage in
423 * non-IPsec communication unless explicitly allowed by policy. */
424 return avc_has_perm(sk_sid, peer_sid,
425 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
d28d1e08
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426}
427
428/*
429 * POSTROUTE_LAST hook's XFRM processing:
430 * If we have no security association, then we need to determine
431 * whether the socket is allowed to send to an unlabelled destination.
432 * If we do have a authorizable security association, then it has already been
67f83cbf 433 * checked in the selinux_xfrm_state_pol_flow_match hook above.
d28d1e08 434 */
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435int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
436 struct common_audit_data *ad, u8 proto)
d28d1e08
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437{
438 struct dst_entry *dst;
d28d1e08 439
67f83cbf
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440 switch (proto) {
441 case IPPROTO_AH:
442 case IPPROTO_ESP:
443 case IPPROTO_COMP:
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444 /* We should have already seen this packet once before it
445 * underwent xfrm(s). No need to subject it to the unlabeled
446 * check. */
447 return 0;
67f83cbf
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448 default:
449 break;
450 }
451
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452 dst = skb_dst(skb);
453 if (dst) {
454 struct dst_entry *iter;
67f83cbf 455
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456 for (iter = dst; iter != NULL; iter = iter->child) {
457 struct xfrm_state *x = iter->xfrm;
458
459 if (x && selinux_authorizable_xfrm(x))
460 return 0;
461 }
462 }
463
464 /* This check even when there's no association involved is intended,
465 * according to Trent Jaeger, to make sure a process can't engage in
466 * non-IPsec communication unless explicitly allowed by policy. */
467 return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
468 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
d28d1e08 469}