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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 *
9 * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
10 *
11 * Granular IPSec Associations for use in MLS environments.
12 *
13 * Copyright (C) 2005 International Business Machines Corporation
14 * Copyright (C) 2006 Trusted Computer Solutions, Inc.
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 */
34#include <linux/kernel.h>
35#include <linux/init.h>
36#include <linux/security.h>
37#include <linux/types.h>
38#include <linux/slab.h>
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>
46#include <linux/atomic.h>
47
48#include "avc.h"
49#include "objsec.h"
50#include "xfrm.h"
51
52/* Labeled XFRM instance counter */
53atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
54
55/*
56 * Returns true if the context is an LSM/SELinux context.
57 */
58static 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/*
66 * Returns true if the xfrm contains a security blob for SELinux.
67 */
68static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
69{
70 return selinux_authorizable_ctx(x->security);
71}
72
73/*
74 * Allocates a xfrm_sec_state and populates it using the supplied security
75 * xfrm_user_sec_ctx context.
76 */
77static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
78 struct xfrm_user_sec_ctx *uctx,
79 gfp_t gfp)
80{
81 int rc;
82 const struct task_security_struct *tsec = current_security();
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
95 ctx = kmalloc(sizeof(*ctx) + str_len + 1, gfp);
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';
104 rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid, gfp);
105 if (rc)
106 goto err;
107
108 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
109 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
110 if (rc)
111 goto err;
112
113 *ctxp = ctx;
114 atomic_inc(&selinux_xfrm_refcount);
115 return 0;
116
117err:
118 kfree(ctx);
119 return rc;
120}
121
122/*
123 * Free the xfrm_sec_ctx structure.
124 */
125static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
126{
127 if (!ctx)
128 return;
129
130 atomic_dec(&selinux_xfrm_refcount);
131 kfree(ctx);
132}
133
134/*
135 * Authorize the deletion of a labeled SA or policy rule.
136 */
137static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
138{
139 const struct task_security_struct *tsec = current_security();
140
141 if (!ctx)
142 return 0;
143
144 return avc_has_perm(tsec->sid, ctx->ctx_sid,
145 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
146 NULL);
147}
148
149/*
150 * LSM hook implementation that authorizes that a flow can use a xfrm policy
151 * rule.
152 */
153int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
154{
155 int rc;
156
157 /* All flows should be treated as polmatch'ing an otherwise applicable
158 * "non-labeled" policy. This would prevent inadvertent "leaks". */
159 if (!ctx)
160 return 0;
161
162 /* Context sid is either set to label or ANY_ASSOC */
163 if (!selinux_authorizable_ctx(ctx))
164 return -EINVAL;
165
166 rc = avc_has_perm(fl_secid, ctx->ctx_sid,
167 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
168 return (rc == -EACCES ? -ESRCH : rc);
169}
170
171/*
172 * LSM hook implementation that authorizes that a state matches
173 * the given policy, flow combo.
174 */
175int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
176 struct xfrm_policy *xp,
177 const struct flowi *fl)
178{
179 u32 state_sid;
180
181 if (!xp->security)
182 if (x->security)
183 /* unlabeled policy and labeled SA can't match */
184 return 0;
185 else
186 /* unlabeled policy and unlabeled SA match all flows */
187 return 1;
188 else
189 if (!x->security)
190 /* unlabeled SA and labeled policy can't match */
191 return 0;
192 else
193 if (!selinux_authorizable_xfrm(x))
194 /* Not a SELinux-labeled SA */
195 return 0;
196
197 state_sid = x->security->ctx_sid;
198
199 if (fl->flowi_secid != state_sid)
200 return 0;
201
202 /* We don't need a separate SA Vs. policy polmatch check since the SA
203 * is now of the same label as the flow and a flow Vs. policy polmatch
204 * check had already happened in selinux_xfrm_policy_lookup() above. */
205 return (avc_has_perm(fl->flowi_secid, state_sid,
206 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
207 NULL) ? 0 : 1);
208}
209
210static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
211{
212 struct dst_entry *dst = skb_dst(skb);
213 struct xfrm_state *x;
214
215 if (dst == NULL)
216 return SECSID_NULL;
217 x = dst->xfrm;
218 if (x == NULL || !selinux_authorizable_xfrm(x))
219 return SECSID_NULL;
220
221 return x->security->ctx_sid;
222}
223
224static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
225 u32 *sid, int ckall)
226{
227 u32 sid_session = SECSID_NULL;
228 struct sec_path *sp = skb->sp;
229
230 if (sp) {
231 int i;
232
233 for (i = sp->len - 1; i >= 0; i--) {
234 struct xfrm_state *x = sp->xvec[i];
235 if (selinux_authorizable_xfrm(x)) {
236 struct xfrm_sec_ctx *ctx = x->security;
237
238 if (sid_session == SECSID_NULL) {
239 sid_session = ctx->ctx_sid;
240 if (!ckall)
241 goto out;
242 } else if (sid_session != ctx->ctx_sid) {
243 *sid = SECSID_NULL;
244 return -EINVAL;
245 }
246 }
247 }
248 }
249
250out:
251 *sid = sid_session;
252 return 0;
253}
254
255/*
256 * LSM hook implementation that checks and/or returns the xfrm sid for the
257 * incoming packet.
258 */
259int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
260{
261 if (skb == NULL) {
262 *sid = SECSID_NULL;
263 return 0;
264 }
265 return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
266}
267
268int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
269{
270 int rc;
271
272 rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
273 if (rc == 0 && *sid == SECSID_NULL)
274 *sid = selinux_xfrm_skb_sid_egress(skb);
275
276 return rc;
277}
278
279/*
280 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
281 */
282int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
283 struct xfrm_user_sec_ctx *uctx,
284 gfp_t gfp)
285{
286 return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
287}
288
289/*
290 * LSM hook implementation that copies security data structure from old to new
291 * for policy cloning.
292 */
293int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
294 struct xfrm_sec_ctx **new_ctxp)
295{
296 struct xfrm_sec_ctx *new_ctx;
297
298 if (!old_ctx)
299 return 0;
300
301 new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
302 GFP_ATOMIC);
303 if (!new_ctx)
304 return -ENOMEM;
305 atomic_inc(&selinux_xfrm_refcount);
306 *new_ctxp = new_ctx;
307
308 return 0;
309}
310
311/*
312 * LSM hook implementation that frees xfrm_sec_ctx security information.
313 */
314void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
315{
316 selinux_xfrm_free(ctx);
317}
318
319/*
320 * LSM hook implementation that authorizes deletion of labeled policies.
321 */
322int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
323{
324 return selinux_xfrm_delete(ctx);
325}
326
327/*
328 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
329 * the supplied security context, and assigns it to the xfrm_state.
330 */
331int selinux_xfrm_state_alloc(struct xfrm_state *x,
332 struct xfrm_user_sec_ctx *uctx)
333{
334 return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
335}
336
337/*
338 * LSM hook implementation that allocates a xfrm_sec_state and populates based
339 * on a secid.
340 */
341int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
342 struct xfrm_sec_ctx *polsec, u32 secid)
343{
344 int rc;
345 struct xfrm_sec_ctx *ctx;
346 char *ctx_str = NULL;
347 int str_len;
348
349 if (!polsec)
350 return 0;
351
352 if (secid == 0)
353 return -EINVAL;
354
355 rc = security_sid_to_context(secid, &ctx_str, &str_len);
356 if (rc)
357 return rc;
358
359 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
360 if (!ctx) {
361 rc = -ENOMEM;
362 goto out;
363 }
364
365 ctx->ctx_doi = XFRM_SC_DOI_LSM;
366 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
367 ctx->ctx_sid = secid;
368 ctx->ctx_len = str_len;
369 memcpy(ctx->ctx_str, ctx_str, str_len);
370
371 x->security = ctx;
372 atomic_inc(&selinux_xfrm_refcount);
373out:
374 kfree(ctx_str);
375 return rc;
376}
377
378/*
379 * LSM hook implementation that frees xfrm_state security information.
380 */
381void selinux_xfrm_state_free(struct xfrm_state *x)
382{
383 selinux_xfrm_free(x->security);
384}
385
386/*
387 * LSM hook implementation that authorizes deletion of labeled SAs.
388 */
389int selinux_xfrm_state_delete(struct xfrm_state *x)
390{
391 return selinux_xfrm_delete(x->security);
392}
393
394/*
395 * LSM hook that controls access to unlabelled packets. If
396 * a xfrm_state is authorizable (defined by macro) then it was
397 * already authorized by the IPSec process. If not, then
398 * we need to check for unlabelled access since this may not have
399 * gone thru the IPSec process.
400 */
401int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
402 struct common_audit_data *ad)
403{
404 int i;
405 struct sec_path *sp = skb->sp;
406 u32 peer_sid = SECINITSID_UNLABELED;
407
408 if (sp) {
409 for (i = 0; i < sp->len; i++) {
410 struct xfrm_state *x = sp->xvec[i];
411
412 if (x && selinux_authorizable_xfrm(x)) {
413 struct xfrm_sec_ctx *ctx = x->security;
414 peer_sid = ctx->ctx_sid;
415 break;
416 }
417 }
418 }
419
420 /* This check even when there's no association involved is intended,
421 * according to Trent Jaeger, to make sure a process can't engage in
422 * non-IPsec communication unless explicitly allowed by policy. */
423 return avc_has_perm(sk_sid, peer_sid,
424 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
425}
426
427/*
428 * POSTROUTE_LAST hook's XFRM processing:
429 * If we have no security association, then we need to determine
430 * whether the socket is allowed to send to an unlabelled destination.
431 * If we do have a authorizable security association, then it has already been
432 * checked in the selinux_xfrm_state_pol_flow_match hook above.
433 */
434int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
435 struct common_audit_data *ad, u8 proto)
436{
437 struct dst_entry *dst;
438
439 switch (proto) {
440 case IPPROTO_AH:
441 case IPPROTO_ESP:
442 case IPPROTO_COMP:
443 /* We should have already seen this packet once before it
444 * underwent xfrm(s). No need to subject it to the unlabeled
445 * check. */
446 return 0;
447 default:
448 break;
449 }
450
451 dst = skb_dst(skb);
452 if (dst) {
453 struct dst_entry *iter;
454
455 for (iter = dst; iter != NULL; iter = iter->child) {
456 struct xfrm_state *x = iter->xfrm;
457
458 if (x && selinux_authorizable_xfrm(x))
459 return 0;
460 }
461 }
462
463 /* This check even when there's no association involved is intended,
464 * according to Trent Jaeger, to make sure a process can't engage in
465 * non-IPsec communication unless explicitly allowed by policy. */
466 return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
467 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
468}
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 *
9 * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
10 *
11 * Granular IPSec Associations for use in MLS environments.
12 *
13 * Copyright (C) 2005 International Business Machines Corporation
14 * Copyright (C) 2006 Trusted Computer Solutions, Inc.
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 */
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/slab.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 <linux/atomic.h>
50
51#include "avc.h"
52#include "objsec.h"
53#include "xfrm.h"
54
55/* Labeled XFRM instance counter */
56atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
57
58/*
59 * Returns true if an LSM/SELinux context
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/*
69 * Returns true if the xfrm contains a security blob for SELinux
70 */
71static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
72{
73 return selinux_authorizable_ctx(x->security);
74}
75
76/*
77 * LSM hook implementation that authorizes that a flow can use
78 * a xfrm policy rule.
79 */
80int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
81{
82 int rc;
83 u32 sel_sid;
84
85 /* Context sid is either set to label or ANY_ASSOC */
86 if (ctx) {
87 if (!selinux_authorizable_ctx(ctx))
88 return -EINVAL;
89
90 sel_sid = ctx->ctx_sid;
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;
98
99 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
100 ASSOCIATION__POLMATCH,
101 NULL);
102
103 if (rc == -EACCES)
104 return -ESRCH;
105
106 return rc;
107}
108
109/*
110 * LSM hook implementation that authorizes that a state matches
111 * the given policy, flow combo.
112 */
113
114int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp,
115 const struct flowi *fl)
116{
117 u32 state_sid;
118 int rc;
119
120 if (!xp->security)
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;
127 else
128 if (!x->security)
129 /* unlabeled SA and labeled policy can't match */
130 return 0;
131 else
132 if (!selinux_authorizable_xfrm(x))
133 /* Not a SELinux-labeled SA */
134 return 0;
135
136 state_sid = x->security->ctx_sid;
137
138 if (fl->flowi_secid != state_sid)
139 return 0;
140
141 rc = avc_has_perm(fl->flowi_secid, state_sid, SECCLASS_ASSOCIATION,
142 ASSOCIATION__SENDTO,
143 NULL)? 0:1;
144
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
152 return rc;
153}
154
155/*
156 * LSM hook implementation that checks and/or returns the xfrm sid for the
157 * incoming packet.
158 */
159
160int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
161{
162 struct sec_path *sp;
163
164 *sid = SECSID_NULL;
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) {
179 *sid = ctx->ctx_sid;
180 sid_set = 1;
181
182 if (!ckall)
183 break;
184 } else if (*sid != ctx->ctx_sid)
185 return -EINVAL;
186 }
187 }
188 }
189
190 return 0;
191}
192
193/*
194 * Security blob allocation for xfrm_policy and xfrm_state
195 * CTX does not have a meaningful value on input
196 */
197static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
198 struct xfrm_user_sec_ctx *uctx, u32 sid)
199{
200 int rc = 0;
201 const struct task_security_struct *tsec = current_security();
202 struct xfrm_sec_ctx *ctx = NULL;
203 char *ctx_str = NULL;
204 u32 str_len;
205
206 BUG_ON(uctx && sid);
207
208 if (!uctx)
209 goto not_from_user;
210
211 if (uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
212 return -EINVAL;
213
214 str_len = uctx->ctx_len;
215 if (str_len >= PAGE_SIZE)
216 return -ENOMEM;
217
218 *ctxp = ctx = kmalloc(sizeof(*ctx) +
219 str_len + 1,
220 GFP_KERNEL);
221
222 if (!ctx)
223 return -ENOMEM;
224
225 ctx->ctx_doi = uctx->ctx_doi;
226 ctx->ctx_len = str_len;
227 ctx->ctx_alg = uctx->ctx_alg;
228
229 memcpy(ctx->ctx_str,
230 uctx+1,
231 str_len);
232 ctx->ctx_str[str_len] = 0;
233 rc = security_context_to_sid(ctx->ctx_str,
234 str_len,
235 &ctx->ctx_sid);
236
237 if (rc)
238 goto out;
239
240 /*
241 * Does the subject have permission to set security context?
242 */
243 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
244 SECCLASS_ASSOCIATION,
245 ASSOCIATION__SETCONTEXT, NULL);
246 if (rc)
247 goto out;
248
249 return rc;
250
251not_from_user:
252 rc = security_sid_to_context(sid, &ctx_str, &str_len);
253 if (rc)
254 goto out;
255
256 *ctxp = ctx = kmalloc(sizeof(*ctx) +
257 str_len,
258 GFP_ATOMIC);
259
260 if (!ctx) {
261 rc = -ENOMEM;
262 goto out;
263 }
264
265 ctx->ctx_doi = XFRM_SC_DOI_LSM;
266 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
267 ctx->ctx_sid = sid;
268 ctx->ctx_len = str_len;
269 memcpy(ctx->ctx_str,
270 ctx_str,
271 str_len);
272
273 goto out2;
274
275out:
276 *ctxp = NULL;
277 kfree(ctx);
278out2:
279 kfree(ctx_str);
280 return rc;
281}
282
283/*
284 * LSM hook implementation that allocs and transfers uctx spec to
285 * xfrm_policy.
286 */
287int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
288 struct xfrm_user_sec_ctx *uctx)
289{
290 int err;
291
292 BUG_ON(!uctx);
293
294 err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0);
295 if (err == 0)
296 atomic_inc(&selinux_xfrm_refcount);
297
298 return err;
299}
300
301
302/*
303 * LSM hook implementation that copies security data structure from old to
304 * new for policy cloning.
305 */
306int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
307 struct xfrm_sec_ctx **new_ctxp)
308{
309 struct xfrm_sec_ctx *new_ctx;
310
311 if (old_ctx) {
312 new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len,
313 GFP_KERNEL);
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 *new_ctxp = new_ctx;
320 }
321 return 0;
322}
323
324/*
325 * LSM hook implementation that frees xfrm_sec_ctx security information.
326 */
327void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
328{
329 kfree(ctx);
330}
331
332/*
333 * LSM hook implementation that authorizes deletion of labeled policies.
334 */
335int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
336{
337 const struct task_security_struct *tsec = current_security();
338 int rc = 0;
339
340 if (ctx) {
341 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
342 SECCLASS_ASSOCIATION,
343 ASSOCIATION__SETCONTEXT, NULL);
344 if (rc == 0)
345 atomic_dec(&selinux_xfrm_refcount);
346 }
347
348 return rc;
349}
350
351/*
352 * LSM hook implementation that allocs and transfers sec_ctx spec to
353 * xfrm_state.
354 */
355int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
356 u32 secid)
357{
358 int err;
359
360 BUG_ON(!x);
361
362 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
363 if (err == 0)
364 atomic_inc(&selinux_xfrm_refcount);
365 return err;
366}
367
368/*
369 * LSM hook implementation that frees xfrm_state security information.
370 */
371void selinux_xfrm_state_free(struct xfrm_state *x)
372{
373 struct xfrm_sec_ctx *ctx = x->security;
374 kfree(ctx);
375}
376
377 /*
378 * LSM hook implementation that authorizes deletion of labeled SAs.
379 */
380int selinux_xfrm_state_delete(struct xfrm_state *x)
381{
382 const struct task_security_struct *tsec = current_security();
383 struct xfrm_sec_ctx *ctx = x->security;
384 int rc = 0;
385
386 if (ctx) {
387 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
388 SECCLASS_ASSOCIATION,
389 ASSOCIATION__SETCONTEXT, NULL);
390 if (rc == 0)
391 atomic_dec(&selinux_xfrm_refcount);
392 }
393
394 return rc;
395}
396
397/*
398 * LSM hook that controls access to unlabelled packets. If
399 * a xfrm_state is authorizable (defined by macro) then it was
400 * already authorized by the IPSec process. If not, then
401 * we need to check for unlabelled access since this may not have
402 * gone thru the IPSec process.
403 */
404int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
405 struct common_audit_data *ad)
406{
407 int i, rc = 0;
408 struct sec_path *sp;
409 u32 sel_sid = SECINITSID_UNLABELED;
410
411 sp = skb->sp;
412
413 if (sp) {
414 for (i = 0; i < sp->len; i++) {
415 struct xfrm_state *x = sp->xvec[i];
416
417 if (x && selinux_authorizable_xfrm(x)) {
418 struct xfrm_sec_ctx *ctx = x->security;
419 sel_sid = ctx->ctx_sid;
420 break;
421 }
422 }
423 }
424
425 /*
426 * This check even when there's no association involved is
427 * intended, according to Trent Jaeger, to make sure a
428 * process can't engage in non-ipsec communication unless
429 * explicitly allowed by policy.
430 */
431
432 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
433 ASSOCIATION__RECVFROM, ad);
434
435 return rc;
436}
437
438/*
439 * POSTROUTE_LAST hook's XFRM processing:
440 * If we have no security association, then we need to determine
441 * whether the socket is allowed to send to an unlabelled destination.
442 * If we do have a authorizable security association, then it has already been
443 * checked in the selinux_xfrm_state_pol_flow_match hook above.
444 */
445int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
446 struct common_audit_data *ad, u8 proto)
447{
448 struct dst_entry *dst;
449 int rc = 0;
450
451 dst = skb_dst(skb);
452
453 if (dst) {
454 struct dst_entry *dst_test;
455
456 for (dst_test = dst; dst_test != NULL;
457 dst_test = dst_test->child) {
458 struct xfrm_state *x = dst_test->xfrm;
459
460 if (x && selinux_authorizable_xfrm(x))
461 goto out;
462 }
463 }
464
465 switch (proto) {
466 case IPPROTO_AH:
467 case IPPROTO_ESP:
468 case IPPROTO_COMP:
469 /*
470 * We should have already seen this packet once before
471 * it underwent xfrm(s). No need to subject it to the
472 * unlabeled check.
473 */
474 goto out;
475 default:
476 break;
477 }
478
479 /*
480 * This check even when there's no association involved is
481 * intended, according to Trent Jaeger, to make sure a
482 * process can't engage in non-ipsec communication unless
483 * explicitly allowed by policy.
484 */
485
486 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
487 ASSOCIATION__SENDTO, ad);
488out:
489 return rc;
490}