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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// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * NSA Security-Enhanced Linux (SELinux) security module
4 *
5 * This file contains the SELinux XFRM hook function implementations.
6 *
7 * Authors: Serge Hallyn <sergeh@us.ibm.com>
8 * Trent Jaeger <jaegert@us.ibm.com>
9 *
10 * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
11 *
12 * Granular IPSec Associations for use in MLS environments.
13 *
14 * Copyright (C) 2005 International Business Machines Corporation
15 * Copyright (C) 2006 Trusted Computer Solutions, Inc.
16 */
17
18/*
19 * USAGE:
20 * NOTES:
21 * 1. Make sure to enable the following options in your kernel config:
22 * CONFIG_SECURITY=y
23 * CONFIG_SECURITY_NETWORK=y
24 * CONFIG_SECURITY_NETWORK_XFRM=y
25 * CONFIG_SECURITY_SELINUX=m/y
26 * ISSUES:
27 * 1. Caching packets, so they are not dropped during negotiation
28 * 2. Emulating a reasonable SO_PEERSEC across machines
29 * 3. Testing addition of sk_policy's with security context via setsockopt
30 */
31#include <linux/kernel.h>
32#include <linux/init.h>
33#include <linux/security.h>
34#include <linux/types.h>
35#include <linux/slab.h>
36#include <linux/ip.h>
37#include <linux/tcp.h>
38#include <linux/skbuff.h>
39#include <linux/xfrm.h>
40#include <net/xfrm.h>
41#include <net/checksum.h>
42#include <net/udp.h>
43#include <linux/atomic.h>
44
45#include "avc.h"
46#include "objsec.h"
47#include "xfrm.h"
48
49/* Labeled XFRM instance counter */
50atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
51
52/*
53 * Returns true if the context is an LSM/SELinux context.
54 */
55static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
56{
57 return (ctx &&
58 (ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
59 (ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
60}
61
62/*
63 * Returns true if the xfrm contains a security blob for SELinux.
64 */
65static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
66{
67 return selinux_authorizable_ctx(x->security);
68}
69
70/*
71 * Allocates a xfrm_sec_state and populates it using the supplied security
72 * xfrm_user_sec_ctx context.
73 */
74static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
75 struct xfrm_user_sec_ctx *uctx,
76 gfp_t gfp)
77{
78 int rc;
79 const struct task_security_struct *tsec = selinux_cred(current_cred());
80 struct xfrm_sec_ctx *ctx = NULL;
81 u32 str_len;
82
83 if (ctxp == NULL || uctx == NULL ||
84 uctx->ctx_doi != XFRM_SC_DOI_LSM ||
85 uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
86 return -EINVAL;
87
88 str_len = uctx->ctx_len;
89 if (str_len >= PAGE_SIZE)
90 return -ENOMEM;
91
92 ctx = kmalloc(sizeof(*ctx) + str_len + 1, gfp);
93 if (!ctx)
94 return -ENOMEM;
95
96 ctx->ctx_doi = XFRM_SC_DOI_LSM;
97 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
98 ctx->ctx_len = str_len;
99 memcpy(ctx->ctx_str, &uctx[1], str_len);
100 ctx->ctx_str[str_len] = '\0';
101 rc = security_context_to_sid(&selinux_state, ctx->ctx_str, str_len,
102 &ctx->ctx_sid, gfp);
103 if (rc)
104 goto err;
105
106 rc = avc_has_perm(&selinux_state,
107 tsec->sid, ctx->ctx_sid,
108 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
109 if (rc)
110 goto err;
111
112 *ctxp = ctx;
113 atomic_inc(&selinux_xfrm_refcount);
114 return 0;
115
116err:
117 kfree(ctx);
118 return rc;
119}
120
121/*
122 * Free the xfrm_sec_ctx structure.
123 */
124static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
125{
126 if (!ctx)
127 return;
128
129 atomic_dec(&selinux_xfrm_refcount);
130 kfree(ctx);
131}
132
133/*
134 * Authorize the deletion of a labeled SA or policy rule.
135 */
136static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
137{
138 const struct task_security_struct *tsec = selinux_cred(current_cred());
139
140 if (!ctx)
141 return 0;
142
143 return avc_has_perm(&selinux_state,
144 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(&selinux_state,
167 fl_secid, ctx->ctx_sid,
168 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
169 return (rc == -EACCES ? -ESRCH : rc);
170}
171
172/*
173 * LSM hook implementation that authorizes that a state matches
174 * the given policy, flow combo.
175 */
176int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
177 struct xfrm_policy *xp,
178 const struct flowi *fl)
179{
180 u32 state_sid;
181
182 if (!xp->security)
183 if (x->security)
184 /* unlabeled policy and labeled SA can't match */
185 return 0;
186 else
187 /* unlabeled policy and unlabeled SA match all flows */
188 return 1;
189 else
190 if (!x->security)
191 /* unlabeled SA and labeled policy can't match */
192 return 0;
193 else
194 if (!selinux_authorizable_xfrm(x))
195 /* Not a SELinux-labeled SA */
196 return 0;
197
198 state_sid = x->security->ctx_sid;
199
200 if (fl->flowi_secid != state_sid)
201 return 0;
202
203 /* We don't need a separate SA Vs. policy polmatch check since the SA
204 * is now of the same label as the flow and a flow Vs. policy polmatch
205 * check had already happened in selinux_xfrm_policy_lookup() above. */
206 return (avc_has_perm(&selinux_state,
207 fl->flowi_secid, state_sid,
208 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
209 NULL) ? 0 : 1);
210}
211
212static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
213{
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;
222
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_sec_path(skb);
231
232 if (sp) {
233 int i;
234
235 for (i = sp->len - 1; i >= 0; i--) {
236 struct xfrm_state *x = sp->xvec[i];
237 if (selinux_authorizable_xfrm(x)) {
238 struct xfrm_sec_ctx *ctx = x->security;
239
240 if (sid_session == SECSID_NULL) {
241 sid_session = ctx->ctx_sid;
242 if (!ckall)
243 goto out;
244 } else if (sid_session != ctx->ctx_sid) {
245 *sid = SECSID_NULL;
246 return -EINVAL;
247 }
248 }
249 }
250 }
251
252out:
253 *sid = sid_session;
254 return 0;
255}
256
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
281/*
282 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
283 */
284int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
285 struct xfrm_user_sec_ctx *uctx,
286 gfp_t gfp)
287{
288 return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
289}
290
291/*
292 * LSM hook implementation that copies security data structure from old to new
293 * for policy cloning.
294 */
295int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
296 struct xfrm_sec_ctx **new_ctxp)
297{
298 struct xfrm_sec_ctx *new_ctx;
299
300 if (!old_ctx)
301 return 0;
302
303 new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
304 GFP_ATOMIC);
305 if (!new_ctx)
306 return -ENOMEM;
307 atomic_inc(&selinux_xfrm_refcount);
308 *new_ctxp = new_ctx;
309
310 return 0;
311}
312
313/*
314 * LSM hook implementation that frees xfrm_sec_ctx security information.
315 */
316void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
317{
318 selinux_xfrm_free(ctx);
319}
320
321/*
322 * LSM hook implementation that authorizes deletion of labeled policies.
323 */
324int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
325{
326 return selinux_xfrm_delete(ctx);
327}
328
329/*
330 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
331 * the supplied security context, and assigns it to the xfrm_state.
332 */
333int selinux_xfrm_state_alloc(struct xfrm_state *x,
334 struct xfrm_user_sec_ctx *uctx)
335{
336 return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
337}
338
339/*
340 * LSM hook implementation that allocates a xfrm_sec_state and populates based
341 * on a secid.
342 */
343int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
344 struct xfrm_sec_ctx *polsec, u32 secid)
345{
346 int rc;
347 struct xfrm_sec_ctx *ctx;
348 char *ctx_str = NULL;
349 int str_len;
350
351 if (!polsec)
352 return 0;
353
354 if (secid == 0)
355 return -EINVAL;
356
357 rc = security_sid_to_context(&selinux_state, secid, &ctx_str,
358 &str_len);
359 if (rc)
360 return rc;
361
362 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
363 if (!ctx) {
364 rc = -ENOMEM;
365 goto out;
366 }
367
368 ctx->ctx_doi = XFRM_SC_DOI_LSM;
369 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
370 ctx->ctx_sid = secid;
371 ctx->ctx_len = str_len;
372 memcpy(ctx->ctx_str, ctx_str, str_len);
373
374 x->security = ctx;
375 atomic_inc(&selinux_xfrm_refcount);
376out:
377 kfree(ctx_str);
378 return rc;
379}
380
381/*
382 * LSM hook implementation that frees xfrm_state security information.
383 */
384void selinux_xfrm_state_free(struct xfrm_state *x)
385{
386 selinux_xfrm_free(x->security);
387}
388
389/*
390 * LSM hook implementation that authorizes deletion of labeled SAs.
391 */
392int selinux_xfrm_state_delete(struct xfrm_state *x)
393{
394 return selinux_xfrm_delete(x->security);
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 sk_sid, struct sk_buff *skb,
405 struct common_audit_data *ad)
406{
407 int i;
408 struct sec_path *sp = skb_sec_path(skb);
409 u32 peer_sid = SECINITSID_UNLABELED;
410
411 if (sp) {
412 for (i = 0; i < sp->len; i++) {
413 struct xfrm_state *x = sp->xvec[i];
414
415 if (x && selinux_authorizable_xfrm(x)) {
416 struct xfrm_sec_ctx *ctx = x->security;
417 peer_sid = ctx->ctx_sid;
418 break;
419 }
420 }
421 }
422
423 /* This check even when there's no association involved is intended,
424 * according to Trent Jaeger, to make sure a process can't engage in
425 * non-IPsec communication unless explicitly allowed by policy. */
426 return avc_has_perm(&selinux_state,
427 sk_sid, peer_sid,
428 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
429}
430
431/*
432 * POSTROUTE_LAST hook's XFRM processing:
433 * If we have no security association, then we need to determine
434 * whether the socket is allowed to send to an unlabelled destination.
435 * If we do have a authorizable security association, then it has already been
436 * checked in the selinux_xfrm_state_pol_flow_match hook above.
437 */
438int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
439 struct common_audit_data *ad, u8 proto)
440{
441 struct dst_entry *dst;
442
443 switch (proto) {
444 case IPPROTO_AH:
445 case IPPROTO_ESP:
446 case IPPROTO_COMP:
447 /* We should have already seen this packet once before it
448 * underwent xfrm(s). No need to subject it to the unlabeled
449 * check. */
450 return 0;
451 default:
452 break;
453 }
454
455 dst = skb_dst(skb);
456 if (dst) {
457 struct dst_entry *iter;
458
459 for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
460 struct xfrm_state *x = iter->xfrm;
461
462 if (x && selinux_authorizable_xfrm(x))
463 return 0;
464 }
465 }
466
467 /* This check even when there's no association involved is intended,
468 * according to Trent Jaeger, to make sure a process can't engage in
469 * non-IPsec communication unless explicitly allowed by policy. */
470 return avc_has_perm(&selinux_state, sk_sid, SECINITSID_UNLABELED,
471 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
472}