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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(&selinux_state, ctx->ctx_str, str_len,
105 &ctx->ctx_sid, gfp);
106 if (rc)
107 goto err;
108
109 rc = avc_has_perm(&selinux_state,
110 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
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(&selinux_state,
147 tsec->sid, ctx->ctx_sid,
148 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
149 NULL);
150}
151
152/*
153 * LSM hook implementation that authorizes that a flow can use a xfrm policy
154 * rule.
155 */
156int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
157{
158 int rc;
159
160 /* All flows should be treated as polmatch'ing an otherwise applicable
161 * "non-labeled" policy. This would prevent inadvertent "leaks". */
162 if (!ctx)
163 return 0;
164
165 /* Context sid is either set to label or ANY_ASSOC */
166 if (!selinux_authorizable_ctx(ctx))
167 return -EINVAL;
168
169 rc = avc_has_perm(&selinux_state,
170 fl_secid, ctx->ctx_sid,
171 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
172 return (rc == -EACCES ? -ESRCH : rc);
173}
174
175/*
176 * LSM hook implementation that authorizes that a state matches
177 * the given policy, flow combo.
178 */
179int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
180 struct xfrm_policy *xp,
181 const struct flowi *fl)
182{
183 u32 state_sid;
184
185 if (!xp->security)
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;
192 else
193 if (!x->security)
194 /* unlabeled SA and labeled policy can't match */
195 return 0;
196 else
197 if (!selinux_authorizable_xfrm(x))
198 /* Not a SELinux-labeled SA */
199 return 0;
200
201 state_sid = x->security->ctx_sid;
202
203 if (fl->flowi_secid != state_sid)
204 return 0;
205
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. */
209 return (avc_has_perm(&selinux_state,
210 fl->flowi_secid, state_sid,
211 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
212 NULL) ? 0 : 1);
213}
214
215static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
216{
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;
225
226 return x->security->ctx_sid;
227}
228
229static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
230 u32 *sid, int ckall)
231{
232 u32 sid_session = SECSID_NULL;
233 struct sec_path *sp = skb->sp;
234
235 if (sp) {
236 int i;
237
238 for (i = sp->len - 1; i >= 0; i--) {
239 struct xfrm_state *x = sp->xvec[i];
240 if (selinux_authorizable_xfrm(x)) {
241 struct xfrm_sec_ctx *ctx = x->security;
242
243 if (sid_session == SECSID_NULL) {
244 sid_session = ctx->ctx_sid;
245 if (!ckall)
246 goto out;
247 } else if (sid_session != ctx->ctx_sid) {
248 *sid = SECSID_NULL;
249 return -EINVAL;
250 }
251 }
252 }
253 }
254
255out:
256 *sid = sid_session;
257 return 0;
258}
259
260/*
261 * LSM hook implementation that checks and/or returns the xfrm sid for the
262 * incoming packet.
263 */
264int 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
273int 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
284/*
285 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
286 */
287int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
288 struct xfrm_user_sec_ctx *uctx,
289 gfp_t gfp)
290{
291 return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
292}
293
294/*
295 * LSM hook implementation that copies security data structure from old to new
296 * for policy cloning.
297 */
298int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
299 struct xfrm_sec_ctx **new_ctxp)
300{
301 struct xfrm_sec_ctx *new_ctx;
302
303 if (!old_ctx)
304 return 0;
305
306 new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
307 GFP_ATOMIC);
308 if (!new_ctx)
309 return -ENOMEM;
310 atomic_inc(&selinux_xfrm_refcount);
311 *new_ctxp = new_ctx;
312
313 return 0;
314}
315
316/*
317 * LSM hook implementation that frees xfrm_sec_ctx security information.
318 */
319void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
320{
321 selinux_xfrm_free(ctx);
322}
323
324/*
325 * LSM hook implementation that authorizes deletion of labeled policies.
326 */
327int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
328{
329 return selinux_xfrm_delete(ctx);
330}
331
332/*
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.
335 */
336int selinux_xfrm_state_alloc(struct xfrm_state *x,
337 struct xfrm_user_sec_ctx *uctx)
338{
339 return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
340}
341
342/*
343 * LSM hook implementation that allocates a xfrm_sec_state and populates based
344 * on a secid.
345 */
346int 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;
353
354 if (!polsec)
355 return 0;
356
357 if (secid == 0)
358 return -EINVAL;
359
360 rc = security_sid_to_context(&selinux_state, secid, &ctx_str,
361 &str_len);
362 if (rc)
363 return rc;
364
365 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
366 if (!ctx) {
367 rc = -ENOMEM;
368 goto out;
369 }
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);
376
377 x->security = ctx;
378 atomic_inc(&selinux_xfrm_refcount);
379out:
380 kfree(ctx_str);
381 return rc;
382}
383
384/*
385 * LSM hook implementation that frees xfrm_state security information.
386 */
387void selinux_xfrm_state_free(struct xfrm_state *x)
388{
389 selinux_xfrm_free(x->security);
390}
391
392/*
393 * LSM hook implementation that authorizes deletion of labeled SAs.
394 */
395int selinux_xfrm_state_delete(struct xfrm_state *x)
396{
397 return selinux_xfrm_delete(x->security);
398}
399
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 */
407int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
408 struct common_audit_data *ad)
409{
410 int i;
411 struct sec_path *sp = skb->sp;
412 u32 peer_sid = SECINITSID_UNLABELED;
413
414 if (sp) {
415 for (i = 0; i < sp->len; i++) {
416 struct xfrm_state *x = sp->xvec[i];
417
418 if (x && selinux_authorizable_xfrm(x)) {
419 struct xfrm_sec_ctx *ctx = x->security;
420 peer_sid = ctx->ctx_sid;
421 break;
422 }
423 }
424 }
425
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. */
429 return avc_has_perm(&selinux_state,
430 sk_sid, peer_sid,
431 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
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
439 * checked in the selinux_xfrm_state_pol_flow_match hook above.
440 */
441int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
442 struct common_audit_data *ad, u8 proto)
443{
444 struct dst_entry *dst;
445
446 switch (proto) {
447 case IPPROTO_AH:
448 case IPPROTO_ESP:
449 case IPPROTO_COMP:
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;
454 default:
455 break;
456 }
457
458 dst = skb_dst(skb);
459 if (dst) {
460 struct dst_entry *iter;
461
462 for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
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. */
473 return avc_has_perm(&selinux_state, sk_sid, SECINITSID_UNLABELED,
474 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
475}
1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * 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 __read_mostly = 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 struct xfrm_sec_ctx *ctx = NULL;
80 u32 str_len;
81
82 if (ctxp == NULL || uctx == NULL ||
83 uctx->ctx_doi != XFRM_SC_DOI_LSM ||
84 uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
85 return -EINVAL;
86
87 str_len = uctx->ctx_len;
88 if (str_len >= PAGE_SIZE)
89 return -ENOMEM;
90
91 ctx = kmalloc(struct_size(ctx, ctx_str, str_len + 1), gfp);
92 if (!ctx)
93 return -ENOMEM;
94
95 ctx->ctx_doi = XFRM_SC_DOI_LSM;
96 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
97 ctx->ctx_len = str_len;
98 memcpy(ctx->ctx_str, &uctx[1], str_len);
99 ctx->ctx_str[str_len] = '\0';
100 rc = security_context_to_sid(ctx->ctx_str, str_len,
101 &ctx->ctx_sid, gfp);
102 if (rc)
103 goto err;
104
105 rc = avc_has_perm(current_sid(), ctx->ctx_sid,
106 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
107 if (rc)
108 goto err;
109
110 *ctxp = ctx;
111 atomic_inc(&selinux_xfrm_refcount);
112 return 0;
113
114err:
115 kfree(ctx);
116 return rc;
117}
118
119/*
120 * Free the xfrm_sec_ctx structure.
121 */
122static void selinux_xfrm_free(struct xfrm_sec_ctx *ctx)
123{
124 if (!ctx)
125 return;
126
127 atomic_dec(&selinux_xfrm_refcount);
128 kfree(ctx);
129}
130
131/*
132 * Authorize the deletion of a labeled SA or policy rule.
133 */
134static int selinux_xfrm_delete(struct xfrm_sec_ctx *ctx)
135{
136 if (!ctx)
137 return 0;
138
139 return avc_has_perm(current_sid(), ctx->ctx_sid,
140 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
141 NULL);
142}
143
144/*
145 * LSM hook implementation that authorizes that a flow can use a xfrm policy
146 * rule.
147 */
148int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid)
149{
150 int rc;
151
152 /* All flows should be treated as polmatch'ing an otherwise applicable
153 * "non-labeled" policy. This would prevent inadvertent "leaks". */
154 if (!ctx)
155 return 0;
156
157 /* Context sid is either set to label or ANY_ASSOC */
158 if (!selinux_authorizable_ctx(ctx))
159 return -EINVAL;
160
161 rc = avc_has_perm(fl_secid, ctx->ctx_sid,
162 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
163 return (rc == -EACCES ? -ESRCH : rc);
164}
165
166/*
167 * LSM hook implementation that authorizes that a state matches
168 * the given policy, flow combo.
169 */
170int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
171 struct xfrm_policy *xp,
172 const struct flowi_common *flic)
173{
174 u32 state_sid;
175 u32 flic_sid;
176
177 if (!xp->security)
178 if (x->security)
179 /* unlabeled policy and labeled SA can't match */
180 return 0;
181 else
182 /* unlabeled policy and unlabeled SA match all flows */
183 return 1;
184 else
185 if (!x->security)
186 /* unlabeled SA and labeled policy can't match */
187 return 0;
188 else
189 if (!selinux_authorizable_xfrm(x))
190 /* Not a SELinux-labeled SA */
191 return 0;
192
193 state_sid = x->security->ctx_sid;
194 flic_sid = flic->flowic_secid;
195
196 if (flic_sid != state_sid)
197 return 0;
198
199 /* We don't need a separate SA Vs. policy polmatch check since the SA
200 * is now of the same label as the flow and a flow Vs. policy polmatch
201 * check had already happened in selinux_xfrm_policy_lookup() above. */
202 return (avc_has_perm(flic_sid, state_sid,
203 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
204 NULL) ? 0 : 1);
205}
206
207static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
208{
209 struct dst_entry *dst = skb_dst(skb);
210 struct xfrm_state *x;
211
212 if (dst == NULL)
213 return SECSID_NULL;
214 x = dst->xfrm;
215 if (x == NULL || !selinux_authorizable_xfrm(x))
216 return SECSID_NULL;
217
218 return x->security->ctx_sid;
219}
220
221static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
222 u32 *sid, int ckall)
223{
224 u32 sid_session = SECSID_NULL;
225 struct sec_path *sp = skb_sec_path(skb);
226
227 if (sp) {
228 int i;
229
230 for (i = sp->len - 1; i >= 0; i--) {
231 struct xfrm_state *x = sp->xvec[i];
232 if (selinux_authorizable_xfrm(x)) {
233 struct xfrm_sec_ctx *ctx = x->security;
234
235 if (sid_session == SECSID_NULL) {
236 sid_session = ctx->ctx_sid;
237 if (!ckall)
238 goto out;
239 } else if (sid_session != ctx->ctx_sid) {
240 *sid = SECSID_NULL;
241 return -EINVAL;
242 }
243 }
244 }
245 }
246
247out:
248 *sid = sid_session;
249 return 0;
250}
251
252/*
253 * LSM hook implementation that checks and/or returns the xfrm sid for the
254 * incoming packet.
255 */
256int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
257{
258 if (skb == NULL) {
259 *sid = SECSID_NULL;
260 return 0;
261 }
262 return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
263}
264
265int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
266{
267 int rc;
268
269 rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
270 if (rc == 0 && *sid == SECSID_NULL)
271 *sid = selinux_xfrm_skb_sid_egress(skb);
272
273 return rc;
274}
275
276/*
277 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
278 */
279int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
280 struct xfrm_user_sec_ctx *uctx,
281 gfp_t gfp)
282{
283 return selinux_xfrm_alloc_user(ctxp, uctx, gfp);
284}
285
286/*
287 * LSM hook implementation that copies security data structure from old to new
288 * for policy cloning.
289 */
290int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
291 struct xfrm_sec_ctx **new_ctxp)
292{
293 struct xfrm_sec_ctx *new_ctx;
294
295 if (!old_ctx)
296 return 0;
297
298 new_ctx = kmemdup(old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len,
299 GFP_ATOMIC);
300 if (!new_ctx)
301 return -ENOMEM;
302 atomic_inc(&selinux_xfrm_refcount);
303 *new_ctxp = new_ctx;
304
305 return 0;
306}
307
308/*
309 * LSM hook implementation that frees xfrm_sec_ctx security information.
310 */
311void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
312{
313 selinux_xfrm_free(ctx);
314}
315
316/*
317 * LSM hook implementation that authorizes deletion of labeled policies.
318 */
319int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
320{
321 return selinux_xfrm_delete(ctx);
322}
323
324/*
325 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
326 * the supplied security context, and assigns it to the xfrm_state.
327 */
328int selinux_xfrm_state_alloc(struct xfrm_state *x,
329 struct xfrm_user_sec_ctx *uctx)
330{
331 return selinux_xfrm_alloc_user(&x->security, uctx, GFP_KERNEL);
332}
333
334/*
335 * LSM hook implementation that allocates a xfrm_sec_state and populates based
336 * on a secid.
337 */
338int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
339 struct xfrm_sec_ctx *polsec, u32 secid)
340{
341 int rc;
342 struct xfrm_sec_ctx *ctx;
343 char *ctx_str = NULL;
344 u32 str_len;
345
346 if (!polsec)
347 return 0;
348
349 if (secid == 0)
350 return -EINVAL;
351
352 rc = security_sid_to_context(secid, &ctx_str,
353 &str_len);
354 if (rc)
355 return rc;
356
357 ctx = kmalloc(struct_size(ctx, ctx_str, str_len), GFP_ATOMIC);
358 if (!ctx) {
359 rc = -ENOMEM;
360 goto out;
361 }
362
363 ctx->ctx_doi = XFRM_SC_DOI_LSM;
364 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
365 ctx->ctx_sid = secid;
366 ctx->ctx_len = str_len;
367 memcpy(ctx->ctx_str, ctx_str, str_len);
368
369 x->security = ctx;
370 atomic_inc(&selinux_xfrm_refcount);
371out:
372 kfree(ctx_str);
373 return rc;
374}
375
376/*
377 * LSM hook implementation that frees xfrm_state security information.
378 */
379void selinux_xfrm_state_free(struct xfrm_state *x)
380{
381 selinux_xfrm_free(x->security);
382}
383
384/*
385 * LSM hook implementation that authorizes deletion of labeled SAs.
386 */
387int selinux_xfrm_state_delete(struct xfrm_state *x)
388{
389 return selinux_xfrm_delete(x->security);
390}
391
392/*
393 * LSM hook that controls access to unlabelled packets. If
394 * a xfrm_state is authorizable (defined by macro) then it was
395 * already authorized by the IPSec process. If not, then
396 * we need to check for unlabelled access since this may not have
397 * gone thru the IPSec process.
398 */
399int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
400 struct common_audit_data *ad)
401{
402 int i;
403 struct sec_path *sp = skb_sec_path(skb);
404 u32 peer_sid = SECINITSID_UNLABELED;
405
406 if (sp) {
407 for (i = 0; i < sp->len; i++) {
408 struct xfrm_state *x = sp->xvec[i];
409
410 if (x && selinux_authorizable_xfrm(x)) {
411 struct xfrm_sec_ctx *ctx = x->security;
412 peer_sid = ctx->ctx_sid;
413 break;
414 }
415 }
416 }
417
418 /* This check even when there's no association involved is intended,
419 * according to Trent Jaeger, to make sure a process can't engage in
420 * non-IPsec communication unless explicitly allowed by policy. */
421 return avc_has_perm(sk_sid, peer_sid,
422 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
423}
424
425/*
426 * POSTROUTE_LAST hook's XFRM processing:
427 * If we have no security association, then we need to determine
428 * whether the socket is allowed to send to an unlabelled destination.
429 * If we do have a authorizable security association, then it has already been
430 * checked in the selinux_xfrm_state_pol_flow_match hook above.
431 */
432int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
433 struct common_audit_data *ad, u8 proto)
434{
435 struct dst_entry *dst;
436
437 switch (proto) {
438 case IPPROTO_AH:
439 case IPPROTO_ESP:
440 case IPPROTO_COMP:
441 /* We should have already seen this packet once before it
442 * underwent xfrm(s). No need to subject it to the unlabeled
443 * check. */
444 return 0;
445 default:
446 break;
447 }
448
449 dst = skb_dst(skb);
450 if (dst) {
451 struct dst_entry *iter;
452
453 for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
454 struct xfrm_state *x = iter->xfrm;
455
456 if (x && selinux_authorizable_xfrm(x))
457 return 0;
458 }
459 }
460
461 /* This check even when there's no association involved is intended,
462 * according to Trent Jaeger, to make sure a process can't engage in
463 * non-IPsec communication unless explicitly allowed by policy. */
464 return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
465 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
466}