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