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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 __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(&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)
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_common *flic)
179{
180 u32 state_sid;
181 u32 flic_sid;
182
183 if (!xp->security)
184 if (x->security)
185 /* unlabeled policy and labeled SA can't match */
186 return 0;
187 else
188 /* unlabeled policy and unlabeled SA match all flows */
189 return 1;
190 else
191 if (!x->security)
192 /* unlabeled SA and labeled policy can't match */
193 return 0;
194 else
195 if (!selinux_authorizable_xfrm(x))
196 /* Not a SELinux-labeled SA */
197 return 0;
198
199 state_sid = x->security->ctx_sid;
200 flic_sid = flic->flowic_secid;
201
202 if (flic_sid != 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(&selinux_state, flic_sid, 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_sec_path(skb);
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 u32 str_len;
351
352 if (!polsec)
353 return 0;
354
355 if (secid == 0)
356 return -EINVAL;
357
358 rc = security_sid_to_context(&selinux_state, secid, &ctx_str,
359 &str_len);
360 if (rc)
361 return rc;
362
363 ctx = kmalloc(struct_size(ctx, ctx_str, str_len), GFP_ATOMIC);
364 if (!ctx) {
365 rc = -ENOMEM;
366 goto out;
367 }
368
369 ctx->ctx_doi = XFRM_SC_DOI_LSM;
370 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
371 ctx->ctx_sid = secid;
372 ctx->ctx_len = str_len;
373 memcpy(ctx->ctx_str, ctx_str, str_len);
374
375 x->security = ctx;
376 atomic_inc(&selinux_xfrm_refcount);
377out:
378 kfree(ctx_str);
379 return rc;
380}
381
382/*
383 * LSM hook implementation that frees xfrm_state security information.
384 */
385void selinux_xfrm_state_free(struct xfrm_state *x)
386{
387 selinux_xfrm_free(x->security);
388}
389
390/*
391 * LSM hook implementation that authorizes deletion of labeled SAs.
392 */
393int selinux_xfrm_state_delete(struct xfrm_state *x)
394{
395 return selinux_xfrm_delete(x->security);
396}
397
398/*
399 * LSM hook that controls access to unlabelled packets. If
400 * a xfrm_state is authorizable (defined by macro) then it was
401 * already authorized by the IPSec process. If not, then
402 * we need to check for unlabelled access since this may not have
403 * gone thru the IPSec process.
404 */
405int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
406 struct common_audit_data *ad)
407{
408 int i;
409 struct sec_path *sp = skb_sec_path(skb);
410 u32 peer_sid = SECINITSID_UNLABELED;
411
412 if (sp) {
413 for (i = 0; i < sp->len; i++) {
414 struct xfrm_state *x = sp->xvec[i];
415
416 if (x && selinux_authorizable_xfrm(x)) {
417 struct xfrm_sec_ctx *ctx = x->security;
418 peer_sid = ctx->ctx_sid;
419 break;
420 }
421 }
422 }
423
424 /* This check even when there's no association involved is intended,
425 * according to Trent Jaeger, to make sure a process can't engage in
426 * non-IPsec communication unless explicitly allowed by policy. */
427 return avc_has_perm(&selinux_state,
428 sk_sid, peer_sid,
429 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
430}
431
432/*
433 * POSTROUTE_LAST hook's XFRM processing:
434 * If we have no security association, then we need to determine
435 * whether the socket is allowed to send to an unlabelled destination.
436 * If we do have a authorizable security association, then it has already been
437 * checked in the selinux_xfrm_state_pol_flow_match hook above.
438 */
439int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
440 struct common_audit_data *ad, u8 proto)
441{
442 struct dst_entry *dst;
443
444 switch (proto) {
445 case IPPROTO_AH:
446 case IPPROTO_ESP:
447 case IPPROTO_COMP:
448 /* We should have already seen this packet once before it
449 * underwent xfrm(s). No need to subject it to the unlabeled
450 * check. */
451 return 0;
452 default:
453 break;
454 }
455
456 dst = skb_dst(skb);
457 if (dst) {
458 struct dst_entry *iter;
459
460 for (iter = dst; iter != NULL; iter = xfrm_dst_child(iter)) {
461 struct xfrm_state *x = iter->xfrm;
462
463 if (x && selinux_authorizable_xfrm(x))
464 return 0;
465 }
466 }
467
468 /* This check even when there's no association involved is intended,
469 * according to Trent Jaeger, to make sure a process can't engage in
470 * non-IPsec communication unless explicitly allowed by policy. */
471 return avc_has_perm(&selinux_state, sk_sid, SECINITSID_UNLABELED,
472 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
473}
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}