blob: 425b9f91d755f6aa229f9bc71c58a747d0f9fa98 [file] [log] [blame]
Trent Jaegerd28d1e02005-12-13 23:12:40 -08001/*
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 *
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -07009 * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
10 *
11 * Granular IPSec Associations for use in MLS environments.
12 *
Trent Jaegerd28d1e02005-12-13 23:12:40 -080013 * Copyright (C) 2005 International Business Machines Corporation
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -070014 * Copyright (C) 2006 Trusted Computer Solutions, Inc.
Trent Jaegerd28d1e02005-12-13 23:12:40 -080015 *
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 */
Trent Jaegerd28d1e02005-12-13 23:12:40 -080034#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>
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090041#include <linux/slab.h>
Trent Jaegerd28d1e02005-12-13 23:12:40 -080042#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>
Arun Sharma600634972011-07-26 16:09:06 -070049#include <linux/atomic.h>
Trent Jaegerd28d1e02005-12-13 23:12:40 -080050
51#include "avc.h"
52#include "objsec.h"
53#include "xfrm.h"
54
Paul Moored621d352008-01-29 08:43:36 -050055/* Labeled XFRM instance counter */
56atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
Trent Jaegerd28d1e02005-12-13 23:12:40 -080057
58/*
Paul Moore4baabee2013-07-23 17:38:39 -040059 * Returns true if the context is an LSM/SELinux context.
Trent Jaegerd28d1e02005-12-13 23:12:40 -080060 */
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/*
Paul Moore4baabee2013-07-23 17:38:39 -040069 * Returns true if the xfrm contains a security blob for SELinux.
Trent Jaegerd28d1e02005-12-13 23:12:40 -080070 */
71static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
72{
73 return selinux_authorizable_ctx(x->security);
74}
75
76/*
Paul Moore2e5aa862013-07-23 17:38:38 -040077 * 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{
83 int rc;
84 const struct task_security_struct *tsec = current_security();
85 struct xfrm_sec_ctx *ctx = NULL;
86 u32 str_len;
87
88 if (ctxp == NULL || uctx == NULL ||
89 uctx->ctx_doi != XFRM_SC_DOI_LSM ||
90 uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
91 return -EINVAL;
92
93 str_len = uctx->ctx_len;
94 if (str_len >= PAGE_SIZE)
95 return -ENOMEM;
96
97 ctx = kmalloc(sizeof(*ctx) + str_len + 1, GFP_KERNEL);
98 if (!ctx)
99 return -ENOMEM;
100
101 ctx->ctx_doi = XFRM_SC_DOI_LSM;
102 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
103 ctx->ctx_len = str_len;
104 memcpy(ctx->ctx_str, &uctx[1], str_len);
105 ctx->ctx_str[str_len] = '\0';
106 rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid);
107 if (rc)
108 goto err;
109
110 rc = avc_has_perm(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/*
Paul Mooreccf17cc2013-07-23 17:38:39 -0400125 * 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(tsec->sid, ctx->ctx_sid,
147 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
148 NULL);
149}
150
151/*
Paul Moore4baabee2013-07-23 17:38:39 -0400152 * LSM hook implementation that authorizes that a flow can use a xfrm policy
153 * rule.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800154 */
Paul Moore03e1ad72008-04-12 19:07:52 -0700155int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800156{
Venkat Yekkirala5b368e62006-10-05 15:42:18 -0500157 int rc;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800158
Paul Moore96484342013-07-23 17:38:39 -0400159 /* All flows should be treated as polmatch'ing an otherwise applicable
160 * "non-labeled" policy. This would prevent inadvertent "leaks". */
161 if (!ctx)
Venkat Yekkirala5b368e62006-10-05 15:42:18 -0500162 return 0;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800163
Paul Moore96484342013-07-23 17:38:39 -0400164 /* Context sid is either set to label or ANY_ASSOC */
165 if (!selinux_authorizable_ctx(ctx))
166 return -EINVAL;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800167
Paul Moore96484342013-07-23 17:38:39 -0400168 rc = avc_has_perm(fl_secid, ctx->ctx_sid,
169 SECCLASS_ASSOCIATION, ASSOCIATION__POLMATCH, NULL);
170 return (rc == -EACCES ? -ESRCH : rc);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800171}
172
173/*
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700174 * LSM hook implementation that authorizes that a state matches
175 * the given policy, flow combo.
176 */
Paul Moore96484342013-07-23 17:38:39 -0400177int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x,
178 struct xfrm_policy *xp,
179 const struct flowi *fl)
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700180{
181 u32 state_sid;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700182
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600183 if (!xp->security)
Venkat Yekkirala5b368e62006-10-05 15:42:18 -0500184 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;
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600190 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;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700198
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600199 state_sid = x->security->ctx_sid;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700200
David S. Miller1d28f422011-03-12 00:29:39 -0500201 if (fl->flowi_secid != state_sid)
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700202 return 0;
203
Paul Moore96484342013-07-23 17:38:39 -0400204 /* We don't need a separate SA Vs. policy polmatch check since the SA
205 * is now of the same label as the flow and a flow Vs. policy polmatch
206 * check had already happened in selinux_xfrm_policy_lookup() above. */
207 return (avc_has_perm(fl->flowi_secid, state_sid,
208 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO,
209 NULL) ? 0 : 1);
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700210}
211
212/*
Venkat Yekkirala6b877692006-11-08 17:04:09 -0600213 * LSM hook implementation that checks and/or returns the xfrm sid for the
214 * incoming packet.
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700215 */
Venkat Yekkiralabeb8d132006-08-04 23:12:42 -0700216int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700217{
Paul Mooree2193692013-07-23 17:38:40 -0400218 u32 sid_session = SECSID_NULL;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700219 struct sec_path *sp;
220
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700221 if (skb == NULL)
Paul Mooree2193692013-07-23 17:38:40 -0400222 goto out;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700223
224 sp = skb->sp;
225 if (sp) {
Paul Mooree2193692013-07-23 17:38:40 -0400226 int i;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700227
Paul Mooree2193692013-07-23 17:38:40 -0400228 for (i = sp->len - 1; i >= 0; i--) {
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700229 struct xfrm_state *x = sp->xvec[i];
230 if (selinux_authorizable_xfrm(x)) {
231 struct xfrm_sec_ctx *ctx = x->security;
232
Paul Mooree2193692013-07-23 17:38:40 -0400233 if (sid_session == SECSID_NULL) {
234 sid_session = ctx->ctx_sid;
Venkat Yekkiralabeb8d132006-08-04 23:12:42 -0700235 if (!ckall)
Paul Mooree2193692013-07-23 17:38:40 -0400236 goto out;
237 } else if (sid_session != ctx->ctx_sid) {
238 *sid = SECSID_NULL;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700239 return -EINVAL;
Paul Mooree2193692013-07-23 17:38:40 -0400240 }
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700241 }
242 }
243 }
244
Paul Mooree2193692013-07-23 17:38:40 -0400245out:
246 *sid = sid_session;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700247 return 0;
248}
249
250/*
Paul Moore4baabee2013-07-23 17:38:39 -0400251 * LSM hook implementation that allocs and transfers uctx spec to xfrm_policy.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800252 */
Paul Moore03e1ad72008-04-12 19:07:52 -0700253int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
254 struct xfrm_user_sec_ctx *uctx)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800255{
Paul Moore2e5aa862013-07-23 17:38:38 -0400256 return selinux_xfrm_alloc_user(ctxp, uctx);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800257}
258
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800259/*
Paul Moore4baabee2013-07-23 17:38:39 -0400260 * LSM hook implementation that copies security data structure from old to new
261 * for policy cloning.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800262 */
Paul Moore03e1ad72008-04-12 19:07:52 -0700263int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
264 struct xfrm_sec_ctx **new_ctxp)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800265{
Paul Moore03e1ad72008-04-12 19:07:52 -0700266 struct xfrm_sec_ctx *new_ctx;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800267
Paul Mooreccf17cc2013-07-23 17:38:39 -0400268 if (!old_ctx)
269 return 0;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800270
Paul Mooreccf17cc2013-07-23 17:38:39 -0400271 new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len, GFP_ATOMIC);
272 if (!new_ctx)
273 return -ENOMEM;
274 memcpy(new_ctx, old_ctx, sizeof(*old_ctx) + old_ctx->ctx_len);
275 atomic_inc(&selinux_xfrm_refcount);
276 *new_ctxp = new_ctx;
277
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800278 return 0;
279}
280
281/*
Paul Moore03e1ad72008-04-12 19:07:52 -0700282 * LSM hook implementation that frees xfrm_sec_ctx security information.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800283 */
Paul Moore03e1ad72008-04-12 19:07:52 -0700284void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800285{
Paul Mooreccf17cc2013-07-23 17:38:39 -0400286 selinux_xfrm_free(ctx);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800287}
288
289/*
Catherine Zhangc8c05a82006-06-08 23:39:49 -0700290 * LSM hook implementation that authorizes deletion of labeled policies.
291 */
Paul Moore03e1ad72008-04-12 19:07:52 -0700292int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
Catherine Zhangc8c05a82006-06-08 23:39:49 -0700293{
Paul Mooreccf17cc2013-07-23 17:38:39 -0400294 return selinux_xfrm_delete(ctx);
Catherine Zhangc8c05a82006-06-08 23:39:49 -0700295}
296
297/*
Paul Moore2e5aa862013-07-23 17:38:38 -0400298 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
299 * the supplied security context, and assigns it to the xfrm_state.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800300 */
Paul Moore2e5aa862013-07-23 17:38:38 -0400301int selinux_xfrm_state_alloc(struct xfrm_state *x,
302 struct xfrm_user_sec_ctx *uctx)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800303{
Paul Moore2e5aa862013-07-23 17:38:38 -0400304 return selinux_xfrm_alloc_user(&x->security, uctx);
305}
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800306
Paul Moore2e5aa862013-07-23 17:38:38 -0400307/*
308 * LSM hook implementation that allocates a xfrm_sec_state and populates based
309 * on a secid.
310 */
311int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
312 struct xfrm_sec_ctx *polsec, u32 secid)
313{
314 int rc;
315 struct xfrm_sec_ctx *ctx;
316 char *ctx_str = NULL;
317 int str_len;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800318
Paul Moore2e5aa862013-07-23 17:38:38 -0400319 if (!polsec)
320 return 0;
321
322 if (secid == 0)
323 return -EINVAL;
324
325 rc = security_sid_to_context(secid, &ctx_str, &str_len);
326 if (rc)
327 return rc;
328
329 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
330 if (!ctx)
331 return -ENOMEM;
332
333 ctx->ctx_doi = XFRM_SC_DOI_LSM;
334 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
335 ctx->ctx_sid = secid;
336 ctx->ctx_len = str_len;
337 memcpy(ctx->ctx_str, ctx_str, str_len);
338 kfree(ctx_str);
339
340 x->security = ctx;
341 atomic_inc(&selinux_xfrm_refcount);
342 return 0;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800343}
344
345/*
346 * LSM hook implementation that frees xfrm_state security information.
347 */
348void selinux_xfrm_state_free(struct xfrm_state *x)
349{
Paul Mooreccf17cc2013-07-23 17:38:39 -0400350 selinux_xfrm_free(x->security);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800351}
352
Paul Moore4baabee2013-07-23 17:38:39 -0400353/*
354 * LSM hook implementation that authorizes deletion of labeled SAs.
355 */
Catherine Zhangc8c05a82006-06-08 23:39:49 -0700356int selinux_xfrm_state_delete(struct xfrm_state *x)
357{
Paul Mooreccf17cc2013-07-23 17:38:39 -0400358 return selinux_xfrm_delete(x->security);
Catherine Zhangc8c05a82006-06-08 23:39:49 -0700359}
360
Catherine Zhang2c7946a2006-03-20 22:41:23 -0800361/*
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800362 * LSM hook that controls access to unlabelled packets. If
363 * a xfrm_state is authorizable (defined by macro) then it was
364 * already authorized by the IPSec process. If not, then
365 * we need to check for unlabelled access since this may not have
366 * gone thru the IPSec process.
367 */
Paul Mooreeef9b412013-07-23 17:38:39 -0400368int selinux_xfrm_sock_rcv_skb(u32 sk_sid, struct sk_buff *skb,
369 struct common_audit_data *ad)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800370{
Paul Mooreeef9b412013-07-23 17:38:39 -0400371 int i;
372 struct sec_path *sp = skb->sp;
373 u32 peer_sid = SECINITSID_UNLABELED;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800374
375 if (sp) {
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800376 for (i = 0; i < sp->len; i++) {
Dave Jones67644722006-04-02 23:34:19 -0700377 struct xfrm_state *x = sp->xvec[i];
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800378
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700379 if (x && selinux_authorizable_xfrm(x)) {
380 struct xfrm_sec_ctx *ctx = x->security;
Paul Mooreeef9b412013-07-23 17:38:39 -0400381 peer_sid = ctx->ctx_sid;
Venkat Yekkiralae0d1caa2006-07-24 23:29:07 -0700382 break;
383 }
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800384 }
385 }
386
Paul Mooreeef9b412013-07-23 17:38:39 -0400387 /* This check even when there's no association involved is intended,
388 * according to Trent Jaeger, to make sure a process can't engage in
389 * non-IPsec communication unless explicitly allowed by policy. */
390 return avc_has_perm(sk_sid, peer_sid,
391 SECCLASS_ASSOCIATION, ASSOCIATION__RECVFROM, ad);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800392}
393
394/*
395 * POSTROUTE_LAST hook's XFRM processing:
396 * If we have no security association, then we need to determine
397 * whether the socket is allowed to send to an unlabelled destination.
398 * If we do have a authorizable security association, then it has already been
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600399 * checked in the selinux_xfrm_state_pol_flow_match hook above.
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800400 */
Paul Mooreeef9b412013-07-23 17:38:39 -0400401int selinux_xfrm_postroute_last(u32 sk_sid, struct sk_buff *skb,
402 struct common_audit_data *ad, u8 proto)
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800403{
404 struct dst_entry *dst;
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800405
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600406 switch (proto) {
407 case IPPROTO_AH:
408 case IPPROTO_ESP:
409 case IPPROTO_COMP:
Paul Mooreeef9b412013-07-23 17:38:39 -0400410 /* We should have already seen this packet once before it
411 * underwent xfrm(s). No need to subject it to the unlabeled
412 * check. */
413 return 0;
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600414 default:
415 break;
416 }
417
Paul Mooreeef9b412013-07-23 17:38:39 -0400418 dst = skb_dst(skb);
419 if (dst) {
420 struct dst_entry *iter;
Venkat Yekkirala67f83cb2006-11-08 17:04:26 -0600421
Paul Mooreeef9b412013-07-23 17:38:39 -0400422 for (iter = dst; iter != NULL; iter = iter->child) {
423 struct xfrm_state *x = iter->xfrm;
424
425 if (x && selinux_authorizable_xfrm(x))
426 return 0;
427 }
428 }
429
430 /* This check even when there's no association involved is intended,
431 * according to Trent Jaeger, to make sure a process can't engage in
432 * non-IPsec communication unless explicitly allowed by policy. */
433 return avc_has_perm(sk_sid, SECINITSID_UNLABELED,
434 SECCLASS_ASSOCIATION, ASSOCIATION__SENDTO, ad);
Trent Jaegerd28d1e02005-12-13 23:12:40 -0800435}