x86/efi: Enforce CONFIG_RELOCATABLE for EFI boot stub
[linux/fpc-iii.git] / security / selinux / xfrm.c
blob78504a18958aa8438b873fcbfb3279e062fd7e8f
1 /*
2 * NSA Security-Enhanced Linux (SELinux) security module
4 * This file contains the SELinux XFRM hook function implementations.
6 * Authors: Serge Hallyn <sergeh@us.ibm.com>
7 * Trent Jaeger <jaegert@us.ibm.com>
9 * Updated: Venkat Yekkirala <vyekkirala@TrustedCS.com>
11 * Granular IPSec Associations for use in MLS environments.
13 * Copyright (C) 2005 International Business Machines Corporation
14 * Copyright (C) 2006 Trusted Computer Solutions, Inc.
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.
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
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>
51 #include "avc.h"
52 #include "objsec.h"
53 #include "xfrm.h"
55 /* Labeled XFRM instance counter */
56 atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
59 * Returns true if an LSM/SELinux context
61 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
63 return (ctx &&
64 (ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
65 (ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
69 * Returns true if the xfrm contains a security blob for SELinux
71 static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
73 return selinux_authorizable_ctx(x->security);
77 * LSM hook implementation that authorizes that a flow can use
78 * a xfrm policy rule.
80 int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
82 int rc;
83 u32 sel_sid;
85 /* Context sid is either set to label or ANY_ASSOC */
86 if (ctx) {
87 if (!selinux_authorizable_ctx(ctx))
88 return -EINVAL;
90 sel_sid = ctx->ctx_sid;
91 } else
93 * All flows should be treated as polmatch'ing an
94 * otherwise applicable "non-labeled" policy. This
95 * would prevent inadvertent "leaks".
97 return 0;
99 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
100 ASSOCIATION__POLMATCH,
101 NULL);
103 if (rc == -EACCES)
104 return -ESRCH;
106 return rc;
110 * LSM hook implementation that authorizes that a state matches
111 * the given policy, flow combo.
114 int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp,
115 const struct flowi *fl)
117 u32 state_sid;
118 int rc;
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;
136 state_sid = x->security->ctx_sid;
138 if (fl->flowi_secid != state_sid)
139 return 0;
141 rc = avc_has_perm(fl->flowi_secid, state_sid, SECCLASS_ASSOCIATION,
142 ASSOCIATION__SENDTO,
143 NULL)? 0:1;
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.
152 return rc;
155 static int selinux_xfrm_skb_sid_ingress(struct sk_buff *skb,
156 u32 *sid, int ckall)
158 struct sec_path *sp = skb->sp;
160 *sid = SECSID_NULL;
162 if (sp) {
163 int i, sid_set = 0;
165 for (i = sp->len-1; i >= 0; i--) {
166 struct xfrm_state *x = sp->xvec[i];
167 if (selinux_authorizable_xfrm(x)) {
168 struct xfrm_sec_ctx *ctx = x->security;
170 if (!sid_set) {
171 *sid = ctx->ctx_sid;
172 sid_set = 1;
174 if (!ckall)
175 break;
176 } else if (*sid != ctx->ctx_sid)
177 return -EINVAL;
182 return 0;
185 static u32 selinux_xfrm_skb_sid_egress(struct sk_buff *skb)
187 struct dst_entry *dst = skb_dst(skb);
188 struct xfrm_state *x;
190 if (dst == NULL)
191 return SECSID_NULL;
192 x = dst->xfrm;
193 if (x == NULL || !selinux_authorizable_xfrm(x))
194 return SECSID_NULL;
196 return x->security->ctx_sid;
200 * LSM hook implementation that checks and/or returns the xfrm sid for the
201 * incoming packet.
204 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
206 if (skb == NULL) {
207 *sid = SECSID_NULL;
208 return 0;
210 return selinux_xfrm_skb_sid_ingress(skb, sid, ckall);
213 int selinux_xfrm_skb_sid(struct sk_buff *skb, u32 *sid)
215 int rc;
217 rc = selinux_xfrm_skb_sid_ingress(skb, sid, 0);
218 if (rc == 0 && *sid == SECSID_NULL)
219 *sid = selinux_xfrm_skb_sid_egress(skb);
221 return rc;
225 * Security blob allocation for xfrm_policy and xfrm_state
226 * CTX does not have a meaningful value on input
228 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
229 struct xfrm_user_sec_ctx *uctx, u32 sid)
231 int rc = 0;
232 const struct task_security_struct *tsec = current_security();
233 struct xfrm_sec_ctx *ctx = NULL;
234 char *ctx_str = NULL;
235 u32 str_len;
237 BUG_ON(uctx && sid);
239 if (!uctx)
240 goto not_from_user;
242 if (uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
243 return -EINVAL;
245 str_len = uctx->ctx_len;
246 if (str_len >= PAGE_SIZE)
247 return -ENOMEM;
249 *ctxp = ctx = kmalloc(sizeof(*ctx) +
250 str_len + 1,
251 GFP_KERNEL);
253 if (!ctx)
254 return -ENOMEM;
256 ctx->ctx_doi = uctx->ctx_doi;
257 ctx->ctx_len = str_len;
258 ctx->ctx_alg = uctx->ctx_alg;
260 memcpy(ctx->ctx_str,
261 uctx+1,
262 str_len);
263 ctx->ctx_str[str_len] = 0;
264 rc = security_context_to_sid(ctx->ctx_str,
265 str_len,
266 &ctx->ctx_sid);
268 if (rc)
269 goto out;
272 * Does the subject have permission to set security context?
274 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
275 SECCLASS_ASSOCIATION,
276 ASSOCIATION__SETCONTEXT, NULL);
277 if (rc)
278 goto out;
280 return rc;
282 not_from_user:
283 rc = security_sid_to_context(sid, &ctx_str, &str_len);
284 if (rc)
285 goto out;
287 *ctxp = ctx = kmalloc(sizeof(*ctx) +
288 str_len,
289 GFP_ATOMIC);
291 if (!ctx) {
292 rc = -ENOMEM;
293 goto out;
296 ctx->ctx_doi = XFRM_SC_DOI_LSM;
297 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
298 ctx->ctx_sid = sid;
299 ctx->ctx_len = str_len;
300 memcpy(ctx->ctx_str,
301 ctx_str,
302 str_len);
304 goto out2;
306 out:
307 *ctxp = NULL;
308 kfree(ctx);
309 out2:
310 kfree(ctx_str);
311 return rc;
315 * LSM hook implementation that allocs and transfers uctx spec to
316 * xfrm_policy.
318 int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
319 struct xfrm_user_sec_ctx *uctx)
321 int err;
323 BUG_ON(!uctx);
325 err = selinux_xfrm_sec_ctx_alloc(ctxp, uctx, 0);
326 if (err == 0)
327 atomic_inc(&selinux_xfrm_refcount);
329 return err;
334 * LSM hook implementation that copies security data structure from old to
335 * new for policy cloning.
337 int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
338 struct xfrm_sec_ctx **new_ctxp)
340 struct xfrm_sec_ctx *new_ctx;
342 if (old_ctx) {
343 new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len,
344 GFP_ATOMIC);
345 if (!new_ctx)
346 return -ENOMEM;
348 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
349 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
350 atomic_inc(&selinux_xfrm_refcount);
351 *new_ctxp = new_ctx;
353 return 0;
357 * LSM hook implementation that frees xfrm_sec_ctx security information.
359 void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
361 atomic_dec(&selinux_xfrm_refcount);
362 kfree(ctx);
366 * LSM hook implementation that authorizes deletion of labeled policies.
368 int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
370 const struct task_security_struct *tsec = current_security();
372 if (!ctx)
373 return 0;
375 return avc_has_perm(tsec->sid, ctx->ctx_sid,
376 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
377 NULL);
381 * LSM hook implementation that allocs and transfers sec_ctx spec to
382 * xfrm_state.
384 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
385 u32 secid)
387 int err;
389 BUG_ON(!x);
391 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
392 if (err == 0)
393 atomic_inc(&selinux_xfrm_refcount);
394 return err;
398 * LSM hook implementation that frees xfrm_state security information.
400 void selinux_xfrm_state_free(struct xfrm_state *x)
402 atomic_dec(&selinux_xfrm_refcount);
403 kfree(x->security);
407 * LSM hook implementation that authorizes deletion of labeled SAs.
409 int selinux_xfrm_state_delete(struct xfrm_state *x)
411 const struct task_security_struct *tsec = current_security();
412 struct xfrm_sec_ctx *ctx = x->security;
414 if (!ctx)
415 return 0;
417 return avc_has_perm(tsec->sid, ctx->ctx_sid,
418 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
419 NULL);
423 * LSM hook that controls access to unlabelled packets. If
424 * a xfrm_state is authorizable (defined by macro) then it was
425 * already authorized by the IPSec process. If not, then
426 * we need to check for unlabelled access since this may not have
427 * gone thru the IPSec process.
429 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
430 struct common_audit_data *ad)
432 int i, rc = 0;
433 struct sec_path *sp;
434 u32 sel_sid = SECINITSID_UNLABELED;
436 sp = skb->sp;
438 if (sp) {
439 for (i = 0; i < sp->len; i++) {
440 struct xfrm_state *x = sp->xvec[i];
442 if (x && selinux_authorizable_xfrm(x)) {
443 struct xfrm_sec_ctx *ctx = x->security;
444 sel_sid = ctx->ctx_sid;
445 break;
451 * This check even when there's no association involved is
452 * intended, according to Trent Jaeger, to make sure a
453 * process can't engage in non-ipsec communication unless
454 * explicitly allowed by policy.
457 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
458 ASSOCIATION__RECVFROM, ad);
460 return rc;
464 * POSTROUTE_LAST hook's XFRM processing:
465 * If we have no security association, then we need to determine
466 * whether the socket is allowed to send to an unlabelled destination.
467 * If we do have a authorizable security association, then it has already been
468 * checked in the selinux_xfrm_state_pol_flow_match hook above.
470 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
471 struct common_audit_data *ad, u8 proto)
473 struct dst_entry *dst;
474 int rc = 0;
476 dst = skb_dst(skb);
478 if (dst) {
479 struct dst_entry *dst_test;
481 for (dst_test = dst; dst_test != NULL;
482 dst_test = dst_test->child) {
483 struct xfrm_state *x = dst_test->xfrm;
485 if (x && selinux_authorizable_xfrm(x))
486 goto out;
490 switch (proto) {
491 case IPPROTO_AH:
492 case IPPROTO_ESP:
493 case IPPROTO_COMP:
495 * We should have already seen this packet once before
496 * it underwent xfrm(s). No need to subject it to the
497 * unlabeled check.
499 goto out;
500 default:
501 break;
505 * This check even when there's no association involved is
506 * intended, according to Trent Jaeger, to make sure a
507 * process can't engage in non-ipsec communication unless
508 * explicitly allowed by policy.
511 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
512 ASSOCIATION__SENDTO, ad);
513 out:
514 return rc;