fs: use kmem_cache_zalloc instead
[pv_ops_mirror.git] / security / selinux / xfrm.c
blobba715f40b658e4dfd63a05024ab566bcb81daf9c
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/module.h>
35 #include <linux/kernel.h>
36 #include <linux/init.h>
37 #include <linux/security.h>
38 #include <linux/types.h>
39 #include <linux/netfilter.h>
40 #include <linux/netfilter_ipv4.h>
41 #include <linux/netfilter_ipv6.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 <asm/semaphore.h>
51 #include "avc.h"
52 #include "objsec.h"
53 #include "xfrm.h"
57 * Returns true if an LSM/SELinux context
59 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
61 return (ctx &&
62 (ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
63 (ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
67 * Returns true if the xfrm contains a security blob for SELinux
69 static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
71 return selinux_authorizable_ctx(x->security);
75 * LSM hook implementation that authorizes that a flow can use
76 * a xfrm policy rule.
78 int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
80 int rc;
81 u32 sel_sid;
82 struct xfrm_sec_ctx *ctx;
84 /* Context sid is either set to label or ANY_ASSOC */
85 if ((ctx = xp->security)) {
86 if (!selinux_authorizable_ctx(ctx))
87 return -EINVAL;
89 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 rc = -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 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->secid != state_sid)
139 return 0;
141 rc = avc_has_perm(fl->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;
156 * LSM hook implementation that checks and/or returns the xfrm sid for the
157 * incoming packet.
160 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
162 struct sec_path *sp;
164 *sid = SECSID_NULL;
166 if (skb == NULL)
167 return 0;
169 sp = skb->sp;
170 if (sp) {
171 int i, sid_set = 0;
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;
178 if (!sid_set) {
179 *sid = ctx->ctx_sid;
180 sid_set = 1;
182 if (!ckall)
183 break;
185 else if (*sid != ctx->ctx_sid)
186 return -EINVAL;
191 return 0;
195 * Security blob allocation for xfrm_policy and xfrm_state
196 * CTX does not have a meaningful value on input
198 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
199 struct xfrm_user_sec_ctx *uctx, u32 sid)
201 int rc = 0;
202 struct task_security_struct *tsec = current->security;
203 struct xfrm_sec_ctx *ctx = NULL;
204 char *ctx_str = NULL;
205 u32 str_len;
207 BUG_ON(uctx && sid);
209 if (!uctx)
210 goto not_from_user;
212 if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
213 return -EINVAL;
215 if (uctx->ctx_len >= PAGE_SIZE)
216 return -ENOMEM;
218 *ctxp = ctx = kmalloc(sizeof(*ctx) +
219 uctx->ctx_len + 1,
220 GFP_KERNEL);
222 if (!ctx)
223 return -ENOMEM;
225 ctx->ctx_doi = uctx->ctx_doi;
226 ctx->ctx_len = uctx->ctx_len;
227 ctx->ctx_alg = uctx->ctx_alg;
229 memcpy(ctx->ctx_str,
230 uctx+1,
231 ctx->ctx_len);
232 ctx->ctx_str[ctx->ctx_len] = 0;
233 rc = security_context_to_sid(ctx->ctx_str,
234 ctx->ctx_len,
235 &ctx->ctx_sid);
237 if (rc)
238 goto out;
241 * Does the subject have permission to set security context?
243 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
244 SECCLASS_ASSOCIATION,
245 ASSOCIATION__SETCONTEXT, NULL);
246 if (rc)
247 goto out;
249 return rc;
251 not_from_user:
252 rc = security_sid_to_context(sid, &ctx_str, &str_len);
253 if (rc)
254 goto out;
256 *ctxp = ctx = kmalloc(sizeof(*ctx) +
257 str_len,
258 GFP_ATOMIC);
260 if (!ctx) {
261 rc = -ENOMEM;
262 goto out;
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);
273 goto out2;
275 out:
276 *ctxp = NULL;
277 kfree(ctx);
278 out2:
279 kfree(ctx_str);
280 return rc;
284 * LSM hook implementation that allocs and transfers uctx spec to
285 * xfrm_policy.
287 int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
288 struct xfrm_user_sec_ctx *uctx)
290 int err;
292 BUG_ON(!xp);
293 BUG_ON(!uctx);
295 err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0);
296 return err;
301 * LSM hook implementation that copies security data structure from old to
302 * new for policy cloning.
304 int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
306 struct xfrm_sec_ctx *old_ctx, *new_ctx;
308 old_ctx = old->security;
310 if (old_ctx) {
311 new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
312 old_ctx->ctx_len,
313 GFP_KERNEL);
315 if (!new_ctx)
316 return -ENOMEM;
318 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
319 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
321 return 0;
325 * LSM hook implementation that frees xfrm_policy security information.
327 void selinux_xfrm_policy_free(struct xfrm_policy *xp)
329 struct xfrm_sec_ctx *ctx = xp->security;
330 if (ctx)
331 kfree(ctx);
335 * LSM hook implementation that authorizes deletion of labeled policies.
337 int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
339 struct task_security_struct *tsec = current->security;
340 struct xfrm_sec_ctx *ctx = xp->security;
341 int rc = 0;
343 if (ctx)
344 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
345 SECCLASS_ASSOCIATION,
346 ASSOCIATION__SETCONTEXT, NULL);
348 return rc;
352 * LSM hook implementation that allocs and transfers sec_ctx spec to
353 * xfrm_state.
355 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
356 u32 secid)
358 int err;
360 BUG_ON(!x);
362 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
363 return err;
367 * LSM hook implementation that frees xfrm_state security information.
369 void selinux_xfrm_state_free(struct xfrm_state *x)
371 struct xfrm_sec_ctx *ctx = x->security;
372 if (ctx)
373 kfree(ctx);
377 * LSM hook implementation that authorizes deletion of labeled SAs.
379 int selinux_xfrm_state_delete(struct xfrm_state *x)
381 struct task_security_struct *tsec = current->security;
382 struct xfrm_sec_ctx *ctx = x->security;
383 int rc = 0;
385 if (ctx)
386 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
387 SECCLASS_ASSOCIATION,
388 ASSOCIATION__SETCONTEXT, NULL);
390 return rc;
394 * LSM hook that controls access to unlabelled packets. If
395 * a xfrm_state is authorizable (defined by macro) then it was
396 * already authorized by the IPSec process. If not, then
397 * we need to check for unlabelled access since this may not have
398 * gone thru the IPSec process.
400 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
401 struct avc_audit_data *ad)
403 int i, rc = 0;
404 struct sec_path *sp;
405 u32 sel_sid = SECINITSID_UNLABELED;
407 sp = skb->sp;
409 if (sp) {
410 for (i = 0; i < sp->len; i++) {
411 struct xfrm_state *x = sp->xvec[i];
413 if (x && selinux_authorizable_xfrm(x)) {
414 struct xfrm_sec_ctx *ctx = x->security;
415 sel_sid = ctx->ctx_sid;
416 break;
422 * This check even when there's no association involved is
423 * intended, according to Trent Jaeger, to make sure a
424 * process can't engage in non-ipsec communication unless
425 * explicitly allowed by policy.
428 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
429 ASSOCIATION__RECVFROM, ad);
431 return rc;
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.
441 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
442 struct avc_audit_data *ad, u8 proto)
444 struct dst_entry *dst;
445 int rc = 0;
447 dst = skb->dst;
449 if (dst) {
450 struct dst_entry *dst_test;
452 for (dst_test = dst; dst_test != 0;
453 dst_test = dst_test->child) {
454 struct xfrm_state *x = dst_test->xfrm;
456 if (x && selinux_authorizable_xfrm(x))
457 goto out;
461 switch (proto) {
462 case IPPROTO_AH:
463 case IPPROTO_ESP:
464 case IPPROTO_COMP:
466 * We should have already seen this packet once before
467 * it underwent xfrm(s). No need to subject it to the
468 * unlabeled check.
470 goto out;
471 default:
472 break;
476 * This check even when there's no association involved is
477 * intended, according to Trent Jaeger, to make sure a
478 * process can't engage in non-ipsec communication unless
479 * explicitly allowed by policy.
482 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
483 ASSOCIATION__SENDTO, ad);
484 out:
485 return rc;