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.
24 * 1. Make sure to enable the following options in your kernel config:
26 * CONFIG_SECURITY_NETWORK=y
27 * CONFIG_SECURITY_NETWORK_XFRM=y
28 * CONFIG_SECURITY_SELINUX=m/y
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>
43 #include <linux/tcp.h>
44 #include <linux/skbuff.h>
45 #include <linux/xfrm.h>
47 #include <net/checksum.h>
49 #include <asm/semaphore.h>
57 * Returns true if an LSM/SELinux context
59 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *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
78 int selinux_xfrm_policy_lookup(struct xfrm_policy *xp, u32 fl_secid, u8 dir)
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))
89 sel_sid = ctx->ctx_sid;
93 * All flows should be treated as polmatch'ing an
94 * otherwise applicable "non-labeled" policy. This
95 * would prevent inadvertent "leaks".
99 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
100 ASSOCIATION__POLMATCH,
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,
123 /* unlabeled SA and labeled policy can't match */
126 state_sid = x->security->ctx_sid;
127 pol_sid = xp->security->ctx_sid;
130 /* unlabeled policy and labeled SA can't match */
133 /* unlabeled policy and unlabeled SA match all flows */
136 err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION,
137 ASSOCIATION__POLMATCH,
143 err = avc_has_perm(fl->secid, state_sid, SECCLASS_ASSOCIATION,
151 * LSM hook implementation that authorizes that a particular outgoing flow
152 * can use a given security association.
155 int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm,
156 struct xfrm_policy *xp)
159 u32 sel_sid = SECINITSID_UNLABELED;
160 struct xfrm_sec_ctx *ctx;
171 /* Context sid is either set to label or ANY_ASSOC */
172 if ((ctx = xfrm->security)) {
173 if (!selinux_authorizable_ctx(ctx))
176 sel_sid = ctx->ctx_sid;
179 rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION,
187 * LSM hook implementation that checks and/or returns the xfrm sid for the
191 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
204 for (i = sp->len-1; i >= 0; i--) {
205 struct xfrm_state *x = sp->xvec[i];
206 if (selinux_authorizable_xfrm(x)) {
207 struct xfrm_sec_ctx *ctx = x->security;
216 else if (*sid != ctx->ctx_sid)
226 * Security blob allocation for xfrm_policy and xfrm_state
227 * CTX does not have a meaningful value on input
229 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
230 struct xfrm_user_sec_ctx *uctx, u32 sid)
233 struct task_security_struct *tsec = current->security;
234 struct xfrm_sec_ctx *ctx = NULL;
235 char *ctx_str = NULL;
243 if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
246 if (uctx->ctx_len >= PAGE_SIZE)
249 *ctxp = ctx = kmalloc(sizeof(*ctx) +
256 ctx->ctx_doi = uctx->ctx_doi;
257 ctx->ctx_len = uctx->ctx_len;
258 ctx->ctx_alg = uctx->ctx_alg;
263 rc = security_context_to_sid(ctx->ctx_str,
271 * Does the subject have permission to set security context?
273 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
274 SECCLASS_ASSOCIATION,
275 ASSOCIATION__SETCONTEXT, NULL);
282 rc = security_sid_to_context(sid, &ctx_str, &str_len);
286 *ctxp = ctx = kmalloc(sizeof(*ctx) +
295 ctx->ctx_doi = XFRM_SC_DOI_LSM;
296 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
298 ctx->ctx_len = str_len;
314 * LSM hook implementation that allocs and transfers uctx spec to
317 int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
318 struct xfrm_user_sec_ctx *uctx)
325 err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0);
331 * LSM hook implementation that copies security data structure from old to
332 * new for policy cloning.
334 int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
336 struct xfrm_sec_ctx *old_ctx, *new_ctx;
338 old_ctx = old->security;
341 new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
348 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
349 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
355 * LSM hook implementation that frees xfrm_policy security information.
357 void selinux_xfrm_policy_free(struct xfrm_policy *xp)
359 struct xfrm_sec_ctx *ctx = xp->security;
365 * LSM hook implementation that authorizes deletion of labeled policies.
367 int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
369 struct task_security_struct *tsec = current->security;
370 struct xfrm_sec_ctx *ctx = xp->security;
374 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
375 SECCLASS_ASSOCIATION,
376 ASSOCIATION__SETCONTEXT, NULL);
382 * LSM hook implementation that allocs and transfers sec_ctx spec to
385 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
392 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
397 * LSM hook implementation that frees xfrm_state security information.
399 void selinux_xfrm_state_free(struct xfrm_state *x)
401 struct xfrm_sec_ctx *ctx = x->security;
407 * SELinux internal function to retrieve the context of a UDP packet
408 * based on its security association.
410 * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
413 u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
420 if (skb->sk->sk_protocol != IPPROTO_UDP)
427 for (i = sp->len-1; i >= 0; i--) {
428 struct xfrm_state *x = sp->xvec[i];
429 if (selinux_authorizable_xfrm(x)) {
430 struct xfrm_sec_ctx *ctx = x->security;
440 * LSM hook implementation that authorizes deletion of labeled SAs.
442 int selinux_xfrm_state_delete(struct xfrm_state *x)
444 struct task_security_struct *tsec = current->security;
445 struct xfrm_sec_ctx *ctx = x->security;
449 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
450 SECCLASS_ASSOCIATION,
451 ASSOCIATION__SETCONTEXT, NULL);
457 * LSM hook that controls access to unlabelled packets. If
458 * a xfrm_state is authorizable (defined by macro) then it was
459 * already authorized by the IPSec process. If not, then
460 * we need to check for unlabelled access since this may not have
461 * gone thru the IPSec process.
463 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
464 struct avc_audit_data *ad)
468 u32 sel_sid = SECINITSID_UNLABELED;
473 for (i = 0; i < sp->len; i++) {
474 struct xfrm_state *x = sp->xvec[i];
476 if (x && selinux_authorizable_xfrm(x)) {
477 struct xfrm_sec_ctx *ctx = x->security;
478 sel_sid = ctx->ctx_sid;
484 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
485 ASSOCIATION__RECVFROM, ad);
491 * POSTROUTE_LAST hook's XFRM processing:
492 * If we have no security association, then we need to determine
493 * whether the socket is allowed to send to an unlabelled destination.
494 * If we do have a authorizable security association, then it has already been
495 * checked in xfrm_policy_lookup hook.
497 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
498 struct avc_audit_data *ad)
500 struct dst_entry *dst;
506 struct dst_entry *dst_test;
508 for (dst_test = dst; dst_test != 0;
509 dst_test = dst_test->child) {
510 struct xfrm_state *x = dst_test->xfrm;
512 if (x && selinux_authorizable_xfrm(x))
517 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
518 ASSOCIATION__SENDTO, ad);