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)
81 u32 sel_sid = SECINITSID_UNLABELED;
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;
92 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
93 ASSOCIATION__POLMATCH,
100 * LSM hook implementation that authorizes that a state matches
101 * the given policy, flow combo.
104 int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp,
112 state_sid = x->security->ctx_sid;
114 state_sid = SECINITSID_UNLABELED;
117 pol_sid = xp->security->ctx_sid;
119 pol_sid = SECINITSID_UNLABELED;
121 err = avc_has_perm(state_sid, pol_sid, SECCLASS_ASSOCIATION,
122 ASSOCIATION__POLMATCH,
128 return selinux_xfrm_flow_state_match(fl, x);
132 * LSM hook implementation that authorizes that a particular outgoing flow
133 * can use a given security association.
136 int selinux_xfrm_flow_state_match(struct flowi *fl, struct xfrm_state *xfrm)
139 u32 sel_sid = SECINITSID_UNLABELED;
140 struct xfrm_sec_ctx *ctx;
142 /* Context sid is either set to label or ANY_ASSOC */
143 if ((ctx = xfrm->security)) {
144 if (!selinux_authorizable_ctx(ctx))
147 sel_sid = ctx->ctx_sid;
150 rc = avc_has_perm(fl->secid, sel_sid, SECCLASS_ASSOCIATION,
158 * LSM hook implementation that determines the sid for the session.
161 int selinux_xfrm_decode_session(struct sk_buff *skb, struct flowi *fl)
165 fl->secid = SECSID_NULL;
174 for (i = sp->len-1; i >= 0; i--) {
175 struct xfrm_state *x = sp->xvec[i];
176 if (selinux_authorizable_xfrm(x)) {
177 struct xfrm_sec_ctx *ctx = x->security;
180 fl->secid = ctx->ctx_sid;
183 else if (fl->secid != ctx->ctx_sid)
193 * Security blob allocation for xfrm_policy and xfrm_state
194 * CTX does not have a meaningful value on input
196 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
197 struct xfrm_user_sec_ctx *uctx, struct xfrm_sec_ctx *pol, u32 sid)
200 struct task_security_struct *tsec = current->security;
201 struct xfrm_sec_ctx *ctx = NULL;
202 char *ctx_str = NULL;
213 if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
216 if (uctx->ctx_len >= PAGE_SIZE)
219 *ctxp = ctx = kmalloc(sizeof(*ctx) +
226 ctx->ctx_doi = uctx->ctx_doi;
227 ctx->ctx_len = uctx->ctx_len;
228 ctx->ctx_alg = uctx->ctx_alg;
233 rc = security_context_to_sid(ctx->ctx_str,
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);
253 rc = security_sid_mls_copy(pol->ctx_sid, sid, &ctx_sid);
257 rc = security_sid_to_context(ctx_sid, &ctx_str, &str_len);
261 *ctxp = ctx = kmalloc(sizeof(*ctx) +
271 ctx->ctx_doi = XFRM_SC_DOI_LSM;
272 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
273 ctx->ctx_sid = ctx_sid;
274 ctx->ctx_len = str_len;
290 * LSM hook implementation that allocs and transfers uctx spec to
293 int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx *uctx)
299 err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, NULL, 0);
305 * LSM hook implementation that copies security data structure from old to
306 * new for policy cloning.
308 int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
310 struct xfrm_sec_ctx *old_ctx, *new_ctx;
312 old_ctx = old->security;
315 new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
322 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
323 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
329 * LSM hook implementation that frees xfrm_policy security information.
331 void selinux_xfrm_policy_free(struct xfrm_policy *xp)
333 struct xfrm_sec_ctx *ctx = xp->security;
339 * LSM hook implementation that authorizes deletion of labeled policies.
341 int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
343 struct task_security_struct *tsec = current->security;
344 struct xfrm_sec_ctx *ctx = xp->security;
348 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
349 SECCLASS_ASSOCIATION,
350 ASSOCIATION__SETCONTEXT, NULL);
356 * LSM hook implementation that allocs and transfers sec_ctx spec to
359 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
360 struct xfrm_sec_ctx *pol, u32 secid)
366 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, pol, secid);
371 * LSM hook implementation that frees xfrm_state security information.
373 void selinux_xfrm_state_free(struct xfrm_state *x)
375 struct xfrm_sec_ctx *ctx = x->security;
381 * SELinux internal function to retrieve the context of a connected
382 * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
383 * association used to connect to the remote socket.
385 * Retrieve via getsockopt SO_PEERSEC.
387 u32 selinux_socket_getpeer_stream(struct sock *sk)
389 struct dst_entry *dst, *dst_test;
390 u32 peer_sid = SECSID_NULL;
392 if (sk->sk_state != TCP_ESTABLISHED)
395 dst = sk_dst_get(sk);
399 for (dst_test = dst; dst_test != 0;
400 dst_test = dst_test->child) {
401 struct xfrm_state *x = dst_test->xfrm;
403 if (x && selinux_authorizable_xfrm(x)) {
404 struct xfrm_sec_ctx *ctx = x->security;
405 peer_sid = ctx->ctx_sid;
416 * SELinux internal function to retrieve the context of a UDP packet
417 * based on its security association used to connect to the remote socket.
419 * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
422 u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
429 if (skb->sk->sk_protocol != IPPROTO_UDP)
436 for (i = sp->len-1; i >= 0; i--) {
437 struct xfrm_state *x = sp->xvec[i];
438 if (selinux_authorizable_xfrm(x)) {
439 struct xfrm_sec_ctx *ctx = x->security;
449 * LSM hook implementation that authorizes deletion of labeled SAs.
451 int selinux_xfrm_state_delete(struct xfrm_state *x)
453 struct task_security_struct *tsec = current->security;
454 struct xfrm_sec_ctx *ctx = x->security;
458 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
459 SECCLASS_ASSOCIATION,
460 ASSOCIATION__SETCONTEXT, NULL);
466 * LSM hook that controls access to unlabelled packets. If
467 * a xfrm_state is authorizable (defined by macro) then it was
468 * already authorized by the IPSec process. If not, then
469 * we need to check for unlabelled access since this may not have
470 * gone thru the IPSec process.
472 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
473 struct avc_audit_data *ad)
477 u32 sel_sid = SECINITSID_UNLABELED;
482 for (i = 0; i < sp->len; i++) {
483 struct xfrm_state *x = sp->xvec[i];
485 if (x && selinux_authorizable_xfrm(x)) {
486 struct xfrm_sec_ctx *ctx = x->security;
487 sel_sid = ctx->ctx_sid;
493 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
494 ASSOCIATION__RECVFROM, ad);
500 * POSTROUTE_LAST hook's XFRM processing:
501 * If we have no security association, then we need to determine
502 * whether the socket is allowed to send to an unlabelled destination.
503 * If we do have a authorizable security association, then it has already been
504 * checked in xfrm_policy_lookup hook.
506 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
507 struct avc_audit_data *ad)
509 struct dst_entry *dst;
515 struct dst_entry *dst_test;
517 for (dst_test = dst; dst_test != 0;
518 dst_test = dst_test->child) {
519 struct xfrm_state *x = dst_test->xfrm;
521 if (x && selinux_authorizable_xfrm(x))
526 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
527 ASSOCIATION__SENDTO, ad);