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, u32 *sid, int ckall)
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;
186 else if (*sid != ctx->ctx_sid)
196 * Security blob allocation for xfrm_policy and xfrm_state
197 * CTX does not have a meaningful value on input
199 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx **ctxp,
200 struct xfrm_user_sec_ctx *uctx, struct xfrm_sec_ctx *pol, u32 sid)
203 struct task_security_struct *tsec = current->security;
204 struct xfrm_sec_ctx *ctx = NULL;
205 char *ctx_str = NULL;
216 if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
219 if (uctx->ctx_len >= PAGE_SIZE)
222 *ctxp = ctx = kmalloc(sizeof(*ctx) +
229 ctx->ctx_doi = uctx->ctx_doi;
230 ctx->ctx_len = uctx->ctx_len;
231 ctx->ctx_alg = uctx->ctx_alg;
236 rc = security_context_to_sid(ctx->ctx_str,
244 * Does the subject have permission to set security context?
246 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
247 SECCLASS_ASSOCIATION,
248 ASSOCIATION__SETCONTEXT, NULL);
256 rc = security_sid_mls_copy(pol->ctx_sid, sid, &ctx_sid);
260 rc = security_sid_to_context(ctx_sid, &ctx_str, &str_len);
264 *ctxp = ctx = kmalloc(sizeof(*ctx) +
274 ctx->ctx_doi = XFRM_SC_DOI_LSM;
275 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
276 ctx->ctx_sid = ctx_sid;
277 ctx->ctx_len = str_len;
293 * LSM hook implementation that allocs and transfers uctx spec to
296 int selinux_xfrm_policy_alloc(struct xfrm_policy *xp, struct xfrm_user_sec_ctx *uctx)
302 err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, NULL, 0);
308 * LSM hook implementation that copies security data structure from old to
309 * new for policy cloning.
311 int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
313 struct xfrm_sec_ctx *old_ctx, *new_ctx;
315 old_ctx = old->security;
318 new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
325 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
326 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
332 * LSM hook implementation that frees xfrm_policy security information.
334 void selinux_xfrm_policy_free(struct xfrm_policy *xp)
336 struct xfrm_sec_ctx *ctx = xp->security;
342 * LSM hook implementation that authorizes deletion of labeled policies.
344 int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
346 struct task_security_struct *tsec = current->security;
347 struct xfrm_sec_ctx *ctx = xp->security;
351 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
352 SECCLASS_ASSOCIATION,
353 ASSOCIATION__SETCONTEXT, NULL);
359 * LSM hook implementation that allocs and transfers sec_ctx spec to
362 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
363 struct xfrm_sec_ctx *pol, u32 secid)
369 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, pol, secid);
374 * LSM hook implementation that frees xfrm_state security information.
376 void selinux_xfrm_state_free(struct xfrm_state *x)
378 struct xfrm_sec_ctx *ctx = x->security;
384 * SELinux internal function to retrieve the context of a connected
385 * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
386 * association used to connect to the remote socket.
388 * Retrieve via getsockopt SO_PEERSEC.
390 u32 selinux_socket_getpeer_stream(struct sock *sk)
392 struct dst_entry *dst, *dst_test;
393 u32 peer_sid = SECSID_NULL;
395 if (sk->sk_state != TCP_ESTABLISHED)
398 dst = sk_dst_get(sk);
402 for (dst_test = dst; dst_test != 0;
403 dst_test = dst_test->child) {
404 struct xfrm_state *x = dst_test->xfrm;
406 if (x && selinux_authorizable_xfrm(x)) {
407 struct xfrm_sec_ctx *ctx = x->security;
408 peer_sid = ctx->ctx_sid;
419 * SELinux internal function to retrieve the context of a UDP packet
420 * based on its security association used to connect to the remote socket.
422 * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
425 u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
432 if (skb->sk->sk_protocol != IPPROTO_UDP)
439 for (i = sp->len-1; i >= 0; i--) {
440 struct xfrm_state *x = sp->xvec[i];
441 if (selinux_authorizable_xfrm(x)) {
442 struct xfrm_sec_ctx *ctx = x->security;
452 * LSM hook implementation that authorizes deletion of labeled SAs.
454 int selinux_xfrm_state_delete(struct xfrm_state *x)
456 struct task_security_struct *tsec = current->security;
457 struct xfrm_sec_ctx *ctx = x->security;
461 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
462 SECCLASS_ASSOCIATION,
463 ASSOCIATION__SETCONTEXT, NULL);
469 * LSM hook that controls access to unlabelled packets. If
470 * a xfrm_state is authorizable (defined by macro) then it was
471 * already authorized by the IPSec process. If not, then
472 * we need to check for unlabelled access since this may not have
473 * gone thru the IPSec process.
475 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
476 struct avc_audit_data *ad)
480 u32 sel_sid = SECINITSID_UNLABELED;
485 for (i = 0; i < sp->len; i++) {
486 struct xfrm_state *x = sp->xvec[i];
488 if (x && selinux_authorizable_xfrm(x)) {
489 struct xfrm_sec_ctx *ctx = x->security;
490 sel_sid = ctx->ctx_sid;
496 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
497 ASSOCIATION__RECVFROM, ad);
503 * POSTROUTE_LAST hook's XFRM processing:
504 * If we have no security association, then we need to determine
505 * whether the socket is allowed to send to an unlabelled destination.
506 * If we do have a authorizable security association, then it has already been
507 * checked in xfrm_policy_lookup hook.
509 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
510 struct avc_audit_data *ad)
512 struct dst_entry *dst;
518 struct dst_entry *dst_test;
520 for (dst_test = dst; dst_test != 0;
521 dst_test = dst_test->child) {
522 struct xfrm_state *x = dst_test->xfrm;
524 if (x && selinux_authorizable_xfrm(x))
529 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
530 ASSOCIATION__SENDTO, ad);