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 determines the sid for the session.
190 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
203 for (i = sp->len-1; i >= 0; i--) {
204 struct xfrm_state *x = sp->xvec[i];
205 if (selinux_authorizable_xfrm(x)) {
206 struct xfrm_sec_ctx *ctx = x->security;
215 else if (*sid != ctx->ctx_sid)
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)
232 struct task_security_struct *tsec = current->security;
233 struct xfrm_sec_ctx *ctx = NULL;
234 char *ctx_str = NULL;
242 if (uctx->ctx_doi != XFRM_SC_ALG_SELINUX)
245 if (uctx->ctx_len >= PAGE_SIZE)
248 *ctxp = ctx = kmalloc(sizeof(*ctx) +
255 ctx->ctx_doi = uctx->ctx_doi;
256 ctx->ctx_len = uctx->ctx_len;
257 ctx->ctx_alg = uctx->ctx_alg;
262 rc = security_context_to_sid(ctx->ctx_str,
270 * Does the subject have permission to set security context?
272 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
273 SECCLASS_ASSOCIATION,
274 ASSOCIATION__SETCONTEXT, NULL);
281 rc = security_sid_to_context(sid, &ctx_str, &str_len);
285 *ctxp = ctx = kmalloc(sizeof(*ctx) +
294 ctx->ctx_doi = XFRM_SC_DOI_LSM;
295 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
297 ctx->ctx_len = str_len;
313 * LSM hook implementation that allocs and transfers uctx spec to
316 int selinux_xfrm_policy_alloc(struct xfrm_policy *xp,
317 struct xfrm_user_sec_ctx *uctx)
324 err = selinux_xfrm_sec_ctx_alloc(&xp->security, uctx, 0);
330 * LSM hook implementation that copies security data structure from old to
331 * new for policy cloning.
333 int selinux_xfrm_policy_clone(struct xfrm_policy *old, struct xfrm_policy *new)
335 struct xfrm_sec_ctx *old_ctx, *new_ctx;
337 old_ctx = old->security;
340 new_ctx = new->security = kmalloc(sizeof(*new_ctx) +
347 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
348 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
354 * LSM hook implementation that frees xfrm_policy security information.
356 void selinux_xfrm_policy_free(struct xfrm_policy *xp)
358 struct xfrm_sec_ctx *ctx = xp->security;
364 * LSM hook implementation that authorizes deletion of labeled policies.
366 int selinux_xfrm_policy_delete(struct xfrm_policy *xp)
368 struct task_security_struct *tsec = current->security;
369 struct xfrm_sec_ctx *ctx = xp->security;
373 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
374 SECCLASS_ASSOCIATION,
375 ASSOCIATION__SETCONTEXT, NULL);
381 * LSM hook implementation that allocs and transfers sec_ctx spec to
384 int selinux_xfrm_state_alloc(struct xfrm_state *x, struct xfrm_user_sec_ctx *uctx,
391 err = selinux_xfrm_sec_ctx_alloc(&x->security, uctx, secid);
396 * LSM hook implementation that frees xfrm_state security information.
398 void selinux_xfrm_state_free(struct xfrm_state *x)
400 struct xfrm_sec_ctx *ctx = x->security;
406 * SELinux internal function to retrieve the context of a connected
407 * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
408 * association used to connect to the remote socket.
410 * Retrieve via getsockopt SO_PEERSEC.
412 u32 selinux_socket_getpeer_stream(struct sock *sk)
414 struct dst_entry *dst, *dst_test;
415 u32 peer_sid = SECSID_NULL;
417 if (sk->sk_state != TCP_ESTABLISHED)
420 dst = sk_dst_get(sk);
424 for (dst_test = dst; dst_test != 0;
425 dst_test = dst_test->child) {
426 struct xfrm_state *x = dst_test->xfrm;
428 if (x && selinux_authorizable_xfrm(x)) {
429 struct xfrm_sec_ctx *ctx = x->security;
430 peer_sid = ctx->ctx_sid;
441 * SELinux internal function to retrieve the context of a UDP packet
442 * based on its security association used to connect to the remote socket.
444 * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
447 u32 selinux_socket_getpeer_dgram(struct sk_buff *skb)
454 if (skb->sk->sk_protocol != IPPROTO_UDP)
461 for (i = sp->len-1; i >= 0; i--) {
462 struct xfrm_state *x = sp->xvec[i];
463 if (selinux_authorizable_xfrm(x)) {
464 struct xfrm_sec_ctx *ctx = x->security;
474 * LSM hook implementation that authorizes deletion of labeled SAs.
476 int selinux_xfrm_state_delete(struct xfrm_state *x)
478 struct task_security_struct *tsec = current->security;
479 struct xfrm_sec_ctx *ctx = x->security;
483 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
484 SECCLASS_ASSOCIATION,
485 ASSOCIATION__SETCONTEXT, NULL);
491 * LSM hook that controls access to unlabelled packets. If
492 * a xfrm_state is authorizable (defined by macro) then it was
493 * already authorized by the IPSec process. If not, then
494 * we need to check for unlabelled access since this may not have
495 * gone thru the IPSec process.
497 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
498 struct avc_audit_data *ad)
502 u32 sel_sid = SECINITSID_UNLABELED;
507 for (i = 0; i < sp->len; i++) {
508 struct xfrm_state *x = sp->xvec[i];
510 if (x && selinux_authorizable_xfrm(x)) {
511 struct xfrm_sec_ctx *ctx = x->security;
512 sel_sid = ctx->ctx_sid;
518 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
519 ASSOCIATION__RECVFROM, ad);
525 * POSTROUTE_LAST hook's XFRM processing:
526 * If we have no security association, then we need to determine
527 * whether the socket is allowed to send to an unlabelled destination.
528 * If we do have a authorizable security association, then it has already been
529 * checked in xfrm_policy_lookup hook.
531 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
532 struct avc_audit_data *ad)
534 struct dst_entry *dst;
540 struct dst_entry *dst_test;
542 for (dst_test = dst; dst_test != 0;
543 dst_test = dst_test->child) {
544 struct xfrm_state *x = dst_test->xfrm;
546 if (x && selinux_authorizable_xfrm(x))
551 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
552 ASSOCIATION__SENDTO, ad);