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/kernel.h>
35 #include <linux/init.h>
36 #include <linux/security.h>
37 #include <linux/types.h>
38 #include <linux/netfilter.h>
39 #include <linux/netfilter_ipv4.h>
40 #include <linux/netfilter_ipv6.h>
41 #include <linux/slab.h>
43 #include <linux/tcp.h>
44 #include <linux/skbuff.h>
45 #include <linux/xfrm.h>
47 #include <net/checksum.h>
49 #include <linux/atomic.h>
55 /* Labeled XFRM instance counter */
56 atomic_t selinux_xfrm_refcount = ATOMIC_INIT(0);
59 * Returns true if an LSM/SELinux context
61 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx *ctx)
64 (ctx->ctx_doi == XFRM_SC_DOI_LSM) &&
65 (ctx->ctx_alg == XFRM_SC_ALG_SELINUX));
69 * Returns true if the xfrm contains a security blob for SELinux
71 static inline int selinux_authorizable_xfrm(struct xfrm_state *x)
73 return selinux_authorizable_ctx(x->security);
77 * Allocates a xfrm_sec_state and populates it using the supplied security
78 * xfrm_user_sec_ctx context.
80 static int selinux_xfrm_alloc_user(struct xfrm_sec_ctx **ctxp,
81 struct xfrm_user_sec_ctx *uctx)
84 const struct task_security_struct *tsec = current_security();
85 struct xfrm_sec_ctx *ctx = NULL;
88 if (ctxp == NULL || uctx == NULL ||
89 uctx->ctx_doi != XFRM_SC_DOI_LSM ||
90 uctx->ctx_alg != XFRM_SC_ALG_SELINUX)
93 str_len = uctx->ctx_len;
94 if (str_len >= PAGE_SIZE)
97 ctx = kmalloc(sizeof(*ctx) + str_len + 1, GFP_KERNEL);
101 ctx->ctx_doi = XFRM_SC_DOI_LSM;
102 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
103 ctx->ctx_len = str_len;
104 memcpy(ctx->ctx_str, &uctx[1], str_len);
105 ctx->ctx_str[str_len] = '\0';
106 rc = security_context_to_sid(ctx->ctx_str, str_len, &ctx->ctx_sid);
110 rc = avc_has_perm(tsec->sid, ctx->ctx_sid,
111 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT, NULL);
116 atomic_inc(&selinux_xfrm_refcount);
125 * LSM hook implementation that authorizes that a flow can use
126 * a xfrm policy rule.
128 int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx *ctx, u32 fl_secid, u8 dir)
133 /* Context sid is either set to label or ANY_ASSOC */
135 if (!selinux_authorizable_ctx(ctx))
138 sel_sid = ctx->ctx_sid;
141 * All flows should be treated as polmatch'ing an
142 * otherwise applicable "non-labeled" policy. This
143 * would prevent inadvertent "leaks".
147 rc = avc_has_perm(fl_secid, sel_sid, SECCLASS_ASSOCIATION,
148 ASSOCIATION__POLMATCH,
158 * LSM hook implementation that authorizes that a state matches
159 * the given policy, flow combo.
162 int selinux_xfrm_state_pol_flow_match(struct xfrm_state *x, struct xfrm_policy *xp,
163 const struct flowi *fl)
170 /* unlabeled policy and labeled SA can't match */
173 /* unlabeled policy and unlabeled SA match all flows */
177 /* unlabeled SA and labeled policy can't match */
180 if (!selinux_authorizable_xfrm(x))
181 /* Not a SELinux-labeled SA */
184 state_sid = x->security->ctx_sid;
186 if (fl->flowi_secid != state_sid)
189 rc = avc_has_perm(fl->flowi_secid, state_sid, SECCLASS_ASSOCIATION,
194 * We don't need a separate SA Vs. policy polmatch check
195 * since the SA is now of the same label as the flow and
196 * a flow Vs. policy polmatch check had already happened
197 * in selinux_xfrm_policy_lookup() above.
204 * LSM hook implementation that checks and/or returns the xfrm sid for the
208 int selinux_xfrm_decode_session(struct sk_buff *skb, u32 *sid, int ckall)
221 for (i = sp->len-1; i >= 0; i--) {
222 struct xfrm_state *x = sp->xvec[i];
223 if (selinux_authorizable_xfrm(x)) {
224 struct xfrm_sec_ctx *ctx = x->security;
232 } else if (*sid != ctx->ctx_sid)
242 * LSM hook implementation that allocs and transfers uctx spec to
245 int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx **ctxp,
246 struct xfrm_user_sec_ctx *uctx)
248 return selinux_xfrm_alloc_user(ctxp, uctx);
253 * LSM hook implementation that copies security data structure from old to
254 * new for policy cloning.
256 int selinux_xfrm_policy_clone(struct xfrm_sec_ctx *old_ctx,
257 struct xfrm_sec_ctx **new_ctxp)
259 struct xfrm_sec_ctx *new_ctx;
262 new_ctx = kmalloc(sizeof(*old_ctx) + old_ctx->ctx_len,
267 memcpy(new_ctx, old_ctx, sizeof(*new_ctx));
268 memcpy(new_ctx->ctx_str, old_ctx->ctx_str, new_ctx->ctx_len);
269 atomic_inc(&selinux_xfrm_refcount);
276 * LSM hook implementation that frees xfrm_sec_ctx security information.
278 void selinux_xfrm_policy_free(struct xfrm_sec_ctx *ctx)
280 atomic_dec(&selinux_xfrm_refcount);
285 * LSM hook implementation that authorizes deletion of labeled policies.
287 int selinux_xfrm_policy_delete(struct xfrm_sec_ctx *ctx)
289 const struct task_security_struct *tsec = current_security();
294 return avc_has_perm(tsec->sid, ctx->ctx_sid,
295 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
300 * LSM hook implementation that allocates a xfrm_sec_state, populates it using
301 * the supplied security context, and assigns it to the xfrm_state.
303 int selinux_xfrm_state_alloc(struct xfrm_state *x,
304 struct xfrm_user_sec_ctx *uctx)
306 return selinux_xfrm_alloc_user(&x->security, uctx);
310 * LSM hook implementation that allocates a xfrm_sec_state and populates based
313 int selinux_xfrm_state_alloc_acquire(struct xfrm_state *x,
314 struct xfrm_sec_ctx *polsec, u32 secid)
317 struct xfrm_sec_ctx *ctx;
318 char *ctx_str = NULL;
327 rc = security_sid_to_context(secid, &ctx_str, &str_len);
331 ctx = kmalloc(sizeof(*ctx) + str_len, GFP_ATOMIC);
335 ctx->ctx_doi = XFRM_SC_DOI_LSM;
336 ctx->ctx_alg = XFRM_SC_ALG_SELINUX;
337 ctx->ctx_sid = secid;
338 ctx->ctx_len = str_len;
339 memcpy(ctx->ctx_str, ctx_str, str_len);
343 atomic_inc(&selinux_xfrm_refcount);
348 * LSM hook implementation that frees xfrm_state security information.
350 void selinux_xfrm_state_free(struct xfrm_state *x)
352 atomic_dec(&selinux_xfrm_refcount);
357 * LSM hook implementation that authorizes deletion of labeled SAs.
359 int selinux_xfrm_state_delete(struct xfrm_state *x)
361 const struct task_security_struct *tsec = current_security();
362 struct xfrm_sec_ctx *ctx = x->security;
367 return avc_has_perm(tsec->sid, ctx->ctx_sid,
368 SECCLASS_ASSOCIATION, ASSOCIATION__SETCONTEXT,
373 * LSM hook that controls access to unlabelled packets. If
374 * a xfrm_state is authorizable (defined by macro) then it was
375 * already authorized by the IPSec process. If not, then
376 * we need to check for unlabelled access since this may not have
377 * gone thru the IPSec process.
379 int selinux_xfrm_sock_rcv_skb(u32 isec_sid, struct sk_buff *skb,
380 struct common_audit_data *ad)
384 u32 sel_sid = SECINITSID_UNLABELED;
389 for (i = 0; i < sp->len; i++) {
390 struct xfrm_state *x = sp->xvec[i];
392 if (x && selinux_authorizable_xfrm(x)) {
393 struct xfrm_sec_ctx *ctx = x->security;
394 sel_sid = ctx->ctx_sid;
401 * This check even when there's no association involved is
402 * intended, according to Trent Jaeger, to make sure a
403 * process can't engage in non-ipsec communication unless
404 * explicitly allowed by policy.
407 rc = avc_has_perm(isec_sid, sel_sid, SECCLASS_ASSOCIATION,
408 ASSOCIATION__RECVFROM, ad);
414 * POSTROUTE_LAST hook's XFRM processing:
415 * If we have no security association, then we need to determine
416 * whether the socket is allowed to send to an unlabelled destination.
417 * If we do have a authorizable security association, then it has already been
418 * checked in the selinux_xfrm_state_pol_flow_match hook above.
420 int selinux_xfrm_postroute_last(u32 isec_sid, struct sk_buff *skb,
421 struct common_audit_data *ad, u8 proto)
423 struct dst_entry *dst;
429 struct dst_entry *dst_test;
431 for (dst_test = dst; dst_test != NULL;
432 dst_test = dst_test->child) {
433 struct xfrm_state *x = dst_test->xfrm;
435 if (x && selinux_authorizable_xfrm(x))
445 * We should have already seen this packet once before
446 * it underwent xfrm(s). No need to subject it to the
455 * This check even when there's no association involved is
456 * intended, according to Trent Jaeger, to make sure a
457 * process can't engage in non-ipsec communication unless
458 * explicitly allowed by policy.
461 rc = avc_has_perm(isec_sid, SECINITSID_UNLABELED, SECCLASS_ASSOCIATION,
462 ASSOCIATION__SENDTO, ad);