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 * LSM hook implementation that authorizes that a flow can use
80 int selinux_xfrm_policy_lookup(struct xfrm_sec_ctx
*ctx
, u32 fl_secid
, u8 dir
)
85 /* Context sid is either set to label or ANY_ASSOC */
87 if (!selinux_authorizable_ctx(ctx
))
90 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
,
115 const struct flowi
*fl
)
122 /* unlabeled policy and labeled SA can't match */
125 /* unlabeled policy and unlabeled SA match all flows */
129 /* unlabeled SA and labeled policy can't match */
132 if (!selinux_authorizable_xfrm(x
))
133 /* Not a SELinux-labeled SA */
136 state_sid
= x
->security
->ctx_sid
;
138 if (fl
->flowi_secid
!= state_sid
)
141 rc
= avc_has_perm(fl
->flowi_secid
, state_sid
, SECCLASS_ASSOCIATION
,
146 * We don't need a separate SA Vs. policy polmatch check
147 * since the SA is now of the same label as the flow and
148 * a flow Vs. policy polmatch check had already happened
149 * in selinux_xfrm_policy_lookup() above.
155 static int selinux_xfrm_skb_sid_ingress(struct sk_buff
*skb
,
158 struct sec_path
*sp
= skb
->sp
;
165 for (i
= sp
->len
-1; i
>= 0; i
--) {
166 struct xfrm_state
*x
= sp
->xvec
[i
];
167 if (selinux_authorizable_xfrm(x
)) {
168 struct xfrm_sec_ctx
*ctx
= x
->security
;
176 } else if (*sid
!= ctx
->ctx_sid
)
185 static u32
selinux_xfrm_skb_sid_egress(struct sk_buff
*skb
)
187 struct dst_entry
*dst
= skb_dst(skb
);
188 struct xfrm_state
*x
;
193 if (x
== NULL
|| !selinux_authorizable_xfrm(x
))
196 return x
->security
->ctx_sid
;
200 * LSM hook implementation that checks and/or returns the xfrm sid for the
204 int selinux_xfrm_decode_session(struct sk_buff
*skb
, u32
*sid
, int ckall
)
210 return selinux_xfrm_skb_sid_ingress(skb
, sid
, ckall
);
213 int selinux_xfrm_skb_sid(struct sk_buff
*skb
, u32
*sid
)
217 rc
= selinux_xfrm_skb_sid_ingress(skb
, sid
, 0);
218 if (rc
== 0 && *sid
== SECSID_NULL
)
219 *sid
= selinux_xfrm_skb_sid_egress(skb
);
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 const struct task_security_struct
*tsec
= current_security();
233 struct xfrm_sec_ctx
*ctx
= NULL
;
234 char *ctx_str
= NULL
;
242 if (uctx
->ctx_alg
!= XFRM_SC_ALG_SELINUX
)
245 str_len
= uctx
->ctx_len
;
246 if (str_len
>= PAGE_SIZE
)
249 *ctxp
= ctx
= kmalloc(sizeof(*ctx
) +
256 ctx
->ctx_doi
= uctx
->ctx_doi
;
257 ctx
->ctx_len
= str_len
;
258 ctx
->ctx_alg
= uctx
->ctx_alg
;
263 ctx
->ctx_str
[str_len
] = 0;
264 rc
= security_context_to_sid(ctx
->ctx_str
,
272 * Does the subject have permission to set security context?
274 rc
= avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
275 SECCLASS_ASSOCIATION
,
276 ASSOCIATION__SETCONTEXT
, NULL
);
283 rc
= security_sid_to_context(sid
, &ctx_str
, &str_len
);
287 *ctxp
= ctx
= kmalloc(sizeof(*ctx
) +
296 ctx
->ctx_doi
= XFRM_SC_DOI_LSM
;
297 ctx
->ctx_alg
= XFRM_SC_ALG_SELINUX
;
299 ctx
->ctx_len
= str_len
;
315 * LSM hook implementation that allocs and transfers uctx spec to
318 int selinux_xfrm_policy_alloc(struct xfrm_sec_ctx
**ctxp
,
319 struct xfrm_user_sec_ctx
*uctx
)
325 err
= selinux_xfrm_sec_ctx_alloc(ctxp
, uctx
, 0);
327 atomic_inc(&selinux_xfrm_refcount
);
334 * LSM hook implementation that copies security data structure from old to
335 * new for policy cloning.
337 int selinux_xfrm_policy_clone(struct xfrm_sec_ctx
*old_ctx
,
338 struct xfrm_sec_ctx
**new_ctxp
)
340 struct xfrm_sec_ctx
*new_ctx
;
343 new_ctx
= kmalloc(sizeof(*old_ctx
) + old_ctx
->ctx_len
,
348 memcpy(new_ctx
, old_ctx
, sizeof(*new_ctx
));
349 memcpy(new_ctx
->ctx_str
, old_ctx
->ctx_str
, new_ctx
->ctx_len
);
350 atomic_inc(&selinux_xfrm_refcount
);
357 * LSM hook implementation that frees xfrm_sec_ctx security information.
359 void selinux_xfrm_policy_free(struct xfrm_sec_ctx
*ctx
)
361 atomic_dec(&selinux_xfrm_refcount
);
366 * LSM hook implementation that authorizes deletion of labeled policies.
368 int selinux_xfrm_policy_delete(struct xfrm_sec_ctx
*ctx
)
370 const struct task_security_struct
*tsec
= current_security();
375 return avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
376 SECCLASS_ASSOCIATION
, ASSOCIATION__SETCONTEXT
,
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
);
393 atomic_inc(&selinux_xfrm_refcount
);
398 * LSM hook implementation that frees xfrm_state security information.
400 void selinux_xfrm_state_free(struct xfrm_state
*x
)
402 atomic_dec(&selinux_xfrm_refcount
);
407 * LSM hook implementation that authorizes deletion of labeled SAs.
409 int selinux_xfrm_state_delete(struct xfrm_state
*x
)
411 const struct task_security_struct
*tsec
= current_security();
412 struct xfrm_sec_ctx
*ctx
= x
->security
;
417 return avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
418 SECCLASS_ASSOCIATION
, ASSOCIATION__SETCONTEXT
,
423 * LSM hook that controls access to unlabelled packets. If
424 * a xfrm_state is authorizable (defined by macro) then it was
425 * already authorized by the IPSec process. If not, then
426 * we need to check for unlabelled access since this may not have
427 * gone thru the IPSec process.
429 int selinux_xfrm_sock_rcv_skb(u32 isec_sid
, struct sk_buff
*skb
,
430 struct common_audit_data
*ad
)
434 u32 sel_sid
= SECINITSID_UNLABELED
;
439 for (i
= 0; i
< sp
->len
; i
++) {
440 struct xfrm_state
*x
= sp
->xvec
[i
];
442 if (x
&& selinux_authorizable_xfrm(x
)) {
443 struct xfrm_sec_ctx
*ctx
= x
->security
;
444 sel_sid
= ctx
->ctx_sid
;
451 * This check even when there's no association involved is
452 * intended, according to Trent Jaeger, to make sure a
453 * process can't engage in non-ipsec communication unless
454 * explicitly allowed by policy.
457 rc
= avc_has_perm(isec_sid
, sel_sid
, SECCLASS_ASSOCIATION
,
458 ASSOCIATION__RECVFROM
, ad
);
464 * POSTROUTE_LAST hook's XFRM processing:
465 * If we have no security association, then we need to determine
466 * whether the socket is allowed to send to an unlabelled destination.
467 * If we do have a authorizable security association, then it has already been
468 * checked in the selinux_xfrm_state_pol_flow_match hook above.
470 int selinux_xfrm_postroute_last(u32 isec_sid
, struct sk_buff
*skb
,
471 struct common_audit_data
*ad
, u8 proto
)
473 struct dst_entry
*dst
;
479 struct dst_entry
*dst_test
;
481 for (dst_test
= dst
; dst_test
!= NULL
;
482 dst_test
= dst_test
->child
) {
483 struct xfrm_state
*x
= dst_test
->xfrm
;
485 if (x
&& selinux_authorizable_xfrm(x
))
495 * We should have already seen this packet once before
496 * it underwent xfrm(s). No need to subject it to the
505 * This check even when there's no association involved is
506 * intended, according to Trent Jaeger, to make sure a
507 * process can't engage in non-ipsec communication unless
508 * explicitly allowed by policy.
511 rc
= avc_has_perm(isec_sid
, SECINITSID_UNLABELED
, SECCLASS_ASSOCIATION
,
512 ASSOCIATION__SENDTO
, ad
);