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 * Copyright (C) 2005 International Business Machines Corporation
11 * This program is free software; you can redistribute it and/or modify
12 * it under the terms of the GNU General Public License version 2,
13 * as published by the Free Software Foundation.
19 * 1. Make sure to enable the following options in your kernel config:
21 * CONFIG_SECURITY_NETWORK=y
22 * CONFIG_SECURITY_NETWORK_XFRM=y
23 * CONFIG_SECURITY_SELINUX=m/y
25 * 1. Caching packets, so they are not dropped during negotiation
26 * 2. Emulating a reasonable SO_PEERSEC across machines
27 * 3. Testing addition of sk_policy's with security context via setsockopt
29 #include <linux/module.h>
30 #include <linux/kernel.h>
31 #include <linux/init.h>
32 #include <linux/security.h>
33 #include <linux/types.h>
34 #include <linux/netfilter.h>
35 #include <linux/netfilter_ipv4.h>
36 #include <linux/netfilter_ipv6.h>
38 #include <linux/tcp.h>
39 #include <linux/skbuff.h>
40 #include <linux/xfrm.h>
42 #include <net/checksum.h>
44 #include <asm/semaphore.h>
52 * Returns true if an LSM/SELinux context
54 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx
*ctx
)
57 (ctx
->ctx_doi
== XFRM_SC_DOI_LSM
) &&
58 (ctx
->ctx_alg
== XFRM_SC_ALG_SELINUX
));
62 * Returns true if the xfrm contains a security blob for SELinux
64 static inline int selinux_authorizable_xfrm(struct xfrm_state
*x
)
66 return selinux_authorizable_ctx(x
->security
);
70 * LSM hook implementation that authorizes that a socket can be used
71 * with the corresponding xfrm_sec_ctx and direction.
73 int selinux_xfrm_policy_lookup(struct xfrm_policy
*xp
, u32 sk_sid
, u8 dir
)
76 u32 sel_sid
= SECINITSID_UNLABELED
;
77 struct xfrm_sec_ctx
*ctx
;
79 /* Context sid is either set to label or ANY_ASSOC */
80 if ((ctx
= xp
->security
)) {
81 if (!selinux_authorizable_ctx(ctx
))
84 sel_sid
= ctx
->ctx_sid
;
87 rc
= avc_has_perm(sk_sid
, sel_sid
, SECCLASS_ASSOCIATION
,
88 ((dir
== FLOW_DIR_IN
) ? ASSOCIATION__RECVFROM
:
89 ((dir
== FLOW_DIR_OUT
) ? ASSOCIATION__SENDTO
:
90 (ASSOCIATION__SENDTO
| ASSOCIATION__RECVFROM
))),
97 * Security blob allocation for xfrm_policy and xfrm_state
98 * CTX does not have a meaningful value on input
100 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx
**ctxp
, struct xfrm_user_sec_ctx
*uctx
)
103 struct task_security_struct
*tsec
= current
->security
;
104 struct xfrm_sec_ctx
*ctx
;
107 BUG_ON(uctx
->ctx_doi
!= XFRM_SC_ALG_SELINUX
);
109 if (uctx
->ctx_len
>= PAGE_SIZE
)
112 *ctxp
= ctx
= kmalloc(sizeof(*ctx
) +
119 ctx
->ctx_doi
= uctx
->ctx_doi
;
120 ctx
->ctx_len
= uctx
->ctx_len
;
121 ctx
->ctx_alg
= uctx
->ctx_alg
;
126 rc
= security_context_to_sid(ctx
->ctx_str
,
134 * Does the subject have permission to set security context?
136 rc
= avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
137 SECCLASS_ASSOCIATION
,
138 ASSOCIATION__SETCONTEXT
, NULL
);
151 * LSM hook implementation that allocs and transfers uctx spec to
154 int selinux_xfrm_policy_alloc(struct xfrm_policy
*xp
, struct xfrm_user_sec_ctx
*uctx
)
160 err
= selinux_xfrm_sec_ctx_alloc(&xp
->security
, uctx
);
166 * LSM hook implementation that copies security data structure from old to
167 * new for policy cloning.
169 int selinux_xfrm_policy_clone(struct xfrm_policy
*old
, struct xfrm_policy
*new)
171 struct xfrm_sec_ctx
*old_ctx
, *new_ctx
;
173 old_ctx
= old
->security
;
176 new_ctx
= new->security
= kmalloc(sizeof(*new_ctx
) +
183 memcpy(new_ctx
, old_ctx
, sizeof(*new_ctx
));
184 memcpy(new_ctx
->ctx_str
, old_ctx
->ctx_str
, new_ctx
->ctx_len
);
190 * LSM hook implementation that frees xfrm_policy security information.
192 void selinux_xfrm_policy_free(struct xfrm_policy
*xp
)
194 struct xfrm_sec_ctx
*ctx
= xp
->security
;
200 * LSM hook implementation that authorizes deletion of labeled policies.
202 int selinux_xfrm_policy_delete(struct xfrm_policy
*xp
)
204 struct task_security_struct
*tsec
= current
->security
;
205 struct xfrm_sec_ctx
*ctx
= xp
->security
;
209 rc
= avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
210 SECCLASS_ASSOCIATION
,
211 ASSOCIATION__SETCONTEXT
, NULL
);
217 * LSM hook implementation that allocs and transfers sec_ctx spec to
220 int selinux_xfrm_state_alloc(struct xfrm_state
*x
, struct xfrm_user_sec_ctx
*uctx
)
226 err
= selinux_xfrm_sec_ctx_alloc(&x
->security
, uctx
);
231 * LSM hook implementation that frees xfrm_state security information.
233 void selinux_xfrm_state_free(struct xfrm_state
*x
)
235 struct xfrm_sec_ctx
*ctx
= x
->security
;
241 * SELinux internal function to retrieve the context of a connected
242 * (sk->sk_state == TCP_ESTABLISHED) TCP socket based on its security
243 * association used to connect to the remote socket.
245 * Retrieve via getsockopt SO_PEERSEC.
247 u32
selinux_socket_getpeer_stream(struct sock
*sk
)
249 struct dst_entry
*dst
, *dst_test
;
250 u32 peer_sid
= SECSID_NULL
;
252 if (sk
->sk_state
!= TCP_ESTABLISHED
)
255 dst
= sk_dst_get(sk
);
259 for (dst_test
= dst
; dst_test
!= 0;
260 dst_test
= dst_test
->child
) {
261 struct xfrm_state
*x
= dst_test
->xfrm
;
263 if (x
&& selinux_authorizable_xfrm(x
)) {
264 struct xfrm_sec_ctx
*ctx
= x
->security
;
265 peer_sid
= ctx
->ctx_sid
;
276 * SELinux internal function to retrieve the context of a UDP packet
277 * based on its security association used to connect to the remote socket.
279 * Retrieve via setsockopt IP_PASSSEC and recvmsg with control message
282 u32
selinux_socket_getpeer_dgram(struct sk_buff
*skb
)
289 if (skb
->sk
->sk_protocol
!= IPPROTO_UDP
)
296 for (i
= sp
->len
-1; i
>= 0; i
--) {
297 struct xfrm_state
*x
= sp
->xvec
[i
];
298 if (selinux_authorizable_xfrm(x
)) {
299 struct xfrm_sec_ctx
*ctx
= x
->security
;
309 * LSM hook implementation that authorizes deletion of labeled SAs.
311 int selinux_xfrm_state_delete(struct xfrm_state
*x
)
313 struct task_security_struct
*tsec
= current
->security
;
314 struct xfrm_sec_ctx
*ctx
= x
->security
;
318 rc
= avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
319 SECCLASS_ASSOCIATION
,
320 ASSOCIATION__SETCONTEXT
, NULL
);
326 * LSM hook that controls access to unlabelled packets. If
327 * a xfrm_state is authorizable (defined by macro) then it was
328 * already authorized by the IPSec process. If not, then
329 * we need to check for unlabelled access since this may not have
330 * gone thru the IPSec process.
332 int selinux_xfrm_sock_rcv_skb(u32 isec_sid
, struct sk_buff
*skb
)
341 * __xfrm_policy_check does not approve unless xfrm_policy_ok
342 * says that spi's match for policy and the socket.
344 * Only need to verify the existence of an authorizable sp.
346 for (i
= 0; i
< sp
->len
; i
++) {
347 struct xfrm_state
*x
= sp
->xvec
[i
];
349 if (x
&& selinux_authorizable_xfrm(x
))
354 /* check SELinux sock for unlabelled access */
355 rc
= avc_has_perm(isec_sid
, SECINITSID_UNLABELED
, SECCLASS_ASSOCIATION
,
356 ASSOCIATION__RECVFROM
, NULL
);
368 * POSTROUTE_LAST hook's XFRM processing:
369 * If we have no security association, then we need to determine
370 * whether the socket is allowed to send to an unlabelled destination.
371 * If we do have a authorizable security association, then it has already been
372 * checked in xfrm_policy_lookup hook.
374 int selinux_xfrm_postroute_last(u32 isec_sid
, struct sk_buff
*skb
)
376 struct dst_entry
*dst
;
382 struct dst_entry
*dst_test
;
384 for (dst_test
= dst
; dst_test
!= 0;
385 dst_test
= dst_test
->child
) {
386 struct xfrm_state
*x
= dst_test
->xfrm
;
388 if (x
&& selinux_authorizable_xfrm(x
))
393 rc
= avc_has_perm(isec_sid
, SECINITSID_UNLABELED
, SECCLASS_ASSOCIATION
,
394 ASSOCIATION__SENDTO
, NULL
);