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/config.h>
30 #include <linux/module.h>
31 #include <linux/kernel.h>
32 #include <linux/init.h>
33 #include <linux/security.h>
34 #include <linux/types.h>
35 #include <linux/netfilter.h>
36 #include <linux/netfilter_ipv4.h>
37 #include <linux/netfilter_ipv6.h>
39 #include <linux/tcp.h>
40 #include <linux/skbuff.h>
41 #include <linux/xfrm.h>
43 #include <net/checksum.h>
45 #include <asm/semaphore.h>
53 * Returns true if an LSM/SELinux context
55 static inline int selinux_authorizable_ctx(struct xfrm_sec_ctx
*ctx
)
58 (ctx
->ctx_doi
== XFRM_SC_DOI_LSM
) &&
59 (ctx
->ctx_alg
== XFRM_SC_ALG_SELINUX
));
63 * Returns true if the xfrm contains a security blob for SELinux
65 static inline int selinux_authorizable_xfrm(struct xfrm_state
*x
)
67 return selinux_authorizable_ctx(x
->security
);
71 * LSM hook implementation that authorizes that a socket can be used
72 * with the corresponding xfrm_sec_ctx and direction.
74 int selinux_xfrm_policy_lookup(struct xfrm_policy
*xp
, u32 sk_sid
, u8 dir
)
77 u32 sel_sid
= SECINITSID_UNLABELED
;
78 struct xfrm_sec_ctx
*ctx
;
80 /* Context sid is either set to label or ANY_ASSOC */
81 if ((ctx
= xp
->security
)) {
82 if (!selinux_authorizable_ctx(ctx
))
85 sel_sid
= ctx
->ctx_sid
;
88 rc
= avc_has_perm(sk_sid
, sel_sid
, SECCLASS_ASSOCIATION
,
89 ((dir
== FLOW_DIR_IN
) ? ASSOCIATION__RECVFROM
:
90 ((dir
== FLOW_DIR_OUT
) ? ASSOCIATION__SENDTO
:
91 (ASSOCIATION__SENDTO
| ASSOCIATION__RECVFROM
))),
98 * Security blob allocation for xfrm_policy and xfrm_state
99 * CTX does not have a meaningful value on input
101 static int selinux_xfrm_sec_ctx_alloc(struct xfrm_sec_ctx
**ctxp
, struct xfrm_user_sec_ctx
*uctx
)
104 struct task_security_struct
*tsec
= current
->security
;
105 struct xfrm_sec_ctx
*ctx
;
108 BUG_ON(uctx
->ctx_doi
!= XFRM_SC_ALG_SELINUX
);
110 if (uctx
->ctx_len
>= PAGE_SIZE
)
113 *ctxp
= ctx
= kmalloc(sizeof(*ctx
) +
120 ctx
->ctx_doi
= uctx
->ctx_doi
;
121 ctx
->ctx_len
= uctx
->ctx_len
;
122 ctx
->ctx_alg
= uctx
->ctx_alg
;
127 rc
= security_context_to_sid(ctx
->ctx_str
,
135 * Does the subject have permission to set security or permission to
137 * Must be permitted to relabel from default socket type (process type)
138 * to specified context
140 rc
= avc_has_perm(tsec
->sid
, tsec
->sid
,
141 SECCLASS_ASSOCIATION
,
142 ASSOCIATION__RELABELFROM
, NULL
);
146 rc
= avc_has_perm(tsec
->sid
, ctx
->ctx_sid
,
147 SECCLASS_ASSOCIATION
,
148 ASSOCIATION__RELABELTO
, NULL
);
161 * LSM hook implementation that allocs and transfers uctx spec to
164 int selinux_xfrm_policy_alloc(struct xfrm_policy
*xp
, struct xfrm_user_sec_ctx
*uctx
)
170 err
= selinux_xfrm_sec_ctx_alloc(&xp
->security
, uctx
);
176 * LSM hook implementation that copies security data structure from old to
177 * new for policy cloning.
179 int selinux_xfrm_policy_clone(struct xfrm_policy
*old
, struct xfrm_policy
*new)
181 struct xfrm_sec_ctx
*old_ctx
, *new_ctx
;
183 old_ctx
= old
->security
;
186 new_ctx
= new->security
= kmalloc(sizeof(*new_ctx
) +
193 memcpy(new_ctx
, old_ctx
, sizeof(*new_ctx
));
194 memcpy(new_ctx
->ctx_str
, old_ctx
->ctx_str
, new_ctx
->ctx_len
);
200 * LSM hook implementation that frees xfrm_policy security information.
202 void selinux_xfrm_policy_free(struct xfrm_policy
*xp
)
204 struct xfrm_sec_ctx
*ctx
= xp
->security
;
210 * LSM hook implementation that allocs and transfers sec_ctx spec to
213 int selinux_xfrm_state_alloc(struct xfrm_state
*x
, struct xfrm_user_sec_ctx
*uctx
)
219 err
= selinux_xfrm_sec_ctx_alloc(&x
->security
, uctx
);
224 * LSM hook implementation that frees xfrm_state security information.
226 void selinux_xfrm_state_free(struct xfrm_state
*x
)
228 struct xfrm_sec_ctx
*ctx
= x
->security
;
234 * LSM hook that controls access to unlabelled packets. If
235 * a xfrm_state is authorizable (defined by macro) then it was
236 * already authorized by the IPSec process. If not, then
237 * we need to check for unlabelled access since this may not have
238 * gone thru the IPSec process.
240 int selinux_xfrm_sock_rcv_skb(u32 isec_sid
, struct sk_buff
*skb
)
249 * __xfrm_policy_check does not approve unless xfrm_policy_ok
250 * says that spi's match for policy and the socket.
252 * Only need to verify the existence of an authorizable sp.
254 for (i
= 0; i
< sp
->len
; i
++) {
255 struct xfrm_state
*x
= sp
->x
[i
].xvec
;
257 if (x
&& selinux_authorizable_xfrm(x
))
262 /* check SELinux sock for unlabelled access */
263 rc
= avc_has_perm(isec_sid
, SECINITSID_UNLABELED
, SECCLASS_ASSOCIATION
,
264 ASSOCIATION__RECVFROM
, NULL
);
276 * POSTROUTE_LAST hook's XFRM processing:
277 * If we have no security association, then we need to determine
278 * whether the socket is allowed to send to an unlabelled destination.
279 * If we do have a authorizable security association, then it has already been
280 * checked in xfrm_policy_lookup hook.
282 int selinux_xfrm_postroute_last(u32 isec_sid
, struct sk_buff
*skb
)
284 struct dst_entry
*dst
;
290 struct dst_entry
*dst_test
;
292 for (dst_test
= dst
; dst_test
!= 0;
293 dst_test
= dst_test
->child
) {
294 struct xfrm_state
*x
= dst_test
->xfrm
;
296 if (x
&& selinux_authorizable_xfrm(x
))
301 rc
= avc_has_perm(isec_sid
, SECINITSID_UNLABELED
, SECCLASS_ASSOCIATION
,
302 ASSOCIATION__SENDTO
, NULL
);