xref: /freebsd/sys/security/mac_ifoff/mac_ifoff.c (revision b1879975794772ee51f0b4865753364c7d7626c3)
1 /*-
2  * Copyright (c) 1999-2002, 2007 Robert N. M. Watson
3  * Copyright (c) 2001-2002 Networks Associates Technology, Inc.
4  * Copyright (c) 2006 SPARTA, Inc.
5  * All rights reserved.
6  *
7  * This software was developed by Robert Watson for the TrustedBSD Project.
8  *
9  * This software was developed for the FreeBSD Project in part by Network
10  * Associates Laboratories, the Security Research Division of Network
11  * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
12  * as part of the DARPA CHATS research program.
13  *
14  * This software was enhanced by SPARTA ISSO under SPAWAR contract
15  * N66001-04-C-6019 ("SEFOS").
16  *
17  * Redistribution and use in source and binary forms, with or without
18  * modification, are permitted provided that the following conditions
19  * are met:
20  * 1. Redistributions of source code must retain the above copyright
21  *    notice, this list of conditions and the following disclaimer.
22  * 2. Redistributions in binary form must reproduce the above copyright
23  *    notice, this list of conditions and the following disclaimer in the
24  *    documentation and/or other materials provided with the distribution.
25  *
26  * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
27  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
28  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
29  * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
30  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
31  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
32  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
33  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
34  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
35  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
36  * SUCH DAMAGE.
37  */
38 
39 /*
40  * Developed by the TrustedBSD Project.
41  *
42  * Limit access to interfaces until they are specifically administratively
43  * enabled.  Prevents protocol stack-driven packet leakage in unsafe
44  * environments.
45  */
46 
47 #include <sys/param.h>
48 #include <sys/kernel.h>
49 #include <sys/module.h>
50 #include <sys/mbuf.h>
51 #include <sys/socket.h>
52 #include <sys/sysctl.h>
53 
54 #include <net/if.h>
55 #include <net/if_var.h>
56 #include <net/if_types.h>
57 #include <net/bpfdesc.h>
58 
59 #include <security/mac/mac_policy.h>
60 
61 static SYSCTL_NODE(_security_mac, OID_AUTO, ifoff,
62     CTLFLAG_RW | CTLFLAG_MPSAFE, 0,
63     "TrustedBSD mac_ifoff policy controls");
64 
65 static int	ifoff_enabled = 1;
66 SYSCTL_INT(_security_mac_ifoff, OID_AUTO, enabled, CTLFLAG_RWTUN,
67     &ifoff_enabled, 0, "Enforce ifoff policy");
68 
69 static int	ifoff_lo_enabled = 1;
70 SYSCTL_INT(_security_mac_ifoff, OID_AUTO, lo_enabled, CTLFLAG_RWTUN,
71     &ifoff_lo_enabled, 0, "Enable loopback interfaces");
72 
73 static int	ifoff_other_enabled = 0;
74 SYSCTL_INT(_security_mac_ifoff, OID_AUTO, other_enabled, CTLFLAG_RWTUN,
75     &ifoff_other_enabled, 0, "Enable other interfaces");
76 
77 static int	ifoff_bpfrecv_enabled = 0;
78 SYSCTL_INT(_security_mac_ifoff, OID_AUTO, bpfrecv_enabled, CTLFLAG_RWTUN,
79     &ifoff_bpfrecv_enabled, 0, "Enable BPF reception even when interface "
80     "is disabled");
81 
82 static int
83 ifnet_check_outgoing(struct ifnet *ifp)
84 {
85 
86 	if (!ifoff_enabled)
87 		return (0);
88 
89 	if (ifoff_lo_enabled && if_gettype(ifp) == IFT_LOOP)
90 		return (0);
91 
92 	if (ifoff_other_enabled && if_gettype(ifp) != IFT_LOOP)
93 		return (0);
94 
95 	return (EPERM);
96 }
97 
98 static int
99 ifnet_check_incoming(struct ifnet *ifp, int viabpf)
100 {
101 	if (!ifoff_enabled)
102 		return (0);
103 
104 	if (ifoff_lo_enabled && if_gettype(ifp) == IFT_LOOP)
105 		return (0);
106 
107 	if (ifoff_other_enabled && if_gettype(ifp) != IFT_LOOP)
108 		return (0);
109 
110 	if (viabpf && ifoff_bpfrecv_enabled)
111 		return (0);
112 
113 	return (EPERM);
114 }
115 
116 /*
117  * Object-specific entry point implementations are sorted alphabetically by
118  * object type and then by operation.
119  */
120 static int
121 ifoff_bpfdesc_check_receive(struct bpf_d *d, struct label *dlabel,
122     struct ifnet *ifp, struct label *ifplabel)
123 {
124 
125 	return (ifnet_check_incoming(ifp, 1));
126 }
127 
128 static int
129 ifoff_ifnet_check_transmit(struct ifnet *ifp, struct label *ifplabel,
130     struct mbuf *m, struct label *mlabel)
131 {
132 
133 	return (ifnet_check_outgoing(ifp));
134 }
135 
136 static int
137 ifoff_inpcb_check_deliver(struct inpcb *inp, struct label *inplabel,
138     struct mbuf *m, struct label *mlabel)
139 {
140 
141 	M_ASSERTPKTHDR(m);
142 	if (m->m_pkthdr.rcvif != NULL)
143 		return (ifnet_check_incoming(m->m_pkthdr.rcvif, 0));
144 
145 	return (0);
146 }
147 
148 static int
149 ifoff_socket_check_deliver(struct socket *so, struct label *solabel,
150     struct mbuf *m, struct label *mlabel)
151 {
152 
153 	M_ASSERTPKTHDR(m);
154 	if (m->m_pkthdr.rcvif != NULL)
155 		return (ifnet_check_incoming(m->m_pkthdr.rcvif, 0));
156 
157 	return (0);
158 }
159 
160 static struct mac_policy_ops ifoff_ops =
161 {
162 	.mpo_bpfdesc_check_receive = ifoff_bpfdesc_check_receive,
163 	.mpo_ifnet_check_transmit = ifoff_ifnet_check_transmit,
164 	.mpo_inpcb_check_deliver = ifoff_inpcb_check_deliver,
165 	.mpo_socket_check_deliver = ifoff_socket_check_deliver,
166 };
167 
168 MAC_POLICY_SET(&ifoff_ops, mac_ifoff, "TrustedBSD MAC/ifoff",
169     MPC_LOADTIME_FLAG_UNLOADOK, NULL);
170