1 /*-
2 * Copyright (c) 2004 Networks Associates Technology, Inc.
3 * Copyright (c) 2005 SPARTA, Inc.
4 * All rights reserved.
5 *
6 * This software was developed for the FreeBSD Project in part by Network
7 * Associates Laboratories, the Security Research Division of Network
8 * Associates, Inc. under DARPA/SPAWAR contract N66001-01-C-8035 ("CBOSS"),
9 * as part of the DARPA CHATS research program.
10 *
11 * Redistribution and use in source and binary forms, with or without
12 * modification, are permitted provided that the following conditions
13 * are met:
14 * 1. Redistributions of source code must retain the above copyright
15 * notice, this list of conditions and the following disclaimer.
16 * 2. Redistributions in binary form must reproduce the above copyright
17 * notice, this list of conditions and the following disclaimer in the
18 * documentation and/or other materials provided with the distribution.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33 #include <kern/zalloc.h>
34 #include <security/_label.h>
35 #include <sys/param.h>
36 #include <sys/queue.h>
37 #include <sys/systm.h>
38 #include <security/mac_internal.h>
39
40 ZONE_DEFINE_ID(ZONE_ID_MAC_LABEL, "MAC Labels", struct label,
41 ZC_READONLY | ZC_ZFREE_CLEARMEM);
42
43 /*
44 * Number of initial values matches logic in security/_label.h
45 */
46 const struct label empty_label = {
47 .l_perpolicy[0 ... MAC_MAX_SLOTS - 1] = MAC_LABEL_NULL_SLOT,
48 };
49
50 static struct label *
label_alloc_noinit(int flags)51 label_alloc_noinit(int flags)
52 {
53 static_assert(MAC_NOWAIT == Z_NOWAIT);
54 return zalloc_ro(ZONE_ID_MAC_LABEL, Z_ZERO | (flags & MAC_NOWAIT));
55 }
56
57 struct label *
mac_labelzone_alloc(int flags)58 mac_labelzone_alloc(int flags)
59 {
60 struct label *label;
61
62 label = label_alloc_noinit(flags);
63 if (label) {
64 zalloc_ro_update_elem(ZONE_ID_MAC_LABEL, label, &empty_label);
65 }
66
67 return label;
68 }
69
70 struct label *
71 mac_labelzone_alloc_for_owner(struct label **labelp, int flags,
72 void (^extra_setup)(struct label *))
73 {
74 struct label *label;
75
76 if (labelp) {
77 struct label tmp_label = empty_label;
78
79 label = zalloc_ro(ZONE_ID_MAC_LABEL, Z_ZERO | (flags & MAC_NOWAIT));
80
81 tmp_label.l_owner = labelp;
82 zalloc_ro_update_elem(ZONE_ID_MAC_LABEL, label, &tmp_label);
83 } else {
84 label = mac_labelzone_alloc(flags);
85 }
86
87 if (label && extra_setup) {
88 extra_setup(label);
89 }
90
91 return label;
92 }
93
94 struct label *
95 mac_labelzone_alloc_owned(struct label **labelp, int flags,
96 void (^extra_setup)(struct label *))
97 {
98 struct label *label;
99
100 label = mac_labelzone_alloc_for_owner(labelp, flags, extra_setup);
101
102 if (labelp) {
103 *labelp = label;
104 }
105
106 return label;
107 }
108
109 void
mac_labelzone_free(struct label * label)110 mac_labelzone_free(struct label *label)
111 {
112 if (label == NULL) {
113 panic("Free of NULL MAC label");
114 }
115
116 zfree_ro(ZONE_ID_MAC_LABEL, label);
117 }
118
119 void
120 mac_labelzone_free_owned(struct label **labelp,
121 void (^extra_deinit)(struct label *))
122 {
123 struct label *label;
124
125 label = mac_label_verify(labelp);
126 if (label) {
127 if (extra_deinit) {
128 extra_deinit(label);
129 }
130
131 *labelp = NULL;
132 mac_labelzone_free(label);
133 }
134 }
135
136 __abortlike
137 static void
mac_label_verify_panic(struct label ** labelp)138 mac_label_verify_panic(struct label **labelp)
139 {
140 panic("label backref mismatch: labelp:%p label:%p l_owner:%p", labelp,
141 *labelp, (*labelp)->l_owner);
142 }
143
144 struct label *
mac_label_verify(struct label ** labelp)145 mac_label_verify(struct label **labelp)
146 {
147 struct label *label = *labelp;
148
149 if (label != NULL) {
150 zone_require_ro(ZONE_ID_MAC_LABEL, sizeof(struct label), label);
151
152 if (__improbable(label->l_owner != labelp)) {
153 mac_label_verify_panic(labelp);
154 }
155 }
156
157 return label;
158 }
159
160 static intptr_t
mac_label_slot_encode(intptr_t p)161 mac_label_slot_encode(intptr_t p)
162 {
163 return p ?: MAC_LABEL_NULL_SLOT;
164 }
165
166 static intptr_t
mac_label_slot_decode(intptr_t p)167 mac_label_slot_decode(intptr_t p)
168 {
169 switch (p) {
170 case 0:
171 /* make sure 0 doesn't mean NULL and causes crashes */
172 return MAC_LABEL_NULL_SLOT;
173 case MAC_LABEL_NULL_SLOT:
174 return 0l;
175 default:
176 return p;
177 }
178 }
179
180 /*
181 * Functions used by policy modules to get and set label values.
182 */
183 intptr_t
mac_label_get(struct label * label,int slot)184 mac_label_get(struct label *label, int slot)
185 {
186 KASSERT(label != NULL, ("mac_label_get: NULL label"));
187
188 zone_require_ro(ZONE_ID_MAC_LABEL, sizeof(struct label), label);
189 return mac_label_slot_decode((intptr_t) label->l_perpolicy[slot]);
190 }
191
192 __abortlike
193 static void
panic_label_set_sentinel(void)194 panic_label_set_sentinel(void)
195 {
196 panic("cannot set mac label to ~0");
197 }
198
199 void
mac_label_set(struct label * label,int slot,intptr_t v)200 mac_label_set(struct label *label, int slot, intptr_t v)
201 {
202 KASSERT(label != NULL, ("mac_label_set: NULL label"));
203
204 #if DEVELOPMENT || DEBUG
205 /* can't modify a sealed label, see mac_cred_label_seal() */
206 assertf(label->l_owner != (struct label **)-1,
207 "mac_label_set(%p, %d, 0x%lx) is sealed",
208 label, slot, v);
209 #endif
210 if (v == MAC_LABEL_NULL_SLOT) {
211 panic_label_set_sentinel();
212 }
213 v = mac_label_slot_encode(v);
214 zalloc_ro_update_field(ZONE_ID_MAC_LABEL, label, l_perpolicy[slot], &v);
215 }
216