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 static SECURITY_READ_ONLY_LATE(zone_t) zone_label;
41 ZONE_INIT(&zone_label, "MAC Labels", sizeof(struct label),
42 ZC_READONLY | ZC_ZFREE_CLEARMEM, ZONE_ID_MAC_LABEL, NULL);
43
44 #define MAC_LABEL_NULL_SLOT (void *)~0ULL
45
46 /*
47 * Number of initial values matches logic in security/_label.h
48 */
49 static const struct label empty_label = {
50 .l_perpolicy = {
51 /* at least 3 */
52 MAC_LABEL_NULL_SLOT,
53 MAC_LABEL_NULL_SLOT,
54 MAC_LABEL_NULL_SLOT,
55 #if defined(XNU_TARGET_OS_OSX)
56 /* +4 for macOS = 7 */
57 MAC_LABEL_NULL_SLOT,
58 MAC_LABEL_NULL_SLOT,
59 MAC_LABEL_NULL_SLOT,
60 MAC_LABEL_NULL_SLOT,
61 #elif CONFIG_VNGUARD
62 /* otherwise, +1 for vnguard = 4 */
63 MAC_LABEL_NULL_SLOT,
64 #endif
65 }
66 };
67
68 static struct label *
label_alloc_noinit(int flags)69 label_alloc_noinit(int flags)
70 {
71 static_assert(MAC_NOWAIT == Z_NOWAIT);
72 return zalloc_ro(ZONE_ID_MAC_LABEL, Z_ZERO | (flags & MAC_NOWAIT));
73 }
74
75 struct label *
mac_labelzone_alloc(int flags)76 mac_labelzone_alloc(int flags)
77 {
78 struct label *label;
79
80 label = label_alloc_noinit(flags);
81 if (label) {
82 struct label tmp_label = empty_label;
83 zalloc_ro_update_elem(ZONE_ID_MAC_LABEL, label, &tmp_label);
84 }
85
86 return label;
87 }
88
89 struct label *
90 mac_labelzone_alloc_for_owner(struct label **labelp, int flags,
91 void (^extra_setup)(struct label *))
92 {
93 struct label *label;
94
95 if (labelp) {
96 struct label tmp_label = empty_label;
97
98 label = zalloc_ro(ZONE_ID_MAC_LABEL, Z_ZERO | (flags & MAC_NOWAIT));
99
100 tmp_label.l_owner = labelp;
101 zalloc_ro_update_elem(ZONE_ID_MAC_LABEL, label, &tmp_label);
102 } else {
103 label = mac_labelzone_alloc(flags);
104 }
105
106 if (label && extra_setup) {
107 extra_setup(label);
108 }
109
110 return label;
111 }
112
113 struct label *
114 mac_labelzone_alloc_owned(struct label **labelp, int flags,
115 void (^extra_setup)(struct label *))
116 {
117 struct label *label;
118
119 label = mac_labelzone_alloc_for_owner(labelp, flags, extra_setup);
120
121 if (labelp) {
122 *labelp = label;
123 }
124
125 return label;
126 }
127
128 void
mac_labelzone_free(struct label * label)129 mac_labelzone_free(struct label *label)
130 {
131 if (label == NULL) {
132 panic("Free of NULL MAC label");
133 }
134
135 zfree_ro(ZONE_ID_MAC_LABEL, label);
136 }
137
138 void
139 mac_labelzone_free_owned(struct label **labelp,
140 void (^extra_deinit)(struct label *))
141 {
142 struct label *label;
143
144 label = mac_label_verify(labelp);
145 if (label) {
146 if (extra_deinit) {
147 extra_deinit(label);
148 }
149
150 *labelp = NULL;
151 mac_labelzone_free(label);
152 }
153 }
154
155 __abortlike
156 static void
mac_label_verify_panic(struct label ** labelp)157 mac_label_verify_panic(struct label **labelp)
158 {
159 panic("label backref mismatch: labelp:%p label:%p l_owner:%p", labelp,
160 *labelp, (*labelp)->l_owner);
161 }
162
163 struct label *
mac_label_verify(struct label ** labelp)164 mac_label_verify(struct label **labelp)
165 {
166 struct label *label = *labelp;
167
168 if (label != NULL) {
169 zone_require_ro(ZONE_ID_MAC_LABEL, sizeof(struct label), label);
170
171 if (__improbable(label->l_owner != labelp)) {
172 mac_label_verify_panic(labelp);
173 }
174 }
175
176 return label;
177 }
178
179 static intptr_t
mac_label_slot_encode(intptr_t p)180 mac_label_slot_encode(intptr_t p)
181 {
182 return (p == 0) ? (intptr_t)MAC_LABEL_NULL_SLOT : p;
183 }
184
185 static intptr_t
mac_label_slot_decode(intptr_t p)186 mac_label_slot_decode(intptr_t p)
187 {
188 return (p == (intptr_t)MAC_LABEL_NULL_SLOT) ? 0 : p;
189 }
190
191 /*
192 * Functions used by policy modules to get and set label values.
193 */
194 intptr_t
mac_label_get(struct label * label,int slot)195 mac_label_get(struct label *label, int slot)
196 {
197 KASSERT(label != NULL, ("mac_label_get: NULL label"));
198
199 zone_require_ro(ZONE_ID_MAC_LABEL, sizeof(struct label), label);
200 return mac_label_slot_decode((intptr_t) label->l_perpolicy[slot]);
201 }
202
203 __abortlike
204 static void
panic_label_set_sentinel(void)205 panic_label_set_sentinel(void)
206 {
207 panic("cannot set mac label to ~0");
208 }
209
210 void
mac_label_set(struct label * label,int slot,intptr_t v)211 mac_label_set(struct label *label, int slot, intptr_t v)
212 {
213 KASSERT(label != NULL, ("mac_label_set: NULL label"));
214
215 if (v == (intptr_t)MAC_LABEL_NULL_SLOT) {
216 panic_label_set_sentinel();
217 }
218
219 v = mac_label_slot_encode(v);
220 zalloc_ro_update_field(ZONE_ID_MAC_LABEL, label, l_perpolicy[slot],
221 (void **)&v);
222 }
223