1 /*-
2 * Copyright (c) 2005 Wayne J. Salamon
3 * All rights reserved.
4 *
5 * This software was developed by Wayne Salamon for the TrustedBSD Project.
6 *
7 * Redistribution and use in source and binary forms, with or without
8 * modification, are permitted provided that the following conditions
9 * are met:
10 * 1. Redistributions of source code must retain the above copyright
11 * notice, this list of conditions and the following disclaimer.
12 * 2. Redistributions in binary form must reproduce the above copyright
13 * notice, this list of conditions and the following disclaimer in the
14 * documentation and/or other materials provided with the distribution.
15 *
16 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
17 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
18 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
19 * ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
20 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
21 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
22 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
23 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
24 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
25 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
26 * SUCH DAMAGE.
27 */
28
29 #include <sys/cdefs.h>
30 __FBSDID("$FreeBSD$");
31
32 #include <sys/param.h>
33 #include <sys/conf.h>
34 #include <sys/kernel.h>
35 #include <sys/lock.h>
36 #include <sys/malloc.h>
37 #include <sys/mutex.h>
38 #include <sys/proc.h>
39 #include <sys/queue.h>
40 #include <sys/systm.h>
41 #include <sys/uio.h>
42
43 #include <security/audit/audit.h>
44 #include <security/audit/audit_private.h>
45
46 /*
47 * Structures and operations to support the basic character special device
48 * used to communicate with userland. /dev/audit reliably delivers one-byte
49 * messages to a listening application (or discards them if there is no
50 * listening application).
51 *
52 * Currently, select/poll are not supported on the trigger device.
53 */
54 struct trigger_info {
55 unsigned int trigger;
56 TAILQ_ENTRY(trigger_info) list;
57 };
58
59 static MALLOC_DEFINE(M_AUDITTRIGGER, "audit_trigger", "Audit trigger events");
60 static struct cdev *audit_dev;
61 static int audit_isopen = 0;
62 static TAILQ_HEAD(, trigger_info) trigger_list;
63 static struct mtx audit_trigger_mtx;
64
65 static int
66 audit_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
67 {
68 int error;
69
70 /* Only one process may open the device at a time. */
71 mtx_lock(&audit_trigger_mtx);
72 if (!audit_isopen) {
73 error = 0;
74 audit_isopen = 1;
75 } else
76 error = EBUSY;
77 mtx_unlock(&audit_trigger_mtx);
78
79 return (error);
80 }
81
82 static int
83 audit_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
84 {
85 struct trigger_info *ti;
86
87 /* Flush the queue of pending trigger events. */
88 mtx_lock(&audit_trigger_mtx);
89 audit_isopen = 0;
90 while (!TAILQ_EMPTY(&trigger_list)) {
91 ti = TAILQ_FIRST(&trigger_list);
92 TAILQ_REMOVE(&trigger_list, ti, list);
93 free(ti, M_AUDITTRIGGER);
94 }
95 mtx_unlock(&audit_trigger_mtx);
96
97 return (0);
98 }
99
100 static int
101 audit_read(struct cdev *dev, struct uio *uio, int ioflag)
102 {
103 int error = 0;
104 struct trigger_info *ti = NULL;
105
106 mtx_lock(&audit_trigger_mtx);
107 while (TAILQ_EMPTY(&trigger_list)) {
108 error = msleep(&trigger_list, &audit_trigger_mtx,
109 PSOCK | PCATCH, "auditd", 0);
110 if (error)
111 break;
112 }
113 if (!error) {
114 ti = TAILQ_FIRST(&trigger_list);
115 TAILQ_REMOVE(&trigger_list, ti, list);
116 }
117 mtx_unlock(&audit_trigger_mtx);
118 if (!error) {
119 error = uiomove(&ti->trigger, sizeof(ti->trigger), uio);
120 free(ti, M_AUDITTRIGGER);
121 }
122 return (error);
123 }
124
125 static int
126 audit_write(struct cdev *dev, struct uio *uio, int ioflag)
127 {
128
129 /* Communication is kernel->userspace only. */
130 return (EOPNOTSUPP);
131 }
132
133 int
134 audit_send_trigger(unsigned int trigger)
135 {
136 struct trigger_info *ti;
137
138 ti = malloc(sizeof *ti, M_AUDITTRIGGER, M_WAITOK);
139 mtx_lock(&audit_trigger_mtx);
140 if (!audit_isopen) {
141 /* If nobody's listening, we ain't talking. */
142 mtx_unlock(&audit_trigger_mtx);
143 free(ti, M_AUDITTRIGGER);
144 return (ENODEV);
145 }
146 ti->trigger = trigger;
147 TAILQ_INSERT_TAIL(&trigger_list, ti, list);
148 wakeup(&trigger_list);
149 mtx_unlock(&audit_trigger_mtx);
150 return (0);
151 }
152
153 static struct cdevsw audit_cdevsw = {
154 .d_version = D_VERSION,
155 .d_open = audit_open,
156 .d_close = audit_close,
157 .d_read = audit_read,
158 .d_write = audit_write,
159 .d_name = "audit"
160 };
161
162 void
163 audit_trigger_init(void)
164 {
165
166 TAILQ_INIT(&trigger_list);
167 mtx_init(&audit_trigger_mtx, "audit_trigger_mtx", NULL, MTX_DEF);
168 }
169
170 static void
171 audit_trigger_cdev_init(void *unused)
172 {
173
174 /* Create the special device file. */
175 audit_dev = make_dev(&audit_cdevsw, 0, UID_ROOT, GID_KMEM, 0600,
176 AUDITDEV_FILENAME);
177 }
178
179 SYSINIT(audit_trigger_cdev_init, SI_SUB_DRIVERS, SI_ORDER_MIDDLE,
180 audit_trigger_cdev_init, NULL);
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