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: releng/9.1/sys/security/audit/audit_trigger.c 180709 2008-07-22 16:44:48Z rwatson $");
31
32 #include <sys/param.h>
33 #include <sys/conf.h>
34 #include <sys/kernel.h>
35 #include <sys/malloc.h>
36 #include <sys/proc.h>
37 #include <sys/queue.h>
38 #include <sys/systm.h>
39 #include <sys/uio.h>
40
41 #include <security/audit/audit.h>
42 #include <security/audit/audit_private.h>
43
44 /*
45 * Structures and operations to support the basic character special device
46 * used to communicate with userland. /dev/audit reliably delivers one-byte
47 * messages to a listening application (or discards them if there is no
48 * listening application).
49 *
50 * Currently, select/poll are not supported on the trigger device.
51 */
52 struct trigger_info {
53 unsigned int trigger;
54 TAILQ_ENTRY(trigger_info) list;
55 };
56
57 static MALLOC_DEFINE(M_AUDITTRIGGER, "audit_trigger", "Audit trigger events");
58 static struct cdev *audit_dev;
59 static int audit_isopen = 0;
60 static TAILQ_HEAD(, trigger_info) trigger_list;
61 static struct mtx audit_trigger_mtx;
62
63 static int
64 audit_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
65 {
66 int error;
67
68 /* Only one process may open the device at a time. */
69 mtx_lock(&audit_trigger_mtx);
70 if (!audit_isopen) {
71 error = 0;
72 audit_isopen = 1;
73 } else
74 error = EBUSY;
75 mtx_unlock(&audit_trigger_mtx);
76
77 return (error);
78 }
79
80 static int
81 audit_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
82 {
83 struct trigger_info *ti;
84
85 /* Flush the queue of pending trigger events. */
86 mtx_lock(&audit_trigger_mtx);
87 audit_isopen = 0;
88 while (!TAILQ_EMPTY(&trigger_list)) {
89 ti = TAILQ_FIRST(&trigger_list);
90 TAILQ_REMOVE(&trigger_list, ti, list);
91 free(ti, M_AUDITTRIGGER);
92 }
93 mtx_unlock(&audit_trigger_mtx);
94
95 return (0);
96 }
97
98 static int
99 audit_read(struct cdev *dev, struct uio *uio, int ioflag)
100 {
101 int error = 0;
102 struct trigger_info *ti = NULL;
103
104 mtx_lock(&audit_trigger_mtx);
105 while (TAILQ_EMPTY(&trigger_list)) {
106 error = msleep(&trigger_list, &audit_trigger_mtx,
107 PSOCK | PCATCH, "auditd", 0);
108 if (error)
109 break;
110 }
111 if (!error) {
112 ti = TAILQ_FIRST(&trigger_list);
113 TAILQ_REMOVE(&trigger_list, ti, list);
114 }
115 mtx_unlock(&audit_trigger_mtx);
116 if (!error) {
117 error = uiomove(&ti->trigger, sizeof(ti->trigger), uio);
118 free(ti, M_AUDITTRIGGER);
119 }
120 return (error);
121 }
122
123 static int
124 audit_write(struct cdev *dev, struct uio *uio, int ioflag)
125 {
126
127 /* Communication is kernel->userspace only. */
128 return (EOPNOTSUPP);
129 }
130
131 int
132 audit_send_trigger(unsigned int trigger)
133 {
134 struct trigger_info *ti;
135
136 ti = malloc(sizeof *ti, M_AUDITTRIGGER, M_WAITOK);
137 mtx_lock(&audit_trigger_mtx);
138 if (!audit_isopen) {
139 /* If nobody's listening, we ain't talking. */
140 mtx_unlock(&audit_trigger_mtx);
141 free(ti, M_AUDITTRIGGER);
142 return (ENODEV);
143 }
144 ti->trigger = trigger;
145 TAILQ_INSERT_TAIL(&trigger_list, ti, list);
146 wakeup(&trigger_list);
147 mtx_unlock(&audit_trigger_mtx);
148 return (0);
149 }
150
151 static struct cdevsw audit_cdevsw = {
152 .d_version = D_VERSION,
153 .d_open = audit_open,
154 .d_close = audit_close,
155 .d_read = audit_read,
156 .d_write = audit_write,
157 .d_name = "audit"
158 };
159
160 void
161 audit_trigger_init(void)
162 {
163
164 TAILQ_INIT(&trigger_list);
165 mtx_init(&audit_trigger_mtx, "audit_trigger_mtx", NULL, MTX_DEF);
166 }
167
168 static void
169 audit_trigger_cdev_init(void *unused)
170 {
171
172 /* Create the special device file. */
173 audit_dev = make_dev(&audit_cdevsw, 0, UID_ROOT, GID_KMEM, 0600,
174 AUDITDEV_FILENAME);
175 }
176
177 SYSINIT(audit_trigger_cdev_init, SI_SUB_DRIVERS, SI_ORDER_MIDDLE,
178 audit_trigger_cdev_init, NULL);
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