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