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); 181