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 * $FreeBSD$ 29 */ 30 31 #include <sys/param.h> 32 #include <sys/conf.h> 33 #include <sys/kernel.h> 34 #include <sys/malloc.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 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 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 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, sizeof *ti, uio); 117 free(ti, M_AUDITTRIGGER); 118 } 119 return (error); 120 } 121 122 static int 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 131 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 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 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