FreeBSD/Linux Kernel Cross Reference
sys/security/audit/audit_trigger.c

     /*-
      * Copyright (c) 2005 Wayne J. Salamon
      * All rights reserved.
      *
      * This software was developed by Wayne Salamon for the TrustedBSD Project.
      *
      * Redistribution and use in source and binary forms, with or without
      * modification, are permitted provided that the following conditions
      * are met:
     * 1. Redistributions of source code must retain the above copyright
     *    notice, this list of conditions and the following disclaimer.
     * 2. Redistributions in binary form must reproduce the above copyright
     *    notice, this list of conditions and the following disclaimer in the
     *    documentation and/or other materials provided with the distribution.
     *
     * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
     * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
     * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
     * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
     * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
     * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
     * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
     * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
     * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
     * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
     * SUCH DAMAGE.
     *
     * $FreeBSD$
     */
    
    #include <sys/param.h>
    #include <sys/conf.h>
    #include <sys/kernel.h>
    #include <sys/malloc.h>
    #include <sys/proc.h>
    #include <sys/queue.h>
    #include <sys/systm.h>
    #include <sys/uio.h>
    
    #include <security/audit/audit.h>
    #include <security/audit/audit_private.h>
    
    /*
     * Structures and operations to support the basic character special device
     * used to communicate with userland.  /dev/audit reliably delivers one-byte
     * messages to a listening application (or discards them if there is no
     * listening application).
     *
     * Currently, select/poll are not supported on the trigger device.
     */
    struct trigger_info {
            unsigned int                    trigger;
            TAILQ_ENTRY(trigger_info)       list;
    };
    
    static MALLOC_DEFINE(M_AUDITTRIGGER, "audit_trigger", "Audit trigger events");
    static struct cdev *audit_dev;
    static int audit_isopen = 0;
    static TAILQ_HEAD(, trigger_info) trigger_list;
    static struct mtx audit_trigger_mtx;
    
    static int
    audit_open(struct cdev *dev, int oflags, int devtype, struct thread *td)
    {
            int error;
    
            /* Only one process may open the device at a time. */
            mtx_lock(&audit_trigger_mtx);
            if (!audit_isopen) {
                    error = 0;
                    audit_isopen = 1;
            } else
                    error = EBUSY;
            mtx_unlock(&audit_trigger_mtx);
    
            return (error);
    }
    
    static int
    audit_close(struct cdev *dev, int fflag, int devtype, struct thread *td)
    {
            struct trigger_info *ti;
    
            /* Flush the queue of pending trigger events. */
            mtx_lock(&audit_trigger_mtx);
            audit_isopen = 0;
            while (!TAILQ_EMPTY(&trigger_list)) {
                    ti = TAILQ_FIRST(&trigger_list);
                    TAILQ_REMOVE(&trigger_list, ti, list);
                    free(ti, M_AUDITTRIGGER);
            }
            mtx_unlock(&audit_trigger_mtx);
    
            return (0);
    }
    
    static int
    audit_read(struct cdev *dev, struct uio *uio, int ioflag)
    {
           int error = 0;
           struct trigger_info *ti = NULL;
   
           mtx_lock(&audit_trigger_mtx);
           while (TAILQ_EMPTY(&trigger_list)) {
                   error = msleep(&trigger_list, &audit_trigger_mtx,
                       PSOCK | PCATCH, "auditd", 0);
                   if (error)
                           break;
           }
           if (!error) {
                   ti = TAILQ_FIRST(&trigger_list);
                   TAILQ_REMOVE(&trigger_list, ti, list);
           }
           mtx_unlock(&audit_trigger_mtx);
           if (!error) {
                   error = uiomove(ti, sizeof *ti, uio);
                   free(ti, M_AUDITTRIGGER);
           }
           return (error);
   }
   
   static int
   audit_write(struct cdev *dev, struct uio *uio, int ioflag)
   {
   
           /* Communication is kernel->userspace only. */
           return (EOPNOTSUPP);
   }
   
   int
   send_trigger(unsigned int trigger)
   {
           struct trigger_info *ti;
   
           ti = malloc(sizeof *ti, M_AUDITTRIGGER, M_WAITOK);
           mtx_lock(&audit_trigger_mtx);
           if (!audit_isopen) {
                   /* If nobody's listening, we ain't talking. */
                   mtx_unlock(&audit_trigger_mtx);
                   free(ti, M_AUDITTRIGGER);
                   return (ENODEV);
           }
           ti->trigger = trigger;
           TAILQ_INSERT_TAIL(&trigger_list, ti, list);
           wakeup(&trigger_list);
           mtx_unlock(&audit_trigger_mtx);
           return (0);
   }
   
   static struct cdevsw audit_cdevsw = {
           .d_version =    D_VERSION,
           .d_open =       audit_open,
           .d_close =      audit_close,
           .d_read =       audit_read,
           .d_write =      audit_write,
           .d_name =       "audit"
   };
   
   void
   audit_trigger_init(void)
   {
   
           TAILQ_INIT(&trigger_list);
           mtx_init(&audit_trigger_mtx, "audit_trigger_mtx", NULL, MTX_DEF);
   }
   
   static void
   audit_trigger_cdev_init(void *unused)
   {
   
           /* Create the special device file. */
           audit_dev = make_dev(&audit_cdevsw, 0, UID_ROOT, GID_KMEM, 0600,
               AUDITDEV_FILENAME);
   }
   
   SYSINIT(audit_trigger_cdev_init, SI_SUB_DRIVERS, SI_ORDER_MIDDLE,
       audit_trigger_cdev_init, NULL);

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