521 lines
13 KiB
C
521 lines
13 KiB
C
/*-
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* SPDX-License-Identifier: BSD-2-Clause
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*
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* Copyright (c) 2011, David E. O'Brien.
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* Copyright (c) 2009-2011, Juniper Networks, Inc.
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* Copyright (c) 2015-2016, EMC Corp.
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* All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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*
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* THIS SOFTWARE IS PROVIDED BY JUNIPER NETWORKS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL JUNIPER NETWORKS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*/
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#include <sys/cdefs.h>
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#include <sys/param.h>
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#include <sys/file.h>
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#include <sys/systm.h>
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#include <sys/buf.h>
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#include <sys/capsicum.h>
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#include <sys/condvar.h>
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#include <sys/conf.h>
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#include <sys/fcntl.h>
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#include <sys/ioccom.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/malloc.h>
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#include <sys/module.h>
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#include <sys/poll.h>
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#include <sys/proc.h>
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#include <sys/sx.h>
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#include <sys/syscall.h>
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#include <sys/sysent.h>
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#include <sys/sysproto.h>
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#include <sys/uio.h>
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#include "filemon.h"
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#if defined(COMPAT_FREEBSD32)
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#include <compat/freebsd32/freebsd32_syscall.h>
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#include <compat/freebsd32/freebsd32_proto.h>
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#include <compat/freebsd32/freebsd32_util.h>
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#endif
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static d_close_t filemon_close;
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static d_ioctl_t filemon_ioctl;
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static d_open_t filemon_open;
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static struct cdevsw filemon_cdevsw = {
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.d_version = D_VERSION,
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.d_close = filemon_close,
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.d_ioctl = filemon_ioctl,
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.d_open = filemon_open,
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.d_name = "filemon",
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};
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MALLOC_DECLARE(M_FILEMON);
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MALLOC_DEFINE(M_FILEMON, "filemon", "File access monitor");
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/*
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* The filemon->lock protects several things currently:
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* - fname1/fname2/msgbufr are pre-allocated and used per syscall
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* for logging and copyins rather than stack variables.
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* - Serializing the filemon's log output.
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* - Preventing inheritance or removal of the filemon into proc.p_filemon.
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*/
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struct filemon {
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struct sx lock; /* Lock for this filemon. */
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struct file *fp; /* Output file pointer. */
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struct ucred *cred; /* Credential of tracer. */
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char fname1[MAXPATHLEN]; /* Temporary filename buffer. */
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char fname2[MAXPATHLEN]; /* Temporary filename buffer. */
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char msgbufr[2*MAXPATHLEN + 100]; /* Output message buffer. */
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int error; /* Log write error, returned on close(2). */
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u_int refcnt; /* Pointer reference count. */
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u_int proccnt; /* Process count. */
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};
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static struct cdev *filemon_dev;
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static void filemon_output(struct filemon *filemon, char *msg, size_t len);
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static __inline struct filemon *
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filemon_acquire(struct filemon *filemon)
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{
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if (filemon != NULL)
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refcount_acquire(&filemon->refcnt);
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return (filemon);
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}
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/*
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* Release a reference and free on the last one.
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*/
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static void
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filemon_release(struct filemon *filemon)
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{
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if (refcount_release(&filemon->refcnt) == 0)
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return;
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/*
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* There are valid cases of releasing while locked, such as in
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* filemon_untrack_processes, but none which are done where there
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* is not at least 1 reference remaining.
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*/
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sx_assert(&filemon->lock, SA_UNLOCKED);
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if (filemon->cred != NULL)
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crfree(filemon->cred);
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sx_destroy(&filemon->lock);
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free(filemon, M_FILEMON);
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}
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/*
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* Acquire the proc's p_filemon reference and lock the filemon.
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* The proc's p_filemon may not match this filemon on return.
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*/
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static struct filemon *
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filemon_proc_get(struct proc *p)
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{
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struct filemon *filemon;
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if (p->p_filemon == NULL)
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return (NULL);
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PROC_LOCK(p);
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filemon = filemon_acquire(p->p_filemon);
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PROC_UNLOCK(p);
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if (filemon == NULL)
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return (NULL);
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/*
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* The p->p_filemon may have changed by now. That case is handled
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* by the exit and fork hooks and filemon_attach_proc specially.
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*/
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sx_xlock(&filemon->lock);
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return (filemon);
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}
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/* Remove and release the filemon on the given process. */
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static void
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filemon_proc_drop(struct proc *p)
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{
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struct filemon *filemon;
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KASSERT(p->p_filemon != NULL, ("%s: proc %p NULL p_filemon",
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__func__, p));
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sx_assert(&p->p_filemon->lock, SA_XLOCKED);
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PROC_LOCK(p);
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filemon = p->p_filemon;
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p->p_filemon = NULL;
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--filemon->proccnt;
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PROC_UNLOCK(p);
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/*
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* This should not be the last reference yet. filemon_release()
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* cannot be called with filemon locked, which the caller expects
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* will stay locked.
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*/
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KASSERT(filemon->refcnt > 1, ("%s: proc %p dropping filemon %p "
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"with last reference", __func__, p, filemon));
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filemon_release(filemon);
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}
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/* Unlock and release the filemon. */
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static __inline void
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filemon_drop(struct filemon *filemon)
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{
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sx_xunlock(&filemon->lock);
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filemon_release(filemon);
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}
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#include "filemon_wrapper.c"
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static void
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filemon_write_header(struct filemon *filemon)
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{
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int len;
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struct timeval now;
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getmicrotime(&now);
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len = snprintf(filemon->msgbufr, sizeof(filemon->msgbufr),
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"# filemon version %d\n# Target pid %d\n# Start %ju.%06ju\nV %d\n",
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FILEMON_VERSION, curproc->p_pid, (uintmax_t)now.tv_sec,
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(uintmax_t)now.tv_usec, FILEMON_VERSION);
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if (len < sizeof(filemon->msgbufr))
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filemon_output(filemon, filemon->msgbufr, len);
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}
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/*
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* Invalidate the passed filemon in all processes.
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*/
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static void
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filemon_untrack_processes(struct filemon *filemon)
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{
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struct proc *p;
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sx_assert(&filemon->lock, SA_XLOCKED);
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/* Avoid allproc loop if there is no need. */
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if (filemon->proccnt == 0)
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return;
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/*
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* Processes in this list won't go away while here since
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* filemon_event_process_exit() will lock on filemon->lock
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* which we hold.
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*/
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sx_slock(&allproc_lock);
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FOREACH_PROC_IN_SYSTEM(p) {
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/*
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* No PROC_LOCK is needed to compare here since it is
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* guaranteed to not change since we have its filemon
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* locked. Everything that changes this p_filemon will
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* be locked on it.
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*/
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if (p->p_filemon == filemon)
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filemon_proc_drop(p);
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}
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sx_sunlock(&allproc_lock);
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/*
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* It's possible some references were acquired but will be
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* dropped shortly as they are restricted from being
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* inherited. There is at least the reference in cdevpriv remaining.
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*/
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KASSERT(filemon->refcnt > 0, ("%s: filemon %p should have "
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"references still.", __func__, filemon));
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KASSERT(filemon->proccnt == 0, ("%s: filemon %p should not have "
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"attached procs still.", __func__, filemon));
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}
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/*
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* Close out the log.
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*/
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static void
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filemon_close_log(struct filemon *filemon)
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{
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struct file *fp;
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struct timeval now;
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size_t len;
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sx_assert(&filemon->lock, SA_XLOCKED);
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if (filemon->fp == NULL)
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return;
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getmicrotime(&now);
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len = snprintf(filemon->msgbufr,
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sizeof(filemon->msgbufr),
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"# Stop %ju.%06ju\n# Bye bye\n",
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(uintmax_t)now.tv_sec, (uintmax_t)now.tv_usec);
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if (len < sizeof(filemon->msgbufr))
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filemon_output(filemon, filemon->msgbufr, len);
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fp = filemon->fp;
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filemon->fp = NULL;
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sx_xunlock(&filemon->lock);
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fdrop(fp, curthread);
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sx_xlock(&filemon->lock);
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}
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/*
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* The devfs file is being closed. Untrace all processes. It is possible
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* filemon_close/close(2) was not called.
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*/
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static void
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filemon_dtr(void *data)
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{
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struct filemon *filemon = data;
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if (filemon == NULL)
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return;
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sx_xlock(&filemon->lock);
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/*
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* Detach the filemon. It cannot be inherited after this.
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*/
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filemon_untrack_processes(filemon);
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filemon_close_log(filemon);
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filemon_drop(filemon);
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}
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/* Attach the filemon to the process. */
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static int
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filemon_attach_proc(struct filemon *filemon, struct proc *p)
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{
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struct filemon *filemon2;
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sx_assert(&filemon->lock, SA_XLOCKED);
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PROC_LOCK_ASSERT(p, MA_OWNED);
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KASSERT((p->p_flag & P_WEXIT) == 0,
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("%s: filemon %p attaching to exiting process %p",
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__func__, filemon, p));
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KASSERT((p->p_flag & P_INEXEC) == 0,
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("%s: filemon %p attaching to execing process %p",
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__func__, filemon, p));
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if (p->p_filemon == filemon)
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return (0);
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/*
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* Don't allow truncating other process traces. It is
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* not really intended to trace procs other than curproc
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* anyhow.
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*/
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if (p->p_filemon != NULL && p != curproc)
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return (EBUSY);
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/*
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* Historic behavior of filemon has been to let a child initiate
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* tracing on itself and cease existing tracing. Bmake
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* .META + .MAKE relies on this. It is only relevant for attaching to
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* curproc.
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*/
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while (p->p_filemon != NULL) {
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PROC_UNLOCK(p);
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sx_xunlock(&filemon->lock);
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while ((filemon2 = filemon_proc_get(p)) != NULL) {
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/* It may have changed. */
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if (p->p_filemon == filemon2)
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filemon_proc_drop(p);
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filemon_drop(filemon2);
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}
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sx_xlock(&filemon->lock);
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PROC_LOCK(p);
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/*
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* It may have been attached to, though unlikely.
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* Try again if needed.
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*/
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}
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KASSERT(p->p_filemon == NULL,
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("%s: proc %p didn't detach filemon %p", __func__, p,
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p->p_filemon));
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p->p_filemon = filemon_acquire(filemon);
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++filemon->proccnt;
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return (0);
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}
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static int
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filemon_ioctl(struct cdev *dev, u_long cmd, caddr_t data, int flag __unused,
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struct thread *td)
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{
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struct filemon *filemon;
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struct file *fp;
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struct proc *p;
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int error;
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if ((error = devfs_get_cdevpriv((void **) &filemon)) != 0)
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return (error);
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sx_xlock(&filemon->lock);
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switch (cmd) {
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/* Set the output file descriptor. */
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case FILEMON_SET_FD:
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if (filemon->fp != NULL) {
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error = EEXIST;
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break;
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}
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error = fget_write(td, *(int *)data, &cap_pwrite_rights, &fp);
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if (error == 0) {
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/*
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* The filemon handle may be passed to another process,
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* so the underlying file handle must support this.
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*/
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if ((fp->f_ops->fo_flags & DFLAG_PASSABLE) == 0) {
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fdrop(fp, curthread);
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error = EINVAL;
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break;
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}
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filemon->fp = fp;
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/* Write the file header. */
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filemon_write_header(filemon);
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}
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break;
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/* Set the monitored process ID. */
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case FILEMON_SET_PID:
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/* Invalidate any existing processes already set. */
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filemon_untrack_processes(filemon);
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error = pget(*((pid_t *)data),
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PGET_CANDEBUG | PGET_NOTWEXIT | PGET_NOTINEXEC, &p);
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if (error == 0) {
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KASSERT(p->p_filemon != filemon,
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("%s: proc %p didn't untrack filemon %p",
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__func__, p, filemon));
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error = filemon_attach_proc(filemon, p);
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PROC_UNLOCK(p);
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}
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break;
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default:
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error = EINVAL;
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break;
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}
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sx_xunlock(&filemon->lock);
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return (error);
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}
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static int
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filemon_open(struct cdev *dev, int oflags __unused, int devtype __unused,
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struct thread *td)
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{
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int error;
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struct filemon *filemon;
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filemon = malloc(sizeof(*filemon), M_FILEMON,
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M_WAITOK | M_ZERO);
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sx_init(&filemon->lock, "filemon");
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refcount_init(&filemon->refcnt, 1);
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filemon->cred = crhold(td->td_ucred);
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error = devfs_set_cdevpriv(filemon, filemon_dtr);
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if (error != 0)
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filemon_release(filemon);
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return (error);
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}
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/* Called on close of last devfs file handle, before filemon_dtr(). */
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static int
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filemon_close(struct cdev *dev __unused, int flag __unused, int fmt __unused,
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struct thread *td __unused)
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{
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struct filemon *filemon;
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int error;
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if ((error = devfs_get_cdevpriv((void **) &filemon)) != 0)
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return (error);
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sx_xlock(&filemon->lock);
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filemon_close_log(filemon);
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error = filemon->error;
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sx_xunlock(&filemon->lock);
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/*
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* Processes are still being traced but won't log anything
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* now. After this call returns filemon_dtr() is called which
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* will detach processes.
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*/
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return (error);
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}
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static void
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filemon_load(void *dummy __unused)
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{
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/* Install the syscall wrappers. */
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filemon_wrapper_install();
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filemon_dev = make_dev(&filemon_cdevsw, 0, UID_ROOT, GID_WHEEL, 0666,
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"filemon");
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}
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static int
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filemon_unload(void)
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{
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destroy_dev(filemon_dev);
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filemon_wrapper_deinstall();
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return (0);
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}
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static int
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filemon_modevent(module_t mod __unused, int type, void *data)
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{
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int error = 0;
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switch (type) {
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case MOD_LOAD:
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filemon_load(data);
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break;
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case MOD_UNLOAD:
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error = filemon_unload();
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break;
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case MOD_QUIESCE:
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/*
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* The wrapper implementation is unsafe for reliable unload.
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* Require forcing an unload.
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*/
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error = EBUSY;
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break;
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case MOD_SHUTDOWN:
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break;
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default:
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error = EOPNOTSUPP;
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break;
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}
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return (error);
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}
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DEV_MODULE(filemon, filemon_modevent, NULL);
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MODULE_VERSION(filemon, 1);
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