4039c53163
Code may still be executing from the wrappers at unload time and thus is not generally safe to unload. Converting the wrappers to use EVENTHANDLER(9) will allow this to safely drain on active threads in hooks. More work on EVENTHANDLER(9) is needed first. MFC after: 1 week Sponsored by: EMC / Isilon Storage Division
200 lines
5.0 KiB
Groff
200 lines
5.0 KiB
Groff
.\" Copyright (c) 2012
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.\" David E. O'Brien <obrien@FreeBSD.org>. 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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.\" 3. All advertising materials mentioning features or use of this software
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.\" must display the following acknowledgment:
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.\" This product includes software developed by David E. O'Brien and
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.\" contributors.
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.\" 4. Neither the name of the author nor the names of its contributors
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.\" may be used to endorse or promote products derived from this software
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.\" without specific prior written permission.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR 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 MERCHANT ABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR 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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.\" $FreeBSD$
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.\"
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.Dd January 28, 2016
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.Dt FILEMON 4
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.Os
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.Sh NAME
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.Nm filemon
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.Nd the filemon device
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.Sh SYNOPSIS
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.In dev/filemon/filemon.h
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.Sh DESCRIPTION
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The
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.Nm
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device allows a process to collect file operations data of its children.
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The device
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.Pa /dev/filemon
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responds to two
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.Xr ioctl 2
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calls.
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.Pp
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.Nm
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is not intended to be a security auditing tool.
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Many syscalls are not tracked and binaries of foreign ABI will not be fully
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audited.
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It is intended for auditing of processes for the purpose of determining its
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dependencies in an efficient and easily parsable format.
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An example of this is
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.Xr make 1
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which uses this module with
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.Sy .MAKE.MODE=meta
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to handle incremental builds more smartly.
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.Pp
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System calls are denoted using the following single letters:
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.Pp
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.Bl -tag -width indent -compact
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.It Ql C
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.Xr chdir 2
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.It Ql D
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.Xr unlink 2
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.It Ql E
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.Xr exec 2
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.It Ql F
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.Xr fork 2 ,
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.Xr vfork 2
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.It Ql L
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.Xr link 2 ,
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.Xr linkat 2 ,
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.Xr symlink 2 ,
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.Xr symlinkat 2
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.It Ql M
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.Xr rename 2
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.It Ql R
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.Xr open 2
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for read
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.It Ql S
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.Xr stat 2
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.It Ql W
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.Xr open 2
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for write
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.It Ql X
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.Xr _exit 2
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.El
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.Pp
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Note that
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.Ql R
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following
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.Ql W
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records can represent a single
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.Xr open 2
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for R/W,
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or two separate
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.Xr open 2
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calls, one for
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.Ql R
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and one for
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.Ql W .
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Note that only successful system calls are captured.
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.Sh IOCTLS
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User mode programs communicate with the
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.Nm
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driver through a number of ioctls which are described below.
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Each takes a single argument.
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.Bl -tag -width ".Dv FILEMON_SET_PID"
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.It Dv FILEMON_SET_FD
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Write the internal tracing buffer to the supplied open file descriptor.
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.It Dv FILEMON_SET_PID
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Child process ID to trace.
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.El
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.Sh RETURN VALUES
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.\" .Rv -std ioctl
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The
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.Fn ioctl
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function returns the value 0 if successful;
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otherwise the value \-1 is returned and the global variable
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.Va errno
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is set to indicate the error.
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.Sh FILES
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.Bl -tag -width ".Pa /dev/filemon"
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.It Pa /dev/filemon
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.El
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.Sh EXAMPLES
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.Bd -literal
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#include <sys/types.h>
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#include <sys/stat.h>
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#include <sys/wait.h>
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#include <sys/ioctl.h>
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#include <dev/filemon/filemon.h>
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#include <fcntl.h>
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#include <err.h>
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#include <unistd.h>
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static void
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open_filemon(void)
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{
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pid_t child;
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int fm_fd, fm_log;
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if ((fm_fd = open("/dev/filemon", O_RDWR | O_CLOEXEC)) == -1)
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err(1, "open(\e"/dev/filemon\e", O_RDWR)");
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if ((fm_log = open("filemon.out",
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O_CREAT | O_WRONLY | O_TRUNC | O_CLOEXEC, DEFFILEMODE)) == -1)
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err(1, "open(filemon.out)");
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if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
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err(1, "Cannot set filemon log file descriptor");
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if ((child = fork()) == 0) {
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child = getpid();
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if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
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err(1, "Cannot set filemon PID");
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/* Do something here. */
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} else {
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wait(&child);
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close(fm_fd);
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}
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}
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.Ed
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.Pp
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Creates a file named
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.Pa filemon.out
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and configures the
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.Nm
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device to write the
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.Nm
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buffer contents to it.
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.Sh SEE ALSO
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.Xr dtrace 1 ,
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.Xr ktrace 1 ,
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.Xr script 1 ,
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.Xr truss 1 ,
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.Xr ioctl 2
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.Sh HISTORY
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A
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.Nm
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device appeared in
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.Fx 9.1 .
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.Sh BUGS
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Loading
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.Nm
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may reduce system performance for the noted syscalls.
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.Pp
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Only children of the set process are logged.
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Processes can escape being traced by double forking.
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This is not seen as a problem as the intended use is build monitoring, which
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does not make sense to have daemons for.
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.Pp
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Unloading the module may panic the system, thus requires using
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.Ic kldunload -f .
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