2 .\" David E. O'Brien <obrien@FreeBSD.org>. All rights reserved.
4 .\" Redistribution and use in source and binary forms, with or without
5 .\" modification, are permitted provided that the following conditions
7 .\" 1. Redistributions of source code must retain the above copyright
8 .\" notice, this list of conditions and the following disclaimer.
9 .\" 2. Redistributions in binary form must reproduce the above copyright
10 .\" notice, this list of conditions and the following disclaimer in the
11 .\" documentation and/or other materials provided with the distribution.
12 .\" 3. All advertising materials mentioning features or use of this software
13 .\" must display the following acknowledgement:
14 .\" This product includes software developed by David E. O'Brien and
16 .\" 4. Neither the name of the author nor the names of its contributors
17 .\" may be used to endorse or promote products derived from this software
18 .\" without specific prior written permission.
20 .\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
21 .\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 .\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 .\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
24 .\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 .\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 .\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 .\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 .\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
39 .Nd the filemon device
41 .In dev/filemon/filemon.h
45 device allows a process to collect file operations data of its children.
53 is not intended to be a security auditing tool.
54 Many syscalls are not tracked and binaries of foreign ABI will not be fully
56 It is intended for auditing of processes for the purpose of determining its
57 dependencies in an efficient and easily parsable format.
60 which uses this module with
62 to handle incremental builds more smartly.
64 System calls are denoted using the following single letters:
66 .Bl -tag -width indent -compact
99 records can represent a single
109 User mode programs communicate with the
111 driver through a number of ioctls which are described below.
112 Each takes a single argument.
113 .Bl -tag -width ".Dv FILEMON_SET_PID"
114 .It Dv FILEMON_SET_FD
115 Write the internal tracing buffer to the supplied open file descriptor.
116 .It Dv FILEMON_SET_PID
117 Child process ID to trace.
123 function returns the value 0 if successful;
124 otherwise the value \-1 is returned and the global variable
126 is set to indicate the error.
128 .Bl -tag -width ".Pa /dev/filemon"
133 #include <sys/types.h>
134 #include <sys/stat.h>
135 #include <sys/wait.h>
136 #include <sys/ioctl.h>
137 #include <dev/filemon/filemon.h>
147 if ((fm_fd = open("/dev/filemon", O_RDWR)) == -1)
148 err(1, "open(\e"/dev/filemon\e", O_RDWR)");
149 if ((fm_log = open("filemon.out",
150 O_CREAT | O_WRONLY | O_TRUNC, DEFFILEMODE)) == -1)
151 err(1, "open(filemon.out)");
153 if (ioctl(fm_fd, FILEMON_SET_FD, &fm_log) == -1)
154 err(1, "Cannot set filemon log file descriptor");
155 /* Set up these two fd's to close on exec. */
156 (void)fcntl(fm_fd, F_SETFD, FD_CLOEXEC);
157 (void)fcntl(fm_log, F_SETFD, FD_CLOEXEC);
159 if ((child = fork()) == 0) {
161 if (ioctl(fm_fd, FILEMON_SET_PID, &child) == -1)
162 err(1, "Cannot set filemon PID");
163 /* Do something here. */
179 buffer contents to it.
192 may reduce system performance for the noted syscalls.
194 Only children of the set process are logged.
195 Processes can escape being traced by double forking.
196 This is not seen as a problem as the intended use is build monitoring, which
197 does not make sense to have daemons for.