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1.1 marc 21:
1.20 rohee 22: <h2><font color="#e00000">Building an OpenBSD port</font></h2>
1.1 marc 23:
24: So you've just compiled your favorite software package on your
25: OpenBSD machine and you want to share your effort by turning
26: it into a standard port. What to do?
27: <p>
1.25 espie 28: The most important thing you can is to <strong>communicate</strong>.
29: Ask people on <a href="mailto:ports@openbsd.org">ports@openbsd.org</a>
30: if they are working on the same port. <em>Tell the original software
31: author about it</em>, including problems you may find. If licensing
32: information appears incorrect tell him. If you had to jump through
33: loops to make the port build, tell him what he can fix. If they are
1.32 deraadt 34: only developing on Linux and feel like ignoring the rest of the Unix
1.25 espie 35: world, try to make them change their view.
36: <p>
37: <strong>COMMUNICATION</strong> makes the difference between a successful
1.34 jufi 38: port and a port that will slowly be abandoned by everyone.
1.25 espie 39: <p>
1.9 marc 40: First look at the porting information on this page. Then check
41: out the referenced documents, especially the OpenBSD porting
1.26 espie 42: <a href="checklist.html">checklist</a>.
1.1 marc 43: <p>
1.9 marc 44: Test, then re-test, and finally test again!
45: <p>
46: Submit the port. Create a gzipped tarball of the port directory.
47: You can then either place it on a public FTP or HTTP server, sending
1.20 rohee 48: its address to <a href="mailto:ports@openbsd.org">ports@openbsd.org</a>
1.9 marc 49: or send the port mime encoded to the same address. Pick whichever
50: method works best for you.
1.35 ! naddy 51:
! 52: <h3><font color="#0000e0">Index of Porting Documentation</font></h3>
! 53: <ul>
! 54: <li><a href="#Avail">Available Porting Information</a></li>
! 55: <li><a href="#Policy">OpenBSD Porting Policy</a></li>
! 56: <li><a href="#Security">Security Recommendations</a></li>
! 57: <li><a href="#Generic">Generic Porting Hints</a></li>
! 58: <li><a href="#Other">Other Helpful Hints</a></li>
! 59: </ul>
! 60:
! 61: <h3><font color="#0000e0"><a name="Avail">Available Porting Information</a></font></h3>
1.1 marc 62: <ul>
63: <li>The file <code>/usr/share/mk/bsd.port.mk</code>. This is the
64: system ports makefile included at the end of each individual
65: port makefile. Read the comments at the start of the makefile.
66: They do a good job of describing the available make options.
67: <li>The
1.13 art 68: <a href="http://www.netbsd.org/Documentation/software/packages.html">
69: NetBSD Package System</a> documentation. This document describes
70: NetBSD's version of the FreeBSD ports system and is quite helpful.
1.33 naddy 71: <li>The
1.30 espie 72: <a href="http://www.freebsd.org/porters-handbook/index.html">FreeBSD
1.33 naddy 73: Porter's Handbook</a>. This is the FreeBSD porting bible.
1.26 espie 74: <li>OpenBSD porting <a href="checklist.html">checklist</a>.
1.29 espie 75: <li>Some differences from other BSD port systems, mostly a summary
76: of <a href="porting/diffs.html">infrastructure differences</a>.
77: <li><a href="audio-port.html">Porting audio applications to OpenBSD</a>.
1.1 marc 78: <li>The OpenBSD ports mailing list,
79: <a href="mailto:ports@openbsd.org">ports@OpenBSD.ORG</a>.
80: </ul>
1.35 ! naddy 81: <h3><font color="#0000e0"><a name="Policy">OpenBSD Porting Policy</a></font></h3>
1.1 marc 82: <ul>
1.24 rohee 83: <li>OpenBSD does NOT use <code>/usr/local/etc/rc.d</code>.<br>
1.7 espie 84: <code>/usr/local</code> is often shared between several machines
1.15 espie 85: thanks to NFS. For this reason, configuration files that are specific
86: to a given machine can't be stored under <code>/usr/local</code>,
87: <code>/etc</code> is the central repository for per machine
88: configuration files. Moreover, OpenBSD policy is to never update
89: files under <code>/etc</code> automatically. Ports that need some
90: specific boot setup should advise the administrator about what to do
91: instead of blindly installing files.
1.1 marc 92: <li>OpenBSD does NOT compress man pages.
93: <li>OpenBSD does NOT require <code>-lcrypt</code>.<br>
94: DES encryption is part of the standard <code>libc</code>.
1.10 espie 95: <li>OpenBSD is strongly security-oriented. You should read and understand
96: this page's <a href="#security">security section</a>.
1.24 rohee 97: <li>Be sure to add the <code>$OpenBSD$</code> CVS tag to
1.10 espie 98: the Makefile. If importing a port from another system be sure to
99: leave their tag in the Makefile, too. However, replace the FreeBSD
1.24 rohee 100: <code>$Id$</code> tag with the
101: <code>$FreeBSD$</code> tag.
1.10 espie 102: <li>The goal is to get all ported applications to support OpenBSD. To
103: achieve this goal you <strong>must</strong> feed any OpenBSD patches
104: back to the application maintainer.
105: </ul>
1.20 rohee 106: <a name=security></a>
1.35 ! naddy 107: <h3><font color="#0000e0"><a name="Security">Security Recommendations</a></font></h3>
1.10 espie 108: There are many security problems to worry about. If
1.2 marc 109: you are not absolutely sure of what you are doing please request
1.1 marc 110: help from the <a href="mailto:ports@openbsd.org">ports</a> mailing
111: list.
1.10 espie 112:
113: <ul>
1.20 rohee 114: <li>Do <em>not</em> use alpha or beta code when preparing a port. Use the
1.10 espie 115: latest regular or patch release.
116:
1.1 marc 117: <li>Any software to be installed as a server should be scanned
118: for buffer overflows, especially unsafe use of
119: <code>strcat/strcpy/strcmp/sprintf</code>. In general,
120: <code>sprintf</code> should be replaced with <code>snprintf</code>.
1.10 espie 121:
1.17 espie 122: <li>Never use filenames instead of true security. There are numerous race
1.10 espie 123: conditions where you don't have proper control. For instance, an attacker
124: who already has user privileges on your machines may replace files in
125: <code>/tmp</code> with symbolic links to more strategic files, such as
1.19 rohee 126: <code>/etc/master.passwd</code>.
1.16 espie 127:
128: <li>For instance, both <code>fopen</code> and <code>freopen</code>
129: <strong>create a new file or open an existing file</strong> for
130: writing. An attacker may create a symbolic link from
1.19 rohee 131: <code>/etc/master.passwd</code> to <code>/tmp/addrpool_dump</code>. The
1.16 espie 132: instant you open it, your password file is hosed. Yes, even with
133: an <code>unlink</code> right before. You only narrow the window
134: of opportunity. Use <code>open</code> with
1.22 rohee 135: <code>O_CREAT|O_EXCL</code> and <code>fdopen</code> instead.
1.15 espie 136:
1.16 espie 137: <li>Another very common problem is the <code>mktemp</code>
1.17 espie 138: function. Heed the warnings of the bsd linker about its uses.
1.15 espie 139: <strong>These must be fixed</strong>.
140: This is not quite as simple as <code>s/mktemp/mkstemp/g</code>. <br>
141: Refer to the <code>mktemp(3)</code> man page of OpenBSD current
142: for more indications.
143: Correct code using <code>mkstemp</code> includes the source to
144: <code>ed</code> or <code>mail</code>.
145: A rare instance of code that uses <code>mktemp</code> correctly
146: can be found in the <code>rsync</code> port.
1.10 espie 147:
148: <li>Just because you can read it doesn't mean you should. A well-known hole
149: of this nature was the <code>startx</code> problem. As a setuid program,
150: you could launch startx with any file as a script. If the file was not
151: a valid shell script, a syntax error message would follow, along with the
152: first line of the offending file, without any further permission check.
153: Pretty handy to grab the first line of a shadow passwd file, considering
1.12 deraadt 154: these often start with root entry. Do not open your file, and then do
155: an <code>fstat</code> on the open descriptor to check if you should have
1.15 espie 156: been able to open it (or the attacker will play with /dev/rst0 and rewind
1.12 deraadt 157: your tape) -- open it with the correct uid/gid/grouplist set.
1.10 espie 158:
159: <li>Don't use anything that forks a shell in setuid programs before dropping
1.15 espie 160: your privileges. This includes <code>popen</code> and
161: <code>system</code>.
1.10 espie 162: Use <code>fork</code>, <code>pipe</code> and <code>execve</code> instead.
163:
1.15 espie 164: <li>Pass open descriptors instead of filenames to other programs to
165: avoid race conditions. Even if a program does not accept file
166: descriptors, you can still use <code>/dev/fd/0</code>.
1.10 espie 167:
1.15 espie 168: <li>Access rights are attached to file descriptors. If you need setuid rights
1.10 espie 169: to open a file, open that file, then drop your privileges. You can still
170: access the open descriptor, but you have less to worry about. This is
171: double-edged: even after dropping privileges, you should still watch out
172: for those descriptors.
173:
174: <li>Avoid root setuid as much as you can. Basically, root can do anything,
1.15 espie 175: but root rights are very rarely needed, except maybe to create
176: socket ports with a number under 1024. It is arguably better to
177: keep that under <code>inetd</code>
1.10 espie 178: control and just add the relevant entries to <code>inetd.conf</code>.
179: You must know the appropriate magic for writing daemons to achieve that.
1.15 espie 180: It could be argued that you have no business writing setuid programs
181: if you don't know how to do that.
1.10 espie 182:
1.15 espie 183: <li>Use setgid instead of setuid. Apart from those specific files needed
184: by setgid programs, most files are not group-writable. Hence, a
185: security problem in a setgid program won't compromise your system as
186: much: with only group rights, the worst an intruder will be able to
187: do is hack a games score table or some such.
1.10 espie 188: See the <code>xkobo</code> port for an instance of such a change.
189:
1.15 espie 190: <li>Don't trust group-writable files. Even though they are audited,
191: setgid programs are not perceived as important potential security
192: holes. Hence stuff they can tamper with shouldn't be considered
193: sensitive information.
194:
195: <li>Don't trust your environment ! This involves simple things such as
196: your <code>PATH</code> (never use <code>system</code> with an
197: unqualified name, avoid <code>execvp</code>), but also more subtle
198: items such as your locale, timezone, termcap, and so on.
199: Be aware of transitivity: even though you're taking full precautions,
200: programs you call directly won't necessarily. <strong>Never</strong>
201: use <code>system</code> in privileged programs, build your command
202: line, a controlled environment, and call <code>execve</code> directly.
203: The <code>perlsec</code> man page is a good tutorial on such problems.
204:
1.31 jufi 205: <li>Never use setuid shell-scripts. These are inherently insecure.
1.15 espie 206: Wrap them into some C code that ensures a proper environment.
207: On the other hand, OpenBSD features secure perl scripts.
208:
209: <li>Beware the dynamic loader. If you are running setuid, it will only
210: use trusted libraries that were scanned with ldconfig.
211: Setgid is not enough.
212:
213: <li>Dynamic libraries are tricky. C++ code sets a similar problem.
214: Basically, libraries may take some action based upon your environment
215: before your main program even gets to check its setuid status.
216: OpenBSD <code>issetugid</code> addresses this problem, from the
217: library writer point of view. Don't try to port libraries unless you
218: understand this issue thoroughly.
1.10 espie 219: </ul>
1.35 ! naddy 220: <h3><font color="#0000e0"><a name="Generic">Generic Porting Hints</a></font></h3>
1.10 espie 221: <ul>
222: <li><code>__OpenBSD__</code> should be used sparingly, if at all.
223: Constructs that look like
224: <pre>
225: #if defined(__NetBSD__) || defined(__FreeBSD__)
226: </pre>
227: are often inappropriate. Don't add blindly <code>__OpenBSD__</code>
228: to it. Instead, try to figure out what's going on, and what actual
229: feature is needed. Manual pages are often useful, as they include
230: historic comments, stating when a particular feature was incorporated
231: into BSD. Checking the numeric value of <code>BSD</code> against known
232: releases is often the right way. See
1.17 espie 233: <a href="ftp://ftp.netbsd.org/pub/NetBSD/packages/pkgsrc/Packages.txt">the NetBSD package guide</a>
1.10 espie 234: for more information.
235: <li>Defining <code>BSD</code> is a bad idea. Try to include <code>sys/param.h</code>.
236: This not only defines <code>BSD</code>, it also gives it a proper value.
237: The right code fragment should look like:
238: <pre>
1.23 rohee 239: #if (defined(__unix__) || defined(unix)) && !defined(USG)
1.10 espie 240: #include <sys/param.h>
241: #endif
242: </pre>
243: <li>Test for features, not for specific OSes. In the long run, it is much
1.15 espie 244: better to test whether <code>tcgetattr</code> works than whether
245: you're running under BSD 4.3 or later, or SystemVR4. These kind of
246: tests just confuse the issue. The way to go about it is, for instance,
247: to test for one particular system, set up a slew of
248: <code>HAVE_TCGETATTR</code> defines, then proceed to the next system.
249: This technique separates features tests from specific OSes.
250: In a hurry, another porter can just add the whole set of
251: <code>-DHAVE_XXX</code> defines to the Makefile. One may also write
252: or add to a configure script to check for that feature and add it
253: automatically. As an example not to follow, check nethack 3.2.2
254: source: it assumes loads of things based on the system type. Most
255: of these assumptions are obsolete and no longer reflect reality:
256: POSIX functions are more useful than older BSD versus SystemV
257: differences, to the point that some traditional bsd functions are
1.10 espie 258: now only supported through compatibility libraries.
259:
260: <li>Avoid include files that include other includes that... First, because
1.15 espie 261: this is inefficient. Your project will end up including a file that
262: includes everything. Also, because it makes some problems difficult
263: to fix. It becomes harder to <em>not</em> include one particular file
264: at a given point.
1.10 espie 265:
266: <li>Avoid bizarre macro tricks. Undefining a macro that was defined by a
267: header file is a bad idea. Defining macros to get some specific behavior
1.15 espie 268: from an include file is also a bad idea: compilation modes should be
269: global. If you want POSIX behavior, say so, and
270: <code>#define POSIX_C_SOURCE</code>
1.10 espie 271: throughout the whole project, not when you feel like it.
272:
273: <li>Don't ever write system function prototypes. All modern systems,
274: OpenBSD included, have a standard location for these prototypes. Likely
1.15 espie 275: places include <code>unistd.h</code>, <code>fcntl.h</code> or
276: <code>termios.h</code>.
277: The man page frequently states where the prototype can be found.
278: You might need another slew of <code>HAVE_XXX</code> macros to
279: procure the right file. Don't worry about including the same file
280: twice, include files have guards that prevent all kinds of nastiness.<br>
1.10 espie 281: If some broken system needs you to write the prototype, don't impose
1.15 espie 282: on all other systems. Roll-your-own prototypes will break because they
283: may use types that are equivalent on your system, but are not portable
284: to other systems (<code>unsigned long</code> instead of
285: <code>size_t</code>), or get some <code>const</code> status wrong.
286: Also, some compilers, such as OpenBSD's own gcc,
1.10 espie 287: are able to do a better job with some very frequent functions such as
288: <code>strlen</code> if you include the right header file.
289:
290: <li>Don't use the name of a standard system function for anything else.
1.15 espie 291: If you want to write your own function, give it its own name, and
292: call that function everywhere. If you wish to revert to the
293: default system function, you just need to comment your code out,
294: and define your own name to the system function. Don't do it the
295: other way round. Code should look like this
1.10 espie 296: <pre>
297: /* prototype part */
298: #ifdef USE_OWN_GCVT
299: char *foo_gcvt(double number, size_t ndigit, char *buf);
300: #else
301: /* include correct file */
302: #include <stdlib.h>
303: /* use system function */
304: #define foo_gcvt gcvt
305: #endif
306:
307: /* definition part */
308: #ifdef USE_OWN_GCVT
309: char *foo_gcvt(double number, size_t ndigit, char *buf)
310: {
1.15 espie 311: /* proper definition */
312: }
1.10 espie 313:
314: /* typical use */
315: s = foo_gcvt(n, 15, b);
316: </pre>
1.1 marc 317: </ul>
1.35 ! naddy 318: <h3><font color="#0000e0"><a name="Other">Other Helpful Hints</a></font></h3>
1.1 marc 319: <ul>
1.15 espie 320: <li>Recent versions of <code>bsd.port.mk</code> set the installers
321: path. Specifically, they set <code>/usr/bin</code> and
322: <code>/bin</code> to be searched <em>before</em>
323: <code>/usr/local/bin</code> and <code>/usr/X11R6/bin</code>.
1.19 rohee 324: <li>Do <em>NOT</em> generate shared libraries if
1.21 rohee 325: <code>${NO_SHARED_LIBS}</code> is defined (beware, it can be defined
326: only after inclusion of <code>bsd.port.mk</code>). If your port has
327: a GNU configure simply add the line
328: <code>CONFIGURE_ARGS += ${CONFIGURE_SHARED}</code> to the Makefile.
1.19 rohee 329: <li>If you rely on a feature that appeared in a recent version of
330: <code>bsd.port.mk</code> don't forget to add a line
331: <code>NEED_VERSION = x.yy</code> in the Makefile.
1.1 marc 332: <li>In OpenBSD <code>curses.h/libcurses/libtermlib</code> are the
333: ``new curses''. Change:<br>
1.15 espie 334: <code>ncurses.h ==> curses.h</code><br>
335: <code>-lncurses ==> -lcurses</code><br>
336: ``old (BSD) curses'' is available by defining
337: <code>_USE_OLD_CURSES_</code>
1.11 millert 338: before including <code>curses.h</code> (usually in a Makefile) and
1.15 espie 339: linking with <code>-locurses</code>.
1.11 millert 340: <li>In OpenBSD, terminal discipline has been upgraded from the older BSD
341: <code>sgtty</code> to the newer POSIX <code>tcgetattr</code> family.
1.15 espie 342: Avoid the older style in new code. Some code may define
343: <code>tcgetattr</code> to be a synonym for the older
344: <code>sgtty</code>, but this is at best a stopgap measure on OpenBSD.
345: The <code>xterm</code> source code is a very good example of
346: what not to do. Try to get your system functionality right: you
347: want a type that remembers the state of your terminal
348: (possible typedef), you want a function that extracts the current
349: state, and a function that sets the new state.
350: Functions that modify this state are more difficult, as they tend
351: to vary depending upon the system. Also, don't forget that you will
352: have to handle cases where you are not connected to a terminal,
353: and that you need to handle signals: not only termination, but
354: also background (<code>SIGTSTP</code>). You should always leave
355: the terminal in a sane state. Do your tests under an older shell,
356: such as sh, which does not reset the terminal in any way at
1.10 espie 357: program's termination.
1.15 espie 358: <li>The newer termcap/terminfo and curses, as included with OpenBSD,
359: include standard sequences for controlling color terminals. You
360: should use these if possible, reverting to standard ANSI color
361: sequences on other systems. However, some terminal descriptions
362: have not been updated yet, and you may need to be able to specify
363: these sequences manually. This is the way vim handles it. This is
364: not strictly necessary. Except for privileged programs, it is
365: generally possible to override a termcap definition through the
1.10 espie 366: <code>TERMCAP</code> variable and get it to work properly.
1.15 espie 367: <li>Signal semantics are tricky, and vary from one system to another.
368: Use <code>sigaction</code> to ensure a specific semantics, along
369: with other system calls referenced in the corresponding manpage.
1.1 marc 370: </ul>
371: <hr>
1.6 pauls 372: <a href="index.html"><img height=24 width=24 src=back.gif border=0 alt=OpenBSD></a>
1.20 rohee 373: <a href="mailto:www@openbsd.org">www@openbsd.org</a>
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