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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>
1.38 espie 63: <li>OpenBSD porting <a href="checklist.html">checklist</a>.
64: <li>The man page
1.41 rohee 65: <a href="http://www.openbsd.org/cgi-bin/man.cgi?query=bsd.port.mk&sektion=5">bsd.port.mk(5)</a>.
1.38 espie 66: This documents the ports infrastructure makefile that is
67: included at the end of each individual port makefile.
68: There are still a few comments at the start of
1.39 horacio 69: the file itself, but most of the useful information is now
1.38 espie 70: documented.
71: <li>Some differences from other BSD port systems, mostly a summary
72: of <a href="porting/diffs.html">infrastructure differences</a>.
73: <li><a href="porting/libraries.html">Using shared libraries
74: in OpenBSD Ports</a>. The rules there are <strong>very
75: important</strong> as soon as you use shared libraries, especially if
76: pkg_update is to work one day...
77: <li><a href="audio-port.html">Porting audio applications to OpenBSD</a>.
1.1 marc 78: <li>The
1.13 art 79: <a href="http://www.netbsd.org/Documentation/software/packages.html">
80: NetBSD Package System</a> documentation. This document describes
81: NetBSD's version of the FreeBSD ports system and is quite helpful.
1.33 naddy 82: <li>The
1.42 pvalchev 83: <a href="http://www.freebsd.org/doc/en_US.ISO8859-1/books/porters-handbook/index.html">FreeBSD
1.33 naddy 84: Porter's Handbook</a>. This is the FreeBSD porting bible.
1.1 marc 85: <li>The OpenBSD ports mailing list,
86: <a href="mailto:ports@openbsd.org">ports@OpenBSD.ORG</a>.
87: </ul>
1.35 naddy 88: <h3><font color="#0000e0"><a name="Policy">OpenBSD Porting Policy</a></font></h3>
1.1 marc 89: <ul>
1.24 rohee 90: <li>OpenBSD does NOT use <code>/usr/local/etc/rc.d</code>.<br>
1.7 espie 91: <code>/usr/local</code> is often shared between several machines
1.15 espie 92: thanks to NFS. For this reason, configuration files that are specific
93: to a given machine can't be stored under <code>/usr/local</code>,
94: <code>/etc</code> is the central repository for per machine
95: configuration files. Moreover, OpenBSD policy is to never update
96: files under <code>/etc</code> automatically. Ports that need some
97: specific boot setup should advise the administrator about what to do
98: instead of blindly installing files.
1.1 marc 99: <li>OpenBSD does NOT compress man pages.
100: <li>OpenBSD does NOT require <code>-lcrypt</code>.<br>
101: DES encryption is part of the standard <code>libc</code>.
1.46 sturm 102: <li>OpenBSD has a separate namespace for users and groups created by ports.
103: See <code>/usr/ports/infrastructure/db/user.list</code> for details.
1.10 espie 104: <li>OpenBSD is strongly security-oriented. You should read and understand
1.42 pvalchev 105: this page's <a href="#Security">security section</a>.
1.24 rohee 106: <li>Be sure to add the <code>$OpenBSD$</code> CVS tag to
1.10 espie 107: the Makefile. If importing a port from another system be sure to
108: leave their tag in the Makefile, too. However, replace the FreeBSD
1.24 rohee 109: <code>$Id$</code> tag with the
110: <code>$FreeBSD$</code> tag.
1.10 espie 111: <li>The goal is to get all ported applications to support OpenBSD. To
112: achieve this goal you <strong>must</strong> feed any OpenBSD patches
113: back to the application maintainer.
114: </ul>
1.35 naddy 115: <h3><font color="#0000e0"><a name="Security">Security Recommendations</a></font></h3>
1.10 espie 116: There are many security problems to worry about. If
1.2 marc 117: you are not absolutely sure of what you are doing please request
1.1 marc 118: help from the <a href="mailto:ports@openbsd.org">ports</a> mailing
119: list.
1.10 espie 120:
121: <ul>
1.20 rohee 122: <li>Do <em>not</em> use alpha or beta code when preparing a port. Use the
1.10 espie 123: latest regular or patch release.
124:
1.1 marc 125: <li>Any software to be installed as a server should be scanned
126: for buffer overflows, especially unsafe use of
127: <code>strcat/strcpy/strcmp/sprintf</code>. In general,
128: <code>sprintf</code> should be replaced with <code>snprintf</code>.
1.10 espie 129:
1.17 espie 130: <li>Never use filenames instead of true security. There are numerous race
1.10 espie 131: conditions where you don't have proper control. For instance, an attacker
132: who already has user privileges on your machines may replace files in
133: <code>/tmp</code> with symbolic links to more strategic files, such as
1.19 rohee 134: <code>/etc/master.passwd</code>.
1.16 espie 135:
136: <li>For instance, both <code>fopen</code> and <code>freopen</code>
137: <strong>create a new file or open an existing file</strong> for
138: writing. An attacker may create a symbolic link from
1.19 rohee 139: <code>/etc/master.passwd</code> to <code>/tmp/addrpool_dump</code>. The
1.16 espie 140: instant you open it, your password file is hosed. Yes, even with
141: an <code>unlink</code> right before. You only narrow the window
142: of opportunity. Use <code>open</code> with
1.22 rohee 143: <code>O_CREAT|O_EXCL</code> and <code>fdopen</code> instead.
1.15 espie 144:
1.16 espie 145: <li>Another very common problem is the <code>mktemp</code>
1.17 espie 146: function. Heed the warnings of the bsd linker about its uses.
1.15 espie 147: <strong>These must be fixed</strong>.
148: This is not quite as simple as <code>s/mktemp/mkstemp/g</code>. <br>
149: Refer to the <code>mktemp(3)</code> man page of OpenBSD current
150: for more indications.
151: Correct code using <code>mkstemp</code> includes the source to
152: <code>ed</code> or <code>mail</code>.
153: A rare instance of code that uses <code>mktemp</code> correctly
154: can be found in the <code>rsync</code> port.
1.10 espie 155:
156: <li>Just because you can read it doesn't mean you should. A well-known hole
157: of this nature was the <code>startx</code> problem. As a setuid program,
158: you could launch startx with any file as a script. If the file was not
159: a valid shell script, a syntax error message would follow, along with the
160: first line of the offending file, without any further permission check.
161: Pretty handy to grab the first line of a shadow passwd file, considering
1.12 deraadt 162: these often start with root entry. Do not open your file, and then do
163: an <code>fstat</code> on the open descriptor to check if you should have
1.15 espie 164: been able to open it (or the attacker will play with /dev/rst0 and rewind
1.12 deraadt 165: your tape) -- open it with the correct uid/gid/grouplist set.
1.10 espie 166:
167: <li>Don't use anything that forks a shell in setuid programs before dropping
1.15 espie 168: your privileges. This includes <code>popen</code> and
169: <code>system</code>.
1.10 espie 170: Use <code>fork</code>, <code>pipe</code> and <code>execve</code> instead.
171:
1.15 espie 172: <li>Pass open descriptors instead of filenames to other programs to
173: avoid race conditions. Even if a program does not accept file
174: descriptors, you can still use <code>/dev/fd/0</code>.
1.10 espie 175:
1.15 espie 176: <li>Access rights are attached to file descriptors. If you need setuid rights
1.10 espie 177: to open a file, open that file, then drop your privileges. You can still
178: access the open descriptor, but you have less to worry about. This is
179: double-edged: even after dropping privileges, you should still watch out
180: for those descriptors.
181:
182: <li>Avoid root setuid as much as you can. Basically, root can do anything,
1.15 espie 183: but root rights are very rarely needed, except maybe to create
184: socket ports with a number under 1024. It is arguably better to
185: keep that under <code>inetd</code>
1.10 espie 186: control and just add the relevant entries to <code>inetd.conf</code>.
187: You must know the appropriate magic for writing daemons to achieve that.
1.15 espie 188: It could be argued that you have no business writing setuid programs
189: if you don't know how to do that.
1.10 espie 190:
1.15 espie 191: <li>Use setgid instead of setuid. Apart from those specific files needed
192: by setgid programs, most files are not group-writable. Hence, a
193: security problem in a setgid program won't compromise your system as
194: much: with only group rights, the worst an intruder will be able to
195: do is hack a games score table or some such.
1.10 espie 196: See the <code>xkobo</code> port for an instance of such a change.
197:
1.15 espie 198: <li>Don't trust group-writable files. Even though they are audited,
199: setgid programs are not perceived as important potential security
200: holes. Hence stuff they can tamper with shouldn't be considered
201: sensitive information.
202:
203: <li>Don't trust your environment ! This involves simple things such as
204: your <code>PATH</code> (never use <code>system</code> with an
205: unqualified name, avoid <code>execvp</code>), but also more subtle
206: items such as your locale, timezone, termcap, and so on.
207: Be aware of transitivity: even though you're taking full precautions,
208: programs you call directly won't necessarily. <strong>Never</strong>
209: use <code>system</code> in privileged programs, build your command
210: line, a controlled environment, and call <code>execve</code> directly.
211: The <code>perlsec</code> man page is a good tutorial on such problems.
212:
1.31 jufi 213: <li>Never use setuid shell-scripts. These are inherently insecure.
1.15 espie 214: Wrap them into some C code that ensures a proper environment.
215: On the other hand, OpenBSD features secure perl scripts.
216:
217: <li>Beware the dynamic loader. If you are running setuid, it will only
218: use trusted libraries that were scanned with ldconfig.
219: Setgid is not enough.
220:
221: <li>Dynamic libraries are tricky. C++ code sets a similar problem.
222: Basically, libraries may take some action based upon your environment
223: before your main program even gets to check its setuid status.
224: OpenBSD <code>issetugid</code> addresses this problem, from the
225: library writer point of view. Don't try to port libraries unless you
226: understand this issue thoroughly.
1.10 espie 227: </ul>
1.35 naddy 228: <h3><font color="#0000e0"><a name="Generic">Generic Porting Hints</a></font></h3>
1.10 espie 229: <ul>
230: <li><code>__OpenBSD__</code> should be used sparingly, if at all.
231: Constructs that look like
232: <pre>
233: #if defined(__NetBSD__) || defined(__FreeBSD__)
234: </pre>
235: are often inappropriate. Don't add blindly <code>__OpenBSD__</code>
236: to it. Instead, try to figure out what's going on, and what actual
237: feature is needed. Manual pages are often useful, as they include
238: historic comments, stating when a particular feature was incorporated
239: into BSD. Checking the numeric value of <code>BSD</code> against known
240: releases is often the right way. See
1.17 espie 241: <a href="ftp://ftp.netbsd.org/pub/NetBSD/packages/pkgsrc/Packages.txt">the NetBSD package guide</a>
1.10 espie 242: for more information.
243: <li>Defining <code>BSD</code> is a bad idea. Try to include <code>sys/param.h</code>.
244: This not only defines <code>BSD</code>, it also gives it a proper value.
245: The right code fragment should look like:
246: <pre>
1.23 rohee 247: #if (defined(__unix__) || defined(unix)) && !defined(USG)
1.10 espie 248: #include <sys/param.h>
249: #endif
250: </pre>
251: <li>Test for features, not for specific OSes. In the long run, it is much
1.15 espie 252: better to test whether <code>tcgetattr</code> works than whether
253: you're running under BSD 4.3 or later, or SystemVR4. These kind of
254: tests just confuse the issue. The way to go about it is, for instance,
255: to test for one particular system, set up a slew of
256: <code>HAVE_TCGETATTR</code> defines, then proceed to the next system.
257: This technique separates features tests from specific OSes.
258: In a hurry, another porter can just add the whole set of
259: <code>-DHAVE_XXX</code> defines to the Makefile. One may also write
260: or add to a configure script to check for that feature and add it
261: automatically. As an example not to follow, check nethack 3.2.2
262: source: it assumes loads of things based on the system type. Most
263: of these assumptions are obsolete and no longer reflect reality:
264: POSIX functions are more useful than older BSD versus SystemV
265: differences, to the point that some traditional bsd functions are
1.10 espie 266: now only supported through compatibility libraries.
267:
268: <li>Avoid include files that include other includes that... First, because
1.15 espie 269: this is inefficient. Your project will end up including a file that
270: includes everything. Also, because it makes some problems difficult
271: to fix. It becomes harder to <em>not</em> include one particular file
272: at a given point.
1.10 espie 273:
274: <li>Avoid bizarre macro tricks. Undefining a macro that was defined by a
275: header file is a bad idea. Defining macros to get some specific behavior
1.15 espie 276: from an include file is also a bad idea: compilation modes should be
277: global. If you want POSIX behavior, say so, and
278: <code>#define POSIX_C_SOURCE</code>
1.10 espie 279: throughout the whole project, not when you feel like it.
280:
281: <li>Don't ever write system function prototypes. All modern systems,
282: OpenBSD included, have a standard location for these prototypes. Likely
1.15 espie 283: places include <code>unistd.h</code>, <code>fcntl.h</code> or
284: <code>termios.h</code>.
285: The man page frequently states where the prototype can be found.
286: You might need another slew of <code>HAVE_XXX</code> macros to
287: procure the right file. Don't worry about including the same file
288: twice, include files have guards that prevent all kinds of nastiness.<br>
1.10 espie 289: If some broken system needs you to write the prototype, don't impose
1.15 espie 290: on all other systems. Roll-your-own prototypes will break because they
291: may use types that are equivalent on your system, but are not portable
292: to other systems (<code>unsigned long</code> instead of
293: <code>size_t</code>), or get some <code>const</code> status wrong.
294: Also, some compilers, such as OpenBSD's own gcc,
1.10 espie 295: are able to do a better job with some very frequent functions such as
296: <code>strlen</code> if you include the right header file.
297:
298: <li>Don't use the name of a standard system function for anything else.
1.15 espie 299: If you want to write your own function, give it its own name, and
300: call that function everywhere. If you wish to revert to the
301: default system function, you just need to comment your code out,
302: and define your own name to the system function. Don't do it the
303: other way round. Code should look like this
1.10 espie 304: <pre>
305: /* prototype part */
306: #ifdef USE_OWN_GCVT
307: char *foo_gcvt(double number, size_t ndigit, char *buf);
308: #else
309: /* include correct file */
310: #include <stdlib.h>
311: /* use system function */
312: #define foo_gcvt gcvt
313: #endif
314:
315: /* definition part */
316: #ifdef USE_OWN_GCVT
317: char *foo_gcvt(double number, size_t ndigit, char *buf)
318: {
1.15 espie 319: /* proper definition */
320: }
1.10 espie 321:
322: /* typical use */
323: s = foo_gcvt(n, 15, b);
324: </pre>
1.1 marc 325: </ul>
1.35 naddy 326: <h3><font color="#0000e0"><a name="Other">Other Helpful Hints</a></font></h3>
1.1 marc 327: <ul>
1.15 espie 328: <li>Recent versions of <code>bsd.port.mk</code> set the installers
329: path. Specifically, they set <code>/usr/bin</code> and
330: <code>/bin</code> to be searched <em>before</em>
331: <code>/usr/local/bin</code> and <code>/usr/X11R6/bin</code>.
1.19 rohee 332: <li>Do <em>NOT</em> generate shared libraries if
1.21 rohee 333: <code>${NO_SHARED_LIBS}</code> is defined (beware, it can be defined
334: only after inclusion of <code>bsd.port.mk</code>). If your port has
335: a GNU configure simply add the line
336: <code>CONFIGURE_ARGS += ${CONFIGURE_SHARED}</code> to the Makefile.
1.44 pvalchev 337: <li>It is OK to rely on a feature that appeared in a recent version of
338: <code>bsd.port.mk</code>, as people are supposed to update their
339: whole ports tree, including <code>bsd.port.mk</code>.
340: NEED_VERSION is now obsolete.
1.1 marc 341: <li>In OpenBSD <code>curses.h/libcurses/libtermlib</code> are the
342: ``new curses''. Change:<br>
1.15 espie 343: <code>ncurses.h ==> curses.h</code><br>
344: ``old (BSD) curses'' is available by defining
345: <code>_USE_OLD_CURSES_</code>
1.11 millert 346: before including <code>curses.h</code> (usually in a Makefile) and
1.15 espie 347: linking with <code>-locurses</code>.
1.11 millert 348: <li>In OpenBSD, terminal discipline has been upgraded from the older BSD
349: <code>sgtty</code> to the newer POSIX <code>tcgetattr</code> family.
1.15 espie 350: Avoid the older style in new code. Some code may define
351: <code>tcgetattr</code> to be a synonym for the older
352: <code>sgtty</code>, but this is at best a stopgap measure on OpenBSD.
353: The <code>xterm</code> source code is a very good example of
354: what not to do. Try to get your system functionality right: you
355: want a type that remembers the state of your terminal
356: (possible typedef), you want a function that extracts the current
357: state, and a function that sets the new state.
358: Functions that modify this state are more difficult, as they tend
359: to vary depending upon the system. Also, don't forget that you will
360: have to handle cases where you are not connected to a terminal,
361: and that you need to handle signals: not only termination, but
362: also background (<code>SIGTSTP</code>). You should always leave
363: the terminal in a sane state. Do your tests under an older shell,
364: such as sh, which does not reset the terminal in any way at
1.10 espie 365: program's termination.
1.15 espie 366: <li>The newer termcap/terminfo and curses, as included with OpenBSD,
367: include standard sequences for controlling color terminals. You
368: should use these if possible, reverting to standard ANSI color
369: sequences on other systems. However, some terminal descriptions
370: have not been updated yet, and you may need to be able to specify
371: these sequences manually. This is the way vim handles it. This is
372: not strictly necessary. Except for privileged programs, it is
373: generally possible to override a termcap definition through the
1.10 espie 374: <code>TERMCAP</code> variable and get it to work properly.
1.15 espie 375: <li>Signal semantics are tricky, and vary from one system to another.
376: Use <code>sigaction</code> to ensure a specific semantics, along
377: with other system calls referenced in the corresponding manpage.
1.1 marc 378: </ul>
379: <hr>
1.6 pauls 380: <a href="index.html"><img height=24 width=24 src=back.gif border=0 alt=OpenBSD></a>
1.20 rohee 381: <a href="mailto:www@openbsd.org">www@openbsd.org</a>
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