xref: /netbsd-src/usr.sbin/rbootd/bpf.c (revision b1c86f5f087524e68db12794ee9c3e3da1ab17a0)
1 /*	$NetBSD: bpf.c,v 1.19 2009/04/18 09:18:17 lukem Exp $	*/
2 
3 /*
4  * Copyright (c) 1992, 1993
5  *	The Regents of the University of California.  All rights reserved.
6  *
7  * This code is derived from software contributed to Berkeley by
8  * the Center for Software Science of the University of Utah Computer
9  * Science Department.  CSS requests users of this software to return
10  * to css-dist@cs.utah.edu any improvements that they make and grant
11  * CSS redistribution rights.
12  *
13  * Redistribution and use in source and binary forms, with or without
14  * modification, are permitted provided that the following conditions
15  * are met:
16  * 1. Redistributions of source code must retain the above copyright
17  *    notice, this list of conditions and the following disclaimer.
18  * 2. Redistributions in binary form must reproduce the above copyright
19  *    notice, this list of conditions and the following disclaimer in the
20  *    documentation and/or other materials provided with the distribution.
21  * 3. Neither the name of the University nor the names of its contributors
22  *    may be used to endorse or promote products derived from this software
23  *    without specific prior written permission.
24  *
25  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
26  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
27  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
28  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
29  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
30  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
31  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
32  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
33  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
34  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
35  * SUCH DAMAGE.
36  *
37  *	from: @(#)bpf.c	8.1 (Berkeley) 6/4/93
38  *
39  * From: Utah Hdr: bpf.c 3.1 92/07/06
40  * Author: Jeff Forys, University of Utah CSS
41  */
42 
43 /*
44  * Copyright (c) 1988, 1992 The University of Utah and the Center
45  *	for Software Science (CSS).
46  *
47  * This code is derived from software contributed to Berkeley by
48  * the Center for Software Science of the University of Utah Computer
49  * Science Department.  CSS requests users of this software to return
50  * to css-dist@cs.utah.edu any improvements that they make and grant
51  * CSS redistribution rights.
52  *
53  * Redistribution and use in source and binary forms, with or without
54  * modification, are permitted provided that the following conditions
55  * are met:
56  * 1. Redistributions of source code must retain the above copyright
57  *    notice, this list of conditions and the following disclaimer.
58  * 2. Redistributions in binary form must reproduce the above copyright
59  *    notice, this list of conditions and the following disclaimer in the
60  *    documentation and/or other materials provided with the distribution.
61  * 3. All advertising materials mentioning features or use of this software
62  *    must display the following acknowledgement:
63  *	This product includes software developed by the University of
64  *	California, Berkeley and its contributors.
65  * 4. Neither the name of the University nor the names of its contributors
66  *    may be used to endorse or promote products derived from this software
67  *    without specific prior written permission.
68  *
69  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
70  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
71  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
72  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
73  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
74  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
75  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
76  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
77  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
78  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
79  * SUCH DAMAGE.
80  *
81  *	from: @(#)bpf.c	8.1 (Berkeley) 6/4/93
82  *
83  * From: Utah Hdr: bpf.c 3.1 92/07/06
84  * Author: Jeff Forys, University of Utah CSS
85  */
86 
87 #include <sys/cdefs.h>
88 #ifndef lint
89 #if 0
90 static char sccsid[] = "@(#)bpf.c	8.1 (Berkeley) 6/4/93";
91 #else
92 __RCSID("$NetBSD: bpf.c,v 1.19 2009/04/18 09:18:17 lukem Exp $");
93 #endif
94 #endif /* not lint */
95 
96 #include <sys/param.h>
97 #include <sys/ioctl.h>
98 #include <sys/socket.h>
99 
100 #include <net/if.h>
101 #include <net/bpf.h>
102 
103 #include <ctype.h>
104 #include <errno.h>
105 #include <fcntl.h>
106 #include <stdio.h>
107 #include <stdlib.h>
108 #include <string.h>
109 #include <syslog.h>
110 #include <paths.h>
111 #include <unistd.h>
112 #include <ifaddrs.h>
113 #include "defs.h"
114 #include "pathnames.h"
115 
116 static int BpfFd = -1;
117 static unsigned BpfLen = 0;
118 static u_int8_t *BpfPkt = NULL;
119 
120 /*
121 **  BpfOpen -- Open and initialize a BPF device.
122 **
123 **	Parameters:
124 **		None.
125 **
126 **	Returns:
127 **		File descriptor of opened BPF device (for select() etc).
128 **
129 **	Side Effects:
130 **		If an error is encountered, the program terminates here.
131 */
132 int
133 BpfOpen()
134 {
135 	struct ifreq ifr;
136 	u_int bufsize = 32768;
137 	int n;
138 
139 	BpfFd = open(_PATH_BPF, O_RDWR);
140 	if (BpfFd < 0) {
141 		syslog(LOG_ERR, "bpf: no available devices: %m");
142 		Exit(0);
143 	}
144 
145 	if (ioctl(BpfFd, BIOCSBLEN, &bufsize) < 0) {
146 		syslog(LOG_ERR, "bpf: ioctl(BIOCSBLEN,%d): %m", bufsize);
147 	}
148 
149 	/*
150 	 *  Set interface name for bpf device, get data link layer
151 	 *  type and make sure it's type Ethernet.
152 	 */
153 	(void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
154 	if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
155 		syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
156 		Exit(0);
157 	}
158 
159 	/*
160 	 *  Make sure we are dealing with an Ethernet device.
161 	 */
162 	if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
163 		syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
164 		Exit(0);
165 	}
166 	if (n != DLT_EN10MB) {
167 		syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
168 		       IntfName, n);
169 		Exit(0);
170 	}
171 
172 	/*
173 	 *  On read(), return packets immediately (do not buffer them).
174 	 */
175 	n = 1;
176 	if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
177 		syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
178 		Exit(0);
179 	}
180 
181 	/*
182 	 *  Try to enable the chip/driver's multicast address filter to
183 	 *  grab our RMP address.  If this fails, try promiscuous mode.
184 	 *  If this fails, there's no way we are going to get any RMP
185 	 *  packets so just exit here.
186 	 */
187 #ifdef MSG_EOR
188 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
189 #endif
190 	ifr.ifr_addr.sa_family = AF_UNSPEC;
191 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
192 	    RMP_ADDRLEN);
193 	if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
194 		syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
195 		Exit(0);
196 	}
197 
198 	/*
199 	 *  Ask BPF how much buffer space it requires and allocate one.
200 	 */
201 	if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
202 		syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
203 		Exit(0);
204 	}
205 	if (BpfPkt == NULL)
206 		BpfPkt = (u_int8_t *)malloc(BpfLen);
207 
208 	if (BpfPkt == NULL) {
209 		syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
210 		       BpfLen);
211 		Exit(0);
212 	}
213 
214 	/*
215 	 *  Write a little program to snarf RMP Boot packets and stuff
216 	 *  it down BPF's throat (i.e. set up the packet filter).
217 	 */
218 	{
219 #define	RMP	((struct rmp_packet *)0)
220 		static struct bpf_insn bpf_insn[] = {
221 		    { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
222 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
223 		    { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
224 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
225 		    { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
226 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
227 		    { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
228 		    { BPF_RET|BPF_K,         0, 0, 0x0 }
229 		};
230 #undef	RMP
231 		static struct bpf_program bpf_pgm = {
232 		    sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
233 		};
234 
235 		if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
236 			syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
237 			Exit(0);
238 		}
239 	}
240 
241 	return(BpfFd);
242 }
243 
244 /*
245 **  BPF GetIntfName -- Return the name of a network interface attached to
246 **		the system, or 0 if none can be found.  The interface
247 **		must be configured up; the lowest unit number is
248 **		preferred; loopback is ignored.
249 **
250 **	Parameters:
251 **		errmsg - if no network interface found, *errmsg explains why.
252 **
253 **	Returns:
254 **		A (static) pointer to interface name, or NULL on error.
255 **
256 **	Side Effects:
257 **		None.
258 */
259 char *
260 BpfGetIntfName(errmsg)
261 	char **errmsg;
262 {
263 	struct ifaddrs *ifap, *ifa, *p;
264 	int minunit, n;
265 	char *cp;
266 	static char device[IFNAMSIZ + 1];
267 	static char errbuf[128] = "No Error!";
268 
269 	if (errmsg != NULL)
270 		*errmsg = errbuf;
271 
272 	if (getifaddrs(&ifap) != 0) {
273 		(void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf));
274 		return(NULL);
275 	}
276 
277 	p = NULL;
278 	minunit = 666;
279 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
280 		/*
281 		 *  If interface is down or this is the loopback interface,
282 		 *  ignore it.
283 		 */
284 		if ((ifa->ifa_flags & IFF_UP) == 0 ||
285 #ifdef IFF_LOOPBACK
286 		    (ifa->ifa_flags & IFF_LOOPBACK))
287 #else
288 		    (strcmp(ifa->ifa_name, "lo0") == 0))
289 #endif
290 			continue;
291 
292 		for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp)
293 			;
294 		n = atoi(cp);
295 		if (n < minunit) {
296 			minunit = n;
297 			p = ifa;
298 		}
299 	}
300 	if (p == NULL) {
301 		(void) strlcpy(errbuf, "bpf: no interfaces found",
302 		    sizeof(errbuf));
303 		freeifaddrs(ifap);
304 		return(NULL);
305 	}
306 
307 	(void) strlcpy(device, p->ifa_name, sizeof(device));
308 	freeifaddrs(ifap);
309 	return(device);
310 }
311 
312 /*
313 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
314 **
315 **	Parameters:
316 **		rconn - filled in with next packet.
317 **		doread - is True if we can issue a read() syscall.
318 **
319 **	Returns:
320 **		True if `rconn' contains a new packet, False otherwise.
321 **
322 **	Side Effects:
323 **		None.
324 */
325 int
326 BpfRead(rconn, doread)
327 	RMPCONN *rconn;
328 	int doread;
329 {
330 	int datlen, caplen, hdrlen;
331 	static u_int8_t *bp = NULL, *ep = NULL;
332 	int cc;
333 
334 	/*
335 	 *  The read() may block, or it may return one or more packets.
336 	 *  We let the caller decide whether or not we can issue a read().
337 	 */
338 	if (doread) {
339 		if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
340 			syslog(LOG_ERR, "bpf: read: %m");
341 			return(0);
342 		} else {
343 			bp = BpfPkt;
344 			ep = BpfPkt + cc;
345 		}
346 	}
347 
348 #define bhp ((struct bpf_hdr *)bp)
349 	/*
350 	 *  If there is a new packet in the buffer, stuff it into `rconn'
351 	 *  and return a success indication.
352 	 */
353 	if (bp < ep) {
354 		datlen = bhp->bh_datalen;
355 		caplen = bhp->bh_caplen;
356 		hdrlen = bhp->bh_hdrlen;
357 
358 		if (caplen != datlen)
359 			syslog(LOG_ERR,
360 			       "bpf: short packet dropped (%d of %d bytes)",
361 			       caplen, datlen);
362 		else if (caplen > (int)sizeof(struct rmp_packet))
363 			syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
364 			       caplen);
365 		else {
366 			rconn->rmplen = caplen;
367 			memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
368 			  sizeof(struct timeval));
369 			memmove((char *)&rconn->rmp, (char *)bp + hdrlen,
370 			    caplen);
371 		}
372 		bp += BPF_WORDALIGN(caplen + hdrlen);
373 		return(1);
374 	}
375 #undef bhp
376 
377 	return(0);
378 }
379 
380 /*
381 **  BpfWrite -- Write packet to BPF device.
382 **
383 **	Parameters:
384 **		rconn - packet to send.
385 **
386 **	Returns:
387 **		True if write succeeded, False otherwise.
388 **
389 **	Side Effects:
390 **		None.
391 */
392 int
393 BpfWrite(rconn)
394 	RMPCONN *rconn;
395 {
396 	if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
397 		syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
398 		return(0);
399 	}
400 
401 	return(1);
402 }
403 
404 /*
405 **  BpfClose -- Close a BPF device.
406 **
407 **	Parameters:
408 **		None.
409 **
410 **	Returns:
411 **		Nothing.
412 **
413 **	Side Effects:
414 **		None.
415 */
416 void
417 BpfClose()
418 {
419 	struct ifreq ifr;
420 
421 	if (BpfPkt != NULL) {
422 		free((char *)BpfPkt);
423 		BpfPkt = NULL;
424 	}
425 
426 	if (BpfFd == -1)
427 		return;
428 
429 #ifdef MSG_EOR
430 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
431 #endif
432 	ifr.ifr_addr.sa_family = AF_UNSPEC;
433 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
434 	    RMP_ADDRLEN);
435 	if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
436 		(void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
437 
438 	(void) close(BpfFd);
439 	BpfFd = -1;
440 }
441