xref: /netbsd-src/usr.sbin/rbootd/bpf.c (revision e371117863707264453fe4aa8533ac8a83bd07b5)
1 /*	$NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $	*/
2 
3 /*
4  * Copyright (c) 1988, 1992 The University of Utah and the Center
5  *	for Software Science (CSS).
6  * Copyright (c) 1992, 1993
7  *	The Regents of the University of California.  All rights reserved.
8  *
9  * This code is derived from software contributed to Berkeley by
10  * the Center for Software Science of the University of Utah Computer
11  * Science Department.  CSS requests users of this software to return
12  * to css-dist@cs.utah.edu any improvements that they make and grant
13  * CSS redistribution rights.
14  *
15  * Redistribution and use in source and binary forms, with or without
16  * modification, are permitted provided that the following conditions
17  * are met:
18  * 1. Redistributions of source code must retain the above copyright
19  *    notice, this list of conditions and the following disclaimer.
20  * 2. Redistributions in binary form must reproduce the above copyright
21  *    notice, this list of conditions and the following disclaimer in the
22  *    documentation and/or other materials provided with the distribution.
23  * 3. Neither the name of the University nor the names of its contributors
24  *    may be used to endorse or promote products derived from this software
25  *    without specific prior written permission.
26  *
27  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
28  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
29  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
30  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
31  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
32  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
33  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
34  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
35  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
36  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
37  * SUCH DAMAGE.
38  *
39  *	from: @(#)bpf.c	8.1 (Berkeley) 6/4/93
40  *
41  * From: Utah Hdr: bpf.c 3.1 92/07/06
42  * Author: Jeff Forys, University of Utah CSS
43  */
44 
45 #include <sys/cdefs.h>
46 #ifndef lint
47 #if 0
48 static char sccsid[] = "@(#)bpf.c	8.1 (Berkeley) 6/4/93";
49 #else
50 __RCSID("$NetBSD: bpf.c,v 1.22 2022/09/03 07:45:08 tsutsui Exp $");
51 #endif
52 #endif /* not lint */
53 
54 #include <sys/param.h>
55 #include <sys/ioctl.h>
56 #include <sys/socket.h>
57 
58 #include <net/if.h>
59 #include <net/bpf.h>
60 
61 #include <ctype.h>
62 #include <errno.h>
63 #include <fcntl.h>
64 #include <stdio.h>
65 #include <stdlib.h>
66 #include <string.h>
67 #include <syslog.h>
68 #include <paths.h>
69 #include <unistd.h>
70 #include <ifaddrs.h>
71 #include "defs.h"
72 #include "pathnames.h"
73 
74 static int BpfFd = -1;
75 static unsigned BpfLen = 0;
76 static u_int8_t *BpfPkt = NULL;
77 
78 /*
79 **  BpfOpen -- Open and initialize a BPF device.
80 **
81 **	Parameters:
82 **		None.
83 **
84 **	Returns:
85 **		File descriptor of opened BPF device (for select() etc).
86 **
87 **	Side Effects:
88 **		If an error is encountered, the program terminates here.
89 */
90 int
BpfOpen(void)91 BpfOpen(void)
92 {
93 	struct ifreq ifr;
94 	u_int bufsize = 32768;
95 	int n;
96 
97 	BpfFd = open(_PATH_BPF, O_RDWR);
98 	if (BpfFd < 0) {
99 		syslog(LOG_ERR, "bpf: no available devices: %m");
100 		Exit(0);
101 	}
102 
103 	if (ioctl(BpfFd, BIOCSBLEN, &bufsize) < 0) {
104 		syslog(LOG_ERR, "bpf: ioctl(BIOCSBLEN,%d): %m", bufsize);
105 	}
106 
107 	/*
108 	 *  Set interface name for bpf device, get data link layer
109 	 *  type and make sure it's type Ethernet.
110 	 */
111 	(void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
112 	if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
113 		syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
114 		Exit(0);
115 	}
116 
117 	/*
118 	 *  Make sure we are dealing with an Ethernet device.
119 	 */
120 	if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
121 		syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
122 		Exit(0);
123 	}
124 	if (n != DLT_EN10MB) {
125 		syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
126 		       IntfName, n);
127 		Exit(0);
128 	}
129 
130 	/*
131 	 *  On read(), return packets immediately (do not buffer them).
132 	 */
133 	n = 1;
134 	if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
135 		syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
136 		Exit(0);
137 	}
138 
139 	/*
140 	 *  Try to enable the chip/driver's multicast address filter to
141 	 *  grab our RMP address.  If this fails, try promiscuous mode.
142 	 *  If this fails, there's no way we are going to get any RMP
143 	 *  packets so just exit here.
144 	 */
145 #ifdef MSG_EOR
146 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
147 #endif
148 	ifr.ifr_addr.sa_family = AF_UNSPEC;
149 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
150 	    RMP_ADDRLEN);
151 	if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) {
152 		syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m");
153 		Exit(0);
154 	}
155 
156 	/*
157 	 *  Ask BPF how much buffer space it requires and allocate one.
158 	 */
159 	if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) {
160 		syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m");
161 		Exit(0);
162 	}
163 	if (BpfPkt == NULL)
164 		BpfPkt = (u_int8_t *)malloc(BpfLen);
165 
166 	if (BpfPkt == NULL) {
167 		syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)",
168 		       BpfLen);
169 		Exit(0);
170 	}
171 
172 	/*
173 	 *  Write a little program to snarf RMP Boot packets and stuff
174 	 *  it down BPF's throat (i.e. set up the packet filter).
175 	 */
176 	{
177 #define	RMP	((struct rmp_packet *)0)
178 		static struct bpf_insn bpf_insn[] = {
179 		    { BPF_LD|BPF_B|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dsap },
180 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP },
181 		    { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.cntrl },
182 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP },
183 		    { BPF_LD|BPF_H|BPF_ABS,  0, 0, (long)&RMP->hp_llc.dxsap },
184 		    { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP },
185 		    { BPF_RET|BPF_K,         0, 0, RMP_MAX_PACKET },
186 		    { BPF_RET|BPF_K,         0, 0, 0x0 }
187 		};
188 #undef	RMP
189 		static struct bpf_program bpf_pgm = {
190 		    sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn
191 		};
192 
193 		if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) {
194 			syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m");
195 			Exit(0);
196 		}
197 	}
198 
199 	return(BpfFd);
200 }
201 
202 /*
203 **  BPF GetIntfName -- Return the name of a network interface attached to
204 **		the system, or 0 if none can be found.  The interface
205 **		must be configured up; the lowest unit number is
206 **		preferred; loopback is ignored.
207 **
208 **	Parameters:
209 **		errmsg - if no network interface found, *errmsg explains why.
210 **
211 **	Returns:
212 **		A (static) pointer to interface name, or NULL on error.
213 **
214 **	Side Effects:
215 **		None.
216 */
217 char *
BpfGetIntfName(char ** errmsg)218 BpfGetIntfName(char **errmsg)
219 {
220 	struct ifaddrs *ifap, *ifa, *p;
221 	int minunit, n;
222 	char *cp;
223 	static char device[IFNAMSIZ + 1];
224 	static char errbuf[128] = "No Error!";
225 
226 	if (errmsg != NULL)
227 		*errmsg = errbuf;
228 
229 	if (getifaddrs(&ifap) != 0) {
230 		(void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf));
231 		return(NULL);
232 	}
233 
234 	p = NULL;
235 	minunit = 666;
236 	for (ifa = ifap; ifa; ifa = ifa->ifa_next) {
237 		/*
238 		 *  If interface is down or this is the loopback interface,
239 		 *  ignore it.
240 		 */
241 		if ((ifa->ifa_flags & IFF_UP) == 0 ||
242 #ifdef IFF_LOOPBACK
243 		    (ifa->ifa_flags & IFF_LOOPBACK))
244 #else
245 		    (strcmp(ifa->ifa_name, "lo0") == 0))
246 #endif
247 			continue;
248 
249 		for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp)
250 			;
251 		n = atoi(cp);
252 		if (n < minunit) {
253 			minunit = n;
254 			p = ifa;
255 		}
256 	}
257 	if (p == NULL) {
258 		(void) strlcpy(errbuf, "bpf: no interfaces found",
259 		    sizeof(errbuf));
260 		freeifaddrs(ifap);
261 		return(NULL);
262 	}
263 
264 	(void) strlcpy(device, p->ifa_name, sizeof(device));
265 	freeifaddrs(ifap);
266 	return(device);
267 }
268 
269 /*
270 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
271 **
272 **	Parameters:
273 **		rconn - filled in with next packet.
274 **		doread - is True if we can issue a read() syscall.
275 **
276 **	Returns:
277 **		True if `rconn' contains a new packet, False otherwise.
278 **
279 **	Side Effects:
280 **		None.
281 */
282 int
BpfRead(RMPCONN * rconn,int doread)283 BpfRead(RMPCONN *rconn, int doread)
284 {
285 	int datlen, caplen, hdrlen;
286 	static u_int8_t *bp = NULL, *ep = NULL;
287 	int cc;
288 
289 	/*
290 	 *  The read() may block, or it may return one or more packets.
291 	 *  We let the caller decide whether or not we can issue a read().
292 	 */
293 	if (doread) {
294 		if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
295 			syslog(LOG_ERR, "bpf: read: %m");
296 			return(0);
297 		} else {
298 			bp = BpfPkt;
299 			ep = BpfPkt + cc;
300 		}
301 	}
302 
303 #define bhp ((struct bpf_hdr *)bp)
304 	/*
305 	 *  If there is a new packet in the buffer, stuff it into `rconn'
306 	 *  and return a success indication.
307 	 */
308 	if (bp < ep) {
309 		datlen = bhp->bh_datalen;
310 		caplen = bhp->bh_caplen;
311 		hdrlen = bhp->bh_hdrlen;
312 
313 		if (caplen != datlen)
314 			syslog(LOG_ERR,
315 			       "bpf: short packet dropped (%d of %d bytes)",
316 			       caplen, datlen);
317 		else if (caplen > (int)sizeof(struct rmp_packet))
318 			syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
319 			       caplen);
320 		else {
321 			rconn->rmplen = caplen;
322 			memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
323 			  sizeof(struct timeval));
324 			memmove((char *)&rconn->rmp, (char *)bp + hdrlen,
325 			    caplen);
326 		}
327 		bp += BPF_WORDALIGN(caplen + hdrlen);
328 		return(1);
329 	}
330 #undef bhp
331 
332 	return(0);
333 }
334 
335 /*
336 **  BpfWrite -- Write packet to BPF device.
337 **
338 **	Parameters:
339 **		rconn - packet to send.
340 **
341 **	Returns:
342 **		True if write succeeded, False otherwise.
343 **
344 **	Side Effects:
345 **		None.
346 */
347 int
BpfWrite(RMPCONN * rconn)348 BpfWrite(RMPCONN *rconn)
349 {
350 	if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
351 		syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
352 		return(0);
353 	}
354 
355 	return(1);
356 }
357 
358 /*
359 **  BpfClose -- Close a BPF device.
360 **
361 **	Parameters:
362 **		None.
363 **
364 **	Returns:
365 **		Nothing.
366 **
367 **	Side Effects:
368 **		None.
369 */
370 void
BpfClose(void)371 BpfClose(void)
372 {
373 	struct ifreq ifr;
374 
375 	if (BpfPkt != NULL) {
376 		free((char *)BpfPkt);
377 		BpfPkt = NULL;
378 	}
379 
380 	if (BpfFd == -1)
381 		return;
382 
383 #ifdef MSG_EOR
384 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
385 #endif
386 	ifr.ifr_addr.sa_family = AF_UNSPEC;
387 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0],
388 	    RMP_ADDRLEN);
389 	if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
390 		(void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
391 
392 	(void) close(BpfFd);
393 	BpfFd = -1;
394 }
395