xref: /freebsd/libexec/rbootd/bpf.c (revision 0957b409)
1 /*-
2  * SPDX-License-Identifier: BSD-3-Clause
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 #ifndef lint
46 #if 0
47 static const char sccsid[] = "@(#)bpf.c	8.1 (Berkeley) 6/4/93";
48 #endif
49 static const char rcsid[] =
50   "$FreeBSD$";
51 #endif /* not lint */
52 
53 #include <sys/param.h>
54 #include <sys/ioctl.h>
55 #include <sys/socket.h>
56 #include <sys/time.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 <unistd.h>
69 #include "defs.h"
70 #include "pathnames.h"
71 
72 static int BpfFd = -1;
73 static unsigned BpfLen = 0;
74 static u_int8_t *BpfPkt = NULL;
75 
76 /*
77 **  BpfOpen -- Open and initialize a BPF device.
78 **
79 **	Parameters:
80 **		None.
81 **
82 **	Returns:
83 **		File descriptor of opened BPF device (for select() etc).
84 **
85 **	Side Effects:
86 **		If an error is encountered, the program terminates here.
87 */
88 int
89 BpfOpen(void)
90 {
91 	struct ifreq ifr;
92 	char bpfdev[32];
93 	int n = 0;
94 
95 	/*
96 	 *  Open the first available BPF device.
97 	 */
98 	do {
99 		(void) sprintf(bpfdev, _PATH_BPF, n++);
100 		BpfFd = open(bpfdev, O_RDWR);
101 	} while (BpfFd < 0 && (errno == EBUSY || errno == EPERM));
102 
103 	if (BpfFd < 0) {
104 		syslog(LOG_ERR, "bpf: no available devices: %m");
105 		Exit(0);
106 	}
107 
108 	/*
109 	 *  Set interface name for bpf device, get data link layer
110 	 *  type and make sure it's type Ethernet.
111 	 */
112 	(void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name));
113 	if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) {
114 		syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName);
115 		Exit(0);
116 	}
117 
118 	/*
119 	 *  Make sure we are dealing with an Ethernet device.
120 	 */
121 	if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) {
122 		syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m");
123 		Exit(0);
124 	}
125 	if (n != DLT_EN10MB) {
126 		syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported",
127 		       IntfName, n);
128 		Exit(0);
129 	}
130 
131 	/*
132 	 *  On read(), return packets immediately (do not buffer them).
133 	 */
134 	n = 1;
135 	if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) {
136 		syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m");
137 		Exit(0);
138 	}
139 
140 	/*
141 	 *  Try to enable the chip/driver's multicast address filter to
142 	 *  grab our RMP address.  If this fails, try promiscuous mode.
143 	 *  If this fails, there's no way we are going to get any RMP
144 	 *  packets so just exit here.
145 	 */
146 #ifdef MSG_EOR
147 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
148 #endif
149 	ifr.ifr_addr.sa_family = AF_UNSPEC;
150 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], 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 *
218 BpfGetIntfName(char **errmsg)
219 {
220 	struct ifreq ibuf[8], *ifrp, *ifend, *mp;
221 	struct ifconf ifc;
222 	int fd;
223 	int minunit, n;
224 	char *cp;
225 	static char device[sizeof(ifrp->ifr_name)];
226 	static char errbuf[128] = "No Error!";
227 
228 	if (errmsg != NULL)
229 		*errmsg = errbuf;
230 
231 	if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) {
232 		(void) strcpy(errbuf, "bpf: socket: %m");
233 		return(NULL);
234 	}
235 	ifc.ifc_len = sizeof ibuf;
236 	ifc.ifc_buf = (caddr_t)ibuf;
237 
238 	if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 ||
239 	    ifc.ifc_len < sizeof(struct ifreq)) {
240 		(void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m");
241 		return(NULL);
242 	}
243 	ifrp = ibuf;
244 	ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len);
245 
246 	mp = NULL;
247 	minunit = 666;
248 	for (; ifrp < ifend; ++ifrp) {
249 		if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) {
250 			(void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m");
251 			return(NULL);
252 		}
253 
254 		/*
255 		 *  If interface is down or this is the loopback interface,
256 		 *  ignore it.
257 		 */
258 		if ((ifrp->ifr_flags & IFF_UP) == 0 ||
259 #ifdef IFF_LOOPBACK
260 		    (ifrp->ifr_flags & IFF_LOOPBACK))
261 #else
262 		    (strcmp(ifrp->ifr_name, "lo0") == 0))
263 #endif
264 			continue;
265 
266 		for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp)
267 			;
268 		n = atoi(cp);
269 		if (n < minunit) {
270 			minunit = n;
271 			mp = ifrp;
272 		}
273 	}
274 
275 	(void) close(fd);
276 	if (mp == NULL) {
277 		(void) strcpy(errbuf, "bpf: no interfaces found");
278 		return(NULL);
279 	}
280 
281 	(void) strcpy(device, mp->ifr_name);
282 	return(device);
283 }
284 
285 /*
286 **  BpfRead -- Read packets from a BPF device and fill in `rconn'.
287 **
288 **	Parameters:
289 **		rconn - filled in with next packet.
290 **		doread - is True if we can issue a read() syscall.
291 **
292 **	Returns:
293 **		True if `rconn' contains a new packet, False otherwise.
294 **
295 **	Side Effects:
296 **		None.
297 */
298 int
299 BpfRead(RMPCONN *rconn, int doread)
300 {
301 	int datlen, caplen, hdrlen;
302 	static u_int8_t *bp = NULL, *ep = NULL;
303 	int cc;
304 
305 	/*
306 	 *  The read() may block, or it may return one or more packets.
307 	 *  We let the caller decide whether or not we can issue a read().
308 	 */
309 	if (doread) {
310 		if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) {
311 			syslog(LOG_ERR, "bpf: read: %m");
312 			return(0);
313 		} else {
314 			bp = BpfPkt;
315 			ep = BpfPkt + cc;
316 		}
317 	}
318 
319 #define bhp ((struct bpf_hdr *)bp)
320 	/*
321 	 *  If there is a new packet in the buffer, stuff it into `rconn'
322 	 *  and return a success indication.
323 	 */
324 	if (bp < ep) {
325 		datlen = bhp->bh_datalen;
326 		caplen = bhp->bh_caplen;
327 		hdrlen = bhp->bh_hdrlen;
328 
329 		if (caplen != datlen)
330 			syslog(LOG_ERR,
331 			       "bpf: short packet dropped (%d of %d bytes)",
332 			       caplen, datlen);
333 		else if (caplen > sizeof(struct rmp_packet))
334 			syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)",
335 			       caplen);
336 		else {
337 			rconn->rmplen = caplen;
338 			memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp,
339 			      sizeof(struct timeval));
340 			memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen);
341 		}
342 		bp += BPF_WORDALIGN(caplen + hdrlen);
343 		return(1);
344 	}
345 #undef bhp
346 
347 	return(0);
348 }
349 
350 /*
351 **  BpfWrite -- Write packet to BPF device.
352 **
353 **	Parameters:
354 **		rconn - packet to send.
355 **
356 **	Returns:
357 **		True if write succeeded, False otherwise.
358 **
359 **	Side Effects:
360 **		None.
361 */
362 int
363 BpfWrite(RMPCONN *rconn)
364 {
365 	if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) {
366 		syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn));
367 		return(0);
368 	}
369 
370 	return(1);
371 }
372 
373 /*
374 **  BpfClose -- Close a BPF device.
375 **
376 **	Parameters:
377 **		None.
378 **
379 **	Returns:
380 **		Nothing.
381 **
382 **	Side Effects:
383 **		None.
384 */
385 void
386 BpfClose(void)
387 {
388 	struct ifreq ifr;
389 
390 	if (BpfPkt != NULL) {
391 		free((char *)BpfPkt);
392 		BpfPkt = NULL;
393 	}
394 
395 	if (BpfFd == -1)
396 		return;
397 
398 #ifdef MSG_EOR
399 	ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2;
400 #endif
401 	ifr.ifr_addr.sa_family = AF_UNSPEC;
402 	memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN);
403 	if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0)
404 		(void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0);
405 
406 	(void) close(BpfFd);
407 	BpfFd = -1;
408 }
409