bpf.c revision 262435
1/* 2 * Copyright (c) 1988, 1992 The University of Utah and the Center 3 * for Software Science (CSS). 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#ifndef lint 44#if 0 45static const char sccsid[] = "@(#)bpf.c 8.1 (Berkeley) 6/4/93"; 46#endif 47static const char rcsid[] = 48 "$FreeBSD: stable/10/libexec/rbootd/bpf.c 262435 2014-02-24 08:21:49Z brueffer $"; 49#endif /* not lint */ 50 51#include <sys/param.h> 52#include <sys/ioctl.h> 53#include <sys/socket.h> 54#include <sys/time.h> 55 56#include <net/if.h> 57#include <net/bpf.h> 58 59#include <ctype.h> 60#include <errno.h> 61#include <fcntl.h> 62#include <stdio.h> 63#include <stdlib.h> 64#include <string.h> 65#include <syslog.h> 66#include <unistd.h> 67#include "defs.h" 68#include "pathnames.h" 69 70static int BpfFd = -1; 71static unsigned BpfLen = 0; 72static u_int8_t *BpfPkt = NULL; 73 74/* 75** BpfOpen -- Open and initialize a BPF device. 76** 77** Parameters: 78** None. 79** 80** Returns: 81** File descriptor of opened BPF device (for select() etc). 82** 83** Side Effects: 84** If an error is encountered, the program terminates here. 85*/ 86int 87BpfOpen(void) 88{ 89 struct ifreq ifr; 90 char bpfdev[32]; 91 int n = 0; 92 93 /* 94 * Open the first available BPF device. 95 */ 96 do { 97 (void) sprintf(bpfdev, _PATH_BPF, n++); 98 BpfFd = open(bpfdev, O_RDWR); 99 } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM)); 100 101 if (BpfFd < 0) { 102 syslog(LOG_ERR, "bpf: no available devices: %m"); 103 Exit(0); 104 } 105 106 /* 107 * Set interface name for bpf device, get data link layer 108 * type and make sure it's type Ethernet. 109 */ 110 (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name)); 111 if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) { 112 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName); 113 Exit(0); 114 } 115 116 /* 117 * Make sure we are dealing with an Ethernet device. 118 */ 119 if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) { 120 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m"); 121 Exit(0); 122 } 123 if (n != DLT_EN10MB) { 124 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported", 125 IntfName, n); 126 Exit(0); 127 } 128 129 /* 130 * On read(), return packets immediately (do not buffer them). 131 */ 132 n = 1; 133 if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) { 134 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m"); 135 Exit(0); 136 } 137 138 /* 139 * Try to enable the chip/driver's multicast address filter to 140 * grab our RMP address. If this fails, try promiscuous mode. 141 * If this fails, there's no way we are going to get any RMP 142 * packets so just exit here. 143 */ 144#ifdef MSG_EOR 145 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 146#endif 147 ifr.ifr_addr.sa_family = AF_UNSPEC; 148 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN); 149 if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) { 150 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m"); 151 Exit(0); 152 } 153 154 /* 155 * Ask BPF how much buffer space it requires and allocate one. 156 */ 157 if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) { 158 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m"); 159 Exit(0); 160 } 161 if (BpfPkt == NULL) 162 BpfPkt = (u_int8_t *)malloc(BpfLen); 163 164 if (BpfPkt == NULL) { 165 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)", 166 BpfLen); 167 Exit(0); 168 } 169 170 /* 171 * Write a little program to snarf RMP Boot packets and stuff 172 * it down BPF's throat (i.e. set up the packet filter). 173 */ 174 { 175#define RMP ((struct rmp_packet *)0) 176 static struct bpf_insn bpf_insn[] = { 177 { BPF_LD|BPF_B|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dsap }, 178 { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP }, 179 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.cntrl }, 180 { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP }, 181 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (long)&RMP->hp_llc.dxsap }, 182 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP }, 183 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 184 { BPF_RET|BPF_K, 0, 0, 0x0 } 185 }; 186#undef RMP 187 static struct bpf_program bpf_pgm = { 188 sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn 189 }; 190 191 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) { 192 syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m"); 193 Exit(0); 194 } 195 } 196 197 return(BpfFd); 198} 199 200/* 201** BPF GetIntfName -- Return the name of a network interface attached to 202** the system, or 0 if none can be found. The interface 203** must be configured up; the lowest unit number is 204** preferred; loopback is ignored. 205** 206** Parameters: 207** errmsg - if no network interface found, *errmsg explains why. 208** 209** Returns: 210** A (static) pointer to interface name, or NULL on error. 211** 212** Side Effects: 213** None. 214*/ 215char * 216BpfGetIntfName(char **errmsg) 217{ 218 struct ifreq ibuf[8], *ifrp, *ifend, *mp; 219 struct ifconf ifc; 220 int fd; 221 int minunit, n; 222 char *cp; 223 static char device[sizeof(ifrp->ifr_name)]; 224 static char errbuf[128] = "No Error!"; 225 226 if (errmsg != NULL) 227 *errmsg = errbuf; 228 229 if ((fd = socket(AF_INET, SOCK_DGRAM, 0)) < 0) { 230 (void) strcpy(errbuf, "bpf: socket: %m"); 231 return(NULL); 232 } 233 ifc.ifc_len = sizeof ibuf; 234 ifc.ifc_buf = (caddr_t)ibuf; 235 236#ifdef OSIOCGIFCONF 237 if (ioctl(fd, OSIOCGIFCONF, (char *)&ifc) < 0 || 238 ifc.ifc_len < sizeof(struct ifreq)) { 239 (void) strcpy(errbuf, "bpf: ioctl(OSIOCGIFCONF): %m"); 240 return(NULL); 241 } 242#else 243 if (ioctl(fd, SIOCGIFCONF, (char *)&ifc) < 0 || 244 ifc.ifc_len < sizeof(struct ifreq)) { 245 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFCONF): %m"); 246 return(NULL); 247 } 248#endif 249 ifrp = ibuf; 250 ifend = (struct ifreq *)((char *)ibuf + ifc.ifc_len); 251 252 mp = 0; 253 minunit = 666; 254 for (; ifrp < ifend; ++ifrp) { 255 if (ioctl(fd, SIOCGIFFLAGS, (char *)ifrp) < 0) { 256 (void) strcpy(errbuf, "bpf: ioctl(SIOCGIFFLAGS): %m"); 257 return(NULL); 258 } 259 260 /* 261 * If interface is down or this is the loopback interface, 262 * ignore it. 263 */ 264 if ((ifrp->ifr_flags & IFF_UP) == 0 || 265#ifdef IFF_LOOPBACK 266 (ifrp->ifr_flags & IFF_LOOPBACK)) 267#else 268 (strcmp(ifrp->ifr_name, "lo0") == 0)) 269#endif 270 continue; 271 272 for (cp = ifrp->ifr_name; !isdigit(*cp); ++cp) 273 ; 274 n = atoi(cp); 275 if (n < minunit) { 276 minunit = n; 277 mp = ifrp; 278 } 279 } 280 281 (void) close(fd); 282 if (mp == 0) { 283 (void) strcpy(errbuf, "bpf: no interfaces found"); 284 return(NULL); 285 } 286 287 (void) strcpy(device, mp->ifr_name); 288 return(device); 289} 290 291/* 292** BpfRead -- Read packets from a BPF device and fill in `rconn'. 293** 294** Parameters: 295** rconn - filled in with next packet. 296** doread - is True if we can issue a read() syscall. 297** 298** Returns: 299** True if `rconn' contains a new packet, False otherwise. 300** 301** Side Effects: 302** None. 303*/ 304int 305BpfRead(RMPCONN *rconn, int doread) 306{ 307 int datlen, caplen, hdrlen; 308 static u_int8_t *bp = NULL, *ep = NULL; 309 int cc; 310 311 /* 312 * The read() may block, or it may return one or more packets. 313 * We let the caller decide whether or not we can issue a read(). 314 */ 315 if (doread) { 316 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) { 317 syslog(LOG_ERR, "bpf: read: %m"); 318 return(0); 319 } else { 320 bp = BpfPkt; 321 ep = BpfPkt + cc; 322 } 323 } 324 325#define bhp ((struct bpf_hdr *)bp) 326 /* 327 * If there is a new packet in the buffer, stuff it into `rconn' 328 * and return a success indication. 329 */ 330 if (bp < ep) { 331 datlen = bhp->bh_datalen; 332 caplen = bhp->bh_caplen; 333 hdrlen = bhp->bh_hdrlen; 334 335 if (caplen != datlen) 336 syslog(LOG_ERR, 337 "bpf: short packet dropped (%d of %d bytes)", 338 caplen, datlen); 339 else if (caplen > sizeof(struct rmp_packet)) 340 syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)", 341 caplen); 342 else { 343 rconn->rmplen = caplen; 344 memmove((char *)&rconn->tstamp, (char *)&bhp->bh_tstamp, 345 sizeof(struct timeval)); 346 memmove((char *)&rconn->rmp, (char *)bp + hdrlen, caplen); 347 } 348 bp += BPF_WORDALIGN(caplen + hdrlen); 349 return(1); 350 } 351#undef bhp 352 353 return(0); 354} 355 356/* 357** BpfWrite -- Write packet to BPF device. 358** 359** Parameters: 360** rconn - packet to send. 361** 362** Returns: 363** True if write succeeded, False otherwise. 364** 365** Side Effects: 366** None. 367*/ 368int 369BpfWrite(RMPCONN *rconn) 370{ 371 if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) { 372 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn)); 373 return(0); 374 } 375 376 return(1); 377} 378 379/* 380** BpfClose -- Close a BPF device. 381** 382** Parameters: 383** None. 384** 385** Returns: 386** Nothing. 387** 388** Side Effects: 389** None. 390*/ 391void 392BpfClose(void) 393{ 394 struct ifreq ifr; 395 396 if (BpfPkt != NULL) { 397 free((char *)BpfPkt); 398 BpfPkt = NULL; 399 } 400 401 if (BpfFd == -1) 402 return; 403 404#ifdef MSG_EOR 405 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 406#endif 407 ifr.ifr_addr.sa_family = AF_UNSPEC; 408 memmove((char *)&ifr.ifr_addr.sa_data[0], &RmpMcastAddr[0], RMP_ADDRLEN); 409 if (ioctl(BpfFd, SIOCDELMULTI, (caddr_t)&ifr) < 0) 410 (void) ioctl(BpfFd, BIOCPROMISC, (caddr_t)0); 411 412 (void) close(BpfFd); 413 BpfFd = -1; 414} 415