1 /* $OpenBSD: bpf.c,v 1.17 2009/10/27 23:59:54 deraadt Exp $ */ 2 /* $NetBSD: bpf.c,v 1.5.2.1 1995/11/14 08:45:42 thorpej Exp $ */ 3 4 /* 5 * Copyright (c) 1988, 1992 The University of Utah and the Center 6 * for Software Science (CSS). 7 * Copyright (c) 1992, 1993 8 * The Regents of the University of California. All rights reserved. 9 * 10 * This code is derived from software contributed to Berkeley by 11 * the Center for Software Science of the University of Utah Computer 12 * Science Department. CSS requests users of this software to return 13 * to css-dist@cs.utah.edu any improvements that they make and grant 14 * CSS redistribution rights. 15 * 16 * Redistribution and use in source and binary forms, with or without 17 * modification, are permitted provided that the following conditions 18 * are met: 19 * 1. Redistributions of source code must retain the above copyright 20 * notice, this list of conditions and the following disclaimer. 21 * 2. Redistributions in binary form must reproduce the above copyright 22 * notice, this list of conditions and the following disclaimer in the 23 * documentation and/or other materials provided with the distribution. 24 * 3. Neither the name of the University nor the names of its contributors 25 * may be used to endorse or promote products derived from this software 26 * without specific prior written permission. 27 * 28 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND 29 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE 30 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE 31 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE 32 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL 33 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS 34 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) 35 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT 36 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY 37 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF 38 * SUCH DAMAGE. 39 * 40 * from: @(#)bpf.c 8.1 (Berkeley) 6/4/93 41 * 42 * From: Utah Hdr: bpf.c 3.1 92/07/06 43 * Author: Jeff Forys, University of Utah CSS 44 */ 45 46 #include <sys/param.h> 47 #include <sys/ioctl.h> 48 #include <sys/socket.h> 49 50 #include <net/if.h> 51 #include <net/bpf.h> 52 53 #include <ctype.h> 54 #include <errno.h> 55 #include <fcntl.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <syslog.h> 60 #include <unistd.h> 61 #include <ifaddrs.h> 62 #include "defs.h" 63 #include "pathnames.h" 64 65 static int BpfFd = -1; 66 static unsigned int BpfLen = 0; 67 static u_int8_t *BpfPkt = NULL; 68 69 /* 70 ** BpfOpen -- Open and initialize a BPF device. 71 ** 72 ** Parameters: 73 ** None. 74 ** 75 ** Returns: 76 ** File descriptor of opened BPF device (for select() etc). 77 ** 78 ** Side Effects: 79 ** If an error is encountered, the program terminates here. 80 */ 81 int 82 BpfOpen(void) 83 { 84 struct ifreq ifr; 85 char bpfdev[32]; 86 int n = 0; 87 88 /* 89 * Open the first available BPF device. 90 */ 91 do { 92 (void) snprintf(bpfdev, sizeof bpfdev, _PATH_BPF, n++); 93 BpfFd = open(bpfdev, O_RDWR); 94 } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM)); 95 96 if (BpfFd < 0) { 97 syslog(LOG_ERR, "bpf: no available devices: %m"); 98 DoExit(); 99 } 100 101 /* 102 * Set interface name for bpf device, get data link layer 103 * type and make sure it's type Ethernet. 104 */ 105 (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name)); 106 if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) { 107 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName); 108 DoExit(); 109 } 110 111 /* 112 * Make sure we are dealing with an Ethernet device. 113 */ 114 if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) { 115 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m"); 116 DoExit(); 117 } 118 if (n != DLT_EN10MB) { 119 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported", 120 IntfName, n); 121 DoExit(); 122 } 123 124 /* 125 * On read(), return packets immediately (do not buffer them). 126 */ 127 n = 1; 128 if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) { 129 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m"); 130 DoExit(); 131 } 132 133 /* 134 * Try to enable the chip/driver's multicast address filter to 135 * grab our RMP address. If this fails, try promiscuous mode. 136 * If this fails, there's no way we are going to get any RMP 137 * packets so just exit here. 138 */ 139 #ifdef MSG_EOR 140 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 141 #endif 142 ifr.ifr_addr.sa_family = AF_UNSPEC; 143 bcopy(&RmpMcastAddr[0], (char *)&ifr.ifr_addr.sa_data[0], RMP_ADDRLEN); 144 if (ioctl(BpfFd, SIOCADDMULTI, (caddr_t)&ifr) < 0) { 145 syslog(LOG_WARNING, 146 "bpf: can't add mcast addr (%m), setting promiscuous mode"); 147 148 if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) { 149 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m"); 150 DoExit(); 151 } 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 DoExit(); 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 DoExit(); 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 /* make sure it is a 802.3 packet */ 178 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_hdr.len }, 179 { BPF_JMP|BPF_JGE|BPF_K, 7, 0, 0x600 }, 180 181 { BPF_LD|BPF_B|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.dsap }, 182 { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP }, 183 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.cntrl }, 184 { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP }, 185 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.dxsap }, 186 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP }, 187 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 188 { BPF_RET|BPF_K, 0, 0, 0x0 } 189 }; 190 191 static struct bpf_insn bpf_wf_insn[] = { 192 /* make sure it is a 802.3 packet */ 193 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_hdr.len }, 194 { BPF_JMP|BPF_JGE|BPF_K, 12, 0, 0x600 }, 195 196 /* check the SNAP header */ 197 { BPF_LD|BPF_B|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.dsap }, 198 { BPF_JMP|BPF_JEQ|BPF_K, 0, 10, IEEE_DSAP_HP }, 199 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.cntrl }, 200 { BPF_JMP|BPF_JEQ|BPF_K, 0, 8, IEEE_CNTL_HP }, 201 202 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.sxsap }, 203 { BPF_JMP|BPF_JEQ|BPF_K, 0, 6, HPEXT_DXSAP }, 204 { BPF_LD|BPF_H|BPF_ABS, 0, 0, (u_int32_t)&RMP->hp_llc.dxsap }, 205 { BPF_JMP|BPF_JEQ|BPF_K, 0, 4, HPEXT_SXSAP }, 206 207 /* check return type code */ 208 { BPF_LD|BPF_B|BPF_ABS, 0, 0, 209 (u_int32_t)&RMP->rmp_proto.rmp_raw.rmp_type }, 210 { BPF_JMP|BPF_JEQ|BPF_K, 1, 0, RMP_BOOT_REPL }, 211 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, RMP_READ_REPL }, 212 213 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 214 { BPF_RET|BPF_K, 0, 0, 0x0 } 215 }; 216 #undef RMP 217 static struct bpf_program bpf_pgm = { 218 sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn 219 }; 220 221 static struct bpf_program bpf_w_pgm = { 222 sizeof(bpf_wf_insn)/sizeof(bpf_wf_insn[0]), bpf_wf_insn 223 }; 224 225 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) { 226 syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m"); 227 DoExit(); 228 } 229 230 if (ioctl(BpfFd, BIOCSETWF, (caddr_t)&bpf_w_pgm) < 0) { 231 syslog(LOG_ERR, "bpf: ioctl(BIOCSETWF): %m"); 232 DoExit(); 233 } 234 235 if (ioctl(BpfFd, BIOCLOCK) < 0) { 236 syslog(LOG_ERR, "bpf: ioctl(BIOCLOCK): %m"); 237 DoExit(); 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(char **errmsg) 261 { 262 int minunit = 999, n; 263 char *cp; 264 static char device[IFNAMSIZ]; 265 static char errbuf[128] = "No Error!"; 266 struct ifaddrs *ifap, *ifa, *mp = NULL; 267 268 if (errmsg != NULL) 269 *errmsg = errbuf; 270 271 if (getifaddrs(&ifap) != 0) { 272 (void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf)); 273 return(NULL); 274 } 275 276 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 277 /* 278 * If interface is down or this is the loopback interface, 279 * ignore it. 280 */ 281 if ((ifa->ifa_flags & IFF_UP) == 0 || 282 #ifdef IFF_LOOPBACK 283 (ifa->ifa_flags & IFF_LOOPBACK)) 284 #else 285 (strcmp(ifa->ifa_name, "lo0") == 0)) 286 #endif 287 continue; 288 289 for (cp = ifa->ifa_name; !isdigit(*cp); ++cp) 290 ; 291 n = atoi(cp); 292 if (n < minunit) { 293 minunit = n; 294 mp = ifa; 295 } 296 } 297 298 if (mp == 0) { 299 (void) strlcpy(errbuf, "bpf: no interfaces found", 300 sizeof(errbuf)); 301 freeifaddrs(ifap); 302 return(NULL); 303 } 304 305 (void) strlcpy(device, mp->ifa_name, sizeof device); 306 freeifaddrs(ifap); 307 return(device); 308 } 309 310 /* 311 ** BpfRead -- Read packets from a BPF device and fill in `rconn'. 312 ** 313 ** Parameters: 314 ** rconn - filled in with next packet. 315 ** doread - is True if we can issue a read() syscall. 316 ** 317 ** Returns: 318 ** True if `rconn' contains a new packet, False otherwise. 319 ** 320 ** Side Effects: 321 ** None. 322 */ 323 int 324 BpfRead(RMPCONN *rconn, int doread) 325 { 326 int datlen, caplen, hdrlen; 327 static u_int8_t *bp = NULL, *ep = NULL; 328 int cc; 329 330 /* 331 * The read() may block, or it may return one or more packets. 332 * We let the caller decide whether or not we can issue a read(). 333 */ 334 if (doread) { 335 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) { 336 syslog(LOG_ERR, "bpf: read: %m"); 337 return(0); 338 } else { 339 bp = BpfPkt; 340 ep = BpfPkt + cc; 341 } 342 } 343 344 #define bhp ((struct bpf_hdr *)bp) 345 /* 346 * If there is a new packet in the buffer, stuff it into `rconn' 347 * and return a success indication. 348 */ 349 if (bp < ep) { 350 datlen = bhp->bh_datalen; 351 caplen = bhp->bh_caplen; 352 hdrlen = bhp->bh_hdrlen; 353 354 if (caplen != datlen) 355 syslog(LOG_ERR, 356 "bpf: short packet dropped (%d of %d bytes)", 357 caplen, datlen); 358 else if (caplen > sizeof(struct rmp_packet)) 359 syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)", 360 caplen); 361 else { 362 rconn->rmplen = caplen; 363 bcopy((char *)&bhp->bh_tstamp, (char *)&rconn->tstamp, 364 sizeof(struct timeval)); 365 bcopy((char *)bp + hdrlen, (char *)&rconn->rmp, caplen); 366 } 367 bp += BPF_WORDALIGN(caplen + hdrlen); 368 return(1); 369 } 370 #undef bhp 371 372 return(0); 373 } 374 375 /* 376 ** BpfWrite -- Write packet to BPF device. 377 ** 378 ** Parameters: 379 ** rconn - packet to send. 380 ** 381 ** Returns: 382 ** True if write succeeded, False otherwise. 383 ** 384 ** Side Effects: 385 ** None. 386 */ 387 int 388 BpfWrite(RMPCONN *rconn) 389 { 390 if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) { 391 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn)); 392 return(0); 393 } 394 395 return(1); 396 } 397