1 /* $OpenBSD: bpf.c,v 1.27 2019/06/28 13:32:50 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/ioctl.h> 47 #include <sys/socket.h> 48 49 #include <net/if.h> 50 #include <net/bpf.h> 51 52 #include <ctype.h> 53 #include <errno.h> 54 #include <fcntl.h> 55 #include <stddef.h> 56 #include <stdio.h> 57 #include <stdlib.h> 58 #include <string.h> 59 #include <syslog.h> 60 #include <unistd.h> 61 #include <limits.h> 62 #include <ifaddrs.h> 63 #include "defs.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 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 int n; 86 87 if ((BpfFd = open("/dev/bpf", O_RDWR)) == -1) { 88 syslog(LOG_ERR, "bpf: can't open device: %m"); 89 DoExit(); 90 } 91 92 /* 93 * Set interface name for bpf device, get data link layer 94 * type and make sure it's type Ethernet. 95 */ 96 (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name)); 97 if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) == -1) { 98 syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName); 99 DoExit(); 100 } 101 102 /* 103 * Make sure we are dealing with an Ethernet device. 104 */ 105 if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) == -1) { 106 syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m"); 107 DoExit(); 108 } 109 if (n != DLT_EN10MB) { 110 syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported", 111 IntfName, n); 112 DoExit(); 113 } 114 115 /* 116 * On read(), return packets immediately (do not buffer them). 117 */ 118 n = 1; 119 if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) == -1) { 120 syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m"); 121 DoExit(); 122 } 123 124 /* 125 * Try to enable the chip/driver's multicast address filter to 126 * grab our RMP address. If this fails, try promiscuous mode. 127 * If this fails, there's no way we are going to get any RMP 128 * packets so just exit here. 129 */ 130 #ifdef MSG_EOR 131 ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; 132 #endif 133 ifr.ifr_addr.sa_family = AF_UNSPEC; 134 bcopy(&RmpMcastAddr[0], (char *)&ifr.ifr_addr.sa_data[0], RMP_ADDRLEN); 135 if (ioctl(BpfFd, SIOCADDMULTI, (caddr_t)&ifr) == -1) { 136 syslog(LOG_WARNING, 137 "bpf: can't add mcast addr (%m), setting promiscuous mode"); 138 139 if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) == -1) { 140 syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m"); 141 DoExit(); 142 } 143 } 144 145 /* 146 * Ask BPF how much buffer space it requires and allocate one. 147 */ 148 if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) == -1) { 149 syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m"); 150 DoExit(); 151 } 152 if (BpfPkt == NULL) 153 BpfPkt = malloc(BpfLen); 154 155 if (BpfPkt == NULL) { 156 syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)", 157 BpfLen); 158 DoExit(); 159 } 160 161 /* 162 * Write a little program to snarf RMP Boot packets and stuff 163 * it down BPF's throat (i.e. set up the packet filter). 164 */ 165 { 166 #define RMP(field) offsetof(struct rmp_packet, field) 167 static struct bpf_insn bpf_insn[] = { 168 /* make sure it is a 802.3 packet */ 169 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_hdr.len) }, 170 { BPF_JMP|BPF_JGE|BPF_K, 7, 0, 0x600 }, 171 172 { BPF_LD|BPF_B|BPF_ABS, 0, 0, RMP(hp_llc.dsap) }, 173 { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP }, 174 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.cntrl) }, 175 { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP }, 176 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.dxsap) }, 177 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP }, 178 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 179 { BPF_RET|BPF_K, 0, 0, 0x0 } 180 }; 181 182 static struct bpf_insn bpf_wf_insn[] = { 183 /* make sure it is a 802.3 packet */ 184 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_hdr.len) }, 185 { BPF_JMP|BPF_JGE|BPF_K, 12, 0, 0x600 }, 186 187 /* check the SNAP header */ 188 { BPF_LD|BPF_B|BPF_ABS, 0, 0, RMP(hp_llc.dsap) }, 189 { BPF_JMP|BPF_JEQ|BPF_K, 0, 10, IEEE_DSAP_HP }, 190 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.cntrl) }, 191 { BPF_JMP|BPF_JEQ|BPF_K, 0, 8, IEEE_CNTL_HP }, 192 193 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.sxsap) }, 194 { BPF_JMP|BPF_JEQ|BPF_K, 0, 6, HPEXT_DXSAP }, 195 { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.dxsap) }, 196 { BPF_JMP|BPF_JEQ|BPF_K, 0, 4, HPEXT_SXSAP }, 197 198 /* check return type code */ 199 { BPF_LD|BPF_B|BPF_ABS, 0, 0, 200 RMP(rmp_proto.rmp_raw.rmp_type) }, 201 { BPF_JMP|BPF_JEQ|BPF_K, 1, 0, RMP_BOOT_REPL }, 202 { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, RMP_READ_REPL }, 203 204 { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, 205 { BPF_RET|BPF_K, 0, 0, 0x0 } 206 }; 207 #undef RMP 208 static struct bpf_program bpf_pgm = { 209 sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn 210 }; 211 212 static struct bpf_program bpf_w_pgm = { 213 sizeof(bpf_wf_insn)/sizeof(bpf_wf_insn[0]), bpf_wf_insn 214 }; 215 216 if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) == -1) { 217 syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m"); 218 DoExit(); 219 } 220 221 if (ioctl(BpfFd, BIOCSETWF, (caddr_t)&bpf_w_pgm) == -1) { 222 syslog(LOG_ERR, "bpf: ioctl(BIOCSETWF): %m"); 223 DoExit(); 224 } 225 226 if (ioctl(BpfFd, BIOCLOCK) == -1) { 227 syslog(LOG_ERR, "bpf: ioctl(BIOCLOCK): %m"); 228 DoExit(); 229 } 230 } 231 232 return(BpfFd); 233 } 234 235 /* 236 ** BPF GetIntfName -- Return the name of a network interface attached to 237 ** the system, or 0 if none can be found. The interface 238 ** must be configured up; the lowest unit number is 239 ** preferred; loopback is ignored. 240 ** 241 ** Parameters: 242 ** errmsg - if no network interface found, *errmsg explains why. 243 ** 244 ** Returns: 245 ** A (static) pointer to interface name, or NULL on error. 246 ** 247 ** Side Effects: 248 ** None. 249 */ 250 char * 251 BpfGetIntfName(char **errmsg) 252 { 253 int minunit = 999, n; 254 char *cp; 255 const char *errstr; 256 static char device[IFNAMSIZ]; 257 static char errbuf[128] = "No Error!"; 258 struct ifaddrs *ifap, *ifa, *mp = NULL; 259 260 if (errmsg != NULL) 261 *errmsg = errbuf; 262 263 if (getifaddrs(&ifap) != 0) { 264 (void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf)); 265 return(NULL); 266 } 267 268 for (ifa = ifap; ifa; ifa = ifa->ifa_next) { 269 /* 270 * If interface is down or this is the loopback interface, 271 * ignore it. 272 */ 273 if ((ifa->ifa_flags & IFF_UP) == 0 || 274 #ifdef IFF_LOOPBACK 275 (ifa->ifa_flags & IFF_LOOPBACK)) 276 #else 277 (strcmp(ifa->ifa_name, "lo0") == 0)) 278 #endif 279 continue; 280 281 for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp) 282 ; 283 n = strtonum(cp, 0, INT_MAX, &errstr); 284 if (errstr == NULL && n < minunit) { 285 minunit = n; 286 mp = ifa; 287 } 288 } 289 290 if (mp == 0) { 291 (void) strlcpy(errbuf, "bpf: no interfaces found", 292 sizeof(errbuf)); 293 freeifaddrs(ifap); 294 return(NULL); 295 } 296 297 (void) strlcpy(device, mp->ifa_name, sizeof device); 298 freeifaddrs(ifap); 299 return(device); 300 } 301 302 /* 303 ** BpfRead -- Read packets from a BPF device and fill in `rconn'. 304 ** 305 ** Parameters: 306 ** rconn - filled in with next packet. 307 ** doread - is True if we can issue a read() syscall. 308 ** 309 ** Returns: 310 ** True if `rconn' contains a new packet, False otherwise. 311 ** 312 ** Side Effects: 313 ** None. 314 */ 315 int 316 BpfRead(RMPCONN *rconn, int doread) 317 { 318 int datlen, caplen, hdrlen; 319 static u_int8_t *bp = NULL, *ep = NULL; 320 int cc; 321 322 /* 323 * The read() may block, or it may return one or more packets. 324 * We let the caller decide whether or not we can issue a read(). 325 */ 326 if (doread) { 327 if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) == -1) { 328 syslog(LOG_ERR, "bpf: read: %m"); 329 return(0); 330 } else { 331 bp = BpfPkt; 332 ep = BpfPkt + cc; 333 } 334 } 335 336 #define bhp ((struct bpf_hdr *)bp) 337 /* 338 * If there is a new packet in the buffer, stuff it into `rconn' 339 * and return a success indication. 340 */ 341 if (bp < ep) { 342 datlen = bhp->bh_datalen; 343 caplen = bhp->bh_caplen; 344 hdrlen = bhp->bh_hdrlen; 345 346 if (caplen != datlen) 347 syslog(LOG_ERR, 348 "bpf: short packet dropped (%d of %d bytes)", 349 caplen, datlen); 350 else if (caplen > sizeof(struct rmp_packet)) 351 syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)", 352 caplen); 353 else { 354 rconn->rmplen = caplen; 355 rconn->tstamp.tv_sec = bhp->bh_tstamp.tv_sec; 356 rconn->tstamp.tv_usec = bhp->bh_tstamp.tv_usec; 357 bcopy((char *)bp + hdrlen, (char *)&rconn->rmp, caplen); 358 } 359 bp += BPF_WORDALIGN(caplen + hdrlen); 360 return(1); 361 } 362 #undef bhp 363 364 return(0); 365 } 366 367 /* 368 ** BpfWrite -- Write packet to BPF device. 369 ** 370 ** Parameters: 371 ** rconn - packet to send. 372 ** 373 ** Returns: 374 ** True if write succeeded, False otherwise. 375 ** 376 ** Side Effects: 377 ** None. 378 */ 379 int 380 BpfWrite(RMPCONN *rconn) 381 { 382 if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) == -1) { 383 syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn)); 384 return(0); 385 } 386 387 return(1); 388 } 389