/* $OpenBSD: bpf.c,v 1.22 2015/04/18 18:28:38 deraadt Exp $ */ /* $NetBSD: bpf.c,v 1.5.2.1 1995/11/14 08:45:42 thorpej Exp $ */ /* * Copyright (c) 1988, 1992 The University of Utah and the Center * for Software Science (CSS). * Copyright (c) 1992, 1993 * The Regents of the University of California. All rights reserved. * * This code is derived from software contributed to Berkeley by * the Center for Software Science of the University of Utah Computer * Science Department. CSS requests users of this software to return * to css-dist@cs.utah.edu any improvements that they make and grant * CSS redistribution rights. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. Neither the name of the University nor the names of its contributors * may be used to endorse or promote products derived from this software * without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF * SUCH DAMAGE. * * from: @(#)bpf.c 8.1 (Berkeley) 6/4/93 * * From: Utah Hdr: bpf.c 3.1 92/07/06 * Author: Jeff Forys, University of Utah CSS */ #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include "defs.h" #include "pathnames.h" static int BpfFd = -1; static unsigned int BpfLen = 0; static u_int8_t *BpfPkt = NULL; /* ** BpfOpen -- Open and initialize a BPF device. ** ** Parameters: ** None. ** ** Returns: ** File descriptor of opened BPF device ** ** Side Effects: ** If an error is encountered, the program terminates here. */ int BpfOpen(void) { struct ifreq ifr; char bpfdev[32]; int n = 0; /* * Open the first available BPF device. */ do { (void) snprintf(bpfdev, sizeof bpfdev, _PATH_BPF, n++); BpfFd = open(bpfdev, O_RDWR); } while (BpfFd < 0 && (errno == EBUSY || errno == EPERM)); if (BpfFd < 0) { syslog(LOG_ERR, "bpf: no available devices: %m"); DoExit(); } /* * Set interface name for bpf device, get data link layer * type and make sure it's type Ethernet. */ (void) strncpy(ifr.ifr_name, IntfName, sizeof(ifr.ifr_name)); if (ioctl(BpfFd, BIOCSETIF, (caddr_t)&ifr) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCSETIF,%s): %m", IntfName); DoExit(); } /* * Make sure we are dealing with an Ethernet device. */ if (ioctl(BpfFd, BIOCGDLT, (caddr_t)&n) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCGDLT): %m"); DoExit(); } if (n != DLT_EN10MB) { syslog(LOG_ERR,"bpf: %s: data-link type %d unsupported", IntfName, n); DoExit(); } /* * On read(), return packets immediately (do not buffer them). */ n = 1; if (ioctl(BpfFd, BIOCIMMEDIATE, (caddr_t)&n) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCIMMEDIATE): %m"); DoExit(); } /* * Try to enable the chip/driver's multicast address filter to * grab our RMP address. If this fails, try promiscuous mode. * If this fails, there's no way we are going to get any RMP * packets so just exit here. */ #ifdef MSG_EOR ifr.ifr_addr.sa_len = RMP_ADDRLEN + 2; #endif ifr.ifr_addr.sa_family = AF_UNSPEC; bcopy(&RmpMcastAddr[0], (char *)&ifr.ifr_addr.sa_data[0], RMP_ADDRLEN); if (ioctl(BpfFd, SIOCADDMULTI, (caddr_t)&ifr) < 0) { syslog(LOG_WARNING, "bpf: can't add mcast addr (%m), setting promiscuous mode"); if (ioctl(BpfFd, BIOCPROMISC, (caddr_t)0) < 0) { syslog(LOG_ERR, "bpf: can't set promiscuous mode: %m"); DoExit(); } } /* * Ask BPF how much buffer space it requires and allocate one. */ if (ioctl(BpfFd, BIOCGBLEN, (caddr_t)&BpfLen) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCGBLEN): %m"); DoExit(); } if (BpfPkt == NULL) BpfPkt = (u_int8_t *)malloc(BpfLen); if (BpfPkt == NULL) { syslog(LOG_ERR, "bpf: out of memory (%u bytes for bpfpkt)", BpfLen); DoExit(); } /* * Write a little program to snarf RMP Boot packets and stuff * it down BPF's throat (i.e. set up the packet filter). */ { #define RMP(field) offsetof(struct rmp_packet, field) static struct bpf_insn bpf_insn[] = { /* make sure it is a 802.3 packet */ { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_hdr.len) }, { BPF_JMP|BPF_JGE|BPF_K, 7, 0, 0x600 }, { BPF_LD|BPF_B|BPF_ABS, 0, 0, RMP(hp_llc.dsap) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 5, IEEE_DSAP_HP }, { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.cntrl) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 3, IEEE_CNTL_HP }, { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.dxsap) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, HPEXT_DXSAP }, { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, { BPF_RET|BPF_K, 0, 0, 0x0 } }; static struct bpf_insn bpf_wf_insn[] = { /* make sure it is a 802.3 packet */ { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_hdr.len) }, { BPF_JMP|BPF_JGE|BPF_K, 12, 0, 0x600 }, /* check the SNAP header */ { BPF_LD|BPF_B|BPF_ABS, 0, 0, RMP(hp_llc.dsap) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 10, IEEE_DSAP_HP }, { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.cntrl) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 8, IEEE_CNTL_HP }, { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.sxsap) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 6, HPEXT_DXSAP }, { BPF_LD|BPF_H|BPF_ABS, 0, 0, RMP(hp_llc.dxsap) }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 4, HPEXT_SXSAP }, /* check return type code */ { BPF_LD|BPF_B|BPF_ABS, 0, 0, RMP(rmp_proto.rmp_raw.rmp_type) }, { BPF_JMP|BPF_JEQ|BPF_K, 1, 0, RMP_BOOT_REPL }, { BPF_JMP|BPF_JEQ|BPF_K, 0, 1, RMP_READ_REPL }, { BPF_RET|BPF_K, 0, 0, RMP_MAX_PACKET }, { BPF_RET|BPF_K, 0, 0, 0x0 } }; #undef RMP static struct bpf_program bpf_pgm = { sizeof(bpf_insn)/sizeof(bpf_insn[0]), bpf_insn }; static struct bpf_program bpf_w_pgm = { sizeof(bpf_wf_insn)/sizeof(bpf_wf_insn[0]), bpf_wf_insn }; if (ioctl(BpfFd, BIOCSETF, (caddr_t)&bpf_pgm) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCSETF): %m"); DoExit(); } if (ioctl(BpfFd, BIOCSETWF, (caddr_t)&bpf_w_pgm) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCSETWF): %m"); DoExit(); } if (ioctl(BpfFd, BIOCLOCK) < 0) { syslog(LOG_ERR, "bpf: ioctl(BIOCLOCK): %m"); DoExit(); } } return(BpfFd); } /* ** BPF GetIntfName -- Return the name of a network interface attached to ** the system, or 0 if none can be found. The interface ** must be configured up; the lowest unit number is ** preferred; loopback is ignored. ** ** Parameters: ** errmsg - if no network interface found, *errmsg explains why. ** ** Returns: ** A (static) pointer to interface name, or NULL on error. ** ** Side Effects: ** None. */ char * BpfGetIntfName(char **errmsg) { int minunit = 999, n; char *cp; const char *errstr; static char device[IFNAMSIZ]; static char errbuf[128] = "No Error!"; struct ifaddrs *ifap, *ifa, *mp = NULL; if (errmsg != NULL) *errmsg = errbuf; if (getifaddrs(&ifap) != 0) { (void) strlcpy(errbuf, "bpf: getifaddrs: %m", sizeof(errbuf)); return(NULL); } for (ifa = ifap; ifa; ifa = ifa->ifa_next) { /* * If interface is down or this is the loopback interface, * ignore it. */ if ((ifa->ifa_flags & IFF_UP) == 0 || #ifdef IFF_LOOPBACK (ifa->ifa_flags & IFF_LOOPBACK)) #else (strcmp(ifa->ifa_name, "lo0") == 0)) #endif continue; for (cp = ifa->ifa_name; !isdigit((unsigned char)*cp); ++cp) ; n = strtonum(cp, 0, INT_MAX, &errstr); if (errstr == NULL && n < minunit) { minunit = n; mp = ifa; } } if (mp == 0) { (void) strlcpy(errbuf, "bpf: no interfaces found", sizeof(errbuf)); freeifaddrs(ifap); return(NULL); } (void) strlcpy(device, mp->ifa_name, sizeof device); freeifaddrs(ifap); return(device); } /* ** BpfRead -- Read packets from a BPF device and fill in `rconn'. ** ** Parameters: ** rconn - filled in with next packet. ** doread - is True if we can issue a read() syscall. ** ** Returns: ** True if `rconn' contains a new packet, False otherwise. ** ** Side Effects: ** None. */ int BpfRead(RMPCONN *rconn, int doread) { int datlen, caplen, hdrlen; static u_int8_t *bp = NULL, *ep = NULL; int cc; /* * The read() may block, or it may return one or more packets. * We let the caller decide whether or not we can issue a read(). */ if (doread) { if ((cc = read(BpfFd, (char *)BpfPkt, (int)BpfLen)) < 0) { syslog(LOG_ERR, "bpf: read: %m"); return(0); } else { bp = BpfPkt; ep = BpfPkt + cc; } } #define bhp ((struct bpf_hdr *)bp) /* * If there is a new packet in the buffer, stuff it into `rconn' * and return a success indication. */ if (bp < ep) { datlen = bhp->bh_datalen; caplen = bhp->bh_caplen; hdrlen = bhp->bh_hdrlen; if (caplen != datlen) syslog(LOG_ERR, "bpf: short packet dropped (%d of %d bytes)", caplen, datlen); else if (caplen > sizeof(struct rmp_packet)) syslog(LOG_ERR, "bpf: large packet dropped (%d bytes)", caplen); else { rconn->rmplen = caplen; bcopy((char *)&bhp->bh_tstamp, (char *)&rconn->tstamp, sizeof(struct timeval)); bcopy((char *)bp + hdrlen, (char *)&rconn->rmp, caplen); } bp += BPF_WORDALIGN(caplen + hdrlen); return(1); } #undef bhp return(0); } /* ** BpfWrite -- Write packet to BPF device. ** ** Parameters: ** rconn - packet to send. ** ** Returns: ** True if write succeeded, False otherwise. ** ** Side Effects: ** None. */ int BpfWrite(RMPCONN *rconn) { if (write(BpfFd, (char *)&rconn->rmp, rconn->rmplen) < 0) { syslog(LOG_ERR, "write: %s: %m", EnetStr(rconn)); return(0); } return(1); }