605 lines
16 KiB
C
605 lines
16 KiB
C
/*
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* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
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* The Regents of the University of California. All rights reserved.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that: (1) source code distributions
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* retain the above copyright notice and this paragraph in its entirety, (2)
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* distributions including binary code include the above copyright notice and
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* this paragraph in its entirety in the documentation or other materials
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* provided with the distribution, and (3) all advertising materials mentioning
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* features or use of this software display the following acknowledgement:
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* ``This product includes software developed by the University of California,
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* Lawrence Berkeley Laboratory and its contributors.'' Neither the name of
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* the University nor the names of its contributors may be used to endorse
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* or promote products derived from this software without specific prior
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* written permission.
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* THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
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* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
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*
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* packet filter subroutines for tcpdump
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* Extraction/creation by Jeffrey Mogul, DECWRL
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*/
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#ifndef lint
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static const char rcsid[] _U_ =
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"@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.97 2008-04-14 20:40:58 guy Exp $ (LBL)";
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#endif
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#ifdef HAVE_CONFIG_H
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#include "config.h"
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#endif
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#include <sys/types.h>
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#include <sys/time.h>
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#include <sys/timeb.h>
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#include <sys/socket.h>
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#include <sys/file.h>
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#include <sys/ioctl.h>
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#include <net/pfilt.h>
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struct mbuf;
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struct rtentry;
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#include <net/if.h>
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#include <netinet/in.h>
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#include <netinet/in_systm.h>
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#include <netinet/ip.h>
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#include <netinet/if_ether.h>
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#include <netinet/ip_var.h>
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#include <netinet/udp.h>
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#include <netinet/udp_var.h>
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#include <netinet/tcp.h>
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#include <netinet/tcpip.h>
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#include <ctype.h>
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#include <errno.h>
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#include <netdb.h>
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#include <stdio.h>
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#include <stdlib.h>
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#include <string.h>
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#include <unistd.h>
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/*
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* Make "pcap.h" not include "pcap/bpf.h"; we are going to include the
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* native OS version, as we need various BPF ioctls from it.
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*/
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#define PCAP_DONT_INCLUDE_PCAP_BPF_H
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#include <net/bpf.h>
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#include "pcap-int.h"
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#ifdef HAVE_OS_PROTO_H
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#include "os-proto.h"
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#endif
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static int pcap_setfilter_pf(pcap_t *, struct bpf_program *);
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/*
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* BUFSPACE is the size in bytes of the packet read buffer. Most tcpdump
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* applications aren't going to need more than 200 bytes of packet header
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* and the read shouldn't return more packets than packetfilter's internal
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* queue limit (bounded at 256).
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*/
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#define BUFSPACE (200 * 256)
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static int
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pcap_read_pf(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
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{
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register u_char *p, *bp;
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register int cc, n, buflen, inc;
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register struct enstamp *sp;
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#ifdef LBL_ALIGN
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struct enstamp stamp;
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#endif
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#ifdef PCAP_FDDIPAD
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register int pad;
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#endif
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again:
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cc = pc->cc;
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if (cc == 0) {
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cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
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if (cc < 0) {
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if (errno == EWOULDBLOCK)
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return (0);
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if (errno == EINVAL &&
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lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
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/*
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* Due to a kernel bug, after 2^31 bytes,
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* the kernel file offset overflows and
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* read fails with EINVAL. The lseek()
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* to 0 will fix things.
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*/
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(void)lseek(pc->fd, 0L, SEEK_SET);
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goto again;
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}
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snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
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pcap_strerror(errno));
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return (-1);
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}
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bp = pc->buffer + pc->offset;
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} else
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bp = pc->bp;
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/*
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* Loop through each packet.
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*/
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n = 0;
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#ifdef PCAP_FDDIPAD
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pad = pc->fddipad;
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#endif
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while (cc > 0) {
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/*
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* Has "pcap_breakloop()" been called?
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* If so, return immediately - if we haven't read any
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* packets, clear the flag and return -2 to indicate
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* that we were told to break out of the loop, otherwise
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* leave the flag set, so that the *next* call will break
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* out of the loop without having read any packets, and
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* return the number of packets we've processed so far.
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*/
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if (pc->break_loop) {
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if (n == 0) {
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pc->break_loop = 0;
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return (-2);
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} else {
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pc->cc = cc;
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pc->bp = bp;
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return (n);
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}
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}
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if (cc < sizeof(*sp)) {
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snprintf(pc->errbuf, sizeof(pc->errbuf),
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"pf short read (%d)", cc);
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return (-1);
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}
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#ifdef LBL_ALIGN
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if ((long)bp & 3) {
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sp = &stamp;
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memcpy((char *)sp, (char *)bp, sizeof(*sp));
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} else
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#endif
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sp = (struct enstamp *)bp;
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if (sp->ens_stamplen != sizeof(*sp)) {
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snprintf(pc->errbuf, sizeof(pc->errbuf),
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"pf short stamplen (%d)",
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sp->ens_stamplen);
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return (-1);
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}
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p = bp + sp->ens_stamplen;
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buflen = sp->ens_count;
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if (buflen > pc->snapshot)
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buflen = pc->snapshot;
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/* Calculate inc before possible pad update */
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inc = ENALIGN(buflen + sp->ens_stamplen);
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cc -= inc;
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bp += inc;
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pc->md.TotPkts++;
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pc->md.TotDrops += sp->ens_dropped;
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pc->md.TotMissed = sp->ens_ifoverflows;
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if (pc->md.OrigMissed < 0)
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pc->md.OrigMissed = pc->md.TotMissed;
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/*
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* Short-circuit evaluation: if using BPF filter
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* in kernel, no need to do it now - we already know
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* the packet passed the filter.
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*
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#ifdef PCAP_FDDIPAD
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* Note: the filter code was generated assuming
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* that pc->fddipad was the amount of padding
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* before the header, as that's what's required
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* in the kernel, so we run the filter before
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* skipping that padding.
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#endif
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*/
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if (pc->md.use_bpf ||
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bpf_filter(pc->fcode.bf_insns, p, sp->ens_count, buflen)) {
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struct pcap_pkthdr h;
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pc->md.TotAccepted++;
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h.ts = sp->ens_tstamp;
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#ifdef PCAP_FDDIPAD
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h.len = sp->ens_count - pad;
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#else
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h.len = sp->ens_count;
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#endif
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#ifdef PCAP_FDDIPAD
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p += pad;
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buflen -= pad;
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#endif
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h.caplen = buflen;
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(*callback)(user, &h, p);
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if (++n >= cnt && cnt > 0) {
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pc->cc = cc;
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pc->bp = bp;
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return (n);
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}
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}
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}
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pc->cc = 0;
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return (n);
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}
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static int
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pcap_inject_pf(pcap_t *p, const void *buf, size_t size)
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{
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int ret;
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ret = write(p->fd, buf, size);
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if (ret == -1) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s",
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pcap_strerror(errno));
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return (-1);
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}
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return (ret);
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}
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static int
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pcap_stats_pf(pcap_t *p, struct pcap_stat *ps)
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{
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/*
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* If packet filtering is being done in the kernel:
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*
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* "ps_recv" counts only packets that passed the filter.
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* This does not include packets dropped because we
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* ran out of buffer space. (XXX - perhaps it should,
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* by adding "ps_drop" to "ps_recv", for compatibility
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* with some other platforms. On the other hand, on
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* some platforms "ps_recv" counts only packets that
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* passed the filter, and on others it counts packets
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* that didn't pass the filter....)
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*
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* "ps_drop" counts packets that passed the kernel filter
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* (if any) but were dropped because the input queue was
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* full.
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*
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* "ps_ifdrop" counts packets dropped by the network
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* inteface (regardless of whether they would have passed
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* the input filter, of course).
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*
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* If packet filtering is not being done in the kernel:
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*
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* "ps_recv" counts only packets that passed the filter.
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*
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* "ps_drop" counts packets that were dropped because the
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* input queue was full, regardless of whether they passed
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* the userland filter.
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*
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* "ps_ifdrop" counts packets dropped by the network
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* inteface (regardless of whether they would have passed
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* the input filter, of course).
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*
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* These statistics don't include packets not yet read from
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* the kernel by libpcap, but they may include packets not
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* yet read from libpcap by the application.
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*/
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ps->ps_recv = p->md.TotAccepted;
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ps->ps_drop = p->md.TotDrops;
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ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
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return (0);
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}
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/*
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* We include the OS's <net/bpf.h>, not our "pcap/bpf.h", so we probably
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* don't get DLT_DOCSIS defined.
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*/
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#ifndef DLT_DOCSIS
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#define DLT_DOCSIS 143
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#endif
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static int
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pcap_activate_pf(pcap_t *p)
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{
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short enmode;
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int backlog = -1; /* request the most */
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struct enfilter Filter;
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struct endevp devparams;
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/*
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* Initially try a read/write open (to allow the inject
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* method to work). If that fails due to permission
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* issues, fall back to read-only. This allows a
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* non-root user to be granted specific access to pcap
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* capabilities via file permissions.
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*
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* XXX - we should have an API that has a flag that
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* controls whether to open read-only or read-write,
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* so that denial of permission to send (or inability
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* to send, if sending packets isn't supported on
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* the device in question) can be indicated at open
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* time.
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*
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* XXX - we assume here that "pfopen()" does not, in fact, modify
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* its argument, even though it takes a "char *" rather than a
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* "const char *" as its first argument. That appears to be
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* the case, at least on Digital UNIX 4.0.
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*/
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p->fd = pfopen(p->opt.source, O_RDWR);
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if (p->fd == -1 && errno == EACCES)
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p->fd = pfopen(p->opt.source, O_RDONLY);
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if (p->fd < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
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your system may not be properly configured; see the packetfilter(4) man page\n",
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p->opt.source, pcap_strerror(errno));
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goto bad;
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}
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p->md.OrigMissed = -1;
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enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
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if (p->opt.promisc)
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enmode |= ENPROMISC;
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if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
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pcap_strerror(errno));
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goto bad;
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}
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#ifdef ENCOPYALL
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/* Try to set COPYALL mode so that we see packets to ourself */
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enmode = ENCOPYALL;
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(void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
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#endif
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/* set the backlog */
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if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
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pcap_strerror(errno));
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goto bad;
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}
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/* discover interface type */
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if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
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pcap_strerror(errno));
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goto bad;
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}
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/* HACK: to compile prior to Ultrix 4.2 */
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#ifndef ENDT_FDDI
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#define ENDT_FDDI 4
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#endif
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switch (devparams.end_dev_type) {
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case ENDT_10MB:
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p->linktype = DLT_EN10MB;
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p->offset = 2;
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/*
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* This is (presumably) a real Ethernet capture; give it a
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* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
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* that an application can let you choose it, in case you're
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* capturing DOCSIS traffic that a Cisco Cable Modem
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* Termination System is putting out onto an Ethernet (it
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* doesn't put an Ethernet header onto the wire, it puts raw
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* DOCSIS frames out on the wire inside the low-level
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* Ethernet framing).
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*/
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p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
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/*
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* If that fails, just leave the list empty.
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*/
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if (p->dlt_list != NULL) {
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p->dlt_list[0] = DLT_EN10MB;
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p->dlt_list[1] = DLT_DOCSIS;
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p->dlt_count = 2;
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}
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break;
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case ENDT_FDDI:
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p->linktype = DLT_FDDI;
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break;
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#ifdef ENDT_SLIP
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case ENDT_SLIP:
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p->linktype = DLT_SLIP;
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break;
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#endif
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#ifdef ENDT_PPP
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case ENDT_PPP:
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p->linktype = DLT_PPP;
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break;
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#endif
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#ifdef ENDT_LOOPBACK
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case ENDT_LOOPBACK:
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/*
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* It appears to use Ethernet framing, at least on
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* Digital UNIX 4.0.
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*/
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p->linktype = DLT_EN10MB;
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p->offset = 2;
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break;
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#endif
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#ifdef ENDT_TRN
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case ENDT_TRN:
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p->linktype = DLT_IEEE802;
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break;
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#endif
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default:
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/*
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* XXX - what about ENDT_IEEE802? The pfilt.h header
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* file calls this "IEEE 802 networks (non-Ethernet)",
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* but that doesn't specify a specific link layer type;
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* it could be 802.4, or 802.5 (except that 802.5 is
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* ENDT_TRN), or 802.6, or 802.11, or.... That's why
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* DLT_IEEE802 was hijacked to mean Token Ring in various
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* BSDs, and why we went along with that hijacking.
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*
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* XXX - what about ENDT_HDLC and ENDT_NULL?
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* Presumably, as ENDT_OTHER is just "Miscellaneous
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* framing", there's not much we can do, as that
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* doesn't specify a particular type of header.
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*/
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
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"unknown data-link type %u", devparams.end_dev_type);
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goto bad;
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}
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/* set truncation */
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#ifdef PCAP_FDDIPAD
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if (p->linktype == DLT_FDDI) {
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p->fddipad = PCAP_FDDIPAD;
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/* packetfilter includes the padding in the snapshot */
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p->snapshot += PCAP_FDDIPAD;
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} else
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p->fddipad = 0;
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#endif
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if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&p->snapshot) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
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pcap_strerror(errno));
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goto bad;
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}
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/* accept all packets */
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memset(&Filter, 0, sizeof(Filter));
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Filter.enf_Priority = 37; /* anything > 2 */
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Filter.enf_FilterLen = 0; /* means "always true" */
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if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
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pcap_strerror(errno));
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goto bad;
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}
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if (p->md.timeout != 0) {
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struct timeval timeout;
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timeout.tv_sec = p->md.timeout / 1000;
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timeout.tv_usec = (p->md.timeout * 1000) % 1000000;
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if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
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snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
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pcap_strerror(errno));
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goto bad;
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}
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}
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p->bufsize = BUFSPACE;
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p->buffer = (u_char*)malloc(p->bufsize + p->offset);
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if (p->buffer == NULL) {
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strlcpy(p->errbuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
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goto bad;
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}
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/*
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* "select()" and "poll()" work on packetfilter devices.
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*/
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p->selectable_fd = p->fd;
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p->read_op = pcap_read_pf;
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p->inject_op = pcap_inject_pf;
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p->setfilter_op = pcap_setfilter_pf;
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p->setdirection_op = NULL; /* Not implemented. */
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p->set_datalink_op = NULL; /* can't change data link type */
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p->getnonblock_op = pcap_getnonblock_fd;
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p->setnonblock_op = pcap_setnonblock_fd;
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p->stats_op = pcap_stats_pf;
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return (0);
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bad:
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pcap_cleanup_live_common(p);
|
|
return (PCAP_ERROR);
|
|
}
|
|
|
|
pcap_t *
|
|
pcap_create_interface(const char *device, char *ebuf)
|
|
{
|
|
pcap_t *p;
|
|
|
|
p = pcap_create_common(device, ebuf);
|
|
if (p == NULL)
|
|
return (NULL);
|
|
|
|
p->activate_op = pcap_activate_pf;
|
|
return (p);
|
|
}
|
|
|
|
int
|
|
pcap_platform_finddevs(pcap_if_t **alldevsp, char *errbuf)
|
|
{
|
|
return (0);
|
|
}
|
|
|
|
static int
|
|
pcap_setfilter_pf(pcap_t *p, struct bpf_program *fp)
|
|
{
|
|
struct bpf_version bv;
|
|
|
|
/*
|
|
* See if BIOCVERSION works. If not, we assume the kernel doesn't
|
|
* support BPF-style filters (it's not documented in the bpf(7)
|
|
* or packetfiler(7) man pages, but the code used to fail if
|
|
* BIOCSETF worked but BIOCVERSION didn't, and I've seen it do
|
|
* kernel filtering in DU 4.0, so presumably BIOCVERSION works
|
|
* there, at least).
|
|
*/
|
|
if (ioctl(p->fd, BIOCVERSION, (caddr_t)&bv) >= 0) {
|
|
/*
|
|
* OK, we have the version of the BPF interpreter;
|
|
* is it the same major version as us, and the same
|
|
* or better minor version?
|
|
*/
|
|
if (bv.bv_major == BPF_MAJOR_VERSION &&
|
|
bv.bv_minor >= BPF_MINOR_VERSION) {
|
|
/*
|
|
* Yes. Try to install the filter.
|
|
*/
|
|
if (ioctl(p->fd, BIOCSETF, (caddr_t)fp) < 0) {
|
|
snprintf(p->errbuf, sizeof(p->errbuf),
|
|
"BIOCSETF: %s", pcap_strerror(errno));
|
|
return (-1);
|
|
}
|
|
|
|
/*
|
|
* OK, that succeeded. We're doing filtering in
|
|
* the kernel. (We assume we don't have a
|
|
* userland filter installed - that'd require
|
|
* a previous version check to have failed but
|
|
* this one to succeed.)
|
|
*
|
|
* XXX - this message should be supplied to the
|
|
* application as a warning of some sort,
|
|
* except that if it's a GUI application, it's
|
|
* not clear that it should be displayed in
|
|
* a window to annoy the user.
|
|
*/
|
|
fprintf(stderr, "tcpdump: Using kernel BPF filter\n");
|
|
p->md.use_bpf = 1;
|
|
|
|
/*
|
|
* Discard any previously-received packets,
|
|
* as they might have passed whatever filter
|
|
* was formerly in effect, but might not pass
|
|
* this filter (BIOCSETF discards packets buffered
|
|
* in the kernel, so you can lose packets in any
|
|
* case).
|
|
*/
|
|
p->cc = 0;
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* We can't use the kernel's BPF interpreter; don't give
|
|
* up, just log a message and be inefficient.
|
|
*
|
|
* XXX - this should really be supplied to the application
|
|
* as a warning of some sort.
|
|
*/
|
|
fprintf(stderr,
|
|
"tcpdump: Requires BPF language %d.%d or higher; kernel is %d.%d\n",
|
|
BPF_MAJOR_VERSION, BPF_MINOR_VERSION,
|
|
bv.bv_major, bv.bv_minor);
|
|
}
|
|
|
|
/*
|
|
* We couldn't do filtering in the kernel; do it in userland.
|
|
*/
|
|
if (install_bpf_program(p, fp) < 0)
|
|
return (-1);
|
|
|
|
/*
|
|
* XXX - this message should be supplied by the application as
|
|
* a warning of some sort.
|
|
*/
|
|
fprintf(stderr, "tcpdump: Filtering in user process\n");
|
|
p->md.use_bpf = 0;
|
|
return (0);
|
|
}
|