freebsd-dev/contrib/libpcap/pcap-pf.c

539 lines
14 KiB
C

/*
* Copyright (c) 1990, 1991, 1992, 1993, 1994, 1995, 1996
* The Regents of the University of California. All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that: (1) source code distributions
* retain the above copyright notice and this paragraph in its entirety, (2)
* distributions including binary code include the above copyright notice and
* this paragraph in its entirety in the documentation or other materials
* provided with the distribution, and (3) all advertising materials mentioning
* features or use of this software display the following acknowledgement:
* ``This product includes software developed by the University of California,
* Lawrence Berkeley Laboratory and its contributors.'' 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 ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
* WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
*
* packet filter subroutines for tcpdump
* Extraction/creation by Jeffrey Mogul, DECWRL
*/
#ifndef lint
static const char rcsid[] _U_ =
"@(#) $Header: /tcpdump/master/libpcap/pcap-pf.c,v 1.79.2.5 2003/11/22 00:32:55 guy Exp $ (LBL)";
#endif
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <sys/types.h>
#include <sys/time.h>
#include <sys/timeb.h>
#include <sys/socket.h>
#include <sys/file.h>
#include <sys/ioctl.h>
#include <net/pfilt.h>
struct mbuf;
struct rtentry;
#include <net/if.h>
#include <netinet/in.h>
#include <netinet/in_systm.h>
#include <netinet/ip.h>
#include <netinet/if_ether.h>
#include <netinet/ip_var.h>
#include <netinet/udp.h>
#include <netinet/udp_var.h>
#include <netinet/tcp.h>
#include <netinet/tcpip.h>
#include <ctype.h>
#include <errno.h>
#include <netdb.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
/*
* Make "pcap.h" not include "pcap-bpf.h"; we are going to include the
* native OS version, as we need various BPF ioctls from it.
*/
#define PCAP_DONT_INCLUDE_PCAP_BPF_H
#include <net/bpf.h>
#include "pcap-int.h"
#ifdef HAVE_OS_PROTO_H
#include "os-proto.h"
#endif
static int pcap_setfilter_pf(pcap_t *, struct bpf_program *);
/*
* BUFSPACE is the size in bytes of the packet read buffer. Most tcpdump
* applications aren't going to need more than 200 bytes of packet header
* and the read shouldn't return more packets than packetfilter's internal
* queue limit (bounded at 256).
*/
#define BUFSPACE (200 * 256)
static int
pcap_read_pf(pcap_t *pc, int cnt, pcap_handler callback, u_char *user)
{
register u_char *p, *bp;
struct bpf_insn *fcode;
register int cc, n, buflen, inc;
register struct enstamp *sp;
#ifdef LBL_ALIGN
struct enstamp stamp;
#endif
#ifdef PCAP_FDDIPAD
register int pad;
#endif
fcode = pc->md.use_bpf ? NULL : pc->fcode.bf_insns;
again:
cc = pc->cc;
if (cc == 0) {
cc = read(pc->fd, (char *)pc->buffer + pc->offset, pc->bufsize);
if (cc < 0) {
if (errno == EWOULDBLOCK)
return (0);
if (errno == EINVAL &&
lseek(pc->fd, 0L, SEEK_CUR) + pc->bufsize < 0) {
/*
* Due to a kernel bug, after 2^31 bytes,
* the kernel file offset overflows and
* read fails with EINVAL. The lseek()
* to 0 will fix things.
*/
(void)lseek(pc->fd, 0L, SEEK_SET);
goto again;
}
snprintf(pc->errbuf, sizeof(pc->errbuf), "pf read: %s",
pcap_strerror(errno));
return (-1);
}
bp = pc->buffer + pc->offset;
} else
bp = pc->bp;
/*
* Loop through each packet.
*/
n = 0;
#ifdef PCAP_FDDIPAD
if (pc->linktype == DLT_FDDI)
pad = pcap_fddipad;
else
pad = 0;
#endif
while (cc > 0) {
/*
* Has "pcap_breakloop()" been called?
* If so, return immediately - if we haven't read any
* packets, clear the flag and return -2 to indicate
* that we were told to break out of the loop, otherwise
* leave the flag set, so that the *next* call will break
* out of the loop without having read any packets, and
* return the number of packets we've processed so far.
*/
if (pc->break_loop) {
if (n == 0) {
pc->break_loop = 0;
return (-2);
} else {
pc->cc = cc;
pc->bp = bp;
return (n);
}
}
if (cc < sizeof(*sp)) {
snprintf(pc->errbuf, sizeof(pc->errbuf),
"pf short read (%d)", cc);
return (-1);
}
#ifdef LBL_ALIGN
if ((long)bp & 3) {
sp = &stamp;
memcpy((char *)sp, (char *)bp, sizeof(*sp));
} else
#endif
sp = (struct enstamp *)bp;
if (sp->ens_stamplen != sizeof(*sp)) {
snprintf(pc->errbuf, sizeof(pc->errbuf),
"pf short stamplen (%d)",
sp->ens_stamplen);
return (-1);
}
p = bp + sp->ens_stamplen;
buflen = sp->ens_count;
if (buflen > pc->snapshot)
buflen = pc->snapshot;
/* Calculate inc before possible pad update */
inc = ENALIGN(buflen + sp->ens_stamplen);
cc -= inc;
bp += inc;
#ifdef PCAP_FDDIPAD
p += pad;
buflen -= pad;
#endif
pc->md.TotPkts++;
pc->md.TotDrops += sp->ens_dropped;
pc->md.TotMissed = sp->ens_ifoverflows;
if (pc->md.OrigMissed < 0)
pc->md.OrigMissed = pc->md.TotMissed;
/*
* Short-circuit evaluation: if using BPF filter
* in kernel, no need to do it now.
*/
if (fcode == NULL ||
bpf_filter(fcode, p, sp->ens_count, buflen)) {
struct pcap_pkthdr h;
pc->md.TotAccepted++;
h.ts = sp->ens_tstamp;
#ifdef PCAP_FDDIPAD
h.len = sp->ens_count - pad;
#else
h.len = sp->ens_count;
#endif
h.caplen = buflen;
(*callback)(user, &h, p);
if (++n >= cnt && cnt > 0) {
pc->cc = cc;
pc->bp = bp;
return (n);
}
}
}
pc->cc = 0;
return (n);
}
static int
pcap_stats_pf(pcap_t *p, struct pcap_stat *ps)
{
/*
* If packet filtering is being done in the kernel:
*
* "ps_recv" counts only packets that passed the filter.
* This does not include packets dropped because we
* ran out of buffer space. (XXX - perhaps it should,
* by adding "ps_drop" to "ps_recv", for compatibility
* with some other platforms. On the other hand, on
* some platforms "ps_recv" counts only packets that
* passed the filter, and on others it counts packets
* that didn't pass the filter....)
*
* "ps_drop" counts packets that passed the kernel filter
* (if any) but were dropped because the input queue was
* full.
*
* "ps_ifdrop" counts packets dropped by the network
* inteface (regardless of whether they would have passed
* the input filter, of course).
*
* If packet filtering is not being done in the kernel:
*
* "ps_recv" counts only packets that passed the filter.
*
* "ps_drop" counts packets that were dropped because the
* input queue was full, regardless of whether they passed
* the userland filter.
*
* "ps_ifdrop" counts packets dropped by the network
* inteface (regardless of whether they would have passed
* the input filter, of course).
*
* These statistics don't include packets not yet read from
* the kernel by libpcap, but they may include packets not
* yet read from libpcap by the application.
*/
ps->ps_recv = p->md.TotAccepted;
ps->ps_drop = p->md.TotDrops;
ps->ps_ifdrop = p->md.TotMissed - p->md.OrigMissed;
return (0);
}
static void
pcap_close_pf(pcap_t *p)
{
if (p->buffer != NULL)
free(p->buffer);
if (p->fd >= 0)
close(p->fd);
}
pcap_t *
pcap_open_live(const char *device, int snaplen, int promisc, int to_ms,
char *ebuf)
{
pcap_t *p;
short enmode;
int backlog = -1; /* request the most */
struct enfilter Filter;
struct endevp devparams;
p = (pcap_t *)malloc(sizeof(*p));
if (p == NULL) {
snprintf(ebuf, PCAP_ERRBUF_SIZE,
"pcap_open_live: %s", pcap_strerror(errno));
return (0);
}
memset(p, 0, sizeof(*p));
/*
* XXX - we assume here that "pfopen()" does not, in fact, modify
* its argument, even though it takes a "char *" rather than a
* "const char *" as its first argument. That appears to be
* the case, at least on Digital UNIX 4.0.
*/
p->fd = pfopen(device, O_RDONLY);
if (p->fd < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\
your system may not be properly configured; see the packetfilter(4) man page\n",
device, pcap_strerror(errno));
goto bad;
}
p->md.OrigMissed = -1;
enmode = ENTSTAMP|ENBATCH|ENNONEXCL;
if (promisc)
enmode |= ENPROMISC;
if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCMBIS: %s",
pcap_strerror(errno));
goto bad;
}
#ifdef ENCOPYALL
/* Try to set COPYALL mode so that we see packets to ourself */
enmode = ENCOPYALL;
(void)ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode);/* OK if this fails */
#endif
/* set the backlog */
if (ioctl(p->fd, EIOCSETW, (caddr_t)&backlog) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s",
pcap_strerror(errno));
goto bad;
}
/* discover interface type */
if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCDEVP: %s",
pcap_strerror(errno));
goto bad;
}
/* HACK: to compile prior to Ultrix 4.2 */
#ifndef ENDT_FDDI
#define ENDT_FDDI 4
#endif
switch (devparams.end_dev_type) {
case ENDT_10MB:
p->linktype = DLT_EN10MB;
p->offset = 2;
break;
case ENDT_FDDI:
p->linktype = DLT_FDDI;
break;
#ifdef ENDT_SLIP
case ENDT_SLIP:
p->linktype = DLT_SLIP;
break;
#endif
#ifdef ENDT_PPP
case ENDT_PPP:
p->linktype = DLT_PPP;
break;
#endif
#ifdef ENDT_LOOPBACK
case ENDT_LOOPBACK:
/*
* It appears to use Ethernet framing, at least on
* Digital UNIX 4.0.
*/
p->linktype = DLT_EN10MB;
p->offset = 2;
break;
#endif
#ifdef ENDT_TRN
case ENDT_TRN:
p->linktype = DLT_IEEE802;
break;
#endif
default:
/*
* XXX - what about ENDT_IEEE802? The pfilt.h header
* file calls this "IEEE 802 networks (non-Ethernet)",
* but that doesn't specify a specific link layer type;
* it could be 802.4, or 802.5 (except that 802.5 is
* ENDT_TRN), or 802.6, or 802.11, or.... That's why
* DLT_IEEE802 was hijacked to mean Token Ring in various
* BSDs, and why we went along with that hijacking.
*
* XXX - what about ENDT_HDLC and ENDT_NULL?
* Presumably, as ENDT_OTHER is just "Miscellaneous
* framing", there's not much we can do, as that
* doesn't specify a particular type of header.
*/
snprintf(ebuf, PCAP_ERRBUF_SIZE, "unknown data-link type %u",
devparams.end_dev_type);
goto bad;
}
/* set truncation */
#ifdef PCAP_FDDIPAD
if (p->linktype == DLT_FDDI)
/* packetfilter includes the padding in the snapshot */
snaplen += pcap_fddipad;
#endif
if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&snaplen) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s",
pcap_strerror(errno));
goto bad;
}
p->snapshot = snaplen;
/* accept all packets */
memset(&Filter, 0, sizeof(Filter));
Filter.enf_Priority = 37; /* anything > 2 */
Filter.enf_FilterLen = 0; /* means "always true" */
if (ioctl(p->fd, EIOCSETF, (caddr_t)&Filter) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s",
pcap_strerror(errno));
goto bad;
}
if (to_ms != 0) {
struct timeval timeout;
timeout.tv_sec = to_ms / 1000;
timeout.tv_usec = (to_ms * 1000) % 1000000;
if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) {
snprintf(ebuf, PCAP_ERRBUF_SIZE, "EIOCSRTIMEOUT: %s",
pcap_strerror(errno));
goto bad;
}
}
p->bufsize = BUFSPACE;
p->buffer = (u_char*)malloc(p->bufsize + p->offset);
if (p->buffer == NULL) {
strlcpy(ebuf, pcap_strerror(errno), PCAP_ERRBUF_SIZE);
goto bad;
}
/*
* "select()" and "poll()" work on packetfilter devices.
*/
p->selectable_fd = p->fd;
p->read_op = pcap_read_pf;
p->setfilter_op = pcap_setfilter_pf;
p->set_datalink_op = NULL; /* can't change data link type */
p->getnonblock_op = pcap_getnonblock_fd;
p->setnonblock_op = pcap_setnonblock_fd;
p->stats_op = pcap_stats_pf;
p->close_op = pcap_close_pf;
return (p);
bad:
if (p->fd >= 0)
close(p->fd);
free(p);
return (NULL);
}
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;
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);
}