/*
* 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
*/
/*
* 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>
/*
* FDDI packets are padded to make everything line up on a nice boundary.
*/
#define PCAP_FDDIPAD 3
/*
* Private data for capturing on Ultrix and DEC OSF/1^WDigital UNIX^W^W
* Tru64 UNIX packetfilter devices.
*/
struct pcap_pf {
int filtering_in_kernel; /* using kernel filter */
u_long TotPkts; /* can't overflow for 79 hrs on ether */
u_long TotAccepted; /* count accepted by filter */
u_long TotDrops; /* count of dropped packets */
long TotMissed; /* missed by i/f during this run */
long OrigMissed; /* missed by i/f before this run */
};
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)
{
struct pcap_pf *pf = pc->priv;
register u_char *p, *bp;
register int cc, n, buflen, inc;
register struct enstamp *sp;
struct enstamp stamp;
register u_int pad;
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;
}
pcapint_fmt_errmsg_for_errno(pc->errbuf,
sizeof(pc->errbuf), errno, "pf read");
return (-1);
}
bp = (u_char *)pc->buffer + pc->offset;
} else
bp = pc->bp;
/*
* Loop through each packet.
*
* This assumes that a single buffer of packets will have
* <= INT_MAX packets, so the packet count doesn't overflow.
*/
n = 0;
pad = pc->fddipad;
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);
}
if ((long)bp & 3) {
sp = &stamp;
memcpy((char *)sp, (char *)bp, sizeof(*sp));
} else
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;
pf->TotPkts++;
pf->TotDrops += sp->ens_dropped;
pf->TotMissed = sp->ens_ifoverflows;
if (pf->OrigMissed < 0)
pf->OrigMissed = pf->TotMissed;
/*
* Short-circuit evaluation: if using BPF filter
* in kernel, no need to do it now - we already know
* the packet passed the filter.
*
* Note: the filter code was generated assuming
* that pc->fddipad was the amount of padding
* before the header, as that's what's required
* in the kernel, so we run the filter before
* skipping that padding.
*/
if (pf->filtering_in_kernel ||
pcapint_filter(pc->fcode.bf_insns, p, sp->ens_count, buflen)) {
struct pcap_pkthdr h;
pf->TotAccepted++;
h.ts = sp->ens_tstamp;
h.len = sp->ens_count - pad;
p += pad;
buflen -= pad;
h.caplen = buflen;
(*callback)(user, &h, p);
if (++n >= cnt && !PACKET_COUNT_IS_UNLIMITED(cnt)) {
pc->cc = cc;
pc->bp = bp;
return (n);
}
}
}
pc->cc = 0;
return (n);
}
static int
pcap_inject_pf(pcap_t *p, const void *buf, int size)
{
int ret;
ret = write(p->fd, buf, size);
if (ret == -1) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "send");
return (-1);
}
return (ret);
}
/*
* 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
* interface (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
* interface (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 = pf->TotAccepted;
ps->ps_drop = pf->TotDrops;
ps->ps_ifdrop = pf->TotMissed - pf->OrigMissed;
return (0);
}
/*
* We include the OS's <net/bpf.h>, not our "pcap/bpf.h", so we probably
* don't get DLT_DOCSIS defined.
*/
#ifndef DLT_DOCSIS
#define DLT_DOCSIS 143
#endif
static int
pcap_activate_pf(pcap_t *p)
{
struct pcap_pf *pf = p->priv;
short enmode;
int backlog = -1; /* request the most */
struct enfilter Filter;
struct endevp devparams;
int err;
/*
* Initially try a read/write open (to allow the inject
* method to work). If that fails due to permission
* issues, fall back to read-only. This allows a
* non-root user to be granted specific access to pcap
* capabilities via file permissions.
*
* XXX - we should have an API that has a flag that
* controls whether to open read-only or read-write,
* so that denial of permission to send (or inability
* to send, if sending packets isn't supported on
* the device in question) can be indicated at open
* time.
*
* 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.
*
* XXX - is there an error that means "no such device"? Is
* there one that means "that device doesn't support pf"?
*/
p->fd = pfopen(p->opt.device, O_RDWR);
if (p->fd == -1 && errno == EACCES)
p->fd = pfopen(p->opt.device, O_RDONLY);
if (p->fd < 0) {
if (errno == EACCES) {
snprintf(p->errbuf, PCAP_ERRBUF_SIZE,
"pf open: %s: Permission denied\n"
"your system may not be properly configured; see the packetfilter(4) man page",
p->opt.device);
err = PCAP_ERROR_PERM_DENIED;
} else {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "pf open: %s", p->opt.device);
err = PCAP_ERROR;
}
goto bad;
}
/*
* Turn a negative snapshot value (invalid), a snapshot value of
* 0 (unspecified), or a value bigger than the normal maximum
* value, into the maximum allowed value.
*
* If some application really *needs* a bigger snapshot
* length, we should just increase MAXIMUM_SNAPLEN.
*/
if (p->snapshot <= 0 || p->snapshot > MAXIMUM_SNAPLEN)
p->snapshot = MAXIMUM_SNAPLEN;
pf->OrigMissed = -1;
enmode = ENTSTAMP|ENNONEXCL;
if (!p->opt.immediate)
enmode |= ENBATCH;
if (p->opt.promisc)
enmode |= ENPROMISC;
if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "EIOCMBIS");
err = PCAP_ERROR;
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) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "EIOCSETW");
err = PCAP_ERROR;
goto bad;
}
/* discover interface type */
if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "EIOCDEVP");
err = PCAP_ERROR;
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;
/*
* This is (presumably) a real Ethernet capture; give it a
* link-layer-type list with DLT_EN10MB and DLT_DOCSIS, so
* that an application can let you choose it, in case you're
* capturing DOCSIS traffic that a Cisco Cable Modem
* Termination System is putting out onto an Ethernet (it
* doesn't put an Ethernet header onto the wire, it puts raw
* DOCSIS frames out on the wire inside the low-level
* Ethernet framing).
*/
p->dlt_list = (u_int *) malloc(sizeof(u_int) * 2);
if (p->dlt_list == NULL) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "malloc");
err = PCAP_ERROR;
goto bad;
}
p->dlt_list[0] = DLT_EN10MB;
p->dlt_list[1] = DLT_DOCSIS;
p->dlt_count = 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(p->errbuf, PCAP_ERRBUF_SIZE,
"unknown data-link type %u", devparams.end_dev_type);
err = PCAP_ERROR;
goto bad;
}
/* set truncation */
if (p->linktype == DLT_FDDI) {
p->fddipad = PCAP_FDDIPAD;
/* packetfilter includes the padding in the snapshot */
p->snapshot += PCAP_FDDIPAD;
} else
p->fddipad = 0;
if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&p->snapshot) < 0) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "EIOCTRUNCATE");
err = PCAP_ERROR;
goto bad;
}
/* 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) {
pcapint_fmt_errmsg_for_errno(p->errbuf, PCAP_ERRBUF_SIZE,
errno, "EIOCSETF");
err = PCAP_ERROR;
goto bad;
}
p = PCAP_CREATE_COMMON(ebuf, struct pcap_pf);
if (p == NULL)
return (NULL);
p->activate_op = pcap_activate_pf;
return (p);
}
/*
* XXX - is there an error from pfopen() that means "no such device"?
* Is there one that means "that device doesn't support pf"?
*/
static int
can_be_bound(const char *name _U_)
{
return (1);
}
static int
get_if_flags(const char *name _U_, bpf_u_int32 *flags _U_, char *errbuf _U_)
{
/*
* Nothing we can do other than mark loopback devices as "the
* connected/disconnected status doesn't apply".
*
* XXX - is there a way to find out whether an adapter has
* something plugged into it?
*/
if (*flags & PCAP_IF_LOOPBACK) {
/*
* Loopback devices aren't wireless, and "connected"/
* "disconnected" doesn't apply to them.
*/
*flags |= PCAP_IF_CONNECTION_STATUS_NOT_APPLICABLE;
return (0);
}
return (0);
}
/*
* 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 packetfilter(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) {
pcapint_fmt_errmsg_for_errno(p->errbuf,
sizeof(p->errbuf), errno, "BIOCSETF");
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");
pf->filtering_in_kernel = 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 (pcapint_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");
pf->filtering_in_kernel = 0;
return (0);
}
