diff options
Diffstat (limited to 'pcap-pf.c')
| -rw-r--r-- | pcap-pf.c | 604 |
1 files changed, 604 insertions, 0 deletions
diff --git a/pcap-pf.c b/pcap-pf.c new file mode 100644 index 0000000..d8326df --- /dev/null +++ b/pcap-pf.c @@ -0,0 +1,604 @@ +/* + * 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 1.97 2008-04-14 20:40:58 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; + register int cc, n, buflen, inc; + register struct enstamp *sp; +#ifdef LBL_ALIGN + struct enstamp stamp; +#endif +#ifdef PCAP_FDDIPAD + register int pad; +#endif + + 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 + pad = pc->fddipad; +#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; + 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 - we already know + * the packet passed the filter. + * +#ifdef PCAP_FDDIPAD + * 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. +#endif + */ + if (pc->md.use_bpf || + bpf_filter(pc->fcode.bf_insns, 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 +#ifdef PCAP_FDDIPAD + p += pad; + buflen -= pad; +#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_inject_pf(pcap_t *p, const void *buf, size_t size) +{ + int ret; + + ret = write(p->fd, buf, size); + if (ret == -1) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "send: %s", + pcap_strerror(errno)); + return (-1); + } + return (ret); +} + +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); +} + +/* + * 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) +{ + short enmode; + int backlog = -1; /* request the most */ + struct enfilter Filter; + struct endevp devparams; + + /* + * 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. + */ + p->fd = pfopen(p->opt.source, O_RDWR); + if (p->fd == -1 && errno == EACCES) + p->fd = pfopen(p->opt.source, O_RDONLY); + if (p->fd < 0) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "pf open: %s: %s\n\ +your system may not be properly configured; see the packetfilter(4) man page\n", + p->opt.source, pcap_strerror(errno)); + goto bad; + } + p->md.OrigMissed = -1; + enmode = ENTSTAMP|ENBATCH|ENNONEXCL; + if (p->opt.promisc) + enmode |= ENPROMISC; + if (ioctl(p->fd, EIOCMBIS, (caddr_t)&enmode) < 0) { + snprintf(p->errbuf, 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(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETW: %s", + pcap_strerror(errno)); + goto bad; + } + /* discover interface type */ + if (ioctl(p->fd, EIOCDEVP, (caddr_t)&devparams) < 0) { + snprintf(p->errbuf, 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; + /* + * 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 that fails, just leave the list empty. + */ + if (p->dlt_list != NULL) { + 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); + goto bad; + } + /* set truncation */ +#ifdef PCAP_FDDIPAD + if (p->linktype == DLT_FDDI) { + p->fddipad = PCAP_FDDIPAD; + + /* packetfilter includes the padding in the snapshot */ + p->snapshot += PCAP_FDDIPAD; + } else + p->fddipad = 0; +#endif + if (ioctl(p->fd, EIOCTRUNCATE, (caddr_t)&p->snapshot) < 0) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCTRUNCATE: %s", + pcap_strerror(errno)); + 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) { + snprintf(p->errbuf, PCAP_ERRBUF_SIZE, "EIOCSETF: %s", + pcap_strerror(errno)); + goto bad; + } + + if (p->md.timeout != 0) { + struct timeval timeout; + timeout.tv_sec = p->md.timeout / 1000; + timeout.tv_usec = (p->md.timeout * 1000) % 1000000; + if (ioctl(p->fd, EIOCSRTIMEOUT, (caddr_t)&timeout) < 0) { + snprintf(p->errbuf, 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(p->errbuf, 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->inject_op = pcap_inject_pf; + p->setfilter_op = pcap_setfilter_pf; + p->setdirection_op = NULL; /* Not implemented. */ + 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; + + return (0); + bad: + pcap_cleanup_live_common(p); + return (PCAP_ERROR); +} + +pcap_t * +pcap_create(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); +} |