OpenBSD-4.6/sbin/pflogd/pflogd.c
/* $OpenBSD: pflogd.c,v 1.46 2008/10/22 08:16:49 henning Exp $ */
/*
* Copyright (c) 2001 Theo de Raadt
* Copyright (c) 2001 Can Erkin Acar
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
*
* - Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* - 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.
*
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS 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
* COPYRIGHT HOLDERS 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.
*/
#include <sys/types.h>
#include <sys/ioctl.h>
#include <sys/file.h>
#include <sys/stat.h>
#include <sys/socket.h>
#include <net/if.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <pcap-int.h>
#include <pcap.h>
#include <syslog.h>
#include <signal.h>
#include <err.h>
#include <errno.h>
#include <stdarg.h>
#include <fcntl.h>
#include <util.h>
#include "pflogd.h"
pcap_t *hpcap;
static FILE *dpcap;
int Debug = 0;
static int snaplen = DEF_SNAPLEN;
static int cur_snaplen = DEF_SNAPLEN;
volatile sig_atomic_t gotsig_close, gotsig_alrm, gotsig_hup, gotsig_usr1;
char *filename = PFLOGD_LOG_FILE;
char *interface = PFLOGD_DEFAULT_IF;
char *filter = NULL;
char errbuf[PCAP_ERRBUF_SIZE];
int log_debug = 0;
unsigned int delay = FLUSH_DELAY;
char *copy_argv(char * const *);
void dump_packet(u_char *, const struct pcap_pkthdr *, const u_char *);
void dump_packet_nobuf(u_char *, const struct pcap_pkthdr *, const u_char *);
void log_pcap_stats(void);
int flush_buffer(FILE *);
int if_exists(char *);
int init_pcap(void);
void logmsg(int, const char *, ...);
void purge_buffer(void);
int reset_dump(int);
int scan_dump(FILE *, off_t);
int set_snaplen(int);
void set_suspended(int);
void sig_alrm(int);
void sig_usr1(int);
void sig_close(int);
void sig_hup(int);
void usage(void);
static int try_reset_dump(int);
/* buffer must always be greater than snaplen */
static int bufpkt = 0; /* number of packets in buffer */
static int buflen = 0; /* allocated size of buffer */
static char *buffer = NULL; /* packet buffer */
static char *bufpos = NULL; /* position in buffer */
static int bufleft = 0; /* bytes left in buffer */
/* if error, stop logging but count dropped packets */
static int suspended = -1;
static long packets_dropped = 0;
void
set_suspended(int s)
{
if (suspended == s)
return;
suspended = s;
setproctitle("[%s] -s %d -i %s -f %s",
suspended ? "suspended" : "running",
cur_snaplen, interface, filename);
}
char *
copy_argv(char * const *argv)
{
size_t len = 0, n;
char *buf;
if (argv == NULL)
return (NULL);
for (n = 0; argv[n]; n++)
len += strlen(argv[n])+1;
if (len == 0)
return (NULL);
buf = malloc(len);
if (buf == NULL)
return (NULL);
strlcpy(buf, argv[0], len);
for (n = 1; argv[n]; n++) {
strlcat(buf, " ", len);
strlcat(buf, argv[n], len);
}
return (buf);
}
void
logmsg(int pri, const char *message, ...)
{
va_list ap;
va_start(ap, message);
if (log_debug) {
vfprintf(stderr, message, ap);
fprintf(stderr, "\n");
} else
vsyslog(pri, message, ap);
va_end(ap);
}
__dead void
usage(void)
{
fprintf(stderr, "usage: pflogd [-Dx] [-d delay] [-f filename]");
fprintf(stderr, " [-i interface] [-p pidfile]\n");
fprintf(stderr, " [-s snaplen] [expression]\n");
exit(1);
}
void
sig_close(int sig)
{
gotsig_close = 1;
}
void
sig_hup(int sig)
{
gotsig_hup = 1;
}
void
sig_alrm(int sig)
{
gotsig_alrm = 1;
}
void
sig_usr1(int sig)
{
gotsig_usr1 = 1;
}
void
set_pcap_filter(void)
{
struct bpf_program bprog;
if (pcap_compile(hpcap, &bprog, filter, PCAP_OPT_FIL, 0) < 0)
logmsg(LOG_WARNING, "%s", pcap_geterr(hpcap));
else {
if (pcap_setfilter(hpcap, &bprog) < 0)
logmsg(LOG_WARNING, "%s", pcap_geterr(hpcap));
pcap_freecode(&bprog);
}
}
int
if_exists(char *ifname)
{
int s;
struct ifreq ifr;
struct if_data ifrdat;
if ((s = socket(AF_INET, SOCK_DGRAM, 0)) == -1)
err(1, "socket");
bzero(&ifr, sizeof(ifr));
if (strlcpy(ifr.ifr_name, ifname, sizeof(ifr.ifr_name)) >=
sizeof(ifr.ifr_name))
errx(1, "main ifr_name: strlcpy");
ifr.ifr_data = (caddr_t)&ifrdat;
if (ioctl(s, SIOCGIFDATA, (caddr_t)&ifr) == -1)
return (0);
if (close(s))
err(1, "close");
return (1);
}
int
init_pcap(void)
{
hpcap = pcap_open_live(interface, snaplen, 1, PCAP_TO_MS, errbuf);
if (hpcap == NULL) {
logmsg(LOG_ERR, "Failed to initialize: %s", errbuf);
return (-1);
}
if (pcap_datalink(hpcap) != DLT_PFLOG) {
logmsg(LOG_ERR, "Invalid datalink type");
pcap_close(hpcap);
hpcap = NULL;
return (-1);
}
set_pcap_filter();
cur_snaplen = snaplen = pcap_snapshot(hpcap);
/* lock */
if (ioctl(pcap_fileno(hpcap), BIOCLOCK) < 0) {
logmsg(LOG_ERR, "BIOCLOCK: %s", strerror(errno));
return (-1);
}
return (0);
}
int
set_snaplen(int snap)
{
if (priv_set_snaplen(snap))
return (1);
if (cur_snaplen > snap)
purge_buffer();
cur_snaplen = snap;
return (0);
}
int
reset_dump(int nomove)
{
int ret;
for (;;) {
ret = try_reset_dump(nomove);
if (ret <= 0)
break;
}
return (ret);
}
/*
* tries to (re)open log file, nomove flag is used with -x switch
* returns 0: success, 1: retry (log moved), -1: error
*/
int
try_reset_dump(int nomove)
{
struct pcap_file_header hdr;
struct stat st;
int fd;
FILE *fp;
if (hpcap == NULL)
return (-1);
if (dpcap) {
flush_buffer(dpcap);
fclose(dpcap);
dpcap = NULL;
}
/*
* Basically reimplement pcap_dump_open() because it truncates
* files and duplicates headers and such.
*/
fd = priv_open_log();
if (fd < 0)
return (-1);
fp = fdopen(fd, "a+");
if (fp == NULL) {
logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
close(fd);
return (-1);
}
if (fstat(fileno(fp), &st) == -1) {
logmsg(LOG_ERR, "Error: %s: %s", filename, strerror(errno));
fclose(fp);
return (-1);
}
/* set FILE unbuffered, we do our own buffering */
if (setvbuf(fp, NULL, _IONBF, 0)) {
logmsg(LOG_ERR, "Failed to set output buffers");
fclose(fp);
return (-1);
}
#define TCPDUMP_MAGIC 0xa1b2c3d4
if (st.st_size == 0) {
if (snaplen != cur_snaplen) {
logmsg(LOG_NOTICE, "Using snaplen %d", snaplen);
if (set_snaplen(snaplen))
logmsg(LOG_WARNING,
"Failed, using old settings");
}
hdr.magic = TCPDUMP_MAGIC;
hdr.version_major = PCAP_VERSION_MAJOR;
hdr.version_minor = PCAP_VERSION_MINOR;
hdr.thiszone = hpcap->tzoff;
hdr.snaplen = hpcap->snapshot;
hdr.sigfigs = 0;
hdr.linktype = hpcap->linktype;
if (fwrite((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
fclose(fp);
return (-1);
}
} else if (scan_dump(fp, st.st_size)) {
fclose(fp);
if (nomove || priv_move_log()) {
logmsg(LOG_ERR,
"Invalid/incompatible log file, move it away");
return (-1);
}
return (1);
}
dpcap = fp;
set_suspended(0);
flush_buffer(fp);
return (0);
}
int
scan_dump(FILE *fp, off_t size)
{
struct pcap_file_header hdr;
struct pcap_pkthdr ph;
off_t pos;
/*
* Must read the file, compare the header against our new
* options (in particular, snaplen) and adjust our options so
* that we generate a correct file. Furthermore, check the file
* for consistency so that we can append safely.
*
* XXX this may take a long time for large logs.
*/
(void) fseek(fp, 0L, SEEK_SET);
if (fread((char *)&hdr, sizeof(hdr), 1, fp) != 1) {
logmsg(LOG_ERR, "Short file header");
return (1);
}
if (hdr.magic != TCPDUMP_MAGIC ||
hdr.version_major != PCAP_VERSION_MAJOR ||
hdr.version_minor != PCAP_VERSION_MINOR ||
hdr.linktype != hpcap->linktype ||
hdr.snaplen > PFLOGD_MAXSNAPLEN) {
return (1);
}
pos = sizeof(hdr);
while (!feof(fp)) {
off_t len = fread((char *)&ph, 1, sizeof(ph), fp);
if (len == 0)
break;
if (len != sizeof(ph))
goto error;
if (ph.caplen > hdr.snaplen || ph.caplen > PFLOGD_MAXSNAPLEN)
goto error;
pos += sizeof(ph) + ph.caplen;
if (pos > size)
goto error;
fseek(fp, ph.caplen, SEEK_CUR);
}
if (pos != size)
goto error;
if (hdr.snaplen != cur_snaplen) {
logmsg(LOG_WARNING,
"Existing file has different snaplen %u, using it",
hdr.snaplen);
if (set_snaplen(hdr.snaplen)) {
logmsg(LOG_WARNING,
"Failed, using old settings, offset %llu",
(unsigned long long) size);
}
}
return (0);
error:
logmsg(LOG_ERR, "Corrupted log file.");
return (1);
}
/* dump a packet directly to the stream, which is unbuffered */
void
dump_packet_nobuf(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
FILE *f = (FILE *)user;
if (suspended) {
packets_dropped++;
return;
}
if (fwrite((char *)h, sizeof(*h), 1, f) != 1) {
off_t pos = ftello(f);
/* try to undo header to prevent corruption */
if (pos < sizeof(*h) ||
ftruncate(fileno(f), pos - sizeof(*h))) {
logmsg(LOG_ERR, "Write failed, corrupted logfile!");
set_suspended(1);
gotsig_close = 1;
return;
}
goto error;
}
if (fwrite((char *)sp, h->caplen, 1, f) != 1)
goto error;
return;
error:
set_suspended(1);
packets_dropped ++;
logmsg(LOG_ERR, "Logging suspended: fwrite: %s", strerror(errno));
}
int
flush_buffer(FILE *f)
{
off_t offset;
int len = bufpos - buffer;
if (len <= 0)
return (0);
offset = ftello(f);
if (offset == (off_t)-1) {
set_suspended(1);
logmsg(LOG_ERR, "Logging suspended: ftello: %s",
strerror(errno));
return (1);
}
if (fwrite(buffer, len, 1, f) != 1) {
set_suspended(1);
logmsg(LOG_ERR, "Logging suspended: fwrite: %s",
strerror(errno));
ftruncate(fileno(f), offset);
return (1);
}
set_suspended(0);
bufpos = buffer;
bufleft = buflen;
bufpkt = 0;
return (0);
}
void
purge_buffer(void)
{
packets_dropped += bufpkt;
set_suspended(0);
bufpos = buffer;
bufleft = buflen;
bufpkt = 0;
}
/* append packet to the buffer, flushing if necessary */
void
dump_packet(u_char *user, const struct pcap_pkthdr *h, const u_char *sp)
{
FILE *f = (FILE *)user;
size_t len = sizeof(*h) + h->caplen;
if (len < sizeof(*h) || h->caplen > (size_t)cur_snaplen) {
logmsg(LOG_NOTICE, "invalid size %u (%u/%u), packet dropped",
len, cur_snaplen, snaplen);
packets_dropped++;
return;
}
if (len <= bufleft)
goto append;
if (suspended) {
packets_dropped++;
return;
}
if (flush_buffer(f)) {
packets_dropped++;
return;
}
if (len > bufleft) {
dump_packet_nobuf(user, h, sp);
return;
}
append:
memcpy(bufpos, h, sizeof(*h));
memcpy(bufpos + sizeof(*h), sp, h->caplen);
bufpos += len;
bufleft -= len;
bufpkt++;
return;
}
void
log_pcap_stats(void)
{
struct pcap_stat pstat;
if (pcap_stats(hpcap, &pstat) < 0)
logmsg(LOG_WARNING, "Reading stats: %s", pcap_geterr(hpcap));
else
logmsg(LOG_NOTICE,
"%u packets received, %u/%u dropped (kernel/pflogd)",
pstat.ps_recv, pstat.ps_drop, packets_dropped);
}
int
main(int argc, char **argv)
{
int ch, np, ret, Xflag = 0;
pcap_handler phandler = dump_packet;
const char *errstr = NULL;
char *pidf = NULL;
ret = 0;
closefrom(STDERR_FILENO + 1);
while ((ch = getopt(argc, argv, "Dxd:f:i:p:s:")) != -1) {
switch (ch) {
case 'D':
Debug = 1;
break;
case 'd':
delay = strtonum(optarg, 5, 60*60, &errstr);
if (errstr)
usage();
break;
case 'f':
filename = optarg;
break;
case 'i':
interface = optarg;
break;
case 'p':
pidf = optarg;
break;
case 's':
snaplen = strtonum(optarg, 0, PFLOGD_MAXSNAPLEN,
&errstr);
if (snaplen <= 0)
snaplen = DEF_SNAPLEN;
if (errstr)
snaplen = PFLOGD_MAXSNAPLEN;
break;
case 'x':
Xflag++;
break;
default:
usage();
}
}
log_debug = Debug;
argc -= optind;
argv += optind;
/* does interface exist */
if (!if_exists(interface)) {
warn("Failed to initialize: %s", interface);
logmsg(LOG_ERR, "Failed to initialize: %s", interface);
logmsg(LOG_ERR, "Exiting, init failure");
exit(1);
}
if (!Debug) {
openlog("pflogd", LOG_PID | LOG_CONS, LOG_DAEMON);
if (daemon(0, 0)) {
logmsg(LOG_WARNING, "Failed to become daemon: %s",
strerror(errno));
}
pidfile(pidf);
}
tzset();
(void)umask(S_IRWXG | S_IRWXO);
/* filter will be used by the privileged process */
if (argc) {
filter = copy_argv(argv);
if (filter == NULL)
logmsg(LOG_NOTICE, "Failed to form filter expression");
}
/* initialize pcap before dropping privileges */
if (init_pcap()) {
logmsg(LOG_ERR, "Exiting, init failure");
exit(1);
}
/* Privilege separation begins here */
if (priv_init()) {
logmsg(LOG_ERR, "unable to privsep");
exit(1);
}
setproctitle("[initializing]");
/* Process is now unprivileged and inside a chroot */
signal(SIGTERM, sig_close);
signal(SIGINT, sig_close);
signal(SIGQUIT, sig_close);
signal(SIGALRM, sig_alrm);
signal(SIGUSR1, sig_usr1);
signal(SIGHUP, sig_hup);
alarm(delay);
buffer = malloc(PFLOGD_BUFSIZE);
if (buffer == NULL) {
logmsg(LOG_WARNING, "Failed to allocate output buffer");
phandler = dump_packet_nobuf;
} else {
bufleft = buflen = PFLOGD_BUFSIZE;
bufpos = buffer;
bufpkt = 0;
}
if (reset_dump(Xflag) < 0) {
if (Xflag)
return (1);
logmsg(LOG_ERR, "Logging suspended: open error");
set_suspended(1);
} else if (Xflag)
return (0);
while (1) {
np = pcap_dispatch(hpcap, PCAP_NUM_PKTS,
phandler, (u_char *)dpcap);
if (np < 0) {
if (!if_exists(interface) == -1) {
logmsg(LOG_NOTICE, "interface %s went away",
interface);
ret = -1;
break;
}
logmsg(LOG_NOTICE, "%s", pcap_geterr(hpcap));
}
if (gotsig_close)
break;
if (gotsig_hup) {
if (reset_dump(0)) {
logmsg(LOG_ERR,
"Logging suspended: open error");
set_suspended(1);
}
gotsig_hup = 0;
}
if (gotsig_alrm) {
if (dpcap)
flush_buffer(dpcap);
else
gotsig_hup = 1;
gotsig_alrm = 0;
alarm(delay);
}
if (gotsig_usr1) {
log_pcap_stats();
gotsig_usr1 = 0;
}
}
logmsg(LOG_NOTICE, "Exiting");
if (dpcap) {
flush_buffer(dpcap);
fclose(dpcap);
}
purge_buffer();
log_pcap_stats();
pcap_close(hpcap);
if (!Debug)
closelog();
return (ret);
}