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487 lines (429 loc) · 13.6 KB
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/* $OpenBSD: pf_osfp.c,v 1.3 2003/08/27 18:23:36 frantzen Exp $ */
/*
* Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
*
* Permission to use, copy, modify, and distribute this software for any
* purpose with or without fee is hereby granted, provided that the above
* copyright notice and this permission notice appear in all copies.
*
* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
*
*/
#include <sys/param.h>
#include <sys/types.h>
#ifdef HAVE_CONFIG_H
#include "config.h"
#endif
#include <dnet.h>
#include "pfvar.h"
# include <arpa/inet.h>
# include <errno.h>
# include <stdio.h>
# include <stdlib.h>
# include <string.h>
#ifndef NTOHS
#define NTOHS(x) (x) = ntohs((u_int16_t)(x))
#endif
# define pool_t int
# define pool_get(pool, flags) malloc(*(pool))
# define pool_put(pool, item) free(item)
# define pool_init(pool, size, a, ao, f, m, p) (*(pool)) = (size)
# ifdef PFDEBUG
# include <stdarg.h>
# define DPFPRINTF(format, x...) fprintf(stderr, format , ##x)
# else
# define DPFPRINTF(format, x...) ((void)0)
# endif /* PFDEBUG */
SLIST_HEAD(pf_osfp_list, pf_os_fingerprint) pf_osfp_list;
pool_t pf_osfp_entry_pl;
pool_t pf_osfp_pl;
struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
struct pf_os_fingerprint *, u_int8_t);
struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
struct pf_os_fingerprint *);
void pf_osfp_insert(struct pf_osfp_list *,
struct pf_os_fingerprint *);
#define TCP_OLEN_MSS 4
#define TCP_OLEN_TIMESTAMP 10
struct pf_osfp_enlist *
pf_osfp_fingerprint_hdr(const struct ip_hdr *ip, const struct tcp_hdr *tcp)
{
struct pf_os_fingerprint fp, *fpresult;
int cnt, optlen = 0;
u_int8_t *optp;
if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN || (ip->ip_off &
htons(IP_OFFMASK)))
return (NULL);
memset(&fp, 0, sizeof(fp));
fp.fp_psize = ntohs(ip->ip_len);
fp.fp_ttl = ip->ip_ttl;
if (ip->ip_off & htons(IP_DF))
fp.fp_flags |= PF_OSFP_DF;
fp.fp_wsize = ntohs(tcp->th_win);
cnt = (tcp->th_off << 2) - sizeof(*tcp);
optp = (void*)tcp + sizeof(*tcp);
for (; cnt > 0; cnt -= optlen, optp += optlen) {
if (*optp == TCP_OPT_EOL)
break;
fp.fp_optcnt++;
if (*optp == TCP_OPT_NOP) {
fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
PF_OSFP_TCPOPT_NOP;
optlen = 1;
} else {
if (cnt < 2)
return (NULL);
optlen = optp[1];
if (optlen > cnt || optlen < 2)
return (NULL);
switch (*optp) {
case TCP_OPT_MSS:
if (optlen >= TCP_OLEN_MSS)
memcpy(&fp.fp_mss, &optp[2],
sizeof(fp.fp_mss));
fp.fp_tcpopts = (fp.fp_tcpopts <<
PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
NTOHS(fp.fp_mss);
break;
case TCP_OPT_WSCALE:
if (optlen > TCP_OPT_LEN)
memcpy(&fp.fp_wscale, &optp[2],
sizeof(fp.fp_wscale));
NTOHS(fp.fp_wscale);
fp.fp_tcpopts = (fp.fp_tcpopts <<
PF_OSFP_TCPOPT_BITS) |
PF_OSFP_TCPOPT_WSCALE;
break;
case TCP_OPT_SACKOK:
fp.fp_tcpopts = (fp.fp_tcpopts <<
PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
break;
case TCP_OPT_TIMESTAMP:
if (optlen >= TCP_OLEN_TIMESTAMP) {
u_int32_t ts;
memcpy(&ts, &optp[2], sizeof(ts));
if (ts == 0)
fp.fp_flags |= PF_OSFP_TS0;
}
fp.fp_tcpopts = (fp.fp_tcpopts <<
PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
break;
default:
return (NULL);
}
}
optlen = MAX(optlen, 1); /* paranoia */
}
DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
"(TS=%s,M=%s%d,W=%s%d)\n",
inet_ntoa(ip->ip_src), ntohs(tcp->th_sport),
fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
(fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
(fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
(fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
fp.fp_mss,
(fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
(fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
fp.fp_wscale);
if ((fpresult = pf_osfp_find(&pf_osfp_list, &fp,
PF_OSFP_MAXTTL_OFFSET)))
return (&fpresult->fp_oses);
return (NULL);
}
/* Match a fingerprint ID against a list of OSes */
int
pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
{
struct pf_osfp_entry *entry;
int os_class, os_version, os_subtype;
int en_class, en_version, en_subtype;
if (os == PF_OSFP_ANY)
return (1);
if (list == NULL) {
DPFPRINTF("osfp no match against %x\n", os);
return (os == PF_OSFP_UNKNOWN);
}
PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
SLIST_FOREACH(entry, list, fp_entry) {
PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
(os_version == PF_OSFP_ANY || en_version == os_version) &&
(os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
DPFPRINTF("osfp matched %s %s %s %x==%x\n",
entry->fp_class_nm, entry->fp_version_nm,
entry->fp_subtype_nm, os, entry->fp_os);
return (1);
}
}
DPFPRINTF("fingerprint 0x%x didn't match\n", os);
return (0);
}
/* Initialize the OS fingerprint system */
void
pf_osfp_initialize(void)
{
pool_init(&pf_osfp_entry_pl, sizeof(struct pf_osfp_entry), 0, 0, 0,
"pfosfpen", NULL);
pool_init(&pf_osfp_pl, sizeof(struct pf_os_fingerprint), 0, 0, 0,
"pfosfp", NULL);
SLIST_INIT(&pf_osfp_list);
}
/* Flush the fingerprint list */
void
pf_osfp_flush(void)
{
struct pf_os_fingerprint *fp;
struct pf_osfp_entry *entry;
while ((fp = SLIST_FIRST(&pf_osfp_list))) {
SLIST_REMOVE_HEAD(&pf_osfp_list, fp_next);
while ((entry = SLIST_FIRST(&fp->fp_oses))) {
SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
pool_put(&pf_osfp_entry_pl, entry);
}
pool_put(&pf_osfp_pl, fp);
}
}
/* Add a fingerprint */
int
pf_osfp_add(struct pf_osfp_ioctl *fpioc)
{
struct pf_os_fingerprint *fp, fpadd;
struct pf_osfp_entry *entry;
memset(&fpadd, 0, sizeof(fpadd));
fpadd.fp_tcpopts = fpioc->fp_tcpopts;
fpadd.fp_wsize = fpioc->fp_wsize;
fpadd.fp_psize = fpioc->fp_psize;
fpadd.fp_mss = fpioc->fp_mss;
fpadd.fp_flags = fpioc->fp_flags;
fpadd.fp_optcnt = fpioc->fp_optcnt;
fpadd.fp_wscale = fpioc->fp_wscale;
fpadd.fp_ttl = fpioc->fp_ttl;
DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
"(TS=%s,M=%s%d,W=%s%d) %x\n",
fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
fpioc->fp_os.fp_subtype_nm,
(fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
(fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
(fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
(fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
fpadd.fp_wsize,
fpadd.fp_ttl,
(fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
(fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
(fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
fpadd.fp_psize,
(long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
(fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
(fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
(fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
fpadd.fp_mss,
(fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
(fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
fpadd.fp_wscale,
fpioc->fp_os.fp_os);
if ((fp = pf_osfp_find_exact(&pf_osfp_list, &fpadd))) {
SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
return (EEXIST);
}
if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL)
return (ENOMEM);
} else {
if ((fp = pool_get(&pf_osfp_pl, PR_NOWAIT)) == NULL)
return (ENOMEM);
memset(fp, 0, sizeof(*fp));
fp->fp_tcpopts = fpioc->fp_tcpopts;
fp->fp_wsize = fpioc->fp_wsize;
fp->fp_psize = fpioc->fp_psize;
fp->fp_mss = fpioc->fp_mss;
fp->fp_flags = fpioc->fp_flags;
fp->fp_optcnt = fpioc->fp_optcnt;
fp->fp_wscale = fpioc->fp_wscale;
fp->fp_ttl = fpioc->fp_ttl;
SLIST_INIT(&fp->fp_oses);
if ((entry = pool_get(&pf_osfp_entry_pl, PR_NOWAIT)) == NULL) {
pool_put(&pf_osfp_pl, fp);
return (ENOMEM);
}
pf_osfp_insert(&pf_osfp_list, fp);
}
memcpy(entry, &fpioc->fp_os, sizeof(*entry));
/* Make sure the strings are NUL terminated */
entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
#ifdef PFDEBUG
if ((fp = pf_osfp_validate()))
printf("Invalid fingerprint list\n");
#endif /* PFDEBUG */
return (0);
}
/* Find a fingerprint in the list */
struct pf_os_fingerprint *
pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
u_int8_t ttldiff)
{
struct pf_os_fingerprint *f;
#define MATCH_INT(_MOD, _DC, _field) \
if ((f->fp_flags & _DC) == 0) { \
if ((f->fp_flags & _MOD) == 0) { \
if (f->_field != find->_field) \
continue; \
} else { \
if (f->_field == 0 || find->_field % f->_field) \
continue; \
} \
}
SLIST_FOREACH(f, list, fp_next) {
if (f->fp_tcpopts != find->fp_tcpopts ||
f->fp_optcnt != find->fp_optcnt ||
f->fp_ttl < find->fp_ttl ||
f->fp_ttl - find->fp_ttl > ttldiff ||
(f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
(find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
continue;
MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
if (find->fp_mss == 0)
continue;
/* Some "smart" NAT devices and DSL routers will tweak the MSS size and
* will set it to whatever is suitable for the link type.
*/
#define SMART_MSS 1460
if ((find->fp_wsize % find->fp_mss ||
find->fp_wsize / find->fp_mss !=
f->fp_wsize) &&
(find->fp_wsize % SMART_MSS ||
find->fp_wsize / SMART_MSS !=
f->fp_wsize))
continue;
} else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
if (find->fp_mss == 0)
continue;
#define MTUOFF (sizeof(struct ip_hdr) + sizeof(struct tcp_hdr))
#define SMART_MTU (SMART_MSS + MTUOFF)
if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
find->fp_wsize / (find->fp_mss + MTUOFF) !=
f->fp_wsize) &&
(find->fp_wsize % SMART_MTU ||
find->fp_wsize / SMART_MTU !=
f->fp_wsize))
continue;
} else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
if (f->fp_wsize == 0 || find->fp_wsize %
f->fp_wsize)
continue;
} else {
if (f->fp_wsize != find->fp_wsize)
continue;
}
}
return (f);
}
return (NULL);
}
/* Find an exact fingerprint in the list */
struct pf_os_fingerprint *
pf_osfp_find_exact(struct pf_
8000
osfp_list *list, struct pf_os_fingerprint *find)
{
struct pf_os_fingerprint *f;
SLIST_FOREACH(f, list, fp_next) {
if (f->fp_tcpopts == find->fp_tcpopts &&
f->fp_wsize == find->fp_wsize &&
f->fp_psize == find->fp_psize &&
f->fp_mss == find->fp_mss &&
f->fp_flags == find->fp_flags &&
f->fp_optcnt == find->fp_optcnt &&
f->fp_wscale == find->fp_wscale &&
f->fp_ttl == find->fp_ttl)
return (f);
}
return (NULL);
}
/* Insert a fingerprint into the list */
void
pf_osfp_insert(struct pf_osfp_list *list, struct pf_os_fingerprint *ins)
{
struct pf_os_fingerprint *f, *prev = NULL;
/* XXX need to go semi tree based. can key on tcp options */
SLIST_FOREACH(f, list, fp_next)
prev = f;
if (prev)
SLIST_INSERT_AFTER(prev, ins, fp_next);
else
SLIST_INSERT_HEAD(list, ins, fp_next);
}
/* Fill a fingerprint by its number (from an ioctl) */
int
pf_osfp_get(struct pf_osfp_ioctl *fpioc)
{
struct pf_os_fingerprint *fp;
struct pf_osfp_entry *entry;
int num = fpioc->fp_getnum;
int i = 0;
memset(fpioc, 0, sizeof(*fpioc));
SLIST_FOREACH(fp, &pf_osfp_list, fp_next) {
SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
if (i++ == num) {
fpioc->fp_mss = fp->fp_mss;
fpioc->fp_wsize = fp->fp_wsize;
fpioc->fp_flags = fp->fp_flags;
fpioc->fp_psize = fp->fp_psize;
fpioc->fp_ttl = fp->fp_ttl;
fpioc->fp_wscale = fp->fp_wscale;
fpioc->fp_getnum = num;
memcpy(&fpioc->fp_os, entry,
sizeof(fpioc->fp_os));
return (0);
}
}
}
return (EBUSY);
}
/* Validate that each signature is reachable */
struct pf_os_fingerprint *
pf_osfp_validate(void)
{
struct pf_os_fingerprint *f, *f2, find;
SLIST_FOREACH(f, &pf_osfp_list, fp_next) {
memcpy(&find, f, sizeof(find));
/* We do a few MSS/th_win percolations to make things unique */
if (find.fp_mss == 0)
find.fp_mss = 128;
if (f->fp_flags & PF_OSFP_WSIZE_MSS)
find.fp_wsize *= find.fp_mss, 1;
else if (f->fp_flags & PF_OSFP_WSIZE_MTU)
find.fp_wsize *= (find.fp_mss + 40);
else if (f->fp_flags & PF_OSFP_WSIZE_MOD)
find.fp_wsize *= 2;
if (f != (f2 = pf_osfp_find(&pf_osfp_list, &find, 0))) {
if (f2)
printf("Found \"%s %s %s\" instead of "
"\"%s %s %s\"\n",
SLIST_FIRST(&f2->fp_oses)->fp_class_nm,
SLIST_FIRST(&f2->fp_oses)->fp_version_nm,
SLIST_FIRST(&f2->fp_oses)->fp_subtype_nm,
SLIST_FIRST(&f->fp_oses)->fp_class_nm,
SLIST_FIRST(&f->fp_oses)->fp_version_nm,
SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
else
printf("Couldn't find \"%s %s %s\"\n",
SLIST_FIRST(&f->fp_oses)->fp_class_nm,
SLIST_FIRST(&f->fp_oses)->fp_version_nm,
SLIST_FIRST(&f->fp_oses)->fp_subtype_nm);
return (f);
}
}
return (NULL);
}