531 lines
15 KiB
C
531 lines
15 KiB
C
/*-
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* SPDX-License-Identifier: ISC
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*
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* Copyright (c) 2003 Mike Frantzen <frantzen@w4g.org>
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*
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* Permission to use, copy, modify, and distribute this software for any
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* purpose with or without fee is hereby granted, provided that the above
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* copyright notice and this permission notice appear in all copies.
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*
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* THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
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* WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
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* MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
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* ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
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* WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
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* ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
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* OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
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*
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* $OpenBSD: pf_osfp.c,v 1.14 2008/06/12 18:17:01 henning Exp $
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*/
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#include <sys/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_inet6.h"
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#include <sys/param.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/mbuf.h>
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#include <sys/socket.h>
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#include <netinet/in.h>
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#include <netinet/ip.h>
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#include <netinet/tcp.h>
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#include <net/if.h>
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#include <net/vnet.h>
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#include <net/pfvar.h>
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#ifdef INET6
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#include <netinet/ip6.h>
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#endif
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static MALLOC_DEFINE(M_PFOSFP, "pf_osfp", "pf(4) operating system fingerprints");
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#define DPFPRINTF(format, x...) \
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if (V_pf_status.debug >= PF_DEBUG_NOISY) \
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printf(format , ##x)
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SLIST_HEAD(pf_osfp_list, pf_os_fingerprint);
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VNET_DEFINE_STATIC(struct pf_osfp_list, pf_osfp_list) =
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SLIST_HEAD_INITIALIZER();
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#define V_pf_osfp_list VNET(pf_osfp_list)
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static struct pf_osfp_enlist *pf_osfp_fingerprint_hdr(const struct ip *,
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const struct ip6_hdr *,
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const struct tcphdr *);
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static struct pf_os_fingerprint *pf_osfp_find(struct pf_osfp_list *,
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struct pf_os_fingerprint *, u_int8_t);
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static struct pf_os_fingerprint *pf_osfp_find_exact(struct pf_osfp_list *,
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struct pf_os_fingerprint *);
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static void pf_osfp_insert(struct pf_osfp_list *,
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struct pf_os_fingerprint *);
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#ifdef PFDEBUG
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static struct pf_os_fingerprint *pf_osfp_validate(void);
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#endif
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/*
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* Passively fingerprint the OS of the host (IPv4 TCP SYN packets only)
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* Returns the list of possible OSes.
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*/
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struct pf_osfp_enlist *
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pf_osfp_fingerprint(struct pf_pdesc *pd, struct mbuf *m, int off,
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const struct tcphdr *tcp)
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{
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struct ip *ip;
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struct ip6_hdr *ip6;
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char hdr[60];
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if ((pd->af != PF_INET && pd->af != PF_INET6) ||
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pd->proto != IPPROTO_TCP || (tcp->th_off << 2) < sizeof(*tcp))
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return (NULL);
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if (pd->af == PF_INET) {
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ip = mtod(m, struct ip *);
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ip6 = (struct ip6_hdr *)NULL;
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} else {
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ip = (struct ip *)NULL;
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ip6 = mtod(m, struct ip6_hdr *);
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}
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if (!pf_pull_hdr(m, off, hdr, tcp->th_off << 2, NULL, NULL,
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pd->af)) return (NULL);
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return (pf_osfp_fingerprint_hdr(ip, ip6, (struct tcphdr *)hdr));
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}
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static struct pf_osfp_enlist *
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pf_osfp_fingerprint_hdr(const struct ip *ip, const struct ip6_hdr *ip6, const struct tcphdr *tcp)
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{
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struct pf_os_fingerprint fp, *fpresult;
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int cnt, optlen = 0;
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const u_int8_t *optp;
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#ifdef INET6
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char srcname[INET6_ADDRSTRLEN];
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#else
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char srcname[INET_ADDRSTRLEN];
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#endif
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if ((tcp->th_flags & (TH_SYN|TH_ACK)) != TH_SYN)
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return (NULL);
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if (ip) {
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if ((ip->ip_off & htons(IP_OFFMASK)) != 0)
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return (NULL);
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}
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memset(&fp, 0, sizeof(fp));
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if (ip) {
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fp.fp_psize = ntohs(ip->ip_len);
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fp.fp_ttl = ip->ip_ttl;
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if (ip->ip_off & htons(IP_DF))
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fp.fp_flags |= PF_OSFP_DF;
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inet_ntoa_r(ip->ip_src, srcname);
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}
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#ifdef INET6
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else if (ip6) {
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/* jumbo payload? */
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fp.fp_psize = sizeof(struct ip6_hdr) + ntohs(ip6->ip6_plen);
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fp.fp_ttl = ip6->ip6_hlim;
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fp.fp_flags |= PF_OSFP_DF;
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fp.fp_flags |= PF_OSFP_INET6;
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ip6_sprintf(srcname, (const struct in6_addr *)&ip6->ip6_src);
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}
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#endif
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else
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return (NULL);
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fp.fp_wsize = ntohs(tcp->th_win);
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cnt = (tcp->th_off << 2) - sizeof(*tcp);
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optp = (const u_int8_t *)((const char *)tcp + sizeof(*tcp));
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for (; cnt > 0; cnt -= optlen, optp += optlen) {
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if (*optp == TCPOPT_EOL)
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break;
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fp.fp_optcnt++;
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if (*optp == TCPOPT_NOP) {
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fp.fp_tcpopts = (fp.fp_tcpopts << PF_OSFP_TCPOPT_BITS) |
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PF_OSFP_TCPOPT_NOP;
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optlen = 1;
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} else {
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if (cnt < 2)
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return (NULL);
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optlen = optp[1];
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if (optlen > cnt || optlen < 2)
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return (NULL);
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switch (*optp) {
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case TCPOPT_MAXSEG:
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if (optlen >= TCPOLEN_MAXSEG)
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memcpy(&fp.fp_mss, &optp[2],
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sizeof(fp.fp_mss));
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fp.fp_tcpopts = (fp.fp_tcpopts <<
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PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_MSS;
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NTOHS(fp.fp_mss);
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break;
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case TCPOPT_WINDOW:
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if (optlen >= TCPOLEN_WINDOW)
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memcpy(&fp.fp_wscale, &optp[2],
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sizeof(fp.fp_wscale));
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NTOHS(fp.fp_wscale);
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fp.fp_tcpopts = (fp.fp_tcpopts <<
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PF_OSFP_TCPOPT_BITS) |
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PF_OSFP_TCPOPT_WSCALE;
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break;
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case TCPOPT_SACK_PERMITTED:
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fp.fp_tcpopts = (fp.fp_tcpopts <<
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PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_SACK;
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break;
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case TCPOPT_TIMESTAMP:
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if (optlen >= TCPOLEN_TIMESTAMP) {
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u_int32_t ts;
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memcpy(&ts, &optp[2], sizeof(ts));
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if (ts == 0)
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fp.fp_flags |= PF_OSFP_TS0;
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}
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fp.fp_tcpopts = (fp.fp_tcpopts <<
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PF_OSFP_TCPOPT_BITS) | PF_OSFP_TCPOPT_TS;
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break;
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default:
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return (NULL);
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}
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}
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optlen = MAX(optlen, 1); /* paranoia */
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}
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DPFPRINTF("fingerprinted %s:%d %d:%d:%d:%d:%llx (%d) "
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"(TS=%s,M=%s%d,W=%s%d)\n",
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srcname, ntohs(tcp->th_sport),
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fp.fp_wsize, fp.fp_ttl, (fp.fp_flags & PF_OSFP_DF) != 0,
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fp.fp_psize, (long long int)fp.fp_tcpopts, fp.fp_optcnt,
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(fp.fp_flags & PF_OSFP_TS0) ? "0" : "",
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(fp.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
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(fp.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
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fp.fp_mss,
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(fp.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
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(fp.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
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fp.fp_wscale);
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if ((fpresult = pf_osfp_find(&V_pf_osfp_list, &fp,
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PF_OSFP_MAXTTL_OFFSET)))
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return (&fpresult->fp_oses);
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return (NULL);
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}
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/* Match a fingerprint ID against a list of OSes */
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int
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pf_osfp_match(struct pf_osfp_enlist *list, pf_osfp_t os)
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{
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struct pf_osfp_entry *entry;
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int os_class, os_version, os_subtype;
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int en_class, en_version, en_subtype;
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if (os == PF_OSFP_ANY)
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return (1);
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if (list == NULL) {
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DPFPRINTF("osfp no match against %x\n", os);
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return (os == PF_OSFP_UNKNOWN);
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}
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PF_OSFP_UNPACK(os, os_class, os_version, os_subtype);
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SLIST_FOREACH(entry, list, fp_entry) {
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PF_OSFP_UNPACK(entry->fp_os, en_class, en_version, en_subtype);
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if ((os_class == PF_OSFP_ANY || en_class == os_class) &&
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(os_version == PF_OSFP_ANY || en_version == os_version) &&
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(os_subtype == PF_OSFP_ANY || en_subtype == os_subtype)) {
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DPFPRINTF("osfp matched %s %s %s %x==%x\n",
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entry->fp_class_nm, entry->fp_version_nm,
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entry->fp_subtype_nm, os, entry->fp_os);
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return (1);
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}
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}
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DPFPRINTF("fingerprint 0x%x didn't match\n", os);
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return (0);
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}
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/* Flush the fingerprint list */
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void
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pf_osfp_flush(void)
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{
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struct pf_os_fingerprint *fp;
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struct pf_osfp_entry *entry;
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while ((fp = SLIST_FIRST(&V_pf_osfp_list))) {
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SLIST_REMOVE_HEAD(&V_pf_osfp_list, fp_next);
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while ((entry = SLIST_FIRST(&fp->fp_oses))) {
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SLIST_REMOVE_HEAD(&fp->fp_oses, fp_entry);
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free(entry, M_PFOSFP);
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}
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free(fp, M_PFOSFP);
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}
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}
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/* Add a fingerprint */
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int
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pf_osfp_add(struct pf_osfp_ioctl *fpioc)
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{
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struct pf_os_fingerprint *fp, fpadd;
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struct pf_osfp_entry *entry;
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PF_RULES_WASSERT();
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memset(&fpadd, 0, sizeof(fpadd));
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fpadd.fp_tcpopts = fpioc->fp_tcpopts;
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fpadd.fp_wsize = fpioc->fp_wsize;
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fpadd.fp_psize = fpioc->fp_psize;
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fpadd.fp_mss = fpioc->fp_mss;
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fpadd.fp_flags = fpioc->fp_flags;
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fpadd.fp_optcnt = fpioc->fp_optcnt;
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fpadd.fp_wscale = fpioc->fp_wscale;
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fpadd.fp_ttl = fpioc->fp_ttl;
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#if 0 /* XXX RYAN wants to fix logging */
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DPFPRINTF("adding osfp %s %s %s = %s%d:%d:%d:%s%d:0x%llx %d "
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"(TS=%s,M=%s%d,W=%s%d) %x\n",
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fpioc->fp_os.fp_class_nm, fpioc->fp_os.fp_version_nm,
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fpioc->fp_os.fp_subtype_nm,
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(fpadd.fp_flags & PF_OSFP_WSIZE_MOD) ? "%" :
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(fpadd.fp_flags & PF_OSFP_WSIZE_MSS) ? "S" :
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(fpadd.fp_flags & PF_OSFP_WSIZE_MTU) ? "T" :
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(fpadd.fp_flags & PF_OSFP_WSIZE_DC) ? "*" : "",
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fpadd.fp_wsize,
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fpadd.fp_ttl,
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(fpadd.fp_flags & PF_OSFP_DF) ? 1 : 0,
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(fpadd.fp_flags & PF_OSFP_PSIZE_MOD) ? "%" :
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(fpadd.fp_flags & PF_OSFP_PSIZE_DC) ? "*" : "",
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fpadd.fp_psize,
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(long long int)fpadd.fp_tcpopts, fpadd.fp_optcnt,
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(fpadd.fp_flags & PF_OSFP_TS0) ? "0" : "",
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(fpadd.fp_flags & PF_OSFP_MSS_MOD) ? "%" :
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(fpadd.fp_flags & PF_OSFP_MSS_DC) ? "*" : "",
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fpadd.fp_mss,
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(fpadd.fp_flags & PF_OSFP_WSCALE_MOD) ? "%" :
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(fpadd.fp_flags & PF_OSFP_WSCALE_DC) ? "*" : "",
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fpadd.fp_wscale,
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fpioc->fp_os.fp_os);
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#endif
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if ((fp = pf_osfp_find_exact(&V_pf_osfp_list, &fpadd))) {
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SLIST_FOREACH(entry, &fp->fp_oses, fp_entry) {
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if (PF_OSFP_ENTRY_EQ(entry, &fpioc->fp_os))
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return (EEXIST);
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}
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if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
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== NULL)
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return (ENOMEM);
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} else {
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if ((fp = malloc(sizeof(*fp), M_PFOSFP, M_ZERO | M_NOWAIT))
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== NULL)
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return (ENOMEM);
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fp->fp_tcpopts = fpioc->fp_tcpopts;
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fp->fp_wsize = fpioc->fp_wsize;
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fp->fp_psize = fpioc->fp_psize;
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fp->fp_mss = fpioc->fp_mss;
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fp->fp_flags = fpioc->fp_flags;
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fp->fp_optcnt = fpioc->fp_optcnt;
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fp->fp_wscale = fpioc->fp_wscale;
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fp->fp_ttl = fpioc->fp_ttl;
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SLIST_INIT(&fp->fp_oses);
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if ((entry = malloc(sizeof(*entry), M_PFOSFP, M_NOWAIT))
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== NULL) {
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free(fp, M_PFOSFP);
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return (ENOMEM);
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}
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pf_osfp_insert(&V_pf_osfp_list, fp);
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}
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memcpy(entry, &fpioc->fp_os, sizeof(*entry));
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/* Make sure the strings are NUL terminated */
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entry->fp_class_nm[sizeof(entry->fp_class_nm)-1] = '\0';
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entry->fp_version_nm[sizeof(entry->fp_version_nm)-1] = '\0';
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entry->fp_subtype_nm[sizeof(entry->fp_subtype_nm)-1] = '\0';
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SLIST_INSERT_HEAD(&fp->fp_oses, entry, fp_entry);
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#ifdef PFDEBUG
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if ((fp = pf_osfp_validate()))
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printf("Invalid fingerprint list\n");
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#endif /* PFDEBUG */
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return (0);
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}
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/* Find a fingerprint in the list */
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static struct pf_os_fingerprint *
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pf_osfp_find(struct pf_osfp_list *list, struct pf_os_fingerprint *find,
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u_int8_t ttldiff)
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{
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struct pf_os_fingerprint *f;
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#define MATCH_INT(_MOD, _DC, _field) \
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if ((f->fp_flags & _DC) == 0) { \
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if ((f->fp_flags & _MOD) == 0) { \
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if (f->_field != find->_field) \
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continue; \
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} else { \
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if (f->_field == 0 || find->_field % f->_field) \
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continue; \
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} \
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}
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SLIST_FOREACH(f, list, fp_next) {
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if (f->fp_tcpopts != find->fp_tcpopts ||
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f->fp_optcnt != find->fp_optcnt ||
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f->fp_ttl < find->fp_ttl ||
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f->fp_ttl - find->fp_ttl > ttldiff ||
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(f->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)) !=
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(find->fp_flags & (PF_OSFP_DF|PF_OSFP_TS0)))
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continue;
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MATCH_INT(PF_OSFP_PSIZE_MOD, PF_OSFP_PSIZE_DC, fp_psize)
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MATCH_INT(PF_OSFP_MSS_MOD, PF_OSFP_MSS_DC, fp_mss)
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MATCH_INT(PF_OSFP_WSCALE_MOD, PF_OSFP_WSCALE_DC, fp_wscale)
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if ((f->fp_flags & PF_OSFP_WSIZE_DC) == 0) {
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if (f->fp_flags & PF_OSFP_WSIZE_MSS) {
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if (find->fp_mss == 0)
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continue;
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/*
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* Some "smart" NAT devices and DSL routers will tweak the MSS size and
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* will set it to whatever is suitable for the link type.
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*/
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#define SMART_MSS 1460
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if ((find->fp_wsize % find->fp_mss ||
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find->fp_wsize / find->fp_mss !=
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f->fp_wsize) &&
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(find->fp_wsize % SMART_MSS ||
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find->fp_wsize / SMART_MSS !=
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f->fp_wsize))
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continue;
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} else if (f->fp_flags & PF_OSFP_WSIZE_MTU) {
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if (find->fp_mss == 0)
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continue;
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#define MTUOFF (sizeof(struct ip) + sizeof(struct tcphdr))
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#define SMART_MTU (SMART_MSS + MTUOFF)
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if ((find->fp_wsize % (find->fp_mss + MTUOFF) ||
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find->fp_wsize / (find->fp_mss + MTUOFF) !=
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f->fp_wsize) &&
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(find->fp_wsize % SMART_MTU ||
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find->fp_wsize / SMART_MTU !=
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f->fp_wsize))
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continue;
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} else if (f->fp_flags & PF_OSFP_WSIZE_MOD) {
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if (f->fp_wsize == 0 || find->fp_wsize %
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f->fp_wsize)
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continue;
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} else {
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if (f->fp_wsize != find->fp_wsize)
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continue;
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}
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}
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return (f);
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}
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return (NULL);
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}
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|
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/* Find an exact fingerprint in the list */
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static struct pf_os_fingerprint *
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pf_osfp_find_exact(struct pf_osfp_list *list, struct pf_os_fingerprint *find)
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{
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struct pf_os_fingerprint *f;
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SLIST_FOREACH(f, list, fp_next) {
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if (f->fp_tcpopts == find->fp_tcpopts &&
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f->fp_wsize == find->fp_wsize &&
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f->fp_psize == find->fp_psize &&
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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 */
|
|
static 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, &V_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);
|
|
}
|
|
|
|
#ifdef PFDEBUG
|
|
/* Validate that each signature is reachable */
|
|
static struct pf_os_fingerprint *
|
|
pf_osfp_validate(void)
|
|
{
|
|
struct pf_os_fingerprint *f, *f2, find;
|
|
|
|
SLIST_FOREACH(f, &V_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;
|
|
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(&V_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);
|
|
}
|
|
#endif /* PFDEBUG */
|