From patchwork Mon Apr 9 09:32:12 2018 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: "Fernando F. Mancera" X-Patchwork-Id: 896195 X-Patchwork-Delegate: pablo@netfilter.org Return-Path: X-Original-To: incoming@patchwork.ozlabs.org Delivered-To: patchwork-incoming@bilbo.ozlabs.org Authentication-Results: ozlabs.org; spf=none (mailfrom) smtp.mailfrom=vger.kernel.org (client-ip=209.132.180.67; helo=vger.kernel.org; envelope-from=netfilter-devel-owner@vger.kernel.org; receiver=) Authentication-Results: ozlabs.org; dmarc=fail (p=none dis=none) header.from=riseup.net Authentication-Results: ozlabs.org; dkim=fail reason="signature verification failed" (1024-bit key; unprotected) header.d=riseup.net header.i=@riseup.net header.b="NZ+VTOyf"; dkim-atps=neutral Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by ozlabs.org (Postfix) with ESMTP id 40KQ7w40NGz9s27 for ; Mon, 9 Apr 2018 19:32:44 +1000 (AEST) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751464AbeDIJck (ORCPT ); Mon, 9 Apr 2018 05:32:40 -0400 Received: from mx1.riseup.net ([198.252.153.129]:42836 "EHLO mx1.riseup.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751291AbeDIJcj (ORCPT ); Mon, 9 Apr 2018 05:32:39 -0400 Received: from cotinga.riseup.net (cotinga-pn.riseup.net [10.0.1.164]) (using TLSv1 with cipher ECDHE-RSA-AES256-SHA (256/256 bits)) (Client CN "*.riseup.net", Issuer "COMODO RSA Domain Validation Secure Server CA" (verified OK)) by mx1.riseup.net (Postfix) with ESMTPS id 3D5F81A08E6 for ; Mon, 9 Apr 2018 02:32:38 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=riseup.net; s=squak; t=1523266358; bh=Wrd588pJmbR7qrlgMUq2KQdwWr/dtdJ8KWNhlhNGHIc=; h=From:To:Cc:Subject:Date:From; b=NZ+VTOyffklvPtrb+TVjzBn90NQOAFAwGONI3/C/Cb/oYxk3ASwkHk5uCiq9Uk2g0 wmf1KPc4ThDmRvCfYY5xtUhG9zvaSQVv9yQ3fQxtJKTtV4PJjLlE4rdlVLX2ySxLz4 0RxRXLvF9znaLWhegqR210luxkgCyqllSeCiQlY8= X-Riseup-User-ID: 6D171FDA59CF8DED84DB5B0966BC5EF5BFCA096E52570CF4A9B6CA1664805A0A Received: from [127.0.0.1] (localhost [127.0.0.1]) by cotinga.riseup.net with ESMTPSA id CD499894B3; Mon, 9 Apr 2018 02:32:36 -0700 (PDT) From: Fernando Fernandez Mancera To: netfilter-devel@vger.kernel.org Cc: Fernando Fernandez Mancera Subject: [PATCH nf-next v4] netfilter: nf_osf: nf_osf_ttl() and nf_osf_match() Date: Mon, 9 Apr 2018 11:32:12 +0200 Message-Id: <20180409093212.19849-1-ffmancera@riseup.net> Sender: netfilter-devel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netfilter-devel@vger.kernel.org Added nf_osf_ttl() and nf_osf_match() into nf_osf.c in order to start the nftables OSF implementation. Signed-off-by: Fernando Fernandez Mancera --- include/linux/netfilter/nf_osf.h | 28 ++++ include/uapi/linux/netfilter/nf_osf.h | 97 ++++++++++++++ include/uapi/linux/netfilter/xt_osf.h | 106 +++------------ net/netfilter/Kconfig | 4 + net/netfilter/Makefile | 1 + net/netfilter/nf_osf.c | 241 ++++++++++++++++++++++++++++++++++ net/netfilter/xt_osf.c | 202 +--------------------------- 7 files changed, 390 insertions(+), 289 deletions(-) create mode 100644 include/linux/netfilter/nf_osf.h create mode 100644 include/uapi/linux/netfilter/nf_osf.h create mode 100644 net/netfilter/nf_osf.c diff --git a/include/linux/netfilter/nf_osf.h b/include/linux/netfilter/nf_osf.h new file mode 100644 index 000000000000..46ae80b1d096 --- /dev/null +++ b/include/linux/netfilter/nf_osf.h @@ -0,0 +1,28 @@ +#include + +/* + * Initial window size option state machine: multiple of mss, mtu or + * plain numeric value. Can also be made as plain numeric value which + * is not a multiple of specified value. + */ +enum nf_osf_window_size_options { + OSF_WSS_PLAIN = 0, + OSF_WSS_MSS, + OSF_WSS_MTU, + OSF_WSS_MODULO, + OSF_WSS_MAX, +}; + +enum osf_fmatch_states { + /* Packet does not match the fingerprint */ + FMATCH_WRONG = 0, + /* Packet matches the fingerprint */ + FMATCH_OK, + /* Options do not match the fingerprint, but header does */ + FMATCH_OPT_WRONG, +}; + +bool nf_osf_match(const struct sk_buff *skb, u_int8_t family, + int hooknum, struct net_device *in, struct net_device *out, + const struct nf_osf_info *info, struct net *net); + diff --git a/include/uapi/linux/netfilter/nf_osf.h b/include/uapi/linux/netfilter/nf_osf.h new file mode 100644 index 000000000000..9164ea564bdd --- /dev/null +++ b/include/uapi/linux/netfilter/nf_osf.h @@ -0,0 +1,97 @@ +#ifndef _NF_OSF_H +#define _NF_OSF_H + +#define MAXGENRELEN 32 + +#define NF_OSF_GENRE (1<<0) +#define NF_OSF_TTL (1<<1) +#define NF_OSF_LOG (1<<2) +#define NF_OSF_INVERT (1<<3) + +#define NF_OSF_LOGLEVEL_ALL 0 /* log all matched fingerprints */ +#define NF_OSF_LOGLEVEL_FIRST 1 /* log only the first matced fingerprint */ +#define NF_OSF_LOGLEVEL_ALL_KNOWN 2 /* do not log unknown packets */ + +#define NF_OSF_TTL_TRUE 0 /* True ip and fingerprint TTL comparison */ + +/* Do not compare ip and fingerprint TTL at all */ +#define NF_OSF_TTL_NOCHECK 2 + +/* + * Wildcard MSS (kind of). + * It is used to implement a state machine for the different wildcard values + * of the MSS and window sizes. + */ +struct nf_osf_wc { + __u32 wc; + __u32 val; +}; + +/* + * This struct represents IANA options + * http://www.iana.org/assignments/tcp-parameters + */ +struct nf_osf_opt { + __u16 kind, length; + struct nf_osf_wc wc; +}; + +struct nf_osf_info { + char genre[MAXGENRELEN]; + __u32 len; + __u32 flags; + __u32 loglevel; + __u32 ttl; +}; + +struct nf_osf_user_finger { + struct nf_osf_wc wss; + + __u8 ttl, df; + __u16 ss, mss; + __u16 opt_num; + + char genre[MAXGENRELEN]; + char version[MAXGENRELEN]; + char subtype[MAXGENRELEN]; + + /* MAX_IPOPTLEN is maximum if all options are NOPs or EOLs */ + struct nf_osf_opt opt[MAX_IPOPTLEN]; +}; + +struct nf_osf_finger { + struct rcu_head rcu_head; + struct list_head finger_entry; + struct nf_osf_user_finger finger; +}; + +struct nf_osf_nlmsg { + struct nf_osf_user_finger f; + struct iphdr ip; + struct tcphdr tcp; +}; + +/* Defines for IANA option kinds */ + +enum iana_options { + OSFOPT_EOL = 0, /* End of options */ + OSFOPT_NOP, /* NOP */ + OSFOPT_MSS, /* Maximum segment size */ + OSFOPT_WSO, /* Window scale option */ + OSFOPT_SACKP, /* SACK permitted */ + OSFOPT_SACK, /* SACK */ + OSFOPT_ECHO, + OSFOPT_ECHOREPLY, + OSFOPT_TS, /* Timestamp option */ + OSFOPT_POCP, /* Partial Order Connection Permitted */ + OSFOPT_POSP, /* Partial Order Service Profile */ + + /* Others are not used in the current OSF */ + OSFOPT_EMPTY = 255, +}; + +bool nf_osf_match(const struct sk_buff *skb, u_int8_t family, + int hooknum, struct net_device *in, struct net_device *out, + const struct nf_osf_info *info, struct net *net); + +#endif /* _NF_OSF_H */ diff --git a/include/uapi/linux/netfilter/xt_osf.h b/include/uapi/linux/netfilter/xt_osf.h index dad197e2ab99..55a33cf6c87b 100644 --- a/include/uapi/linux/netfilter/xt_osf.h +++ b/include/uapi/linux/netfilter/xt_osf.h @@ -23,101 +23,29 @@ #include #include #include +#include -#define MAXGENRELEN 32 +#define XT_OSF_GENRE NF_OSF_GENRE +#define XT_OSF_INVERT NF_OSF_INVERT -#define XT_OSF_GENRE (1<<0) -#define XT_OSF_TTL (1<<1) -#define XT_OSF_LOG (1<<2) -#define XT_OSF_INVERT (1<<3) +#define XT_OSF_TTL NF_OSF_TTL +#define XT_OSF_LOG NF_OSF_LOG -#define XT_OSF_LOGLEVEL_ALL 0 /* log all matched fingerprints */ -#define XT_OSF_LOGLEVEL_FIRST 1 /* log only the first matced fingerprint */ -#define XT_OSF_LOGLEVEL_ALL_KNOWN 2 /* do not log unknown packets */ +#define XT_OSF_LOGLEVEL_ALL NF_OSF_LOGLEVEL_ALL +#define XT_OSF_LOGLEVEL_FIRST NF_OSF_LOGLEVEL_FIRST +#define XT_OSF_LOGLEVEL_ALL_KNOWN NF_OSF_LOGLEVEL_ALL_KNOWN -#define XT_OSF_TTL_TRUE 0 /* True ip and fingerprint TTL comparison */ -#define XT_OSF_TTL_LESS 1 /* Check if ip TTL is less than fingerprint one */ -#define XT_OSF_TTL_NOCHECK 2 /* Do not compare ip and fingerprint TTL at all */ +#define XT_OSF_TTL_TRUE NF_OSF_TTL_TRUE +#define XT_OSF_TTL_NOCHECK NF_OSF_TTL_NOCHECK -struct xt_osf_info { - char genre[MAXGENRELEN]; - __u32 len; - __u32 flags; - __u32 loglevel; - __u32 ttl; -}; - -/* - * Wildcard MSS (kind of). - * It is used to implement a state machine for the different wildcard values - * of the MSS and window sizes. - */ -struct xt_osf_wc { - __u32 wc; - __u32 val; -}; - -/* - * This struct represents IANA options - * http://www.iana.org/assignments/tcp-parameters - */ -struct xt_osf_opt { - __u16 kind, length; - struct xt_osf_wc wc; -}; - -struct xt_osf_user_finger { - struct xt_osf_wc wss; - - __u8 ttl, df; - __u16 ss, mss; - __u16 opt_num; - - char genre[MAXGENRELEN]; - char version[MAXGENRELEN]; - char subtype[MAXGENRELEN]; +#define XT_OSF_TTL_LESS 1 /* Check if ip TTL is less than fingerprint one */ - /* MAX_IPOPTLEN is maximum if all options are NOPs or EOLs */ - struct xt_osf_opt opt[MAX_IPOPTLEN]; -}; - -struct xt_osf_nlmsg { - struct xt_osf_user_finger f; - struct iphdr ip; - struct tcphdr tcp; -}; - -/* Defines for IANA option kinds */ - -enum iana_options { - OSFOPT_EOL = 0, /* End of options */ - OSFOPT_NOP, /* NOP */ - OSFOPT_MSS, /* Maximum segment size */ - OSFOPT_WSO, /* Window scale option */ - OSFOPT_SACKP, /* SACK permitted */ - OSFOPT_SACK, /* SACK */ - OSFOPT_ECHO, - OSFOPT_ECHOREPLY, - OSFOPT_TS, /* Timestamp option */ - OSFOPT_POCP, /* Partial Order Connection Permitted */ - OSFOPT_POSP, /* Partial Order Service Profile */ - - /* Others are not used in the current OSF */ - OSFOPT_EMPTY = 255, -}; - -/* - * Initial window size option state machine: multiple of mss, mtu or - * plain numeric value. Can also be made as plain numeric value which - * is not a multiple of specified value. - */ -enum xt_osf_window_size_options { - OSF_WSS_PLAIN = 0, - OSF_WSS_MSS, - OSF_WSS_MTU, - OSF_WSS_MODULO, - OSF_WSS_MAX, -}; +#define xt_osf_wc nf_osf_wc +#define xt_osf_opt nf_osf_opt +#define xt_osf_info nf_osf_info +#define xt_osf_user_finger nf_osf_user_finger +#define xt_osf_finger nf_osf_finger +#define xt_osf_nlmsg nf_osf_nlmsg /* * Add/remove fingerprint from the kernel. diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index d3220b43c832..7c0015f3a43e 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -444,6 +444,9 @@ config NETFILTER_SYNPROXY endif # NF_CONNTRACK +config NF_OSF + tristate '"osf" Passive OS fingerprint match' + config NF_TABLES select NETFILTER_NETLINK tristate "Netfilter nf_tables support" @@ -1377,6 +1380,7 @@ config NETFILTER_XT_MATCH_NFACCT config NETFILTER_XT_MATCH_OSF tristate '"osf" Passive OS fingerprint match' depends on NETFILTER_ADVANCED && NETFILTER_NETLINK + select NF_OSF help This option selects the Passive OS Fingerprinting match module that allows to passively match the remote operating system by diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 138db16d59ed..c9ddff965e4f 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -105,6 +105,7 @@ obj-$(CONFIG_NFT_HASH) += nft_hash.o obj-$(CONFIG_NFT_FIB) += nft_fib.o obj-$(CONFIG_NFT_FIB_INET) += nft_fib_inet.o obj-$(CONFIG_NFT_FIB_NETDEV) += nft_fib_netdev.o +obj-$(CONFIG_NF_OSF) += nf_osf.o # nf_tables netdev obj-$(CONFIG_NFT_DUP_NETDEV) += nft_dup_netdev.o diff --git a/net/netfilter/nf_osf.c b/net/netfilter/nf_osf.c new file mode 100644 index 000000000000..a9582d4fb460 --- /dev/null +++ b/net/netfilter/nf_osf.c @@ -0,0 +1,241 @@ +/* + * Copyright (c) 2003+ Evgeniy Polyakov + * + * + * This program is free software; you can redistribute it and/or modify + * it under the terms of the GNU General Public License as published by + * the Free Software Foundation; either version 2 of the License, or + * (at your option) any later version. + * + * This program is distributed in the hope that it will be useful, + * but WITHOUT ANY WARRANTY; without even the implied warranty of + * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the + * GNU General Public License for more details. + * + * You should have received a copy of the GNU General Public License + * along with this program; if not, see . + */ +#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt +#include +#include + +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include + +#include +#include +#include +#include +/* Indexed by dont-fragment bit. + * It is the only constant value in the fingerprint. + */ +static struct list_head nf_osf_fingers[2]; + +static inline int nf_osf_ttl(const struct sk_buff *skb, + const struct nf_osf_info *info, + unsigned char f_ttl) +{ + const struct iphdr *ip = ip_hdr(skb); + + if (info->flags & NF_OSF_TTL) { + if (info->ttl == NF_OSF_TTL_TRUE) + return ip->ttl == f_ttl; + if (info->ttl == NF_OSF_TTL_NOCHECK) + return 1; + else if (ip->ttl <= f_ttl) + return 1; + else { + struct in_device *in_dev = __in_dev_get_rcu(skb->dev); + int ret = 0; + + for_ifa(in_dev) { + if (inet_ifa_match(ip->saddr, ifa)) { + ret = (ip->ttl == f_ttl); + break; + } + } + endfor_ifa(in_dev); + + return ret; + } + } + + return ip->ttl == f_ttl; +} + +bool +nf_osf_match(const struct sk_buff *skb, u_int8_t family, + int hooknum, struct net_device *in, struct net_device *out, + const struct nf_osf_info *info, struct net *net) +{ +const struct iphdr *ip = ip_hdr(skb); + const struct tcphdr *tcp; + struct tcphdr _tcph; + int fmatch = FMATCH_WRONG, fcount = 0; + unsigned int optsize = 0, check_WSS = 0; + u16 window, totlen, mss = 0; + bool df; + const unsigned char *optp = NULL, *_optp = NULL; + unsigned char opts[MAX_IPOPTLEN]; + const struct nf_osf_finger *kf; + const struct nf_osf_user_finger *f; + + tcp = skb_header_pointer(skb, ip_hdrlen(skb), + sizeof(struct tcphdr), &_tcph); + if (!tcp) + return false; + + if (!tcp->syn) + return false; + + totlen = ntohs(ip->tot_len); + df = ntohs(ip->frag_off) & IP_DF; + window = ntohs(tcp->window); + + if (tcp->doff * 4 > sizeof(struct tcphdr)) { + optsize = tcp->doff * 4 - sizeof(struct tcphdr); + + _optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) + + sizeof(struct tcphdr), optsize, opts); + } + + list_for_each_entry_rcu(kf, &nf_osf_fingers[df], finger_entry) { + int foptsize, optnum; + + f = &kf->finger; + + if (!(info->flags & NF_OSF_LOG) && + strcmp(info->genre, f->genre)) + continue; + + optp = _optp; + fmatch = FMATCH_WRONG; + + if (totlen != f->ss || !nf_osf_ttl(skb, info, f->ttl)) + continue; + + /* + * Should not happen if userspace parser was written correctly. + */ + if (f->wss.wc >= OSF_WSS_MAX) + continue; + + /* Check options */ + + foptsize = 0; + for (optnum = 0; optnum < f->opt_num; ++optnum) + foptsize += f->opt[optnum].length; + + if (foptsize > MAX_IPOPTLEN || + optsize > MAX_IPOPTLEN || + optsize != foptsize) + continue; + + check_WSS = f->wss.wc; + + for (optnum = 0; optnum < f->opt_num; ++optnum) { + if (f->opt[optnum].kind == (*optp)) { + __u32 len = f->opt[optnum].length; + const __u8 *optend = optp + len; + + fmatch = FMATCH_OK; + + switch (*optp) { + case OSFOPT_MSS: + mss = optp[3]; + mss <<= 8; + mss |= optp[2]; + + mss = ntohs((__force __be16)mss); + break; + case OSFOPT_TS: + break; + } + + optp = optend; + } else + fmatch = FMATCH_OPT_WRONG; + + if (fmatch != FMATCH_OK) + break; + } + + if (fmatch != FMATCH_OPT_WRONG) { + fmatch = FMATCH_WRONG; + + switch (check_WSS) { + case OSF_WSS_PLAIN: + if (f->wss.val == 0 || window == f->wss.val) + fmatch = FMATCH_OK; + break; + case OSF_WSS_MSS: + /* + * Some smart modems decrease mangle MSS to + * SMART_MSS_2, so we check standard, decreased + * and the one provided in the fingerprint MSS + * values. + */ +#define SMART_MSS_1 1460 +#define SMART_MSS_2 1448 + if (window == f->wss.val * mss || + window == f->wss.val * SMART_MSS_1 || + window == f->wss.val * SMART_MSS_2) + fmatch = FMATCH_OK; + break; + case OSF_WSS_MTU: + if (window == f->wss.val * (mss + 40) || + window == f->wss.val * (SMART_MSS_1 + 40) || + window == f->wss.val * (SMART_MSS_2 + 40)) + fmatch = FMATCH_OK; + break; + case OSF_WSS_MODULO: + if ((window % f->wss.val) == 0) + fmatch = FMATCH_OK; + break; + } + } + + if (fmatch != FMATCH_OK) + continue; + + fcount++; + + if (info->flags & NF_OSF_LOG) + nf_log_packet(net, family, hooknum, skb, + in, out, NULL, + "%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n", + f->genre, f->version, f->subtype, + &ip->saddr, ntohs(tcp->source), + &ip->daddr, ntohs(tcp->dest), + f->ttl - ip->ttl); + + if ((info->flags & NF_OSF_LOG) && + info->loglevel == NF_OSF_LOGLEVEL_FIRST) + break; + } + + if (!fcount && (info->flags & NF_OSF_LOG)) + nf_log_packet(net, family, hooknum, skb, in, + out, NULL, + "Remote OS is not known: %pI4:%u -> %pI4:%u\n", + &ip->saddr, ntohs(tcp->source), + &ip->daddr, ntohs(tcp->dest)); + + if (fcount) + fmatch = FMATCH_OK; + + return fmatch == FMATCH_OK; +} +EXPORT_SYMBOL_GPL(nf_osf_match); + +MODULE_LICENSE("GPL"); diff --git a/net/netfilter/xt_osf.c b/net/netfilter/xt_osf.c index a34f314a8c23..a860b2d41382 100644 --- a/net/netfilter/xt_osf.c +++ b/net/netfilter/xt_osf.c @@ -37,21 +37,6 @@ #include #include -struct xt_osf_finger { - struct rcu_head rcu_head; - struct list_head finger_entry; - struct xt_osf_user_finger finger; -}; - -enum osf_fmatch_states { - /* Packet does not match the fingerprint */ - FMATCH_WRONG = 0, - /* Packet matches the fingerprint */ - FMATCH_OK, - /* Options do not match the fingerprint, but header does */ - FMATCH_OPT_WRONG, -}; - /* * Indexed by dont-fragment bit. * It is the only constant value in the fingerprint. @@ -164,200 +149,17 @@ static const struct nfnetlink_subsystem xt_osf_nfnetlink = { .cb = xt_osf_nfnetlink_callbacks, }; -static inline int xt_osf_ttl(const struct sk_buff *skb, const struct xt_osf_info *info, - unsigned char f_ttl) -{ - const struct iphdr *ip = ip_hdr(skb); - - if (info->flags & XT_OSF_TTL) { - if (info->ttl == XT_OSF_TTL_TRUE) - return ip->ttl == f_ttl; - if (info->ttl == XT_OSF_TTL_NOCHECK) - return 1; - else if (ip->ttl <= f_ttl) - return 1; - else { - struct in_device *in_dev = __in_dev_get_rcu(skb->dev); - int ret = 0; - - for_ifa(in_dev) { - if (inet_ifa_match(ip->saddr, ifa)) { - ret = (ip->ttl == f_ttl); - break; - } - } - endfor_ifa(in_dev); - - return ret; - } - } - - return ip->ttl == f_ttl; -} - static bool xt_osf_match_packet(const struct sk_buff *skb, struct xt_action_param *p) { const struct xt_osf_info *info = p->matchinfo; - const struct iphdr *ip = ip_hdr(skb); - const struct tcphdr *tcp; - struct tcphdr _tcph; - int fmatch = FMATCH_WRONG, fcount = 0; - unsigned int optsize = 0, check_WSS = 0; - u16 window, totlen, mss = 0; - bool df; - const unsigned char *optp = NULL, *_optp = NULL; - unsigned char opts[MAX_IPOPTLEN]; - const struct xt_osf_finger *kf; - const struct xt_osf_user_finger *f; struct net *net = xt_net(p); if (!info) return false; - tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph); - if (!tcp) - return false; - - if (!tcp->syn) - return false; - - totlen = ntohs(ip->tot_len); - df = ntohs(ip->frag_off) & IP_DF; - window = ntohs(tcp->window); - - if (tcp->doff * 4 > sizeof(struct tcphdr)) { - optsize = tcp->doff * 4 - sizeof(struct tcphdr); - - _optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) + - sizeof(struct tcphdr), optsize, opts); - } - - list_for_each_entry_rcu(kf, &xt_osf_fingers[df], finger_entry) { - int foptsize, optnum; - - f = &kf->finger; - - if (!(info->flags & XT_OSF_LOG) && strcmp(info->genre, f->genre)) - continue; - - optp = _optp; - fmatch = FMATCH_WRONG; - - if (totlen != f->ss || !xt_osf_ttl(skb, info, f->ttl)) - continue; - - /* - * Should not happen if userspace parser was written correctly. - */ - if (f->wss.wc >= OSF_WSS_MAX) - continue; - - /* Check options */ - - foptsize = 0; - for (optnum = 0; optnum < f->opt_num; ++optnum) - foptsize += f->opt[optnum].length; - - if (foptsize > MAX_IPOPTLEN || - optsize > MAX_IPOPTLEN || - optsize != foptsize) - continue; - - check_WSS = f->wss.wc; - - for (optnum = 0; optnum < f->opt_num; ++optnum) { - if (f->opt[optnum].kind == (*optp)) { - __u32 len = f->opt[optnum].length; - const __u8 *optend = optp + len; - - fmatch = FMATCH_OK; - - switch (*optp) { - case OSFOPT_MSS: - mss = optp[3]; - mss <<= 8; - mss |= optp[2]; - - mss = ntohs((__force __be16)mss); - break; - case OSFOPT_TS: - break; - } - - optp = optend; - } else - fmatch = FMATCH_OPT_WRONG; - - if (fmatch != FMATCH_OK) - break; - } - - if (fmatch != FMATCH_OPT_WRONG) { - fmatch = FMATCH_WRONG; - - switch (check_WSS) { - case OSF_WSS_PLAIN: - if (f->wss.val == 0 || window == f->wss.val) - fmatch = FMATCH_OK; - break; - case OSF_WSS_MSS: - /* - * Some smart modems decrease mangle MSS to - * SMART_MSS_2, so we check standard, decreased - * and the one provided in the fingerprint MSS - * values. - */ -#define SMART_MSS_1 1460 -#define SMART_MSS_2 1448 - if (window == f->wss.val * mss || - window == f->wss.val * SMART_MSS_1 || - window == f->wss.val * SMART_MSS_2) - fmatch = FMATCH_OK; - break; - case OSF_WSS_MTU: - if (window == f->wss.val * (mss + 40) || - window == f->wss.val * (SMART_MSS_1 + 40) || - window == f->wss.val * (SMART_MSS_2 + 40)) - fmatch = FMATCH_OK; - break; - case OSF_WSS_MODULO: - if ((window % f->wss.val) == 0) - fmatch = FMATCH_OK; - break; - } - } - - if (fmatch != FMATCH_OK) - continue; - - fcount++; - - if (info->flags & XT_OSF_LOG) - nf_log_packet(net, xt_family(p), xt_hooknum(p), skb, - xt_in(p), xt_out(p), NULL, - "%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n", - f->genre, f->version, f->subtype, - &ip->saddr, ntohs(tcp->source), - &ip->daddr, ntohs(tcp->dest), - f->ttl - ip->ttl); - - if ((info->flags & XT_OSF_LOG) && - info->loglevel == XT_OSF_LOGLEVEL_FIRST) - break; - } - - if (!fcount && (info->flags & XT_OSF_LOG)) - nf_log_packet(net, xt_family(p), xt_hooknum(p), skb, xt_in(p), - xt_out(p), NULL, - "Remote OS is not known: %pI4:%u -> %pI4:%u\n", - &ip->saddr, ntohs(tcp->source), - &ip->daddr, ntohs(tcp->dest)); - - if (fcount) - fmatch = FMATCH_OK; - - return fmatch == FMATCH_OK; + return nf_osf_match(skb, xt_family(p), xt_hooknum(p), xt_in(p), + xt_out(p), info, net); } static struct xt_match xt_osf_match = {