>From 520cf8eb6b1c7ae803f26fdfe8b49b642b1d51d8 Mon Sep 17 00:00:00 2001
From: Fernando Fernandez Mancera <ffmancera@xxxxxxxxxx>
Date: Fri, 30 Mar 2018 15:53:09 +0200
Subject: [PATCH] nf_osf implementation: nf_osf_ttl() and nf_osf_match()
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 <ffmancera@xxxxxxxxxx>
---
include/linux/netfilter/nf_osf.h | 110 ++++++++++++++++
include/uapi/linux/netfilter/xt_osf.h | 101 ++------------
net/netfilter/Kconfig | 5 +
net/netfilter/Makefile | 1 +
net/netfilter/nf_osf.c | 239 ++++++++++++++++++++++++++++++++++
net/netfilter/xt_osf.c | 219 +------------------------------
6 files changed, 369 insertions(+), 306 deletions(-)
create mode 100644 include/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..5f2871fcde42
--- /dev/null
+++ b/include/linux/netfilter/nf_osf.h
@@ -0,0 +1,110 @@
+#define NF_MAXGENRELEN 32
+
+#define NF_OSF_TTL (1<<1)
+#define NF_OSF_LOG (1<<2)
+
+#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 */
+#define NF_OSF_TTL_NOCHECK 2 /* Do not compare ip and fingerprint TTL at all */
+
+/*
+ * 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_info {
+ char genre[NF_MAXGENRELEN];
+ __u32 len;
+ __u32 flags;
+ __u32 loglevel;
+ __u32 ttl;
+};
+
+struct xt_osf_user_finger {
+ struct xt_osf_wc wss;
+
+ __u8 ttl, df;
+ __u16 ss, mss;
+ __u16 opt_num;
+
+ char genre[NF_MAXGENRELEN];
+ char version[NF_MAXGENRELEN];
+ char subtype[NF_MAXGENRELEN];
+
+ /* MAX_IPOPTLEN is maximum if all options are NOPs or EOLs */
+ struct xt_osf_opt opt[MAX_IPOPTLEN];
+};
+
+struct xt_osf_finger {
+ struct rcu_head rcu_head;
+ struct list_head finger_entry;
+ struct xt_osf_user_finger finger;
+};
+
+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,
+};
+
+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 xt_osf_info *info, struct net *net);
diff --git a/include/uapi/linux/netfilter/xt_osf.h b/include/uapi/linux/netfilter/xt_osf.h
index dad197e2ab99..eb71a1c703db 100644
--- a/include/uapi/linux/netfilter/xt_osf.h
+++ b/include/uapi/linux/netfilter/xt_osf.h
@@ -23,101 +23,24 @@
#include <linux/types.h>
#include <linux/ip.h>
#include <linux/tcp.h>
+#include <linux/netfilter/nf_osf.h>
-#define MAXGENRELEN 32
+#define MAXGENRELEN NF_MAXGENRELEN
-#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_GENRE NF_OSF_GENRE
+#define XT_OSF_INVERT NF_OSF_INVERT
-#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_TTL NF_OSF_TTL
+#define XT_OSF_LOG NF_OSF_LOG
-#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 */
-
-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;
+#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
- char genre[MAXGENRELEN];
- char version[MAXGENRELEN];
- char subtype[MAXGENRELEN];
+#define XT_OSF_TTL_TRUE NF_OSF_TTL_TRUE
+#define XT_OSF_TTL_NOCHECK NF_OSF_TTL_NOCHECK
- /* 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_TTL_LESS 1 /* Check if ip TTL is less than fingerprint one */
/*
* Add/remove fingerprint from the kernel.
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index d3220b43c832..bd1c0eef0aa2 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -631,6 +631,10 @@ config NFT_FIB_INET
The lookup will be delegated to the IPv4 or IPv6 FIB depending
on the protocol of the packet.
+config NF_OSF
+ tristate '"osf" Passive OS fingerprint match'
+ depends on NETFILTER_ADVANCED && NETFILTER_NETLINK
+
if NF_TABLES_NETDEV
config NF_DUP_NETDEV
@@ -1377,6 +1381,7 @@ 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..72f8005e1913
--- /dev/null
+++ b/net/netfilter/nf_osf.c
@@ -0,0 +1,239 @@
+/*
+ * Copyright (c) 2003+ Evgeniy Polyakov <zbr@xxxxxxxxxxx>
+ *
+ *
+ * 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 <http://www.gnu.org/licenses/>.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/module.h>
+#include <linux/kernel.h>
+
+#include <linux/capability.h>
+#include <linux/if.h>
+#include <linux/inetdevice.h>
+#include <linux/ip.h>
+#include <linux/list.h>
+#include <linux/rculist.h>
+#include <linux/skbuff.h>
+#include <linux/slab.h>
+#include <linux/tcp.h>
+
+#include <net/ip.h>
+#include <net/tcp.h>
+
+#include <linux/netfilter/nfnetlink.h>
+#include <linux/netfilter/x_tables.h>
+#include <net/netfilter/nf_log.h>
+#include <linux/netfilter/nf_osf.h>
+/*
+ * Indexed by dont-fragment bit.
+ * It is the only constant value in the fingerprint.
+ */
+static struct list_head xt_osf_fingers[2];
+
+static inline int nf_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 & 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 xt_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 xt_osf_finger *kf;
+ const struct xt_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, &xt_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..55f1f79df8a8 100644
--- a/net/netfilter/xt_osf.c
+++ b/net/netfilter/xt_osf.c
@@ -1,20 +1,3 @@
-/*
- * Copyright (c) 2003+ Evgeniy Polyakov <zbr@xxxxxxxxxxx>
- *
- *
- * 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 <http://www.gnu.org/licenses/>.
- */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.h>
@@ -37,21 +20,6 @@
#include <net/netfilter/nf_log.h>
#include <linux/netfilter/xt_osf.h>
-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 +132,17 @@ 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 = {
--
2.16.2
