[GitHub/exynos8895/android_kernel_samsung_universal8895.git] / net / netfilter / xt_osf.c

/*
 * Copyright (c) 2003+ Evgeniy Polyakov <zbr@ioremap.net>
 *
 *
 * 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, write to the Free Software
 * Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
 */
#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
#include <linux/module.h>
#include <linux/kernel.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/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.
 */
static struct list_head xt_osf_fingers[2];

static const struct nla_policy xt_osf_policy[OSF_ATTR_MAX + 1] = {
	[OSF_ATTR_FINGER]	= { .len = sizeof(struct xt_osf_user_finger) },
};

static int xt_osf_add_callback(struct sock *ctnl, struct sk_buff *skb,
			       const struct nlmsghdr *nlh,
			       const struct nlattr * const osf_attrs[])
{
	struct xt_osf_user_finger *f;
	struct xt_osf_finger *kf = NULL, *sf;
	int err = 0;

	if (!osf_attrs[OSF_ATTR_FINGER])
		return -EINVAL;

	if (!(nlh->nlmsg_flags & NLM_F_CREATE))
		return -EINVAL;

	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

	kf = kmalloc(sizeof(struct xt_osf_finger), GFP_KERNEL);
	if (!kf)
		return -ENOMEM;

	memcpy(&kf->finger, f, sizeof(struct xt_osf_user_finger));

	list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
		if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
			continue;

		kfree(kf);
		kf = NULL;

		if (nlh->nlmsg_flags & NLM_F_EXCL)
			err = -EEXIST;
		break;
	}

	/*
	 * We are protected by nfnl mutex.
	 */
	if (kf)
		list_add_tail_rcu(&kf->finger_entry, &xt_osf_fingers[!!f->df]);

	return err;
}

static int xt_osf_remove_callback(struct sock *ctnl, struct sk_buff *skb,
				  const struct nlmsghdr *nlh,
				  const struct nlattr * const osf_attrs[])
{
	struct xt_osf_user_finger *f;
	struct xt_osf_finger *sf;
	int err = -ENOENT;

	if (!osf_attrs[OSF_ATTR_FINGER])
		return -EINVAL;

	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);

	list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
		if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
			continue;

		/*
		 * We are protected by nfnl mutex.
		 */
		list_del_rcu(&sf->finger_entry);
		kfree_rcu(sf, rcu_head);

		err = 0;
		break;
	}

	return err;
}

static const struct nfnl_callback xt_osf_nfnetlink_callbacks[OSF_MSG_MAX] = {
	[OSF_MSG_ADD]	= {
		.call		= xt_osf_add_callback,
		.attr_count	= OSF_ATTR_MAX,
		.policy		= xt_osf_policy,
	},
	[OSF_MSG_REMOVE]	= {
		.call		= xt_osf_remove_callback,
		.attr_count	= OSF_ATTR_MAX,
		.policy		= xt_osf_policy,
	},
};

static const struct nfnetlink_subsystem xt_osf_nfnetlink = {
	.name			= "osf",
	.subsys_id		= NFNL_SUBSYS_OSF,
	.cb_count		= OSF_MSG_MAX,
	.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;

	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);
	}

	rcu_read_lock();
	list_for_each_entry_rcu(kf, &xt_osf_fingers[df], finger_entry) {
		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)) {
			int foptsize, optnum;

			/*
			 * 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;
					int loop_cont = 0;

					fmatch = FMATCH_OK;

					switch (*optp) {
					case OSFOPT_MSS:
						mss = optp[3];
						mss <<= 8;
						mss |= optp[2];

						mss = ntohs(mss);
						break;
					case OSFOPT_TS:
						loop_cont = 1;
						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(p->family, p->hooknum, skb,
					p->in, p->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 & XT_OSF_LOG) &&
			    info->loglevel == XT_OSF_LOGLEVEL_FIRST)
				break;
		}
	}
	rcu_read_unlock();

	if (!fcount && (info->flags & XT_OSF_LOG))
		nf_log_packet(p->family, p->hooknum, skb, p->in, p->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;
}

static struct xt_match xt_osf_match = {
	.name 		= "osf",
	.revision	= 0,
	.family		= NFPROTO_IPV4,
	.proto		= IPPROTO_TCP,
	.hooks      	= (1 << NF_INET_LOCAL_IN) |
				(1 << NF_INET_PRE_ROUTING) |
				(1 << NF_INET_FORWARD),
	.match 		= xt_osf_match_packet,
	.matchsize	= sizeof(struct xt_osf_info),
	.me		= THIS_MODULE,
};

static int __init xt_osf_init(void)
{
	int err = -EINVAL;
	int i;

	for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i)
		INIT_LIST_HEAD(&xt_osf_fingers[i]);

	err = nfnetlink_subsys_register(&xt_osf_nfnetlink);
	if (err < 0) {
		pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
		goto err_out_exit;
	}

	err = xt_register_match(&xt_osf_match);
	if (err) {
		pr_err("Failed to register OS fingerprint "
		       "matching module (%d)\n", err);
		goto err_out_remove;
	}

	return 0;

err_out_remove:
	nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
err_out_exit:
	return err;
}

static void __exit xt_osf_fini(void)
{
	struct xt_osf_finger *f;
	int i;

	nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
	xt_unregister_match(&xt_osf_match);

	rcu_read_lock();
	for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i) {

		list_for_each_entry_rcu(f, &xt_osf_fingers[i], finger_entry) {
			list_del_rcu(&f->finger_entry);
			kfree_rcu(f, rcu_head);
		}
	}
	rcu_read_unlock();

	rcu_barrier();
}

module_init(xt_osf_init);
module_exit(xt_osf_fini);

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
MODULE_DESCRIPTION("Passive OS fingerprint matching.");
MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_OSF);
Commit	Line	Data
11eeef41 EP	1	/*
	2	* Copyright (c) 2003+ Evgeniy Polyakov <zbr@ioremap.net>
	3	*
	4	*
	5	* This program is free software; you can redistribute it and/or modify
	6	* it under the terms of the GNU General Public License as published by
	7	* the Free Software Foundation; either version 2 of the License, or
	8	* (at your option) any later version.
	9	*
	10	* This program is distributed in the hope that it will be useful,
	11	* but WITHOUT ANY WARRANTY; without even the implied warranty of
	12	* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
	13	* GNU General Public License for more details.
	14	*
	15	* You should have received a copy of the GNU General Public License
	16	* along with this program; if not, write to the Free Software
	17	* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
	18	*/
8bee4bad	19	#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
11eeef41 EP	20	#include <linux/module.h>
	21	#include <linux/kernel.h>
	22
	23	#include <linux/if.h>
	24	#include <linux/inetdevice.h>
	25	#include <linux/ip.h>
	26	#include <linux/list.h>
	27	#include <linux/rculist.h>
	28	#include <linux/skbuff.h>
	29	#include <linux/slab.h>
	30	#include <linux/tcp.h>
	31
	32	#include <net/ip.h>
	33	#include <net/tcp.h>
	34
	35	#include <linux/netfilter/nfnetlink.h>
	36	#include <linux/netfilter/x_tables.h>
	37	#include <net/netfilter/nf_log.h>
	38	#include <linux/netfilter/xt_osf.h>
	39
	40	struct xt_osf_finger {
	41	struct rcu_head rcu_head;
	42	struct list_head finger_entry;
	43	struct xt_osf_user_finger finger;
	44	};
	45
	46	enum osf_fmatch_states {
	47	/* Packet does not match the fingerprint */
	48	FMATCH_WRONG = 0,
	49	/* Packet matches the fingerprint */
	50	FMATCH_OK,
	51	/* Options do not match the fingerprint, but header does */
	52	FMATCH_OPT_WRONG,
	53	};
	54
	55	/*
	56	* Indexed by dont-fragment bit.
	57	* It is the only constant value in the fingerprint.
	58	*/
	59	static struct list_head xt_osf_fingers[2];
	60
	61	static const struct nla_policy xt_osf_policy[OSF_ATTR_MAX + 1] = {
	62	[OSF_ATTR_FINGER] = { .len = sizeof(struct xt_osf_user_finger) },
	63	};
	64
11eeef41	65	static int xt_osf_add_callback(struct sock ctnl, struct sk_buff skb,
39938324 PM	66	const struct nlmsghdr *nlh,
39938324 PM	67	const struct nlattr * const osf_attrs[])
11eeef41 EP	68	{
	69	struct xt_osf_user_finger *f;
	70	struct xt_osf_finger kf = NULL, sf;
	71	int err = 0;
	72
	73	if (!osf_attrs[OSF_ATTR_FINGER])
	74	return -EINVAL;
	75
	76	if (!(nlh->nlmsg_flags & NLM_F_CREATE))
	77	return -EINVAL;
	78
	79	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
	80
	81	kf = kmalloc(sizeof(struct xt_osf_finger), GFP_KERNEL);
	82	if (!kf)
	83	return -ENOMEM;
	84
	85	memcpy(&kf->finger, f, sizeof(struct xt_osf_user_finger));
	86
	87	list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
	88	if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
	89	continue;
	90
	91	kfree(kf);
	92	kf = NULL;
	93
	94	if (nlh->nlmsg_flags & NLM_F_EXCL)
	95	err = -EEXIST;
	96	break;
	97	}
	98
	99	/*
	100	* We are protected by nfnl mutex.
	101	*/
	102	if (kf)
	103	list_add_tail_rcu(&kf->finger_entry, &xt_osf_fingers[!!f->df]);
	104
	105	return err;
	106	}
	107
	108	static int xt_osf_remove_callback(struct sock ctnl, struct sk_buff skb,
39938324 PM	109	const struct nlmsghdr *nlh,
39938324 PM	110	const struct nlattr * const osf_attrs[])
11eeef41 EP	111	{
	112	struct xt_osf_user_finger *f;
	113	struct xt_osf_finger *sf;
d667b9cf	114	int err = -ENOENT;
11eeef41 EP	115
	116	if (!osf_attrs[OSF_ATTR_FINGER])
	117	return -EINVAL;
	118
	119	f = nla_data(osf_attrs[OSF_ATTR_FINGER]);
	120
	121	list_for_each_entry(sf, &xt_osf_fingers[!!f->df], finger_entry) {
	122	if (memcmp(&sf->finger, f, sizeof(struct xt_osf_user_finger)))
	123	continue;
	124
	125	/*
	126	* We are protected by nfnl mutex.
	127	*/
	128	list_del_rcu(&sf->finger_entry);
88b4a034	129	kfree_rcu(sf, rcu_head);
11eeef41 EP	130
	131	err = 0;
	132	break;
	133	}
	134
	135	return err;
	136	}
	137
	138	static const struct nfnl_callback xt_osf_nfnetlink_callbacks[OSF_MSG_MAX] = {
	139	[OSF_MSG_ADD] = {
	140	.call = xt_osf_add_callback,
	141	.attr_count = OSF_ATTR_MAX,
	142	.policy = xt_osf_policy,
	143	},
	144	[OSF_MSG_REMOVE] = {
	145	.call = xt_osf_remove_callback,
	146	.attr_count = OSF_ATTR_MAX,
	147	.policy = xt_osf_policy,
	148	},
	149	};
	150
	151	static const struct nfnetlink_subsystem xt_osf_nfnetlink = {
	152	.name = "osf",
	153	.subsys_id = NFNL_SUBSYS_OSF,
	154	.cb_count = OSF_MSG_MAX,
	155	.cb = xt_osf_nfnetlink_callbacks,
	156	};
	157
	158	static inline int xt_osf_ttl(const struct sk_buff skb, const struct xt_osf_info info,
	159	unsigned char f_ttl)
	160	{
	161	const struct iphdr *ip = ip_hdr(skb);
	162
	163	if (info->flags & XT_OSF_TTL) {
	164	if (info->ttl == XT_OSF_TTL_TRUE)
	165	return ip->ttl == f_ttl;
	166	if (info->ttl == XT_OSF_TTL_NOCHECK)
	167	return 1;
	168	else if (ip->ttl <= f_ttl)
	169	return 1;
	170	else {
	171	struct in_device *in_dev = __in_dev_get_rcu(skb->dev);
	172	int ret = 0;
	173
	174	for_ifa(in_dev) {
	175	if (inet_ifa_match(ip->saddr, ifa)) {
	176	ret = (ip->ttl == f_ttl);
	177	break;
	178	}
	179	}
	180	endfor_ifa(in_dev);
	181
	182	return ret;
	183	}
	184	}
	185
	186	return ip->ttl == f_ttl;
	187	}
	188
4b560b44	189	static bool
62fc8051	190	xt_osf_match_packet(const struct sk_buff skb, struct xt_action_param p)
11eeef41 EP	191	{
	192	const struct xt_osf_info *info = p->matchinfo;
	193	const struct iphdr *ip = ip_hdr(skb);
	194	const struct tcphdr *tcp;
	195	struct tcphdr _tcph;
	196	int fmatch = FMATCH_WRONG, fcount = 0;
	197	unsigned int optsize = 0, check_WSS = 0;
	198	u16 window, totlen, mss = 0;
	199	bool df;
	200	const unsigned char optp = NULL, _optp = NULL;
	201	unsigned char opts[MAX_IPOPTLEN];
	202	const struct xt_osf_finger *kf;
	203	const struct xt_osf_user_finger *f;
	204
	205	if (!info)
	206	return false;
	207
	208	tcp = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(struct tcphdr), &_tcph);
	209	if (!tcp)
	210	return false;
	211
	212	if (!tcp->syn)
	213	return false;
	214
	215	totlen = ntohs(ip->tot_len);
	216	df = ntohs(ip->frag_off) & IP_DF;
	217	window = ntohs(tcp->window);
	218
	219	if (tcp->doff * 4 > sizeof(struct tcphdr)) {
	220	optsize = tcp->doff * 4 - sizeof(struct tcphdr);
	221
	222	_optp = optp = skb_header_pointer(skb, ip_hdrlen(skb) +
	223	sizeof(struct tcphdr), optsize, opts);
	224	}
	225
	226	rcu_read_lock();
	227	list_for_each_entry_rcu(kf, &xt_osf_fingers[df], finger_entry) {
	228	f = &kf->finger;
	229
	230	if (!(info->flags & XT_OSF_LOG) && strcmp(info->genre, f->genre))
	231	continue;
	232
	233	optp = _optp;
	234	fmatch = FMATCH_WRONG;
	235
	236	if (totlen == f->ss && xt_osf_ttl(skb, info, f->ttl)) {
	237	int foptsize, optnum;
	238
	239	/*
	240	* Should not happen if userspace parser was written correctly.
	241	*/
	242	if (f->wss.wc >= OSF_WSS_MAX)
	243	continue;
	244
	245	/* Check options */
	246
	247	foptsize = 0;
	248	for (optnum = 0; optnum < f->opt_num; ++optnum)
	249	foptsize += f->opt[optnum].length;
	250
	251	if (foptsize > MAX_IPOPTLEN \|\|
	252	optsize > MAX_IPOPTLEN \|\|
	253	optsize != foptsize)
	254	continue;
255
256	check_WSS = f->wss.wc;
257
258	for (optnum = 0; optnum < f->opt_num; ++optnum) {
259	if (f->opt[optnum].kind == (*optp)) {
260	__u32 len = f->opt[optnum].length;
261	const __u8 *optend = optp + len;
262	int loop_cont = 0;
263
264	fmatch = FMATCH_OK;
265
266	switch (*optp) {
267	case OSFOPT_MSS:
268	mss = optp[3];
269	mss <<= 8;
270	mss \|= optp[2];
271
272	mss = ntohs(mss);
273	break;
274	case OSFOPT_TS:
275	loop_cont = 1;
276	break;
277	}
278
279	optp = optend;
280	} else
281	fmatch = FMATCH_OPT_WRONG;
282
283	if (fmatch != FMATCH_OK)
284	break;
285	}
286
287	if (fmatch != FMATCH_OPT_WRONG) {
288	fmatch = FMATCH_WRONG;
289
290	switch (check_WSS) {
291	case OSF_WSS_PLAIN:
292	if (f->wss.val == 0 \|\| window == f->wss.val)
293	fmatch = FMATCH_OK;
294	break;
295	case OSF_WSS_MSS:
296	/*
297	* Some smart modems decrease mangle MSS to
298	* SMART_MSS_2, so we check standard, decreased
299	* and the one provided in the fingerprint MSS
300	* values.
301	*/
302	#define SMART_MSS_1 1460
303	#define SMART_MSS_2 1448
304	if (window == f->wss.val * mss \|\|
305	window == f->wss.val * SMART_MSS_1 \|\|
306	window == f->wss.val * SMART_MSS_2)
307	fmatch = FMATCH_OK;
308	break;
309	case OSF_WSS_MTU:
310	if (window == f->wss.val * (mss + 40) \|\|
311	window == f->wss.val * (SMART_MSS_1 + 40) \|\|
312	window == f->wss.val * (SMART_MSS_2 + 40))
313	fmatch = FMATCH_OK;
314	break;
315	case OSF_WSS_MODULO:
316	if ((window % f->wss.val) == 0)
317	fmatch = FMATCH_OK;
318	break;
319	}
320	}
321
322	if (fmatch != FMATCH_OK)
323	continue;
324
325	fcount++;
326
327	if (info->flags & XT_OSF_LOG)
aa6a03eb PM	328	nf_log_packet(p->family, p->hooknum, skb,
aa6a03eb PM	329	p->in, p->out, NULL,
7f635d0d	330	"%s [%s:%s] : %pI4:%d -> %pI4:%d hops=%d\n",
11eeef41 EP	331	f->genre, f->version, f->subtype,
	332	&ip->saddr, ntohs(tcp->source),
	333	&ip->daddr, ntohs(tcp->dest),
	334	f->ttl - ip->ttl);
	335
	336	if ((info->flags & XT_OSF_LOG) &&
	337	info->loglevel == XT_OSF_LOGLEVEL_FIRST)
	338	break;
	339	}
	340	}
	341	rcu_read_unlock();
	342
	343	if (!fcount && (info->flags & XT_OSF_LOG))
aa6a03eb	344	nf_log_packet(p->family, p->hooknum, skb, p->in, p->out, NULL,
7f635d0d	345	"Remote OS is not known: %pI4:%u -> %pI4:%u\n",
11eeef41 EP	346	&ip->saddr, ntohs(tcp->source),
	347	&ip->daddr, ntohs(tcp->dest));
	348
	349	if (fcount)
	350	fmatch = FMATCH_OK;
	351
	352	return fmatch == FMATCH_OK;
	353	}
	354
	355	static struct xt_match xt_osf_match = {
	356	.name = "osf",
	357	.revision = 0,
	358	.family = NFPROTO_IPV4,
	359	.proto = IPPROTO_TCP,
	360	.hooks = (1 << NF_INET_LOCAL_IN) \|
	361	(1 << NF_INET_PRE_ROUTING) \|
	362	(1 << NF_INET_FORWARD),
	363	.match = xt_osf_match_packet,
	364	.matchsize = sizeof(struct xt_osf_info),
	365	.me = THIS_MODULE,
	366	};
	367
	368	static int __init xt_osf_init(void)
	369	{
	370	int err = -EINVAL;
	371	int i;
	372
	373	for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i)
	374	INIT_LIST_HEAD(&xt_osf_fingers[i]);
	375
	376	err = nfnetlink_subsys_register(&xt_osf_nfnetlink);
	377	if (err < 0) {
8bee4bad	378	pr_err("Failed to register OSF nsfnetlink helper (%d)\n", err);
11eeef41 EP	379	goto err_out_exit;
	380	}
	381
	382	err = xt_register_match(&xt_osf_match);
	383	if (err) {
8bee4bad JE	384	pr_err("Failed to register OS fingerprint "
8bee4bad JE	385	"matching module (%d)\n", err);
11eeef41 EP	386	goto err_out_remove;
	387	}
	388
	389	return 0;
	390
	391	err_out_remove:
	392	nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
	393	err_out_exit:
	394	return err;
	395	}
	396
	397	static void __exit xt_osf_fini(void)
	398	{
	399	struct xt_osf_finger *f;
	400	int i;
	401
	402	nfnetlink_subsys_unregister(&xt_osf_nfnetlink);
	403	xt_unregister_match(&xt_osf_match);
	404
	405	rcu_read_lock();
	406	for (i=0; i<ARRAY_SIZE(xt_osf_fingers); ++i) {
	407
	408	list_for_each_entry_rcu(f, &xt_osf_fingers[i], finger_entry) {
	409	list_del_rcu(&f->finger_entry);
88b4a034	410	kfree_rcu(f, rcu_head);
11eeef41 EP	411	}
	412	}
	413	rcu_read_unlock();
	414
	415	rcu_barrier();
	416	}
	417
	418	module_init(xt_osf_init);
	419	module_exit(xt_osf_fini);
	420
	421	MODULE_LICENSE("GPL");
	422	MODULE_AUTHOR("Evgeniy Polyakov <zbr@ioremap.net>");
	423	MODULE_DESCRIPTION("Passive OS fingerprint matching.");
	424	MODULE_ALIAS_NFNL_SUBSYS(NFNL_SUBSYS_OSF);