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

/* SANE connection tracking helper
 * (SANE = Scanner Access Now Easy)
 * For documentation about the SANE network protocol see
 * http://www.sane-project.org/html/doc015.html
 */

/* Copyright (C) 2007 Red Hat, Inc.
 * Author: Michal Schmidt <mschmidt@redhat.com>
 * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
 *  (C) 1999-2001 Paul `Rusty' Russell
 *  (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
 *  (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
 *  (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2 as
 * published by the Free Software Foundation.
 */

#include <linux/module.h>
#include <linux/moduleparam.h>
#include <linux/netfilter.h>
#include <linux/slab.h>
#include <linux/in.h>
#include <linux/tcp.h>
#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <linux/netfilter/nf_conntrack_sane.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
MODULE_DESCRIPTION("SANE connection tracking helper");
MODULE_ALIAS_NFCT_HELPER("sane");

static char *sane_buffer;

static DEFINE_SPINLOCK(nf_sane_lock);

#define MAX_PORTS 8
static u_int16_t ports[MAX_PORTS];
static unsigned int ports_c;
module_param_array(ports, ushort, &ports_c, 0400);

struct sane_request {
	__be32 RPC_code;
#define SANE_NET_START      7   /* RPC code */

	__be32 handle;
};

struct sane_reply_net_start {
	__be32 status;
#define SANE_STATUS_SUCCESS 0

	__be16 zero;
	__be16 port;
	/* other fields aren't interesting for conntrack */
};

static int help(struct sk_buff *skb,
		unsigned int protoff,
		struct nf_conn *ct,
		enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff, datalen;
	const struct tcphdr *th;
	struct tcphdr _tcph;
	void *sb_ptr;
	int ret = NF_ACCEPT;
	int dir = CTINFO2DIR(ctinfo);
	struct nf_ct_sane_master *ct_sane_info;
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_tuple *tuple;
	struct sane_request *req;
	struct sane_reply_net_start *reply;

	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
	/* Until there's been traffic both ways, don't look in packets. */
	if (ctinfo != IP_CT_ESTABLISHED &&
	    ctinfo != IP_CT_ESTABLISHED_REPLY)
		return NF_ACCEPT;

	/* Not a full tcp header? */
	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	/* No data? */
	dataoff = protoff + th->doff * 4;
	if (dataoff >= skb->len)
		return NF_ACCEPT;

	datalen = skb->len - dataoff;

	spin_lock_bh(&nf_sane_lock);
	sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer);
	BUG_ON(sb_ptr == NULL);

	if (dir == IP_CT_DIR_ORIGINAL) {
		if (datalen != sizeof(struct sane_request))
			goto out;

		req = sb_ptr;
		if (req->RPC_code != htonl(SANE_NET_START)) {
			/* Not an interesting command */
			ct_sane_info->state = SANE_STATE_NORMAL;
			goto out;
		}

		/* We're interested in the next reply */
		ct_sane_info->state = SANE_STATE_START_REQUESTED;
		goto out;
	}

	/* Is it a reply to an uninteresting command? */
	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
		goto out;

	/* It's a reply to SANE_NET_START. */
	ct_sane_info->state = SANE_STATE_NORMAL;

	if (datalen < sizeof(struct sane_reply_net_start)) {
		pr_debug("nf_ct_sane: NET_START reply too short\n");
		goto out;
	}

	reply = sb_ptr;
	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
		/* saned refused the command */
		pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
			 ntohl(reply->status));
		goto out;
	}

	/* Invalid saned reply? Ignore it. */
	if (reply->zero != 0)
		goto out;

	exp = nf_ct_expect_alloc(ct);
	if (exp == NULL) {
		ret = NF_DROP;
		goto out;
	}

	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
			  &tuple->src.u3, &tuple->dst.u3,
			  IPPROTO_TCP, NULL, &reply->port);

	pr_debug("nf_ct_sane: expect: ");
	nf_ct_dump_tuple(&exp->tuple);

	/* Can't expect this?  Best to drop packet now. */
	if (nf_ct_expect_related(exp) != 0)
		ret = NF_DROP;

	nf_ct_expect_put(exp);

out:
	spin_unlock_bh(&nf_sane_lock);
	return ret;
}

static struct nf_conntrack_helper sane[MAX_PORTS][2] __read_mostly;

static const struct nf_conntrack_expect_policy sane_exp_policy = {
	.max_expected	= 1,
	.timeout	= 5 * 60,
};

/* don't make this __exit, since it's called from __init ! */
static void nf_conntrack_sane_fini(void)
{
	int i, j;

	for (i = 0; i < ports_c; i++) {
		for (j = 0; j < 2; j++) {
			pr_debug("nf_ct_sane: unregistering helper for pf: %d "
				 "port: %d\n",
				 sane[i][j].tuple.src.l3num, ports[i]);
			nf_conntrack_helper_unregister(&sane[i][j]);
		}
	}

	kfree(sane_buffer);
}

static int __init nf_conntrack_sane_init(void)
{
	int i, j = -1, ret = 0;

	sane_buffer = kmalloc(65536, GFP_KERNEL);
	if (!sane_buffer)
		return -ENOMEM;

	if (ports_c == 0)
		ports[ports_c++] = SANE_PORT;

	/* FIXME should be configurable whether IPv4 and IPv6 connections
		 are tracked or not - YK */
	for (i = 0; i < ports_c; i++) {
		sane[i][0].tuple.src.l3num = PF_INET;
		sane[i][1].tuple.src.l3num = PF_INET6;
		for (j = 0; j < 2; j++) {
			sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
			sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
			sane[i][j].expect_policy = &sane_exp_policy;
			sane[i][j].me = THIS_MODULE;
			sane[i][j].help = help;
			if (ports[i] == SANE_PORT)
				sprintf(sane[i][j].name, "sane");
			else
				sprintf(sane[i][j].name, "sane-%d", ports[i]);

			pr_debug("nf_ct_sane: registering helper for pf: %d "
				 "port: %d\n",
				 sane[i][j].tuple.src.l3num, ports[i]);
			ret = nf_conntrack_helper_register(&sane[i][j]);
			if (ret) {
				printk(KERN_ERR "nf_ct_sane: failed to "
				       "register helper for pf: %d port: %d\n",
					sane[i][j].tuple.src.l3num, ports[i]);
				nf_conntrack_sane_fini();
				return ret;
			}
		}
	}

	return 0;
}

module_init(nf_conntrack_sane_init);
module_exit(nf_conntrack_sane_fini);
Commit	Line	Data
6fecd198 MS	1	/* SANE connection tracking helper
	2	* (SANE = Scanner Access Now Easy)
	3	* For documentation about the SANE network protocol see
	4	* http://www.sane-project.org/html/doc015.html
	5	*/
	6
	7	/* Copyright (C) 2007 Red Hat, Inc.
	8	* Author: Michal Schmidt <mschmidt@redhat.com>
	9	* Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
	10	* (C) 1999-2001 Paul `Rusty' Russell
	11	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	12	* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
	13	* (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
	14	*
	15	* This program is free software; you can redistribute it and/or modify
	16	* it under the terms of the GNU General Public License version 2 as
	17	* published by the Free Software Foundation.
	18	*/
	19
	20	#include <linux/module.h>
	21	#include <linux/moduleparam.h>
	22	#include <linux/netfilter.h>
5a0e3ad6	23	#include <linux/slab.h>
6fecd198 MS	24	#include <linux/in.h>
	25	#include <linux/tcp.h>
	26	#include <net/netfilter/nf_conntrack.h>
	27	#include <net/netfilter/nf_conntrack_helper.h>
	28	#include <net/netfilter/nf_conntrack_expect.h>
	29	#include <linux/netfilter/nf_conntrack_sane.h>
	30
	31	MODULE_LICENSE("GPL");
	32	MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
	33	MODULE_DESCRIPTION("SANE connection tracking helper");
4dc06f96	34	MODULE_ALIAS_NFCT_HELPER("sane");
6fecd198 MS	35
	36	static char *sane_buffer;
	37
	38	static DEFINE_SPINLOCK(nf_sane_lock);
	39
	40	#define MAX_PORTS 8
	41	static u_int16_t ports[MAX_PORTS];
	42	static unsigned int ports_c;
	43	module_param_array(ports, ushort, &ports_c, 0400);
	44
6fecd198 MS	45	struct sane_request {
	46	__be32 RPC_code;
	47	#define SANE_NET_START 7 /* RPC code */
	48
	49	__be32 handle;
	50	};
	51
	52	struct sane_reply_net_start {
	53	__be32 status;
	54	#define SANE_STATUS_SUCCESS 0
	55
	56	__be16 zero;
	57	__be16 port;
	58	/* other fields aren't interesting for conntrack */
	59	};
	60
3db05fea	61	static int help(struct sk_buff *skb,
6fecd198 MS	62	unsigned int protoff,
	63	struct nf_conn *ct,
	64	enum ip_conntrack_info ctinfo)
	65	{
	66	unsigned int dataoff, datalen;
02e23f40 JE	67	const struct tcphdr *th;
	68	struct tcphdr _tcph;
	69	void *sb_ptr;
6fecd198 MS	70	int ret = NF_ACCEPT;
	71	int dir = CTINFO2DIR(ctinfo);
	72	struct nf_ct_sane_master *ct_sane_info;
	73	struct nf_conntrack_expect *exp;
	74	struct nf_conntrack_tuple *tuple;
	75	struct sane_request *req;
	76	struct sane_reply_net_start *reply;
6fecd198 MS	77
	78	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
	79	/* Until there's been traffic both ways, don't look in packets. */
	80	if (ctinfo != IP_CT_ESTABLISHED &&
fb048833	81	ctinfo != IP_CT_ESTABLISHED_REPLY)
6fecd198 MS	82	return NF_ACCEPT;
	83
	84	/* Not a full tcp header? */
3db05fea	85	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
6fecd198 MS	86	if (th == NULL)
	87	return NF_ACCEPT;
	88
	89	/* No data? */
	90	dataoff = protoff + th->doff * 4;
3db05fea	91	if (dataoff >= skb->len)
6fecd198 MS	92	return NF_ACCEPT;
6fecd198 MS	93
3db05fea	94	datalen = skb->len - dataoff;
6fecd198 MS	95
6fecd198 MS	96	spin_lock_bh(&nf_sane_lock);
3db05fea	97	sb_ptr = skb_header_pointer(skb, dataoff, datalen, sane_buffer);
6fecd198 MS	98	BUG_ON(sb_ptr == NULL);
	99
	100	if (dir == IP_CT_DIR_ORIGINAL) {
	101	if (datalen != sizeof(struct sane_request))
	102	goto out;
	103
02e23f40	104	req = sb_ptr;
6fecd198 MS	105	if (req->RPC_code != htonl(SANE_NET_START)) {
	106	/* Not an interesting command */
	107	ct_sane_info->state = SANE_STATE_NORMAL;
	108	goto out;
	109	}
	110
	111	/* We're interested in the next reply */
	112	ct_sane_info->state = SANE_STATE_START_REQUESTED;
	113	goto out;
	114	}
	115
	116	/* Is it a reply to an uninteresting command? */
	117	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
	118	goto out;
	119
	120	/* It's a reply to SANE_NET_START. */
	121	ct_sane_info->state = SANE_STATE_NORMAL;
	122
	123	if (datalen < sizeof(struct sane_reply_net_start)) {
0d53778e	124	pr_debug("nf_ct_sane: NET_START reply too short\n");
6fecd198 MS	125	goto out;
	126	}
	127
02e23f40	128	reply = sb_ptr;
6fecd198 MS	129	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
6fecd198 MS	130	/* saned refused the command */
0d53778e PM	131	pr_debug("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
0d53778e PM	132	ntohl(reply->status));
6fecd198 MS	133	goto out;
	134	}
	135
	136	/* Invalid saned reply? Ignore it. */
	137	if (reply->zero != 0)
	138	goto out;
	139
6823645d	140	exp = nf_ct_expect_alloc(ct);
6fecd198 MS	141	if (exp == NULL) {
	142	ret = NF_DROP;
	143	goto out;
	144	}
	145
	146	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
5e8fbe2a	147	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, nf_ct_l3num(ct),
6002f266	148	&tuple->src.u3, &tuple->dst.u3,
6823645d	149	IPPROTO_TCP, NULL, &reply->port);
6fecd198	150
0d53778e	151	pr_debug("nf_ct_sane: expect: ");
3c9fba65	152	nf_ct_dump_tuple(&exp->tuple);
6fecd198 MS	153
6fecd198 MS	154	/* Can't expect this? Best to drop packet now. */
6823645d	155	if (nf_ct_expect_related(exp) != 0)
6fecd198 MS	156	ret = NF_DROP;
6fecd198 MS	157
6823645d	158	nf_ct_expect_put(exp);
6fecd198 MS	159
	160	out:
	161	spin_unlock_bh(&nf_sane_lock);
	162	return ret;
	163	}
	164
ec59a111	165	static struct nf_conntrack_helper sane[MAX_PORTS][2] __read_mostly;
6fecd198	166
6002f266 PM	167	static const struct nf_conntrack_expect_policy sane_exp_policy = {
	168	.max_expected = 1,
	169	.timeout = 5 * 60,
	170	};
	171
6fecd198 MS	172	/* don't make this __exit, since it's called from __init ! */
	173	static void nf_conntrack_sane_fini(void)
	174	{
	175	int i, j;
	176
	177	for (i = 0; i < ports_c; i++) {
	178	for (j = 0; j < 2; j++) {
0d53778e PM	179	pr_debug("nf_ct_sane: unregistering helper for pf: %d "
	180	"port: %d\n",
	181	sane[i][j].tuple.src.l3num, ports[i]);
6fecd198 MS	182	nf_conntrack_helper_unregister(&sane[i][j]);
	183	}
	184	}
	185
	186	kfree(sane_buffer);
	187	}
	188
	189	static int __init nf_conntrack_sane_init(void)
	190	{
	191	int i, j = -1, ret = 0;
6fecd198 MS	192
	193	sane_buffer = kmalloc(65536, GFP_KERNEL);
	194	if (!sane_buffer)
	195	return -ENOMEM;
	196
	197	if (ports_c == 0)
	198	ports[ports_c++] = SANE_PORT;
	199
	200	/* FIXME should be configurable whether IPv4 and IPv6 connections
	201	are tracked or not - YK */
	202	for (i = 0; i < ports_c; i++) {
	203	sane[i][0].tuple.src.l3num = PF_INET;
	204	sane[i][1].tuple.src.l3num = PF_INET6;
	205	for (j = 0; j < 2; j++) {
	206	sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	207	sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
6002f266	208	sane[i][j].expect_policy = &sane_exp_policy;
6fecd198 MS	209	sane[i][j].me = THIS_MODULE;
6fecd198 MS	210	sane[i][j].help = help;
6fecd198	211	if (ports[i] == SANE_PORT)
3a8fc53a	212	sprintf(sane[i][j].name, "sane");
6fecd198	213	else
3a8fc53a	214	sprintf(sane[i][j].name, "sane-%d", ports[i]);
6fecd198	215
0d53778e PM	216	pr_debug("nf_ct_sane: registering helper for pf: %d "
	217	"port: %d\n",
	218	sane[i][j].tuple.src.l3num, ports[i]);
6fecd198 MS	219	ret = nf_conntrack_helper_register(&sane[i][j]);
	220	if (ret) {
	221	printk(KERN_ERR "nf_ct_sane: failed to "
	222	"register helper for pf: %d port: %d\n",
	223	sane[i][j].tuple.src.l3num, ports[i]);
	224	nf_conntrack_sane_fini();
	225	return ret;
	226	}
	227	}
	228	}
	229
	230	return 0;
	231	}
	232
	233	module_init(nf_conntrack_sane_init);
	234	module_exit(nf_conntrack_sane_fini);