[deliverable/linux.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/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");

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);

#if 0
#define DEBUGP printk
#else
#define DEBUGP(format, args...)
#endif

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 **pskb,
		unsigned int protoff,
		struct nf_conn *ct,
		enum ip_conntrack_info ctinfo)
{
	unsigned int dataoff, datalen;
	struct tcphdr _tcph, *th;
	char *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;
	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;

	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+IP_CT_IS_REPLY)
		return NF_ACCEPT;

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

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

	datalen = (*pskb)->len - dataoff;

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

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

		req = (struct sane_request *)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)) {
		DEBUGP("nf_ct_sane: NET_START reply too short\n");
		goto out;
	}

	reply = (struct sane_reply_net_start *)sb_ptr;
	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
		/* saned refused the command */
		DEBUGP("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, family, &tuple->src.u3, &tuple->dst.u3,
			  IPPROTO_TCP, NULL, &reply->port);

	DEBUGP("nf_ct_sane: expect: ");
	NF_CT_DUMP_TUPLE(&exp->tuple);
	NF_CT_DUMP_TUPLE(&exp->mask);

	/* 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];
static char sane_names[MAX_PORTS][2][sizeof("sane-65535")];

/* 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++) {
			DEBUGP("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;
	char *tmpname;

	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].max_expected = 1;
			sane[i][j].timeout = 5 * 60;	/* 5 Minutes */
			sane[i][j].me = THIS_MODULE;
			sane[i][j].help = help;
			tmpname = &sane_names[i][j][0];
			if (ports[i] == SANE_PORT)
				sprintf(tmpname, "sane");
			else
				sprintf(tmpname, "sane-%d", ports[i]);
			sane[i][j].name = tmpname;

			DEBUGP("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>
	23	#include <linux/in.h>
	24	#include <linux/tcp.h>
	25	#include <net/netfilter/nf_conntrack.h>
	26	#include <net/netfilter/nf_conntrack_helper.h>
	27	#include <net/netfilter/nf_conntrack_expect.h>
	28	#include <linux/netfilter/nf_conntrack_sane.h>
	29
	30	MODULE_LICENSE("GPL");
	31	MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
	32	MODULE_DESCRIPTION("SANE connection tracking helper");
	33
	34	static char *sane_buffer;
	35
	36	static DEFINE_SPINLOCK(nf_sane_lock);
	37
	38	#define MAX_PORTS 8
	39	static u_int16_t ports[MAX_PORTS];
	40	static unsigned int ports_c;
	41	module_param_array(ports, ushort, &ports_c, 0400);
	42
	43	#if 0
	44	#define DEBUGP printk
	45	#else
	46	#define DEBUGP(format, args...)
	47	#endif
	48
	49	struct sane_request {
	50	__be32 RPC_code;
	51	#define SANE_NET_START 7 /* RPC code */
	52
	53	__be32 handle;
	54	};
	55
	56	struct sane_reply_net_start {
	57	__be32 status;
	58	#define SANE_STATUS_SUCCESS 0
	59
	60	__be16 zero;
	61	__be16 port;
	62	/* other fields aren't interesting for conntrack */
	63	};
	64
65	static int help(struct sk_buff **pskb,
66	unsigned int protoff,
67	struct nf_conn *ct,
68	enum ip_conntrack_info ctinfo)
69	{
70	unsigned int dataoff, datalen;
71	struct tcphdr _tcph, *th;
72	char *sb_ptr;
73	int ret = NF_ACCEPT;
74	int dir = CTINFO2DIR(ctinfo);
75	struct nf_ct_sane_master *ct_sane_info;
76	struct nf_conntrack_expect *exp;
77	struct nf_conntrack_tuple *tuple;
78	struct sane_request *req;
79	struct sane_reply_net_start *reply;
80	int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
81
82	ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
83	/* Until there's been traffic both ways, don't look in packets. */
84	if (ctinfo != IP_CT_ESTABLISHED &&
85	ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
86	return NF_ACCEPT;
87
88	/* Not a full tcp header? */
89	th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
90	if (th == NULL)
91	return NF_ACCEPT;
92
93	/* No data? */
94	dataoff = protoff + th->doff * 4;
95	if (dataoff >= (*pskb)->len)
96	return NF_ACCEPT;
97
98	datalen = (*pskb)->len - dataoff;
99
100	spin_lock_bh(&nf_sane_lock);
101	sb_ptr = skb_header_pointer(*pskb, dataoff, datalen, sane_buffer);
102	BUG_ON(sb_ptr == NULL);
103
104	if (dir == IP_CT_DIR_ORIGINAL) {
105	if (datalen != sizeof(struct sane_request))
106	goto out;
107
108	req = (struct sane_request *)sb_ptr;
109	if (req->RPC_code != htonl(SANE_NET_START)) {
110	/* Not an interesting command */
111	ct_sane_info->state = SANE_STATE_NORMAL;
112	goto out;
113	}
114
115	/* We're interested in the next reply */
116	ct_sane_info->state = SANE_STATE_START_REQUESTED;
117	goto out;
118	}
119
120	/* Is it a reply to an uninteresting command? */
121	if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
122	goto out;
123
124	/* It's a reply to SANE_NET_START. */
125	ct_sane_info->state = SANE_STATE_NORMAL;
126
127	if (datalen < sizeof(struct sane_reply_net_start)) {
128	DEBUGP("nf_ct_sane: NET_START reply too short\n");
129	goto out;
130	}
131
132	reply = (struct sane_reply_net_start *)sb_ptr;
133	if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
134	/* saned refused the command */
135	DEBUGP("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
136	ntohl(reply->status));
137	goto out;
138	}
139
140	/* Invalid saned reply? Ignore it. */
141	if (reply->zero != 0)
142	goto out;
143
6823645d	144	exp = nf_ct_expect_alloc(ct);
6fecd198 MS	145	if (exp == NULL) {
	146	ret = NF_DROP;
	147	goto out;
	148	}
	149
	150	tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
6823645d PM	151	nf_ct_expect_init(exp, family, &tuple->src.u3, &tuple->dst.u3,
6823645d PM	152	IPPROTO_TCP, NULL, &reply->port);
6fecd198 MS	153
	154	DEBUGP("nf_ct_sane: expect: ");
	155	NF_CT_DUMP_TUPLE(&exp->tuple);
	156	NF_CT_DUMP_TUPLE(&exp->mask);
	157
	158	/* Can't expect this? Best to drop packet now. */
6823645d	159	if (nf_ct_expect_related(exp) != 0)
6fecd198 MS	160	ret = NF_DROP;
6fecd198 MS	161
6823645d	162	nf_ct_expect_put(exp);
6fecd198 MS	163
	164	out:
	165	spin_unlock_bh(&nf_sane_lock);
	166	return ret;
	167	}
	168
	169	static struct nf_conntrack_helper sane[MAX_PORTS][2];
	170	static char sane_names[MAX_PORTS][2][sizeof("sane-65535")];
	171
	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++) {
	179	DEBUGP("nf_ct_sane: unregistering helper for pf: %d "
	180	"port: %d\n",
	181	sane[i][j].tuple.src.l3num, ports[i]);
	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;
	192	char *tmpname;
	193
	194	sane_buffer = kmalloc(65536, GFP_KERNEL);
	195	if (!sane_buffer)
	196	return -ENOMEM;
	197
	198	if (ports_c == 0)
	199	ports[ports_c++] = SANE_PORT;
	200
	201	/* FIXME should be configurable whether IPv4 and IPv6 connections
	202	are tracked or not - YK */
	203	for (i = 0; i < ports_c; i++) {
	204	sane[i][0].tuple.src.l3num = PF_INET;
	205	sane[i][1].tuple.src.l3num = PF_INET6;
	206	for (j = 0; j < 2; j++) {
	207	sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	208	sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
6fecd198 MS	209	sane[i][j].max_expected = 1;
	210	sane[i][j].timeout = 5 * 60; /* 5 Minutes */
	211	sane[i][j].me = THIS_MODULE;
	212	sane[i][j].help = help;
	213	tmpname = &sane_names[i][j][0];
	214	if (ports[i] == SANE_PORT)
	215	sprintf(tmpname, "sane");
	216	else
	217	sprintf(tmpname, "sane-%d", ports[i]);
	218	sane[i][j].name = tmpname;
	219
	220	DEBUGP("nf_ct_sane: registering helper for pf: %d "
	221	"port: %d\n",
	222	sane[i][j].tuple.src.l3num, ports[i]);
	223	ret = nf_conntrack_helper_register(&sane[i][j]);
	224	if (ret) {
	225	printk(KERN_ERR "nf_ct_sane: failed to "
	226	"register helper for pf: %d port: %d\n",
	227	sane[i][j].tuple.src.l3num, ports[i]);
	228	nf_conntrack_sane_fini();
	229	return ret;
	230	}
	231	}
	232	}
	233
	234	return 0;
	235	}
	236
	237	module_init(nf_conntrack_sane_init);
	238	module_exit(nf_conntrack_sane_fini);