[net-next-2.6.git] / net / netfilter / nf_conntrack_ftp.c

/* FTP extension for connection tracking. */

/* (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>
 *
 * 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/ip.h>
#include <linux/ipv6.h>
#include <linux/ctype.h>
#include <linux/inet.h>
#include <net/checksum.h>
#include <net/tcp.h>

#include <net/netfilter/nf_conntrack.h>
#include <net/netfilter/nf_conntrack_expect.h>
#include <net/netfilter/nf_conntrack_ecache.h>
#include <net/netfilter/nf_conntrack_helper.h>
#include <linux/netfilter/nf_conntrack_ftp.h>

MODULE_LICENSE("GPL");
MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
MODULE_DESCRIPTION("ftp connection tracking helper");
MODULE_ALIAS("ip_conntrack_ftp");
MODULE_ALIAS_NFCT_HELPER("ftp");

/* This is slow, but it's simple. --RR */
static char *ftp_buffer;

static DEFINE_SPINLOCK(nf_ftp_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);

static int loose;
module_param(loose, bool, 0600);

unsigned int (*nf_nat_ftp_hook)(struct sk_buff *skb,
				enum ip_conntrack_info ctinfo,
				enum nf_ct_ftp_type type,
				unsigned int matchoff,
				unsigned int matchlen,
				struct nf_conntrack_expect *exp);
EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);

static int try_rfc959(const char *, size_t, struct nf_conntrack_man *, char);
static int try_eprt(const char *, size_t, struct nf_conntrack_man *, char);
static int try_epsv_response(const char *, size_t, struct nf_conntrack_man *,
			     char);

static struct ftp_search {
	const char *pattern;
	size_t plen;
	char skip;
	char term;
	enum nf_ct_ftp_type ftptype;
	int (*getnum)(const char *, size_t, struct nf_conntrack_man *, char);
} search[IP_CT_DIR_MAX][2] = {
	[IP_CT_DIR_ORIGINAL] = {
		{
			.pattern	= "PORT",
			.plen		= sizeof("PORT") - 1,
			.skip		= ' ',
			.term		= '\r',
			.ftptype	= NF_CT_FTP_PORT,
			.getnum		= try_rfc959,
		},
		{
			.pattern	= "EPRT",
			.plen		= sizeof("EPRT") - 1,
			.skip		= ' ',
			.term		= '\r',
			.ftptype	= NF_CT_FTP_EPRT,
			.getnum		= try_eprt,
		},
	},
	[IP_CT_DIR_REPLY] = {
		{
			.pattern	= "227 ",
			.plen		= sizeof("227 ") - 1,
			.skip		= '(',
			.term		= ')',
			.ftptype	= NF_CT_FTP_PASV,
			.getnum		= try_rfc959,
		},
		{
			.pattern	= "229 ",
			.plen		= sizeof("229 ") - 1,
			.skip		= '(',
			.term		= ')',
			.ftptype	= NF_CT_FTP_EPSV,
			.getnum		= try_epsv_response,
		},
	},
};

static int
get_ipv6_addr(const char *src, size_t dlen, struct in6_addr *dst, u_int8_t term)
{
	const char *end;
	int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
	if (ret > 0)
		return (int)(end - src);
	return 0;
}

static int try_number(const char *data, size_t dlen, u_int32_t array[],
		      int array_size, char sep, char term)
{
	u_int32_t i, len;

	memset(array, 0, sizeof(array[0])*array_size);

	/* Keep data pointing at next char. */
	for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
		if (*data >= '0' && *data <= '9') {
			array[i] = array[i]*10 + *data - '0';
		}
		else if (*data == sep)
			i++;
		else {
			/* Unexpected character; true if it's the
			   terminator and we're finished. */
			if (*data == term && i == array_size - 1)
				return len;

			pr_debug("Char %u (got %u nums) `%u' unexpected\n",
				 len, i, *data);
			return 0;
		}
	}
	pr_debug("Failed to fill %u numbers separated by %c\n",
		 array_size, sep);
	return 0;
}

/* Returns 0, or length of numbers: 192,168,1,1,5,6 */
static int try_rfc959(const char *data, size_t dlen,
		      struct nf_conntrack_man *cmd, char term)
{
	int length;
	u_int32_t array[6];

	length = try_number(data, dlen, array, 6, ',', term);
	if (length == 0)
		return 0;

	cmd->u3.ip =  htonl((array[0] << 24) | (array[1] << 16) |
				    (array[2] << 8) | array[3]);
	cmd->u.tcp.port = htons((array[4] << 8) | array[5]);
	return length;
}

/* Grab port: number up to delimiter */
static int get_port(const char *data, int start, size_t dlen, char delim,
		    __be16 *port)
{
	u_int16_t tmp_port = 0;
	int i;

	for (i = start; i < dlen; i++) {
		/* Finished? */
		if (data[i] == delim) {
			if (tmp_port == 0)
				break;
			*port = htons(tmp_port);
			pr_debug("get_port: return %d\n", tmp_port);
			return i + 1;
		}
		else if (data[i] >= '0' && data[i] <= '9')
			tmp_port = tmp_port*10 + data[i] - '0';
		else { /* Some other crap */
			pr_debug("get_port: invalid char.\n");
			break;
		}
	}
	return 0;
}

/* Returns 0, or length of numbers: |1|132.235.1.2|6275| or |2|3ffe::1|6275| */
static int try_eprt(const char *data, size_t dlen, struct nf_conntrack_man *cmd,
		    char term)
{
	char delim;
	int length;

	/* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
	   then delimiter again. */
	if (dlen <= 3) {
		pr_debug("EPRT: too short\n");
		return 0;
	}
	delim = data[0];
	if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
		pr_debug("try_eprt: invalid delimitter.\n");
		return 0;
	}

	if ((cmd->l3num == PF_INET && data[1] != '1') ||
	    (cmd->l3num == PF_INET6 && data[1] != '2')) {
		pr_debug("EPRT: invalid protocol number.\n");
		return 0;
	}

	pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim);

	if (data[1] == '1') {
		u_int32_t array[4];

		/* Now we have IP address. */
		length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
		if (length != 0)
			cmd->u3.ip = htonl((array[0] << 24) | (array[1] << 16)
					   | (array[2] << 8) | array[3]);
	} else {
		/* Now we have IPv6 address. */
		length = get_ipv6_addr(data + 3, dlen - 3,
				       (struct in6_addr *)cmd->u3.ip6, delim);
	}

	if (length == 0)
		return 0;
	pr_debug("EPRT: Got IP address!\n");
	/* Start offset includes initial "|1|", and trailing delimiter */
	return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
}

/* Returns 0, or length of numbers: |||6446| */
static int try_epsv_response(const char *data, size_t dlen,
			     struct nf_conntrack_man *cmd, char term)
{
	char delim;

	/* Three delimiters. */
	if (dlen <= 3) return 0;
	delim = data[0];
	if (isdigit(delim) || delim < 33 || delim > 126 ||
	    data[1] != delim || data[2] != delim)
		return 0;

	return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
}

/* Return 1 for match, 0 for accept, -1 for partial. */
static int find_pattern(const char *data, size_t dlen,
			const char *pattern, size_t plen,
			char skip, char term,
			unsigned int *numoff,
			unsigned int *numlen,
			struct nf_conntrack_man *cmd,
			int (*getnum)(const char *, size_t,
				      struct nf_conntrack_man *, char))
{
	size_t i;

	pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen);
	if (dlen == 0)
		return 0;

	if (dlen <= plen) {
		/* Short packet: try for partial? */
		if (strnicmp(data, pattern, dlen) == 0)
			return -1;
		else return 0;
	}

	if (strnicmp(data, pattern, plen) != 0) {
#if 0
		size_t i;

		pr_debug("ftp: string mismatch\n");
		for (i = 0; i < plen; i++) {
			pr_debug("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
				 i, data[i], data[i],
				 pattern[i], pattern[i]);
		}
#endif
		return 0;
	}

	pr_debug("Pattern matches!\n");
	/* Now we've found the constant string, try to skip
	   to the 'skip' character */
	for (i = plen; data[i] != skip; i++)
		if (i == dlen - 1) return -1;

	/* Skip over the last character */
	i++;

	pr_debug("Skipped up to `%c'!\n", skip);

	*numoff = i;
	*numlen = getnum(data + i, dlen - i, cmd, term);
	if (!*numlen)
		return -1;

	pr_debug("Match succeeded!\n");
	return 1;
}

/* Look up to see if we're just after a \n. */
static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
{
	unsigned int i;

	for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
		if (info->seq_aft_nl[dir][i] == seq)
			return 1;
	return 0;
}

/* We don't update if it's older than what we have. */
static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
			  struct nf_ct_ftp_master *info, int dir,
			  struct sk_buff *skb)
{
	unsigned int i, oldest;

	/* Look for oldest: if we find exact match, we're done. */
	for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
		if (info->seq_aft_nl[dir][i] == nl_seq)
			return;
	}

	if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
		info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
	} else {
		if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
			oldest = 0;
		else
			oldest = 1;

		if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
			info->seq_aft_nl[dir][oldest] = nl_seq;
	}
}

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;
	const char *fb_ptr;
	int ret;
	u32 seq;
	int dir = CTINFO2DIR(ctinfo);
	unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff);
	struct nf_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
	struct nf_conntrack_expect *exp;
	union nf_inet_addr *daddr;
	struct nf_conntrack_man cmd = {};
	unsigned int i;
	int found = 0, ends_in_nl;
	typeof(nf_nat_ftp_hook) nf_nat_ftp;

	/* 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) {
		pr_debug("ftp: Conntrackinfo = %u\n", ctinfo);
		return NF_ACCEPT;
	}

	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
	if (th == NULL)
		return NF_ACCEPT;

	dataoff = protoff + th->doff * 4;
	/* No data? */
	if (dataoff >= skb->len) {
		pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
			 skb->len);
		return NF_ACCEPT;
	}
	datalen = skb->len - dataoff;

	spin_lock_bh(&nf_ftp_lock);
	fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer);
	BUG_ON(fb_ptr == NULL);

	ends_in_nl = (fb_ptr[datalen - 1] == '\n');
	seq = ntohl(th->seq) + datalen;

	/* Look up to see if we're just after a \n. */
	if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
		/* Now if this ends in \n, update ftp info. */
		pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
			 ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
			 ct_ftp_info->seq_aft_nl[dir][0],
			 ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
			 ct_ftp_info->seq_aft_nl[dir][1]);
		ret = NF_ACCEPT;
		goto out_update_nl;
	}

	/* Initialize IP/IPv6 addr to expected address (it's not mentioned
	   in EPSV responses) */
	cmd.l3num = nf_ct_l3num(ct);
	memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	       sizeof(cmd.u3.all));

	for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
		found = find_pattern(fb_ptr, datalen,
				     search[dir][i].pattern,
				     search[dir][i].plen,
				     search[dir][i].skip,
				     search[dir][i].term,
				     &matchoff, &matchlen,
				     &cmd,
				     search[dir][i].getnum);
		if (found) break;
	}
	if (found == -1) {
		/* We don't usually drop packets.  After all, this is
		   connection tracking, not packet filtering.
		   However, it is necessary for accurate tracking in
		   this case. */
		pr_debug("conntrack_ftp: partial %s %u+%u\n",
			 search[dir][i].pattern,  ntohl(th->seq), datalen);
		ret = NF_DROP;
		goto out;
	} else if (found == 0) { /* No match */
		ret = NF_ACCEPT;
		goto out_update_nl;
	}

	pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
		 matchlen, fb_ptr + matchoff,
		 matchlen, ntohl(th->seq) + matchoff);

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

	/* We refer to the reverse direction ("!dir") tuples here,
	 * because we're expecting something in the other direction.
	 * Doesn't matter unless NAT is happening.  */
	daddr = &ct->tuplehash[!dir].tuple.dst.u3;

	/* Update the ftp info */
	if ((cmd.l3num == nf_ct_l3num(ct)) &&
	    memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
		     sizeof(cmd.u3.all))) {
		/* Enrico Scholz's passive FTP to partially RNAT'd ftp
		   server: it really wants us to connect to a
		   different IP address.  Simply don't record it for
		   NAT. */
		if (cmd.l3num == PF_INET) {
			pr_debug("conntrack_ftp: NOT RECORDING: %pI4 != %pI4\n",
				 &cmd.u3.ip,
				 &ct->tuplehash[dir].tuple.src.u3.ip);
		} else {
			pr_debug("conntrack_ftp: NOT RECORDING: %pI6 != %pI6\n",
				 cmd.u3.ip6,
				 ct->tuplehash[dir].tuple.src.u3.ip6);
		}

		/* Thanks to Cristiano Lincoln Mattos
		   <lincoln@cesar.org.br> for reporting this potential
		   problem (DMZ machines opening holes to internal
		   networks, or the packet filter itself). */
		if (!loose) {
			ret = NF_ACCEPT;
			goto out_put_expect;
		}
		daddr = &cmd.u3;
	}

	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num,
			  &ct->tuplehash[!dir].tuple.src.u3, daddr,
			  IPPROTO_TCP, NULL, &cmd.u.tcp.port);

	/* Now, NAT might want to mangle the packet, and register the
	 * (possibly changed) expectation itself. */
	nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
	if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
		ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype,
				 matchoff, matchlen, exp);
	else {
		/* Can't expect this?  Best to drop packet now. */
		if (nf_ct_expect_related(exp) != 0)
			ret = NF_DROP;
		else
			ret = NF_ACCEPT;
	}

out_put_expect:
	nf_ct_expect_put(exp);

out_update_nl:
	/* Now if this ends in \n, update ftp info.  Seq may have been
	 * adjusted by NAT code. */
	if (ends_in_nl)
		update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
 out:
	spin_unlock_bh(&nf_ftp_lock);
	return ret;
}

static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")] __read_mostly;

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

/* don't make this __exit, since it's called from __init ! */
static void nf_conntrack_ftp_fini(void)
{
	int i, j;
	for (i = 0; i < ports_c; i++) {
		for (j = 0; j < 2; j++) {
			if (ftp[i][j].me == NULL)
				continue;

			pr_debug("nf_ct_ftp: unregistering helper for pf: %d "
				 "port: %d\n",
				 ftp[i][j].tuple.src.l3num, ports[i]);
			nf_conntrack_helper_unregister(&ftp[i][j]);
		}
	}

	kfree(ftp_buffer);
}

static int __init nf_conntrack_ftp_init(void)
{
	int i, j = -1, ret = 0;
	char *tmpname;

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

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

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

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

	return 0;
}

module_init(nf_conntrack_ftp_init);
module_exit(nf_conntrack_ftp_fini);
Commit	Line	Data
9fb9cbb1 YK	1	/* FTP extension for connection tracking. */
	2
	3	/* (C) 1999-2001 Paul `Rusty' Russell
	4	* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
	5	* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
	6	*
	7	* This program is free software; you can redistribute it and/or modify
	8	* it under the terms of the GNU General Public License version 2 as
	9	* published by the Free Software Foundation.
9fb9cbb1 YK	10	*/
9fb9cbb1 YK	11
9fb9cbb1 YK	12	#include <linux/module.h>
	13	#include <linux/moduleparam.h>
	14	#include <linux/netfilter.h>
	15	#include <linux/ip.h>
	16	#include <linux/ipv6.h>
	17	#include <linux/ctype.h>
6a28ec8c	18	#include <linux/inet.h>
9fb9cbb1 YK	19	#include <net/checksum.h>
	20	#include <net/tcp.h>
	21
	22	#include <net/netfilter/nf_conntrack.h>
77ab9cff	23	#include <net/netfilter/nf_conntrack_expect.h>
f6180121	24	#include <net/netfilter/nf_conntrack_ecache.h>
9fb9cbb1 YK	25	#include <net/netfilter/nf_conntrack_helper.h>
	26	#include <linux/netfilter/nf_conntrack_ftp.h>
	27
	28	MODULE_LICENSE("GPL");
	29	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
	30	MODULE_DESCRIPTION("ftp connection tracking helper");
d2483dde	31	MODULE_ALIAS("ip_conntrack_ftp");
4dc06f96	32	MODULE_ALIAS_NFCT_HELPER("ftp");
9fb9cbb1 YK	33
	34	/* This is slow, but it's simple. --RR */
	35	static char *ftp_buffer;
	36
	37	static DEFINE_SPINLOCK(nf_ftp_lock);
	38
	39	#define MAX_PORTS 8
	40	static u_int16_t ports[MAX_PORTS];
	41	static unsigned int ports_c;
	42	module_param_array(ports, ushort, &ports_c, 0400);
	43
	44	static int loose;
e7be6994	45	module_param(loose, bool, 0600);
9fb9cbb1	46
3db05fea	47	unsigned int (nf_nat_ftp_hook)(struct sk_buff skb,
9fb9cbb1	48	enum ip_conntrack_info ctinfo,
55a73324	49	enum nf_ct_ftp_type type,
9fb9cbb1 YK	50	unsigned int matchoff,
9fb9cbb1 YK	51	unsigned int matchlen,
25b86e05	52	struct nf_conntrack_expect *exp);
9fb9cbb1 YK	53	EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
9fb9cbb1 YK	54
9fb9cbb1 YK	55	static int try_rfc959(const char , size_t, struct nf_conntrack_man , char);
	56	static int try_eprt(const char , size_t, struct nf_conntrack_man , char);
	57	static int try_epsv_response(const char , size_t, struct nf_conntrack_man ,
	58	char);
	59
	60	static struct ftp_search {
9fb9cbb1 YK	61	const char *pattern;
	62	size_t plen;
	63	char skip;
	64	char term;
55a73324	65	enum nf_ct_ftp_type ftptype;
9fb9cbb1	66	int (getnum)(const char , size_t, struct nf_conntrack_man *, char);
7d8c5018 PM	67	} search[IP_CT_DIR_MAX][2] = {
	68	[IP_CT_DIR_ORIGINAL] = {
	69	{
	70	.pattern = "PORT",
	71	.plen = sizeof("PORT") - 1,
	72	.skip = ' ',
	73	.term = '\r',
55a73324	74	.ftptype = NF_CT_FTP_PORT,
7d8c5018 PM	75	.getnum = try_rfc959,
	76	},
	77	{
	78	.pattern = "EPRT",
	79	.plen = sizeof("EPRT") - 1,
	80	.skip = ' ',
	81	.term = '\r',
55a73324	82	.ftptype = NF_CT_FTP_EPRT,
7d8c5018 PM	83	.getnum = try_eprt,
7d8c5018 PM	84	},
9fb9cbb1	85	},
7d8c5018 PM	86	[IP_CT_DIR_REPLY] = {
	87	{
	88	.pattern = "227 ",
	89	.plen = sizeof("227 ") - 1,
	90	.skip = '(',
	91	.term = ')',
55a73324	92	.ftptype = NF_CT_FTP_PASV,
7d8c5018 PM	93	.getnum = try_rfc959,
	94	},
	95	{
	96	.pattern = "229 ",
	97	.plen = sizeof("229 ") - 1,
	98	.skip = '(',
	99	.term = ')',
55a73324	100	.ftptype = NF_CT_FTP_EPSV,
7d8c5018 PM	101	.getnum = try_epsv_response,
7d8c5018 PM	102	},
9fb9cbb1 YK	103	},
	104	};
	105
9fb9cbb1 YK	106	static int
	107	get_ipv6_addr(const char src, size_t dlen, struct in6_addr dst, u_int8_t term)
	108	{
6a28ec8c DM	109	const char *end;
6a28ec8c DM	110	int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
1884f78c YH	111	if (ret > 0)
	112	return (int)(end - src);
	113	return 0;
9fb9cbb1 YK	114	}
	115
	116	static int try_number(const char *data, size_t dlen, u_int32_t array[],
601e68e1	117	int array_size, char sep, char term)
9fb9cbb1 YK	118	{
	119	u_int32_t i, len;
	120
	121	memset(array, 0, sizeof(array[0])*array_size);
	122
	123	/* Keep data pointing at next char. */
	124	for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
	125	if (data >= '0' && data <= '9') {
	126	array[i] = array[i]10 + data - '0';
	127	}
	128	else if (*data == sep)
	129	i++;
	130	else {
	131	/* Unexpected character; true if it's the
	132	terminator and we're finished. */
	133	if (*data == term && i == array_size - 1)
	134	return len;
	135
0d53778e PM	136	pr_debug("Char %u (got %u nums) `%u' unexpected\n",
0d53778e PM	137	len, i, *data);
9fb9cbb1 YK	138	return 0;
	139	}
	140	}
0d53778e PM	141	pr_debug("Failed to fill %u numbers separated by %c\n",
0d53778e PM	142	array_size, sep);
9fb9cbb1 YK	143	return 0;
	144	}
	145
	146	/* Returns 0, or length of numbers: 192,168,1,1,5,6 */
	147	static int try_rfc959(const char *data, size_t dlen,
	148	struct nf_conntrack_man *cmd, char term)
	149	{
	150	int length;
	151	u_int32_t array[6];
	152
	153	length = try_number(data, dlen, array, 6, ',', term);
	154	if (length == 0)
	155	return 0;
	156
	157	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16) \|
	158	(array[2] << 8) \| array[3]);
	159	cmd->u.tcp.port = htons((array[4] << 8) \| array[5]);
	160	return length;
	161	}
	162
	163	/* Grab port: number up to delimiter */
	164	static int get_port(const char *data, int start, size_t dlen, char delim,
bff9a89b	165	__be16 *port)
9fb9cbb1 YK	166	{
	167	u_int16_t tmp_port = 0;
	168	int i;
	169
	170	for (i = start; i < dlen; i++) {
	171	/* Finished? */
	172	if (data[i] == delim) {
	173	if (tmp_port == 0)
	174	break;
	175	*port = htons(tmp_port);
0d53778e	176	pr_debug("get_port: return %d\n", tmp_port);
9fb9cbb1 YK	177	return i + 1;
	178	}
	179	else if (data[i] >= '0' && data[i] <= '9')
	180	tmp_port = tmp_port*10 + data[i] - '0';
	181	else { /* Some other crap */
0d53778e	182	pr_debug("get_port: invalid char.\n");
9fb9cbb1 YK	183	break;
	184	}
	185	}
	186	return 0;
	187	}
	188
	189	/* Returns 0, or length of numbers: \|1\|132.235.1.2\|6275\| or \|2\|3ffe::1\|6275\| */
	190	static int try_eprt(const char data, size_t dlen, struct nf_conntrack_man cmd,
	191	char term)
	192	{
	193	char delim;
	194	int length;
	195
	196	/* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
	197	then delimiter again. */
	198	if (dlen <= 3) {
0d53778e	199	pr_debug("EPRT: too short\n");
9fb9cbb1 YK	200	return 0;
	201	}
	202	delim = data[0];
	203	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126 \|\| data[2] != delim) {
0d53778e	204	pr_debug("try_eprt: invalid delimitter.\n");
9fb9cbb1 YK	205	return 0;
	206	}
	207
	208	if ((cmd->l3num == PF_INET && data[1] != '1') \|\|
	209	(cmd->l3num == PF_INET6 && data[1] != '2')) {
0d53778e	210	pr_debug("EPRT: invalid protocol number.\n");
9fb9cbb1 YK	211	return 0;
	212	}
	213
0d53778e	214	pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim);
9fb9cbb1 YK	215
	216	if (data[1] == '1') {
	217	u_int32_t array[4];
	218
	219	/* Now we have IP address. */
	220	length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
	221	if (length != 0)
	222	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16)
	223	\| (array[2] << 8) \| array[3]);
	224	} else {
	225	/* Now we have IPv6 address. */
	226	length = get_ipv6_addr(data + 3, dlen - 3,
	227	(struct in6_addr *)cmd->u3.ip6, delim);
	228	}
	229
	230	if (length == 0)
	231	return 0;
0d53778e	232	pr_debug("EPRT: Got IP address!\n");
9fb9cbb1 YK	233	/* Start offset includes initial "\|1\|", and trailing delimiter */
	234	return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
	235	}
	236
	237	/* Returns 0, or length of numbers: \|\|\|6446\| */
	238	static int try_epsv_response(const char *data, size_t dlen,
	239	struct nf_conntrack_man *cmd, char term)
	240	{
	241	char delim;
	242
	243	/* Three delimiters. */
	244	if (dlen <= 3) return 0;
	245	delim = data[0];
f64f9e71 JP	246	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126 \|\|
f64f9e71 JP	247	data[1] != delim \|\| data[2] != delim)
9fb9cbb1 YK	248	return 0;
	249
	250	return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
	251	}
	252
	253	/* Return 1 for match, 0 for accept, -1 for partial. */
	254	static int find_pattern(const char *data, size_t dlen,
	255	const char *pattern, size_t plen,
	256	char skip, char term,
	257	unsigned int *numoff,
	258	unsigned int *numlen,
	259	struct nf_conntrack_man *cmd,
	260	int (getnum)(const char , size_t,
	261	struct nf_conntrack_man *, char))
	262	{
	263	size_t i;
	264
0d53778e	265	pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen);
9fb9cbb1 YK	266	if (dlen == 0)
	267	return 0;
	268
	269	if (dlen <= plen) {
	270	/* Short packet: try for partial? */
	271	if (strnicmp(data, pattern, dlen) == 0)
	272	return -1;
	273	else return 0;
	274	}
	275
	276	if (strnicmp(data, pattern, plen) != 0) {
	277	#if 0
	278	size_t i;
	279
0d53778e	280	pr_debug("ftp: string mismatch\n");
9fb9cbb1	281	for (i = 0; i < plen; i++) {
0d53778e PM	282	pr_debug("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
	283	i, data[i], data[i],
	284	pattern[i], pattern[i]);
9fb9cbb1 YK	285	}
	286	#endif
	287	return 0;
	288	}
	289
0d53778e	290	pr_debug("Pattern matches!\n");
9fb9cbb1 YK	291	/* Now we've found the constant string, try to skip
	292	to the 'skip' character */
	293	for (i = plen; data[i] != skip; i++)
	294	if (i == dlen - 1) return -1;
	295
	296	/* Skip over the last character */
	297	i++;
	298
0d53778e	299	pr_debug("Skipped up to `%c'!\n", skip);
9fb9cbb1 YK	300
	301	*numoff = i;
	302	*numlen = getnum(data + i, dlen - i, cmd, term);
	303	if (!*numlen)
	304	return -1;
	305
0d53778e	306	pr_debug("Match succeeded!\n");
9fb9cbb1 YK	307	return 1;
	308	}
	309
	310	/* Look up to see if we're just after a \n. */
55a73324	311	static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
9fb9cbb1 YK	312	{
	313	unsigned int i;
	314
	315	for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
	316	if (info->seq_aft_nl[dir][i] == seq)
	317	return 1;
	318	return 0;
	319	}
	320
	321	/* We don't update if it's older than what we have. */
a71996fc AD	322	static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
a71996fc AD	323	struct nf_ct_ftp_master *info, int dir,
9fb9cbb1 YK	324	struct sk_buff *skb)
9fb9cbb1 YK	325	{
aaff23a9	326	unsigned int i, oldest;
9fb9cbb1 YK	327
	328	/* Look for oldest: if we find exact match, we're done. */
	329	for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
	330	if (info->seq_aft_nl[dir][i] == nl_seq)
	331	return;
9fb9cbb1 YK	332	}
	333
	334	if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
	335	info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
aaff23a9 PM	336	} else {
	337	if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
	338	oldest = 0;
	339	else
	340	oldest = 1;
	341
	342	if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
	343	info->seq_aft_nl[dir][oldest] = nl_seq;
9fb9cbb1 YK	344	}
	345	}
	346
3db05fea	347	static int help(struct sk_buff *skb,
9fb9cbb1 YK	348	unsigned int protoff,
	349	struct nf_conn *ct,
	350	enum ip_conntrack_info ctinfo)
	351	{
	352	unsigned int dataoff, datalen;
58c0fb0d JE	353	const struct tcphdr *th;
	354	struct tcphdr _tcph;
	355	const char *fb_ptr;
9fb9cbb1 YK	356	int ret;
	357	u32 seq;
	358	int dir = CTINFO2DIR(ctinfo);
d6e8cc6c	359	unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff);
55a73324	360	struct nf_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
9fb9cbb1	361	struct nf_conntrack_expect *exp;
643a2c15	362	union nf_inet_addr *daddr;
9fb9cbb1	363	struct nf_conntrack_man cmd = {};
9fb9cbb1 YK	364	unsigned int i;
9fb9cbb1 YK	365	int found = 0, ends_in_nl;
337fbc41	366	typeof(nf_nat_ftp_hook) nf_nat_ftp;
9fb9cbb1 YK	367
9fb9cbb1 YK	368	/* Until there's been traffic both ways, don't look in packets. */
f64f9e71 JP	369	if (ctinfo != IP_CT_ESTABLISHED &&
f64f9e71 JP	370	ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
0d53778e	371	pr_debug("ftp: Conntrackinfo = %u\n", ctinfo);
9fb9cbb1 YK	372	return NF_ACCEPT;
	373	}
	374
3db05fea	375	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
9fb9cbb1 YK	376	if (th == NULL)
	377	return NF_ACCEPT;
	378
	379	dataoff = protoff + th->doff * 4;
	380	/* No data? */
3db05fea	381	if (dataoff >= skb->len) {
0d53778e	382	pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
3db05fea	383	skb->len);
9fb9cbb1 YK	384	return NF_ACCEPT;
9fb9cbb1 YK	385	}
3db05fea	386	datalen = skb->len - dataoff;
9fb9cbb1 YK	387
9fb9cbb1 YK	388	spin_lock_bh(&nf_ftp_lock);
3db05fea	389	fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer);
9fb9cbb1 YK	390	BUG_ON(fb_ptr == NULL);
	391
	392	ends_in_nl = (fb_ptr[datalen - 1] == '\n');
	393	seq = ntohl(th->seq) + datalen;
	394
	395	/* Look up to see if we're just after a \n. */
	396	if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
	397	/* Now if this ends in \n, update ftp info. */
0d53778e PM	398	pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
	399	ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
	400	ct_ftp_info->seq_aft_nl[dir][0],
	401	ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
	402	ct_ftp_info->seq_aft_nl[dir][1]);
9fb9cbb1 YK	403	ret = NF_ACCEPT;
	404	goto out_update_nl;
	405	}
	406
601e68e1 YH	407	/* Initialize IP/IPv6 addr to expected address (it's not mentioned
601e68e1 YH	408	in EPSV responses) */
5e8fbe2a	409	cmd.l3num = nf_ct_l3num(ct);
9fb9cbb1 YK	410	memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	411	sizeof(cmd.u3.all));
	412
7d8c5018	413	for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
9fb9cbb1	414	found = find_pattern(fb_ptr, datalen,
7d8c5018 PM	415	search[dir][i].pattern,
	416	search[dir][i].plen,
	417	search[dir][i].skip,
	418	search[dir][i].term,
9fb9cbb1 YK	419	&matchoff, &matchlen,
9fb9cbb1 YK	420	&cmd,
7d8c5018	421	search[dir][i].getnum);
9fb9cbb1 YK	422	if (found) break;
	423	}
	424	if (found == -1) {
	425	/* We don't usually drop packets. After all, this is
	426	connection tracking, not packet filtering.
	427	However, it is necessary for accurate tracking in
	428	this case. */
4813eadf PM	429	pr_debug("conntrack_ftp: partial %s %u+%u\n",
4813eadf PM	430	search[dir][i].pattern, ntohl(th->seq), datalen);
9fb9cbb1 YK	431	ret = NF_DROP;
	432	goto out;
	433	} else if (found == 0) { /* No match */
	434	ret = NF_ACCEPT;
	435	goto out_update_nl;
	436	}
	437
0d53778e PM	438	pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
	439	matchlen, fb_ptr + matchoff,
	440	matchlen, ntohl(th->seq) + matchoff);
9fb9cbb1	441
6823645d	442	exp = nf_ct_expect_alloc(ct);
9fb9cbb1 YK	443	if (exp == NULL) {
	444	ret = NF_DROP;
	445	goto out;
	446	}
	447
	448	/* We refer to the reverse direction ("!dir") tuples here,
	449	* because we're expecting something in the other direction.
	450	* Doesn't matter unless NAT is happening. */
df43b4e7	451	daddr = &ct->tuplehash[!dir].tuple.dst.u3;
9fb9cbb1 YK	452
9fb9cbb1 YK	453	/* Update the ftp info */
5e8fbe2a	454	if ((cmd.l3num == nf_ct_l3num(ct)) &&
9fb9cbb1 YK	455	memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	456	sizeof(cmd.u3.all))) {
	457	/* Enrico Scholz's passive FTP to partially RNAT'd ftp
601e68e1 YH	458	server: it really wants us to connect to a
	459	different IP address. Simply don't record it for
	460	NAT. */
9fb9cbb1	461	if (cmd.l3num == PF_INET) {
14d5e834 HH	462	pr_debug("conntrack_ftp: NOT RECORDING: %pI4 != %pI4\n",
	463	&cmd.u3.ip,
	464	&ct->tuplehash[dir].tuple.src.u3.ip);
9fb9cbb1	465	} else {
5b095d98	466	pr_debug("conntrack_ftp: NOT RECORDING: %pI6 != %pI6\n",
38ff4fa4 HH	467	cmd.u3.ip6,
38ff4fa4 HH	468	ct->tuplehash[dir].tuple.src.u3.ip6);
9fb9cbb1 YK	469	}
	470
	471	/* Thanks to Cristiano Lincoln Mattos
	472	<lincoln@cesar.org.br> for reporting this potential
	473	problem (DMZ machines opening holes to internal
	474	networks, or the packet filter itself). */
	475	if (!loose) {
	476	ret = NF_ACCEPT;
	477	goto out_put_expect;
	478	}
df43b4e7	479	daddr = &cmd.u3;
9fb9cbb1 YK	480	}
9fb9cbb1 YK	481
6002f266	482	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num,
df43b4e7 PM	483	&ct->tuplehash[!dir].tuple.src.u3, daddr,
df43b4e7 PM	484	IPPROTO_TCP, NULL, &cmd.u.tcp.port);
9fb9cbb1 YK	485
	486	/* Now, NAT might want to mangle the packet, and register the
	487	* (possibly changed) expectation itself. */
337fbc41	488	nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
55a73324	489	if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
3db05fea	490	ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype,
25b86e05	491	matchoff, matchlen, exp);
9fb9cbb1 YK	492	else {
9fb9cbb1 YK	493	/* Can't expect this? Best to drop packet now. */
6823645d	494	if (nf_ct_expect_related(exp) != 0)
9fb9cbb1 YK	495	ret = NF_DROP;
	496	else
	497	ret = NF_ACCEPT;
	498	}
	499
	500	out_put_expect:
6823645d	501	nf_ct_expect_put(exp);
9fb9cbb1 YK	502
	503	out_update_nl:
	504	/* Now if this ends in \n, update ftp info. Seq may have been
	505	* adjusted by NAT code. */
	506	if (ends_in_nl)
a71996fc	507	update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
9fb9cbb1 YK	508	out:
	509	spin_unlock_bh(&nf_ftp_lock);
	510	return ret;
	511	}
	512
ec59a111 PM	513	static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
ec59a111 PM	514	static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")] __read_mostly;
9fb9cbb1	515
6002f266 PM	516	static const struct nf_conntrack_expect_policy ftp_exp_policy = {
	517	.max_expected = 1,
	518	.timeout = 5 * 60,
	519	};
	520
9fb9cbb1	521	/* don't make this __exit, since it's called from __init ! */
65b4b4e8	522	static void nf_conntrack_ftp_fini(void)
9fb9cbb1 YK	523	{
	524	int i, j;
	525	for (i = 0; i < ports_c; i++) {
	526	for (j = 0; j < 2; j++) {
	527	if (ftp[i][j].me == NULL)
	528	continue;
	529
0d53778e PM	530	pr_debug("nf_ct_ftp: unregistering helper for pf: %d "
	531	"port: %d\n",
	532	ftp[i][j].tuple.src.l3num, ports[i]);
9fb9cbb1 YK	533	nf_conntrack_helper_unregister(&ftp[i][j]);
	534	}
	535	}
	536
	537	kfree(ftp_buffer);
	538	}
	539
65b4b4e8	540	static int __init nf_conntrack_ftp_init(void)
9fb9cbb1 YK	541	{
	542	int i, j = -1, ret = 0;
	543	char *tmpname;
	544
	545	ftp_buffer = kmalloc(65536, GFP_KERNEL);
	546	if (!ftp_buffer)
	547	return -ENOMEM;
	548
	549	if (ports_c == 0)
	550	ports[ports_c++] = FTP_PORT;
	551
	552	/* FIXME should be configurable whether IPv4 and IPv6 FTP connections
	553	are tracked or not - YK */
	554	for (i = 0; i < ports_c; i++) {
9fb9cbb1 YK	555	ftp[i][0].tuple.src.l3num = PF_INET;
	556	ftp[i][1].tuple.src.l3num = PF_INET6;
	557	for (j = 0; j < 2; j++) {
	558	ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	559	ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
6002f266	560	ftp[i][j].expect_policy = &ftp_exp_policy;
9fb9cbb1 YK	561	ftp[i][j].me = THIS_MODULE;
	562	ftp[i][j].help = help;
	563	tmpname = &ftp_names[i][j][0];
	564	if (ports[i] == FTP_PORT)
	565	sprintf(tmpname, "ftp");
	566	else
	567	sprintf(tmpname, "ftp-%d", ports[i]);
	568	ftp[i][j].name = tmpname;
	569
0d53778e PM	570	pr_debug("nf_ct_ftp: registering helper for pf: %d "
	571	"port: %d\n",
	572	ftp[i][j].tuple.src.l3num, ports[i]);
9fb9cbb1 YK	573	ret = nf_conntrack_helper_register(&ftp[i][j]);
	574	if (ret) {
	575	printk("nf_ct_ftp: failed to register helper "
	576	" for pf: %d port: %d\n",
	577	ftp[i][j].tuple.src.l3num, ports[i]);
65b4b4e8	578	nf_conntrack_ftp_fini();
9fb9cbb1 YK	579	return ret;
	580	}
	581	}
	582	}
	583
	584	return 0;
	585	}
	586
65b4b4e8 AM	587	module_init(nf_conntrack_ftp_init);
65b4b4e8 AM	588	module_exit(nf_conntrack_ftp_fini);