[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/slab.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>
5a0e3ad6	16	#include <linux/slab.h>
9fb9cbb1 YK	17	#include <linux/ipv6.h>
9fb9cbb1 YK	18	#include <linux/ctype.h>
6a28ec8c	19	#include <linux/inet.h>
9fb9cbb1 YK	20	#include <net/checksum.h>
	21	#include <net/tcp.h>
	22
	23	#include <net/netfilter/nf_conntrack.h>
77ab9cff	24	#include <net/netfilter/nf_conntrack_expect.h>
f6180121	25	#include <net/netfilter/nf_conntrack_ecache.h>
9fb9cbb1 YK	26	#include <net/netfilter/nf_conntrack_helper.h>
	27	#include <linux/netfilter/nf_conntrack_ftp.h>
	28
	29	MODULE_LICENSE("GPL");
	30	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
	31	MODULE_DESCRIPTION("ftp connection tracking helper");
d2483dde	32	MODULE_ALIAS("ip_conntrack_ftp");
4dc06f96	33	MODULE_ALIAS_NFCT_HELPER("ftp");
9fb9cbb1 YK	34
	35	/* This is slow, but it's simple. --RR */
	36	static char *ftp_buffer;
	37
	38	static DEFINE_SPINLOCK(nf_ftp_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
	45	static int loose;
e7be6994	46	module_param(loose, bool, 0600);
9fb9cbb1	47
3db05fea	48	unsigned int (nf_nat_ftp_hook)(struct sk_buff skb,
9fb9cbb1	49	enum ip_conntrack_info ctinfo,
55a73324	50	enum nf_ct_ftp_type type,
9fb9cbb1 YK	51	unsigned int matchoff,
9fb9cbb1 YK	52	unsigned int matchlen,
25b86e05	53	struct nf_conntrack_expect *exp);
9fb9cbb1 YK	54	EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
9fb9cbb1 YK	55
9fb9cbb1 YK	56	static int try_rfc959(const char , size_t, struct nf_conntrack_man , char);
	57	static int try_eprt(const char , size_t, struct nf_conntrack_man , char);
	58	static int try_epsv_response(const char , size_t, struct nf_conntrack_man ,
	59	char);
	60
	61	static struct ftp_search {
9fb9cbb1 YK	62	const char *pattern;
	63	size_t plen;
	64	char skip;
	65	char term;
55a73324	66	enum nf_ct_ftp_type ftptype;
9fb9cbb1	67	int (getnum)(const char , size_t, struct nf_conntrack_man *, char);
7d8c5018 PM	68	} search[IP_CT_DIR_MAX][2] = {
	69	[IP_CT_DIR_ORIGINAL] = {
	70	{
	71	.pattern = "PORT",
	72	.plen = sizeof("PORT") - 1,
	73	.skip = ' ',
	74	.term = '\r',
55a73324	75	.ftptype = NF_CT_FTP_PORT,
7d8c5018 PM	76	.getnum = try_rfc959,
	77	},
	78	{
	79	.pattern = "EPRT",
	80	.plen = sizeof("EPRT") - 1,
	81	.skip = ' ',
	82	.term = '\r',
55a73324	83	.ftptype = NF_CT_FTP_EPRT,
7d8c5018 PM	84	.getnum = try_eprt,
7d8c5018 PM	85	},
9fb9cbb1	86	},
7d8c5018 PM	87	[IP_CT_DIR_REPLY] = {
	88	{
	89	.pattern = "227 ",
	90	.plen = sizeof("227 ") - 1,
	91	.skip = '(',
	92	.term = ')',
55a73324	93	.ftptype = NF_CT_FTP_PASV,
7d8c5018 PM	94	.getnum = try_rfc959,
	95	},
	96	{
	97	.pattern = "229 ",
	98	.plen = sizeof("229 ") - 1,
	99	.skip = '(',
	100	.term = ')',
55a73324	101	.ftptype = NF_CT_FTP_EPSV,
7d8c5018 PM	102	.getnum = try_epsv_response,
7d8c5018 PM	103	},
9fb9cbb1 YK	104	},
	105	};
	106
9fb9cbb1 YK	107	static int
	108	get_ipv6_addr(const char src, size_t dlen, struct in6_addr dst, u_int8_t term)
	109	{
6a28ec8c DM	110	const char *end;
6a28ec8c DM	111	int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), (u8 *)dst, term, &end);
1884f78c YH	112	if (ret > 0)
	113	return (int)(end - src);
	114	return 0;
9fb9cbb1 YK	115	}
	116
	117	static int try_number(const char *data, size_t dlen, u_int32_t array[],
601e68e1	118	int array_size, char sep, char term)
9fb9cbb1 YK	119	{
	120	u_int32_t i, len;
	121
	122	memset(array, 0, sizeof(array[0])*array_size);
	123
	124	/* Keep data pointing at next char. */
	125	for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
	126	if (data >= '0' && data <= '9') {
	127	array[i] = array[i]10 + data - '0';
	128	}
	129	else if (*data == sep)
	130	i++;
	131	else {
	132	/* Unexpected character; true if it's the
	133	terminator and we're finished. */
	134	if (*data == term && i == array_size - 1)
	135	return len;
	136
0d53778e PM	137	pr_debug("Char %u (got %u nums) `%u' unexpected\n",
0d53778e PM	138	len, i, *data);
9fb9cbb1 YK	139	return 0;
	140	}
	141	}
0d53778e PM	142	pr_debug("Failed to fill %u numbers separated by %c\n",
0d53778e PM	143	array_size, sep);
9fb9cbb1 YK	144	return 0;
	145	}
	146
	147	/* Returns 0, or length of numbers: 192,168,1,1,5,6 */
	148	static int try_rfc959(const char *data, size_t dlen,
	149	struct nf_conntrack_man *cmd, char term)
	150	{
	151	int length;
	152	u_int32_t array[6];
	153
	154	length = try_number(data, dlen, array, 6, ',', term);
	155	if (length == 0)
	156	return 0;
	157
	158	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16) \|
	159	(array[2] << 8) \| array[3]);
	160	cmd->u.tcp.port = htons((array[4] << 8) \| array[5]);
	161	return length;
	162	}
	163
	164	/* Grab port: number up to delimiter */
	165	static int get_port(const char *data, int start, size_t dlen, char delim,
bff9a89b	166	__be16 *port)
9fb9cbb1 YK	167	{
	168	u_int16_t tmp_port = 0;
	169	int i;
	170
	171	for (i = start; i < dlen; i++) {
	172	/* Finished? */
	173	if (data[i] == delim) {
	174	if (tmp_port == 0)
	175	break;
	176	*port = htons(tmp_port);
0d53778e	177	pr_debug("get_port: return %d\n", tmp_port);
9fb9cbb1 YK	178	return i + 1;
	179	}
	180	else if (data[i] >= '0' && data[i] <= '9')
	181	tmp_port = tmp_port*10 + data[i] - '0';
	182	else { /* Some other crap */
0d53778e	183	pr_debug("get_port: invalid char.\n");
9fb9cbb1 YK	184	break;
	185	}
	186	}
	187	return 0;
	188	}
	189
	190	/* Returns 0, or length of numbers: \|1\|132.235.1.2\|6275\| or \|2\|3ffe::1\|6275\| */
	191	static int try_eprt(const char data, size_t dlen, struct nf_conntrack_man cmd,
	192	char term)
	193	{
	194	char delim;
	195	int length;
	196
	197	/* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
	198	then delimiter again. */
	199	if (dlen <= 3) {
0d53778e	200	pr_debug("EPRT: too short\n");
9fb9cbb1 YK	201	return 0;
	202	}
	203	delim = data[0];
	204	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126 \|\| data[2] != delim) {
0d53778e	205	pr_debug("try_eprt: invalid delimitter.\n");
9fb9cbb1 YK	206	return 0;
	207	}
	208
	209	if ((cmd->l3num == PF_INET && data[1] != '1') \|\|
	210	(cmd->l3num == PF_INET6 && data[1] != '2')) {
0d53778e	211	pr_debug("EPRT: invalid protocol number.\n");
9fb9cbb1 YK	212	return 0;
	213	}
	214
0d53778e	215	pr_debug("EPRT: Got %c%c%c\n", delim, data[1], delim);
9fb9cbb1 YK	216
	217	if (data[1] == '1') {
	218	u_int32_t array[4];
	219
	220	/* Now we have IP address. */
	221	length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
	222	if (length != 0)
	223	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16)
	224	\| (array[2] << 8) \| array[3]);
	225	} else {
	226	/* Now we have IPv6 address. */
	227	length = get_ipv6_addr(data + 3, dlen - 3,
	228	(struct in6_addr *)cmd->u3.ip6, delim);
	229	}
	230
	231	if (length == 0)
	232	return 0;
0d53778e	233	pr_debug("EPRT: Got IP address!\n");
9fb9cbb1 YK	234	/* Start offset includes initial "\|1\|", and trailing delimiter */
	235	return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
	236	}
	237
	238	/* Returns 0, or length of numbers: \|\|\|6446\| */
	239	static int try_epsv_response(const char *data, size_t dlen,
	240	struct nf_conntrack_man *cmd, char term)
	241	{
	242	char delim;
	243
	244	/* Three delimiters. */
	245	if (dlen <= 3) return 0;
	246	delim = data[0];
f64f9e71 JP	247	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126 \|\|
f64f9e71 JP	248	data[1] != delim \|\| data[2] != delim)
9fb9cbb1 YK	249	return 0;
	250
	251	return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
	252	}
	253
	254	/* Return 1 for match, 0 for accept, -1 for partial. */
	255	static int find_pattern(const char *data, size_t dlen,
	256	const char *pattern, size_t plen,
	257	char skip, char term,
	258	unsigned int *numoff,
	259	unsigned int *numlen,
	260	struct nf_conntrack_man *cmd,
	261	int (getnum)(const char , size_t,
	262	struct nf_conntrack_man *, char))
	263	{
	264	size_t i;
	265
0d53778e	266	pr_debug("find_pattern `%s': dlen = %Zu\n", pattern, dlen);
9fb9cbb1 YK	267	if (dlen == 0)
	268	return 0;
	269
	270	if (dlen <= plen) {
	271	/* Short packet: try for partial? */
	272	if (strnicmp(data, pattern, dlen) == 0)
	273	return -1;
	274	else return 0;
	275	}
	276
	277	if (strnicmp(data, pattern, plen) != 0) {
	278	#if 0
	279	size_t i;
	280
0d53778e	281	pr_debug("ftp: string mismatch\n");
9fb9cbb1	282	for (i = 0; i < plen; i++) {
0d53778e PM	283	pr_debug("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
	284	i, data[i], data[i],
	285	pattern[i], pattern[i]);
9fb9cbb1 YK	286	}
	287	#endif
	288	return 0;
	289	}
	290
0d53778e	291	pr_debug("Pattern matches!\n");
9fb9cbb1 YK	292	/* Now we've found the constant string, try to skip
	293	to the 'skip' character */
	294	for (i = plen; data[i] != skip; i++)
	295	if (i == dlen - 1) return -1;
	296
	297	/* Skip over the last character */
	298	i++;
	299
0d53778e	300	pr_debug("Skipped up to `%c'!\n", skip);
9fb9cbb1 YK	301
	302	*numoff = i;
	303	*numlen = getnum(data + i, dlen - i, cmd, term);
	304	if (!*numlen)
	305	return -1;
	306
0d53778e	307	pr_debug("Match succeeded!\n");
9fb9cbb1 YK	308	return 1;
	309	}
	310
	311	/* Look up to see if we're just after a \n. */
55a73324	312	static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
9fb9cbb1 YK	313	{
	314	unsigned int i;
	315
	316	for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
	317	if (info->seq_aft_nl[dir][i] == seq)
	318	return 1;
	319	return 0;
	320	}
	321
	322	/* We don't update if it's older than what we have. */
a71996fc AD	323	static void update_nl_seq(struct nf_conn *ct, u32 nl_seq,
a71996fc AD	324	struct nf_ct_ftp_master *info, int dir,
9fb9cbb1 YK	325	struct sk_buff *skb)
9fb9cbb1 YK	326	{
aaff23a9	327	unsigned int i, oldest;
9fb9cbb1 YK	328
	329	/* Look for oldest: if we find exact match, we're done. */
	330	for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
	331	if (info->seq_aft_nl[dir][i] == nl_seq)
	332	return;
9fb9cbb1 YK	333	}
	334
	335	if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
	336	info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
aaff23a9 PM	337	} else {
	338	if (before(info->seq_aft_nl[dir][0], info->seq_aft_nl[dir][1]))
	339	oldest = 0;
	340	else
	341	oldest = 1;
	342
	343	if (after(nl_seq, info->seq_aft_nl[dir][oldest]))
	344	info->seq_aft_nl[dir][oldest] = nl_seq;
9fb9cbb1 YK	345	}
	346	}
	347
3db05fea	348	static int help(struct sk_buff *skb,
9fb9cbb1 YK	349	unsigned int protoff,
	350	struct nf_conn *ct,
	351	enum ip_conntrack_info ctinfo)
	352	{
	353	unsigned int dataoff, datalen;
58c0fb0d JE	354	const struct tcphdr *th;
	355	struct tcphdr _tcph;
	356	const char *fb_ptr;
9fb9cbb1 YK	357	int ret;
	358	u32 seq;
	359	int dir = CTINFO2DIR(ctinfo);
d6e8cc6c	360	unsigned int uninitialized_var(matchlen), uninitialized_var(matchoff);
55a73324	361	struct nf_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
9fb9cbb1	362	struct nf_conntrack_expect *exp;
643a2c15	363	union nf_inet_addr *daddr;
9fb9cbb1	364	struct nf_conntrack_man cmd = {};
9fb9cbb1 YK	365	unsigned int i;
9fb9cbb1 YK	366	int found = 0, ends_in_nl;
337fbc41	367	typeof(nf_nat_ftp_hook) nf_nat_ftp;
9fb9cbb1 YK	368
9fb9cbb1 YK	369	/* Until there's been traffic both ways, don't look in packets. */
f64f9e71 JP	370	if (ctinfo != IP_CT_ESTABLISHED &&
f64f9e71 JP	371	ctinfo != IP_CT_ESTABLISHED + IP_CT_IS_REPLY) {
0d53778e	372	pr_debug("ftp: Conntrackinfo = %u\n", ctinfo);
9fb9cbb1 YK	373	return NF_ACCEPT;
	374	}
	375
3db05fea	376	th = skb_header_pointer(skb, protoff, sizeof(_tcph), &_tcph);
9fb9cbb1 YK	377	if (th == NULL)
	378	return NF_ACCEPT;
	379
	380	dataoff = protoff + th->doff * 4;
	381	/* No data? */
3db05fea	382	if (dataoff >= skb->len) {
0d53778e	383	pr_debug("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
3db05fea	384	skb->len);
9fb9cbb1 YK	385	return NF_ACCEPT;
9fb9cbb1 YK	386	}
3db05fea	387	datalen = skb->len - dataoff;
9fb9cbb1 YK	388
9fb9cbb1 YK	389	spin_lock_bh(&nf_ftp_lock);
3db05fea	390	fb_ptr = skb_header_pointer(skb, dataoff, datalen, ftp_buffer);
9fb9cbb1 YK	391	BUG_ON(fb_ptr == NULL);
	392
	393	ends_in_nl = (fb_ptr[datalen - 1] == '\n');
	394	seq = ntohl(th->seq) + datalen;
	395
	396	/* Look up to see if we're just after a \n. */
	397	if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
	398	/* Now if this ends in \n, update ftp info. */
0d53778e PM	399	pr_debug("nf_conntrack_ftp: wrong seq pos %s(%u) or %s(%u)\n",
	400	ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
	401	ct_ftp_info->seq_aft_nl[dir][0],
	402	ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
	403	ct_ftp_info->seq_aft_nl[dir][1]);
9fb9cbb1 YK	404	ret = NF_ACCEPT;
	405	goto out_update_nl;
	406	}
	407
601e68e1 YH	408	/* Initialize IP/IPv6 addr to expected address (it's not mentioned
601e68e1 YH	409	in EPSV responses) */
5e8fbe2a	410	cmd.l3num = nf_ct_l3num(ct);
9fb9cbb1 YK	411	memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	412	sizeof(cmd.u3.all));
	413
7d8c5018	414	for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
9fb9cbb1	415	found = find_pattern(fb_ptr, datalen,
7d8c5018 PM	416	search[dir][i].pattern,
	417	search[dir][i].plen,
	418	search[dir][i].skip,
	419	search[dir][i].term,
9fb9cbb1 YK	420	&matchoff, &matchlen,
9fb9cbb1 YK	421	&cmd,
7d8c5018	422	search[dir][i].getnum);
9fb9cbb1 YK	423	if (found) break;
	424	}
	425	if (found == -1) {
	426	/* We don't usually drop packets. After all, this is
	427	connection tracking, not packet filtering.
	428	However, it is necessary for accurate tracking in
	429	this case. */
4813eadf PM	430	pr_debug("conntrack_ftp: partial %s %u+%u\n",
4813eadf PM	431	search[dir][i].pattern, ntohl(th->seq), datalen);
9fb9cbb1 YK	432	ret = NF_DROP;
	433	goto out;
	434	} else if (found == 0) { /* No match */
	435	ret = NF_ACCEPT;
	436	goto out_update_nl;
	437	}
	438
0d53778e PM	439	pr_debug("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
	440	matchlen, fb_ptr + matchoff,
	441	matchlen, ntohl(th->seq) + matchoff);
9fb9cbb1	442
6823645d	443	exp = nf_ct_expect_alloc(ct);
9fb9cbb1 YK	444	if (exp == NULL) {
	445	ret = NF_DROP;
	446	goto out;
	447	}
	448
	449	/* We refer to the reverse direction ("!dir") tuples here,
	450	* because we're expecting something in the other direction.
	451	* Doesn't matter unless NAT is happening. */
df43b4e7	452	daddr = &ct->tuplehash[!dir].tuple.dst.u3;
9fb9cbb1 YK	453
9fb9cbb1 YK	454	/* Update the ftp info */
5e8fbe2a	455	if ((cmd.l3num == nf_ct_l3num(ct)) &&
9fb9cbb1 YK	456	memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	457	sizeof(cmd.u3.all))) {
	458	/* Enrico Scholz's passive FTP to partially RNAT'd ftp
601e68e1 YH	459	server: it really wants us to connect to a
	460	different IP address. Simply don't record it for
	461	NAT. */
9fb9cbb1	462	if (cmd.l3num == PF_INET) {
14d5e834 HH	463	pr_debug("conntrack_ftp: NOT RECORDING: %pI4 != %pI4\n",
	464	&cmd.u3.ip,
	465	&ct->tuplehash[dir].tuple.src.u3.ip);
9fb9cbb1	466	} else {
5b095d98	467	pr_debug("conntrack_ftp: NOT RECORDING: %pI6 != %pI6\n",
38ff4fa4 HH	468	cmd.u3.ip6,
38ff4fa4 HH	469	ct->tuplehash[dir].tuple.src.u3.ip6);
9fb9cbb1 YK	470	}
	471
	472	/* Thanks to Cristiano Lincoln Mattos
	473	<lincoln@cesar.org.br> for reporting this potential
	474	problem (DMZ machines opening holes to internal
	475	networks, or the packet filter itself). */
	476	if (!loose) {
	477	ret = NF_ACCEPT;
	478	goto out_put_expect;
	479	}
df43b4e7	480	daddr = &cmd.u3;
9fb9cbb1 YK	481	}
9fb9cbb1 YK	482
6002f266	483	nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, cmd.l3num,
df43b4e7 PM	484	&ct->tuplehash[!dir].tuple.src.u3, daddr,
df43b4e7 PM	485	IPPROTO_TCP, NULL, &cmd.u.tcp.port);
9fb9cbb1 YK	486
	487	/* Now, NAT might want to mangle the packet, and register the
	488	* (possibly changed) expectation itself. */
337fbc41	489	nf_nat_ftp = rcu_dereference(nf_nat_ftp_hook);
55a73324	490	if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
3db05fea	491	ret = nf_nat_ftp(skb, ctinfo, search[dir][i].ftptype,
25b86e05	492	matchoff, matchlen, exp);
9fb9cbb1 YK	493	else {
9fb9cbb1 YK	494	/* Can't expect this? Best to drop packet now. */
6823645d	495	if (nf_ct_expect_related(exp) != 0)
9fb9cbb1 YK	496	ret = NF_DROP;
	497	else
	498	ret = NF_ACCEPT;
	499	}
	500
	501	out_put_expect:
6823645d	502	nf_ct_expect_put(exp);
9fb9cbb1 YK	503
	504	out_update_nl:
	505	/* Now if this ends in \n, update ftp info. Seq may have been
	506	* adjusted by NAT code. */
	507	if (ends_in_nl)
a71996fc	508	update_nl_seq(ct, seq, ct_ftp_info, dir, skb);
9fb9cbb1 YK	509	out:
	510	spin_unlock_bh(&nf_ftp_lock);
	511	return ret;
	512	}
	513
ec59a111 PM	514	static struct nf_conntrack_helper ftp[MAX_PORTS][2] __read_mostly;
ec59a111 PM	515	static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")] __read_mostly;
9fb9cbb1	516
6002f266 PM	517	static const struct nf_conntrack_expect_policy ftp_exp_policy = {
	518	.max_expected = 1,
	519	.timeout = 5 * 60,
	520	};
	521
9fb9cbb1	522	/* don't make this __exit, since it's called from __init ! */
65b4b4e8	523	static void nf_conntrack_ftp_fini(void)
9fb9cbb1 YK	524	{
	525	int i, j;
	526	for (i = 0; i < ports_c; i++) {
	527	for (j = 0; j < 2; j++) {
	528	if (ftp[i][j].me == NULL)
	529	continue;
	530
0d53778e PM	531	pr_debug("nf_ct_ftp: unregistering helper for pf: %d "
	532	"port: %d\n",
	533	ftp[i][j].tuple.src.l3num, ports[i]);
9fb9cbb1 YK	534	nf_conntrack_helper_unregister(&ftp[i][j]);
	535	}
	536	}
	537
	538	kfree(ftp_buffer);
	539	}
	540
65b4b4e8	541	static int __init nf_conntrack_ftp_init(void)
9fb9cbb1 YK	542	{
	543	int i, j = -1, ret = 0;
	544	char *tmpname;
	545
	546	ftp_buffer = kmalloc(65536, GFP_KERNEL);
	547	if (!ftp_buffer)
	548	return -ENOMEM;
	549
	550	if (ports_c == 0)
	551	ports[ports_c++] = FTP_PORT;
	552
	553	/* FIXME should be configurable whether IPv4 and IPv6 FTP connections
	554	are tracked or not - YK */
	555	for (i = 0; i < ports_c; i++) {
9fb9cbb1 YK	556	ftp[i][0].tuple.src.l3num = PF_INET;
	557	ftp[i][1].tuple.src.l3num = PF_INET6;
	558	for (j = 0; j < 2; j++) {
	559	ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	560	ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
6002f266	561	ftp[i][j].expect_policy = &ftp_exp_policy;
9fb9cbb1 YK	562	ftp[i][j].me = THIS_MODULE;
	563	ftp[i][j].help = help;
	564	tmpname = &ftp_names[i][j][0];
	565	if (ports[i] == FTP_PORT)
	566	sprintf(tmpname, "ftp");
	567	else
	568	sprintf(tmpname, "ftp-%d", ports[i]);
	569	ftp[i][j].name = tmpname;
	570
0d53778e PM	571	pr_debug("nf_ct_ftp: registering helper for pf: %d "
	572	"port: %d\n",
	573	ftp[i][j].tuple.src.l3num, ports[i]);
9fb9cbb1 YK	574	ret = nf_conntrack_helper_register(&ftp[i][j]);
	575	if (ret) {
	576	printk("nf_ct_ftp: failed to register helper "
	577	" for pf: %d port: %d\n",
	578	ftp[i][j].tuple.src.l3num, ports[i]);
65b4b4e8	579	nf_conntrack_ftp_fini();
9fb9cbb1 YK	580	return ret;
	581	}
	582	}
	583	}
	584
	585	return 0;
	586	}
	587
65b4b4e8 AM	588	module_init(nf_conntrack_ftp_init);
65b4b4e8 AM	589	module_exit(nf_conntrack_ftp_fini);