[GitHub/mt8127/android_kernel_alcatel_ttab.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.
 *
 * 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
 *	- enable working with Layer 3 protocol independent connection tracking.
 *	- track EPRT and EPSV commands with IPv6 address.
 *
 * Derived from net/ipv4/netfilter/ip_conntrack_ftp.c
 */

#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 <net/checksum.h>
#include <net/tcp.h>

#include <net/netfilter/nf_conntrack.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");

/* 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 **pskb,
				enum ip_conntrack_info ctinfo,
				enum ip_ct_ftp_type type,
				unsigned int matchoff,
				unsigned int matchlen,
				struct nf_conntrack_expect *exp,
				u32 *seq);
EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);

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

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 ip_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	= IP_CT_FTP_PORT,
			.getnum		= try_rfc959,
		},
		{
			.pattern	= "EPRT",
			.plen		= sizeof("EPRT") - 1,
			.skip		= ' ',
			.term		= '\r',
			.ftptype	= IP_CT_FTP_EPRT,
			.getnum		= try_eprt,
		},
	},
	[IP_CT_DIR_REPLY] = {
		{
			.pattern	= "227 ",
			.plen		= sizeof("227 ") - 1,
			.skip		= '(',
			.term		= ')',
			.ftptype	= IP_CT_FTP_PASV,
			.getnum		= try_rfc959,
		},
		{
			.pattern	= "229 ",
			.plen		= sizeof("229 ") - 1,
			.skip		= '(',
			.term		= ')',
			.ftptype	= IP_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)
{
	int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), 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;

			DEBUGP("Char %u (got %u nums) `%u' unexpected\n",
			       len, i, *data);
			return 0;
		}
	}
	DEBUGP("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,
		    u_int16_t *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);
			DEBUGP("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 */
			DEBUGP("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) {
		DEBUGP("EPRT: too short\n");
		return 0;
	}
	delim = data[0];
	if (isdigit(delim) || delim < 33 || delim > 126 || data[2] != delim) {
		DEBUGP("try_eprt: invalid delimitter.\n");
		return 0;
	}

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

	DEBUGP("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;
	DEBUGP("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;

	DEBUGP("find_pattern `%s': dlen = %u\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;

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

	DEBUGP("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++;

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

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

	DEBUGP("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 ip_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(u32 nl_seq, struct ip_ct_ftp_master *info, int dir,
			  struct sk_buff *skb)
{
	unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;

	/* 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 (oldest == info->seq_aft_nl_num[dir]
		    || before(info->seq_aft_nl[dir][i], oldest))
			oldest = i;
	}

	if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
		info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
		nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
	} else if (oldest != NUM_SEQ_TO_REMEMBER) {
		info->seq_aft_nl[dir][oldest] = nl_seq;
		nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
	}
}

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 *fb_ptr;
	int ret;
	u32 seq;
	int dir = CTINFO2DIR(ctinfo);
	unsigned int matchlen, matchoff;
	struct ip_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
	struct nf_conntrack_expect *exp;
	struct nf_conntrack_man cmd = {};

	unsigned int i;
	int found = 0, ends_in_nl;

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

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

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

	spin_lock_bh(&nf_ftp_lock);
	fb_ptr = skb_header_pointer(*pskb, 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. */
		DEBUGP("nf_conntrack_ftp_help: 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 = ct->tuplehash[dir].tuple.src.l3num;
	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. */
		if (net_ratelimit())
			printk("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;
	}

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

	exp = nf_conntrack_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.  */
	exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3;

	/* Update the ftp info */
	if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) &&
	    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) {
                	DEBUGP("conntrack_ftp: NOT RECORDING: " NIPQUAD_FMT " != " NIPQUAD_FMT "\n",
			       NIPQUAD(cmd.u3.ip),
			       NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip));
		} else {
			DEBUGP("conntrack_ftp: NOT RECORDING: " NIP6_FMT " != " NIP6_FMT "\n",
			       NIP6(*((struct in6_addr *)cmd.u3.ip6)),
			       NIP6(*((struct in6_addr *)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;
		}
		memcpy(&exp->tuple.dst.u3, &cmd.u3.all,
		       sizeof(exp->tuple.dst.u3));
	}

	exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3;
	exp->tuple.src.l3num = cmd.l3num;
	exp->tuple.src.u.tcp.port = 0;
	exp->tuple.dst.u.tcp.port = cmd.u.tcp.port;
	exp->tuple.dst.protonum = IPPROTO_TCP;

	exp->mask = (struct nf_conntrack_tuple)
		    { .src = { .l3num = 0xFFFF,
			       .u = { .tcp = { 0 }},
			     },
		      .dst = { .protonum = 0xFF,
			       .u = { .tcp = { 0xFFFF }},
			     },
		    };
	if (cmd.l3num == PF_INET) {
		exp->mask.src.u3.ip = 0xFFFFFFFF;
		exp->mask.dst.u3.ip = 0xFFFFFFFF;
	} else {
		memset(exp->mask.src.u3.ip6, 0xFF,
		       sizeof(exp->mask.src.u3.ip6));
		memset(exp->mask.dst.u3.ip6, 0xFF,
		       sizeof(exp->mask.src.u3.ip6));
	}

	exp->expectfn = NULL;
	exp->flags = 0;

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

out_put_expect:
	nf_conntrack_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(seq, ct_ftp_info, dir, *pskb);
 out:
	spin_unlock_bh(&nf_ftp_lock);
	return ret;
}

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

/* 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;

			DEBUGP("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].mask.src.u.tcp.port = 0xFFFF;
			ftp[i][j].mask.dst.protonum = 0xFF;
			ftp[i][j].max_expected = 1;
			ftp[i][j].timeout = 5 * 60;	/* 5 Minutes */
			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;

			DEBUGP("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.
	10	*
	11	* 16 Dec 2003: Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
	12	* - enable working with Layer 3 protocol independent connection tracking.
	13	* - track EPRT and EPSV commands with IPv6 address.
	14	*
	15	* Derived from net/ipv4/netfilter/ip_conntrack_ftp.c
	16	*/
	17
9fb9cbb1 YK	18	#include <linux/module.h>
	19	#include <linux/moduleparam.h>
	20	#include <linux/netfilter.h>
	21	#include <linux/ip.h>
	22	#include <linux/ipv6.h>
	23	#include <linux/ctype.h>
	24	#include <net/checksum.h>
	25	#include <net/tcp.h>
	26
	27	#include <net/netfilter/nf_conntrack.h>
	28	#include <net/netfilter/nf_conntrack_helper.h>
	29	#include <linux/netfilter/nf_conntrack_ftp.h>
	30
	31	MODULE_LICENSE("GPL");
	32	MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
	33	MODULE_DESCRIPTION("ftp connection tracking helper");
	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 YK	47
	48	unsigned int (nf_nat_ftp_hook)(struct sk_buff *pskb,
	49	enum ip_conntrack_info ctinfo,
	50	enum ip_ct_ftp_type type,
	51	unsigned int matchoff,
	52	unsigned int matchlen,
	53	struct nf_conntrack_expect *exp,
	54	u32 *seq);
	55	EXPORT_SYMBOL_GPL(nf_nat_ftp_hook);
	56
	57	#if 0
	58	#define DEBUGP printk
	59	#else
	60	#define DEBUGP(format, args...)
	61	#endif
	62
	63	static int try_rfc959(const char , size_t, struct nf_conntrack_man , char);
	64	static int try_eprt(const char , size_t, struct nf_conntrack_man , char);
	65	static int try_epsv_response(const char , size_t, struct nf_conntrack_man ,
	66	char);
	67
	68	static struct ftp_search {
9fb9cbb1 YK	69	const char *pattern;
	70	size_t plen;
	71	char skip;
	72	char term;
	73	enum ip_ct_ftp_type ftptype;
	74	int (getnum)(const char , size_t, struct nf_conntrack_man *, char);
7d8c5018 PM	75	} search[IP_CT_DIR_MAX][2] = {
	76	[IP_CT_DIR_ORIGINAL] = {
	77	{
	78	.pattern = "PORT",
	79	.plen = sizeof("PORT") - 1,
	80	.skip = ' ',
	81	.term = '\r',
	82	.ftptype = IP_CT_FTP_PORT,
	83	.getnum = try_rfc959,
	84	},
	85	{
	86	.pattern = "EPRT",
	87	.plen = sizeof("EPRT") - 1,
	88	.skip = ' ',
	89	.term = '\r',
	90	.ftptype = IP_CT_FTP_EPRT,
	91	.getnum = try_eprt,
	92	},
9fb9cbb1	93	},
7d8c5018 PM	94	[IP_CT_DIR_REPLY] = {
	95	{
	96	.pattern = "227 ",
	97	.plen = sizeof("227 ") - 1,
	98	.skip = '(',
	99	.term = ')',
	100	.ftptype = IP_CT_FTP_PASV,
	101	.getnum = try_rfc959,
	102	},
	103	{
	104	.pattern = "229 ",
	105	.plen = sizeof("229 ") - 1,
	106	.skip = '(',
	107	.term = ')',
	108	.ftptype = IP_CT_FTP_EPSV,
	109	.getnum = try_epsv_response,
	110	},
9fb9cbb1 YK	111	},
	112	};
	113
9fb9cbb1 YK	114	static int
	115	get_ipv6_addr(const char src, size_t dlen, struct in6_addr dst, u_int8_t term)
	116	{
1884f78c YH	117	int ret = in6_pton(src, min_t(size_t, dlen, 0xffff), dst, term, &end);
	118	if (ret > 0)
	119	return (int)(end - src);
	120	return 0;
9fb9cbb1 YK	121	}
	122
	123	static int try_number(const char *data, size_t dlen, u_int32_t array[],
	124	int array_size, char sep, char term)
	125	{
	126	u_int32_t i, len;
	127
	128	memset(array, 0, sizeof(array[0])*array_size);
	129
	130	/* Keep data pointing at next char. */
	131	for (i = 0, len = 0; len < dlen && i < array_size; len++, data++) {
	132	if (data >= '0' && data <= '9') {
	133	array[i] = array[i]10 + data - '0';
	134	}
	135	else if (*data == sep)
	136	i++;
	137	else {
	138	/* Unexpected character; true if it's the
	139	terminator and we're finished. */
	140	if (*data == term && i == array_size - 1)
	141	return len;
	142
	143	DEBUGP("Char %u (got %u nums) `%u' unexpected\n",
	144	len, i, *data);
	145	return 0;
	146	}
	147	}
	148	DEBUGP("Failed to fill %u numbers separated by %c\n", array_size, sep);
	149
	150	return 0;
	151	}
	152
	153	/* Returns 0, or length of numbers: 192,168,1,1,5,6 */
	154	static int try_rfc959(const char *data, size_t dlen,
	155	struct nf_conntrack_man *cmd, char term)
	156	{
	157	int length;
	158	u_int32_t array[6];
	159
	160	length = try_number(data, dlen, array, 6, ',', term);
	161	if (length == 0)
	162	return 0;
	163
	164	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16) \|
	165	(array[2] << 8) \| array[3]);
	166	cmd->u.tcp.port = htons((array[4] << 8) \| array[5]);
	167	return length;
	168	}
	169
	170	/* Grab port: number up to delimiter */
	171	static int get_port(const char *data, int start, size_t dlen, char delim,
	172	u_int16_t *port)
	173	{
	174	u_int16_t tmp_port = 0;
	175	int i;
	176
	177	for (i = start; i < dlen; i++) {
	178	/* Finished? */
	179	if (data[i] == delim) {
	180	if (tmp_port == 0)
	181	break;
	182	*port = htons(tmp_port);
	183	DEBUGP("get_port: return %d\n", tmp_port);
	184	return i + 1;
185	}
186	else if (data[i] >= '0' && data[i] <= '9')
187	tmp_port = tmp_port*10 + data[i] - '0';
188	else { /* Some other crap */
189	DEBUGP("get_port: invalid char.\n");
190	break;
191	}
192	}
193	return 0;
194	}
195
196	/* Returns 0, or length of numbers: \|1\|132.235.1.2\|6275\| or \|2\|3ffe::1\|6275\| */
197	static int try_eprt(const char data, size_t dlen, struct nf_conntrack_man cmd,
198	char term)
199	{
200	char delim;
201	int length;
202
203	/* First character is delimiter, then "1" for IPv4 or "2" for IPv6,
204	then delimiter again. */
205	if (dlen <= 3) {
206	DEBUGP("EPRT: too short\n");
207	return 0;
208	}
209	delim = data[0];
210	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126 \|\| data[2] != delim) {
211	DEBUGP("try_eprt: invalid delimitter.\n");
212	return 0;
213	}
214
215	if ((cmd->l3num == PF_INET && data[1] != '1') \|\|
216	(cmd->l3num == PF_INET6 && data[1] != '2')) {
217	DEBUGP("EPRT: invalid protocol number.\n");
218	return 0;
219	}
220
221	DEBUGP("EPRT: Got %c%c%c\n", delim, data[1], delim);
222
223	if (data[1] == '1') {
224	u_int32_t array[4];
225
226	/* Now we have IP address. */
227	length = try_number(data + 3, dlen - 3, array, 4, '.', delim);
228	if (length != 0)
229	cmd->u3.ip = htonl((array[0] << 24) \| (array[1] << 16)
230	\| (array[2] << 8) \| array[3]);
231	} else {
232	/* Now we have IPv6 address. */
233	length = get_ipv6_addr(data + 3, dlen - 3,
234	(struct in6_addr *)cmd->u3.ip6, delim);
235	}
236
237	if (length == 0)
238	return 0;
239	DEBUGP("EPRT: Got IP address!\n");
240	/* Start offset includes initial "\|1\|", and trailing delimiter */
241	return get_port(data, 3 + length + 1, dlen, delim, &cmd->u.tcp.port);
242	}
243
244	/* Returns 0, or length of numbers: \|\|\|6446\| */
245	static int try_epsv_response(const char *data, size_t dlen,
246	struct nf_conntrack_man *cmd, char term)
247	{
248	char delim;
249
250	/* Three delimiters. */
251	if (dlen <= 3) return 0;
252	delim = data[0];
253	if (isdigit(delim) \|\| delim < 33 \|\| delim > 126
254	\|\| data[1] != delim \|\| data[2] != delim)
255	return 0;
256
257	return get_port(data, 3, dlen, delim, &cmd->u.tcp.port);
258	}
259
260	/* Return 1 for match, 0 for accept, -1 for partial. */
261	static int find_pattern(const char *data, size_t dlen,
262	const char *pattern, size_t plen,
263	char skip, char term,
264	unsigned int *numoff,
265	unsigned int *numlen,
266	struct nf_conntrack_man *cmd,
267	int (getnum)(const char , size_t,
268	struct nf_conntrack_man *, char))
269	{
270	size_t i;
271
272	DEBUGP("find_pattern `%s': dlen = %u\n", pattern, dlen);
273	if (dlen == 0)
274	return 0;
275
276	if (dlen <= plen) {
277	/* Short packet: try for partial? */
278	if (strnicmp(data, pattern, dlen) == 0)
279	return -1;
280	else return 0;
281	}
282
283	if (strnicmp(data, pattern, plen) != 0) {
284	#if 0
285	size_t i;
286
287	DEBUGP("ftp: string mismatch\n");
288	for (i = 0; i < plen; i++) {
289	DEBUGP("ftp:char %u `%c'(%u) vs `%c'(%u)\n",
290	i, data[i], data[i],
291	pattern[i], pattern[i]);
292	}
293	#endif
294	return 0;
295	}
296
297	DEBUGP("Pattern matches!\n");
298	/* Now we've found the constant string, try to skip
299	to the 'skip' character */
300	for (i = plen; data[i] != skip; i++)
301	if (i == dlen - 1) return -1;
302
303	/* Skip over the last character */
304	i++;
305
306	DEBUGP("Skipped up to `%c'!\n", skip);
307
308	*numoff = i;
309	*numlen = getnum(data + i, dlen - i, cmd, term);
310	if (!*numlen)
311	return -1;
312
313	DEBUGP("Match succeeded!\n");
314	return 1;
315	}
316
317	/* Look up to see if we're just after a \n. */
318	static int find_nl_seq(u32 seq, const struct ip_ct_ftp_master *info, int dir)
319	{
320	unsigned int i;
321
322	for (i = 0; i < info->seq_aft_nl_num[dir]; i++)
323	if (info->seq_aft_nl[dir][i] == seq)
324	return 1;
325	return 0;
326	}
327
328	/* We don't update if it's older than what we have. */
329	static void update_nl_seq(u32 nl_seq, struct ip_ct_ftp_master *info, int dir,
330	struct sk_buff *skb)
331	{
332	unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
333
334	/* Look for oldest: if we find exact match, we're done. */
335	for (i = 0; i < info->seq_aft_nl_num[dir]; i++) {
336	if (info->seq_aft_nl[dir][i] == nl_seq)
337	return;
338
339	if (oldest == info->seq_aft_nl_num[dir]
340	\|\| before(info->seq_aft_nl[dir][i], oldest))
341	oldest = i;
342	}
343
344	if (info->seq_aft_nl_num[dir] < NUM_SEQ_TO_REMEMBER) {
345	info->seq_aft_nl[dir][info->seq_aft_nl_num[dir]++] = nl_seq;
346	nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
347	} else if (oldest != NUM_SEQ_TO_REMEMBER) {
348	info->seq_aft_nl[dir][oldest] = nl_seq;
349	nf_conntrack_event_cache(IPCT_HELPINFO_VOLATILE, skb);
350	}
351	}
352
353	static int help(struct sk_buff **pskb,
354	unsigned int protoff,
355	struct nf_conn *ct,
356	enum ip_conntrack_info ctinfo)
357	{
358	unsigned int dataoff, datalen;
359	struct tcphdr _tcph, *th;
360	char *fb_ptr;
361	int ret;
362	u32 seq;
363	int dir = CTINFO2DIR(ctinfo);
364	unsigned int matchlen, matchoff;
dc808fe2	365	struct ip_ct_ftp_master *ct_ftp_info = &nfct_help(ct)->help.ct_ftp_info;
9fb9cbb1 YK	366	struct nf_conntrack_expect *exp;
	367	struct nf_conntrack_man cmd = {};
	368
	369	unsigned int i;
	370	int found = 0, ends_in_nl;
	371
	372	/* Until there's been traffic both ways, don't look in packets. */
	373	if (ctinfo != IP_CT_ESTABLISHED
	374	&& ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY) {
	375	DEBUGP("ftp: Conntrackinfo = %u\n", ctinfo);
	376	return NF_ACCEPT;
	377	}
	378
	379	th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
	380	if (th == NULL)
	381	return NF_ACCEPT;
	382
	383	dataoff = protoff + th->doff * 4;
	384	/* No data? */
	385	if (dataoff >= (*pskb)->len) {
	386	DEBUGP("ftp: dataoff(%u) >= skblen(%u)\n", dataoff,
	387	(*pskb)->len);
	388	return NF_ACCEPT;
	389	}
	390	datalen = (*pskb)->len - dataoff;
	391
	392	spin_lock_bh(&nf_ftp_lock);
	393	fb_ptr = skb_header_pointer(*pskb, dataoff, datalen, ftp_buffer);
	394	BUG_ON(fb_ptr == NULL);
	395
	396	ends_in_nl = (fb_ptr[datalen - 1] == '\n');
	397	seq = ntohl(th->seq) + datalen;
	398
	399	/* Look up to see if we're just after a \n. */
	400	if (!find_nl_seq(ntohl(th->seq), ct_ftp_info, dir)) {
	401	/* Now if this ends in \n, update ftp info. */
	402	DEBUGP("nf_conntrack_ftp_help: wrong seq pos %s(%u) or %s(%u)\n",
	403	ct_ftp_info->seq_aft_nl_num[dir] > 0 ? "" : "(UNSET)",
	404	ct_ftp_info->seq_aft_nl[dir][0],
	405	ct_ftp_info->seq_aft_nl_num[dir] > 1 ? "" : "(UNSET)",
	406	ct_ftp_info->seq_aft_nl[dir][1]);
	407	ret = NF_ACCEPT;
	408	goto out_update_nl;
	409	}
	410
	411	/* Initialize IP/IPv6 addr to expected address (it's not mentioned
	412	in EPSV responses) */
	413	cmd.l3num = ct->tuplehash[dir].tuple.src.l3num;
	414	memcpy(cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	415	sizeof(cmd.u3.all));
	416
7d8c5018	417	for (i = 0; i < ARRAY_SIZE(search[dir]); i++) {
9fb9cbb1	418	found = find_pattern(fb_ptr, datalen,
7d8c5018 PM	419	search[dir][i].pattern,
	420	search[dir][i].plen,
	421	search[dir][i].skip,
	422	search[dir][i].term,
9fb9cbb1 YK	423	&matchoff, &matchlen,
9fb9cbb1 YK	424	&cmd,
7d8c5018	425	search[dir][i].getnum);
9fb9cbb1 YK	426	if (found) break;
	427	}
	428	if (found == -1) {
	429	/* We don't usually drop packets. After all, this is
	430	connection tracking, not packet filtering.
	431	However, it is necessary for accurate tracking in
	432	this case. */
	433	if (net_ratelimit())
	434	printk("conntrack_ftp: partial %s %u+%u\n",
7d8c5018	435	search[dir][i].pattern,
9fb9cbb1 YK	436	ntohl(th->seq), datalen);
	437	ret = NF_DROP;
	438	goto out;
	439	} else if (found == 0) { /* No match */
	440	ret = NF_ACCEPT;
	441	goto out_update_nl;
	442	}
	443
	444	DEBUGP("conntrack_ftp: match `%.*s' (%u bytes at %u)\n",
	445	(int)matchlen, fb_ptr + matchoff,
	446	matchlen, ntohl(th->seq) + matchoff);
	447
	448	exp = nf_conntrack_expect_alloc(ct);
	449	if (exp == NULL) {
	450	ret = NF_DROP;
	451	goto out;
	452	}
	453
	454	/* We refer to the reverse direction ("!dir") tuples here,
	455	* because we're expecting something in the other direction.
	456	* Doesn't matter unless NAT is happening. */
	457	exp->tuple.dst.u3 = ct->tuplehash[!dir].tuple.dst.u3;
	458
	459	/* Update the ftp info */
	460	if ((cmd.l3num == ct->tuplehash[dir].tuple.src.l3num) &&
	461	memcmp(&cmd.u3.all, &ct->tuplehash[dir].tuple.src.u3.all,
	462	sizeof(cmd.u3.all))) {
	463	/* Enrico Scholz's passive FTP to partially RNAT'd ftp
	464	server: it really wants us to connect to a
	465	different IP address. Simply don't record it for
	466	NAT. */
	467	if (cmd.l3num == PF_INET) {
46b86a2d	468	DEBUGP("conntrack_ftp: NOT RECORDING: " NIPQUAD_FMT " != " NIPQUAD_FMT "\n",
9fb9cbb1 YK	469	NIPQUAD(cmd.u3.ip),
	470	NIPQUAD(ct->tuplehash[dir].tuple.src.u3.ip));
	471	} else {
46b86a2d	472	DEBUGP("conntrack_ftp: NOT RECORDING: " NIP6_FMT " != " NIP6_FMT "\n",
9fb9cbb1 YK	473	NIP6(((struct in6_addr )cmd.u3.ip6)),
	474	NIP6(((struct in6_addr )ct->tuplehash[dir]
	475	.tuple.src.u3.ip6)));
	476	}
	477
	478	/* Thanks to Cristiano Lincoln Mattos
	479	<lincoln@cesar.org.br> for reporting this potential
	480	problem (DMZ machines opening holes to internal
	481	networks, or the packet filter itself). */
	482	if (!loose) {
	483	ret = NF_ACCEPT;
	484	goto out_put_expect;
	485	}
	486	memcpy(&exp->tuple.dst.u3, &cmd.u3.all,
	487	sizeof(exp->tuple.dst.u3));
	488	}
	489
	490	exp->tuple.src.u3 = ct->tuplehash[!dir].tuple.src.u3;
	491	exp->tuple.src.l3num = cmd.l3num;
	492	exp->tuple.src.u.tcp.port = 0;
	493	exp->tuple.dst.u.tcp.port = cmd.u.tcp.port;
	494	exp->tuple.dst.protonum = IPPROTO_TCP;
	495
	496	exp->mask = (struct nf_conntrack_tuple)
	497	{ .src = { .l3num = 0xFFFF,
	498	.u = { .tcp = { 0 }},
	499	},
	500	.dst = { .protonum = 0xFF,
	501	.u = { .tcp = { 0xFFFF }},
	502	},
	503	};
	504	if (cmd.l3num == PF_INET) {
	505	exp->mask.src.u3.ip = 0xFFFFFFFF;
	506	exp->mask.dst.u3.ip = 0xFFFFFFFF;
	507	} else {
	508	memset(exp->mask.src.u3.ip6, 0xFF,
	509	sizeof(exp->mask.src.u3.ip6));
	510	memset(exp->mask.dst.u3.ip6, 0xFF,
	511	sizeof(exp->mask.src.u3.ip6));
	512	}
	513
	514	exp->expectfn = NULL;
	515	exp->flags = 0;
	516
	517	/* Now, NAT might want to mangle the packet, and register the
	518	* (possibly changed) expectation itself. */
	519	if (nf_nat_ftp_hook)
7d8c5018	520	ret = nf_nat_ftp_hook(pskb, ctinfo, search[dir][i].ftptype,
9fb9cbb1 YK	521	matchoff, matchlen, exp, &seq);
	522	else {
	523	/* Can't expect this? Best to drop packet now. */
	524	if (nf_conntrack_expect_related(exp) != 0)
	525	ret = NF_DROP;
	526	else
	527	ret = NF_ACCEPT;
	528	}
	529
	530	out_put_expect:
	531	nf_conntrack_expect_put(exp);
	532
	533	out_update_nl:
	534	/* Now if this ends in \n, update ftp info. Seq may have been
	535	* adjusted by NAT code. */
	536	if (ends_in_nl)
	537	update_nl_seq(seq, ct_ftp_info, dir, *pskb);
	538	out:
	539	spin_unlock_bh(&nf_ftp_lock);
	540	return ret;
	541	}
	542
	543	static struct nf_conntrack_helper ftp[MAX_PORTS][2];
	544	static char ftp_names[MAX_PORTS][2][sizeof("ftp-65535")];
	545
	546	/* don't make this __exit, since it's called from __init ! */
65b4b4e8	547	static void nf_conntrack_ftp_fini(void)
9fb9cbb1 YK	548	{
	549	int i, j;
	550	for (i = 0; i < ports_c; i++) {
	551	for (j = 0; j < 2; j++) {
	552	if (ftp[i][j].me == NULL)
	553	continue;
	554
	555	DEBUGP("nf_ct_ftp: unregistering helper for pf: %d "
	556	"port: %d\n",
	557	ftp[i][j].tuple.src.l3num, ports[i]);
	558	nf_conntrack_helper_unregister(&ftp[i][j]);
	559	}
	560	}
	561
	562	kfree(ftp_buffer);
	563	}
	564
65b4b4e8	565	static int __init nf_conntrack_ftp_init(void)
9fb9cbb1 YK	566	{
	567	int i, j = -1, ret = 0;
	568	char *tmpname;
	569
	570	ftp_buffer = kmalloc(65536, GFP_KERNEL);
	571	if (!ftp_buffer)
	572	return -ENOMEM;
	573
	574	if (ports_c == 0)
	575	ports[ports_c++] = FTP_PORT;
	576
	577	/* FIXME should be configurable whether IPv4 and IPv6 FTP connections
	578	are tracked or not - YK */
	579	for (i = 0; i < ports_c; i++) {
9fb9cbb1 YK	580	ftp[i][0].tuple.src.l3num = PF_INET;
	581	ftp[i][1].tuple.src.l3num = PF_INET6;
	582	for (j = 0; j < 2; j++) {
	583	ftp[i][j].tuple.src.u.tcp.port = htons(ports[i]);
	584	ftp[i][j].tuple.dst.protonum = IPPROTO_TCP;
	585	ftp[i][j].mask.src.u.tcp.port = 0xFFFF;
	586	ftp[i][j].mask.dst.protonum = 0xFF;
	587	ftp[i][j].max_expected = 1;
	588	ftp[i][j].timeout = 5 * 60; /* 5 Minutes */
	589	ftp[i][j].me = THIS_MODULE;
	590	ftp[i][j].help = help;
	591	tmpname = &ftp_names[i][j][0];
	592	if (ports[i] == FTP_PORT)
	593	sprintf(tmpname, "ftp");
	594	else
	595	sprintf(tmpname, "ftp-%d", ports[i]);
	596	ftp[i][j].name = tmpname;
	597
	598	DEBUGP("nf_ct_ftp: registering helper for pf: %d "
	599	"port: %d\n",
	600	ftp[i][j].tuple.src.l3num, ports[i]);
	601	ret = nf_conntrack_helper_register(&ftp[i][j]);
	602	if (ret) {
	603	printk("nf_ct_ftp: failed to register helper "
	604	" for pf: %d port: %d\n",
	605	ftp[i][j].tuple.src.l3num, ports[i]);
65b4b4e8	606	nf_conntrack_ftp_fini();
9fb9cbb1 YK	607	return ret;
	608	}
	609	}
	610	}
	611
	612	return 0;
	613	}
	614
65b4b4e8 AM	615	module_init(nf_conntrack_ftp_init);
65b4b4e8 AM	616	module_exit(nf_conntrack_ftp_fini);