Add FTP NAT helper.
Split out from Jozsef's big nf_nat patch with a few small fixes by myself.
Signed-off-by: Jozsef Kadlecsik <kadlec@blackhole.kfki.hu>
Signed-off-by: Patrick McHardy <kaber@trash.net>
Signed-off-by: David S. Miller <davem@davemloft.net>
/* FTP tracking. */
/* This enum is exposed to userspace */
-enum ip_ct_ftp_type
+enum nf_ct_ftp_type
{
/* PORT command from client */
- IP_CT_FTP_PORT,
+ NF_CT_FTP_PORT,
/* PASV response from server */
- IP_CT_FTP_PASV,
+ NF_CT_FTP_PASV,
/* EPRT command from client */
- IP_CT_FTP_EPRT,
+ NF_CT_FTP_EPRT,
/* EPSV response from server */
- IP_CT_FTP_EPSV,
+ NF_CT_FTP_EPSV,
};
#ifdef __KERNEL__
#define NUM_SEQ_TO_REMEMBER 2
/* This structure exists only once per master */
-struct ip_ct_ftp_master {
+struct nf_ct_ftp_master {
/* Valid seq positions for cmd matching after newline */
u_int32_t seq_aft_nl[IP_CT_DIR_MAX][NUM_SEQ_TO_REMEMBER];
/* 0 means seq_match_aft_nl not set */
int seq_aft_nl_num[IP_CT_DIR_MAX];
};
-struct ip_conntrack_expect;
+struct nf_conntrack_expect;
/* For NAT to hook in when we find a packet which describes what other
* connection we should expect. */
-extern unsigned int (*ip_nat_ftp_hook)(struct sk_buff **pskb,
+extern unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb,
enum ip_conntrack_info ctinfo,
- enum ip_ct_ftp_type type,
+ enum nf_ct_ftp_type type,
unsigned int matchoff,
unsigned int matchlen,
- struct ip_conntrack_expect *exp,
+ struct nf_conntrack_expect *exp,
u32 *seq);
#endif /* __KERNEL__ */
#ifndef _IP_CONNTRACK_FTP_H
#define _IP_CONNTRACK_FTP_H
+/* FTP tracking. */
-#include <linux/netfilter/nf_conntrack_ftp.h>
+/* This enum is exposed to userspace */
+enum ip_ct_ftp_type
+{
+ /* PORT command from client */
+ IP_CT_FTP_PORT,
+ /* PASV response from server */
+ IP_CT_FTP_PASV,
+ /* EPRT command from client */
+ IP_CT_FTP_EPRT,
+ /* EPSV response from server */
+ IP_CT_FTP_EPSV,
+};
+
+#ifdef __KERNEL__
+
+#define FTP_PORT 21
+
+#define NUM_SEQ_TO_REMEMBER 2
+/* This structure exists only once per master */
+struct ip_ct_ftp_master {
+ /* Valid seq positions for cmd matching after newline */
+ u_int32_t seq_aft_nl[IP_CT_DIR_MAX][NUM_SEQ_TO_REMEMBER];
+ /* 0 means seq_match_aft_nl not set */
+ int seq_aft_nl_num[IP_CT_DIR_MAX];
+};
+
+struct ip_conntrack_expect;
+
+/* For NAT to hook in when we find a packet which describes what other
+ * connection we should expect. */
+extern unsigned int (*ip_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 ip_conntrack_expect *exp,
+ u32 *seq);
+#endif /* __KERNEL__ */
#endif /* _IP_CONNTRACK_FTP_H */
/* per conntrack: application helper private data */
union nf_conntrack_help {
/* insert conntrack helper private data (master) here */
- struct ip_ct_ftp_master ct_ftp_info;
+ struct nf_ct_ftp_master ct_ftp_info;
};
#include <linux/types.h>
To compile it as a module, choose M here. If unsure, say N.
+# If they want FTP, set to $CONFIG_IP_NF_NAT (m or y),
+# or $CONFIG_IP_NF_FTP (m or y), whichever is weaker.
+# From kconfig-language.txt:
+#
+# <expr> '&&' <expr> (6)
+#
+# (6) Returns the result of min(/expr/, /expr/).
+config IP_NF_NAT_FTP
+ tristate
+ depends on IP_NF_IPTABLES && IP_NF_CONNTRACK && IP_NF_NAT
+ default IP_NF_NAT && IP_NF_FTP
+
+config NF_NAT_FTP
+ tristate
+ depends on IP_NF_IPTABLES && NF_CONNTRACK && NF_NAT
+ default NF_NAT && NF_CONNTRACK_FTP
+
config IP_NF_NAT_IRC
tristate
depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
default IP_NF_NAT if IP_NF_IRC=y
default m if IP_NF_IRC=m
-# If they want FTP, set to $CONFIG_IP_NF_NAT (m or y),
-# or $CONFIG_IP_NF_FTP (m or y), whichever is weaker. Argh.
-config IP_NF_NAT_FTP
- tristate
- depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
- default IP_NF_NAT if IP_NF_FTP=y
- default m if IP_NF_FTP=m
-
config IP_NF_NAT_TFTP
tristate
depends on IP_NF_IPTABLES!=n && IP_NF_CONNTRACK!=n && IP_NF_NAT!=n
obj-$(CONFIG_IP_NF_SIP) += ip_conntrack_sip.o
obj-$(CONFIG_IP_NF_NETBIOS_NS) += ip_conntrack_netbios_ns.o
-# NAT helpers
+# NAT helpers (ip_conntrack)
obj-$(CONFIG_IP_NF_NAT_H323) += ip_nat_h323.o
obj-$(CONFIG_IP_NF_NAT_PPTP) += ip_nat_pptp.o
obj-$(CONFIG_IP_NF_NAT_AMANDA) += ip_nat_amanda.o
obj-$(CONFIG_IP_NF_NAT_IRC) += ip_nat_irc.o
obj-$(CONFIG_IP_NF_NAT_SIP) += ip_nat_sip.o
+# NAT helpers (nf_conntrack)
+obj-$(CONFIG_NF_NAT_FTP) += nf_nat_ftp.o
+
# generic IP tables
obj-$(CONFIG_IP_NF_IPTABLES) += ip_tables.o
--- /dev/null
+/* FTP extension for TCP NAT alteration. */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2006 Netfilter Core Team <coreteam@netfilter.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/ip.h>
+#include <linux/tcp.h>
+#include <linux/netfilter_ipv4.h>
+#include <net/netfilter/nf_nat.h>
+#include <net/netfilter/nf_nat_helper.h>
+#include <net/netfilter/nf_nat_rule.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_ftp.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
+MODULE_DESCRIPTION("ftp NAT helper");
+MODULE_ALIAS("ip_nat_ftp");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/* FIXME: Time out? --RR */
+
+static int
+mangle_rfc959_packet(struct sk_buff **pskb,
+ __be32 newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ u32 *seq)
+{
+ char buffer[sizeof("nnn,nnn,nnn,nnn,nnn,nnn")];
+
+ sprintf(buffer, "%u,%u,%u,%u,%u,%u",
+ NIPQUAD(newip), port>>8, port&0xFF);
+
+ DEBUGP("calling nf_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
+ matchlen, buffer, strlen(buffer));
+}
+
+/* |1|132.235.1.2|6275| */
+static int
+mangle_eprt_packet(struct sk_buff **pskb,
+ __be32 newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ u32 *seq)
+{
+ char buffer[sizeof("|1|255.255.255.255|65535|")];
+
+ sprintf(buffer, "|1|%u.%u.%u.%u|%u|", NIPQUAD(newip), port);
+
+ DEBUGP("calling nf_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
+ matchlen, buffer, strlen(buffer));
+}
+
+/* |1|132.235.1.2|6275| */
+static int
+mangle_epsv_packet(struct sk_buff **pskb,
+ __be32 newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo,
+ u32 *seq)
+{
+ char buffer[sizeof("|||65535|")];
+
+ sprintf(buffer, "|||%u|", port);
+
+ DEBUGP("calling nf_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return nf_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
+ matchlen, buffer, strlen(buffer));
+}
+
+static int (*mangle[])(struct sk_buff **, __be32, u_int16_t,
+ unsigned int, unsigned int, struct nf_conn *,
+ enum ip_conntrack_info, u32 *seq)
+= {
+ [NF_CT_FTP_PORT] = mangle_rfc959_packet,
+ [NF_CT_FTP_PASV] = mangle_rfc959_packet,
+ [NF_CT_FTP_EPRT] = mangle_eprt_packet,
+ [NF_CT_FTP_EPSV] = mangle_epsv_packet
+};
+
+/* So, this packet has hit the connection tracking matching code.
+ Mangle it, and change the expectation to match the new version. */
+static unsigned int nf_nat_ftp(struct sk_buff **pskb,
+ enum ip_conntrack_info ctinfo,
+ enum nf_ct_ftp_type type,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conntrack_expect *exp,
+ u32 *seq)
+{
+ __be32 newip;
+ u_int16_t port;
+ int dir = CTINFO2DIR(ctinfo);
+ struct nf_conn *ct = exp->master;
+
+ DEBUGP("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen);
+
+ /* Connection will come from wherever this packet goes, hence !dir */
+ newip = ct->tuplehash[!dir].tuple.dst.u3.ip;
+ exp->saved_proto.tcp.port = exp->tuple.dst.u.tcp.port;
+ exp->dir = !dir;
+
+ /* When you see the packet, we need to NAT it the same as the
+ * this one. */
+ exp->expectfn = nf_nat_follow_master;
+
+ /* Try to get same port: if not, try to change it. */
+ for (port = ntohs(exp->saved_proto.tcp.port); port != 0; port++) {
+ exp->tuple.dst.u.tcp.port = htons(port);
+ if (nf_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (port == 0)
+ return NF_DROP;
+
+ if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo,
+ seq)) {
+ nf_conntrack_unexpect_related(exp);
+ return NF_DROP;
+ }
+ return NF_ACCEPT;
+}
+
+static void __exit nf_nat_ftp_fini(void)
+{
+ rcu_assign_pointer(nf_nat_ftp_hook, NULL);
+ synchronize_rcu();
+}
+
+static int __init nf_nat_ftp_init(void)
+{
+ BUG_ON(rcu_dereference(nf_nat_ftp_hook));
+ rcu_assign_pointer(nf_nat_ftp_hook, nf_nat_ftp);
+ return 0;
+}
+
+/* Prior to 2.6.11, we had a ports param. No longer, but don't break users. */
+static int warn_set(const char *val, struct kernel_param *kp)
+{
+ printk(KERN_INFO KBUILD_MODNAME
+ ": kernel >= 2.6.10 only uses 'ports' for conntrack modules\n");
+ return 0;
+}
+module_param_call(ports, warn_set, NULL, NULL, 0);
+
+module_init(nf_nat_ftp_init);
+module_exit(nf_nat_ftp_fini);
unsigned int (*nf_nat_ftp_hook)(struct sk_buff **pskb,
enum ip_conntrack_info ctinfo,
- enum ip_ct_ftp_type type,
+ enum nf_ct_ftp_type type,
unsigned int matchoff,
unsigned int matchlen,
struct nf_conntrack_expect *exp,
size_t plen;
char skip;
char term;
- enum ip_ct_ftp_type ftptype;
+ 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] = {
.plen = sizeof("PORT") - 1,
.skip = ' ',
.term = '\r',
- .ftptype = IP_CT_FTP_PORT,
+ .ftptype = NF_CT_FTP_PORT,
.getnum = try_rfc959,
},
{
.plen = sizeof("EPRT") - 1,
.skip = ' ',
.term = '\r',
- .ftptype = IP_CT_FTP_EPRT,
+ .ftptype = NF_CT_FTP_EPRT,
.getnum = try_eprt,
},
},
.plen = sizeof("227 ") - 1,
.skip = '(',
.term = ')',
- .ftptype = IP_CT_FTP_PASV,
+ .ftptype = NF_CT_FTP_PASV,
.getnum = try_rfc959,
},
{
.plen = sizeof("229 ") - 1,
.skip = '(',
.term = ')',
- .ftptype = IP_CT_FTP_EPSV,
+ .ftptype = NF_CT_FTP_EPSV,
.getnum = try_epsv_response,
},
},
}
/* 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)
+static int find_nl_seq(u32 seq, const struct nf_ct_ftp_master *info, int dir)
{
unsigned int i;
}
/* 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,
+static void update_nl_seq(u32 nl_seq, struct nf_ct_ftp_master *info, int dir,
struct sk_buff *skb)
{
unsigned int i, oldest = NUM_SEQ_TO_REMEMBER;
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_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;
/* 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)
+ if (nf_nat_ftp && ct->status & IPS_NAT_MASK)
ret = nf_nat_ftp(pskb, ctinfo, search[dir][i].ftptype,
matchoff, matchlen, exp, &seq);
else {
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