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path: root/net/ipv4/netfilter/ip_nat_ftp.c
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Diffstat (limited to 'net/ipv4/netfilter/ip_nat_ftp.c')
-rw-r--r--net/ipv4/netfilter/ip_nat_ftp.c183
1 files changed, 183 insertions, 0 deletions
diff --git a/net/ipv4/netfilter/ip_nat_ftp.c b/net/ipv4/netfilter/ip_nat_ftp.c
new file mode 100644
index 00000000000..c6000e794ad
--- /dev/null
+++ b/net/ipv4/netfilter/ip_nat_ftp.c
@@ -0,0 +1,183 @@
+/* FTP extension for TCP NAT alteration. */
+
+/* (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 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/netfilter_ipv4.h>
+#include <linux/ip.h>
+#include <linux/tcp.h>
+#include <linux/moduleparam.h>
+#include <net/tcp.h>
+#include <linux/netfilter_ipv4/ip_nat.h>
+#include <linux/netfilter_ipv4/ip_nat_helper.h>
+#include <linux/netfilter_ipv4/ip_nat_rule.h>
+#include <linux/netfilter_ipv4/ip_conntrack_ftp.h>
+#include <linux/netfilter_ipv4/ip_conntrack_helper.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Rusty Russell <rusty@rustcorp.com.au>");
+MODULE_DESCRIPTION("ftp NAT helper");
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+/* FIXME: Time out? --RR */
+
+static int
+mangle_rfc959_packet(struct sk_buff **pskb,
+ u_int32_t newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct ip_conntrack *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 ip_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return ip_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,
+ u_int32_t newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct ip_conntrack *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 ip_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return ip_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,
+ u_int32_t newip,
+ u_int16_t port,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct ip_conntrack *ct,
+ enum ip_conntrack_info ctinfo,
+ u32 *seq)
+{
+ char buffer[sizeof("|||65535|")];
+
+ sprintf(buffer, "|||%u|", port);
+
+ DEBUGP("calling ip_nat_mangle_tcp_packet\n");
+
+ *seq += strlen(buffer) - matchlen;
+ return ip_nat_mangle_tcp_packet(pskb, ct, ctinfo, matchoff,
+ matchlen, buffer, strlen(buffer));
+}
+
+static int (*mangle[])(struct sk_buff **, u_int32_t, u_int16_t,
+ unsigned int,
+ unsigned int,
+ struct ip_conntrack *,
+ enum ip_conntrack_info,
+ u32 *seq)
+= { [IP_CT_FTP_PORT] = mangle_rfc959_packet,
+ [IP_CT_FTP_PASV] = mangle_rfc959_packet,
+ [IP_CT_FTP_EPRT] = mangle_eprt_packet,
+ [IP_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 ip_nat_ftp(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)
+{
+ u_int32_t newip;
+ u_int16_t port;
+ int dir = CTINFO2DIR(ctinfo);
+ struct ip_conntrack *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.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 = ip_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 (ip_conntrack_expect_related(exp) == 0)
+ break;
+ }
+
+ if (port == 0) {
+ ip_conntrack_expect_free(exp);
+ return NF_DROP;
+ }
+
+ if (!mangle[type](pskb, newip, port, matchoff, matchlen, ct, ctinfo,
+ seq)) {
+ ip_conntrack_unexpect_related(exp);
+ return NF_DROP;
+ }
+ return NF_ACCEPT;
+}
+
+static void __exit fini(void)
+{
+ ip_nat_ftp_hook = NULL;
+ /* Make sure noone calls it, meanwhile. */
+ synchronize_net();
+}
+
+static int __init init(void)
+{
+ BUG_ON(ip_nat_ftp_hook);
+ ip_nat_ftp_hook = ip_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 __stringify(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(init);
+module_exit(fini);