netfilter: nf_nat: support IPv6 in FTP NAT helper
Signed-off-by: Patrick McHardy <kaber@trash.net>
diff --git a/net/netfilter/nf_nat_ftp.c b/net/netfilter/nf_nat_ftp.c
new file mode 100644
index 0000000..e839b97
--- /dev/null
+++ b/net/netfilter/nf_nat_ftp.c
@@ -0,0 +1,143 @@
+/* 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/inet.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_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");
+
+/* FIXME: Time out? --RR */
+
+static int nf_nat_ftp_fmt_cmd(struct nf_conn *ct, enum nf_ct_ftp_type type,
+ char *buffer, size_t buflen,
+ union nf_inet_addr *addr, u16 port)
+{
+ switch (type) {
+ case NF_CT_FTP_PORT:
+ case NF_CT_FTP_PASV:
+ return snprintf(buffer, buflen, "%u,%u,%u,%u,%u,%u",
+ ((unsigned char *)&addr->ip)[0],
+ ((unsigned char *)&addr->ip)[1],
+ ((unsigned char *)&addr->ip)[2],
+ ((unsigned char *)&addr->ip)[3],
+ port >> 8,
+ port & 0xFF);
+ case NF_CT_FTP_EPRT:
+ if (nf_ct_l3num(ct) == NFPROTO_IPV4)
+ return snprintf(buffer, buflen, "|1|%pI4|%u|",
+ &addr->ip, port);
+ else
+ return snprintf(buffer, buflen, "|2|%pI6|%u|",
+ &addr->ip6, port);
+ case NF_CT_FTP_EPSV:
+ return snprintf(buffer, buflen, "|||%u|", port);
+ }
+
+ return 0;
+}
+
+/* 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 *skb,
+ enum ip_conntrack_info ctinfo,
+ enum nf_ct_ftp_type type,
+ unsigned int protoff,
+ unsigned int matchoff,
+ unsigned int matchlen,
+ struct nf_conntrack_expect *exp)
+{
+ union nf_inet_addr newaddr;
+ u_int16_t port;
+ int dir = CTINFO2DIR(ctinfo);
+ struct nf_conn *ct = exp->master;
+ char buffer[sizeof("|1||65535|") + INET6_ADDRSTRLEN];
+ unsigned int buflen;
+
+ pr_debug("FTP_NAT: type %i, off %u len %u\n", type, matchoff, matchlen);
+
+ /* Connection will come from wherever this packet goes, hence !dir */
+ newaddr = ct->tuplehash[!dir].tuple.dst.u3;
+ 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++) {
+ int ret;
+
+ exp->tuple.dst.u.tcp.port = htons(port);
+ ret = nf_ct_expect_related(exp);
+ if (ret == 0)
+ break;
+ else if (ret != -EBUSY) {
+ port = 0;
+ break;
+ }
+ }
+
+ if (port == 0)
+ return NF_DROP;
+
+ buflen = nf_nat_ftp_fmt_cmd(ct, type, buffer, sizeof(buffer),
+ &newaddr, port);
+ if (!buflen)
+ goto out;
+
+ pr_debug("calling nf_nat_mangle_tcp_packet\n");
+
+ if (!nf_nat_mangle_tcp_packet(skb, ct, ctinfo, protoff, matchoff,
+ matchlen, buffer, buflen))
+ goto out;
+
+ return NF_ACCEPT;
+
+out:
+ nf_ct_unexpect_related(exp);
+ return NF_DROP;
+}
+
+static void __exit nf_nat_ftp_fini(void)
+{
+ RCU_INIT_POINTER(nf_nat_ftp_hook, NULL);
+ synchronize_rcu();
+}
+
+static int __init nf_nat_ftp_init(void)
+{
+ BUG_ON(nf_nat_ftp_hook != NULL);
+ RCU_INIT_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);