396 lines
9.2 KiB
C
396 lines
9.2 KiB
C
/*
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* ip_vs_ftp.c: IPVS ftp application module
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*
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* Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $
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*
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* Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
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*
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* Changes:
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*
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*
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* This program is free software; you can redistribute it and/or
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* modify it under the terms of the GNU General Public License
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* as published by the Free Software Foundation; either version
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* 2 of the License, or (at your option) any later version.
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*
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* Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference
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* is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp.
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*
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* IP_MASQ_FTP ftp masquerading module
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*
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* Version: @(#)ip_masq_ftp.c 0.04 02/05/96
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*
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* Author: Wouter Gadeyne
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*
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*/
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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/kernel.h>
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#include <linux/skbuff.h>
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#include <linux/in.h>
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#include <linux/ip.h>
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#include <linux/netfilter.h>
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#include <net/protocol.h>
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#include <net/tcp.h>
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#include <asm/unaligned.h>
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#include <net/ip_vs.h>
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#define SERVER_STRING "227 Entering Passive Mode ("
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#define CLIENT_STRING "PORT "
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/*
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* List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
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* First port is set to the default port.
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*/
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static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0};
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module_param_array(ports, ushort, NULL, 0);
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MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands");
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/* Dummy variable */
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static int ip_vs_ftp_pasv;
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static int
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ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
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{
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return 0;
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}
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static int
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ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
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{
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return 0;
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}
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/*
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* Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
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* with the "pattern" and terminated with the "term" character.
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* <addr,port> is in network order.
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*/
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static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
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const char *pattern, size_t plen, char term,
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__be32 *addr, __be16 *port,
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char **start, char **end)
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{
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unsigned char p[6];
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int i = 0;
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if (data_limit - data < plen) {
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/* check if there is partial match */
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if (strnicmp(data, pattern, data_limit - data) == 0)
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return -1;
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else
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return 0;
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}
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if (strnicmp(data, pattern, plen) != 0) {
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return 0;
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}
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*start = data + plen;
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for (data = *start; *data != term; data++) {
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if (data == data_limit)
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return -1;
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}
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*end = data;
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memset(p, 0, sizeof(p));
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for (data = *start; data != *end; data++) {
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if (*data >= '0' && *data <= '9') {
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p[i] = p[i]*10 + *data - '0';
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} else if (*data == ',' && i < 5) {
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i++;
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} else {
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/* unexpected character */
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return -1;
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}
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}
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if (i != 5)
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return -1;
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*addr = get_unaligned((__be32 *)p);
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*port = get_unaligned((__be16 *)(p + 4));
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return 1;
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}
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/*
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* Look at outgoing ftp packets to catch the response to a PASV command
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* from the server (inside-to-outside).
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* When we see one, we build a connection entry with the client address,
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* client port 0 (unknown at the moment), the server address and the
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* server port. Mark the current connection entry as a control channel
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* of the new entry. All this work is just to make the data connection
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* can be scheduled to the right server later.
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*
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* The outgoing packet should be something like
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* "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
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* xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
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*/
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static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
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struct sk_buff *skb, int *diff)
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{
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struct iphdr *iph;
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struct tcphdr *th;
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char *data, *data_limit;
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char *start, *end;
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__be32 from;
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__be16 port;
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struct ip_vs_conn *n_cp;
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char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
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unsigned buf_len;
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int ret;
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*diff = 0;
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/* Only useful for established sessions */
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if (cp->state != IP_VS_TCP_S_ESTABLISHED)
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return 1;
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/* Linear packets are much easier to deal with. */
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if (!skb_make_writable(skb, skb->len))
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return 0;
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if (cp->app_data == &ip_vs_ftp_pasv) {
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iph = ip_hdr(skb);
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th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
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data = (char *)th + (th->doff << 2);
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data_limit = skb_tail_pointer(skb);
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if (ip_vs_ftp_get_addrport(data, data_limit,
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SERVER_STRING,
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sizeof(SERVER_STRING)-1, ')',
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&from, &port,
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&start, &end) != 1)
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return 1;
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IP_VS_DBG(7, "PASV response (%u.%u.%u.%u:%d) -> "
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"%u.%u.%u.%u:%d detected\n",
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NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0);
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/*
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* Now update or create an connection entry for it
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*/
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n_cp = ip_vs_conn_out_get(iph->protocol, from, port,
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cp->caddr, 0);
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if (!n_cp) {
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n_cp = ip_vs_conn_new(IPPROTO_TCP,
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cp->caddr, 0,
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cp->vaddr, port,
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from, port,
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IP_VS_CONN_F_NO_CPORT,
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cp->dest);
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if (!n_cp)
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return 0;
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/* add its controller */
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ip_vs_control_add(n_cp, cp);
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}
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/*
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* Replace the old passive address with the new one
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*/
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from = n_cp->vaddr;
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port = n_cp->vport;
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sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from),
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(ntohs(port)>>8)&255, ntohs(port)&255);
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buf_len = strlen(buf);
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/*
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* Calculate required delta-offset to keep TCP happy
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*/
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*diff = buf_len - (end-start);
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if (*diff == 0) {
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/* simply replace it with new passive address */
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memcpy(start, buf, buf_len);
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ret = 1;
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} else {
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ret = !ip_vs_skb_replace(skb, GFP_ATOMIC, start,
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end-start, buf, buf_len);
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}
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cp->app_data = NULL;
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ip_vs_tcp_conn_listen(n_cp);
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ip_vs_conn_put(n_cp);
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return ret;
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}
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return 1;
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}
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/*
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* Look at incoming ftp packets to catch the PASV/PORT command
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* (outside-to-inside).
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*
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* The incoming packet having the PORT command should be something like
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* "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
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* xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
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* In this case, we create a connection entry using the client address and
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* port, so that the active ftp data connection from the server can reach
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* the client.
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*/
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static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
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struct sk_buff *skb, int *diff)
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{
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struct iphdr *iph;
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struct tcphdr *th;
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char *data, *data_start, *data_limit;
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char *start, *end;
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__be32 to;
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__be16 port;
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struct ip_vs_conn *n_cp;
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/* no diff required for incoming packets */
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*diff = 0;
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/* Only useful for established sessions */
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if (cp->state != IP_VS_TCP_S_ESTABLISHED)
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return 1;
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/* Linear packets are much easier to deal with. */
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if (!skb_make_writable(skb, skb->len))
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return 0;
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/*
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* Detecting whether it is passive
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*/
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iph = ip_hdr(skb);
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th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
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/* Since there may be OPTIONS in the TCP packet and the HLEN is
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the length of the header in 32-bit multiples, it is accurate
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to calculate data address by th+HLEN*4 */
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data = data_start = (char *)th + (th->doff << 2);
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data_limit = skb_tail_pointer(skb);
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while (data <= data_limit - 6) {
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if (strnicmp(data, "PASV\r\n", 6) == 0) {
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/* Passive mode on */
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IP_VS_DBG(7, "got PASV at %td of %td\n",
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data - data_start,
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data_limit - data_start);
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cp->app_data = &ip_vs_ftp_pasv;
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return 1;
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}
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data++;
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}
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/*
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* To support virtual FTP server, the scenerio is as follows:
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* FTP client ----> Load Balancer ----> FTP server
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* First detect the port number in the application data,
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* then create a new connection entry for the coming data
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* connection.
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*/
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if (ip_vs_ftp_get_addrport(data_start, data_limit,
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CLIENT_STRING, sizeof(CLIENT_STRING)-1,
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'\r', &to, &port,
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&start, &end) != 1)
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return 1;
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IP_VS_DBG(7, "PORT %u.%u.%u.%u:%d detected\n",
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NIPQUAD(to), ntohs(port));
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/* Passive mode off */
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cp->app_data = NULL;
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/*
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* Now update or create a connection entry for it
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*/
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IP_VS_DBG(7, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n",
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ip_vs_proto_name(iph->protocol),
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NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0);
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n_cp = ip_vs_conn_in_get(iph->protocol,
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to, port,
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cp->vaddr, htons(ntohs(cp->vport)-1));
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if (!n_cp) {
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n_cp = ip_vs_conn_new(IPPROTO_TCP,
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to, port,
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cp->vaddr, htons(ntohs(cp->vport)-1),
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cp->daddr, htons(ntohs(cp->dport)-1),
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0,
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cp->dest);
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if (!n_cp)
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return 0;
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/* add its controller */
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ip_vs_control_add(n_cp, cp);
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}
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/*
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* Move tunnel to listen state
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*/
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ip_vs_tcp_conn_listen(n_cp);
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ip_vs_conn_put(n_cp);
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return 1;
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}
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static struct ip_vs_app ip_vs_ftp = {
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.name = "ftp",
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.type = IP_VS_APP_TYPE_FTP,
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.protocol = IPPROTO_TCP,
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.module = THIS_MODULE,
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.incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
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.init_conn = ip_vs_ftp_init_conn,
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.done_conn = ip_vs_ftp_done_conn,
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.bind_conn = NULL,
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.unbind_conn = NULL,
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.pkt_out = ip_vs_ftp_out,
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.pkt_in = ip_vs_ftp_in,
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};
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/*
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* ip_vs_ftp initialization
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*/
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static int __init ip_vs_ftp_init(void)
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{
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int i, ret;
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struct ip_vs_app *app = &ip_vs_ftp;
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ret = register_ip_vs_app(app);
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if (ret)
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return ret;
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for (i=0; i<IP_VS_APP_MAX_PORTS; i++) {
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if (!ports[i])
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continue;
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ret = register_ip_vs_app_inc(app, app->protocol, ports[i]);
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if (ret)
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break;
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IP_VS_INFO("%s: loaded support on port[%d] = %d\n",
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app->name, i, ports[i]);
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}
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if (ret)
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unregister_ip_vs_app(app);
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return ret;
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}
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/*
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* ip_vs_ftp finish.
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*/
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static void __exit ip_vs_ftp_exit(void)
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{
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unregister_ip_vs_app(&ip_vs_ftp);
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}
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module_init(ip_vs_ftp_init);
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module_exit(ip_vs_ftp_exit);
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MODULE_LICENSE("GPL");
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