be7be6e161
The commitab8bc7ed86
("netfilter: remove nf_ct_is_untracked") changed the line if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) { to if (ct && nfct_nat(ct)) { meanwhile, the commit41390895e5
("netfilter: ipvs: don't check for presence of nat extension") from ipvs-next had changed the same line to if (ct && !nf_ct_is_untracked(ct) && (ct->status & IPS_NAT_MASK)) { When ipvs-next got merged into nf-next, the merge resolution took the first version, dropping the conversion of nfct_nat(). While this doesn't cause a problem at the moment, it will once we stop adding the nat extension by default. Signed-off-by: Florian Westphal <fw@strlen.de> Signed-off-by: Pablo Neira Ayuso <pablo@netfilter.org>
505 lines
12 KiB
C
505 lines
12 KiB
C
/*
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* ip_vs_ftp.c: IPVS ftp application module
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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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#define KMSG_COMPONENT "IPVS"
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#define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
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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/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <net/netfilter/nf_nat.h>
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#include <net/netfilter/nf_nat_helper.h>
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#include <linux/gfp.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 "
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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 int ports_count = 1;
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static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0};
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module_param_array(ports, ushort, &ports_count, 0444);
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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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/* We use connection tracking for the command connection */
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cp->flags |= IP_VS_CONN_F_NFCT;
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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", ignoring before "skip" and terminated with
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* 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,
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char skip, 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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char *s, c;
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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 (strncasecmp(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 (strncasecmp(data, pattern, plen) != 0) {
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return 0;
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}
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s = data + plen;
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if (skip) {
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int found = 0;
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for (;; s++) {
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if (s == data_limit)
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return -1;
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if (!found) {
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if (*s == skip)
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found = 1;
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} else if (*s != skip) {
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break;
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}
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}
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}
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for (data = s; ; data++) {
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if (data == data_limit)
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return -1;
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if (*data == term)
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break;
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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 = s; ; data++) {
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c = *data;
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if (c == term)
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break;
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if (c >= '0' && c <= '9') {
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p[i] = p[i]*10 + c - '0';
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} else if (c == ',' && 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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*start = s;
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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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union nf_inet_addr 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 int buf_len;
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int ret = 0;
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enum ip_conntrack_info ctinfo;
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struct nf_conn *ct;
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*diff = 0;
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#ifdef CONFIG_IP_VS_IPV6
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/* This application helper doesn't work with IPv6 yet,
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* so turn this into a no-op for IPv6 packets
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*/
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if (cp->af == AF_INET6)
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return 1;
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#endif
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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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'(', ')',
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&from.ip, &port,
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&start, &end) != 1)
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return 1;
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IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
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&from.ip, ntohs(port), &cp->caddr.ip, 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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{
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struct ip_vs_conn_param p;
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ip_vs_conn_fill_param(cp->ipvs, AF_INET,
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iph->protocol, &from, port,
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&cp->caddr, 0, &p);
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n_cp = ip_vs_conn_out_get(&p);
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}
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if (!n_cp) {
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struct ip_vs_conn_param p;
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ip_vs_conn_fill_param(cp->ipvs,
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AF_INET, IPPROTO_TCP, &cp->caddr,
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0, &cp->vaddr, port, &p);
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/* As above, this is ipv4 only */
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n_cp = ip_vs_conn_new(&p, AF_INET, &from, port,
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IP_VS_CONN_F_NO_CPORT |
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IP_VS_CONN_F_NFCT,
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cp->dest, skb->mark);
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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.ip = n_cp->vaddr.ip;
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port = n_cp->vport;
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snprintf(buf, sizeof(buf), "%u,%u,%u,%u,%u,%u",
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((unsigned char *)&from.ip)[0],
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((unsigned char *)&from.ip)[1],
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((unsigned char *)&from.ip)[2],
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((unsigned char *)&from.ip)[3],
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ntohs(port) >> 8,
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ntohs(port) & 0xFF);
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buf_len = strlen(buf);
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ct = nf_ct_get(skb, &ctinfo);
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if (ct && (ct->status & IPS_NAT_MASK)) {
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bool mangled;
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/* If mangling fails this function will return 0
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* which will cause the packet to be dropped.
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* Mangling can only fail under memory pressure,
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* hopefully it will succeed on the retransmitted
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* packet.
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*/
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rcu_read_lock();
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mangled = nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
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iph->ihl * 4,
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start - data,
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end - start,
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buf, buf_len);
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rcu_read_unlock();
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if (mangled) {
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ip_vs_nfct_expect_related(skb, ct, n_cp,
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IPPROTO_TCP, 0, 0);
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if (skb->ip_summed == CHECKSUM_COMPLETE)
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skb->ip_summed = CHECKSUM_UNNECESSARY;
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/* csum is updated */
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ret = 1;
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}
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}
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/*
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* Not setting 'diff' is intentional, otherwise the sequence
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* would be adjusted twice.
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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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union nf_inet_addr 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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#ifdef CONFIG_IP_VS_IPV6
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/* This application helper doesn't work with IPv6 yet,
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* so turn this into a no-op for IPv6 packets
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*/
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if (cp->af == AF_INET6)
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return 1;
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#endif
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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 (strncasecmp(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.ip, &port,
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&start, &end) != 1)
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return 1;
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IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to.ip, 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 %pI4:%d %pI4:%d\n",
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ip_vs_proto_name(iph->protocol),
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&to.ip, ntohs(port), &cp->vaddr.ip, 0);
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{
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struct ip_vs_conn_param p;
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ip_vs_conn_fill_param(cp->ipvs, AF_INET,
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iph->protocol, &to, port, &cp->vaddr,
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htons(ntohs(cp->vport)-1), &p);
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n_cp = ip_vs_conn_in_get(&p);
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if (!n_cp) {
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/* This is ipv4 only */
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n_cp = ip_vs_conn_new(&p, AF_INET, &cp->daddr,
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htons(ntohs(cp->dport)-1),
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IP_VS_CONN_F_NFCT, cp->dest,
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skb->mark);
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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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/*
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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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* per netns ip_vs_ftp initialization
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*/
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static int __net_init __ip_vs_ftp_init(struct net *net)
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{
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int i, ret;
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struct ip_vs_app *app;
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struct netns_ipvs *ipvs = net_ipvs(net);
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if (!ipvs)
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return -ENOENT;
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app = register_ip_vs_app(ipvs, &ip_vs_ftp);
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if (IS_ERR(app))
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return PTR_ERR(app);
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for (i = 0; i < ports_count; i++) {
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if (!ports[i])
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continue;
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ret = register_ip_vs_app_inc(ipvs, app, app->protocol, ports[i]);
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if (ret)
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goto err_unreg;
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pr_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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return 0;
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err_unreg:
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unregister_ip_vs_app(ipvs, &ip_vs_ftp);
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return ret;
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}
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/*
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* netns exit
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*/
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static void __ip_vs_ftp_exit(struct net *net)
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{
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struct netns_ipvs *ipvs = net_ipvs(net);
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if (!ipvs)
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return;
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unregister_ip_vs_app(ipvs, &ip_vs_ftp);
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}
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static struct pernet_operations ip_vs_ftp_ops = {
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.init = __ip_vs_ftp_init,
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.exit = __ip_vs_ftp_exit,
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};
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static int __init ip_vs_ftp_init(void)
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{
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/* rcu_barrier() is called by netns on error */
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return register_pernet_subsys(&ip_vs_ftp_ops);
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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_pernet_subsys(&ip_vs_ftp_ops);
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/* rcu_barrier() is called by netns */
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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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