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- /*
- * ip_vs_ftp.c: IPVS ftp application module
- *
- * Authors: Wensong Zhang <wensong@linuxvirtualserver.org>
- *
- * Changes:
- *
- *
- * This program is free software; you can redistribute it and/or
- * modify it under the terms of the GNU General Public License
- * as published by the Free Software Foundation; either version
- * 2 of the License, or (at your option) any later version.
- *
- * Most code here is taken from ip_masq_ftp.c in kernel 2.2. The difference
- * is that ip_vs_ftp module handles the reverse direction to ip_masq_ftp.
- *
- * IP_MASQ_FTP ftp masquerading module
- *
- * Version: @(#)ip_masq_ftp.c 0.04 02/05/96
- *
- * Author: Wouter Gadeyne
- *
- */
- #define KMSG_COMPONENT "IPVS"
- #define pr_fmt(fmt) KMSG_COMPONENT ": " fmt
- #include <linux/module.h>
- #include <linux/moduleparam.h>
- #include <linux/kernel.h>
- #include <linux/skbuff.h>
- #include <linux/in.h>
- #include <linux/ip.h>
- #include <linux/netfilter.h>
- #include <net/netfilter/nf_conntrack.h>
- #include <net/netfilter/nf_conntrack_expect.h>
- #include <net/netfilter/nf_nat.h>
- #include <net/netfilter/nf_nat_helper.h>
- #include <linux/gfp.h>
- #include <net/protocol.h>
- #include <net/tcp.h>
- #include <asm/unaligned.h>
- #include <net/ip_vs.h>
- #define SERVER_STRING "227 "
- #define CLIENT_STRING "PORT"
- /*
- * List of ports (up to IP_VS_APP_MAX_PORTS) to be handled by helper
- * First port is set to the default port.
- */
- static unsigned int ports_count = 1;
- static unsigned short ports[IP_VS_APP_MAX_PORTS] = {21, 0};
- module_param_array(ports, ushort, &ports_count, 0444);
- MODULE_PARM_DESC(ports, "Ports to monitor for FTP control commands");
- /* Dummy variable */
- static int ip_vs_ftp_pasv;
- static int
- ip_vs_ftp_init_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
- {
- /* We use connection tracking for the command connection */
- cp->flags |= IP_VS_CONN_F_NFCT;
- return 0;
- }
- static int
- ip_vs_ftp_done_conn(struct ip_vs_app *app, struct ip_vs_conn *cp)
- {
- return 0;
- }
- /*
- * Get <addr,port> from the string "xxx.xxx.xxx.xxx,ppp,ppp", started
- * with the "pattern", ignoring before "skip" and terminated with
- * the "term" character.
- * <addr,port> is in network order.
- */
- static int ip_vs_ftp_get_addrport(char *data, char *data_limit,
- const char *pattern, size_t plen,
- char skip, char term,
- __be32 *addr, __be16 *port,
- char **start, char **end)
- {
- char *s, c;
- unsigned char p[6];
- int i = 0;
- if (data_limit - data < plen) {
- /* check if there is partial match */
- if (strncasecmp(data, pattern, data_limit - data) == 0)
- return -1;
- else
- return 0;
- }
- if (strncasecmp(data, pattern, plen) != 0) {
- return 0;
- }
- s = data + plen;
- if (skip) {
- int found = 0;
- for (;; s++) {
- if (s == data_limit)
- return -1;
- if (!found) {
- if (*s == skip)
- found = 1;
- } else if (*s != skip) {
- break;
- }
- }
- }
- for (data = s; ; data++) {
- if (data == data_limit)
- return -1;
- if (*data == term)
- break;
- }
- *end = data;
- memset(p, 0, sizeof(p));
- for (data = s; ; data++) {
- c = *data;
- if (c == term)
- break;
- if (c >= '0' && c <= '9') {
- p[i] = p[i]*10 + c - '0';
- } else if (c == ',' && i < 5) {
- i++;
- } else {
- /* unexpected character */
- return -1;
- }
- }
- if (i != 5)
- return -1;
- *start = s;
- *addr = get_unaligned((__be32 *) p);
- *port = get_unaligned((__be16 *) (p + 4));
- return 1;
- }
- /*
- * Look at outgoing ftp packets to catch the response to a PASV command
- * from the server (inside-to-outside).
- * When we see one, we build a connection entry with the client address,
- * client port 0 (unknown at the moment), the server address and the
- * server port. Mark the current connection entry as a control channel
- * of the new entry. All this work is just to make the data connection
- * can be scheduled to the right server later.
- *
- * The outgoing packet should be something like
- * "227 Entering Passive Mode (xxx,xxx,xxx,xxx,ppp,ppp)".
- * xxx,xxx,xxx,xxx is the server address, ppp,ppp is the server port number.
- */
- static int ip_vs_ftp_out(struct ip_vs_app *app, struct ip_vs_conn *cp,
- struct sk_buff *skb, int *diff)
- {
- struct iphdr *iph;
- struct tcphdr *th;
- char *data, *data_limit;
- char *start, *end;
- union nf_inet_addr from;
- __be16 port;
- struct ip_vs_conn *n_cp;
- char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */
- unsigned int buf_len;
- int ret = 0;
- enum ip_conntrack_info ctinfo;
- struct nf_conn *ct;
- *diff = 0;
- #ifdef CONFIG_IP_VS_IPV6
- /* This application helper doesn't work with IPv6 yet,
- * so turn this into a no-op for IPv6 packets
- */
- if (cp->af == AF_INET6)
- return 1;
- #endif
- /* Only useful for established sessions */
- if (cp->state != IP_VS_TCP_S_ESTABLISHED)
- return 1;
- /* Linear packets are much easier to deal with. */
- if (!skb_make_writable(skb, skb->len))
- return 0;
- if (cp->app_data == &ip_vs_ftp_pasv) {
- iph = ip_hdr(skb);
- th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
- data = (char *)th + (th->doff << 2);
- data_limit = skb_tail_pointer(skb);
- if (ip_vs_ftp_get_addrport(data, data_limit,
- SERVER_STRING,
- sizeof(SERVER_STRING)-1,
- '(', ')',
- &from.ip, &port,
- &start, &end) != 1)
- return 1;
- IP_VS_DBG(7, "PASV response (%pI4:%d) -> %pI4:%d detected\n",
- &from.ip, ntohs(port), &cp->caddr.ip, 0);
- /*
- * Now update or create an connection entry for it
- */
- {
- struct ip_vs_conn_param p;
- ip_vs_conn_fill_param(cp->ipvs, AF_INET,
- iph->protocol, &from, port,
- &cp->caddr, 0, &p);
- n_cp = ip_vs_conn_out_get(&p);
- }
- if (!n_cp) {
- struct ip_vs_conn_param p;
- ip_vs_conn_fill_param(cp->ipvs,
- AF_INET, IPPROTO_TCP, &cp->caddr,
- 0, &cp->vaddr, port, &p);
- /* As above, this is ipv4 only */
- n_cp = ip_vs_conn_new(&p, AF_INET, &from, port,
- IP_VS_CONN_F_NO_CPORT |
- IP_VS_CONN_F_NFCT,
- cp->dest, skb->mark);
- if (!n_cp)
- return 0;
- /* add its controller */
- ip_vs_control_add(n_cp, cp);
- }
- /*
- * Replace the old passive address with the new one
- */
- from.ip = n_cp->vaddr.ip;
- port = n_cp->vport;
- snprintf(buf, sizeof(buf), "%u,%u,%u,%u,%u,%u",
- ((unsigned char *)&from.ip)[0],
- ((unsigned char *)&from.ip)[1],
- ((unsigned char *)&from.ip)[2],
- ((unsigned char *)&from.ip)[3],
- ntohs(port) >> 8,
- ntohs(port) & 0xFF);
- buf_len = strlen(buf);
- ct = nf_ct_get(skb, &ctinfo);
- if (ct && !nf_ct_is_untracked(ct) && nfct_nat(ct)) {
- /* If mangling fails this function will return 0
- * which will cause the packet to be dropped.
- * Mangling can only fail under memory pressure,
- * hopefully it will succeed on the retransmitted
- * packet.
- */
- rcu_read_lock();
- ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
- iph->ihl * 4,
- start-data, end-start,
- buf, buf_len);
- rcu_read_unlock();
- if (ret) {
- ip_vs_nfct_expect_related(skb, ct, n_cp,
- IPPROTO_TCP, 0, 0);
- if (skb->ip_summed == CHECKSUM_COMPLETE)
- skb->ip_summed = CHECKSUM_UNNECESSARY;
- /* csum is updated */
- ret = 1;
- }
- }
- /*
- * Not setting 'diff' is intentional, otherwise the sequence
- * would be adjusted twice.
- */
- cp->app_data = NULL;
- ip_vs_tcp_conn_listen(n_cp);
- ip_vs_conn_put(n_cp);
- return ret;
- }
- return 1;
- }
- /*
- * Look at incoming ftp packets to catch the PASV/PORT command
- * (outside-to-inside).
- *
- * The incoming packet having the PORT command should be something like
- * "PORT xxx,xxx,xxx,xxx,ppp,ppp\n".
- * xxx,xxx,xxx,xxx is the client address, ppp,ppp is the client port number.
- * In this case, we create a connection entry using the client address and
- * port, so that the active ftp data connection from the server can reach
- * the client.
- */
- static int ip_vs_ftp_in(struct ip_vs_app *app, struct ip_vs_conn *cp,
- struct sk_buff *skb, int *diff)
- {
- struct iphdr *iph;
- struct tcphdr *th;
- char *data, *data_start, *data_limit;
- char *start, *end;
- union nf_inet_addr to;
- __be16 port;
- struct ip_vs_conn *n_cp;
- /* no diff required for incoming packets */
- *diff = 0;
- #ifdef CONFIG_IP_VS_IPV6
- /* This application helper doesn't work with IPv6 yet,
- * so turn this into a no-op for IPv6 packets
- */
- if (cp->af == AF_INET6)
- return 1;
- #endif
- /* Only useful for established sessions */
- if (cp->state != IP_VS_TCP_S_ESTABLISHED)
- return 1;
- /* Linear packets are much easier to deal with. */
- if (!skb_make_writable(skb, skb->len))
- return 0;
- /*
- * Detecting whether it is passive
- */
- iph = ip_hdr(skb);
- th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]);
- /* Since there may be OPTIONS in the TCP packet and the HLEN is
- the length of the header in 32-bit multiples, it is accurate
- to calculate data address by th+HLEN*4 */
- data = data_start = (char *)th + (th->doff << 2);
- data_limit = skb_tail_pointer(skb);
- while (data <= data_limit - 6) {
- if (strncasecmp(data, "PASV\r\n", 6) == 0) {
- /* Passive mode on */
- IP_VS_DBG(7, "got PASV at %td of %td\n",
- data - data_start,
- data_limit - data_start);
- cp->app_data = &ip_vs_ftp_pasv;
- return 1;
- }
- data++;
- }
- /*
- * To support virtual FTP server, the scenerio is as follows:
- * FTP client ----> Load Balancer ----> FTP server
- * First detect the port number in the application data,
- * then create a new connection entry for the coming data
- * connection.
- */
- if (ip_vs_ftp_get_addrport(data_start, data_limit,
- CLIENT_STRING, sizeof(CLIENT_STRING)-1,
- ' ', '\r', &to.ip, &port,
- &start, &end) != 1)
- return 1;
- IP_VS_DBG(7, "PORT %pI4:%d detected\n", &to.ip, ntohs(port));
- /* Passive mode off */
- cp->app_data = NULL;
- /*
- * Now update or create a connection entry for it
- */
- IP_VS_DBG(7, "protocol %s %pI4:%d %pI4:%d\n",
- ip_vs_proto_name(iph->protocol),
- &to.ip, ntohs(port), &cp->vaddr.ip, 0);
- {
- struct ip_vs_conn_param p;
- ip_vs_conn_fill_param(cp->ipvs, AF_INET,
- iph->protocol, &to, port, &cp->vaddr,
- htons(ntohs(cp->vport)-1), &p);
- n_cp = ip_vs_conn_in_get(&p);
- if (!n_cp) {
- /* This is ipv4 only */
- n_cp = ip_vs_conn_new(&p, AF_INET, &cp->daddr,
- htons(ntohs(cp->dport)-1),
- IP_VS_CONN_F_NFCT, cp->dest,
- skb->mark);
- if (!n_cp)
- return 0;
- /* add its controller */
- ip_vs_control_add(n_cp, cp);
- }
- }
- /*
- * Move tunnel to listen state
- */
- ip_vs_tcp_conn_listen(n_cp);
- ip_vs_conn_put(n_cp);
- return 1;
- }
- static struct ip_vs_app ip_vs_ftp = {
- .name = "ftp",
- .type = IP_VS_APP_TYPE_FTP,
- .protocol = IPPROTO_TCP,
- .module = THIS_MODULE,
- .incs_list = LIST_HEAD_INIT(ip_vs_ftp.incs_list),
- .init_conn = ip_vs_ftp_init_conn,
- .done_conn = ip_vs_ftp_done_conn,
- .bind_conn = NULL,
- .unbind_conn = NULL,
- .pkt_out = ip_vs_ftp_out,
- .pkt_in = ip_vs_ftp_in,
- };
- /*
- * per netns ip_vs_ftp initialization
- */
- static int __net_init __ip_vs_ftp_init(struct net *net)
- {
- int i, ret;
- struct ip_vs_app *app;
- struct netns_ipvs *ipvs = net_ipvs(net);
- if (!ipvs)
- return -ENOENT;
- app = register_ip_vs_app(ipvs, &ip_vs_ftp);
- if (IS_ERR(app))
- return PTR_ERR(app);
- for (i = 0; i < ports_count; i++) {
- if (!ports[i])
- continue;
- ret = register_ip_vs_app_inc(ipvs, app, app->protocol, ports[i]);
- if (ret)
- goto err_unreg;
- pr_info("%s: loaded support on port[%d] = %d\n",
- app->name, i, ports[i]);
- }
- return 0;
- err_unreg:
- unregister_ip_vs_app(ipvs, &ip_vs_ftp);
- return ret;
- }
- /*
- * netns exit
- */
- static void __ip_vs_ftp_exit(struct net *net)
- {
- struct netns_ipvs *ipvs = net_ipvs(net);
- if (!ipvs)
- return;
- unregister_ip_vs_app(ipvs, &ip_vs_ftp);
- }
- static struct pernet_operations ip_vs_ftp_ops = {
- .init = __ip_vs_ftp_init,
- .exit = __ip_vs_ftp_exit,
- };
- static int __init ip_vs_ftp_init(void)
- {
- int rv;
- rv = register_pernet_subsys(&ip_vs_ftp_ops);
- /* rcu_barrier() is called by netns on error */
- return rv;
- }
- /*
- * ip_vs_ftp finish.
- */
- static void __exit ip_vs_ftp_exit(void)
- {
- unregister_pernet_subsys(&ip_vs_ftp_ops);
- /* rcu_barrier() is called by netns */
- }
- module_init(ip_vs_ftp_init);
- module_exit(ip_vs_ftp_exit);
- MODULE_LICENSE("GPL");
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