| /* |
| * ip_vs_ftp.c: IPVS ftp application module |
| * |
| * Version: $Id: ip_vs_ftp.c,v 1.13 2002/09/15 08:14:08 wensong Exp $ |
| * |
| * 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 |
| * |
| */ |
| |
| #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 <net/protocol.h> |
| #include <net/tcp.h> |
| |
| #include <net/ip_vs.h> |
| |
| |
| #define SERVER_STRING "227 Entering Passive Mode (" |
| #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 short ports[IP_VS_APP_MAX_PORTS] = {21, 0}; |
| module_param_array(ports, ushort, NULL, 0); |
| 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) |
| { |
| 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" 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 term, |
| __be32 *addr, __be16 *port, |
| char **start, char **end) |
| { |
| unsigned char p[6]; |
| int i = 0; |
| |
| if (data_limit - data < plen) { |
| /* check if there is partial match */ |
| if (strnicmp(data, pattern, data_limit - data) == 0) |
| return -1; |
| else |
| return 0; |
| } |
| |
| if (strnicmp(data, pattern, plen) != 0) { |
| return 0; |
| } |
| *start = data + plen; |
| |
| for (data = *start; *data != term; data++) { |
| if (data == data_limit) |
| return -1; |
| } |
| *end = data; |
| |
| memset(p, 0, sizeof(p)); |
| for (data = *start; data != *end; data++) { |
| if (*data >= '0' && *data <= '9') { |
| p[i] = p[i]*10 + *data - '0'; |
| } else if (*data == ',' && i < 5) { |
| i++; |
| } else { |
| /* unexpected character */ |
| return -1; |
| } |
| } |
| |
| if (i != 5) |
| return -1; |
| |
| *addr = (p[3]<<24) | (p[2]<<16) | (p[1]<<8) | p[0]; |
| *port = (p[5]<<8) | 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 **pskb, int *diff) |
| { |
| struct iphdr *iph; |
| struct tcphdr *th; |
| char *data, *data_limit; |
| char *start, *end; |
| __be32 from; |
| __be16 port; |
| struct ip_vs_conn *n_cp; |
| char buf[24]; /* xxx.xxx.xxx.xxx,ppp,ppp\000 */ |
| unsigned buf_len; |
| int ret; |
| |
| *diff = 0; |
| |
| /* Only useful for established sessions */ |
| if (cp->state != IP_VS_TCP_S_ESTABLISHED) |
| return 1; |
| |
| /* Linear packets are much easier to deal with. */ |
| if (!ip_vs_make_skb_writable(pskb, (*pskb)->len)) |
| return 0; |
| |
| if (cp->app_data == &ip_vs_ftp_pasv) { |
| iph = (*pskb)->nh.iph; |
| th = (struct tcphdr *)&(((char *)iph)[iph->ihl*4]); |
| data = (char *)th + (th->doff << 2); |
| data_limit = (*pskb)->tail; |
| |
| if (ip_vs_ftp_get_addrport(data, data_limit, |
| SERVER_STRING, |
| sizeof(SERVER_STRING)-1, ')', |
| &from, &port, |
| &start, &end) != 1) |
| return 1; |
| |
| IP_VS_DBG(7, "PASV response (%u.%u.%u.%u:%d) -> " |
| "%u.%u.%u.%u:%d detected\n", |
| NIPQUAD(from), ntohs(port), NIPQUAD(cp->caddr), 0); |
| |
| /* |
| * Now update or create an connection entry for it |
| */ |
| n_cp = ip_vs_conn_out_get(iph->protocol, from, port, |
| cp->caddr, 0); |
| if (!n_cp) { |
| n_cp = ip_vs_conn_new(IPPROTO_TCP, |
| cp->caddr, 0, |
| cp->vaddr, port, |
| from, port, |
| IP_VS_CONN_F_NO_CPORT, |
| cp->dest); |
| 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 = n_cp->vaddr; |
| port = n_cp->vport; |
| sprintf(buf,"%d,%d,%d,%d,%d,%d", NIPQUAD(from), |
| ntohs(port)&255, (ntohs(port)>>8)&255); |
| buf_len = strlen(buf); |
| |
| /* |
| * Calculate required delta-offset to keep TCP happy |
| */ |
| *diff = buf_len - (end-start); |
| |
| if (*diff == 0) { |
| /* simply replace it with new passive address */ |
| memcpy(start, buf, buf_len); |
| ret = 1; |
| } else { |
| ret = !ip_vs_skb_replace(*pskb, GFP_ATOMIC, start, |
| end-start, buf, buf_len); |
| } |
| |
| 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 **pskb, int *diff) |
| { |
| struct iphdr *iph; |
| struct tcphdr *th; |
| char *data, *data_start, *data_limit; |
| char *start, *end; |
| __be32 to; |
| __be16 port; |
| struct ip_vs_conn *n_cp; |
| |
| /* no diff required for incoming packets */ |
| *diff = 0; |
| |
| /* Only useful for established sessions */ |
| if (cp->state != IP_VS_TCP_S_ESTABLISHED) |
| return 1; |
| |
| /* Linear packets are much easier to deal with. */ |
| if (!ip_vs_make_skb_writable(pskb, (*pskb)->len)) |
| return 0; |
| |
| /* |
| * Detecting whether it is passive |
| */ |
| iph = (*pskb)->nh.iph; |
| 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 = (*pskb)->tail; |
| |
| while (data <= data_limit - 6) { |
| if (strnicmp(data, "PASV\r\n", 6) == 0) { |
| /* Passive mode on */ |
| IP_VS_DBG(7, "got PASV at %zd of %zd\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, &port, |
| &start, &end) != 1) |
| return 1; |
| |
| IP_VS_DBG(7, "PORT %u.%u.%u.%u:%d detected\n", |
| NIPQUAD(to), ntohs(port)); |
| |
| /* Passive mode off */ |
| cp->app_data = NULL; |
| |
| /* |
| * Now update or create a connection entry for it |
| */ |
| IP_VS_DBG(7, "protocol %s %u.%u.%u.%u:%d %u.%u.%u.%u:%d\n", |
| ip_vs_proto_name(iph->protocol), |
| NIPQUAD(to), ntohs(port), NIPQUAD(cp->vaddr), 0); |
| |
| n_cp = ip_vs_conn_in_get(iph->protocol, |
| to, port, |
| cp->vaddr, htons(ntohs(cp->vport)-1)); |
| if (!n_cp) { |
| n_cp = ip_vs_conn_new(IPPROTO_TCP, |
| to, port, |
| cp->vaddr, htons(ntohs(cp->vport)-1), |
| cp->daddr, htons(ntohs(cp->dport)-1), |
| 0, |
| cp->dest); |
| 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, |
| }; |
| |
| |
| /* |
| * ip_vs_ftp initialization |
| */ |
| static int __init ip_vs_ftp_init(void) |
| { |
| int i, ret; |
| struct ip_vs_app *app = &ip_vs_ftp; |
| |
| ret = register_ip_vs_app(app); |
| if (ret) |
| return ret; |
| |
| for (i=0; i<IP_VS_APP_MAX_PORTS; i++) { |
| if (!ports[i]) |
| continue; |
| ret = register_ip_vs_app_inc(app, app->protocol, ports[i]); |
| if (ret) |
| break; |
| IP_VS_INFO("%s: loaded support on port[%d] = %d\n", |
| app->name, i, ports[i]); |
| } |
| |
| if (ret) |
| unregister_ip_vs_app(app); |
| |
| return ret; |
| } |
| |
| |
| /* |
| * ip_vs_ftp finish. |
| */ |
| static void __exit ip_vs_ftp_exit(void) |
| { |
| unregister_ip_vs_app(&ip_vs_ftp); |
| } |
| |
| |
| module_init(ip_vs_ftp_init); |
| module_exit(ip_vs_ftp_exit); |
| MODULE_LICENSE("GPL"); |