| /* |
| * 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 |
| * |
| * |
| * Code for ip_vs_expect_related and ip_vs_expect_callback is taken from |
| * http://www.ssi.bg/~ja/nfct/: |
| * |
| * ip_vs_nfct.c: Netfilter connection tracking support for IPVS |
| * |
| * Portions Copyright (C) 2001-2002 |
| * Antefacto Ltd, 181 Parnell St, Dublin 1, Ireland. |
| * |
| * Portions Copyright (C) 2003-2008 |
| * Julian Anastasov |
| */ |
| |
| #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 Entering Passive Mode (" |
| #define CLIENT_STRING "PORT " |
| |
| #define FMT_TUPLE "%pI4:%u->%pI4:%u/%u" |
| #define ARG_TUPLE(T) &(T)->src.u3.ip, ntohs((T)->src.u.all), \ |
| &(T)->dst.u3.ip, ntohs((T)->dst.u.all), \ |
| (T)->dst.protonum |
| |
| #define FMT_CONN "%pI4:%u->%pI4:%u->%pI4:%u/%u:%u" |
| #define ARG_CONN(C) &((C)->caddr.ip), ntohs((C)->cport), \ |
| &((C)->vaddr.ip), ntohs((C)->vport), \ |
| &((C)->daddr.ip), ntohs((C)->dport), \ |
| (C)->protocol, (C)->state |
| |
| /* |
| * 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 = get_unaligned((__be32 *)p); |
| *port = get_unaligned((__be16 *)(p + 4)); |
| return 1; |
| } |
| |
| /* |
| * Called from init_conntrack() as expectfn handler. |
| */ |
| static void |
| ip_vs_expect_callback(struct nf_conn *ct, |
| struct nf_conntrack_expect *exp) |
| { |
| struct nf_conntrack_tuple *orig, new_reply; |
| struct ip_vs_conn *cp; |
| |
| if (exp->tuple.src.l3num != PF_INET) |
| return; |
| |
| /* |
| * We assume that no NF locks are held before this callback. |
| * ip_vs_conn_out_get and ip_vs_conn_in_get should match their |
| * expectations even if they use wildcard values, now we provide the |
| * actual values from the newly created original conntrack direction. |
| * The conntrack is confirmed when packet reaches IPVS hooks. |
| */ |
| |
| /* RS->CLIENT */ |
| orig = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple; |
| cp = ip_vs_conn_out_get(exp->tuple.src.l3num, orig->dst.protonum, |
| &orig->src.u3, orig->src.u.tcp.port, |
| &orig->dst.u3, orig->dst.u.tcp.port); |
| if (cp) { |
| /* Change reply CLIENT->RS to CLIENT->VS */ |
| new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; |
| IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", " |
| FMT_TUPLE ", found inout cp=" FMT_CONN "\n", |
| __func__, ct, ct->status, |
| ARG_TUPLE(orig), ARG_TUPLE(&new_reply), |
| ARG_CONN(cp)); |
| new_reply.dst.u3 = cp->vaddr; |
| new_reply.dst.u.tcp.port = cp->vport; |
| IP_VS_DBG(7, "%s(): ct=%p, new tuples=" FMT_TUPLE ", " FMT_TUPLE |
| ", inout cp=" FMT_CONN "\n", |
| __func__, ct, |
| ARG_TUPLE(orig), ARG_TUPLE(&new_reply), |
| ARG_CONN(cp)); |
| goto alter; |
| } |
| |
| /* CLIENT->VS */ |
| cp = ip_vs_conn_in_get(exp->tuple.src.l3num, orig->dst.protonum, |
| &orig->src.u3, orig->src.u.tcp.port, |
| &orig->dst.u3, orig->dst.u.tcp.port); |
| if (cp) { |
| /* Change reply VS->CLIENT to RS->CLIENT */ |
| new_reply = ct->tuplehash[IP_CT_DIR_REPLY].tuple; |
| IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuples=" FMT_TUPLE ", " |
| FMT_TUPLE ", found outin cp=" FMT_CONN "\n", |
| __func__, ct, ct->status, |
| ARG_TUPLE(orig), ARG_TUPLE(&new_reply), |
| ARG_CONN(cp)); |
| new_reply.src.u3 = cp->daddr; |
| new_reply.src.u.tcp.port = cp->dport; |
| IP_VS_DBG(7, "%s(): ct=%p, new tuples=" FMT_TUPLE ", " |
| FMT_TUPLE ", outin cp=" FMT_CONN "\n", |
| __func__, ct, |
| ARG_TUPLE(orig), ARG_TUPLE(&new_reply), |
| ARG_CONN(cp)); |
| goto alter; |
| } |
| |
| IP_VS_DBG(7, "%s(): ct=%p, status=0x%lX, tuple=" FMT_TUPLE |
| " - unknown expect\n", |
| __func__, ct, ct->status, ARG_TUPLE(orig)); |
| return; |
| |
| alter: |
| /* Never alter conntrack for non-NAT conns */ |
| if (IP_VS_FWD_METHOD(cp) == IP_VS_CONN_F_MASQ) |
| nf_conntrack_alter_reply(ct, &new_reply); |
| ip_vs_conn_put(cp); |
| return; |
| } |
| |
| /* |
| * Create NF conntrack expectation with wildcard (optional) source port. |
| * Then the default callback function will alter the reply and will confirm |
| * the conntrack entry when the first packet comes. |
| */ |
| static void |
| ip_vs_expect_related(struct sk_buff *skb, struct nf_conn *ct, |
| struct ip_vs_conn *cp, u_int8_t proto, |
| const __be16 *port, int from_rs) |
| { |
| struct nf_conntrack_expect *exp; |
| |
| BUG_ON(!ct || ct == &nf_conntrack_untracked); |
| |
| exp = nf_ct_expect_alloc(ct); |
| if (!exp) |
| return; |
| |
| if (from_rs) |
| nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
| nf_ct_l3num(ct), &cp->daddr, &cp->caddr, |
| proto, port, &cp->cport); |
| else |
| nf_ct_expect_init(exp, NF_CT_EXPECT_CLASS_DEFAULT, |
| nf_ct_l3num(ct), &cp->caddr, &cp->vaddr, |
| proto, port, &cp->vport); |
| |
| exp->expectfn = ip_vs_expect_callback; |
| |
| IP_VS_DBG(7, "%s(): ct=%p, expect tuple=" FMT_TUPLE "\n", |
| __func__, ct, ARG_TUPLE(&exp->tuple)); |
| nf_ct_expect_related(exp); |
| nf_ct_expect_put(exp); |
| } |
| |
| /* |
| * 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 buf_len; |
| int ret = 0; |
| enum ip_conntrack_info ctinfo; |
| struct nf_conn *ct; |
| |
| #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 |
| |
| *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 (!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 |
| */ |
| n_cp = ip_vs_conn_out_get(AF_INET, iph->protocol, &from, port, |
| &cp->caddr, 0); |
| if (!n_cp) { |
| n_cp = ip_vs_conn_new(AF_INET, 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.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. |
| */ |
| ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo, |
| start-data, end-start, |
| buf, buf_len); |
| if (ret) |
| ip_vs_expect_related(skb, ct, n_cp, |
| IPPROTO_TCP, NULL, 0); |
| } |
| |
| /* |
| * 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; |
| |
| #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 |
| |
| /* 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 (!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 (strnicmp(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); |
| |
| n_cp = ip_vs_conn_in_get(AF_INET, iph->protocol, |
| &to, port, |
| &cp->vaddr, htons(ntohs(cp->vport)-1)); |
| if (!n_cp) { |
| n_cp = ip_vs_conn_new(AF_INET, 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; |
| pr_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"); |