--- /dev/null
+/*
+ * 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;
+ struct net *net;
+
+ *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(ip_vs_conn_net(cp), 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(ip_vs_conn_net(cp),
+ 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.
+ */
+
+ net = skb_net(skb);
+ cp->app_data = NULL;
+ ip_vs_tcp_conn_listen(net, 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;
+ struct net *net;
+
+ /* 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(ip_vs_conn_net(cp), 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
+ */
+ net = skb_net(skb);
+ ip_vs_tcp_conn_listen(net, 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(net, &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(net, 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(net, &ip_vs_ftp);
+ return ret;
+}
+/*
+ * netns exit
+ */
+static void __ip_vs_ftp_exit(struct net *net)
+{
+ unregister_ip_vs_app(net, &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");
Code Review / kvmfornfv.git / blobdiff