/*
* 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;
struct net *net;
#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
*/
{
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);
n_cp = ip_vs_conn_new(&p, &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.
*/
ret = nf_nat_mangle_tcp_packet(skb, ct, ctinfo,
start-data, end-start,
buf, buf_len);
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;
}
/*
* 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;
__u32 from;
__u16 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(1-debug, "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),
port&255, (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;
}
/*
* 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;
#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 (%u.%u.%u.%u:%d) -> "
"%u.%u.%u.%u:%d detected\n",
NIPQUAD(from.ip), ntohs(port),
NIPQUAD(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;
sprintf(buf, "%d,%d,%d,%d,%d,%d", NIPQUAD(from.ip),
(ntohs(port)>>8)&255, ntohs(port)&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(skb, 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;
}
