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#ifndef _NF_TPROXY_CORE_H
#define _NF_TPROXY_CORE_H
#include <linux/types.h>
#include <linux/in.h>
#include <linux/skbuff.h>
#include <net/sock.h>
#include <net/inet_hashtables.h>
#include <net/inet6_hashtables.h>
#include <net/tcp.h>
#define NFT_LOOKUP_ANY 0
#define NFT_LOOKUP_LISTENER 1
#define NFT_LOOKUP_ESTABLISHED 2
/* look up and get a reference to a matching socket */
/* This function is used by the 'TPROXY' target and the 'socket'
* match. The following lookups are supported:
*
* Explicit TProxy target rule
* ===========================
*
* This is used when the user wants to intercept a connection matching
* an explicit iptables rule. In this case the sockets are assumed
* matching in preference order:
*
* - match: if there's a fully established connection matching the
* _packet_ tuple, it is returned, assuming the redirection
* already took place and we process a packet belonging to an
* established connection
*
* - match: if there's a listening socket matching the redirection
* (e.g. on-port & on-ip of the connection), it is returned,
* regardless if it was bound to 0.0.0.0 or an explicit
* address. The reasoning is that if there's an explicit rule, it
* does not really matter if the listener is bound to an interface
* or to 0. The user already stated that he wants redirection
* (since he added the rule).
*
* "socket" match based redirection (no specific rule)
* ===================================================
*
* There are connections with dynamic endpoints (e.g. FTP data
* connection) that the user is unable to add explicit rules
* for. These are taken care of by a generic "socket" rule. It is
* assumed that the proxy application is trusted to open such
* connections without explicit iptables rule (except of course the
* generic 'socket' rule). In this case the following sockets are
* matched in preference order:
*
* - match: if there's a fully established connection matching the
* _packet_ tuple
*
* - match: if there's a non-zero bound listener (possibly with a
* non-local address) We don't accept zero-bound listeners, since
* then local services could intercept traffic going through the
* box.
*
* Please note that there's an overlap between what a TPROXY target
* and a socket match will match. Normally if you have both rules the
* "socket" match will be the first one, effectively all packets
* belonging to established connections going through that one.
*/
static inline struct sock *
nf_tproxy_get_sock_v4(struct net *net, const u8 protocol,
const __be32 saddr, const __be32 daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in, int lookup_type)
{
struct sock *sk;
/* look up socket */
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NFT_LOOKUP_ANY:
sk = __inet_lookup(net, &tcp_hashinfo,
saddr, sport, daddr, dport,
in->ifindex);
break;
case NFT_LOOKUP_LISTENER:
sk = inet_lookup_listener(net, &tcp_hashinfo,
daddr, dport,
in->ifindex);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too */
break;
case NFT_LOOKUP_ESTABLISHED:
sk = inet_lookup_established(net, &tcp_hashinfo,
saddr, sport, daddr, dport,
in->ifindex);
break;
default:
WARN_ON(1);
sk = NULL;
break;
}
break;
case IPPROTO_UDP:
sk = udp4_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
if (sk && lookup_type != NFT_LOOKUP_ANY) {
int connected = (sk->sk_state == TCP_ESTABLISHED);
int wildcard = (inet_sk(sk)->inet_rcv_saddr == 0);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too */
if ((lookup_type == NFT_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
(lookup_type == NFT_LOOKUP_LISTENER && connected)) {
sock_put(sk);
sk = NULL;
}
}
break;
default:
WARN_ON(1);
sk = NULL;
}
pr_debug("tproxy socket lookup: proto %u %08x:%u -> %08x:%u, lookup type: %d, sock %p\n",
protocol, ntohl(saddr), ntohs(sport), ntohl(daddr), ntohs(dport), lookup_type, sk);
return sk;
}
#if defined(CONFIG_IPV6) || defined(CONFIG_IPV6_MODULE)
static inline struct sock *
nf_tproxy_get_sock_v6(struct net *net, const u8 protocol,
const struct in6_addr *saddr, const struct in6_addr *daddr,
const __be16 sport, const __be16 dport,
const struct net_device *in, int lookup_type)
{
struct sock *sk;
/* look up socket */
switch (protocol) {
case IPPROTO_TCP:
switch (lookup_type) {
case NFT_LOOKUP_ANY:
sk = inet6_lookup(net, &tcp_hashinfo,
saddr, sport, daddr, dport,
in->ifindex);
break;
case NFT_LOOKUP_LISTENER:
sk = inet6_lookup_listener(net, &tcp_hashinfo,
daddr, ntohs(dport),
in->ifindex);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too */
break;
case NFT_LOOKUP_ESTABLISHED:
sk = __inet6_lookup_established(net, &tcp_hashinfo,
saddr, sport, daddr, ntohs(dport),
in->ifindex);
break;
default:
WARN_ON(1);
sk = NULL;
break;
}
break;
case IPPROTO_UDP:
sk = udp6_lib_lookup(net, saddr, sport, daddr, dport,
in->ifindex);
if (sk && lookup_type != NFT_LOOKUP_ANY) {
int connected = (sk->sk_state == TCP_ESTABLISHED);
int wildcard = ipv6_addr_any(&inet6_sk(sk)->rcv_saddr);
/* NOTE: we return listeners even if bound to
* 0.0.0.0, those are filtered out in
* xt_socket, since xt_TPROXY needs 0 bound
* listeners too */
if ((lookup_type == NFT_LOOKUP_ESTABLISHED && (!connected || wildcard)) ||
(lookup_type == NFT_LOOKUP_LISTENER && connected)) {
sock_put(sk);
sk = NULL;
}
}
break;
default:
WARN_ON(1);
sk = NULL;
}
pr_debug("tproxy socket lookup: proto %u %pI6:%u -> %pI6:%u, lookup type: %d, sock %p\n",
protocol, saddr, ntohs(sport), daddr, ntohs(dport), lookup_type, sk);
return sk;
}
#endif
/* assign a socket to the skb -- consumes sk */
void
nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk);
#endif
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