1 #ifndef _NF_TPROXY_H_
2 #define _NF_TPROXY_H_
3
4 #include <net/tcp.h>
5
6 enum nf_tproxy_lookup_t {
7 NF_TPROXY_LOOKUP_LISTENER,
8 NF_TPROXY_LOOKUP_ESTABLISHED,
9 };
10
11 static inline bool nf_tproxy_sk_is_transparent(struct sock *sk)
12 {
13 if (inet_sk_transparent(sk))
14 return true;
15
16 sock_gen_put(sk);
17 return false;
18 }
19
20 /* assign a socket to the skb -- consumes sk */
21 static inline void nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
22 {
23 skb_orphan(skb);
24 skb->sk = sk;
25 skb->destructor = sock_edemux;
26 }
27
28 __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr);
29
30 /**
31 * nf_tproxy_handle_time_wait4 - handle IPv4 TCP TIME_WAIT reopen redirections
32 * @skb: The skb being processed.
33 * @laddr: IPv4 address to redirect to or zero.
34 * @lport: TCP port to redirect to or zero.
35 * @sk: The TIME_WAIT TCP socket found by the lookup.
36 *
37 * We have to handle SYN packets arriving to TIME_WAIT sockets
38 * differently: instead of reopening the connection we should rather
39 * redirect the new connection to the proxy if there's a listener
40 * socket present.
41 *
42 * nf_tproxy_handle_time_wait4() consumes the socket reference passed in.
43 *
44 * Returns the listener socket if there's one, the TIME_WAIT socket if
45 * no such listener is found, or NULL if the TCP header is incomplete.
46 */
47 struct sock *
48 nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
49 __be32 laddr, __be16 lport, struct sock *sk);
50
51 /*
52 * This is used when the user wants to intercept a connection matching
53 * an explicit iptables rule. In this case the sockets are assumed
54 * matching in preference order:
55 *
56 * - match: if there's a fully established connection matching the
57 * _packet_ tuple, it is returned, assuming the redirection
58 * already took place and we process a packet belonging to an
59 * established connection
60 *
61 * - match: if there's a listening socket matching the redirection
62 * (e.g. on-port & on-ip of the connection), it is returned,
63 * regardless if it was bound to 0.0.0.0 or an explicit
64 * address. The reasoning is that if there's an explicit rule, it
65 * does not really matter if the listener is bound to an interface
66 * or to 0. The user already stated that he wants redirection
67 * (since he added the rule).
68 *
69 * Please note that there's an overlap between what a TPROXY target
70 * and a socket match will match. Normally if you have both rules the
71 * "socket" match will be the first one, effectively all packets
72 * belonging to established connections going through that one.
73 */
74 struct sock *
75 nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
76 const u8 protocol,
77 const __be32 saddr, const __be32 daddr,
78 const __be16 sport, const __be16 dport,
79 const struct net_device *in,
80 const enum nf_tproxy_lookup_t lookup_type);
81
82 const struct in6_addr *
83 nf_tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
84 const struct in6_addr *daddr);
85
86 /**
87 * nf_tproxy_handle_time_wait6 - handle IPv6 TCP TIME_WAIT reopen redirections
88 * @skb: The skb being processed.
89 * @tproto: Transport protocol.
90 * @thoff: Transport protocol header offset.
91 * @net: Network namespace.
92 * @laddr: IPv6 address to redirect to.
93 * @lport: TCP port to redirect to or zero.
94 * @sk: The TIME_WAIT TCP socket found by the lookup.
95 *
96 * We have to handle SYN packets arriving to TIME_WAIT sockets
97 * differently: instead of reopening the connection we should rather
98 * redirect the new connection to the proxy if there's a listener
99 * socket present.
100 *
101 * nf_tproxy_handle_time_wait6() consumes the socket reference passed in.
102 *
103 * Returns the listener socket if there's one, the TIME_WAIT socket if
104 * no such listener is found, or NULL if the TCP header is incomplete.
105 */
106 struct sock *
107 nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
108 struct net *net,
109 const struct in6_addr *laddr,
110 const __be16 lport,
111 struct sock *sk);
112
113 struct sock *
114 nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
115 const u8 protocol,
116 const struct in6_addr *saddr, const struct in6_addr *daddr,
117 const __be16 sport, const __be16 dport,
118 const struct net_device *in,
119 const enum nf_tproxy_lookup_t lookup_type);
120
121 #endif /* _NF_TPROXY_H_ */