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 static inline void nf_tproxy_twsk_deschedule_put(struct inet_timewait_sock *tw)
21 {
22 	local_bh_disable();
23 	inet_twsk_deschedule_put(tw);
24 	local_bh_enable();
25 }
26 
27 /* assign a socket to the skb -- consumes sk */
28 static inline void nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk)
29 {
30 	skb_orphan(skb);
31 	skb->sk = sk;
32 	skb->destructor = sock_edemux;
33 }
34 
35 __be32 nf_tproxy_laddr4(struct sk_buff *skb, __be32 user_laddr, __be32 daddr);
36 
37 /**
38  * nf_tproxy_handle_time_wait4 - handle IPv4 TCP TIME_WAIT reopen redirections
39  * @net:	The network namespace.
40  * @skb:	The skb being processed.
41  * @laddr:	IPv4 address to redirect to or zero.
42  * @lport:	TCP port to redirect to or zero.
43  * @sk:		The TIME_WAIT TCP socket found by the lookup.
44  *
45  * We have to handle SYN packets arriving to TIME_WAIT sockets
46  * differently: instead of reopening the connection we should rather
47  * redirect the new connection to the proxy if there's a listener
48  * socket present.
49  *
50  * nf_tproxy_handle_time_wait4() consumes the socket reference passed in.
51  *
52  * Returns: the listener socket if there's one, the TIME_WAIT socket if
53  * no such listener is found, or NULL if the TCP header is incomplete.
54  */
55 struct sock *
56 nf_tproxy_handle_time_wait4(struct net *net, struct sk_buff *skb,
57 			    __be32 laddr, __be16 lport, struct sock *sk);
58 
59 /*
60  * This is used when the user wants to intercept a connection matching
61  * an explicit iptables rule. In this case the sockets are assumed
62  * matching in preference order:
63  *
64  *   - match: if there's a fully established connection matching the
65  *     _packet_ tuple, it is returned, assuming the redirection
66  *     already took place and we process a packet belonging to an
67  *     established connection
68  *
69  *   - match: if there's a listening socket matching the redirection
70  *     (e.g. on-port & on-ip of the connection), it is returned,
71  *     regardless if it was bound to 0.0.0.0 or an explicit
72  *     address. The reasoning is that if there's an explicit rule, it
73  *     does not really matter if the listener is bound to an interface
74  *     or to 0. The user already stated that he wants redirection
75  *     (since he added the rule).
76  *
77  * Please note that there's an overlap between what a TPROXY target
78  * and a socket match will match. Normally if you have both rules the
79  * "socket" match will be the first one, effectively all packets
80  * belonging to established connections going through that one.
81  */
82 struct sock *
83 nf_tproxy_get_sock_v4(struct net *net, struct sk_buff *skb,
84 		      const u8 protocol,
85 		      const __be32 saddr, const __be32 daddr,
86 		      const __be16 sport, const __be16 dport,
87 		      const struct net_device *in,
88 		      const enum nf_tproxy_lookup_t lookup_type);
89 
90 const struct in6_addr *
91 nf_tproxy_laddr6(struct sk_buff *skb, const struct in6_addr *user_laddr,
92 		 const struct in6_addr *daddr);
93 
94 /**
95  * nf_tproxy_handle_time_wait6 - handle IPv6 TCP TIME_WAIT reopen redirections
96  * @skb:	The skb being processed.
97  * @tproto:	Transport protocol.
98  * @thoff:	Transport protocol header offset.
99  * @net:	Network namespace.
100  * @laddr:	IPv6 address to redirect to.
101  * @lport:	TCP port to redirect to or zero.
102  * @sk:		The TIME_WAIT TCP socket found by the lookup.
103  *
104  * We have to handle SYN packets arriving to TIME_WAIT sockets
105  * differently: instead of reopening the connection we should rather
106  * redirect the new connection to the proxy if there's a listener
107  * socket present.
108  *
109  * nf_tproxy_handle_time_wait6() consumes the socket reference passed in.
110  *
111  * Returns: the listener socket if there's one, the TIME_WAIT socket if
112  * no such listener is found, or NULL if the TCP header is incomplete.
113  */
114 struct sock *
115 nf_tproxy_handle_time_wait6(struct sk_buff *skb, int tproto, int thoff,
116 			    struct net *net,
117 			    const struct in6_addr *laddr,
118 			    const __be16 lport,
119 			    struct sock *sk);
120 
121 struct sock *
122 nf_tproxy_get_sock_v6(struct net *net, struct sk_buff *skb, int thoff,
123 		      const u8 protocol,
124 		      const struct in6_addr *saddr, const struct in6_addr *daddr,
125 		      const __be16 sport, const __be16 dport,
126 		      const struct net_device *in,
127 		      const enum nf_tproxy_lookup_t lookup_type);
128 
129 #endif /* _NF_TPROXY_H_ */
130