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
nf_tproxy_sk_is_transparent(struct sock * sk)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
nf_tproxy_twsk_deschedule_put(struct inet_timewait_sock * tw)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 */
nf_tproxy_assign_sock(struct sk_buff * skb,struct sock * 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