#ifndef _NF_TPROXY_CORE_H #define _NF_TPROXY_CORE_H #include #include #include #include #include #include #include #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 static inline void nf_tproxy_put_sock(struct sock *sk) { /* TIME_WAIT inet sockets have to be handled differently */ if ((sk->sk_protocol == IPPROTO_TCP) && (sk->sk_state == TCP_TIME_WAIT)) inet_twsk_put(inet_twsk(sk)); else sock_put(sk); } /* assign a socket to the skb -- consumes sk */ int nf_tproxy_assign_sock(struct sk_buff *skb, struct sock *sk); #endif