| /* |
| * Transparent proxy support for Linux/iptables |
| * |
| * Copyright (C) 2007-2008 BalaBit IT Ltd. |
| * Author: Krisztian Kovacs |
| * |
| * This program is free software; you can redistribute it and/or modify |
| * it under the terms of the GNU General Public License version 2 as |
| * published by the Free Software Foundation. |
| * |
| */ |
| #define pr_fmt(fmt) KBUILD_MODNAME ": " fmt |
| #include <linux/module.h> |
| #include <linux/skbuff.h> |
| #include <linux/netfilter/x_tables.h> |
| #include <linux/netfilter_ipv4/ip_tables.h> |
| #include <net/tcp.h> |
| #include <net/udp.h> |
| #include <net/icmp.h> |
| #include <net/sock.h> |
| #include <net/inet_sock.h> |
| #include <net/netfilter/ipv4/nf_defrag_ipv4.h> |
| |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| #include <linux/netfilter_ipv6/ip6_tables.h> |
| #include <net/inet6_hashtables.h> |
| #include <net/netfilter/ipv6/nf_defrag_ipv6.h> |
| #endif |
| |
| #include <net/netfilter/nf_socket.h> |
| #include <linux/netfilter/xt_socket.h> |
| |
| /* "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. |
| */ |
| static bool |
| socket_match(const struct sk_buff *skb, struct xt_action_param *par, |
| const struct xt_socket_mtinfo1 *info) |
| { |
| struct sk_buff *pskb = (struct sk_buff *)skb; |
| struct sock *sk = skb->sk; |
| |
| if (!sk) |
| sk = nf_sk_lookup_slow_v4(par->net, skb, par->in); |
| if (sk) { |
| bool wildcard; |
| bool transparent = true; |
| |
| /* Ignore sockets listening on INADDR_ANY, |
| * unless XT_SOCKET_NOWILDCARD is set |
| */ |
| wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) && |
| sk_fullsock(sk) && |
| inet_sk(sk)->inet_rcv_saddr == 0); |
| |
| /* Ignore non-transparent sockets, |
| * if XT_SOCKET_TRANSPARENT is used |
| */ |
| if (info->flags & XT_SOCKET_TRANSPARENT) |
| transparent = nf_sk_is_transparent(sk); |
| |
| if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard && |
| transparent) |
| pskb->mark = sk->sk_mark; |
| |
| if (sk != skb->sk) |
| sock_gen_put(sk); |
| |
| if (wildcard || !transparent) |
| sk = NULL; |
| } |
| |
| return sk != NULL; |
| } |
| |
| static bool |
| socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) |
| { |
| static struct xt_socket_mtinfo1 xt_info_v0 = { |
| .flags = 0, |
| }; |
| |
| return socket_match(skb, par, &xt_info_v0); |
| } |
| |
| static bool |
| socket_mt4_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) |
| { |
| return socket_match(skb, par, par->matchinfo); |
| } |
| |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| static bool |
| socket_mt6_v1_v2_v3(const struct sk_buff *skb, struct xt_action_param *par) |
| { |
| const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; |
| struct sk_buff *pskb = (struct sk_buff *)skb; |
| struct sock *sk = skb->sk; |
| |
| if (!sk) |
| sk = nf_sk_lookup_slow_v6(par->net, skb, par->in); |
| if (sk) { |
| bool wildcard; |
| bool transparent = true; |
| |
| /* Ignore sockets listening on INADDR_ANY |
| * unless XT_SOCKET_NOWILDCARD is set |
| */ |
| wildcard = (!(info->flags & XT_SOCKET_NOWILDCARD) && |
| sk_fullsock(sk) && |
| ipv6_addr_any(&sk->sk_v6_rcv_saddr)); |
| |
| /* Ignore non-transparent sockets, |
| * if XT_SOCKET_TRANSPARENT is used |
| */ |
| if (info->flags & XT_SOCKET_TRANSPARENT) |
| transparent = nf_sk_is_transparent(sk); |
| |
| if (info->flags & XT_SOCKET_RESTORESKMARK && !wildcard && |
| transparent) |
| pskb->mark = sk->sk_mark; |
| |
| if (sk != skb->sk) |
| sock_gen_put(sk); |
| |
| if (wildcard || !transparent) |
| sk = NULL; |
| } |
| |
| return sk != NULL; |
| } |
| #endif |
| |
| static int socket_mt_v1_check(const struct xt_mtchk_param *par) |
| { |
| const struct xt_socket_mtinfo1 *info = (struct xt_socket_mtinfo1 *) par->matchinfo; |
| |
| if (info->flags & ~XT_SOCKET_FLAGS_V1) { |
| pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V1); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| static int socket_mt_v2_check(const struct xt_mtchk_param *par) |
| { |
| const struct xt_socket_mtinfo2 *info = (struct xt_socket_mtinfo2 *) par->matchinfo; |
| |
| if (info->flags & ~XT_SOCKET_FLAGS_V2) { |
| pr_info("unknown flags 0x%x\n", info->flags & ~XT_SOCKET_FLAGS_V2); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| static int socket_mt_v3_check(const struct xt_mtchk_param *par) |
| { |
| const struct xt_socket_mtinfo3 *info = |
| (struct xt_socket_mtinfo3 *)par->matchinfo; |
| |
| if (info->flags & ~XT_SOCKET_FLAGS_V3) { |
| pr_info("unknown flags 0x%x\n", |
| info->flags & ~XT_SOCKET_FLAGS_V3); |
| return -EINVAL; |
| } |
| return 0; |
| } |
| |
| static struct xt_match socket_mt_reg[] __read_mostly = { |
| { |
| .name = "socket", |
| .revision = 0, |
| .family = NFPROTO_IPV4, |
| .match = socket_mt4_v0, |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| { |
| .name = "socket", |
| .revision = 1, |
| .family = NFPROTO_IPV4, |
| .match = socket_mt4_v1_v2_v3, |
| .checkentry = socket_mt_v1_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| { |
| .name = "socket", |
| .revision = 1, |
| .family = NFPROTO_IPV6, |
| .match = socket_mt6_v1_v2_v3, |
| .checkentry = socket_mt_v1_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #endif |
| { |
| .name = "socket", |
| .revision = 2, |
| .family = NFPROTO_IPV4, |
| .match = socket_mt4_v1_v2_v3, |
| .checkentry = socket_mt_v2_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| { |
| .name = "socket", |
| .revision = 2, |
| .family = NFPROTO_IPV6, |
| .match = socket_mt6_v1_v2_v3, |
| .checkentry = socket_mt_v2_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #endif |
| { |
| .name = "socket", |
| .revision = 3, |
| .family = NFPROTO_IPV4, |
| .match = socket_mt4_v1_v2_v3, |
| .checkentry = socket_mt_v3_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| { |
| .name = "socket", |
| .revision = 3, |
| .family = NFPROTO_IPV6, |
| .match = socket_mt6_v1_v2_v3, |
| .checkentry = socket_mt_v3_check, |
| .matchsize = sizeof(struct xt_socket_mtinfo1), |
| .hooks = (1 << NF_INET_PRE_ROUTING) | |
| (1 << NF_INET_LOCAL_IN), |
| .me = THIS_MODULE, |
| }, |
| #endif |
| }; |
| |
| static int __init socket_mt_init(void) |
| { |
| nf_defrag_ipv4_enable(); |
| #if IS_ENABLED(CONFIG_IP6_NF_IPTABLES) |
| nf_defrag_ipv6_enable(); |
| #endif |
| |
| return xt_register_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
| } |
| |
| static void __exit socket_mt_exit(void) |
| { |
| xt_unregister_matches(socket_mt_reg, ARRAY_SIZE(socket_mt_reg)); |
| } |
| |
| module_init(socket_mt_init); |
| module_exit(socket_mt_exit); |
| |
| MODULE_LICENSE("GPL"); |
| MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler"); |
| MODULE_DESCRIPTION("x_tables socket match module"); |
| MODULE_ALIAS("ipt_socket"); |
| MODULE_ALIAS("ip6t_socket"); |