diff options
Diffstat (limited to 'net/netfilter/xt_socket.c')
| -rw-r--r-- | net/netfilter/xt_socket.c | 404 |
1 files changed, 404 insertions, 0 deletions
diff --git a/net/netfilter/xt_socket.c b/net/netfilter/xt_socket.c new file mode 100644 index 00000000..ddf5e050 --- /dev/null +++ b/net/netfilter/xt_socket.c @@ -0,0 +1,404 @@ +/* + * 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/nf_tproxy_core.h> +#include <net/netfilter/ipv4/nf_defrag_ipv4.h> + +#if defined(CONFIG_IP6_NF_IPTABLES) || defined(CONFIG_IP6_NF_IPTABLES_MODULE) +#define XT_SOCKET_HAVE_IPV6 1 +#include <linux/netfilter_ipv6/ip6_tables.h> +#include <net/netfilter/ipv6/nf_defrag_ipv6.h> +#endif + +#include <linux/netfilter/xt_socket.h> + +#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE) +#define XT_SOCKET_HAVE_CONNTRACK 1 +#include <net/netfilter/nf_conntrack.h> +#endif + +void +xt_socket_put_sk(struct sock *sk) +{ + if (sk->sk_state == TCP_TIME_WAIT) + inet_twsk_put(inet_twsk(sk)); + else + sock_put(sk); +} +EXPORT_SYMBOL(xt_socket_put_sk); + +static int +extract_icmp4_fields(const struct sk_buff *skb, + u8 *protocol, + __be32 *raddr, + __be32 *laddr, + __be16 *rport, + __be16 *lport) +{ + unsigned int outside_hdrlen = ip_hdrlen(skb); + struct iphdr *inside_iph, _inside_iph; + struct icmphdr *icmph, _icmph; + __be16 *ports, _ports[2]; + + icmph = skb_header_pointer(skb, outside_hdrlen, + sizeof(_icmph), &_icmph); + if (icmph == NULL) + return 1; + + switch (icmph->type) { + case ICMP_DEST_UNREACH: + case ICMP_SOURCE_QUENCH: + case ICMP_REDIRECT: + case ICMP_TIME_EXCEEDED: + case ICMP_PARAMETERPROB: + break; + default: + return 1; + } + + inside_iph = skb_header_pointer(skb, outside_hdrlen + + sizeof(struct icmphdr), + sizeof(_inside_iph), &_inside_iph); + if (inside_iph == NULL) + return 1; + + if (inside_iph->protocol != IPPROTO_TCP && + inside_iph->protocol != IPPROTO_UDP) + return 1; + + ports = skb_header_pointer(skb, outside_hdrlen + + sizeof(struct icmphdr) + + (inside_iph->ihl << 2), + sizeof(_ports), &_ports); + if (ports == NULL) + return 1; + + /* the inside IP packet is the one quoted from our side, thus + * its saddr is the local address */ + *protocol = inside_iph->protocol; + *laddr = inside_iph->saddr; + *lport = ports[0]; + *raddr = inside_iph->daddr; + *rport = ports[1]; + + return 0; +} + +struct sock* +xt_socket_get4_sk(const struct sk_buff *skb, struct xt_action_param *par) +{ + const struct iphdr *iph = ip_hdr(skb); + struct udphdr _hdr, *hp = NULL; + struct sock *sk; + __be32 daddr, saddr; + __be16 dport, sport; + u8 protocol; +#ifdef XT_SOCKET_HAVE_CONNTRACK + struct nf_conn const *ct; + enum ip_conntrack_info ctinfo; +#endif + + if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) { + hp = skb_header_pointer(skb, ip_hdrlen(skb), + sizeof(_hdr), &_hdr); + if (hp == NULL) + return NULL; + + protocol = iph->protocol; + saddr = iph->saddr; + sport = hp->source; + daddr = iph->daddr; + dport = hp->dest; + + } else if (iph->protocol == IPPROTO_ICMP) { + if (extract_icmp4_fields(skb, &protocol, &saddr, &daddr, + &sport, &dport)) + return NULL; + } else { + return NULL; + } + +#ifdef XT_SOCKET_HAVE_CONNTRACK + /* Do the lookup with the original socket address in case this is a + * reply packet of an established SNAT-ted connection. */ + + ct = nf_ct_get(skb, &ctinfo); + if (ct && !nf_ct_is_untracked(ct) && + ((iph->protocol != IPPROTO_ICMP && + ctinfo == IP_CT_ESTABLISHED_REPLY) || + (iph->protocol == IPPROTO_ICMP && + ctinfo == IP_CT_RELATED_REPLY)) && + (ct->status & IPS_SRC_NAT_DONE)) { + + daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip; + dport = (iph->protocol == IPPROTO_TCP) ? + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port : + ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port; + } +#endif + + sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol, + saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); + + pr_debug("proto %hhu %pI4:%hu -> %pI4:%hu (orig %pI4:%hu) sock %p\n", + protocol, &saddr, ntohs(sport), + &daddr, ntohs(dport), + &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); + + return sk; +} +EXPORT_SYMBOL(xt_socket_get4_sk); + +static bool +socket_match(const struct sk_buff *skb, struct xt_action_param *par, + const struct xt_socket_mtinfo1 *info) +{ + struct sock *sk; + + sk = xt_socket_get4_sk(skb, par); + if (sk != NULL) { + bool wildcard; + bool transparent = true; + + /* Ignore sockets listening on INADDR_ANY */ + wildcard = (sk->sk_state != TCP_TIME_WAIT && + inet_sk(sk)->inet_rcv_saddr == 0); + + /* Ignore non-transparent sockets, + if XT_SOCKET_TRANSPARENT is used */ + if (info && info->flags & XT_SOCKET_TRANSPARENT) + transparent = ((sk->sk_state != TCP_TIME_WAIT && + inet_sk(sk)->transparent) || + (sk->sk_state == TCP_TIME_WAIT && + inet_twsk(sk)->tw_transparent)); + + xt_socket_put_sk(sk); + + if (wildcard || !transparent) + sk = NULL; + } + + return (sk != NULL); +} + +static bool +socket_mt4_v0(const struct sk_buff *skb, struct xt_action_param *par) +{ + return socket_match(skb, par, NULL); +} + +static bool +socket_mt4_v1(const struct sk_buff *skb, struct xt_action_param *par) +{ + return socket_match(skb, par, par->matchinfo); +} + +#ifdef XT_SOCKET_HAVE_IPV6 + +static int +extract_icmp6_fields(const struct sk_buff *skb, + unsigned int outside_hdrlen, + int *protocol, + struct in6_addr **raddr, + struct in6_addr **laddr, + __be16 *rport, + __be16 *lport) +{ + struct ipv6hdr *inside_iph, _inside_iph; + struct icmp6hdr *icmph, _icmph; + __be16 *ports, _ports[2]; + u8 inside_nexthdr; + int inside_hdrlen; + + icmph = skb_header_pointer(skb, outside_hdrlen, + sizeof(_icmph), &_icmph); + if (icmph == NULL) + return 1; + + if (icmph->icmp6_type & ICMPV6_INFOMSG_MASK) + return 1; + + inside_iph = skb_header_pointer(skb, outside_hdrlen + sizeof(_icmph), sizeof(_inside_iph), &_inside_iph); + if (inside_iph == NULL) + return 1; + inside_nexthdr = inside_iph->nexthdr; + + inside_hdrlen = ipv6_skip_exthdr(skb, outside_hdrlen + sizeof(_icmph) + sizeof(_inside_iph), &inside_nexthdr); + if (inside_hdrlen < 0) + return 1; /* hjm: Packet has no/incomplete transport layer headers. */ + + if (inside_nexthdr != IPPROTO_TCP && + inside_nexthdr != IPPROTO_UDP) + return 1; + + ports = skb_header_pointer(skb, inside_hdrlen, + sizeof(_ports), &_ports); + if (ports == NULL) + return 1; + + /* the inside IP packet is the one quoted from our side, thus + * its saddr is the local address */ + *protocol = inside_nexthdr; + *laddr = &inside_iph->saddr; + *lport = ports[0]; + *raddr = &inside_iph->daddr; + *rport = ports[1]; + + return 0; +} + +struct sock* +xt_socket_get6_sk(const struct sk_buff *skb, struct xt_action_param *par) +{ + struct ipv6hdr *iph = ipv6_hdr(skb); + struct udphdr _hdr, *hp = NULL; + struct sock *sk; + struct in6_addr *daddr, *saddr; + __be16 dport, sport; + int thoff, tproto; + + tproto = ipv6_find_hdr(skb, &thoff, -1, NULL); + if (tproto < 0) { + pr_debug("unable to find transport header in IPv6 packet, dropping\n"); + return NF_DROP; + } + + if (tproto == IPPROTO_UDP || tproto == IPPROTO_TCP) { + hp = skb_header_pointer(skb, thoff, + sizeof(_hdr), &_hdr); + if (hp == NULL) + return NULL; + + saddr = &iph->saddr; + sport = hp->source; + daddr = &iph->daddr; + dport = hp->dest; + + } else if (tproto == IPPROTO_ICMPV6) { + if (extract_icmp6_fields(skb, thoff, &tproto, &saddr, &daddr, + &sport, &dport)) + return NULL; + } else { + return NULL; + } + + sk = nf_tproxy_get_sock_v6(dev_net(skb->dev), tproto, + saddr, daddr, sport, dport, par->in, NFT_LOOKUP_ANY); + pr_debug("proto %hhd %pI6:%hu -> %pI6:%hu " + "(orig %pI6:%hu) sock %p\n", + tproto, saddr, ntohs(sport), + daddr, ntohs(dport), + &iph->daddr, hp ? ntohs(hp->dest) : 0, sk); + return sk; +} +EXPORT_SYMBOL(xt_socket_get6_sk); + +static bool +socket_mt6_v1(const struct sk_buff *skb, struct xt_action_param *par) +{ + struct sock *sk; + const struct xt_socket_mtinfo1 *info; + + info = (struct xt_socket_mtinfo1 *) par->matchinfo; + sk = xt_socket_get6_sk(skb, par); + if (sk != NULL) { + bool wildcard; + bool transparent = true; + + /* Ignore sockets listening on INADDR_ANY */ + wildcard = (sk->sk_state != TCP_TIME_WAIT && + ipv6_addr_any(&inet6_sk(sk)->rcv_saddr)); + + /* Ignore non-transparent sockets, + if XT_SOCKET_TRANSPARENT is used */ + if (info && info->flags & XT_SOCKET_TRANSPARENT) + transparent = ((sk->sk_state != TCP_TIME_WAIT && + inet_sk(sk)->transparent) || + (sk->sk_state == TCP_TIME_WAIT && + inet_twsk(sk)->tw_transparent)); + + xt_socket_put_sk(sk); + + if (wildcard || !transparent) + sk = NULL; + } + + return (sk != NULL); +} +#endif + +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, + .matchsize = sizeof(struct xt_socket_mtinfo1), + .hooks = (1 << NF_INET_PRE_ROUTING) | + (1 << NF_INET_LOCAL_IN), + .me = THIS_MODULE, + }, +#ifdef XT_SOCKET_HAVE_IPV6 + { + .name = "socket", + .revision = 1, + .family = NFPROTO_IPV6, + .match = socket_mt6_v1, + .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(); +#ifdef XT_SOCKET_HAVE_IPV6 + 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"); |