![Jan Engelhardt](/assets/img/avatar_default.png)
The function signatures for Xtables extensions have grown over time. It involves a lot of typing/replication, and also a bit of stack space even if they are not used. Realize an NFWS2008 idea and pack them into structs. The skb remains outside of the struct so gcc can continue to apply its optimizations. This patch does this for match extensions' match functions. A few ambiguities have also been addressed. The "offset" parameter for example has been renamed to "fragoff" (there are so many different offsets already) and "protoff" to "thoff" (there is more than just one protocol here, so clarify). Signed-off-by: Jan Engelhardt <jengelh@medozas.de> Signed-off-by: Patrick McHardy <kaber@trash.net>
186 lines
4.6 KiB
C
186 lines
4.6 KiB
C
/*
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* Transparent proxy support for Linux/iptables
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*
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* Copyright (C) 2007-2008 BalaBit IT Ltd.
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* Author: Krisztian Kovacs
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*
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* This program is free software; you can redistribute it and/or modify
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* it under the terms of the GNU General Public License version 2 as
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* published by the Free Software Foundation.
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*
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*/
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#include <linux/module.h>
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#include <linux/skbuff.h>
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#include <linux/netfilter/x_tables.h>
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#include <linux/netfilter_ipv4/ip_tables.h>
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#include <net/tcp.h>
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#include <net/udp.h>
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#include <net/icmp.h>
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#include <net/sock.h>
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#include <net/inet_sock.h>
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#include <net/netfilter/nf_tproxy_core.h>
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#include <net/netfilter/ipv4/nf_defrag_ipv4.h>
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#if defined(CONFIG_NF_CONNTRACK) || defined(CONFIG_NF_CONNTRACK_MODULE)
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#define XT_SOCKET_HAVE_CONNTRACK 1
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#include <net/netfilter/nf_conntrack.h>
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#endif
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static int
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extract_icmp_fields(const struct sk_buff *skb,
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u8 *protocol,
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__be32 *raddr,
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__be32 *laddr,
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__be16 *rport,
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__be16 *lport)
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{
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unsigned int outside_hdrlen = ip_hdrlen(skb);
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struct iphdr *inside_iph, _inside_iph;
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struct icmphdr *icmph, _icmph;
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__be16 *ports, _ports[2];
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icmph = skb_header_pointer(skb, outside_hdrlen,
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sizeof(_icmph), &_icmph);
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if (icmph == NULL)
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return 1;
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switch (icmph->type) {
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case ICMP_DEST_UNREACH:
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case ICMP_SOURCE_QUENCH:
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case ICMP_REDIRECT:
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case ICMP_TIME_EXCEEDED:
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case ICMP_PARAMETERPROB:
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break;
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default:
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return 1;
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}
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inside_iph = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr),
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sizeof(_inside_iph), &_inside_iph);
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if (inside_iph == NULL)
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return 1;
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if (inside_iph->protocol != IPPROTO_TCP &&
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inside_iph->protocol != IPPROTO_UDP)
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return 1;
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ports = skb_header_pointer(skb, outside_hdrlen +
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sizeof(struct icmphdr) +
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(inside_iph->ihl << 2),
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sizeof(_ports), &_ports);
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if (ports == NULL)
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return 1;
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/* the inside IP packet is the one quoted from our side, thus
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* its saddr is the local address */
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*protocol = inside_iph->protocol;
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*laddr = inside_iph->saddr;
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*lport = ports[0];
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*raddr = inside_iph->daddr;
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*rport = ports[1];
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return 0;
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}
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static bool
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socket_mt(const struct sk_buff *skb, const struct xt_match_param *par)
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{
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const struct iphdr *iph = ip_hdr(skb);
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struct udphdr _hdr, *hp = NULL;
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struct sock *sk;
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__be32 daddr, saddr;
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__be16 dport, sport;
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u8 protocol;
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#ifdef XT_SOCKET_HAVE_CONNTRACK
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struct nf_conn const *ct;
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enum ip_conntrack_info ctinfo;
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#endif
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if (iph->protocol == IPPROTO_UDP || iph->protocol == IPPROTO_TCP) {
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hp = skb_header_pointer(skb, ip_hdrlen(skb),
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sizeof(_hdr), &_hdr);
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if (hp == NULL)
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return false;
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protocol = iph->protocol;
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saddr = iph->saddr;
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sport = hp->source;
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daddr = iph->daddr;
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dport = hp->dest;
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} else if (iph->protocol == IPPROTO_ICMP) {
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if (extract_icmp_fields(skb, &protocol, &saddr, &daddr,
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&sport, &dport))
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return false;
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} else {
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return false;
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}
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#ifdef XT_SOCKET_HAVE_CONNTRACK
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/* Do the lookup with the original socket address in case this is a
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* reply packet of an established SNAT-ted connection. */
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ct = nf_ct_get(skb, &ctinfo);
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if (ct && (ct != &nf_conntrack_untracked) &&
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((iph->protocol != IPPROTO_ICMP &&
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ctinfo == IP_CT_IS_REPLY + IP_CT_ESTABLISHED) ||
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(iph->protocol == IPPROTO_ICMP &&
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ctinfo == IP_CT_IS_REPLY + IP_CT_RELATED)) &&
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(ct->status & IPS_SRC_NAT_DONE)) {
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daddr = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u3.ip;
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dport = (iph->protocol == IPPROTO_TCP) ?
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.tcp.port :
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ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.u.udp.port;
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}
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#endif
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sk = nf_tproxy_get_sock_v4(dev_net(skb->dev), protocol,
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saddr, daddr, sport, dport, par->in, false);
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if (sk != NULL) {
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bool wildcard = (inet_sk(sk)->rcv_saddr == 0);
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nf_tproxy_put_sock(sk);
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if (wildcard)
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sk = NULL;
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}
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pr_debug("socket match: proto %u %08x:%u -> %08x:%u "
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"(orig %08x:%u) sock %p\n",
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protocol, ntohl(saddr), ntohs(sport),
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ntohl(daddr), ntohs(dport),
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ntohl(iph->daddr), hp ? ntohs(hp->dest) : 0, sk);
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return (sk != NULL);
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}
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static struct xt_match socket_mt_reg __read_mostly = {
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.name = "socket",
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.family = AF_INET,
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.match = socket_mt,
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.hooks = 1 << NF_INET_PRE_ROUTING,
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.me = THIS_MODULE,
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};
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static int __init socket_mt_init(void)
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{
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nf_defrag_ipv4_enable();
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return xt_register_match(&socket_mt_reg);
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}
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static void __exit socket_mt_exit(void)
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{
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xt_unregister_match(&socket_mt_reg);
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}
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module_init(socket_mt_init);
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module_exit(socket_mt_exit);
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Krisztian Kovacs, Balazs Scheidler");
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MODULE_DESCRIPTION("x_tables socket match module");
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MODULE_ALIAS("ipt_socket");
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