![Patrick McHardy](/assets/img/avatar_default.png)
Since conntrack currently allows to use masks for every bit of both helper and expectation tuples, we can't hash them and have to keep them on two global lists that are searched for every new connection. This patch removes the never used ability to use masks for the destination part of the expectation tuple and completely removes masks from helpers since the only reasonable choice is a full match on l3num, protonum and src.u.all. Signed-off-by: Patrick McHardy <kaber@trash.net> Signed-off-by: David S. Miller <davem@davemloft.net>
239 lines
6.1 KiB
C
239 lines
6.1 KiB
C
/* SANE connection tracking helper
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* (SANE = Scanner Access Now Easy)
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* For documentation about the SANE network protocol see
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* http://www.sane-project.org/html/doc015.html
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*/
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/* Copyright (C) 2007 Red Hat, Inc.
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* Author: Michal Schmidt <mschmidt@redhat.com>
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* Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
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* (C) 1999-2001 Paul `Rusty' Russell
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* (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
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* (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
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* (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
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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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#include <linux/module.h>
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#include <linux/moduleparam.h>
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#include <linux/netfilter.h>
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#include <linux/in.h>
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#include <linux/tcp.h>
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#include <net/netfilter/nf_conntrack.h>
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#include <net/netfilter/nf_conntrack_helper.h>
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#include <net/netfilter/nf_conntrack_expect.h>
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#include <linux/netfilter/nf_conntrack_sane.h>
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MODULE_LICENSE("GPL");
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MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
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MODULE_DESCRIPTION("SANE connection tracking helper");
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static char *sane_buffer;
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static DEFINE_SPINLOCK(nf_sane_lock);
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#define MAX_PORTS 8
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static u_int16_t ports[MAX_PORTS];
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static unsigned int ports_c;
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module_param_array(ports, ushort, &ports_c, 0400);
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#if 0
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#define DEBUGP printk
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#else
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#define DEBUGP(format, args...)
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#endif
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struct sane_request {
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__be32 RPC_code;
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#define SANE_NET_START 7 /* RPC code */
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__be32 handle;
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};
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struct sane_reply_net_start {
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__be32 status;
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#define SANE_STATUS_SUCCESS 0
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__be16 zero;
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__be16 port;
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/* other fields aren't interesting for conntrack */
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};
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static int help(struct sk_buff **pskb,
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unsigned int protoff,
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struct nf_conn *ct,
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enum ip_conntrack_info ctinfo)
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{
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unsigned int dataoff, datalen;
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struct tcphdr _tcph, *th;
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char *sb_ptr;
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int ret = NF_ACCEPT;
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int dir = CTINFO2DIR(ctinfo);
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struct nf_ct_sane_master *ct_sane_info;
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struct nf_conntrack_expect *exp;
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struct nf_conntrack_tuple *tuple;
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struct sane_request *req;
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struct sane_reply_net_start *reply;
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int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
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ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
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/* Until there's been traffic both ways, don't look in packets. */
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if (ctinfo != IP_CT_ESTABLISHED &&
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ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
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return NF_ACCEPT;
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/* Not a full tcp header? */
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th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
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if (th == NULL)
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return NF_ACCEPT;
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/* No data? */
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dataoff = protoff + th->doff * 4;
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if (dataoff >= (*pskb)->len)
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return NF_ACCEPT;
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datalen = (*pskb)->len - dataoff;
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spin_lock_bh(&nf_sane_lock);
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sb_ptr = skb_header_pointer(*pskb, dataoff, datalen, sane_buffer);
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BUG_ON(sb_ptr == NULL);
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if (dir == IP_CT_DIR_ORIGINAL) {
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if (datalen != sizeof(struct sane_request))
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goto out;
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req = (struct sane_request *)sb_ptr;
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if (req->RPC_code != htonl(SANE_NET_START)) {
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/* Not an interesting command */
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ct_sane_info->state = SANE_STATE_NORMAL;
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goto out;
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}
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/* We're interested in the next reply */
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ct_sane_info->state = SANE_STATE_START_REQUESTED;
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goto out;
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}
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/* Is it a reply to an uninteresting command? */
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if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
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goto out;
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/* It's a reply to SANE_NET_START. */
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ct_sane_info->state = SANE_STATE_NORMAL;
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if (datalen < sizeof(struct sane_reply_net_start)) {
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DEBUGP("nf_ct_sane: NET_START reply too short\n");
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goto out;
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}
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reply = (struct sane_reply_net_start *)sb_ptr;
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if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
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/* saned refused the command */
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DEBUGP("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
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ntohl(reply->status));
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goto out;
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}
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/* Invalid saned reply? Ignore it. */
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if (reply->zero != 0)
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goto out;
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exp = nf_ct_expect_alloc(ct);
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if (exp == NULL) {
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ret = NF_DROP;
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goto out;
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}
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tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
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nf_ct_expect_init(exp, family, &tuple->src.u3, &tuple->dst.u3,
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IPPROTO_TCP, NULL, &reply->port);
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DEBUGP("nf_ct_sane: expect: ");
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NF_CT_DUMP_TUPLE(&exp->tuple);
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NF_CT_DUMP_TUPLE(&exp->mask);
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/* Can't expect this? Best to drop packet now. */
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if (nf_ct_expect_related(exp) != 0)
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ret = NF_DROP;
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nf_ct_expect_put(exp);
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out:
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spin_unlock_bh(&nf_sane_lock);
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return ret;
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}
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static struct nf_conntrack_helper sane[MAX_PORTS][2];
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static char sane_names[MAX_PORTS][2][sizeof("sane-65535")];
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/* don't make this __exit, since it's called from __init ! */
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static void nf_conntrack_sane_fini(void)
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{
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int i, j;
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for (i = 0; i < ports_c; i++) {
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for (j = 0; j < 2; j++) {
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DEBUGP("nf_ct_sane: unregistering helper for pf: %d "
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"port: %d\n",
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sane[i][j].tuple.src.l3num, ports[i]);
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nf_conntrack_helper_unregister(&sane[i][j]);
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}
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}
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kfree(sane_buffer);
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}
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static int __init nf_conntrack_sane_init(void)
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{
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int i, j = -1, ret = 0;
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char *tmpname;
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sane_buffer = kmalloc(65536, GFP_KERNEL);
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if (!sane_buffer)
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return -ENOMEM;
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if (ports_c == 0)
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ports[ports_c++] = SANE_PORT;
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/* FIXME should be configurable whether IPv4 and IPv6 connections
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are tracked or not - YK */
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for (i = 0; i < ports_c; i++) {
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sane[i][0].tuple.src.l3num = PF_INET;
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sane[i][1].tuple.src.l3num = PF_INET6;
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for (j = 0; j < 2; j++) {
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sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
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sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
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sane[i][j].max_expected = 1;
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sane[i][j].timeout = 5 * 60; /* 5 Minutes */
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sane[i][j].me = THIS_MODULE;
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sane[i][j].help = help;
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tmpname = &sane_names[i][j][0];
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if (ports[i] == SANE_PORT)
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sprintf(tmpname, "sane");
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else
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sprintf(tmpname, "sane-%d", ports[i]);
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sane[i][j].name = tmpname;
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DEBUGP("nf_ct_sane: registering helper for pf: %d "
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"port: %d\n",
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sane[i][j].tuple.src.l3num, ports[i]);
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ret = nf_conntrack_helper_register(&sane[i][j]);
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if (ret) {
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printk(KERN_ERR "nf_ct_sane: failed to "
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"register helper for pf: %d port: %d\n",
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sane[i][j].tuple.src.l3num, ports[i]);
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nf_conntrack_sane_fini();
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return ret;
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}
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}
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}
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return 0;
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}
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module_init(nf_conntrack_sane_init);
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module_exit(nf_conntrack_sane_fini);
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