--- /dev/null
+/* SANE connection tracking helper
+ * (SANE = Scanner Access Now Easy)
+ * For documentation about the SANE network protocol see
+ * http://www.sane-project.org/html/doc015.html
+ */
+
+/* Copyright (C) 2007 Red Hat, Inc.
+ * Author: Michal Schmidt <mschmidt@redhat.com>
+ * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c):
+ * (C) 1999-2001 Paul `Rusty' Russell
+ * (C) 2002-2004 Netfilter Core Team <coreteam@netfilter.org>
+ * (C) 2003,2004 USAGI/WIDE Project <http://www.linux-ipv6.org>
+ * (C) 2003 Yasuyuki Kozakai @USAGI <yasuyuki.kozakai@toshiba.co.jp>
+ *
+ * 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.
+ */
+
+#include <linux/module.h>
+#include <linux/moduleparam.h>
+#include <linux/netfilter.h>
+#include <linux/in.h>
+#include <linux/tcp.h>
+#include <net/netfilter/nf_conntrack.h>
+#include <net/netfilter/nf_conntrack_helper.h>
+#include <net/netfilter/nf_conntrack_expect.h>
+#include <linux/netfilter/nf_conntrack_sane.h>
+
+MODULE_LICENSE("GPL");
+MODULE_AUTHOR("Michal Schmidt <mschmidt@redhat.com>");
+MODULE_DESCRIPTION("SANE connection tracking helper");
+
+static char *sane_buffer;
+
+static DEFINE_SPINLOCK(nf_sane_lock);
+
+#define MAX_PORTS 8
+static u_int16_t ports[MAX_PORTS];
+static unsigned int ports_c;
+module_param_array(ports, ushort, &ports_c, 0400);
+
+#if 0
+#define DEBUGP printk
+#else
+#define DEBUGP(format, args...)
+#endif
+
+struct sane_request {
+ __be32 RPC_code;
+#define SANE_NET_START 7 /* RPC code */
+
+ __be32 handle;
+};
+
+struct sane_reply_net_start {
+ __be32 status;
+#define SANE_STATUS_SUCCESS 0
+
+ __be16 zero;
+ __be16 port;
+ /* other fields aren't interesting for conntrack */
+};
+
+static int help(struct sk_buff **pskb,
+ unsigned int protoff,
+ struct nf_conn *ct,
+ enum ip_conntrack_info ctinfo)
+{
+ unsigned int dataoff, datalen;
+ struct tcphdr _tcph, *th;
+ char *sb_ptr;
+ int ret = NF_ACCEPT;
+ int dir = CTINFO2DIR(ctinfo);
+ struct nf_ct_sane_master *ct_sane_info;
+ struct nf_conntrack_expect *exp;
+ struct nf_conntrack_tuple *tuple;
+ struct sane_request *req;
+ struct sane_reply_net_start *reply;
+ int family = ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple.src.l3num;
+
+ ct_sane_info = &nfct_help(ct)->help.ct_sane_info;
+ /* Until there's been traffic both ways, don't look in packets. */
+ if (ctinfo != IP_CT_ESTABLISHED &&
+ ctinfo != IP_CT_ESTABLISHED+IP_CT_IS_REPLY)
+ return NF_ACCEPT;
+
+ /* Not a full tcp header? */
+ th = skb_header_pointer(*pskb, protoff, sizeof(_tcph), &_tcph);
+ if (th == NULL)
+ return NF_ACCEPT;
+
+ /* No data? */
+ dataoff = protoff + th->doff * 4;
+ if (dataoff >= (*pskb)->len)
+ return NF_ACCEPT;
+
+ datalen = (*pskb)->len - dataoff;
+
+ spin_lock_bh(&nf_sane_lock);
+ sb_ptr = skb_header_pointer(*pskb, dataoff, datalen, sane_buffer);
+ BUG_ON(sb_ptr == NULL);
+
+ if (dir == IP_CT_DIR_ORIGINAL) {
+ if (datalen != sizeof(struct sane_request))
+ goto out;
+
+ req = (struct sane_request *)sb_ptr;
+ if (req->RPC_code != htonl(SANE_NET_START)) {
+ /* Not an interesting command */
+ ct_sane_info->state = SANE_STATE_NORMAL;
+ goto out;
+ }
+
+ /* We're interested in the next reply */
+ ct_sane_info->state = SANE_STATE_START_REQUESTED;
+ goto out;
+ }
+
+ /* Is it a reply to an uninteresting command? */
+ if (ct_sane_info->state != SANE_STATE_START_REQUESTED)
+ goto out;
+
+ /* It's a reply to SANE_NET_START. */
+ ct_sane_info->state = SANE_STATE_NORMAL;
+
+ if (datalen < sizeof(struct sane_reply_net_start)) {
+ DEBUGP("nf_ct_sane: NET_START reply too short\n");
+ goto out;
+ }
+
+ reply = (struct sane_reply_net_start *)sb_ptr;
+ if (reply->status != htonl(SANE_STATUS_SUCCESS)) {
+ /* saned refused the command */
+ DEBUGP("nf_ct_sane: unsuccessful SANE_STATUS = %u\n",
+ ntohl(reply->status));
+ goto out;
+ }
+
+ /* Invalid saned reply? Ignore it. */
+ if (reply->zero != 0)
+ goto out;
+
+ exp = nf_conntrack_expect_alloc(ct);
+ if (exp == NULL) {
+ ret = NF_DROP;
+ goto out;
+ }
+
+ tuple = &ct->tuplehash[IP_CT_DIR_ORIGINAL].tuple;
+ nf_conntrack_expect_init(exp, family,
+ &tuple->src.u3, &tuple->dst.u3,
+ IPPROTO_TCP,
+ NULL, &reply->port);
+
+ DEBUGP("nf_ct_sane: expect: ");
+ NF_CT_DUMP_TUPLE(&exp->tuple);
+ NF_CT_DUMP_TUPLE(&exp->mask);
+
+ /* Can't expect this? Best to drop packet now. */
+ if (nf_conntrack_expect_related(exp) != 0)
+ ret = NF_DROP;
+
+ nf_conntrack_expect_put(exp);
+
+out:
+ spin_unlock_bh(&nf_sane_lock);
+ return ret;
+}
+
+static struct nf_conntrack_helper sane[MAX_PORTS][2];
+static char sane_names[MAX_PORTS][2][sizeof("sane-65535")];
+
+/* don't make this __exit, since it's called from __init ! */
+static void nf_conntrack_sane_fini(void)
+{
+ int i, j;
+
+ for (i = 0; i < ports_c; i++) {
+ for (j = 0; j < 2; j++) {
+ DEBUGP("nf_ct_sane: unregistering helper for pf: %d "
+ "port: %d\n",
+ sane[i][j].tuple.src.l3num, ports[i]);
+ nf_conntrack_helper_unregister(&sane[i][j]);
+ }
+ }
+
+ kfree(sane_buffer);
+}
+
+static int __init nf_conntrack_sane_init(void)
+{
+ int i, j = -1, ret = 0;
+ char *tmpname;
+
+ sane_buffer = kmalloc(65536, GFP_KERNEL);
+ if (!sane_buffer)
+ return -ENOMEM;
+
+ if (ports_c == 0)
+ ports[ports_c++] = SANE_PORT;
+
+ /* FIXME should be configurable whether IPv4 and IPv6 connections
+ are tracked or not - YK */
+ for (i = 0; i < ports_c; i++) {
+ sane[i][0].tuple.src.l3num = PF_INET;
+ sane[i][1].tuple.src.l3num = PF_INET6;
+ for (j = 0; j < 2; j++) {
+ sane[i][j].tuple.src.u.tcp.port = htons(ports[i]);
+ sane[i][j].tuple.dst.protonum = IPPROTO_TCP;
+ sane[i][j].mask.src.u.tcp.port = 0xFFFF;
+ sane[i][j].mask.dst.protonum = 0xFF;
+ sane[i][j].max_expected = 1;
+ sane[i][j].timeout = 5 * 60; /* 5 Minutes */
+ sane[i][j].me = THIS_MODULE;
+ sane[i][j].help = help;
+ tmpname = &sane_names[i][j][0];
+ if (ports[i] == SANE_PORT)
+ sprintf(tmpname, "sane");
+ else
+ sprintf(tmpname, "sane-%d", ports[i]);
+ sane[i][j].name = tmpname;
+
+ DEBUGP("nf_ct_sane: registering helper for pf: %d "
+ "port: %d\n",
+ sane[i][j].tuple.src.l3num, ports[i]);
+ ret = nf_conntrack_helper_register(&sane[i][j]);
+ if (ret) {
+ printk(KERN_ERR "nf_ct_sane: failed to "
+ "register helper for pf: %d port: %d\n",
+ sane[i][j].tuple.src.l3num, ports[i]);
+ nf_conntrack_sane_fini();
+ return ret;
+ }
+ }
+ }
+
+ return 0;
+}
+
+module_init(nf_conntrack_sane_init);
+module_exit(nf_conntrack_sane_fini);
projects / linux-2.6 / commitdiff