From: Michal Schmidt Date: Wed, 7 Feb 2007 23:05:12 +0000 (-0800) Subject: [NETFILTER]: Add SANE connection tracking helper X-Git-Tag: v2.6.21-rc1~83^2~65^2~35 X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=6fecd1985116fb08bdee3b9db6719e159fe5e43d;p=linux-2.6 [NETFILTER]: Add SANE connection tracking helper This is nf_conntrack_sane, a netfilter connection tracking helper module for the SANE protocol used by the 'saned' daemon to make scanners available via network. The SANE protocol uses separate control & data connections, similar to passive FTP. The helper module is needed to recognize the data connection as RELATED to the control one. Signed-off-by: Michal Schmidt Signed-off-by: Patrick McHardy Signed-off-by: David S. Miller --- diff --git a/include/linux/netfilter/nf_conntrack_sane.h b/include/linux/netfilter/nf_conntrack_sane.h new file mode 100644 index 0000000000..4767d6e23e --- /dev/null +++ b/include/linux/netfilter/nf_conntrack_sane.h @@ -0,0 +1,21 @@ +#ifndef _NF_CONNTRACK_SANE_H +#define _NF_CONNTRACK_SANE_H +/* SANE tracking. */ + +#ifdef __KERNEL__ + +#define SANE_PORT 6566 + +enum sane_state { + SANE_STATE_NORMAL, + SANE_STATE_START_REQUESTED, +}; + +/* This structure exists only once per master */ +struct nf_ct_sane_master { + enum sane_state state; +}; + +#endif /* __KERNEL__ */ + +#endif /* _NF_CONNTRACK_SANE_H */ diff --git a/include/net/netfilter/nf_conntrack.h b/include/net/netfilter/nf_conntrack.h index bd01b4633e..68ec27490c 100644 --- a/include/net/netfilter/nf_conntrack.h +++ b/include/net/netfilter/nf_conntrack.h @@ -45,6 +45,7 @@ union nf_conntrack_expect_proto { #include #include #include +#include /* per conntrack: application helper private data */ union nf_conntrack_help { @@ -52,6 +53,7 @@ union nf_conntrack_help { struct nf_ct_ftp_master ct_ftp_info; struct nf_ct_pptp_master ct_pptp_info; struct nf_ct_h323_master ct_h323_info; + struct nf_ct_sane_master ct_sane_info; }; #include diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index 80107d4909..614c92c178 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -235,6 +235,19 @@ config NF_CONNTRACK_PPTP To compile it as a module, choose M here. If unsure, say N. +config NF_CONNTRACK_SANE + tristate "SANE protocol support (EXPERIMENTAL)" + depends on EXPERIMENTAL && NF_CONNTRACK + help + SANE is a protocol for remote access to scanners as implemented + by the 'saned' daemon. Like FTP, it uses separate control and + data connections. + + With this module you can support SANE on a connection tracking + firewall. + + To compile it as a module, choose M here. If unsure, say N. + config NF_CONNTRACK_SIP tristate "SIP protocol support (EXPERIMENTAL)" depends on EXPERIMENTAL && NF_CONNTRACK diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 5dc5574f7e..5054b0ff80 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -29,6 +29,7 @@ obj-$(CONFIG_NF_CONNTRACK_H323) += nf_conntrack_h323.o obj-$(CONFIG_NF_CONNTRACK_IRC) += nf_conntrack_irc.o obj-$(CONFIG_NF_CONNTRACK_NETBIOS_NS) += nf_conntrack_netbios_ns.o obj-$(CONFIG_NF_CONNTRACK_PPTP) += nf_conntrack_pptp.o +obj-$(CONFIG_NF_CONNTRACK_SANE) += nf_conntrack_sane.o obj-$(CONFIG_NF_CONNTRACK_SIP) += nf_conntrack_sip.o obj-$(CONFIG_NF_CONNTRACK_TFTP) += nf_conntrack_tftp.o diff --git a/net/netfilter/nf_conntrack_sane.c b/net/netfilter/nf_conntrack_sane.c new file mode 100644 index 0000000000..eb2d1dc46d --- /dev/null +++ b/net/netfilter/nf_conntrack_sane.c @@ -0,0 +1,242 @@ +/* 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 + * Based on the FTP conntrack helper (net/netfilter/nf_conntrack_ftp.c): + * (C) 1999-2001 Paul `Rusty' Russell + * (C) 2002-2004 Netfilter Core Team + * (C) 2003,2004 USAGI/WIDE Project + * (C) 2003 Yasuyuki Kozakai @USAGI + * + * 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 +#include +#include +#include +#include +#include +#include +#include +#include + +MODULE_LICENSE("GPL"); +MODULE_AUTHOR("Michal Schmidt "); +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);