diff options
| -rw-r--r-- | net/netfilter/Kconfig | 19 | ||||
| -rw-r--r-- | net/netfilter/Makefile | 1 | ||||
| -rw-r--r-- | net/netfilter/nf_conntrack_netbios_ns.c | 125 |
3 files changed, 145 insertions, 0 deletions
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig index bd50897d8fbb..d1a365d83c53 100644 --- a/net/netfilter/Kconfig +++ b/net/netfilter/Kconfig @@ -194,6 +194,25 @@ config NF_CONNTRACK_IRC To compile it as a module, choose M here. If unsure, say N. +config NF_CONNTRACK_NETBIOS_NS + tristate "NetBIOS name service protocol support (EXPERIMENTAL)" + depends on EXPERIMENTAL && NF_CONNTRACK + help + NetBIOS name service requests are sent as broadcast messages from an + unprivileged port and responded to with unicast messages to the + same port. This make them hard to firewall properly because connection + tracking doesn't deal with broadcasts. This helper tracks locally + originating NetBIOS name service requests and the corresponding + responses. It relies on correct IP address configuration, specifically + netmask and broadcast address. When properly configured, the output + of "ip address show" should look similar to this: + + $ ip -4 address show eth0 + 4: eth0: <BROADCAST,MULTICAST,UP> mtu 1500 qdisc pfifo_fast qlen 1000 + inet 172.16.2.252/24 brd 172.16.2.255 scope global eth0 + + To compile it as a module, choose M here. If unsure, say N. + config NF_CT_NETLINK tristate 'Connection tracking netlink interface (EXPERIMENTAL)' depends on EXPERIMENTAL && NF_CONNTRACK && NETFILTER_NETLINK diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile index 343fd4896406..67144b2af647 100644 --- a/net/netfilter/Makefile +++ b/net/netfilter/Makefile @@ -26,6 +26,7 @@ obj-$(CONFIG_NF_CONNTRACK_AMANDA) += nf_conntrack_amanda.o obj-$(CONFIG_NF_CONNTRACK_FTP) += nf_conntrack_ftp.o obj-$(CONFIG_NF_CONNTRACK_H323) += nf_conntrack_h323.o obj-$(CONFIG_NF_CONNTRACK_IRC) += nf_conntrack_irc.o +obj-$(CONFIG_NF_CONNTRACK_NETBIOS_NS) += nf_conntrack_netbios_ns.o # generic X tables obj-$(CONFIG_NETFILTER_XTABLES) += x_tables.o xt_tcpudp.o diff --git a/net/netfilter/nf_conntrack_netbios_ns.c b/net/netfilter/nf_conntrack_netbios_ns.c new file mode 100644 index 000000000000..4fad3ad0b886 --- /dev/null +++ b/net/netfilter/nf_conntrack_netbios_ns.c @@ -0,0 +1,125 @@ +/* + * NetBIOS name service broadcast connection tracking helper + * + * (c) 2005 Patrick McHardy <kaber@trash.net> + * + * This program is free software; you can redistribute it and/or + * modify it under the terms of the GNU General Public License + * as published by the Free Software Foundation; either version + * 2 of the License, or (at your option) any later version. + */ +/* + * This helper tracks locally originating NetBIOS name service + * requests by issuing permanent expectations (valid until + * timing out) matching all reply connections from the + * destination network. The only NetBIOS specific thing is + * actually the port number. + */ +#include <linux/kernel.h> +#include <linux/module.h> +#include <linux/init.h> +#include <linux/skbuff.h> +#include <linux/netdevice.h> +#include <linux/inetdevice.h> +#include <linux/if_addr.h> +#include <linux/in.h> +#include <linux/ip.h> +#include <net/route.h> + +#include <net/netfilter/nf_conntrack.h> +#include <net/netfilter/nf_conntrack_helper.h> +#include <net/netfilter/nf_conntrack_expect.h> + +#define NMBD_PORT 137 + +MODULE_AUTHOR("Patrick McHardy <kaber@trash.net>"); +MODULE_DESCRIPTION("NetBIOS name service broadcast connection tracking helper"); +MODULE_LICENSE("GPL"); +MODULE_ALIAS("ip_conntrack_netbios_ns"); + +static unsigned int timeout __read_mostly = 3; +module_param(timeout, uint, 0400); +MODULE_PARM_DESC(timeout, "timeout for master connection/replies in seconds"); + +static int help(struct sk_buff **pskb, unsigned int protoff, + struct nf_conn *ct, enum ip_conntrack_info ctinfo) +{ + struct nf_conntrack_expect *exp; + struct iphdr *iph = (*pskb)->nh.iph; + struct rtable *rt = (struct rtable *)(*pskb)->dst; + struct in_device *in_dev; + __be32 mask = 0; + + /* we're only interested in locally generated packets */ + if ((*pskb)->sk == NULL) + goto out; + if (rt == NULL || !(rt->rt_flags & RTCF_BROADCAST)) + goto out; + if (CTINFO2DIR(ctinfo) != IP_CT_DIR_ORIGINAL) + goto out; + + rcu_read_lock(); + in_dev = __in_dev_get_rcu(rt->u.dst.dev); + if (in_dev != NULL) { + for_primary_ifa(in_dev) { + if (ifa->ifa_broadcast == iph->daddr) { + mask = ifa->ifa_mask; + break; + } + } endfor_ifa(in_dev); + } + rcu_read_unlock(); + + if (mask == 0) + goto out; + + exp = nf_conntrack_expect_alloc(ct); + if (exp == NULL) + goto out; + + exp->tuple = ct->tuplehash[IP_CT_DIR_REPLY].tuple; + exp->tuple.src.u.udp.port = htons(NMBD_PORT); + + exp->mask.src.u3.ip = mask; + exp->mask.src.u.udp.port = htons(0xFFFF); + exp->mask.dst.u3.ip = htonl(0xFFFFFFFF); + exp->mask.dst.u.udp.port = htons(0xFFFF); + exp->mask.dst.protonum = 0xFF; + + exp->expectfn = NULL; + exp->flags = NF_CT_EXPECT_PERMANENT; + + nf_conntrack_expect_related(exp); + nf_conntrack_expect_put(exp); + + nf_ct_refresh(ct, *pskb, timeout * HZ); +out: + return NF_ACCEPT; +} + +static struct nf_conntrack_helper helper __read_mostly = { + .name = "netbios-ns", + .tuple.src.l3num = AF_INET, + .tuple.src.u.udp.port = __constant_htons(NMBD_PORT), + .tuple.dst.protonum = IPPROTO_UDP, + .mask.src.l3num = 0xFFFF, + .mask.src.u.udp.port = __constant_htons(0xFFFF), + .mask.dst.protonum = 0xFF, + .max_expected = 1, + .me = THIS_MODULE, + .help = help, +}; + +static int __init nf_conntrack_netbios_ns_init(void) +{ + helper.timeout = timeout; + return nf_conntrack_helper_register(&helper); +} + +static void __exit nf_conntrack_netbios_ns_fini(void) +{ + nf_conntrack_helper_unregister(&helper); +} + +module_init(nf_conntrack_netbios_ns_init); +module_exit(nf_conntrack_netbios_ns_fini); |