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Date: Thu, 18 Oct 2007 12:27:15 +0200
From: Patrick McHardy <kaber@...sh.net>
To: Laszlo Attila Toth <panther@...abit.hu>
CC: netdev@...r.kernel.org, netfilter-devel@...r.kernel.org
Subject: Re: [PATCH 2/2] Interface group match
Laszlo Attila Toth wrote:
> Interface group values can be checked on both input and output interfaces.
>
> Signed-off-by: Laszlo Attila Toth <panther@...abit.hu>
> ---
> include/linux/netfilter/xt_ifgroup.h | 18 ++++++
> net/netfilter/Kconfig | 16 +++++
> net/netfilter/Makefile | 1 +
> net/netfilter/xt_ifgroup.c | 108 ++++++++++++++++++++++++++++++++++
> 4 files changed, 143 insertions(+), 0 deletions(-)
>
> diff --git a/include/linux/netfilter/xt_ifgroup.h b/include/linux/netfilter/xt_ifgroup.h
> new file mode 100644
> index 0000000..9ac75de
> --- /dev/null
> +++ b/include/linux/netfilter/xt_ifgroup.h
> @@ -0,0 +1,18 @@
> +#ifndef _XT_IFGROUP_H
> +#define _XT_IFGROUP_H
> +
> +#define XT_IFGROUP_INVERT_IN 0x01
> +#define XT_IFGROUP_INVERT_OUT 0x02
> +#define XT_IFGROUP_MATCH_IN 0x04
> +#define XT_IFGROUP_MATCH_OUT 0x08
> +
> +struct xt_ifgroup_info {
> + u_int32_t in_group;
> + u_int32_t in_mask;
> + u_int32_t out_group;
> + u_int32_t out_mask;
> + u_int8_t flags;
> +};
> +
> +#endif /*_XT_IFGROUP_H*/
> +
> diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
> index 3599770..0864e19 100644
> --- a/net/netfilter/Kconfig
> +++ b/net/netfilter/Kconfig
> @@ -597,6 +597,22 @@ config NETFILTER_XT_MATCH_QUOTA
> If you want to compile it as a module, say M here and read
> <file:Documentation/kbuild/modules.txt>. If unsure, say `N'.
>
> +config NETFILTER_XT_MATCH_IFGROUP
> + tristate '"ifgroup" interface group match support'
> + depends on NETFILTER_XTABLES
> + help
> + Interface group matching allows you to match a packet by
> + its incoming interface "group", settable using ip link set
> + group
> +
> + Typical usage is to assign dynamic interfaces to a group
> + when they come up using "ip link set group" and then match
> + incoming packets with a rule like this:
> +
> + iptables -A INPUT -m ifgroup --if-group openvpn-rw1 -j LOG
> +
> + To compile it as a module, choose M here. If unsure, say N.
> +
> config NETFILTER_XT_MATCH_REALM
> tristate '"realm" match support'
> depends on NETFILTER_XTABLES
> diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
> index 0c054bf..da9ab07 100644
> --- a/net/netfilter/Makefile
> +++ b/net/netfilter/Makefile
> @@ -77,3 +77,4 @@ obj-$(CONFIG_NETFILTER_XT_MATCH_TCPMSS) += xt_tcpmss.o
> obj-$(CONFIG_NETFILTER_XT_MATCH_PHYSDEV) += xt_physdev.o
> obj-$(CONFIG_NETFILTER_XT_MATCH_U32) += xt_u32.o
> obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
> +obj-$(CONFIG_NETFILTER_XT_MATCH_IFGROUP) += xt_ifgroup.o
> diff --git a/net/netfilter/xt_ifgroup.c b/net/netfilter/xt_ifgroup.c
> new file mode 100644
> index 0000000..07c3acc
> --- /dev/null
> +++ b/net/netfilter/xt_ifgroup.c
> @@ -0,0 +1,108 @@
> +/*
> + * An x_tables match module to match interface groups
> + *
> + * (C) 2006,2007 Balazs Scheidler <bazsi@...abit.hu>,
> + * Laszlo Attila Toth <panther@...abit.hu>
> + *
> + * 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/skbuff.h>
> +#include <linux/if_ether.h>
> +#include <linux/if_packet.h>
These two look unnecessary.
> +
> +#include <linux/netfilter/xt_ifgroup.h>
> +#include <linux/netfilter/x_tables.h>
> +
> +MODULE_LICENSE("GPL");
> +MODULE_AUTHOR("Laszlo Attila Toth <panther@...abit.hu>");
> +MODULE_DESCRIPTION("Xtables interface group matching module");
> +MODULE_ALIAS("ipt_ifgroup");
> +MODULE_ALIAS("ip6t_ifgroup");
> +
> +static bool ifgroup_match(const struct sk_buff *skb,
> + const struct net_device *in,
> + const struct net_device *out,
> + const struct xt_match *match,
> + const void *matchinfo,
> + int offset,
> + unsigned int protoff,
> + bool *hotdrop)
> +{
> +#define FLAG_IS_SET(a,b) ((a & b) == b)
> +#define MATCH_IN (((in->ifgroup & info->in_mask) == info->in_group) ^ FLAG_IS_SET(info->flags, XT_IFGROUP_INVERT_IN))
> +#define MATCH_OUT (((out->ifgroup & info->out_mask) == info->out_group) ^ FLAG_IS_SET(info->flags, XT_IFGROUP_INVERT_OUT))
Exceeds 80 characters and looks pretty obfuscating. Please open
code this or use an inline function.
> +
> + const struct xt_ifgroup_info *info = matchinfo;
> + bool verdict = false;
> +
> + if ((info->flags & XT_IFGROUP_MATCH_IN) && (info->flags & XT_IFGROUP_MATCH_OUT))
> + verdict = MATCH_IN && MATCH_OUT;
> + else if (info->flags & XT_IFGROUP_MATCH_IN)
> + verdict = MATCH_IN;
> + else if (info->flags & XT_IFGROUP_MATCH_OUT)
> + verdict = MATCH_OUT;
How about:
if (info->flags & XT_IFGROUP_MATCH_IN && !MATCH_IN)
return false;
if (info->flags & XT_IFGROUP_MATCH_OUT && !MATCH_OUT)
return false;
instead of having each match twice?
> + return verdict;
> +}
> +
> +static bool ifgroup_checkentry(const char *tablename, const void *ip_void,
> + const struct xt_match *match,
> + void *matchinfo, unsigned int hook_mask)
> +{
> + struct xt_ifgroup_info *info = matchinfo;
> +
> + if (!(info->flags & (XT_IFGROUP_MATCH_IN|XT_IFGROUP_MATCH_OUT))) {
> + printk(KERN_ERR "xt_ifgroup: neither incoming nor "
> + "outgoing device selected\n");
> + return false;
> + }
> + if (hook_mask & (1 << NF_IP_PRE_ROUTING | 1 << NF_IP_LOCAL_IN)
> + && info->flags & XT_IFGROUP_MATCH_OUT) {
> + printk(KERN_ERR "xt_ifgroup: output device not valid in "
> + "PRE_ROUTING and INPUT\n");
> + return false;
> + }
> + if (hook_mask & (1 << NF_IP_POST_ROUTING | 1 << NF_IP_LOCAL_OUT)
> + && info->flags & XT_IFGROUP_MATCH_IN) {
> + printk(KERN_ERR "xt_ifgroup: input device not valid in "
> + "POST_ROUTING and OUTPUT\n");
> + return false;
> + }
> + return true;
> +}
> +
> +static struct xt_match xt_ifgroup_match[] __read_mostly = {
> + {
> + .name = "ifgroup",
> + .match = ifgroup_match,
> + .checkentry = ifgroup_checkentry,
> + .matchsize = sizeof(struct xt_ifgroup_info),
> + .family = AF_INET,
> + .me = THIS_MODULE,
> +
> + },
> + {
> + .name = "ifgroup",
> + .match = ifgroup_match,
> + .checkentry = ifgroup_checkentry,
> + .matchsize = sizeof(struct xt_ifgroup_info),
> + .family = AF_INET6,
> + .me = THIS_MODULE,
> + },
> +};
> +
> +static int __init xt_ifgroup_init(void)
> +{
> + return xt_register_matches(xt_ifgroup_match, ARRAY_SIZE(xt_ifgroup_match));
Also exceeds 80 characters.
> +}
> +
> +static void __exit xt_ifgroup_fini(void)
> +{
> + xt_unregister_matches(xt_ifgroup_match, ARRAY_SIZE(xt_ifgroup_match));
> +}
> +
> +module_init(xt_ifgroup_init);
> +module_exit(xt_ifgroup_fini);
-
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