Laszlo Attila Toth wrote:
Interface group values can be checked on both input and output interfaces.
Signed-off-by: Laszlo Attila Toth <panther@xxxxxxxxxx>
---
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@xxxxxxxxxx>,
+ * Laszlo Attila Toth <panther@xxxxxxxxxx>
+ *
+ * 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@xxxxxxxxxx>");
+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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