netfilter: xtables: move ipt_ecn to xt_ecn
Prepare the ECN match for augmentation by an IPv6 counterpart. Since
no symbol dependencies to ipv6.ko are added, having a single ecn match
module is the more so welcome.
Signed-off-by: Jan Engelhardt <[email protected]>
Signed-off-by: Pablo Neira Ayuso <[email protected]>
diff --git a/net/netfilter/Kconfig b/net/netfilter/Kconfig
index bac93ba..20388a9 100644
--- a/net/netfilter/Kconfig
+++ b/net/netfilter/Kconfig
@@ -778,6 +778,15 @@
To compile it as a module, choose M here. If unsure, say N.
+config NETFILTER_XT_MATCH_ECN
+ tristate '"ecn" match support'
+ depends on NETFILTER_ADVANCED
+ ---help---
+ This option adds an "ECN" match, which allows you to match against
+ the IPv4 and TCP header ECN fields.
+
+ To compile it as a module, choose M here. If unsure, say N.
+
config NETFILTER_XT_MATCH_ESP
tristate '"esp" match support'
depends on NETFILTER_ADVANCED
diff --git a/net/netfilter/Makefile b/net/netfilter/Makefile
index b2eee4d..40f4c3d 100644
--- a/net/netfilter/Makefile
+++ b/net/netfilter/Makefile
@@ -81,6 +81,7 @@
obj-$(CONFIG_NETFILTER_XT_MATCH_DCCP) += xt_dccp.o
obj-$(CONFIG_NETFILTER_XT_MATCH_DEVGROUP) += xt_devgroup.o
obj-$(CONFIG_NETFILTER_XT_MATCH_DSCP) += xt_dscp.o
+obj-$(CONFIG_NETFILTER_XT_MATCH_ECN) += xt_ecn.o
obj-$(CONFIG_NETFILTER_XT_MATCH_ESP) += xt_esp.o
obj-$(CONFIG_NETFILTER_XT_MATCH_HASHLIMIT) += xt_hashlimit.o
obj-$(CONFIG_NETFILTER_XT_MATCH_HELPER) += xt_helper.o
diff --git a/net/netfilter/xt_ecn.c b/net/netfilter/xt_ecn.c
new file mode 100644
index 0000000..2c198f5
--- /dev/null
+++ b/net/netfilter/xt_ecn.c
@@ -0,0 +1,128 @@
+/* IP tables module for matching the value of the IPv4 and TCP ECN bits
+ *
+ * (C) 2002 by Harald Welte <[email protected]>
+ *
+ * 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.
+ */
+#define pr_fmt(fmt) KBUILD_MODNAME ": " fmt
+#include <linux/in.h>
+#include <linux/ip.h>
+#include <net/ip.h>
+#include <linux/module.h>
+#include <linux/skbuff.h>
+#include <linux/tcp.h>
+
+#include <linux/netfilter/x_tables.h>
+#include <linux/netfilter_ipv4/ip_tables.h>
+#include <linux/netfilter_ipv4/ipt_ecn.h>
+
+MODULE_AUTHOR("Harald Welte <[email protected]>");
+MODULE_DESCRIPTION("Xtables: Explicit Congestion Notification (ECN) flag match for IPv4");
+MODULE_LICENSE("GPL");
+MODULE_ALIAS("ipt_ecn");
+
+static inline bool match_ip(const struct sk_buff *skb,
+ const struct ipt_ecn_info *einfo)
+{
+ return ((ip_hdr(skb)->tos & IPT_ECN_IP_MASK) == einfo->ip_ect) ^
+ !!(einfo->invert & IPT_ECN_OP_MATCH_IP);
+}
+
+static inline bool match_tcp(const struct sk_buff *skb,
+ const struct ipt_ecn_info *einfo,
+ bool *hotdrop)
+{
+ struct tcphdr _tcph;
+ const struct tcphdr *th;
+
+ /* In practice, TCP match does this, so can't fail. But let's
+ * be good citizens.
+ */
+ th = skb_header_pointer(skb, ip_hdrlen(skb), sizeof(_tcph), &_tcph);
+ if (th == NULL) {
+ *hotdrop = false;
+ return false;
+ }
+
+ if (einfo->operation & IPT_ECN_OP_MATCH_ECE) {
+ if (einfo->invert & IPT_ECN_OP_MATCH_ECE) {
+ if (th->ece == 1)
+ return false;
+ } else {
+ if (th->ece == 0)
+ return false;
+ }
+ }
+
+ if (einfo->operation & IPT_ECN_OP_MATCH_CWR) {
+ if (einfo->invert & IPT_ECN_OP_MATCH_CWR) {
+ if (th->cwr == 1)
+ return false;
+ } else {
+ if (th->cwr == 0)
+ return false;
+ }
+ }
+
+ return true;
+}
+
+static bool ecn_mt(const struct sk_buff *skb, struct xt_action_param *par)
+{
+ const struct ipt_ecn_info *info = par->matchinfo;
+
+ if (info->operation & IPT_ECN_OP_MATCH_IP)
+ if (!match_ip(skb, info))
+ return false;
+
+ if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR)) {
+ if (!match_tcp(skb, info, &par->hotdrop))
+ return false;
+ }
+
+ return true;
+}
+
+static int ecn_mt_check(const struct xt_mtchk_param *par)
+{
+ const struct ipt_ecn_info *info = par->matchinfo;
+ const struct ipt_ip *ip = par->entryinfo;
+
+ if (info->operation & IPT_ECN_OP_MATCH_MASK)
+ return -EINVAL;
+
+ if (info->invert & IPT_ECN_OP_MATCH_MASK)
+ return -EINVAL;
+
+ if (info->operation & (IPT_ECN_OP_MATCH_ECE|IPT_ECN_OP_MATCH_CWR) &&
+ (ip->proto != IPPROTO_TCP || ip->invflags & IPT_INV_PROTO)) {
+ pr_info("cannot match TCP bits in rule for non-tcp packets\n");
+ return -EINVAL;
+ }
+
+ return 0;
+}
+
+static struct xt_match ecn_mt_reg __read_mostly = {
+ .name = "ecn",
+ .family = NFPROTO_IPV4,
+ .match = ecn_mt,
+ .matchsize = sizeof(struct ipt_ecn_info),
+ .checkentry = ecn_mt_check,
+ .me = THIS_MODULE,
+};
+
+static int __init ecn_mt_init(void)
+{
+ return xt_register_match(&ecn_mt_reg);
+}
+
+static void __exit ecn_mt_exit(void)
+{
+ xt_unregister_match(&ecn_mt_reg);
+}
+
+module_init(ecn_mt_init);
+module_exit(ecn_mt_exit);
