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Date: Wed, 04 Aug 2010 14:40:19 +0400
From: xeb@...l.ru
To: netdev@...r.kernel.org
Subject: PATCH 1/3] PPTP: PPP over IPv4 (Point-to-Point Tunneling Protocol)
This is patch 1/3 which contains gre demultiplexer driver source
for demultiplexing gre packets with different gre version.
---
include/net/gre.h | 18 ++++++
net/ipv4/Kconfig | 7 +++
net/ipv4/Makefile | 1 +
net/ipv4/gre.c | 151 +++++++++++++++++++++++++++++++++++++++++++++++++++++
4 files changed, 177 insertions(+), 0 deletions(-)
diff --git a/include/net/gre.h b/include/net/gre.h
new file mode 100644
index 0000000..31a0f76
--- /dev/null
+++ b/include/net/gre.h
@@ -0,0 +1,18 @@
+#ifndef __LINUX_GRE_H
+#define __LINUX_GRE_H
+
+#include <linux/skbuff.h>
+
+#define GREPROTO_CISCO 0
+#define GREPROTO_PPTP 1
+#define GREPROTO_MAX 2
+
+struct gre_protocol {
+ int (*handler)(struct sk_buff *skb);
+ void (*err_handler)(struct sk_buff *skb, u32 info);
+};
+
+int gre_add_protocol(const struct gre_protocol *proto, u8 version);
+int gre_del_protocol(const struct gre_protocol *proto, u8 version);
+
+#endif
diff --git a/net/ipv4/Kconfig b/net/ipv4/Kconfig
index 7c3a7d1..7458bda 100644
--- a/net/ipv4/Kconfig
+++ b/net/ipv4/Kconfig
@@ -215,8 +215,15 @@ config NET_IPIP
be inserted in and removed from the running kernel whenever you
want). Most people won't need this and can say N.
+config NET_IPGRE_DEMUX
+ tristate "IP: GRE demultiplexer"
+ help
+ This is helper module to demultiplex GRE packets on GRE version field criteria.
+ Required by ip_gre and pptp modules.
+
config NET_IPGRE
tristate "IP: GRE tunnels over IP"
+ depends on NET_IPGRE_DEMUX
help
Tunneling means encapsulating data of one protocol type within
another protocol and sending it over a channel that understands the
diff --git a/net/ipv4/Makefile b/net/ipv4/Makefile
index 80ff87c..4978d22 100644
--- a/net/ipv4/Makefile
+++ b/net/ipv4/Makefile
@@ -20,6 +20,7 @@ obj-$(CONFIG_PROC_FS) += proc.o
obj-$(CONFIG_IP_MULTIPLE_TABLES) += fib_rules.o
obj-$(CONFIG_IP_MROUTE) += ipmr.o
obj-$(CONFIG_NET_IPIP) += ipip.o
+obj-$(CONFIG_NET_IPGRE_DEMUX) += gre.o
obj-$(CONFIG_NET_IPGRE) += ip_gre.o
obj-$(CONFIG_SYN_COOKIES) += syncookies.o
obj-$(CONFIG_INET_AH) += ah4.o
diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
new file mode 100644
index 0000000..993f3cf
--- /dev/null
+++ b/net/ipv4/gre.c
@@ -0,0 +1,151 @@
+/*
+ * GRE over IPv4 demultiplexer driver
+ *
+ * Authors: Dmitry Kozlov (xeb@...l.ru)
+ *
+ * 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.
+ *
+ */
+
+#include <linux/module.h>
+#include <linux/kernel.h>
+#include <linux/kmod.h>
+#include <linux/skbuff.h>
+#include <linux/in.h>
+#include <linux/netdevice.h>
+#include <linux/version.h>
+#include <linux/spinlock.h>
+#include <net/protocol.h>
+#include <net/gre.h>
+
+
+const struct gre_protocol *gre_proto[GREPROTO_MAX] ____cacheline_aligned_in_smp;
+static DEFINE_RWLOCK(gre_proto_lock);
+
+int gre_add_protocol(const struct gre_protocol *proto, u8 version)
+{
+ int ret;
+
+ if (version >= GREPROTO_MAX)
+ return -1;
+
+ write_lock_bh(&gre_proto_lock);
+ if (gre_proto[version]) {
+ ret = -1;
+ } else {
+ gre_proto[version]=proto;
+ ret = 0;
+ }
+ write_unlock_bh(&gre_proto_lock);
+
+ return ret;
+}
+int gre_del_protocol(const struct gre_protocol *proto, u8 version)
+{
+ int ret;
+
+ if (version >= GREPROTO_MAX)
+ return -1;
+
+ write_lock_bh(&gre_proto_lock);
+ if (gre_proto[version] == proto) {
+ gre_proto[version] = NULL;
+ ret = 0;
+ } else {
+ ret = -1;
+ }
+ write_unlock_bh(&gre_proto_lock);
+
+ return ret;
+}
+static int gre_rcv(struct sk_buff *skb)
+{
+ u8 ver;
+ int ret;
+
+ if (!pskb_may_pull(skb, 12))
+ goto drop_nolock;
+
+ ver = skb->data[1]&0x7f;
+ if (ver >= GREPROTO_MAX)
+ goto drop_nolock;
+
+ read_lock(&gre_proto_lock);
+ if (!gre_proto[ver] || !gre_proto[ver]->handler)
+ goto drop;
+
+ ret = gre_proto[ver]->handler(skb);
+ read_unlock(&gre_proto_lock);
+
+ return ret;
+
+drop:
+ read_unlock(&gre_proto_lock);
+drop_nolock:
+ kfree_skb(skb);
+ return NET_RX_DROP;
+}
+static void gre_err(struct sk_buff *skb, u32 info)
+{
+ u8 ver;
+
+ printk("err\n");
+
+ if (!pskb_may_pull(skb, 12))
+ goto drop_nolock;
+
+ ver=skb->data[1];
+ if (ver>=GREPROTO_MAX)
+ goto drop_nolock;
+
+ read_lock(&gre_proto_lock);
+ if (!gre_proto[ver] || !gre_proto[ver]->err_handler)
+ goto drop;
+
+ gre_proto[ver]->err_handler(skb,info);
+ read_unlock(&gre_proto_lock);
+
+ return;
+
+drop:
+ read_unlock(&gre_proto_lock);
+drop_nolock:
+ kfree_skb(skb);
+}
+
+
+static struct net_protocol net_gre_protocol = {
+ .handler = gre_rcv,
+ .err_handler = gre_err,
+// .netns_ok=1,
+};
+
+static int __init gre_init(void)
+{
+ printk(KERN_INFO "GRE over IPv4 demultiplexor driver");
+
+ if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
+ printk(KERN_INFO "gre: can't add protocol\n");
+ return -EAGAIN;
+ }
+
+ return 0;
+}
+
+static void __exit gre_exit(void)
+{
+ inet_del_protocol(&net_gre_protocol, IPPROTO_GRE);
+}
+
+module_init(gre_init);
+module_exit(gre_exit);
+
+MODULE_DESCRIPTION("GRE over IPv4 demultiplexer driver");
+MODULE_AUTHOR("D. Kozlov (xeb@...l.ru)");
+MODULE_LICENSE("GPL");
+EXPORT_SYMBOL_GPL(gre_add_protocol);
+EXPORT_SYMBOL_GPL(gre_del_protocol);
--
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