initial_commit

1 files changed, 143 insertions, 0 deletions

diff --git a/net/ipv4/gre.c b/net/ipv4/gre.c
new file mode 100644
index 00000000..3e3f75d9
--- /dev/null
+++ b/net/ipv4/gre.c
@@ -0,0 +1,143 @@
+/*
+ *	GRE over IPv4 demultiplexer driver
+ *
+ *	Authors: Dmitry Kozlov (xeb@mail.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/ip.h>
+#include <linux/netdevice.h>
+#include <linux/version.h>
+#include <linux/spinlock.h>
+#include <net/protocol.h>
+#include <net/gre.h>
+
+
+static const struct gre_protocol __rcu *gre_proto[GREPROTO_MAX] __read_mostly;
+static DEFINE_SPINLOCK(gre_proto_lock);
+
+int gre_add_protocol(const struct gre_protocol *proto, u8 version)
+{
+	if (version >= GREPROTO_MAX)
+		goto err_out;
+
+	spin_lock(&gre_proto_lock);
+	if (gre_proto[version])
+		goto err_out_unlock;
+
+	rcu_assign_pointer(gre_proto[version], proto);
+	spin_unlock(&gre_proto_lock);
+	return 0;
+
+err_out_unlock:
+	spin_unlock(&gre_proto_lock);
+err_out:
+	return -1;
+}
+EXPORT_SYMBOL_GPL(gre_add_protocol);
+
+int gre_del_protocol(const struct gre_protocol *proto, u8 version)
+{
+	if (version >= GREPROTO_MAX)
+		goto err_out;
+
+	spin_lock(&gre_proto_lock);
+	if (rcu_dereference_protected(gre_proto[version],
+			lockdep_is_held(&gre_proto_lock)) != proto)
+		goto err_out_unlock;
+	rcu_assign_pointer(gre_proto[version], NULL);
+	spin_unlock(&gre_proto_lock);
+	synchronize_rcu();
+	return 0;
+
+err_out_unlock:
+	spin_unlock(&gre_proto_lock);
+err_out:
+	return -1;
+}
+EXPORT_SYMBOL_GPL(gre_del_protocol);
+
+static int gre_rcv(struct sk_buff *skb)
+{
+	const struct gre_protocol *proto;
+	u8 ver;
+	int ret;
+
+	if (!pskb_may_pull(skb, 12))
+		goto drop;
+
+	ver = skb->data[1]&0x7f;
+	if (ver >= GREPROTO_MAX)
+		goto drop;
+
+	rcu_read_lock();
+	proto = rcu_dereference(gre_proto[ver]);
+	if (!proto || !proto->handler)
+		goto drop_unlock;
+	ret = proto->handler(skb);
+	rcu_read_unlock();
+	return ret;
+
+drop_unlock:
+	rcu_read_unlock();
+drop:
+	kfree_skb(skb);
+	return NET_RX_DROP;
+}
+
+static void gre_err(struct sk_buff *skb, u32 info)
+{
+	const struct gre_protocol *proto;
+	const struct iphdr *iph = (const struct iphdr *)skb->data;
+	u8 ver = skb->data[(iph->ihl<<2) + 1]&0x7f;
+
+	if (ver >= GREPROTO_MAX)
+		return;
+
+	rcu_read_lock();
+	proto = rcu_dereference(gre_proto[ver]);
+	if (proto && proto->err_handler)
+		proto->err_handler(skb, info);
+	rcu_read_unlock();
+}
+
+static const struct net_protocol net_gre_protocol = {
+	.handler     = gre_rcv,
+	.err_handler = gre_err,
+	.netns_ok    = 1,
+};
+
+static int __init gre_init(void)
+{
+	pr_info("GRE over IPv4 demultiplexor driver");
+
+	if (inet_add_protocol(&net_gre_protocol, IPPROTO_GRE) < 0) {
+		pr_err("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@mail.ru)");
+MODULE_LICENSE("GPL");
+